PERFORMANCE ANALYSIS OF TIME-HOPPING M-ARY UWB WIRELESS SYSTEM USING V-BLAST ALGORITHM

Ultra WideBand (UWB) transmissions are attractive for low power, baseband asynchronous multiple access and peer-to-peer wireless communications. Multiple Input Multiple Output (MIMO) technology is useful in combating against multipath and at the same time improves system performance by using multielement antennas at both transmitter and receiver.This letter proposes a time hopping M-ary UWB systems using V-BLAST algorithm, and power control is considered for better performance. Simulations are provided to compare performance with different antennas.

A NEW METHOD FOR FINDING THE NATURAL FREQUENCY SET OF A LINEAR TIME-INVARIANT NETWORK

提出了一种求线性定常ｎ阶网络的固有频率集的新方法，给出了通用方程的推导及证明．该方法首次将ｎ阶网络的固有频率与ｎ端口网络参数相联系，方程形式简洁对偶，物理意义明确，求解简捷规范且不会产生丢根现象，具有通用性和系统性．

New Zircon U-Pb Age of the Babu Ophiolites in Southeast Yunnan,China and Constrains of Plate Subduction Time

Objective The Babu ophiolite in Malipo County of southeastern Yunnan is interpreted as remanant ocean crust and represents a possible branch of Paleo-Tethyan Ocean in South China. It consists mainly of mafic and ultramafic rocks. These rocks are very important to understand the evolution of the Paleo-Tethyan Ocean. However, the Babu ophiolite is still disputed and the mafic and ultramafic rocks have been inferred to be part of the Emeishan large igneous province （LIP） by some researchers. In this paper, we present zircon U-Pb data on the metabasalts in Malipo to reveal the formation time of mafic and ultramafic rocks and their tectonic nature.

New Evidence of Detrital Zircon Ages for the Final Closure Time of the Paleo-Asian Ocean in the Eastern Central Asian Orogenic Belt(NE China)

Objective The NE China is located in the eastern segment of the Central Asian Orogenic Belt（CAOB）,which is a large accretionary orogen between the Siberian Craton and the North China Craton（NCC）.Many researches have discussed about the evolution of the Paleo-Asian Ocean（PAO）in the eastern CAOB.However,

Time-Hopping Sequence Design for Virtual Full Duplex via Rapid On-Off-Division Duplex

To achieve virtual full-duplex(VFD)communication using half-duplex radios,the rapid on-off-division(RODD)technique has been proposed in recent years.The time-hopping(TH)sequence is critical to controlling self-interference introduced in the paradigm.By constructing the collision model with a symbol level time scale,the periodic collision correlation function properties are introduced as the performance metric for the TH sequence in the RODD system.To achieve the best VFD performance,an optimization-based method for TH sequence design is proposed.In addition,the conventional TH frame structure design for RODD system is improved.Numerical simulations are presented to demonstrate that the proposed approach can significantly increase system performance.Results indicate that the TH sequence design is very effective for the RODD system.

Strengthening Exchanges and Cooperation in the Northeast Asia Region Follows the Trend of the Times——Sidelights of the 10^(th) Northeast Asia Youth Forum

The 10thNortheast Asia Youth Forum,with the theme of China-ROK-Japan Youth Employment Guidance,sponsored by Moral Re-Armament/Initiatives of Change(MRA/IC)-Korea was held in Seoul and Cheonan from August 12 to 17.Seventy five college students from 37 universities sent by China International Youth Exchange Center,Moral Re-Armament/Initiatives of Change(MRA/IC)-Korea and Japan Society attended the Forum.Lee Boksil,Vice-Minister of Ministry of

A Multi-Hop Dynamic Path-Selection (MHDP) Algorithm for the Augmented Lifetime of Wireless Sensor Networks

In Wireless Sensor Networks (WSN), the lifetime of sensors is the crucial issue. Numerous schemes are proposed to augment the life time of sensors based on the wide range of parameters. In majority of the cases, the center of attraction will be the nodes’ lifetime enhancement and routing. In the scenario of cluster based WSN, multi-hop mode of communication reduces the communication cast by increasing average delay and also increases the routing overhead. In this proposed scheme, two ideas are introduced to overcome the delay and routing overhead. To achieve the higher degree in the lifetime of the nodes, the residual energy (remaining energy) of the nodes for multi-hop node choice is taken into consideration first. Then the modification in the routing protocol is evolved (Multi-Hop Dynamic Path-Selection Algorithm—MHDP). A dynamic path updating is initiated in frequent interval based on nodes residual energy to avoid the data loss due to path extrication and also to avoid the early dying of nodes due to elevation of data forwarding. The proposed method improves network’s lifetime significantly. The diminution in the average delay and increment in the lifetime of network are also accomplished. The MHDP offers 50% delay lesser than clustering. The average residual energy is 20% higher than clustering and 10% higher than multi-hop clustering. The proposed method improves network lifetime by 40% than clustering and 30% than multi-hop clustering which is considerably much better than the preceding methods.

指数有界双连续n阶α次积分C半群的扰动

利用经典算子半群理论中的研究方法,在指数有界双连续α次积分C半群的基础上,讨论了指数有界双连续n阶α次积分C半群的扰动定理。设A为次生成元的指数有界双连续n阶α次积分C半群{T(t)}_(t≥0),B为界线性算子,A、B、C可交换,则在一定条件下,C^(-1)(A+B)C_(B)生成双连续n阶α次积分C半群{T_(B)(t)}_(t≥0),并给出T_(B)(t)的表达式,从而推广了n阶α次积分C半群相关的扰动定理。

Promote the All-round Development of China's Human Right Cause in the New Era——Summary of the Symposium on “Deeply Studying and Implementing the Spirit of the 20th CPC National Congress and Adhering to the Chinese Path of Human Rights Development”

On November 8, 2022, the symposium on “Deeply Studying and Implementing the Spirit of the 20thCPC National Congress and Adhering to the Chinese Path of Human Rights Development” was held by the China Society for Human Rights Studies in Beijing. Focusing on “the leadership of the CPC and human rights development”, “adapting Marxism to the Chinese context and the needs of our times and human rights theories in contemporary China”, “the Chinese path to modernization and the new form of human rights civilization”, “Chinese human rights solutions and global human rights governance”, “making a better China’s story of advancing human rights and constructing human rights discourse system”, and other topics, the participants reached broad consensus after discussion, and the symposium achieved fruitful results.

基于自发数据传输的高效双LAN太赫兹无线局域网MAC协议

针对现有的双局域网(LAN)太赫兹无线局域网(Dual-LAN THz WLAN)相关介质访问控制(MAC)协议中存在的某些节点会在多个超帧内重复发送相同的信道时隙请求帧以申请时隙资源以及网络运行的一些时段存在空闲时隙等问题,提出一种基于自发数据传输的高效MAC协议——SDTE-MAC(high-Efficiency MAC protocol based on Spontaneous Data Transmission)。SDTE-MAC通过让各节点都维护一张或多张时间单元链表,使各节点与其余节点在网络运行时间上达到同步,从而获悉各节点应该在信道空闲时隙的什么位置开始发送数据帧,优化了传统的信道时隙分配和信道剩余时隙再分配的流程,提高了网络吞吐量和信道时隙利用率,降低了数据时延,能够进一步提升双LAN太赫兹无线局域网的性能。仿真结果表明,网络饱和时,相较于AHT-MAC(Adaptive High Throughout multi-pan MAC protocol)中的N-CTAP(Normal Channel Time Allocation Period)时段时隙资源分配新机制以及自适应缩短超帧时段机制,SDTE-MAC的MAC层吞吐量提升了9.2%,信道时隙利用率提升了10.9%,数据时延降低了22.2%。

指数有界n阶α次积分C群的紧性

利用指数有界n阶α次积分C群及其次生成元的定义,并借助经典算子理论的研究方法,给出了指数有界n阶α次积分C群紧的定义,从而推导出指数有界n阶α次积分C群的紧性的一些性质。

基于单矢量水听器时频声强法的非合作水声跳频信号多维参数估计

针对传统方法对水下非合作跳频信号的多维参数估计效果不佳的问题,提出一种基于单矢量水听器时频声强法的非合作水声跳频信号空时频参数估计方法。利用矢量水听器声压通道与振速通道的接收信号建立时频域的短时互谱分布,分析噪声与信号在时频域分布的差异,通过迭代去噪法与连通域方法,对噪声进行抑制并平滑每跳的能量分布;采用复声强法对短时互谱矩阵进行处理,得到清晰稳定的跳频信号空时频分布;提取空时频分布的脊线并利用Haar小波变换对脊线进行奇异点检测,估计出信号的多维参数。仿真和水池试验结果表明,当信噪比大于-5 dB时,所提方法得到的参数估计归一化均方根误差小于0.05。

热载流子多结太阳能电池CdSe/CdS核壳量子点和纳米片的声子瓶颈效应机理

热载流子多结太阳能电池(HCMJSC)是热载流子及叠层电池概念相结合而提出的一种较有前景的第三代太阳能电池之一,其理论效率在一个标准太阳条件(即1000 W/m 2,25℃)下将高于65%,远高于32%的单节硅基电池极限效率。该型电池主要包括一个宽带隙的顶结薄膜和一个适中带隙的厚底结基底,以分别高效吸收利用高能和低能光子。其广泛应用于光电器件的宽带隙CdSe/CdS低维材料体系(如量子点、纳米片等)有望成为顶结薄膜的合适候选材料。然而,该材料体系中的声子瓶颈效应(PBE)机理目前尚不明晰。文章主要研究了CdSe/CdS核壳量子点(QDs)和纳米片(NPLs)中的PBE机理;通过稳态光致发光(SSPL)和皮秒时间分辨尺度光致发光(ps-TRPL)技术,计算该材料体系的热弛豫系数(Q th),从而定量分析激发载流子的弛豫速率,同时阐述了PBE和量子点中常见的俄歇复合之间的耦合关系,最终系统研究了QDs和NPLs中载流子弛豫过程机理,提出HCMJSC的发展路径和建议。

跳时超宽带(TH-UWB)多址系统性能的研究

针对多用户跳时超宽带(TH-UWB)系统建立了数学模型,其目的在于研究多址干扰对TH-UWB系统各方面性能的影响。利用多址干扰服从高斯分布的特性,分析了多址系统的误码率性能,得到了系统数据速率及上界的解析数学表达式,并将误码率理论值与实验数据进行了比较。仿真结果表明,误码率理论值与实验值一致。此外,还分析了在不同的室内密集信道下功率控制对系统数据速率的影响,结果表明,非精确的功率控制将导致系统的误码率及数据速率的下降,且可视距信道中的性能好于非可视距信道中的系统性能。

TH-PPM与TH-PAM超宽带系统的性能分析和比较

采用基于软判决和硬判决的方法,对跳时脉冲位置调制(time hopping-pulse position modulation,TH-PPM)和跳时脉冲幅度调制(time hopping-pulse amplitude modulation,TH-PAM)超宽带系统的误比特率性能进行了分析和比较.在加性高斯白噪声(additive white Gausses noise,AWGN)信道下,研究了TH-PPM和TH-PAM超宽带单用户系统接收端信号进行软判决和硬判决时的性能,同时分析比较系统在两种调制方式下采用不同脉冲重复次数时的性能差异.仿真结果表明,在AWGN信道下,TH-PPM和TH-PAM的系统性能均随脉冲重复次数的增加而明显改善,并且后者优于前者.此外,采用软判决时的系统性能优于采用硬判决时的系统性能.

宽带跳频TDMA辐射源网群的定位及网群划分方法

为了解决现有方法难以对宽带跳频时分多址(frequency hopping-time division multiple access,FH-TDMA)辐射源网群定位的问题,提出一种仅利用波达方向(direction of arrival,DOA)信息的多站定位及网群划分方法。首先通过模拟滤波对各站接收到的信号进行频段划分,通过基于多相滤波的数字信道化方法把信号输出到多个信道中;然后通过直接定位(direct position determination,DPD)算法计算得出各时隙辐射源的位置;最后先通过不同参数的基于密度的噪声应用空间聚类(density-based spatial clustering of applications with noise,DBSCAN)算法选择出最佳的辐射源定位结果,再根据提出的基于先验信息的改进K-means聚类算法进行网群划分。所提方法实现了采样率和信号处理速率的降低,且无需站间严格的时间同步。结果表明,所提方法有效估计出了辐射源的数量、位置,以及网群划分情况。

甘肃阳山金矿独居石Th-U-Pb化学年龄及其地质和成矿意义

阳山金矿是西秦岭地区新发现的超大型金矿,作者运用电子探针测定了含矿花岗斑岩脉的独居石 Y-Th-U-Pb含量,采用 ChemAge 软件计算了各测点的表面年龄,各测点表面年龄落入3个组。第一组包括9个数据,来自独居石的核心部位,表面年龄变化于297-251 Ma,等时线年龄为268±4Ma(MWSD=0.24),记录了勉略洋俯冲引发的晚古生代弧岩浆活动。第二组包括12个数据,表面年龄变化于237～207Ma,等时线年龄为220±3Ma(MWSD=0.20),属花岗斑岩侵入结晶年龄,与西秦岭碰撞型花岗岩开始大规模发育的时间一致。第三组包括7件位于独居石边缘的测点,表面年龄变化于200～179Ma,等时线年龄为190±3Ma(MSWD=0.15),属阳山金矿的成矿时间。因此,阳山金矿成矿时间与西秦岭中生代陆陆碰撞体制的大规模流体成矿事件一致。

初发SLE病人Th1/Th2及调控因子IL-18基因研究

目的：探讨未经药物治疗初发狼疮病人Th1/Th2细胞亚群分布及其调控细胞因子、细胞因子受体基因表达的差异，试图揭示系统性红斑狼疮发病的免疫紊乱机理。方法：运用三色荧光标记法流式细胞术检测42例未经药物治疗初发狼疮病人细胞亚群分布，并以10例正常人作对照；ABI7700 real-time PCR法同时检测 38例未经药物治疗初发狼疮病人和 28例正常人IL-18及其受体mRNA表达水平的差异。结果：①初发狼疮病人Th1较正常人明显减低（P<0．05），但Th1/Th2无显著性改变。②与正常组相比，SLE组病人IL-18 mRNA及其受体表达较正常人明显降低（P<0．05）；③面部红斑组病人Th1/Th2较正常人明显降低（P<0．05）；④关节炎组SLE病人较无关节炎病人IL-18表达降低。结论SLE是一种以Th1细胞下降，Th2细胞相对占优势的免疫介导的自身免疫性疾病，源于诱导向Th1细胞分化的IL-18及其受体减少和细胞因子间失衡所致。

TH-UWB的码间干扰分析

由于UWB主要应用在密集多径的室内环境,所以研究多径效应造成的码间干扰对于设计高速UWB系统非常重要。分析了基于跳时多址的UWB的码间干扰效应。通过分析脉冲的各个多径分量与之后发送的脉冲的时间差的分布,得到了跳时UWB的码间干扰估算公式。与采用等间距发送脉冲时的码间干扰对比,结果显示,随着脉冲重复周期增大,跳时UWB的码间干扰的改善的速度比等间距发送脉冲时缓慢。