Additive manufacturing’s impact and future in the aviation industry

Additive manufacturing (AM) is a technology that has the potential to change the future of aviation supply chains and how the aviation industry designs, manufactures and repairs aircraft in the future. The purpose of this research was to shed light on the current and future states of AM in the aviation industry. From focus groups with nearly 50 aviation professionals from aircraft original equipment manufacturers (OEMs), suppliers, maintenance repair overhaul providers, and AM service providers and AM production firms, we found that the adoption of AM will be triggered by the accumulated AM experience in the industry, the stability of AM technology and the development of new aircraft generations. For AM to be finally adopted, aircraft OEMs must actively manage several success factors and monitor numerous control factors identified and discussed in this research. AM will supplement traditional manufacturing processes at least in the short to midterm, likely grow exponentially and offer benefits for players in the aviation supply chain.     

Cost-Effectiveness of Risk-Reduction Measures from a National Viewpoint: A Case Study of the Angra Nuclear Plant in Brazil

In this paper a systemic or national approach to cost-effectiveness analysis of risk-reduction measures is reviewed, and its advantages and limitations are discussed. The method is applied to the problem of the cost-effectiveness of increasing the Angra 3 NPP containment wall thickness from the present 60 cm to 180 cm thick in order to prevent damage to the reactor core in case of a direct commercial aircraft crash on it. It is concluded that this measure is not cost-effective if the referred approach is considered.     

信息共享与协同合作对两级供应链的收益影响

研究了由一个供应商和一个制造商组成的按订单生产的2级供应链系统。用数学的方法分析了信息共享与协同合作在供应商与制造商的不同策略组合下对该供应链收益的影响。通过具体算例对各种策略进行实验分析,并根据实验结果对信息共享与协调合作在各种策略中,对供应链各成员及整个供应链的收益影响进行评估。结果表明,供应链从传统模式转向完全信息共享与协同合作模式,制造商的订货次数、供应商的调整准备次数以及运输次数都大大减少,系统总成本降低了22.76%。信息共享能够降低成本,但主要收益来自系统的协调决策,而且这些收益并不是均匀地在各成员间进行分配的,而是随策略的不同而不同。     

Securing Passenger Aircraft from the Threat of Man‐Portable Air Defense Systems (MANPADS)

In this article, we develop a model for the expected maximum hit probability of an attack on a commercial aircraft using MANPADS, as a function of the (random) location of the attacker. We also explore the sensitivity of the expected maximum hit probability to the parameters of the model, including both attacker parameters (such as weapon characteristics) and defender parameters (such as the size of the secure region around the airport). We conclude that having a large secure region around an airport offers some protection against MANPADS, and that installing onboard countermeasures reduces the success probability of a MANPADS attack.     

具公平关切零售商的闭环供应链差别定价策略研究

将零售商公平关切行为倾向引入到闭环供应链的差别定价策略中,构建了制造商考虑和不考虑零售商公平关切行为两种差别定价决策模型,运用博弈理论对两种模型进行分析求解。研究表明闭环供应链成员的差别定价策略、收益以及废旧产品回收量均受到零售商公平关切行为的影响;制造商应考虑零售商的公平关切行为倾向做出决策,这对制造商自身是有利的,同时也增加了对废旧产品的回收量,有利于资源回收再利用;同时还发现公平关切行为倾向是零售商获取闭环供应链系统利润分配的一种有效手段,同时这种公平关切行为倾向会造成闭环供应链系统效率的损失。     

A study of supply chain integration in the aeronautics sector

Competitive pressure, high development costs, long lead times, rapidly changing technologies and the risks inherent in projects combined with the delays seen in the latest aircraft models (with the rise in costs that these have entailed) highlight the need to reorganise the supply chain in the aeronautics sector paying special attention to an improvement in inter- and intra-organisational integration. The aim of this study is to analyse the situation of supply chain integration (SCI) in the aeronautics sector using three dimensions (information integration, coordination and resource sharing and organisational relationship linkage), considering both internal integration and external integration with customers and suppliers. A group of first-tier supplier experts analyse the dimensions and assess the degree to which the factors that define SCI have been achieved. The results enable strengths and weaknesses to be determined and indicate possible improvements to the situation that is detected with clear managerial implications.     

The decision to add a second system producer

Typically in the United States only one contractor (the developer or first producer) makes a weapon system because it is too expensive or for some other reason infeasible to develop a second source. Congress and higher headquarters are constantly challenging the Armed Services to add other sources who can competitively make their systems. This paper describes a method of analyzing this complex problem which often has very large monetary and other significant impacts. Procedures and a case study are presented which consider cost and other criteria which might be used to make the second source decision.     

会计诚信危机治理机制研究

会计诚信危机作为一种经济现象,也遵循供求规律,信息不对称的客观存在是其产生的经济根源,法律等外在制度约束和道德等内在制度约束的缺失及不健全,使经营者道德风险和逆向选择变为现实.会计人员是否遵守职业操守、讲求诚信是利益驱动下重复博弈的结果.建立会计诚信的制度规范,优化会计诚信环境,是治理诚信危机的根本措施.     

Supply Chain Integration,Product Modularity,and Market Valuation: Evidence from the Solar Energy Industry

Supply chain integration is increasingly seen as a method to obtain flexibility and, consequently, to provide competitive advantage for firms within a supply chain. Product modularity, either in concert with or independent of such integration, can also produce flexibility for firms within a supply chain. In this proof‐of‐concept research, we explore whether the supply chain network affects each constituent firm's market valuation and how decisions regarding the level of supply chain integration and the usage of product modularity are associated with the value of the supply chain. We develop a method to identify and measure the supply chain's effect on each constituent firm's market valuation. Results indicate that greater integration is associated with a higher supply chain valuation, whereas increasing aggregated product modularity across the supply chain relates to a lower supply chain value. However, when combined, the interaction of aggregated product modularity and supply chain integration is positively associated with the supply chain's valuation.     

The IAEA, the NPT and the VIII NPT Review Conference

Since the end of World War II the international community has been building, step by step and with many difficulties, the nuclear weapon non-proliferation regime. The purpose of this regime is the prevention of the proliferation of this type of weaponry and to achieve, as one of their final goal, the complete elimination of all nuclear weapons and the closure of all nuclear weapon production facilities or the conversion of these facilities for their exclusively use with peaceful purposes in the future. Despite all efforts made by the majority of the international community, the world still is far from achieving this important objective. This article offers to the international community a group of actions for the strengthening of the nuclear weapon non-proliferation regime and for the beginning of multilateral negotiations towards nuclear disarmament.     

Estimating the Return to Schooling: Progress on Some Persistent Econometric Problems

This paper reviews a set of recent studies that have attempted to measure the causal effect of education on labor market earnings by using institutional features of the supply side of the education system as exogenous determinants of schooling outcomes. A simple theoretical model that highlights the role of comparative advantage in the optimal schooling decision is presented and used to motivate an extended discussion of econometric issues, including the properties of ordinary least squares and instrumental variables estimators. A review of studies that have used compulsory schooling laws, differences in the accessibility of schools, and similar features as instrumental variables for completed education, reveals that the resulting estimates of the return to schooling are typically as big or bigger than the corresponding ordinary least squares estimates. One interpretation of this finding is that marginal returns to education among the low‐education subgroups typically affected by supply‐side innovations tend to be relatively high, reflecting their high marginal costs of schooling, rather than low ability that limits their return to education.     

A Grasp for Aircraft Routing in Response to Groundings and Delays

This paper presents a greedy randomized adaptive search procedure (GRASP) to reconstruct aircraft routings in response to groundings and delays experienced over the course of the day. Whenever the schedule is disrupted, the immediate objective of the airlines is to minimize the cost of reassigning aircraft to flights taking into account available resources and other system constraints. Associated costs are measured by flight delays and cancellations.In the procedure, the neighbors of an incumbent solution are generated and evaluated, and the most desirable are placed on a restricted candidate list. One is selected randomly and becomes the incumbent. The heuristic is polynomial with respect to the number of flights and aircraft. This is reflected in our computational experience with data provided by Continental Airlines. Empirical results demonstrate the ability of the GRASP to quickly explore a wide range of scenarios and, in most cases, to produce an optimal or near-optimal solution.     

Ecological Risk Assessment Framework for Low-Altitude Aircraft Overflights: II. Estimating Effects on Wildlife

An ecological risk assessment framework for aircraft overflights has been developed, with special emphasis on military applications. This article presents the analysis of effects and risk characterization phases; the problem formulation and exposure analysis phases are presented in a companion article. The framework addresses the effects of sound, visual stressors, and collision on the abundance and production of wildlife populations. Profiles of effects, including thresholds, are highlighted for two groups of endpoint species: ungulates (hoofed mammals) and pinnipeds (seals, sea lions, walruses). Several factors complicate the analysis of effects for aircraft overflights. Studies of the effects of aircraft overflights previously have not been associated with a quantitative assessment framework; therefore no consistent relations between exposure and population-level response have been developed. Information on behavioral effects of overflights by military aircraft (or component stressors) on most wildlife species is sparse. Moreover, models that relate behavioral changes to abundance or reproduction, and those that relate behavioral or hearing effects thresholds from one population to another are generally not available. The aggregation of sound frequencies, durations, and the view of the aircraft into the single exposure metric of slant distance is not always the best predictor of effects, but effects associated with more specific exposure metrics (e.g., narrow sound spectra) may not be easily determined or added. The weight of evidence and uncertainty analyses of the risk characterization for overflights are also discussed in this article.     

A Heuristic Risk Assessment Technique for Birdstrike Management at Airports

Collisions between birds and aircraft (birdstrikes) have caused the loss of at least 88 aircraft and 243 lives in world civil aviation. Conservative estimates suggest that more routine damage and delays following birdstrikes cost the industry and its insurers US$1.2-1.5 billion per year. The majority of strikes happen close to airports and most countries have regulations that require airport managers to control the birdstrike risk on their property. Birdstrike prevention has, however, lagged behind other aspects of flight safety in the development and implementation of risk assessment protocols, possibly because of the inherent difficulty in quantifying the variability in the populations and behavior of the various bird species involved. This article presents a technique that uses both national and airport-specific data to evaluate risk by creating a simple probability-times-severity matrix. It uses the frequency of strikes reported for different bird species at a given airport over the preceding five years as a measure of strike probability, and the proportion of strikes with each species that result in damage to aircraft, in the national birdstrike database, as a measure of likely severity. Action thresholds for risk levels for particular bird species are then defined, above which the airport should take action to reduce the risk further. The assessment is designed for airports where the reporting and collation of birdstrike events is reasonably consistent over time and where a bird hazard management program of some sort is already in place. This risk assessment is designed to measure risk to the airport as a business rather than risk to the traveling passenger individually. It therefore takes no account of aircraft movement rate in the calculations and is aimed at minimizing the number of damaging incidents rather than concentrating on catastrophic events. Once set up at an airport, the technique is simple to implement for nonexperts, and it allows managers to focus bird control resources on the species causing the greatest risk, hence maximizing the return on investment. This protocol is now being successfully used at major airports in the United Kingdom and elsewhere in the world.     

A systematic approach for supply chain conflict detection with a hierarchical Petri Net extension

Coordinating and managing distributed entities in a supply chain is a challenging task due, in part, to conflicts present in such systems. If not handled effectively, the conflict can degrade the performance of the system as a whole due to the fact that each individual entity may be working towards goals that sub-optimize the integrated system. Therefore, the ability to discover conflicts would be a valuable asset, particularly if the discovery occurred proactively. This paper presents a methodology, extending the concept of basic Petri Nets, to discover supply chain conflict before they occur and cause detrimental effects to system performance. The approach involves linking hierarchical levels of the supply chain system and detecting conflicts occurring when the single entities, each optimized for it own operations, are combined together in a supply chain. These conflicts are not obvious or intuitive in examining the single entities of the supply chain, but when integrated the conflicts are discovered by the methodology. We applied the proposed methodology on a real-world supply chain to illustrate the validity of the tool. Although, further research is needed to fully explore this method of conflict detection, we believe that this research does indeed provide some much needed insight into the daunting task of conflict discovery and therefore proactive handling of these potentially negative occurrences in the supply chain.     

Decision support for lead time and demand variability reduction

Companies undertaking operations improvement in supply chains face many alternatives. This work seeks to assist practitioners to prioritize improvement actions by developing analytical expressions for the marginal values of three parameters – (i) lead time mean, (ii) lead time variance, and (iii) demand variance – which measure the marginal cost of an incremental change in a parameter. The relative effectiveness of reducing lead time mean versus lead time variance is captured by the ratio of the marginal value of lead time mean to that of lead time variance. We find that this ratio strongly depends on whether the lead time mean and variance are independent or correlated. We illustrate the application of the results with a numerical example from an industrial setting. The insights can help managers determine the optimal investment decision to modify demand and supply characteristics in their supply chain, e.g., by switching suppliers, factory layout, or investing in information systems.     

加征关税下的跨国供应链决策及补贴策略研究

本文讨论加征关税视角下的供应链决策及补贴策略问题。基于本国制造商、分销商与国外进口零售商所组成的三级跨国供应链,分别讨论了政府不补贴、政府补贴下的供应链决策,研究加征关税和补贴对供应链的影响,并分析保持产品销售价不变补贴策略(I)、保持制造商利润不变补贴策略(II)及社会福利最大化补贴策略(III)的效应。结果表明,加征关税导致产品销售价增大和本国企业批发价、供应链各企业利润及社会福利的降低,但政府提高补贴使得产品销售价减小和供应链各企业利润增大,而社会福利随着补贴的增大先增大后减小。随着加征关税税率及补贴的增大,供应链更多地表现为补贴的作用,补贴能有效减小加征关税的影响。在较低关税税率下,策略(III)激励产品出口作用显著,但政府补贴支出过高;策略(II)相较策略(I)激励效果更显著,但补贴支出更大。在较高关税税率下,策略(II)更能激励制造商出口,策略(I)以较低的补贴支出激励制造商出口,更有利于维持国际市场稳定。     

Ecological Risk Assessment Framework for Low-Altitude Aircraft Overflights: I. Planning the Analysis and Estimating Exposure

An ecological risk assessment framework for low-altitude aircraft overflights was developed, with special emphasis on military applications. The problem formulation and exposure analysis phases are presented in this article; an analysis of effects and risk characterization is presented in a companion article. The intent of this article is threefold: (1) to illustrate the development of a generic framework for the ecological risk assessment of an activity, (2) to show how the U.S. Environmental Protection Agency's ecological risk assessment paradigm can be applied to an activity other than the release of a chemical, and (3) to provide guidance for the assessment of ecological risks from low-altitude aircraft overflights. The key stressor for low-altitude aircraft overflights is usually sound, although visual and physical (collision) stressors may also be significant. Susceptible and regulated wildlife populations are the major assessment endpoint entities, although plant communities may be impacted by takeoffs and landings. The exposure analysis utilizes measurements of wildlife locations, measurements of sound levels at the wildlife locations, measurements of slant distances from aircraft to wildlife, models that extrapolate sound from the source aircraft to the ground, and bird-strike probability models. Some of the challenges to conducting a risk assessment for aircraft overflights include prioritizing potential stressors and endpoints, choosing exposure metrics that relate to wildlife responses, obtaining good estimates of sound or distance, and estimating wildlife locations.     

Green supply chain performance measurement using the analytic hierarchy process: a comparative analysis of manufacturing organisations

The main purpose of this research is to develop and deploy an analytical framework for measuring the environmental performance of manufacturing supply chains. This work's theoretical bases combine and reconcile three major areas: supply chain management, environmental management and performance measurement. Researchers have suggested many empirical criteria for green supply chain (GSC) performance measurement and proposed both qualitative and quantitative frameworks. However, these are mainly operational in nature and specific to the focal company. This research develops an innovative GSC performance measurement framework by integrating supply chain processes (supplier relationship management, internal supply chain management and customer relationship management) with organisational decision levels (both strategic and operational). Environmental planning, environmental auditing, management commitment, environmental performance, economic performance and operational performance are the key level constructs. The proposed framework is then applied to three selected manufacturing organisations in the UK. Their GSC performance is measured and benchmarked by using the analytic hierarchy process (AHP), a multiple-attribute decision-making technique. The AHP-based framework offers an effective way to measure and benchmark organisations’ GSC performance. This study has both theoretical and practical implications. Theoretically it contributes holistic constructs for designing a GSC and managing it for sustainability; and practically it helps industry practitioners to measure and improve the environmental performance of their supply chain.     

Union Power in a Welfare State

Abstract. Most West European countries have suffered from stagflation for many years. Mainstream economics has debated the question in particular in terms of the demand and supply of goods, labour and capital. But in recent contributions a new element has been introduced: the institutional structure of the economy as a source of imbalances. In this article we focus on the institutions of the labour market. For more than a century West European unions have been struggling to transform market economies into a more efficient and just order. Moral persuasion, strikes, and revolutionary threats were their main weapons. After the Second World War governments yielded to the pressure by building up, together with the unions, a welfare state. During the sixties however, the struggle was renewed, although the governments continued to improve the social security system and maintained their responsibility for full employment. A short sketch will be given of the ideological struggle during the first half of the twentieth century, leading to a significant institutional change: the transformation of a system of private wage bargaining into a collective wage bargaining system. Then the neoclassical, the Marxist and the Keynesian view on the effects of union power on the economic performance of a market economy and of a welfare state will be presented. The conclusion is drawn that the methods required to transform a market economy into a welfare state are anomalies as soon as a welfare state is more or less realized. This is particularly so, because the transformation of a welfare state into a centrally planned economy cannot be considered desirable. In present circumstances, it would be appropriate to pay more attention to the design of an extensive system of mediation and arbitrage to reduce the use of the strike weapon.