Destructive and non-destructive evaluation of concrete for optimum sand to aggregate volume ratio

Aggregates are the biggest contributor to concrete volume and are a crucial parameter in dictating its mechanical properties. As such, a detailed experimental investigation was carried out to evaluate the effect of sand-to-aggregate volume ratio (s/a) on the mechanical properties of concrete utilizing both destructive and non-destructive testing (employing UPV (ultrasonic pulse velocity) measurements). For investigation, standard cylindrical concrete samples were made with different s/a (0.36, 0.40, 0.44, 0.48, 0.52, and 0.56), cement content (340 and 450 kg/m³), water-to-cement ratio (0.45 and 0.50), and maximum aggregate size (12 and 19 mm). The effect of these design parameters on the 7, 14, and 28 d compressive strength, tensile strength, elastic modulus, and UPV of concrete were assessed. The careful analysis demonstrates that aggregate proportions and size need to be optimized for formulating mix designs; optimum ratios of s/a were found to be 0.40 and 0.44 for the maximum aggregate size of 12 and 19 mm, respectively, irrespective of the W/C (water-to-cement) and cement content.     

Influence of sintering temperature on the crystallization and mechanical properties of BN-MAS composites

A type of boron nitride–magnesium aluminum silicate (BN-MAS) composite ceramics was fabricated by hot-press sintering at different sintering temperatures. The relationship between the sintering temperature and microstructure was investigated by analyzing the interaction between hexagonal boron nitride (h-BN) and the MAS phase. The main MAS phase in the composite ceramics is the α-cordierite phase at a sintering temperature of 1300°C. At temperatures above 1400°C, the inhibitory effect of h-BN on the crystallization of the MAS system is significant, and MAS mainly exists in the form of an amorphous phase. The composite sintered at 1700°C exhibited the highest bending strength of 218MPa. h-BN and MAS were co-enhanced. MAS can be used as an effective liquid-phase sintering aid to assist in the sintering of h-BN, whereas h-BN can absorb the fracture energy of the composite ceramics through the pull-out and bridging effect of the particles.     

基于Agent的SYN Flood攻击仿真

针对分布式SYN Flood攻击的特点,采用多Agent的方法对其进行建模仿真,通过构建系统整体框架,分析A—gent通信和行为的具体实现,最后基于JADE平台构建了一个多Agent的SYN Flood攻击仿真系统,解决了从底层开发该类型的仿真系统存在难度大、周期长的问题,为一些耗时的网络对抗进行反复研究提供了一种方法。     

A platform for P2P agent-based collaborative applications

The operational environment can be a valuable source of information about the behavior of software applications and their usage context. Although a single instance of an application has limited evidence of the range of the possible behaviors and situations that might be experienced in the field, the collective knowledge composed by the evidence gathered by the many instances of a same application running in several diverse user environments (eg, a browser) might be an invaluable source of information. This information can be exploited by applications able to autonomously analyze how they behave in the field and adjust their behavior accordingly. Augmenting applications with the capability to collaborate and directly share information about their behavior is challenging because it requires the definition of a fully decentralized and dependable networked infrastructure whose nodes are the user machines. The nodes of the infrastructure must be collaborative, to share information, and autonomous, to exploit the available information to change their behavior, for instance, to better accommodate the needs of the users to prevent known problems. This paper describes the initial results that we obtained with the design and the development of an infrastructure that can enable the execution of collaborative scenarios in a fully decentralized way. Our idea is to combine the agent-based paradigm, which is well suited to design collaborative and autonomous nodes, and the peer-to-peer paradigm, which is well suited to design distributed and dynamic network infrastructures. To demonstrate our idea, we augmented the popular JADE agent-based platform with a software layer that supports both the creation of a fully decentralized peer-to-peer network of JADE platforms and the execution of services within that network, thus enabling JADE multiagent systems (MASs) to behave as peer-to-peer networks. The resulting platform can be used to study the design of collaborative applications running in the field.     

电网调度操作票系统的发展与应用

主要对电网调度操作票专家系统的发展历程作了详细叙述,并对一些新技术在电网调度操作票专家系统中的应用进行了介绍,阐述了操作票专家系统应用的现状和现存的主要问题,并指出了操作票专家系统未来的发展前景。     

基于Multi-Agent系统的含分布式电源电网能源优化管理

在市场运行环境下,为了寻求微电网成本利益和环境效益的最大化,提出基于Multi-Agent系统能源优化管理策略。该研究首先构建Multi-Agent系统。此系统包括市场管理Agent(MOA),微电网管理Agent(MMA),公共电网Agent(UGA)和分布式发电Agent(DGA)。根据各微电网管理Agent上报的发电计划,在市场管理Agent中设计电价竞标策略用来确定各微电网的最佳交易电价和中标电量,以确保微电网经济利益最大化。在此基础上,在各微电网管理Agent中设计能量管理策略,并采用改进粒子群算法来确定微电网内部各分布式发电Agents的最佳功率分派,从而最小化微电网的运行成本。最后仿真验证了该方案的有效性。     

Ordered structure and thermal property of acid-modified high-amylose rice starch

High-amylose cereal starch has a great benefit on human health. Acid modification is very helpful for application of high-amylose starch in food and non-food industries. In this study, the ordered structure of acid-modified high-amylose rice starch was investigated by GPC, HPAEC, ¹³C CP/MAS NMR and XRD. Acid preferentially degraded the amylose, then A chain and short B chain of amylopectin. Relative double helix content and crystallinity both initially increased sharply and then progressively with acid hydrolysis. The relative crystallinity of starches obtained from ¹³C CP/MAS NMR was higher than that from XRD. The onset gelatinisation temperature decreased, while the peak and conclusion temperatures increased with increasing hydrolysis time. The endothermic value initially increased and then decreased with acid hydrolysis. The swelling power decreased while solubility increased after acid hydrolysis. These results add to our understanding of the effect of acid hydrolysis on the high-amylose rice starch.     

基于MAS和BP网络的近距离目标预测法

以轨迹拟合法为基础，将目标预测问题转化为对预测模型参数优化搜索的问题。结合MAS、BP网络和位置预测原理，提出将近距离目标视为刚体。其状态按自由度划分为6个，其中3个自由度表示空间位置，另外3个自由度表示角的转动向量，6个自由度看作6个子网，分别进行子网预测，再进行组网的近距离目标预测法。最后，以无人机为例对算法进行仿真计算，验证了其正确性和可行性。     

New Algorithm for FMS Scheduling Based on Multiagent System Architecture

Redefined benefit-driven function is used to study the dynamic scheduling of FMS based on multiagent architecture. Each agent is dedicated to a work center, i.e. a set of the manufacturing system. In one hand, each agent selects locally and dynamically the dispatching rule(DR) that seems to be most suited to the operating conditions, production objectives and current shop status. On the other hand, each task should bring certain amount of benefit for the manufacturer. So, it is reasonable to have the dynamic scheduling of FMS relying upon multiagent architecture using the benefit-driven function as a strategy. Well, today's manufacturing corporation, especially the high & new technology one and deep machining one, the cost of their products is mainly determined by how much the knowledge is input From this viewpoint, we redefined the benefit-driven function, hi the end, this approach is compared with other existing DRs on a job-shop problem, already used in other research works.     

Liquid phase reactions catalyzed by Fe- and Mn-sulphated ZrO2

Fe- and Mn-promoted ZrO₂–SO₄ (ZS) powders were prepared both by a single step sol–gel reaction and by impregnation of the zirconia hydrous precursor. The samples were calcined at 890 K and characterized for the structural (XRD) and morphological features (BET method). Surface functionalities were investigated by XPS, ¹H MAS NMR and FTIR analyses. The liquid medium catalytic activity was tested with respect to both the esterification of benzoic acid to methylbenzoate and the benzylation of toluene. The acidity features appeared not to be significantly different among the various samples while all surface characterizations showed a lower affinity to retain water by the metal-promoted samples with respect to ZS, the more so in the case of iron-containing samples. The presence of Mn reduced the surface area and depressed the catalytic activity. Iron-doped catalysts appeared, instead, to be more efficient than ZS especially for the benzylation of toluene.