供需模型在众包平台定价中的应用

以众包平台为对象,基于已有数据,考虑供求关系,通过因子分析法对原始数据加以处理,建立任务的定价模型.在实际应用中,可以对分布密集的任务进行打包,并给出针对这种情况的定价模型.结果表明:提出的模型不仅考虑了会员人数与任务数量的关系,还考虑了个人需求的差异,提高了任务的完成度,对众包平台定价的发展与完善有着重要的意义.     

多层对称薄膜的光子晶体光波导设计

基于多层对称薄膜的反射镜作用,设计了一种工作波长位于1550nm附近的基于周期性多层膜的光子晶体光波导。由平板波导的相关理论分析了波长在1515~1587nm范围内电磁波在波导中的传输性质。研究表明TE模和TM模在波导都是基模传输,其功率约束因子(Γ)限制在0.99~1之间,说明波导近乎完全将光波限制在其中传输。在控光能力上这种结构要比普通的三层薄膜波导更具优势。利用周期性多层膜的光子带隙结构,可以构造具有超低损耗的全向带隙介质光波导。     

A computer model of pulse wave and input impedance in human arteries

To predict the propagation of pressure and flow pulses in arterial system and the variation of vascular input impedance, a branched and tapered tube model is studied through one-dimensional transient flow analysis. Coupling the continuity and momentum equations yields a group of quasilinear hyperbolic partial differential equations which can be solved numerically by using the method of characteristics. Several boundary conditions of the arterial system are also simplified suitably. The propagation of the pulses of the arterial system and the vascular input impedance is calculated on computer by using the dimensions and the physiological data of the arterial system. The results point out that the pressure and flow pulses of the arterial system and the vascular input impedance produced by this theoretical model is consistent quite well with the experimental results published.     

数字逻辑的稳健神经网络实现

多层二进前向神经网络或布尔神经网络作为典型的人工神经网络模型，研究和应用的十分广泛，这里在分析数字逻辑基本运算和神经元关系后，提出了一种改进的利用三层前向感知器神经网络实现任意数字逻辑函数的新算法，该算法由稳健的感知器构造神经网络，并引入汉明距离化简、卡诺图化简和最小项抑制来降低网络的复杂性，由此算法构造的神经网络不但具有稳健性能，而且消除了对数字输入变量所作的变换，使其更加简单、规范，容错能力更强，可广泛应用于对数字电路设计、编码密码的研究。     

内部爆炸作用下多层钢筒的动态响应

为评估内部爆炸作用下多层钢筒结构的防护效果,考察多层钢筒结构动态响应和变形吸能特征,采用两端开口、总厚度为50 mm的4层圆柱形Q345钢筒,在8.90~18.18 kg TNT药量下进行爆炸实验,并在容器外壁进行应变电测。实验后钢筒结构爆心局部发生塑性变形,内层钢筒变形最大,但未发生破坏。根据研究得到初步认识:采用爆心单位环面变形吸能的设计方法,可以较好地预估给定药量下所需钢筒的厚度;不同药量下,轴向距离超过多层钢筒结构的1/4内径后,其外壁环向变形峰值约减小为爆心截面环向应变峰值的1/2。     

表面吸附K原子的多层FeSe/SrTiO3(001)薄膜的抗磁响应的原位测量

SrTiO₃（001）单晶表面上生长的单层FeSe薄膜显示出了超乎寻常的高温超导电性,其超导增强机制的一个重要因素是电子由衬底转移到了单层FeSe薄膜当中.基于此认识,研究者们在吸附了钾（K）原子的多层FeSe薄膜表面上观察到了类似超导能隙的隧穿能谱和光电子能谱.但这种自上而下的电子掺入方式在多层FeSe薄膜表面上可能引起的高温超导电性,还缺乏零电阻或迈斯纳效应等物性测量实验的直接证实.本研究利用自行研制的一台特殊的多功能扫描隧道显微镜,在生长于SrTiO₃（001）衬底上的多层FeSe薄膜表面上,不但观察到了超导能隙随K吸附量的变化,而且利用原位双线圈互感测量技术,成功地的观察到了该薄膜的抗磁响应,并由此确定了该薄膜样品呈现迈斯纳效应的超导转变温度为23.9 K.其穿透深度随温度的变化呈二次幂指数关系,表明该体系的超导序参量很可能具有S^±配对对称性.     

用于高能X射线能谱测量的MLS法

为满足高能X射线能谱测量的需要,提出采用MLS法进行能谱测量的方案。MLS法克服了其他测量方法散射不易控制、光场不均匀性影响较大的缺点,还具有对不同角度能谱进行测量的优势。对MLS法的测量原理以及测量过程中的注意事项进行了明确,并利用蒙特卡罗方法针对一特定的X射线能谱设计了两种不同介质的测量装置,并将测量装置自身散射的影响控制在5%以内。     

一类非线性奇摄动问题的多层解

利用匹配渐近展开法,讨论一类非线性奇摄动边值问题中边界层内存在两个特异极限的多层解.首先,构造原问题的外部解;其次,利用伸长变量,求得了两个特异极限,进而得到了对应问题的两个内部解;最后,研究了边界层位于三种不同位置的多层解,利用匹配原则,求出了各种情形解的一致有效     

Neural networks: A biased overview

An overview of recent activity in the field of neural networks is presented. The long-range aim of this research is to understand how the brain works. First some of the problems are stated and terminology defined; then an attempt is made to explain why physicists are drawn to the field, and their main potential contribution. In particular, in recent years some interesting models have been introduced by physicists. A small subset of these models is described, with particular emphasis on those that are analytically soluble. Finally a brief review of the history and recent developments of single- and multilayer perceptrons is given, bringing the situation up to date regarding the central immediate problem of the field: search for a learning algorithm that has an associated convergence theorem.     

Signal Penetration into Thick Clouds Studied by Multi-Layer Data Observed with a Micro-Pulse Lidar

Lidar return signals are studied for a micro-pulse lidar under sky conditions with multi-layer clouds. From theoretical considerations on the lidar signal-to-noise ratio, it is estimated that the maximum cloud optical thickness detectable is about 3.7. This result reasonably agrees with the actual multi-layer cloud data obtained from observations in Sukhothai, Thailand. Deviations from theoretical prediction, however, are found for a geometrically thin but dense cloud, and for a moderately concentrated but geometrically thick cloud. The effect of multiple scattering is also discussed.