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51.
教育资源价值补偿问题的提出,为高校预算改革提供了新的视角。面向绩效的高校预算管理模式能有效地提高高等教育办学效益,也是实现教育资源价值补偿的制度保障。 相似文献
52.
本文由高校教师培训现状及缋效技术的基本理论出发,在构建高校教师培训评价体系过程中使用绩效技术理念,将高校教师培训的培训问题进行更加整体和系统性的研究,目的是讨论将缋效理念放入高校教师培训评价是否可行和必要,设计一整套的评价体系来进行高校教师培训的评价. 相似文献
53.
[目的]建立青海省唐古特铁线莲中齐墩果酸成分HPLC指纹图谱,为其质量控制提供方法学依据.[方法]采用HPLC法建立唐古特铁线莲中齐墩果酸指纹图谱,标示其共有峰与特征峰,进行相似度评价.[结果]通过对10批唐古特铁线莲药材的测定,标定15个共有峰和12个非共有峰,建立了测试样品的HPLC指纹图谱.[结论]该方法准确、稳定、可靠,可用于唐古特铁线莲的质量研究和评价. 相似文献
54.
S. Minkevičius 《Acta Appl Math》2008,104(3):271-285
The model of an open queueing network in heavy traffic has been developed. These models are mathematical models of computer
networks in heavy traffic. A limit theorem has been presented for the virtual waiting time of a customer in heavy traffic
in open queueing networks. Finally, we present an application of the theorem—a reliability model from computer network practice. 相似文献
55.
Peixia Gao Sabine Wittevrongel Joris Walraevens Herwig Bruneel 《Mathematical Methods of Operations Research》2008,67(2):269-284
In this paper, we study the behavior of a discrete-time multiserver buffer system with infinite buffer size. Packets arrive
at the system according to a two-state Markovian arrival process. The service times of the packets are assumed to be constant,
equal to multiple slots. The behavior of the system is analyzed by means of an analytical technique based on probability generating
functions (PGF’s). Explicit expressions are obtained for the PGF’s of the system contents and the packet delay. From these,
the mean values, the variances and the tail distributions of the system contents and the packet delay are calculated. Numerical
examples are given to show the influence of various model parameters on the system behavior. 相似文献
56.
磁场电源是 HL-2M 装置初始等离子体放电的重要组成部分,它关系到 HL-2M 装置零场的建立,等
离子体的击穿和维持及位形控制。为实现初始等离子体放电所需的供电电压和电流,对磁场电源从主回路、控制、
测量和保护分别作了相应的调整。在此基础上进行了大量的工程调试,确保了磁场电源的控制和保护等性能达到
初始等离子体放电的需求。在磁场电源运行中,电源控制性能和输出参数的一致性、纹波质量等都有显著提高。
介绍了磁场电源在调试及 HL-2M 装置初始放电中的应用。 相似文献
57.
Modification of membrane surface for anti-biofouling performance: Effect of anti-adhesion and anti-bacteria approaches 总被引:2,自引:0,他引:2
Membrane biofouling refers to the undesirable accumulation (attachment and growth) of microorganisms on a membrane surface, and has been a major problem in the application of membrane technology in water and wastewater treatment. In this study, the surface of a base membrane made of chitosan/cellulose acetate blend was modified by reacting with heparin, quaternary ammonium or being immobilized with silver ions. The purpose of the modifications was to increase the surface hydrophilicity, alter the surface charge property or endue the surface with anti-bacteria function. The modified membranes were then examined for their anti-biofouling performance in terms of the anti-adhesion and anti-bacteria effects, with Escherichia coli pure culture and mixed culture bacteria in a bioreactor that simulated the activated sludge wastewater treatment process. The results clearly show that the hydrophilicity of a membrane, although important, is not an effective indicator for the tendency of membrane biofouling but the nature of the surface charges of the membrane also plays a very important role. It was found that the anti-adhesion approach that prevents the initial attachment of bacteria on a membrane surface is a more effective method than the anti-bacteria approach that aims at killing bacteria already attached on the membrane surface. The best performance for minimizing membrane biofouling has, however, been realized through a modified membrane surface that has effective anti-adhesion property plus additional anti-bacteria function, with the latter as a safe guard in case some bacteria do attach to the surface of a membrane. 相似文献
58.
The paper presents a new tool for the determination of inorganic speciation forms of aluminium: AlFn(3 − n)+, and Al3+ by means of the HPIC-FAAS. The proposed method has been successfully used for speciation analysis (qualitative and quantitative) of inorganic aluminium forms AlFn(3 − n)+ in soil samples. In order to isolate the most environmentally available fraction, 5 g of the sample was collected and extracted in deionised water (water soluble fraction) for 1 h using a magnetic stirrer. The determinations in a hyphenated technique system were performed for a number of prepared water extracts. Concentration determinations of particular aluminium forms were performed based on model studies and real samples. The separation of Al species with nominal charge of + 1, + 2, and + 3 required a run time of less than 4 min during a single analysis. Based on the analysis of water extracts of soil, it was obtained that aluminium forms elute in the following order: 1PA (first signal) — AlF2+ and/or AlF4−; 2PA (second signal) — AlF2+ and/or AlF30; 3PA (third signal) — Al3+. In order to confirm the occurrence of these forms a simulation using the Mineql program was conducted. The details of speciation analysis of aluminium fluoride forms by means of an HPIC-FAAS instrument equipped are presented. Interpretation of the speciation analysis of the water soluble fraction of soil samples is proposed, based on the separation during chromatographic run and calculated data by Mineql. 相似文献
59.
Acid/base modifiers are sometimes used as additives in normal phase elution on columns packed with CHIRALPAK® AD®. These modifiers affect enantioseparations in ways that are not yet fully understood for the lack of systematic studies. Shifts of the selectivity of certain pairs of enantiomers upon exposure of the column to these modifiers is amply documented. Furthermore, once the modifier has been removed from the mobile phase, the modified selectivity remains, which has been named the Memory Effect. After a column has been exposed to an eluent stream containing acidic/basic modifiers, this particular column no longer separates certain enantiomeric pairs with the same selectivity as a modifier naive column. This makes the transfer of developed methods from one to other CHIRALPAK AD columns difficult to predict, if the selectivity needs to be similar between the two columns. We selected four enantiomeric pairs for a systematic study of this Memory Effect. The selectivity of 4-chlorophenylalanine ethyl ester improves after a solution of ethanesulfonic acid (ESA) is percolated through the column. The selectivity of Propranolol and Tröger's base increases after a solution of Diiospropylamine is percolated through the column. The selectivity of Propranolol and Tröger's base enantiomers is inversely affected by percolation of the acid solution. The 4-chlorophenylalanine ethyl ester enantiomers is inversely affected by percolation of the base solution. In contrast, the selectivity of trans-stilbene oxide (TSO) is not affected by either modifier. Analytical studies of the stationary phase suggest that slow protonation/deprotonation of water molecules attached to the carbamate moiety may be responsible for the acid/base Memory Effect. To further the understanding of the effect of water on the Memory Effect, mobile phases – spiked with water (0.01–0.43%) – were used to measure changes in the Memory Effect. Finally, we showed that the influence of water on the Memory Effect can be minimized by percolating through the column a sufficiently concentrated solution of the appropriate base while using dried mobile phases. 相似文献
60.