Probabilistic assessment of fleet-level noise impacts of projected technology improvements

Demand projections for civil aviation have forecast increases in operations in future decades. Increases in demand are beneficial to the growth and advancement of the aviation industry, but also come with the threat of significant increase in environmental impacts. In response, the industry is focusing on programs to develop technologies for reductions in fuel burn, NO_x emissions, and noise. While aircraft-level impacts are an obvious metric of success, it is difficult to make informed robust technology investment decisions with respect to noise without understanding the fleet-level impacts. Fleet-level predictions of noise for technology explorations are especially complicated because it is computationally expensive, highly combinatorial, and airport-specific. Recently, rapid automated airport noise models have been developed, which can be simulated using Design of Experiments (DOE). The results of these simulations are used to generate surrogate models for airport noise contour area, which can be summed to yield a fleet-level impact. These models make use of simplifying assumptions to provide estimates of airport-level noise that are substantially cheaper to compute. They can be used to perform parametric trade-off analyses in conjunction with the equivalency assumption. Equivalency asserts that environmental impacts of a technology infused aircraft can be represented by scaled operations of the baseline aircraft in the same class. This simple assumption allows for the modeling of technology and market penetration factors under the same units: operations. This research uses surrogate models in conjunction with the equivalency assumption to examine two potential technology scenarios in a target forecast year, simulating technology and market performance factors to identify vehicle classes that could have the greatest impact in reducing contour area. Results show that technology and market performance of future notional Small Single Aisle and Large Single Aisle vehicle aircraft have the highest positive correlations with potential reductions in contour area.     

Stock market comovements around the Global Financial Crisis: Evidence from the UK,BRICS and MIST markets

This paper analyses stock market co-movements around recent crises and explores the international portfolio diversification benefits available for UK investors holding a portfolio in the BRICS and MIST emerging markets. The application of conventional and regime-switch cointegration techniques suggests an absence of diversification benefits. Further evidence from application of a multivariate time-varying asymmetric model (i.e. AG-DCC) suggests that conditional correlation among the stock markets exhibits higher dependency when it is driven by negative shocks to the market. The asymmetric causality test provides supporting evidence of the decoupling hypothesis. The results indicate that the Chinese stock market is the most attractive option for the UK investor.     

Modelling interactions among the housing market and key US sectors

This study evaluates the dynamic interactions among the housing market and ten key US sectors including: consumer discretionary, consumer staples, energy, financials, industrial, technology, health care, materials, utility and telecommunications. Long-run results indicate that the housing market is integrated with each of the ten sector and that the degree of convergence has increased over time and especially after the onset of the most recent housing crisis. Moreover, the housing market contributes most heavily to the common trends indicating that the housing market is the ‘leader’ market that drives each sector towards the long-run equilibrium relationships. Short-run analyses indicate causal linkages emanating from the housing market to each sector with reciprocal feedback. Finally, impulse response function analysis reveal that shocks from each sector affect the housing market but that shocks from the housing market have a (comparatively) more profound and persistent impact on each sector.     

季节性旅游的地方响应研究——以广交会展馆内外翻译为例

广交会是目前我国最大的综合性国际贸易盛会,每年都吸引了大量国内外客商到场参加。本文以广交会场馆内外的翻译工作者对广交会的响应情况作为研究重点,通过对广交会翻译的问卷调查及访谈,分析和研究广交会翻译对于广交会这一季节性旅游的地方响应。响应的人群主要为学生及社会工作者,其响应的方式可分为学校组织与个人自发响应。翻译工作者在广交会的这种季节性的旅游效应下不仅获得了学习和锻炼的机会,而且可以赚取更多的兼职收入,他们都对广交会的工作有较高的评价。     

曲面响应法预测砂浆性能的试验研究

本试验以砂浆性能为研究对象,采用Box-Behnken的中心组合实验设计及响应面分析方法对腻子粘结强度进行预测研究。试验选用三因素三水平的响应曲面分析法,建立了粘结强度的二次多项数学模型,并以粘结强度为响应值作响应面和等高线,考察了水粉比、灰粉比和胶粉比对粘结强度的影响,并根据实际选择响应曲面方程,利用最小二乘法估计相应的系数,剔除最不显著因素,建立最终的数学方程。结果表明:该预测模型能很好地描述粘结强度与水粉比、灰粉比和胶粉比之间的关系,可以对腻子粘结强度进行分析和预测,为砂浆性能研究提供一种新方法。     

Dual sourcing of a newsvendor with exponential utility of profit

Dual sourcing strategies supplement inflexible, low-cost country sourcing with quick response manufacturing. Due to short product life cycles, combined with uncertain demand, dual sourcing strategies are very common in several industries, in particular in the sporting goods or fashion industries.Even though scholars have given some attention to the analysis of dual sourcing strategies, the importance of the decision-maker’s risk preferences has not been covered yet.In this paper we analyse dual sourcing strategies using an extended single-product newsvendor model with two order points. Different risk preferences will be modelled using an exponential utility function. Within realistic parameter ranges, the optimal order quantities can only be numerically computed. The findings of this paper show that dual sourcing strategies are always preferable to an exclusive offshore approach, as long as the onshore ordering costs are smaller than the selling price of the considered product. The more risk-averse the decision-maker, the smaller the offshore order quantity will be.     

The response of U.S. natural gas futures and spot prices to storage change surprises: Fundamental information and the effect of escalating physical gas production

We study the behavior of U.S. natural gas futures and spot prices on and around the weekly announcements by the U.S. Energy Information Administration of the amount of natural gas in storage. We identify an inverse empirical relation between changes in futures prices and surprises in the change in natural gas in storage and that this relation is not driven by the absolute size of the surprise. The evidence also indicates prices react first in the futures market for natural gas with that information then flowing to the spot market. Post 2005, corresponding to a period of significant increases in the production of natural gas in the United States, the response of prices to storage surprises was larger in absolute value. No evidence is found of economically meaningful reactions to the surprise other than on the date the storage news is released. The results demonstrate the importance of fundamental information in the formation of natural gas prices.     

Alternative Approaches to Multilevel Modelling of Survey Non‐Contact and Refusal

We review three alternative approaches to modelling survey non‐contact and refusal: multinomial, sequential, and sample selection (bivariate probit) models. We then propose a multilevel extension of the sample selection model to allow for both interviewer effects and dependency between non‐contact and refusal rates at the household and interviewer level. All methods are applied and compared in an analysis of household non‐response in the United Kingdom, using a data set with unusually rich information on both respondents and non‐respondents from six major surveys. After controlling for household characteristics, there is little evidence of residual correlation between the unobserved characteristics affecting non‐contact and refusal propensities at either the household or the interviewer level. We also find that the estimated coefficients of the multinomial and sequential models are surprisingly similar, which further investigation via a simulation study suggests is due to non‐contact and refusal having largely different predictors.     

A contingent plan for disaster response

Natural and man-made disasters imply a great deal of uncertainty in terms of potential damage, though it is certain that there would be a huge spike in the demand for relief supplies causing shortages and/or delays in providing aid. Ruptures in the infrastructure (roads, utility, and communication lines) cause additional delays due to repairs. Therefore, the relief providers need to work in collaboration with retailers, and infrastructure service providers for improving responsiveness. The relief providers (government and non government) rely on acquiring and delivering supplies in real time because such actions accompany little risk of resource underutilization, though the cost of real time acquisitions can be high. In contrast, a proactive response, while minimizing acquisition cost, can be very ineffective if demand surges are high. We study a hybrid of reactive and proactive approaches, where the reactive response is contingent upon the disaster intensity exceeding a certain threshold. We show how the threshold value may impact capacity acquisitions and prices and establish the optimality of contingent response. Further, we establish how an infrastructure contract may help reducing the social cost of disaster.     

控制权转移的市场反应——基于私有收益视角

控制权转移可以引起公司股票价格以及股东财富的变化,国内外学者对此进行了大量研究,但鲜有结合控制权私有收益的分析。本文从私有收益视角出发,从事件期的累积超常收益、超常换手率、内幕交易指标、长期购买持有收益以及国有和民营买家超常收益的比较等方面进行了实证研究,结果表明:上市公司的控制权转移在很大程度上是新控股股东通过内幕交易获取私有收益的行为,并未真正为股东创造价值。