Structural changes in catalytic hydroprocessing of syncrude coker gas oil

A method of Structural Group Analysis (SGA) was used to characterize feed and liquid products from catalytic hydroprocessing using a commercial Ni-Mo catalyst. Comparison of the structural profiles revealed significant changes in the concentration of various structural groups. SGA is a promising tool for investigating chemical changes in complex reacting systems.     

Enhancing non-task sociability of asynchronous CSCL environments

While from a technological perspective Computer Supported Collaborative Learning (CSCL) systems have been improved considerably, previous studies have shown that the social aspect of the CSCL is often neglected or assumed to happen automatically by simply creating such virtual learning environments. By distinguishing between students’ non-task social interactions from on-task interactions, and through a content analysis, this paper demonstrates that non-task interactions do occur frequently in CSCL environments. Furthermore, by conducting a self-reported survey, the present study operationalizes non-task sociability of CSCL environments and determines factors that affect them. The findings from the survey revealed that the sense of cohesion and awareness about others significantly impact the non-task sociability of CSCL. Furthermore, the study demonstrates that the perception of self-representation and perception of compatibility affect the sense of cohesion and awareness about others and indirectly contribute to the perceived non-pedagogical sociability of the environment. The findings of this paper can be used in future research for investigating the relationship between the non-task sociability of CSCL and other CSCL factors. The study also provides the CSCL lecturers and facilitators with a conceptual model by which sociability can be explicitly addressed in their course planning and delivery processes. And finally, this study develops and validates an instrument that guides required changes in current CSCL systems to improve the non-task social functionality of the environment.     

Effect of Magnetic Field Dynamics on the Copper‐Constantan Thermocouple Performance

Abstract

This paper presents some results of experimental research addressing the influence of magnetic field dynamics on the copper‐constantan thermocouple performance. There are challenges in measuring temperature by thermocouples in a time‐dependent magnetic field. Although there is considerable experience on the effect of a static magnetic field, there is a lack of awareness of the outcome of a varying field on thermocouple performance. We measured the accuracy of the thermocouple response in an alternating magnetic field for various operational parameters: frequency of the magnetic field, geometry, and length of the thermocouple wire in the field, and magnetic field strength. The effect of each of the operational parameters is discussed. Test results of temperature profile measure by a copper‐constantan thermocouple in a varying magnetic field system that was used in a room temperature magnetic refrigeration test bed are demonstrated.     

Experimental Modeling of Gas–Solid Heat Transfer in a Pipe with Various Inclination Angles

Gas–solid flow in a pipe with different configurations (vertical, horizontal, and inclined positions) is studied experimentally. Air with temperature around 170°C and sand particles with mean diameter of 253 μm are used as gas and solid mediums, respectively. Effects of different parameters (pipe slope and solid particles feed rate) are studied on heat transfer rate between gas and solid particles. The Nusselt number decreases at lower solids feed rate in a dilute regime of the mixture; however, it increases at higher solids feed rates. Furthermore, results show that a higher Nusselt number takes place at the angles closer to 45 degrees.     

Standard ANSI Z9.14: Testing and performance verification methodologies for ventilation systems for Biological Safety Level 3 (BSL-3) and animal Biological Safety Level 3 (ABSL-3) facilities

The American Industrial Hygiene Association (AIHA) and the American National Standards Institute (ANSI) are developing a national standard titled “Testing and performance verification methodologies for ventilation systems for Biological Safety Level 3(BSL-3) and animal Biological Safety Level 3 (ABSL-3) laboratories” known as ANSI/AIHA Z9.14. The ANSI Z9.14 standard will focus on performance verification of engineering controls related specifically to ventilation system features of BSL-3/ABSL-3 facilities. Currently the design of these facilities is largely guided by the criteria defined in successive versions of the Biosafety in Microbiological and Biomedical Laboratories (BMBL),¹ while facilities funded by the National Institutes of Health (NIH) follow BMBL as well as the NIH Design Requirements Manual (DRM).² Among professionals such as architects, engineers, contractors, commissioning agents and owners who are asked to specify or perform tests for performance of ventilation systems in high containment facilities, there is a consensus that there is no comprehensive methodology based on a risk assessment of each individual facility. An extensive literature review was conducted to determine if there are any regulations, standards or guidance available that provide a “methodology” to verify that the ventilation systems in such facilities are performing appropriately for the current or potential future use. This ‘Gap and Needs Analysis’ provides evidence that there is no single resource for a comprehensive testing methodology that can be used uniformly from one facility to another to verify that the ventilation systems in such facilities are performing appropriately. ANSI Z9.14 can provide one component of a more extensive graduated, risk-based approach to reaching containment goals appropriate to the risk of the agent and the laboratory activity.     

Adhesion of tin droplets impinging on a stainless steel plate: effect of substrate temperature and roughness

We photographed impact of small tin droplets on stainless steel surfaces of varying temperature and roughness. To achieve high impact velocities the test surfaces were mounted on the rim of a rotating fly wheel. Substrate temperature (T_s) was varied from 120 to 220 °C and surface roughness (R_a) kept at either 0.05 or 2 µm. We kept constant the impact velocity (30 m/s) and droplet diameter (0.6 mm). To form a coating 60 droplets were deposited randomly on each stainless steel test coupon. Deposition efficiency was evaluated by dividing the mass adhering to the coupon by the mass of sixty droplets prior to impact. The maximum deposition efficiency was achieved at a substrate temperature of 160 °C. For T_s < 160 °C the deposition efficiency was higher on a rough surface (R_a = 2 µm) than on a smooth surface (R_a = 0.05 µm), since splats did not adhere well to the smooth surface. For T_s≥ 160 °C the deposition efficiency was higher on a smooth surface (R_a = 0.05 µm) than on a rough surface (R_a = 2 µm), since splats splashed less on the smooth surface.

© 2003 Elsevier Science Ltd. All rights reserved.     

Investigation of lanthanum and Si/Al ratio effect on the HZSM-5 catalyst efficiency for production of Olefin from Methanol

The effect of lanthanum and Si/Al ratio on catalytic performance of HZSM-5 in methanol to olefin process is investigated in this paper. The catalyst with bases of HZSM-5 is modified using the lanthanum by a wet impregnation producer. The Box-Behnken method, experimental design is used to evaluate effects of lanthanum parameters, Si/Al ratio, temperature and the effect of the interaction between them in methanol to olefin process for production of ethylene and propylene. Finally, the obtained results show the highest yield of ethylene is achieved for high load lanthanum catalyst, low Si/Al ratio and high temperature.     

Analysis of the strain process of soil slope model during infiltration using BOTDA

Rainfall infiltration can be a major cause of slope failure. In the present paper, an indoor soil slope model was built; a distributed sensing fiber was designed based on Brillouin optical time-domain analysis (BOTDA). Two soil moisture probes were planted and a rainfall infiltrationtest was simulated to acquire the data of slope infiltration and deformation progress under rainfall infiltration. Time domain volumetric moisture content of the slope as well as the vertical and horizontal strain changes were monitored. The moisture content results showed the infiltration path and had obvious ascent at the sliding surface of the slope. The fiber results showed that there existed an apparent strain concentration near the shear section of the slope and strain conversion zone; the soil deformation law had a close spatial relationship with the infiltration path in the soil. In addition to the accurate determination of the sliding surface, a secondary shear surface was also detected by the BOTDA system. These results provide valuable information pertaining to the sliding mechanism and prediction of slope failure.     

Attaining optimal dyeability and tensile properties of polypropylene/poly(ethylene terephthalate) blends with a special cubic mixture experimental design

In this investigation, we attempted to enhance the dyeability of polypropylene (PP) with disperse dyestuffs without adversely affecting its tensile properties. To this end, a special cubic experimental design was used to predict the effect of variations in the properties of a tricomponent mixture composed of PP, poly(ethylene terephthalate) (PET), and maleic anhydride grafted polypropylene (PP‐g‐MA) on the dyeability and tensile properties of the resultant polymer blend. The results illustrate that there seemed to be critical PET content, above which the blend's dye uptake tended to remain constant, but the tensile properties were adversely affected. Further analysis of the results indicated that the PP/PET/PP‐g‐MA blends in which the PET and PP‐g‐MA contents were in the range 10–15 and 4–5 wt %, respectively, gave maximal dye uptake and desirable tensile properties. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Design of a reversible structure for memory in quantum-dot cellular automata

Complementary metal oxide semiconductor (CMOS) technology has limitations in reducing the area and size of circuits. The disadvantages of this technology include high power consumption and temperature problems. Quantum-dot cellular automata (QCA) is a new technology that can overcome these shortcomings. Reversible logic is technology used to reduce the power loss in QCA. QCA can be used to design memories that require high operating speed. In this paper, we propose a structure for the reversible memory in QCA. The proposed structure utilizes three-layer technology, which has a significant impact on circuit size reduction. The proposed structure for the reversible memory has 63% improvement in cell number, a 75% improvement in area occupancy, and a 60% reduction in delay compared to the previous best structure.