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1.
The supervision of a hybrid power plant, including solar panels, a gas microturbine and a storage unit operating under varying solar power profiles is considered. The Economic Supervisory Predictive controller assigns the power references to the controlled subsystems of the hybrid cell using a financial criterion. A prediction of the renewable sources power is embedded into the supervisor. Results deteriorate when the solar power is unsteady, owing to the inaccuracy of the predictions for a long-range horizon of 10 s. The receding horizon is switched between an upper and a lower value according to the amplitude of the solar power trend. Theoretical results show the relevance of horizon switching, according to a tradeoff between performance and prediction accuracy. Experimental results, obtained in a Hardware In the Loop (HIL) framework, show the relevance of the variable horizon approach. Power amplifiers allow us to simulate virtual components, such as a gas microturbine, and to blend their powers with that of real devices (storage unit, real solar panels). In this case, fuel savings, reaching 15%, obtained under unsteady operating conditions lead to a better overall performance of the hybrid cell. The overall savings obtained in the experiments amount to 12%. 相似文献
2.
Combination of heat treatment and chitosan coating to improve postharvest quality of wolfberry (Lycium barbarum) 下载免费PDF全文
Zhaojun Ban Wenwen Wei Xiangzheng Yang Jianhua Feng Junfeng Guan Li Li 《International Journal of Food Science & Technology》2015,50(4):1019-1025
The synergistic application of hot water dip at 42 °C for 30 min and 1% chitosan coating on differentiation in postharvest quality traits, microstructure as well as microbiological evolution of wolfberry fruits was investigated. Fresh wolfberry fruits were stored at 2 ± 0.5 °C and 90% relative humidity (RH) for 28 days. Results indicated the combination of prestorage heat treatment and chitosan coating maintained higher levels of ascorbic acid, total phenolic contents and antioxidant capacity as well as lower decay, compared with untreated wolfberry fruits. The possible mechanism was that the heat treatment almost sealed open stomata to limit the sites of pathogen penetration into fruits independently, followed by the biofilm formed by chitosan which controlled secondary infections as well as slowed changes in fruit respiration and metabolic activity in wolfberries. The synergistically treated fruit also exhibited a higher acceptability obtained by sensory analysis after cold storage. In this sense, the integrated application of heat treatment and chitosan coating could be regarded as an effective strategy to extend storage life and maintain the postharvest quality of wolfberry fruits. 相似文献
3.
电网的安全水平主要取决于其使用产品的质量是否过关。如果产品的质量较好,则能建造出优质的电网,电网的安全水平便会随之提高。因此,应加强对产品质量的监督管理,从而提高电网的安全水平。我们可建立质量监督管理系统,及时抽检出质量不过关的产品,从而消除电网运行过程中潜在的安全隐患。 相似文献
4.
Goat milk has specific chemical composition and physical properties. The purpose of this study was to investigate the change of milk quality and emulsion stability during 60 d frozen storage. Milk sample was taken from three Ettawah Crossedbred goats that were divided into three groups. Samples were frozen and stored for 0, 30 and 60 days. At the end of each storage periode, milk sample was thawed in the refrigerator and analyzed for total number of bacteria, chemical (acidity, pH, free fatty acids), physical (alcohol test, clot on boiling test) quality, and emulsion stability. The microbiological and chemical data were analyzed statistically using one way ANOVA, whereas physical quality and emulsion stabilty were expressed qualitatively. There were no change in the total bacteria, acidity, pH and free fatty acid (FFA) of milk during storage, whereas the assessment by 70% alcohol showed positive since 0 d. Emulsions stability changed after 30 d of storage. While, the clot on boiling (COB) test of milk was positive at 60 d of storage. Recommendation is frozen storage of goat milk should not longer than 30 d. 相似文献
5.
For the first time, we present the unique features exhibited by power 4H–SiC UMOSFET in which N and P type columns (NPC) in the drift region are incorporated to improve the breakdown voltage, the specific on-resistance, and the total lateral cell pitch. The P-type column creates a potential barrier in the drift region of the proposed structure for increasing the breakdown voltage and the N-type column reduces the specific on-resistance. Also, the JFET effects reduce and so the total lateral cell pitch will decrease. In the NPC-UMOSFET, the electric field crowding reduces due to the created potential barrier by the NPC regions and causes more uniform electric field distribution in the structure. Using two dimensional simulations, the breakdown voltage and the specific on-resistance of the proposed structure are investigated for the columns parameters in comparison with a conventional UMOSFET (C-UMOSFET) and an accumulation layer UMOSFET (AL-UMOSFET) structures. For the NPC-UMOSFET with 10 µm drift region length the maximum breakdown voltage of 1274 V is obtained, while at the same drift region length, the maximum breakdown voltages of the C-UMOSFET and the AL-UMOSFET structures are 534 and 703 V, respectively. Moreover, the proposed structure exhibits a superior specific on-resistance (Ron,sp) of 2 mΩ cm2, which shows that the on-resistance of the optimized NPC-UMOSFET are decreased by 56% and 58% in comparison with the C-UMOSFET and the AL-UMOSFET, respectively. 相似文献
6.
Spray quality is the critical factor which decides the efficacy of Small Quantity Lubrication (SQL) technology in a high specific energy involved machining process like grinding. Yet, the understanding about spray quality, the actual process mechanics and its effect on machining performance is inadequate. The present work is an attempt to establish a correlation between the spray input variables, quality of the spray and machining performance of SQL grinding through modelling and experiments. Using computational fluid dynamic techniques, the variation of droplet size, droplet velocity, number of droplets and heat transfer coefficient have been analysed at different input parameters and the computed trends have been verified and validated. CFD modelling of spray indicates that it is possible to produce aerosol medium with high heat dissipation ability at moderately high air pressure and low flow rate. It also shows that any increase in atomising air pressure favourably leads to notable increase in wetting area and also results in substantial enhancement in heat dissipation ability. Reduction of residual stress is thus remarkably good. On the other hand, grinding fluid flow rate, if increased, offers significantly better lubricity and reduces the grinding force which also reduces tensile residual stress. Short spell grinding test results are found to be in good agreement with CFD results. 相似文献
7.
Suitability,efficiency and microbiological safety of novel physical technologies for the processing of ready‐to‐eat meals,meats and pumpable products 下载免费PDF全文
Alexandros Ch. Stratakos Anastasios Koidis 《International Journal of Food Science & Technology》2015,50(6):1283-1302
Consumer studies and market reports show an increase in consumption of ready‐to‐eat (RTE) foods. Although conventional processing technologies can in most cases produce safe products, they can also lead to the degradation of nutritional compounds and negatively affect quality characteristics. Consumers strongly prefer food that is minimally processed with the maximum amount of health‐promoting substances. Novel processing technologies as pre‐ or post‐treatment decontamination methods or as substitutes of conventional technologies have the potential to produce foods that are safe, rich in nutrient content and with superior organoleptic properties. Combining novel with conventional processes can eliminate potential drawbacks of novel technologies. This review examines available scientific information and critically evaluates the suitability and efficiency of various novel thermal and nonthermal technologies in terms of microbial safety, quality as well as nutrient content on the production of RTE meals, meats and pumpable products. 相似文献
8.
9.
针对不同地质目标的叠前时间偏移成像解释评价 总被引:3,自引:0,他引:3
随着计算机硬件和地震勘探成像技术的发展,叠前时间偏移正逐步替代常规的NMO加DMO加叠后时间偏移成为地震数据成像处理方法的主流。但对于不同的地质目标,叠前时间偏移的成像效果是否优于常规NMO加DMO加叠后时间偏移的成像效果呢?为此,从地震数据成像处理方法、处理流程和处理参数等方面进行了讨论,并基于某地区三维数据常规处理结果和叠前时间偏移处理结果,针对不同地质目标进行了剖析与评价。认为:叠前时间偏移成像的垂向分辨率较常规处理明显降低,但对于空间波阻抗变化明显的河流和断层,叠前时间偏移成像的空间分辨率要高于常规处理;对于小于1/4波长的叠置薄储层,叠前时间偏移成像的垂向和空间分辨率低于常规处理结果。 相似文献
10.
应用人工神经网络处理部分广东地区煤质分析数据,建立网络模型,预测出煤的发热量,经实测值与预测值比较,在一定的煤种范围内预测值与实测值比较接近。 相似文献