查询词典 explicit difference schemes

Equidistance point and difference theory in theory of function approximation are studied. Meanwhile, the relation among difference, difference quotient and derivate is revealed. By drawing Lagrange's and Cauchy's theorem of mean on difference and Taylor's formula into difference function, four theorems, such as Lagrange's theorem of mean on difference, are concluded in simple way. On the basis of these conclusions, the asymptotic property of middle point is studied, a series of new conclusions are drawn and the discussions on the asymptotic property of middle point in differential mid-value are summarized.

对函数逼近论中等距节点和差分理论进行了研究，揭示了差分、差商与导数之间的联系；将Lagrange中值定理、Cauchy中值定理、Taylor公式引入到差分函数中，简明地推导出Lagrange差分中值定理等4个定理，并在此基础上对&中间点&的渐近性进行了研究，得出了一系列&中间点&的渐近性的结果，概括了有关文献对微分中值公式的&中间点&的渐近性的讨论；给出的引理改进了函数逼近论的证明方法，精简了函数逼近论中的一些内容。

Two new second-order explicit finite-difference schemes are introduced for the analysis of transient two-component flows.

这些格式是在计算流体力学中采用的，近来用于解决管道中的瞬变问题。

It is helpful for us to construct difference approximation schemes for HJ equation with aids of schemes for conservation laws.

众所周知，即使在初值条件0是充分光滑的情况下，一般来说，虽可以得到式(1 )的连续解，但其解的导数却是间断的。

A general Godunov finite difference schemes-WENO (Weighted Essentially Non-Oscillatory) schemes which have fifth-order accuracy is used to perform a numerical calculation for 2-dimensional axis symmetrical laser-supported plasma flow field under laser ablated solid target.

采用具有五阶精度的WENO差分格式和简易等离子体状态方程模型对激光与等离子体相互作用的复杂物理过程进行了数值计算，分析了激光束能量在等离子体区中的吸收、屏蔽效应等动态耦合规律以及激光支持等离子体前驱冲击波传播。

A general Godunov finite difference schemes-WENO schemes which had fifth-order accuracy was used to make a numerical calculation for 2-dimensional axis symmetrical laser-supported plasma flow field under laser ablated solid target and laser ablated propulsion efficiency parameters(mechanical coupling coefficient etc.) was obtained by the simulation.The models of the calculation of ionization degree of plasma and the interaction between laser beam and plasma and the simplified eos of plasma were considered in the simulation.

采用针对高温气体电离度的一种近似计算方法，以及具有五阶精度的广义Godunov差分格式-加权本质无振荡格式WENO(weighted essentially non-oscillatory schemes)，给出了高温气体状态方程的简便描述，并考虑激光与等离子体的相互作用，模拟了强激光与固体靶相互作用时激光支持靶面等离子体流场的动态物理过程，并给出了不同参数条件下激光烧蚀固体靶的推进效应参数。

Based on this, a new WENO difference scheme which based on Dispersion-Relation-Preserving relation is developed, and representative test cases with this scheme for computational aeroacoustics problems has been implemented and compared in order to test capability of wave capturing; In addition, WENO schemes generally do not converge at high order in the presence of contact discontinuity of Euler equations, so a conservative front tracking technique coupling WENO schemes and Level Set method to simulate the translating density profile is presented here, and numerical simulation with this technique for representative test case has been implemented and results show the desired accuracy.

本文研究了高阶精度加权基本无振荡格式及其在双曲守恒律方程中的应用，在此基础上作了两个方面的工作：一是针对高频声波问题构造出一种基于保色散关系的WENO有限差分格式，并对计算气动声学问题的代表性算例进行了大量数值实验，比较了该格式捕捉波数的能力；另外，针对高阶WENO格式在处理Euler方程的接触间断时精度有所降低的问题，研究了利用界面追踪技术Level Set方法和高阶激波捕捉WENO格式相结合的一种守恒追踪方法，并且给出有代表性的密度滑移面问题的算例，得到一致高阶精度的数值模拟结果。

High order symplectic schemes of three-dimensional time-domain Maxwell's equations are constructed with symplectic integrator technique combined with high order staggered difference. The method is used to analyzing stability and numerical dispersion of high order time-domain methods and symplectic schemes with matrix analysis and tensor product.

利用辛积分技术与高阶交错差分技术，建立求解三维时域Maxwell方程的高阶辛算法；结合电磁场中的物理概念，借助矩阵分析和张量分析理论，获得高阶时域方法及高阶辛算法的稳定性和数值色散性的统一处理新方法。

With the IAP Prediction System of Short-term Climate Anomaly, two sets of seasonal and extra-seasonal ensemble hindcasts have been performed during the period of 1980～1994 in order to assess the prediction skill of the IAP PSSCA with two different schemes The difference of the two schemes is in the different version of AGCM used, with the IAP AGCM 1 1 in one scheme and the IAP AGCM 1 2 with an improved surface albedo parameterization in the other Comparisons of the hindcast results with the observations show that IAP PSSCA is capable of predicting the precipitation anomaly to some extent In the eastern China largely affected by Asian monsoon and SST anomalies, the prediction skill is relatively high, especially in the Southeastern China where the anomaly correlation coefficient can reach as high as 0 50 in the severe flood and drought years This may suggest that the possible mechanisms for these severe disasters have been well captured by the IAP PSSCA The prediction skill is higher for the modified model AGCM 1 2 as the model's climatological state is well simulated This indicates that models with reasonable land process will improve the prediction skill for short-term climate prediction

利用中国科学院大气物理研究所研制的短期气候距平数值预测系统，种版本的大气环流模式：AGCM 1.1和AGCM 1.2，分别以2月11～19日的9天大气观测值为初始场，以给定海温为边界场，对1980～1994年的15年的降水异常进行了两组集合后报试验。对试验结果进行定量评估表明：IAP PSSCA对降水异常具有一定的预测能力，特别是在中国东部受东亚季风及海温异常影响的地区，IAP PSSCA具有较高的预报技巧，其中以东南区域(包括江淮流域和华南地区)最高，尤其是对有洪涝灾害的降水异常年，距平相关系数在0.50左右，接近可供业务使用的要求，说明模式能够抓住在东亚季风区存在的某种物理机制，从而提高了这一地区的预报技巧；另外，两个大气环流模式相比，改进了地表反照率的AGCM 1.2的15年集合平均预测技巧略高于AGCM 1.1，特别是在华北地区，预测效果有明显提高，这表明改进地表反照率从而改进了模式的气候平均态的模拟，能提高气候模式的预测能力，说明较好的陆面过程引入模式对短期气候预测是有益的。

Short-circuit current secretly schemes against , system hits the target to the transformer substation when three-phase short circuit happened in the lower voltage grade bus bar one by one, the difference what be flowed past short-circuit current has been carried out secretly schemes against

短路电流计算，对变电站系统中的各个电压等级下的母线发生三相短路时，所流过的短路电流进行了分别计算。

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。

When this condition occurs, inbound replication with the source partner is stopped on the destination domain controller and event ID 2042 is logged in the Directory Services event log.

计算机密码学是研究计算机信息加密、解密及其变换的科学，是数学和计算机的交义学科，也是一门新兴的学科。

Instructions: click on the thumbnails to see a larger image, then use the left-right arrow keys to scroll through the slideshow.

使用说明：滑鼠点在小图上即可放大观赏。开启后键盘左右键可用来换照片。