ABSTRACT Geographical Region Summary Service for Geographical Routing

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英语作文介绍一下中国地理位置

中国地理位置简介Nestled in the heart of East Asia, China occupies a pivotal position in the world's geographical landscape. Bordering a diverse array of countries, China's strategic location has historically been a confluence of cultural, economic, and political exchanges.Surrounded by the Pacific Ocean to the east, thecountry extends westward into the vast Eurasian continent. To the north, China shares borders with Russia and Mongolia, while to the south, it abuts a string of nations including Vietnam, Laos, Myanmar, and more. This extensive border network not only defines China's territorial integrity but also shapes its unique geographical identity.Geographically, China can be divided into three major regions: the eastern coastal plain, the central hills and plateaus, and the western mountains and deserts. Theeastern region, rich in water resources and fertile soil, supports a dense population and is the economic heart ofthe country. The central region, characterized by rolling hills and diverse climates, is home to a range ofagricultural activities and cultural traditions. Thewestern region, with its vast mountains and deserts, isrich in natural resources and strategic minerals.The Yangtze River, the longest river in Asia, and the Huang He or Yellow River, China's second-longest, play a crucial role in the country's hydrology and agriculture. These rivers, along with other major waterways, form a dense network of waterways that facilitate trade and transportation throughout the country.China's geographical diversity also contributes to its diverse climate zones. The southern regions enjoy a subtropical climate with ample rainfall, while the northern regions experience a more temperate climate with colder winters. The western regions, especially those adjacent to the Tibetan Plateau, have a unique highland climate with distinct seasonal patterns.In terms of global positioning, China's geographical location places it at the crossroads of East and West, North and South. This strategic position has historically been a gateway for trade and cultural exchange, making China a natural hub for connectivity and integration within the Asian region and beyond.In conclusion, China's geographical position, encompassing a vast territory with diverse landscapes, climates, and borders, is not only a testament to its rich natural resources but also a catalyst for its cultural, economic, and political influence in the world. This unique geographical makeup continues to shape the country's development and influence in the global arena.**中国地理位置简介**中国位于东亚的心脏地带，在世界地理景观中占据着重要的位置。

英文介绍南京的地理位置作文

英文介绍南京的地理位置作文Introducing the Geographical Location of NanjingNestled in the eastern part of China, Nanjing, also known as Jinling, Jincheng, or Nanking, is a city steeped in history and culture. Geographically, Nanjing is situated in the central region of Jiangsu Province, bordering the Yangtze River to the north and the Taihu Lake Basin to the west. This strategic location has long made Nanjing a crucial transportation hub in China.Located at the intersection of the Yangtze River and the Grand Canal, Nanjing enjoys a convenient waterway system. The Yangtze River, one of the longest rivers in China, flows through the city, connecting Nanjing with the vast inland regions to the upstream and the economically prosperous Yangtze River Delta region to the downstream. Meanwhile, the Grand Canal, an ancient artificial waterway, links Nanjing to Beijing and Hangzhou, facilitating trade and cultural exchanges.From a geographical perspective, Nanjing also boasts a favorable climate. It belongs to the subtropical monsoon climate zone, characterized by four distinct seasons, withample sunshine and rainfall. This climate not only supports a diverse range of agricultural crops but also contributes to the city's lush vegetation and beautiful scenery.In addition, Nanjing is situated in a fertile plain, surrounded by mountains and rivers. To the south lies the Nanjing Plain, which is one of the most fertile agricultural areas in China. To the east and west are low mountains and hills, providing natural barriers and scenic landscapes.Moreover, Nanjing is geographically close to major cities in China, such as Shanghai, Hangzhou, and Hefei. This proximity has fostered close economic and cultural ties between Nanjing and these cities, contributing to Nanjing's status as an important urban center in eastern China.In summary, Nanjing's strategic location at the intersection of major waterways, its fertile plain, and its proximity to major cities have all contributed to its prominence as an economically and culturally significant city in China.。

语言学名词解释和问答题答案(只供参考)

四、名词解释：1)Parole话语：①it refers to the realization of langue in actual use.②it is the concrete use of the conventions and the application of the rules.③it is concrete, refers to the naturally occurring language events.④it varies from person to person, and from situation to situation.2)Applied linguistics应用语言学：findings in linguistic studies can often be applied tothe solution of such practical problems as recovery of speech ability. The study of such applications is known as applied linguistics.3)Reference（所指）语义: It means what a linguistic form refers to in the real, physicalworld, it deals with the relationship between the linguistic element and the non-linguistic world of experience.4)Illocutionary act言外行为：the act of expressing the speaker’s intention,it is th e actpreformed in saying something.5)Regional dialect地域方言：it is a linguistic variety used by people living in the samegeographical region. It has been found that regional dialect boundaries often coincide with geographical barriers such as mountains, rivers and swamps.6)LAD(Language Acquisition Device)语言习得机制：It was described as an imaginary"black box" existing somewhere in the human brain.7)CA（Contrastive Analysis）对比分析：starting with describing comparable featuresof the native language and the target language, CA compares the forms and meanings across these two languages to locate the mismatches or differences so that people can predict the possible learning difficulty learners may encounter.8)Neurolinguistics（神经语言学）：it is the study of two related areas：language disordersand the relationship between the brain and language. It includes research into how the brain is structured and what function each part of the brain performs, how and in which parts of the brain language is stored, and how damage to the brain affects the ability to use language.9)Predication analysis述谓结构分析：①It is proposed by the British Linguist G.Leech.②The basic unit is called predication, which is the abstraction of the meaning of a sentence.③This applies to all forms of a sentence.④ A predication consists of argument(s) and predicate.10)Cross-cultural communication(intercultural communication)跨文化交流：it iscommunication between people whose cultural perceptions and symbols systems are distinct enough to alter the communication event.11)Cross-association互相联想：In English we sometimes may come across words whichare similar in meaning. Their spelling and pronunciation are also alike. The close association of the two leads to confusion. Such interference is often referred as cross-association.12) CPH（Critical Period Hypothesis）临界期假说：a specific and limited time period for language acquisition.①The strong version of CPH suggests that children must acquire theirfirst language by puberty or they will never be able to learn from subsequent exposure.②The weak version holds that language learning will be more difficult and incomplete after puberty. (Support in Victor’s and Genie’s cases)13) Prescriptive（grammer）规定语法：if the linguistic study aims to lay down rules for "correct and standard " behaviour in using language to ell people what they should say and what they should not say, it is said to be prescriptive.14)Performance语言运用；言语行为：the actual realization of this knowledge in linguistic communication .15) Duality双重性(double articulation)：language is a system, which consists of two sets of structures, or two levels. The lower or basic level is of sounds, which are meaningless. The higher level can be meaningful.五、问答题：Chapter 11.How do you interpret the following definition of linguistics: linguistics is the scientific studyof language?Linguistics studies not any particular language,but it studies languages in general.It is a scientific study because it is based on the systematic investigation of linguistic data,conducted with reference to some general theory of language structure.In order to discover the nature and rules of the underlying language system, what the linguist has to do first is to collect and observe language facts,which are found to display some similarities ,and generalizations are made about them,then he formulates some hypotheses about the language structure .But the hypotheses thus formed have to be checked repeatedly against the observed facts to fully prove their validity.6. How is Saussure’s distinction between langue and parole similar to Chomsky’s distinctionbetween competence and performance?Both Saussure and Chomsky make the distinction between the abstract language system and the actual use of language. their purpose is to single out the language system for serious studyThey are similar in two aspects: the definition and the content of study.On one hand, Saussure defines langue as the abstract linguistic system shared by all the members of a speech community, and parole as the realization of langue in actual use. Chomsky definescompetence as the ideal user’s knowledge of the rules of his language, and performance the actual realization of this knowledge in linguistic communication. We can see that langue and competence both refer to the abstract issue, conventions and knowledge, and parole and performance both are their actual realization, the concrete use.On the other hand, in Saussure’s opinion, what linguists should do is to abstract langue from parole as parole is too varied and confusing. And this is the same as Chomsky. He thinks linguists should study t he ideal speaker’s competence, not his performance, which is too haphazard to be studied.Two linguists idea differ in that Saussure took a sociological view of language, Chomsky looks at language from a psychological point of view, competence is a property of the mind of each individual.8.What are the main features of human language that have been specified by C.Hockett toshow that it is essentially different from animal communication system?1)Arbitrariness:this means that there is no logical connection between meanings and sounds. Agood example is the fact that different sounds are used to refer to the same object in different language.2)Productivity:Language is productive in that it makes possible the construction andinterpretation of new signals of its users.3)Duality:language is a system, which consists of two sets of structures, or two levels. At thelower or the basic level there is a structure of sounds, which are meaningless. But the sounds of language can be grouped and regrouped into a large number of units of meaning, which are found at the higher level of the system.4) Displacement: Language can be use to refer to things which are present or not present, real orimagined matters in the past ,present or future, or in far-away places. In other words, language can be used to refer to contexts removed from the immediate situations of the speaker.5) Cultural transmission:Language is passed on from one generation to next through teaching andlearning rather than by instinct.Chapter 23.Explain with examples how broad transcription and narrow one transcription differ?Broad transcription—one letter symbol for one sound.Narrow transcription—diacritics are added to the one-letter symbols to show the finer differences between sounds.In broad transcription, the symbol [l] is used for the sound [l]8.what’s a phone? how is it different from a phoneme? how are allophones related to a phoneme?① A phone is a phonetic unit or segment. The speech sounds we hear and produce during linguistic communication are all phones. Phones do not necessarily distinguish meaning, some do, some don’t, e.g. [ bI:t ] & [ bIt ], [spIt] & [spIt].② A phoneme is a phonological unit; it is a unit of distinctive value; an abstract unit, not a particular sound, but it is represented by a certain phone in certain phonetic context, e.g. the phoneme /p/ can be represented differently in [pIt], [tIp] and [spIt].③Allophone—the phones that can represent a phoneme in different phonetic environments Phone is different from phoneme,The phoneme /l/ can be realized as dark/l-/and clear/l/,which are allophones of the phoneme /l/Chapter 51.What are the major views concerning the study of meaning?1)The naming theory命名论was proposed by the ancient Greek scholar Plato. The linguisticforms or symbols, in other words, the words used in a language are taken to be labels of theobjects they stand for; words are just names or labels for things. The semantic relationshipholding between words and things is the relationship of naming.2)The conceptualist view概念论: This view holds that there is no direct link between alinguistic form and what it refers to; rather, in the interpretation of meaning they are linkedthrough the mediation of concepts in the mind. This is best illustrated by the semantic trianglesuggested by Ogden and Richards:3)Contextualism语境论: Representatively proposed by the British linguist J. R. Firth who hadbeen influenced by the Polish anthropologist Malinowski and the German philosopherWittgenstein.It holds that meaning should be studied in terms of situation, use,context-elements closely linked with language behavior. …the meaning of a word is its use inthe language.4)Behaviourism行为主义论: Based on contextualist view by Bloomfield who drew onbehaviorist psychology in defining “meaning”. Behaviorists attempted to define the meaningof a language from as the “ situation in which the speaker utters it and the response it callsforth in the hearer.”This theory, somewhat close to contextualism, is linked withpsychological interest.6.In what way is componential analysis similar to the analysis of phonemes into distinctive features?成分分析和把音位分析为区别性特征有何相似之处？In the light of componential analysis, the meaning of a word consists of a number of distinctive meaning features, the analysis breaks down the meaning of the word into these features; it is these different features that distinguish word meaning similarly, a phoneme is considered as a collection of distinctive sound features, a phoneme can be broken down into these distinctive sound features and its these sound features that distinguish different sounds.Chapter 65. According to Austin, what are the three acts a person is possibly performing while making an utterance. Give an example.According to Austin's new model, a speaker might be performing three acts simultaneously when speaking: locutionary act, illocutionary act, and perlocutionary act.A locutionary act is the act of uttering words, phrases, clauses. It is the act of conveying literal meaning by means of syntax, lexicon and phonology. An illocutionary act is the act of expressing the speaker’s intention; it is the act performed in saying something. A perlocutionary act is the act performed by or resulting from saying something; it is the consequence of, or the change brought about by the utterance; it is the act performed by saying something. Let's look at an example:"You have left the door wide open."The locutionary act performed by the speaker is his utterance of the wo rds “you”, “have”, “door”,“open”, etc. thus expressing what the words literally mean.The illocutionary act performed by the speaker is that by making such an utterance he has expressed his intention of speaking, i.e. asking someone to close the door, or making a complaint, depending on the context.The perlocutionary act refers to the effect of the utterance. If the hearer gets the speaker's message and sees that the speaker means to tell him to close the door, the speaker has successfully brought about the change in the real world he has intended to; then the perlocutionary act is successfully performed.8. What are the four maxims of the CP? Try to give your own examples to show how flouting thesemaxims gives rise to conversational implicature?答：Cooperative Principle, abbreviated as CP. It goes as follows:Make your conversational contribution such as required at the stage at which it occurs by the accepted purpose or direction of the talk exchange in which you are engaged.To be more specific, there are four maxims under this general principle:(1) The maxim of quantity数量原则E.g. A: When is Susan's farewell party?B: Sometimes next month.It is flouting the maxim of quantity(2) The maxim of quality质量原则E.g. A: Would you like to join us for the picnic on Sunday?B: I'm afraid I have got a class on Sunday.(3) The maxim of relation相关原则E.g. A: How did the math exam go today, Tom?B: We had a basketball match with the other class.(4) The maxim of manner方式准则E.g. A: Shall we got something for the kids?B: Yes. But I veto I-C-E-C-R-E-A-M.Chapter92.What do you think of Sapir-Whorf hypothesis? Give examples or proof to support your point of view.Sapir-Whorf believe that language filters people's perception and the way they categorize their experiences. This interdependence of language and thought is now known as Sapir-Whorf Hypothesis. There are mainly two different interpretations about Sapir-Whorf Hypothesis: a strong version and a weak one. The strong version believes that language patterns determine people’s thinking and behavior, the weak one holds that the former influences the later.I agree with the weak one. Here is an example, the word snow. For Eskimo snow is extremely important and so crucial to life that each of its various forms and conditions is named. InEnglish-speaking cultures, snow is far less important and simple word snow usually suffices the need. When some needs become more specific, however, longer phrases can be made up to meet these needs: “corn snow”, “fine powder snow”, and “drifting snow”.Chapter102.Among the language acquisition theories mentioned in this chapter, which one do you think is more reasonable and convincing? Explain why.1)Behaviourist view---language is behavior ,language learning is simply a matter of imitation and habit formation.In this theory,imitation and practice are preliminary(开始),discrimination（识别）and generalizaition are key to language development.2)An innatist (语法天生主义者)view----In the human brain, there is an imaginary “black box”called Language acquisition device which is said to contain principles that are universal to all language.Children need access to the samples of a natural language to activate the LAD, which enables them to discover his language's structure by matching the innate knowledge of basic grammatical system to that particular ter Chomsky prefer this innate endowment as UG and hold that if children are pre-equipped with UG, then what they have to learn is the ways in which their own language make use of these principles and the variations in those principles which may exist in the particular language they are learning.3) An interactionist(互动主义者)view----language develops as a result of the complex interplay,between the human characteristics of the child and the environment in which child develops. In a word,Behaviorists view sounds reasonable in explaining the routine aspects,the innatist accounts most reasonable in explaining children's acquiring complex system, and the interactionist description convincing in understanding how children learn and use the language appropriately from their environment.Chapter111、To what extent is second language learning similar to first language learning? Can you list some proof from your own learning experience?(please list your own experience.)The studies on the first language acquisition have influenced enormously those on the second language acquisition at both theoretical and pratical levels. Theoretically the new findings and advances in first language acquisition in learning theories and learning process are illuminating in understanding second language acquisition. The techniques used to collect and analyze data in first language acquisition also provide insights and perspectives in the study of second language acquisition. Just as Littlewood summarizes, the first language study has served as a backcloth for perceiving and undrerstanding new facts about second language learning.2.Try to observe yourself and pay attention to your own learning experience, what conclusion can you reach about the role of Chinese in your English learning? On what occasions are you more likely to use or depend on Chinese in learning and using English?Chinese plays an inseparable role in our English learning and people can't afford to ignore it. Hence, therole of Chinese in our English learning is worth careful examination. In addition, English learning have been influnenced by Chinese learning at both theoretical and practical levels. (1)Theoretically, the new findings and advanced in Chinese acquisition especially in learning theories and learning process are illuminate (helping) in understanding English acquisition.(2)The techniques used to collect and analyze data in Chinese learning also provides insights and perspectives in the study of English learning. Occasion: Recent studies have discovered that there are three interacting factors in determining language transfer in second language learning:1)a learner's psychology, how a learner organizes his or her native language;2)a learner's perception of native-target language distance,3)a learner's actual knowledge of the target language.。

描述中国的地理位置英语作文

描述中国的地理位置英语作文China's Geographical Position: A Captivating ExplorationChina, the world's most populous country and the fourth-largest by total area, boasts a captivating and diverse geographical landscape that has captivated the minds of people across the globe. Situated in the heart of East Asia, China's strategic location has played a pivotal role in shaping its rich history and cultural heritage. From the towering Himalayan peaks to the vast expanses of the Gobi Desert, the country's geographical features are as breathtaking as they are diverse.At the heart of China's geographical position lies its vast landmass, which spans from the Pacific Ocean in the east to the Tibetan Plateau in the west. This expansive territory encompasses a wide range of landscapes, including lush tropical rainforests, arid deserts, snow-capped mountains, and sprawling grasslands. The country's diverse topography has given rise to a wealth of natural resources, which have been instrumental in fueling China's rapid economic growth and development.One of the most striking features of China's geographical position isits proximity to the Pacific Ocean. The country's eastern coastline, which stretches for over 14,500 kilometers, is dotted with bustling port cities and thriving economic hubs. These coastal regions have played a crucial role in China's integration with the global economy, serving as gateways for international trade and investment.Beyond its coastal regions, China's geographical position is defined by its landlocked borders, which share boundaries with 14 other countries. This strategic location has made China a hub of regional and global geopolitical influence, with the country's policies and actions having far-reaching implications for its neighbors and the international community.One of the most significant aspects of China's geographical position is its proximity to the Himalayan mountain range, which forms the country's western border. The Himalayas, often referred to as the "Roof of the World," are a formidable natural barrier that have played a crucial role in shaping China's history and culture. The region's harsh climate and rugged terrain have long been a source of both fascination and challenge for explorers and adventurers alike.China's geographical position has also been shaped by its vast river systems, which have played a central role in the country's agricultural and economic development. The Yangtze River, the world's third-longest river, flows through the heart of China, while the Yellow River,often referred to as the "Mother River of China," has been a crucial source of life and sustenance for the country's people for thousands of years.The country's diverse geographical features have also given rise to a rich tapestry of cultural traditions and practices. From the ancient Silk Road trade routes that connected China to the West, to the intricate system of canals and waterways that have facilitated domestic trade and transportation, the country's geography has been a driving force behind its cultural and economic development.In conclusion, China's geographical position is a complex and multifaceted phenomenon that has played a crucial role in shaping the country's history, culture, and economic development. From its vast landmass and diverse landscapes to its strategic location at the heart of East Asia, China's geographical features have captivated the minds of people around the world and continue to be a source of fascination and wonder.。

英语词汇学200要点(不过都难啊!)

1.外来词分为四类：1 Denizens ,cup from cuppa , port form portus 2) Aliens garage , décor 3) Translation –loans e.g. long time no see 4) Semantic- loans.e.g. dream.2.Motivation 分类：onomatopoeic motivation, morphological motivation, semantic motivation, etymological motivation. Types of meaning: grammatical ~ & lexical ~; conceptual ~& associative ~(connotative~, stylistic~, affective ~, collocative ~,)多义关系及两种研究方法:Polysemy is a common feature peculiar to all natural language that one word has two or more senses or meanings. Diachronic approach is an approach to polysemy which studies how a word derived its different meanings from its primary meaning in the course of time.3.Synchronic approach is an approach to polysemy which studies the coexistence of various meanings of the same word in a certain historical period of time.4.Primary meaning is the only meaning that a word had when it was first created.5.Derived meanings are the meanings that a word gets from the primary meaning at different stages of its development in the course of time.6.同形同音异义关系Homonymy is one of the features of words that a word is different in meaning from another, but either identical both in sound and spelling or identical only in sound or spelling with the other Homonyms generally fall into three classes: perfect homonyms (same name); homographs (same spelling) and homophones （some sound）. Perfect homonyms are those words identical both in sound and spelling, but different in meaning, e.g. bear /bea/ (n) a large heavy animal; bear /bea/ (v) to put up with. Homographs are the words identical only in spelling but different in sound and meaning, e.g. saw / / (v) to scatter seeds; sow /sau/ (n) female adult pig. Homophones refer to the words identical only in sound but different in spelling and meaning, e.g. dear /dia/ (n) a loved person; deer /dia/ (n) a kind of animal.7.同形同音异义词与多义词的区别Perfect homonyms and polysemants are fully identical with regard to spelling and pronunciation. This creates the problem of differentiation. The fundamental difference between homonyms and polysemants lies in the fact that the former refers to different words which happen to share the same form and the latter is the one and same word which has several distinguishable meanings. One important criterion is to see their etymology, i.e. homonyms are from different sources whereas a polysemant is from the same source which has acquired different meanings in the course of development. The second principal consideration is semantic relatedness. The various meanings of a polysemant are correlated and connected to one central meaning to a greater or lesser degree, e. g. neck (See 6.1 Polysemy) . On the other hand, meanings of different homonyms have nothing to do with one another. In dictionaries, a polysemant has its meanings all listed under one headword whereas homonyms are listed as separate entries.8.同义关系Synonyms are words which share the same or nearly the same meaning with each other but different in sound and spelling. There are absolute synonyms and relative synonyms which result from borrowing, dialects and regional English, figurative and euphemistic use of words, coincidence with idiomatic expressions. There exists the difference between or among synonyms in terms of their denotation, connotation or application. Absolute synonyms or complete synonyms are words which are identical in meaning in all its aspects. Relative synonyms or near-synonyms are similar or nearly the same in denotation, but embrace different shades of meaning or different degrees of a given quality.9.Sources of Synonyms 1) Borrowing 2)Dialects and regional English 3) Figurative and euphemistic use of words 4) Coincidence with idiomatic expressions10.如何区分同义词？1Difference in denotation2 Difference in connotation 3 Difference in application11.What are the characteristics of antonyms?12.1) Antonyms are classified on the basis of semantic opposition 2) A word which has more than one meaning can have more than one antonym. 3) Antonyms differ in semantic inclusion. 4) Contrary terms are gradable antonyms, differing in degree of intenisty, so each has its own corresponding opposite.13.上下义关系:Hyponymy deals with the relationship of semantic inclusion. That is, the meaning of a more specific word is included in that of another more general word. Superordinates refer to some general words; subordinates denote those more specific words. Hyponymy can be described in terms of tree-like graphs, with higher-order superordinates above the lower subordinates. But their status either as superordinate or subordinate is relative to other terms. Forexample, horse, dog, pig are subordinates in relation to animal, but superordinates of mare, hound and boar, Animal itself becomes a subordinate of creature. And creature in turn becomes14.词义变化的种类There are five types of meaning, changes: extension, narrowing, degradation, elevation, and transfer among which extension and narrowing are the most common. Changes in meaning can be accounted for from extra-linguistic factors (historical reason, class reason, and psychological reason) and intra-linguistic factors (shortening, the influx of borrowing, and analogy).15.词义的扩大Extension is a process by which a word with a specialized sense is generalized to cover a broader or less16.definite concept. Compare the following；词义的缩小Narrowing is a process by which a word of wider meaning acquires a specialized sense；词义的升华Elevation is a process by which a word moves from a derogatory or neutral sense to a neutral and/or appreciative sense；词义的降格Degradation is a process by which a word of reputation slides into a pejorative use,；词义的转移Transfer is a process by which a word denoting one thing changes to refer to a different but related thing. Paper serves as an example. This word formerly denoted an African plant papyrus, which was once used to make paper. In modern times, paper is made from rags, wood, straw and the like, but the product has retained the same name. There is associated transfer. There are other kinds of transfer, such as, concrete to abstract, abstract to concrete and transfer of sensation.17.语境的种类:非语言语境。

地理位置介绍英语介绍

地理位置介绍英语介绍Location IntroductionIntroduction:Geographical location plays a significant role in understanding a place's unique characteristics, cultural diversity, and socio-economic factors. In this article, we will delve into the description of a fascinating location - its geographic features, climate, and cultural aspects, providing readers with a comprehensive understanding of the place.I. Geographic Features:Situated in [Location], surrounded by [neighboring regions], [Place] boasts a rich and diverse geographical landscape. It is characterized by [topography, landforms, natural landmarks, etc.]. The region's breathtaking scenery includes [specific geographical features, such as mountains, rivers, valleys, or coastlines].Furthermore, [Place] serves as a home to abundant wildlife, with numerous species of flora and fauna flourishing in its lush green forests and expansive national parks. Welcoming hikers and nature enthusiasts alike, [Place] invites visitors to explore its picturesque trails, capturing the essence of its awe-inspiring environment.II. Climate:The climate of [Place] is influenced by various factors, resulting in its distinct climatic conditions. [Place] experiences [climate type], characterized by [temperature range, precipitation patterns, etc.]. Summers are generally[adjective] and winters tend to be [adjective], providing residents and visitors with diverse seasonal experiences.The moderate climate of [Place] makes it suitable for various outdoor activities throughout the year. Whether it is swimming in crystal-clear lakes during summers or embracing snowy adventures in winters, the region offers something for everyone, catering to different preferences and interests.III. Cultural Aspects:Beyond its geographical allure, [Place] is also known for its vibrant culture, which is deeply rooted in the heritage and traditions of its people. The region is a melting pot of different ethnicities, resulting in a harmonious blend of customs, languages, and festivals.The local cuisine is an integral part of [Place]'s cultural scene. Visitors have the opportunity to savor an array of delectable dishes, ranging from traditional delicacies to international cuisines. Through food, one can truly experience the flavors and authenticity of [Place]'s culinary traditions.Moreover, [Place] is dotted with historical landmarks, architectural marvels, and museums that showcase its rich history and cultural significance. These attractions provide insights into the past, allowing visitors to explore the story behind [Place]'s progression and preservation over the years.Conclusion:In summary, [Place] offers a captivating mix of geographical wonders, favorable climate, and a rich cultural tapestry. Its natural beauty coupled with its diverse traditions and customs make it an appealing destination fortravelers seeking an immersive experience. Whether exploring its unique topography or embracing the warmth of its people, [Place] is undoubtedly an intriguing location with much to offer to both locals and tourists alike.(Note: This 505-word article provides a detailed introduction to a location's geographical features, climate, and cultural aspects. Please feel free to expand its word count according to your requirements.)。

英语作文介绍自己喜欢的城市重庆

英语作文介绍自己喜欢的城市重庆全文共3篇示例，供读者参考篇1My Beloved Chongqing: A Metropolis Like No OtherChongqing, the mountain city that stole my heart – a place where ancient traditions embrace modern marvels, creating an urban tapestry that leaves an indelible mark on all who visit. As a student hailing from this vibrant metropolis, I can't help but beam with pride when reflecting upon its unique charm and richness.Perched majestically upon the confluence of the Yangtze and Jialing Rivers, Chongqing's GeographyChongqing's geography is nothing short of awe-inspiring. The city's landscape is a breathtaking amalgamation of towering skyscrapers and lush, verdant hills that seem to embrace the urban sprawl. The winding rivers that snake through the city act as arterial lifelines, lending a certain rhythm and flow to daily life. It's not uncommon to witness locals navigating the waterways in traditional wooden boats, a scene that harkens back to a bygone era.As you wander the streets, you can't help but marvel at the juxtaposition of old and new. Centuries-old temples and pavilions stand in silent reverence amidst a sea of modernhigh-rises, each vying for dominance in the ever-changing skyline. It's a constant reminder of Chongqing's resilience and ability to evolve while still cherishing its storied past.A Culinary WonderlandIf there's one thing that defines Chongqing in my mind, it's the food. As a self-proclaimed foodie, I've lost count of the number of times I've found myself entranced by the intoxicating aromas wafting from local eateries. Chongqing's cuisine is a gastronomic symphony, a harmonious blend of fiery Sichuan spices and subtle, nuanced flavors that linger on the palate long after the last bite.From the iconic hot pot, where diners gather around simmering cauldrons of mouth-numbing broth, to the humble yet delectable xiaomian (Chongqing-style noodles), every dish is a testament to the city's rich culinary heritage. And let's not forget the legendary hongyu (braised fish), a dish so beloved that it's practically a religion unto itself.A Bustling Cultural HubChongqing's cultural tapestry is as vibrant and diverse as its cuisine. As a student, I've had the privilege of immersing myself in a city that seamlessly blends traditional arts with cutting-edge modernity.The Ciqikou Ancient Town, a bastion of preserved architectural gems, transports visitors back in time with its narrow alleyways and charming teahouses. Yet, just a stone's throw away, you'll find yourself in the heart of Jiefangbei, a neon-drenched commercial district that pulses with youthful energy and trendy boutiques.Art enthusiasts like myself are spoiled for choice, with world-class museums and galleries showcasing everything from ancient calligraphy to avant-garde installations. The Chongqing Museum, in particular, is a treasure trove of historical artifacts and cultural relics that offer a glimpse into the city's storied past.A Warm and Welcoming PeopleBut perhaps the most endearing aspect of Chongqing is its people. Known for their warmth, wit, and unwavering hospitality, the locals have a way of making you feel like you're part of one big family.Whether it's the affable vendor who greets you with a beaming smile or the kind-hearted elderly woman who insists on offering you a seat on the crowded bus, the people of Chongqing embody a spirit of generosity and camaraderie that is truly infectious.And let's not forget the unique dialect – a melodic blend of Mandarin and local vernacular that adds an extra layer of charm to everyday conversations. As a student, attempting to master the intricacies of the Chongqing dialect has been both a challenge and a delight, a constant reminder of the city's rich linguistic heritage.A City of Contrasts and Endless DiscoveriesChongqing, in many ways, is a city of contrasts – a place where the ancient and modern collide in a kaleidoscope of sights, sounds, and flavors. Yet, it's precisely this juxtaposition that makes the city so captivating.As a student, I've had the privilege of witnessing Chongqing's transformation firsthand, watching as it evolves from a once-forgotten inland city into a global metropolis brimming with opportunity and potential. With each passing day, I uncover new facets of this enigmatic place, peeling back layers of history and culture that leave me in awe.Whether it's exploring the labyrinthine alleyways of a centuries-old neighborhood or marveling at the architectural wonders of the city's ever-growing skyline, Chongqing never fails to surprise and delight. It's a place that challenges preconceptions and defies expectations, a true embodiment of the old adage, "expect the unexpected."For me, Chongqing is more than just a city; it's a way of life, a tapestry woven from threads of tradition, modernity, and an indomitable spirit that refuses to be defined by boundaries or conventions. It's a place that has captured my heart and soul, and I can't help but feel a sense of pride and belonging whenever I walk its streets.As I look towards the future, I know that Chongqing will continue to evolve and grow, embracing change while honoring its roots. And as a student of this great city, I feel a responsibility to carry its spirit forward, to be an ambassador of its rich culture and traditions, and to share its unique charm with the world.Chongqing, my beloved mountain city, you have captured my heart and ignited my soul. I can only hope that others will have the opportunity to experience your magic and fall under your spell, just as I have.篇2My Favorite City: The Vibrant and Captivating ChongqingAs a student passionate about exploring new cultures and embracing diverse experiences, I have had the privilege of visiting numerous cities across China. However, one city that has truly captured my heart and left an indelible mark on my soul is the mesmerizing Chongqing. Located in the southwestern region of the country, this metropolis is a captivating blend of modernity and tradition, offering a unique tapestry of sights, sounds, and flavors that have forever etched themselves into my memory.Nestled amidst the majestic embrace of the Yangtze and Jialing Rivers, Chongqing's geographical location is nothing short of breathtaking. The city's skyline is adorned with towering skyscrapers that seem to pierce the heavens, juxtaposed against the undulating hills and verdant landscapes that surround it. This striking contrast between the urban and the natural is one of the city's most alluring features, creating a harmonious symphony that captivates the senses.One of the first things that struck me upon arriving in Chongqing was the sheer vibrancy of its streets. The bustlingalleyways, known as "longtang," are a labyrinth of narrow passages that wind their way through the heart of the city. These ancient thoroughfares are alive with the sounds of hawkers beckoning passersby, the aroma of sizzling street food wafting through the air, and the infectious energy of locals going about their daily lives. Navigating these intricate pathways is an adventure in itself, offering glimpses into the city's rich cultural tapestry and the warmth of its people.Chongqing's culinary scene is a true feast for the senses, and it was here that I discovered the fiery and flavorful delights of Sichuan cuisine. From the mouth-numbing sensation of the legendary hot pot to the intricate flavors of the region's famous "xiaomian" noodles, every bite was an explosion of taste that left me craving for more. The city's food stalls and restaurants are more than just eateries; they are vibrant hubs of social interaction where locals gather to share stories, laughter, and the unifying power of a good meal.Beyond its gastronomic delights, Chongqing is a city steeped in history and cultural heritage. The region's fascinating past as a wartime capital during World War II has left an indelible mark on its architecture and museums. The Chongqing China Three Gorges Museum, with its incredible exhibits andinteractive displays, offered me a profound understanding of the city's role in shaping China's modern history. Wandering through its halls, I was transported back in time, immersing myself in the struggles,篇3My Favorite City: The Vibrant and Unique ChongqingAs a student who has had the opportunity to travel and experience various cities, I can confidently say that Chongqing stands out as one of my absolute favorites. This city, nestled in the southwestern part of China, is a fascinating blend of ancient history, modern development, and breathtaking natural beauty. From its iconic skyline to its delectable cuisine, Chongqing has captivated my heart and soul in a way that few other places have.Perched on the banks of the mighty Yangtze River, Chongqing's geographical location is nothing short ofawe-inspiring. The city is surrounded by a series of striking mountains and hills, creating a unique and dramatic landscape that seems almost surreal. As you navigate through the winding streets and alleyways, you can't help but be struck by the sheer verticality of the city, with buildings seeming to defy gravity as they cling to the steep slopes.One of the things that fascinate me the most about Chongqing is its rich history, which dates back over 3,000 years. The city has played a pivotal role in various dynasties and has witnessed numerous significant events throughout Chinese history. From the ancient Ba and Chu civilizations to its role as the temporary capital of China during World War II, Chongqing's past is deeply woven into its present-day fabric.As I wander through the city's historic districts, such as Ciqikou and Huguang Guild Hall, I am transported back in time. The narrow alleys, adorned with traditional architecture and quaint shops, offer a glimpse into a bygone era. The sound of mahjong tiles clacking together, the aroma of incense wafting through the air, and the sight of elderly locals sipping tea in tiny teahouses all contribute to an atmosphere that is both enchanting and authentically Chongqing.Yet, Chongqing is not just a museum piece stuck in the past. The city has undergone a remarkable transformation in recent decades, embracing modernity while preserving its unique character. One of the most striking examples of this is the Chongqing Chaotic Transmitting Terminal, a futuristic transportation hub that seamlessly blends cutting-edge architecture with traditional elements. The juxtaposition ofancient and modern is a constant theme throughout the city, creating a visually stunning and thought-provoking experience.Beyond its architectural marvels, Chongqing is also renowned for its incredible cuisine, which is a true feast for the senses. As a self-proclaimed foodie, I have been utterly captivated by the city's diverse and flavorful culinary offerings. From the fiery and numbing sensation of Chongqing hot pot to the delicate and delicious xiaolongbao (soup dumplings), every bite is a celebration of bold flavors and time-honored traditions.One of my fondest memories is exploring the bustling night markets, where the air is thick with the tantalizing aromas of sizzling skewers, freshly grilled fish, and an array of mouthwatering street foods. The energy and liveliness of these markets are infectious, and I found myself drawn into the vibrant atmosphere, mingling with locals and savoring every bite.Of course, no discussion of Chongqing would be complete without mentioning its iconic bridges. The city is home to an impressive collection of bridges spanning the Yangtze River and its tributaries, each one a feat of engineering and a testament to human ingenuity. From the imposing Chaotianmen Bridge to the graceful Caiyuanba Bridge, these structures not only servepractical purposes but have also become iconic symbols of the city's resilience and progress.Beyond its urban delights, Chongqing also offers a gateway to some of China's most breathtaking natural wonders. Just a short drive from the city center, you can find yourself immersed in the lush greenery of national parks and nature reserves, such as the Wulong Karst National Geology Park and the Dazu Rock Carvings. These destinations provide a much-needed respite from the bustling city life, offering opportunities for hiking, camping, and simply reconnecting with nature.As I reflect on my experiences in Chongqing, I am struck by the city's ability to seamlessly blend tradition and modernity, creating a unique and captivating atmosphere that is trulyone-of-a-kind. From its rich cultural heritage to its culinary delights, from its architectural marvels to its natural wonders, Chongqing is a city that constantly surprises and delights.Whether you're a history buff, an architecture enthusiast, a foodie, or simply someone seeking an authentic and immersive cultural experience, Chongqing has something to offer. It is a city that challenges preconceptions, defies expectations, and leaves an indelible mark on the hearts and minds of all who visit.For me, Chongqing will always hold a special place in my heart. It is a city that has not only captivated my senses but has also opened my eyes to the incredible diversity and richness of Chinese culture. As I continue on my academic journey, I carry with me the memories and experiences I've had in this vibrant city, knowing that they have shaped me in ways I may never fully understand. Chongqing is truly a gem, a city that deserves to be celebrated and cherished for its unique and multifaceted charms.。

陕西地理介绍英语作文

陕西地理介绍英语作文English:Located in the northwest region of China, Shaanxi Province is surrounded by mountains on three sides and the Yellow River flows through the northern part of the province. Shaanxi has a diverse terrain, including the Loess Plateau in the north and the Qinling Mountains in the south. The Qinling Mountains serve as a natural boundary between the north and south of China. The province experiences a temperate semi-arid climate with distinct four seasons. Shaanxi is known for its rich history and cultural heritage, being the birthplace of ancient Chinese civilization. The province is home to many historical sites, such as the Terracotta Army in Xi'an, the ancient capital of 13 dynasties. Shaanxi also boasts unique local cuisine, including famous dishes such as biang biang noodles and roujiamo. Additionally, the province is a hub for traditional Chinese medicine, with many renowned practitioners and schools of medicine located in the region. Shaanxi's geographical diversity, historical significance, and cultural contributions make it a fascinating destination for both domestic and international tourists.中文翻译:陕西省位于中国西北地区，三面环山，黄河流经省北部。

介绍湖南地理位置英语作文

介绍湖南地理位置英语作文Hunan Province: A Geographical Gem in Central ChinaNestled in the heart of China, Hunan Province is a captivating region that boasts a rich tapestry of natural beauty, cultural heritage, and economic dynamism. As one of the country's most diverse and multifaceted provinces, Hunan's strategic geographical location has played a pivotal role in shaping its unique identity and vibrant development.Situated in the south-central part of China, Hunan is bordered by the provinces of Hubei to the north, Jiangxi to the east, Guangdong to the southeast, Guangxi to the southwest, and Chongqing to the west. This central positioning grants Hunan a strategic advantage as a vital transportation and economic hub, connecting the eastern coastal regions with the western interior. The province's diverse terrain, ranging from towering mountain ranges to lush river valleys, further enhances its geographical significance.One of the defining features of Hunan's geography is its mountainous landscape. The Wuling, Xuefeng, and Nanling mountain ranges dominate the province's western and southernregions, creating a stunning natural tapestry of towering peaks, deep gorges, and serene valleys. These majestic mountains not only provide breathtaking scenery but also play a crucial role in regulating the province's climate and hydrology.The Yangtze River, one of the world's mightiest waterways, flows through the northern part of Hunan, while the Xiang River, a major tributary of the Yangtze, meanders through the heart of the province. These vast river systems have been the lifeblood of Hunan, sustaining its thriving agricultural sector, supporting its bustling river-based transportation network, and nurturing the rich biodiversity that thrives along their banks.Hunan's diverse geography has also given rise to a remarkable array of natural resources, including abundant mineral deposits, fertile farmlands, and vast forests. The province's rich mineral wealth includes deposits of coal, iron ore, copper, and rare earth elements, which have fueled the growth of its industrial sector. Hunan's agricultural heartland, with its temperate climate and nutrient-rich soil, is renowned for its production of rice, tea, citrus fruits, and a variety of other cash crops.Beyond its natural resources, Hunan's strategic location has also played a pivotal role in shaping its cultural and historical development. As a gateway between the north and south, theprovince has long been a hub of cultural exchange and cross-pollination. The region's rich heritage is reflected in its renowned cuisine, which blends the flavors of Cantonese, Sichuan, and Huaiyang culinary traditions, as well as its vibrant folk arts, such as the iconic Xiang embroidery and the captivating Hunan opera.The province's geographical advantages have also contributed to its economic prominence within China. Hunan's well-developed transportation infrastructure, including an extensive network of highways, railways, and airports, has facilitated the efficient movement of goods and people, fostering the growth of industries ranging from manufacturing and energy to tourism and high-tech sectors.In recent years, Hunan has emerged as a key player in China's ambitious Belt and Road Initiative, a global infrastructure development project aimed at enhancing connectivity and trade across Asia, Europe, and Africa. The province's central position and robust transportation links have positioned it as a crucial node in this vast network, further solidifying its role as a strategic economic hub.As Hunan continues to harness its geographical advantages, the province is poised to play an increasingly significant role in China's ongoing economic transformation and development. From its towering mountains and winding rivers to its thriving cities andvibrant cultural landscape, Hunan's unique geographical identity has been the driving force behind its remarkable progress and the key to its promising future.。

介绍成都地理位置英语介绍

介绍成都地理位置英语介绍Chengdu's Geographical Location: An IntroductionLocated in the southwestern part of China, Chengdu, the capital city of Sichuan Province, encompasses an area of approximately 14,291 square kilometers. Renowned for its rich history, vibrant culture, and beautiful landscapes, Chengdu stands as a significant economic, cultural, and transportation hub in the region. In this article, we will explore the geographical location of Chengdu, focusing on its coordinates, neighboring provinces, climate, and geographical features.Coordinates:Chengdu is situated between longitude 102°54′49″E and latitude30°04′23″N. It is positioned on the western edge of the Sichuan Basin, which makes it a strategic location connecting the vast Chengdu Plain and surrounding mountainous areas. Its central location within China provides great accessibility and connectivity to other major cities and provinces.Neighboring Provinces:Chengdu is surrounded by several provinces, each offering its own unique attractions and cultural heritage. To the north, lies the vast expanse of Shaanxi Province with its historical treasures such as the Terracotta Army in Xi'an. Sichuan's southern neighbor is the captivating Yunnan Province, known for its picturesque landscapes, ethnic diversity, and the legendary Shangri-La. To the east of Chengdu lies Chongqing, a central metropolis with its own distinctive culture and cuisine. Finally, Tibet, often referred toas the "Roof of the World," is located to the west of Chengdu, offering breathtaking natural beauty and spiritual experiences.Climate:Chengdu experiences a humid subtropical climate with four distinct seasons. The city is known for its mild and comfortable temperatures throughout the year. Spring, starting from March to May, brings blooming flowers and moderate temperatures, making it an ideal time to visit. Summer, from June to August, is characterized by occasional rainfall and temperatures averaging around 26 to 30 degrees Celsius. Autumn, from September to November, is known for its pleasant weather, clear skies, and beautiful foliage. Winter, occurring from December to February, tends to be mild with average temperatures around 5 to 10 degrees Celsius. Overall, Chengdu's climate offers a balance, allowing residents and visitors to enjoy a diverse range of activities year-round.Geographical Features:Chengdu is nestled within the fertile Chengdu Plain, often referred to as the "Land of Abundance." The Minjiang River, Jinjiang River, and Tuojiang River flow through the city, providing abundant water resources and contributing to the area's agricultural productivity. The nearby Qingcheng Mountain, one of the birthplaces of Taoism, and the majestic Mount Emei, a UNESCO World Heritage Site, showcase the region's stunning natural beauty. The city's geography is also characterized by low-lying hills, which provide a picturesque landscape and serve as popular recreational spots for locals and tourists alike.Conclusion:Chengdu's geographical location not only contributes to its historical significance and cultural prominence but also provides a favorable environment for economic growth and tourism. With its strategic coordinates, neighboring provinces, pleasant climate, and captivating geographical features, Chengdu continues to attract domestic and international visitors, opening up opportunities for cultural exchange and economic development.。

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Geographical Region Summary Service for Geographical Routing∗†Pai-Hsiang HsiaoHarvard University33Oxford Street,Cambridge,MA02138shawn@ABSTRACTIn a network consists of wireless mobile nodes,routing with ge-ographical information is more efﬁcient and scalable than meth-ods that only rely on node connectivities.Geographical routing requires a distributed location dissemination or location database system to provide forwarding location.In this paper,we propose a novel location dissemination system called“Geographical Region Summary Service”(GRSS).Mobile nodes in GRSS proactively dis-seminate aggregated forwarding locations as a summary of node IDs in a deﬁned region.This summary propagates to other regions and updates stale summaries.Each node in the network knows the exact location of every other node,or the region it resides in.Packet forwarding decisions can be made independently at each node. We introduce the system and algorithm,also summarize some ﬁndings from our simulation results in this paper.1.INTRODUCTIONRouting with geographical information is a solution for efﬁcient and scalable routing in a mobile wireless network[4].Routing with geographical information works as follows:when a node receives a packet that is bounded to the other node,it looks up the forward-ing location of the destination node,chooses a neighboring node that is closer to the forwarding location and forwards the packet to the neighbor.Geographical routing algorithms are localized,the participating nodes store only local information,such as neighbor locations,and use them to make forwarding decisions.This local-ized property is the key to success because of the reduced local states and routing protocol overhead.However,geographical rout-ing faces two challenging problems.First,its greedy nature fails to route a packet when the only route to a forwarding location is through nodes that are further away from the location rather than the closer ones.There have been several This research was supported in part by the Air Force Ofﬁce ofScientiﬁc Research Multidisciplinary University Research Initia-tive Grant F49620-97-1-0382and as well as Microsoft Research, Nortel,and Sun Microsystems.†A full version of the paper is available at /˜shawn/GRSS/.solutions for this problem[2][6].In a dense network,this problem is unlikely to happen[7].Second,it requires an auxiliary service to retrieve the forwarding location of the destination node—ge-ographical routing is a mechanism that carries out the step of for-warding a packet,but in order to do so,it requires a method to learn the forwarding location.For routing purpose,the forwarding loca-tion needs not be very accurate because node may be moving and the location is only used as a forwarding hint.We note that a poorly designed location retrieval system will cancel out the advantages of geographical routing.There are two classes of methods to make forwarding locations available to assist routing.The major distinction between them is the location retrieval mechanism.Theﬁrst method is through a location database system,the second one is through a location dis-semination system.In a location database system,every node elects one or more other nodes in the network as its location database servers.These database servers are being updated proactively.On the other hand,in a location dissemination system,a node will an-nounce its forwarding location proactively to all the others.Ev-ery node in this system will receive the location updates from the others,and will be able toﬁnd the forwarding locations of them from its own location table.A location dissemination system can be treated as a special case of a location database system,where every node in the network is a location database server for all the others.These two methods have different properties and will inﬂu-ence the routing mechanism that utilizes the location information. There are trade-offs between the two classes of methods on the number of states kept per node and the complexity of retrieving the locations.In this paper,we propose a distributed algorithm to build a location dissemination system called Geographical Region Summary Service(GRSS).GRSS is different from existing work in that,forwarding locations are aggregated to increase the system’s efﬁciency and scalability.The paper is organized as follows.We begin by introducing the system in Section2,then describe our algorithms in Section3.Section4includes our conclusions and future work.2.GRSS SYSTEM OVERVIEW2.1Network SettingsWe are interested in wireless data networks such as ad hoc mo-bile wireless networks[5]or Rooftop networks[8].Packets are delivered in these networks through multiple wireless hops.Nodes in the networks could be mobile or stationary in any period of time. All of them are participating in the routing of the network,i.e.,they will deliver packets for the others using some geographical routing algorithms.Each node in the network canﬁnd out their own lo-cation either via GPS devices or other means.We assume certainFigure1:An example of GRSS network.(a)The origin and extent of the network.(b)The entire network is divided into 4by4order-0squares numbered from1to16.Four sibling order-0squares form an order-1square.(c)The four order-1 squares A,B,C,D form an order-2square,which covers the entire network.node densities,such that not only for geographical routing but also the summary generation and propagation can work well.The wire-less data communications in the networks are via two-way radios such as IEEE802.11.To enable GRSS in such a network,the geographical area of the network must be divided into a grid with small squares.To divide the area into small squares,the origin and extent of this area must be known by all nodes in the network.An example of such network is shown in Figure1(a).In addition,a size of order-0square is given.This size is used to divide the area into order-0squares.Asshown in Figure1(b),we use the size of order-0square as14ofthe network extent and divides the covered area into16squares. We can deﬁne node residency with these order-0squares.A node resides in exactly one order-0square at a time.We say a node resides in a square,if its location is inside the boundary of that order-0square.2.2Location Dissemination using Summary GRSS constructs a hierarchical infrastructure starting from these order-0squares for the purpose of generating and disseminating summaries.This hierarchical infrastructure contributes efﬁciency and scalability to our system.Similar to the grid system in GLS[7],this infrastructure con-sists of overlapping squares with different orders and sizes.GRSS uses adjacent lower-order squares to form higher-order squares.A higher-order square covers several unique lower-order squares,thus its size is larger than a lower-order square.In particular,four unique sibling order-(i−1)squares form an order-i square—as shown in Figure1(b),four sibling order-0squares(1,2,3,4)form an order-1square;in Figure1(c),four sibling order-1squares(A,B, C,D)form an order-2square.We use“adjacent square”to refer to a square that is adjacent to another one,and“sibling square”if it is also covered by the same one higher-order square.The greatest-order square of the network is the least-order square with a size can cover the entire network.We can locate a node in a region with exactly one square of any order.For example,if a node’s location is the origin,we can locate it using order-0square“1”or order-1square“A”.To bootstrap the summary generation,nodes residing in the same order-0square use a local routing protocol to exchange their loca-tions and neighboring node lists with each other.The ultimate goal is for every node to know the exact paths to all the other nodes in the same order-0square.Nodes that are close enough to the bound-aries will also receive routing messages from neighboring nodes in the adjacent squares.These nodes are called“boundary nodes”and will be responsible for sending summary update messages to adja-cent squares.Every boundary node in an order-0square generates asummary Figure2:An example of geographical routing with GRSS. There are four orders of squares in the network.(1)Packet is being forward to the center of the order-2square the des-tination node reside in;(2)packet is being forwarded to the center of the order-1square the destination node reside in;(3) the intermediate node resides in the same order-0square with the destination node.about the nodes in the square and sends it as a summary update message to other sibling order-0squares.The summary includes IDs of all known nodes in the square.For instance,in Figure1(b), boundary nodes in order-0square“1”send summary update mes-sages to square“2”,“3”,and“4”.Every node now knows exact paths to all the other nodes in the same order-0square by the local routing protocol and has sum-maries of the other three sibling order-0squares.Some boundary nodes in the order-1square can then generate summaries of the order-1square and send it to sibling order-1squares.The procedure continues recursively until the greatest-order square is reached.Ev-ery node resides in squares of different orders and thus receives summary update messages from sibling squares of different orders. For a node,the union of all received summaries covers the entire network except the order-0square it resides in.For example,in Figure1(b)and Figure1(c),a node resides in the order-0square6 receives summaries from order-0squares5,7,8,and order-1square A,C,D.The union of these summaries covers the network except the square6.2.3Geographical Forwarding using Summary In GRSS,a node has some knowledge about the forwarding lo-cations of all the other nodes in the network—either by the local routing protocol if nodes are local(in the same order-0square)or by looking up summaries.The summary describes a node in a spe-ciﬁc region instead of the exact location,so the center of the square will be used as its forwarding location.An intermediate node can make packet forwarding decision with the destination node ID.If the destination node is a local node,the exact path to it is known by the node,and the packet can be for-warded accordingly;otherwise,the intermediate node forwards the packet towards the center of the least-order square whose summary includes the destination node.We show a running example in Fig-ure2.The source or intermediate node that resides in the same order-i square(for i>0)with the destination node forwards the packet to the center of the square of order-(i−1),or less,that con-tains the destination node.This i decreases to0as the packet gets closer to the destination node.It is true when the packet is forwarded to the center of the square rather than the exact location,the total number of hops it travels may not be optimal.However,the difference between the distances from any location outside the square to these two locations inside the square are bounded by a fraction of the square size,thus we believe this limited difference will not affect the decisions of nexthop too much when performing geographical routing.3.ALGORITHMS3.1OverviewWe introduce the two major routing algorithms of the GRSS sys-tem in this section.Theﬁrst one is a link-state based local routing protocol for order-0squares,the second one is a sibling square up-dating algorithm for squares of all orders.We also describe the algorithm for generating summary,and discuss routing in the pres-ence of false positives.3.1.1Local Routing ProtocolTo exchange routing information within an order-0square,GRSS uses a link-state based routing protocol.The propagation of infor-mation is limited to two hops to avoid excessive trafﬁc and routing loops.However,this also limits the size of order-0squares for the reasons to be explained below.Every node periodically sends out beacons to announce its pres-ence and location.The interval between two successive beacons is denoted as I b.Other nodes that are within the radio range will receive the beacons and record the sender as a neighbor.A neigh-bor of a node may or may not reside in the same order-0square.A receiving node,R,can determine whether it resides in the same order-0square with the sending node,S,based on the location carried in beacons.If both of them reside in the same square,R records S as“a neighbor in the square”.These beacons also contain a list of S’s known neighbors that reside in the same order-0square.When a beacon is received by R and the sender S is a neighbor in the square,R also records all nodes from the beacon’s neighbor list.Thus,a node can learn about other nodes in the same square that are less than or equal to two hops away.When node R needs a route to some nodes in the neighbor list of node S,node S could be used as next hop.If a node just moved away from the previous order-0square,its beacons can still be received by some nodes in that square.Af-ter receiving its beacons with a location in other order-0squares, those nodes can conclude the node has moved away and can safely remove it from the list of neighbors in the square.Otherwise,the absence of periodic beacons triggers neighbor expiration.If a node does not receive beacons from a known neighbor for some num-ber of beacon intervals,say c×I b,where c is a constant,the node expires the neighbor and removes it from the table along with its neighbor list.We suggest to use a c>2,so that temporary failures in the network do not causeﬂapping in the local table.A node that receives beacons from other order-0square is a “boundary node”.Each boundary node must determines its own order,the order of the least-order square that it itself and all of its neighbors reside in.This order for the boundary node X is denoted as X BO,and is used for updating sibling squares.3.1.2All-Order Sibling Square Update AlgorithmA node maintains a summary of a square if it resides in one of the square’s sibling squares.Summaries held by a node must be updated when it is appropriate.The criteria to start an update can be chosen differently to meet several performance objectives. Boundary nodes are responsible for generating new summaries and initiating the update,other nodes in the sibling squares must cooperate in the propagation of the update messages.To simplify the design,our algorithm is based on broadcasting,that is,aﬂood is initiated when the update is required.A boundary node with order X BO generates a summary for each of the square that it re-sides in and with order that is less than or equal to X BO.The boundary node then broadcasts the summaries carried in summary update messages,which are received by its neighbors in the sibling squares.All nodes receiving the summaries decide whether it is necessary to re-broadcast it.The ultimate goal is for all the nodes in those sibling squares to receive the summary update messages without degrading network efﬁciency.When a node R receives a summary update message for a square of order-i originated from a node S,it only updates the stored summary and re-broadcasts the message if both of the following conditions are satisﬁed:(1)if R and S resides in sibling order-i squares;(2)if R never receives a summary for the same square,or it was received more than an I b interval ago.Note that summary update messages of the same square may be sent by different senders.This algorithm does not distinguish be-tween senders.Summary update messages can beﬂooded at differ-ent areas in parallel.Participating nodes use these two criteria to decide whether they should re-broadcast it or not.3.1.3Summary GenerationWe use similar summary representations as described in[3].Bloom ﬁlter[1]can also be used to generate summaries in some applica-tions.The idea of summary will be brieﬂy introduced below by using the terminologies in this paper.We then proceed to explain the process of generating a summary for a square.All summaries are represented by aﬁxed-length bit vector.To look up a node in the summary,weﬁrst apply n hash functions (for n≥1)to its ID and get n bit positions.We then check the summary to see whether these bits are set.If at least one of these bits are not set,then the node is not included in the summary.If all of the bits are set,then the node is included in the summary with a certain probability.The probability can be as high as1.In the case that the node is not included in the summary but all the bits for it are set in the bit vector,we call it a“false positive”.Unless nodes move,this can only be caused by collisions of hashed values. There are two types of summary representations:theﬁrst one is called“exact summary”,the second one is called“imprecise sum-mary”.Either one can be used in GRSS,but the system exhibits different properties.When“exact summary”is used,the total num-ber of bits in the bit vector must be greater than or equal to the size of ID name space,that is,the enumeration of all possible ID values. Every bit in the bit vector is dedicated to a possible node ID.If it is set,then the node must be included.There is no false positive due to collisions for this type of representation,and it requires only one hash function.When“imprecise summary”is used,the length of the bit vector can be smaller than the size of ID name space,but the total number of nodes could be included is still limited.We use Bloomﬁlter to generate summary of node IDs from an arbitrary name space that is larger than the length of the bit vector can repre-sent.More than one hash functions will be applied to a single node ID to obtain bit positions.All of these bit positions will be set or tested.When look up a node in the summary,if all of these bits are set,the node is included in the summary with a certain probability. It is possible to have false positive for this type of representation; however,it has been shown that the false positive rate can be con-trolled by using a larger bit vector or more hash functions.After describing our summary representation,we can discuss how to generate summary for a square.Note that a higher-order square is formed by several lower-order squares,a summary for an order-(i+1)square must include all nodes that are included in the summaries of all its order-i squares.Because the summaries are bit vectors with the same length,we can obtain a new summary that is the union of these summaries by bit-wise OR operations.A summary can be constructed recursively,but we need to gen-erate an initial summary for order-0squares.A boundary node can construct an order-0square summary from node IDs stored in its local table using a summary representation.A boundary node cal-culates all of its bit positions by applying n hash functions to every node ID it knows that resides in the square,and sets the bit vector accordingly.It is desirable to keep the length of the bit vector as small as possible,so it can beﬁt into a packet.If a summary update spans multiple packets,it will consume more resources to carry out an up-date and complicate the implementation.In practice,the maximum packet size is about1,500bytes,which means the ID name space can not be larger than12,000with exact summary;with imprecise summary,though the ID name space can be arbitrarily large,only about1,200nodes can be included in a summary without introduc-ing signiﬁcant false positive rate(1%).3.1.4Routing with False PositivesAs mentioned before,it is possible to have false positives with exact summary representation in a mobile network,or just with im-precise summary representation in any network.These false posi-tives may cause a packet to be dropped due to ambiguous routes to the destination.In a mobile network,stale information can result in false pos-itives with exact summary representation.These false positives only happen when a node moves across square boundaries.If a node moves across squares,it may take time before some boundary nodes in the original square to detect its absence,but the boundary nodes in the new square will learn its presence in I b time.So both squares may include the node in their summaries for a short period of time.The result is some nodes receive multiple summaries that all include the same node.There are two possible ways to deal with this problem:either arbitrarily choose a square whose summary in-cludes the node and forward the packet to its center,or simply drop the packet.This same problem also appears in the mobile network with im-precise summary representation.In addition to that,more false pos-itives are caused by hash function collisions.Hash function colli-sions introduce a problem such that some nodes look up their sum-maries and conclude the existence of a node,but in fact it does not reside in those squares or does not even exist in the network.This false positive can not be repaired if nodes stop moving,and the damage becomes permanent.The solutions to deal with previous case can also apply here.With exact summary,the cost of choosing an arbitrary square and forwarding the packet is the increased total number of hops it travels.In addition to that,with imprecise summary,the cost of choosing an arbitrary square and forwarding the packet is the waste of network resource—the packet may be forwarded in the network for several hops before certain intermediate nodes detect its destination node does not exist and decide to drop it.4.CONCLUSIONS AND FUTURE WORK We proposed an algorithm for building a robust and scalable lo-cation dissemination system called GRSS.The system is designed to proactively disseminate aggregated information using a hierar-chical structure.The system is proactively disseminating informa-tion in the summary update messages,and the region a message is being propagated is restricted by the hierarchical structure.Only few messages are required to travel a long distance in the network. Although the information included in a summary is aggregated,its inaccuracy does not necessarily degrade the routing performance —the packet can be delivered with a high successful rate,but the path traveled may not be optimal.Below are someﬁndings from our simulation results.First,the state kept per node is proportional to the logarithm of the network’s geographical size.Second,the cost of maintaining the system is proportional to the number of nodes in the network and the state kept per node.Third,the correctness of location summary does not decrease when the size of the network increase;however,the cor-rectness decreases as the density of the network increases.Forth, although the packet delivery rate of using a simple geographical routing algorithm is high in a dense network,the average path length can be as worse as20%longer than optimal.Fifth,prop-erly tuned parameters(m ratio and number of hash functions)of imprecise summary representation can achieve the same level of performance as exact summary.Details of the simulation results and some implementation experience can be found in the full ver-sion of the paper.In order to further study the performance of GRSS,it must be better integrated with the forwarding mechanism,that is,the ge-ographical routing algorithm.A feature of GRSS is that it does not require the data packets to carry additional information and this could help when integrating with a geographical routing algorithm that requires.We plan to explore along this direction by integrat-ing with,for example,GPSR.We are also interested in compar-isons with existing work.However,the comparisons are subject to same performance objectives,where different network conﬁgura-tions may require different optimization schemes that are not well understood yet.5.REFERENCES[1]B.Bloom.Space/time trade-offs in hash coding with allowablemunications of ACM,13(7):422–426,July1970.[2]P.Bose,P.Morin,I.Stojmenovic,and J.Urrutia.Routing withguaranteed delivery in ad hoc wireless networks.In int.Workshop on Discrete Algorithms and methods for mobilecomputing and communications,August1999.[3]L.Fan,P.Cao,J.Almeida,and A.Z.Broder.Summary cache:A scalable wide-area cache sharing protocol.In Proceedingsof the ACM SIGCOMM,October1998.[4]G.G.Finn.Routing and addressing problems in largemetropolitan-scale internetworks.Technical ReportISI/RR-87-180,March1987.[5]D.B.Johnson.Routing in ad hoc networks of mobile hosts.InProceedings of the IEEE Workshop on Mobile ComputingSystems and Applications,pages158–163,December1994. 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