Computing airfare elasticities or opening Pandora's box

Airfare elasticities are crucial for policy instruments for the stakeholders of tourism industry. Modellers attempting to estimate these elasticities face several challenges in the absence of microeconomic data on consumer preferences. The aim of this paper is to offer a critical analysis of the practice of computing airfare elasticities from tourism demand studies. It identifies and discusses potential sources of measurement errors in the data and drawbacks that investigators face and assesses their implications for the estimated parameters in the respective models. The use of price of crude oil and distance between origin and destination as proxies for transportation costs are evaluated. It is recommended that authors be more systematic in reporting their results. They need to comment on the limitations of their elasticity estimates since these have repercussions on policy recommendations made based on their results.     

规范化安全评估与港口船舶交通安全

港口船舶交通是海上交通运输系统的一个子系统。该系统所具有的危险性，可能造成的损失，人们可接受的风险值究竟如何，所有这些都依赖于有效和合理的安全评价。规范化安全评估(FSA)是近年来国外已在不断推广应用的一种安全评估方法。在简要介绍FSA特点与实施步骤的基础上，文中根据港口船舶交通安全评估的实际情况与需要，采用人工神经网络的方法对港口船舶交通系统的模型和技术路线进行了论述，并就相应人为因素的研究提出一些建议，以改进港口船舶交通安全工作和提高其安全水平。     

Iterative Approximation with Errors for Generalized Set-Valued Strongly Accretive Mapping in Banach Spaces

Introduction Variational inequalities are the most interestingand important mathematical problems and have beenstudied intensively in the past years since they havewide applications in mechanics, physics, optimizationand control, nonlinear programming, ec…     

About process times in some deepwater formation events in the Mediterranean Sea

Experimental data gathered on some Mediterranean deepwater formation sites have been analysed in order to check the Chapman (Ch), Visbeck and Maxworthy scale laws, their final mixing water depth and process times estimates. All the analysed sites have a high probability to be “internally constrained” so that the baroclinic Rossby radius is the dominant horizontal length scale and the final chimney depth is independent of the rate of rotation as indicated by Visbeck and Maxworthy criteria; the Eady instability times are generally very fast (3/f) but the least final mixing process times are too long compared with the meteorological forcing ones. It is attempted here to identify some new criteria to give some insight on the processes time scale, which is still an open problem. Conclusions about the Rhodes gyre appear questionable, because the experimental data appear inconsistent with any theoretical criterion.     

言语失误的成因及其对英语口语教学的启示

言语失误是一种产生于口语交际过程的必然的语言现象,其形成受到认知因素、心理因素,及社会因素的影响。本文在前人研究成果的基础上,分析了言语失误的成因及其对英语口语教学的启示。     

平台导航误差对导弹中末制导交班影响分析

针对多平台导航误差对导弹中末制导过程影响的问题,基于将多平台导航误差传递到目标和导弹位置误差的思想,提出了导航误差传递模型,并采用中末制导交班成功概率模型量化多平台导航误差对导弹中末制导交班过程的影响。仿真结果表明,一定范围的导航误差对导弹中末制导交班成功概率影响较小,但随着导航误差的增大,中末制导交班成功概率迅速减小。     

随机场数值分析的伽辽金法

本文建立了随机场数值分析的摄动伽辽金法的基本列式，讨论了解的合理性并给出解的误差界。     

Bézier曲面拼接误差影响因素

通过mxn次Bézier曲面和n次Bézier曲线G^1、G^2连续的条件，分析了Bézier曲面在拼接边界上控制顶点矢量末端的偏差对位置误差、相切误差和曲率误差的影响因素。根据分析结果提出了减小曲面拼接误差的方法，并以汽车发动机罩曲面拼接为例，验证了分析的正确性。     

水尺计量误差分析与解决办法

为减少和控制水尺计量误差,应采取各种措施得出正确的海水密度、水尺,压载水量。本文分析评估各种误差以得到准确货量,并采用合适的数学方法,可有效提高尺寸计量精度。     

自动机轴线成夹角的双联装舰炮火控解相遇问题研究

针对双联装舰炮自动机轴线夹角带来的火控解相遇问题,建立了自动机轴线夹角引起的系统误差计算模型;提出了一种提前点计算的修正方法,通过仿真计算和分析,验证了提前点修正的有效性并讨论了影响修正效果的因素。