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71.
The work presented in this paper is part of an EPRI-sponsored research program to develop experimentally verified methodology for predicting failure modes and leakage characteristics of concrete containments. This paper deals specifically with recent results of the analytical correlation and interpretation of full scale containment specimen tests. The tests under consideration are a wall/skirt-basemat specimen of a typical prestressed concrete containment, a specimen with a flawed liner to study liner crack growth, and a specimen with a typical steampipe penetration. Computational models of specimens are described, and pre-test and post-test analysis results are presented. The importance of local effects is discussed, and the role of specimen tests and analysis in failure prediction of containment structures is summarized. 相似文献
72.
Sufyan Ababneh Rashid Ansari Ashfaq Khokhar 《Journal of Visual Communication and Image Representation》2009,20(5):303-311
Multimedia content authentication can be achieved by deriving a fragile content-based signature from a media signal and embedding it robustly back into the signal. The perturbation due to embedding needs to be compensated with mechanisms that lead to producing the original signature. Closed form solutions for compensation are not always feasible. In this paper, we propose two iterative compensation schemes to address such scenarios. The first is based on a set-theoretic approach by using projections onto convex sets (POCS), where signature generation and signal fidelity are modeled as convex constraint sets. The other scheme uses an additive iterative approach used in the cases where the POCS approach is not applicable. Examples of successful image authentication are presented to demonstrate the effectiveness of the proposed schemes over a range of watermark-embedding robustness. A comparison with the closed-form compensation scheme, when feasible, is also presented. 相似文献
73.
Spherical particles (~3 μm) of copper(II) oxalate were produced in the form of precipitated solids by gently mixing aqueous solutions of oxalic acid and copper nitrate with predetermined concentrations at room temperature. These particles were isolated from the mother liquor and then coated with cobalt basic carbonate. The coating trials involved heating of the aqueous dispersions, containing known amounts of the dispersed copper oxalate particles (cores), urea, and cobalt nitrate, at 70–85 °C for various periods of time with constant stirring. The heating process decomposed urea, increased pH, liberated carbonate ions, which resulted in the precipitation of the dissolved cobalt ions in the form of shells of cobalt basic carbonate around each core particle. The coating process was sensitive to the applied experimental parameters, since uniformly coated particles were obtained under a narrow range of coating mixture composition. In the absence of the cores, the same reactants solutions produced coating precursor particles (cobalt basic carbonate), when subjected to similar heating conditions. Physical and chemical analyses indicated that the coating material of the coated particles and the coating precursor particles had the same chemical compositions. The as-prepared core, coating precursor, and coated particles were converted into oxide forms by heating their dry powders at elevated temperatures under controlled heating conditions. The heat treatment produced obvious changes in the surface morphology of these particles due to loss of material. Moreover, the heat-treated particles preserved shape integrity to a maximum extent, showing their thermal stability. Selected batches of the as-prepared and heat-treated products were characterized by various physical methods. 相似文献
74.
75.
Mitch J. Duncan Camille Short Mahbub Rashid Nicoleta Cutumisu Corneel Vandelanotte Ronald C. Plotnikoff 《Building Research & Information》2015,43(5):646-658
Office workers are commonly targeted in interventions to modify their sitting behaviour, yet there is limited evidence of the correlates of breaks in sitting to inform intervention development. This study identifies the individual, workplace and spatial configuration correlates of the frequency of breaks in sitting (number/hour) in office workers (n?=?5531) stratified by office type (private-enclosed, shared, open plan). All behaviours and potential correlates were measured via self-report using an online cross-sectional survey. Regression analyses revealed age was the only socio-demographic characteristic associated with frequency of breaks in sitting in all office types. Greater job autonomy and local connectivity were positively associated with frequency of breaks in sitting in shared and open-plan offices. In open-plan offices co-worker proximity was negatively associated with frequency of breaks in sitting. Co-worker visibility was positively associated with frequency of breaks in sitting in all office types. This study demonstrates that individual, workplace and spatial configuration factors are all associated with the frequency of breaks in sitting and that these relationships differ by office type. These observations extend prior studies that have only examined correlates at a single level (e.g. the individual). This evidence could be useful to guide future interventions in the design of workplaces to increase breaks in sitting and workers’ physical activity. 相似文献
76.
Water purification from metal ions using carbon nanoparticle-conjugated polymer nanocomposites 总被引:2,自引:0,他引:2
The paper deals with a novel method of obtaining nanocarbon-conjugated polymer nanocomposites (NCPC) using nanocarbon colloids (NCC) and polyethylenimine (PEI) for water purification from metal ions. Size of NCC, process of NCPC synthesis, its chemical characteristics, ratio of NCC and PEI in NCPC, speed of coagulation of NCPC, mechanism of interaction of metal ions with NCPC, ability of removing metal ions from water by NCPC against pH have been studied. NCPC has a bonding capacity of 4.0-5.7 mmol/g at pH 6 for most of the divalent metal ions. Percent of sorption of Zn2+, Cd2+, Cu2+, Hg2+, Ni2+, Cr6+ ions is higher than 99%. Lifetime of NCPC before coagulation in the treated water is 1 s-1000 min and depends on the ratio of polymeric molecules and carbon nanoparticle concentrations. Results of laboratory tests of the method are described. 相似文献
77.
78.
79.
Mohammad Shafiur Rahman M.M. Rashid M.A. Hussain 《Food and Bioproducts Processing》2012,90(2):333-340
A neuro-fuzzy modeling technique was used to predict the effective of thermal conductivity of various fruits and vegetables. A total of 676 data point was used to develop the neuro-fuzzy model considering the inputs as the fraction of water content, temperature and apparent porosity of food materials. The complexity of the data set which incorporates wide ranges of temperature (including those below freezing points) made it difficult for the data to be predicted by normal analytical and conventional models. However the adaptive neuro-fuzzy model (ANFIS) was able to predict conductivity values which closely matched the experimental values by providing lowest mean square error compared to multivariable regression and conventional artificial neural network (ANN) models. This method also alleviates the problem of determining the hidden structure of the neural network layer by trial and error. 相似文献
80.
Layali Rashid Wessam M. Hassanein Moustafa A. Hammad 《The Journal of supercomputing》2010,53(2):293-312
The sort operation is a core part of many critical applications (e.g., database management systems). Despite the large efforts
to parallelize it, the fact that it suffers from high data-dependencies vastly limits its performance. Multithreaded architectures
are emerging as the most demanding technology in leading-edge processors. These architectures include simultaneous multithreading,
chip multiprocessors, and machines combining different multithreading technologies. In this paper, we analyze the memory behavior
and improve the performance of the most recent parallel radix and quick integer sort algorithms on modern multithreaded architectures.
We achieve speedups up to 4.69× for radix sort and up to 4.17× for quicksort on a machine with 4 multithreaded processors
compared to single threaded versions, respectively. We find that since radix sort is CPU-intensive, it exhibits better results
on chip multiprocessors where multiple CPUs are available. While quicksort is accomplishing speedups on all types of multithreading
processers due to its ability to overlap memory miss latencies with other useful processing. 相似文献