True high-order VCO-based ADC

A novel approach to use a voltage-controlled oscillator (VCO) as the first integrator of a high-order continuous-time delta-sigma modulator (CT-DSM) is presented. In the proposed architecture, the VCO is combined with a digital up-down counter to implement the first integrator of the CT-DSM. Thus, the first integrator is digital-friendly and hence can maximally benefit from technological scaling

Effect of pulsed power on particle matter in diesel engine exhaust using a DBD plasma reactor

Nonthermal plasma (NTP) treatment of exhaust gas is a promising technology for both nitrogen oxides (NOX) and particulate matter (PM) reduction by introducing plasma into the exhaust gases. This paper considers the effect of NTP on PM mass reduction, PM size distribution, and PM removal efficiency. The experiments are performed on real exhaust gases from a diesel engine. The NTP is generated by applying high-voltage pulses using a pulsed power supply across a dielectric barrier discharge (DBD) reactor. The effects of the applied high-voltage pulses up to 19.44 kVpp with repetition rate of 10 kHz are investigated. In this paper, it is shown that the PM removal and PM size distribution need to be considered both together, as it is possible to achieve high PM removal efficiency with undesirable increase in the number of small particles. Regarding these two important factors, in this paper, 17 kVpp voltage level is determined to be an optimum point for the given configuration. Moreover, particles deposition on the surface of the DBD reactor is found to be a significant phenomenon, which should be considered in all plasma PM removal tests

Physicochemical characterization of sodium surfactin for oil and gas industry application

Introduction – Industry operators are becoming more critical of synthetic surfactants for various oil and gas operations. Principal among these concerns is the environmental degradation. As a result, there is increasing interest in the use of biosurfactant, including surfactin, in oil and gas operations. Therefore the need to improve its characteristics, hence performance becomes evident. Characteristics of cultures of surfactin (isolates) were reported. These characteristics could potentially change after synthesis and drying, hence the need for this study. Methodology - The methodology involved characterizing surfactin in aqueous media, and sodium chloride (NaCl) salt solution of 0.1–1.5M concentrations. Properties that influence active site for adsorption (functional group), dispersion (density, foaming), amount of dissolved minerals (pH and conductivity) among others, were analyzed at various surfactin dosages of 0.025 – 1.0%. Results − Results indicated foaming and solubility were excellent in aqueous solution, but significantly affected above 0.5M NaCl concentration. Aqueous surfactin had maximum density of 985.2kg/m3, however increases with increasing NaCl concentration. With pH of 7.1 at 1.0% dosage, aqueous surfactin will pose no corrosion problem to pipelines. Additionally, both surfactin dosage and change in salt concentration exhibited linear relationship effect with pH and conductivity. Infrared analysis confirms cyclic nature of sodium surfactin with lipopeptide chain linked to an aliphatic, hydrocarbon chain. Conclusion − These makes it suitable for use as dispersion agent, viscosity reduction for heavy crude transport, additive for drilling mud preparation, and potential candidate for surface activities, a desirable requirement for oil and gas applications. Keywords: Sodium surfactin, Bacillus subtilis, biosurfactant, physicochemical characteristic

Effect of impermeable barrier orientation on bottom water cresting

The use of either a permeable or semi-permeable barriers has been proven to be effective in minimizing cresting effects in oil reservoirs characterized by strong bottom aquifer, with the latter known to be more effective. Most research has been focused on coning control in vertical wells with little research existing for cresting control in horizontal wells, especially in use of barriers. Therefore, this paper sets out to numerically investigate the effect of an impermeable barrier orientation in an oil reservoir characterized by a strong bottom aquifer. The orientations considered in this study were horizontal and inclined (step-like) in terms of placement in the oil reservoir, modeled with similar thickness and width. From the results, it was observed that a horizontally-placed impermeable barrier is more effective than inclined impermeable barriers in bottom water cresting scenarios. A horizontal impermeable barrier closer to the perforation of the horizontal well, 0.08x in thickness to the reservoir height and 0.45x to reservoir width was the most effective, although the effect of impermeable barrier width was found to be inconsistent with the performance of impermeable barriers. The study shows that the closer the entire top surface of the inclined impermeable barrier, the more effective the inclined impermeable barrier in minimizing bottom water cresting effect. The value of Reynolds number was found to be dependent on the orientation, thickness, position, and width of an impermeable barrier

Screening of drought-tolerant and sensitive genotypes in soybean (Glycine max L.) using different multivariate methods

The soybean is a crop of global importance, which cultivate in worldwide. However, the soybean is more susceptible to water shortages during germination and reproductive growth stages. Stress is an in ordinary physical process of environmental factors effects and it has traumatic ability, which causes unusual metabolism in plants, and it is possible; reduce plant product or causes plant death. Drought indices provide a measure of drought based on loss of yield under drought conditions in comparison to normal and have been used for screening drought tolerant genotypes. We cultivated Ten genotypes of soybean in the research field of seed and plant improvement institute in Karaj- Iran in 2015 June. The experimental design was a randomized block with three replicate in two separate field experiments for normal and stress conditions. We irrigated the normal experiment in 85% field capacity and got 50% filed capacity for stress conditions. Seventeen drought tolerance indices were calculated. Four methods were used to identify more resistant and more susceptible genotypes. After genotypes selection, we carried out experiment in green house with two selected genotypes. Results showed using the indices such as MP, GMP and STI, alone, cannot select a stable genotype and we have to use a combine of all indices or use indices that showed reduction and average yield, together. In second year, results showed that we had a true selection.Int. J. Agril. Res. Innov. & Tech. 7 (2): 7-17, December, 201