Avanti Publishers
Not a member yet
711 research outputs found
Sort by
The Regeneration of Ammonia Solution by Calcium Hydroxide for Carbon Dioxide Absorption from the Flue Gas
Get PDFThe tests of this study were conducted by the semi-continuous flow experiments to absorb the carbon dioxide (CO2) gas in a bench-scale spraying column reactor. The absorption capacity and the regeneration efficiency of the absorbed ammonia (NH3) solution were determined. In this study, the maximum regeneration efficiency is 68.4% as the concentration of NH3 solution is 1% and the ratio of calcium hydroxide (Ca(OH)2) and CO2 is 1 as well. Furthermore, the absorption capacity of the NH3 solution decreases from 1.67 to 0.27 kg-CO2/kg-NH3 after regenerating four times due to the 30-38% loss each time. Regarding the regeneration kinetics between absorbed products and Ca(OH)2, the comparative degree of covered Ca(OH)2 during the reaction was recognized after fitting by a surface coverage model. Finally, the ammonium bicarbonate (NH4HCO3) reduced by Ca(OH)2 to calcium carbonate (CaCO3) solid and NH3 solution in the regeneration reactions was observed by scanning electron microscope (SEM), Energy-dispersive X-ray spectroscopy (EDS) pictures and X-Ray Diffraction (XRD) analyses. Although the NH3 solution can be regenerated by Ca(OH)2 effectively in this study, the overall benefit of this process should be estimated further in the energy aspect
Detection and Discrimination of the Periodicity of Prime Numbers by Discrete Fourier Transform – Symphony of Primes
Get PDFA novel representation of a quasi-periodic modified von Mangoldt function L(n) on prime numbers and its decomposition into Fourier series has been investigated. We focus on some particular quantities characterizing the modified von Mangoldt function. The results indicate that prime number progression can be decomposed into periodic sequences. The main approach is to decompose it into sin or cosine function. Basically, it is applied to extract hidden periodicities in seemingly quasi periodic prime function. Numerical evidences were provided to confirm the periodic distribution of primes
Removal of Methyl Orange from Aqueous Solutions by Using Zn-Al Layered Double Hydroxide as Photocatalyst
Get PDFThe Zn-Al layered double hydroxide (LDH) was prepared using co-precipitation method at constant pH and characterized from structural point of view. Due to the high concentration of ZnO obtained after LDH calcinations, the material can be used as photocatalyst in removal of organic persistent compounds from water. The photocatalytic activity of the as-synthesized and calcined materials was evaluated for the degradation of Methyl Orange dye under UV irradiation. The influence of calcination temperature, solid: liquid ratio and initial dye concentration on photocatalytic activity of LDH was studied. The increase of calcination temperature and solid: liquid ratio and the decrease of initial dye concentration leads to increasing degradation efficiency
Performance Optimization of a Turbocharged Spark-Ignition VVA Engine at Part Load
Get PDFNowadays, modern internal combustion engines show more and more complex architectures in order to improve their performance. Referring to the spark-ignition (SI) engines, downsizing philosophy and Variable Valve Actuation (VVA) systems allow to reduce the Brake Specific Fuel Consumption (BSFC) at low and medium load, while maintaining the required performance at high load. On the other hand, the above solutions introduce additional degrees of freedom for the engine control, requiring longer calibration time and experimental effort.
In the present work, a twin-cylinder turbocharged VVA SI engine is numerically investigated by a one-dimensional (1D) model (GT-PowerTM). The considered engine is equipped with a fully flexible VVA actuation system, realizing an Early Intake Valve Closure (EIVC) strategy. Proper "user routines" are implemented in the code to simulate turbulence and combustion processes.
In a first stage, 1D engine model is validated against the experimental data under part load condition, both in terms of overall performance and combustion evolution. The validated 1D engine model is then integrated in a multipurpose commercial optimizer (mode FRONTIERTM) with the aim to identify the engine calibrations that simultaneously minimize BSFC and Brake Mean Effective Pressure (BMEP) under part load operation at a specified engine speed of 3000rpm. In particular, the decision parameters of the optimization process are the EIVC angle, the throttle valve opening and the waste-gate valve opening and combustion phasing. Proper constraints are assigned for the pressure in the intake plenum in order to limit the gas-dynamic noise radiated by the intake mouth.
The adopted optimization approach shows the capability to reproduce with a very good accuracy the experimentally advised optimal calibration, corresponding to the numerically derived Pareto frontier in the Brake Mean Effective Pressure (BMEP)-BSFC tradeoff. The optimization also underlines the advantages of an engine calibration based on a combination of EIVC strategy and intake throttling, rather than a purely throttle-based calibration.
The developed automatic procedure allows for a "virtual" calibration of the considered engine on completely theoretical basis and proves to be very helpful in reducing the experimental costs and the engine time-to-market
Fragility Estimates of Rc Building Using Etabs
Get PDFEarthquakes are the most destructive natural disaster causing lot of casualties, injuries and economic losses leaving behind a trail of panic. Earthquake risk assessment is needed for disaster mitigation, disaster management, and emergency preparedness. Vulnerability of building is one of the major factors contributing to earthquake risk. The vulnerability functions framed for a particular building is input parameter for loss estimation. Procedure for developing fragility curves of specific building type is discussed. Seismic fragility curves were developed and damage probability threshold has been constructed for the chosen problems
The Importance of Transition from Micro to Nano Clay Size in Improving the Engineering Properties of Sandy Soils (Poorly Graded Sand)
Get PDFNano-clays are a broad class of naturally occurring inorganic minerals in the form of plate-like alumina-silicate layers with thickness between 1nano-meter to 10micro-meters. Due to the very small sizes of nanoparticle, they provide a large specific surface area which make them to absorb water and fill the voids within the soil particles.The aim of this paper is to investigate the use of nano-clays for modifying the engineering properties of granular soils. This type of soil covers large parts of the land surface and cause many problems for the development of urban areas, infrastructure projects and instability of slopes along the railways and road networks.The mineral composition of the granular soil mainly consists of quartz grains and the soil types are classified as poorly- to well-grade materials. In order to evaluate the effect of micro and nano clay on modification of geotechnical properties of the sand, different percentage of 0.5%, 1%, 2% and 4% of micro-clay and percentage 0.5%, 1%, 2%, 4%, 6%, 8%, 10%, 12% and 14% nano-clay. In order to determine the value of its peak were done. Then mixed with the sand and a number of tests such as compaction test, direct shear test are conducted on the samples. The result shows that maximum dry unit weight and maximum optimum moisture content were obtained when 10% nano-clay mixed with the sand. It was also was noted that the increment of nano-clay and micro-clay causes gradual increases and gradual decreases of the shear strength of the sample, respectively
Economic Calculation Forecasting of Tourism: Example from Kazakhstan
Get PDFAbstract: This article evaluates touristic – recreational potential of Kazakhstan and model of organizational forecast of tourist cluster. Interactions within the cluster lead to the development of new ways to compete and generate an entirely new opportunities to overcome isolation on domestic issues, inertia, inflexibility, and collusion between competitors that reduce or completely block the beneficial effects of competition and the emergence of new firms. Thus, the presence of the cluster allows domestic industry to maintain its advantage, and not give it to those countries that are more inclined to upgrade
Sidetrack/Recompletion Time Evaluation by Proxy Model
Get PDFSidetrack during field development and ongoing production arises to exploit bypassed reserves, unexploited zones and to tackle unforeseen conditions that are likely to occur due to uncertainties and heterogeneity in initially characterizing a reservoir. Whereas recompletion is due to sequential production of stacked reservoirs or multiple pay zones that is caused by regulation on commingling. The purpose of this paper is to investigate the application of experimental design (ED) in optimizing sidetrack/recompletion time of multiple pay zones in view of maximizing returns on investment by net present value (NPV) and expected monetary value (EMV). A hypothetical reservoir of two pay zones with uncertainties associated with pay thickness, porosity, permeability and time to perform the sidetrack was considered. The ED method of Box-Behnken response surface design was used to reduce the number of runs made by generating the most effective combination of variables for the experiment. Experimental runs were conducted with a Black Oil reservoir simulator to give production profile and the computed NPV was used afterwards to produce the Proxy model in ED. NPV computed from the Proxy Model was reasonable compared to that of the production profile from the simulator. However, a higher level D-Optimal or factorial design may be required for a reasonable match of EMV with respect to obtaining a realistic sidetrack/recompletion time
The Effect of Microwave Treatment on Ryegrass and Wild Radish Plants and Seeds
Get PDFAnnual ryegrass (Lolium rigidum) and wild radish (Raphanus raphanistrum) are significant weeds in Australian winter cropping systems. These species have developed significant herbicide resistance and new control strategies need to be developed. Microwave energy has been considered for weed control for some time. The research considered the effect of varying amounts of microwave energy on plants and their seeds for each species. Several experiments explored the interaction between microwave energy and seed depth in the soil. Plant responses to microwave energy were also determined for each species. Seed treatment requires higher energy applications than plant treatment and is conceptually similar to soil fumigation treatments. Soil treatment may have application in some high value horticultural crops, which already use soil fumigation. Microwave treatment of plants requires less energy, with wild radish requiring about 60 Jcm-2 to achieve 100% mortality, while ryegrass plants require about 370 Jcm-2 to achieve 100% mortality. Microwave treatment of growing plants can be compared to the application of herbicide. Therefore control of growing plants should be the focus of developing a commercially viable microwave weed control device for cropping systems
Ultrasonic Technique on Fluid Saturation in Porous Media
Get PDFPhase behavior of hydrocarbon fluids is closely related to porous media. However, there are many limitations of current detection techniques. Therefore, it is very urgent to find a suitable method to solve this problem. In this paper, based on the brine and three natural cores from Jilin oilfield, the relations of the interval transit time and fluid saturation of these cores both in brine/air system and kerosene/air system were measured, and the difference of these relations during the process of displacement, imbibition and air drying were compared and analyzed. Results show that the ultrasonic technique is a potential method to invert fluid saturation in porous media