New permeation models for nanocomposite polymeric membranes filled with nonporous particles

In this article, permeation models for nanocomposite polymeric membranes (NCPMs) filled with nonporous particles are discussed and two new models for prediction of effective permeability of NCPMs are proposed. To derive these models, the presence of interfacial layer at the surface of the nanofiller particles as well as the impact of two important phenomena namely creating void volumes and increasing free volume at the interface layer are taken into account. The capability of the models for prediction of reliable results is checked against available experimental data on permeability of NCPMs and is also compared with other presented models for such membranes. The new proposed models show profound superiority over the well known models such as “Bruggeman model in limit” which offers fairly good prediction for NCPMs.     

Improving the efficiency of Monte Carlo power estimation [VLSI]

In this paper, we propose two efficient statistical sampling techniques for estimating the total power consumption of large hierarchical circuits. We first show that, due to the characteristic of the sampling efficiency in Monte Carlo simulation, granularity of samples is an important issue in achieving high overall efficiency. The proposed techniques perform sampling both temporally (across different clock cycles) and spatially (across different modules) so that a smaller sample granularity can be achieved while maintaining the normality of samples. The first proposed technique, which is referred to as the module-based approach, samples each module independently when forming a power sample. The second technique, which is referred to as the cluster-based approach, lumps the modules of a hierarchical circuit into a number of clusters on which sampling is then performed. Both techniques adapt stratification to further improve the efficiency. Experimental results show that these techniques provide a reduction of 23× in simulation run time compared to existing Monte-Carlo simulation techniques     

Two high-performance and low-power serial communication interfaces for on-chip interconnects

This paper presents two novel methods for on-chip serial communication in which the clocks of the transmitter and the receiver are generated with two separate ring oscillators. These oscillators are identical, although they can have a small frequency difference. In the first method, a strobe line that toggles exactly once with every frame of n-bit data is used to activate the oscillators. Local counters are used to count the number of bits in the data frame and to stop the local oscillators when the frame has been processed. In the second method, a single physical line is used to transmit both data and (in-band) control information, further reducing the power dissipation. The data transmission is controlled by the output of a starter flip-flop that indicates the empty/full state of an input buffer, whereas the data reception is controlled by the decoding of a ?1? start bit and a ?0? end bit, both of which are added to the n-bit data word to form a frame. Circuit simulation results demonstrate that both communication methods have high bandwidth and low power dissipation.     

The protection of mild steel by zinc-rich paint in flowing aerated 0.5 M NaCl solution—III. The effect of zinc content

The effect of the rate of flow of 0.5 M NaCl solution on the corrosion rate of mild steel and steel painted with zinc-rich paints containing from 50 to 93 wt% zinc dust was investigated. The results showed that the zinc dust content necessary to ensure protection of mild steel over the full flow range up to a Reynolds number of 16,000 was 80 wt% in the dried film.     

Facilitated transport by amine‐mediated poly(vinyl alcohol) membranes for CO2 removal from natural gas

The drive toward greater application of membrane has resulted in its rapid development in natural gas processing industry. In this work, amine‐mediated membranes were tailored for CO2 removal from CO2/CH4 stream. The effects of various parameters such as amine concentration, microporous support, feed pressure and composition were examined to study the permeation behavior of pure and mixed gases. Generally, CO2 transport through the DEA‐PVA membranes was higher than that of MEA‐PVA membranes for approximately 70%. The membrane containing 15 wt% DEA and 35 wt% MEA revealed higher permselectivity. CO2 permeance enhancement of amine‐PVA membranes in comparison with neat PVA membrane, confirmed that CO2‐amine reaction was the dominant transport mechanism. Additionally, with increasing feed pressure, CO2/CH4 permselectivity decreased due to carrier saturation. However, lower partial pressure of CO2 was in favor of reaction mechanism in pure and mixed gas tests. On the other hand, CH4 is not significantly affected by feed pressure confirming that solution‐diffusion is the governing transport mechanism. Additionally, PTFE support with higher wettability showed better performance (+8%) regardless of amine type, concentration and feed pressure. DEA‐PVA membrane has exhibited good stability during 2 weeks, unlike MEA‐impregnated membrane, which was probably due to carrier degradation over time. POLYM. ENG. SCI., 54:1268–1279, 2014. © 2013 Society of Plastics Engineers     

NBTI and hot-carrier effects in accumulation-mode Pi-gate pMOSFETs

Negative bias temperature instability (NBTI) and hot-carrier induced device degradation in accumulation-mode Pi-gate pMOSFETs have been studied for different fin widths ranging from 20 to 40 nm. The NBTI induced device degradation is more significant in narrow devices. This result can be explained by enhanced diffusion of hydrogen at the corners in multiple-gate devices. Due to larger impact ionization, hot-carrier induced device degradation is more significant in wider devices. Finally, hot-carrier induced device degradation rate is highest under stress conditions where V_GS = V_TH.     

PHYSICAL-CHEMICAL APPROACHES FOR THE ENVIRONMENTALLY SOUND DISPOSAL OF AN OIL SHALE RETORT WATER

ABSTRACT

The extraction of shale oil produces relatively large volumes of polluted process water. These waters contain large concentrations of organic and inorganic pollutants as well as environmentally significant amounts of trace materials. These substances either individually or in combination can be highly toxic to environmental systems. This paper addresses a suggested cleanup sequence designed to remove specific pollutants and to detoxify these waters. Hot gas stripping, followed by activated carbon adsorption and reverse osmosis removed over 93 percent of the total organic carbon load while also reducing the.toxicity of the resultant effluent as measured by a standard technique. Depending upon the ultimate use of these waters, the suggested treatment sequence or its individual components could be employed at a pilot or commercial scale retorting facility.     

Low power DCVSL circuits employing AC power supply

In view of changing the type of energy conversion in CMOS circuits, this paper investigates low power CMOS circuit design, which adopts a gradually changing power clock. First, we discuss the algebraic expressions and the corresponding properties of clocked power signals. Then the design procedure is summed up for converting complementary CMOS logic gates employing DC power to the power-clocked CMOS gates employing AC power. On this basis, the design of differential cas-code voltage switch logic (DCVSL) circuits employing AC power clocks is proposed. The PSPICE simulations using a sinusoidal power-clock demonstrate that the designed power-clocked DCVSL circuit has a correct logic function and low power characteristics. Finally, an interface circuit to convert clocked signals into the standard logic levels of a CMOS circuit is proposed, and its validity is verified by computer simulations.