Influence of wet chemical cleaning on quantum efficiency of GaN photocathode

GaN samples 1-3 are cleaned by a 2：2：1 solution of sulfuric acid（98%） to hydrogen peroxide（30%） to de-ionized water;hydrochloric acid（37%）;or a 4：1 solution of sulfuric acid（98%） to hydrogen peroxide（30%）.The samples are activated by Cs/O after the same annealing process.X-ray photoelectron spectroscopy after the different ways of wet chemical cleaning shows：sample 1 has the largest proportion of Ga,N,and O among the three samples,while its C content is the lowest.After activation the quantum efficiency curves show sample 1 has the best photocathode performance.We think the wet chemical cleaning method is a process which will mainly remove C contamination.

Determining the Optimal Parameters of an Advanced Linter Machine

In this article, research was conducted to improve Linter machines that remove short fibers remaining in ginned cotton seeds at cotton ginneries. The study examined the effect of changing the dimensions of the brush drum, guide and mesh surface in the cleaning device proposed for the linting machine on the movement of the peg and the cleaning efficiency, and the highest level of efficiency in separating impurities from the peg was determined. During the study, the main factors influencing the effective operation of the improved linting machine were identified, the limits of their values were determined, and studies were carried out using the mathematical modeling method. As a result, at the values of the given coefficients, efficient operation of the improved linting machine was observed, that is, the lint cleaning efficiency reached 55.1%.

Multi-phase computer modeling and laboratory study of dust capture by an inertial Vortecone scrubber

Dust generated in mining and tunneling activities is hazardous to health of persons and safety of operations. These projects employ pick-milling machines to extract minerals and rock by mechanical breakage.The machines are equipped with flooded-bed scrubbers that encase dust particles within fine water films as particles encounter a flooded wire-mesh screen. A major disadvantage is that the screen gets clogged when particles become trapped within the wire mesh, reducing airflow through the scrubber and increasing ambient dust concentrations. Thus, the system requires frequent maintenance or replacement. The application of a Vortecone scrubber as an improved alternative to conventional fibrous type scrubbers is investigated. A Vortecone forces dust-laden air and water to follow a complex, rapidly swirling motion.The momentum drives dust particles towards the periphery where they are captured by the water film.The operating characteristics of a reduced-scale physical model of a Vortecone, with its primary axis mounted in the horizontal orientation, was analyzed numerically and experimentally. Computational fluid dynamics(CFD) models depicting the spraying action and multi-phase air/water flows using the volume of fraction(VOF) approach, are presented. Experimental results, utilizing an optical particle counting technique to establish the dust-cleaning capabilities of the model, are also described.

Evaluation of methyl ester sulphonate spacer fluid additive for efficient wellbore clean-up

Oil-based drilling fluid(OBDF)is used to drill through high permeable pay zone to prevent possible damage to the formation.However,the oil based drilling fluid leaves behind filter cake residue and oilwet surfaces which hinder cement bonding.Spacer fluid is usually introduced to clean up the wellbore prior to cementing job.This work presents a spacer fluid designed with environment-friendly anionic methyl ester sulphonate(MES)surfactant and evaluated through a series of experimental tests to ascertain its effectiveness to clean wellbore.Addition of methyl ester sulphonate to confected waterbased drilling fluid at high amount(0.15 g and 0.20 g)showed good rheological properties,compatibility with OBDF and cement and low contact angle on steel and sandstone in the range of 21.9°-34.7°.Furthermore,results show that it requires less amount of MES spacer fluid to revert oil-wet OBDF aqueous phase to water external continuous phase,validating the low contact angle measurements.Cleaning efficiencies for two best performing MES spacer fluids achieved 83.27%and 94.3%respectively.Shear bond strength were measured to be 1.3 MPa and 1.05 MPa for steel and sandstone respectively,above the minimum allowable shear bond strength for oil well cementing.Hence,MES spacer fluid can be used to clean up wellbores in high permeable formations and in well completion,where strong cement bonding is required.

On the Design and Optimization of a Clean and Efficient Combustion Mode for Internal Combustion Engines through a Computer NSGA-Ⅱ Algorithm

In order to address typical problems due to the huge demand of oil for consumption in traditional internal combustion engines,a new more efficient combustion mode is proposed and studied in the framework of Computational Fluid Dynamics(CFD).Moreover,a Non-dominated Sorting Genetic Algorithm(NSGA-Ⅱ)is applied to optimize the related parameters,namely,the engine methanol ratio,the fuel injection time,the initial temperature,the Exhaust Gas Re-Circulation(EGR)rate,and the initial pressure.The so-called Conventional Diesel Combustion(CDC),Homogeneous Charge Compression Ignition(HCCI)and the Reactivity Controlled Compression Ignition(RCCI)combustion modes are compared.The results show that RCCI has a higher methanol ratio and an earlier injection timing with moderate EGR rate and higher initial pressure.The initial temperature increases as the methanol ratio increases.In comparison,CDC has the lowest hydrocarbon and CO emissions and the highest combustion efficiency.At different crankshaft rotation angles corresponding to 50%of the combustion amount(CA50),the combustion temperature and boundary layer temperature of HCCI change significantly,while those of RCCI undergo limited variations.At the same CA50,the exergy losses of HCCI and RCCI are lower than that of the CDC.On the basis of these findings,it can be concluded that the methanol/diesel RCCI engine can be used to obtain a clean and efficient combustion process,which should be regarded as a promising combustion mode.

High mercury leachate containing HgS22- complex ion： Detoxifying solidification and high efficiency Hg extraction

Clean and efficient treatment of high-mercury leachate produced from remediation of mercury-polluted soil has become a huge challenge for environmental scientists. In this work, cement solidification was firstly adopted to treat the high-concentration mercury leachate, which had high alkalinity. Different mercury concentrations, namely 3.120 mg/L Hg mercury leachate and 9.243 mg/L Hg mercury concentrated leachate, were separately solidified by Portland cement. The results indicated that simply using the cement can properly solidify both the leachates to meet the waste landfill standard, with liquid （mL）/solid （g） ratio （US ratio） of 4：10-6：10. In order to make full use of mercury in the leachates, a Hg extraction method was subsequently carried out under different experimental parameters, such as temperature and pH value. It was shown that the Hg extraction ratio could reach as high as 99.84% and almost all the mercury in the leachate could be transformed to HgS precipitate; moreover, the Hg concentration in the treated leachate was reduced from 3.120 to 0.005 mg/L at pH 2.98 and 30℃, which was much less than the limit of the national standard, indicating that the leachate had been completely cleaned and could be discharged freely. Hence, simple cement solidification renders high-mercury leachate nontoxic, and the Hg extraction method can successfully recover the Hg and enable the residual leachate to be discharged safely.

More Discussion on High Efficiency & Low Cost Clean Steel Production Platform

The construction of high efficiency, low cost clean steel platform is one of the common key technologies concerning efficiency, quality and cost. It is basic and universal and not only applicable in the R&D and production of "high-end" products, but also in the production of bulk ordinary steel products. The platform of high efficiency, low cost clean steel is the important direction of modern steel technology progress and has great significance on the competitiveness of each steel plant. The research of high efficiency, low cost platform not only involves the production and management of the steel plant, but also the academic research field (process engineering and dynamic operation) and theories and methods innovation of engineering design (theory and method of dynamic-precision design). The integrated theory and method of high efficiency and low cost clean steel platform is the binding point of metallurgical process engineering and material engineering. Different types of high efficiency, low cost clean steel platform should combine with the corresponding rolling process and iron making process so that high efficiency, low cost clean steel manufacturing system would come into being.

Prediction of design parameters of pneumatic cleaners with MARS method

One of the cleaning methods for agricultural materials is based on aerodynamic properties.Pneumatic cleaners are developed on this method.The purpose of this study is to predict the parameters such as fan angle,air velocity,and tunnel length,which are used in the design of pneumatic cleaners,through the multivariate adaptive regression splines(MARS)method.Some parameters have been estimated using the MARS method in order to use pneumatic cleaners under optimum conditions and adapt them to automation systems.The cleaners have a collection box which was installed at the outlet of the storage.Two different product collection boxes of 400 mm(defined as the first box)and 800 mm(defined as the second box)from the storage outlet section were used.From the results obtained,it was observed that the first box R2 was higher.When looking at the cross validation,it was observed that the results of the first box were more acceptable.With this study,MARS equations were used to obtain dependent variables at desired values.Using these equations,independent variables have been demonstrated to be identifiable.In the application results obtained,cleaning efficiency values were obtained in a wide range.While cleaning efficiency values reached up to 100%,the loss rate was found to be very high.Independent variables have been made identifiable to reduce the loss rate.The highest and feasible of these values were determined by MARS as 41°fan angle and 15 m/s air velocity in order to be able to apply at 97%CE and 1%LR determined for the first box.The MARS method allows for the use of more dependent and independent variables.Usable equations were obtained as a result of statistical analysis.More precise values can be obtained with these equations.It will contribute to the design of the parameters of the machine manufactured,such as speed,angle,and feeding amount.