交通噪声外文文献
噪声污染的英文作文
噪声污染的英文作文英文：Noise pollution is a serious problem in our modern society. It refers to the excessive noise that is generated by various sources such as traffic, construction work, industrial activities, and even household appliances. This type of pollution can have negative impacts on both our physical and mental health.Firstly, noise pollution can cause hearing problems. Exposure to high levels of noise can damage the delicate hair cells in our inner ear, leading to hearing loss or even deafness. Secondly, it can also cause stress and anxiety. Constant exposure to loud noise can elevate our stress hormone levels, which can affect our mood and lead to mental health problems over time.In addition, noise pollution can also affect our sleep quality. Loud noises at night can disrupt our sleeppatterns, leading to fatigue and decreased productivity during the day. Furthermore, it can also affect our communication abilities. Excessive noise can make itdifficult to hear and understand what others are saying, leading to misunderstandings and even conflicts.To address this problem, we need to take action at both the individual and societal levels. At the individual level, we can use noise-cancelling headphones or earplugs toprotect our ears from loud noises. We can also avoid using noisy appliances at home or during quiet hours. At the societal level, governments and businesses can implement noise control measures, such as building noise barriers or regulating noise levels in public areas.In conclusion, noise pollution is a serious issue that needs to be addressed. By taking action at both the individual and societal levels, we can reduce its negative impacts on our health and well-being.中文：噪声污染是我们现代社会面临的严重问题。
噪声相关英文文献
2008 Received February 12, 2007; accepted November 30, 2007; published online June 25, 2008doi: 10.1007/s11432-008-0082-5†Corresponding author (email: yunguihun@ )Supported by the National Natural Science Foundation of China (Grant No. 60372022) and Program for New Century Excellent Talents in Uni-versity (Grant No. NCET-05-0806)Sci China Ser F-Inf Sci | Oct. 2008 | vol. 51 | no. 10 | 1585-1593 eigenstructure-based methods, such as 2-D MUSIC-type method [1] and 2-D ESPRIT-type ESPRIT method is a special case of DOA matrix method [5].Unfortunately, there are also many phenomena in signal processing which are decidedly non-Gaussian [6―13], such as atmospheric noise, urban radio channels, man-made signals, and so on. Recently, it has been shown that impulsive noise can be modeled as a complex symmetric α-stable(S αS) process. Since S αS does not possess finite variance when 2α<, minimum dis-persion criterion is a good choice to evaluate the S αS process. Lv et al.[6,7] have proposed several methods using cross-covariation matrix to estimate 2-D DOAs of the signals in the presence of impulsive noise.In some applications, useful information can be obtained by introducing time domain process-ing [8,9,14―16]. He et al.[8,9] presented a DOA estimation method in impulsive noise environments using fractional lower-order spatio-temporal (FLOST) matrix. Jin [15,16] proposed a spatio-tempo- ral DOA matrix (ST-DOA) algorithm which takes advantages of the a priori in time domain. How- ever, not only 2-D ESPRIT method [2,6], but also DOA matrix method [4,5,7] and ST-DOA matrix method [15,16] cannot estimate signals with common 1-D angles or in some curved plane, which degrades the estimation performance of those algorithms.In this paper, we proposed a novel joint diagonalization FLOST matrix method (JD-FLOM- ST-DOA). The method can obtain the 2-D DOAs of the array based on joint diagonalization di-rectly with neither peak searching nor pair matching. Moreover, compared with ST-DOA matrix method, the significances of the novel algorithms are as follows: 1) it can work in impulsive noise environments; 2) it can estimate signals with common 1-D angles in any plane. Simulation results show the effectiveness of the proposed method.2 Complex S αS random variables [11]A complex random variable is S αS if and are joint S αS, and then their characteristic function is written as1j X X X =+2⎤1X 2X (1)122*11221122,12(){exp[j ()]}{exp[j()]}exp ||d (,),X X S E X E X X x x x x αϕωωωωωωΓ=+⎡=−+⎢⎥⎣⎦∫R where 12,j ωωω=+ is the real part operator, and is a symmetric measure on theunit sphere , called the spectral measure of the random variable The characteristic expo-nent is restricted to the values []i R 12,X X Γ2S .X 02,α<≤ and it determines the shape of the distribution. The smaller the characteristic exponent α, the heavier the tails of the density.A complex random variable 1j 2X X X =+ is isotropic if and only if hasa uniform spectral measure. In this case, the characteristic function of X can be written as12(,)X X (2)*(){exp[j ()]}exp(||),E X αϕωωγω==−R where (0)γγ> is the dispersion of the distribution. The dispersion plays a role analogous to the role that the variance plays for the second-order processes. Namely, it determines the spread of the probability density function around the origin. A method for generating complex isotropic S αS random variables is given in ref. [11]. Several in-phase components of the time series with different characteristic exponents are given in Figure 1, which shows the impulsiveness of the S αS distribution.1586 XIA TieQi et al. Sci China Ser F-Inf Sci | Oct. 2008 | vol. 51 | no. 10 | 1585-1593Figure 1 Time series of S αS random variables.A complex isotropic S αS random variable X has finite fractional lower-order moments (FLOMs) 2,p α<≤ i.e., {||},p E X <∞ 2.p α∀<≤ Obviously, S αS signals are of infinite variance because their second-order moments are infinite. The FLOM between ξ and η is defined as in ref. [10]:12*[,]{}{||},12,p p f E E p ξηξηξηηα−−==<<≤ (3) where, 1*||,p p ηηη−= and the superscript * denotes complex conjugate.3 Array configuration and signal model3.1 Assumptions and data modelConsider a uniform linear array consisting of M -element as shown in Figure 2. The spacing be-tween the first M −1 sensors is d x while the spacing between the first and the M th sensor is d y . Assume that there are D narrowband independent signals () (1,2,,)k s t k D =… with common carrier impinging on the array from 2-D directions (,).k k θβ As made in refs. [8,9], we assume the signal vector s (t ) satisfying2T H 1{s()[(|s()|)s ()]}diag[(),,()],p D E t t t τρτρτ−+= … (4) where superscript H denotes complex conjugate transpose, denotes Hadamard product (ele-ment-by-element product), and diag[]⋅ is the diagonal matrix formed with the elements of its vector valued argument. Eq. (4) means that the signals () (1,2,,)k s t k D =… are mutuallyFLOST uncorrelated. denotes the auto-FLOST moment of2*()[()|()|()]p k k k k E s t s t s t ρττ−=+().k s t The baseband signals of the t th snapshot of the array output measured by the array can be expressed asXIA TieQi et al. Sci China Ser F-Inf Sci | Oct. 2008 | vol. 51 | no. 10 | 1585-1593 158712π()()exp j (1)cos()(), 1,,1,Di k x k i k x t s t i d n t i M θλ=⎡⎤=−+=⎢⎥⎣⎦∑…− (5) 12π()()exp j cos()().D M k y k M k x t s t d n βλ=⎡⎤=⎢⎥⎣⎦∑t +(6)Figure 2 Array configuration for independent 2-D DOAs estimation.Write eqs. (5) and (6) into matrix form, and we have()()(),t t =+x As n t T D(7)T T 111[(),,()], ()[(),,()], [(),,()],M M x t x t t n t n t s t s t ===......x n s T 11[,,,,], [,,,,],k D k k ik Mk a a a ==............A a a a a (8)2πexp j (1)cos(), 1,,1,ik x k a i d i θλ⎡⎤M =−=⎢⎥⎣⎦…− (9) 2πexp j cos(),Mk y k a d βλ⎡⎤=⎢⎥⎣⎦(10) where is additive uniform complex isotropic S αS noise with dispersion γ, independent of the signals, i.e.,()(1,2,...,)i n t i M = 2T H {()[(|()|)()]}(),p M E t t t τ−+ n n n I γδτ= (11) where ()δτ is Kronecker function, and M I is an M M × dimensional identity matrix.3.2 FLOM-ST-DOA matrix method Under the above assumptions, we have the following array outputs of FLOST moments:2**1()[(),()][()|()|()][()],(1,2,,,0,,,,,,i M k k p x x i M f i M M D),s s Mk ik s s s s k R x t x t E x t x t x t R a a i M NT T T NT ττττττ−==+=+==≠=−−∑ (12)where 2*()[(),()][()|()|()].k k p s s k k f k k kR s t s t E s t s t s t τττ−=+=+ 2****1()[(),()][()|()|()][()], (0,1,2,,,1,2,,,1).i l k k p x x i l f i l l Dlks s Mk ik k Mk R x t x t E x t x t x t a R a a i M l L L M a τττττ−==+=+=≠==∑……=− (13)1588 XIA TieQi et al. Sci China Ser F-Inf Sci | Oct. 2008 | vol. 51 | no. 10 | 1585-1593Let (),X τR ()l Y R τ and (),S τR respectively, be1T ()[(),,(),,()],M i M M M X x x x x x x R R R ττττ=……R (14)1T ()[(),,(),,()],l l i l M l Y x x x x x x R R R ττττ=……R (15)11**1()[(),,(),,()].k k D D S s s M s s Mk s s MD R a R a R a ττττ=⋅⋅⋅……R *T (16)Write eqs. (12) and (13) into matrix form,()(),X S ττ=R AR (17)()(),l Y l S ττ=R A R Φ (18) where is a D ×D dimensional matrix,l Φ 11***1***1j2π/[cos (1)cos ]j2π/[cos (1)cos ]j2π/[cos (1)cos ]j2π/[cos (1)cos ]1diag ,,,,diag{e ,,e ,, e ,,e }diag[,,,,x y x p y p x q y q x D y D l lk lD l M Mk MD d d l d d l d d l d d l l gl a a a a a a λβθλβθλβθλβθφφ−−−−−−−−⎡⎤=⎢⎥⎣⎦==………………Φ,,], 1.ql Dl g q D φφ≠...≤≤ (19)By collecting the “pseudo snapshots” at 2N lags ,,,,,,s s s s NT T T NT τ=−−…… the “pseudo snapshots” data matrices are formed as follows:[(),,(),(),,()],X s X s X s X s NT T T NT =−−……X R R R R[(),,(),(),,()],l l l l l Y s Y s Y s Y s NT T T NT =−−……Y R R R R[(),,(),(),,()].S s S s S s S s NT T T NT =−−……S R R R R Then, eqs. (17) and (18) can be rewritten into,=X AS (20). (21) l l =Y A S ΦDefine FLOM-ST-DOA matrix as(22) †[],l TS l =⋅R Y X where denotes pseudoinverse, i.e.,†[]X†H H [][].1−=X X XX (23)Theorem 1. FLOM-ST-DOA matrix algorithm: if A and S is nonsingular and has un-equal elements, then the FLOM-ST-DOA matrix has its D non-zero eigenvalues equal to the D diagonal elements of and the corresponding eigenvectors equal to the D column vec-tors of matrix A , i.e.,l Φl TS R l Φ.l TS l =R A A Φ (24)The proof is similar to that given in ref. [5]. By eigendecomposition, we have A and . Then, the l Φk θ’s are obtained using the first M −1 elements of according to eq. (9), while (1)k D ≤≤k a k β’s are given by the M th element of according to eq. (10). The above theorem means that an estimate can be obtained if and only if there exists a matrix , which has (1)k D ≤≤k a l Φ XIA TieQi et al. Sci China Ser F-Inf Sci | Oct. 2008 | vol. 51 | no. 10 | 1585-1593 1589unequal entries. However, it is easy to construct examples where each l Φ(1)l L ≤≤ has a de-generate eigenvalue spectrum, and then the FLOM-ST-DOA matrix algorithm will fail. In the next section, we will propose an improved robust JD-FLOM-ST-DOA matrix algorithm to over-come this problem.4 JD-FLOM-ST-DOA matrix mehtod4.1 WhiteningThe first step of our JD-FLOM-ST-DOA matrix algorithm procedure consists of whitening the signal part of the pseudo-observation. This is achieved by applying a whitening matrix W to them, i.e., an ()X s nT R M D × matrix verifying the following:H H H H H [()()]X s X s X E nT nT .==WR R W WQ W WAA W I =,, (25)where and we assume thatH [()()]X X s X s E nT nT =Q R R H[()()](1/2)S S E N ττ=R R H ,0()()N S s S s n N n nT nT =−≠=∑R R Iand ()S τR has unit variance so that the dynamic range of ()S τR is accounted for by the mag-nitude of the corresponding column of A , which does not affect the estimation of the 2-D DOAs. Eq. (25) shows that if W is a whitening matrix, then is a WA D D × dimensional unitary ma-trix. It follows that for any whitening matrix W , there exists a unitary matrix U such that . As a consequence, matrix A can be factored as=WA U (26) †.=A W U Note that this whitening procedure reduces the determination of the M D × dimensional mixture matrix A to that of a unitary D D × dimensional matrix U . The whitened process still obeys a linear model:(27) ()(),X X n =z WR n n H H ..}, (28) ()().l l Y Y n =z WR Define the following cross-correlation matrix between and()l Y n z (),X n z (29)H H H H H [()()][()()][()()]l l l Y X Y X Y X l S S l E n n E n n E ττ====G z z WR R W WA R R A W U U ΦΦ4.2 Determining the unitary factor UThe second step of our JD-FLOM-STDOA matrix algorithm procedure is to determine a unitary factor U , which is obtained by performing a joint diagonalization of the combined set of The essential uniqueness of joint diagonalization is guaranteed by Theorem 2.1{,,,,}l L Y X Y X Y X= ……G G G G Theorem 2. Essential uniqueness of joint diagonalization: let be a set of L matrices where, for matrix is in the form withU a uni- tary matrix. Any joint diagonalizer of is essentially equal (the definition is given in ref. 1{,,,,l L Y X Y X Y X= ……G G G G 1l L ≤≤l Y X G H l U U Φ G [14]) 1590 XIA TieQi et al. Sci China Ser F-Inf Sci | Oct. 2008 | vol. 51 | no. 10 | 1585-1593to U if and only if1, , 1, pl ql p q D l l L .φφ∀≠∃≠≤≤≤≤ (30)The essential uniqueness condition (30) is of course much weaker than the requirement thatthere should exist a matrix in which is uniquely unitarily diagonalizable. In particular, it is easy to construct examples, where each matrix in has a degenerate eigenvalue spectrum but such that the joint diagonalizer of is nonetheless essentially unique. The proof of Theorem 2 is similar to the proof given in ref. G GG [14].Theorem 3. Sufficiency condition: if then (,)[0,π)[0,π),k k αβ∈×, 1,l l L ∃≤≤1∀≤. ,p q D ≠≤pl ql φφ≠Proof. If for the DOAs of the g th source (,)[0,π)[0,π),k k αβ∈×(,)g g αβ and q th source (,),q q αβ ,g q ≠ there exist two cases:1) if ,p q ββ≠ then 11;p q φφ≠2) if ,p q ββ=,p q αα≠ then ,pl ql φφ≠2l L ≤≤.Theorem 3 means that there exists at least one matrix satisfies (1)l l L ≤≤Φ.gl ql φφ≠Then, matrix A can be obtained by eq. (26) and the 2-D DOAs can be estimated according to eqs.(9) and (10).4.3 Implementation of the JD-FLOM-ST-DOA matrix methodBased on the previous sections, we can introduce a 2-D DOAs estimation method based on FLOST processing. The JD-FLOM-ST-DOA matrix method is defined by the following imple-mentation:1) Estimate the FLOM-ST matrix of the array outputs according to eqs. (13) and (14).2) Form the new pseudo-observation vectors X and .l Y 3) Estimate the sample covariance from the X Q 2M N × pseudo-observation X . Denote 1,,,D λλ… the D largest eigenvalues and 1,,D …h h the corresponding eigenvectors of As .X Q 0,τ≠ the whitening matrix W is formed by1/21/2H 11[,,D D λλ−−=…W h h ].4) Form the cross-correlation matrix according to eq. (29).l Y X G (1)l L ≤≤5) A unitary matrix U is then obtained as joint diagonalizer of the set{|1,,}.l Y X l L =…G 6) The matrix A is estimated as then the 2-D DOAs can be estimated according to eqs. (9) and (10).†,=A W U 5 Simulation results and performance analysisExample 1. Assume the three narrowband signals impinge from directions (40°, 50°), (55°, 80°), and (70°, 65°). We assume that α is already known, in practice, it can be estimated by some algorithms [13]. Simulation results are also compared with those of the ST-DOA matrix method [15]. α=1.4, p =1.1, M =6, d x =d y =λ/2. T = 500, 2N = 500([250,1]n ∈−−∪[1,250]). The performance of the estimators is obtained from 300 Monte-Carlo simulations, by calculating the RMSEs of the XIA TieQi et al. Sci China Ser F-Inf Sci | Oct. 2008 | vol. 51 | no. 10 | 1585-1593 1591DOA estimates. The RMSE is defined as RMSE(,)k k θβ= and GSNR is defined as 21GSNR 10log[(|()|)/].Tt s t T γ==∑ Figure 3 shows the RMSEs in degrees of the estimates of the three signals versus GSNR. We can see that the robustness is increased with our JD-FLOM-ST-DOA matrix method at low GSNRs.Example 2. In this example, the DOA parameters of the three signals are the same as Exam-ple 1. We fix GSNR=10 dB, p =1.05. The number of snapshots is T = 400, 2N = 400 The performance of the estimators is obtained from 300 Monte-Carlo simulations, by calculating the RMSEs of the DOA estimates. The RMSEs of the estimates of the three signals versus α are shown in Figure 3. We can see that the robustness is increased with our JD-FLOM-ST-DOA matrix method in strong impulsive noise environments.([200,1][1,200]).n ∈−−∪Example 3. Assume the three signals that impinge from the directions (59°, 59°), (70°, 80°), and (80°, 80°). Note that in this case for each l Φ(1,2,3)l = has a degenerate eigenvalue spec-trum. α=1.5, p =1.1, M =4, T = 450, 2N = 450([225,1][1,225]),n ∈−−∪ GSNR=15 dB. To obtain a measure of statistical repeatability, we make 100 Monte-Carlo simulations. Figure 4 shows that the FLOM-ST-DOA matrix algorithm can only estimate one of the three signals because the other two signals have a degenerate eigenvalue spectrum, but JD-FLOM-ST-DOA matrix method can estimate three signals successfully for its integration of the information in the three FLOM-ST-DOA matrices.Figure 3 RMSEs for the three signals versus GSNR. Figure 4 RMSEs for the three signals versus α. 6 ConclusionA novel 2-D DOAs estimation method based on joint diagonalization FLOST matrices is pro-posed, which makes full use of the data in time domain, as well as in spatial domain, to define generalized FLOST matrices. Theoretical analysis and simulation results show that the method is robust against S αS noise and it remedies the lack of the traditional subspace-based techniques employing second-order or higher-order moments cannot be applied in impulsive noise environ-ments. The method retains the advantage of the original ST-DOA matrix method which can esti- mate 2-D DOAs with neither peak searching nor pair matching. Moreover, it can estimate sources 1592 XIA TieQi et al. Sci China Ser F-Inf Sci | Oct. 2008 | vol. 51 | no. 10 | 1585-1593Figure 5Scatter plot of the three signals. (a) ST-DOA matrix method, l=1; (b) ST-DOA matrix method, l=2; (c) ST-DOA matrix method, l=3; (d) JD-FLOM-ST-DOA matrix method.with common 1-D angles in any plane, which outperforms the original ST-DOA matrix method significantly.1 Chan A Y J, Litva J. MUSIC and maximum likelihood techniques on two-dimensional DOA estimation with uniform cir-cular array. IEE P-Radar Son Nav, 1995, 3(142): 105―114 [DOI]2 Kedia V S, Chandna B. A new algorithm for 2-D DOA estimation. Signal Process, 1997, 60(3): 325―332 [DOI]3 Wang J Y, Chen T Q. Joint frequency, 2D AOA and polarization estimation using fourth-order cumulants. Sci China SerE-Tech Sci, 2000, 43(3): 297―3034 Yin Q Y, Zou L H, Newcomb R. A high resolution approach to 2-D signal parameter estimation-DOA matrix method. JChina I Commun (in Chinese), 1991, 4(12): 1―65 Yin Q Y. High Resolution Direction of arrival estimation. Doctor Dissertation. Xi’an: Xi’an Jiao Tong University (in Chi-nese), 19896 Lv Z J, Xiao X C. A novel method for estimating 2-D DOA in the presence of impulsive noise. J Electron Inf Tech (inChinese), 2004(3): 350―3567 Lv Z J，Xiao X C. A covariation-based algorithm for estimating 2-D DOA in the presence of impulsive noise. Acta Acust(in Chinese), 2004(2): 149―1548 Lv Z J, Xiao X C. A subspace-based direction finding algorithm using temporal and spatial processing of time lag frac-tional order correlation function. Signal Process (in Chinese), 2003, 2(19): 51―549 He J, Liu Z. DOA estimation in impulsive noise environments using fractional lower order spatial-temporal matrix. ActaAeronaut Astronaut Sin (in Chinese), 2006, 1(27): 104―10810 Liu T H, Mendel J M. A subspace-based direction finding algorithm using fractional lower order statistics. IEEE Trans Sig-nal Process, 2001, 8(49): 1606―161311 Tsakalides P, Nikias C L. The robust covariation-based MUSIC (ROC-MUSIC) algorithm for bearing estimation in impul-sive noise environments. IEEE Trans Signal Process, 1996, 7(44): 1623―1633 [DOI]12 Szajnowski W J, Wynne J B. Simulation of dependent samples of symmetric alpha-stable clutter. IEEE Trans Signal Proc-ess lett, 2001, 5(8): 151―152 [DOI]13 Tsihrintzis G A, Nikias C L. Fast estimation of the parameters of alpha-stable impulsive interference. IEEE Trans SignalProcess, 1996, 6(44): 1492―1503 [DOI]14 Belouchrani A, Abed-Meraim K, Cardoso J F, et al. A blind source separation technique using second-order statistics. IEEETrans Signal Process, 1997, 2(45): 434―444 [DOI]15 Jin L, Yin Q Y. Space-time DOA matrix method. Acta Electron Sin (in Chinese), 2000, 7(28): 8―1216 Jin L, Yin Q Y. Analysis and generalization of space-time DOA matrix method. Acta Electron Sin (in Chinese), 2001, 3(39):XIA TieQi et al. Sci China Ser F-Inf Sci | Oct. 2008 | vol. 51 | no. 10 | 1585-15931593300―3031594XIA TieQi et al. Sci China Ser F-Inf Sci | Oct. 2008 | vol. 51 | no. 10 | 1585-1593。
交通噪声介绍英文作文
交通噪声介绍英文作文Traffic noise is a constant presence in urban areas. The sound of cars honking, engines revving, and buses rumbling by can be overwhelming at times.The noise from traffic can have a negative impact on people's health. It can cause stress, sleep disturbances, and even hearing loss over time.In addition to the health effects, traffic noise can also be a nuisance for people trying to relax or concentrate. It can make it difficult to have a conversation, enjoy outdoor activities, or even just find some peace and quiet.One of the main sources of traffic noise is the design of the roads themselves. Highways and busy streets with a lot of traffic can produce a constant roar that is hard to escape.Efforts to reduce traffic noise include sound barriers, quieter road surfaces, and better urban planning to minimize the impact of traffic on residential areas.Despite these efforts, traffic noise remains a pervasive issue in many cities around the world. It's a reminder of the constant activity and movement of urban life, but it can also be a source of frustration and discomfort for those who have to live with it every day.。
噪音研究报告作文500字
噪音研究报告作文500字Englsih Answer:Noise pollution is a serious environmental issue that has been linked to a number of health problems, including hearing loss, cardiovascular disease, and sleep disturbance. Noise pollution can also have a negative impact oncognitive function and performance.One of the most common sources of noise pollution is traffic. Road traffic noise is a major problem in manycities around the world, and it can be a significant source of annoyance and stress for people who live near busy roads. Other sources of noise pollution include construction, industrial activities, and loud music.Noise pollution can have a number of negative effectson human health. Prolonged exposure to noise can lead to hearing loss, which can be a temporary or permanent condition. Noise pollution can also increase the risk ofcardiovascular disease, and it can lead to sleep disturbance. Sleep deprivation can have a number of negative consequences, including impaired cognitivefunction and decreased performance at work or school.Noise pollution can also have a negative impact on the environment. Noise can disturb animals, and it can disrupt ecosystems. Noise pollution can also make it difficult for people to enjoy the outdoors, and it can reduce the quality of life for people who live in noisy areas.There are a number of things that can be done to reduce noise pollution. Some of these measures include:Reducing the amount of traffic on the roads.Using quieter vehicles.Constructing noise barriers.Planting trees and shrubs.Educating the public about the dangers of noise pollution.Noise pollution is a serious environmental problem that can have a number of negative effects on human health and the environment. There are a number of things that can be done to reduce noise pollution, and it is important to take action to protect our health and the environment from this harmful pollutant.中文回答：噪音污染是一个严重的环境问题，它与许多健康问题有关，包括听力丧失、心血管疾病和睡眠障碍。
《城市交通拥堵问题研究国内外文献综述》3300字
城市交通拥堵问题研究国内外文献综述1.国外研究现状（1）对城市交通拥堵产生原因的研究Bull（2001）认为，城市公交系统的吸引力下降容易导致交通出现拥堵问题。
在不少城市，公交系统是解决交通拥堵问题的重要途径。
这主要是公交系统可以节约公共交通资源，以有限的资源满足公众的交通需要。
为此，公交系统的吸引力下降容易导致人们选择其他交通公交，例如公众选择自驾车作为交通公交。
另外，Bruno. A（2008）还补充认为，公交的吸引力还影响人们对政府治理城市交通的信心。
公交系统水平常常被人们视为政府管理交通的能力的表现。
为此，低下的公交发展水平容易对政府的公信力产生消极的影响[2]。
David F（1995）认为城市交通拥堵产生原因主要为部分公民的交通意识没有得到有效提高，这给城市交通拥堵问题的解决带来一定的制约作用。
Dublin （2002）认为城市交通拥堵问题的解决不能够仅仅依靠交通法规。
法规随着在很大程度上能够对公民的交通行为进行规范。
但是，单纯的法律强制却不能发挥完全的作用。
毕竟，交通法规无法完全对公众的交通行为进行全范围的限制和规范。
这需要交通道德意识的补充[4]。
Fries（1992）指出，良好的交通意识可以提升公众的自律能力，自觉性对自身的行为进行规范。
但是，由于公共交通意识教育的缺失，公民的交通道德意识并没有得到有效提升。
低水平的公共交通意识导致部分公民没有认真遵守交通法规，导致交通的混乱。
另外，低水平的公共交通意识还影响了行政政策的执行。
一些公众由于缺乏良好的公共意识，没有严格执行政府颁发的交通措施。
这导致措施的效用大打折扣，影响了城市交通拥堵问题的解决[3]。
Leblan（2006）提出，数量庞大的自驾车无疑给城市的交通管理带来沉重的压力，导致城市交通出现了拥堵。
相对于其他出行方式，自驾车这种方式占有更大的公共交通资源，严重降低了道路的使用效率。
政府难以通过对自驾车的管理以实现交通拥堵问题的解决。
城市轨道车辆外文文献
Environmental Noise Reduction of Tokaido Shinkansenand Future ProspectHitoshi Kanda, Hideaki Tsuda, Kimihiro Ichikawa, and Shohei YoshidaTechnology Planning Department, General Technology DivisionCentral Japan Railway Co., 2-1-85 Kounan, Minato-ku, 109-8204 Tokyo, JapanTel.: +81 3 6711 9580; Fax: +81 3 6711 9707h-kanda@jr-central.co.jpSummaryThis paper describes the technical review of the environmental noise reduction of Tokaido Shinkansen and its future prospect. Current environmental quality standards for Shinkansen railway noise were established in 1975 by the Environmental Agency, Japan. The Japanese Cabinet agreed on “general principles for countermeasures against Shinkansen railway noise” in 1976. Based on the principles, Central Japan Railway Company has spent a great effort to reduce the railway noise at source. Ow-ing to measures, the wayside noise has been remarkably decreased. On the other hand, the land use planning has not been strongly enforced. So there are regrettably some problems on later inhabitants along the Shinkansen railroad.This paper also discusses the noise evaluation. A present Shinkansen noise index is given by L Amax (peak noise level). It is reasonable to assume that the index will be shifted to L AEQ basis, since it has been widely applied. In order to study the effect of L AEQ standard, it seems important to investigate theoretical and scientific aspects of noise evaluation in other countries.1 IntroductionCentral Japan Railway Company (JR Central) commenced operations in April 1987 upon the privatization of the Japanese National Railways (JNR). The core of JR Cen-tral’s operations is the high-speed Tokaido Shinkansen, the main transportation line linking Japan’s metropolitan areas of Tokyo, Nagoya and Osaka. Providing a great mobility, it has played an important role in Japan’s economic growth and high living standards. Moreover, Tokaido Shinkansen has since offered large capacity, high fre-quency transportation services with high safety; such performance is drawing a strong attention from the worlds.JR Central has consistently responded to growing demand from business travellers and long-distance commuters since its founding. In March 1992, the timetable was revised in order to start the series 300 rolling stock into service with operating speeds up to 270 km/h. It has cut travel time drastically. The similar efforts have been made constantly to raise the service level.B. Schulte-Werning et al. (Eds.): Noise and Vibration Mitigation, NNFM 99, pp. 1–8, 2008. © Springer-Verlag Berlin Heidelberg 20082 H. Kanda et al.In the summer of 2007, the new trainset of series N700 starts the commercial op-eration. Along with starting new services, the series N700 will offer an "even more comfortable space" that meets the various needs of passengers. In addition, the series N700 achieves a reduction in energy consumption by 25% compared with the series 300 owing to the latest technologies. It greatly contributes to the preservation of the global environment.When studying such service improvement, the highest consideration must be given to the prevention of noise and vibration alongside the railroad because the Shinkansen connects Japan’s most densely populated areas. As means of improving environmental conditions, controlling environmental noise has recently been gathering attention in Japan as well as other countries.2 Environmental Quality Standards for Shinkansen Railway Current environmental quality standards for Shinkansen railway noise were estab-lished in 1975 by the Environmental Agency, Japan. The index of evaluation is given by L pA, Smax (slow max value of A-weighted noise level) not by L Aeq (equivalent noise energy level). The standard values are classified into two categories (I and II) based on the condition of residential use (Table 1).In category I, standard value is 70 dB or less, and in category II, standard value is 75 dB or less. They are applied from 6am to 24pm, the service hours of commercial Shinkansen operation.Table 1. Environmental quality standards for Shinkansen railway noiseCategory of Area Standard Value (L pA,Smax)Category I 70 dB or lessCategory II 75 dB or lessCategory I --- Mainly residential useCategory II --- Other areas including commercial and industrial, where normalliving conditions should be preservedOne year later, the Japanese Cabinet agreed on “general principles for countermea-sures against Shinkansen railway noise” in 1976. The principles addressed three measures that should be strongly promoted for achieving the environmental quality standards; (1) countermeasures at noise source, (2) compensation for the loss, and (3) land use planning along the Shinkansen railroad.Based on the principles, the Japanese National Railways and JR-Central have so far spent a great effort to decrease the railway noise at source. Successive efforts on measures at noise source will also be accumulated in future toward the environmental quality standards.Environmental Noise Reduction of Tokaido Shinkansen and Future Prospect 33 Technical Development for Noise Source3.1 Rolling StocksIn order to reduce the high-speed railway noise at source, technical development has been carried out for rolling stocks including pantograph covers and low noise panto-graphs, car’s ultimate shapes, smooth car bodies, and so on.Figure 1 presents the comparison of old and new type of pantographs and insulator covers. Figure 1(a) shows the series 300 former type, figure 1(b) shows the series 300 later type and the series 700, and figure 1(c) shows the new type insulator cover and low noise pantograph developed for the latest series N700.(a) Series 300 former type (b) Series 300 later type and series 700 (c) New Series N700Fig. 1. Comparison of pantographs and insulator covers Figure2 shows a photograph of a wind tunnel test for designing the series 700 “aerostream form” ultimate shape. Figure 3 shows the “external flush gap shroud (all covering hoods)” [1] and boggie skirts which are newly developed and introduced to the series N700 Shinkansen.3. All covering hoods and boggieFig. 2. Ultimate shape of Series 700 Fig.skirts of N7003.2 Rail and TrucksNoise can be reduced at rail and trucks by installing an elastic lubber sleeper or a lub-ber ballast mat shown in Figure 4. These measures are especially effective to reduce structure noise, and are widely used in viaduct sections of Tokaido Shinkansen. This measure is effective to vibration reduction as well as noise reduction.4 H. Kanda et al.Fig. 4. Elastic lubber sleeper and lubber ballast mat 3.3 Noise BarriersNoise barriers are built alongside of the Shinkansen railroad. Typical noise barrier ofTokaido Shinkansen is shown in Figure 5. Basic noise barriers are 2-meters high, and some additional barriers may be attached in a special area to increase the reduction effect.Fig. 5. Photograph of noise barriers Fig. 6. Photograph of a new-type noisebarrierBecause noise barriers were not considered for the initial design of the Tokaido Shinkansen structures, there is a limitation of barrier’s height especially in a viaduct section. In addition, since a high noise barrier may interrupt the wayside scenery from the window, special noise barriers are also experimentally developed. Figure 6 shows an example of a new-type barrier with “mountain-type” slits in the upper part of the wall to secure the window view.3.4 Simulation TechniquesMeasurement techniques and prediction methods for noise propagation are important to develop the new type Shinkansen trainset with better environmental quality. Figure 7 shows the “sound intensity counter maps” of Series 300 and 700, developed by a research group of JR-Central[2]. It is clearly demonstrated that the dark areasnear the boggie skirts, which display large sound pressure, are widely decreased for series 700 in Figure 7(b) compared to the series 300 in Figure 7(a).Environmental Noise Reduction of Tokaido Shinkansen and Future Prospect 5(a) Series 300 (b) Series700Fig. 7. Sound intensity counter maps 3.5 Environmental Supervision DepotsCentral Japan Railway Co. has four local environmental supervision depots alongside of the Shinkansen railroad. The main objective of these depots is the wayside envi-ronmental preservation of the Tokaido Shinkansen. There are two or three special engineers in each depot who are in charge of noise and vibration measurement, public relations and negotiation with inhabitants.4 Noise Level ReductionOwing to these measures, the Shinkansen wayside noise has been remarkably de-creased from the year of its inauguration in 1964, whereas the maximum velocity has been increased to 270 km/h. Figure 8 shows the transition of noise level from 1964 to 2000[3]. Typical counter-measures in each period are also noted below the figure.Inauguration of Tokaido Shinkansen NoisebarrierBallast mat Rail grinding Pantograph cover 70758085901964196719751986199119942000Year N o i s e L e v e l (L p A , S m a x ) d B 200210220230240250260270280290300M a x V e l o c i t y (k m /h )Series 300Series 700CountermeasuresFig. 8.Transition of Shinkansen noise level and countermeasures6 H. Kanda et al.It is expected in future that successive efforts on measures at noise source will be accumulated toward the environmental quality standards.5 Land Use PlanningOn the other hand, the land use planning, which is another principle addressed in the Cabinet Agreement, has not been strongly enforced so far. So there are regrettably some problems on later inhabitants along the Shinkansen railroad.Figure 9 demonstrates some photographs that show the change of Shinkansen way-side land use. After the inauguration of Shinkansen railway, many residential houses have been built alongside of the railroad. Therefore target areas for countermeasures have been increased with the development of residential areas at waysides. It is hoped in future that a specific method is introduced to the land use planning in Japan to re-strict the increase of residential houses alongside of the railroad.TokaidoShinkansenLocalTokaido Line(a) Under Construction (1963) (b) Present Condition (2004)Fig. 9. Change of wayside land use6 Index of Noise Evaluation6.1 L AEQ of ShinkansenThe new standards for Shinkansen noise have been discussed in recent years in Japan.A present noise index is given by L Amax, not by L AEQ which is widely applied in for-eign countries. However, L AEQ has already been applied in Japan to the guideline for newly-constructed local railway noise from 1995 and the environmental standards for road traffic from 1998. It is therefore reasonable to assume that the Shinkansen noise index will be shifted to the L AEQ basis in a future.There is a research paper that estimates the L AEQ of Shinkansen noise by the use of an indirect calculation from L Amax with a current trains’ timetable[4]. The results are summarized in Table 2. Tokaido Shinkansen offers 244 regular trains daily, in the daytime from 7am to 22pm. If all trains have 70dB peak noise level, L AEQ, 15H (7-22) is calculated to be 54.3dB. Similarly, if all trains have 75dB peak level, L AEQ, 15H (7-22)Environmental Noise Reduction of Tokaido Shinkansen and Future Prospect 7 becomes 59.3dB [5]. Table 2 also addresses the environmental standards for road traffic and guidelines for newly-constructed local railway in Japan.6.2 DiscussionIt becomes clear from Table2 that L AEQ of Shinkansen is smaller than that of road traffic in all categories. In both “exclusive residential” and “commercial & industrial” areas, Shinkansen keeps the environmental standards of road traffic even at night. In addition, since the grouping of “residential” is different, residential area of Shinkan-sen offers still smaller L AEQ than road.Table 2. Comparison between Shinkansen Environmental Noise Standards and Other Surface TrafficNext, when Shinkansen is compared with local railway, Shinkansen keeps the newly constructed local railway guidelines even at night in exclusive residential and residential areas, and keeps the daytime guidelines in commercial and industrial areas.This research reveals that, on the L AEQ basis, the present noise standards for Shinkansen railway provides more preferable wayside noise environment than the road traffic. This is contrary to many European countries that have the “railway-bonus” on the environmental standards for traffic noise. In order to study the effect of L AEQ standard and the background of railway-bonus, it is important to investigate the theoretical and scientific aspects of noise evaluation in European countries and to make clear if the similar idea is applicable to the standards in other countries.7 ConclusionIn this paper, technical review of the environmental noise reduction of Tokaido Shinkansen and its future prospect are described. Typical countermeasures at noise source are summarized, and the reduction effect of wayside noise level during past 408 H. Kanda et al.years is reviewed. Some problems are also mentioned on later inhabitants along the Shinkansen railroad. This paper also discusses the noise evaluation and comparison of environmental standard value between railway and road traffic.In conclusion, it is hoped that the Japanese Cabinet Agreement in 1976 is promoted more strongly toward the environmental quality standards. At the same time, railway companies will continue technical development on countermeasures at noise source.References[1]Kitayama, S.: Noise reduction of high-speed trains by installing an external flush gapshroud. In: Inter-Noise 2003, vol. 1008 (2003)[2]Kawahara, M., et al.: Source identification and prediction of Shinkansen noise by soundintensity method. In: Inter-Noise 1997 (1997)[3]Maeda, T.: Japanese Shinkansen noise: Development of noise reduction technology. In: In-ter-Noise 2006, Distinguished Lecture 2 (2006)[4]Nagakura, K., Zenda, Y.: Prediction model of wayside noise level of Shinkansen. RailwayTechnical Research Institute Report (in Japanese) 14(9), 9 (2000)[5]INCE/J, Research report on noise countermeasures of Shinkansen Railway. In: Ministry ofthe Environment, Japan (2004) (in Japanese)。
国内外铁路噪声污染研究
80 年代开始制定铁路边界噪声和铁路环 境振动标准；
90年代结合铁路建设项目境噪声预测评价 需要, 开展对铁路运行噪声传播规律、 铁路 噪声预测模式、机车风笛特性及常速铁路噪 声振动体制措施等相关内容的研究。
高速动车组降噪研究
以CRH冷却装置为例
国内外铁路噪声污染研究
铁道交通噪声
信
机
轮
号
车
轨
噪
噪
噪
声
声
声
(1)噪声对听觉系统的损伤； (2)噪声对人体生理的影响； (3)噪声对人们正常生活产 生不良影响； (4)噪声还能影响视力； 此外，强噪声会损坏建筑 物、机器设备，危害科研和 国防建设等。强噪声还可能 导致自动化设备、高精度仪 表火灵等。
国外铁路噪声的研究
国外铁路噪声控制研究
德国、荷兰、法国、瑞典、英国钢铁公司和英国商安普 敦大学声与振动研究所联合.从1997年开始到2000年,花费 374万欧元,研究轮轨噪声的机制, 以及降低噪声的措施。
在法国,法国国管铁路(SNCF)己经使用 TWINS软件对低 噪声的基本概念进行定义,对于速度达到350km/h的高速运 输进行了实验验证,并且以此开发一些低噪声零件样品。在 欧美、日本,对于铁路噪声的研究都取得了相当大的成果, 并根据振动的传播及声音传播过程:车辆、轨道、结构物、 基础、地基、建筑物,以及运助列车与空气之间的摩擦等综 合因素, 提出了一系列降低铁路嵘声的措施。
率特性集中在500--8000Hz范围内。距离铁路中心线25m，地面1.2m高处， 列车通过最大声级水平为75--76dB。新干线的噪声源强度见表1：
新干线采用的噪声控制措施
车辆措施 地面措施
汽车噪音震动论文英文版
Vehicle noise vibration and harshnessAbstractVehicle noise, vibration and harshness (NVH) is usually the major attribute because of its priority in the design of vehicles. NVH affects the design and manufacture process of a vehicle as higher customer satisfaction are attributed by a good NVH behavior. The research on NVH relies on a variety of computer software to improve and control NVH. In this paper, several vehicle components including rubber dampers and isolators which play an important role in controlling the NVH are presented. A description of source of NVH in a vehicle is shown.Keywords: NVH; rubber damper; isolator; research.1. IntroductionVehicles consist of space vehicles, airplanes, submarines, trains, road, off-road and others [1]. Vehicle noise, vibration, and harshness (NVH) is a major problem in the automobile manufacturing process and affects the customer satisfaction of automobile owners. The researches of vehicle noise, vibration, and harshness (NVH) are not only suitable for the design process of new automobiles, but contribute to improve the comfort and performance of current type of automobiles. Those researches are largely due to the increasing demands of vehicle manufacturers, Original Equipment Manufacturers (OEMs) and customers. The OEMs aim to look for the products that address issues of NVH, reduce vehicle weight, improve stiffness, and are easy to model, lower costs, and are environmentally friendly [2]. Automotive noise, vibration and harshness are the most important issues when the customers assess vehicle quality [1]. On the other hand, some manufacturers refuse to corporate automation into vehicle design, as addressing the issues of NVH which makes vehicles too quiet may pose a threat to the safety of pedestrians [4]. The vehicular noise can act as a warning signal for pedestrians.Some components in the vehicles play important roles in reducing NVH, namely rubber dampers, the power plants, chassis coupling, and elastomeric isolators.Rubber dampers insert between the fins and rubber dampers reduce the amplitude of vibration of fins which are used to speed up the heat transfer from the engine surfaces [3].In vehicles, the engine mounts affect largely the noise, vibration, and harshness comfort. The mounts are used to provide supports for the power plant and to isolate the vibrations of the power plant from the rest of the vehicles [6].A multiplicity of elastomeric isolators is needed, including engine mounts, suspension bushings, and frame and sub frame mounts [5]. Some functional requirements for isolators involve steering, braking, package, and durability, although these desired characteristics conflict frequently.2. The research on NVHFor vehicles, the issue of vibration, noise, and harshness (NVH) exists mainly in the engine, car body, and engine mounts. During the working of these components, they are affected by aerodynamic (NVH), air-conditioning system (NVH) and brake system (NVH). Vehicle NVH emphasis the feeling of human beings for vibration and noise and cannot be measured directly. The research on NVH consists of the comfort of passengers in vehicles and intensity problems of vehicle s’components caused by vibration. The research on the characters of vehicle NVH should concentrate on entire cars and separate entire cars into subsystems, such as engine system, engine mount system and car body system.The issue of vehicle NVH is not caused by relatively several reasons rather than simply one reason. For instance, the noise in the car may be due to the high level of noise of the engine, the pour isolation effect of suspension around the engine, or limited technology of sound-proofing between the car body and power system.There are some basic theories and methodologies helping understand and study the character of NVH.Finite element methods are to separate continuous elastomer into the limited number of units and calculate the system deformation, stress, and dynamics character through the finite element models on the computer. Because of the rapid development of finite element methods and the maturity of relative analysis software, FEM has become an essential method to analyze the character of vehicle NVH. FEM is suitable for the modeling analysis of vehicle body structure vibration and car interior cavity noise. On the other hand, combining FEM with multi-system dynamics to analyze engine mount system can increase the accuracy of dynamic character of the engine mount.BEM is short for the blade element momentum. Compared with FEM, BEM decreases the dimension of questions, making it convenient to handle the issues of unlimited field and establish the efficient network on the computer. The BEM theory is greatly employed for practical engineering application, especially in the field of NVH [16]. The shortage of BEM to address the problem of NVH is low speed of calculation.Experimental transfer path analysis (TPA) is a fairly well established technique for estimating and ranking individual low-frequency noise or vibration contributions via the different structural transmission paths from point-coupled powertrain or wheel suspensions to the vehicle body [11]. Experimental transfer path analysis is a favored technique to investigate further possibilities to fine-tune the rubber components of the engine and wheel suspension with respect to NVH.The experimental transfer path analysis method involves an indirect measurement procedure for estimating operating force components acting at the coupled DOFs (degree of freedom). TPA also involves a direct measurement of all transfer frequency response functions between response in points of interest and points where these forces act [11].Design of experiments method (DOE) can be used to minimize the transmittedengine- induced harshness to the body and improve a vehicle body structure. The DOE method includes factorial and response surface methods. The surface modeling is accomplished for the vehicle body with CATIA and HYPERMESH software which is used to create and optimize the FEA modal. NASTRAN software is used to analyze the modal in a frequency range between 0-50Hz [17, 18].3. The effect of rubber dampers on NVHThe rubber damper is an important type of equipment to reduce noise, vibration, and harshness (NVH), widely being used in a number of machines, vehicles, trains and aircrafts. The popularity of rubber dampers is due to the characteristics of rubber with high visco-elasticity and high elasticity. Compared with steel, elastic deformation of rubber is large and elasticity modulus of rubber is small. As well, rubber is considered as incompressible material.The function of rubber dampers between the fins is to make a compromise between vibration amplitude increases and fin base temperature decreases. Through the research on the effect of rubber dampers on the radiated noise from engine, it is concluded that the effect of the rubber dampers is to reduce engine high frequency noise level, which means the problem of vehicle noise vibration and harshness can be partly handled by using the rubber dampers. Engineers continue to work on the issues of high vehicle noise vibration and harshness when an engine does not rubber dampers with two methods. These two approaches are related to structural noise problems.The first method is to find ways of reducing the sound power by passive means and the other method is to use active control approaches. Compared with active control solutions which may be suitable in the future, passive control should not be ignored as it is useful for high frequency noise [3].Rubber dampers are not the only equipment using rubber in vehicles and some rubber connections are widely employed for structural parts. A change in rubber joint material properties can help evaluate the sensitivity of the full-scale system vehicle noise vibration and harshness (NVH) [7]. A three level modeling approach with a material, a component, and a system level has been introduced to evaluate the sensitivity of the NVH.4. powerplant mounting system NVHThe basic function of engine mount is to support the weight of power train and to isolate the vibration and harshness transmission from engine to body, to segregate the transmission from road surface excitation to power train [8]. As well, in order to lighten the car body, increase power-intensive engine and require vibration, noise, and harshness isolation for passenger cars, the performance of the powerplant mount system need to be improved. Many factors, such as the engine layout state, the supporting positions of chassis mount, the fixed positions on the cylinder of the mount and the layout of surrounding parts, should be considered before the designation of engine mount [9].The responses of the powerplant mounting system to low frequency vibrations are important for improving the NVH in terms of rigidity and damping. Some designs of powerplant mounting system try to handle the issues of NVH by concentrating on the positioning and design of resilient supports. However they fail to consider chassis and suspension system interactions as these designs are based on decoupling rigid body modes from a grounded powerplant mode.Fig.1. Powerplant mounting systemThe traditional engine mount design strategies consider only the rigid body modes of a grounded engine and arrangements of powerplant rigid body mode [6]. When considered as a rigid body, three translational modes and three rotational modes of frame represent the vibration, noise, and harshness (NVH) of powerplant using dynamic decoupling method. In detail, three translational modes are bounce, lateral, and longitudinal vibrations and three rotational modes are called by rotations about pitch, roll and yaw. It is believed that the vibration, noise and harshness (NVH) transferred to the car body structure can be reduced by conditioning the powerplant mounting system such that the powerplant oscillates about the torque axis [10]. The torque roll axis decoupling strategy controls the displacement of the uncoupled blocked powerplant. With less displacement of the powerplant, the level of NVH is reduced [6].The traditional design strategies sometimes may not put the issues of vehicle vibration noise and harshness (NVH) into consideration. With the development of technology and increasing demands of customers for comfort, the manufacturers and automobile companies begin to pay attention to design new powerplant mounting system. The current powerplant mounting strategies examine the rigid-body modes of the power train as it would sit on the mounts attached to the ground and neglect the effect of the chassis. The current engine mount system has achieved the goal that makes sure the driver and the passengers isolate from vibration noise and harshness (NVH) generated by the engine.5. Isolator on NVHElastomeric isolator and hydraulic isolator are widely used in automotive vehicle including shock absorbers, engine mounts and body mounts. Isolators can reduce vibrations and improve the ride performance experienced by drivers and passengers. Noise, vibration and harshness (NVH) are important to the consumer s’acceptance of a vehicle. Isolator s’type, sizing and placement are critical to NVH design [13]. The difference between elastomericisolator and hydraulic isolator is that hydraulic isolators are frequency dependent and elastomeric isolators are independent of frequency. It is largely because they use different mediums to dissipate mechanical energy.A hydraulic isolator connects a vibrating body and an isolated body in a vehicle and consists of a cylinder with two chambers and a piston. An electronic control system is required to cooperate with hydraulic isolator to supply an alternating current of appropriate amplitude and phase to several magnetic coils disposed adjacent to the tuning slug [12]. Matching the isolation frequency with the vibration frequency and adding energy to the vibration isolator to compensate for damping losses is the basic theory how no vibration is transferred from the vibrating body to the isolated body with the help of hydraulic isolator.Fig 4.1 hydraulic isolatorThe elastomeric isolators in the vehicles are separated into two kinds, namely rubber isolator and metal-net isolator. They are used for engines, especially for large power diesel engine. The metal-net isolator with the characters of nonlinear stiffness, large damping and power circumstance adaptability has advantages over rubber isolator and can be used as diesel engine’s mount component.Rubber isolators have been used in NVH control for years. Rubber is hyper elastic material and its suitability as isolator is due to good flexibility and resilience characteristics [14, 15].Rubber isolators cannot be used in low, high temperature, erode and toughcircumstance, e.g. in low temperature, rubber isolators have no isolating effect causing the aggravation of NVH and also can only isolate a single frequency vibration in any circumstance. It is due to the traditional design depending on experience and repeat experiment. Modern rubber isolator is designed with finite element method [14]. A modern rubber isolator is composed of steel and rubber. What differentiate modern isolator rubbers from traditional rubbers is that there are several holes. Those holes can effectively change the static and dynamic characteristics of rubber isolators. As a result, it manages to improve NVH with the improvement of performance of rubber isolatorsFig 4.2 rubber isolatorA metal-net isolator consists of the stainless steel web and the metal wire. When the force is on the stainless steel web, the metal wire slides and results in dry friction damping that absorbs and consumes the energy of system to approach isolating and cushion aims. The isolator’s elastic character is nonlinear, which has higher carrying capacity. Active isolation and passive isolation are two kinds of ways to isolate vibration with the use of metal-net isolator. Active isolation reduces vibration by isolating machine from vibration source and passive isolation relaxes the effect of external vibration [10].Fig 4.3 metal-net isolatorCompared rubber isolator with metal-net isolator, the transfer rate of metal isolator is smaller than that of rubber isolator, which means metal-net isolator has more ability to control NVH and absorb energy.6. ConclusionVehicle vibration, noise and harshness (NVH) has been receiving considerable attention for many years. The main sources of usual NVH are power engine, brake, suspension system, the steering system as well as other hardware of the vehicle. Also, the road NVH and wind NVH has become important issues as they dominate the medium and high speed ranges. In order to improve NVH, the performance of rubber dampers and isolator should be taken measured to improve.The paper gives a brief description of the current research of NVH, several modern methods such as finite element method and blade element momentum have already put into use. These methods greatly increase the accuracy and efficiency when addressing the issues of NVH.Two major components in a vehicle used to control NVH are introduced in the paper, namely rubber damper and isolator. The effect of rubber dampers is to isolate the engine NVH. Isolators are widely used in a vehicle and can be separated as elastomeric isolator and hydraulic isolator. The metal-net isolator has more advantage than rubber dampers. Engine and engine mount are the main sources of NVH. Some traditional engine mounting systems have shortages in design and manufacture.References[1] Mohamad, S. Qatu. “R ecent research on vehicle noise and vibration” , Int. J. Vehicle Noise and Vibration, Vol. 8, No.4, (2012).[2] Anita Carey and Kurt Lilley. Considering and comparing sealant option: a variety of cost-effective solutions, 2002.[3] Singh, O.P., Sreenivasulu, T., Kannan, M. “The effect of rubber dampers on engine’s NVH and thermal performance” , Applied Acoustics 75 17-26 (2014).[4] Nicholas D. Cottrell and Benjamin K. Barton. “The impact of artificial vehicle sounds for pedestrians on driver stress”,Ergonomics, Vol.55, 1476-1486 (2012).[5] Himes, R.S. and David Griffiths. “Future vehicle noise, vibration and harshness requirements for elastomeric isolators”, the Detroit Rubber Group meetin g, Detroit, the USA, September 2000[6] Courteille, E., Leotoing, L., Mortier, F. and Ragnean, E. “New analytical method to evaluate the power plant and chassis coupling in the improvement vehicle NVH”, European Journal of Mechanics A/Solids 24, 929-943 (2005). [7] Stenti, A., Moens, D., Sas, P. and Desmet, W. “A three-level non-deterministic modeling methodology for the NVH behavior of rubber connections” , Journal of Sound and Vibration 329 912-930 (2010).[8] Haran Periyathamby, Michael E. Anderson, David A. Nash and Y. Charles Lu. “NVH characteristics of thermoplastic composite engine covers”, Int. J. Vehicle Noise and Vibration, Vol. 5, No. 3, (2009).[9] Xiangming QIAN. “Research on Structural Design of Vehicle Engine Mount” , IEEE, 978-1-4577-0536-6/11 (2011).[10] Wenbing YAN, Shaozhong JIANG, Yujun CAI, Lizhi WEN and Yue CHEN. “Experimental Study of Engine Mount System’s Vibration Characteristics”, World Congress on Software Engineering, Tianjing, China, 2009.[11] Juha Plunt. “Finding and Fixing Vehicle NVH Problems with Transfer Path Analysis”, the Noise & Vibration Conference, Traverse City, MI, 16-19 May,.2005.[12] Zhixing Li, Shijian Zhu, Jingjun Lou and Simi Tang. “Simulation on Performance of Rubber Isolator Based on ANSYS”IEEE 978-1-4244-9439-2/11 (2011)[13] Chen-Ron Lin and Yu-Der Lee. “Effects of viscoelasticity on rubber vibration isolator design” , Journal of Applied Physics 83, 8027 (1998).[14] Dai, J.C., Hu, Y.P., Liu, D.S. and Long X. “Aerodynamic loads calculation and analysis for large scale wind turbine based on combing BEM modified theory with dynamic stall model” , Renewable Energy 36, 1095-1104 (2011). [15] Shahram Azadi, Mohammad Azadi and Farshad Zahedi. “NVH analysis and improvement of a vehicle body structure using DOE method” , Journal of Mechanical Science and Technology23, 2980-2989 (2009).[16] Shariyat, M. and Djamshidi, P. “Minimizing the Engine-induced Harshness Based on the DOE Method and Sensitivity Analysis of the Full Vehicle NVH Model”, International Journal of Automotive Technology, Vol. 10, No,6, pp. 687-696 (2009)...。
- 1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
- 2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
- 3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。
Proceedings of the International Conference on EnvironmentalEditors: A. Kungolos, K. Aravossis, Management, Engineering, Planning and EconomicsA. Karagiannidis, P. SamarasSkiathos, June 24-28, 2007, Pages: 2591-2596Road traffic noise reduction by vegetation in the ring road of a big cityTh. Samara 1and Th. Tsitsoni 2* 1Forest Research Institute of Thessaloniki, NAGREF, 57006 Vassilika, Thessaloniki, Greece 2Aristotle University of Thessaloniki, Department of Forestry and Natural Environment,Laboratory of Silviculture, P.O. Box 262, 54 124 - Thessaloniki*Corresponding author: E-mail: tsitsoni@for.auth.gr Tel: +30 2310 992763, Fax: +302310998881AbstractThis study was designed to investigate the traffic noise attenuation by vegetation along the ring road of Thessaloniki. Measurements were taken of road traffic noise at two areas, one through a belt of trees and the other above grass-covered ground. 245 measurements were taken in each area during a period of 2 months and expressed as differences in L Aeq (equivalent constant A- weighted sound pressure levels). Also there were measurements for the number of vehicles per minute, the type of vehicles and analytic description of vegetation at both areas. The results showed a significant noise reduction through the belt of trees rather than above grass-covered ground. According to the results of this research the largest reduction, 6 dB, was seen in the Pinus brutia belt, 60 m away from the road. This reduction of noise pollution is judged satisfactory because there are belts of trees on both sides of the ring road.Keywords: noise pollution; belts of trees; noise reduction; vegetation.1. INTRODUCTIONNoise is not simply a local problem, but global issue that should concern us all [1,2]. In the European Union over 40% of the population is exposed to noise of motorways to a level, which exceeds 55 dBA during the day and the 20% of the populations to levels that exceed 65 dBA [3]. Sound pollution continues to expand with an increasing number of complaints from the residents. Most people are usually exposed to more than one source of noise of which motorway noise is the main source [4]. In order to study noise, we must separate the different types of noise, the way that we measure them, their origin and their effects on people. In 1993, the World Health Organization (WHO) [5] recognized the following effects on the health of the population that can emanate from noise: sleep patterns, cardio respiratory and psycho physiological systems, and hearing. It also affects us negatively on intervention in communication, productivity and social behavior [6,7,5].The aim of this research is to locate and to evaluate the effect of vegetation on the reduction of circulatory noise that emanates from highways. In particular:1. Is circulatory noise decreased by vegetation and if yes by how much?2. Which are the characteristics of vegetation (type, structure) that affect the reduction of circulatory noise?3. What is the necessary treatment to be applied to vegetation for a great reduction in circulatory noise?2. MATERIALS AND METHODSMeasurements were taken at two different areas near residential zones each one 500 m 2. The first area is grassland while the second is forest of Pinus brutia. Both areas were 4 metres higher than the road and level (0-5%). The terrain was selected so that the two areas would be roughly similar.Environmental Management, Engineering, Planning and Economics2592In this way the sound distribution was not differently influenced.Noise intensity was measured using the Sound level Meter 407735 Extech Instrument, which has 2 measurement standards A and C, and we used only the A-standard [8]. The instrument was placed in height of 1,8 m above the surface as it is proposed by FHWA [9] and was turned to face the road. In both areas a straight line of measurement was made at right angles from the road to point 60 metres away. Measurements were made in 7 places every 10 metres along this line, starting at the edge of the road at point 0 [10,11]. In every place seven measurements were taken, each of 5 minutes duration. This was done 35 times in both areas over a period of 2 months from 9.00 a.m. to 2 p.m. In total 245 measurements were taken in each plot.In the forest area it was measured the main silvicultural parameters of the trees: height in m, diameter in cm and the crown length in m. The height and the crown length of trees were measured with the altitude Haga.All the measurements were computer registered with the use of statistical package of SPSS version 10.0 for windows. To check the effect of the vegetation factor on dependent variable highway noise the t-test was used [12] and the test Levene was used to check the homogeneity of fluctuation [13]. Diagrams of dissemination and the box-and-whisker plot on both areas studied were made.3. RESULTS AND DISCUSSIONThe mean circulatory pressure is 120.28(±7.67) vehicles/min, the number of big vehicles is 30.00(±1.95) vehicles/min and the proportion of heavy vehicles 24.85(±0.50) (all the measurement are represented as mean±s.e.). From 9 a.m. to 2 p.m. the Thessal οniki ring road is particularly busy and there is a high proportion of lorries. These heavy vehicles raise the level of noise as they pass (table 1). Table 1. The intensity of noise due to heavy vehicles.Surface Distance from street Noise intensity (dB) Intensity of noise with the passage of big vehicles (dB)Type ofvehicles40 65.2 67.3 lorry0 76.1 81.3 lorry 30 65.6 68.1 lorry 40 65.3 74.7 lorry 10 70.8 75.1 lorry 20 67.9 71.3 lorry 40 64.8 68.3 motorcycle0 81.0 86.1 lorry 50 62.7 70.0 lorry60 61.7 65.6 lorry0 77.9 92.9 ambulance*30 65.4 72.9 lorry10 72.7 77.7 lorry0 79.2 85.4 motorcyclegrassland0 78.5 85.2 lorry20 66.0 79.9 ambulance*0 80.2 90.1 lorry 0 80.4 83.2 lorry 0 78.8 83.2 lorry10 69.7 75.3 lorryforest10 69.5 77.8 lorry* The ambulance had in operation the sirens.Visual impact and noise pollution25933.1 Description of vegetationThe grassland is degraded with plants of families Compositae , Solanaceae and various other broadleaved plants. Horses occasionally graze there. The vegetation of the forest is reforestation of Pinus brutia with planted at 3x3m intervals. There are no bushes under the crown of the trees, only a few plants. The main silvicultural parameters of the green belt were: tree height 8.68(±0.22)m, tree diameter 18.94(±0.78)cm, the crown started above ground at 1.04(±0.17)m and finally the total crown length was 6.72(±0.19)m (all measurement are represented as mean±s.e.).3.2 Reduction of intensity of noiseIt was found that at 60m from the road the intensity of noise in the forest was on average 6 dB less than in the grassland. A presentation of the results of statistical analysis in the two surfaces is given in the table 2 and the figure1 with box-and-whisker plots.Table 2. Results of statistical analysis the values that are not followed by the same letter differ significantly (a=0.05, t-test).surface variable Distance from the road mean median standard deviation min max range Coefficientofvariation0 78.36a 78.40 0.86 76.181.0 4.9 1.09 10 71.80a 72.35 1.27 69.373.3 4.0 1.76 20 68.07a 68.00 0.49 67.368.8 1.5 0.71 30 65.50a 65.50 0.28 64.766.0 1.3 0.42 40 63.96a 63.75 0.64 63.065.3 2.3 1.00 50 61.94a 61.80 0.50 61.163.2 2.1 0.80grasslanddB 60 60.50a 60.45 0.6859.361.9 2.6 1.12 0 78.70a 78.55 0.69 77.680.4 2.8 0.87 10 69.56a 69.60 0.20 69.069.9 0.9 0.28 20 65.43a 65.40 0.29 65.066.0 1.0 0.44 30 62.51a 62.50 0.26 62.061.1 1.1 0.41 40 59.50a 59.50 0.27 59.059.9 0.9 0.45 50 56.51a 56.60 0.26 56.056.9 0.9 0.46 forestdB 60 54.72b 54.60 0.54 54.257.7 3.5 0.98From the table 2, the following was observed: At the distance 0m from the road, the factors of variation which are the unique characteristics of relative variation are big and in both cases. In the forest its value is 0.87, smaller than the value of 1.09 in the grassland.At a distance of 10m from the road the factors of variation in the grassland are prevailing in the forest than in the grassland.At the distance of 60m from the road the factors of variation of intensity of noise and in the two surfaces are roughly equal. This is due to the gap that exists in the forest from 50-60m, therefore there is no positive effect of the crown of trees and the sound behaves as in a region that does not have high vegetation.The box-and-whisker plot shows a graphic presentation of information on the distribution of data that are examined. The values of inferior and superior percentile (25th and 75th percentile) determine the beginning and the end of the box-and-whisker, which contains the intermediate 50% of prices of data. The horizontal line that cuts the box-and-whisker depicts the median.Environmental Management, Engineering, Planning and Economics25940 m 10 m20 m 30 m40 m 50 m60 mFigure 2. Box-and-whisker plots of intensity of noise at the grassland (1) and at the forest (2) atdistance 0,10,20,30,40,50,60m from the road.Visual impact and noise pollution4. CONCLUSIONSThe levels of noise pollution in the ring road of Thessaloniki are above the limits stated by Greek legislation 29087/2295 (67 dB). This is due to the high speed of vehicles, to the amount of traffic and to increased passage of heavy vehicles.By the analysis of the results, it can be understood that the vegetation functions as a plant noise barrier decreasing the intensity of the noise.- The vegetation can decrease satisfactorily the intensity of traffic noise in streets with rapid circulation. In the area of green with reforestations of Pinus brutia a bigger reduction was observed at 6 dB 60 m than in the grassland surface.- The reduction of noise pollution is judged satisfactory here because areas of green exist in most places on both sides of the road- In the existing areas of green that are found along the ring road the following characteristics of vegetation were recorded. The high vegetation constitutes only of trees of Pinus brutia.5. PROPOSALS- Evergreen bushes (2-3 metres height) should be planted in rows close to the road edge. Ligustrum vulgare, Pitosporum tobira, Pyracantha coccinea and Phillyrea latifolia are suggested [14]. Then a tree barrier should be planted. These trees must be of at least 15 metres height when mature. This combined green zone must be at least 20 metres in depth.- As well as coniferous trees, deciduous trees may also be planted such as Cercis siliquastrum, Celtis australis, Fraxinus ornus, Ostrya carpinifolia, Carpinus orientalis and Acer campestre. Also it should be used the suitable tree species according to the prevailing circumstances in the urban and periurban environment [15,16,17,18,19]. It is suggested avoiding the use of Olea europea as its blossom is an allergenic [20]. It can only be used if pruned regularly so that it does not blossom, but also dense hedges are formed.Referencesng, W.W., 1999. Is noise policy a global issue, or is it a locl issue?. In: Cuschieri J., Glegg S.and Yan Yong (eds.). Internoise 99- The 1999 International Congress on noise Control Engineering, December 1999, Fort Landerdale, Florida. USA, 1939-1943.2.Sandberg, U., 1999. Abatement of traffic, vehicle and tire/road noise- the global perspective. In:Cuschieri J., Glegg S. and Yan Yong (eds.). Internoise 99- The 1999 International Congress on noise Control Engineering, Decamber 1999, Fort Landerdale, Florida. USA, 37-42.mbert, J., Vallet, M., 1994. Study Related to the Preparation of a Communication on aFuture EC Noise Policy. INRETS LRN Report No. 9420, INRETS- Institut National de Recherche sur les Transports et leur Securite, Bron, France.4.OECD-ECMT, 1995. Urban Travel and Sustainable Development. European Conference ofMinisters of Transport, Organization for Economic Co-operation and Development, Paris, France.5.WHO, 1993. The Environmental Health Criteria Document on Community Noise. Report on theTask Force Meeting, Dusseldorf, Germany, November 1992. WHO Regional Office for Europe, Report EUR/HFA Target 24, World Health Organization, Copenhagen, Denmark.6.Berlund, B., Lindvall, T., 1995. Community noise. Document prepared for the World HealthOrganization. Archives of the Center for Sensory Research, 2, 1-195.7.Tsitsoni, Th., Batala, E., Zagas, Th., 2005. Management of urban and suggestions for itsupgrade in the Municipality of Thessaloniki. Proceedings of the 12th Panhellenic Forest Science Conferenc e, October 2-4, Drama, Greece, 231-242 (in Greek).2595Environmental Management, Engineering, Planning and Economics8.Caltrans, 1998. Technical Noise Supplement. Enviromental division, noise and vibration studies.California Department of Transportation.9.FHWA-INM, 1998. Federal Administration Traffic Noise Model, Version 1.1. US Departmentof Transportation, Washigton, DC.10.El-Fadel, M., Shazbak, S., Hadi Baaj, M., Saliby, E., 2002. Parametric sensitivity analysis ofnoise impact of multihighways in urban areas. Enviromental Impact Assessment Review, 22, 145-162.11. Pal, A.K., Kumar, V., Saxena, N.C., 2000. Noise attenuation by green belts. Journal of Soundand Vibration, 234 (1), 149-165.12. Snedecor, G.W., Cochran, W.G., 1988. Statistical methods. The Iowa State University Press,507.13. Matis, K., 1991. Forest Biometry Ι. Statistics. (G. Dedousis eds.), 67-68 (in greek).14. Tsitsoni, T., Samara, Th., 2002. The existing situation and management of urban forests andtrees in western Macedonia. Proceedings of the 10th Panhellenic Forest Science Conference, May 2002, Tripoli, Greece, 136-147 (in greek).15. Ganatsas, P., Tsitsoni, Th., Zagas, Th., Tsakaldimi, M., 2002. Proceedings of the 10thPanhellenic Forest Science Conference, May 2002, Tripoli, Greece, 627-637 (in greek).16. Samara, Th., Tsitsoni, T., 2003. Tree quality control and care measures in urban enviroment.Proceedings of the 11th Panhellenic Forest Science Conference, October 2003, Ancient Olymbia, Greece, 705-721, (in greek).17. Tsitsoni, T., Zagas, Th., 1999. Estimation of Adaptability of Tree Species on the Basis of TreeCondition and Human Activities. Proceedings of the Urban Greening and Landscape Architecture research symposium. Thomas B. Rundrup (ed.). Copenhagen, Demark, June 1999, ISBN 87-7903-040-8, ISSN 1399-2163.18. Tsitsoni, T., Zagas, Th., 2001. Silvicultural measures for improved adaptability of tree speciesto the Urban Environment. Proceedings of International Conference ‘ECOLOGICAL PROTECTION OF THE PLANET EARTH. June 2001. Xanthi, Greece, Vol.1: 415-422.19. Zagas, T., 1999. Early Growth of Silver Lime Trees in the City of Thessaloniki. Proceedings ofthe Urban Greening and Landscape Architecture research symposium. Thomas B. Rundrup (ed.). Copenhagen, Demark, June 1999, ISBN 87-7903-040-8, ISSN 1399-2163, 122-123.20. Papageorgiou, V., Papajiotidis, S., Zagas, T., Athanasiadis, N., 2002. Allergic consequences ofplants in urban areas: an unknown underestimated parameter’. Proceedings of the 10th Panhellenic Forest Science Conference, May 2002, Tripoli, Greece, 148-155 (in greek).2596。