目标规划在大学生学习成绩预测中的应用

大学生学习成绩预测是非常有必要的。文章首先介绍了用最小二乘法进行线性回归预测的方法，并分析了其缺点，即当存在着极端的异常情况时，往往存在着较大的预测误差。其次文章介绍了另一种建立预测方程的方法——目标规划法，并详细分析了模型的建立过程。文章最后举了一实例，将两种方法进行了比较，结果证明，当存在着异常情况时，目标规划是一种较好的预测方法。     

用燕尾突变理论来讨论交通流预测

交通流本身是一个动态过程，运用尖点突变理论来分析交通流的预测时只考虑了流量和密度，而忽视了时间因素，这本身就不是很合理的．基于这个基础之上，采用燕尾突变理论来讨论交通流预测时将时间因素考虑进去，并给出一个算例表明了此方法预测的效果更符合现实。     

ANALYSIS OF WAVEFORM ERRORS IN MILLIMETER-WAVE LFMCW SYNTHETIC APERTURE RADAR

In remote sensing applications, there is a special interest in the lightweight, cost effective, and high resolution imaging sensors. The combination of linearly frequency modulated continuous wave (LFMCW) technology and synthetic aperture radar (SAR) technique can lead to such a sensor. This paper concentrates on the analysis of waveform errors in millimeter-wave (MMW) LFMCW SAR. The generating scheme of millimeter-wave LFMCW waveforms with phase locked loop (PLL) and direct digital synthesizer (DDS) combined frequency synthesizer is investigated. The impacts of quantization errors, spurs, and frequency nonlinearities are analyzed. Simulation results show that the quality of LFMCW waveforms has a direct influence on the SAR images. Hence a scheme of frequency synthesizer to achieve high performance MMW LFMCW waveform is proposed. This synthesizer driven by a DDS array can adaptive suppress the spurious level without degradation of excellent frequency linearity and fast switching speed.     

基于Fisher准则的两组判别分析方法在夏季降水预报中的应用

根据1959—2004年(12月到次年3月)逐月大气环流特征量资料,运用基于F isher准则的两组判别分析方法,预报安徽宣城夏季降水量.结果表明,历史拟合率高,在预报业务中具有实用价值.     

Degeneracy in infinite horizon optimization

We consider sequential decision problems over an infinite horizon. The forecast or solution horizon approach to solving such problems requires that the optimal initial decision be unique. We show that multiple optimal initial decisions can exist in general and refer to their existence as degeneracy. We then present a conceptual cost perturbation algorithm for resolving degeneracy and identifying a forecast horizon. We also present a general near-optimal forecast horizon.This material is based on work supported by the National Science Foundation under Grants ECS-8409682 and ECS-8700836.     

A compact numerical algorithm for solving the time‐dependent mild slope equation

The mild slope equation has been widely used to describe combined wave refraction and diffraction. In this study, a new numerical algorithm is developed to solve the time‐dependent mild slope equation in a second‐order hyperbolic form. The numerical algorithm is based on a compact and explicit finite difference method that is second‐order accurate in both time and space. The algorithm has the similar structure to the leap‐frog method but is constructed on three time levels for the second‐order time derivative term. The numerical model has the capability of simulating transient wave motion by correctly predicting the speed of wave energy propagation, which is important for the real‐time forecast of the arrival time of storm waves generated in the far field. The model is validated against analytical solution for wave shoaling and experimental data for combined wave refraction and diffraction over a submerged elliptic shoal on a slope (Coastal Eng. 1982; 6 :255). Lastly, the realistic scale Homma's island (Geophys. Mag. 1950; 21 :199) is studied with the use of various wave periods of T = 720s, T = 120 s, and T = 24 s. These wave periods correspond to long, intermediate, and short waves for the given topography, respectively. Comparisons are made between numerical results and existing analytical solutions in terms of the wave amplification around the island, which serves as the indicator for the potential wave runup. Excellent agreements are obtained. The model runs on a PC (Pentium IV 1.8GHz) and the computer capacity allows the computation of a mesh system up to 3000 × 3000, which is equivalent to about 150 × 150 waves or a large area of 540km × 540km for a wave train with the period of T = 60 s. Copyright 2004 John Wiley & Sons, Ltd.     

Varian系统所有通道上的整形脉冲

本文介绍了Varian系统所有通道上的整形脉冲;整形脉冲的形状;波形发生器的功率适中的脉冲整形以及应用"Tophat"的选择激发;整形脉冲与选择性反转;选择性反转或宽带反转,整形脉冲的宽带激发;以及多频率激发的移层式脉冲等.     

大气中臭氧含量分析预测的支向量机模型

以俄亥俄州(O h io)的气象、臭氧监测数据为基础,对一个监测点数据进行了分析处理,运用支持向量机回归方法,对气象指标的多参数样本进行学习,获得精确的支持向量机映射关系,并对臭氧含量进行预测.预测结果的误差较小,符合实际情况,能够较好的解决实际问题,说明支持向量机回归在预测上具有小的结构风险与强的泛化能力.     

Allocation of flexible and indivisible resources with decision postponement and demand learning

We consider a firm that uses two perishable resources to satisfy two demand types. Resources are flexible such that each resource can be used to satisfy either demand type. Resources are also indivisible such that the entire resource must be allocated to the same demand type. This type of resource flexibility can be found in different applications such as movie theater complexes, cruise lines, and airlines. In our model, customers arrive according to independent Poisson processes, but the arrival rates are uncertain. Thus, the manager can learn about customer arrival rates from earlier demand figures and potentially increase the sales by postponing the resource allocation decision. We consider two settings, and derive the optimal resource allocation policy for one setting and develop a heuristic policy for the other. Our analysis provides managerial insights into the effectiveness of different resource allocation mechanisms for flexible and indivisible resources.     

Boosting the advantages of biosensors: Niche applicability and fitness for environmental purpose

Environmental assessments rely on data derived from metrological schemes in order to draw in due detail the state of the ecosystems. The reliability of the data and the cost-effectiveness of the scheme become critical, especially if the ultimate goal involves decision making and policy development. Biosensor platforms provide the versatility required for integrating environmental, metrological and operational parameters at the design phase. The pertinency and the opportunity for environmental biosensing is apparent, although not seized appropriately with only a few environmental biosensors in the market. This study is based on a technology forecasting approach using bibliometric data to trace the dynamics of the science base and content analysis to identify the drawbacks of the technology base. The results are compared with market forecasts in an effort to align research dynamics with market opportunities. A number of key findings emerged, such as the increase in networking and the establishment of a multi-disciplinarity trend, as well as a shifting of research scope towards ready-to-market designing. Notwithstanding, a renewed interest of the physical chemistry sector has been identified herein, indicating necessary revisions of the science-base, adding a critical parameter in the uncertainty of trajectories.