Transport of K+, Br– and KBr through saturated inert and reactive porous media

Farhat Abbas

Anion and cations from applied agrochemicals move differently during their bulk solution flow through sandy and clayey soils. Saturated inert and reactive porous media were generated from solid glass beads and sepiolite clay minerals to mimic sandy and clayey soils. At various flow rates, solutions of potassium bromide (KBr) of various concentrations were separately displaced by deionised water through above media. Concentration of the Br– and K+ were determined with ion-specific electrodes and bulk solution by electrical conductivity (EC). Non-linear curve fitting technique, CXTFIT 2.0 was used to parameterize the breakthrough curves (BTCs) of each displacement for the anion, the cation and the bulk solution, separately. Shapes of BTCs and parameters including retardation factor (R) and coefficient of hydrodynamic dispersion (D) were used to interpret the results. For inert media, (a) the matching BTCs of the anion, cation and bulk solution were observed, (b) the values of R did not differ significantly from unity, and (c) the values of D were identical and changed with pore-water velocity, (v). For reactive media, the BTCs of anion appeared before and those of cations appeared after those of bulk solution. The values of R were less than unity for the anion, greater than unity for the cation and close to unity for the bulk solution. However, the values of D were unaffected by nature of solutes or solution. Results of this study show that separation of ions observed during transport through reactive material means that the composition as well as the concentration of a solution change continuously during flow through reactive soils i.e. clay or clay loam. These results have implications for exchange of cations and exclusion of anions from the soils of varying net negative charges and cation exchange capacity.

Jatropha and Karanj bio-fuel: an alternate fuel for diesel engine

Surendra R. Kalbande and Subhash D. Vikhe

The bio-diesel was produced from non-edible oils by using bio-diesel processor and the diesel engine performance for water lifting was tested on bio-diesel and bio-diesel blended with diesel. The newly developed bio-diesel processor was capable of preparing the oil esters sufficient in quantity for running the commonly used farm engines. The fuel properties of bio-diesel such as kinematic viscosity and specific gravity were found within limited of BIS standard. Operational efficiency of diesel pump set for various blends of bio-diesel were found nearer to the expected efficiency of 20 percent. Bio-diesel can be used as an alternate and non-conventional fuel to run all type of C.I. engine.

Effect of concentration of alkaline liquid and curing time on strength and water absorption of geopolymer concrete

Anurag Mishra, Deepika Choudhary, Namrata Jain, Manish Kumar, Nidhi Sharda and Durga Dutt

In order to address environmental effects associated with Portland cement, there is need to use other binders to make concrete. An effort in this regard is the development of geopolymer concrete, synthesized from the materials of geological origin or by product materials such as fly ash, which are rich in silicon and aluminum. This paper presents results of an experimental study on the strength and absorption characteristics of geopolymer concrete. The experiments were conducted on fly ash based geopolymer concrete by varying the concentration of NaOH and curing time. Total nine mixes were prepared with NaOH concentration as 8M, 12M, 16M and curing time as 24hrs, 48hrs, and 72hrs. Compressive strength, water absorption and tensile strength tests were conducted on each of the nine mixes. Results of the investigation indicated that there was an increase in compressive strength with increase in NaOH concentration. Strength was also increased with increase in curing time, although the increase in compressive strength after 48hrs curing time was not significant. Compressive strength up to 46 MPa was obtained with curing at 60oC. The results of water absorption test indicated that % water absorption of cubes decreased with increase in NaOH concentration and curing time. Hence, geopolymar concrete has a great potential for utilization in construction industry as it is environmental friendly and also facilitates the use of fly ash, which is a waste product from coal burning industries.

Development of hybrid model and optimization of metal removal rate in electric discharge machining using artificial neural networks and genetic algorithm

G Krishna Mohana Rao, G Ranga Janardhana, D. Hanumantha Rao and M. Srinivasa Rao

The present work is aimed at optimizing the metal removal rate of die sinking electric discharge machining (EDM) by considering the simultaneous affect of various input parameters. The experiments are carried out on Ti6Al4V, HE15, 15CDV6 and M-250. Experiments were conducted by varying the peak current and voltage and the corresponding values of metal removal rate (MRR) were measured. Multiperceptron neural network models were developed using Neuro solutions package. Genetic algorithm concept is used to optimize the weighting factors of the network. It is observed that the developed model is within the limits of the agreeable error when experimental and network model results are compared for all performance measures considered. It is further observed that the maximum error when the network is optimized by genetic algorithm has been reduced considerably. Sensitivity analysis is also done to find the relative influence of factors on the performance measures. It is observed that type of material is having more influence on the performance measures.

Analysis for flexibility in the ovality and thinning limits of pipe bends

A. R. Veerappan and S. Shanmugam

Pipe bends are critical components in piping systems. In the manufacturing process of pipe bends it is difficult to avoid thickening on the intrados and thinning on the extrados. The cross section of the bend also becomes non circular due to bending process. The acceptability of pipe bends is based on the induced level of these shape imperfections. Ovality and thinning are the shape imperfections considered for the analysis. It is observed that thinning and ovality are to be taken into account together to decide the acceptability of these bends. The possible flexibility that can be introduced in the selection of ovality and thinning limits of pipe bends to reduce rejection has been suggested. A general mathematical expression relating internal pressure, shape imperfections and bend geometry is also presented.

A simplified partial power model of slightly unstable fused coupled fibers

Saktioto, Jalil Ali, Rosly Abdul Rahman, Mohammed Fadhali and Jasman Zainal

Abstract:

Coupled fibers are successfully fabricated by injecting hydrogen flow at 1bar and fused slightly by unstable torch flame in the range of 800-1350oC. Optical parameters may vary significantly over wide range physical properties. Coupling coefficient and refractive index are estimated from the experimental result of the coupling ratio distribution from 1% to 75%. The change of structural and geometrical fiber affects the normalized frequency (V) even for single mode fibers. Coupling ratio as a function of coupling coefficient and separation of fiber axis changes with respect to V at coupling region. V is derived from radius, wavelength and refractive index parameters. Parametric variations are performed on the left and right hand side of the coupling region. At the center of the coupling region V is assumed constant. A partial power is modeled and derived using V, normalized lateral phase constant (u), and normalized lateral attenuation constant, (w) through the second kind of modified Bessel function of the l order, which obeys the normal mode, LP01 and normalized propagation constant (b). Total power is maintained constant in order to comply with the energy conservation law. The power is integrated through V, u and w over the pulling length range of 7500-9500μm for 1-D where radial and angle directions are ignored. The core radius of fiber significantly affects V and power partially at coupling region rather than wavelength and refractive index of core and cladding.  This model has power phenomena in transmission and reflection for industrial application of coupled fibers.

Buffer stocks in Kanban controlled (traditional) unsaturated multi-stage production system

M. Sreenivasa Rao, K. V. Sharma, A. Seshu Kumar and G. Krishna Mohana Rao

In recent years, most of the manufacturers are resorting to Kanban mechanism to control Work in Process inventories (WIP) in their production activity. Typical production system faces various sources of uncertainties, viz, external demand uncertainty, processing time variations and yield uncertainty etc and Kanban systems are not an exception to this. Often safety stocks are deployed to reduce the ill effects of uncertainties. In literature, there exist insights on the issues relevant to deployment of safety stocks in a Kanban controlled production system however under the assumption that external demand for the finished product is very large also known as saturated condition. In the present global competition, most products have a finite demand rate and stochastic in nature known as unsaturated condition. The present paper deals with Kanban controlled multi-stage unsaturated production (traditional) system with multiple sources of uncertainties in external demand and processing times. For the considered system, Continuous Time Markov Chain (CTMC) model is developed and expressions for steady state performance measures, viz, Probability that a customer demand is satisfied instantaneously on his arrival (known as Customer Service Level), average inventory and average throughput are derived. The expressions are subjected to numerical experimentation and to gain insights for evaluating the performance of the system. The analytical results are validated with the results obtained from stochastic discrete event simulation model at 95% Confidence Level (C.F). Further certain guidelines on the deployment of safety stocks in the considered system are presented.

Study on surface roughness minimization in turning of DRACs using surface roughness methodology and Taguchi under pressured steam jet approach

Raviraj Shetty, R. Pai, V. Kamath and S. S. Rao

Abstract:

This paper discusses the use of Taguchi and response surface methodologies for minimizing the surface roughness in turning of discontinuously reinforced aluminum composites (DRACs) having aluminum alloy 6061 as the matrix and containing 15 vol. % of silicon carbide particles of mean diameter 25µm under pressured steam jet approach. The measured results were then collected and analyzed with the help of the commercial software package MINITAB15. The experiments have been conducted using Taguchi’s experimental design technique. The matrix of test conditions included cutting speeds of 45, 73 and 101 m/min, feed rates of 0.11, 0.18 and 0.25 mm/rev and steam pressure 4, 7, 10 bar while the depth of cut has been kept constant at 0.5 mm. The effect of cutting parameters on surface roughness is evaluated and the optimum cutting condition for minimizing the surface roughness is determined. A second-order model has been established between the cutting parameters and surface roughness using response surface methodology. The experimental results reveal that the most significant machining parameter for surface roughness is steam pressure followed by feed. The predicted values and measured values are fairly close, which indicates that the developed model can be effectively used to predict the surface roughness in the machining of DRACs.

Effect of polymer additives on the mechanics of slow draining of large tank under gravity

Ch. V. Subbarao, P. King and VSRK Prasad

A mathematical equation for efflux time for gravity draining of a Newtonian liquid from a large cylindrical tank through an exit pipe located at the bottom of tank when the flow in the pipe line is turbulent is developed based on macroscopic balances. The equation is fine tuned with the experimental data and an empirical equation for friction factor is developed. The efflux time equation so developed will be of use in arriving at the minimum time required for draining the tank. When the flow is mixed, i.e. partly laminar and partly turbulent, gravity driven and once through (as is the case in the above), the effect of addition of water soluble Polyacrylamide Polymer on drag reduction is expressed in terms of % reduction in efflux time. Based on the efflux time for different solutions, empirical equations for friction factor are developed. The concentration of Polymer which gives maximum drag reduction is also established.

Tribological studies on discontinuously reinforced aluminum composites based on the orthogonal arrays

Raviraj Shetty, R. Pai and S. S. Rao

The development of metal matrix composites with reinforced Aluminum composites (DRACs) represents a well-established method for improving the strength and stiffness of a material. When DRACs are being chosen for high volume and machine-intensive components, it is crucial that the tribological conditions during machining of the DRACs be understood since it is greatly different from aluminum alloys. The machinability of DRACs has been investigated actively worldwide since the 1980s, and most researchers have found that polycrystalline diamond (PCD) or cubic boron nitride tools can be used to machine DRACs effectively. Driven by the high cost of these tools, it is still desirable to optimize the cutting conditions, such as the effect of cutting fluid, since there has been no comprehensive study undertaken in this area. This paper reports on the experimental investigations carried out under dry, oil water emulsion and steam lubricated conditions in turning of DRACs. The experiments were planned on orthogonal arrays, made with prefixed cutting parameters and different lubricated conditions. An analysis of variance (ANOVA) was carried out to check the validity of the proposed parameters and also their percentage contributions. The results of the tests show that with proper selection of the range of cutting parameters, it is possible to obtain better performance under steam lubricated condition.