A time‐staged multi‐objective network‐design model

A multi‐objective, time‐staged network‐design problem is formulated. Through transformation, the problem is decomposed into a set of single‐period, single‐objective problems. Lexicographic ordering is instrumental in effecting this transformation; it also allows a backward‐recursion algorithm to be applied using strong pruning criteria. Furthermore, monotonicity properties enable us to solve the problem using the familiar tree‐search algorithms. The solution method has several desirable properties — as shown by an example and a case study of Tripoli Province, Libya. First, the algorithm ensures continuity of project implementation over the multi time‐periods and provides optimality in later computational stages irrespective of the decision at an interim stage. Second, the algorithm tends to provide accessibility to unconnected regions in the study area at low user‐cost without employing weights to the two objective functions of accessibility and user‐cost efficiency. Such a property is deemed advantageous for suggesting transportation investments based purely on purchasing the greatest benefit for each dollar, with political neutrality strictly maintained.     

Sensitivity analysis on stochastic equilibrium transportation networks using genetic algorithm

This study deals with the sensitivity analysis of an equilibrium transportation networks using genetic algorithm approach and uses the bi‐level iterative sensitivity algorithm. Therefore, integrated Genetic Algorithm‐TRANSYT and Path Flow Estimator (GATPFE) is developed for signalized road networks for various level of perceived travel time in order to test the sensitivity of perceived travel time error in an urban stochastic road networks. Level of information provided to drivers correspondingly affects the signal timing parameters and hence the Stochastic User Equilibrium (SUE) link flows. When the information on road system is increased, the road users try to avoid conflicting links. Therefore, the stochastic equilibrium assignment concept tends to be user equilibrium. The GATPFE is used to solve the bi‐level problem, where the Area Traffic Control (ATC) is the upper‐level and the SUE assignment is the lower‐level. The GATPFE is tested for six‐junction network taken from literature. The results show that the integrated GATPFE can be applied to carry out sensitivity analysis at the equilibrium network design problems for various level of information and it simultaneously optimize the signal timings (i.e. network common cycle time, signal stage and offsets between junctions).     

摩洛哥大西洋沿岸的波能评估（英文）

The aim of the present work is to assess the offshore wave energy potential along the Atlantic coast of Morocco. Research works of this paper focus on the identification of the most energetic sites for wave energy converters(WECs) deployment. For this purpose, 11 sites have been explored; all of them are located at more than 40 m depth on the Moroccan Atlantic coast. The wave power at each site is computed on the basis of wave data records in terms of significant wave height and energy period provided by the Wave Watch three(WW3) model. Results indicate that the coast sites located between latitudes 30° 30′ N and 33° N are the most energetic with an annual average wave power estimated at about 30 kW· m~(-1), whereas, in the other sites, the wave power is significantly lower. Moreover, the study of the monthly and seasonal temporal variability is found to be uniform in the powerful sites with values four times greater in winter than in summer. The directional investigation on the significant wave height has shown that for almost all the powerful sites, the incoming waves have a dominant sector ranging between Northern(N) and Western-Northern-Western(WNW) directions.     

An exact modelling of the uniform control traffic delay in undersaturated signalized intersections

The average delay experienced by vehicles at a signalized intersection defines the level of service (LOS) at which the intersection operates. A major challenge in this regard is the ability to accurately estimate all the components underlying the overall control delay, including the uniform, incremental and initial queue delays. This paper tackles this challenging task by proposing a novel exact model of the uniform control delay component with a view to enhancing the accuracy of the existing approximate models, notably, the one reported in the Highway Capacity Manual 2010. Both graphical and analytical proofs are employed to derive exact closed‐form expressions for the uniform control delay at undersaturated signalized intersections. The high degree of accuracy of the proposed models is analysed through extensive simulations to demonstrate their abilities to exactly characterize the performance of real‐life intersections in terms of the resulting vehicle delay. Unlike the existing widely adopted uniform delay models, which tend to overestimate the LOS of real‐life intersections, the delay models introduced in this paper have the merit of exactly capturing such a LOS. Copyright © 2016 John Wiley & Sons, Ltd.     

Operational performance comparison of four unconventional intersection designs using micro‐simulation

Several unconventional intersection designs have been proposed as an innovative approach to mitigate congestion at heavily congested at‐grade signalized intersections. Many of these unconventional designs were shown to outperform conventional intersections in terms of the average control delay and the overall intersection capacity. Little research has been conducted to compare the performance of these unconventional intersections to each other under different volume conditions. This study evaluated and compared the operational performance of four unconventional intersection schemes: the crossover displaced left‐turn (XDL), the upstream signalized crossover (USC), the double crossover intersection (DXI) (i.e., half USC), and the median U‐turn (MUT). The micro‐simulation software vissim (PTV Planung Transport Verkehr AG, Karlsruhe, Germany) was used to model and analyze the four unconventional intersections as well as a counterpart conventional one. The results showed that the XDL intersection constantly exhibited the lowest delays at nearly all tested balanced and unbalanced volume levels. The operational performance of both the USC and the DXI was similar in most volume conditions. The MUT design, on the other hand, was unable to accommodate high approach volumes and heavy left‐turn traffic. The capacity of the XDL intersection was found to be 99% higher than that of the conventional intersection, whereas the capacity of the USC and the DXI intersections was about 50% higher than that of the conventional intersection. The results of this study can provide guidance on choosing among alternative unconventional designs according to the prevailing traffic conditions at an intersection. Copyright © 2012 John Wiley & Sons, Ltd.     

The development of a policy for road tax in Turkey, using a genetic algorithm approach for demand estimation

This study deals, first, with estimation of transport demand based on Genetic Algorithm (GA) approach, and then deals with the evaluation of the road tax system in Turkey. It proposes an alternative road tax policy. The total transport demand is estimated based on population, Gross Domestic Product per Capita (GDPPC), and vehicle-number. Three forms of the Genetic Algorithm Transport Demand Estimation for Tax Revenues (GATDETR) are developed, of which one is linear, and the second and third are exponential forms of the mathematical expressions. The best-fit GATDETR model in terms of total minimum relative average errors between observed and estimated values are selected for future demand estimation. The evaluation of the road tax system and policy proposal is made based on estimated demand. The Distance-Based-Taxation (DBT) system is proposed in order to control highway transport. With the DBT system, some road users may wish to use railway. Thus, we re-organize the railways in order to meet the demand, but this requires new fund. The DBT system may help to create to this fund. It may also help to develop fair-taxation for the road users. Results show that the GA can be used to model transport demand and hence income tax in future transports planning. This study also suggests that planning the taxation in highway transport may help to ease funding problem of railway system.     

Passing sight distance on two-lane highways: Review and revision

Several models have been developed to determine the minimum passing sight distance required for safe and efficient operation on two-lane highways. The American Association of State Highway and Transportation Officials has developed a model assuming that once the driver begins a pass, he/she has no opportunity but to complete it. This assumption is believed to result in exaggerated passing sight distance requirements. Considerably shorter passing sight distance values are presented in the Manual of Uniform Traffic Control Devices and are used as the marking standards in Canada and the U.S.A. More appropriate models have been developed considering the driver's opportunity to abort the pass, and are based on a critical sight distance which produces the same factor of safety whether the pass is completed or aborted. However, these models need to be revised to determine the passing sight distance requirements more accurately and to closely match field observations. In this paper, a revised model for determining the minimum required passing sight distance was developed, based on the concept of critical sight distance and considering the kinematic interaction between the passing, passed, and opposing vehicles. The results of the revised model were compared with field data and showed that the revised model simulates the passing manoeuvre better than the currently-available models which are either too conservative or too liberal. The results showed that the passing sight distance requirements recommended in the Manual of Uniform Traffic Control Devices are sufficient at low design speeds (50–60 k.p.h.) and for manoeuvres involving passenger cars only. For higher design speeds, the Manual of Uniform Traffic Control Devices standards are less than the passing sight distance required for safe and comfortable passes. The deficiency was found to increase with the increase in design speed, and reaches about 36% at a 120-k.p.h. design speed. Based on these results, major revisions to the current Manual of Uniform Traffic Control Devices marking standards are recommended.     

倒置屋面的研究及应用

介绍了倒置屋面技术、发展过程及其在工程中的应用。做为正铺屋面的替代技术其良好的发展前景,以及其所具有的经济和社会效益价值。     

Thermodynamic analysis of alternative marine fuels for marine gas turbine power plants

The marine shipping industry faces challenges to reduce engine exhaust emissions and greenhouse gases (GHGs) from ships, and in particular, carbon dioxide. International regulatory bodies such as the International Maritime Organization and National Environmental Agencies of many countries have issued rules and regulations to drastically reduce GHG and emissions emanating from marine sources. This study investigates the possibility of using natural gas and hydrogen as alternative fuels to diesel oil for marine gas turbines and uses a mathematical model to assess the effect of these alternative fuels on gas turbine thermodynamic performance. Results show that since natural gas is categorized as a hydrocarbon fuel, the thermodynamic performance of the gas turbine cycle using natural gas was close to that of the diesel case. However, the gas turbine thermal efficiency was found to be slightly lower for natural gas and hydrogen fuels compared to diesel fuel.     

Grouper Culture: An Option for Grouper Management in Indonesia

Strong market demand, combined with the high price of live groupers for live food fish, aquarium fish, and grouper farming, has been enticing all participants in the live reef fish trade (LRFT) network in Asian countries to exploit more live groupers, resulting in an alarming situation regarding groupers in the wild. The current destructive fishing methods that are used to catch live groupers, the fishery's potential for overexploitation, and its impact to both fishers and consumers have raised many concerns among environmentalists, live grouper businesspeople, and the grouper fishers on the need to wisely manage the grouper resources in the wild. Introducing grouper culture looks promising as an option for grouper management.