Web软件的易用性测试探究

随着网络技术在软件方面的广泛应用,Web软件以其方便、快速、易操作等特点成为软件开发的重点。作为与用户交互的主要特性,易用性也随之成为Web软件关注的热点,而易用性测试也为越来越多的人所重视。根据Web软件的特点,对Web软件的易用性测试标准、如何进行Web软件易用性测试以及易用性测试的具体操作步骤进行了探讨。     

A theoretical investigation of the emerging standards for web services

Currently, standards for web services are being developed via three different initiatives (W3C, Semantic web services and ebXML). To the best of our knowledge, no theoretical perspectives underlie these standardization efforts. Without the benefit of a strong theoretical basis, the results, within and across these initiatives, have remained piecemeal. We suggest ‘Language–Action Theories’ as a plausible perspective that can effectively define, assess and refine web services standards. In this paper, we first investigate the existing initiatives to identify commonalities that point to theories of ‘Language–Action’ as an appropriate theoretical basis for web services standards. Next, we adapt work from these theories to develop a comprehensive reference framework for understanding web services standards. Finally, we use this reference framework to assess the three initiatives, and analyze the findings to provide insights for future development and refinement of web services standards.

基于时域Neal-Smith准则的人机控制系统设计多目标优化研究

为了获得驾驶员和飞机良好的匹配特性,使用基于人机闭环参考模型的方法将飞行品质的要求引入优化算法,进行飞行控制系统设计。首先使用CAP准则建立飞机等效系统模型。然后,基于时域Neal-Smith准则,通过多目标优化算法一次性得到在不同任务条件下的最优驾驶员模型。根据需要选择相应的驾驶员模型,并与飞机等效系统模型组成人机闭环参考模型,进行飞行控制设计多目标优化。仿真结果显示,文中的算法不仅可以整定控制器参数,根据任务需求选取最优驾驶员模型,还可以利用优化结果进行PIO易感性的分析。     

A high-order compact method for nonlinear Black–Scholes option pricing equations of American options

Due to transaction costs, illiquid markets, large investors or risks from an unprotected portfolio the assumptions in the classical Black–Scholes model become unrealistic and the model results in nonlinear, possibly degenerate, parabolic diffusion–convection equations. Since in general, a closed-form solution to the nonlinear Black–Scholes equation for American options does not exist (even in the linear case), these problems have to be solved numerically. We present from the literature different compact finite difference schemes to solve nonlinear Black–Scholes equations for American options with a nonlinear volatility function. As compact schemes cannot be directly applied to American type options, we use a fixed domain transformation proposed by ?ev?ovi? and show how the accuracy of the method can be increased to order four in space and time.     

试论美国动画片《花木兰》中的中国祖先文化

1998年美国迪斯尼动画片以中国北魏时期的民间故事《木兰辞》为素材拍制动画片《花木兰》,一经放映就取得很高关注度,在全世界范围内掀起了中国文化热,其中具有几千年历史的中国祖先文化也贯穿始终。本文对动画片《花木兰》中体现出来的中国祖先文化作简要分析。影片在表面上宣扬和体现了中国祖先文化,但深其本质,影片体现出来的中国祖先文化带有浓重的美国文化元素。     

Reach distance and safety standards

The reach of British males of 99th percentile stature over different height barriers was determined to establish reach distances for a proposed Comite Europeen de Normalisation (CEN) standard. The distances recorded are considerably in excess of those given in the draft West German standard DIN 310011984, and those given in the recently published British standard code of practice for safety of machinery BS.5304. Data are included from earlier experiments which show that the safety distances would also be inadequate for the 95th percentile stature British male. It is suggested that reasons for the discrepancies arise mainly from the differences in the way that the reach measurements were obtained.     

A new radial basis functions method for pricing American options under Merton's jump-diffusion model

A new radial basis functions (RBFs) algorithm for pricing financial options under Merton's jump-diffusion model is described. The method is based on a differential quadrature approach, that allows the implementation of the boundary conditions in an efficient way. The semi-discrete equations obtained after approximation of the spatial derivatives, using RBFs based on differential quadrature are solved, using an exponential time integration scheme and we provide several numerical tests which show the superiority of this method over the popular Crank–Nicolson method. Various numerical results for the pricing of European, American and barrier options are given to illustrate the efficiency and accuracy of this new algorithm. We also show that the option Greeks such as the Delta and Gamma sensitivity measures are efficiently computed to high accuracy.