重积分对称性的数学原理及应用

本文系统疏理了重积分的对称性,从重积分的换元法出发,给出了几种常用对称性的数学原理,并通过一些算例展示了这些对称性在简化重积分计算方面所发挥的重要作用.     

观念建构为本的化学教学设计研究

以提高学生的科学素养为核心的新课程向以事实为本的课堂教学设计提出了挑战,也为观念建构为本的教学设计提供了展现的平台。在王磊和范晓琼2005年"观念建构为本教学的理论研究"的基础上,提出了观念建构为本的教学设计模型。结合具体教学案例"电离平衡",对如何进行观念建构为本教学设计进行了详细阐述,并提供了电离平衡一节的教学设计。     

Exact tail asymptotics in a priority queue—characterizations of the preemptive model

In this paper, we consider the classical preemptive priority queueing system with two classes of independent Poisson customers and a single exponential server serving the two classes of customers at possibly different rates. For this system, we carry out a detailed analysis on exact tail asymptotics for the joint stationary distribution of the queue length of the two classes of customers, for the two marginal distributions and for the distribution of the total number of customers in the system, respectively. A complete characterization of the regions of system parameters for exact tail asymptotics is obtained through analysis of generating functions. This characterization has never before been completed. It is interesting to note that the exact tail asymptotics along the high-priority queue direction is of a new form that does not fall within the three types of exact tail asymptotics characterized by various methods for this type of two-dimensional system reported in the literature. We expect that the method employed in this paper can also be applied to the exact tail asymptotic analysis for the non-preemptive priority queueing model, among other possibilities.     

Direct analysis of lanthanum in extraction process by in-situ gamma spectrometry

Journal of Radioanalytical and Nuclear Chemistry - High sensitivity analytical techniques, such as ICP-MS, MIP-AES, XRF etc., in rare earth hydrometallurgy, have drastically developed products...     

Analyzing retrial queues by censoring

In this paper we analyze the M/M/c retrial queue using the censoring technique. This technique allows us to carry out an asymptotic analysis, which leads to interesting and useful asymptotic results. Based on the asymptotic analysis, we develop two methods for obtaining approximations to the stationary probabilities, from which other performance metrics can be obtained. We demonstrate that the two proposed approximations are good alternatives to existing approximation methods. We expect that the technique used here can be applied to other retrial queueing models.     

On Modules Over Group Rings

Let M be a right module over a ring R and let G be a group. The set MG of all formal finite sums of the form ∑? _g?∈?G m _g g where m _g ?∈?M becomes a right module over the group ring RG under addition and scalar multiplication similar to the addition and multiplication of a group ring. In this paper, we study basic properties of the RG-module MG, and characterize module properties of (MG) _RG in terms of properties of M _R and G. Particularly, we prove the module-theoretic versions of several well-known results on group rings, including Maschke’s Theorem and the classical characterizations of right self-injective group rings and of von Neumann regular group rings.     

Distribution characteristics of liquid in spiral-wound heat exchanger under sloshing conditions

Journal of Thermal Analysis and Calorimetry - The maldistribution of working medium restricts the heat transfer performance of the spiral-wound heat exchangers (SWHEs), especially when the heat...     

Duplex Surface Enhanced Raman Scattering-Based Lateral Flow Immunosensor for the Low-Level Detection of Antibiotic Residues in Milk

A duplex surface enhanced Raman scattering (SERS)-based lateral flow immunosensor was established for the simultaneous detection of two common antibiotic residues including tetracycline and penicillin in milk. The newly synthesized Au@Ag nanoparticles were labeled with different Raman molecules including 5,5-dithiobis-2-nitrobenzoic acid (DTNB) or 4-mercaptobenzoic acid (MBA), followed by the conjugation of anti-tetracycline monoclonal antibody or anti-penicillin receptor, forming two kinds of SERS nanoprobes. The two nanoprobes can recognize tetracycline-BSA and ampicillin-BSA, respectively, which facilitates the simultaneous detection of the two types of antibiotics on a single test line. After optimization, detection limits of tetracycline and penicillin as low as 0.015 ng/mL and 0.010 ng/mL, respectively, were achieved. These values were far below those of most of other documented bio-analytical approaches. Moreover, the spiking test demonstrates an excellent assay accuracy with recoveries of 88.8% to 111.3%, and satisfactory assay precision with relative standard deviation below 16%. Consequently, the results demonstrate that the SERS-based lateral flow immunosensor developed in this study has the advantages of excellent assay sensitivity and remarkable multiplexing capability, thus it will have great application potential in food safety monitoring.