Akmal S. Abdelfatah

A simulation-based signal optimization algorithm within a dynamic traffic assignment framework

This paper considers the issues that arise in seeking to optimize network performance through simultaneous determination of optimal routes and optimal signal settings. It presents numerical experiments for a simulation-based algorithm on a realistic moderately large network (a portion of the Fort-Worth area) and a hypothetical network to underscore the potential of additional improvement through joint consideration of signal control and route assignment compared to either one of these decisions alone.

Modeling Bus Priority Using Intermodal Dynamic Network Assignment-Simulation Methodology

This paper presents a modeling framework that represents bus priority at signalized intersections in the context of its potential network-level and intermodal effects. The model incorporates bus priority within an intermodal dynamic traffic assignment-simulation model, and dynamically assigns travelers to different modes and routes in the network according to prevailing traffic conditions, which result from applying a certain network control/bus priority scheme. The model considers changes in traffic conditions as a result of 1) drivers’ route choice adjustments due to changes in traffic signals settings and 2) modal shifts by travelers to take advantage of improved transit service. Three different bus priority strategies are considered: phase (green) extension, red truncation, and phase advance. A set of simulation experiments is performed to compare these strategies using 2 different assignment scenarios: single-mode assignment and intermodal assignment. The results of these experiments highlight the importance of considering reassignment and potential modal shifts in evaluating traffic network performance under different control schemes, especially when these schemes are expected to affect the modal split in the network such as bus priority.

Faculty response to ethical issues at an American university in the Middle‐East

Purpose – The objective of this study is to get feedback on faculty perception of ethical issues related to teaching, scholarship and service at a relatively new American‐style university in the Middle‐East.Design/methodology/approach – A questionnaire involving 21 scenarios with multiple choice answers was developed and distributed to all faculty at the institution to get their opinion on the issues. The effects of faculty background, gender, rank, and administrative responsibilities on the obtained responses at the institution were considered.Findings – The findings include: about one‐third of the faculty participants were unaware of the universitys code of ethics; several of the faculty surveyed stated that they would ignore violations of an ethical code of conduct committed by colleagues; and there was no definite trend observed between the responses of faculty based on their discipline.Research limitations/implications – The study is based on a questionnaire; this implies that the faculty responses ...

Review of Research on and Implementation of Recycled Concrete Aggregate in the GCC

The goal of sustainable construction is to reduce the environmental impact of a constructed facility over its lifetime. Concrete is the main material used in construction in the Gulf Cooperation Council (GCC). Therefore, it makes economic and environmental sense to use recycled materials in the making of new concrete for different applications. The objectives of this study are to summarize published research on the use of recycled concrete aggregates in new concrete mixes and examine its implementation in construction and industry in the GCC region. The study showed that while there is reasonable research on recycled concrete, the practical implementation in the region greatly lacks behind, especially due to the lack of economic viability and awareness of such applications at the current time.

Utilization of Recycled Coarse Aggregate in Concrete Mixes

In this paper, the effect of the source of recycled coarse aggregate on the properties of concrete is investigated. The tests were conducted on concrete made from three sources of recycled aggregates: (1) old concrete with unknown strength, (2) old concrete with a known compressive strength of 21 MPa, and (3) old concrete with a known strength of 42 MPa. The three sources of recycled aggregates were used to produce new concrete with a target compressive strength of 21 MPa. The first and third sources of recycled aggregates were used in producing concrete with target strength of 42 MPa. A control mix was designed with aggregates from natural sources. The research included two methods of making recycled concrete. One concrete mix was produced using the recycled aggregate and adding more water than the control mix, to reach the target slump, while the second concrete mix was produced using the same amount of water as the control mix but with additional superplasticizer to maintain the target slump. The results obtained in this research showed that the concrete compressive strength depends on the source of recycled aggregates; the stronger the source of recycled aggregate, the higher the compressive strength of the produced concrete. Furthermore, the compressive strength of the first concrete mix was about 10%-20% lower than the compressive strength of the control mix. However, when superplasticizers were used, the compressive strength was around the same value as the control mix.

A conceptual framework for a bridge management system for the United Arab Emirates

Most of the major cities in the United Arab Emirates (UAE) have witnessed a rapid growth rate in population during the past two decades, which was accompanied by the development of major transportation infrastructure. This fast growth of the infrastructure and the pressure of constructing more infrastructures in the UAE cities did not allow the local authorities to develop a suitable Bridge Management System (BMS) to maintain the nations valuable asset at acceptable levels of safety and serviceability. This paper aims at developing a conceptual framework for a BMS that recognizes the local conditions and needs of the UAE. To achieve this objective, the paper provides a review of the BMS around the world and a summary of the local practices and experiences in this area. In addition, a proposed framework for the development of a comprehensive bridge management system for UAE and discussion of the main components of the proposed BMS are presented.

Dynamic O-D Demand Estimation: Application of SPSA AD-PI Method in Conjunction with Different Assignment Strategies

This paper examines the impact of applying dynamic traffic assignment (DTA) and quasi-dynamic traffic assignment (QDTA) models, which apply different route choice approaches (shortest paths based on current travel times, User Equilibrium: UE, and system optimum: SO), on the accuracy of the solution of the offline dynamic demand estimation problem. The evaluation scheme is based on the adoption of a bilevel approach, where the upper level consists of the adjustment of a starting demand using traffic measures and the lower level of the solution of the traffic network assignment problem. The SPSA AD-PI (Simultaneous Perturbation Stochastic Approximation Asymmetric Design Polynomial Interpolation) is adopted as a solution algorithm. A comparative analysis is conducted on a test network and the results highlight the importance of route choice model and information for the stability and the quality of the offline dynamic demand estimations.

Engineering students and faculty perceptions of academic dishonesty

Purpose This paper aims to survey students and faculty from the College of Engineering at an American university in the United Arab Emirates about their perception on different issues related to academic dishonesty. Opinions were sought on plagiarism, inappropriate collaboration, cheating on exams, copyright violations and complicity in academic dishonesty. Reasons for students to commit dishonest acts and ways to reduce academic misconduct were also included. Design/methodology/approach A survey involving 11 questions with multiple choice answers was developed and distributed to engineering students and faculty at the institution to get their perception of the considered issues. Findings Results of the study showed that while faculty and students were generally in agreement in their perception of the frequency of academic dishonesty among students, they greatly differed on the courses of action needed to reduce them. Most faculty members favored applying tougher penalties and using more proctors in exams. On the other hand, students preferred softer approaches such as educating them on academic integrity issues, applying lenient deadlines for assignments and reducing the difficulty of exams. Research limitations/implications The conclusions and recommendations of the study are applicable to colleges of higher education having similar characteristics and culture to the surveyed institution. Practical implications The findings can be used to understand students’ behavior and faculty’s attitude toward academic dishonesty, and to assess the effectiveness of current strategies addressing the issue at similar universities in the region. Originality/value The conducted literature review indicated that this work is believed to be a pioneering case study in the Gulf Cooperation Council countries.