Hydrogen production by radio frequency plasma stimulation in methane hydrate at atmospheric pressure

Methane hydrate, formed by injecting methane into 100 g of shaved ice at a pressure of 7 MPa and reactor temperature of 0 °C, was decomposed by applying 27.12 MHz radio frequency plasma in order to produce hydrogen. The process involved the stimulation of plasma in the methane hydrate with a variable input power at atmospheric pressure. It was observed that production of CH₄ is optimal at a slow rate of CH₄ release from the methane hydrate, as analyzed by in light of the steam methane reforming (SMR) and the methane cracking reaction (MCR) processes in accordance with the content of gas production. In comparison with the steam methane reforming (SMR), it was found that methane-cracking reaction (MCR) was dominant in conversion of CH₄ into hydrogen. An H₂ content of 55% in gas production was obtained from conversion of 40% of CH₄ at an input power of 150 W. The results clearly show that hydrogen can be directly produced from methane hydrate by the in-liquid plasma method.     

Mineralogy,geochemistry and expansion testing of an alkali-reactive basalt from western Anatolia,Turkey

In this paper, the alkali–silica reaction performance of a basalt rock from western Anatolia, Turkey is reported. It is observed that the rock causes severe gel formation in the concrete microbar test. It appears that the main source of expansion is the reactive glassy phase of the basalt matrix having approximately 70% of SiO₂. The study presents the microstructural characteristics of unreacted and reacted basalt aggregate by optical and electron microscopy and discusses the possible reaction mechanism. Microstructural analysis revealed that the dissolution of silica is overwhelming in the matrix of the basalt and it eventually generates four consequences: (1) Formation of alkali–silica reaction gel at the aggregate perimeter, (2) increased porosity and permeability of the basalt matrix, (3) reduction of mechanical properties of the aggregate and (4) additional gel formation within the aggregate. It is concluded that the basalt rock is highly prone to alkali–silica reaction. As an aggregate, this rock is not suitable for concrete production.     

Material characterization of blended epoxy resins related to fracture toughness

The present study describes the effect of the macromolecular modifications on the fracture toughness of an epoxy system. We synthesized epoxy networks by the reaction of diglycidyl ether of bisphenol A (DGEBA) with methyl-tetrahydro-phthalic anhydride (MTHPA), initiated by a tertiary amine. Several materials were obtained by adding a high molecular weight monomer to one with low molecular weight (both based on DGEBA) at different concentrations. In every case, a stoichiometric amount of MTHPA was employed. The glass transition temperature and the Angell’s fragility index, derived from thermo-viscoelastic properties, were used to characterize the materials. Relationship between these two parameters and the fracture properties, including the fracture toughness and the microscopic roughness of the fracture surfaces observed by atomic force microscope (AFM), was then investigated. We found that there were direct correlations among the glass transition temperature, the fragility, the fracture toughness, and the roughness. This study revealed that both the glass transition temperature and the fragility are effective for characterizing material in relation to the fracture toughness of the blended epoxy resins.     

A dynamic load balancing algorithm for Quality of Service and mobility management in next generation home networks

Heterogeneity of connection technologies and nodes mobility open new challenges in home networks control strategies. Moreover, user’s needs are changing towards applications requiring high transmission speeds such as 3D gaming, enhanced interactivity and high definition video. Each of those applications puts several constraints on the network capabilities to guarantee requirements on the Quality of Service. In this paper we introduce an innovative concept based on fast load balancing algorithm operating on top of a convergence layer, in order to rapidly react to network changes and contemporaneously to satisfy strict application demands. We formulated the load balancing problem as a Multi-Commodity Flow and resolved it with a column generation approach using Lagrangian Relaxation and Dijkstra algorithm. The load balancing problem computational complexity is decreased with respect to state of the art load balancing solutions based on linear programming techniques. Proof of concept simulation results are reported.     

Enhancing student participation in a design-centric mechatronics class

This paper presents the work to address the problem of student participation in a class. The work is particularly applied to a design-centric mechatronics-related classes, using web, smartphone, and mechatronics-related technology. The specific issues to be targeted on are the irregular attendance and the low participation of students during classes using on-the-spot questions and answers on design-centric subjects to improve and adaptively redirect the orientation of targeted students as well as the whole class. The approach and system have been developed with Android smartphone-based application and Apache Tomcat-based server. This allows data storage and opens up possibility for statistical analysis in the future.     

岸堤水库岩溶坝基防渗处理

本文概述了岸堤水库大坝岩溶坝基帷幕灌浆施工工艺,结合水库历年观测资料分析,介绍一种岩溶地基处理防渗的经济有效、简便易行的施工工艺。     

Model for negotiating the price and due date for a single order with multiple suppliers in a make-to-order environment

The nature of the business of a make-to-order company complicates its procurement activities. This paper is concerned with the development of a model for price and due-date negotiations between a manufacturer and its multiple suppliers in fulfilling a single order from a customer in a make-to-order environment. The developed negotiation model incorporates several established negotiation theories: aspiration level, limit level, natural forces acting on a negotiator and effective alternatives. Instead of presenting a single alternative for an offer in the current round of negotiation, we apply the Interactive Weighted-Tchebycheff method to generate a set of effective alternatives for presentation to the decision-maker in each round of the negotiation process. By giving a set of alternatives, we provide a degree of freedom to incorporate the decision-maker's preference in making offers and counter-offers during the negotiation process.     

Modified Ponorogo bentonite for the removal of ampicillin from wastewater

The adsorption of ampicillin onto natural and organo-bentonite was studied. Organo-bentonite was obtained by modifying the natural bentonite obtained from Ponorogo, Indonesia, using CTAB surfactant by microwave heating. The temperature dependent form of the Langmuir, Freundlich, Sips and Toth equations was employed to correlate equilibrium data. Based on the evaluation of the physical meaning of fitted isotherm parameters of each model, it is clear that Toth equation can represent the equilibrium data better than other models. The adsorption performance of natural and organo-bentonite for the removal of ampicillin from pharmaceutical company wastewater was also studied. In real wastewater, both adsorbents could not completely remove the ampicillin due to the sorption competition with other substances which also present in the wastewater.     

基于深度强化学习的主动配电网高恢复力决策方法

随着全球极端天气事件频发,电力系统在极端自然灾害下恢复力的研究日益受到关注。本文提出基于深度强化学习的高恢复力决策方法,将极端灾害下配电网运行状态和线路故障状态作为观测状态集合,自学习智能体Agent在当前环境观测状态下寻求可行的决策策略进行动作,定义自学习Agent的回报函数以进行动作评价;采用观测状态数据,开展基于竞争深度Q网络(dueling deep Q network,DDQN)的深度强化学习(deep reinforcement learning,DRL)训练,智能体Agent通过试错学习方式选择动作,试错经验在估值函数Q矩阵中存储,实现状态到主动配电网实时故障恢复策略的非线性映射;最后结合改进的IEEE 33节点算例,基于蒙特卡罗法仿真随机故障场景,对所提出方法生成的故障恢复随机优化决策进行分析。结果表明:通过主动配电网的分布式电源、联络开关和可中断负荷的协调优化控制,可以有效提升极端灾害下供电能力。     

Alkali–silica reactions (ASR): Literature review on parameters influencing laboratory performance testing

Utilisation of potentially alkali–silica reactive aggregates requires reliable performance tests to evaluate the alkali–silica reactivity of various aggregate combinations, including their alkali threshold dependence on binder type. Several such performance tests have been used worldwide for more than 15 years, but none of the methods have proven to be reliable for use with all aggregate types and all binders. One of the objectives of RILEM TC 219-ACS (2007–2012) is to develop and validate one or more of such performance tests.Several parameters may influence the results obtained in an accelerated performance test compared to the field behaviour. Based on a state of the art literature review, this paper discusses which parameters must be considered to be able to develop reliable ASR performance testing methods and provides some tentative recommendations. The internal humidity in the test specimens, the extent of alkali leaching and the storage temperature are of particular importance.