The operation characteristics and electrochemical reactions of a specific circulation-enhanced electrokinetics

For electrokinetics remediation, the acid produced at the anode due to the water electrolysis will cause the soil acidification and destroy the soil constituents. Especially, the contaminated soils in Taiwan are usually agricultural lands; it is necessary to improve the performance of EK system to maintain the soils nature after remediation. In this study, a circulation-enhanced EK system (CEEK) was designed to neutralize the pH of the working solution and soils. Experiments were conducted by the control of different electrolyte species (sodium and potassium salts) and concentrations (10(-3) to 5x10(-2)M), respectively. Experimental results show the operational characteristics include: the CEEK system can effectively stabilize the pH of processing solution at neutral range and the current can be maintained at stable status with carbonate salts; the pH buffering range of working solution in the CEEK system depends on the electrolyte species and their concentration significantly; the water content remains roughly as their original nature in the CEEK system. For consideration of electrochemical reactions, the water electrolysis is the predominating electrochemical reaction in the CEEK system, which not only influences the pH but also the conductivity of the working solution. In the application of practical engineering, there exist linear relationships between the pH, conductivity, current and the electrolyte concentration, respectively, which can serve as a means to assist engineers to select operational parameters of CEEK.     

Solar absorption cooling effect on operational parameters on power saving

The paper deals with engineering estimates of the electrical power consumption of equivalent cooling capacity vapour-compression and vapour-absorption (solar) cooling systems. The effects of operational parameters on absorption chiller performance have been studied to define the breakeven point at which the two systems will consume equivalent amounts of electrical energy per unit of cooling output.     

The effects of the operational parameters of the reactor on ECR plasma characteristics

A two-dimensional axis-symmetric model is adopted to investigate the characteristics of an electron cyclotron resonance plasma. The mass conservation equations of electrons, positive ions, and metastable atoms, the electron energy equation, and the Poisson equation are used in this multi-component system. The magnetic field generated by coils was computed numerically. The distributions of temperature and density of electrons are calculated by the finite difference method. The results of the numerical simulation for argon plasma shows that, in the phase of a long-time discharge, the electron temperature in the resonance chamber is higher than that in the reactor chamber, and electron density in the resonance chamber is lower than that in the reactor chamber. In addition, the effects of pressure on the two distributions are illustrated and discussed.     

Electrochemical-assisted photodegradation of dye on TiO2 thin films: investigation on the effect of operational parameters

Electrochemical-assisted photodegradation of methyl orange has been investigated using TiO2 thin films. The films were prepared by sol-gel dip-coating method. Several operational parameters to achieve optimum efficiency of this electrochemical-assisted photodegradation system have been tested. Photoelectrochemical degradation was studied using different light sources and light intensity. The light sources chosen ranged from ultraviolet to visible light. The effect of agitation of the solution at different speeds has also been studied. Slight improvement of photodegradation rate was observed by applying higher agitation speed. Investigation on the electrode after repeated usages show the electrode can be reused up to 20 times with percentage of deficiency less than 15%. The study on the effect of solution temperature indicated that the activation energy of the methyl orange degradation is 18.63 kJ mol(-1).     

Decolorization of basic dye solutions by electrocoagulation: an investigation of the effect of operational parameters

Electrocoagulation (EC) is one of the most effective techniques to remove color and organic pollutants from wastewater, which reduces the sludge generation. In this paper, electrocoagulation has been used for the removal of color from solutions containing C. I. Basic Red 46 (BR46) and C. I. Basic Blue 3 (BB3). These dyes are used in the wool and blanket factories for fiber dyeing. The effect of operational parameters such as current density, initial pH of the solution, time of electrolysis, initial dye concentration and solution conductivity were studied in an attempt to reach higher removal efficiency. The findings in this study shows that an increase in the current density up to 60-80 A m(-2) enhanced the color removal efficiency, the electrolysis time was 5 min and the range of pH was determined between 5.5 and 8.5 for two mentioned dye solutions. It was found that for, the initial concentration of dye in solutions should not be higher than 80 mg l(-1) in order to achieve a high color removal percentage. The optimum conductivity was found to be 8 mS cm(-1), which was adjusted using proper amount of NaCl with the dye concentration of 50 mg l(-1). Electrical energy consumption in the above conditions for the decolorization of the dye solutions containing BR46 and BB3 were 4.70 kWh(kgdye removed)(-1) and 7.57 kWh(kgdye removed)(-1), respectively. Also, during the EC process under the optimized conditions, the COD decreased by more than 75% and 99% in dye solutions containing BB3 and BR46, respectively.     

TiO2-UV photocatalytic oxidation of Reactive Yellow 14: effect of operational parameters

The photocatalytic decolourisation and degradation of an azo dye Reactive Yellow (RY14) in aqueous solution with TiO(2) as photocatalyst in slurry form has been carried out using UV-A radiation (365 nm). The effect of various parameters such as catalyst loading, radiation intensity and initial dye concentration on the dye removal was investigated to find optimum conditions. The decolourisation and degradation kinetics have been analysed. Both follow modified Langmuir-Hinshelwood kinetic (L-H) model. A study on the effect of electron acceptors on photooxidation reveals that both decolourisation and degradation increase in the presence of H(2)O(2), (NH(4))(2)S(2)O(8), KBrO(3), to certain dosage beyond which the enhancement effect is negligible. But negative effects are observed in the presence of NaCl or Na(2)CO(3).     

The effect of drilling parameters on bone

For orthopaedic biomaterial implantation testing, specimens are often implanted into cortical bone defects. The implantation site is assumed to be one of the factors that influence the bone response to biomaterials. The aim of this study was to investigate the bone-healing process in drilled cortical defects at different sites with respect to time. Sheep metatarsus was implemented, since it is a long straight bone with four flat faces. Thus, the different drilling sites were obtained by changing the longitudinal level (proximal, middle and distal) and bone aspect (anterior, lateral and posterior). Metatarsi were obtained at 1, 2, 3 and 4 months post-operatively and with non-decalcified sections the newly formed bone area was measured using a microscope connected to an image analyser. The rate of bone formation was higher in the anterior aspect (P<0.05). The new bone did not form concentrically from the hole edge towards the centre, and the principal direction of bone growth was different between the anterior and the posterior aspects (P<0.05). However, there was no difference with respect to the longitudinal axis. These results indicate that the implantation site must be considered when analysing the bone response to biomaterials implanted in cortical defects.     

Effect of operational parameters on the recovery rate of an oleophilic drum skimmer

The primary objective of this research was to determine the relationship between operational variables and oil spill recovery rates, by performing a full-scale oil spill recovery test using an oleophilic drum skimmer. Prototype interchangeable oleophilic skimmer drums with aluminum, polyethylene and Neoprene surfaces were fabricated and tested at the field scale at the Ohmsett-National Oil Spill Response Test Facility. This study determined the effect of the recovery surface material, oil properties, oil slick thickness, temperature and drum rotational speed on the oleophilic drum skimmer recovery rates. It was found that the selection of the recovery surface material can increase the recovery rates up to 20%. The increase in oil slick thickness from 10 to 25 mm led to up to two times higher recovery rates for a viscous oil, but did not have any noticeable effect on the recovery rates of light oil.     

Influence of operational parameters on the TiO2 photocatalytic degradation of Methylene blue

Thin films of titanium oxide were obtained by dip-coating, using the sol–gel method. TiO₂ powder (Degussa, P25) and polyethylene glycol (PEG) were added to enhance the photocatalytic properties of resulting films. Effects of experimental variables on the photocatalytic properties of the coatings were evaluated based on the degradation efficiency of the reference dye (Methylene blue). The photocatalytic activity of resulting TiO₂ coatings was improved with the loading of TiO₂ powder (Degussa, P25) and PEG in the sols. The electron-hole pair photogeneration increases with the energy of irradiation and improves photocatalytic efficiency. Increasing coating thickness leads to a rough surface with more reaction sites. Photodegradation conversion of Methylene blue (Mb) decreases with an increase in the initial concentration of Mb.     

The effect of ultrasound on the parameters of metal-dielectric-semiconductor structures

Data on the effect of ultrasound on the metal-oxide-semiconductor structures preliminary irradiated by γ-quanta are presented. It is demonstrated that the ultrasonic action results in a decrease of the radiation-induced charge in the dielectric layer of the structures under study. The observed effects are explained using a mechanism of the ultrasound-stimulated diffusion of radiation defects in the field of elastic stresses in the layer of silicon dioxide.     

Influence of aerodynamics on the critical parameters of thermal ignition

A numerical analysis of the critical conditions of thermal ignition for a two-dimensional cylindrical reactor with flow field occurrence was carried out. The critical conditions of thermal ignition were defined as bifurcation points of the limit type. The dependence of the bifurcation points on aerodynamics was analysed by a sequential variation of the Peclet number. The flow field in the reactor was generated previously by a numerical solution of the Navier-Stokes equations. The nonlinear parabolic equation of heat balance and linear eigenvalue boundary problems occurring in the proposed non-stationary method for calculating the bifurcation points was solved numerically using the finite difference technique. It was shown that the critical points of thermal ignition form a surface bounded by the line of ‘limit of criticality’ in the parameter space. For large values of the Peclet number, the dependence of the critical parameter of ignition on Peclet number becomes linear.     

The effect of cathode deuteration on the parameters of vacuum-arc plasma

We propose a model for determining the influence of the relative content of deuterium in a zirconium cathode on the properties of vacuum-arc plasma. It is shown that the occlusion of deuterium in the cathode leads to an additional energy consumption for its ionization and to the related decrease in the average charge of cathode material ions in the discharge plasma. Deuterium in the cathode spot is fully ionized, and the drift velocity of deuterium ions almost coincides with that of ions of the cathode material.     

The effect of particles on the critical strain associated with the Portevin-LeChatelier effect in aluminium alloys

The effect of particles on the critical strain, _c, associated with the Portevin-LeChatelier (PL) effect of aluminium alloys is studied using Al-Mg-Ni and Al-Si alloys. Al-Mg-Ni and Al-Si alloy matrixes are composed of Al₃Ni and Si particles, respectively. Tensile tests were performed in the temperature range 223–273 K in which the critical strain decreases with increasing temperature, and strain rates between 10^–5 and 10^–2 s^–1 were chosen. According to the apparent activation energies, Q, Mg and Si solute atoms are responsible for the flow instability in Al-Mg-Ni and Al-Si alloys, respectively. The experimental results also show that the critical strain decreases with decreasing particle spacing, d _p. Since the particle spacing is small compared to the corresponding grain size, the decrease in critical strain should be ascribed to the effect of particles. Considering that the dislocation density is increased by the particles, a modified model showing the critical strain, _c, as a function of particle spacing, d _p, is proposed as T ^–1 exp (–Q/kT), in which , T and k are the strain rate, temperature and Boltzmann constant, respectively. Linear fit of the plots of In _c versus In d _p and In _c versus In d _p indicates that this equation is appropriate to rationalize the particle effect on the critical strain.     

The effect of condensation on the parameters of pulsed supersonic streams

We report on the results of mass-spectrometric measurements conducted in the pulsed supersonic streams of argon, nitrogen, and helium. Evolution of the time parameters of a stream determined as functions of the retarding pressure P ₀ is compared to the pattern of variation of the mass peak intensities corresponding to monomers and clusters. The transition of a gas flow into the condensation regime is accompanied by changes in the flight time and the halfwidth of the monomer signal measured in the molecular beam formed from the supersonic stream. It is demonstrated that the monitoring of the time parameters of a pulsed stream allows different condensation stages to be distinguished.     

The effect of the processing parameters on the fabrication of auxetic polyethylene

Auxetic (negative Poisson's ratio) ultra high molecular weight polyethylene has been fabricated by a novel thermal processing route consisting of three stages-compaction, sintering and extrusion. In this paper, the sintering stage is examined in detail, the processing window investigated and the optimum conditions to produce the microporous microstructure necessary for a negative Poisson's ratio are identified. The effects of varying the processing parameters are also studied.     

Thermodynamic parameters of hydrocarbons in the critical range

Scale equations of state have been derived for normal octane and nonane, which describe the thermal and caloric properties of those substances with an error close to the error of experiment.Translated from Inzhenerno-Fizicheskii Zhurnal, No. 12, pp. 929–934, December, 1990.     

湿法纺丝条件对临界凝固时间的影响

以聚丙烯腈-二甲基亚砜-水体系为研究对象,通过建立数学模型,对聚丙烯腈湿法纺丝凝固的初期阶段进行研究。借助MATLAB软件,采用有限元法对数学模型进行求解。利用数学模型考察纺丝条件对纺丝液临界凝固时间的影响。结果表明:(1)凝固浴浓度在一定程度上决定凝固进程;纺丝液临界凝固时间随凝固浴浓度升高而增加,且增加的趋势是越来越快,当浓度大于60%尤为明显;(2)纺丝液临界凝固时间随纺丝液中水含量的增加而减小,使纺丝液凝固时发生瞬时相分离的趋势增大;(3)随着喷丝孔直径的增加,纺丝液临界凝固时间会延长。     

The effect of additives on critical phenomena in CO2

The density distribution over the height of a vessel has been investigated in a gravitational field using floats with magnetic suspension. The substance studied was carbon dioxide containing small amounts of added noncondensible gases. It is shown that near the critical point the density distribution over the height of the vessel depends to a large extent on the amount of additive.