Pushing the envelope of the test functions in the Szegö and Avram–Parter theorems

The Szegö and Avram–Parter theorems give the limit of the arithmetic mean of the values of certain test functions at the eigenvalues of Hermitian Toeplitz matrices and the singular values of arbitrary Toeplitz matrices, respectively, as the matrix dimension goes to infinity. The question on whether these theorems are true whenever they make sense is essentially the question on whether they are valid for all continuous, nonnegative, and monotonously increasing test functions. We show that, surprisingly, the answer to this question is negative. On the other hand, we prove the two theorems in a general form which includes all versions known so far.     

魔芋总生物碱量的测定

用酸性染料比色法测定魔芋总生物碱量,以盐酸金刚烷胺计,在2—10μg/mL范围内线性关系良好。设计正交试验选择总生物碱的最佳提取条件为：料液比1：12,乙醇浓度85%,索氏提取4h。     

原子吸收光谱法测定重金属铬的含量

以火焰原子吸收光谱法测定重金属铬含量为宗旨,考察了雾化器流量、乙炔流量、氧化剂流量、燃烧头高度、基本改进剂等因素,结果发现,通过实验条件优化,校正系数从0.998265提高到0.999998,该方法能最大程度改善火焰原子吸收光谱法测定铬元素灵敏度低的问题,具有快速、准确、灵敏度高等优点,为与人类密切相关的食品、药品、化妆品、医疗器械等产品中重金属铬含量测定提供一定的参考。     

紫草的提取工艺

对紫草提取工艺中各参数进行了优化,为紫草工业化提取提供一定的参考;以左旋紫草素含量的测定为工艺指标,通过正交设计试验,对乙醇浓度,乙醇体积,浸泡时间,及渗漉时间各因素进行了考察;紫草最佳提取工艺为：5倍量80%乙醇浸泡16h,再加10倍量80%的乙醇渗漉4h;适宜工艺为：5倍量80%乙醇浸泡12h,再加10倍量80%的乙醇渗漉4h;本工艺设计合理,工艺稳定,左旋紫草素提取率高,质量可控,适宜于工业化生产。     

Singular densities,test particles and generalized Hamiltonian systems in general relativity

We derive the motion equations and the structure equations of neutral and charged test particles, starting from the gravitational field equations. The method consists in the application of conservation laws to singular tensor densities, which represent regions of strong matter concentration. Moreover, a Hamiltonian formulation of the particle equations is given, in the form of implicit differential equations generated by Hamiltonian Morse families.     

Resource downgrading

This paper aims to develop models to optimally manage costs associated with resources that can be downgraded. These resources are reused a number of times before becoming unsuitable for their original purpose, and then they are assigned for some other purpose. The typical decisions are the quantity of resources to purchase, to downgrade and to hold in the inventory. A network-based model is developed to formulate the problem and to investigate several special cases. As the model becomes an integer program due to some side constraints, several heuristics are developed here to overcome the challenges associated with solving the resulting integer program. A semiconductor industry application for test wafer management is presented using real-life data.     

一种新型的化学离子敏（1）一次性血液电解质钾、钠测试卡片的研制和应用

新型的一次性化学离子敏钾、钠测试卡片，是基于离子选择电极（ＩＳＥ）原理设计制作的一种电化学传感器~［１］。它由测量电池装置、敏感膜、接触衬底（石墨）和盐桥等构件组装而成。采用两点电位测量法。具有一次性使用、简便、快速、精确度高、成本低等优点，对样品不必作预处理，避免了交叉污染，克服了ＩＳＥ重现性差、固有漂移等缺点，发挥了ＩＳＥ选择性好、准确度高等优点。根据临床应用和抽样测试结果，钾、钠测试卡片的精密度±ＳＤ：钾１．０；钠２．０，Ｃ．Ｖ％：钾３．０％；钠２．０％；响应时间为３０ｓ；漂移：钾０．３ｍＶ／ｍｉｎ；钠０．５ｍＶ／ｍｉｎ；回收率为９９．５％，均符合临床应用的基本要求。     

Performance analysis of test scheduling schemes for a multi-access communications network

In this paper, we investigate the performance of two implementable test scheduling schemes for a multi-access communication channel whose components are subject to failure or malfunction. We relate the reliability of the system design, as reflected by system failure rate parameters, and the frequency at which the system (or nodal subsystem) is tested for failure detection, to the underlying key message delay and throughput performance. We derive queue-size distribution results for a discreteGeom ^(X)/D/1 system, representing the operation of the multi-access channel, or of a network node operating as a communications or queueing processor, which is maintained by a periodic or near periodic test scheduling scheme. Explicit formulas are presented for the system behavior as exhibited by the generating functions of the system queue-size distributions. The mean message delay is then calculated. The mean delay (or mean system size/workload performance index) can then be optimized by selecting the proper scheme parameters, under specified system (and component) failure conditions, noting that performing a test at too high a rate leads to inefficient system bandwidth utilization, while if tests are not carried out often enough, excessive message (or task) retransmissions and delays ensue.     

测定总氮时影响空白吸光值的因素

针对GB 11894-89测定污水中总氮空白值偏高的情况,分析了碱性过硫酸钾本身以及纯度的影响、消解量、消解温度和时间、去离子水纯度、玻璃器皿的洁净度、碱性过硫酸钾存储时间、环境因素等影响因素,找出了实验出现问题的原因,并进行了校正.     

深圳某电厂H型钢桩沉桩与效果测试

在上部为花岗岩块石填土、下部为相对软弱的粘性土 ,地下水与海水相通的地区进行大型工程建设 ,主要建 (构 )筑物采用桩基础是安全可靠的措施 ,但采用何种桩型、沉桩时怎样才能顺利穿过花岗岩块石填土是一个值得研究的课题。采用潜孔锤引孔穿过花岗岩块石填土 ,往孔内回填碎石 ,然后打H型钢桩 ,在深圳某电厂地基处理中获得了较好的效果