中低温煤焦油基炭微球的制备

通过馏分切割、温和加氢相结合对中低温煤焦油进行精制处理，精制后的原料采用分级热聚制备中间相炭微球。考察了精制处理条件对原料性质、中间相炭微球宏观外貌及微晶结构的影响。采用FTIR、GC-MS、族组成、元素分析对原料进行表征，采用SEM、XRD对中间相炭微球进行表征。结果表明：中低温煤焦油中300～430℃馏分油是制备中间相炭微球的较佳馏分。300～430℃馏分油中正庚烷可溶物（HS）质量分数高达84.76%，吡啶不溶物（PI）质量分数低至0.23%，杂原子含量低，芳烃化合物的环数为2～4环。300～430℃馏分油在T_H=350℃、p=8MPa、t=1.5h、剂油比1∶40（质量比）的条件下温和加氢得到的精制原料，经420℃热聚6h得制备的中间相炭微球宏观外貌、微晶结构较好。中低温煤焦油基炭微球的粒径范围为5～15μm，小球表面光滑，微观结构为地球仪型，经1450℃高温煅烧后，石墨化度达到12.33%。     

我国饮用水卫生标准的变革及特点

从饮用水安全问题出发，介绍了我国生活饮用水水质标准的现状，剖析和比较了《城市供水水质标准》和《生活饮用水卫生标准》的特点，对检测项目、检测方法和指标值等方面的变革做了分析，同时与国外饮用水水质标准进行了比较，并提出了实施新水质标准存在的问题及建议。     

The Impact of Single-family Mortgage Foreclosures on Neighborhood Crime

Foreclosures of single-family mortgages have increased dramatically in many parts of the US in recent years. Much of this has been tied to the rise of higher-risk subprime mortgage lending. Debates concerning mortgage regulation, as well as around other residential finance policies and practices, hinge critically on the social as well as personal costs of loan default and foreclosure. This paper examines the impact of foreclosures of single-family mortgages on levels of violent and property crime at the neighborhood level. Using data on foreclosures, neighborhood characteristics, and crime, the study found that higher foreclosure levels do contribute to higher levels of violent crime. The results for property crime are not statistically significant. A standard deviation increase in the foreclosure rate (about 2.8 foreclosures for every 100 owner-occupied properties in one year) corresponds to an increase in neighborhood violent crime of approximately 6.7 per cent. The policy implications of these findings are discussed.     

重庆市脱硫石膏建材资源化现状分析

重庆市脱硫石膏年产生量已经超过100万t,重庆市脱硫石膏建材资源化的主要方式是生产建筑石膏、水泥缓凝剂、纸面石膏板和石膏砌块等。但脱硫石膏杂质和含水率高,处理工艺较复杂,品质不稳定等问题严重制约了其在建筑材料中的应用。为了促进脱硫石膏的建材资源化,除了在财税政策上继续给予大力支持外,也需要加大科研投入,在关键应用技术领域取得真正突破,才能更加有力地推动脱硫石膏的建材资源化。     

多天线无人机通信系统中的安全波束成形方案

针对第6代移动通信系统中多天线无人机通信下行链路传输系统,在有多个合法用户和单个窃听者的场景以及已知窃听者统计信道状态信息的情况下,提出了2种安全波束成形方案：一种是基于迫零算法的波束成形方案,在系统传输总功率受限条件下最大化系统可达安全速率,得到了波束成形权矢量和功率分配因子的闭合解;另一种是基于增强信漏噪比算法的波束成形方案,采用一种分式规划和交替方向乘子法（ADMM）相结合的迭代算法,实现波束成形权矢量和功率分配因子的设计.仿真结果表明,相比较于迫零算法,基于ADMM的增强信漏噪比算法能够有效地提升系统的安全性能.     

羧基改性聚乙烯醇的制备及水溶性研究

通过丙烯酸(AA)与乙酸乙烯酯(VAc)共聚进而醇解的方法合成出具有高醇解度、低结晶度的丙烯1酸改性聚乙烯醇。通过FT-IR和H-NMR对聚合物的化学结构进行了表征;通过XRD、UV-Vis、剪切流变测试等手段研究了丙烯酸结构单元含量对改性PVA的结晶性能、水溶性能和溶液表观黏度的影响。结果显示,通过引入适量丙烯酸结构单元,可降低PVA结晶度,提高PVA水溶性,增强PVA水溶液表观黏度的剪切稳定性。     

多西他赛手性侧链的制备

以苯甲醛(Ⅱ)和S-对甲氧基苯乙胺(Ⅲ)为起始原料,缩合制备N-苯亚甲基-4-甲氧基苯胺(Ⅳ),化合物Ⅳ再与乙酰氧基乙酰氯缩合成四元环,经异丙醚重结晶得到单一手性的(+)-顺式-1-对甲氧基苯基-3-乙酰氧基-4-苯基-2-吖叮啶酮(Ⅴ),再经硝酸铈铵氧化脱去对甲氧基苯乙胺得到(+)-顺式-3-乙酰氧基-4-苯基-2-吖叮啶酮(Ⅶ),然后在碱性条件下脱去乙酰基得到(+)-顺式-3-羟基-4-苯基-2-吖叮啶酮(Ⅷ),最后采用一锅法,化合物Ⅷ先与乙烯基乙醚缩合、再与二叔丁基二碳酸酯缩合直接得到多西他赛手性侧链(Ⅰ),总收率23.4%。该合成方法反应条件温和,反应步骤少,收率高。     

CERTAINTY FACTOR THEORY AND ITS IMPLEMENTATION IN AN INFORMATION SYSTEM-ORIENTED EXPERT SYSTEM SHELL

This article discusses some topics related to the MYCIN model for uncertainty handling in expert systems. Some previously identified problems in this model should be considered as evidence to support the point of view that the probabilistic interpretation for measure of belief (MB) and measure of disbelief (MD) given by Shortliffe is inappropriate. In connection lo this, some results achieved by Heckerman are also reviewed and one of his arguments is questioned. According to this argument, the original interpretation for certainty factors implies a noncommutative method for evidence combination, and therefore, this interpretation should be abandoned. Problems similar to those identified by Adams in the original interpretation for certainty factors exist also in the interpretation recommended by Heckerman. Then, in the context of previous results stating that there is an isomorphic mapping from the evidence combination scheme for the likelihood ratio to the evidence combination function adopted in EMYCIN and its successors, we point out that the evidence combination scheme for the likelihood ratio suffers from a strong restriction. We remark upon the complaint that the MYCIN model cannot always function as well as one has expected. Implementation of the certainty factor mechanism in an information system-oriented expert system shell with some substantial changes is described     

GITT studies on oxide cathode LiNi1/3Co1/3Mn1/3O2 synthesized by citric acid assisted high-energy ball milling

Layered LiNi_1/3Co_1/3Mn_1/3O₂ was synthesized by a citric acid assisted solid-state method. The structure and electrochemical properties of the LiNi_1/3Co_1/3Mn_1/3O₂ materials were investigated. XRD analysis indicated the as-synthesized LiNi_1/3Co_1/3Mn_1/3O₂ was with the layered α-NaFeO₂ structure. The discharge capacity was about 154 m·Ahg^???1 at 0·1 °C rate in the range of 2·0–4·5 V. The kinetics of the LiNi_1/3Co_1/3Mn_1/3O₂ materials was investigated by the galvanostatic intermittent titration technique (GITT) method. The lithium ion diffusion coefficient of the LiNi_1/3Co_1/3Mn_1/3O₂ was determined in the range of 10^???8??? 10^???9 cm²· s^???1 as a function of voltage of 3·7?4·5 V.     

A Riccati-like equation arising in suboptimal control

An explicit Formula for the suboptimal control of linear plants has been derived by Teodorescu (1985). Based on this result, the present paper proves that the suboptimal control and trajectory can be obtained by solving a matrix equation of the form XLX + XH + E = 0, where L, H, E are some constant, parameter-dependent matrices. The equation is easier to solve in comparison with the customary Riccati equation. An example is worked out to illustrate the steps of the procedure.