基于无速度传感器的直接转矩控制系统优化

针对传统异步电机直接转矩控制系统在低速运行状态下存在磁链轨迹发生波动、转矩脉动大的问题,提出一种新型异步电机直接转矩控制策略。采用滑模控制和空间矢量脉宽调制技术(SVPWM: Space Voltage Pwlse-Width Modulation), 引入滑模控制器, 以提高系统对参数变化和外界干扰的鲁棒性。利用空间电压矢量脉宽调制技术产生系统所需要的任意期望空间电压矢量, 使磁链轨迹更趋近于圆形, 即降低了转矩和磁链脉动,又增强了系统的鲁棒性。同时引入无速度传感器技术, 以提高系统工程应用性。通过在Matlab/ Simulink软件仿真结果表明, 新型直接转矩控制系统改善了磁链轨迹波动并有效地降低了转矩脉动, 使转速估计具有较高精度。     

人工蜂群算法及其应用

为促进人工蜂群算法理论和应用的发展, 在分析人工蜂群算法的基本原理基础上, 针对算法的不足, 全面地归纳了国内外学者对算法的改进研究, 对算法的蜜源初始化、更新策略的改进、调整策略的改进、适应度函数的选择以及与其他算法的融合进行综述, 提出了更有效的改进策略。同时从多方面综述了人工蜂群算法的应用, 并对人工蜂群算法的发展方向进行了总结和展望。     

MTMR14基因缺失促进小鼠成肌细胞增殖和分化

为研究磷酸肌醇磷酸酶肌管相关蛋白14(MTMR14)在骨骼肌发生中的作用,通过组织切片和细胞培养技术研究了MTMR14敲除对骨骼肌的组织结构、成肌细胞分化和增殖的影响.结果表明:MTMR14敲除小鼠的腓肠肌和比目鱼肌的结构较同窝野生型小鼠产生了明显变化,MTMR14敲除小鼠的成肌细胞的分化和增殖成肌小管过程较野生型显著加快.MTMR14基因敲除后小鼠肌管细胞中平均细胞核数显著增加.故MTMR14基因缺失/敲除导致骨骼肌组织结构异常,干扰了骨骼肌肌肉发生过程中的成肌细胞的增殖和分化.     

触摸式远程控制终端设计

设计的触摸式远程控制终端由主控制端和从控制端2部分所组成,硬件结构包括STM32处理器、TFT触摸屏、CAN总线、n RF24L01模块、串口通信模块和电源模块。利用Keil MDK-ARM 5实现终端软件的开发,CAN总线通信网络进行数据通讯,n RF24L01无线通讯进行指令传输。实验结果表明,触摸式远程控制终端能够可靠传输数据,快速响应远程操作。     

Small molecule activators of SIRT1 as therapeutics for the treatment of type 2 diabetes

Calorie restriction extends lifespan and produces a metabolic profile desirable for treating diseases of ageing such as type 2 diabetes. SIRT1, an NAD+-dependent deacetylase, is a principal modulator of pathways downstream of calorie restriction that produce beneficial effects on glucose homeostasis and insulin sensitivity. Resveratrol, a polyphenolic SIRT1 activator, mimics the anti-ageing effects of calorie restriction in lower organisms and in mice fed a high-fat diet ameliorates insulin resistance, increases mitochondrial content, and prolongs survival. Here we describe the identification and characterization of small molecule activators of SIRT1 that are structurally unrelated to, and 1,000-fold more potent than, resveratrol. These compounds bind to the SIRT1 enzyme-peptide substrate complex at an allosteric site amino-terminal to the catalytic domain and lower the Michaelis constant for acetylated substrates. In diet-induced obese and genetically obese mice, these compounds improve insulin sensitivity, lower plasma glucose, and increase mitochondrial capacity. In Zucker fa/fa rats, hyperinsulinaemic-euglycaemic clamp studies demonstrate that SIRT1 activators improve whole-body glucose homeostasis and insulin sensitivity in adipose tissue, skeletal muscle and liver. Thus, SIRT1 activation is a promising new therapeutic approach for treating diseases of ageing such as type 2 diabetes.     

Structural definition of a conserved neutralization epitope on HIV-1 gp120

The remarkable diversity, glycosylation and conformational flexibility of the human immunodeficiency virus type 1 (HIV-1) envelope (Env), including substantial rearrangement of the gp120 glycoprotein upon binding the CD4 receptor, allow it to evade antibody-mediated neutralization. Despite this complexity, the HIV-1 Env must retain conserved determinants that mediate CD4 binding. To evaluate how these determinants might provide opportunities for antibody recognition, we created variants of gp120 stabilized in the CD4-bound state, assessed binding of CD4 and of receptor-binding-site antibodies, and determined the structure at 2.3 A resolution of the broadly neutralizing antibody b12 in complex with gp120. b12 binds to a conformationally invariant surface that overlaps a distinct subset of the CD4-binding site. This surface is involved in the metastable attachment of CD4, before the gp120 rearrangement required for stable engagement. A site of vulnerability, related to a functional requirement for efficient association with CD4, can therefore be targeted by antibody to neutralize HIV-1.     

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.