Mathematic principle of active jamming against wideband LFM radar

The inherent mathematic principle of active jamming against the wideband linear frequency modulated（LFM） radar is investigated. According to different generation strategies, the active jamming methods are reclassified into three groups, i.e.,non-coherent jamming（NCJ）, convolution jamming（CJ） and multiplying jamming（MJ）. Based on the classification, the mathematic principles of different active jamming groups are put forward, which describe the relationships between the modulated signals and the jamming results. The advantages and disadvantages of different groups are further analyzed, which provides a new perspective for the study of jamming/anti-jamming methods and a potential for engineers to integrate similar jamming methods into one jammer platform. The analyses and simulation results of some typical active jamming methods prove the validity of the proposed mathematics principle.

Extra-seasonal prediction of summer 500-hPa height field in the area of cold vortices over East Asia with a dynamical-statistical method

The cold vortex is a major high impact weather system in northeast China during the warm season, its frequent activities also affect the short-term climate throughout eastern China. How to objectively and quantitatively predict the intensity trend of the cold vortex is an urgent and difficult problem for current short-term climate prediction. Based on the dynamical-statistical combining principle, the predicted results of the Beijing Climate Center＇s global atmosphereocean coupled model and rich historical data are used for dynamic-statistical extra-seasonal prediction testing and actual prediction of the summer 500-hPa geopotential height over the cold vortex activity area. The results show that this method can significantly reduce the model＇s prediction error over the cold vortex activity area, and improve the prediction skills. Furthermore, the results of the sensitivity test reveal that the predicted results are highly dependent on the quantity of similar factors and the number of similar years.

Generalized Parseval’s Theorem on Fractional Fourier Transform for Discrete Signals and Filtering of LFM Signals

This paper investigates the generalized Parseval’s theorem of fractional Fourier transform (FRFT) for concentrated data. Also, in the framework of multiple FRFT domains, Parseval’s theorem reduces to an inequality with lower and upper bounds associated with FRFT parameters, named as generalized Parseval’s theorem by us. These results theoretically provide potential valuable applications in filtering, and examples of filtering for LFM signals in FRFT domains are demonstrated to support the derived conclusions.

Application of the Morphological Analysis for the Synthesis Arrangements of Industrial Robots with Parallel Structure Mechanisms

The main features of morphological model of industrial robots are discussed, such as support system, manipulator and gripping device. These features are presented with the alternatives for their realization as separate modules. The examples of synthesis of arrangements of industrial robots are resulted on module principle with writing of their morphological formulas.

OFD-NLFM雷达信号的优化设计及射频隐身性能分析

具有高主副瓣比的雷达信号可以降低无源探测系统的截获概率,从而具有一定的射频隐身特性。利用窗函数反求法设计了非线性调频信号,并利用组合窗法优化非线性调频信号,分析信号的自相关主副瓣比和主瓣宽度。由于多输入多输出雷达具备较好的射频隐身能力,基于单一窗和组合窗设计了正交频分非线性调频信号,给出了不同类型、不同组合系数时信号的自相关主副瓣比、主瓣宽度及互相关峰值电平。研究表明,正交频分非线性调频信号具备较强的射频隐身能力,有较广泛的应用前景。

基于组合窗的OFDM-NLFM信号设计

高主副瓣比、窄主瓣宽度以及良好的正交特性是多输入多输出雷达波形设计的研究重点。利用组合窗法对非线性调频信号主副瓣比以及主瓣宽度进行了优化,分析了组合参数对信号的影响;在此基础上,提出了基于组合窗优化的正交频分非线性调频信号的设计方法,并对点目标正交频分回波信号进行了匹配滤波。仿真结果表明,优化后的雷达信号具有良好的正交性能。

OFDM-MQAM在相关Nakagami-m衰落信道上的性能分析

本文研究频率选择性相关Nakagami衰落信道上采用最大比合并(MRC)分集接收的正交频分多路复用M进制正交幅度调制(OFDM-MQAM)系统。使用矩生成函数(MGF)方法和高斯超几何函数、Appell超几何函数或Lauricella函数,推导任意衰落参数频率选择性相关Nakagami衰落信道上MRC分集接收的OFDM-MQAM系统的误符号率(SER)性能,获得了OFDM-MQAM误符号率的一个新的解析表达式。数值计算结果阐明了多径路径数、Nakagami衰落参数和信道脉冲响应抽头间的相关系数对OFDM-MQAM误符号率性能的影响。

一种抑制OFDM系统峰均功率比的融合算法

提出了一种抑制正交频分复用(OFDM)系统峰均功率比(PAPR)的融合算法,该算法在OFDM系统发射端对信号先后进行选择映射(SLM)和压扩变换,从而使信号的峰均比得到二次抑制。仿真结果说明了该算法对峰均比的抑制效果比单独使用SLM技术和压扩技术都有明显的改善,并且对于计算复杂度要求不高的OFDM系统,不同参数的综合技术可相互替代以提高系统的误码性能。

多用户OFDM自适应组合调制及比特分配算法的实现

将自适应技术应用于多用户正交频分复用系统,能够提高频谱利用率,降低系统发射功率,从而使系统的整体性能达到最优;针对多用户OFDM系统,将其信道分配和比特分配相结合,提出了更优的多用户OFDM自适应组合调制比特分配算法(M CABA)。根据信道特性的瞬时估计值,自适应地为各用户分配子信道和比特,在给定误码率的条件下使总的发送功率最小,仿真结果表明,该算法计算简单,优化效率高,可以达到接近理论上的最优水平。

Fractional differential equations of motion in terms of combined Riemann-Liouville derivatives

In this paper, we focus on studying the fractional variational principle and the differential equations of motion for a fractional mechanical system. A combined Riemann-Liouville fractional derivative operator is defined, and a fractional Hamilton principle under this definition is established. The fractional Lagrange equations and the fractional Hamilton canonical equations are derived from the fractional Hamilton principle. A number of special cases are given, showing the universality of our conclusions. At the end of the paper, an example is given to illustrate the application of the results.

Hilbert spectrum and intrinsic oscillation mode of dynamic response of a bilinear SDOF system: influence of harmonic excitation amplitude

Under harmonic wave excitation, the dynamic response of a bilinear SDOF system can be expressed by the Hilbert spectrum. The Hilbert spectrum can be formulated by (1) the inter-wave combination mechanism between the steady response and the transient response when the system behaves linearly, or (2) the intra-wave modulation mechanism embedded in one intrinsic mode function (IMF) component when the system behaves nonlinearly. The temporal variation of the instantaneous frequency of the IMF component is consistent with the system nonlinear behavior of yielding and unloading. As a thorough study of this fundamental structural dynamics problem, this article investigates the influence of the amplitude of the harmonic wave excitation on the Hilbert spectrum and the intrinsic oscillatory mode of the dynamic response of a bilinear SDOF system.

APPLICATION OF MEDIAN-EFFECT IN QUANTITATIVE ANALYSIS OF ANTITUMOR DRUGS IN VITRO

Objective: To analyze quantitatively the synergistic and antagonistic effects of combined oxymatrine (OMT) and 5-fluorouracil (5-GU) on a cell line of human liver cancer (HepG2) with median-effect principle in vitro. Methods: The median-effect principle and MTT method were used in the quantitative analysis of effects of the two drugs. Results: Cytotoxic activity of the individual drugs enhanced as drug concentration increased. As fa=0.41, a CI equal to 1 indicated additivity; fa<0.41, a CI less than 1 indicated synergy; and fa>0.41, a CI greater than 1 indicated antagonism. The sequence of administration did not influence the cytotoxic activity of the combined antitumor drugs. The ratio of drug concentration was a factor that can influence the killing effect. Conclusion: The combined drugs interaction (CI<1) was synergistic at lower concentration and antagonistic at higher concentration. The ratio of drug concentration is a factor that can influence the killing effect.

Development of Computer Network of CNTIEC Management Information System

LAN, WAN and MIS are developing quickly in China and foreign countries nowadays.The development of IF system has went through 3 stages with 7 development processes. The higstage of information integration highway has reached us and some other developed countries. Thecentral government, ministries and commissions in China have stated the engineering design on thissubject. China National Tobacco Import & Export Corporation (CNTIEC) brought a developmentproject forward. The general goals of this mission are: (a) to increaae the working efficiency ofCNTIEC by using modern information technology; (b) to incresdr the success rate in managementdecision making; (c) to heighten the management level to the high technology of information automation. The design should have a pod beginning and the whole design should be carried outin several steps. The management principle of information system is centsral management and distributed usage. CNTIEC's management can get a new stage by achieveng a scienific management.The management personnel can exert their activity to the full by changing the way of the work.Besides, it can realize personnel resource exploiting and concept transforming.

A high performance waveform and a new ranging method for the proximity detector

Signal modulation is an essential design factor for proximity detectors and directly affects the system's potential performance.In order to achieve the advantages of chaotic codes bi-phase modulation(CCBPM)and linear frequency modulation(LFM) simultaneously,this paper designed a waveform which combined chaotic codes bi-phase modulation and linear frequency modulation(CCBPM-LFM) for proximity detectors.The CCBPM-LFM waveform was analyzed in the aspect of time delay resolution(TDR) and Doppler tolerance(DT) based on ambiguity function(AF).Then,a ranging method,which we called instant correlation harmonic demodulation(ICHD),was presented for the detector using the CCBPM-LFM waveform.By combining time domain instant correlation with harmonic demodulation,the ICHD solved the problem caused by combination modulation and made the most of the linear frequency modulation(LFM) harmonics and the correlation of chaotic codes.Finally,a prototype was implemented and ranging experiments were carried out.From the theoretical analysis and experimental results,the proximity detector used the CCBPM-LFM waveform has an outstanding detection performance.

The interaction between cytarabine and vincristine on HL-60 cell line in vitro

Objective： To analyze the effect of cytarabine combined with vincristine on HL-60 cell line in vitro. Methods： The median-effect equation and MTr assay were used on HL-60. Results： The cytotoxic activity of cytarabine（Ara-C） and vincristine （VCR） used alone or in combination enhanced as drug concentration increased. The order of administration did not influence the cytotoxic activity of the combined antitumor drugs. The ratio of drug concentration was a factor to influence the killing effect. The interaction of the agents was synergistic at lower concentration, and antagonistic at higher concentration. Conclusion： The combined drugs interaction（CI 〈 1 ） was synergistic at lower concentration and antagonistic at higher concentration. The ratio of drug concentration is a significant factor that can influence the killing effect.

基于BLLR-GSC的MQAM-OFDM系统性能

研究频率选择性相关Nakagami-m衰落信道上基于信噪比广义选择合并(SNR-GSC)和基于比特对数似然比广义选择合并(BLLR-GSC)分集接收,采用M进制正交幅度调制方式的正交频分多路复用(MQAM-OFDM)系统的误比特率性能。仿真结果表明采用L支路最大比合并分集接收的MQAM-OFDM系统的误比特率,L支路中选择L/2支路的基于BLLR-GSC分集接收的MQAM-OFDM系统的误比特率相等;在接收天线数和选择天线数相同的情况下,BLLR-GSC分集接收的MQAM-OFDM系统的误比特率性能要优于基于SNR-GSC分集接收的MQAM-OFDM系统。

Electronic structures and energy band properties of Be- and S-doped wurtzite ZnO

The energy band properties, density of states, and band alignment of the BexZn1-xO1-ySy alloy （Be- and S-doped wurtzite ZnO） are investigated by the first-principles method. BexZn1-xO1-ySy alloy is a direct band gap semiconductor, the valence band maximum （VBM） and the conduction band minimum （CBM） of BexZn1-xO1-ySy are dominated by S 3p and Zn 4s states, respectively. The band gap and lattice constant of BexZn1-xO1-ySy alloy can be modulated by changing the doped content values x and y. With the increase in Be content value x in the BexZnl-xOl-ySy alloy, the band gap increases and the lattice constant reduces, but the situation is just the opposite when increasing the S content value y in the BexZn1-xO1-ySy alloy. Because the lattice constant of Be0.375Zn0.625O0.75S0.25 alloy is well matched with that of ZnO and its energy gap is large compared with that of ZnO, so the Be0.375Zn0.625O0.75S0.25 alloy is suitable for serving as the blocking material for a high-quality ZnO-based device.

PERFORMANCE ANALYSIS OF ATM SWITCH FABRIC WITH COMBINED-INPUT/OUTPUT BUFFERING

This paper analyses the performance of the ATM switch fabric with Combined-Input/ Output Buffering(C-IOB) under two different service principles for the cells at the head of line (HOL) positions of input buffers: First Come First Service (FCFS)/Random Service(RS) for the set of HOL cells addressed to a given output port with different/same "age" (the waiting time at the HOL position) and Pure Random Service(PRS) for all HOL cells addressed to a given output port regardless of their "ages" while the Queue Loss (QL) transfer scheme is adopted for interaction between input and output buffers in the ATM switch fabric. The results obtained show that the C-IOB ATM switch fabric with PRS service policy and the QL transfer scheme is better than other buffering ATM switch fabrics.

新时代推进“第二个结合”的价值意蕴、原则要求和现实路径

“第二个结合”作为又一次思想解放,是新时代持续推动党的理论创新的重要前提、努力实现中华优秀传统文化现代转型的内生动力、自觉担负新的文化使命的科学指南、不断促进与世界文明交流互鉴的坚实保障。新时代新征程不断推进“第二个结合”,要在遵循理论性与实践性、守正性与创新性、学理性与大众性、历史性与现实性、民族性与世界性辩证统一原则的基础上,把握结合方向、培育结合主体、丰富结合载体、拓展结合视域,实现马克思主义思想精髓同中华优秀传统文化精华的贯通融通,聚变为新的理论优势,为在新的起点上继续推动文化繁荣、建设文化强国、建设中华民族现代文明,以文化复兴助力民族复兴奠定坚实的思想基础。

磁场调制电机的由来、发展与挑战

得益于磁场调制效应,磁场调制电机具有高转矩密度优势,在风力发电、舰船推进、工业驱动等低速大转矩直驱领域具有广阔应用前景。该文首先介绍磁场调制电机的由来,并梳理该类电机基础理论和分析方法的发展与完善过程;进一步,对磁场调制电机进行分类并介绍其工作原理;同时,归纳磁场调制电机转矩密度、功率因数等关键电磁性能的提升方法。最后,总结磁场调制电机领域取得的主要研究成果,并讨论该类电机所面临的技术挑战和未来发展方向。