Performance analysis of DSRC priority mechanism for road safety applications in vehicular networks

Dedicated short range communications (DSRC) has been regarded as one of the most promising technologies to provide robust communications for large scale vehicle networks. It is designed to support both road safety and commercial applications. Road safety applications will require reliable and timely wireless communications. However, as the medium access control (MAC) layer of DSRC is based on the IEEE 802.11 distributed coordination function (DCF), it is well known that the random channel access based MAC cannot provide guaranteed quality of services (QoS). It is very important to understand the quantitative performance of DSRC, in order to make better decisions on its adoption, control, adaptation, and improvement. In this paper, we propose an analytic model to evaluate the DSRC-based inter-vehicle communication. We investigate the impacts of the channel access parameters associated with the different services including arbitration inter-frame space (AIFS) and contention window (CW). Based on the proposed model, we analyze the successful message delivery ratio and channel service delay for broadcast messages. The proposed analytical model can provide a convenient tool to evaluate the inter-vehicle safety applications and analyze the suitability of DSRC for road safety applications.

The link between HR practices, psychological contract fulfillment, and organizational performance:the case of the Greek services sector

The purpose of this study is to investigate the impact of human resource (HR) practices on organizational performance through the mediating role of psychological contract (expressed by the influence of employer on employee promises fulfillment through employee attitudes). The study is based on a national sample of 78 organizations from the public and private services sector in Greece, including education, health, and banking, and on data obtained from 348 employees. The statistical method employed is structural equation modeling, via LISREL and bootstrapping estimation. The findings of the study suggest that employee incentives, performance appraisal, and employee promotion are three major HR practices that must be extensively employed. Furthermore, the study suggests that the organization must primarily keep its promises about a pleasant and safe working environment, respectful treatment, and feedback for performance, in order for employees to largely keep their own promises about showing loyalty to the organization, maintaining high levels of attendance, and upholding company reputation. Additionally, the study argues that the employee attitudes of motivation, satisfaction, and commitment constitute the nested epicenter mediating construct in both the HR practices–performance and employer–employee promise fulfillment relationships, resulting in superior organizational performance. © 2012 Wiley Periodicals, Inc.

Process improvement and quality management systems in the financial services industry:the case for the OPEX quality management system and framework

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Developments and prospects of freight railway transport in Northern Germany:a Delphi survey

Despite the fact that Germany has a well expanded traffic infrastructure, it confronts a strong growth in freight volumes and it is very likely that in the forthcoming years will not be able to reasonably cope with the increasing demand. The aim of this paper is to explore the developments of the transport sector, railways in particular, in North Germany. More specific, the paper explores whether the railway network could contribute to improved traffic development in North Germany and also whether or not the existing logistics practices are effective enough to cope with the traffic problems in the region. The research based on the Delphi technique, collected, analysed and summarised the opinions of a group of experts in the aforementioned issues. Results indicate that railways could represent the solution to the forecasted growing freight volumes in the next years. In spite of continuous efforts undertaken by the politics and the economy, the existing logistics and freight traffic concepts are not sufficient, financing is too scarce, while emerging issues like sustainability, environment protection and working conditions are taken into little consideration. Copyright © 2014 Inderscience Enterprises Ltd.

Reformed county government structure and service delivery performance: An integrated study of Florida counties

The most fundamental and challenging function of government is the effective and efficient delivery of services to local taxpayers and businesses. Counties, once known as the “dark continent” of American government, have recently become a major player in the provision of services. Population growth and suburbanization have increased service demands while the counties' role as service provider to incorporated residents has also expanded due to additional federal and state mandates. County governments are under unprecedented pressure and scrutiny to meet citizens' and elected officials' demands for high quality, and equitable delivery of services at the lowest possible cost while contending with anti-tax sentiments, greatly decreased state and federal support, and exceptionally costly and complex health and public safety problems. ^ This study tested the reform government theory proposition that reformed structures of county government positively correlate with efficient service delivery. A county government reformed index was developed for this dissertation comprised of form of government, home-rule status, method of election, number of government jurisdictions, and number of elected officials. The county government reform index and a measure of relative structural fragmentation were used to assess their impact on two measures of service output: mean county road pavement condition and county road maintenance expenditures. The study's multi-level design triangulated results from different data sources and methods of analysis. Data were collected from semi-structured interviews of county officials, secondary archival sources, and a survey of 544 elected and appointed officials from Florida's 67 counties. The results of the three sources of data converged in finding that reformed Florida counties are more likely than unreformed counties to provide better road service and to spend less on road expenditures. The same results were found for unfragmented Florida counties. Because both the county government reform index and the fragmentation variables were specified acknowledging the reform theory as well as elements from the public-choice model, the results help explain contradicting findings in the urban service research. ^ Therefore, as suggested by the corroborated findings of this dissertation, reformed as well as unfragmented counties are better providers of road maintenance service and do so in a less costly manner. These findings hold although the variables were specified to capture theoretical arguments from the consolidated as well as the public-choice theories suggesting a way to advance the debate from the consolidated-fragmented dichotomy of urban governance. ^

Temporal analysis of land use and transportation investments with geographic information system

Land use and transportation interaction has been a research topic for several decades. There have been efforts to identify impacts of transportation on land use from several different perspectives. One focus has been the role of transportation improvements in encouraging new land developments or relocation of activities due to improved accessibility. The impacts studied have included property values and increased development. Another focus has been on the changes in travel behavior due to better mobility and accessibility. Most studies to date have been conducted in metropolitan level, thus unable to account for interactions spatially and temporally at smaller geographic scales. ^ In this study, a framework for studying the temporal interactions between transportation and land use was proposed and applied to three selected corridor areas in Miami-Dade County, Florida. The framework consists of two parts: one is developing of temporal data and the other is applying time series analysis to this temporal data to identify their dynamic interactions. Temporal GIS databases were constructed and used to compile building permit data and transportation improvement projects. Two types of time series analysis approaches were utilized: univariate models and multivariate models. Time series analysis is designed to describe the dynamic consequences of time series by developing models and forecasting the future of the system based on historical trends. Model estimation results from the selected corridors were then compared. ^ It was found that the time series models predicted residential development better than commercial development. It was also found that results from three study corridors varied in terms of the magnitude of impacts, length of lags, significance of the variables, and the model structure. Long-run effect or cumulated impact of transportation improvement on land developments was also measured with time series techniques. The study offered evidence that congestion negatively impacted development and transportation investments encouraged land development. ^

A Look Back To Look Forward: New Patterns In The Supply/Demand Equation In The Lodging Industry

In his dialogue entitled - A Look Back to Look Forward: New Patterns In The Supply/Demand Equation In The Lodging Industry - by Albert J. Gomes, Senior Principal, Pannell Kerr Forster, Washington, D.C. What the author intends for you to know is the following: “Factors which influence the lodging industry in the United States are changing that industry as far as where hotels are being located, what clientele is being served, and what services are being provided at different facilities. The author charts these changes and makes predictions for the future.” Gomes initially alludes to the evolution of transportation – the human, animal, mechanical progression - and how those changes, in the last 100 years or so, have had a significant impact on the hotel industry. “A look back to look forward treats the past as prologue. American hoteliers are in for some startling changes in their business,” Gomes says. “The man who said that the three most important determinants for the success of a hotel were “location, location, location” did a lot of good only in the short run.” Gomes wants to make you aware of the existence of what he calls, “locational obsolescence.” “Locational obsolescence is a fact of life, and at least in the United States bears a direct correlation to evolutionary changes in transportation technology,” he says. “…the primary business of the hospitality industry is to serve travelers or people who are being transported,” Gomes expands the point. Tied to the transportation element, the author also points out an interesting distinction between hotels and motels. In addressing, “…what clientele is being served, and what services are being provided at different facilities,” Gomes suggests that the transportation factor influences these constituents as well. Also coupled with this discussion are oil prices and shifts in transportation habits, with reference to airline travel being an ever increasing method of travel; capturing much of the inter-city travel market. Gomes refers to airline deregulation as an impetus. The point being, it’s a fluid market rather than a static one, and [successful] hospitality properties need to be cognizant of market dynamics and be able to adjust to the variables in their marketplace. Gomes provides many facts and figures to bolster his assertions. Interestingly and perceptively, at the time of this writing, Gomes alludes to America’s deteriorating road and bridge network. As of right now, in 2009, this is a major issue. Gomes rounds out this study by comparing European hospitality trends to those in the U.S.

It takes an institution's village to retain a student: A comprehensive look at two early warning system undergraduate retention programs and administrators' perceptions of students' experiences and the retention services they provide students in the early warning system retention programs

Institutions have implemented many campus interventions to address student persistence/retention, one of which is Early Warning Systems (EWS). However, few research studies show evidence of interventions that incorporate noncognitive factors/skills, and psychotherapy/psycho-educational processes in the EWS. A qualitative study (phenomenological interview and document analysis) of EWS at both a public and private 4-year Florida university was conducted to explore EWS through the eyes of the administrators of the ways administrators make sense of students' experiences and the services they provide and do not provide to assist students. Administrators' understanding of noncognitive factors and the executive skills subset and their contribution to retention and the executive skills development of at-risk students were also explored. Hossler and Bean's multiple retention lenses theory/paradigms and Perez's retention strategies were used to guide the study. Six administrators from each institution who oversee and/or assist with EWS for first time in college undergraduate students considered academically at-risk for attrition were interviewed. Among numerous findings, at Institution X: EWS was infrequently identified as a service, EWS training was not conducted, numerous cognitive and noncognitive issues/deficits were identified for students, and services/critical departments such as EWS did not work together to share students' information to benefit students. Assessment measures were used to identify students' issues/deficits; however, they were not used to assess, track, and monitor students' issues/deficits. Additionally, the institution's EWS did address students' executive skills function beyond time management and organizational skills, but did not address students' psychotherapy/psycho-educational processes. Among numerous findings, at Institution Y: EWS was frequently identified as a service, EWS training was not conducted, numerous cognitive and noncognitive issues/deficits were identified for students, and services/critical departments such as EWS worked together to share students' information to benefit students. Assessment measures were used to identify, track, and monitor students' issues/deficits; however, they were not used to assess students' issues/deficits. Additionally, the institution's EWS addressed students' executive skills function beyond time management and organizational skills, and psychotherapy/psycho-educational processes. Based on the findings, Perez's retention strategies were not utilized in EWS at Institution X, yet were collectively utilized in EWS at Institution Y, to achieve Hossler and Bean's retention paradigms. Future research could be designed to test the link between engaging in the specific promising activities identified in this research (one-to-one coaching, participation in student success workshops, academic contracts, and tutoring) and student success (e.g., higher GPA, retention). Further, because this research uncovered some concern with how to best handle students with physical and psychological disabilities, future research could link these same promising strategies for improving student performance for example among ADHD students or those with clinical depression.

Computational fluid dynamics (CFD) based approach to consequence assessment of accidental release of hydrocarbon during storage and transportation

This thesis investigated the risk of accidental release of hydrocarbons during transportation and storage. Transportation of hydrocarbons from an offshore platform to processing units through subsea pipelines involves risk of release due to pipeline leakage resulting from corrosion, plastic deformation caused by seabed shakedown or damaged by contact with drifting iceberg. The environmental impacts of hydrocarbon dispersion can be severe. Overall safety and economic concerns of pipeline leakage at subsea environment are immense. A large leak can be detected by employing conventional technology such as, radar, intelligent pigging or chemical tracer but in a remote location like subsea or arctic, a small chronic leak may be undetected for a period of time. In case of storage, an accidental release of hydrocarbon from the storage tank could lead pool fire; further it could escalate to domino effects. This chain of accidents may lead to extremely severe consequences. Analyzing past accident scenarios it is observed that more than half of the industrial domino accidents involved fire as a primary event, and some other factors for instance, wind speed and direction, fuel type and engulfment of the compound. In this thesis, a computational fluid dynamics (CFD) approach is taken to model the subsea pipeline leak and the pool fire from a storage tank. A commercial software package ANSYS FLUENT Workbench 15 is used to model the subsea pipeline leakage. The CFD simulation results of four different types of fluids showed that the static pressure and pressure gradient along the axial length of the pipeline have a sharp signature variation near the leak orifice at steady state condition. Transient simulation is performed to obtain the acoustic signature of the pipe near leak orifice. The power spectral density (PSD) of acoustic signal is strong near the leak orifice and it dissipates as the distance and orientation from the leak orifice increase. The high-pressure fluid flow generates more noise than the low-pressure fluid flow. In order to model the pool fire from the storage tank, ANSYS CFX Workbench 14 is used. The CFD results show that the wind speed has significant contribution on the behavior of pool fire and its domino effects. The radiation contours are also obtained from CFD post processing, which can be applied for risk analysis. The outcome of this study will be helpful for better understanding of the domino effects of pool fire in complex geometrical settings of process industries. The attempt to reduce and prevent risks is discussed based on the results obtained from the numerical simulations of the numerical models.

Parental Criminal Justice Involvement and Children's Involvement With Child Protective Services: Do Adult Drug Treatment Courts Prevent Child Maltreatment?

BACKGROUND: In light of evidence showing reduced criminal recidivism and cost savings, adult drug treatment courts have grown in popularity. However, the potential spillover benefits to family members are understudied. OBJECTIVES: To examine: (1) the overlap between parents who were convicted of a substance-related offense and their children's involvement with child protective services (CPS); and (2) whether parental participation in an adult drug treatment court program reduces children's risk for CPS involvement. METHODS: Administrative data from North Carolina courts, birth records, and social services were linked at the child level. First, children of parents convicted of a substance-related offense were matched to (a) children of parents convicted of a nonsubstance-related offense and (b) those not convicted of any offense. Second, we compared children of parents who completed a DTC program with children of parents who were referred but did not enroll, who enrolled for <90 days but did not complete, and who enrolled for 90+ days but did not complete. Multivariate logistic regression was used to model group differences in the odds of being reported to CPS in the 1 to 3 years following parental criminal conviction or, alternatively, being referred to a DTC program. RESULTS: Children of parents convicted of a substance-related offense were at greater risk of CPS involvement than children whose parents were not convicted of any charge, but DTC participation did not mitigate this risk. Conclusion/Importance: The role of specialty courts as a strategy for reducing children's risk of maltreatment should be further explored.

Climate change and the long-term viability of the World’s busiest heavy haul ice road

Climate models project that the northern high latitudes will warm at a rate in excess of the global mean. This will pose severe problems for Arctic and sub-Arctic infrastructure dependent on maintaining low temperatures for structural integrity. This is the case for the economically important Tibbitt to Contwoyto Winter Road (TCWR)—the world’s busiest heavy haul ice road, spanning 400 km across mostly frozen lakes within the Northwest Territories of Canada. In this study, future climate scenarios are developed for the region using statistical downscaling methods. In addition, changes in lake ice thickness are projected based on historical relationships between measured ice thickness and air temperatures. These projections are used to infer the theoretical operational dates of the TCWR based on weight limits for trucks on the ice. Results across three climate models driven by four RCPs reveal a considerable warming trend over the coming decades. Projected changes in ice thickness reveal a trend towards thinner lake ice and a reduced time window when lake ice is at sufficient thickness to support trucks on the ice road, driven by increasing future temperatures. Given the uncertainties inherent in climate modelling and the resultant projections, caution should be exercised in interpreting the magnitude of these scenarios. More certain is the direction of change, with a clear trend towards winter warming that will reduce the operation time window of the TCWR. This illustrates the need for planners and policymakers to consider future changes in climate when planning annual haulage along the TCWR.

Growth and Public Transportation Investments: Growth Management Strategies to Reduce Transportation Capital Costs In and Near Midwestern Urban Areas, 1995

Transportation and land-use are independent, inter-active systems. Land-use patterns shape local transportation demand, but transportation systems in turn influence land-use patterns. In attempting to satisfy transportation demand created by existing land-use patterns, transportation planners directly, if not always consciously or intentionally, influence future land-use patterns. This study examines that complex relationship. The purpose of the study was threefold: to compile the body of knowledge already existing; to apply this body of knowledge to the context of midsize cities in the Midwest; and, to make the knowledge accessible both to transportation planners and to public officials who make key decisions about land use.

Estimates of Total Fuel Consumption in Transporting Grain from Iowa to Major Grain-Importing Countries by Alternative Modes and Routes, 1985

This study measured fuel consumption in transporting grain from Iowa origins to Japan and Amsterdam by alternative routes and modes of transport and applied these data to construct equations for fuel consumption from Iowa origins to alternative final destinations. Some of the results are as follows: (1) The metered tractor-trailer truck averaged 186.6 gross ton-miles per gallon and 90.5 net ton-miles per gallon when loaded 50% of total miles. (2) The 1983 fuel consumption of seven trucks taken from company records was 82.4 net ton-miles per gallon at 67.5% loaded miles and 68.6 net ton-miles per gallon at 50% loaded miles. (3) Unit grain trains from Iowa to West Coast ports averaged 437.0 net ton-miles per gallon whereas unit grain trains from Iowa to New Orleans averaged 640.1 net ton-miles per gallon--a 46% advantage for the New Orleans trips. (4) Average barge fuel consumption on the Mississippi River from Iowa to New Orleans export grain elevators was 544.5 net ton-miles per gallon, with a 35% backhaul rate. (5) Ocean vessel net ton-miles per gallon varies widely by size of ship and backhaul percentage. With no backhaul, the average net ton-miles per gallon were as follows: for 30,000 dwt ship, 574.8 net ton-miles per gallon; for 50,000 dwt ship, 701.9; for 70,000 dwt ship, 835.1; and for 100,000 dwt ship, 1,043.4. (6) The most fuel efficient route and modal combination to transport grain from Iowa to Japan depends on the size of ocean vessel, the percentage of backhaul, and the origin of the grain. Alternative routes and modal combinations in shipping grain to Japan are ranked in descending order of fuel efficiencies.