查询词典 transient time

The main work and the originality points of this dissertation could be concluded as the following parts:(1) To analyze systematically the mathematical model of LES of air flow in great space, under the case of isothermal and non-isothermal, as well as the combined action of buoyancy and strain. Some basic problems are studied about the LES application into airflow simulation of great space, such as boundary conditions, spatial difference scheme and time advancing scheme, time step etc., which creates the basis for the LES application to indoor airflow simulation.(2) Both the instantaneous and time averaged flow field of great space with multiple jets under isothermal and non-isothermal cases are explored with large eddy simulation method, and also discussed the dynamic characteristics and the law of fluidflow in the great space.(3) Based on the results of LES of the great space and the Fanger thermal comfort indexes, it is brought forward the concept of the series of dynamic thermal comfort evaluating indexes, which could be divided into thermal comfort index with time averaged properties PD, PPD, PMV, thermal comfort index with instantaneous properties IPD, IPPD, IPMV, and time averaged thermal comfort indexes TAPD, TAPPD, TAPMV, and transient situations time averaged thermal comfort indexes TTAPD, TTAPPD, TTAPMV. The differences among them and the calculation methods are discussed, and the four kinds of indexes are calculated with the thermal comfort index PD as an example.(4) Based on the LES results it is discussed the hot air stratification phenomena in air-conditioned buildings in the case with air supply and return registers on the ceiling and the case on the sidewall. The fundamentals of the hot air stratification are studied and the relations of estimating hot air stratification are brought forward.(5) With the advanced apparatus such as hot wire film anemometer IFA300 and laser particle field anemoscope, corresponding model test and site measurements have been done, which are compared with the simulation results and LES is proved a very promising method in air flow simulation indoor.

本文主要工作既创新点体现在以下几个方面：(1)系统分析了等温、非等温和考虑剪切力与浮升力综合作用的高大空间大涡模拟数学模型，并研究了高大空间大涡模拟在室内气流仿真应用中的一些基本问题，如边界条件、空间离散格式和时间推进格式、时间步长选择等问题，为大涡模拟在室内气流计算中的广泛应用打下了基础；(2)首次用大涡模拟方法研究了高雷诺数下高大空间多射流在等温、非等温情况下的瞬时流场和时均流场分布，并探讨了多射流流场的动态特性和流动规律；(3)基于大涡模拟的动态仿真结果和Fanger的热舒适指标，首次系统地提出了动态热舒适评价指标体系的概念：即基于时间平均参数的热舒适指标PD、PPD、PMV；基于瞬时参数的瞬时热指标IPD、IPPD、IPMV；基于时间平均热舒适指标TAPD、TAPPD、TAPMV；以及沿行动迹线的时间平均热舒适指标TTAPD、TTAPPD、TTAPMV，并分析了四类热舒适指标的差异性和计算方法，还以PD值为例对四类指标分别进行了计算；(4)基于数十种工况下空调房间大涡模拟的结果，研究了空调建筑上送上回和侧送侧回两种情况下热分层现象，并探讨了热分层的基本规律，首次提出了避免热分层现象的判断公式；(5)在暖通空调领域，首次使用IFA300热线风速仪、激光粒子速度场仪等先进设备，完成了与大涡模拟相对应的模型试验，并把实测结果与仿真结果进行了对比，说明LES在室内气流仿真方面是一种很有前景的方法。

This paper analyze and study the influence of the superimposition in depth based on the previous achievements and combined with the theoretical qualitative analysis and project instances. The main contents as follow:Chapter 1: Indicate the significance and objective of this paper, review the previous achievements of the transient process and superimposition, and then present the study purpose of this paper.Chapter 2: combined with the physic knowledge of the fluctuation and the superimposition, Indicate the physical essences and the influence of the superimposition phenomena that exist in the diversion pipe system, and take one hydraulic turbine owning only one diversion tunnel and two hydraulic turbines sharing one tailrace conduit for instance to study out the numerical calculation superimpose operations.Chapter 3: From the calculation theory of the parameter of the guaranty calculation of regulation of the hydro-turbine, qualitative analyze the influence of the superimposition on them and the superpose time, combined with some project instances, get the numerical value of the influence of the superimposition and the superpose time.Chapter 4: Based on the previous achievements of the calculation and theoretical analysis of the surge-chamber ground swell, analyze the influence of the superimposition on it and the superpose time.

本文在前人研究成果的基础上，结合理论定性分析及工程实例，对波动叠加带来的影响进行深入分析研究，其主要内容如下：第1章，指出本文研究的意义和目的，回顾前人对水电站过渡过程及波动叠加方面的有关研究成果，在此基础上提出本文的研究内容；第2章，结合物理学中有关振动与波动叠加方面的有关知识，阐述水电站引水发电系统中存在的波动现象的实质及其影响，并以两机一洞和一机一洞具有上游调压室或下游调压室的水电站拟定其数值计算叠加工况；第3章，从机组调保参数的理论出发，定性的分析波动叠加对机组调保参数的不利影响及叠加时间，结合几个工程实例，得到波动叠加带来的影响大小及叠加时间；第4章，在前人对调压室涌浪进行计算和理论分析的基础上，分析波动叠加对调压室涌浪的影响及其叠加时间。

A key point in Short Time Fourier Transform is the choice of window function. Although rectangle window is regarded as the first choice because it's featured by integral harmonic to filter signals and by DC component, decaying DC component and frequency shift of signals cause great error to rectangle window STFT. In addition, transient signals contain rich information of faults, but the fixed time window of STFT fail to collect these information.

STFT 算法关键问题之一是窗函数的选择，矩形窗以滤除信号整数次谐波和直流分量的特点自然称为首选窗，但衰减直流分量和信号的频率偏移对矩形窗 STFT 造成了很大误差；其次，暂态信号中含有丰富的故障信息，傅立叶变换固定的频窗忽略了这些特征信息。

In the meantime, we got several achievements during the process:Firstly, a sequence encryption algorithm of real-time video in use of one dimension piece-wise linear chaotic map is carried out. This algorithm makes use of Inter' s SSE2 special dictates and makes nonlinear change of chaotic sequences.As a result, the algorithm not only encrypts faster, but also resists several cipher analysis methods. Secondly, this paper presents a block encryption algorithm of real-time video based on chaotic neural network which makes use of numerical transient chaotic neural network to produce chaotic sequences and uses these sequences to do encryption.

同时，在实现系统的过程中，取得了以下研究成果：(1)提出了一种利用一维的分段线性混沌映射来对实时视频进行序列加密的算法，该算法利用Inter的SSE2专用指令集来实现，并对产生的混沌序列进行了有效的非线性变换，从而使该算法不仅加密速度快，并且能有效的抗多种密码分析；(2)提出了一种利用混沌神经网络对实时视频进行分组加密的算法。

After the transient temperature distribution has reached dynamic equilibrium, because of radius temperature gradient periodically changing with time, the optical path difference between center and edge beam is also periodically changing with time.

当晶体温度达到周期性分布后，由于晶体径向温度梯度的周期性变化，引起通过晶体的平面光波的中心和边缘光线相对光程差也随时间作周期性变化。

Several transient compounds were synthesized by the homo- and heterogeneous reactions of reactive halogen compounds, In-situ ultraviolet photoelectron spectroscopy and photoionization mass spectroscopy as well as theoretical calculations were used to study their molecular structures, stability and molecular orbital properties, their electronic structures and geometric structures were obtained for the first time; Simultaneously, the electronic structure and thermal dissociation of acetyl peroxynitrate and trifluoroacetyl peroxynitrate which have great importance in the atmospheric chemistry were studied; The substituent effects of series of halopyridines and halothiophenes were studied by the ultraviolet photoelectron spectroscopy method for the first time. The atmospheric chemical reaction between peroxyacetyl radicals with IO radicals as well as the dissociation of the most stable isomer of CH3COIO3 were calculated by density functional theory, it was found that the CH3COOIO2 isomer may be act as a new reservoir of inorganic iodine in the stratosphere.

通过活性卤素的系列均相与非均相化学反应合成了几种瞬态物种，采用原位紫外光电子能谱和光电离质谱结合量子化学理论计算对化合物的分子结构、稳定性以及分子轨道特性进行了研究，首次获得了这些物种的电子结构和几何结构的信息；同时研究了大气中有重要作用的乙酰过氧硝酸酯和三氟乙酰过氧硝酸酯的电子结构性质及热解过程；采用紫外光电子能谱手段首次研究了系列卤代吡啶和噻吩的取代基效应；通过量子化学理论计算研究了乙酰基过氧自由基与IO自由基的大气化学反应及其最稳定异构体CH3COOIO2的解离，发现该物种可能是无机碘化合物在平流层中的储库物种。

In this dissertation, high-speed CCD camera was used as the image system. An eight-wave retardation plate was added within the optical path to remove the phase shifting device. By means of short exposure time and precise time sequency control, transient information in a series of time scales could be obtained successfully.

本研究承续前人的努力采用高速CCD为取像系统，但改於光路中加入八分之一波板於光路中来取代传统的相移机构，再藉由极短的曝光时间和时序控制成功取得了振动物体一系列连续时间点之暂态资讯。

The time constant reflects directly the transition time of circuit transient.

时间常数直接反映了暂态过程的持续时间。

Numerical method for calculating the exact all-time apparent resistivity for time domain transient electromagnetic method is proposed in this paper.

bstract 给出了一种时间域瞬变电磁法视电阻率的数值计算方法，利用该方法可以容易地求出中心方式的全程视电阻率。

A numerical method for calculating the exact all-time apparent resistivity for time domain transient electromagnetic method is proposed in this paper.

给出了一种时间域瞬变电磁法视电阻率的数值计算方法，利用该方法可以容易地求出中心方式的全程视电阻率。

I am sure after a few weeks of adaptation and familiarization I will have no difficulty in functioning on a daily basis in an English speaking society or in participating fully in graduate studies.

在大学的三年的学习生活不仅给予我自身的充实，更重要的是磨练和培养了我较强的自觉能力和严谨，踏实的作风以及不怕困难的精神，对未来充满了信心！

As the first volcanoes erupted, one of the gases that bellowed out was steam.

在第一批火山喷发时，喷出的气体之一就是水蒸汽。