Preparation of Ni0.1Mg0.9O nanocrystalline powder and its catalytic performance in methane reforming with carbon dioxide

Ni_0.1Mg_0.9O nanocrystalline powders were prepared by surfactant assisted precipitation method and employed as catalyst in dry reforming. The powders were characterized by using XRD, BET, SEM, TGA/DSC and TPR techniques. The results showed that the surfactant to metal mole ratio affects the textural properties. Increasing in surfactant to metal mole ratio increased the specific surface area and decreased the crystallite and particle size. The Ni_0.1Mg_0.9O with the highest surface area (115.39 m² g^?1) was employed as catalyst in dry reforming. This catalyst showed a high catalytic activity and stability during 122 h time on stream without any decrease in methane conversion.     

An integrated thin-walled steel skeleton structure (two full scale tests)

The increased popularity of cold-formed thin-walled steel sections in housing construction has lead to an increased interest in the development of thin-walled frame buildings in accordance with seismic requirements. This paper investigates appropriate details for the main frame elements of a thin-walled building structure. Some of the proposed details are tested by two full scale one-storey frames under gravity and lateral cyclic loads. The results show that this type of structure offers a good potential for earthquake resistant construction, but more thorough studies are needed.     

Electrical and magnetic properties of Mg0.85Co0.15Fe2O4 ceramics with V2O5 additives

In this study, magnesium-cobalt ferrite (Mg_0.85Co_0.15Fe₂O₄) powder was synthesized using a solid-state synthesis method, followed by the liquid sintering using 0.50–3.00 wt% vanadium oxide (V₂O₅) at 1050 °C for 2 h. X-ray diffraction (XRD) studies confirmed the formation of spinel ferrite. Microstructure studies revealed that by increasing the amount of V₂O₅ from 0.50 to 3.00 wt%, the average grain size was reduced from 15.9?±?5.9 to 7.0?±?2.5 μm and the samples were highly densified. V₂O₅ promoted the sintering process and reduced the dielectric constant (ε′), loss tangent (tanδ), and increased electrical resistivity. A magnesium-cobalt ferrite sample with 25.4 dielectric constant, 0.078 loss tangent, and 9.0?×?10⁵ Ω.cm resistivity at 1 MHz was achieved using 3.00 wt% V₂O₅. Increasing V₂O₅ content caused increasing coercivity (Hc) from 89 to 129 Oe. Moreover, the maximum saturation magnetization (Ms) value of 26.8 emu/g was obtained for the sample containing 1.50 wt% V₂O₅. The small dielectric loss tangent of the samples at 1 MHz suggests applications of these ceramics in microwave devices.

     

Environmental vulnerability assessment of Choghakhor International Wetland during 1985 to 2018

As of natural constraints, and the specific climate of Iran, as well as the increasing importance of international water resources in the socio‐economic development of societies, studies on surface water resources, especially wetlands, merit special attention. Accordingly, the TM, ETM+ and OLI satellite images of 1985, 2000 and 2018 were used in the present study to detect changes in the Choghakhor international wetland. Classifying the images with a supervised method, and using maximum likelihood algorithms, the distinct land use/land cover classes of waterbody, aquatic plants, pasture and forest, agricultural lands, bare land and human built lands were ranked. Selected landscape metrics information on the spatial pattern of the Choghakhor wetland was quantitatively determined, using Fragstats software, and the spatial composition and vulnerability of the wetland were evaluated. The vulnerability assessment of wetland contamination was investigated using the WRASTIC index based on the catchment area scale. Time processing of the data obtained from the maps indicated a 26.63% decrease in the pasture and forest area, and a 12.1% increase in the area of human built lands and agriculture lands during the period from 1985 to 2018. Further, in spite of the waterbody area expanding during 1985 to 2000, it subsequently shrunk in size from 2000 to 2018, with the area of aquatic plants lands increasing during the same period. Analysis of landscape metrics generally indicated the natural wetland cover has been changing during this period along with increasing anthropogenic impacts. Degradation, rotation and replacement of natural land cover such as pastures and forests with human built areas can be considered undesirable development effects on the Choghakhor wetland. The results of the WRASTIC index calculation indicated a major impact of Choghakhor wetland components from water pollution. The results of the present study place an emphasis on more sustainable land use and prevention of land destruction in the Choghakhor wetland basin.     

A new multi objective optimization approach based on TLBO for location of automatic voltage regulators in distribution systems

This paper proposes a new multi-objective optimization algorithm based on modified teaching–learning-based optimization (MTLBO) algorithm in order to solve the optimal location of automatic voltage regulators (AVRs) in distribution systems at presence of distributed generators (DGs). The objective functions including energy generation costs, electrical energy losses and the voltage deviation are considered in this paper. In the proposed MTLBO algorithm, teacher and learner phases are modified. The considered objective functions are energy generation costs, electrical energy losses and the voltage deviations. The proposed algorithm uses an external repository to save founded Pareto optimal solutions during the search process. Since the objective functions are not the same, a fuzzy clustering method is used to control the size of the repository. The proposed technique allows the decision maker to select one of the Pareto optimal solutions (by compromising) for different applications. The performance of the suggested algorithm on a 70-bus distribution network in comparison with other evolutionary methods such as genetic algorithm (GA), particle swarm optimization (PSO) and TLBO is extraordinary.     

e-Supply network coordination: the design of intelligent agents for buyer-supplier dynamic negotiations

This paper concentrates on the problem of automated negotiations in e-supply network coordination (e-SNC). Supply network is considered as a collection of agent-mediated decisions and coordination mechanisms in a web-based environment. The proposed agent based coordination model is composed of two negotiator agents and a coordinator agent. The coordination mechanism begins with determining the feasible and most promising partners in the network based on the similarity of profiles. In response to autonomy levels and conflict objectives, the model allows agents to negotiate in a cooperative manner through an iterative process of generating offers for re-establishing global optimality. The dynamic negotiation model is then defined based on the protocol, rule of bargain, proposal generation, and dynamic strategy. To illustrate the model efficiency, a prototype system has been modeled and is compared to the normal tendering mechanism. The validation results confirm the model efficiency in providing coherent decision making in a dynamic environment.     

A multi-objective fuzzy adaptive PSO algorithm for location of automatic voltage regulators in radial distribution networks

This paper proposes a multi-objective optimal location of Automatic Voltage Regulators (AVRs) in distribution systems at the presence of Distributed Generators (DGs) by a Fuzzy Adaptive Particle Swarm Optimization (FAPSO) algorithm. The proposed algorithm utilizes an external repository to save founded Pareto optimal solutions during the search process. The proposed technique allows the decision maker to select one of the Pareto optimal solutions (by trade-off) for different applications. The performance of the suggested algorithm on a 70-bus distribution network in comparison with other evolutionary methods such as Genetic algorithm and PSO is extraordinary.