基于节点剩余功率的多中继选择算法

提出一种基于节点剩余功率的多中继放大转发协同节点选择算法,根据节点信道状态信息(CSI)和剩余能量信息对网络生存时间进行优化,使用加权函数和信道容量增益门限进行多协同节点选择。仿真结果表明,对于动态和固定功率分配,该算法选择三四个中继可使协同通信系统性能达到最优;相对基于CSI的单中继选择算法,当中继数为4时,其在动态功率分配时的网络生存时间最高可延长82%。     

Study on sub-cycling algorithm for flexible multi-body system: stability analysis and numerical examples

Numerical stability is an important issue for any integral procedure. Since sub-cycling algorithm has been presented by Belytschko et al. (Comput Methods Appl Mech Eng 17/18: 259–275, 1979), various kinds of these integral procedures were developed in later 20 years and their stability were widely studied. However, on how to apply the sub-cycling to flexible multi-body dynamics (FMD) is still a lack of investigation up to now. A particular sub-cycling algorithm for the FMD based on the central difference method was introduced in detail in part I (Miao et al. in Comp Mech doi: 10.1007/s00466-007-0183-9) of this paper. Adopting an integral approximation operator method, stability of the presented algorithm is transformed to a generalized eigenvalue problem in the paper and is discussed by solving the problem later. Numerical examples are performed to verify the availability and efficiency of the algorithm further.     

DDoS放大攻击原理及防护

分布式拒绝服务攻击（DDoS）是一种攻击强度大、危害比较严重的网络攻击。 DDoS放大攻击利用放大器对网络流量具有放大作用的技术,向被攻击目标发送大量的网络数据包,造成被攻击的目标网络资源和带宽被耗尽,使得正常的请求无法得到及时有效的响应。简单介绍DDoS放大攻击的原理,分析DDoS放大攻击的防护方法,从攻击源头、放大器、被攻击目标等三个方面采取防护措施,从而达到比较有效的防护效果。     

心率模拟信号处理电路的仿真研究和设计

为保证基于FPGA数字心率计设计的性能,心率信号处理的模拟电路设计至关重要,由于外围电路存在噪声干扰,如何优化设计该电路,以有效地提取心率信号是传统设计的难点.利用Multisim仿真,可以很好地解决传统设计方法难以实现的电路优化设计.Multisim仿真把传统的硬件设计、调试、仿真集成在一个软件环境下,边设计边修改边调试,经过不断地参数设计和电路的调试,将心率模拟信号处理电路分为前级、中级和末级多级放大,低通、高通和陷波多级滤波,最终经过整形得到心率的数字信号.实践表明,改进电路有效地去除噪声,可提取正确心率信号,达到了理想的设计效果.证明仿真设计为信号处理电路提供了一个有效手段.     

梯型熔解温度等温扩增检测食品中植物源成分的内标方法构建

目的 为梯型熔解温度核酸等温扩增(ladder-type melting temperature isothermal amplification, LMTIA)检测食品中植物源特异性基因建立内标方法, 同时可作为检测肉制品中植物成分的LMTIA方法。方法 针对植物ITS的共有序列, 设计LMTIA引物, 优化反应温度, 测定灵敏度, 并评估淀粉制品、蜂蜜、食用油DNA提取方法与LMTIA检测方法的适应性, 以H2O、鸭肉、鸡肉、羊肉、猪肉和牛肉基因组为阴性对照测试LMTIA方法的假阳性。结果 所建LMTIA方法在最优温度57 ℃时, 灵敏度为10 pg/μuL 玉米基因组与10 pg/μL玉米基因组, 可检出肉制品掺入0.1%的玉米淀粉, 并且所选淀粉制品、蜂蜜、食用油DNA提取方法均适用于LMTIA检测, 并且所有阴性对照样品在测试中均未出现假阳性。结论 本研究建立了LMTIA检测食品中植物源特异性基因的内标方法, 排除了DNA提取引起的LMTIA检测的假阴性, 同时为肉制品中植物成分定性检测建立了LMTIA方法。     

Generation of Reference Material by the Use of Multiple Displacement Amplification (MDA) for the Detection of Genetically Modified Organisms (GMOs)

The identification of genetically modified (GM) organisms (GMOs) in unknown samples by polymerase chain reaction (PCR) requires the use of a positive control sample, containing the target sequence derived from the respective GMO. For this purpose, either DNA extracted from suitable reference material or plasmids bearing the sequence are used. In the case of isolated genomic DNA, the preparation is cost-intensive and time-consuming, and material availability may be limited. Once the sequence is cloned into a plasmid, it may be simpler and less cost-intensive to purify the DNA, but contamination risk is substantially higher. The potential of multiple displacement amplification (MDA) as a new tool to generate reference material for GMO detection was studied taking the GM maize MON810 as a case. MDA yield of maize-specific DNA and amplification efficiency in dependence of the amount of starting material were estimated using real-time PCR. Applicability of the amplified DNA for the use as reference material was tested with regard to real-time PCR performance and MDA bias. Depending on the amount of genomic DNA (gDNA) input into MDA, amplification rates in the range of 30-fold (100 ng input of gDNA) to 23,000-fold (0.1 ng input of gDNA) were achieved. Real-time PCR performance and gene representation of amplified DNA (mdaDNA) are comparable to those of gDNA. Our results demonstrate that the DNA amplified by MDA is suitable for the use as reference material for qualitative GMO analysis.     

核测井用小型光电倍增管高温特性的研究

本文简要介绍了三种国内外小型高温光电倍增管的热噪声、放大系数与温度的关系特性，通过实验测试，并加以比较，结果表明，对国产光电倍增管严格挑选的情况下，国产光电倍增管可以替代进口管．     

铜物理显影挽救微弱银影像

介绍了用铜物理显影方法挽救微弱银影像的技术。实验表明，对黑白负片拍摄的文汇报半调影像，曝光量可以减少至常规曝光量的１／１２５；对Ｘ光胶片拍摄的手指骨连续调底片，曝光量可以减少至常规曝光量１／３：铜物理显影方法更适合于半调影像。     

基于MSP430的微弱信号检测装置的设计

系统以MSP430为主控制芯片,实施对微弱信号输出的AD采样,并借助1602液晶将结果显示以提高人性化的操作。对于微弱信号及噪声源的处理,主要是使用反相求和比例运算器、Ⅱ型纯电阻衰减网络、射极跟随器、选频放大网络及精密整流路来组成信号检测电路,从而将稳定的直流信号输出给MSP430主控芯片。当输入正弦波信号VS的频率在100Hz-10kHz范围内、幅度峰峰值在20mV-200mV范围内时,以上模块可检测并显示正弦波信号的幅度值,且误差不超过5%。     

全柔性微位移放大机构的设计与分析

微机械放大器中常采用全柔性微位移放大机构来实现输出位移的放大,且大多采用短臂柔性铰链连接各构件。设计了一种对称的长柔性杆微位移放大机构,结合弹性力学和Bernoulli-Eu-ler假设,推导出该放大机构的力位移计算公式及放大比公式。对影响该机构放大比的关键因素进行了分析,通过实例分析得到该机构中的长柔性杆角度与输出位移之间的关系。同时用有限元方法对该实例进行了仿真分析,并对两种方法所得结果进行了分析比较。