Evaluation method of cracking resistance of lightweight aggregate concrete

The cracking behavior of lightweight aggregate concrete（LWAC） was investigated by mechanical analysis, SEM and cracking-resistant test where a shrinkage-restrained ring with a clapboard was used. The relationship between the ceramsite type and the cracking resistance of LWAC was built up and compared with that of normal-weight coarse aggregate concrete（NWAC）. A new method was proposed to evaluate the cracking resistance of concrete, where the concepts of cracking coefficient ζt（t） and the evaluation index Acr（t） were proposed, and the development of micro-cracks and damage accumulation were recognized. For the concrete with an ascending cracking coefficient curve, the larger Acr（t） is, the lower cracking resistance of concrete is. For the concrete with a descending cracking coefficient curve, the larger Acr（t） is, the stronger the cracking resistance of concrete is. The evaluation results show that in the case of that all the three types of coarse aggregates in concrete are pre-soaked for 24 h, NWAC has the lowest cracking resistance, followed by the LWAC with lower water absorption capacity ceramsite and the LWAC with higher water absorption capacity ceramsite has the strongest cracking resistance. The proposed method has obvious advantages over the cracking age method, because it can evaluate the cracking behavior of concrete even if the concrete has not an observable crack.     

Dynamic cluster member selection method for multi-target tracking in wireless sensor network简

Multi-target tracking（MTT） is a research hotspot of wireless sensor networks at present.A self-organized dynamic cluster task allocation scheme is used to implement collaborative task allocation for MTT in WSN and a special cluster member（CM） node selection method is put forward in the scheme.An energy efficiency model was proposed under consideration of both energy consumption and remaining energy balance in the network.A tracking accuracy model based on area-sum principle was also presented through analyzing the localization accuracy of triangulation.Then,the two models mentioned above were combined to establish dynamic cluster member selection model for MTT where a comprehensive performance index function was designed to guide the CM node selection.This selection was fulfilled using genetic algorithm.Simulation results show that this method keeps both energy efficiency and tracking quality in optimal state,and also indicate the validity of genetic algorithm in implementing CM node selection.     

Thermal properties of open-celled aluminum foams prepared by two infiltration casting methods

Contrastive research was carried out to study the thermal properties of open-celled aluminum foams prepared by counter-gravity infiltration casting system and the traditional process respectively.The experimental results show that the thermal conductivity coefficients of aluminum foams prepared by two different infiltration methods have similar increasing trend with the increase of particle size; along with the reducing porosity,the thermal conductivity coefficients will be enhanced oppositely.However,with the same particle size,the open-celled aluminum foam prepared by the former method has a higher thermal conductivity coefficient obviously.It is largely because that the sample prepared by counter-gravity infiltration casting has a lower void content and better dense crystallization of metal-matrix after the constant pressure process.     

填料级配对筋土界面特性的影响

不同填料级配对筋土界面特性的影响直接关系到工程的稳定性.通过室内大型直剪试验,研究了颗粒级配、密实度、筋材种类等对于界面强度的影响,深入了解筋土界面抗剪强度以及界面剪胀特性.试验结果表明,粗颗粒和细颗粒土分别与筋材的界面强度要明显大于级配较好的标准砂与筋材的界面强度.密实砂土界面强度具有类似混凝土材料强度高韧性低脆性破坏的特性.对于土工格栅,粗颗粒砂粒由于粒径较大达到峰值强度需要较大的剪切位移.     

民族传统体育项目引入高校体育课的研究

在高校开展少数民族传统优秀体育项目教学,不仅能使少数民族传统体育走向规范化、科学化,较好地展现学生的运动能力,培养民族文化情感,激发民族热情,更重要的是还能提高学生的身心健康和综合素质,有利于对民族传统体育的继承、发展和广泛地传播。     

煤气锅炉机组变负荷运行安全经济性分析

宁波钢铁有限公司余能发电厂135 MW汽轮发电机组利用富余煤气进行发电,承担了公司煤气调峰任务,导致机组负荷波动较大.通过变负荷试验,对机组变负荷运行时锅炉汽包使用寿命、锅炉水循环可靠性等进行全面分析,给出了经济性比较,提出了定滑定优化运行方式及运行时应注意的事项.     

红色文化:马克思主义中国化的文化棱镜

马克思主义基本原理的理论自觉、中国传统文化的文化自觉、人民群众的实践自觉的三者和谐互动与有机统一,创造与发展了中国主流意识形态与文化的特殊形态,二者构成了马克思主义中国化历程中的两个主要面相,在此进程中,生成了两种主要形态,即中国化的马克思主义理论形态和以革命遗迹为"底板"的红色文化形态。作为一种特殊的文化形态,红色文化不仅是马克思主义中国化的文化自觉和文化再造的产物,也是继续推进马克思主义中国化的文化展望的对象。     

给水塑料管材生物稳定性快速评价方法的建立与运用

给水塑料管材的生物稳定性直接影响供水水质.建立了评价饮用水塑料管材生物稳定性的新方法(BioMig),并使用该方法评价了典型塑料管材的生物稳定性.该方法主要由迁移实验、生物膜形成实验、病原菌形成潜能和毒性评价组成.该方法具有操作简单、易于推广、灵敏度高、重现性好等优点.研究结果表明:管道材料PEX-a和PEX-c具有很好生物稳定性,而密封材料EPDM 2%却具有很高的微生物再生长潜能.除EPDM 20%外的其它管材均能支持三种病原菌的生长,其中P.aeruginosa比E.coli O157和V.cholerae在迁移水中具有更高的生长潜能.EPDM 20%具有很高的有机物释放潜能,但由于其毒性作用抑制微生物在溶液及其表面生长.     

智能配电系统的发展现状与展望

随着分布式发电、电动汽车、智能电表和新一代无线通信等的发展,以及通过电价机制实现需求侧管理,配电系统的状况逐步发生变化,智能配电系统应运而生。作为未来智能电网的重要组成部分,智能配电系统可以充分利用自身的灵活性对资源进行优化配置,也有能力参与上层输电系统的优化调度或市场化运行。在过去的10多年间,国内外不少学者对未来配电系统的组成、体系架构、规划方法、运行策略等进行了比较广泛的研究,逐步建立了智能配电系统的概念。在此背景下,对含电动汽车的智能配电系统的研究现状做了评述并对将来的发展进行了展望。首先分析了智能配电系统的体系构成,并给出了一种系统架构;之后对智能配电系统的组成部分和核心技术进行了分析,并指出了有待研究或进一步研究的问题。最后,就智能配电系统的规划、设计、运行与控制等方面所面临的挑战做了探讨。     

稀土改性钛基二氧化锡催化电极制备及降解苯酚研究

改性钛基电极以析氧过电位低、副反应少、使用寿命长等优点得到广泛应用.采用钛酸丁脂作为钛源,SnCl4＆#183;5H2O为锡源,掺杂不同Ce量,采用浸渍法制备稀土改性钛基二氧化锡催化电极,用XRD对电极进行表征,同时采用制备的电极进行苯酚降解实验,考察了电流强度、降解时间、pH和电解质浓度对降解率的影响.稀土改性电极表面呈纳米结构,苯酚降解率随电流强度、降解时间、电解质浓度增加而升高,随pH值增大先增加后降低,实验条件下苯酚降解率可达到90％;通过实验数据得到了降解率的关联式,计算值与实验值吻合较好,误差在＆#177;10％范围内.