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991.
Shahzad N Hussain ST Siddiqua A Baig MA 《Journal of nanoscience and nanotechnology》2012,12(6):5061-5065
Reduction of H2S gas over Sulphur doped TiO2 nanoparticles and TiO2 nanotubes was studied in this work. Fixed bed catalytic system was used for the catalytic reduction of H2S gas at a high temperature of 450 degrees C under laboratory conditions. 99.97% reduction was achieved using S-doped TiO2. 2.89% Sulphur was adsorbed on S-doped TiO2 nanoparticles in the form of Ti(SO4)2, while 95.6% reduction was achieved in case of TiO2 nanotubes and the sulphur adsorption was 2.67%. The XRD, SEM, and EDX techniques were carried out to characterize the nanoparticles and nanotubes, while gas reduction analysis was carried out using GC-MS for gas samples. 相似文献
992.
Muhammad Abdullah Jamil Ahmad Mazhar Mehmood H. Waqas M. Mujahid 《Composites Part B》2012,43(3):1564-1569
In the present study effect of deflocculants like P-Aminobenzoic Acid (PABA) and Cetyltrimethyl ammonium bromide (CTAB) on densification and hardness of 3 mol.% Yttria-stabilized ZrO2 (abridged as YSZ) + Al2O3 (whiskers or particulates) composite have been studied. Maximum hardness & density were achieved at 1 wt% of CTAB or PABA, while further addition (5, 10 and 15 wt%) had no significant affect on the aforementioned properties. It was also observed that alumina addition in form of particulates only improved the density while its addition in form of whiskers significantly increased the hardness of YSZ + alumina composite. The maximum hardness achieved was more than 14 GPa in case of sample containing alumina in form of whiskers. 相似文献
993.
Muhammad Abid Abdul Waheed Awan David H. Nash 《Canadian Metallurgical Quarterly》2010,136(12):1519-1527
Performance of a bolted flange joint is characterized mainly due to its “strength” and “sealing capability.” A number of analytical and experimental studies have been conducted to study these characteristics only under internal pressure loading. A very limited amount of work is found in the literature under combined internal pressure and bending loading. Due to the ignorance of this external loading, i.e., bending loading, the optimized performance of the bolted flange joint cannot be achieved. The present design codes do not address the effects of bending loading on the structural integrity and sealing ability. To investigate joint strength and sealing capability under combined loading, an extensive comparative experimental and numerical study of a nongasketed flange joint is carried out and overall joint performance and behavior is discussed. Actual joint load capacity is determined under both the design and proof test pressure with maximum additional external bending loading that can be applied for safe joint performance. In addition, as experimentally it is impossible to test different flange joint sizes under combined loading application, hence finite element model developed and verified with the experimental results, presented in this paper can be used as base to study the behavior for different nongasketed flange joint sizes for different classes under combined pressure and bending loading. 相似文献
994.
The need of immediate supportive measures for sustainability of municipal infrastructures calls for better understanding of the behavior of various infrastructure network systems and their components. This paper presents a study which uses artificial neural networks to investigate the importance and influence of certain characteristics of sewer pipes upon their structural performance, expressed in terms of condition rating. In this study, back propagation and probabilistic neural network (NN) models were developed and validated. The data used in the development of these models were provided by the municipality of Pierrefonds, Quebec. It comprised of parameters related to sewer pipelines, pipe diameter, buried depth/cover, bedding material, pipe material, pipeline length, age, and closed circuit television (CCTV) based structural condition rating. The first six parameters are the independent variables of the models whereas CCTV based condition rating for these pipes is the dependent variable (i.e., the output of the models). The developed NN models were used to rank the parameters, in order of their importance/influence on pipe condition. It was found that, among the studied parameters, material attributes have highest influence on pipe structural condition, respectively, followed by the geometric and physical attribute group. Sensitivity analysis was then performed to simulate the structural condition of a pipe at a range of values of each input parameters. Results of sensitivity analysis describe the nature and degree of the influence of each parameter on pipe structural condition. The developed models are expected to benefit academics and practitioners (municipal engineers, consultants, and contractors) to prioritize inspection and rehabilitation plans for existing sewer mains. 相似文献
995.
We propose a novel system of the dynamic optical tweezers generated by a dark soliton in the fiber optic loop. A dark soliton known as an optical tweezer is amplified and tuned within the microring resonator system. The required tunable tweezers with different widths and powers can be controlled. The analysis of dark-bright soliton conversion using a dark soliton pulse propagating within a microring resonator system is analyzed. The dynamic behaviors of soliton conversion in add/drop filter is also analyzed. The control dark soliton is input into the system via the add port of the add/drop filter. The dynamic behavior of the dark-bright soliton conversion is observed. The required stable signal is obtained via a drop and throughput ports of the add/drop filter with some suitable parameters. In application, the trapped light/atom and transportation can be realized by using the proposed system. 相似文献
996.
Air pollution assessment in urban areas and its impact on human health in the city of Quetta, Pakistan 总被引:1,自引:0,他引:1
Syed Zafar Ilyas Azmat Iqbal Khattak S. M. Nasir Tabnak Qurashi Rehana Durrani 《Clean Technologies and Environmental Policy》2010,12(3):291-299
Nowadays, air over major cities throughout the world has become overburdened with gases produced by automobiles. The death
rate due to automobile pollution is increasing rapidly in the metropolitan areas. With passage of time, people realized that
polluted air has serious effects on their health, climate and economics. Weather and climate have integrated impact on human
activities resulting in worldwide concentration of the particulates of environmental pollution, viz., chlorofluorocarbons,
carbon dioxide, methane, nitrogen oxide, lead and several other dust and gaseous particles. Like many other mega cities in
the world the ambient air quality of Quetta, Pakistan is also deteriorating nowadays. Automobile exhausts and certain industrial
pollutants produce O3 by photochemical reactions. The particulate matter, particularly less than 10 μm in size, can pass through the natural protective
mechanism of human respiratory system and plays an important role in genesis and augmentation of allergic disorders. Sources
of air pollution in the area and the unique problem arising out of the emission from the vehicles, industries, etc. have been
described. Ambient air quality was monitored along with micrometeorological data and the results are discussed. The status
of air pollution in the area has been evaluated and a questionnaire survey was conducted to estimate the allergic symptoms
and exposure to assess the respiratory disorders. The data are analyzed to evaluate the critical situation arising out of
the emission of air pollutants and the impact on human health due to respirable diseases (RDs) in middle class sub-population
(activity-wise) in the area assessed. A strategic air quality management plan has been proposed. For the mitigation of air
pollution problems in the city, different measures to be adopted to maintain the balance between sustainable development and
environmental management have been discussed. Air pollution has significant effects on exacerbation of asthma, allergy and
other respiratory diseases. 相似文献
997.
We propose using a two-level (-1 and +1 as variables) orthogonal array (OA) to generate a binary phase diffuser for speckle reduction in laser projection displays. Compared with the Hadamard matrix, the diffuser generated from OA is more flexible. The speckle contrast ratio (CR) when introducing the binary phase diffuser at an intermediate image plane within the projector is calculated, and the minimum speckle CR can be achieved by finite step change of the diffuser patterns. With Kronecker algebra, the two-dimensional diffuser can also be replaced by two one-dimensional diffusers with the same function, and it can be implemented into the laser projector electronically and easily. 相似文献
998.
The effects of using low and high enrichment uranium fuel on the uncontrolled loss of flow transients in a material test research reactor were studied. For this purpose, simulations were carried out of an MTR fuelled separately with LEU and HEU fuel, to determine the reactor performance under loss of flow transients with totally failed external control systems. The coolant pump was assumed to loose its performance and the coolant flow rate reduced according to the relation m(t)/m0 = exp(−t/25) to a new stable level. The new reduced flows m/m0 = 0.2, 0.4, 0.6 and 0.8 were modeled. The nuclear reactor analysis code PARET was employed to carry out these calculations. It was observed that the reactors stabilized at new power levels which were lower than the original power level, with the power of HEU fuelled reactor slightly lesser than that of the LEU fuelled reactor. However, at the start of transient, the LEU fuelled reactor had a lower power level resulting in lower fuel, clad and coolant temperatures than the HEU fuelled reactor. 相似文献
999.
Muhammad Zarif Brian McKay Jiehua Li Peter Schumacher 《BHM Berg- und Hüttenm?nnische Monatshefte》2010,155(11):506-511
High purity Al-5Si (wt. %) master alloys containing different levels of Sr additions were manufactured in an arc melter under high vacuum. The alloys were melt-spun which resulted in the production of thin ribbons. The microstructure of the ribbons consisted of Al matrix and entrained eutectic droplets. The ribbons were subsequently investigated using differential scanning calorimetry (DSC) and conventional transmission electron microscopy (CTEM) to examine the effect of Sr on the droplet undercooling and nucleation of eutectic silicon. The results indicate that the addition of Sr increases the eutectic droplet nucleation undercooling (ΔT). This may be due to Sr poisoning of the AlP phase. 相似文献
1000.
Comparison of in vivo toxicity,antioxidant and immunomodulatory activities of coconut,nipah and pineapple juice vinegars 下载免费PDF全文