Wildlife strikes to civil helicopters in the US, 1990–2011

This paper examines wildlife strikes with civil helicopters within the US. Month and time of day, location, and other factors influenced the frequency of wildlife strikes with civil helicopters. Wildlife strikes occurred most frequently when the aircraft were traveling en route or engaged in terrain flight. Birds accounted for over 97% of the wildlife strikes where the animal was identified.     

论建立长效的农业公共灾害社会保险法律制度--由"禽流感"公共危机引起的思考

现代社会类似于禽流感的公共灾害往往不期而至,给国家和人民带来重大损失。但是国家给予灾害受损户的公共补偿则因为国家财政的限制而很有限,使得这种补偿不完全;商业性质的财产保险又因为这种灾害具有很大的不确定性而惰于保险。基于此,本提出我国应当建立一种融国家公共补偿责任和商业财产保险机制于一体的农业公共灾害社会保险制度。     

空袭目标威胁排序模型研究

对空中来袭目标进行威胁排序是防空作战的主要依据。由于影响空中来袭目标威胁度的因素很多,而且防空任务非常紧迫,为了提高评估效果的实时性,文中以单舰防空为例,选取了几个主要参数来描述来袭目标的威胁度。为了消除不同物理量纲对评估结果的影响,采用效益型函数和成本型函数对各威胁指标因素进行规范化处理,用相邻比较法来确定指标权重,并结合实例进行分析,得到的结果与专家群体评议后的结果完全一致。     

Mitigative and adaptive investments for natural disasters and labor strikes in a seaport–dry port inland logistics network

ABSTRACT

Inland distribution is a crucial link between ocean shipping and terminal consumers. However, such a distribution system is vulnerable to disturbance caused by natural disasters and labor strikes. Pre-event investments, specifically mitigative and adaptive investments, could alleviate the adverse consequences of a disturbance to mitigate the possibility of event occurrence and reduce damage after event occurrence, respectively. This study investigates an inland distribution network that comprises one seaport and one major dry port. Moreover, this research discusses the two existing management models in the network, namely, centralized and decentralized systems. We analyze the optimal investment level when coping with natural disasters and labor strikes and compare the results under different cases. Results show that decentralization will increase the total expected cost, while cooperation is always beneficial in terms of pre-event investment. However, an appropriate cost-sharing plan is required to make the cooperation feasible for a seaport and dry port.     

Edge effect of busy high traffic roads on the nest site selection of birds inside the city area: Guild response

The rapid development of road infrastructure is inevitable with increasing world human population and rise in the number of vehicles on the roads is going to be an increasing threat to native habitat of many wildlife populations around the world. The present work examines the edge effect of high traffic roads on nest site selection of birds in Udaipur city, Rajasthan (India). A total of 112 nesting site of 14 bird species (among six guilds), was recorded during the study. All six guilds (i.e., carnivore, omnivore, granivore, nectivore, frugivore and insectivore) were sharing similar kind of habitat with fine scale differences (P < 0.0001). The PCA revealed that trees with suitable GBH, canopy and height were supporting birds’ nesting diversity, but the buildings were supporting the highest number of nesting. Different guilds showed different preference to different variables. Spatial heterogeneity, less predation, optimal feeding ground and higher number of advertising and display boards of shops at roadside buildings might be crucial factors for birds’ nesting in this highly disturbed area.     

Modeling the cost of bird strikes to US civil aircraft

The objective of our analysis is to develop a model of damage costs that arise from collisions between aircraft and birds, based on data drawn from the Federal Aviation Administration National Wildlife Strike Database (NWSD). We develop a two-part model, composed of two separate statistical models, that accounts for the effects of aircraft mass category, engine type, component of the aircraft struck, and the size and number of birds struck. Our results indicate the size of bird, number of birds, and engine ingestions are the largest determinants of strike-related costs. More generally, our result is a model that provides a better understanding of the determinants of damage costs and that can be used to interpolate the substantial amount of missing data on damage costs that currently exists within the NWSD. A more complete accounting of damage costs will allow a better understanding of how damage costs vary geographically and temporally and, thus, enable more efficient allocation of management resources across airports and seasons.     

How tube strikes affect macroscopic and link travel times in London

Abstract

The purpose of this study was to investigate the impact of the five strikes on the London Underground (metro) rail system, which occurred in 2009 and 2010, on macroscopic and road link travel times. A consequence of these strikes was an increase in road traffic flows above usual levels. This provides an opportunity to observe the operation of the road network under unusually high flows. The first objective involves the examination of strike effects on inbound (IT) and outbound traffic (OT) within central, inner and outer London. Travel time data obtained from automatic number plate recognition cameras are used within the first part of the analysis. The second more detailed objective was to investigate in spatio-temporal effects on travel times on five road links. Correlation analyses and general linear models are developed using both traffic flow and travel time data. According to the results of the study, the morning IT had approximately twice as much delay as the OT. Central London experienced the highest delays, followed by inner and outer London. As would be expected, the unique full-day strike in 2009 yielded the worst impact on the network with the highest percentage increase in total travel time (60%) occurring during the morning peak in the IT in inner London. The results from the link-level analysis showed statistical significance amongst the examined links indicating heterogeneous effects from one link to another. It was also found that travel time changes may be more effectively captured through time-of-day terms compared to hourly traffic flows.