Effects Of Various Other Parameters Research Articles

Aerodynamic behaviour of double hinged articulated loading platforms

Articulated loading platforms (ALPs) belongs to a class of offshore structures known as compliant. ALP motions have time periods falling in the wind excitation frequency range due to their compliant behaviour. This paper deals with the dynamic behavior of a double hinged ALP subjected to low-frequency wind forces with random waves. Nonlinear effects due to variable submergence, fluctuating buoyancy, variable added mass, and hydrodynamic forces are considered in the analysis. The random sea state is characterized by the Pierson-Moskowitz (P-M) spectrum. The wave forces on the submerged elements of the platform's shaft are calculated using Morison's Equation with Airy's linear wave theory ignoring diffraction effects. The fluctuating wind load has been estimated using Ochi and Shin wind velocity spectrum for offshore structures. The nonlinear dynamic equation of motion is solved in the time domain by the Wilson-e method. The wind-structure interactions, along with the effect of various other parameters on the platform response, are investigated. The effect of offset of aerodynamic center (A.C.) with the center of gravity (C.G.) of platform superstructure has also been investigated. The outcome of the analyses indicates that low-frequency wind forces affect the response of ALP to a large extent, which otherwise is not enhanced in the presence of only waves. The mean wind modifies the mean position of the platform surge response to the positive side, causing an offset. Various power spectral densities (PSDs) under high and moderate sea states show that apart from the significant peak occurring at the two natural frequencies, other prominent peaks also appear at very low frequencies showing the influence of wind on the response.

Electrostatic waves driven by electron beam in lunar wake plasma

A linear analysis of electrostatic waves propagating parallel to the ambient field in a four component homogeneous, collisionless, magnetised plasma comprising fluid protons, fluid He++, electron beam, and suprathermal electrons following kappa distribution is presented. In the absence of electron beam streaming, numerical analysis of the dispersion relation shows six modes: two electron acoustic modes (modes 1 and 6), two fast ion acoustic modes (modes 2 and 5), and two slow ion acoustic modes (modes 3 and 4). The modes 1, 2 and 3 and modes 4, 5, and 6 have positive and negative phase speeds, respectively. With an increase in electron beam speed, the mode 6 gets affected the most and the phase speed turns positive from negative. The mode 6 thus starts to merge with modes 2 and 3 and generates the electron beam driven fast and slow ion acoustic waves unstable with a finite growth. The electron beam driven slow ion-acoustic waves occur at lower wavenumbers, whereas fast ion-acoustic waves occur at a large value of wavenumbers. The effect of various other parameters has also been studied. We have applied this analysis to the electrostatic waves observed in lunar wake during the first flyby of the ARTEMIS mission. The analysis shows that the low (high) frequency waves observed in the lunar wake could be the electron beam driven slow (fast) ion-acoustic modes.

Optimization of process parameters for mercury extraction through pseudo-emulsion hollow fiber strip dispersion system

In the present work, pseudo-emulsion hollow fiber strip dispersion system was used in which the pseudo-emulsion phase consisted of di-2-ethylhexylphosphoric acid as a carrier, n-heptane as an organic solvent and sulphuric acid with thiourea as stripping solution. Experiments were carried out in order to optimize the process dependent factors for the maximum extraction of Hg(II) from aqueous solutions of mercuric chloride using face-centered central composite design (CCF). The three process dependent factors for CCF were mercury concentration in the feed phase, carrier concentration in the membrane phase and sulphuric acid concentration in the stripping phase. The study has also focused on the effects of various other parameters, such as hydrodynamic conditions, volume ratio of the membrane solution to the stripping solution, stirring speed in the pseudo-emulsion tank. Effect of multiple cycles using the same pseudo-emulsion on mercury extraction was also analyzed. A model developed by regression analysis showed that 98% mercury extraction can be achieved from aqueous solutions at the optimum conditions. A mass transfer model was also developed and from that aqueous and membrane resistances were evaluated as 2.3×104sm−1 and 3.9×105sm−1, respectively, under optimum conditions. Hence, membrane diffusion was found to be rate-controlling step.

Response Surface Modelling and Optimization of Mercury Extraction through Emulsion Liquid Membrane

Mercury(II) is a very harmful metal, highly toxic, and carcinogenic in nature. Experiments were carried out using the emulsion liquid membrane (ELM) technique in order to evaluate the maximum extraction of mercury(II) from aqueous solutions of mercuric chloride using 33 factorial design. The ELM consisted of di-2-ethylhexylphosphoric acid as a carrier, toluene as an organic solvent, span 80 as a surfactant, and sulphuric acid with thiourea solution as stripping phase. The three factors for the factorial design were mercury(II) concentration in the aqueous solution, that is, feed phase concentration, carrier concentration in the membrane phase, and sulphuric acid concentration in the stripping phase. The study has also highlighted the effects of various other parameters, such as pH of the feed phase and thiourea concentration on mercury(II) extraction. The optimization of the factors to obtain maximum extraction were carried out by incorporating main effect plots, interaction plots, analysis of variance (ANOVA), normal probability plots, residual plots, surface plots, and contour plots. A reduced model developed by regression analysis was suggested in which the experimental data were fitted very well. The results showed that it is possible to extract mercury(II) up to 98% from aqueous solutions at the optimum conditions.

Balancing the reagent suite to optimise grade and recovery

The recovery of Platinum Group Metals and Gold (PGM + Au) from the UG-2 reef of the Bushveld Complex is an interesting challenge when the selection and optimisation of the reagent suite is considered. The UG-2 reef is characterised by two predominant gangue phases i.e. chromite and silicate, that have significantly different physical and chemical properties. A strategy needs to be devised to address concentrate grade that will reduce the recovery of gangue without significantly affecting the recovery of the valuable species. Recovery of the valuable species is complicated by the fact that PGM + Au occurs as a variety of different minerals having varying chemical and physical properties. The operating strategy has to consider the characteristics of the valuable mineral species and maximise recovery while meeting stringent grade specifications. Laboratory tests are conducted to illustrate the effect of the various flotation parameters. Applications of the findings on existing concentrators are discussed illustrating the need for a better understanding of the contribution of the various mechanisms occurring in the flotation cell. The paper demonstrates the significance of entrainment in the recovery of both valuable species and gangue species, and the need for a greater understanding of this non-selective sub-process on overall circuit performance. This paper forms part of a postgraduate study through the University of Cape Town into the development of a mechanistic model for the entrainment process. Although much work has been done in this study of the effect of various other parameters on the flotation of UG-2 ore, this paper focuses on the effect of frother, depressant and water on the flotation results.

Adsolubilization of Organic Compounds in Surfactant-Modified Alumina

Adsolubilization is the solubilization of organics into the three dimensional micelle like structures formed by the adsorption of ionic surfactants at high concentration on oppositely charged surfaces. Adsolubilization process could efficiently be used for the removal of different organic pollutants like dyes, phenolic compounds, etc. from water environment. In the present work, the adsorption characteristics of sodium dodecyl sulfate (SDS), an anionic surfactant (AS) on neutral alumina were studied in detail. Alumina was found to be an efficient adsorbent for SDS and could be used for the removal of SDS from its highly concentrated (several thousand ppm) solution. The equilibrium time found was 2 h. Though the removal efficiency was low (∼ 65%) at neutral pH, but at slightly acidic condition and in the presence of NaCl, the efficiency could be increased drastically (>98%). The adsorption isotherm study showed four distinct regions. The effects of various other parameters such as adsorbent dose, the presence of different ions (Cl - , NO 3 - , SO 4 2- and Fe 3+ ), and non-ionic surfactant on the SDS adsorption were also studied. It was observed that the adsorption capacity was increased due to the presence of these ions in general. After the adsorption of SDS on alumina, the alumina, which was then called the surfactant-modified alumina (SMA), was used for the removal of crystal violet (CV), a well-known cationic dye and phenol from aquatic environment. The kinetic studies showed that 1 h shaking time was sufficient to achieve the equilibrium for CV. The equilibrium time for phenol was 1.5 h. Studies were conducted to see the effects of adsorbent dose on the removal of CV and phenol separately using the SMA. The pH was maintained at 6.7±0.1. The SMA was found to be very efficient, and ∼ 99% and ∼ 90% efficiency could be achieved under optimised conditions for the removal of CV and phenol when present even at a high concentration (200 ppm for CV and 50 ppm for phenol). Effects of different parameters like SDS coverage on alumina, pH, presence of different ions, temperature, etc. were studied. To test whether the removal of CV and phenol was possible from real water using the SMA, the removal studies were conducted using CV and phenol spiked tap water samples. It was interesting to note that the removal efficiency was better for the tap water samples than for the distilled water ones. Desorption of SDS from the SMA was possible using aqueous sodium hydroxide and desorption of CV and phenol from the exhausted surface could be done by rectified spirit.

Study of turn-on test method for high-voltage thyristor valve

Digital simulations have been conducted to analyze the thyristor valve turn-on phenomenon while a valve arrester is conducting, which gives the most severe turn-on stress for the valve. The effects of various other parameters have also been clarified. Based on this analysis, two test methods are proposed that verify a valve turn-on during arrester conduction, and their effectiveness is described. The nonrepetitive turn-on test given in the IEC Std Pb. 700 and IEEE Std 857 is studied, and a new test voltage level based on these analyses is proposed. >

On the investigation of local interface sharpness and period uniformity of multilayers in plan-view observation by CBED

By using computer simulation based on the dynamical diffraction theory, local interface irregularities (interface sharpness and period uniformity) of a multilayer are investigated in plan-view observation by convergent-beam electron diffraction (CBED) with high spatial resolution. It is found that the intensity of some bright lines in satellite higher-order Laue zone (sHOLZ) reflection discs is very sensitive to interface irregularity (interface sharpness and period non-uniformity). The effect of various other parameters is also discussed. The investigation shows that, if specific bright lines in different rings of sHOLZ discs are used, interface irregularity can be evaluated accurately.

A probabilistic model for evaluating the remaining life of evaluating the remaining life of electrical insulation in rotating machines

A Markov model is introduced for estimating the remaining life of electrical insulation in large motors and generators. The model incorporates various levels of insulation deterioration and periodic (minor) maintenance. The model permits computation of the average time before insulation failure occurs. A mathematical formulation of the expected transition time from any deterioration state to the failure state (expected remaining life) is given. Data requirements are discussed, and numerical examples are presented. This model would also allow assessment through sensitivity studies of the relative effects of various other parameters in the process which are controllable, e.g. maintenance policy and stress level. Even though it is theoretically possible to apply the Markov models to any particular insulation deterioration mechanism, this approach is best applied to an overall insulation determination problem which combines the effects of all individual processes. The models are fairly flexible. They allow, for example, representation of changing stresses acting on the machine insulation as the utility operating environment changes. >

Solvent extraction of Au/III/ with 1,2,3-benzotriazole into n-butanol

A new and rapid method has been developed for the quantitative extraction of Co/III/ with 1, 2, 3-benzotriazole into n-butanol. The extraction coefficient value of Co/III/ between n-butanol and an aqueous 5% solution of 1, 2, 3-BT in 2M sodium acetate-acetic acid buffer showed a maximum value of E=280 at pH 8.5. The effect of various other parameters on the extraction coefficient of Co/III/ such as solvents, anions, cations etc. has also been studied. The stoichiometry of the metal: reagent determined by the method of substoichiometric extraction and slope-ratio method was found to be 1∶2. The separation factors studied for most of the elements were found to be better than 103.

Electroinitiated Polymerization of Styrene in a Mixed Two-Phase Medium

Abstract In extension of our earlier work on electroinitiated polymerization in biphasic media, the electroinitiated polymerization of styrene has been studied using a mixed two-phase system in which formamide together with some added electrolyte is used as the polar phase and the monomer in the bulk form as the nonpolar phase. Among a series of zinc and ferric salts used as the electrolyte, ZnBr2 was found to be the most effective. The polymer obtained has a molecular weight of 44–47 ± 103. The effects of various other parameters, such as the dependence of polymer yield on current, the concentration of the electrolyte, the temperature, and the stirring, have also been examined, and a plausible mechanism based on the electrochemical formation of radicals involving a CT complex has been suggested.

A new and rapid method for the solvent extraction of Ru/III/ with 1,2,3-benzotriazole into 1-pentanol

A new and rapid method has been developed for the quantitative extraction of Ru/III/ with 1,2,3-benzotriazole /1,2,3-BT/ into 1-pentanol. The extraction coefficient value of Ru/III/ between 1-pentanol and an aqueous 5% solution of 1,2,3-BT in 2M sodium acetate-acetic acid buffer showed a maximum value of E=46 at pH 4.5. The effect of various other parameters on the extraction coefficient of Ru/III/ such as solvents, anions, cations, etc. have also been studied. The stoichiometry of metal:reagent determined by the method of substoichiometric extraction and slope ratio method was found to be 1∶3. Decontamination factors for many elements in the substoichiometric extraction of Ru/III/ were also evaluated.

Live Load Effect on Dynamic Response of Structures

For the aseismic design of structures, the dynamic forces are generally replaced by equivalent static forces which are usually given as a function of the effective weight of the structure. The effective weight of a structure consists of full dead weight and a fraction of live loads as these are invariably spring and dashpot mounted. This paper presents the effect of such a mounting on the response of structures subjected to horizontal ground motion caused by an earthquake. The primary system as well as live load system have been idealized as single degree of freedom systems. This study indicates that only a part of the live load is effective under horizontal vibrations and this depends on the ratio of live to dead load and the amount of damping present in the live load model. The effect of various other parameters, namely, the spring mounting, undamped natural period of vibration of the primary system and the ground motion has also been investigated.