1,650 research outputs found

    Explosive Welding of Aluminum, Titanium and Zirconium to Copper Sheet Metal

    Get PDF
    The main material properties affecting the explosive weldability of a certain metal combination are the yield strength, the ductility, the density and the sonic velocity of the two metals. Successful welding of the metal combination depends mainly on the correct choice of the explosive welding parameters; i.e., the stand off distance, the weight of the explosive charge relative to the weight of the flyer plate and the detonation velocity of the explosive. Based on the measured and the handbook values of the properties of interest, the explosive welding parameters were calculated and the arrangements for the explosive welding of the Al alloy 6061-T6, titanium and zirconium to OFHC copper were determined. The relatively small sheet metal thickness (1/8") and the fact that the thickness of the explosive layer must exceed a certain minimum value were considered during the determination of the explosive welding conditions. The results of the metallographic investigations and the measurements of the shear strength at the interface demonstrate the usefulness of these calculations to minimize the number of experimental trials

    Study of output difference of two different ionization chambers for large fields used in radiotherapy

    Get PDF
    Many radiotherapy centers don't pay attention to effect of ionization champers type on accuracy of quality control measurements. They use any available ionization champers in all quality control and data entry measurements (1,2) . Many studies were carried out in this field to compare different ionization champers in small fields but large fields were not completely compared before (3.4).  The aim of this work is to compare   output factor in large field using two different sizes ionization champers connected to electrometer. Final out put were obtained from the farmer and smidflex dosimeter irradiated with 6 MV photon beams. Important field side ranging from 20 cm to 70 cm side field is measured in whole body radiation (5, 6). For all examined large  field sizes a difference ranging from 1% to 5 % was found when added to other calibration errors it will exceeds the acceptable margin. The largest difference was found in field side 70 cm this may be due to large scattering radiatio

    Biomass Production for Energy in India: Review

    Get PDF
    This paper presents a general view about biomass production in India and its potential energy for use in different fields. India has tremendous potential for energy generation through biomass and its residues. Biomass energy is normally produced from firewood, agricultural residues such as bagasse, crop stalks, animal dung and wastes generated from agro-based industries. With the estimated and predicted values, the generating power from the surplus biomass in India was significant and it will continue to be more effective in future. Residue use as a fuel in India is estimated to be 216 Mt as projected value in 2010, recently, around 605 MW of electricity is being produced from biomass firing and 720 MW from cogeneration activities for residue. About 185 Mt (40%) of the dung collected is used as fuel in cook stoves. The potential for biogas production annually is 8750 million m3 from 251 Mt of dung. The amount of fuel-wood consumption during year 2004 was 205 million tonnes used as fuel for traditional cook stoves with low efficiency, 16 Mt used in industrial sector producing 10 PJ, and it was estimated that the production of fuel wood and charcoal increased to the rate of 1.98 per cent per annum. The total quantity of solid wastes generated in larger towns and cities has been estimated at 40 Mt in 2001, and in 2005 the average MSW generation in overall India was approximately 100,000 Mt/day. For the wastewater in India, in 2010, the energy estimated to be around 3929.8 TJ as energy value of CH4

    Delayed surgical debridement in pediatric open fractures: a systematic review and meta-analysis.

    Get PDF
    Purpose: Open fractures are considered orthopedic emergencies that are traditionally treated with surgical debridement within 6 h of injury to prevent infection. However, this proclaimed “6-h rule” is arbitrary and not based on rigorous scientific evidence. The aim of our study was to systematically review the literature that compares late (>6 h from the time of injury) to early (<6 h from the time of injury) surgical debridement of pediatric open fractures. Methods: We searched several databases from 1946 to 2013 for any observational or experimental studies that evaluated late and early surgical debridement of pediatric open fractures. We performed a meta-analysis using a random effects model to pool odds ratios for a comparison of infection rates between children undergoing late versus early surgical debridement. We also investigated the infection rates in upper- and lower-limb pediatric open fractures. Descriptive, quantitative, and qualitative data were extracted. Results: Of the 12 articles identified, three studies (retrospective cohort studies) were eligible for the meta-analysis, encompassing a total of 714 open fractures. The pooled odds ratio (OR = 0.79) for infection between late and early surgical debridement was in favor of late surgical debridement but was not statistically significant (95 % CI 0.32, 1.99; p = 0.38, I 2 = 0 %). No significant difference in infection rate was detected between pediatric open fractures in the upper and lower limbs according to the time threshold in the included studies (OR = 0.72, 95 % CI 0.29, 1.82; p = 0.40, I 2 = 0 %). Conclusions: The cumulative evidence does not, at present, indicate an association between late surgical debridement and higher infection rates in pediatric open fractures. However, initial expedient surgical debridement of open fractures in children should always remain the rule. Thus, multi-center randomized controlled trials or prospective cohort studies will be able to answer this question with more certainty and a higher level of evidence

    Parameter estimation of electric power transformers using Coyote Optimization Algorithm with experimental verification

    Get PDF
    In this work, the Coyote Optimization Algorithm (COA) is implemented for estimating the parameters of single and three-phase power transformers. The estimation process is employed on the basis of the manufacturer's operation reports. The COA is assessed with the aid of the deviation between the actual and the estimated parameters as the main objective function. Further, the COA is compared with well-known optimization algorithms i.e. particle swarm and Jaya optimization algorithms. Moreover, experimental verifications are carried out on 4 kVA, 380/380 V, three-phase transformer and 1 kVA, 230/230 V, single-phase transformer. The obtained results prove the effectiveness and capability of the proposed COA. According to the obtained results, COA has the ability and stability to identify the accurate optimal parameters in case of both single phase and three phase transformers; thus accurate performance of the transformers is achieved. The estimated parameters using COA lead to the highest closeness to the experimental measured parameters that realizes the best agreements between the estimated parameters and the actual parameters compared with other optimization algorithms

    Feasibility Considerations of an Optimal Pumping Strategy to Capture TCE/PCE Plume at March AFB, CA

    Get PDF
    TCE/PCE contaminated groundwater from March AFB has reached off-base supply wells. Further migration of the contaminants can endanger other downstream water supply wells

    The value of Holter monitoring in the assessment of Pediatric patients

    Get PDF
    Aims: Holter monitoring (HM) has been established as one of the most effective noninvasive clinical tools in the diagnosis, assessment and risk stratification of cardiac patients. However, studies in the pediatric age group are limited. The present work aims at determining the value of HM in the diagnosis and management of children. Settings and Design: Retrospective study conducted at a tertiary referral arrhythmolology service.Methods and Material: Holter records of 1319 pediatric patients (54.1% males and 45.9% females) were reviewed. Their average age was 6.7± 4.1 years (5 days-16 years). Indications for which Holter monitoring was done were analysed as well as all the abnormalities diagnosed and factors that may increase Holter yield.Statistical analysis used: Statistical Package of social science (SPSS) version 9,0 was used for analysis of data. Results: The most common indications were palpitations (19.8%), syncope (17.8%), cardiomyopathy (12.6%), chest pain (10%), evaluation of antiarrhythmic therapy (6.8%), postoperative assessment (2.6%) and complete AV Block (2.4%). A sum of 141 Holter recordings were found abnormal with a total diagnostic yield of 10.7%. The highest contribution to diagnosis was in postoperative assessment (32.4%) and in cardiomyopathy (19.9%) where the most common abnormalities were frequent supraventricular / ventricular premature beats, supraventricular tachycardia, ventricular tachycardia and AV block. Diagnostic yield was low in patients with palpitations (5.7%) and syncope (0.4%). An abnormal ECG was significantly associated with a higher diagnostic yield (p=0.0001). None of the children with chest pain had abnormal Holter recordings.Conclusions: HM has an extremely valuable role in the assessment of high risk patients (postoperative and cardiomyopathy). However in children with palpitations, syncope and chest pain HM has a low yield. In this group of patients an abnormal ECG is more likely to be associated with abnormal Holter recordings

    Optimal management of irrigation and vadose zone pesticide transport

    Get PDF
    A management model is developed for maximizing crop yield while avoiding unacceptable pesticide leaching. Utilized constraint equations: maintain a soil moisture volume balance, describe downward pesticide transport, and limit the amount of pesticide reaching groundwater. The reported optimization model is the first which includes unsaturated zone pesticide transport. It is designed to help prevent nonpoint-source contamination of shallow groundwater aquifers. The model computes optimal irrigation amounts for given soil, crop, chemical, and climate data and irrigation frequencies. The model is tested for different irrigation scenarios. The modeling approach is promising as a tool to aid developing environmentally sound agricultural production practices. It allows estimation of trade-offs between crop production and groundwater protection for different management strategies. More frequent irrigation tends to give better crop production and less solute movement. Yield/environmental quality trade-offs are smaller for deeper groundwater tables. Trade-offs also decrease with increased irrigation frequency

    How Viable Is the UTAUT Model in a Non-Western Context?

    Get PDF
    The present research examines the plausibility of Unified Theory Acceptance and Use Technology (UTAUT) model in predicting internet banking behaviour as a newly adopted technology third world countries. Data is collected from three Arab countries: Jordan, Saudi Arabia and Egypt. Confirmatory factor analysis is applied to test constructs measurement and model hypotheses. Findings are congruent with model testing under conditions of volitional usage behaviour. In this regard, the role of facilitating conditions variable is insignificant as a determinant of usage behaviour. Social norms variable also proved to be weak determinant of behavioural intentions mainly owing to users’ experience. Findings demonstrate effort expectancy as the key determinant of internet banking usage behaviour in the examined markets, while users’ experience moderates the impact of effort expectancy on behavioural intention. Results should enhance our understanding of internet banking usage in developing countries and support e-services promoting in this region
    corecore