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Cereal Crops for Biogas Production: A Review of Possible Impact of Elevated Temperature
Alioune Senghor,
Christoph Müller,
Issakha Youm
Issue:
Volume 5, Issue 3, September 2020
Pages:
27-32
Received:
29 October 2019
Accepted:
28 November 2019
Published:
9 June 2020
Abstract: Biogas production from crops and their residues is widely used as feed because of its availability and high methane content due to its calorific value. The aim of this study is to estimate the response of cereal crops such as maize, sorghum, wheat, barley and rice to elevated temperature and his impact on biogas production by meta-analysis method. Studies show that increasing temperature by 1°C and 2°C respectively decreased biomass yield by -5% to -7% (wheat), -5% to -16% (rice), -7% to -12% (sorghum), -10% to -14% (maize) and -4% (barley). On the other hand, key element which determine the quality of the plant and which are negatively affect by elevated temperature are the basic elements for a good quality and quantity of biogas such as ( lipids, carbohydrates, micro and macro-element). If protein concentration increases under warming, decrease in grain is largely due to lower starch concentration under elevated temperature, -13 to -33% for barley, -2 to -33% for wheat and -2 to -6% for rice. Lipids also decrease under elevated temperature and some nutrients like Selenium (Se), Cobalt (Co) and Aluminum (Al) which decrease respectively by -43.5%, -15% and -22%. Based on these results, we can argued that biogas production from cereal crops is threatened in the future.
Abstract: Biogas production from crops and their residues is widely used as feed because of its availability and high methane content due to its calorific value. The aim of this study is to estimate the response of cereal crops such as maize, sorghum, wheat, barley and rice to elevated temperature and his impact on biogas production by meta-analysis method. ...
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A Method for Electroless Nickel Plating on Aluminum Alloy Surface
Ming Chen,
Wei Dong,
Cherry Qin
Issue:
Volume 5, Issue 3, September 2020
Pages:
33-37
Received:
17 January 2020
Accepted:
8 June 2020
Published:
23 July 2020
Abstract: According to the following plating processes: deoiling → washing → pickling → washing → drying → weighing → electroless plating → washing → drying → weighing. It can obtain Ni-P deposit on aluminum alloy. It studied the influence of bath composition and process parameters on the composition and deposition rate of the alloy coating. Under temperature of 85~90°C, nickel sulfate hexahydrate 15~35g/L, sodium hypophosphite 10~30g/L, sodium citrate 5~10g/L, tartaric acid 1~2g/L, pH 3~5, reaction time 30~60min, load factor 1.0~2.0dm2/L. The microstructure, surface morphology, composition and valence of the elements in the alloy coating were studied by metallographic microscope, SEM, EDS and other modern analytical methods. The size of spherical grain was below 1um and compact distribution. The chemical coatings were mainly composed two elements, which were phosphorous and nickel. The mass percentage of phosphorous was about 15%, and the other one was about 80~85%. The corrosion resistance of the alloy coating was studied by CASS [1] test method, through 80h CASS test detection, the protection class of chemical coating can be reached 5. The relevant evaluation criteria can be referred to GB/T 6461-2002 [2]. The results show that the Ni-P binary amorphous alloy can be successfully prepared by this process.
Abstract: According to the following plating processes: deoiling → washing → pickling → washing → drying → weighing → electroless plating → washing → drying → weighing. It can obtain Ni-P deposit on aluminum alloy. It studied the influence of bath composition and process parameters on the composition and deposition rate of the alloy coating. Under temperatur...
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Prediction Model of Material Removal for Polishing Single Crystal Silicon by Cluster Magnetorheological Finishing with Dynamic Magnetic Fields Based on BP Neural Network
Qixiang Zhang,
Mingliang Guo,
Jiayun Deng,
Jisheng Pan
Issue:
Volume 5, Issue 3, September 2020
Pages:
38-44
Received:
11 September 2020
Accepted:
27 September 2020
Published:
13 October 2020
Abstract: Magnetorheological Finishing (MRF) is a new optical surface processing method, which has the advantages that good polishing effect, no subsurface damage, and suitable for complex surface processing. However, the interaction mechanism between the MRF pad and the workpiece is very complicated, so that the existing MRF material removal theoretical model is not accurate enough to establish the relationship between polishing parameters and material removal. In order to improve the processing efficiency and explore the material removal mechanism, a cluster magnetorheological finishing (CMRF) with dynamic magnetic fields method was proposed. Studying CMRF with dynamic magnetic fields material removal model is helpful to explain the removal mechanism more deeply, and improve the processing efficiency. In this study, the CMRF method was used to conduct a multi-factor orthogonal test on 2-inch single crystal silicon wafers. Based on the empirical Preston equation, the relationship between the machining gap and the polishing pressure was explained. Orthogonal experiments were done for a series of speeds, and obtaining the order of the influence of various factors on the average surface roughness Ra of the workpiece was: workpiece rotation speed > polishing disk speed > magnetic poles rotation speed > oscillating speed; the material removal rate (MRR) was: polishing disk speed > workpiece rotation speed > magnetic poles rotation speed > oscillating speed. Then combining with the orthogonal experimental data, and taking the surface roughness Ra and MRR as evaluation criteria, using Adam (Adaptive momentum) optimization algorithm to build a prediction model of Ra and MRR for polishing single crystal silicon by CMRF with dynamic magnetic fields based on BP neural network. For the prediction result, Ra of the maximum error was 7.05%, the minimum was 0.31%; MRR of the maximum error was 10.22%, the minimum was 1.32%. Therefore, the feasibility of this model for predicting the results of CMRF was verified, and it laid a good foundation for the development of CMRF technology and its industrial application.
Abstract: Magnetorheological Finishing (MRF) is a new optical surface processing method, which has the advantages that good polishing effect, no subsurface damage, and suitable for complex surface processing. However, the interaction mechanism between the MRF pad and the workpiece is very complicated, so that the existing MRF material removal theoretical mod...
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