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Precast concrete inlay panels (PCIPs) are a new rapid repair technique developed to address deep-seated rutting issues in asphalt pavements. Providing a uniform, stable support layer for precast concrete pavement is critical to its performance, and constructibility of this support is a key factor in the feasibility of PCIPs as an overnight repair technique. Three methods of PCIP support (asphalt supported, grade supported, and grout supported) were developed, designed, and constructed in a trial installation in Ontario, Canada. An analytic hierarchy process (AHP) analysis was performed to evaluate the performance of the options based on four construction-related criteria: cost, installation rate, repeatability, and resiliency. Input from the construction contractor and the Ministry of Transportation of Ontario was considered. This paper describes the support options, trial construction operations, and AHP evaluation. The results indicate that the grout-supported condition is most favorable and is recommended for future applications of PCIP for conditions similar to the trial section. [ABSTRACT FROM AUTHOR]

Abstract Polybrominated diphenyl ethers (PBDEs) were widely used as flame retardants in consumer products including electronic devices. Important routes of human exposure are contaminated food and contact with dust. In this study, we measured twelve PBDEs in household/workplace dust and blood plasma samples provided by 113 volunteers living in the Puget Sound region, WA and working at electronic waste (E-waste) recycling sites (n = 29) or non-specific indoor (n = 57) or outdoor occupations (n = 27). The volunteers in the outdoor group were also selected because of a history of high seafood consumption habits. Results indicated the sum PBDE levels varied between <2.5 and up to 310 ng g−1 lipid. E-waste recyclers were predominantly men, generally consumed low amounts of seafood, and had PBDE blood levels (geometric mean, GM = 26.56 ng g−1 lipid) that were similar to indoor workers (GM = 27.17 ng g−1 lipid). The sum PBDE levels were highest in the outdoor group (GM = 50.63 ng g−1 lipid). Dust samples from E-waste sites were highly enriched with BDE-209 and BDE-153 relative to non-E-waste businesses and homes. The concentrations of these BDE congeners in dust at E-waste sites were ∼32–39 times higher than in dust from other sites. However, the detection rate of BDE-209 in plasma was low across all groups (13%) and no statistical comparisons were made. Our results suggest that E-waste recyclers in this study population did not have elevated PBDE levels in comparison to volunteers working in other types of occupations. Graphical abstract Image 1 Highlights • High seafood eaters had higher plasma ∑PBDE levels than low seafood eaters. • E-waste workers had plasma PBDE levels similar to non-E-waste indoor workers. • Male volunteers had higher plasma ∑PBDEs and BDE-153 than female volunteers. • Dust PBDEs was 32–39 times higher at E-waste sites than home or non-E-waste sites. [ABSTRACT FROM AUTHOR]

Currently, concurrent programs are becoming increasingly widespread to meet the demands of the rapid development of multi-core hardware. However, it could be quite expensive and challenging to guarantee the correctness and efficiency of concurrent programs. In this paper, we provide a systematic review of the existing research on fighting against concurrency bugs, including automated concurrency bug exposing, detection, avoidance, and fixing. These four categories cover the different aspects of concurrency bug problems and are complementary to each other. For each category, we survey the motivation, key issues, solutions, and the current state of the art. In addition, we summarize the classical benchmarks widely used in previous empirical studies and the contribution of active research groups. Finally, some future research directions on concurrency bugs are recommended. We believe this survey would be useful for concurrency programmers and researchers. [ABSTRACT FROM AUTHOR]

Vehicular Ad Hoc Networks (VANET) in the large-scale road section usually have typical characteristics of large number of vehicles and unevenly distribution over geographic spaces. These two inherent characteristics lead to the unsatisfactory performance of VANETs. This poor performance is mainly due to fragile communication link and low dissemination efficiency. We propose a novel routing mechanism to address the issue in the paper, which includes a competition-based routing discovery with priority metrics and a local routing repair strategy. In the routing discovery stage, the algorithm uses adaptive scheme to select a stable route by the priorities of routing metrics, which are the length of each hop, as well as the residual lifetime of each link. Comparisons of different ratios over link length and link stability further show outstanding improvements. In the routing repair process, upstream and downstream nodes also compete for the right to establish repair process and to remain as a member of the active route after repair. Our simulation results confirm the improved performance of the proposed algorithm. [ABSTRACT FROM AUTHOR]

We study a single server queuing system with arrivals in batches of variable size and general service in three fluctuating modes with different mean service rates. It is assumed that just after completion of the previous service or just after completion of repairs or just after arrival of a fresh batch of customers at a time when the system is in an idle state, the service to next customer may start in mode j with probability pj where j = 1,2,3 Σ3j=1 pj = 1. The system is assumed to be subject to random failures with the general repair time distribution. The system is equipped with a stand-by server which operates only during the breakdown periods of the system. We further assume that an arriving batch may balk and leave the system as soon as it arrives or may join the system. The balking rates have been assumed to be different during the working periods or the breakdown periods of the main server. Steady state results for the queue size distribution at a random epoch have been obtained explicitly. Probabilities of the idle state as well as the utilization factor of the system have been found explicitly. Many particular cases of interest are discussed. [ABSTRACT FROM AUTHOR]

An s - t-network with highly reliable edges with repair and variable external load is considered. A fast simulation method is proposed to evaluate the probability of functional failure when the real capacity of the network is less than the required capacity. It is proved that under some conditions the estimate has a bounded relative error as edges reliability increases. The numerical example illustrates the efficiency of the method. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, the transient behavior dealing with a two-processor heterogeneous system with catastrophes, server failures and repairs is investigated, where tasks arrive according to a Poisson process and execution times are exponentially distributed. Each task requires exactly one processor for its execution and the scheduling policy is FCFS. For this model, the exact time dependent solutions of system size probabilities are obtained using the generating function technique. An explicit expression is also found for the time dependent mean and variance of the system size distribution .Moreover, the current system may be regarded as an extension to some previous studies such as that Dharmaraja [4]. Finally, numerical illustrations are used to discuss the system behavior. [Copyright &y& Elsevier]

Repairing a plan executed in a partially observable environment is a challenging task; especially when the plan to be repaired is part of a Multiagent Plan (MAP), and hence the synchronization among the agents further constrains the repair process. The paper formalizes a local plan repair strategy, where each agent in a MAP is responsible for controlling (monitoring and diagnosing) the actions it executes, and for autonomously repairing its own plan whenever an action failure is detected. The paper also describes how to mitigate the impact of an action failure on the plans of other agents when the local recovery strategy fails. [ABSTRACT FROM AUTHOR]

n operating system is subject to random shocks that arrive according to a non-homogeneous Poisson process and cause the system failed. System failures experience to be divided into two categories: a type-I failure (minor), rectified by a minimal repair; or a type-II failure (catastrophic) that calls for a replacement. An age-replacement model is studied by considering both a cumulative repair-cost limit and a system's entire repair-cost history. Under such a policy, the system is replaced at age T, or at the k-th type-I failure at which the accumulated repair cost exceeds the pre-determined limit, or at any type-II failure, whichever occurs first. The object of this article is to study analytically the minimum-cost replacement policy for showing its existence, uniqueness, and the structural properties. The proposed model provides a general framework for analyzing the maintenance policies, and presents several numerical examples for illustration purposes. [ABSTRACT FROM AUTHOR]

Abstract: This paper considers a finite buffer M/M/c queueing system in which servers are unreliable and follow a (d, c) vacation policy. With such a policy, at a service completion instant, if the number of customers is reduced to c − d (c > d), the d idle servers together take a vacation (or leave for a random amount of time doing other secondary job). When these d servers return from a vacation and if still no more than c − d customers are in the system, they will leave for another vacation and so on, until they find at least c − d +1 customers are in the system at a vacation completion instant, and then they return to serve the queue. This study is motivated by the fact that some practical production and inventory systems or call centers can be modeled as this finite-buffer Markovian queue with unreliable servers and (d, c) vacation policy. Using the Markovian process model, we obtain the stationary distribution of the number of customers in the system numerically. Some cost relationships among several related systems are used to develop a finite search algorithm for the optimal policy (d, c) which maximizes the long-term average profit. Numerical results are presented to illustrate the usefulness of such a algorithm for examining the effects of system parameters on the optimal policy and its associated average profit. [Copyright &y& Elsevier]