488 research outputs found
A WOA-based optimization approach for task scheduling in cloud Computing systems
Task scheduling in cloud computing can directly
affect the resource usage and operational cost of a system. To
improve the efficiency of task executions in a cloud, various
metaheuristic algorithms, as well as their variations, have been
proposed to optimize the scheduling. In this work, for the
first time, we apply the latest metaheuristics WOA (the whale
optimization algorithm) for cloud task scheduling with a multiobjective optimization model, aiming at improving the performance of a cloud system with given computing resources. On that
basis, we propose an advanced approach called IWC (Improved
WOA for Cloud task scheduling) to further improve the optimal
solution search capability of the WOA-based method. We present
the detailed implementation of IWC and our simulation-based
experiments show that the proposed IWC has better convergence
speed and accuracy in searching for the optimal task scheduling
plans, compared to the current metaheuristic algorithms. Moreover, it can also achieve better performance on system resource
utilization, in the presence of both small and large-scale tasks
Chrome tanning process and the leather properties under microwave irradiation
Content:
In leather making processes, the thermal and non-thermal effect of microwave, especially non-thermal effect, strengthen the combination between collagen and chemicals. Although tanning under microwave
makes the leather have better thermal stability, the tanning process and leather properties have not been studied in detail. For illustrating the influence of microwave on chrome tanning process, pickled skin was tanned for 6h as penetration procedure and then basified for another 4h as fixation procedure. The tanning under microwave heating (MW) was experimental sample and under water bath heating was control. UVVis, ICP-OES and pH meter were used to measure the changes of tanning effluent during tanning, and Shrinkage temperature meter, DSC, TG, FT-IR, SEM, XRD and XPS were applied to determine the differences between MW and WB in aspect of leather property and structure. The results indicated microwave accelerated chrome tanning agent penetration and had better promotion effect on chromium
complex hydrolysis and olation. The leather tanned with microwave assisting had special effect on improve tanning effect which led better thermal stability and resistance of leather, but the collagen structure,
including triple helix structure, stayed as WB and the combination mechanism between collagen and chromium was also same with conventional. In sum, microwave had positive effect on accelerating tanning
rate and resulting in better leather without any negative effect on leather structure. Therefore, microwave would be a potential for achieving clean and sustainable chrome tanning by making tanning much faster and more efficiency.
Take-Away:
Microwave promotes chrome tanning agent penetration and combination
Microwave has positive effect on tanning effect further as the leather tanned by microwave assisting has higher thermal stability.
Although microwave promotes chrome tanning process, the collagen structure and tanning mechanism remained as normal
A Novel Collagen Extraction Method Based on Microwave Irradiation
Content:
Microwave was used as a thermal source to extract collagen acid from the cattle hide in the present work. The effects of microwave on collagen extraction yields were studied under different microwave
temperatures, time and hide-liquid ratio. The optimal extraction process was obtained by an orthogonal experiment, and the composition, structure and properties of the extracted collagen were characterized by amino acid analysis, SDS-PAGE, FTIR, UV-Vis, CD, FL, and VP-DSC. The results showed that the extraction rate of collagen was positively correlated with temperature, time and hide-liquid ratio. Under the condition of 35 °C, 6 h and 1:30 of solid-liquid ratio, the extraction proportion of collagen extracted under microwave was the highest, reaching to 13.40 %. The extracted collagen was identified as type I collagen by Amino acid analysis, and the graphic pattern of SDS-PAGE, FTIR and UV-Vis showed that the extracted collagen was similar to the standard type I collagen. Also, the results suggest that the triple helical structure exists still in the extracted collagen. The transition from triple helix to random coil of the extracted collagen was 41 â. These results provide a scientific basis for microwave technology for the extraction of collagen.
Take-Away:
The results showed that the extraction rate of collagen was positively correlated with temperature, time and hide-liquid ratio. Under the condition of 35 °C, 6 h and 1:30 of solid-liquid ratio, the extraction
proportion of collagen extracted under microwave was the highest, reaching to 13.40 %. The extracted collagen was identified as type I collagen by Amino acid analysis, and the graphic pattern of SDS-PAGE,
FTIR and UV-Vis showed that the extracted collagen was similar to the standard type I collagen. Also, the results suggest that the triple helical structure exists still in the extracted collagen. The transition from triple helix to random coil of the extracted collagen was 41 â. These results provide a scientific basis for microwave technology for the extraction of collagen
Heat conduction mechanisms in nanofluids and suspensions
Nanofluids, liquids containing suspensions of nanoparticles, have been reported by some groups to exhibit substantially higher thermal conductivity than that of their corresponding base fluids that cannot be explained by existing theories. However, the reported high thermal conductivity sometimes cannot be reproduced by others. Potential mechanisms leading to this enhancement are still under scrutiny. In this paper, we first take a critical review of heat conduction mechanisms proposed in literature, and then summarize our work. Our experimental studies demonstrate that nanoparticle clustering is the key contributor to the thermal conductivity enhancement. Guided by this insight, we use graphite flakes as additives and develop a method to prepare stable graphite suspensions with large thermal conductivity enhancement in water and oil. We also observe thermal percolation phenomenon and explained the phenomenon based on combined optical and AC impedance spectroscopy studies. We demonstrate temperature regulation of electrical and thermal properties of graphite suspensions through solidâliquid phase change, which may potentially be useful in energy systems in the future.United States. Air Force Office of Scientific Research (AFOSR FA9550-11-1-0174)China. Fundamental Research Funds for the Central Universitie
Ti (III)-tannin combination tanning technology based on microwave irradiation
Content:
Microwave is a fast, efficient and energy-saving thermal resource, hence an attempt has been made for applying this technology in the combination tanning using titanium (III) and tannin extracts. In this work, the microwave effects on the complex reaction of Ti (III) with tannin extracts and leather products properties were investigated. The precipitation condition was used to characterize the complexation
degree between Ti (III) and tannin extracts. And the shrinkage temperature, tear strength, SEM, DSC, TG, FT-IR, and histological structure were used to characterize the changes in the physical and chemical
properties of the combined tanned leather.
Take-Away:
The results showed that microwave irradiation can accelerate the complex reaction of Ti (III) with tannin extracts. At the room temperature, the mixture of tannin and titanous sulphate kept stable at pH 3-4. In addition, microwave could increase the shrinkage temperature, tear strength, thermal stability, and fibrage of Ti (III)-tannin tanned leather, and it would not change the combination mode of the skins with
tanning agents as well as the hierarchical structure of collagen. Therefore, these results inferred that microwave could promote the reaction between Ti (III) and tannins and the combination of tannins with
collagen, which may provide a theoretical basis for the application of microwave in Ti (III)-tannin combination tanning technology
The Application of Downhole Vibration Factor in Drilling Tool Reliability Big Data Analytics - A Review
In the challenging downhole environment, drilling tools are normally subject to high temperature, severe vibration, and other harsh operation conditions. The drilling activities generate massive field data, namely field reliability big data (FRBD), which includes downhole operation, environment, failure, degradation, and dynamic data. Field reliability big data has large size, high variety, and extreme complexity. FRBD presents abundant opportunities and great challenges for drilling tool reliability analytics. Consequently, as one of the key factors to affect drilling tool reliability, the downhole vibration factor plays an essential role in the reliability analytics based on FRBD. This paper reviews the important parameters of downhole drilling operations, examines the mode, physical and reliability impact of downhole vibration, and presents the features of reliability big data analytics. Specifically, this paper explores the application of vibration factor in reliability big data analytics covering tool lifetime/failure prediction, prognostics/diagnostics, condition monitoring (CM), and maintenance planning and optimization. Furthermore, the authors highlight the future research about how to better apply the downhole vibration factor in reliability big data analytics to further improve tool reliability and optimize maintenance planning
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