非均匀介质谐振器的谐振频率分析与FDTD方法

为了揭示非均匀介质谐振器的谐振频率与非均匀介质的特性之间的关系,首先基于Matlab编码,应用时域有限差分法(FDTD),对一个均匀介质的谐振器进行了模型分析和结果仿真,与实测结果对比,仿真结果显示了FDTD方法的有效性。然后建立一个具有横向平面分层式结构的非均匀介质谐振器模型,通过调节各层介质不同的厚度比例,发现可以用两种固定的介电常数相异的介质来获取所期望的谐振频率。这个分析和模拟结果有助于设计模型简单、尺寸规格相近但谐振频率各异的介质谐振器。     

Analysis of a 26 756 bp segment from the left arm of yeast chromosome IV

The nucleotide sequence of a 26·7 kb DNA segment from the left arm of Saccharomyces cerevisiae chromosome IV is presented. An analysis of this segment revealed 11 open reading frames (ORFs) longer than 300 bp and one split gene. These ORFs include the genes encoding the large subunit of RNA polymerase II, the biotin apo-protein ligase, an ADP-ribosylation factor (ARF 2), the ‘L35’-ribosomal protein, a rho GDP dissociation factor, and the sequence encoding the protein phosphatase 2A. Further sequence analysis revealed a short ORF encoding the ribosomal protein YL41B, an intron in a 5′ untranslated region and an extended homology with another cosmid (X83276) located on the same chromosome. The potential biological relevance of these findings is discussed. The sequence was submitted to the EMBL database under Accession Number X96876.     

Quality measure of color images based on properties ofvision psychology and color distortion in MPEG-21

In this article, a new way to evaluate the quality of color images is proposed, in which the properties of human vision psychology, objective fidelity, edge information, and color distortion will be combined through utilizing 3-D matrix transform. There exists color redundancy and structural similarity between three different frames of a color image, the definition of vision properties will be measured by 3-D submatrix integration transform (SIT), in which three color components are integrated into one model and color redundancy can be exploited fully. The simulation results show that the measure index is very effective and objective in accord with vision properties.     

Delay-dependent H∞ filtering for discrete-time singular Markovian jump systems with time-varying delay and partially unknown transition probabilities

This paper is concerned with the H_∞ filtering design for a class of discrete-time singular Markovian jump systems with time-varying delay and partially unknown transition probabilities. The class of systems under consideration is more general and covers the singular Markovian delay systems with completely known and completely unknown transition probabilities as two special cases. A mode-dependent filter is constructed and by defining an appropriate stochastic Lyapunov functional combined with using the discrete Jensen inequality, a delay-dependent bounded real lemma (BRL) for the considered systems is established in terms of linear matrix inequalities (LMIs). Based on this, a sufficient condition on the existence of the desired filter which guarantees the admissibility and the H_∞ performance of the corresponding filtering error system is presented by employing the LMIs technique. Some numerical examples are provided to illustrate the effectiveness of the developed theoretical results.     

miR-21的高表达与乳腺癌预后关系的meta分析

目的：评价miR-21的高表达与乳腺癌预后的相关性。方法：检索PubMed,MEDLINE,EMBASE,Webofscience,维普,CNKI数据库,收集从建库至2013年9月期间关于miR-21的高表达与乳腺癌预后相关性的文献,用meta分析方法评价miR-21的高表达是否与乳腺癌的预后相关。结果：共纳入4篇文献（总计548个病例）,总生存率（OS）HR的合并值为1．61（95％CI：1．09至2．37,P〈0．05）。结论：miR-21的高表达是乳腺癌预后的一个危险因素。     

miR-21的高表达在结直肠癌预后中的meta分析

目的:评价miR-21的高表达与结直肠癌预后的相关性.方法:通过全面检索PubMed、EMBASE、Google scholar、维普、CNKI等数据库,收集关于miR-21的高表达与结直肠癌预后相关性的文献,用meta分析方法评价miR-21的高表达是否与结直肠癌的预后相关.结果:共纳入4篇文献(共783个病例),总生存率(OS)HR的合并值为1.42,95％CI:1.21至1.66,P＜0.05.结论:miR-21的高表达是结直肠癌预后的一个危险因素.     

基于ATMEGAB的高精度超声波测距仪设计

针对普通超声波测距系统测量精度低的问题,介绍了一种由ATMEGA8单片机控制的实时超声波测距系统．电路主要采用专用时间测量芯片TDC—GP21,并考虑了温度补偿,有效地保证了系统测量精度和低功耗特性。     

TC4-DT及TC21钛合金疲劳裂纹扩展速率的对比分析

为进一步研究航空主承力疲劳结构件损伤容限型钛合金的疲劳裂纹扩展问题,基于新版标准疲劳裂纹扩展试验方法GB/T 6398—2017,对两类损伤容限型钛合金TC4-DT及TC21进行测试。结果表明,低速扩展阶段,TC4-DT较TC21的疲劳裂纹扩展速率更小,宏观断口形貌粗糙度较大。当裂纹尖端应力强度因子范围ΔK处于24～31 MPa·m1/2的初始稳态扩展阶段时,裂纹扩展速率曲线基本重合,TC4-DT较TC21具有更长的稳态扩展区,断口形貌较为平滑。随裂纹长度的增加,应力强度因子范围ΔK约为断裂韧度KIC的50%时,进入失稳扩展阶段,断裂面粗糙度增加。     

一种高性能的桥式驱动电路

介绍了一种IGBT驱动电路SKHI21,它具有对驱动电源的欠压监测的功能;原副边采用脉冲变压器隔离,可以驱动半桥的上下管两个IGBT,而且只需一路直流电源就能工作;另外它可以输出短路进行保护护及软件关断IGBT,有效地保护IGBT;分析了它的内部框图和使用方法,实验证明,该驱动电路使用简单、可靠,具有优良的驱动和保护性能。     

Characteristics and favorable area prediction of Ordovician buried-hill carbonate reservoirs in the Bozhong 21–2 tectonic belt,Bohai Bay Basin,China

Based on core data, thin section and logging, this study investigates the basic characteristics and occurrence regularities of the Ordovician buried-hill carbonate reservoir in the Bozhong 21-2 tectonic belt. Results show that the reservoir lithology is primarily limestone, followed by dolomite, dolomitic limestone or limey dolomite, and silty mudstone. The reservoir spaces are primarily composed of secondary porosity. These reservoirs can be divided vertically into weathered-crust karst reservoirs and inner dissolution-type reservoirs. The distribution of reservoirs is controlled chiefly by karstification. The high karst units in the study area are favorable for the development of the two reservoir types.