Scheme optimization of AT shifting element based on genetic algorithm

In order to realize the computer aided design of AT shifting element schemes, a mathematical model of shifting element schemes which can be easily identified by computers was built. Taking the transmission ratio sequence as an optimization objective and simple shifting logic between adjacent gears through operating only one shifting element as a constraint condition, a fitness function of shifting element schemes was proposed. ZF-8AT shifting element schemes were optimized based on GA work-box of MATLAB, and the feasibility of the optimization algorithm was verified.     

Neural Network Based Multi-level Fuzzy Evaluation Model for Mechanical Kinematic Scheme

1 Introduction An approach of function analysis is generally adopted in conceptual design of mechanical kinematic sys-tem[1 ,2]. Under this approach,a number of design schemes can be acquired through function decomposition,function expression,andfunctionsynthesis .Then,for these schemes ,it is necessaryto analyze them with kine-matics and dynamicstheory,in whichthe comparatively poor schemes are rejected.The rest schemes are prefer-able to the rejected ones in satisfying the design requirement…     

Research on Estimator and Testing Acquisition Schemes in Direct Sequence Spectrum Spreading Systems

Serveral methods for the pararrel acquisition of a PN sequence in a baseband direct sequence spread spectrum system are investigated. Four different kinds of schemes are considered: the optimal estimation scheme, the locally optimal estimation scheme, the optimal testing searches and the locally optimal testing scheme. In the four kinds of parallel acquisition schemes, the expressions for the probability of error are given and compared with the actual error probabilities obtained via Monte Carlo simulation. We also outline a technique that can be suboptimal because of a large amount of hardware and computation when using the parallel acquisition schemes.     

A study of parameter-free shock capturing upwind schemes on low speeds’ issues

Nowadays,the upwind schemes are in a rapid development to capture shock accurately.However,these upwind schemes’properties at low speeds,such as their reconstruction scheme dependencies,grid dependencies,and Mach number dependencies,are concerned by few people.In this paper,a systematic study on their low speeds’issues is conducted.Through a series of tests,we can find that most parameter-free upwind schemes,widely used in practice today,are not applicable to low speeds’simulations.In contrast,SLAU and SLAU2 can give reliable results.Also,the upwind scheme’s influence on the accuracy is stronger than the reconstruction scheme’s influence at low speeds.     

Convertible Proxy Signcryption Scheme

In 1996, Mambo et al introduced the concept of proxy signature. However, proxy signature can only provide the delegated authenticity and cannot provide confidentiality. Recently, Gamage et al and Chart and Wei proposed different proxy signcryption schemes respectively, which extended the concept of proxy signature.However, only the specified receiver can decrypt and verify the validity of proxy signcryption in their schemes.To protect the receiver‘ s benefit in case of a later dispute, Wu and Hsu proposed a convertible authenticated encryption scheme, which can enable the receiver to convert signature into an ordinary one that can be verified by anyone. Based on Wu and Hsu‘ s scheme and improved Kim‘ s scheme, we propose a convertible proxy signcryption scheme. The security of the proposed scheme is based on the intractability of reversing the one-way hash function and solving the discrete logarithm problem. The proposed scheme can satisfy all properties of strong proxy signature and withstand the public key substitution attack and does not use secure channel. In addition, the proposed scheme can be extended to convertible threshold proxy signcryption scheme.     

Analysis of the compound split transmission based on the four-port power split device

In order to identify all the appropriate system schemes for the compound split systems formed primarily with a four-port mechanical power split device,power transmission characteristics of the compound split systems was analyzed.Considering the structural symmetry and according to the different connection arrangement of the four ports,compound split system was classified into four types.Using black-box modeling method,the generalized models of the speed ratio,the torque ratio and the power split ratio were established.Moreover,a semi-invert diagram was used to distinguish the different schemes in each type.The characteristics of the speed ratio,the torque ratio and the power split ratio in each domain were also analyzed and compared.Through the semi-invert diagram,a selection method based on the rated-power speed ranges in different schemes was presented and all suitable compound split systems were identified,which can be used as references for the scheme selection of this kind of continuously variable power split transmission.     

Robust MSE precoder for imperfectly known MIMO wireless correlated channel

Aimed at that only one form of channel statistic information is utilized in traditional robust precoder schemes: either the channel mean or the transmit antenna correlation in multiple-input multiple-output (MIMO) wireless system, this paper proposes robust precoder designs which exploit both of statistic information to minimize the equalization mean-square error (MSE) with power constraint. Two different power constraints are studied. Besides the usual sum power constraint over all antennas, the per-antenna power constraint is imposed at transmitter in this paper. Since each antenna has its own amplifier, individual power constraint on each antenna is more realistic. Especially in MIMO-OFDM systems, the Peak-to-Average Ratio (PAR) is one of main practical problems. Simulations show that the proposed schemes have better performance than traditional normalized zero forcing schemes for imperfectly known correlated channel. Moreover, per-antenna power constraint can efficiently decrease the demand of dynamic range of power amplifier on each transmit antenna, especially in MIMO-OFDM systems.     

Saving Strategy and Simulation Analysis of Green Log Walls in Severe Cold Area

Log house is a traditional type of vernacular dwelling in Chinese cold area. It contains distinct regional characteristics and architectural cuhures. In recent years, log house has come into vogue softly with the development of wood techniques. However, log houses expend too much wood materials. There are also many negative aspects of this type of wood building which go against the criteria of energy conservation, and its high prime cost hinders the application as well. To solve these problems, the paper emphasizes using more environmental standardized techniques which save cost at the same time, and put forward technical strategy to improve the log walls. The optimization schemes are mainly divided into two categories： internal insulation and filled insulation. Each type of insulation is respectively derived two schemes through changing the thickness of main structure layers and insulation layer. Firstly, we use Weto software to calculate the timber volume of the four schemes, and it concludes that all the optimizations can save more timber than the prototype log wall with the section of 200 minX200 mm. Secondly, thermal cornfort of each scheme is insulated in Design Builder. The results show that thermal insulation of filling type represents better than the other schemes. At last, we use thermal calculating formula to calculate thermal resistance of every scheme. Contrast to the energy efficiency standards of Heilongjiang Province, the data show that the four schemes meet the requirements of the specification.     

Normal transmitting boundary conditions

The multi-transmitting formula (MTF) governed by a single artificial speed is analytically developed into a generalized MTF governed by a few artificial speeds to improve its capacity in simultaneous simulation of several one-way waves propagating at different speeds.The generalized MTF is then discretized and further generalized using the space extrapolation to improve its accuracies in numerical simulation of transient waves at large angles of incidence.The above two successive generalizitions of MTF based on the notion of normal transmission lead to a compact formula of local non-reflecting boundary condition.The formula not only provides a general representation of the major schemes of existing local boundary conditions but can be used to generate new schemes,which combine advantages of different schemes.     

New scheme of dynamic traitor tracing against the immediate rebroadcast attack

Traitor tracing schemes are introduced to combat the piracy scenarios. The notation of dynamic traitor tracing is proposed by Fiat and Tassa,which fights against rebroadcast of decrypted content. In this paper,using the idea of searching user address level by level,a new dynamic traitor tracing scheme based on a multilevel structure of user set is constructed. The scheme proposed can efficiently combat with the immediate rebroadcast attack,and possesses lower tracing complexity. Importantly,the tracing scheme can be applicable to systems with different sizes of subscriber sets.     

TD-HSUPA MU-MIMO室内调度及用户配对

为了解决在室内多用户多输入多输出(MU-MIMO)场景下,时分双工上行高速分组接入(TD-HSUPA)系统的多用户调度问题,提出了一种新的调度和用户配对算法.该算法综合考虑了接收天线间的流间干扰和同一接收天线内的码间干扰.通过将用户动态接入不同基站天线服务列表,所提算法能在保持用户公平性的前提下明显提升基站平均吞吐量.该算法运算复杂度低,无需增加信令开销,适用于实际室内系统中.     

基于差分进化算法的MU-MIMO用户调度算法

为了使MU-MIMO系统的用户得到更公平的服务,提出了一种块对角化预编码下基于差分进化算法的用户调度算法.该算法将差分进化算法进行改进,使其可对任意可行大小的用户子集进行调度,并进行参数自适应,与改进的比例公平算法相结合进行用户调度.实验结果表明,在不同的信噪比和用户数下,该算法较改进遗传算法在效率方面有大幅度提高,且公平度、系统和数据率相对于改进遗传算法均有所提高,能有效地解决块对角化预编码下的用户调度问题.     

空间复用系统分组调度机制研究

由于现有的轮询算法系统容量较低,而多用户分集算法无法考虑用户的公平性.在结合了轮询、最优用户分配和最优天线分配算法的基础上,提出了一种新的改进的空间复用系统下行分组调度算法,该算法在轮询的基础上,利用了多用户分集特性,使系统容量得到非线性增长,在用户公平性和系统容量之间取得了较好的折衷.同时提出了“最大删除”算法来完成信道和用户的一一映射,系统容量要略小于穷举法所得到的系统容量,但基站计算的次数由NT!降低到NT次,降低了系统复杂性,这在NT比较大时是非常重要的.     

保证混合业务质量的跨层OFDMA资源分配方法

提出了一种新的跨层正交频分多址（OFDMA）系统资源分配方法,其综合考虑了无线信道的时变特征和媒体接入子层（MAC）业务质量（QoS）要求,将MAC层分组调度和物理层的OFDM子信道分配及自适应调制编码进行联合设计,目的是在保证实时时延敏感业务和非实时业务的QoS基础上最大化系统吞吐量。在子载波分配过程中,分别采用了信道依赖的最早预期 (CD-EDD)算法和 最小速率需求(MRR)算法,对实时时延敏感业务和非实时业务进行调度。基于IEEE 802.16标准建立了动态仿真模型对算法性能进行评估,结果表明较传统的最大信噪比方法在系统吞吐量相近的基础上对时延特性、用户公平性方面有较大性能提升。     

Turbo CDMA多用户检测的研究

简述了Turbo译码原理及逐符号最大后验算法,并将Turbo译码原理应用于CDMA系统的多用户检测;提出了基于Turbo译码原理的多用户检测接收机方案,通过计算机仿真验证了该方案的性能。结果表明,该方案经过4次迭代之后,其误码率接近单用户界,这种接收机可去除多址干扰(MAI)的影响。     

一种采用松弛正交预编码的多址接入方法

在多址方法设计中,有效管理多个并发通信间的共道干扰是提升系统频谱效率的关键。现有干扰管理的思路是使多路信号在传输过程中相互正交,然而在多用户多输入多输出系统中,发射机和接收机的数量以及它们的天线配置严格制约了系统能够支持的正交并发通信的数量。针对这一问题,提出一种应用于多用户多输入多输出下行通信的基于松弛正交预编码的多址接入方法,通过引入一个正交幅度调节函数,在一个符号周期内对预编码的幅度进行调整,利用调节后的预编码进行信号处理和发送,可以将对多用户信号在空域上严格正交的要求放宽到相关意义上的正交;相应地,接收机采用相关运算对期望信号进行检测,可以利用幅度调节函数之间的正交性在判决时刻消除共道干扰的影响。仿真结果表明,所提方法可以在不增加频谱资源消耗的情况下,显著提高系统容纳的用户数量,改善系统的频谱效率。     

双功能雷达通信系统的多用户功率分配算法

为解决传统多用户双功能雷达通信系统因载波分配导致通信性能较差的问题,提高双功能雷达通信系统的资源利用率,提出了一种通信用户载波共享模型下的多用户功率分配方案,并通过构造合理的资源分配问题使得系统具有更优的通信性能。首先,建立双功能雷达通信系统的通信用户载波共享信号模型。其次,为保证双功能雷达通信系统性能,构造了以系统通信和速率最大并满足雷达信噪比下界、总功率和用户功率约束的优化问题,通过理论分析严格证明了优化问题的可行性。最后,为求解凸优化问题,提出一种多用户功率分配算法,通过引入辅助变量对目标函数进行二次转换,将其分解为两个优化子问题,继而通过交替迭代的方式进行求解。研究结果表明,相较于传统通信用户载波分配模型,优化后的通信用户载波共享模型通信和速率提高了约40%,从而验证了所提方案具有更优的通信性能,有效提高了系统资源利用率。本研究成果为提高多用户双功能雷达通信系统的通信性能提供了一种新思路和手段。     

利用HARQ多用户MIMO系统的自适应反馈方法

提出了一种利用混合自动重传请求（HARQ）的多用户多输入多输出（MIMO）系统的自适应反馈方法. 该方法利用HARQ过程中用户反馈的确认/不确认（ACK/NACK）信息,分析信道状态和多用户之间的配对状况,决定用户端何时反馈信道状态信息（CSI）,并进行调度和预编码来提高系统容量. 仿真结果表明,该方法减少了反馈量,复杂度低,比传统的多用户MIMO系统具有更好的性能,特别是高信噪比和高速移动情况下,一定程度解决了多用户MIMO系统的瓶颈问题.     

最小误码率排序迭代优化的SLNR改进算法

针对多用户MIMO系统应用SLNR算法时由于干扰用户增加引起的系统性能下降问题,联合考虑误码率性能和信道质量,提出一种先把部分已知的多用户干扰加入SLNR准则进行抑制,根据信噪比大小确定预编码矩阵的设计顺序,再利用已知的多用户干扰迭代优化后续用户预编码矩阵的SLNR改进算法.由于只利用发射端信道信息优化预编码矩阵,改进算法无需基站与用户协作,计算复杂度低.对比仿真结果表明,改进算法收敛速度快,在高信噪比区域,误码率性能和系统容量增益得到了显著提升.     

改进的MU-MIMO线性预编码算法

针对MU-MIMO系统中多用户天线之间存在的干扰问题,提出一种块状对角化-最小均方误差(BDMMSE)算法。该算法是在信噪比一定的情况下,先用BD预编码算法在发送端消除多用户之间的干扰,然后在接收端使用MMSE信号检测技术对每个用户多个天线之间的干扰进行消除,最终使误比特率达到最小。仿真结果表明,改进的预编码算法比单一的预编码算法的BER性能有显著提高。