房间采暖技术与变频调速综述

本文对房间采暖技术的发展状况、技术原理、构造特点进行了归纳总结,重点分析了地板供暖的优缺点,指出了地板供暖技术在房间采暖设计中的应用前景。针对低温地板热水辐射供暖系统存在的一些工程问题,通过对水泵的控制算法的研究和探讨,提出了地板水供暖系统采用以uPD78F1213为核心的无传感器永磁同步电机矢量控制系统的方案。     

Having a Same Type IIS Enzyme’s Restriction Site on Guide RNA Sequence Does Not Affect Golden Gate (GG) Cloning and Subsequent CRISPR/Cas Mutagenesis

Golden gate/modular cloning facilitates faster and more efficient cloning by utilizing the unique features of the type IIS restriction enzymes. However, it is known that targeted insertion of DNA fragment(s) must not include internal type IIS restriction recognition sites. In the case of cloning CRISPR constructs by using golden gate (GG) cloning, this narrows down the scope of guide RNA (gRNA) picks because the selection of a good gRNA for successful genome editing requires some obligation of fulfillment, and it is unwanted if a good gRNA candidate cannot be picked only because it has an internal type IIS restriction recognition site. In this article, we have shown that the presence of a type IIS restriction recognition site in a gRNA does not affect cloning and subsequent genome editing. After each step of GG reactions, correct insertions of gRNAs were verified by colony color and restriction digestion and were further confirmed by sequencing. Finally, the final vector containing a Cas12a nuclease and four gRNAs was used for Agrobacterium-mediated citrus cell transformation. Sequencing of PCR amplicons flanking gRNA-2 showed a substitution (C to T) mutation in transgenic plants. The knowledge derived from this study could widen the scope of GG cloning, particularly of gRNAs selection for GG-mediated cloning into CRISPR vectors.     

NVCGM高性能灌浆料的研究及应用

从流变性、竖向膨胀、有效承载接触面积、抗压强度等方面,采用对比试验的方法,系统分析了 NVCGM 灌浆料与国外两种灌浆料、国内某灌浆料的优劣性。试验结果以及工程应用表明,NVCGM 灌浆料是一种综合性能优异的高性能灌浆料。     

小口径弹药引信定距精度分析

从理论上分析了影响引信定距精度的因素,利用试验数据,对连发射击时引信定距精度变差的原因作了定性分析,对武器系统的使用提出意见和建议.     

双层辉光离子渗Ni-Cr-Mo-Cu合金的工艺

在20钢基材上,利用双层辉光离子渗金属技术进行Ni-Cr-Mo-Cu多元共渗正交实验工艺研究.结果表明,工艺参数对渗层的元素总含量以及渗层的厚度有较大的影响,并确定了最佳工艺参数为源极电压1050V,工件电压250V,气压35Pa,极间距15mm.     

基于有限样本的大气偏振模式生成方法

大气偏振模式在导航等领域具有广阔的应用前景,但是由于受到大气偏振信息采集装置物理特性的限制,在同一时刻只能获得局部的、不连续的偏振信息,对实际应用产生影响。针对此问题,本文通过挖掘大气偏振模式分布的连续性,提出一种大气偏振模式生成方法,从局部的偏振信息生成全天域的大气偏振模式。此外,偏振信息往往受到不同的天气条件、地理环境等因素的影响,而这些偏振数据在真实环境中难以采集。针对此问题,本文挖掘不同天气、地理条件下有限样本数据之间的多样性关系,以此关系将生成的大气偏振模式泛化到不同的条件下。本论文在仿真数据和实测数据上进行了实验,并与其它最新方法进行对比,实验结果证明了本文方法的优越性和鲁棒性。     

Direct Ink Writing of Highly Conductive MXene Frames for Tunable Electromagnetic Interference Shielding and Electromagnetic Wave?Induced Thermochromism

The highly integrated and miniaturized next-generation electronic products call for high-performance electromagnetic interfer?ence (EMI) shielding materials to ...     

Phase change memory alloys: GST cell array characterization using picosecond ultrasonics

Phase change random access memory alloys (PRAM or PCM) are a class of non-volatile memory that is thought as viable alternatives to flash memory technology or to supplement other memory technologies depending on the end applications and its key performance requirements. Ge₂Sb₂Te₅ alloy (GST) is the most widely used chalcogenide material for PCM application, and has many unique properties, including strong temperature-dependent film properties, low thermal conductivity, and high electrical resistivity. Picosecond ultrasonics was used to make non-contact, non-destructive measurements of GST films on blanket wafers and directly on product wafers. On-product wafer measurements were made on various via array (0.5 μm and 1 μm between cell edges with CD size from 250 to 800 nm). Measurements have shown excellent correlation to cross-section SEM and were consistent with CMP polish times for both blanket and pattern wafer measurement. Excellent repeatability based on extensive measurements demonstrates the capability and reliability of picosecond ultrasonic technology. Picosecond ultrasonic measurements also provide rapid characterization across the whole wafer at production-worthy throughputs.     

美国联邦检察官的地方反腐行动之正当性辨析

美国司法部在未获得国会立法明确授权的情况下,自上世纪70年代初始启动了由联邦检察官直接参与调查和检控各州腐败官员的大规模廉政行动.该行动历时四十余年,取得了显著成效,但一直被美国各界持异议者视为对各州及地方政府的政治独立和现代法治构成了最为严重、最具破坏性的侵蚀.立足于美国语境,从联邦检察官与各州民选检察官之间的比较优势、联邦法官群体反腐伦理倾向、社会舆论基础以及美国实用主义政治、法律传统等多维角度,探究联邦检察官的地方反腐行动得以正当化的因素,有助于加深对美国民主与法治的认识,吸取有益于中国反腐实践的经验.     

Detection of cracks in simply-supported beams by continuous wavelet transform of reconstructed modal data

This paper proposes a new approach for damage detection in beam-like structures with small cracks, whose crack ratio [r = H_c/H] is less than 5%, without baseline modal parameters. The approach is based on the difference of the continuous wavelet transforms (CWTs) of two sets of mode shape data which correspond to the left half and the right half of the modal data of a cracked simply-supported beam. The mode shape data of a cracked beam are apparently smooth curves, but actually exhibit local peaks or discontinuities in the region of damage because they include additional response due to the cracks. The modal responses of the damaged simply-supported beams used are computed using the finite element method. The results demonstrate the efficiency of the proposed method for crack detection, and they provide a better crack indicator than the result of the CWT of the original mode shape data. The effects of crack location and sampling interval are examined. The simulated and experimental results show that the proposed method has great potential in crack detection of beam-like structures as it does not require the modal parameter of an uncracked beam as a baseline for crack detection. It can be recommended for real applications.