互质阵MIMO雷达DOA估计性能综合分析

以非相干信号源为研究对象,综合分析了单基地互质阵多输入多输出(MIMO)雷达的波达方向(DOA)估计性能。首先,在总结归纳互质阵结构特点的基础上推导了基于和联合阵列及和差联合阵列的单基地MIMO雷达测向信号模型,然后结合多重信号分类(MUSIC)算法,分别详细介绍了基于和联合阵列及和差联合阵列的单基地MIMO雷达DOA估计方法,最后,进行与等阵元数的均匀线阵MIMO雷达的对比仿真实验,验证了互质阵MIMO雷达DOA估计性能的优越性。

“赛+课”融合模式下通识课程教学改革与实践——基于中国汽车工程学会巴哈大赛

0前言普通高校开展工程类专业的建设,一项重要的评估指标是通过中国工程教育专业认证协会的工程教育认证。以工程认证标准作为专业培养方案制定的指导性文件,其目的是为培养符合学校定位的、适应社会经济发展需要的工程技术类人才提供参照。

磁极偏心切向聚磁型并联结构混合励磁电机的振动噪声研究

以一台2.5 k W切向聚磁型并联结构混合励磁电机为研究对象,研究切向聚磁型并联结构混合励磁电机磁极偏心对电机振动噪声的影响。根据电机电磁振动噪声相关理论,建立磁极偏心切向聚磁型并联结构混合励磁电机模型,采用磁极偏心优化其气隙磁密畸变率和电磁噪声,分析该电机在优化前后径向电磁力的阶次、频率特征,并对该电机的定子进行模态分析,利用ANSYS Workbench仿真平台搭建电机振动噪声耦合模型,计算优化前后电机的振动响应与噪声变化。结果表明:采用磁极偏心能有效优化电机气隙磁密和电磁力密度,气隙磁密谐波畸变率显著下降,电磁力(16,4 f1)分量幅值减小74%,从而可达到抑制电机振动噪声的目的。

基于遗传算法和TOPSIS法的混合励磁电机齿槽转矩优化

针对切向聚磁型并联结构混合励磁电机(TMPS-HESM)随着励磁电流增加导致齿槽转矩剧增容易引发电机振动噪声的问题,根据齿槽转矩的产生原理,探讨改变转子极靴宽度、磁极偏心距和气隙长度削弱电机齿槽转矩的可行性。借助Maxwell and Workbench and Optislong联合仿真软件建立8极48槽TMPS-HESM模型,运用遗传算法进行全局多目标优化,得到pareto最优解集后使用优劣解距离法(TOPSIS)客观选取最优解。最后对比分析优化前后电机的各项其他性能,结果表明:采用遗传算法和TOPSIS法对电机参数进行优化,能提升电机多目标优化效率,不仅可解决混合励磁电机励磁电流增加导致齿槽转矩剧增的问题,还能有效削弱电机转矩脉动,提升电机平均转矩,在减少电机的振动噪声和提高电机输出转矩方面均取得改善。

基于矩阵束的嵌套MIMO雷达快速DOA估计方法

对于非相干信源,在低信噪比和少快拍数条件下,针对单基地嵌套多输入多输出(MIMO)雷达利用旋转不变子空间(ESPRIT)算法进行波达方向(DOA)估计时精度不高的问题,提出了基于矩阵束的快速DOA估计方法。首先,将单基地嵌套MIMO雷达接收数据协方差矩阵向量化,并对其中重复数据进行冗余平均处理得到“和差联合阵列”虚拟接收数据;然后,对该单快拍的等效均匀线阵接收信号矢量构造矩阵束;最后,利用前向或前后向矩阵束算法来估计目标角度。文中所提算法具有更高的DOA估计精度和更低的算法复杂度,且在低信噪比和少快拍数条件下仍能有效估计目标角度。仿真实验与总体最小二乘ESPRIT算法进行对比,验证了所提算法的有效性和优越性。

北秦岭二郎坪弧后盆地俯冲消减的构造演化时限

秦岭造山带早古生代发育一套完整的"沟—弧—盆"体系,其中二郎坪群作为弧后盆地的代表。为了查明二郎坪弧后盆地俯冲消减的构造演化时限,本文以二郎坪群及其相关侵入岩体为研究对象,进行了锆石U-Pb年代学研究。结果表明,火神庙组斜长角闪片岩测得锆石U-Pb加权平均年龄为495.2±6.9 Ma,属于原岩的结晶年龄;侵入二郎坪群内部的变形岩体主要代表板山坪岩体、张家庄岩体、郭家幔岩体,测得其结晶年龄分别为:479.9±5.6 Ma、461.5±5.4 Ma和456.5±6.3 Ma。板山坪岩体的变形特征与二郎坪群北部岩片向北俯冲消减特征相同,张家庄岩体、郭家幔岩体的变形特征与二郎坪群南部岩片向南俯冲消减特征相同。另外,在二郎坪群南部岩片内部发现顺面理面侵入的未变形岩脉,其结晶年龄为427.8±5.4 Ma,以及切穿二郎坪群南部岩片面理的未变形岩脉,给出一颗锆石结晶年龄为388 Ma。综合上述以及前人研究成果,认为二郎坪弧后盆地可能于460 Ma闭合,其俯冲消减方式为双向式俯冲,并且两侧岩片俯冲变形可能持续至427 Ma,最终岩石俯冲变形结束时间上限为388 Ma。

基于双边拍卖机制的频谱切换算法研究

随着无线电业务的爆炸式增长,频谱稀缺成为无线通信中一个棘手的问题。在此背景下,认知无线电网络应运而生,而选择最佳的信道进行频谱切换是认知无线电网络面临的一个挑战。目前,利用博弈论选择最佳信道进行频谱切换被证明是有效的方法。研究了一种基于双边拍卖机制的认知无线网络频谱切换优化方案,提出了一种基于传输率的报价算法。仿真结果表明,利用该方案选择最佳信道进行频谱切换十分有效。

北秦岭板山坪岩体锆石U-Pb年代学及岩石成因研究

板山坪岩体是北秦岭二郎坪群中的侵入岩。为了查明该岩体的成因,对该岩体进行了锆石U-Pb年代学、锆石原位Hf同位素研究以及矿物化学分析等方面的研究。研究结果表明,板山坪岩体岩性组成主要为石英闪长岩和花岗闪长岩,花岗闪长岩内部存在暗色包体。本次研究获得板山坪石英闪长岩锆石U-Pb年龄为442.7~432.2 Ma,花岗闪长岩锆石U-Pb年龄为436.8~432.7 Ma,暗色包体锆石U-Pb年龄为437.6 Ma。锆石176Hf/177Hf值为0.282 737~0.282 736,εHf(t)值集中分布在8.4~9.4之间,二阶段Hf模式年龄(TDM2)在876~832 Ma之间。石英闪长岩结晶温压分别为673 ℃~745 ℃和0.19~0.54 GPa,花岗闪长岩结晶温压分别为657 ℃~730 ℃和0.48~0.96 GPa,暗色包体结晶温压分别为680 ℃~734 ℃和0.69~1.65 GPa。综合分析认为板山坪岩体为复式岩体,两期结晶年龄分别为496~487 Ma和442~432 Ma。岩石来源于地幔分离出来的新生下地壳。

雷达与通信用频兼容性测量模型分析

针对地面防空作战中雷达与通信装备之间的电磁兼容问题,采用干扰余量来描述同频或邻频装备系统间的电磁兼容程度。根据天线方向性进行分类,地面防空作战中的雷达与通信用频装备天线主要有全向和定向两种。首先建立了两种方向天线的电磁兼容模型,其次综合得到整个用频系统的电磁兼容测量模型,最后对几个重要的技术参数与电磁兼容程度的关系进行了仿真定量分析。该研究给地面防空作战中雷达及用频装备的部署优化提供了新方法,为分析雷达通信协同情报组网时的效益最大化奠定了理论基础。

红细胞药物递送系统的研究进展

载药纳米粒、脂质体、微球和微囊等微粒给药系统,成为近年来的研究热点,但其自身稳定性能较差,且给药后易被人体免疫系统捕获和清除,生物利用度低。红细胞作为内源性细胞,具有高生物安全性和低免疫原性等优点,是一种极具应用前景的新型药物递送系统,已成为相关领域的研究热点。基于此,综述了红细胞仿生给药系统的概况及研究进展,总结了基于红细胞的载药技术和方法,阐述了目前红细胞药物递送系统的优缺点及其发展趋势。

非肌层浸润性膀胱癌患者经尿道膀胱肿瘤电切术后复发的影响因素

目的分析非肌层浸润性膀胱癌(NMIBC)患者经尿道膀胱肿瘤电切术(TURBT)后复发的影响因素。方法回顾性分析168例NMIBC患者临床资料,患者均进行TURBT治疗。术后随访2年,统计患者复发情况,根据结果分为复发组与未复发组,分析NMIBC患者术后复发的影响因素。结果随访2年,168例NMIBC患者有34例出现复发,占比为20.24%(34/168)。未复发组中再发、T1分期、肿瘤低分化、多发肿瘤占比均低于复发组,差异有统计学意义(P<0.05);2组性别、年龄、体质量、肿瘤直径、有无基础病对比,差异无统计学意义(P>0.05)。Logistic回归分析:发病状况为再发、T1分期、肿瘤低分化、多发肿瘤是NMIBC患者术后复发的独立危险因素(P<0.05且OR≥1)。结论NMIBC患者TURBT术后仍有一定复发情况,影响因素较多,包括再发性肿瘤、T1分期、肿瘤低分化、多发肿瘤。

钬激光剜除术联合辅助化疗及膀胱热灌注化疗治疗T2期膀胱癌的临床疗效观察

目的观察钬激光剜除术联合辅助化疗及膀胱热灌注化疗治疗T2期膀胱癌的临床疗效。方法回顾性分析2018年1月-2019年6月在安阳市人民医院行钬激光剜除术联合辅助化疗及膀胱热灌注化疗治疗的42例T2期膀胱癌患者的临床资料,统计术中、术后相关指标,分析治疗的安全性及有效性。结果所有患者手术均成功,手术时间(25.17±8.28)min,术中出血(10.26±3.27)mL,术中无闭孔神经反射、膀胱穿孔及尿外渗发生;术后辅助化疗期间相关并发症的发生率分别为骨髓抑制52.38%、消化道症状73.81%、脱发14.29%、其他并发症19.05%,无致死等严重并发症发生;膀胱热灌注化疗相关并发症的发生率分别为排尿刺激症状26.19%、肉眼血尿7.14%、泌尿系感染16.67%、其他并发症11.90%。术后随访12个月时,共5例患者在非手术部位发生复发,复发率为11.90%。结论钬激光剜除术联合辅助化疗及膀胱热灌注化疗治疗T2期膀胱癌安全、有效。

基于双标图差异分析的离子选择电极营养液建模研究

基于双标图法量化表征了山崎生菜、山崎草莓、山崎番茄、康奈尔生菜、康奈尔草莓5种营养液配方以及NO3^-N、PO4^-P、K^+、Ca^2+、Mg^2+、NH4^-N、SO4^-S7种养分元素间的差异性。研究表明,NO3-N、K+、Ca2+在差异性及含量比例皆排在前3位,同时山崎系列营养液配方与康奈尔系列营养液配方各自具有高度相关性。通过分别建立统一的建模样本集合进行支持向量机(SVM)模型训练,实现了对NO3^-N、K+、Ca^2+的准确测量,相比于未进行差异性分析为输入的SVM预测模型,在山崎配方环境下,平均相对误差分别从7.66%、11.88%、11.55%减小至6.41%、6.14%、10.20%;在康奈尔配方环境下,平均相对误差则分别降低了1.79、2.98、1.13个百分点。基于双标图营养液配方分析方法可为无土栽培营养液电极法监测提供参考。

硅酸盐单矿物主、微量元素的LA-ICPMS分析及影响因素

文章利用美国193nm ArF型准分子激光剥蚀系统和Agilent 7500a型的ICPMS联机,采用直径为44μm的激光束斑,对BCR-2G、T1-G及StHs6/80-G 3个国际标准物质的熔融玻璃进行了LA-ICPMS的10种主量元素和47种微量元素分析,分别以NIST 610、GSE-1G及MPI-DING国际标准物质作外标,采用Ca为归一化元素,分别利用无内标和以Ca为内标进行校正,获得了满意的结果;并且对比了同一套数据采用不同校正策略所获得的结果之间的差别,初步探讨了造成这些差别的原因。研究结果显示,大部分主、微量元素的相对误差一般优于10%,少部分元素的相对误差在10%~20%之间,极个别元素的相对误差超过20%,这些个别元素相对误差较大的原因可能与样品中的元素质量比极低有关。研究结果表明,该实验室建立的硅酸盐单矿物的LA-ICPMS主微量元素的测试方法是可行的。

基于水杨醛荧光探针的营养液镁离子检测方法

镁离子(Mg^(2+))是植物光合、呼吸及遗传物质合成等重要生理过程的必需营养元素,准确检测无土栽培营养液中Mg^(2+)含量对作物生产调控具有重要意义。Mg^(2+)荧光探针材料合成复杂且易受钙离子(Ca^(2+))、锌离子(Zn^(2+))干扰。本研究采用水杨醛荧光探针开展了营养液Mg^(2+)检测,系统测定了该分子探针的灵敏性、选择性、抗干扰性,并通过加标回收率结果证明了水杨醛荧光探针测定的重复性。试验结果表明:在Mg^(2+)浓度0~800μmol/L范围内,水杨醛探针荧光响应强度线性良好,决定系数达到0.999,响应时间约为2 min,可实现对溶液中Mg^(2+)的快速测定;探针对Mg^(2+)的选择性良好,等浓度Ca^(2+)、Zn^(2+)荧光响应强度同比增长系数仅为Mg^(2+)强度的2.5%、9.1%。同时,探针具有较好的抗干扰性,Ca^(2+)、Zn^(2+)与Mg^(2+)等量共存,较单一Mg^(2+)溶液水杨醛荧光探针测定荧光强度同比增长系数在-0.004~0.009之间,上下波动小于0.01。Ba^(2+)、Cu^(2+)、Mn^(2+)、Fe ^(2+ )、Fe ^(3+)对水杨醛探针存在荧光猝灭影响;实际样本的加标回收率为99%~104.9%,较离子色谱法测定结果的相对误差不大于1.33%,RMSE为5.78 mol/L。本研究初步验证了水杨醛荧光探针用于营养液Mg^(2+)检测的可行性。

被保护层工作面瓦斯来源分析及治理技术

为研究被保护层高瓦斯工作面瓦斯来源,综合运用分源预测、统计、碳同位素分析等方法,首次发现了被保护层工作面上覆围岩一次破坏形成的裂隙中残存有大量游离瓦斯。在朱集东煤矿被保护层1111(3)工作面进行工程实践,优化了“顶板走向钻孔+边孔”系统布置,改进了护孔套管连接方式,“管到底”率达到95%,单孔瓦斯抽采量增加3.5倍左右,工作面瓦斯抽采率达到88%,回风瓦斯浓度控制在0.36%以下,平均0.12%,平均日产量8300t,实现了安全高产高效。

Regional disparities of phytoplankton in relation to environmental factors in the western Arctic Ocean during summer of 2010

Global warming has caused Arctic sea ice to rapidly retreat,which is affecting phytoplankton,the primary producers at the base of the food chain,as well as the entire ecosystem.However,few studies with large spatial scales related to the Arctic Basin at high latitude have been conducted.This study aimed to investigate the relationship between changes in phytoplankton community structure and ice conditions.Fifty surface and 41 vertically stratified water samples from the western Arctic Ocean（67.0°–88°26′N,152°–178°54′W） were collected by the Chinese icebreaker R/V Xuelong from July 20 to August 30,2010 during China＇s fourth Arctic expedition.Using these samples,the species composition,spatial distribution,and regional disparities of phytoplankton during different stages of ice melt were assessed.A total of 157 phytoplankton taxa（〉5 μm） belonging to 69 genera were identified in the study area.The most abundant species were Navicula pelagica and Thalassiosira nordenskioeldii,accounting for 31.23% and 14.12% of the total phytoplankton abundance,respectively.The average abundance during the departure trip and the return trip were 797.07×10~2 cells/L and 84.94×10~2 cells/L,respectively.The highest abundance was observed at Sta.R09 in the north of Herald Shoal,where Navicula pelagica was the dominant species accounting for 59.42% of the abundance.The vertical distribution of phytoplankton abundance displayed regional differences,and the maximum abundances were confined to the lower layers of the euphotic zone near the layers of the halocline,thermocline,and nutricline.The species abundance of phytoplankton decreased from the low-latitude shelf to the high-latitude basin on both the departure and return trips.The phytoplankton community structure in the shallow continental shelf changed markedly during different stages of ice melt,and there was shift in dominant species from centric to pennate diatoms.Results of canonical correspondence analysis（CCA） showed that there were two distinct communities of phytoplankton in the western Arctic Ocean,and water temperature,ice coverage and silicate concentration were the most important environmental factors affecting phytoplankton distribution in the surveyed sea.These findings will help predict the responses of phytoplankton to the rapid melting of Arctic sea ice.

Ecological characteristics of phytoplankton community from eutrophic waters in the Maluan Bay

present study is based on the analysis of the data collected in 10 dnas during the periods of 2 surveys (from May 1992 to January 1993 and from August 1993 to May 1994). The results show that the number ofphytoplankton in highly eutrophic waters of the Maluan Bay is low, Only 6-35 spotes from each cruise and 66species in total fain the 2 surveys. The phytoplanha abundanCe is high. The mean cell densities of phytoplanktonfrom the net samples were 21 386x 104 cells/m3 for the first sUrVey and 110 136 x 104 cells/m3 for the second survey,that fm the water Samples was 1 150. 7 cells/cm3. The mean concentration of chlorOPhyll a reachs 6. 67 mg/m3.Both the species diversity (H') and evennes (J) were low, only 0. 78 and 0. 28, restwhvdy. The temporal and spatial fluctuation of the cell denSity of phytoplankton was quite wificant, caused banly by contribution of pennate diatom Nitzschia delicatissima that often abudanily occurred in a ofed waters rich in organic matter and could be takenas an ecologic indicator of highly eutrophic harbour. The axistence of good correlation between the cell density ofNitzschia delicatissima and some environmental variables (e. g. Po43 - P and COD, etc. ), and the heterotrophic tendancy of this species are discussed, too.

浮游植物

在海洋生态系统里,形成物质和能量循环的基础是浮游植物。由于其种群结构和数量分布的变动等通常是栖息环境直接的综合效应,因而在估计水域生产力、评价环境质量和探讨水系消长等方面都有一定的指示作用。有关厦门港浮游植物的生态特点,厦门大学金德祥教授曾作过详尽研究(主要根据厦鼓水道的定点采样)。

Community structure and spatial-temporal variation of netzphytoplankton in the Bering Sea in summer

Marine biodiversity is changing in response to altered physical environment, subsequent ecological changes as well as anthropogenic disturbances. In this study, phytoplankton samples in situ collected in the Bering Sea in July of 1999 and 2010 were analyzed to obtain phytoplankton community structure and spatial-temporal variation between the beginning and end of this decade, and the correlation of phytoplankton community dynamics and environmental factors was investigated. A total of 5 divisions, 58 genera and 153 species of phytoplankton belonging to 3 ecological groups were identified. The vast majority of phytoplankton consisted of diatoms accounting for 66.7% of the total species and 95.2% of the total abundance. Considering differentiation in spatial extent and phytoplankton sample types, there were subtle changes in species composition, large altering in abundance and significant variation in spatial distribution between two surveys. The abundance peak area was located at the Bering Strait while sub peak was found at the Bering Sea Basin. The boreal-temperate diatom was the dominant flora, which was subsequently replaced by eurythermal and frigid-water diatom. Phytoplankton community in the Bering Sea was not a simplex uniform community but composed of deep-ocean assemblage and neritic assemblage. The deep-ocean assemblage was located in the northwestern Pacific Ocean and Bering Sea Basin, dominated by boreal-temperate species（Neodenticula seminae, Thalassiothrix longissima, Amphiprora hyperborean, Chaetoceros atlanticus, Thalassiosira trifulta, etc.） and eurychoric species（Thalassionema nitzschioides, Ch. compressus, Rhizosolenia styliformis, etc.）, and characterized by low abundance, even interspecies abundance allocations, diverse dominant species and high species diversity. The neritic assemblage was distributed on the continental shelf and slope of Bering Sea and was mainly composed of frigid-water species（Th.nordenski？ldii, Ch. furcellatus, Ch. socialis, Bacteriosira fragilis, etc.） and eurythermal and euryhaline species（L.danicus, Ch. curvisetus, Coscinodiscus curvatulus, etc.）, and it was characterized by high abundance, uneven interspecies allocations, prominent dominant species and low species diversity. Spatial-temporal variation of species composition and abundance of phytoplankton in the Bering Sea was directly controlled by surface circulation,nutrient supply and ice edge.