卫星多体制测控地面测试系统设计

随着航天技术的不断发展,卫星功能日趋复杂,对卫星测控分系统的功能提出更高的需求,要求同时支持对地非相干扩频测控、中继测控、扩跳频测控及测量数传测控体制,对卫星测控系统地面测试平台多体制支持、通用化及自动化测试能力、可靠性提出了更高要求;本文研究了卫星多体制测控地面测试平台系统设计方法,采用了多通道测控地检通道复用、基于数据库的通用化配置及自动化测试技术,应用于某遥感卫星的地面测试,测试结果表明：该平台运行稳定,取得了良好的使用效果,满足了卫星多体制测控地面测试需求;     

基于 GST-TT 变换的单端故障行波测距方法

针对行波法测距波头时刻标定精度不足和波速不稳定的问题,提出一种基于GST-TT变换的单端故障行波测距方法。首先将采样的电压行波信号做解耦处理,提取线模电压信号,然后将线模电压信号进行广义S变换,提取适当高频频带作为故障特征频带,运用TT变换对角线位置元素聚高频、抑制低频的特性,在故障特征频带内对波头到达测量端时刻进行精确标定,根据不依赖具体行波波速的故障测距计算方法得出故障距离。该方法可以提高波头时刻的标定精度,降低波速不稳定对故障测距的影响。通过PSCAD仿真验证,根据结果可知,该方法测距精度较高,在无噪声干扰情况下,平均相对误差为0.25%;同时也可知晓该方法具有较强的耐受过渡电阻能力和抗噪能力。     

Relevance of Plasma Homocysteine and Methylenetetrahydrofolate Reductase 677TT Genotype in Sickle Cell Disease: A Systematic Review and Meta-Analysis

We evaluated the relevance of plasma homocysteine (HC) and the TT genotype of the methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism (rs1801133) in sickle cell disease (SCD) and associated vaso-occlusive crisis (VOC) and ischemic stroke (IS). We identified in Embase and Medline 22 studies on plasma HC and 22 on MTHFR genotypes. Due to age-related HC differences, adult and paediatric SCD were separated: 879 adult SCD and 834 controls (CTR) yielded a neutral effect size; 427 paediatric SCD and 625 CTR favoured SCD (p = 0.001) with wide heterogeneity (I² = 95.5%) and were sub-grouped by country: six studies (Dutch Antilles n = 1, USA n = 5) yielded a neutral effect size, four (India n = 1, Arab countries n = 3) favoured SCD (p < 0.0001). Moreover, 249 SCD in VOC and 419 out of VOC yielded a neutral effect size. The pooled prevalence of the MTHFR TT genotype in 267 SCD equalled that of 1199 CTR (4.26% vs. 2.86%, p = 0.45), and in 84 SCD with IS equalled that of 86 without IS (5.9% vs. 3.7%, p = 0.47); removal of one paediatric study yielded a significant effect size (p = 0.006). Plasma HC in paediatric SCD from Middle East and India was higher, possibly due to vitamin deficiencies. Despite its low prevalence in SCD, the MTHFR TT genotype relates to adult IS.     

The Role of E3 Ubiquitin Ligases in Chloroplast Function

Chloroplasts are ancient organelles responsible for photosynthesis and various biosynthetic functions essential to most life on Earth. Many of these functions require tightly controlled regulatory processes to maintain homeostasis at the protein level. One such regulatory mechanism is the ubiquitin-proteasome system whose fundamental role is increasingly emerging in chloroplasts. In particular, the role of E3 ubiquitin ligases as determinants in the ubiquitination and degradation of specific intra-chloroplast proteins. Here, we highlight recent advances in understanding the roles of plant E3 ubiquitin ligases SP1, COP1, PUB4, CHIP, and TT3.1 as well as the ubiquitin-dependent segregase CDC48 in chloroplast function.     

~3H_e和~4H_e及其混合气体输运性质的理论研究

本文应用TT势计算了~3He和~4He气温体在0.1K—3273K温度范围内的粘滞系数和热传导系数,以及~3He和~4He气体等摩尔二元混合在0.1—373K内的输运性质,计算结果与Kestin等人的数据符合得很好。计算中用了经典和量子力学两种输运截面公式,T=373K时两种计算得出的输运系数,其相对偏差在0.7％左右,随温度降低偏差逐渐增大。     

S频段统一测控雷达健康故障诊断系统的设计

针对S频段统一测控系统故障诊断及健康管理的需求,给出故障诊断软件体系架构,并基于故障树的设备故障诊断开展了LNA+D/C设备状态评估设计。健康故障诊断系统以可更换单元或模块的监测信息为基础,综合利用自动测试和标校结果,收集、存储、诊断全系统设备工作状态,并依据建立的系统健康诊断和任务能力预测模型,实现设备健康状态预测和任务能力评估功能,为资源调度提供决策依据。     

甲型副伤寒多糖-破伤风类毒素结合疫苗的制备及安全性和免疫原性

目的制备甲型副伤寒多糖-破伤风类毒素结合疫苗,并检测其安全性与免疫原性。方法副甲O-SP溶液加入CDAP活化,己二酰肼(ADH)衍化,在碳二亚胺(EDAC)作用下与破伤风类毒素(TT)偶联,反应物经柱层析纯化,制得多糖蛋白结合物,经质量检测后,进行安全性及免疫原性试验。结果所制备的结合物多糖蛋白比稳定在0.6~0.8之间,CL-4B检测Kd≤0.2时的回收率大于75%,高相对分子质量结合物含量不低于90%。免疫双扩散试验显示结合物与副甲家兔超免血清和TT抗血清均产生可见沉淀线。动物安全试验均合格。结合物免疫小鼠后,其血清副甲LPS抗体滴度显著增长,阳转率达到100%。结论用CDAP活化多糖制备的甲型副伤寒-破伤风类毒素结合疫苗质量稳定,安全可靠,且具有良好的免疫原性。     

A study on wear coefficients and mechanisms of steam generator tube materials

Reciprocating sliding wear tests were performed to evaluate wear properties of Inconel 600MA and 690TT steam generator (SG) tube materials against 405 and 409 ferritic stainless steels. With increasing normal loads and sliding amplitudes, the wear rate of tube materials increased but a wear transition occurred only in Inconel 690TT. Subsurface deformation strengthening seemed to be an important factor that determines the wear resistance of tube materials. After the wear test, the worn surfaces were observed to investigate the wear mechanism of tube materials using SEM. The results indicated that there are different mechanisms of wear particle removal between the tube materials. The differences are related to the degree of work hardening due to the differences in chromium content in the tube materials. Based on the present results, wear coefficient values for the life estimation of SG tubes were calculated according to the work-rate model at each test condition. The wear rate is lower for Inconel 690TT compared to that for Inconel 600MA. Finally, parameters that should be considered for evaluation of wear coefficients were discussed.     

Decision‐tree‐based methods for differential diagnosis of β‐thalassemia trait from iron deficiency anemia

Several discrimination indices have been proposed to distinct between β‐thalassemia trait (βTT) and iron deficiency anemia (IDA). This study is the first application of tree‐based methods for differential diagnosis of βTT from IDA. One hundred forty‐four patients with hypochromic microcytic anemia aged 18–40 years old from Ayat Hospital of Tehran were recruited. Classification and Regression tree, CHi‐squared Automatic Interaction Detector (CHAID), Exhaustive CHi‐squared Automatic Interaction Detector (E‐CHAID), Quick, Unbiased, Efficient Statistical Tree (QUEST), Classification Rule with Unbiased Interaction Selection and Estimation (CRUISE), and Generalized, Unbiased, Interaction Detection and Estimation (GUIDE) have been used to discriminate the diagnosis. Mean corpuscular volume (MCV) was found as the main predictor in discrimination. All the mentioned tree‐based methods showed acceptable sensitivity, specificity, accuracy, Youden's index, false positive and negative rate, positive and negative predictive values and AUC in differential diagnosis of βTT from IDA. However, Classification Rule with Unbiased Interaction Selection and Estimation revealed more precise classification with an area under the curve value of 0.99. Decision‐tree‐based methods can be used to develop sensitive and accurate diagnostic methods for differentiating βTT from IDA.