Uncertainty driven service cost estimation for decision support at the bidding stage

Service cost estimation attempts to predict future costs associated to the design and delivery of services that support goods and equipment or the actions of customers. In particular, the bidding stage poses challenges due to the uncertainties that are experienced originating from lack of information and knowledge about service requirements. This research paper presents and analyses the benefits of using the Uncertainty Tool for Assessment and Simulation of Cost (U-TASC). U-TASC offers a methodology to improve service cost estimation during the bidding stage of service contracts through a systematic process to identify, evaluate and integrate uncertainty to cost. A case study is applied with three contracting scenarios within a major multinational aerospace organisation. Lessons learnt from the development and evaluation of the U-TASC methodology are used to discuss applications, generalisation potential, limitations and future research potentials.     

Light truck vehicles (LTVs) contribution to rear-end collisions

Light truck vehicles (LTVs), comprising light-duty trucks, vans, and sport-utility vehicles (SUVs) drive higher and wider than passenger cars which could affect the visibility for the following passenger car driver. This paper investigates the contribution of LTVs to rear-end collisions resulting from horizontal visibility blockage using the University of Central Florida sophisticated reconfigurable driving simulator. Indeed, a sudden stop of a leading LTV, in the shadow of the blindness of the succeeding passenger car driver, may deprive the latter of a sufficient response time, which may lead to high probability of a rear-end collision. To investigate this issue, two scenarios were developed in the UCF driving simulator. The first scenario serves as a base scenario where the simulator car follows a passenger car, and the second scenario serves as a test scenario, where the simulator car follows an LTV. The results obtained by comparing the scenarios showed that LTVs produce more rear-end collisions at unsignalized intersections due to horizontal visibility blockage and due to the resulting drivers' behavior when driving behind an LTV.     

Quality of traffic flow on urban arterial streets and its relationship with safety

The two-fluid model for vehicular traffic flow explains the traffic on arterials as a mix of stopped and running vehicles. It describes the relationship between the vehicles’ running speed and the fraction of running vehicles. The two parameters of the model essentially represent ‘free flow’ travel time and level of interaction among vehicles, and may be used to evaluate urban roadway networks and urban corridors with partially limited access. These parameters are influenced by not only the roadway characteristics but also by behavioral aspects of driver population, e.g., aggressiveness. Two-fluid models are estimated for eight arterial corridors in Orlando, FL for this study. The parameters of the two-fluid model were used to evaluate corridor level operations and the correlations of these parameters’ with rates of crashes having different types/severity. Significant correlations were found between two-fluid parameters and rear-end and angle crash rates. Rate of severe crashes was also found to be significantly correlated with the model parameter signifying inter-vehicle interactions. While there is need for further analysis, the findings suggest that the two-fluid model parameters may have potential as surrogate measures for traffic safety on urban arterial streets.     

Sedimentological and petrophysical characteristics of Raha Formation at Wadi Tubia,Northern Gulf of Aqaba,Sinai, Egypt

The main aim of this study is to shed some light on the microfacies association, geochemistry and petrophysical properties of the rock types: dolomite, sandstone, shale and limestone forming the Raha Formation.The microfacies association includes: ferroan dolomite, sublithic arenite, ferruginous sublithic arenite, dolomitic lithic arenite, sandy bioclastic wackstone, bioclastic packstone, calcareous ferruginous lithic arenite and fossiliferous bioclastic grainstone.The depositional environments of these sediments are interpreted as restricted, shelf lagoon and open circulation.The dominant diagenetic processes presented in the studied samples are cementation, compaction, replacement, dissolution and dolomitization in sandstone rocks, while neomorphism, micritization, cementation, dolomitization, compaction and dissolution are present in carbonate facies. Geochemically, the ferruginous sublithic arenite microfacies are characterized by phosphate bands and high chemical weathering. Calcareous ferruginous lithic arenite microfacies are characterized by high concentration of iron oxides and fossiliferous bioclastic grainstone is characterized by high concentration of barium, as indicated from the chemical index of alteration (CIA).Statistical analysis of the measured petrophysical data shows that, the dolomitic lithic arenite and fossiliferous bioclastic grainstone microfacies have a good storage capacity in the Raha Formation of Wadi Tubia, Northern Gulf of Aqaba, Sinai, Egypt.     

Coating of 6028 Aluminum Alloy Using Aluminum Piston Alloy and Al-Si Alloy-Based Nanocomposites Produced by the Addition of Al-Ti5-B1 to the Matrix Melt

The Al-12 pctSi alloy and aluminum-based composites reinforced with TiB₂ and Al₃Ti intermetallics exhibit good wear resistance, strength-to-weight ratio, and strength-to-cost ratio when compared to equivalent other commercial Al alloys, which make them good candidates as coating materials. In this study, structural AA 6028 alloy is used as the base material. Four different coating materials were used. The first one is Al-Si alloy that has Si content near eutectic composition. The second, third, and fourth ones are Al-6 pctSi-based reinforced with TiB₂ and Al₃Ti nano-particles produced by addition of Al-Ti5-B1 master alloy with different weight percentages (1, 2, and 3 pct). The coating treatment was carried out with the aid of GTAW process. The microstructures of the base and coated materials were investigated using optical microscope and scanning electron microscope equipped with EDX analyzer. Microhardness of the base material and the coated layer were evaluated using a microhardness tester. GTAW process results in almost sound coated layer on 6028 aluminum alloy with the used four coating materials. The coating materials of Al-12 pct Si alloy resulted in very fine dendritic Al-Si eutectic structure. The interface between the coated layer and the base metal was very clean. The coated layer was almost free from porosities or other defects. The coating materials of Al-6 pct Si-based mixed with Al-Ti5-B1 master alloy with different percentages (1, 2, and 3 pct), results in coated layer consisted of matrix of fine dendrite eutectic morphology structure inside α-Al grains. Many fine in situ TiAl₃ and TiB₂ intermetallics were precipitated almost at the grain boundary of α-Al grains. The amounts of these precipitates are increased by increasing the addition of Al-Ti5-B1 master alloy. The surface hardness of the 6028 aluminum alloy base metal was improved with the entire four used surface coating materials. The improvement reached to about 85 pct by the first type of coating material (Al-12 pctSi alloy), while it reached to 77, 83, and 89 pct by the coating materials of Al-6 pct Si-based mixed with Al-Ti5-B1 master alloy with different percentages 1, 2, and 3 pct, respectively.     

Microbiological aspects and challenges of whey powders – I thermoduric,thermophilic and spore-forming bacteria

For dairy processors, spoilage and pathogenic spore-forming bacteria are key sources of concern, not only due to their ability to remain dormant in a desiccated state in powders and to survive heat treatments, but also their ability to form biofilms in the vegetative state that lead to contamination of foods. These include members of the genera Bacillus, Geobacillus, Anoxybacillus, Brevibacillus, Paenibacillus and Clostridium, many of which are associated with food poisoning and spoilage. Here, we review the common bacterial species that form spores in whey powders and their sources and provide insights into their risks and strategies to control them.     

Recent advances in whey processing and valorisation: Technological and environmental perspectives

Whey has several environmental risks if disposed of as waste in watercourses. However, there are numerous valorisation techniques to convert it into valuable and highly nutritious products. Techniques such as membrane filtration may be utilised, but these are not applicable to all categories of whey. Novel methodologies that are agile enough to deal with whey variability can produce valorised products. This review assesses the capability of whey processing techniques, applications and methodologies, discussing pertinent research that can innovate product development further. It focuses on environmental impacts of whey as a waste and ways of minimising it.     

Optimizing the distributed generators integration in electrical distribution networks: efficient modified forensic-based investigation

Neural Computing and Applications - As a result of various loads, including critical installations (industries, nuclear facilities, etc.), electrical distribution networks (EDNs) must operate...     

Modified Differential Evolution Algorithm for Solving Dynamic Optimization with Existence of Infeasible Environments

Dynamic constrained optimization is a challenging research topic in which the objective function and/or constraints change over time. In such problems, it is commonly assumed that all problem instances are feasible. In reality some instances can be infeasible due to various practical issues, such as a sudden change in resource requirements or a big change in the availability of resources. Decision-makers have to determine whether a particular instance is feasible or not, as infeasible instances cannot be solved as there are no solutions to implement. In this case, locating the nearest feasible solution would be valuable information for the decision-makers. In this paper, a differential evolution algorithm is proposed for solving dynamic constrained problems that learns from past environments and transfers important knowledge from them to use in solving the current instance and includes a mechanism for suggesting a good feasible solution when an instance is infeasible. To judge the performance of the proposed algorithm, 13 well-known dynamic test problems were solved. The results indicate that the proposed algorithm outperforms existing recent algorithms with a margin of 79.40% over all the environments and it can also find a good, but infeasible solution, when an instance is infeasible.