大型医疗设备电气设计要点

本文详细介绍了磁共振设备（MRI）、加速器、X射线设备等医院建筑中常用的大型医疗设备的工作原理、临床应用、负荷特性和主要电气参数，并对相应设备的供电方案、配电系统、照明和接地等主要电气设计要点加以说明，可为电气设计人员提供参考。     

Sidelobe suppression in NC-OFDM systems using constellation adjustment

In this letter, a new method for sidelobe suppression in non-contiguous orthogonal frequency division multiplexing (NC-OFDM) systems is proposed. Unlike the conventional approach, sidelobes are suppressed by iteratively adjusting the constellation points for the subcarriers that are close to the edges of the used bandwidth. The constellation points corresponding to the maximum sidelobe suppression are chosen for transmission. Simulation results show that the proposed algorithm yields good performance improvement in terms of sidelobe suppression, and does not have a significant impact on the peak-to-average power ratio (PAPR).     

Identification of the gene PaEMT1 for biosynthesis of mannosylerythritol lipids in the basidiomycetous yeast Pseudozyma antarctica

The yeast Pseudozyma antarctica produces a large amount of glycolipid biosurfactants known as mannosylerythritol lipids (MELs), which show not only excellent surface‐active properties but also versatile biochemical actions. To investigate the biosynthesis of MELs in the yeast, we recently reported expressed sequence tag (EST) analysis and estimated genes expressing under MEL production conditions. Among the genes, a contiguous sequence of 938 bp, PA_004, showed high sequence identity to the gene emt1, encoding an erythritol/mannose transferase of Ustilago maydis, which is essential for MEL biosynthesis. The predicted translation product of the extended PA_004 containing the two introns and a stop codon was aligned with Emt1 of U. maydis. The predicted amino acid sequence shared high identity (72%) with Emt1 of U. maydis, although the amino‐terminal was incomplete. To identify the gene as PaEMT1 encoding an erythritol/mannose transferase of P. antarctica, the gene‐disrupted strain was developed by the method for targeted gene disruption, using hygromycin B resistance as the selection marker. The obtained ΔPaEMT1 strain failed to produce MELs, while its growth was the same as that of the parental strain. The additional mannosylerythritol into culture allowed ΔPaEMT1 strain to form MELs regardless of the carbon source supplied, indicating a defect of the erythritol/mannose transferase activity. Furthermore, we found that MEL formation is associated with the morphology and low‐temperature tolerance of the yeast. Copyright © 2010 John Wiley & Sons, Ltd.     

地下工程抗浮加固设计

地下工程的抗浮设计非常重要,往往决定着工程的成败。本文所述案例由于原设计未充分考虑地下水的影响而致使事故的发生。笔者通过对事故现象的分析,找出了造成事故原因,从而采取经济合理的加固方案使该工程达到了较为满意的经济和社会效益。     

Field reliability modeling based on two-dimensional warranty data with censoring times

ABSTRACT

Warranty data can be used for estimating product reliability, identifying causes of failure and designing warranty policy. Based on two-dimensional warranty data, we utilize an accelerated failure time model to investigate the effect of usage rate on product degradation. The stochastic expectation-maximization algorithm is proposed to estimate parameters of the reliability model considering both censored data and field data. Extensive simulation studies are used to validate the proposed method and to compare it with the maximum likelihood method. The utilities of the results have been demonstrated through real warranty data collected from an automobile manufacturer in China.     

Visible light communications heterogeneous network (VLC-HetNet): new model and protocols for mobile scenario

Wireless Networks - In order to resolve the crowded radio spectrum of wireless communication systems, visible light communications (VLC), which uses a vast unregulated and free light spectrum, has...     

Secondary Coincidence Site Lattice Model for Truncated Triangular β-Mg2Sn Precipitates in a Mg-Sn-Based Alloy

This article presents a model of a secondary coincidence site lattice (CSL^ΙΙ). It is applied to interpret a truncated triangular morphology of β-Mg₂Sn precipitates in an Mg-Sn-based alloy. With a slight long-range strain being accommodated elastically, the distribution of good matching sites (GMS) on interfaces between the β-Mg₂Sn precipitates and α-Mg matrix exhibits double periodicity. One is within GMS clusters, and the other is carried by the constrained-CSL^ΙΙ (CCSL^ΙΙ) points at the centers of the GMS clusters. The calculated results fully agree with the experimental results, including the irrational orientation relationship, the habit plane, and the irrational side facets. The preferred state of the interfaces, the preferred ledge height, and the preferred Burgers vectors of secondary dislocations have been discussed.     

不同插管方式对患者心率及血压影响的临床对比分析

目的:对比快速诱导插管与清醒遗忘插管2种插管方式分别对心率、血压的影响,探讨其临床运用优略。方法:以花溪区人民医院2015年3月~2016年9月80例实施ASA的手术患者作为研究对象,对其进行随机分组,分为快速诱导插管组和清醒遗忘插管组,采用SPSS18.0软件对结果进行统计分析。结果:将两组进行对比后发现,快速诱导插管组在插管前和插管后1 min心率、血压波动明显大于清醒遗忘插管组。结论:清醒遗忘插管方式对困难气道处理、危重患者麻醉等各方面明显优于快速诱导插管,值得临床推广。     

稀土对锌熔法再生WC-8Co合金微观组织的影响

以锌熔回收料为原料,用常规硬质合金生产工艺制备出再生WC-8Co硬质合金试样;用X射线衍射金相显微镜、场发射扫描电子显微镜/EDS能谱分析等测试方法研究了不同稀土钇添加方式制备的再生WC-8Co硬质合金孔隙、孔隙度、杂质形态及成分的差异,并采用截距法测量了WC晶粒尺寸及晶粒度分布。研究结果表明:添加稀土钇可抑制WC晶粒的非均匀长大,在一定程度上减小再生硬质合金的WC晶粒尺寸;可以显著减少再生硬质合金中的A类和B类孔隙,降低合金的孔隙度;稀土钇与杂质元素结合能够改善杂质相形态,由不规则和棒状Ca-S-O相转变为球状或类球形的Ca-Y-S-O相,并显著细化杂质相尺寸;采用复合粉的稀土添加方式使稀土钇元素分布更为均匀,微观组织和含稀土杂质相的均匀细化效果更加显著。     

三冗余控制器在核电汽轮机保护系统中的应用

本文介绍了三冗余控制系统在哈汽田湾核电三号汽轮机组保护系统(ETS)的应用情况,着重阐述了系统的结构、原理、特点,并对Micronet TMR系统与一般三冗余控制系统的区别做出介绍。