Optimal size,hydraulic retention time and volatile solids loading rate of biogas unit using water hyacinth

With a view to evaluate the effects of hydraulic retention time and volatile solids loading rate on methane production using water hyacinth, experiments were conducted in a 160 dm³ capacity, well-mixed continuous digestion unit at ambient temperature. The optimal design of biogas plant using water hyacinth was elucidated, to provide a unit giving a maximum methane yield of 0.16 nm³ kg^?1 volatile solids added, which was 60% greater than the conventional plant using cowdung. The calculations of optimal design factors were based on reactor size, hydraulic retention time and volatile solids loading rate; considerations were made of capital cost, running costs and operational revenue.     

A 4.5-GHz 130-nm 32-KB L0 cache with a leakage-tolerant self reverse-bias bitline scheme

This paper describes a 32-KB two-read, one-write ported L0 cache for 4.5-GHz operation in 1.2-V 130-nm dual-V/sub TH/ CMOS technology. The local bitline uses a leakage-tolerant self reverse-bias (SRB) scheme with nMOS source-follower pullup access transistors, while preserving robust full-swing operation. Gate-source underdrive of -220 mV on the bitline read-select transistors is established without external bias voltages or gate-oxide overstress. Device-level measurements in the 130-nm technology show 72/spl times/ bitline active leakage reduction, enabling low-V/sub TH/ usage, 40% bitline keeper downsizing, and 16 bitcells/bitline. 11% faster read delay and 2/spl times/ higher dc noise robustness are achieved compared with high-performance dual-V/sub TH/ bitline scheme. Sustained performance and robustness benefits of the SRB technique against conventional dynamic bitline with scaling to 100- and 70-nm technology is also presented.     

ENVIRONMENTAL TOBACCO SMOKE REMOVAL CAPABILITY OF ACTIVATED CARBON

Removal of gaseous and vapor constituents of environmental tobacco smoke (ETS) by activated carbons in a packed bed arrangement was studied under dynamic conditions and was compared with that by silica gel and molecular sieve 13X. ETS is a mixture of sidestream smoke and exhaled mainstream smoke, and it consists of various organic and inorganic compounds, trace heavy metals, and particulate matters. Due to the complex nature of ETS-air mixture, its removal from indoors is a challenging task. For experimentation in a laboratory, the ETS was produced from a specially designed smoking apparatus that simulated the puffng of a cigarette by a person. Air containing ETS was passed through a bed containing about 25 grams of activated carbon at room temperature. The flow rate of air-ETS mixture through the bed was 4000 cm3/min. The relative humidity of the air was 50% and contained about 35 to 40 ppm of hydrocarbons as measured as methane-equivalent. The number of particles in the inlet air stream were in the range of 30,000 to 35,000 particles/cm3. About 60% of hydrocarbons present in ETS were removed at these operating conditions for a period of about 70 hours. Based on 15 adsorption and regeneration cycles, it was noted that the carbon bed did not loose its capacity for ETS significantly as indicated by the BET surface area and water adsorption data. At the beginning of an adsorption cycle, the carbon bed captured a significant number of particles. However, the bed rapidly lost its particle capture effciency as the experiment progressed. The number of particles in the outlet air stream was found to be the same as that of the inlet stream within five minutes.     

An actor-critic algorithm for constrained Markov decision processes

An actor-critic type reinforcement learning algorithm is proposed and analyzed for constrained controlled Markov decision processes. The analysis uses multiscale stochastic approximation theory and the envelope theorem' of mathematical economics.     

Mixed Micelles of Surface Active Ionic Liquid (SAIL)–Octylphenol Ethoxylate: A Novel Reaction Medium for Selective Oxidation of Toluene to Benzaldehyde

Ionic liquids have been found to be suitable alternatives to volatile organic solvents in chemical transformation. Through a proper choice of cations and anions, the properties of an ionic liquid can be tuned so that it resembles an amphiphile. Such specially designed molecules are known as surface-active ionic liquids (SAIL). Like conventional surfactants, SAIL also form aggregates in an aqueous medium. Studies show that the mixing of SAIL with conventional surfactants leads to synergistic micellization. However, very few reports are available on the application of such systems as reaction media. Present study focuses on the application of mixed micelles of 1-tetradecyl-3-methylimidazol-1-ium bromide, ([C₁₄mim]Br) with nonionic surfactant, Octylphenol ethoxylate with 10 moles of ethylene oxide (OPE-10). Enhanced solubilization and selective catalytic oxidation of toluene using hydrogen peroxide as an oxidant and tungstic acid as a catalyst have been studied in detail using this system.     

A stochastic Kaczmarz algorithm for network tomography

We develop a stochastic approximation version of the classical Kaczmarz algorithm that is incremental in nature and takes as input noisy real time data. Our analysis shows that with probability one it mimics the behavior of the original scheme: starting from the same initial point, our algorithm and the corresponding deterministic Kaczmarz algorithm converge to precisely the same point. The motivation for this work comes from network tomography where network parameters are to be estimated based upon end-to-end measurements. Numerical examples via Matlab based simulations demonstrate the efficacy of the algorithm.     

Recent advances in CKD and ESRD: A literature update

The past year has seen interesting publications in the fields of chronic kidney disease and end stage renal disease. This review highlights some of these important papers and places their findings in the context of clinical care.     

Efficient resource allocation for genetic algorithm based multi-objective optimization with 1,000 simulations

This study pertains to practical use of the GA for industrial applications where only a limited number of simulations can be afforded. Specifically, an attempt is made to find an efficient allocation of the total simulation budget (population size and number of generations) for constrained multi-objective optimization. A study is conducted to seek improvements while restricting the number of simulations to 1,000. Parallelization is exploited using concurrent simulations for each GA generation on a HP quad-core cluster, and resulted in a significant time savings. Furthermore, the efficient distribution of computational effort to achieve the greatest improvement in performance was explored. Two analytical examples as well as an automotive crashworthiness simulation of a finite element model with 58,000 elements were used as test examples. Various population sizes and numbers of generations were tried while limiting the total number of simulations to 1,000. The optimization performance was compared with Monte-Carlo and space filling sampling methods. It was observed that using the GA, many feasible and trade-off solutions could be found. It is shown that allowing a large number of generations is beneficial to get good trade-off solutions. For the vehicle design, significant improvements in the performance were observed. This example also suggests that, for problems with a small feasible region, the number of feasible solutions can be significantly increased in the first few generations involving about 200 simulations.     

Express Virtual Channels with Capacitively Driven Global Links

Networks on chip must deliver high bandwidth at low latencies while keeping within a tight power envelope. Using express virtual channels for flow control improves energy-delay throughput by letting packets bypass intermediate routers, but EVCs have key limitations. Nochi (NoC with hybrid interconnect) overcomes these limitations by transporting data payloads and control information on separate planes, optimized for bandwidth and latency respectively.