Based on the Characteristics of Respondents and the Voice of the Urban Neighborhood Public Space Business Facilities Noise Environment Evaluation Research

Comfort is one of the important indicators evaluation of voice. In order to understand the urban neighborhood public space environment of comfort,this paper is to explore characteristics of consumer society on the public space environment evaluation of the effect,and using the questionnaire survey method,to evaluate the Harbin city neighborhood area public space as the typical case analysis. Based on one of the main sound source in neighborhood public space,environment,business facilities environment as the breakthrough point,it is to consider neighborhood public space environment evaluation and social characteristics.

A pilot project of ambient noise tomography on a dense seismic array in Ji'nan urban area

In this study, we conducted ambient noise tomography(ANT), with 33-day data, to investigate the nearsurface shear-velocity structure in downtown Ji’nan, Shandong Province, China. The cross-correlation functions with quiet clear Rayleigh waves are obtained with more symmetrical energy distribution which indicates that strong human activities, such as moving vehicles and municipal engineering construction, can produce approximately isotropic distribution of noise sources for high-frequency signals. The direct surfacewave tomographic method with period-dependent ray-tracing is used to invert all surface-wave dispersion data in the period band 0.2–1.5 s simultaneously for 3D variations of shear-velocity structure. The study result can help us better understand the local geologic structures, evaluate the distribution and geometry of the fracture-karst media, and assess hazards of the concealed active fault and its effect on the springs in the future.

ON THE NECESSARY AND SUFFICIENT CONDITIONS TO SOLVE A HEAT EQUATION WITH GENERAL ADDITIVE GAUSSIAN NOISE

In this note, we consider stochastic heat equation with general additive Gaussian noise. Our aim is to derive some necessary and sufficient conditions on the Gaussian noise in order to solve the corresponding heat equation. We investigate this problem invoking two differen t met hods, respectively, based on variance compu tations and on pat h-wise considerations in Besov spaces. We are going to see that, as anticipated, both approaches lead to the same necessary and sufficient condition on the noise. In addition, the path-wise approach brings out regularity results for the solution.

Adjustment Model and Colored Noise Compensation of Continuous Observation System

The affection caused by the colored noises should be taken into account to the adjustment model.As useful signals,these colored noises should be accurately identified and extracted by Fourier analysis.A continuous adjustment model is introduced with respect to the colored noises,and then it can be generalized from the finite space to the infinite space so called as Hilbert space.This extension is to provide a new technique to perform the continuous observational system design,Fourier analysis as well as the parameter estimation.It shows that the Gramer’s determinant provides maximization criteria in the system optimization design as well as a rule in diagnosing the adjustment model.Related with the definition of the integral,the least squares solution of the continuous adjustment model becomes the limit of the traditional least squares solution in finite space.Moreover,the influence caused by the colored noises is systematic,but it can be eliminated or compensated by optimally designing the observational system.

Research of Background Noise Characteristics of the Zhangzhou Seismic Array

The data recorded during the site survey in the Zhangzhou area in Fujian Province between October 23, 2007 and December 3, 2007 was analyzed. The main methods adopted for the noise level of this area are the noise root mean square( RMS),noise power spectrum density and noise coherency function. The results indicate that the noise levels of the survey sites are higher in the 1 s-10 s periods,which is the main frequency band of preliminary microseism,and also,two main noise sources were found in 1. 5 Hz and around 5 Hz. According to arithmetic,the direction and frequency band of the noise source were analyzed and academic proofs were presented. At last,we found that the noise source in 1. 5 Hz was made by the water wave aroused by the wind in the reservoir region and the noise source around 5 Hz was made by the power station in the northeast direction.

Urban avifauna distribution explained by road noise in an Eastern European city

In Eastern Europe,efforts are being made for road infrastructure development,as this area has not yet reached the level of that in the West.Road noise negatively affects birds,especially in urban habitats.Therefore,seven green spaces from an Eastern European city were monitored,which were selected according to the urbanization gradient and the hydrographic peculiarities of the area.The correlation between species richness and human population density,urban mobility,or road noise was verified.These three factors together explained over 99%of species richness distribution in habitats and during study periods.Road noise was the strongest predictor and the most negative influencer of bird species.These correlations were higher when we also considered the variability of species in habitats over time,instead of the total species richness of a habitat,as it expresses more accurately the impact of noise on the presence of species.The presence of species has decreased from one habitat to another along the urbanization gradient,from the edge of the city to the center,both in the case of terrestrial and aquatic green spaces.The most central park differed significantly from the other terrestrial green spaces in the city.At the same time,no significant differences were registered between the aquatic habitats or the rest of the terrestrial habitats.The ideal mitigation measure in this case would be that there are no roads in the immediate vicinity of green spaces.Still,if this is not possible(as in the case of all the existing green spaces in a city),we discuss/recommend placing noise barriers at the edge of green spaces or high-speed roads.

Ambient Noise Tomography of Jinan:The Migration of Groundwater and the Formation of Geothermal Water

Jinan is an important city in eastern China,with rich groundwater in the region.There are four famous springs in the urban area and an abundance of geothermal water in the northern part,which makes the migration of groundwater in this area a very important issue.To study the shallow shear wave velocity structure and groundwater migration in Jinan,we utilized almost a month of continuous waveform data from 175 short period seismometers deployed by the Chinese Academy of Geological Sciences,in order to calculate the cross-correlation function.We picked 7749 group dispersion curves and 6117 phase dispersion curves with a period range of 0.2–2 s.Through inversion,we obtained the fine threedimensional shear wave velocity and azimuthal anisotropy structure(0–2.4 km).Combining the results with local geological and hydrological data,the following conclusions were reached.(1)There are widespread high velocity anomalies in the region between the Qianfoshan and Wenhuaqiao faults,as well as to the east of the Wenhuaqiao Fault,which may be related to the intrusive gabbro known as the Jinan Intrusive Rock.(2)The two distinct high velocity anomalies in our model(referred to as west and east Jinan Intrusive Rock in this paper)may indicate that the Jinan Intrusive Rock was broken through crustal movement.(3)There is an obvious low velocity layer under the intrusive rock,which could be the channel of groundwater migration.The precipitation in the southern mountain region seeps down into the ground,then is blocked by the Jinan Intrusive Rock and can only progress downwards to a deeper part,where the groundwater is heated by the geothermal gradient.The heated water finally arrives at the northern part and forms geothermal water.(4)The depth of the low velocity layer beneath the Jinan Intrusive Rock varies laterally,which may indicate that the depth of the groundwater migration is different beneath the west and east Jinan Intrusive Rock.(5)There is strong azimuthal anisotropy in southern Jinan,with nearly E-W fast orientation,which may be related to the tilt limestone layering structure.

Species-Related Difference to Noise Reduction Between Trees in Urban Forest: The Abidar Forest Park (Case Study)

Sound pollution is one of the most important urban problems which endangers mental and physical health of the residents.This study was aimed to assess the influence of different tree species,including Fraxinus rotundifolia,Robinia pseudoacacia,Platanus orientalis,Platycladus orientalis,and Pinus eldarica,in reducing noise pollution in the Abidar Forest Park.A further objective was to identify the contaminated areas of Sanandaj city and to propose suitable noise absorbent tree species in consistent conditions.For each tree stands the noise measurements were performed during intervals at frequencies of 250,500 and 1000 Hz,besides an open area with the same topography.With regards to the second purpose,a total of 50 stations with residential,commercial,residentialcommercial,and green space applications were selected across the city.Equivalent Continuous Sound Pressure Level(Leq)was determined in five replicates for 30 min.The measurements were performed under stable weather conditions and low wind velocity at 17:00(traffic peak)in summer and fall.All of the Leq values were above the threshold noise level.The highest noise reduction was recorded in summer(i.e.,green season);Platanus and Platycladus species demonstrated the highest and lowest noise absorption(31.43 dB and 22.28 dB,respectively).Furthermore,a meaningful difference was observed between Leq values of commercial,residential,commercial-residential,and green space urban applications,and the central parts of the city showed noticeable noise pollution.Taken together,due to being exposed to higher than the acceptable threshold noise level,the residents of Sanandaj will be endangered to health problems in the near future;thus consideration should be given to the noise pollution sources.

Prediction of seawater pH by bidirectional gated recurrent neural network with attention under phase space reconstruction:case study of the coastal waters of Beihai,China

Marine life is very sensitive to changes in pH.Even slight changes can cause ecosystems to collapse.Therefore,understanding the future pH of seawater is of great significance for the protection of the marine environment.At present,the monitoring method of seawater pH has been matured.However,how to accurately predict future changes has been lacking effective solutions.Based on this,the model of bidirectional gated recurrent neural network with multi-headed self-attention based on improved complete ensemble empirical mode decomposition with adaptive noise combined with phase space reconstruction(ICPBGA)is proposed to achieve seawater pH prediction.To verify the validity of this model,pH data of two monitoring sites in the coastal sea area of Beihai,China are selected to verify the effect.At the same time,the ICPBGA model is compared with other excellent models for predicting chaotic time series,and root mean square error(RMSE),mean absolute error(MAE),mean absolute percentage error(MAPE),and coefficient of determination(R2)are used as performance evaluation indicators.The R2 of the ICPBGA model at Sites 1 and 2 are above 0.9,and the prediction errors are also the smallest.The results show that the ICPBGA model has a wide range of applicability and the most satisfactory prediction effect.The prediction method in this paper can be further expanded and used to predict other marine environmental indicators.

超长空间激光传输数值模拟研究进展

文章主要围绕空间引力波探测中超长空间链路传输部分进行介绍,概述了目前国内外星间传输仿真时采用的计算方法,以及指向抖动引起的相位噪声分析方法。相较于地基引力波探测,空间引力波探测可以有效降低噪声,增加干涉臂长度,从而实现更高精度、更低频率的探测。在长达数百万公里的传输距离,以及皮米量级数值模拟的精度要求下,需要考虑指向角变化引起的相位噪声。研究表明,在2.5×10~9 m的传输距离下,离焦和像散是影响指向抖动噪声的主要像差。通常情况下,相位驻点位置与原点位置存在一定偏离,需要对望远镜角度进行调整,才能使相位噪声最小化。在相位驻点位置进行引力波探测,可以有效降低相位噪声,并降低望远镜出瞳波前的质量要求。而大的离焦像差与小的彗差可以使相位驻点接近光轴,提高接收到的激光功率。

采用多丝正比室读出的屏栅电离室能量分辨研究

搭建了一个基于多丝正比室读出的屏栅电离室探测器,使其保留屏栅电离室屏蔽特性的同时具备雪崩放大功能,通过在探测器内部对原初电离信号进行预放大,以提高信噪比,改善探测器的能量分辨率。利用241Am源详细测试了探测器在不同气压、沉积能量、阳极丝径时能量分辨率及增益随阳极电压的变化关系。探测器最佳能量分辨对应的工作电压与入射粒子在漂移区中沉积的能量有关,能量沉积越小,对应的最佳工作电压越高,探测器的增益越大。对于5.486 MeV的241Am α粒子源的能量分辨率可达1.45%。

面向TDI技术地面验证的激光干涉仪本底噪声分析

在空间引力波探测中,由于星间激光干涉臂不等,导致激光频率噪声不能共模消除,从而使微弱的引力波信号被激光频率噪声淹没。时间延迟干涉(TDI)技术通过将激光相位数据在时间上延迟,构成虚拟等臂干涉,从而能减小激光频率噪声对引力波信号探测的影响。为了在地面验证TDI技术能够将激光频率噪声对引力波探测的影响降低至3×10^(-7) Hz/√Hz(傅里叶频率1 mHz处),需要分析TDI地面验证系统本底噪声的主要来源。通过实验测量和计算分析,提出了面向TDI技术地面验证的激光干涉仪的重要参数设计要求,包括激光干涉臂的臂长差、激光频率稳定度、气压稳定度、激光功率稳定度以及各部件温度稳定度等。

惯性空间TDI相机长弧段星源主动扫描设计

为了有效扩大惯性空间观测的幅宽范围和成像信噪比,提出了一种基于星等与光学多参量的映射函数的卫星与载荷姿频协同补偿的TDI相机长弧段星源主动扫描设计方法。首先,基于黑体辐射能量密度公式,构造TDI光学参量与极限探测星等之间的映射函数;然后,采用齐次坐标变换和欧拉轴最优路径规划方法,建立惯性空间卫星恒速机动和载荷动态实时补偿的长弧段星源扫描成像模型,完成动态星源无拖尾高信噪比成像。最后,基于平行实验理论,搭建由TDI相机和动态星源模拟器组成的实验系统,并完成了扫描成像实验和误差分析。实验结果表明,本体坐标系相对惯性坐标系的欧拉角速率为8.5(°)/s时,积分级数为96,TDI相机行频为1 kHz,成像时长10 s,TDI相机成像过程中星图成像信噪比最大值为7.325,扫描区域立体角为5.4232 rad。惯性空间TDI相机长弧段星源主动扫描可实现对星源高信噪比成像,并大幅拓展了成像观测范围。

大坝安全监测数据降噪的流形学习方法

针对大坝变形、渗流、应力应变等安全监测数据难以避免受到噪声污染,且传统线性降噪方法去噪效果不佳的问题,提出了基于相空间重构与流形学习相组合的大坝安全监测数据非线性降噪方法。该方法在重构大坝安全监测数据时间序列相空间的基础上,通过交叉应用局部切空间排列方法与极大似然估计、自适应邻域等方法,以重构的相空间为桥梁,提取大坝安全监测数据序列深层次信息,得到降噪后的大坝安全监测数据。工程实测数据验证结果表明,相比小波软阈值法和固定邻域-LTSA法,本文提出的方法降噪效果更优,具有一定的工程应用价值。

非机械指向空间激光通信接收系统设计与分析

采用非机械指向结构能够极大缩小空间激光通信系统尺寸与重量,由于现有器件性能局限,目前尚未见到成熟的非机械指向空间激光通信接收系统。提出基于正交液晶级联偏振光栅与四象限探测器的空间激光通信接收光学系统,利用了正交液晶级联偏振光栅体积小、口径大、偏转范围大,及四象限探测器接收角度范围大的优势,根据正交液晶级联偏振光栅与四象限探测器的理论与器件性能,设计了光学系统,分析了探测器噪声、背景噪声、系统噪声对于通信与入射角度测量的影响,计算了可实现的通信速率,给出了系统的最大响应角速度。

基于量子Bernoulli噪声的一维时空非齐次开放量子游荡

用量子Bernoulli噪声方法研究一维时空非齐次开放量子游荡,给出该游荡的演化性质以及极限概率分布,并表明以局部基态作为初始态时,基于量子Bernoulli噪声的一维时空非齐次开放量子游荡具有与经典随机游荡相同的极限概率分布.

空间引力波探测望远镜多自由度形变测量方法解耦研究与噪声分析

空间引力波探测望远镜是引力波探测卫星的核心载荷之一,它同时对传输光束进行扩束和缩束。光程稳定性是望远镜的核心指标之一,其与望远镜结构稳定性密切相关。为了满足引力波探测任务对望远镜提出的超高光程稳定性和结构稳定性要求,必须对望远镜结构形变测量进行研究。本文开展了对空间引力波探测望远镜多自由度形变测量的研究,重点解决多自由度测量的耦合问题,并对误差来源进行详细分析。在空间引力波探测望远镜的研制阶段,该测量方法的研究有望满足望远镜多自由度形变测量的需求,为望远镜设计提供多自由度形变的数据反馈,为望远镜光程稳定性研究提供指导。

GNSS对流层湿延迟随机游走过程噪声时空变化特征分析

全球导航卫星系统GNSS对流层天顶湿延迟(zenith wet delay,ZWD)随机噪声不仅影响ZWD估计值大小,还会影响ZWD的趋势项变化。为揭示ZWD随机游走过程噪声(random walk process noise,RWPN)的时空变化特征,本文选取全球20个IGS(International GNSS Service)测站,基于JPL(Jet Propulsion Laboratory)、GFZ(Helmholtz-Centre Potsdam-German Research Centre for Geosciences)和CODE(Center for Orbit Determination in Europe)分析中心2010至2020年对流层产品,从不同地理位置和不同时间序列分析GNSS ZWD随机游走过程噪声的变化范围和特征;并且在扣除ZWD的趋势项和主要周期项后,进一步揭示了ZWD残差信号分量构成。结果表明:不同地理位置湿延迟RWPN具有显著差异,年均值范围在0.01~0.146 mm/√s之间,且在大气集中的中低纬地区湿延迟RWPN值较大,在大气相对稀薄的极地地区其值较小;同一测站的湿延迟RWPN具有明显的周年、半周年和季节性特征,极差值高达0.12 mm/√s以上;通过对ZWD残差值分析,发现ZWD残差信号除包含白噪声外,还具有4.8 h至2.43 d的高频信号分量。