Linear,non-linear,bi-directional? Testing the nature of the relationship between mobility and satisfaction with life

Transportation - Travel is one of the most important facilitators of life and has been widely acknowledged as a prerequisite for economic and social activity. Research developing in recent decades...     

Benthic community patterns reflect water column processes in the Northeast Water polynya (Greenland)

Benthic community patterns were investigated in the Northeast Water polynya (Greenland) during the summers of 1992 and 1993 to elucidate to what extent the bottom fauna is influenced by the dynamics of the overlying water. Five different fractions of the benthos (foraminiferans, nematodes, polychaetes, peracarid crustaceans, and epibenthic megafauna), ranging in average adult body size over 6 orders of magnitude (from about 100 μm to about 10 cm), were sampled quantitatively at 69 stations in water depths from 40 to 515 m. Total abundances of nematodes, polychaetes and peracarid crustaceans were found to be primarily correlated with parameters characterizing the potential benthic food supply (water column pigment and nitrate concentrations, sediment bound pigments and sediment biological activity), whereas abundances of foraminiferans and megabenthos were largely associated with seabed properties. Four benthic zones were distinguished by separately analyzing the faunistic composition and distribution of the five community fractions for Ob Bank, Western Westwind Trough, Eastern Westwind Trough, and Belgica Trough. This pattern was shown principally to reflect pelagic regimes differing in surface water hydrography, ice cover and euphotic productivity. This is the first time that a synoptic study of several benthic community portions spanning such a range in sizes and life styles has been performed in a polar shelf ecosystem. Our results indicate that abundances as well as composition of Arctic benthos are largely influenced by mesoscale pelagic processes, and thus provide further evidence for the importance of the benthic-pelagic coupling in high latitude seas.     

Evasive manoeuvres with a steering robot

In the pursuit of an objective rating on vehicle stability performance, it is always desirable to reduce disturbances and inconsistencies during experimental evaluations, especially the ones introduced by human drivers. This paper presents the development of a steering robot designed for closed-loop steering tasks during evasive manoeuvres. It describes the controller structure and discusses experimental results, in addition to simulation/vehicle model verifications and theoretical control analysis.     

Shared taxis: modelling the choice of a paratransit mode in Santiago de Chile

The shared taxi is a special public transport mode, typical of Chilean cities. It operates with cars offering a maximum capacity of four seats, a predefined coverage area and a route that is fixed in principle, but can be adapted to meet passengers’ needs. During a normal day in Santiago, almost 700,000 trips use shared taxis during one of their stages. This represents about 4% of the total trips made in the city, and this modal share increases in zones and periods with low Metro and bus coverage. This study is a first attempt at studying shared taxis as a relevant transport alternative, analysing its main attributes and modelling its demand. With this purpose, after an analysis of the network and its operation, a revealed preference survey (including perceptual indicators) was applied to public transport users in Santiago who had shared taxi as a feasible alternative. Results show a positive evaluation of the mode’s unique attributes, such as the possibility of travelling seated, reducing transfers and alighting at a convenient destination. The subjective valuation of the attributes derived from the models confirm the strong penalty assigned by Chilean users to alternatives implying transfers or increased walking times. The analysis also shows that studying the characteristics of shared taxi users is relevant in a discussion about its regulation and modernization, considering that, while it is desirable to preserve its positive attributes, this should be done in a context of efficient integration with the rest of the transport system.

     

The jurisdictional challenges to the prosecution of piracy cases in Kenya: mixed fortunes for a perfect model in the global war against piracy

Since 2008 Kenya has distinguished itself in the global war against piracy by undertaking prosecutions in the national courts of suspected pirates arrested in the high seas and handed over by navies of leading maritime nations under bilateral agreements (MOUs) entered into between Kenya and these leading maritime nations. As of July 2011, Kenya had over 20 convicted pirates serving jail terms ranging between 7 and 20 years and over 100 suspected pirates awaiting trial in national courts. This is the largest number of suspected pirates held and tried in any one state at any given time in modern history. To achieve this, Kenya had to effect far reaching changes in the law. In the initial stages, suspected pirates were charged under Kenya’s Penal Code (Cap 63 Laws of Kenya). However, the high court in the case of Re Mohamud Mohamed Dashi and eight others [2010] eKLR, ruled that Kenya had no jurisdiction to try suspected pirates under that law. In September 2009, Kenya passed a new law (the Merchant Shipping Act), which not only defined more comprehensively and extensively the offence of piracy, but also extended the jurisdiction of Kenyan courts to try piracy committed by non-nationals. Though the law gives Kenya a very broad jurisdiction to try suspected pirates, the process is still fraught with challenges due to lack of financial and human resources. In the case of Republic vs Hassan Jama Haleys Alias Hassan Jamal and five others [2010] eKLR, the court commented thus:

“… I must note that the ‘piracy trials’ have presented a unique challenge to the Kenyan legal system. We cannot ignore the fact that these are suspects who having been arrested by foreign naval forces on the High Seas are brought to Kenya for trial. They are strangers in the country, do not understand the legal system, may not know what their rights are and do not understand the language… the Kenyan Government and the International partners supporting these trials put in place a system to provide free legal representation for the suspects…”     

Optimal Threshold Policies for Robust Data Center Control

With the simultaneous rise of energy costs and demand for cloud computing, efficient control of data centers becomes crucial. In the data center control problem, one needs to plan at every time step how many servers to switch on or off in order to meet stochastic job arrivals while trying to minimize electricity consumption. This problem becomes particularly challenging when servers can be of various types and jobs from different classes can only be served by certain types of server, as it is often the case in real data centers. We model this problem as a robust Markov decision process (i.e., the transition function is not assumed to be known precisely). We give sufficient conditions (which seem to be reasonable and satisfied in practice) guaranteeing that an optimal threshold policy exists. This property can then be exploited in the design of an efficient solving method, which we provide. Finally, we present some experimental results demonstrating the practicability of our approach and compare with a previous related approach based on model predictive control.     

E-bike user groups and substitution effects: evidence from longitudinal travel data in the Netherlands

Transportation - In recent years, the e-bike has become increasingly popular in many European countries. With higher speeds and less effort needed, the e-bike is a promising mode of transport to...     

A random heaping model of annual vehicle kilometres travelled considering heterogeneous approximation in reporting

Transportation - Annual vehicle kilometres travelled (VKT) is a long used index of car use. Usually, the annual VKT, as reported by respondents, is used for the analysis. But the reported values...