Chapter 7 waves
大海啊故乡英文版
大海啊故乡英文版Oh, Sea! My Beloved HomelandHow I long to embrace the vastness of the ocean, to immerse myself in its gentle waves and feel the salt air brushing against my face. The sea, my dear homeland, holds a special place in my heart. Its beauty and grandeur never fail to captivate me, no matter where I may roam.Chapter 1: The Melody of WavesAs I stroll along the sandy shore, the symphony of the sea fills my ears. The rhythmic crashing of the waves against the rocks creates a soothing melody, a lullaby that brings me comfort. The ebb and flow of the tides, like the heartbeat of the ocean, remind me of the constant change in life.Chapter 2: A Kaleidoscope of ColorsGazing out onto the horizon, I marvel at the kaleidoscope of colors that dance upon the water's surface. The brilliant hues of blue, turquoise, and emerald mingle with the golden rays of the sun, painting a picture that is both serene and awe-inspiring. How fortunate I am to witness this natural masterpiece!Chapter 3: Untapped TreasuresBeneath the surface lies a world of wonders waiting to be explored. Coral reefs, teeming with vibrant marine life, create a mosaic of colors just below the water's edge. Schools of fish play hide and seek amidst the rocks, while graceful dolphins and majestic whales gracefully glide through the depths. The sea is a treasure trove, holding secrets that still remain untold.Chapter 4: The Serenity of SeclusionThere is a certain serenity that can only be found at sea. The vast expanse offers a haven from the chaos of the world, a place where one can find solace in the gentle lapping of the waves. With each breath of the salty air, I am reminded of the tranquility that exists in the simplicity of nature.Chapter 5: A Source of InspirationFor centuries, the sea has inspired poets, artists, and dreamers. Its ever-changing nature serves as a metaphor for the unpredictable journey of life. Just as the sea can be calm and tranquil one moment, it can also unleash its fury in a tempestuous storm. Through its constant motion, the sea teaches us to embrace change and find strength in adversity.Chapter 6: A Connection to Beloved OnesThe sea holds a special place in my heart because it connects me to my loved ones. As a child, I would visit the shore with my family, building sandcastles and collecting seashells. These memories are etched in my mind, and every time I return to the sea, I feel their presence by my side. The sea bonds us across time and space, reminding me of the enduring power of love.Chapter 7: Reflection and RenewalStanding at the water's edge, I find a sense of clarity and renewal. The vastness of the sea is a mirror that reflects my innermost thoughts and feelings. It is here that I can let go of my worries and fears, allowing the waves to wash them away. The sea acts as a therapist, soothing my soul and guiding me towards self-discovery.Epilogue: A Love Letter to the SeaOh, sea, how I cherish you, my dear homeland. You are a source of wonder, a place of solace, and a muse for my soul. Your vastness and beauty remind me of the infinite possibilities that lie within and around me. As I bid you farewell for now, know that I carry your spirit with me, wherever I may go. Until we meet again, my beloved sea.。
ANSYS循环对称结构的模态分析
循环对称结构的模态分析主要用在如齿轮，涡轮，叶轮等的具有循环对称结构物体的模态分析。
它通过模拟结构的一个扇区，通过分析这个扇区，从而扩展到整个模型。
它的步骤主要有6个。
1，建立基本扇区模型，也就是只建1/n的模型，一个齿活一个叶片的模型。
2，确定循环对称面（可以自动确定，也可以手动选择）。
3，施加边界条件。
4，制定分析类型和分析选项。
5，通过cycop命令指定循环求解选项，并用solve求解。
6，通过/cyexpand将振型扩展到全部360度范围，观察整个结果。
由于选择的谐波指数的关系，固有频率在排列上会有一些凌乱。
以前的ansys版本把谐波指数这个概念叫做节径，现在的都叫做谐波指数了。
按照整体结构分析，系统会把频率按照从小到大排列。
而用谐波指数这样计算出来的频率，他在排列的时候是按照谐波指数的增加而排列的，因此，相对应的固有频率有大有小，不规则（但是数值一样，就是排列不同）。
解决的办法是，你把这个结果提取出来，自己把它按照从小到大排列一下就可以了。
另外求解这个过程有一些注意的地方。
a在建立基本扇区的时候要在柱坐标系，你把csys置1就可以，b另外，扇区角选择能被360整除的。
c选择循环对称面时选择节点，好像其他特征不行（原因别人和我讲了，忘了）。
ac比较重要，b稍微注意一下就好。
然后就是求解方面了。
循环对称模态分析结果提取一般的结构模态分析完成后，要提取相应阶次结果，就用下面命令*GET,PARA,MODE,i,FREQ对于循环对称结构，取单个扇区进行分析，指定谐波指数The harmonic index，数值上谐波指数可以通过下面计算得到，The harmonic index= N/2 （N为偶数）The harmonic index=（N-1）/2 （N为奇数）上式中，N为总体模型分成的扇区总数。
然后对每次谐波设定提取模态阶次，分析的时候，ansys在原来扇区有限元模型的基础上，叠加一个完全相同的模型，通过谐波指数控制不同的傅里叶级数展开，从而扩展得到全模型的结果，对于这样计算的模态结果，ansys计算的时候，默认从0谐波开始计算，每次谐波按照一个载荷步（LSstep）进行，对应每次谐波下提取的固有频率按照子步substep给出，要提取所有谐波指数下的模态解，可采用下面命令/POST1*dim,frq_0,,7,10*do,i,1,7*do,j,1,10SET,i,j*GET,frq_0(i,j),ACTIVE,,SET,FREQ*enddo*enddo解释：按照谐波指数提取结构固有频率到数组frq_0中，i代表计算的LSstep，循环对称结构模态分析中，其最大值在数值上等于谐波指数+1，比如说，提取6次谐波，就需要7步计算；j代表每次谐波提取的固有频率个数。
国际金融英文版(托马斯A普格尔著)---Chapter7
International lending to developing countries: the surge in international lending, 1974-1982
The oil shocks of the 1970s led to a surge in private international lending to developing countries. Four forces combined to create the surge.
12
International lending to developing countries: the surge in international lending, 1974-1982
– Third, in developing countries, the 1970s was an era of peak resistance to foreign direct investment, in order to gain access to the higher returns offered in developing countries, banks had to lend outright to governments and companies in these countries.
8
Taxes on international lending
If a country looms large enough to have power over the world market rate of return, it can exploit this market power to its own advantage, at the expense of other countries and the world as a whole. (nationally optimal tax) see figure 7.1 for an illustration
新概念英语第四册第40课-Waves
新概念英语第四册第40课:Waves（实用版）编制人：__________________审核人：__________________审批人：__________________编制单位：__________________编制时间：____年____月____日序言下载提示：该文档是本店铺精心编制而成的，希望大家下载后，能够帮助大家解决实际问题。
文档下载后可定制修改，请根据实际需要进行调整和使用，谢谢!并且，本店铺为大家提供各种类型的实用范文，如学习资料、英语资料、学生作文、教学资源、求职资料、创业资料、工作范文、条据文书、合同协议、其他范文等等，想了解不同范文格式和写法，敬请关注!Download tips: This document is carefully compiled by this editor.I hope that after you download it, it can help you solve practical problems. The document can be customized and modified after downloading, please adjust and use it according to actual needs, thank you!In addition, this shop provides various types of practical sample essays, such as learning materials, English materials, student essays, teaching resources, job search materials, entrepreneurial materials, work examples, documents, contracts, agreements, other essays, etc. Please pay attention to the different formats and writing methods of the model essay!新概念英语第四册第40课:WavesLesson 40 Waves海浪 First listen and then answer the following question.听录音，然后回答以下问题。
FundamentalsofAerodynamics
Fundamentals of Aerodynamics
Fourth Edition
John D. Anderson, Jr.
Curator of Aerodynamics National Air and Space Museum Smithsonian Institution and Professor Emeritus University of Maryland
பைடு நூலகம்
Contents
xiii
Chapter 4 Incompressible Flow over Airfoils 295 4.1 4.2 4.3 4.4 Introduction 297 Airfoil Nomenclature 300 Airfoil Characteristics 302 Philosophy of Theoretical Solutions for Low-Speed Flow over Airfoils: The Vortex Sheet 307 4.5 The Kutta Condition 312
Inventarisiert unter
TECHWISCHE UNIVERSITAT DARMSTADT
Fachgebiot Konstruktiver Leichtbau und Bauwelsen Prof. Dr.-lng. Helmut Schurmann S4287 Darmstadt, PetersenstraBe 30
187
3.19
3.20 3.21 3.22
190
Incompressible Flow in a Duct: The Venturi and Low-Speed Wind Tunnel 197 Pitot Tube: Measurement of Airspeed 210 Pressure Coefficient 219 Condition on Velocity for Incompressible Flow 221 Governing Equation for Irrotational, Incompressible Flow: Laplace's Equation 222 3.7.1 -. Infinity Boundary Conditions 225 3.7.2 Wall Boundary Conditions 225 Interim Summary 226 Uniform Flow::Our First Elementary Flow 227 Source Flow: O u r Second Elementary Flow 229 : ...; .•,..= :. ....• Combination of a Uniform Flow with a Source and Sink 233 Doublet Flow: Our Third Elementary Flow 237 Nonlifting Flow over a Circular Cylinder 239 Vortex Flow: Our Fourth Elementary Flow 245 Lifting Flow over a Cylinder 249 The Kutta-Joukowski Theorem and the Generation of Lift 262 Nonlifting Flows over Arbitrary Bodies: The Numerical Source Panel Method 264 Applied Aerodynamics: The Flow over a Circular Cylinder—The Real Case 274 Historical Note: Bernoulli and Euler—The Origins of Theoretical Fluid Dynamics 282 Historical Note: d'Alembert and His Paradox 287 Summary 288 Problems 291
IgorPro中文操作手册-1
Igor computes a wave’s X values.
Point number
0
X value 0
Igor stores a wave’s data values in memory.
25614294_Chapter_7_The_call_of_the_wild_第七章野性的呼唤
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chapter- 7 Heat transfer
Heat transfer by conduction
Fourier’s First Law of Heat Transfer
q dT = −k A dx
q is the rate of heat flow, A is the area through which heat is transferred. The expression q/A, the rate of heat transfer per unit areas, is called the heat flux. The derivative dT/dx is the temperature gradient. K is thermal conductivity.
Conduction: Heat will be transferred between adjacent molecules. Convection: Heat is transferred when molecules move from one point to another and exchanges energy with another molecule in the other location. Radiation: the phenomenon of heat transfer by electromagnetic waves.
If the wall of the cylinder consists of layers having different thermal conductivities. T1 and T2 must transect a layer bounded by r1 and r2, which has a uniform thermal conductivity k1. Similarly, the layer bounded by r and r where the temperatures are T and T must also have a uniform thermal conductivity, k2.
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Velocity of wave traveling depends on the medium which waves go through.(波的传播速度只与介质有关）
Transverse wave on a rope or string
v
v
(1)Velocity of Transverse waves
plane wave spherical wave wave ray wave front wave surface wave number medium element nodes antinodes constructive interference destructive interference standing wave Doppler effect
Velocity of wave
Wavelength λ
v
Crest
λ v T
x
Amplitude
Vibrating
Trough
Transverse wave
λ
Crest
Amplitude Trough
v
v f T
x
Longitudinal wave
4. Velocity of waves
平面波 球面波 波线 波前 波面 角波数 介质元素 波节 波腹 加强干涉 减弱干涉 驻波 多普勒效应
7.1 Mechanical Waves
1. Mechanic waves
Earthquake waves
Sound waves in the air
Chorus, Violin, viola, cello, (bass), brasses (flute, clarinet)
Longitudinal waves
Vibrating direction
Wave traveling
Drum membrane
The displacement of every such oscillating string element is parallel to the direction of wave’s travel.
t=0
0
4
8
12
16
20
Longitudinal wave
Production of sound wave, which is example of longitudinal wave
Drum membrane Compression
Expansion
3. Characteristics of wave motion
Key words and terms
wave motion mechanical wave transverse wave longitudinal wave simple harmonic wave （SHW) crest trough wavelength wave velocity reflection interference wave function (wave equation or mathematical representation of traveling waves) 波动 机械波 横波 纵波 简谐波 波峰 波谷 波长 波速 反射 干涉 波函数, 波动方程
2. Wave types and Propagation (1) Types of Mechanical Wave Transverse waves Wave traveling
Vibrating direction
The displacement of every such oscillating string element is perpendicular to the direction of wave’s travel.
v
E
v
B
ρ
E – young’s modulus of material， ρ— density, B—bulk modulus
Sound wave B < E, In a solid G < Y,
vliquid<vsolid v横波<v纵波
* 横波产生切应变, 纵波产生长、体应变. 因此, 固体中能 传播纵、横波, 而液体和气体中只能传播纵波
a Direction of travel b
2
x
x
2
x k x Path length difference Phase difference
单位时间内的相位变化 “+” to the left
2 2 f T
“-” to the right
Determine wave function A ， ，，k Phase constant : from the initial conditions
* Suppose SHM couldn’t be absorbed ( frictional losses) by the medium which SHM travels through.
1. Mathematical representation of the waves (wave function)
5. Several concepts about wave motion：
wave surface
ray Wave front ray
ray ray
Plane waves
Spherical wave
Wave front
7.2 SHW and its Representation
SHW—simple harmonic waves , SHM traveling through a medium forms SHW
General features of mechanical waves: (1) A wave travels over large distance with a particular speed. (2) Each part of medium in which the wave travels oscillates about its equilibrium and does not go away with the wave . (3) Waves carry energy and states of oscillation from one place to another.
Chapter 7 Wave Motion
Chapter 7 Wave Motion 7.1 Mechanical Waves 7.2 SHW and its Representation 7.3 Energy and Intensity of waves 7.4 Interference of waves 7.5 Standing waves 7.6 Doppler Effect
1. Mechanical waves: mechanical vibration travels through elastic medium
Vibration is the source of mechanical wave and medium is necessary for vibration traveling through .
phase angle
Angular wave number
Angular frequency
Determine wave function A ， ，，k
(1) Find the characteristics of the wave
General form
v
y (x , t ) A sin kx t 2 单位长度内的相位变化 k v
v FT
FT
ቤተ መጻሕፍቲ ባይዱ
On a cord
FT- tension in the cord , -mass of per unit length
Velocity of Longitudinal waves
Longitudinal wave in a solid Longitudinal wave in a liquid
(2) 已知某时刻 t=0 (或t=t0) 的波形图波动方程
y( x, t 0) A sin kx A sin
y
2
x Wave shape at t=0 (波形图)
v
o
x
After a time t, the wave will have traveled a distance vt 2 y ( x, t ) A sin[ ( x vt )] A sin( kx t ) Mathematical representation of waves
Question： The displacement of a string carrying a
traveling sinusoidal wave is given by
y ( x, t ) A sin(kx t )
At time t = 0 the point at x = 0 has velocity of 0 and positive displacement. The phase constant is: (A) 00 (B) 900 (C) 1350 (D) 1800 (E) 2700