The Investigation of an Efficient and Effective Proactive Pipeline Integrity System

In this paper, we propose the investigation of an efficient and effective proactive pipeline integrity system that uses multi-sensors for monitoring and inspection of the pipeline. Although the focus is on the pipeline, the methodologies will also be applicable for other systems including other energy infrastructure elements. The investigation focuses on the integration of multi-sources of data as well as multi-types of data for the same location (section) of the pipeline. The data include imaging, acoustic signals, electromagnetic flux system, and others. Moreover, the data could be obtained using continuous monitoring of the pipeline sections or through time intervals. In both cases, the data may also include censored observations. We develop several approaches to filter the data for noise and identify outliers, integrate the data streams into one degradation path and determine the optimum time to maintain or replace the pipeline sections being monitored. It will utilize extensive mathematical modeling for condition-based maintenance and repair, which will be developed by the investigators of this proposal. Following the suggestions of one of the reviewers of the last year's submission, we plan to validate and modify the model using standard or artificially developed defects such as corrosion, cracks, stress cracking, etc. to understand the output of the proposed methodology and validate the models accordingly

Using Electrospinning Technique for Preparation of Cobalt Hydroxide Nanoparticles

Cobalt hydroxide or cobaltous hydroxide or cobaltous hydrate, has attracted increasing attention in recent years because of its novel electric and catalytic properties and important technological applications, for examples in advanced batteries, supercapacitors, solar cells, electrochromics, as an oil additive, it can improve tribological properties [1,2], etc. Cobalt hydroxide nanoparticles were prepared via in-situ electrospinning. Thus, electrospinning of polyethylene oxide solution with different cobalt nitrate concentrations were carried out in gaseous ammonia atmosphere. The reaction of cobalt nitrate with ammonia produces cobalt hydroxide. The reaction occurs during fiber formation. Transmission Electron Microscopy (TEM) showed that cobalt hydroxide Co(OH)2 nanoparticles were formed on the produced nanofibers of 100-600 nm in diameter. The existence of the formed Co(OH)2 was also proven by X-ray Diffraction (XRD) analysis and it showed that the Co(OH)2 nanoparticles were produced. Thermogravimetric Analysis (TGA) results also confirmed the presence of Co(OH)2 within the fibers. Experimental Section Co(NO3)2.6H2O (supplied by Merck Chemical Co.) with different concentrations was dissolved in 100 mL distilled water to produced Co+2 solution. Then, the following seven experiments (Exp. G1, G2, G3, G4, G5 (collectively called G-series in this article), P, and N) were carried out. G-series: 4.0 g of polyethylene oxide (with weight average molecular weight of 600,000 g/mol and supplied by Acros Organics Co.) was added to 100 mL of above mentioned cobalt nitrate solution with different concentrations (given in Table I) and left for two nights to obtain a homogenous PEO solution having cobalt ions. The polymer solution was put into a hypodermic syringe. A syringe pump (Stoelting Co., USA) was used to feed the polymer solution into a metallic needle with an inner diameter of 0.7 mm. A grounded aluminum foil as collector was placed at a fixed distance of 18 cm from the needle. The metallic needle and the collector were enclosed in a polymethyl metacrylate box (40?50?60 cm). The feed rate of the syringe pump was fixed at 0.7 mL/h. A positive potential of 18 kV was then applied to the polymer solution using a high-voltage power supplier (HV35P series, Fnm Co., IR) with a maximum voltage of 35 kV. During electrospinning, gaseous ammonia (from a cylinder purchased from Merck Chemical) was purged into the box with a rate of 10 L/min. Electrospun nanofibers were collected on the surface of the grounded aluminum foil. Results and Discussion A comparison of the appearance (color change) of the mats obtained from G-series with that of the P fiber mat suggested that the cobalt ions in the jet traveling the distance between the needle and the collector could precipitate in the gaseous ammonia atmosphere to produce cobalt hydroxide. In other words, in this process, one reaction occurs during fiber formation: the reaction of Co+2 ions with NH3 which produces Co(OH)2 nanoparticles on the nanofibers. Cobalt (II) hydroxide is obtained as a precipitate when an alkaline hydroxide is added to an aqueous solution of cobalt (II) salt. Since the reaction of nanoparticle formations occurs during fiber formation in electrospinning process, the precipitated nanoparticles have special morphology and crystalline structures (due to the applied voltage, elongation, etc.). Figure 1 displays the TEM images of fibers obtained from Exp. G1 (electrospinning of polyethylene oxide solution having 2.5% Co+2 based on PEO, in ammonia atmosphere) and as it shows, dark spots of Co(OH)2 are heterogeneously dispersed on the fibers. These TEM images suggest that in the Exp. G1, Co(OH)2 nanoparticles were heterogeneously synthesized on fibers through the reaction of cobalt ions with NH3. Fig.1 TEM images of nanofibers obtained from Exp. G1. Ref. Zhang, L.; Dutta, A.K.; Jarero, G.; Stroeve, P. Nucleation and growth of cobalt hydroxide crystallites in organized polymeric multilayers. Langmuir, 2000, 16, 7095. Patnaik, P.; Handbook of Inorganic Chemicals, McGraw-Hili, New York, 2002.qscienc

Safety performance of school buses in the State of Qatar

School buses and minibuses are one of the major modes of traveling for students in the state of Qatar. Many studies pointed to the fact that school buses travelling are safer for students than walking or car riding (Bolte, et al., 2000; Hinch, et al., 2002). For that reason, safety measures and performance of school buses in the State of Qatar should be studied and evaluated carefully and wisely. The project aims were done through merged qualitative and quantitative methods. Initially a safety checklist was constructed for school buses and a comprehensive schools map to evaluate of the current safety measures in school buses and to understand the conditions around the surrounding areas like the location of the bus stops and the availability of signage. Then, the second step focuses on conducting a survey for school bus drivers, school bus guides, students, and parents. Finally, the third steps compares between the school bus safety strategies followed in the State of Qatar and the strategies followed in other high income countries. The results of the field visits revealed many very important statistics for all surveys on the safety of school bus and the surrounding areas as well as the behavior of students and drivers. The results revealed that most of the parents are not happy with the safety while loading and unloading and with the safety procedures. In addition, 43% of school bus users didn't attend any training or workshops about the safety procedures in school bus. References: [1] Bolte, K. et al., 2000. Simulations of Large School Bus Crashes. [Online] Available at: http://papers.sae.org/2000-01-0469/ [Accessed 10 october 2014]. [2] Hinch, J. et al., 2002. School Bus Safety: Crashworthiness Research, Washington: National Highway Traffic Safety Administration.Qscienc

Multiple parts process planning in serial–parallel flexible flow lines: part II—solution method based on genetic algorithms with fixed- and variable-length chromosomes

Multiple parts process planning (MPPP) is a hard optimization problem that requires the rigor and intensity of metaheuristic-based algorithms such as simulated annealing and genetic algorithms. In this paper, a solution method for this problem is developed based on genetic algorithms. Genetic algorithms solve problems by exploring a given search space. To do this, a landscape over which the search traverses is constructed based on a number of algorithm choices. Key algorithm choices include (a) type of chromosome representation, which affects the efficiency of an algorithm, and (b) type and form of genetic operators, which affect the effectiveness of an algorithm. More specifically, the suitability of a variable-length chromosome (VLC) representation for encoding a solution to a MPPP problem is investigated. The effectiveness and efficiency of implementing the VLC algorithm is analyzed and compared with: (a) the commonly used fixed-length chromosome representation, (b) a variant of the simulated annealing algorithm, and (c) a knowledge-informed simulated annealing algorithm. The scalability of the algorithms is analyzed and their effectiveness demonstrated by experimental results based on four problem sizes. Obtained results show that, although there are variances in performances, all algorithms investigated are capable of obtaining good solutions. In addition, variances were observed for different aspects of the MPPP problem. The results indicate that the VLC algorithm is effective in solving MPPP problems that consider multiple aspects in the search for optimal process planning solutions

Influence of Micron-Ti and Nano-Cu Additions on the Microstructure and Mechanical Properties of Pure Magnesium

In this study, metallic elements that have limited/negligible solubility in pure magnesium (Mg) were incorporated in Mg using the disintegrated melt deposition technique. The metallic elements added include: (i) micron sized titanium (Ti) particulates with negligible solubility; (ii) nano sized copper (Cu) particulates with limited solubility; and (iii) the combination of micro-Ti and nano-Cu. The combined metallic addition (Ti + Cu) was carried out with and without preprocessing by ball-milling. The microstructure and mechanical properties of the developed Mg-materials were investigated. Microstructure observation revealed grain refinement due to the individual and combined presence of hard metallic particulates. The mechanical properties evaluation revealed a significant improvement in microhardness, tensile and compressive strengths. Individual additions of Ti and Cu resulted in Mg-Ti composite and Mg-Cu alloy respectively, and their mechanical properties were influenced by the inherent properties of the particulates and the resulting second phases, if any. In the case of combined addition, the significant improvement in properties were observed in Mg-(Ti + Cu)BM composite containing ball milled (Ti + Cu) particulates, when compared to direct addition of Ti and Cu particulates. The change in particle morphology, formation of Ti3Cu intermetallic and good interfacial bonding with the matrix achieved due to preprocessing, contributed to its superior strength and ductility, in case of Mg-(Ti + Cu)BM composite. The best combination of hardness, tensile and compressive behavior was exhibited by Mg-(Ti + Cu)BM composite formulation

Age replacement models: A summary with new perspectives and methods

Age replacement models are fundamental to maintenance theory. This paper summarizes our new perspectives and hods in age replacement models: First, we optimize the expected cost rate for a required availability level and vice versa. Second, an asymptotic model with simple calculation is proposed by using the cumulative hazard function skillfully. Third, we challenge the established theory such that preventive replacement should be non-random and only corrective replacement should be made for the unit with exponential failure. Fourth, three replacement policies with random working cycles are discussed, which are called overtime replacement, replacement first, and replacement last, respectively. Fifth, the policies of replacement first and last are formulated with general models. Sixth, age replacement is modified for the situation when the economical life cycle of the unit is a random variable with probability distribution. Finally, models of a parallel system with constant and random number of units are taken into considerations. The models of expected cost rates are obtained and optimal replacement times to minimize them are discussed analytically and computed numerically. Further studies and potential applications are also indicated at the end of discussions of the above modelsScopu

Microstructure and Mechanical Properties of Mg-5Nb Metal-Metal Composite Reinforced with Nano SiC Ceramic Particles

In this work, a Mg-5Nb metal–metal composite was reinforced with nano SiC (SiCn) ceramic reinforcement of varying volume fractions, using the disintegrated melt deposition technique. The extruded Mg-5Nb-SiCn composites were characterized for their microstructure and mechanical properties. Based on the results obtained, it was observed that the volume fraction of nano-SiC reinforcement played an important role in determining the grain size and improving the mechanical properties. A comparison of properties with those of pure Mg and Mg-5Nb composite showed that while the improvement in hardness occurred at all volume fractions, a minimum volume fraction of ~0.27% SiCn was required to increase the tensile and compressive strengths. The observed mechanical response of the composites were investigated in terms of the effect of SiCn volume fraction, processing, distribution of metallic and ceramic reinforcements and the inherent properties of the matrix and reinforcements. The influences of these factors on the mechanical behavior of the composites are understood based on the structure–property relationship

Simulation and experimental study of underwater dissimilar friction-stir welding between aluminium and steel

The volume of fluid (VOF) modeling method was implemented to simulate the underwaterfriction-stir welding (FSW) process for dissimilar joining between aluminum and steel. Tem-perature profile, materials flow, and intermixing during dissimilar bonding under the coolingmedium were monitored via VOF modeling and verified according to experimental data. Theeffects of processing parameters on the formation of intermetallic compounds (IMCs) atthe Al/St interface, microstructural characteristics, and mechanical property of dissimilarweldments were studied and addressed. By decreasing tool rotational speed (w), increas-ing traverse velocity (v), and employing cooling medium, peak temperature continuouslyreduced (down to ?473 and 573 K for the aluminum and steel sides, respectively) led to sub-stantial refining the grain structure and formation of a thinner IMC layer. The average grainsize in the aluminum and steel sides of SZ is refined down to ?4 and 12-m, respectively. Thethickness of the IMC layer varied depending on the processing parameters with the lowestvalue of ?0.2-m. The formation of a curved interface due to enhanced materials mixing atthe advancing side is noted with a linear hardness gradient across the dissimilar weldment.Superior mechanical strength of ?80 MPa attained at an optimized submerged condition ofw = 1650 rpm/v = 40 mm/min showed combined ductile-brittle fractographic aspects on thefracture surface. 2020 The Authors. Published by Elsevier B.V.Scopu

Reliability estimation of load sharing capacity-c-out-of-n pairs:G Balanced system

In many cases, systems are required to provide a specified capacity such as the case of power distribution system. A system fails when its capacity does not meet the required minimum capacity. In this paper, we investigate reliability estimation of capacity-c-out-of-n pairs:G Balanced systems which consist of units in a balanced spatial configuration. When one of the units fails its load is shared among the remaining units. The load shared by each operating unit affects its reliability and hence the system reliability. We incorporate load sharing effect on reliability of individual units into the estimation of system reliability. Higher load sharing has adverse effect on system reliability as demonstrated using a numerical example.Scopu

In situ strengthening of thin-wall structures using pressurized foam

A simple and effective in situ method for strengthening or healing thin-wall structures is presented. In this method, a liquid-state gap-sealing foam is injected within the enclosed spaces of a structure. After injection it expands to fill and pressurize the cavities, then solidifies in few hours. The stiff pressurized foam enhances load carrying capacity both by supporting part of the load, and by retarding the buckling of thin-wall structural components. A simple demonstration of the proposed technique is provided by load-testing thin-wall beverage cans, and also both intact and damaged aluminum honeycomb, filled with commercially available gap-sealing polyurethane foam. By adding foam, the structures' peak load and energy absorption were significantly enhanced. The injected foam partially restored the original undeformed shape during unloading, highlighting the potential advantage to apply this method for multiple-use energy absorbing components.Qatar National Research Foundation (QNRF) Award Number NPRP 09-145-2-061Scopu