Graphene oxide coated wad as a new sorbent in fixed bed column for the removal of crystal violet from contaminated water

An efficient method was developed to fabricate graphene oxide coated cotton wad (GO/W) using self-assembly technique. GO/W could be used as an adsorbent material in remediation of environmental pollutants in a continuous packed bed column. The efficiency of GO/W fixed bed column in the removal of crystal violet (CV) from an aquatic environment was studied. The experimental breakthrough data were modeled using Thomas, Adams-Bohart, and Yoon-Nelson models, and the column parameters for all these models were calculated. Increasing the effluent discharge rate and initial adsorbate concentration make the breakthrough and saturation points to be obtained faster and hence lower the adsorption capacity of column.     

Multiobjective optimization of polymerization reaction of vinyl acetate by genetic algorithm technique with a new replacement criterion

A multiobjective optimization procedure based on genetic algorithm has been developed to determine optimum operational conditions of polymerization reaction. In this article by using a new selection criterion to choose the next generation members with better quality, optimization efficiency is improved and the number of generations to obtain Pareto optimal set reduced. In this proposed method a novel replacement criterion based on ranking level information and proximity of solutions to the Pareto optimal front is used to choose the next generation members. The polymerization of vinyl acetate has been chosen as an example. Two objective functions, which used in this study, are maximization of the weight average molecular weight up to the desired value and minimization of the residual initiator concentration. A Pareto optimal set of objective functions has been obtained by application of a Pareto set filter operator. Furthermore, the influence of genetic algorithm parameters on the efficiency and convergence of genetic algorithm is studied by changing cross over and mutation probabilities. Because of the flexibility and generality of genetic algorithm, this optimization method is a useful technique with lots of potentials in determination of optimum value of operation parameters. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

Energy harvesting,cooperative spectrum sensing,and data transmission improvement in energy‐efficient multichannel cognitive sensor networks

In this paper, we investigate the energy harvesting capability in a multichannel wireless cognitive sensor networks for energy‐efficient cooperative spectrum sensing and data transmission. Spectrum sensors can cooperatively scan the spectrum for available channels, whereas data sensors transmit data to the fusion center (FC) over those channels. We select the sensing, data transmission, and harvesting sensors by setting the sensing time, data transmission time, and also harvesting time to maximize the network data transmission rate and improve the total energy consumption in the multichannel network under global probability of false alarm and global probability of detection constraints. We formulate our optimization problem and employ the convex optimization method to obtain the optimal times and nodes for spectrum sensing, data transmission, and harvesting energy in each subchannel for multiband cognitive sensor networks. Simulation results show that in our proposed algorithm, the network data transmission rate is improved while more energy is saved compared with the baseline methods with equal sensing time in all subchannels.     

Morphological characterization of Hypnaceae (Bryopsida,Hypnales): Investigating four genera from Western Himalayas by using LM and SEM techniques

The Hypnaceae is one of the largest and diversified family among the pleurocarpous mosses which consists of nearly 60 genera and 1,000 species around the world. In Pakistan, it is represented by 15 species and 8 genera. The current research article provides the detail morphological investigation of four different species (genera) of the family Hypnaceae that is, Gollania clarescens, Hypnum revolutum, Homomallium andoi, and Taxiphyllum taxirameum in the Western Himalayas, Pakistan. The research article reports the first SEM study of the leaf surfaces of the studied taxa, along with comprehensive morphological characters of the four species. The main objective of the research project is to present the comparative light and scanning electron microscopic study to discuss the morphology in detail because previously the family is just reported in different bryophyte checklists of the Western Himalayas. Based on results, morphological characters, micromorphological observations, qualitative and quantitative attributes, taxonomic keys for the studied taxa, distribution, and habitat are described. Stereoscope was used to analyze different qualitative characters, and light microscope was used to observe and measure the laminal and alar cells of the leaf. The SEM study reveals many important surface features like cell shape and cell wall. The laminal cells were mostly linear and elongated with thin cell walls. The specimens used for the SEM were air dried, so the laminal cells were somewhat constricted and concaved. The current study project will help to make the contribution in the taxonomy and morphology of this family.     

Rapid synthesis of flower-like ZnO nanostructures

Flower-like ZnO nanostructures were prepared via microwave assisted heating in the presence and absence of ionic liquid (IL). X-ray diffraction analysis (XRD), Scanning electron microscopy SEM and room temperature photoluminescence (PL) spectra have been employed for characterization of the products. The SEM image illustrates the surface of flower-like ZnO prepared in the presence of IL is not smooth and consists of nanoparticles with grain size of about 48 nm. PL spectra of flower-like ZnO in absence and presence IL reveal similar photoluminescence features: a strong UV, weak blue and green-yellow emissions peak at a bout 393 nm, 448 nm and 583 nm respectively. The strong UV photoluminescence and the weak green emission indicate the good crystallization quality of the flower-like nanostructure. The results show that imidazolium-based IL can be used as template for achieving very high level control over the size and shape of nanostructures. The approach developed in this work can potentially be used as a viable method for making various other uniform nanostructures in the presence of IL. This method is simple, fast, low-cost and suitable for large-scale production of ZnO nanostructures.     

A stochastic games framework for verification and control of discrete time stochastic hybrid systems

We describe a framework for analyzing probabilistic reachability and safety problems for discrete time stochastic hybrid systems within a dynamic games setting. In particular, we consider finite horizon zero-sum stochastic games in which a control has the objective of reaching a target set while avoiding an unsafe set in the hybrid state space, and a rational adversary has the opposing objective. We derive an algorithm for computing the maximal probability of achieving the control objective, subject to the worst-case adversary behavior. From this algorithm, sufficient conditions of optimality are also derived for the synthesis of optimal control policies and worst-case disturbance strategies. These results are then specialized to the safety problem, in which the control objective is to remain within a safe set. We illustrate our modeling framework and computational approach using both a tutorial example with jump Markov dynamics and a practical application in the domain of air traffic management.     

Numerical solution of GRLW equation using Sinc-collocation method

In this paper, we present a meshfree technique for the numerical solution of the generalized regularized long wave (GRLW) equation. This approach is based on a global collocation method using Sinc basis functions. The propagation of single solitons and the interaction of two solitary waves are used to validate the method which is found to be accurate and efficient. The three invariants of the motion are evaluated to determine the conservation properties of the method.     

Fault-tolerant computation of distributed regular path queries

Regular path queries are the building blocks of almost any mechanism for querying semistructured data. Despite the fact that the main applications of such data are distributed, there are only few works dealing with distributed evaluation of regular path queries. In this paper we present a message-efficient and truly distributed algorithm for computing the answer to regular path queries in a multi-source semistructured database setting. Our algorithm is general as it works for the larger class of weighted regular path queries on weighted semistructured databases.