Electrochemical degradation of waters containing O-Toluidine on PbO2 and BDD anodes

Electrochemical oxidation of O-Toluidine (OT) was studied by galvanostatic electrolysis using lead dioxide (PbO₂) and boron-doped diamond (BDD) as anodes. The influence of operating parameters, such as current density, initial concentration of OT and temperature was investigated. Measurements of chemical oxygen demand were used to follow the oxidation. The experimental data indicated that on PbO₂ and BDD anodes, OT oxidation takes place by reaction with electrogenerated hydroxyl radicals and is favoured by low current density and high temperature. Furthermore, BDD anodes offer significant advantages over PbO₂ in terms of current efficiency and oxidation rate.     

Network-Level QoS Assurances Through Adaptive Allocation of CDMA Resources

In a Code Division Multiple Access (CDMA) network, multiple Mobile Hosts (MHs) can simultaneously transmit over the wireless channel by using different codes. To assure an acceptable Quality of Service (QoS) for all MHs' flows, the network usually tunes the transmit powers of all MHs to achieve a certain level of signal strength as compared to the noise and the interference (SINR) for each MH. The traditional assumption in power control schemes is that the SINR requirement is statically determined for each MH's flow. In contrast, in this paper, we propose a scheme that dynamically adapts the SINR requirements of MH's flow based on its QoS requirements and the conditions of the wireless channel between the MHs and the base station. As a result of this adaptation, we show that network-level QoS measures such as fraction of packets meeting their delay requirements and energy consumed per packet transmission are significantly better than in a scheme that statically fixes the SINR requirements. We show that the adaptation approach works well for the Matched Filter (MF) and the Minimum Mean Squared Error (MMSE) receivers. Our scheme uses a simple table-driven approach for optimally selecting the target SINR requirement for each MH at run time. The entries in the table are computed off-line using a dynamic programming algorithm with the objective of maximizing a profit function that balances the need for meeting the network-level QoS requirements and the cost of using a particular target SINR for a given transmission. Moncef Elaoud (M'97) received his B.Sc. (1988) his M.Sc. (1990) and his Ph.D. (2000) in electrical an computer engineering from the University of Wisconsin-Madison. He is currently a senior research Scientist at Telcordia Technologies' Applied Research organization. His main research interests are in the areas of quality of service, self-forming and self healing networks, auto-configuration, and mobility management in wireless and ad-hoc networks. Bechir Hamdaoui received the B.S. degrees in both electrical and mechanical engineering, and the M.S. degree in mechanical engineering from the National School of Engineering in Tunis (BAC+6+DEA, ENIT), Tunisia, in 1997 and 1998, respectively. He also received the M.S. degree in electrical and computer engineering from the University of Wiconsin, Madison, WI, in 2002, where he is currently working toward the Ph.D. degree. From 1998 to 1999, he worked as a quality control and planning engineer on power generation plant project under the supervision of FIAT Avio. His research focuses on various aspects in the area of computer networking including mobile networks, wireless communication systems, and ad hoc networks. Parameswaran Ramanathan received the B. Tech degree from the Indian Institute of Technology, Bombay, India, in 1984, and the M. S. E. and Ph. D. degrees from the University of Michigan, Ann Arbor, in 1986 and 1989, respectively. Since 1989, Dr. Ramanathan has been faculty member in the Department of Electrical & Computer Engineering, University of Wisconsin, Madison, where is presently a Full Professor. He leads research projects in the areas of sensor networks and next generation cellular technology. In 1997–98, he took a sabbatical leave to visit research groups at AT&T Laboratories and Telcordia Technologies. Dr. Ramanathan's research interests include wireless and wireline networking, real-time systems, fault-tolerant computing, and distributed systems. He is presently an Associate Editor for IEEE Transactions on Mobile Computing and Elsevier AdHoc Networks Journal. He served as an Associate Editor for IEEE Transactions on Parallel and Distributed Computing from 1996–1999. He has also served on program committees of conferences such as Mobicom, Mobihoc, International Conferences on Distributed Systems and Networks, Distributed Computing Systems, Fault-tolerant Computing Symposium, Real-time Systems Symposium, Conference on Local Computer Networks, and International Conference on Engineering Complex Computer Systems. He was the Finance and Registration Chair for the 1999 Fault-tolerant Computing Symposium. He was the program chairman of the Workshop on Architectures for Real-time Applications, 1994 and the program vice-chair for the International Workshop on Parallel and Distributed Real-time Systems, 1996. He is a member of Association of Computing Machinery and a senior member of IEEE.     

Automated Framework for Water Looped Network Equilibrium

In this paper, a novel algorithm is proposed for balancing water looped network in steady state through a fully automated general framework of hydraulic networks regardless of their topological complexity. The model is developed by combining the following two steps, firstly a set of independent loops are identified based on a graph theoretical analysis in a looped network. Further the second step is devoted to the equilibrium process by determining the flow rate distribution within the network ducts and the pressure in the delivery nodes. The above such equilibrium process gives rise to a system of non linear algebraic equations which are solved numerically using both Hardy Cross (HC) and Newton Raphson (NR) methods. In HC method, the flow correction term is modified and a generalized expression is given to consider various possibilities of independent loops selection. Some real networks topologies that were commonly used as benchmarks, for testing various independent loops selection algorithms, are taken as case studies to apply the general automatic framework for hydraulic network analysis. Such network analysis enhances proving the applicability as well as the effectiveness of the proposed approach. Also, during the equilibrium procedure, it is proved that NR method is capable of producing accurate results and it converges more rapidly comparing to the widely used HC method. Moreover, it is demonstrated that NR’s iterative process, contrary to HC’s one, converges to reliable results even with a choice of random initial flow rates which makes a NR algorithm quite simple to implement without affecting the accuracy of the results.     

Veratric acid treatment by anodic oxidation with BDD anode

BACKGROUND: Veratric acid (VA, 3,4‐dimethoxy‐benzoic acid) is representative of the polyphenolic type compounds present in olive mill wastewater (OMW). Given the bactericide factor, the inhibitor character and the anti bacteriological activity of this compound, traditional biological digestion cannot be applied and therefore new technologies, such as electrochemical oxidation using a boron‐doped diamond (BDD) anode have to be considered to avoid its accumulation in the environment. RESULTS: The electrochemical oxidation of aqueous solutions containing 1 mmol L^?1 VA has been investigated using a filter‐press reactor with a BDD anode during galvanostatic electrolysis. The influence of several operating parameters, such as applied current density, temperature, flow‐rate and supporting electrolyte concentration and type has been investigated. The experimental results showed that under the experimental conditions used the oxidation of VA was under mass‐transfer control and VA was completely degraded by the reaction with hydroxyl radicals electrogenerated at the BDD surface. The chemical oxygen demand (COD) decay kinetic followed a pseudo‐first‐order reaction and the apparent rate constant increased with flow rate and temperature. Under optimal experimental conditions of flow‐rate (300 L h^?1), temperature (35 °C) and current density (10 mA cm^?2), 99.5% of COD was removed during 2 h electrolysis, with 16.4 kWh m^?3 energy consumption. CONCLUSIONS: This study suggests that anodic oxidation with a BDD electrode is an excellent method for the treatment of effluents contaminated with VA and related polyphenols. Copyright © 2011 Society of Chemical Industry     

An efficient Resource Management to optimize the placement of hardware task on FPGA in the RVC framework

Dynamic partial reconfiguration (DPR) functionality allows implementing multi-tasks applications by exchanging tasks in a design at run-time. It is a promising solution to enhance system performances. But, the effective use of DPR is often hampered by the complexity added to the system design process. In this paper, we investigate the implementation of a multi-tasks applications using the DPR in the RVC framework. We present a resource management method which includes three steps: partitioning the application in HW/SW tasks, divided the FPGA in static and dynamic regions and placement the tasks on FPGA. The proposed method is based on using linear programming strategy to find the optimal placement of hardware tasks. We take into account the heterogeneity aspect of the device. The goal is to minimize the resource utilization and fragmentation. We use RVC technology which is based on a specific language for writing dataflow models called RVC-CAL. This language describes the application as set of blocks called actors connected through a network. To test the efficiency of our approach, we exploit the decoder MPEG-4 SP described in RVC-CAL. We measure the quality of placement in terms of tasks rejection, execution time and resource wastage. Application of different data combinations and a comparison with the state-of-the art method show the high performance of the proposed approach.     

Soil Compaction Due to Tractor Traffic

Horticulture in Mediterranean areas demand frequent tractor traffic for tillage and for the application of herbicides and pesticides, resulting in soil compaction. Soil compaction is one of the most important factors responsible for soil physical degradation. This compaction by agricultural machines can have adverse effects on crop production and the environment. Different methods have been proposed to estimate soil compaction intensity as a function of vehicle and soil properties such as the soil’s water content, bulk density, and resistance to penetration. In this work the authors studied subsoil compaction based on wheel load in the terrain tillage and tillage in a region that was not previously cultivated. A small tractor (engine power 25 kW, type E-TCVS, and weight 1200 kg) was used in the tests. Results showed that the first passage of wheel traffic of the tractor, increases the soil resistance more than the second passage; for example, there is a big difference between the penetration resistance at initial state (2.22 daN/cm²) and after the first passage (5.72 daN/cm²), while the variation between the penetration resistance after first passage (5.72 daN/cm²) and after second passage (6.22 daN/cm²) is relatively small. This shows that the first passage has the most significant impact on soil compaction.     

Electrochemical degradation of 4-chloroguaiacol for wastewater treatment using PbO2 anodes

Electrochemical oxidation of 4-chloroguaiacol (4-CG) at Nb/PbO(2) anodes was studied under different experimental conditions such as initial concentration of substrate, electrolysis time, temperature and pH. We measured the concentrations of 4-chlorocatechol (4-CC), 2-methoxyhydroquinone (2-MHQ), maleic acid (MA) and carbon dioxide as the main products. Black solid particles consisting mainly of polymers were formed during electrolysis. A mechanism of electrochemical oxidation of 4-CG was investigated. The oxidation of 4-CG can generally be described by simple pseudo first-order kinetics. The degradation of 4-CG was favoured at high temperature and lower initial concentration of 4-CG and low solution pH. However, the increase of temperature has not a significant effect on the mineralization of carboxylic acids. Moreover, these products required long electrolysis time.     

Genetic algorithms to solve the cover printing problem

Inspired by successful application of evolutionary algorithms to solving difficult optimization problems, we explore in this paper, the applicability of genetic algorithms (GAs) to the cover printing problem, which consists in the grouping of book covers on offset plates in order to minimize the total production cost. We combine GAs with a linear programming solver and we propose some innovative features such as the “unfixed two-point crossover operator” and the “binary stochastic sampling with replacement” for selection. Two approaches are proposed: an adapted genetic algorithm and a multiobjective genetic algorithm using the Pareto fitness genetic algorithm. The resulting solutions are compared. Some computational experiments have also been done to analyze the effects of different genetic operators on both algorithms.     

A novel integer programming formulation with logic cuts for the U-shaped assembly line balancing problem

U-shaped assembly lines are regarded as an efficient configuration in Just-In-Time manufacturing. Balancing the workload in these lines is an unsolved problem that attracted significant research within the past two decades. We present a novel integer programming formulation for U-shaped line balancing problems, where cycle time, the interval between two consecutive outputs, is known and the aim is to minimize the number of workstations. To enhance the efficiency of the LP relaxation of the new formulation, we present three types of logic cuts (assignable-station-cuts, task-assignment-cuts and knapsack-cuts) that exploit the inherent logic of the problem structure. The new formulation and logic cuts are tested on an extensive set of benchmark problems to provide a comparative analysis with the existing models in the literature. The results show that our novel formulation augmented by assignable-station-cuts is significantly better than the previous formulations.     

A delay-based admission control mechanism for multimedia support in IEEE 802.11e wireless LANs

Multimedia over IEEE 802.11 wireless local area networks (WLANs) has recently been the focus of many researchers due to its rapidly increasing popularity. Unlike their best-effort counterparts, multimedia applications have quality of service (QoS) needs typically expressed in terms of the maximum allowed delay and/or the minimum required throughput. Therefore, prior to accepting a multimedia application, the network must assure the satisfaction of its QoS requirements. In this paper, we develop a mechanism that can be used to control the admissibility of multimedia applications into WLANs. To develop the proposed mechanism, we first derive an analytical approximation of the delay experienced by packets when travelled through these networks. The analytical approximation of the delay is then used to propose an admission control mechanism for the enhanced distributed channel access (EDCA) method used by the hybrid coordination function (HCF) of IEEE 802.11e. The proposed delay-based admission control mechanism is validated via simulations of voice traffic.