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131.
This paper studies the fault diagnosis of singular stochastic systems. The probability distribution of output is measured
by probability density functions (PDFs), which are modeled by a square root B-spline expansion. An adaptive nonlinear observer
is proposed to estimate the size of the fault occurring in systems. Furthermore, the linear matrix inequality (LMI) approach
is applied to establish sufficient conditions for the existence of the observer. Finally, the simulation results are given
to indicate the method for diagnosing the fault. 相似文献
132.
Michael Ekow Manuel 《WMU Journal of Maritime Affairs》2017,16(3):473-483
Traditional seafarer training has always focused on the acquisition and use of practical skills. The prevailing view is that, while this approach addresses a degree of cognitive skills, it focuses on and gives much more emphasis to the acquisition of hands-on practical skills for the performance of specific tasks. On the other hand, academic education has been seen to be much more focused on the development of in-depth analytical and critical thinking skills; cognitive skills that are less reliant on hands-on task-oriented training, but stress critical reading and discussion. The global trend in maritime education and training is increasingly to link an essentially vocational education that provides specific and restricted competence outcomes with more general or deeper academic components leading to an academic qualification. This trend has led to some dilemmas for curriculum development, for training legislation in a global industry, and for achieving desired learning outcomes in a professional setting (in the shipping industry). This paper discusses some of the challenges arising from this trend and the opportunities the trend offers. 相似文献
133.
Carlos Jerome Lawrence A. Howard Ezgi Uzel Jameela R. Androulidakis 《WMU Journal of Maritime Affairs》2017,16(1):89-98
Protection against on-ship infectious disease—whether due to mishap or to harmful purpose—faces special situational problems. Sometimes, when infection levels on board have reached threshold levels, emergency actions are required. Often, the most thorough strategies for responding to threat are not feasible. A rapid first-stage test (RFT) is a fast, minimally invasive procedure used to rule out from possible infection a large percentage of an infection-threatened group. Prevention and control of on-ship infection need to combine various interconnected tactics. When timely criterion tests are not possible, the medical team must adopt fast alternative measures. The methods used to summarize protection against on-ship infectious agents included a scientific literature review and a web search. The fields of the review were maritime, health, and technology sources. Special attention was paid to material dealing with risks and threats of on-ship penetration by infectious agents, on-ship infection prevalence thresholds, and rapid diagnostic screens. The Bayes rule and the law of large numbers were applied to the analysis, for large on-ship populations, of RFT indications of crossing of an infection prevalence threshold. The increasing risk of serious on-ship infection—either accidental or purposeful—calls for a multi-layered protection approach. RFTs are a key part of the outer layer of such a defense. Well-designed and well-administered RFTs provide several advantages for defense against on-ship infection: low-cost, non-invasive, fast, and focuses on a drastically smaller number of infection possibilities. 相似文献
134.
The brittleness analysis and important nodes detection have been a hot spot in the complex networks. How to get the overall feature of the whole network and how to find out some important nodes are requisites to solve these problems. In this paper, we adopt the trace of the adjacency matrix and the centrality of the complex networks to give a quantitative and qualitative analysis of networks being studied. Results show that the k-shell plays a more important role than the degree centrality and the betweenness in finding important nodes, and it can also be used to give direction on the immunization and maintenance of complex networks. 相似文献
135.
The crude oil offloading and supply problem (COSP) is a type of operation maritime inventory routing (MIR) problem encountered by petroleum companies. In COSP, the company not only is responsible for the ship scheduling to carry the crude oil from production sites to discharge ports but also must maintain inventory levels at both ports (production and consumption) between safety operational bounds to avoid disruptions in its crude oil production and/or refining processes. We show how to improve significantly the decision-making process in a Brazilian petroleum company using a mixed-integer linear programming (MILP) model to represent COSP. Comparison tests with a current ship-scheduling method adopted in the company indicated that the use of the MILP model increased the transportation efficiency and reduced costs by 20% on average. In addition to the quantitative gains, the use of a MILP model to solve COSP has succeeded when encountering real-life events, such as variation in production or consumption rates, berth unavailability, and changes in the storage capacities at ports. 相似文献
136.
Michael Duncan 《Transportation》2011,38(2):363-382
Carsharing is a vehicle sharing service for those with occasional need of private transportation. Transportation planners
are beginning to see great potential for carsharing in helping to create a more diversified and sustainable transport system.
While it has grown quickly in the US in recent years, it is still far from the level where it can deliver significant aggregate
benefits. A key element to the potential growth of carsharing is its ability to provide cost savings to those who adopt it
in favor of vehicle ownership. This research seeks to quantify these potential cost savings. The costs of carsharing and vehicle
ownership are compared based on actual vehicle usage patterns from a large survey of San Francisco Bay Area residents. The
results of this analysis show that a significant minority of Bay Area households own a vehicle with a usage pattern that carsharing
could accommodate at a lower cost. Further research is required to indentify how these cost savings translate to the adoption
of carsharing. 相似文献
137.
The European Union (EU) has proposed renewing the target for halving the number of road fatalities in the period 2011–2020. In this paper, a nonlinear distribution method for dynamic fatality reduction targets is applied for the purpose of finding individual national mortality reduction targets for each of the 27 member countries in the EU. Weighting is undertaken for four scenarios based on the following indicators: road mortality rates, fatality rates, fatality risks, and fatality density. Results are presented for four proposals to reduce the number of fatalities in each Member State, based on the original situation of the indicators considered in the study. The results seek to provide policy-makers with a broader vision with regard to the achievement of the goals of EU road safety policy. 相似文献
138.
Lajos Urbán 《运输评论》2013,33(4):305-321
Abstract In its introductory part this article discusses the principles of the transport policy approved in 1968, followed by the reasons behind the advances on this policy approved in 1978. It then goes on to review the Hungarian transport pattern and organization, including the roles played by the railways, the road transport companies, the state‐owned enterprises as well as cooperatives, urban transport, shipping, air transport, pipelines, and private transport. In discussing the division of labour (or market sharing) in transport it concludes that passenger transport is increasing slowly, while the proportion of private transport is continuing to rise. A moderate increase is expected in goods transport with a decline in the share of the railways and a rise in that of the other transport branches. This division of labour is being influenced by economic, not administrative, means. The main target of the advanced transport policy is to shape a transport system which corresponds to socioeconomic requirements. This means that goods transport capacities must be put to more efficient use, which involves improving development, organizational and planning operations. In passenger transport priority must go to public transport while the proportion of private transport must be defined in keeping with demand and economic possibilities. In the development of the infrastructure and investments, the need to improve energy use and protect the environment must be stressed. The rest of the article presents the detailed reasoning behind the measures already taken and scheduled to be taken to achieve these main targets. 相似文献
139.
A digital signature with message recovery is a signature that the message itself (or partial of the message) is not required
to be transmitted together with the signature. It has the advantage of small data size of communication comparing with the
traditional digital signatures. In this paper, combining both advantages of the message recovery signatures and the certificateless
cryptography, we propose the first certificatelss signature scheme with message recovery. The remarkable feature of our scheme
is that it can achieve Girault’s Level-3 security while the conventional certificateless signature scheme only achieves Level-2
security. The security of the scheme is rigorously proved in the random oracle model based on the hardness of the k bilinear Diffie-Hellman inverse (k-BDHI) problem. 相似文献
140.
User selection is necessary for multiuser multiple-input multiple-output (MIMO) downlink systems with block diagonalization
(BD) due to the limited free spatial transmit dimensions. The pure user selection algorithms can be improved by performing
receive antenna selection (RAS) to increase sum rate. In this paper, a joint user and antenna selection algorithm, which performs
user selection for sum rate maximization in the first stage and then performs antenna selection in the second stage, is proposed.
The antenna selection process alternately drops one antenna with the poorest channel quality based on maximum determinant
ranking (MDR) from the users selected during the first stage and activates one antenna with the maximum norm of projected
channel from the remaining users. Simulation results show that the proposed algorithm significantly outperforms the algorithm
only performing user selection as well as the algorithm combining user selection with MDR receive antenna selection in terms
of sum rate. 相似文献