查询词典 numerical coefficient

According to by the time series estimate power spectral density\'s periodogram law principle,the research adopts five level of orbital power spectra which US Federal railway Administrative bureau FRA proposed;then,through the Fourier inverse transformation,the orbital not smooth time domain samples are obtained, which determine the track irregularity peak-to-peak value and the corresponding wave length; on the basis of the research,the influence of the wheel track dynamic contact force are considered.Based on the orbital roadbed coefficient\'s definition,computation model is established to solve the roadbed equispaced spring constant,and the roadbed uniform spring stiffness is obtained by using the numerical simulation method.Finally,based on the Matlab procedure platform,the computational procedure is established,and the load time interval caused by the moving train acts on the roadbed is obtained.

根据由时间序列估计功率谱密度的周期图法原理，采用美国联邦铁路管理局FRA提出的五级轨道功率谱，通过Fourier逆变换得到轨道不平顺的时域样本，确定了轨道不平顺的幅值及对应的波长，以此为基础考虑轮轨动态接触力的影响；基于轨道路基系数的定义建立了求解路基均布弹簧刚度的计算模型，采用数值模拟得到了路基均布弹簧刚度；最后，基于Matlab程序平台编制了计算程序，得到了运行列车作用到路基上的荷载时程。

An investigation on the local heat transfer coefficient of a helically segmented finned tube surface in a tube bundle was conducted by experiment in cooperation with numerical calculation.

对齿型螺旋肋片管管束内部沿管表面周向的局部放热系数进行了研究。

With the support of a major research grant of Zhejiang Province (No. 001101027) and the Plan of Promoting Education of Excellence of Zhejiang University in the 21st Century, this dissertation is devoted to address the above problems and fabricate an L-band EDFA with low cost, high performance and technological innovation.First the mechanism of an erbium doped fiber amplifier is introduced. Various theoretical models based on classical rate propagation equations are summarized and compared for their applications. We use a modified numerical model based on the Giles model, which agrees with the experimental results well. This serves as the theoretical base for the whole thesis and will be used to optimize the characteristics of EDFAs. A novel method based on a map of noise figure and gain is proposed to analyze efficiently the dependence of the noise figure and gain for EDFAs on the EDF length and the pump power. The characteristics of various EDFAs are studied and compared.Secondly, some important parameters are introduced to describe the characteristics of EDFAs. The methods and the experimental setups for measuring the gain and noise figure of an EDFA are emphasized. We introduce how to measure the characteristics of each component of an EDFA, especially the gain and absorption coefficient of an erbium doped fiber.Thirdly, four types of simple and novel L-band EDFA structures with low noise, high gain and low gain ripple are proposed to satisfy the requirement of a DWDM system. They can be classified into two categories. In the first category, a single ASE pumping is served asa secondary pump. This category includes the following three types. Type: a new construction using a fiber Bragg grating in an unpumped EDF section at the input side. Type: a new structure of L-Band EDFA with two-stage pumps, which utilizes the forward ASE as a second pump.

本论文本着科技创新、服务于生产实践的精神，以设计价格低廉，性能优越、结构合理简单的L-band EDFA为目标，依托浙江省科技厅重大科学基金资助项目(001101027)和浙江大学振兴教育计划资助的全光网络的搭建—《光通信技术》课程实验建设项目，展开了如下工作：首先，介绍了掺铒光纤放大器的工作原理，归纳总结了基于速率方程基础的EDFA的各种理论模型，分析比较了各个模型的特点和适用场合，最终选择完善的Giles理论模型作为本论文分析设计EDFA的理论基础；针对实际实验条件提出了修正的EDFA模型的数值计算方法；创新地提出了增益—噪声系数全局分析法，直观有效地分析了EDFA的增益和噪声系数与掺铒光纤长度和泵浦功率的依赖关系，并对各种EDFA的性能作了全面的比较；第二，介绍了掺铒光纤放大器特性参数的定义与测量方法，重点介绍了噪声系数和增益系数的测量方法及实验装置；介绍了组成掺铒光纤放大器各组件的特性测量方法，重点介绍了测量掺铒光纤参数的方法和实验装置；第三，针对WDM系统对L-band EDFA谱平坦、低噪声、高增益的要求，我们创新地提出了四种不同的L-band EDFA结构，按设计思路可以分为两大类：一类是基于单抽运二级泵浦法，这一类包括在未泵浦掺铒光纤的输入端插入一根布拉格光纤光栅的两段L-band的EDFA的新结构；基于前向ASE光作为二级泵浦源推动下一级EDF工作的泵浦分配、两段级联L-band的EDFA的新结构；基于单根光纤光栅、泵浦分配、两段级联的EDFA；另一类则是基于同时应用前后向C-band ASE作二级泵浦源的双抽运法，如基于前后向ASE光作为二级泵浦源的三段级联L-band的EDFA的新结构。

Numerical simulation results showed that the unstable periodic orbits of the system could be ballasted,the chaos could be eliminated via choosing proper delayed time and gain coefficient,and the system could be changed from unstable to s.

数值仿真结果表明，选择适当的延迟时间和反馈系数能够控制系统的不稳定周期轨道、消除混沌，并能使系统从失稳状态进入稳定状态。

And to study a method for carrying out numerical calculation by adopting the powerful functioned mathematical software MATHCAD in the solution of coincidence extent on less teeth differenced internal messing and in iterative computation for equation set of interference coefficient of tooth profile overlapping.

提出用CAD法研究三环式少齿差减速器设计的关键问题———内、外齿轮必须采用变位传动的设计，研究在求解少齿差内啮合的重合度和齿廓重叠干涉系数方程组的迭代计算中，选用功能强大的数学软件MATHCAD进行数值计算的方法，计算

By the use of CAD method to carry out the research on key problems of three ring typed less teeth difference reducer-the inner and outer gears have to be designed by adopting modified transmission was advanced. And to study a method for carrying out numerical calculation by adopting the powerful functioned mathematical software MATHCAD in the solution of coincidence extent on less teeth differenced internal messing and in iterative computation for equation set of interference coefficient of tooth profile overlapping.

提出用CAD法研究三环式少齿差减速器设计的关键问题―内外齿轮必须采用变位传动的设计，并研究在求解少齿差内啮合的重合度和齿廓重叠干涉系数方程组的迭代计算中，选用功能强大的数学软件MATHCAD进行数值计算的方法。

The mechanism of instability wrinkling in the process based on minimum energy principle is revealed, uniform mathematic description of the wrinkling wave on the strip of in-plane bending is established, the internal and external energy is deduced by energy method, and a uniform criteria of internal and external wrinkling is established; then how to combine the criteria with the FEM simulation system to make the numerical prediction of wrinkling into reality is also resolved in the paper. The effects of the forming parameters on the deforming result are analyzed by the uniform predict criteria. The results show as follows: as the compress width increase, external wrinkling first come into being, then internal winkling do, and finally in-plane bend occur; the loading wedge angle increase, internal winkling first come into being, thenin-plane bend do, and finally external wrinkling occur; in-plane bend is possible to occur with a increase of the strain-hardening exponent and the strength coefficient; and the effect of the friction factor may be ignored.

2揭示了板带不均匀压下面内弯曲成形过程基于能量原理的失稳起皱机理，提出了统一的描述内外缘起皱波形的函数，采用变分法推导了服从该波形函数的内外缘起皱能，建立了统一的起皱预测准则；将新建立的统一的起皱预测准则引入到数值模拟系统IBS中，数值预测结果与实验结果的吻合较好；分析了成形过程各参数对起皱的影响规律：随着接触变形区宽度的逐渐增大，先是发生外缘起皱，然后发生内缘起皱，进而才出现稳定成形；随着实际加载楔角的增大，先是发生内缘起皱，然后发生稳定成形，进而出现外缘起皱；硬化指数和强化系数增大，易于稳定成形；摩擦因子对起皱的影响不明显；而且接触变形区宽度对起皱的影响最大。

The numerical results show that: the stress distribution on contact surface is relative to the relative velocity of sliding block and friction coefficient, and the maximum relative error of stress can be 100.08%. The non-linear Stribeck friction model can better describe the real situation of contact surface, because of the consideration of impact of the relative velocity to the friction.

研究结果表明：随着接触体相对速度的改变，摩擦因数相应变化，接触面上的应力与位移的分布随之改变，应力最大相对误差达100.08%；Stribeck模型考虑了速度对摩擦因数的影响，更能描述接触的真实情况。

Then the numerical simulation is developed with the above dynamic model. The effects of the clearance on the dynamic characteristics are studied in detail. The influence of factors such as clearance size, driving speed, stiffness, coefficient of viscous damping of contact surface, and the gravity are discussed and the quantitative results are given.

利用本文建立的动力学模型对含间隙三球销移动副的曲柄滑块机构进行了动力学数值仿真，研究了运动副间隙对机构的运动和受力状况的影响，考察了间隙大小、曲柄转速、接触刚度、阻尼、外力矩等对机构动态特性的影响规律，给出了定量结果。

Influence of Additional Twist on Flax Cotton Blended Compact Yarn Property;2. By numerical integral of this model, the factors which affect the additional twist of yarn are analyzed, including the pressure in the profile tube and the coefficient of friction between the fiber band and lattice apron.

通过对集聚区内须条的集聚过程分析，建立须条变截面部分的力学模型，可以得出此部分须条是有附加捻度的，并且对影响这部分须条附加捻度的因素：须条与网格间的摩擦因数和负压的大小进行了分析，结果表明集聚区须条的附加捻度随着须条与网格间的摩擦因数和负压的增加而增加。

The split between the two groups can hardly be papered over.

这两个团体间的分歧难以掩饰。

This approach not only encourages a greater number of responses, but minimizes the likelihood of stale groupthink.

这种做法不仅鼓励了更多的反应，而且减少跟风的可能性。