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961.
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963.
Hong Mei Gang Huang Tiancheng Liu Junguo Li 《International Journal of Software and Informatics》2007,1(1):101-128
Being the most popular runtime infrastructure for distributed systems, middleware can be viewed as a collection of common services. Since the development, deployment and maintenance of distributed systems rely largely on middleware services, the failure of middleware services puts a significant impact on the reliability and availability of the whole system. Though recovery-based fault tolerance is an effective way to improve the reliability of middleware services, it is far away from practice mainly because of the high complexity and cost of the recovery of correlated failures between interdependent services. In this paper,a framework for detecting and recovering the correlated failures of middleware services in an automated way is presented. First, the problem is investigated from two perspectives, i.e.,analyzing the role and impact of middleware services and illustrating a set of correlated failures in J2EE standard services as motivating examples. Then, a general coordinated recovery model is constructed with the elements necessary and su±cient for detecting and recovering correlated failures in middleware services. The supporting framework is demonstrated on three J2EE application servers, i.e., PKUAS, JBoss and JOnAS, one by one without fundamental modifications. Finally, based on the three enhanced application servers, many cases on J2EE common services, including the transaction service, database service, naming and directory service, security service and messaging service, are studied. The experiment results show the effectiveness and applicability of the framework presented in this paper. 相似文献
964.
基于彩色多普勒成像的近测等速面(PISA)算法是临床评价二尖瓣中心返流严重程度的一种常用方法,但对于偏心返流却存在极大低估。针对这一现状,从返流角度和湍流强度两个方面,对传统PISA算法的有效返流瓣口面积(EROA)进行修正。为比较首先用传统PISA算法的EROA对具有不同程度偏心返流的20例患者进行分级,结果误差较大;用改进PISA算法的EROA分级效果良好。对比实时三维超声测得的数据表明修改后的PISA算法相关性更好。 相似文献
965.
无驱型USB KEY专用接口的设计和实现是基于FPGA&ASIC的. 该设计主要使用Verilog语言在FPGA上实现USB协议,并提供针对USB收发器和微控制器的接口. 通过该接口USB KEY在接入系统后不需要驱动程序即可正常使用. 该设计通过了软件的仿真并在FPGA上进行了硬件验证. 相似文献
966.
967.
以园区为研究背景,基于"以热定电"、"以电定热"两种模式,对园区内的综合能源系统进行研究.针对夏季、冬季两个典型日设计了八种方案来对比系统配置液化空气储能与未配置液化空气储能时各子系统输出功率及总成本的变化.结果表明,在园区配置液化空气储能,采用"以热定电"模式运行时经济效益最高且能源损耗量最少.在大暑日,其总成本比未配置液化空气储能的系统降低6.1%.在大寒日,其总成本比未配置液化空气储能的系统总成本降低4.5%.同样配置液化空气储能的情况下,采用"以热定电"模式运行的系统要比"以电定热"模式总成本低.在大暑日总成本降低9.5%,在大寒日,总成本降低4.5%. 相似文献
968.
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Weichen Zhu Yuxuan He Minman Tong Xiaoyong Lai Shijia Liang Xu Wang Yanjuan Li Xiao Yan 《中国化学工程学报》2021,33(5):118-124
CH_4 storage associated with adsorbed natural gas(ANG) technology is an issue attracting great concern.Following the Advanced Research Project Agency-Energy(ARPA-E) targeted deliverable capacity of 315 cm~3·cm~(-3)(STP), hundreds of thousands of materials have been experimentally or theoretically evaluated,while the best results still show a 35% gap from the target. Moreover, recent theoretical research reveals that the target is beyond the possibility that real materials can be designed. To get rid of the awkward situation, we make attempts on investigating the CH_4 delivery performance under other operation conditions. Methods of raising the discharge temperature(to infinite high) or elevating the storage pressure(to 25 MPa) have been proved to show limited effectiveness. In this work, it is found that the ARPA-E target can be achieved by using a decreasing storage temperature strategy. By taking 280 Co RE(computation-ready, experimental) COFs(covalent organic frameworks) as ANG materials, when reduce the storage temperature to 190.6 K, the highest deliverable capacity can reach 392 cm~3·cm~(-3)(STP), and16.1% Co RE COFs can surpass the target. The target is also achievable when storage at 220 K. Structure performance relationships study shows strong correlation between deliverable capacity and void fraction. Hence, 120 hypothetical COFs are generated to ascertain the optimum void fraction. In addition,the performance of 2 D-COFs can be greatly enhanced by increasing the interlayer spacings, e.g. CH_4 deliverable capacity(storage at 190.6 K) of ATFG-COF can be improved from 239 to 411 cm~3·cm~(-3)(STP) when interlayer spacing is enlarged to 1.65 nm. 相似文献