oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2019 ( 122 )

2018 ( 2506 )

2017 ( 2614 )

2016 ( 2784 )

Custom range...

Search Results: 1 - 10 of 129482 matches for " 余永建 "
All listed articles are free for downloading (OA Articles)
Page 1 /129482
Display every page Item
基于笔段特征和HMM的在线签名认证方法研究*
孟明,吴仲城,,葛运
模式识别与人工智能 , 2007,
Abstract: 手写签名过程中的书写力包含丰富个人特征.受输入设备所限,目前的在线手写签名认证系统都没有能够充分利用这一信息.基于此,本文提出一种综合利用签名字形和书写力特征的在线签名认证方法.首先,利用一种新型的FTablet手写板用于获取签名的动态笔迹和书写力信息,并根据速度极小值点对签名进行笔画分段.然后从中提取16维的字形和书写力特征矢量序列用于签名隐马尔可夫模型(HMM)的建立和认证.在基于FTablet手写板建立的签名数据库上的认证实验结果表明书写力特征比字形特征更难以模仿,两种特征相结合可以有效提高系统的识别性能,提出的认证方法的相等错误率(EER)达到3.9%.
加锚多组有序裂隙类岩体单轴破断试验分析
王平,冯涛,,伟健
岩石工程学报 , 2015,
Abstract: 为研究锚杆对多组有序裂隙岩体的作用机制,以水泥砂浆预制多组有序裂隙类岩体,采用玻璃纤维塑料筋材(gfrp)模拟锚杆,对预制的类岩体进行全长锚固,制作多组不同锚固条件下的试件。将预制试件在rmt-150伺服试验机进行单轴压缩破断试验。根据试验结果提出了主控裂纹的概念,认为主控裂纹的贯通导致了试件强度的弱化。分别从细观上研究了锚杆对多组有序裂隙类岩体主控裂纹的起裂、扩展和贯通影响机制;从宏观上研究锚杆对多组有序裂隙岩体峰值强度、残余强度以及抗变形能力的影响。研究发现:锚杆锚固后多组有序裂隙类岩体主控裂纹由纵向—倾斜—横向贯通为主的扩展、贯通模式转变为横向—纵向—倾斜的模式,主控裂纹路径更长且贯通过程受到锚杆锚固限制,具体表现为锚杆锚固改变了裂纹尖端的应力强度因子使得类岩体试件抗变形能力更大、试件的峰值强度和残余强度更高。但并非加锚密度越大,类岩体强度越高,适当的加锚密度才能获得更好的支护效果。
单离子束技术概述
詹福如,许明亮,,增亮
强激光与粒子束 , 2007,
Abstract: ?对单离子束的发展和应用作了介绍。结合我国首台单离子束装置cas-libb,综合讨论了准直器限流型和静电透镜聚焦型两种典型单离子束的技术结构。限流型结构简单但定位精度有限,聚焦型条件苛刻但可获得亚微米束,是单离子束发展的趋势。评估了前探测、全前置探测和后探测3种单离子束探测方式及其特点,研究了这3种探测方式对辐照离子的计数精度和单离子束品质产生的影响。对cas-libb装置研制了光导型全前置探测器以提高计数精度和束流品质。最后设计了快速荧光在线检测技术方案。
小新月菱形藻碳酸酐酶活性和光合作用对高盐度胁迫的响应
锦兰?,荣?,东?
水产学报 , 2011, DOI: 10.3724/SP.J.1231
Abstract: 以浮游硅藻小新月菱形藻为实验材料,研究其在不同盐度下的生长、胞外碳酸酐酶活性、光合速率和叶绿素a荧光参数的变化。结果显示,与正常海水培养相比,最高盐度(70)培养的细胞比生长速率下降了59.2%;同时,胞外碳酸酐酶活性、叶绿素a、c含量分别降低了66.3%、50.0%和45.7%。高盐度培养下,最大光合速率(pm)、光合效率(α)、最大光化学效率(fv/fm)、实际光化学效率(yield)和光化学淬灭系数(qp)下降,但非光化学淬灭系数(qn)升高,对无机碳的亲和力明显下降。以上结果表明,盐度升高对小新月菱形藻生长和光合作用具有明显抑制作用,但小新月菱形藻可以通过胞外碳酸酐酶活性变化、对无机碳的亲和力和调整光系统ⅱ的能量流动与能量利用效率以应对高盐度的胁迫。
食醋总酸和还原糖含量近红外光谱检测模型的优化研究
郝 勇?,,朱胜虎?
西北农林科技大学学报(自然科学版) , 2013,
Abstract: 【目的】采用近红外光谱(near-infraredspectroscopy,nirs)分析技术对食醋中的总酸和还原糖进行快速定量分析,为食醋品质的检测提供技术支持。【方法】用近红外透射光谱法采集食醋的光谱信息,用savitzky-golay一阶导数和小波导数(waveletderivative,wd)对采集到的食醋光谱进行预处理,采用连续投影算法(successiveprojectionsalgorithm,spa)的波长筛选方法对食醋的总酸以及还原糖定量分析模型进行优化。【结果】食醋光谱经小波导数预处理和基于spa的波长优选后,总酸和还原糖含量分析精度得以提高,模型得到简化。总酸的预测均方根误差(rootmeansquareerrorofprediction,rmsep)由0.282降低为0.227,预测相关系数(correlationcoefficientofprediction,rp)由0.965提高到0.977,建模变量由680个精简为51个;还原糖的rmsep由0.627降低为0.606,预测相关系数rp由0.996提高至0.997,建模变量精简为50个。【结论】利用近红外光谱分析技术结合小波导数和spa分析方法,可用于食醋品质的定量分析,为食醋品质的快速检测提供了一种可行的方法。
无线传感器网络节点行为度量方案
Behavior measurement scheme for the wireless sensor network nodes

周彩秋,,
- , 2017, DOI: 10.16511/j.cnki.qhdxxb.2017.21.008
Abstract: 随着电子信息技术的发展,无线传感器网络得到了日益广泛的应用,传统安全防护技术却无法直接应用于无线传感网中,传感器节点容易遭受到恶意攻击。该文提出了一种无线传感器网络的节点行为度量机制,对不同计算能力的节点采用不同的度量机制,具有实时度量和主动控制的特点。仿真实验表明,该方案充分考虑了无线传感器节点能耗问题,能够有效识别恶意节点,同时有更好的环境适应性,能够在部分节点遭到攻击时保障传感器网络顺畅运行。
Abstract:The development of electronic information systems has led to many more wireless sensor networks. However, traditional security systems cannot be directly applied to wireless sensor networks, so the sensor nodes are vulnerable to malicious attacks. This paper presents a node behavior measurement mechanism for wireless sensor networks using different metric mechanisms for different computing nodes with real-time measurements and active control features. Simulations show that this method monitors the energy consumption of the wireless sensor nodes to identify malicious nodes while better adaptability to the environment to make the sensor network run smoothly when some nodes attack.
基于脉冲激光定位的SRAM单粒子闩锁事件率预估
SEL rate prediction for SRAM using pulsed laser sensitivity mapping

,,封国强,蔡明辉
- , 2015, DOI: 10.13700/j.bh.1001-5965.2014.0301
Abstract: 摘要 器件单粒子闩锁效应(SEL)预估方法一般是建立在只有一个敏感体积单元的长方体(RPP)模型上,静态随机存储器(SRAM)单粒子闩锁敏感区的定位试验结果表明敏感体积单元不仅有一个.利用脉冲激光定位SRAM K6R4016V1D单粒子闩锁效应敏感区的试验结果对器件在轨SEL事件率进行了修正计算.首先利用脉冲激光定位SRAM SEL敏感区,获得敏感区的分布情况,并确定整个器件敏感体积单元的数量.然后针对不同的空间轨道、辐射粒子以及敏感体积厚度和敏感体积单元数进行了相应的器件SEL事件率计算,并对计算结果进行了分析讨论.结果表明,重离子引起的SEL事件率随敏感体积单元数量的增大而减小;修正敏感体积单元数量对预估质子引起的SEL事件率非常必要,否则将会过高评估质子直接电离作用对SEL事件率的贡献.
Abstract: The classical approaches for single event latchup (SEL) rate prediction are based on the rectangular parallelepiped (RPP) model of only one sensitive volume. However, the experiment results of SEL sensitivity mapping of static random access memory (SRAM) show that the device has not only one sensitive volume (SV). The in-flight SEL rate of the device was corrected using the experiment results of pulsed laser SEL sensitivity mapping of SRAM K6R4016V1D.The SEL sensitivity maps of the SRAM by pulsed laser were first obtained and then the SV number of the device was calculated. The SEL rates of the device were predicted and discussed for different space orbits, radiation particles, SV thicknesses and SV number in particular. The results show that SEL rate caused by heavy ion decreases with SV number. The correction of the SV number is essential for SEL rate due to proton direct ionization; otherwise, the contribution of direct ionization of protons to SEL rate would be greatly overestimated.
?深水海底管道全尺寸压溃试验及数值模拟
,卞雪航,,杨源,
天津大学学报(自然科学与工程技术版) , 2012,
Abstract: ?针对深水海底管道压溃问题,研制了深水海底管道屈曲试验装置,该装置可承受水压43,mpa,全长11.5m,直径1.6,m.使用该装置设计并开展了全尺寸管道压溃试验.利用ansys软件建立三维圆柱壳模型进行管道压溃数值模拟分析,并将试验结果与数值模拟结果进行对比,来研究径厚比、初始凹坑缺陷、初始椭圆度缺陷等因素对管道压溃的影响.结果表明,管道压溃载荷随着径厚比的增大而显著降低,单个点状凹坑缺陷对于管道压溃载荷影响较小,初始椭圆度缺陷则明显降低了管道的压溃载荷.
蛤蜊酱的发酵工艺及其鲜味物质分析
周敏,,,,李崎
- , 2016, DOI: 10.3969/j.issn.1673-1689.2016.11.012
Abstract: 为综合利用我国蛤蜊资源,研究蛤蜊酱的发酵生产。以米曲霉为发酵微生物,比较了不同原料制曲和不同发酵工艺对蛤蜊酱中氨基氮和氨基酸含量的影响,结果显示:以麦麸制曲和发酵初期加入蛤蜊的工艺最佳,其总氨基氮质量分数最高,为1.25 g/hg;其谷氨酸为1.2 g/hg;呈味核苷酸为209.54 mg/hg。发酵结束后蛤蜊酱鲜味突出,其中5'-GMP的呈味强度值为8.460,说明发酵过程中产生的5'-GMP对蛤蜊酱鲜味有重要贡献。
The fermentation of clam sauce was studied to development of clam resource utilization. The contents of amino nitrogen and amino acid were investigated based on the different raw materials and fermentation technologies,in which Aspergillus oryzae was used as the fermentation microorganism. The optimization of fermentation condition was achieved by koji made from wheat bran and clam added in the initial stage. The total content of amino nitrogen was as high as 1.25 g/100 g with 1.2 g/100 g of glutamic acid and 209.54 mg/100 g of flavor nucleotide. A characteristic flavor of clam sauce was significantly exhibited with the 5'-GMP intensity of 8.460. The contribution of 5'-GMP to umami flavor of clam sauce during fermentation was confirmed
Measurement and analysis of thermal properties of SiNx thin films
SiNx薄膜热物性参数实验测量与分析研究

Yu Lei,Yu Jian-Zu,Wang Yong-Kun,
 雷
,,

物理学报 , 2004,
Abstract: The thermal conductivity, emissivity, specific heat capacity and thermal diffusivity of SiNx thin films which are widely used in semiconductor and microelectronics MEMS are measured using a novel experimental method which combines the heater and the bolometer in one unit. The obtained reliable thermal properties are very useful for microelectronic circuits design and mask processing. The experimental data show that the thermal conductivity, emissivity and thermal diffusivity of SiNx thin films are much lower than those of the bulk and depend on the temperature and thickness of the thin films, and the size effect of SiNx thin films is notable. However, the specific heat capacity of SiNx thin films is almost the same as that of the bulk.
Page 1 /129482
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.