冻融损伤对再生混凝土耐久性及与钢筋粘结性能分析

制作掺入引气剂和未掺入引气剂的100％粗骨料取代率的再生混凝土RC1和RC2两组试件以及掺入引气剂和未掺入引气剂的普通混凝土NC1和NC2两组试件,并分别对经过不同次数冻融循环试件的抗压强度、质量损失率、动弹性模量损失率进行研究。结果表明,冻融后各组试件的抗压强度、质量损失率及动弹性模量损失率均降低,对于添加引气剂的NC1和RC1两组试件损失较小,其中RC1组试件在200次冻融后抗压强度损失接近40％,质量损失率达0．5％,动弹性模量损失率38．5％。100％取代率并加入引气剂的ZRC组试件冻融后进行中心拨出实验,发生劈裂破坏和钢筋拔出破坏2种形式。再生粗骨料混凝土与钢筋的极限粘结应力均随冻融次数的增加而降低,200次冻融后极限粘结应力下降33．5,荷载滑移曲线既有上升段也有下降段。     

双层异构网络下多用户干扰对齐算法

针对多个毫微微蜂窝网络与宏蜂窝网络共存的网络环境,基于干扰对齐技术,提出了一种双层预编码方案,首先定义宏蜂窝网络对毫微微蜂窝网络造成的干扰为跨层干扰,毫微微蜂窝网络之间的干扰为同层干扰,分别对毫微微蜂窝用户和宏蜂窝用户进行预编码,宏蜂窝用户的预编码使得跨层干扰最小,使之可比拟于背景噪声,毫微微蜂窝用户的预编码与毫微微蜂窝基站的后置编码进行迭代,以最小均方误差(MMSE)准则输出,仿真结果表明所提算法使得毫微微蜂窝网络的吞吐量相较于单层MMSE算法在信噪比为0~30 d B区间内平均提高了3 bps/Hz.     

枯草芽孢杆菌微生态制剂在禽畜养殖中的作用

枯草芽孢杆菌作为一种绿色健康的微生态制剂,具有调节动物肠道平衡、促进营养吸收、提高免疫能力等功能。微生态制剂是抗生素的理想替代品之一,因其可有效防治动物疾病,并且无毒副作用,无残留污染,不产生抗药性,还能促进动物生长发育而在禽畜养殖中广泛应用。通过综述枯草芽孢杆菌的特性、作用机理以及枯草芽孢杆菌微生态制剂在禽畜养殖中的效果,分析了目前微生态制剂存在的问题及解决措施,并展望了其未来发展方向,为后续禽畜养殖提供借鉴和参考。     

基于混合DBN的海上编队通信链路威胁估计

针对海上编队通信链路威胁估计涉及因素多、知识表示与推理存在不确定性等问题,分析了海上编队通信链路威胁要素,依据要素间因果关系建立了通信链路威胁估计的混合动态贝叶斯网络(DBN)模型,提出了混合DBN模型中连续型网络节点变量的学习方法。仿真分析证实了该方法的有效性和可操作性。     

A second generation human haplotype map of over 3.1 million SNPs

We describe the Phase II HapMap, which characterizes over 3.1 million human single nucleotide polymorphisms (SNPs) genotyped in 270 individuals from four geographically diverse populations and includes 25-35% of common SNP variation in the populations surveyed. The map is estimated to capture untyped common variation with an average maximum r2 of between 0.9 and 0.96 depending on population. We demonstrate that the current generation of commercial genome-wide genotyping products captures common Phase II SNPs with an average maximum r2 of up to 0.8 in African and up to 0.95 in non-African populations, and that potential gains in power in association studies can be obtained through imputation. These data also reveal novel aspects of the structure of linkage disequilibrium. We show that 10-30% of pairs of individuals within a population share at least one region of extended genetic identity arising from recent ancestry and that up to 1% of all common variants are untaggable, primarily because they lie within recombination hotspots. We show that recombination rates vary systematically around genes and between genes of different function. Finally, we demonstrate increased differentiation at non-synonymous, compared to synonymous, SNPs, resulting from systematic differences in the strength or efficacy of natural selection between populations.     

Genome-wide detection and characterization of positive selection in human populations

With the advent of dense maps of human genetic variation, it is now possible to detect positive natural selection across the human genome. Here we report an analysis of over 3 million polymorphisms from the International HapMap Project Phase 2 (HapMap2). We used 'long-range haplotype' methods, which were developed to identify alleles segregating in a population that have undergone recent selection, and we also developed new methods that are based on cross-population comparisons to discover alleles that have swept to near-fixation within a population. The analysis reveals more than 300 strong candidate regions. Focusing on the strongest 22 regions, we develop a heuristic for scrutinizing these regions to identify candidate targets of selection. In a complementary analysis, we identify 26 non-synonymous, coding, single nucleotide polymorphisms showing regional evidence of positive selection. Examination of these candidates highlights three cases in which two genes in a common biological process have apparently undergone positive selection in the same population:LARGE and DMD, both related to infection by the Lassa virus, in West Africa;SLC24A5 and SLC45A2, both involved in skin pigmentation, in Europe; and EDAR and EDA2R, both involved in development of hair follicles, in Asia.     

2.4GHz非对称缝隙波导天线设计

无线网络技术在近年得到蓬勃发展,而目前无线设备的天线限制了无线通信系统的性能.针对现有无线局域网设备天线增益效果差、传输距离短、成本较高的不足,采用波导缝隙天线原理设计用于2.4 GHz的无线网络通信的非对称波导缝隙天线,为适应不同场合使用要求,设计了6种造型.在理论设计的基础上,采用常见铝合金材料,使用数控铣床加工出试验品,经反复试验和优化,制作出较为成熟的产品.在校园内架设试验网络测试表明:天线增益效果明显,信号传输距离和范围与现有产品比较有很大提升,稳定性好,抵抗恶劣环境能力较强,能够满足正常使用要求,材料成本低廉,便于生产加工.     

椎弓根钉系统复位固定椎间融合治疗11例多节段腰椎滑脱

目的:探讨椎弓根钉系统复位固定椎间植骨融合治疗多节段腰椎滑脱的临床价值和相关问题。方法:11例多节段腰椎滑脱患者,男6例,女5例,年龄43~58岁,平均52.5岁,均为L4、5椎体滑脱,采用后路椎弓根螺钉系统复位固定,椎管减压,神经根松解,椎间植骨融合手术。术前、术后行腰腿痛视觉模拟评分(VAS),使用Os-westry功能障碍指数(OD I)问卷调查表评价临床功能恢复情况,并通过影像学检查观察滑脱恢复情况、椎间孔高度、植骨融合情况综合评价临床疗效。结果:11例患者均获随访,随访时间1~5年,平均3年2个月,VAS评分术后(1.0±1.0)分及末次随访(1.0±0.5)分,较术前(8.0±1.5)分均有显著性差异(P<0.005);OD I术后(22.13±13.40)及末次随访(20.31±13.27),较术前(64.80±15.68)均有显著差异(P<0.005)。术后椎间隙、椎间孔高度术后较术前明显增高,无内固定松动或断钉断棒;所有病例复位满意,所有患者植骨融合良好,无假关节形成。结论:后路椎弓根钉系统复位固定,椎管减压,神经根松解,椎间植骨融合治疗多节段腰椎滑脱效果满意,该术式具有复位良好,固定牢靠,...     

基于PSO-RBF神经网络模型的原水水质评价方法及应用

针对自来水生产过程的原水水质评价问题,提出了一种基于PSO-RBF神经网络模型的原水水质评价方法.首先,根据水厂生产经验和历史数据分析,制定面向自来水生产过程的原水水质评价标准.然后,采用粒子群优化(PSO)算法训练的RBF神经网络模型,对苏州市相城水厂的进厂原水水质实施在线评价.最后,将进厂原水水质在线评价结果作为前...     

采用BP神经网络的基波高精度检测方法

提出一种基于BP(Back Propagation)神经网络的电网基波频率和幅值的高精度检测方法。正弦信号过零点两侧对称两点连线与时间轴的交点和频率满足单调关系,但并非严格的线性关系,而且与幅值无关,据此用BP神经网络建立该交点与频率的映射关系,并提出了对称点优化选取方法。仿真表明,提出的算法对频率的检测精度达到10-4,幅值的检测精度高达10-5,远远高于普通傅里叶变换(Fast Fourier Transfromation, FFT)算法和FFT加Hanning窗算法;随机噪声和谐波对该方法测量精度的影响很小,具有较强的抗干扰能力。