Variation resilient low-power memristor-based synchronous flip-flops: design and analysis

Microsystem Technologies - Flip-flops are the basic digital components for all types of complex digital electronics systems and sequential logic circuits. In this paper, new nonvolatile, low power,...     

Mixed convective heat transfer enhancement in a ventilated cavity by flow modulation via rotating plate

The present study numerically explores the mixed convection phenomena in a differentially heated ventilated square cavity with active flow modulation via a rotating plate. Forced convection flow in the cavity is attained by maintaining external fluid flow through an opening at the bottom of the left cavity wall while leaving it through another opening at the right cavity wall. A counter-clockwise rotating plate at the center of the cavity acts as an active flow modulator. Moving mesh approach is used for the rotation of the plate and the numerical solution is achieved using arbitrary Lagrangian-Eulerian finite element formulation with a quadrilateral discretization scheme. Transient parametric simulations have been performed for various frequency of the rotating plate for a fixed Reynolds number (Re) of 100 based on maximum inlet flow velocity while the Richardson number (Ri) is maintained at unity. Heat transfer performance has been evaluated in terms of spatially averaged Nusselt number and time-averaged Nusselt number along the heated wall. Power spectrum analysis in the frequency domain obtained from the fast Fourier transform analysis indicates that thermal frequency and plate frequency start to deviate from each other at higher values of velocity ratio (>4).     

A low power,temperature compensated,robust design of CS amplifier in nanoscale regime

Microsystem Technologies - A low power, temperature compensated, robust design of CS amplifier is proposed in this paper. A new voltage reference is introduced to enhance reliability of the design...     

Patterning of worm-like soft polydimethylsiloxane structures using a TiO2 nanotubular array

Patterned polydimethylsiloxane (PDMS) is an important structure for soft lithography. Various materials have been deployed as mold for patterning PDMS. Anodized nanotubular array has been sought after as cost-effective alternative for textured silicon. An array of TiO₂ nanotubes with characteristic diameter ≈140 nm and the length of ≈1.5 microns, created by anodic oxidation of a titanium substrate, was used here as a template for soft PDMS molding. The optimal molding process was developed by a combination of silanization, use of solvent, application of a vacuum, and hydraulic pressing. The silanization was confirmed by Fourier transform infrared spectroscopy and contact angle measurements while the PDMS structure was examined by scanning electron microscope and energy dispersive X-ray spectroscopy. Hydraulic pressing significantly improved the infiltration of PDMS into the pores of nanotubular array resulting in formation of PDMS nanobumps after separation of the polymer from the template. Complete infiltration of PDMS precursor into the cavity of nanotubes was observed on the hydraulic-pressed sample without toluene impurities. The hydraulic-pressed samples exhibited higher adhesion strength than nonpressed ones. The adhesive strength was measured by a simple experimental arrangement, in which the PDMS layer was stuck on a vertical glass surface followed by pulling it downwards.     

Dry sliding wear in case-hardened niobium microalloyed steels

Low-carbon steel samples containing a small addition of niobium singly or in combination with nitrogen have been carburized in a natural Titas gas atmosphere at 950 °C and 15 psi gas pressure for different time periods. At the end of the predetermined time period, the specimens were pre-cooled to 860 °C in the furnace and quenched in 10% brine. One set of the quenched specimens was tempered at a low temperature of 160 °C and the other set was sub-zero treated at −195 °C in liquid nitrogen, followed by tempering at the same tempering temperature. Surface hardness was measured by Rockwell hardness testing machine and optical microscopy was performed on etched samples. Using a pin-on-disc type apparatus, wear test was carried out under dry sliding condition to assess the beneficial effect of niobium and niobium with nitrogen on the wear properties of the carburized and hardened low-carbon steels in relation to the resulted surface hardness and microstructures.

It has been found that niobium with or without nitrogen improves the wear resistance under both the heat treatment conditions. Niobium with nitrogen is more effective than niobium in improving the wear resistance. Whatever was the heat treatment condition, the wear rate of the specimens increases for all the steels as the carburizing time increases. It has also been found that samples with sub-zero treatment always have higher wear resistance than that of samples without sub-zero treatment. Niobium singly or in combination with nitrogen has been found as a modifier of the wear mechanism.     

The effects of pressure and temperature on the catalytic oxidation of hydrogen sulfide in natural gas and regeneration of the catalyst to recover the sulfur produced

The influence of pressure up to 5600 kPa and temperature up to 175 °C on the oxidation of low concentrations of H₂S in natural gas was studied in a fixed bed reactor over an activated carbon catalyst. Operation of this system at 5600 kPa provides higher catalyst activity (virtually 100% H₂S conversion) over a longer period of time and with lower selectivity to SO₂ than when operated at atmospheric pressure. The desorption of sulfur from a loaded catalyst occurs first from the macropores (> 100 nm) of the catalyst which contain a substantial portion of the sulfur load and then from the micropores (< 100 nm). This study also indicated that the sulfur recovery process is both rapid and effective at 327°C.     

An efficient evolutionary algorithm to optimize the Choquet integral

Information fusion is an essential part of nearly all systems whose goal is to derive decisions from multiple sources. Often, a fusion solution has parameters and the goal is to learn them from data. Herein, we propose efficient evolutionary algorithm (EA) operators to facilitate learning the Choquet integral (ChI). Whereas many EAs provide a way to solve complex, unconstrained optimization tasks, most tend to perform relatively poor in light of constraints. Recently, a few EA-based approaches to optimizing the ChI have appeared. Namely, these methods focus on fixing the values of variables so conditions are met or feasible candidate pairs are identified for steps such as crossover. Herein, we introduce a new set of transparent operators that are guaranteed to naturally preserve constraints, thus eliminating the need to resort to costly evaluations and fixing of constraint violations. In particular, our method scales well to large numbers of inequality constraints, something that prior work does not. The proposed algorithm, coined efficient ChI genetic algorithm (ECGA), is evaluated on several synthetic data sets and it is compared with state-of-the-art algorithms. In particular, we show benefits in terms of solutions found and the time it takes to find such an answer.     

Current-mode circuit-level technique to design variation-aware nanoscale summing circuit for ultra-low power applications

Prodigious demand for fast performance-ultra low power electronic devices has insinuated the discovery of circuit style that promises reduced propagation delay (t _p ), as well as low power dissipation (PWR). MOS current mode logic (MCML) style has emerged as a promising logic style that offers high speed of operation at the expense of acceptable power dissipation. This paper proposes a MCML full adder which employs a load controller circuit. It compares MCML full adder with hybrid-CMOS full adder in terms of various design metrics in superthreshold as well as subthreshold regions. MCML topology with load controller offers a high speed of operation and low power dissipation in superthreshold region. Same circuit arrangement, when operated in subthreshold region also delivers higher operating speed with ultralow power dissipation compared to its hybrid-CMOS counterpart. Power dissipation analysis established MCML based full adder more robust compared to its hybrid-CMOS counterpart. In particular, MCML full adder design achieves 3.77× (2.38×) improvement in propagation delay, 10.43× (3.45×) improvement in average power dissipation, 39.43× (8.21×) lower power-delay product (PDP) and 149.07× (19.55×) improvement in energy-delay product (EDP) in superthreshold (subthreshold) regions of operation at 16-nm technology node. The above results are also validated using TSMC’s industry standard 0.18-μm technology model parameters and a similar trend is observed in the design metrics of the MCML and hybrid-CMOS full adder circuits. In addition, noise performance of the above mentioned circuits is also carried out. It is observed that the noise induced by the hybrid-CMOS full adder is about 14× to that of the MCML full adder.

     

Immunoconcentration of Shiga toxin-producing Escherichia coli O157 from animal faeces and raw meats by using Dynabeads anti-E. coli O157 and the VIDAS system

To identify the reservoirs and routes of transmission of Shiga toxin-producing Escherichia coli (STEC) O157, sensitive detection and isolation methods are necessary. The sensitivity of traditional culture methods can be improved significantly by the inclusion of an immunoconcentration step, resulting in less false-negatives. In this report, we evaluated the results of two commercially available test systems: Dynabeads anti-E. coli O157 and the Vitek Immunodiagnostic Assay System (VIDAS) Immuno-Concentration E. coli O157 (ICE) kit. Additionally, we compared two selective isolation media for STEC O157. Statistical analysis of the results obtained for animal faecal samples (n=637) examined by both immunoconcentration methods showed that by the manual Dynabeads anti-E. coli O157 procedure systematically more samples were identified as positive than by the VIDAS ICE. In case of meat samples (n=360), no difference between the results of the two methods was found. In addition to being accurate, the Dynabeads anti-E. coli O157 method is a less expensive method than the VIDAS ICE. But, the Dynabeads method is laborious and there is a risk of cross-contamination. The VIDAS ICE procedure on the other hand is fully automated with a standardised performance; fast and safe for the user. Irrespective of the type of sample (faeces or meat) and the immunoconcentration technique applied (Dynabeads anti-E. coli O157 or VIDAS ICE) more samples were found positive after plating onto CHROMagar O157 with cefixime (0.025 mg l(-1)) and tellurite (1.25 mg l(-1)) than after plating onto sorbitol-MacConkey agar with cefixime (0.05 mg l(-1)) and tellurite (2.5 mg l(-1)). However, only in case of meat samples examined by the VIDAS ICE the difference between the isolation media was not statistically significant.     

Physiochemical Properties of <Emphasis Type="Italic">Jatropha curcas</Emphasis> Seed Oil from Different Origins and Candidate Plus Plants (CPPs)

The physicochemical properties of Jatropha seed oil from 9 geographical origins and 24 candidate plus plants (CPPs) were evaluated. The yield of seed oil obtained by Soxhlet extraction using n-hexane as solvent varied from 40.0% (Malaysia) to 48.4% (Vietnam) among seeds from different origins and 32.1% (CPP-17) to 48.8% (CPP-01) (w/w) among CPPs. Density, specific gravity, and refractive index of oil showed very little differences among all the seed sources. Oil from Borneo had the highest free fatty acid (FFA) content (2.3%) and a South African sample had the lowest FFA (0.4%), as oleic acids. Seed oil of CPP-13 had the highest FFA content (1.2%) and seed oil of CPP-17 the lowest (0.3%). Most of the CPPs in this study had an FFA content of less than 1%. Jatropha seed oil of Philippine origin had the highest iodine value (187.3 mg/g oil) and seed oil from Borneo the lowest (83.5 mg/g oil). The lowest saponification values were obtained from seed oil of Philippine origin (189.5 mg KOH/g) and CPP-22 (183.3 mg KOH/g oil) from Malaysia. The maximum higher heating value (40.3 MJ/kg) was obtained from seed oil from Borneo. The cetane numbers range from 25.4 (Indonesia) to 56.0 (Borneo) among the oils of base material and 46.4 (CPP-15) to 53.7 (CPP-06) among CPPs. This study gives basic information of relevance for biodiesel production using Jatropha seeds from various origins.