杀虫剂现状及发展前景

本文了杀虫剂的四个时代及其现状。在分析评价其发展历史及历史发展需要的基础地新一代杀虫剂发展的途径及展望。     

Effect of frequency on fatigue lifetime of extruded Mg-3%Al-1%Zn alloy

Samples prepared from as-extruded magnesium alloy Mg-3%Al-1%Zn (AZ31) billets were utilized in low-cycle fatigue tests in order to investigate the frequency-dependent fatigue life. Fully reversed strain-controlled tension-compression fatigue tests were carried out at frequencies of 1 Hz and 10 Hz in air. The microstructures were examined by optical microscopy (OM) and scanning electron microscopy (SEM).When the strain amplitude was lower than 0.2%, the fatigue life exhibited a positive correlation with loading frequency, and the activity of twinning was increased at 10 Hz. When the strain amplitude was higher than 0.2%, significant twinning was observed both at these two frequencies, and the fatigue life was found to be independent of frequency. The possible reasons for this frequency-related fatigue lifetime may be due to the dependence of twinning upon loading frequency and strain amplitude.     

An Efficient Algorithm for Haplotype Inference on?Pedigrees with a Small Number of Recombinants

Combinatorial (or rule-based) methods for inferring haplotypes from genotypes on a pedigree have been studied extensively in the recent literature. These methods generally try to reconstruct the haplotypes of each individual so that the total number of recombinants is minimized in the pedigree. The problem is NP-hard, although it is known that the number of recombinants in a practical dataset is usually very small. In this paper, we consider the question of how to efficiently infer haplotypes on a large pedigree when the number of recombinants is bounded by a small constant, i.e. the so called k-recombinant haplotype configuration (k-RHC) problem. We introduce a simple probabilistic model for k-RHC where the prior haplotype probability of a founder and the haplotype transmission probability from a parent to a child are all assumed to follow the uniform distribution and k random recombination events are assumed to have taken place uniformly and independently in the pedigree. We present an O(mnlog? ^k+1 n) time algorithm for k-RHC on tree pedigrees without mating loops, where m is the number of loci and n is the size of the input pedigree, and prove that when 90log?n<m<n ³, the algorithm can correctly find a feasible haplotype configuration that obeys the Mendelian law of inheritance and requires no more than k recombinants with probability $1 -O(k^{2}\frac{\log^{2}n}{mn}+\frac{1}{n^{2}})$ . The algorithm is efficient when k is of a moderate value and could thus be used to infer haplotypes from genotypes on large tree pedigrees efficiently in practice. We have implemented the algorithm as a C++ program named Tree-k-RHC. The implementation incorporates several ideas for dealing with missing data and data with a large number of recombinants effectively. Our experimental results on both simulated and real datasets show that Tree-k-RHC can reconstruct haplotypes with a high accuracy and is much faster than the best combinatorial method in the literature.     

高密度电法在大幕山水库渗漏隐患探测中的应用

针对传统土石坝渗漏安全隐患探测方法的不足,采用高密度电法对通山大幕山水库土石坝渗漏安全隐患进行了无损探测,以检查评价高密度电法在中小型水库土石坝渗漏安全隐患探测中的有效性和适用性。试验研究结果表明,高密度电法可以用于查明土石坝渗漏通道位置或进行疑点提示,为大坝除险加固和后续处理提供科学参考依据。     

动态3D虚拟场景并行化光线跟踪加速结构设计

为提高光线与虚拟场景几何面片求交的计算效率,提出一种基于混合模式的空间加速结构。该方法改进传统的层次包围盒,把细分层次包围盒与空间均匀网格划分相结合,实现了可并行的混合空间加速设计。此外,把帧间可重用的数据抽取至数据缓存,建立多几何群组的加速结构共享,实现了光线跟踪算法的并行优化。实验证明,该混合加速结构能有效加快光线跟踪的光线场景求交判断速度,快速实现光线跟踪并行化计算。     

合成羟基乙叉二膦酸反应机理分析

详细分析了合成羟基乙叉二膦酸的反应机理，并讨论了影响ＨＥＤＰＡ产率的主要因素，对生产实际具有一定指导作用     

Effects of Ti addition on low carbon hot strips produced by CSP process

Large quantity of fine Ti（C,N） particles, 15-30 nm in size, were observed in low carbon hot strips added to a small amount of Ti and produced by CSP process. The results showed that the precipitation of Ti（C,N） mostly took place during soaking and hot rolling, which is significantly different from that in the conventional production. These fine Ti carbonitride particles could be very effective on the austenite grain refinement by hindering grain growth of recrystallized austenite. Their precipitation behavior was discussed and compared with that of the steels produced in the conventional production.     

An investigation of the effects of mix strength on the fracture and fatigue behavior of concrete mortar

This paper examines the effects of mix compressive strength (30, 35 and 40 MPa) on the fracture initiation toughness, resistance-curve behavior and fatigue crack growth behavior of concrete mortar. The fracture initiation toughness and the resistance-curve behavior are shown to increase with increasing mix strength. The observed resistance-curve behavior is then attributed largely to the effects of ligament bridging, which are predicted using small- and large-scale bridging models. In contrast, the fatigue crack growth resistance is shown to decrease with increasing mix strength. An extended multiparameter framework was used for the modeling of fatigue crack growth. Finally, the implications of the results are discussed for the design of concrete mixtures with attractive combinations of strength, fracture toughness and fatigue crack growth resistance.     

Stable multiwavelength dispersion-tuned actively mode-locked erbium-doped fiber ring laser using nonlinear polarization rotation

We demonstrate a stable multiwavelength actively mode-locked erbium-doped fiber laser at 10 GHz based on a dispersion cavity and nonlinear polarization rotation (NPR) effect. The dispersion cavity allows simultaneous multiple wavelengths to satisfy the round-trip condition and smooth wavelength tuning, while the NPR ensures the stable operation and supermode noise suppression. A simple model is developed to explore the optimal setting of the cavity. Simultaneous dual- and five-wavelength operation is experimentally investigated.     

无线流媒体应用中的错误隐藏算法

无线流媒体应用对网络信道扰动有着较高的敏感性，错误隐藏是对网络错误所造成的丢失数据进行预测与恢复的重要方法之一。该文介绍了错误隐藏的原理及算法，并根据无线流媒体的特点提出了一种基十模式选择的错误隐藏算法，该算法充分利用视频数据时空域的相关性对受损数据进行恢复和重建，并在基于H．264标准的手机解码器中获得了较好的主观质量效果。同时，该算法有着低计算复杂度和空间消耗的特点，能够适用于手机等资源缺乏的无线流媒体应用环境。