THE IMPACT OF ASPHALTENES REMOVAL ON THE KINETICS OF RESIDUUM HYDROTREATING

Iraqi reduced crude (above 350°C) prepared in a laboratory distillation unit containing 15 trays was solvent deasphaltened at specified conditions using n-heptane as the precipitant Both the original and deasphaltened reduced crude was hydrotreated on a commercial Ni-Mo- alumina catalyst in a laboratory trickle bed reactor. This investigation was undertaken to understand the role of asphaltenes removal in the kinetics of the desulphurization, demetallization and deasphaltening processes. Kinetic analysis showed that the hydrotreating reactions of the deasphaltened reduced crude followed a first order kinetics. Rate constants calculated for the above reactions are higher than those obtained in the HDS process for the original full residuum.     

A numerical study to investigate the influence of surface roughness and boundary condition on the shear behaviour of rock joints

Bulletin of Engineering Geology and the Environment - The shear behaviours of rock joints with and without rock bolt support are numerically studied using the discrete element code PFC2D. A...     

Ring-Shaped Lateral Bracing System for Steel Structures

Buckling of compression members has a great impact on the reduction of energy dissipation capacity and ductility of the structural system such as concentrically braced frame systems (CBFs). As well, direct connection of tensile and compression members to beams and designation of the link beam as a fuse, and the formation of plastic hinges in the link beam in eccentrically braced systems (EBFs) endanger the safety of this type structural systems. This paper introduces a new ring-shaped lateral bracing system so-called the Shami lateral bracing system (SLBs) which removes the common tensile and compressive members along with their connections to the structure. As a substitute, SLBs introduces a new element with proper ductility and energy dissipation capacity and could be an appropriate alternative to the existing systems. Because of the high degree of statically indeterminacy of the proposed system, the structural stiffness does not lead to a steep reduction after the formation of the first plastic hinge. The performance of this lateral system is evaluated by numerical modeling, and the results show that the structures resist against the lateral loads with acceptable seismic performance. It seems that this system in comparison with CBF and EBF systems may not be cost-effective for bending of the ring, welding, etc., but from the seismic performance points of view, it has good performance.     

A MANET‐based semantic traffic management framework for ubiquitous public safety networks

A global trend toward large scale emergencies has placed an emphasis on the achievement of a ubiquitous public safety network. Such a network may be realized over a mobile ad hoc network formed by the handheld mobile devices. Therefore, traffic in the network can be user generated and thus semantic. Unfortunately, none of the traffic management techniques proposed for the underlying network considers the semantic properties of the generated traffic. Therefore, in this paper, we propose a semantic traffic management framework which has two modules: traffic monitoring unit and traffic reduction unit. Although the first module analyzes the semantic traffic to detect an emergency, the latter module removes redundant semantic information for traffic reduction. We have supported the feasibility of the proposed semantic framework through simulation. Simulation results suggest that the framework is capable of accurate and early detection of an emergency as well as traffic reduction while keeping sufficient information to report the emergency. Copyright © 2012 John Wiley & Sons, Ltd.     

The Effect of the Relief Wave on the Uniformity of an Air Blast Load

In most blast loading structure analyses, it is assumed that the load acts uniformly on a target area. For the rationable design, it is useful to have a quantitative criterion to determine at which maximum distance the standoff can be placed to assume a uniform pressure distribution. Surprisingly, no standard criterion was found in the literature and the effect of blast wave clearing was not considered as well. In this paper, pressure histories applied on structures are calculated considering the non‐uniform loading characteristic as well as pressure relief from the edges. Additionally, the effects of various parameters on uniformity of impulse distribution are investigated. The results have shown that the effect of pressure relief on impulse uniformity is very important, especially when the blast wave is attenuated. This phenomenon leads an optimum distance at which impulse distribution is the most uniform.     

Optimizing convexity defect in a tile industry using fuzzy goal programming

In most designed experiments, the main focus is to find the factor settings that optimize a quality response regardless of engineer’s preferences about factor settings. Further, in tiles industry convexity defects result in huge quality costs as well as production losses. This research, therefore, aims at optimizing convexity defect while considering process engineers’ preferences using fuzzy goal programming (FGP). Three two-level key process factors are considered, including below-rollers temperature, above-rollers temperature, direct blow air. Experiments are conducted with two repetitions; in each the convexity is measured on four tiles. Two optimization techniques are employed to determine the combination of optimal factor settings, including the Taguchi method and latter technique. The Taguchi approach and FGP approach provide relative improvements of 61.2% and 41.2%, respectively. Although the former technique reduces convexity larger than latter approach, it failed to satisfy the preferences on the settings of process factors. In contrast, the optimal factor settings obtained using FGP completely satisfy engineers’ preferences. In conclusion, FGP successfully optimizes process performance and completely satisfies process engineers’ preferences in tiles industry.     

Some Properties of Electroless Ni-P,Co-P,and Ni-Co-P Deposits

The electroless deposition of Ni-P, Ni-Co-P and Co-P alloys has been investigated. The effects of pH on the chemical composition of the deposits and the induced stresses have been explored. The magnetic and electrochemical properties and the mechanical hardness of the deposits have been studied after annealing at various temperatures and are related to the crystal structures.     

An investigation into the effects of lime on compressive and shear strength characteristics of fiber-reinforced clays

To meet the ever-increasing construction demands around the world during recent years,reinforcement and stabilization methods have been widely used by geotechnical engineers to improve the performances and behavior of fine-grained soils.Although lime stabilization increases the compressive strength of soils,it reduces the soil ductility at the same time.Recent research shows that random fiber inclusion modifies the brittleness of soils.In the current research,the effects of lime and polypropylene(PP) fiber additions on such characteristics as compressive and shear strengths,failure strain,secant modulus of elasticity(E_(50)) and shear strength parameters of mixtures were investigated.Kaolinite was treated with 1%,3% and 5% lime by dry weight of soil and reinforced with 0.1% monovalent PP fibers with the length of 6 mm.Samples were prepared at optimum conditions and cured at 35℃ for 1 d,7 d and28 d at 90% relative humidity and subsequently subjected to uniaxial and triaxial compression tests(UCT and TCT) under cell pressures of 25 kPa,50 kPa and 100 kPa.Results showed that inclusion of random PP fibers to clay-lime mixtures increases both compressive and shear strengths as well as the ductility.Lime content and curing period were found to be the most influential factors.Scanning electron microscopy(SEM) analysis showed that lime addition and the formation of cementitious compounds bind soil particles and increase soil/fiber interactions at interface,leading to enhanced shear strength.The more ductile the stabilized and reinforced composition,the less the cracks in roads and waste landfill covers.     

Normalised availability importance measures for complex systems

Once the performance characteristics of a system have been determined, engineers are often faced with the task of identifying the critical components. The objective of this identification is to prioritise improvements in the systems and the efforts to bring these about in the areas that will have the most effect on the system’s performance. Availability is an important metric, used to assess the performance of complex systems. Having the availability importance measure (AIM), which determines the importance of items regarding the availability of the system, can help designers and managers to improve performance and minimise the life cost of the system. This paper has developed an AIM for complex systems. Thereafter, the application of the developed importance measure is illustrated by a case study.