Catalytic oxidation of 2-Propanol over (Cr,Mn,Fe)-Pt/gamma-Al2O3 bimetallic catalysts and modeling of experimental results by artificial neural networks.

The catalytic activity of transition metals (Cr,Mn,Fe) supported on the Pt/gamma -Al(2)O(3) industrial catalyst was investigated to bring about the complete oxidation of 2-Propanol. Catalytic studies were carried out under atmospheric pressure in a fixed bed reactor. X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and ICP-AES techniques were used to characterize a series of catalysts. Results showed that the Pt-Mn/gamma -Al(2)O(3) (3.88 wt.%Mn) at calcination temperature of 300 degrees C was the most promising catalyst based on activity, which might be contributed to the quantity of manganese loading, the favorable synergetic effects between Pt and Mn and the well-dispersed bimetallic phase. An artificial neural networks (ANN) model was developed to predict the performance of catalytic oxidation process over Pt-Mn/gamma -Al(2)O(3) bimetallic catalyst based on experimental data. For this purpose the Levenberg-Marquardt (LM) learning algorithm was employed to train the model by using laboratory experimental data. A comparison between the predicted results of the designed ANN model and experimental data was also conducted. The developed model can describe the catalytic oxidation over bimetallic catalysts under different conditions.

Coupled artificial neural networks to estimate 3D whole-body posture, lumbosacral moments, and spinal loads during load-handling activities.

Biomechanical modeling approaches require body posture to evaluate the risk of spine injury during manual material handling. The procedure to measure body posture via motion-analysis techniques as well as the subsequent calculations of lumbosacral moments and spine loads by, respectively, inverse-dynamic and musculoskeletal models are complex and time-consuming. We aim to develop easy-to-use yet accurate artificial neural networks (ANNs) that predict 3D whole-body posture (ANNposture), segmental orientations (ANNangle), and lumbosacral moments (ANNmoment) based on our measurements during load-handling activities. Fifteen individuals each performed 135 load-handling activities by reaching (0 kg) or handling (5 and 10 kg) weights located at nine different horizontal and five vertical (0, 30, 60, 90, and 120 cm from the floor) locations. Whole-body posture was measured via a motion capture system and lumbosacral moments were calculated via a 3D top-down eight link-segment inverse-dynamic model. ANNposture, ANNangle, and ANNmoment were trained (RMSEs = 6.7 cm, 29.8°, and 16.2 Nm, respectively) and their generalization capability was tested (RMSE = 7.0 cm and R2 = 0.97, RMSE = 29.9° and R2 = 0.85, and RMSE = 16.5 Nm and R2 = 0.97, respectively). These ANNs were subsequently coupled to our previously-developed/validated ANNload, which predicts spinal loads during 3D load-handling activities. The results showed outputs of the coupled ANNs for L4-L5 intradiscal pressure (IDPs) during a number of activities were in agreement with measured IDPs (RMSE = 0.37 MPa and R2 = 0.89). Hence, coupled ANNs were found to be robust tools to evaluate posture, lumbosacral moments, spinal loads, and thus risk of injury during load-handling activities.

Application of artificial neural networks for modeling of the treatment of wastewater contaminated with methyl tert-butyl ether (MTBE) by UV/H2O2 process.

During the last two decades, methyl tert-butyl ether (MTBE) has been widely used as an additive to gasoline (up to 15%) both to increase the octane number and as a fuel oxygenate to improve air quality by reducing the level of carbon monoxide in vehicle exhausts. The present work mainly deals with photooxidative degradation of MTBE in the presence of H2O2 under UV light illumination (30W). We studied the influence of the basic operational parameters such as initial concentration of H2O2 and irradiation time on the photodegradation of MTBE. The oxidation rate of MTBE was low when the photolysis was carried out in the absence of H2O2 and it was negligible in the absence of UV light. The addition of proper amount of hydrogen peroxide improved the degradation, while the excess hydrogen peroxide could quench the formation of hydroxyl radicals (OH). The semi-log plot of MTBE concentration versus time was linear, suggesting a first order reaction. Therefore, the treatment efficiency was evaluated by figure-of-merit electrical energy per order (E(Eo)). Our results showed that MTBE could be treated easily and effectively with the UV/H2O2 process with E(Eo) value 80 kWh/m3/order. The proposed model based on artificial neural network (ANN) could predict the MTBE concentration during irradiation time in optimized conditions. A comparison between the predicted results of the designed ANN model and experimental data was also conducted.

Injuries due to handtools. Results of a questionnaire.

A questionnaire was mailed to various federal and state agencies in the United States to determine the frequency, severity and annual cost of handtool-related injuries in industry and to identify problem areas with regard to tool type, accident type, nature of injury, parts of body affected, type of industry and characteristics of the injured worker. The responses of various state and regional agencies were tabulated and analysed. This paper summarises the findings.

Determination of optimal location for parachute ripcord handle in a suspended position.

A number of parachuting fatalities are attributed every year to the inability of the parachutist to pull the ripcord. The purpose of this study was to determine a location for the ripcord handle in parachutes, which would be most compatible with human capabilities. Eight different ripcord handle locations were selected for this investigation. Eighteen male and 18 female subjects participated in the study. The subjects were tested while being suspended 5 cm above floor level wearing a parachute harness. Maximum voluntary force exertions were measured with the subjects pulling the ripcord handle using their left, right and both hands at all locations. The results indicate that the thigh locations are superior in regard to pull forces for all hand applications (left, right, and both). Also, two-handed pulls yield the largest forces at all locations.

Influence of VDT monitor positions on discomfort and performance of users with or without bifocal lenses.

The difficulty of video display terminal users with bifocal lenses through a traditional workstation increases the complaints and risks for upper extremity cumulative trauma disorders. Furthermore, the regular and no lens users also have problems with traditionally designed workstations over prolonged periods of video display terminal use. A study was conducted on 14 subjects to investigate the effect of computer monitor location for video display terminal users with or without bifocals on subjective assessment and performance. The two monitor locations were 15 degrees and 40 degrees below horizontal eye level. The experimental task consisted of reading words from computer screens and typing them from the reverse side to the next column. Each experimental session lasted one hour. Males with bifocal lenses had less discomfort in the neck, shoulders, forearms, and wrists, less tiredness and eyestrain and higher performance with a 40 degrees angle monitor than with a 15 degrees angle monitor. A similar conclusion has been reached for females. Users with bifocal lenses had significantly higher neck discomfort and lower performance than nonbifocal users. The 40 degrees angle monitor caused less neck discomfort than the 15 degrees angle monitor did. Overall, females had less physical discomfort, less tiredness, and higher performance than males.

Impact of anthropometric and personal variables on grip strength.

This paper presents the results of a study to evaluate the effects of personal and anthropometric variables on grip strength. Weight, height, frame size, and Fat-Free Cross-Sectional Area (FFCSA) were the anthropometric variables included in the study. Sex and the amount of exercise were the personal variables included. A group of 33 female and 59 male students were used as subjects. A stepwise regression analysis was performed to find a model which can be used to predict grip strength. It was found that the sex and weight are two variables which account for maximum variation in grip strength among these variables. Although, FFCSA (r2 = 0.788) correlated strongly with grip strength but was not chosen in the model, possibly because of lower correlation between FFCSA and sex. Height and weight also seem to correlate with grip strength, but to a lesser extent.

Maximum acceptable weight of lift for side and back lifting.

A series of laboratory experiments were conducted to find maximum acceptable weights in front, side, and back lifting. Fifteen college students participated in the experiment. Experimental trials for each type of lifting were conducted for 10 min for each subject at a rate of 4 lifts/min. Psychophysical methodology was used to find the acceptable weight based upon their perceived feeling of stress in the lower back. It was found that subjects are willing to lift the heaviest load using back lifting (average maximum acceptable weight: 41.5 lbs). Front lifting was the close second with 39.4 lbs. Also, there was a significant difference in maximum acceptable weight of lift between side lifting (average maximum acceptable weight: 25.5 lbs) and the other two types of lifting. It was also found that leg strength was a limiting variable for maximum acceptable weight in front lifting. Composite strength and shoulder strength were found to be limiting variables in side lifting. Composite strength was the limiting variable in the back lifting.

Evaluating lifting tasks using subjective and biomechanical estimates of stress at the lower back.

The objective of this study was to evaluate five different lifting tasks based on subjective and biomechanical estimates of stress at the lower back. Subjective estimates were obtained immediately after the subjects performed the lifting tasks. Rankings for different tasks were obtained according to the perceived level of stress at the lower back. A biomechanical model was used to predict the compressive force at the L5/S1 disc for the weight lifted considering link angles for the particular posture. The tasks were also ranked according to the compressive force loading at the L5/S1 disc. The weight lifted in these tasks for obtaining the subjective estimate of stress was the maximum acceptable weight of lift (MAWOL). This was determined separately for each subject using a psychophysical approach. Subjective estimates of stress were obtained for infrequent lifting, specifically for a single lift, as well as for lifting at a frequency of four lifts per min. The results showed that a lifting task acceptable from the biomechanical point of view may not be judged as a safe or acceptable task by the worker based on his subjective perception. This may result in a risk of the worker not performing the recommended task or not following the recommended method.