查询词典 method of difference

The definition of generator angle is proposed in this paper. A new method to deduce generator angle by using rotor rotation signal is illustrated, which compares the phase difference between GPS timing pulse and RRS. Using only mechanical signal, the technique unfreezes limitation of zero-cross of generator terminal voltage during transient process. Automatic correction of initial generator angle is also proposed .

本文介绍了同步发电机绝对转子角的定义，提出了一种测量绝对转子角，进而获得高精度的相对转子角的方法；此方法不使用机端电压过零整形脉冲，而是将机组键相脉冲与GPS 定时脉冲比相，并能够自动整定初始位置角，因此，测量结果不受发电机运行状态的影响，能够在各种运行方式和扰动情况下获取高精度的绝对转子角。

ABSTRACT This thesis is a study of FDTD (Finite-Difference Time-Domain) method and its application to the problems of electromagnetic scatt...

本论文论述了时域有限差分法以及该方法应用于各向异性复合材料散射问题仿真的研究。

The paper investigates both block-type pilot linear minimum mean square error algorithm and IEEE802.16 OFDM channel estimation analysis. Simulation results confirm the block-type pilot structure is more suitable for IEEE802.16 system. An optimal pilot setting algorithm, based on space frequency domain, is explored and the pilot chart is presented. The proposed algorithm finds its application in MIMO-OFDM. Simulation results show the algorithm presents a good approximation to the perfect channel state information curve, with about 2dB difference in SNR. The simulation results also demonstrate the algorithm achieves fairly high stability in the environment of fast fading, performance of the proposed algorithm is better that of pilot training channel estimation.3. Taking into account the characteristics of IEEE802.16 OFDM system, OFDM system simulation platform is constructed in Matlab, exploiting simulink as a tool. OFDM modulation and demodulation simulation system are configured on LabVIEW platform. All the system signal processing is simulated, including defining system parameters, designing modulation model, and verifying all the proposed algorithms under different environments, such as white Gaussian noise, multi-path fading, with or without guard interval etc. Bit error performance is evaluated. The research provides valid theoretical basis for practical OFDM system performance evaluation.4. Taking advantage of software radio, the paper designs a hardware platform with both 256-IFFT/FFT and 512-IFFT/FFT OFDM schemes co-existing in one platform. You can predetermine one from the two schemes to carry out almost the same model function with different system performance and parameter setting.5. Referring to IEEE802.16 standard, the paper proposes a design method for generating signals and frames suitable for laboratory investigations implemented in laboratory environment.6. Based on 6701evm digital evaluation card, combined with analogy front-end, the paper designs a DSP software model to deal with baseband signal processing. An overall OFDM scheme, with modulation and demodulation function, is accomplished.

讨论分析了MIMO-OFDM中一种基于空频域的最优导频设置算法，给出了导频图案，通过仿真实验表明，该算法与理想的信道状态信息曲线非常接近，信噪比差距约在2dB左右，并且在快衰落条件下具有较好的稳定性，其性能要优于基于前导训练的信道估计方法。3、根据IEEE802.16OFDM系统特点，论文分别在Matlab中应用Simulink工具构建OFDM系统仿真平台、在LabVIEW平台上实现了OFDM调制解调仿真系统，模拟了整个系统的信号流程，进行了OFDM仿真系统参数的选择和调制模块的仿真设计、论证各算法性能，并根据各种不同的条件：例如高斯噪声、多径衰落、有无保护间隔等，对系统的误码特性进行了评估，为正确评价实际OFDM系统的性能提供了有效的理论依据。4、论文以软件无线电思想作为指导，提出了以256点IFFT／FFT为核心和以512点IFFT／FFT为核心的两种OFDM算法模式并存于同一个硬件平台、且可预选的方案，它们在参数选取和性能指标上有所差异，均实现了相似的模块和功能。5、论文参考IEEE 802.16无线网络标准的参数设置，针对本设计系统的应用环境和系统硬件的性能速率，提出了一种应用于实验室环境的信号结构、帧格式等参数设计。6、论文基于TI公司的6701evm数字评估板卡，结合模拟前端搭建数字中频平台，设计了基带处理的DSP软件模块并进行系统调试，基本实现了一套完整的OFDM调制解调方案。

The pinch point technology and the mathematics programming method are the main means in the process system energy integration and optimization. But both of them are with the first law of thermodynamics for foundation, they only make sure the quantity relation in energy conversion process and neglect the difference of quality of energy.

夹点技术和数学规划法是过程系统能量综合优化的主要手段，但它们均以热力学第一定律为基础，仅仅确定了能量转换过程中的数量关系，而忽略了能量品质的区别。

In the program, on theoretically we have studied the effects of configuration, the arranged periodic length and the refractive index ratio on PBG using finite difference time dormain method; on experimental, we have synthesized monodispersed silaca microspheres with size of 150-320 nm by colloidal chemical methods. And 3D perfect photonic crystals were prepared using the evaporating of acetone self-assembling the monodispersed SiO2 microspheres on quartzes by and horizontal and vertical deposition methods.

在本项目的研究中，理论上我们应用有限时阈差分法研究了光子晶体光子带隙形成与空间构型、排列的周期长度及折射率比之间的关系；实验上，我们应用胶体化学方法制备了150-320 nm的SiO2胶体微球，以丙酮为挥发溶剂，通过水平重力沉积法和垂直自然吸附法制备了各种粒度、排列完美的面心立方光子晶体。

We performed a simulative test, which confirms that wavelet analysis can separate annual wobble and Chandler wobble. Our results show that this method can be used in astronomical geodynamies effectively. This paper is divided into two parts. The first is about statistic characteristic of polar motion. Polar motion includes secular motion, long period fluctuations, Chandler wobble, annual wobble and high frequency wobble. The secular motion is 3.4mas/year and towards 760W meridian. Long period fluctuations have difference periods in x-axis and y-axis. They are 31.7-year and 24-year in x-axis and 28.5-year and 22.9-year in y-axis. These 2~? decades fluctuations have an amplitude of about 30 mas , and are very nearly linearly polarized, with the observed motion of pole being almost entirely along a line between 360E and 1440W. There is a 55.4-year wobble whose amplitude is 9 mas. The amplitude of the interannual fluctuations is about 4? mas. The amplitude of long period fluctuations decreased after 1970. The annual wobble is a steady wobble. It retrograde wobble is only 1/20 of prograde wobble in amplitude.

本文的工作主要分为两部分：第一部分是通过分析POLE97序列，我们对极移的统计特性有了一个较全面的认识，极移主要包括趋势项、长周期项、Chandler项、周年项和高频项：趋势项的方向是西经76°，速度为每年3.4mas；长周期项中Markowitz 项在X、Y两个方向有不同的周期，它们分别是：X方向的两个周期是31.7年和24 年，Y方向的两个周期为28.5年和22.9年它们叠加在一起是一个线偏振运动，最大振幅约为30mas，偏振方向在西经144°和东经36°之间；极移的长周期波动中还存在一个 55.4年周期的圆周运动，振幅约为9mas；十年尺度变化的振幅在4～6mas之间，在Y 方向十年尺度的成份比较多，它们的周期在X方向和Y方向不是对应的；从七十年代年开始长周期变化的振幅明显降低；周年项是一个振幅稳定的摆动，在X、Y两个方向的振幅略有差别，逆向运动振幅大约为顺向运动振幅的1/20；Chandler摆动的振幅自1900年以来经历了几次较大的变化，其中包括1915年和1955年两次极大值，振幅分别达到0&。25和0&。28，以及1925～1940期间小于0.09的过程，Chandler项在X、Y 两个方向的振幅几乎完全相等，其逆向运动振幅不到顺向运动振幅的1/50。

The invention is suitable for pipe shell type heat exchanger, better heat transfer effect can be achieved by adopting the arrangement method for heat transfer pipe according to the invention, and heat exchanger having different temperature difference of intake water and outtake water can be conveniently combined.

本发明适用于管壳式换热器，在换热装置中采用本发明的传热管的排列方法，可以达到较好的传热效果，而且可以方便地组合成不同进、出水温差的换热器。

Based on numerical difference between the first order and high order Mueller matrix solutions, an iterative method for inversion of surface moisture and fraction per unit area of random small spheroids from polarimetric backscattering measurement is developed.

中文摘要：根据一层随机非球形粒子矢量辐射传输方程的一阶与高阶Mueller矩阵解的数值模拟及其差异，提出了在一些参数已知的条件下，用水平与垂直同极化和交叉极化的后向散射测量反演植被覆盖下地表湿度和植被散射元单位面积占空比的迭代方法。

Due to the cooling-water tube diameter of the generator is too small, the velocity of cooling-water is also too low, if we only use the travelling period difference of one emmission and reception, the propagation time will be too small to test. Then, we select ultrasonic circulation method as our concrete plan.

由于发电机冷却水引水管的管径小，冷却水的水流速度低，利用单次发射和接收的时间差检测时，传播时间差极其微小，故作者首次提出利用声循环法来检测大型汽轮发电机定子线棒冷却水流速。

The operation method, characteristics and notice items of the static pressure test through the height difference between the in and out nozzles of the in-service pressure vessel are introduced. The difficult problems for hydrostatic test of certain kinds of the in-service pressure vessel have been solved ingeniously. And the overhaul cost and maintenance difficulty of in-service pressure vessel have been reduced efficiently.

论述了利用某些在用压力容器出入口连接管线达到一定高度差可产生的静压强进行水压试验的作业方法、特点和注意事项，巧妙解决了某类容器不易进行水压试验的难题，有效降低了压力容器的检修难度和费用。

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。