基于动态冲击试验的通勤类飞机座椅符合性验证技术

国产某型民用通勤类飞机为了取得欧洲航空安全局(EASA)型号合格证,机上座椅需进行设计更改并补充进行应急着陆情况下的动态要求符合性验证.通过对适航条款及相应标准的解读,研究了基于动态试验的航空座椅动态要求适航验证技术,其主要包括座椅动态性能基本要求、试验构型及工况筛选、试验规划、合格判据和试验结果分析等内容.结果表明,该型机旅客座椅满足适航规章对座椅的动态性能要求.该项旅客座椅动态性能试验的成功为型号取得EASA型号合格证奠定了良好的基础,该型飞机也即将成为第一个取得欧洲型号合格证的国产飞机.     

Market impact: a systematic study of the high frequency options market

This paper deals with a fundamental subject that has seldom been addressed in recent years, that of market impact in the options market. Our analysis is based on a proprietary database of metaorders—large orders that are split into smaller pieces before being sent to the market—on one of the main Asian markets. In line with our previous work on the equity market [Said, E., Bel Hadj Ayed, A., Husson, A. and Abergel, F., Market impact: A systematic study of limit orders. Mark. Microstruct. Liq., 2018, 3(3&4), 1850008.], we propose an algorithmic approach to identify metaorders, based on some implied volatility parameters, the at the money forward volatility and at the money forward skew. In both cases, we obtain results similar to the now well-understood equity market: Square-Root Law, Fair Pricing Condition and Market Impact Dynamics.     

Periodic strategies in optimal execution with multiplicative price impact

We study the optimal execution problem with multiplicative price impact in algorithmic trading, when an agent holds an initial position of shares of a financial asset. The interselling decision times are modeled by the arrival times of a Poisson process. The criterion to be optimized consists in maximizing the expected net present value of the gains of the agent, and it is proved that an optimal strategy has a barrier form, depending only on the number of shares left and the level of the asset price.     

The equity impacts of bus rapid transit: A review of the evidence and implications for sustainable transport

The paper offers an analysis of empirical evidence on the equity impacts of operational Bus Rapid Transit (BRT) systems in the Global South. The focus is on vertical equity, i.e. whether BRT systems achieve progressive benefits for poorer segments of the population. Findings from Africa, Asia, and Latin America all suggest that BRT does offer significant benefits to low-income groups, in terms of travel time and cost savings, access enhancement, and safety and health benefits. However benefits are often skewed toward medium-income users and thus less progressive than they might be. Two primary reasons for this are insufficient spatial coverage and inappropriate fare policies. While many features of BRT potentially allow it to deliver pro-poor outcomes, such outcomes only materialize if BRT implementers pay specific and sustained attention to equity. The paper identifies key issues that need to be addressed to steer BRT implementation toward more socially sustainable outcomes—including better integration with other transit, paratransit, and nonmotorized transport services, and with the housing sector.     

The Impact of the Implementation of Technology Education on In-Service Teacher Education in South Africa (Impact of Technology Education in the RSA)

In this article the impact of technology education, as a new learning area (subject) in the curriculum, on in-service teacher education in South Africa is described in order to ascertain the extent of the impact. The research on which this article is based draws on a variety of experiences and observations in the field at grassroots level (in particular an outreach project in rural communities). The envisaged impact of technology education on South African schools, communities, teacher educators and teachers, the range of in-service teacher education that is required, and the impacts in urban and rural areas are discussed. Finally a number of concluding remarks are made about the extent of the impact of the inclusion of technology education in the new National Curriculum Statement and whether the situation has changed since the implementation of a pilot technology education project in 1998. This revised version was published online in July 2006 with corrections to the Cover Date.     

刍议馆长的非权力影响力

馆长对图书馆的事业发展至关重要.探讨了图书馆馆长治理图书馆的非权力影响力,即指依靠馆长自身的素养,即德、才、仁、情等因素,使馆长更具向心力、凝聚力,从而推动图书馆工作的有效地运作,促进图书馆事业的蓬勃发展.     

Liquidating large security positions strategically: a pragmatic and empirical approach

This article investigates static liquidation strategies for large security positions in illiquid markets. Under the assumption that the liquidation horizon is given exogenously, a discretionary liquidity trader solves for the optimal sales trajectory so as to maximize an objective function that considers the expected liquidation revenues and their standard deviation. Although existing literature tends to focus on theoretical aspects with the intention of deriving closed-form solutions for special types of market impact functions, this article considers a framework that is able to capture important empirical phenomena in the stock market, such as the intraday U-shaped pattern of price impact and the resiliency of the order book. The new model is very flexible since it allows for liquidation intervals of varying length and foregoes the assumption of constant speed of trading. Examples with real-world order book data demonstrate how the setup can be implemented numerically and provide deeper insight into relevant properties of the model.     

Assessing the growth-inducing impact of the Appalachian Development Highway System in southern Ohio: Did policy promote change?

The concept of “inducing growth” is typically considered an adverse consequence of a project on the land use system. In certain instances, however, the desire to induce growth and foster land use change is a focus of land use policy. Such is the example of the Appalachian Highway Development System (AHDS) program initiated by the Appalachian Regional Commission (ARC) during the late 1960s. With the goal of providing highway infrastructure to improve assess to a geographically isolated and historically impoverished region, the ADHS has added nearly 3000 miles of highway to the Appalachian landscape. The degree to which highway investment has contributed to regional growth remains a controversial point and tractable methods to quickly assess landscape change given a project of this magnitude are elusive. In this paper a portion of the AHDS trending through southern Ohio is examined using data acquired from the Landsat series of satellites. Beginning with a pre-highway condition in 1976, a 26 year time horizon, concluding in 2002, was analyzed based on a post-classification change detection methodology. Results of this investigation revealed slight, yet significant, levels of urban expansion within a 10 km corridor along the path of AHDS Corridor D/State Route 32. Beyond this buffer zone the land use system evidenced more stability, suggesting that as distance increased from Corridor D/State Route 32, reduced accessibility also reduced the attractiveness of land for urban uses. Relating these results back to the infrastructure investment policies of the ARC demonstrates that growth did result from the construction of Corridor D and supports previous findings that land development based on highway construction is extremely time-sensitive.     

绿色壁垒对我国纺织服装业的影响研究

为了避免绿色壁垒对我国纺织服装业造成更大的经济损失,保持行业的持续健康发展,本文分析了绿色壁垒对我国纺织服装业带来的积极影响和消极影响,进而提出应对绿色壁垒消极影响的措施。     

竖向地震力的冲量计算法

一般认为地震在地表引起的破坏主要是S波的水平震动,很少考虑地震竖向力的作用。单从考虑地震水平力的作用是不易全面反映震害特征的。提出用冲量法来研究计算竖向地震力,通过对最大竖向地震力分布研究,探讨竖向地震力对建筑物的影响与破坏,为进一步提高工程抗震设计水平提供理论依据。