853 research outputs found

    GIS Potential in Management of Pedestrian Accidents in Developing Countries

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    The main objective of this work was to investigate the potential of utilizing geographic information systems (GISs) in identifying hazardous pedestrian accident-prone locations. The study was performed for roads in Irbid city-Jordan for the years 2002 and 2003. Pedestrian accident data was analyzed by pedestrian characteristics, driver characteristics, accident time and location, environmental conditions, vehicle speed and characteristics, and accident severity. Pedestrian accidents were correlated to operational factors, including traffic volume, vehicle speed, pedestrian volume, street length, and access points. Hazardous locations of vehicle-pedestrian accidents were identified using a GIS query builder. Results showed that there was a high potential for GISs in studying pedestrian accidents

    Study on New Sampling Plans and Optimal Integration with Proactive Maintenance in Production Systems

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    Sampling plans are statistical process control (SPC) tools used mainly in production processes. They are employed to control processes by monitoring the quality of produced products and alerting for necessary adjustments or maintenance. Sampling is used when an undesirable change (shift) in a process is unobservable and needs time to discover. Basically, the shift occurs when an assignable cause affects the process. Wrong setups, defective raw materials, degraded components are examples of assignable causes. The assignable cause causes a variable (or attribute) quality characteristic to shift from the desired state to an undesired state. The main concern of sampling is to observe a process shift quickly by signaling a true alarm, at which, maintenance is performed to restore the process to its normal operating conditions. While responsive maintenance is performed if a shift is detected, proactive maintenance such as age-replacement is integrated with the design of sampling. A sampling plan is designed economically or economically-statistically. An economical design does not assess the system performance, whereas the economic-statistical design includes constraints on system performance such as the average outgoing quality and the effective production rate. The objective of this dissertation is to study sampling plans by attributes. Two studies are conducted in this dissertation. In the first study, a sampling model is developed for attribute inspection in a multistage system with multiple assignable causes that could propagate downstream. In the second study, an integrated model of sampling and maintenance with maintenance at the time of the false alarm is proposed. Most of the sampling plans are designed based on the occurrence of one assignable cause. Therefore, a sampling plan that allows two assignable causes to occur is developed in the first study. A multistage serial system of two unreliable machines with one assignable cause that could occur on each machine is assumed where the joint occurrence of assignable causes propagates the process\u27s shift to a higher value. As a result, the system state at any time is described by one in-control and three out-of-control states where the evolution from a state to another depends on the competencies between shifts. A stochastic methodology to model all competing scenarios is developed. This methodology forms a base that could be used if the number of machines and/or states increase. In the second study, an integrated model of sampling and scheduled maintenance is proposed. In addition to the two opportunities for maintenance at the true alarm and scheduled maintenance, an additional opportunity for preventive maintenance at the time of a false alarm is suggested. Since a false alarm could occur at any sampling time, preventive maintenance is assumed to increase with time. The effectiveness of the proposed model is compared to the effectiveness of separate models of scheduled maintenance and sampling. Inspired by the conducted studies, different topics of sampling and maintenance are proposed for future research. Two topics are suggested for integrating sampling with selective maintenance. The third topic is an extension of the first study where more than two shifts can occur simultaneously

    The Value Relevance of Accounting Information in Emerging Stock Exchange Markets "Case of Jordan"

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    In a different way from the pervious studies concerning factors affecting individual investors’ decisions in stock markets, this study aimed to assess the value relevance of accounting information for investment decisions, as well as to investigate if investors` demographic and behavior factors affect this value relevance. A questionnaire was developed and distributed to a sample of individual investors in Amman Stock Exchange (ASE). The results indicated that Jordanian individual investors perceive accounting information to be value relevant to investment decisions regardless of their demographic and behavior factors. Also, the study reveled that investment decisions are affected by other factors, such as trading volume, key investors, and company reputation. A secondary result indicated that trading frequency is affected by factors of sex, portfolio size, and monthly income. Finally, the study revealed that individual investors exhibit behavioral biases such as: overconfidence, herd, and personal judgment. Key Words: Individual investors, Decisions, Accounting information, Value relevance, Amman Stock Exchange

    Spatial Mapping of Traffic Noise Levels in Urban Areas

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    This paper combines field data with an analytical approach to spatially map noise levels due to traffic movements at relatively high traffic volume signalized intersections utilizing the potential of Geographic Information Systems (GIS). Noise data were collected using a discrete mapping technique at 29 signalized intersections, as well as between intersections, and at their respective neighborhood areas in Amman, capital of Jordan. Data were collected in three different highly congested traffic peak periods: 7:30 a.m.-9:00 a.m., 1:30 p.m.-3:00 p.m., and 9:00 p.m.-11:00 p.m. A portable precision sound level meter capable of measuring noise levels from 34 to 134 decibels (dB) was used during the data collection process. The highest recorded noise level at some signals was 80 dB, while the lowest was 34 dB. In fact, some signalized intersections showed higher noise levels than the acceptable or the standard ones, i.e., 65 dB for daytime and 55 dB for nighttime in residential areas at city center. Two-dimensional (2D) vector and raster maps of noise levels, at different time periods for signals' areas and neighborhoods, were spatially displayed. Results showed that the developed GIS maps could be useful for city planning and other environmental management applications for the purpose of: 1) temporal monitoring and queries of noise level changes as a function of time, 2) spatial queries to find the highest noise disturbance location and its time of the day, 3) development of an online noise information system, 4) using noise level based spatial maps as indicators of variation in land prices, and 5) forecasting and current assessment of the acoustic climate of urban areas

    Effect of Interfacial Properties on the Behaviour of Retrofitted Members

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    Few contributions are available concerning the effect of interfacial properties on the behaviour of retrofitted beams using fibre reinforced polymers. In this paper, finite element analyses of the test specimens from literature were carried out to investigate the effect of interfacial parameters such as, fracture energy, local shear stress and interfacial stiffness on the retrofitted beam performance. Results from the analyses reveal that the load-carrying capacity is significantly influenced by interfacial parameters, fracture energy, local shear stress and interfacial stiffness. Higher shear stress and fracture energy increase the composite action by increasing the maximum load and delaying debonding. The stiffness of the FRP-concrete interface was found to influence the load-carrying capacity and axial strain in FRP. The axial strain in FRP increases by increasing the stiffness of the FRP-concrete interface

    Almost periodic solutions for Fox production harvesting model with delay

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    By utilizing the continuation theorem of coincidence degree theory, we shall prove that a Fox production harvesting model with delay has at least one positive almost periodic solution. Some preliminary assertions are provided prior to proving our main theorem. We construct a numerical example along with graphical representations to illustrate feasibility of the theoretical result

    Magnetic Nanoparticles as MRI Contrast Agents

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    Magnetic Resonance Imaging (MRI) is a non-invasive imaging modality that offers both anatomical and functional information. Intrinsic longitudinal and transverse relaxation times (T1 and T2, respectively) provide tools to manipulate image contrast. Additional control is yielded when paramagnetic and magnetic particulate materials are used as contrast materials. Superparamagnetic particles are mostly synthesized from iron oxide and are usually coated with polymers and functional particles to offer multifunctional biomedical applications. The latter include not only MRI but also cancer treatment through drug delivery and hyperthermia. This Chapter reviews the fundamental dipole–dipole diamagnetic proton relaxation mechanism dominant in water followed by a brief description of the use of gadolinium complexes as MRI contrast agent. Finally, a description of the important chemical and physical properties of magnetic nanoparticle (MNP) that define their use as MRI relaxation enhancing agents especially for T2. The main governing models are described for the different motional regimes with few simulation results demonstrating the applicability of the given equations
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