数学因“动”而精彩

新教材理念下的教与学是多元的，其中，教学的“动”应该占有重要的地位，它是调动学生的学习积极性，使学生主动参与课堂学习、集中精力学习的最好的途径．数学的“动”包含两方面内容：数学内容的“动”以及学生的参与活动．本文从这两方面展开讨论，并提供几个“动”的课例．

Influence of Diesel Nozzle Geometry on Cavitation Using Eulerian Multi-Fluid Method

Dependent on automatically generated unstructured grids, a comprehensive computational fluid dynamics(CFD)numerical simulation is performed to analyze the influence of nozzle geometry on the internal flow characteristics of a multi-hole diesel injector with the multi-phase flow model based on Eulerian multi-fluid method.The diesel components in nozzle are considered as two continuous phases, diesel liquid and diesel vapor respectively.Considering that both of them are fully coupled and interpenetrated, sepa...

The Structure Theorem for Module Coalgebras

This paper,mainly gives the structure theorem for module coalgebras by a kind of new method,and deletes the condition that the antipode S of the Hopf algebra H is bijective.

A New Fractal Model of Elastic,Elastoplastic and Plastic Normal Contact Stiffness for Slow Sliding Interface Considering Dynamic Friction and Strain Hardening

The deflection properties of elastic stage, elastoplastic stage and plastic stage of elastomer were analyzed. Taking account of the kinetic friction force in friction interface and strain hardening in slow sliding interface, the elastic, elastoplastic and plastic normal contact stiffness model for harsh surface was established, which revised the Majumdar-Bhushan fractal model and made it more perfect. In the combination of macro and micro perspective, the effects of coarse surface fractal variables, kinetic friction force in the friction interface, material characters of the friction couples on the contact status and contact property were discussed by the study of digital analysis. Results imply that the normal contact stiffness improves with the increasing real contact area and normal contact load, and reduces with the augment of kinetic friction coefficient. When the kinetic friction coefficient is smaller than 0.3, the normal contact stiffness comprises a linear decrease with the increment of kinetic friction coefficient. When the kinetic friction coefficient is bigger than 0.3, the normal contact stiffness has an exponential decrease with the increasing kinetic friction coefficient. © 2017, Shanghai Jiaotong University and Springer-Verlag GmbH Germany.

Mathematical models of canine right and left atria cardiomyocytes

The aim of this study is to build two mathematical models of canine ionic currents specific to right atria and left atria.The canine left atria mathematical model was firstly modified from the Ramirez-Nattel-Courtemanche(RNC) model using the recently available experimental data of ionic currents and was further developed based on our own experimental data.A model of right atria was then built by considering the differences between right atria and left atria.The two developed models well reproduced the experimental data on action potential morphology,the rate dependence,and action potential duration restitution.They are useful for investigating the mechanisms underlying the het-erogeneity of canine regional action potentials and would help the simulation of whole heart excitation propagation and cardiac arrhythmia in the near future.

Efficient link scheduling with joint power control and successive interference cancellation in wireless networks

Existing works have addressed the interference mitigation by any two of the three approaches: link scheduling, power control, and successive interference cancellation(SIC). In this paper, we integrate the above approaches to further improve the spectral efficiency of the wireless networks and consider the max-min fairness to guarantee the transmission demand of the worst-case link. We formulate the link scheduling with joint power control and SIC(PCSIC) problem as a mixed-integer non-linear programming(MINLP), which has been proven to be NP-complete. Consequently, we propose an iterative algorithm to tackle the problem by decomposing it into a series of linear subproblems, and then the analysis shows that the algorithm has high complexity in the worst case. In order to reduce the computational complexity, we have further devised a two-stage algorithm with polynomial-time complexity. Numerical results show the performance improvements of our proposed algorithms in terms of the network throughput and power consumption compared with the link scheduling scheme only with SIC.

Performance Modelling of Patient Flow Scheduling Through a Formal Method

Smart environment is being used in many areas to deliver more services to individuals in a physical space, such as a hospital. In the UK, the National Health Service(NHS) provides free and high quality healthcare service for all residents. Smart hospital environment is able to support NHS and provide more convenience. Patient flow scheduling is a crucial section in a smart hospital environment. Smart hospital environment aims to provide a smart environment in the hospital to facilitate individual experience and improve the quality of healthcare service.First of all, this paper investigates a real world patient flow scenario of a hospital in the UK and models a general scheduling scheme based on the scenario using a compositional formal approach, i.e. performance evaluation process algebra(PEPA). This scheduling scheme uses an easy-implemented solution(the grouping scheme) to reduce the waiting queue in the hospital. Secondly, fluid flow analysis is used for the performance analysis by generating a set of ordinary differential equations(ODEs) in terms of the PEPA model.

System of Generalized Symmetric Vector Quasi-Equilibrium Problems for Set-Valued Mappings

In this paper, a system of generalized symmetric vector quasi-equilibrium problems for set-valued mappings is introduced. By using a scalarization method and a fixed-point theorem, the existence result for its solution is established. The main result extends the corresponding results in Fu (J. Math. Anal. Appl. 285, 708–713, 2003) and Zhang, Chen and Li (OR Transactions 10, 24–32, 2006).