Aggregate nonparametric safety analysis of traffic zones

Exploring the significant variables related to specific types of crashes is vitally important in the planning stage of a transportation network. This paper aims to identify and examine important variables associated with total crashes and severe crashes per traffic analysis zone (TAZ) in four counties of the state of Florida by applying nonparametric statistical techniques such as data mining and random forest. The intention of investigating these factors in such aggregate level analysis is to incorporate proactive safety measures in transportation planning. Total and severe crashes per TAZ were modeled to provide predictive decision trees. The variables which carried higher weight of importance for total crashes per TAZ were – total number of intersections per TAZ, airport trip productions, light truck productions, and total roadway segment length with 35 mph posted speed limit. The other significant variables identified for total crashes were total roadway length with 15 mph posted speed limit, total roadway length with 65 mph posted speed limit, and non-home based work productions. For severe crashes, total number of intersections per TAZ, light truck productions, total roadway length with 35 mph posted speed limit, and total roadway length with 65 mph posted speed limit were among the significant variables. These variables were further verified and supported by the random forest results.     

An evaluation of Winnipeg's photo enforcement safety program: Results of time series analyses and an intersection camera experiment

The objective of this study was to evaluate the impact of Winnipeg's photo enforcement safety program on speeding, i.e., “speed on green”, and red-light running behavior at intersections as well as on crashes resulting from these behaviors. ARIMA time series analyses regarding crashes related to red-light running (right-angle crashes and rear-end crashes) and crashes related to speeding (injury crashes and property damage only crashes) occurring at intersections were conducted using monthly crash counts from 1994 to 2008. A quasi-experimental intersection camera experiment was also conducted using roadside data on speeding and red-light running behavior at intersections. These data were analyzed using logistic regression analysis. The time series analyses showed that for crashes related to red-light running, there had been a 46% decrease in right-angle crashes at camera intersections, but that there had also been an initial 42% increase in rear-end crashes. For crashes related to speeding, analyses revealed that the installation of cameras was not associated with increases or decreases in crashes. Results of the intersection camera experiment show that there were significantly fewer red light running violations at intersections after installation of cameras and that photo enforcement had a protective effect on speeding behavior at intersections. However, the data also suggest photo enforcement may be less effective in preventing serious speeding violations at intersections. Overall, Winnipeg's photo enforcement safety program had a positive net effect on traffic safety. Results from both the ARIMA time series and the quasi-experimental design corroborate one another. However, the protective effect of photo enforcement is not equally pronounced across different conditions so further monitoring is required to improve the delivery of this measure. Results from this study as well as limitations are discussed.     

Uncertainties and quantification of common cause failure rates and probabilities for system analyses

Simultaneous failures of multiple components due to common causes at random times are modelled by constant multiple-failure rates. A procedure is described for quantification of common cause failure (CCF) basic event probabilities for system models using plant-specific and multiple-plant failure-event data. Methodology is presented for estimating CCF-rates from event data contaminated with assessment uncertainties. Generalised impact vectors determine the moments for the rates of individual systems or plants. These moments determine the effective numbers of events and observation times to be input to a Bayesian formalism to obtain plant-specific posterior CCF-rates. The rates are used to determine plant-specific common cause event probabilities for the basic events of explicit fault tree models depending on test intervals, test schedules and repair policies. Three methods are presented to determine these probabilities such that the correct time-average system unavailability can be obtained with single fault tree quantification. Recommended numerical values are given and examples illustrate different aspects of the methodology.     

Automated manufacturability evaluation system for sheet metal components in mass production

Automated manufacturability evaluation of a given design is a key requirement in realizing complete integration of design and process planning. It would still be better to control the designing process itself with manufacturability information. The purpose of such an evaluation is to assist designers in their effort to come up with manufacturable parts economizing in terms of cost and time, without compromising on quality and functional requirements. The present work deals with one such system developed for manufacturability evaluation of sheet metal components. Unlike most of the work done in the sheet metal area in the past, which concentrates on specific domain or phase of manufacturability evaluation, the present work is more comprehensive combining characteristics of all the existing methods and phases of manufacturability evaluation. The prime components of the present system are design evaluation and process plan generation. Design evaluator and process planner use different types of data and knowledge to identify design and process planning violations which are overcome by suggesting design changes. A process planner also uses manufacturing resource and process information to arrive at manufacturable parts by generating feasible process plans. Results of manufacturability evaluation are presented for typical sheet metal parts to be produced by bending and shearing (blanking and piercing) processes.     

Synthesis of quantitative and qualitative evidence for accident analysis in risk-based highway planning

Accident analysis involves the use of both quantitative and qualitative data in decision-making. The aim of this paper is to demonstrate the synthesis of relevant quantitative and qualitative evidence for accident analysis and for planning a large and diverse portfolio of highway investment projects. The proposed analysis and visualization techniques along with traditional mathematical modeling serve as an aid to planners, engineers, and the public in comparing the benefits of current and proposed improvement projects. The analysis uses data on crash rates, average daily traffic, cost estimates from highway agency databases, and project portfolios for regions and localities. It also utilizes up to two motivations out of seven that are outlined in the Transportation Equity Act for the 21st Century (TEA-21). Three case studies demonstrate the risk-based approach to accident analysis for short- and long-range transportation plans. The approach is adaptable to other topics in accident analysis and prevention that involve the use of quantitative and qualitative evidence, risk analysis, and multi-criteria decision-making for project portfolio selection.     

An integrated approach for production and distribution planning in supply chain management

Many firms have been trying to optimize their production and distribution systems separately, but using this approach limits any possible increase in profit. Thus, it is becoming more important to analyse these two systems simultaneously. This paper presents the solutions for integrated production and distribution planning and investigates the effectiveness of their integration through a computational study, in a multi-plant, multi-retailer, multi-item, and multi-period logistic environment where the objective is to maximize the total net profit. Computational results on test problems using the proposed heuristic confirm the substantial advantage of the integrated planning approach over the decoupled one. Sensitivity analysis on the input parameters indicates that, under the right conditions, the effectiveness of integrating production and distribution functions can be extremely high.     

Constraint effects on plastic crack-tip fields for plane strain mode-I, II and III cracks in non-hardening materials

To explore constraint effects on fully plastic crakc-tip fields, analytical solutions are examined for mode-I, II and III loading in non-hardening materials under plane strain conditions. The results reveal that under mode-II and III loading the crack-tip stress fields are unique, and thus can be characterized by a `single parameter'. Under mode-I loading, however, the crack-tip stress field is non-unique but can be characterized by two sets of solutions or `two parameters'. One set of the solutions is the well-known Prandtl field and the other is a plastic T-stress field. This conclusion corroborates the observation of McClintock (1971) that the slip-line field is non-unique for plane strain tensile cracks. A two-term plastic solution which combines the Prandtl field and the plastic T-stress field with two parameters B ₁ and B ₂ can then characterize the crack-tip stress field of plane strain mode-I crack over the plastic region and quantify the magnitude of crack-tip constraints. These characters are similar to those for hardening materials. Analyses and examples show that the two-term plastic solution can match well with the slip-line field or finite element results over plastic region. Thus the parameters B ₁ and B ₂ can be used to characterize the constraint level for mode-I finite-sized crack specimens in non-hardening materials under plane strain conditions.     

A Direct Energy Balance Approach for Determining Energy Release Rates in Three and Four Point Bend End Notched Flexure Tests

A direct energy balance approach has been developed and used to determine energy release rates in three and four point bend end notched flexure tests. This study was performed in the context of the larger goal of understanding the wide variation in mode II toughnesses that have been obtained by the two tests when used on the same material. The primary motivation for developing the direct energy balance approach was to fully account for the effects of friction, large deformations, and other geometric nonlinearities that occur during these tests. The direct energy balance approach simulates crack advance as it occurs in physical testing. Most significantly, this approach accounts for frictional dissipation that occurs during crack advance, which is an effect that has been neglected in previous analyses of these tests. The direct energy balance approach is used to show that, for most cases of practical interest, the virtual crack closure technique is quite accurate, and predictions by this latter approach are only in error when moderately large geometric nonlinearities occur prior to crack advance. Based on these results, a “cut-off value,” expressed in terms of the maximum slope in the specimen as predicted by classical beam theory, is suggested for the upper limit of applicability of the virtual crack closure technique.     

Kinetic and safety parameters analysis for 1,1,-di-(tert-butylperoxy)-3,3,5-trimethylcyclohexane in isothermal and non-isothermal conditions

Over the past 30 years, the field of thermal analysis of organic peroxides has become an important issue in chemical engineering departments, safety departments, and in companies working with polymerization, petrifaction process, and so on. The contributions of thermal analysis to the evaluation and prediction of the runaway reactions have been important for decreasing or preventing a hazard, such as fire or explosion accident. This study was carried out using differential scanning calorimetry (DSC) to evaluate the kinetic and safety parameters in isothermal and non-isothermal conditions, for instance, temperature of no return (T_NR), self accelerating decomposition temperature (SADT), time to maximum rate (TMR), activation energy (E_a), frequency factor (A), reaction order (n), and reaction heat (ΔH), in terms of the hazardous material of 1,1,-di-(tert-butylperoxy)-3,3,5-trimethylcyclohexane (TMCH) 88 mass%. On the basis of this study, we demonstrated that TMCH 88 mass% must be well controlled in the manufacturing process due to the unstable structure of O-O, which releases a great quantity of heat, higher than 1300 J/g under decomposition. Results of this study could contribute to the relevant plants adopting TMCH 88 mass% in a process, in order to prevent a fire or explosion accident from happening.     

Application of the partial safety concept for complex non‐linear calculations through the example of Friedrichswerder Church in Berlin

Non‐linear analysis of special structures is routine practice in every engineering design office. Current code provisions provide no sufficient regulations or clear procedures on how to use partial safety factors in non‐linear analyses. The present paper introduces some specific problems of masonry structures from practice. Limit state functions of vertically loaded masonry walls were investigated. A reliability study shows that the decisive case of verification can be obtained by considering a special combination of material parameters. The study also indicates the importance of considering a partial factor for the elastic modulus to account for stability failure. This proposed procedure has been applied to a practical example, the Friedrichswerder Church. The stability of the church has been checked with many FEM models at the macro level.     

Method for Tungsten Grain Size Analysis in Coiled Lamp Filaments

A method of tungsten grain size analysis in coiled lamp filaments has been developed. It is shown to be a valuable tool in design and optimization of heat treatment schedules, predictions of sag rates, failure analyses as well as standardization and benchmarking of non-sag tungsten grain structure in coiled lamp filaments. The procedure consists of two measurements on a polished and etched cross-section of a lamp coil: a number of observed “grains” and a number of examined turns. The resulting figure of merit, a grain-per-turn ratio, provides a useful relative measure of grain size (grain aspect ratio) in recrystallized non-sag tungsten lamp coils. The method permits rapid measurement, does not require any special instrumentation, and is performed directly from a stage of a standard light microscope.     

Evaluation of fundamental and functional properties of natural plant product powders for direct compaction based on multivariate statistical analysis

Direct compaction (DC) is the preferred choice for tablet manufacturing; however, its application in natural plant product (NPP) tablets is still extremely immature. In this study, NPP powders prepared by three commonly used methods were evaluated on their suitability for DC. Extensive characterizations of their physical properties were performed. Multivariate statistical analysis was utilized to explore the influence of preparation technology on the properties of NPP powders and identify the dominating factors that influence their DC properties. The results demonstrated that (i) the 27 kinds of model NPP powders selected randomly in this study could to some degree represent most NPP powders used in actual production; (ii) ～81.5% of the NPP powders exhibited both poor compactibility and flowability, and none of the NPP powders could be compacted into tablets via DC; (iii) the physical properties of NPP powders prepared by direct pulverization were significantly different from those of extracted ones, while there were no significant differences between the water and ethylalcohol extracted ones; and (iv) the DC properties of NPP powders could be improved through controlling some physical properties (e.g., density, particle size, morphology, and texture parameters) reasonably. Overall, this study comprehensively evaluated the current status and application of NPP powders in DC, and is significant in facilitating the development and modernization of NPPs through DC.