杨梅果醋发酵工艺研究

以杨梅为原料,采用表面静止发酵方式,先后经过酒精发酵和醋酸发酵制得杨梅醋。在醋酸发酵过程中,通过单因素实验和正交实验,确定了果醋发酵的最佳工艺参数。实验结果表明,最佳醋酸发酵条件为：温度为26℃、接种量为6％、装液量为200ml／L,酒精度为5％时醋酸菌的转酸率最高。参考醋酸发酵过程中花色苷浓度的变化趋势,选择最佳发酵周期为10d。     

聚乙烯亚胺添加剂对碱性镀铜电沉积行为的影响

为了研究碱性镀铜中添加剂对铜电沉积行为的影响,采用一种新型柠檬酸碱性镀铜工艺制备了铜镀层,研究了聚乙烯亚胺添加剂在新型柠檬酸盐碱性镀铜中的作用机理.运用SEM,XRD和电化学方法对镀液、镀层进行了分析.结果表明:聚乙烯亚胺有利于获得较宽的电流密度范围和均匀细致的镀层,使铜镀层表现出(111)晶面的择优取向,铜的沉积为侧向生长;聚乙烯亚胺优先吸附在阴极高电流密度处,并对铜沉积产生较强的阻化作用;铜电沉积的初期行为服从扩散控制和三维连续成核方式生长规律.     

超材料吸波体吸波特性研究

设计了一个强谐振超材料吸波体,它由电谐环振器(Electric ring resonator)和短导线组合而成.采用数值仿真法,在8～12GHz波段提取了这种超材料的s参数,并计算了其吸渡率.单层超材料吸波体在10.2GHz处达到吸收峰,吸波率达91.3%.多层组合吸渡体在9.72GHz处峰值吸波率接近100%.与传统吸波材料不同的是,该超材料吸波体完全由金属结构组成,通过对介电常数和磁导率的灵活调节,经优化设计即可实现对入射电磁波的高吸收.另外,通过尺寸变化的多层组合结构,利用不同吸波频段的叠加效应,实现了对吸波频带的拓宽.     

The Creep Feature Analysis of The High Performance Concrete

In order to seek the creep change rules of ased concrete with two different mix proportions, the test is carried out in the situation which is similar to that of the creation of concrete C60, and the creep test on the concrete of two different mix proportions is done under standard lab. Based on creep test of the high performance concrete, the creep degree and the creep coefficient are obtained. By comparing with the wide-adopted models of AC1209 （1997） and CEB- FIP MC90, it is found that the test result is good at its regularity and the research results offer reference to the calculating analysis of the on-the-spot experimental data.     

Properties and Structure of Magnesium Matrix Composite Reinforced with CNTs

By using high pure Magnesium (99.9 wt% ) as matrix and multi-walled bended carbon nanotubes ( CNTs ) as reinforced phase, carbon nanotubes/magnesium matrix composite was prepared to the foundry method under the argon gas protection, and its mechanical properties were tested. The interface structure and component of plating and un-plating carbon nanotubes were analyzed by TEM and EDS , and the action mechanism was discussed. The experiment results show that the CNTs con strengthen mechanical properties of the nano-tube-reinforced Mg matrix composite, the tensile strength and elongation ratio are greatly improved. Furthermore, the plating CNTs are better than un-plating CNTs in strengthening effects. The tensile strength is inereased by 150% and the elongation ratio is increased by 30% than that of matrix when content of CNTs is 0.67 wt%.     

适用于铁路贯通(自闭)线的高性能FTU的研制

根据铁路10kV贯通(自闭)线的发展现状、铁路电力贯通(自闭)线供电臂与一般馈电线的区别,研制出实用于供电臂分段开关的FTU。它的硬件结构是以80C196KC为核心,外扩8kRAM、32kROM、2kE2PROM24LC16B、两片MAX125、实时时钟DS12887、逻辑和译码器件EPM7128SQC100Q、液晶控制器6963C。软件部分精确采集并处理FTU安装处的线路三相电流和零序电流,上传各电流的实部和虚部。实验室模拟试验证明,它与上位机STU(Substationterminalunit)组网,只要零序电流>0.1A就能可靠处理并识别单相接地故障的故障段,且相间短路故障能按设定时间和动作电流发跳闸信号,达到非故障区段基本不停电,隔离仅限于故障区段的目标。该FTU可扩展性强,稍加改动便可广泛应用于电力系统的配电自动化网中。     

Assessment of barriers to public rental housing exits: Evidence from tenants in Beijing,China

Public rental housing (PRH) exits exert a profound influence on turnover rates, which further impact the public housing principles of fairness and efficiency. However, very few studies have attempted to investigate the tenant's barriers to exit PRH units in Chinese studies. In this paper, using data drawn from a randomly sampled survey of tenants in Beijing during the March 2017, we employ structural equation modeling (SEM) to examine the factors influencing tenant's barriers to exit. We find that housing availability is the most influential factor in determining the tenant's barriers to leave PRH, and residential satisfaction is also considered as a motivation against PRH exits. In addition, residential satisfaction transfers the impact of tenant's perceptions of housing and neighborhood to exit barriers. Especially, the effects of housing availability on exit barriers are higher in some groups, such as elderly, high income households, large-sized families and respondents with long spell of residence. Any program aimed at getting tenants to leave public housing sector needs to reduce their barriers to access to the private rental market and take into consideration the various characteristics of the tenants.     

一种制备唾液酸磁性表面分子印迹聚合物的新方法

一锅法合成氨基化磁性纳米颗粒Fe₃O₄@NH₂,与对甲酰基苯硼酸(FPBA)反应嫁接硼酸官能团,通过硼酸基与模板唾液酸Neu5Ac分子上的顺式二醇共价反应,将Neu5Ac定向固定于磁性纳米颗粒。以多巴胺(DA)及3-氨基苯硼酸(3-APBA)为功能单体,自聚合反应形成共聚壳层包覆在磁性纳米颗粒的表面,制备得Neu5Ac磁性分子印迹聚合物(Neu5Ac-MMIPs)。通过透射电镜、红外光谱对其形态及结构进行表征,并评价其吸附性能。结果表明,Neu5Ac磁性分子印迹聚合物对Neu5Ac具有较好的吸附量、印迹效率、特异性等优点。通过对Neu5Ac至少5次吸附-洗脱的循环实验表明,MMIPs具有较好的重复再利用能力。     

电力物联网中基于多跳网络的密钥管理方案

输电线路状态检测是电力物联网建设中的重要应用,针对输电线路在线监测中部署的大尺度、多跳无线传感器网络,设计了一种新的层次化密钥管理方案,对簇进行重新组织,依据新的跳数来生成新的密钥替换过时密钥。通过WSNs分簇中不同的跳数作为密钥管理机制的种子,实现轻量级的动态密钥安全管理。仿真结果表明,该方案不仅具有密钥系统局域化、低能量损耗、不需要特殊节点等特点,而且也提高了网络安全水平。     

基于关联估计的分散预测控制

考虑了关联大系统的分散控制问题.假设各个子系统可以利用部分关联信息——能够对关联项进行预估.然后各子系统利用预测控制策略实施对子系统的控制,可以证明这种分散预测控制策略使全局系统是有界的大系统.