The performance of Pt nanoparticles supported on Sb2O5.SnO2, on carbon and on physical mixtures of Sb2O5.SnO2 and carbon for ethanol electro-oxidation

Pt nanoparticles were supported on Sb₂O₅.SnO₂ (ATO), on carbon and on physical mixtures of ATO and carbon by an alcohol-reduction process using ethylene glycol as reducing agent. The obtained materials were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Their performance for ethanol oxidation was investigated at room temperature by chronoamperometry and in a direct ethanol fuel cell (DEFC) at 100 °C. Pt nanoparticles supported on a physical mixture of ATO and carbon showed a significant increase of performance for ethanol oxidation compared to Pt nanoparticles supported on ATO or on carbon.     

Optimum design of containers for manual material handling tasks

The container in manual material handling represents the point of interface between the worker and his task as well as with the surrounding environment. It is at this point that many of the well known handling hazards occur which manifest themselves in stresses and strains that are transmitted to the body via the musculo-skeletal system. If a substantial number of handling hazards is to be controlled or eliminated at the source, containers designed in accordance with principles of biomechanics and related recommendations provide a logical starting point. The container characteristics to be considered in the design process are weight (and its distribution), shape, stiffness, and availability of coupling devices. This paper presents several examples which outline and detail a number of problems associated with the design of containers involved in manual tasks. Application of basic mechanics, coupled with the use of optimization techniques, is presented as the approach for dealing with the hazards and problems of containers.     

Electrochemical Reactivation of Granular Activated Carbon: Effect of Electrolyte Mixing

Bench-scale experiments investigated the effect of electrolyte mixing on the effectiveness of an electrochemical reactor for the reactivation of granular activated carbon (GAC). Two different GACs (F-400 and WV-B) were loaded with phenol via batch adsorption tests, then electrochemically reactivated and finally reloaded with phenol. Reactivation was conducted in a recirculating flow reactor with a 0.1?M NaCl solution as the electrolyte. Cathodic reactivation was more efficient than the anodic reactivation and increasing the degree of electrolyte mixing decreased the cathodic reactivation efficiencies, while there was no significant change in the anodic reactivation efficiencies. Higher degrees of electrolyte mixing decreased the local pH at the cathode and consequently reduced the desorption driving force and therefore reduced the reactivation efficiency. The electrolyte mixing lowered the cell voltage. However, this advantage was overshadowed by the increased energy consumption required for the electrolyte pumping, the reduction of the oxidation rate of phenol, and a 20% reduction in the reactivation efficiencies. Thus, electrolyte mixing of the electrolyte is not recommended in the electrochemical reactivation of GAC.     

Selective Monolaurin Synthesis through Esterification of Glycerol Using Sulfated Zirconia-Loaded SBA-15 Catalyst

The selective conversion of lauric acid to glycerol monolaurin over sulfated zirconia SBA prepared under various conditions was investigated in this study. The structural properties of the prepared catalysts were characterized using different characterization techniques. Sulfated zirconia was successfully incorporated with improved properties, such as larger mesopore surface area; the mesoporous structure was preserved as well. The highest yield of 79.1% was obtained during reaction over SZSBA-15 catalyst with 16 wt.% zirconium oxychloride loading and 3 h of reflux time. About 83.4% selectivity toward monolaurin was achieved at a high conversion of lauric acid (94.9%), a lauric acid-to-glycerol molar ratio of 4.0, within 6 h, and at 160°C. Product distribution was successfully elucidated. High selectivity to monolaurin was influenced by molecular sieving effects.     

A 2-D simulation model for lifting activities

Occupational biomechanics models deal with the evaluation of physical activities such as lifting of loads. This allows the user to determine the stresses imposed on the musculoskeletal system while holding or moving a load. These models are useful tools in estimating these stresses especially those imposed on the lumbar spine. dynamic biomechanical models, as opposed to static models require the displacement-time information to obtain the kinematics needed to estimate the kinetics of the motion. However, the collection of this displacement data is both tedious and can require expensive equipment.

Simulation models on the other hand can provide an indirect means of performing the biomechanical analyses without having to collect the displacement-time data. A typical simulation model for 2-D lifting activities will be presented. The basis for this is the hypothesis that the body will perform the activity in such a manner so as to minimize the work done. Using this assumption an objective function was developed subject to a set of constraints. These constraints relate to the human movement, the physical workplace layout, and maintenance of balance. Using this model, it was possible to generate the lifting motion patterns, as well as the kinematics and kinetics of motion. The paper discusses the model development, the model output and the kinematics and kinetics of the simulation of the lifting action.     

Assessment of the physical work capacity of institutionalized mentally retarded males

Educable and trainable mentally retarded males (N=37) were examined for physical work capacity. Analysis of results indicated that the physical work capacity of the test population was 20 to 30% below that cited in the literature for nonretarded subjects of similar age and sex. Evidence also suggested that developmental and maintenance programs of physical fitness were required in order for mentally retarded persons to qualify for and maintain employment on most of the manual occupational tasks cited.     

The combined effect of step-feed and recycling on RBC performance

The effect of step-feed and recycling on the efficiency of treatment in rotating biological contractors (RBCs) was investigated. Experiments were conducted on a RBC system consisting of two three-stage units. The two units were operated in parallel, one unit as a control with a single feed point and the other in a step-feed mode. Seven experimental runs were conducted, using a simple synthetic wastewater, in which hydraulic loading rates were maintained constant at about 0.094 m3/m2d and variable COD concentrations (800-1200 mg/L), NH3-N concentrations (104-116 mg/L), step-feed ratios (60/40 and 70/30), and recirculation modes. Results indicate that improvements in the treatment efficiencies of RBC systems may be attained by operating the system in a step feed mode as compared to a single point feed mode. Further improvements may also be obtained by inducing effluent recirculation to the inlet stage. In both cases, levels of improvement have shown to be more pronounced for NH3-N removals and DO residual concentrations as compared to COD removals. The combined effect of step feed and recirculation of system effluent on NH3-N removal efficiencies is appreciable. Comparing removal efficiencies between the control, step feed and the combined step-feed/recirculation modes shows an increase of about 26%. For COD removals, the effect is not that pronounced as the results for the combined modes of operation indicate a limited increase in overall removal efficiency of about 3%. Supplementing step feed by a recircutation system also markedly improved DO residuals in stages 1 and 2 and to a lower extent in stage 3 of the system. Changing the ratio in the step feed system from 60/40% to 70/30% exhibited a slight improvement in NH3-N removal efficiencies as well as improved residual DO concentrations but very limited effect on COD removals. The use of a simple synthetic wastewater in the experiments may limit extrapolation of the findings to actual operation.     

Heavy Metal Removal by Coagulation with Seawater Liquid Bittern

Soluble heavy metals present in water could be deleterious to health, and as a result, their discharge into surface waters has been regulated internationally. Many processes for the removal of heavy metals from water and wastewater have been investigated. Coagulation and precipitation are the processes that have been reported to be most effective in the removal of heavy metals. In this study, seawater liquid bittern (LB), as an inexpensive source of magnesium, added to wastewater alkalized with lime or caustic soda is investigated as a possible coagulant. The experiments covered tests on eight metals: arsenic, cadmium, chromium, copper, lead, mercury, nickel, and zinc. The lime-LB process culminated in high removals (>90%) for cadmium, chromium, lead, mercury, and zinc and reasonably good removals (71, 82, and 75%) for arsenic, copper, and nickel, respectively. These results were superior to those obtained using the caustic-soda–LB process. The concurrent presence of different metals in solution has been shown to have a minor effect on removal efficiencies for most metals. However, in the case of nickel, removal was appreciably increased by 18.5%. Also, higher concentrations of a single metal showed higher removal efficiencies.     

Resource trading in cloud environments for utility maximisation using game theoretic modelling approach

We develop a novel auction-based scheme for trading free processors in cloud computing environment. Our scheme allows clients to fairly compete for the offered processors. Second-price auction is used where each client bids for the processors. The client that makes the higher bid wins the auction and starts using the processors for executing its jobs. The winner pays the second highest bid. Maximising profit is the key objective for the cloud provider (CP). The optimisation problem of renting processors on the cloud market is a complex and challenging task. The proposed mechanism takes into account the market demand and the economic concerns for the CP and clients. Within this context, we show the existence of a Nash equilibrium which leads to a unique allocation under certain processors distribution. Numerical analysis stresses the ability of our approach to maximise the client's utility under varying cloud environment conditions.