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991.
Various intrusion detection systems (IDSs) have been proposed in recent years to provide safe and reliable services in cloud computing. However, few of them have considered the existence of service attackers who can adapt their attacking strategies to the topology-varying environment and service providers’ strategies. In this paper, we investigate the security and dependability mechanism when service providers are facing service attacks of software and hardware, and propose a stochastic evolutionary coalition game (SECG) framework for secure and reliable defenses in virtual sensor services. At each stage of the game, service providers observe the resource availability, the quality of service (QoS), and the attackers’ strategies from cloud monitoring systems (CMSs) and IDSs. According to these observations, they will decide how evolutionary coalitions should be dynamically formed for reliable virtual-sensor-service composites to deliver data and how to adaptively defend in the face of uncertain attack strategies. Using the evolutionary coalition game, virtual-sensor-service nodes can form a reliable service composite by a reliability update function. With the Markov chain constructed, virtual-sensor-service nodes can gradually learn the optimal strategy and evolutionary coalition structure through the minimax-Q learning, which maximizes the expected sum of discounted payoffs defined as QoS for virtual-sensor-service composites. The proposed SECG strategy in the virtual-sensor-service attack-defense game is shown to achieve much better performance than strategies obtained from the evolutionary coalition game or stochastic game, which only maximizes each stage's payoff and optimizes a defense strategy of stochastic evolutionary, since it successfully accommodates the environment dynamics and the strategic behavior of the service attackers. 相似文献
992.
Polyethylene, as non-polar material, shows a high affinity especially to liquid non-polar aromatic and aliphatic hydrocarbons, and liquid hydrocarbons (LHC) to a certain extent migrate into the bulk material by sorption, leading to material plasticization (i.e., drop in modulus and yield stress). This paper aims to study the crack growth mechanism and failure behavior of commercial pipe grade materials when exposed to deionized water or LHC (90/10 wt% i-octane/toluene) under the simultaneous application of cyclic loads. The results of the cyclic crack growth experiments with three PE 100 pipe grades, using cracked round bar (CRB) specimens and performed at two different temperatures (35 °C and 60 °C), are compared in terms of the specimen lifetimes, and the micro-modes and kinetics of failure by referring to concepts of fracture mechanics. Most importantly, while crack advance is preceded by crack-tip crazing in water, shear yielding takes place at crack-tips in the LHC environment. 相似文献
993.
Yong‐Ning Zhou Mahsa Sina Nathalie Pereira Xiqian Yu Glenn G. Amatucci Xiao‐Qing Yang Frederic Cosandey Kyung‐Wan Nam 《Advanced functional materials》2015,25(5):696-703
Searching high capacity cathode materials is one of the most important fields of the research and development of sodium‐ion batteries (SIBs). Here, we report a FeO0.7F1.3/C nanocomposite synthesized via a solution process as a new cathode material for SIBs. This material exhibits a high initial discharge capacity of 496 mAh g?1 in a sodium cell at 50 °C. From the 3rd to 50th cycle, the capacity fading is only 0.14% per cycle (from 388 mAh g?1 at 3rd the cycle to 360 mAh g?1 at the 50th cycle), demonstrating superior cyclability. A high energy density of 650 Wh kg?1 is obtained at the material level. The reaction mechanism studies of FeO0.7F1.3/C with sodium show a hybridized mechanism of both intercalation and conversion reaction. 相似文献
994.
Maryam Karimi-Shamsabadi Mohsen Behpour 《International Journal of Hydrogen Energy》2021,46(53):26989-27013
In the present study, a TiO2 nanotube (TNAs) supported Sb2S3–TiO2–SiO2 (STS/TNAs), and Ag2S–TiO2–SiO2 (ATS/TNAs) hybrid novel photocatalysts were prepared and characterized by XRD, FT-IR, SEM-EDX, X-ray mapping and, DRS. EIS was employed, and an equivalent circuit model is proposed. Flat-band potential and free carrier concentration were determined by Mott–Schottky plots. The obtained catalysts were used in the photodegradation of a binary mixture of Basic Blue 41 (BB41) and Basic Red 46 (BR46) dyes. Compared with ATS/TNAs, STS/TNAs photocatalyst showed the highest apparent rate constant for BB41 dye, about two times higher, and BR41 dye more than 1.5 times. EIS results agreed with the photodegradation results, so the STS/TNAs system with higher charge transfer ability than the ATS/TNAs system showed the best photodegradation activity. The optimization effect of the amount of Sb2S3, TiO2, and SiO2 doped on the TNAs on the photocatalytic activity of the STS/TNAs was done using a central composite rotatable design (CCRD) based response surface methodology (RSM). Results have shown catalyst containing 12.2% Sb2S3 and 27.1% SiO2/TNAs (S3TS3/TNAs) the best photodegradation activity was obtained. The GC-Mass analysis was done to detect the degradation intermediates formed during the photodegradation process. 相似文献
995.
Yi-Ming Zhao Shikha Ojha Catherine M. Burgess Da-Wen Sun Brijesh K. Tiwari 《International Journal of Food Science & Technology》2021,56(2):721-732
This study aimed to evaluate the influence of plasma treatment time, bacterial exposure time to PAW and bacterial species on the inactivation efficacy of plasma-activated water (PAW), with additional investigation of the inactivation mechanisms of PAW. Six bacterial species, including Listeria innocua, Staphyloccus aureus, Escherichia coli, Pseudomonas fluorescens, Shewanella putrefaciens and Aeromonas hydrophila were selected as the representative bacteria. The initial bacterial concentration was around 7 log CFU ml−1 after mixing with PAW, and the inactivation efficacy was measured after different exposure times during the 4 °C storage. Scanning electron microscopy (SEM) images of the bacteria after PAW treatment were carried out to inspect the cell structure damage, and physicochemical properties of PAW, including pH, conductivity and long-living reactive species of H2O2, , and , were examined. The results showed that the inactivation efficacy of PAW was positively correlated with plasma treatment time and bacterial exposure time, and for the species examined in this study, the Gram-negative species were more sensitive to PAW than the Gram-positive species. Cell structure damage, including shrinkage, distortion, or holes, was observed after PAW treatment. The pH of PAW was acidified to 2.5–2.9, and conductivity was significantly increased to 518.0 μs cm−1. and H2O2 were reduced during the 48 h storage, while an increased concentration was observed for . This study demonstrated that the processing parameters of plasma treatment time, exposure time and characteristics of bacteria can significantly affect the inactivation efficacy of PAW. 相似文献
996.
Naveed Ahmed Khan Guftaar Ahmad Sardar Sidhu Ahmed Bilal Awan Zain Ali Anzar Mahmood 《国际能源研究杂志》2019,43(13):6721-6739
Microgrids provide promising solution for integration of renewable energy sources in the electrical grid. To exploit the key benefits, achieving the economical operation of renewable aided microgrids has become necessary and is a challenging task. This paper presents an efficient optimization model to minimize the operational cost of a solar integrated microgrid. We formulate a joint optimization mixed integer problem for appropriate modeling of the system under various practical constraints. An efficient solution is obtained with a distributed approach such that the original problem is solved in two stages. Dual decomposition approach is adopted for cost, emissions, and solar share optimization. Lagrange relaxation, Lambda iteration method, and binary integer programming are employed to obtain the joint optimization solution. Finally, the performance of the proposed model is validated through simulations that show that an overall cost reduction of 4.2070e+04 $ and emission reduction of 7.2001e+03 kg are achieved with the proposed model. 相似文献
997.
以壳聚糖(CTS)和生物炭(AC)为原料,采用原位沉淀法制备了壳聚糖-生物炭(CTS-AC)复合材料,研究了吸附时间、铀初始浓度、初始pH值、温度和干扰离子等因素对CTS-AC吸附U(Ⅵ)的影响,探讨了CTS-AC对U(Ⅵ)的吸附动力学、等温线,采用傅里叶红外光谱(FT-IR)、X射线衍射(XRD)、扫描电镜(SEM-EDS)及比表面积分析(BET)等手段进行了相关机理分析。实验结果表明,CTS-AC吸附U(Ⅵ)的最佳条件为:pH=4、CTS-AC投加量0.8~1 g/L、吸附时间240 min,在此条件下,最大吸附率可达94.85%。CTS-AC对U(Ⅵ)的吸附等温线模型符合Langmuir模型,U(Ⅵ)的吸附动力学符合准二级模型;高浓度Cu2+对CTS-AC吸附U(Ⅵ)的抑制作用明显;FT-IR、XRD和EDS结果表明,CTS的负载未改变AC的原结构,仅增大了其孔径、增加了结合位点。CTS-AC对U(Ⅵ)的吸附机制为配位作用以及离子交换。 相似文献
998.
摘要:为了深入了解非均相脱磷剂中固体CaO在3CaO·P2O5-2CaO·SiO2(C2S-C3P)饱和熔渣中的溶解及反应机理,采用静态浸入法和旋转圆柱法研究固体CaO在C2S-C3P饱和CaO-SiO2-FetO-P2O5(10%)渣中的溶解行为,运用FESEM/BSED EDS对固体CaO和熔渣界面进行了观察,分析了固体CaO与C2S-C3P饱和熔渣间的反应机理。结果表明,加强对熔池的搅拌,能够加快固体CaO在熔渣中的侵蚀速度和溶解速度;发现了固体CaO在饱和熔渣中的溶解数量受熔渣中FeO通过边界层向固体内部渗透深度的影响,FeO渗透深度越深,溶解越多;固体CaO先与熔渣中的硅和磷反应生成磷含量低的C2S-C3P固溶体,待一段时间后,最终生成磷含量高的Ca5(PO4)2SiO4。 相似文献
999.
This paper presents a dual Newton scheme for tree‐sparse quadratic programs as they may arise in the field of stochastic programming. Previous work suggests to introduce auxiliary variables to decompose the tree into scenarios and use Newton's method to solve a dual problem formulation. Following a different approach, we apply the same principle directly on the tree‐sparse problem, avoiding the increase in dimensionality. In combination with a tailored algorithm for the calculation of the step direction, which is typically the most expensive operation per iteration, the proposed algorithm achieves a linear complexity in the number of nodes and supports parallel processing of the tree branches in a stage‐wise fashion. An open‐source implementation of the presented dual Newton strategy is publicly available in treeQP , a toolbox of open‐source solvers for tree‐sparse quadratic programs. 相似文献
1000.