021770   Ratha D;Hari Prasad K S;Ojha C S P (Civil Engineering Dep, Indian Institute of Technology, Roorkee) : Finite volume model for the solution of the advection-dispersion equation. ISH J Hydraul Engng 2007, 13(2), 122-35.

The study is concerned with the modeling of conservative as well as non-conservative solute transport in ground water. The model is based on an operator split approach which uses an Eulerian frame work with finite volume method for the advective transport and fully implicit central difference method for the dispersive transport. This formulation helps in accurately simulating both highly advective and dispersive transport cases with less restriction on the grid size and time step. The numerical solution is compared with exact as well as the approximate analytical solution and the maximum error as percentage of peak concentration is presented for different values of decay constant at varying distances. It is found that finite volume method provides accurate solutions of both conservative and non-conservative solutes for both advection and dispersion dominated situations.

4 illus, 12 ref

021769   Ranganath B J;Prakash C P S (Mechanical Engineering Dep, Vidyavikas Institute of Engg & Technology, Mysore, Email: cpsprakash@hotmail.com) : Design of experiments method for optimization process parameters in WEDM. Ultra Scient phys Sci 2007, 19(2), 327-30.

Wire Electric Discharge Machining (WEDM) is a complex process controlled by a number of process parameters; hence selection of proper combination of parameters producing a quality surface with uniform kerf and increased metal removal rate (MRR) becomes very important. The study details the Design of Experiments technique in analyzing and predicting required process parameter values.

3 tables, 4 ref

021768   Rama kotaiah K;Srinivas J;Babu K J;Kolla S (Indl and Production Engg Dep, K.L. Coll of Engg, Vaddeswaram, Guntur (Dist), Andhra Pradesh, Email: krk_ipe@yahoo.co.in) : Analysis of regenerative chatter in turning. Mfg Technol Today 2007, 6(11), 35-40.

Effects of various cutting conditions (such as Velocity, Feed, Depth of cut), and tool geometry (such as Side Cutting Edge angle, Inclination angle, Rake angle), overhanging distance of work piece and over hanging distance of tool on regenerative chatter (Self excited vibrations) in turning process are presented. A low mass accelerometer is placed at the tool-tip of the assembly and the system exited at the same point by using an impulse hammer to obtain the tool-point frequency response function through spectrum analyzer or modal testing software. New test is peformed when tool-overhang length changes or for different combination of system components. Regarding the analytical aspects, have to obtain any model of cutting process. This paper also presents mathematical modelling for better understanding the relationship between various cutting conditions, cutting forces and vibrations in turning machines.

15 illus, 14 ref

021767   Rajaraman R;Velraj R (B S Abdur Rahman Crescent Engg, Coll Anna Univ, Chennai, Email: rajaraman_65@rediffmail.com) : Estimation of interfacial heat transfer coefficient by control volume technique during solidification of cylindrical aluminum aloy casting. Mfg Technol Today 2007, 6(12), 19-25.

Metal casting is one of the most important manufacturing methods. The quality of the casting is determined by the desirability of its microstructure and the absence of defects which in turn depends on the process of solidification. The solidification process is complex in nature and the simulation of the process is desirable to predict the quality of cast. Precise estimation of the interfacial heat transfer coefficient (IHTC) is essential for accurate simulation of the casting process. The present work estimates IHTC during solidification '"Of aluminum alloy casting of cylindrical geometry with the sand mold. The mold surface heat flux and temperature are estimated by inverse heat conduction method using control volume technique. The instantaneous cast temperature is measured experimentally and this value is used in the theoretical investigations. In the present technique, partial differential heat conduction equation is reduced to ordinary differential equations in time, which are then solved sequentially. The IHTCs at various time intervals are determined from the surface heat flux and the mold surface temperature.

5 illus, 9 ref

021766   Rai R K;Ojha C S P (Uttar Pradesh Irrigation Dep, State Water Resources Agency, Lucknow-226 026) : Estimating Dispersion coefficient from Soil-column test. ISH J Hydraul Engng 2007, 13(2), 1-14.

Tracer test in a soil column is one of the reliable techniques for the estimation of dispersion coefficient. In a tracer movement test, the exit concentration known as breakthrough curve with time is observed from known input in the form of step change in the concentration input. In the present paper, two methodologies viz., summation distribution graph and Z-transform of transfer function of the process have been proposed for the estimation of dispersion coefficient from the data on soil-column test. Application of the methodologies has been demonstrated on the published data. The results indicated that the proposed methods have better potential to estimate the dispersion coefficient with reliable accuracy. A summation distribution graph approach can easily perform on a simple scientific calculator whereas; later one needs linear optimization technique.

3 illus, 5 table, 13 ref

021765   Ojha C S P;ish F;Shankar V;Chauhan N S (Civil Engineering Dep, IIT Roorkee, Roorkee) : Analysis of flow over Horizontal transverse bottom racks. ISH J Hydraul Engng 2007, 13(2), 41-52.

A rack set in the bottom of a channel is often used as a hydraulic structure for intake or an outlet for flow. The flow through the bottom racks is a typical case of spatially varied flow with decreasing discharge. In the present work, experiments have been conducted to study flow diversion from transverse bar bottom rack under varying flow conditions i.e. Froude number ranging from 0.1 to 1.5 and ratio of transverse bar spacing to rack length ranging from 0.041 to 0.102. To study discharge characteristics, invariant specific energy assumption is utilized. The variation of Mostkow's discharge coefficient, which is based on invariance of specific energy along the bottom rack, is investigated with Froude number as well as bottom rack parameters. Existing functional forms of discharge coefficient variation in case of longitudinal bar bottom racks have been utilized to develop relationships for discharge coefficient variation in case of transverse bar bottom racks. Observed and computed values of discharges based on theses new functional relationships show good agreement. In some cases, where specific energy loss has been significant, these relationships do not work well.

7 illus, 2 table, 12 ref

021764   Navaneethakrishnan P;Srinivasan P S S; Dhandapani S (Mechanical Engineering Dep, Kongu Engineering College, Perundurai-638 052, Email: pnkmech@gmail.com) : Heat transfer and heating rate of food stuffs in commercial shop ovens. Sadhana 2007, 32(5), 535-44.

The CFD analysis of flow and temperature distribution in heating ovens used in bakery shop, to keep the foodstuffs warm, is attempted using finite element technique. The oven is modelled as a two-dimensional steady state natural convection heat transfer problem. Effects of heater location and total heat input on temperature uniformity of foodstuffs are studied. Placing the heater at the bottom of the oven improves the air circulation rate by 17 times and 10 times than that at the top and side of the oven. But the top location provides better uniformity in foodstuff temperature than the other cases. Side location is not preferable. In the present ovens, the heating elements are located at the top. The analysis shows that if heaters are located at the bottom along with additional flow guidance arrangements, energy efficient oven configuration can be obtained.

10 illus, 15 ref

021763   Mudgal S (BRCM College of Engineering and Technology, Behal, Bhiwani) : Love wave scattering due to an infinite rigid plane boundary. Ultra Scient phys Sci 2007, 19(3), 505-14.

The problem of scattering of Love waves due to an infinite rigid Plane Boundary in a surface layer lying over a solid half space is studied here. The rigid plane boundary lies along half of a slightly dissipative surface layer and the other half of the layer is a free surface. The reflected, transmitted and the waves scattered due to the strip have been obtained by using the Wiener-Hopf technique. The scattered waves propagate with the speed of the waves in the half space and not with that of the waves in the layer.

4 illus, 11 ref

021762   Mohamed Nazeer S;Murugan M;Rasool Mohideen S; Narasimma Moorthy Y V N (Mechanical Engg Dep, BSA Crescent Engg Coll, Chennai, Email: Smdnazeer@hotmail.com) : Effect of long cycle cryogenic treatment on mechanical properties of steel weldments. Mfg Technol Today 2007, 6(12), 12-18.

Cryogenic treatment is a process of treating materials, at temperatures well below 0°C to achieve improved mechanical properties. Cryogenic treatment was observed to enhance the mechanical properties of various materials like tool steels, bearing materials, carbon fiber composites and copper resistance welding electrodes. Application of cryogenic treatment as a post weld treatment to weldments is a new area to be studied. In the present investigation, 2.25 Cr 1 Mo low carbon low alloy 'steel weldments were cryogenically treated and their mechanical behavior evaluated. Changes in micro hardness, Charpy V notch toughness and changes in the microstructure were studied. The performance of as welded, tempered, long cycle cryogenic treated and tempered and long cycle cryogenic treated weldments were compared. J-integral as a measure of fracture toughness of the weldments was computed and compared. The long cycle cryogenic treatment was found to result is substantial increase in impact toughness with the marginal reduction in micro hardness. At the micro structural level, that formation of acicular ferrite, grain refinement and precipitation of alloying elements were found to be the basic mechanisms responsible for the increased impact toughness.

11 illus, 3 tables, 12 ref

021761   Lone M A (Civil Engineering Dep, National Institute of Technology, Srinagar, Jammu and Kashmir) : Significance of Coefficient of uniformity of bases on their filter design. ISH J Hydraul Engng 2007, 13(2), 31-40.

Filter tests for the bases of various gradations were carried out to study the effect of Coefficient of Uniformity of bases (Cu) on their filter design. Filters usually designed on the basis of d₈₅ (85% finer size of the base material) of a base prove conservative in most of the cases. The present study indicates that the filters designed on the basis of some other representative size d* of the base result in less conservative and more economical design of filters for a particular base. This size d*, which has been termed as design controlling usually size in the present study, does not only depend on d₈₅ size of the base but also on the coefficient of uniformity Cu of the base material, thereby taking into account almost overall gradation of the base material for filter design.

3 illus, 5 table, 12 ref

021760   Karakas E;Vardarbasi S (Kocaeli Univ, Technical Education Faculty, Electrical Education Dep, Kocaeli, Turkey, Email: karakas@kou.edu.tr) : Speed control of SR motor by self-tuning fuzzy PI controller with artificial neural network. Sadhana 2007, 32(5), 587-96.

The dynamic model, flux-current-rotor position and torque-current-rotor position Values of the switched reluctance motor (SRM) are obtained in MATLAB/Simulink. Motor control speed is achieved by self-tuning fuzzy PI (Proportional Integral) controller with artificial neural network tuning (NSTFPI). Performance of NSTFPI controller is compared with performance of fuzzy logic (FL) and fuzzy logic PI (FLPI) controllers in respect of rise time, settling time, overshoot and steady state error.

8 illus, 3 tables, 14 ref

021759   Helenprabha K;Natarajan A M (ECE Dep, Anna Univ, Kongu Engineering College, Perundurai, Erode-638 052, Email: helenprabha@yahoo.com) : FPGA implementation of gamma filter for extracting fetal electrocardiogram. IETE J Res 2007, 53(5), 433-40.

Fetal electrocardiogram (FECG) monitoring is a technique for obtaining important information about the condition of the fetus during pregnancy and labour. This technique is used for measuring electrical signals generated by the fetal heart as measured from multichannel potential recordings on the mother's body surface. Unfortunately, the desired fetal heart signals appear with undesirable disturbances. To extract FECG from the several contaminations, we propose a new class of adaptive filter that combines the attractive properties of Finite Impulse Response (FIR) filter with Infinite Impulse Response (IIR) filter. The Maternal ECG and Fetal ECG signals are simulated using MATLAB. The Gamma Filter design is implemented in FPGA Spartan 2E which was programmed using VHDL. This implementation has solved the complex situations more reliably than normal adaptive methods used earlier for recovering fetal signals.

12 illus, 8 ref

021758   Gupta R;Trivedi A (Electronics Engineering Dep, Madhav Institute of Technology and Science, Gwalior-474 005, Email: rekha652003@yahoo.com) : Pilot symbol assisted channel estimation techniques for OFDM systems. IETE J Res 2007, 53(5), 387-99.

Orthogonal frequency division multiplexing (OFDM) is a potential technique for transmitting high rate data over wireless channels. Satisfactory performance can be achieved by using coherent modulation techniques together with the channel estimation. For frequency selective fast fading channels, the task of channel estimation becomes quite challenging for an OFDM system because channel response appears unequal in both frequency and time domain. Therefore, an independent estimation of the channel is necessary at each of the subcarriers in each individual OFDM symbol. This article describes various pilot symbol assisted (PSA) channel estimation techniques. The Minimum mean square error (MMSE) channel estimation is superior in performance as it exploits prior information about the channel. Different models of MMSE estimator, which are based on different approximations of channel correlation matrix, are also discussed. Finally, a brief description of Kalman filter based estimation is presented for the situations where inter carrier interference (ICI) can not be neglected.

6 illus, 38 ref

021757   Girirajkumar S M;Sivaankar R;Jain R; Anantharaman N;Dharmalingam V (EWIE Dep, SEEE, SASTRA Univ, Thanjavur, Tamil Nadu, Email: smgirirajkumar@gmail.com) : Design of simulated annealing (SA) based optimal controller for a mechanical system. Mfg Technol Today 2007, 6(12), 34-41.

As part of control and automation Proportional-Integral-Derivative (PID) control schemes have been widely used in most of the control engineering applications including the field of mechanical engineering. A mechanical system's transfer function is considered for which a controller is designed using non-traditional optimization technique. The stability and performance of this mechanical system is greatly governed by the controller settings.

10 illus, 1 table, 21 ref

021756   Edwin Raja J;Kumanan S (Production Engng Dep, National Inst of Technol, Tiruchirapalli, Email: kumanan@nitt.edu) : Prediction of weld bead geometry in saw using regression method. Mfg Technol Today 2007, 6(11), 31-4.

Submerged Arc Welding (SAW) is a metal joining technique widely used in heavy fabrication industries due to its inherent properties. The welding quality and productivity is controlled by the process parameters. The process planners use different techniques to estimate the influence of the welding parameters (welding current, arc voltage, welding speed and electrode stickout) on bead geometry. Discusses about the design of experiments and the development of Multiregression model to predict the weld bead geometry. The developed model determines those variables which, will give the desired set of bead geometry (weld bead width, weld reinforcement, weld bead penetration, reinforcement area, and area of penetration and bead dilution.

3 illus, 3 tables, 16 ref

021755   Chaubey S;Joshi P;Manoj Kumar;Arya R;Nath A K;Kher S (Fibre Optics Lab, SSLD, Raja Ramanna Centre for Advanced Technology, Indor-450 213, Email: Kher@cat.ernet.in) : Disign and development of long-period grating sensors for temperature monitoring. Sadhana 2007, 32(5), 513-9.

Long Period Gratings (LPGs) have been developed using carbon dioxide laser in a standard optical fibre. LPGs with a periodicity of 600 μm and grating length of 24 mm have been inscribed on standard single mode fibre. Such gratings have been used in designing temperature sensors and temperature is monitored up to 80°C. The sensitivity of such type of sensor is 0.06 nm/°C where as for standard Fibre Bragg Grating (FBG) it is 0.011 nm/°C. The LPG performance is also evaluated after γ-ray irradiation for total dose of 5 KGy and has not shown any effect on transmission spectrum.

7 illus, 11 ref

021754   Biswal B;Dash P K;Panigrahi B K (Silicon Institute of Technology, Silicon Hills, Patia-751 024, Email: birendra@silicin.ac.in) : Time frequency analysis and non-stationary signal classification using PSO based fuzzy C-means algorithm. IETE J Res 2007, 53(5), 441-50.

Proposes a new approach for Time frequency analysis and non-stationary power signal classification using PSO based fuzzy C-means algorithm. Various non-stationary power signals like transient of different length (oscillatory transient), Voltage sag, Voltage swell, notches and impulsive transient are processed through S-transform to extract various features. The excellent time frequency resolution characteristic of the Generalized S-transform makes it an attractive candidate for analysis and detection of non-stationary signal. After feature extraction, the PSO (Particle Swarm Optimization) based Fuzzy C-means algorithm is used to cluster the extracted features to get the desired classification. The fuzzy C-means algorithm is then extended using particle swarm optimization algorithm to refine the cluster centers formed by fuzzy C-means algorithm. In the proposed work, the non-stationary power signals like oscillatory transient, impulsive transient, Voltage sag, Voltage swell, and notches have been considered for power signal classification.

18 illus, 8 ref

021753   Bhanu Prakashan Reddy N;Ish M;Ramakrishna Reddy M (Civil Engineering Dep, N.B.K.R. Institute of Science & Technology, Vidyanagar-524 413) : Efficiency of steady Non-uniform flow through Homogeneous porous media. ISH J Hydraul Engng 2007, 13(2), 53-65.

An experimental investigation on the effect of convergent flow on the linear and non-linear parameters for different ratios of radii of the test section in a converging permeameter was studied. The relationship relating friction factor and Reynolds number using the square root of intrinsic permeability as the characteristic length is examined for flow in porous media with converging boundaries. Using the friction factor (f_k) and Reynolds number (R_k) relationship, theoretical curves, which are similar to a Moody diagram used for pipe flow are developed and verified with the help of existing experimental data. In the present case, crushed rock of size 4.73 mm was used as media and water as fluid, to develop curves relating friction factor and Reynolds number with efficiency for different rate of flows of the test section of permeameter.

9 illus, 1 table, 10 ref

021752   Barve S B;Khodke P M (Mechanical Engg Dep, Bharati Vidyapeeth's Coll of Engg, C.B.D., Navi-Mumbai, Email: sbbarve@rediffmail.com) : Design of cellular manufacturing system for dynamic production requirements. Mfg Technol Today 2007, 6(11), 12-18.

Cellular Manufacturing System (CMS) provides great benefits as compared to traditional manufacturing systems. The design of cellular manufacturing systems is complex for real life problems. Existing design methods employ simplifying assumptions, which often deteriorate the validity of the models used for obtaining solutions. Assumption used in existing design methods is that product-mix and demand do not change over the planning horizon. The purpose of this study is to develop solution approach for designing cellular manufacturing systems for dynamic production requirements. The CMS model with dynamic production belongs to a class of NP-Complete problems that cannot be solved by traditional optimization methods. Thus, simulated annealing (SA) method is proposed to solve the problem. After discussing the method and presenting the model, it is applied on randomly generated problem based upon published data in the CMS design literature with two period planning horizons, to validate the efficacy of the algorithm so developed. The proposed model reduces total cost of CMS.

3 illus, 5 tables, 13 ref

021751   Arulselvi S;Govindarajan U (Instrumentation Engineering Dep, Annamalai Univ, Chidambaram, Tamilnadu-608 002, Email: arulselvi_2k3@yahoo.co.in) : Real-time implementation of modified fuzzy logic controller for a non-linear quasi-resonant DC-DC converter. IETE J Res 2007, 53(5), 401-16.

Describes the design and implementation of Modified Fuzzy Logic Controller (MFLC) for a non-linear quasi-resonant converter (QRC). It is shown that the two-dimensional rule table of conventional FLCs (CFLCs) used in power converters can be reduced to one-dimensional rule table using MFLC.The proposed MFLC reduces the memory space and computing time of the fuzzy algorithm. The tuning of scaling factors and the generation of fuzzy rules is also easier when compared with CFLC. As a result, realizing MFLC in a Microcontroller or Digital Signal Processor is made simple. The proposed controller structure is universal and it can be directly applied to any of the dc-dc converter topologies. The application of MFLC is successfully verified for the voltage control of Extended Period (EP)-ZCS/ZVS-QRC through simulation and experimental studies using TMS320F2407A Processor. The ability of MFLC compared to CFLC, to achieve good transient response for load variations and supply disturbances are demonstrated.

21 illus, 4 tables, 24 ref

021750   Ansari S A;Kothyari U C;Ranga Raju K G (Civil Engineering Dep, A.M.U., Aligarh) : Incipient motion characteristics of cohesive sediments. ISH J Hydraul Engng 2007, 13(2), 108-121.

Results of an experimental study on incipient motion characteristics of cohesive sediments are presented. Cohesive sediments used consisted of medium sand mixed with Illite clay in different proportions. Incipient motion condition of thus formed cohesive sediment bed was identified through visual observations. Antecedent moisture content, clay content, plasticity index and void ratio/dry density are found to be significant parameters affecting the incipient motion characteristics in these cohesive sediments. A functional relationship between shear stress for incipient motion and sediment characteristics has been proposed based on dimensional considerations which account for both the plastic as well as non-plastic sediments. An empirical relation is also proposed for computation of Critical Shear Stress (CST) with certain limitations related to the type of clay used for experimentation and other factors.

9 illus, 1 table, 18 ref

021749   Afzalimhr H;Dey S;Rasoulianfar P (Water Engineering Dep, Isfahan Univ of Technology, Isfahan, Iran, Email: hafzali@cc.iut.ac.ir) : Influence of decelerating flow on incipient motion of a gravel-bed stream. Sadhana 2007, 32(5), 545-59.

Experimental study on incipient motion of gravel-bed streams under steady-decelerating flow is presented. Experiments were carried out in a flume with two median grain sizes, d₅₀ = 16.7 mm for a fixed-bed case and d₅₀ = 8 mm for a mobile bed case. In addition, an effort is made to determine a simplified method for the estimation of bed shear stress in decelerating flow over fixed and mobile beds for use in field situations. From the observation of eleven fixed-bed and nine mobile-bed velocity profiles, it is revealed that the parabolic law method (PLM) and the Reynolds stress method are comparable for estimation of shear velocity in general. Also, the results show that the shear stress distribution adopts a convex form over fixed and mobile beds. Due to this form the critical Shields parameter value for decelerating flow is less than the reported values in literature. This paper supports Buffington & Montgomery (1997) statement that less emphasis should be given on choosing a universal shields parameter, and more emphasis should be given on choosing defendable values based on flow structure.

6 illus, 1 table, 54 ref

021748   Abani N;Bakshi S;Ravikrishna R V (Mechanical Engineering Dep, Indian Institute of Science, Banglore-560 012, Email: ravikris@mecheng.iisc.ernet.in) : Multi-dimensional modelling of spray, in-cylinder air motion and fuel-air mixing in a direct-injection engine. Sadhana 2007, 32(5), 597-617.

In this work, three-dimensional fuel-air mixing inside a conventional spark ignition engine cylinder is simulated under direct injection conditions. The motivation is to explore retrofitting of conventional engines for direct injection to take advantage of low emissions and high thermal efficiency of the direct injection concept. Fuel-air mixing is studied at different loads by developing and applying a model based on the Lagrangian-drop and Eulerian-fluid (LDEF) procedure for modelling the two-phase flow. The Taylor Analogy Breakup (TAB) model for modelling the hollow cone spray and appropriate models for droplet impingement, drag and evaporation are used. Moving boundary algorithm and two-way interaction between both phases are implemented. Fuel injection timing and quantity is varied with load. Results show that near-stoichiometric fuel-air ratio region is observed at different locations depending on the load. The model developed serves to predict the fuel-air mixing spatially and temporally, and hence is a useful tool in design and optimization of direct injection engines with regards to injector and spark plug locations. Simulations over a range of speed and load indicate the need for a novel ignition strategy involving dual spark plugs and also provide guidelines in deciding spark plug locations.

18 illus, 2 tables, 13 ref

020908   Zhou C R;Liu X Y (Information Material Science Dep and Engineering, Guilin Univ, of Electronic Technology, Guilin Guangxi-541 004, Email: zcr750320@yahoo.com.cn) : Dielectric properties and relaxation of Bi₀₁₅Na_0.5TiO₃-BaNb₂O₆ lead-free ceramics. Bull Mater Sci 2007, 30(6), 575-8.

A new member of lead-free piezoelectric ceramics of the BNT-based group, (1 - x)Bi_0.5Na_0.5TiO_3-x BaNb₂O₆, was prepared by conventional solid state reaction and its dielectric properties and relaxation was investigated. X-ray diffraction showed that BaNb₂O₆ diffused into the lattice of Bi_0.5Na_0.5TiO₃ to form a solid solution with perovskite-type structure. A diffuse character was proved by the linear fitting of the modified Curie-Weiss law. The temperature dependence of dielectric constant at different frequencies revealed that the solid solution exhibited relaxor characteristics different from classic relaxor ferroelectrics. The samples with x = 0.002 and 0.006 exhibited obvious relaxor characteristics near the low temperature dielectric abnormal peak, T_f, and the samples with x = 0.010 and 0.014 exhibited obvious relaxor characteristics between room temperature and T_f. The mechanism of relaxor behaviour was also discussed according to the macro-domain to micro-domain transition theory.

4 illus, 15 ref

020907   Tiwari G;Fazio J;Sushant S (Transportation Research and Injury Prevention Programme, Indian Insitute of Technology, Hauz Khas, New Delhi-110 016, Email: geetamt@gmail.com) : Traffic planning for non-homogeneous traffic. Sadhana 2007, 32(4), 309-28.

Traffic on Indian roads (both urban and inter-urban) consists of a variety of vehicles. These vehicles have widely different static and dynamic characteristics. The traffic is also very different from homogeneous traffic which primarily consists of motorized vehicles. Homogeneous traffic follows strict lane discipline as compared to non-homogeneous traffic. Western traffic planning methodologies mostly address the concerns of homogeneous traffic and therefore often prove inadequate in solving problems involving non-homogeneous traffic conditions as found in Indian cities. Presents studies conducted on non-homogeneous traffic. Section 1 presents a methodology to verify the continuity equation, the basic block of any traffic planning analysis. In  2, the methodology developed is applied to modify the Highway Capacity Manual (HCM) 2000 density method to derive passengercar equivalencies (PCEs) or units (PCUs) for heavy vehicles and recreational vehicles. These PCUs appear as 'ET' and 'ER' in HCM tables. The density method assumes motorized, four-wheeler traffic, i.e., homogeneous traffic, and does not include motorized three-wheelers, motorized two-wheelers, and non-motorized traffic often present on Indian highways. By modifying the density method to represent non-homogeneous traffic, which includes significant percentages of motorized, three-wheelers, motorized two-wheelers, and non-motorized traffic entities, one can derive more accurate passenger car units for Indian conditions. Transport professionals can use these PCU values for accurate capacity, safety, and operational analysis of highways carrying non-homogeneous traffic.

5 illus, 13 tables, 13 ref

020906   Thomas P;Sathpathy L N;Dwarakanath K;Varma K B R (Materials Research Centre, Indian Institute of Science, Bangalore-560 012, Email: kbrvarma@mrc.iisc.ernet.in) : Microwave synthesis and sintering characteristics of CaCu₃Ti₄O₁₂. Bull Mater Sci 2007, 30(6), 567-70.

CaCu₃Ti₄O₁₂ (CCTO) was synthesized and sintered by microwave processing at 2.45 GHz, 1.1 kW. The optimum calcination temperature using microwave heating was determined to be 950°C for 20 min to obtain cubic CCTO powders. The microwave processed powders were sintered to 94 density at 1000°C/60 min. The microstructural studies carried out on these ceramics revealed the grain size to be in the range 1-7 μm. The dielectric constants for the microwave sintered (1000°C/60 min) ceramics were found to vary from 11000-7700 in the 100 Hz-100 kHz frequency range. Interestingly the dielectric loss had lower values than those sintered by conventional sintering routes and decreases with increase in frequency.

5 illus, 32 ref

020905   Su B T;Wang K;Zuo X W;Mu H M;Dong N;Tong Y C; Bai J;Lei Z Q (Key Laboratory of Eco-Environment-Related Polymer Materials, , Ministry of Education of China, Email: sub0608@sina.com) : Facile synthesis of ZnO hollow fibres. Bull Mater Sci 2007, 30(6), 571-4.

Cotton fibres were used as bio-template to successfully synthesize new ceramic materials, ZnO hollow fibres and in an effort to explore the synthesis condition, and simplify the synthesis procedure. In this synthesis, a direct thermal decomposition of zinc acetate dihydrate coated on the surface of cotton fibres was explored. The wall porosity of the ZnO hollow fibres was controlled by changing the concentration of zinc acetate aqueous solution.

7 illus, 12 ref

020904   Senthil Kumar S;Planisamy V (Electrical Engineering Dep, Government College of Engineering, Salem) : Hybrid fuzzy dynamic programming approach to unit commitment. J Instn Engrs-Pt EL 2008, 88(Mar), 3-9.

A new approach using Fuzzy Dynamic Programming (FDP) is proposed for the unit commitment of a power system. The objective of the paper is to find the genera tor scheduling such that the total opera ting cost can be minimized, when subject to a variety of constraints. This method allows a qualitative description of the behaviour of a system, the system's characteristics and response without the need for exact mathematical formulations. It is demonstrated through numerical example that a fuzzy logic based approach achieves a logical and feasible economical cost of operation of the power system, which is the major objective of unit commitment. Conventional Dynamic Programming (DP) is a well known technique in operations research for solving optimization problems. Fuzzy logic has the capability to qualitatively represent the results in terms of input variables. With its two stage processing, the algorithm can benefit from the advantages of both the approaches. The Neyveli Thermal Power Station (NTPS) unit II in India has been considered as a case study and extensive studies have also been performed for different power systems consisting of 10, 20 and 26 generating units. The proposed approach to short term unit commitment achieves a reasonable opera ting cost and optimum stage for constrained power system. Numerical results obtained by FDP are compared with conventional methods like DP and Lagrangian Relaxation (LR) to reach proper unit commitment.

10 illus, 3 tables, 11 ref

020903   Sathe Vivek;Chidambaram M (Chemical Engineering Dep, Indian Institute of Technology Madras, Chennai-600 036, Email: chidam@iitm.ac.in) : Simultaneous relay auto tuning of series cascade controllers. Indian chem Engr 2007, 49(4), 324-29.

The paper is concerned with the relay auto tuning of a series cascade control system. Traditionally, auto tuning procedures for cascade controllers are applied using a sequential, one-loop-at-a-time method. Recently, Saraf et al. [1] have proposed a simultaneous method of relay tuning of series cascade control system. In this method, they have assumed the principle harmonic analysis of relay oscillations. This results in error in calculation of the ultimate gains. In the present work, the method of Srinivasan and Chidambaram [2], which considers higher order harmonics, is applied to a series cascade control of a stable system. Using improved ultimate gains the inner loop (PI) and outer loop (PID) controllers are designed by Ziegler-Nichols tuning method. The improved performance of the proposed series cascade control is compared with that of Saraf et al.

5 illus, 2 table, 8 ref

020902   Sarkar D;Modak J M (Chemical Engineering Dep, Indian Institute of Science, Bangalore-560 012, Email: modak@chemeng.iisc.ernet.in) : Dynamic reoptimisation of fed-batch bioreactors using genetic algorithms. Indian chem Engr 2007, 49(4), 375-91.

On-line reoptimisation of a bioprocess is a difficult task due to its complex, time-varying, nonlinear nature. The task is further complicated by the lack of suitable on-line sensors. Frequently, model errors due to the complex nature of bioprocesses require that kinetic model used in optimisation be reparameterised or updated on-line for effective control of fermentation processes. An on-line reoptimisation procedure based on an improved genetic algorithm approach in combination with state and parameter estimation is developed for the determination of substrate feed profiles for the optimal operation of fed-batch bioreactors. The problem specific knowledge generated through the rigorous application of the optimal control theory is used to formulate the set of decision variables representing the qualitative and quantitative aspects of the feed rate profile. An Extended Kalman Filter (EKF) is used to provide optimal estimates of the relevant state variables from readily available on-line process measurements and the model parameters are dynamically adjusted using a nonlinear programming approach over a moving window. The EKF also keeps track of the specific growth parameter to detect any change in the process. The efficiency of the proposed algorithm is demonstrated on a cell mass production problem under fed-batch operation.

11 illus, 37 ref

020901   Sai Srinadh K V;Singh N;Singh V (Metallurgical Engineering Dep, Institute of Technology, Banaras Hindu Univ, Varanasi-221 005, Email: vakil@bhu.ac.in) : Role of Ti₃Al/silicides on tensile properties of timetal 834 at various temperatures. Bull Mater Sci 2007, 30(6), 595-600.

Extremely fine coherent precipitates of ordered Ti₃Al and relatively coarse incoherent precipitates of S₂ silicide exist together in the near α-titanium alloy, Timetal 834, in the dual phase matrix of primary a and transformed β. In order to assess the role of these precipitates, three heat treatments viz. WQ, WQ-A and WQ-OA, were given to have no precipitates, Ti₃Al and silicide and only silicide precipitates in the respective conditions. Tensile properties in the above three heat treated conditions were determined at room temperature, 673 K and 873 K. It was observed that largely Ti₃Al precipitates were responsible for increase in the yield strength and decrease in ductility in this alloy.

4 illus, 2 tables, 12 ref

020900   Roy T K (NO, Indian National Academy of Engineering, New Delhi-110 016, Email: iichenrcdelhi@yahoo.com) : Sixty years of hydrometallurgy: still an exciting area of research. Indian chem Engr 2007, 49(4), 443-50.

Hydrometallurgy has now been established as a commercially proven technology for winning of metals like Ni, Co and cu as well as pure oxides of AI, U and Ti. In 1950s, a number of innovations were made in pressure leaching and hydrogen reduction, which led to the establishment of three Co and Ni refineries in USA, Canada and Cuba. By 1980, 40% of the world's nickel was produced by pressure hydrometallurgy. Currently, several new hydrometallurgy projects are in operation or under construction in Australia, New Caledonia and Madagascar. Pressure leaching of ores and concentrates and precipitation of pure metals or oxides from the leach solution avoid release of polluting and greenhouse gases to the atmosphere. But the technology is complex and requires skillful application of chemistry of metallic complexes and principles of reaction engineering, mass transfer, non-Newtonian fluid mechanics, crystallisation etc. A high degree of engineering expertise is also required for designing critical items of equipment and components. This paper emphasises that now the time is ripe for inventing and developing new hydrothermal process schemes for recovering metal values from a diversity of ores and concentrates.

4 illus, 9 ref, 1 table

020899   Pinnoji P K;Mahajan P (Transportation Research and Injury Prevention Programme, Indian Institute of Technology, Hauz Khas, New Delhi-110 016, Email: mahajan@am.iitd.ac.in) : Finite element modelling of helmeted head impact under frontal loading. Sadhana 2007, 32(4), 445-58.

Finite element models of the head and helmet were used to study contact forces during frontal impact of the head with a rigid surface. The finite element model of the head consists of skin, skull, cerebro-spinal fluid (CSF), brain, tentorium and falx. The finite element model of the helmet consists of shell and foam liner. The foam is taken as elasto-plastic, the brain is assumed to be viscoelastic and all other components are taken as elastic. The contact forces and coup pressures with helmet on the head are much lower than in the absence of the helmet. A parametric study was performed to investigate the effect of liner thickness and density on the contact forces, pressures and energy absorption during impact. For 4 ms^-1 velocity, expanded poly styrene (EPS) foam of density 24 kg m^-3 gave the lowest contact forces and for the velocities considered, thickness of the foam did not affect the contact forces.

19 illus, 3 tables, 11 ref

020898   Peric Grujic A A;Neskovic O M;Veljkovic M V; Lausevic Z V;Lausevic M D (Faculty of Technology and Metallurgy, Belgrade Univ, Karnegijeva 4, Belgrade, Serbia, Email: alexp@tmf.bg.ac.yu ) : Surface characterization of silver and palladium modified glassy carbon. Bull Mater Sci 2007, 30(6), 587-93.

The influence of silver and palladium on the surface of undoped, boron doped and phosphorus doped glassy carbon has been studied. The silver and palladium concentrations in solution, after metal deposition, were measured by atomic absorption spectrophotometer. The morphology of metal coatings was characterized by scanning electron microscopy. In order to investigate the nature and thermal stability of surface oxygen groups, temperature-programmed desorption method combined with mass spectrometric analyses, was performed. The results obtained have shown that silver and palladium spontaneously deposit from their salt solutions at the surface of glassy carbon samples. Silver deposits have dendrite structure, whilst palladium forms separate clusters. The highest amount of both silver and palladium deposits at the surface of sample containing the highest quantity of surface oxide complexes. It has been concluded that carboxyl groups and structure defects are responsible for metal reduction. Calculated desorption energies have shown that the surface modification by metal deposition leads to the formation of more stable surface of undoped and doped glassy carbon samples.

5 illus, 2 tables, 22 ref

020897   Mukherjee V;Ghoshal S P (Electrical Engineering Dep, Asansol Engineering College, Asansol, Dist: Burdwan) : Particle swarm optimization-genetic algorithm based fuzzy logic controller for dual input power system stabilizers. J Instn Engrs-Pt EL 2008, 88(Mar), 36-43.

Deals with the comparative performance study of optimal controls of three types of dual input power system stabilizers (PSSs) in a single-machine infinite bus (SMIB) system with the application of two varieties of particle swarm optimization (PSO), binary-coded genetic algorithm (GA) and Sugeno fuzzy logic (SFL). Each variety of PSO or GA is adopted for off-line, nominal optimization of stabilizer parameters under nominal system operating conditions. On real time measurements of system operating conditions, SFL adaptively and very fast yields on-line, off-nominal optimal stabilizer parameters. From simulation studies, it is found that the damping performance of generator's electromechanical mode of oscillations of PSS3B is the best and that of PSS4B is better than PSS2B but poorer than PSS3B. Both PSS4B and PSS3B yield robust dynamic performance over a wide range of system operating conditions for the particular SMIB system understudy. Moreover, by comparison of optimizing performances, PSO based algorithms prove to be better than GA.

9 ref

020896   Mukherjee S;Mohan D;Gawade T R (Transportation Research and Injury Prevention Programme, Indian Institute of Technology, Hauz Khas, New Delhi-110 016, Email: sudipto@me.iitd.ernet.in) : Three-wheeled scooter taxi: a safety analysis. Sadhana 2007, 32(4), 459-78.

The rollover propensity of a three-wheeled scooter taxi used extensively on SE Asian roads is analysed in this report. A rigid body mathematical model was used to simulate increasing steer, NHTSA J-turn, and Road Edge Recovery maneuvers. The anomaly between public perception of the rollover susceptibility and available crash data has been resolved through finite element (FE) simulation. The optimum configuration of the vehicle and seating arrangement for varying numbers of passengers was determined. The safety of occupants and pedestrians in impact events was analysed through simulation in MADYMO^T, and cost effective solutions to improve safety were identified.

12 illus, 4 tables, 18 ref

020895   Mukherjee S;Chawla A;Karthikeyan B;Soni A (Mechanical Engineering Dep, Indian Institute of Technology Delhi, New Delhi-110 016, Email: sudipto@mech.iitd.ernet.in) : Finite element crash simulations of the human body: passive and active muscle modelling. Sadhana 2007, 32(4), 409-26.

Conventional dummy based testing procedures suffer from known limitations. Addresses issues in finite element human body models in evaluating pedestrian and occupant crash safety measures, Review of material properties of soft tissues and characterization methods show'a scarcity of material properties for characterizing soft tissues in dynamic loading. Experiments imparting impacts to tissues and subsequent inverse finite element mapping to extract material properties are described. The effect of muscle activation due to voluntary and non-voluntary reflexes on injuries has been investigated through finite element modelling.

12 illus, 1 tables, 90 ref

020894   Mukherjee S (NO, Lurgi India Co. Pvt. Ltd., A-30 Mohan Cooperative Industrial Estate, Mathura Road, New Delhi-110 044, Email: siddhartha.mukherjee@lurgi.com) : Debottlenecking a distillation column for capacity augmentation. Indian chem Engr 2007, 49(4), 514-25.

Discusses various ways of revamping a distillation column and its implications. First, the tray geometry and hydraulic parameters in a distillation column are discussed. The tray active area, downcomer area, weir height, crest height, dry and wet tray pressure drops are illustratively described. Next, the definitions of various other terms associated with tray hydraulics are defined. These parameters include downcomer back up, downcomer flood, jet flood, weir height, downcomer clearance, downcomer chord height etc. Three typical debottlenecking cases are discussed. In Case 1, the column is debottlenecked by just increasing the number of valves. In the other two cases, first the number and type of valves had to be changed. Interestingly, in Case 2 while the downcomer chord height had to be increased, in Case 3 the chord height had to be decreased to meet all the hydrodynamic criterion. More complicated cases are touched upon, where both liquid and vapour loads are high and more expensive methods have to be adopted.

4 illus, 2 ref, 3 table

020893   Maiti R N;Khanna R;Nigam K D P (Chemical Engineering, Indian Institute of Technology Delhi, New Delhi-100 016, Email: drkpdn@gmail.com) : Pinning effect of saturated pores on liquid spreading. Indian chem Engr 2007, 49(4), 413-20.

Experimental study of the pinning effect of pores in liquid spreading on porous surface is presented based on spreading of microlitre-sized liquid drops on substrate that have millimetre-sized pores to improve the present understanding of wetting. The liquid drops were put on pores and nonporous parts of solid substrate in horizontal position and then the substrate was rotated in the vertical plane. The inclinations, from the horizontal, at which the drops started to runoff, were noted from the display of the rotator. To study the effect of different parameters on the pinning effect, the experiments were performed with different sizes of pore, volumes of liquid drop and types of liquid. It was observed that the force required to runoff the liquid drop sitting on pores i.e. pinning force is higher than drop on nonporous part. It increases with the increase of the surface tension of the liquid and less prominently with the diameter of the pore. A factor 'f' similar to the correction factor in drop weight method of measuring surface tension is determined to predict the pinning force and correlated with the drop size and diameter of pore. It is expected that this pore level analysis of liquid spreading will help in increasing the understanding of liquid spreading behaviour in various fundamental and technological scenarios where liquid-solid contact line is required to move over porous surface.

4 illus, 27 ref

020892   Mackay M (Mull House, Ballagarrett, Bride, Isle of Mann, IM7 BEA, Email: mmackay@netcomuk.co.uk) : Increasing importance of the biomechanics of impact trauma. Sadhana 2007, 32(4), 397-408.

The evolution of experimental biomechanics and crash injury research is summarized briefly to show that they both play a major role in mitigating traffic deaths and injuries. Historically, the subject has been based largely in western countries and thus focused on vehicle occupants, whereas some 80% of traffic casualties in the world are outside the vehicle as pedestrians, cyclists and motorcyclists. The subject is close to the regulatory process which controls vehicle design and is thus heavily influenced by government and industry, yet it is now in an expanding period because of new techniques to replicate the human frame's response to impact forces. New knowledge is likely to emerge from addressing population variations and combining real world accident investigations with experimental biomechanics. The application of impact biomechanics to the vulnerable road users is of particular importance.

4 illus, 1 table, 31 ref

020891   Liu X Y;Zhou C R;Shan Z H (School of Material Science and Engineering, Central South Univ, Changsha Hunan 410083 China, Email: zcr750320@yahoo.com.cn) : Depolarication temperature and piezoelectric properties of Na_1/2Bi_1/2TiO₃-Na_1/2Bi_1/2(Zn _1/3Nb_2/3)O₃ ceramics by two-stage calcination method. Bull Mater Sci 2007, 30(6), 579-81.

A new group of NBT-based lead-free piezoelectric ceramics, Na_1/2Bi_1/2TiO₃-Na_1/2Bi_1/2Zn_1/3Nb2/3)O₃, was synthesized using the two-stage calcination method and depolarization temperatures and piezoelectric properties were also investigated. The XRD analysis showed that the ceramics system had a morphotropic phase boundary (MPB) between the rhombohedral and the tetragonal structure. The highest piezoelectric properties of d₃₃ = 97 pC/N and k_t = 0.46 were obtained near MPB compositions. Furthermore, the depolarization temperatures near MPB compositions were slightly decreased and the lowest T_d was maintained at 210°C.

6 illus, 10 ref

020890   Kumar N;Ibraheem;Agarwal S K (Electrical Dep Engineering, Delhi College of Engineering, Delhi) : A SVS control strategy to damp torsional electromechanical oscillations in a series compensated power system. J Instn Engrs-Pt EL 2008, 88(Mar), 16-21.

Presents a control strategy for static VAR system (SVS) to damp out the torsimal electromechanical oscillations in a series compensated power system. The control strategy include, the damping effect of combined active and reactive power (CARP) auxiliary signals incorporated in the SVS located at the middle of the transmission line. The proposed control strategy has been validated using IEEE first benchmark model. The digital simulation, using a non-linear system model, has been ca sried out. The simulation results exhibit a remarkable improvement in the system transient performance and the Torsional electromechanical oscillations are effectively damped out. The control strategy is easily implemental as it utilizes the locally derived signals from the SVS bus.

8 illus, 14 ref

020889   Koornstra M (Insight Consult, Langeweg 70, NL-2371-EJ, Roelofarendsveen, The Netherlands, Email: matthijs.koornstra@insightconuslt.nl) : Prediction of traffic fatalities and prospects for mobility becoming sustainable-safe. Sadhana 2007, 32(4), 365-95.

The macroscopic trend of road traffic fatalities in any motorized country is described and predicted by the product of rather well fitting functions of time for the exponential decay of fatality risk per unit of traffic volume and the S-shaped Gompertz function of traffic volume growth. This product defines a single-peaked development of road traffic deaths, where its peak reaches earlier the sooner and faster a nation or region motorizes massively. Since in developing countries long series of traffic volume data are absent, another model for the fit and prediction of road traffic fatalities for developing countries is used, based on the relationships of income level per capita with road traffic mortality. Also this model implies that at some point in time road traffic deaths will start declining for ever, also worldwide. After empirically derived corrections for missing or incomplete data and police under-reporting, it is estimated that 1.2 million deaths and almost 8 million serious injuries are caused by road traffic worldwide in 2000. Using realistic income level predictions the new income-dependent model predicts markedly later and higher fatality peaks than the verified time-dependent model. It might be assumed that the developing countries could learn faster to increase their road safety by knowledge transfer from developed countries. Four prediction scenarios are specified for modified income-dependent models of road traffic death and serious injury developments up to 2050. Depending on the scenario the world total of road fatalities begins to reduce soon or only after 2035 with a global peak of about 1.8 million road traffic deaths, where the national fatality reduction starts later the lower the national income per capita is. Without the potentially achievable learning scenario the road fatality reductions in developed countries may not be enough to compensate the road fatality increases in developing countries, while road fatality increases may even occur after 2060 in countries with the lowest levels of income per capita.

21 illus, 9 tables, 31 ref

020888   Knoflacher H (Institute for Transport Planning and Traffic Engineering, Univ of Technology, Vienna A-1040, Email: hermann.knoflacher@ivv.tuwien.ac.at) : Success and failures in urban transport planning in Europe-understanding the transport system. Sadhana 2007, 32(4), 293-307.

Technological determinism has become a kind of religion for many people since it appears to offer solutions for societal problems as never before in history. Transport is one of the fascinating technology branches developed during the last 200 years. Effortless movement over long distances has become possible for car users as long as cheap fossil energy is available. However, the effect of fast transport on urban structures and society was not taken into account when developing these technical means. Technologists and economists have used indicators for expected benefits of these fast transport modes without taking into account the real system effects on society and urban structures. Plausible assumptions and hopes instead of scientific understanding of the complex system are used in practice. In contradiction to widely held beliefs of transportation planners, there is actually no growth of mobility if counted in number of trips per person per day, no time saving by increasing speed in the system, and no real freedom of modal choice. Modal choice is dependent on physical and other structures, the artificial environment built by urban planners, transport experts and political decisions. The core hypothesis of traditional urban and transport planning 'growth of mobility', 'travel time saving by increasing speed' and 'freedom of modal choice' are myths and do not exist in the real urban and transport system. This is the reason why urban planning and transport planning based on traditional non-scientific assumptions is creating continuously not only more transport problems, but also environmental and social as well as economic problems all over the world, where these principals are applied. Urban transport planning in Europe, understanding the transport system and the solutions are presented

16 illus, 1 table, 15 ref

020887   Khilar K C;Sarkar D;Tikku S (Chemical Engineering Dep, Indian Institute of Technology Bombay, Powai, Mumbai-400 076, Email: kartic@iitb.ac.in) : Preparation of engineered nano particles. Indian chem Engr 2007, 49(4), 469-79.

Presents review of the work in the field of nano particle synthesis. authors have used water in oil microemulsions for preparation of core and core/shell nano particles. The preparation and various characterisation techniques used to characterise these core and core-shell nano particles as well as findings on the effects of various process parameters on the terminal particle sizes are reviewed in brief. A brief review of our modelling work based on stochastic population balance, which can be used to describe the formation of both core and core-shell nano particles, is also presented. The results of our ongoing work on metal nanoclusters are also included. We are also currently working on some engineering issues such as possibility of reuse of surfactant and organic phases and some results are presented.

^iia10 illus, 23 ref

020886   Kale S R;Veeravalli S V;Punekar H D;Yelmule M M (GE India Technology Centre, Bangalore, 560 066, Email: srk@mech.iitd.ernet.in) : Air flow through a non-airconditioned bus with open windows. Sadhana 2007, 32(4), 347-63.

Open window buses without air-conditioning are a major mode of urban and inter-city transport in most countries. High occupancy combined with hot and humid conditions makes travel in these buses quite uncomfortable. In this study air flow through a bus has been studied that could be the basis for low cost and eco-friendly methods of increasing passenger comfort and possibly reduce drag. The aerodynamics of such a road vehicle has not been studied as previous investigations have been confined to vehicles with closed windows that present a smooth exterior to air flow. Using a 1:25 scaled Perspex model of an urban bus in Delhi, flow visualization was performed in a water channel. The Reynolds numbers were one-tenth of a real bus moving at 10 m/s. Smoke and tuft visualizations were also performed on an urban bus at 40 km/h. Numerical simulations were performed at the actual Reynolds number. Even though there were Reynolds number differences, the broad features were similar. Air enters the bus from the rear windows, moves to the front (relative to the bus) and exits from the front windows. Inside air velocity relative to the bus is about one-tenth of the free-stream velocity. The flow is highly three-dimensional and unsteady.

11 illus, 8 ref

020885   Gouranlou F (Material Sciecne Dep, Malek Ashtar Univ of Technology Lavizan, Tehran, Iran, Email: farideh47@yahoo.com) : Anti-corrosive coating prepared from hydroxy terminated polybutadiene. Asian J Chem 2007, 19(2), 1645-7.

Hydroxyterminated polybutadiene coaling has good properties as strong adhesion, resistance against bases and dilute acids, sally water, and solvents. The coating also has insulating properties against electricity and use to varnish coating.

1 table, 6 ref

020884   Dhage S R;Ravi V;Yang O B (School, of Environmental and Chemical Engineering, Chonbuk National Univ, Jeonju-561-756, South Korea, Email: sanjay.dhage@gmail.com) : Low voltage varistor ceramics based on SnO₂. Bull Mater Sci 2007, 30(6), 583-6.

The nonlinear current (I)-voltage (V) characteristics of tin dioxide doped with either Nb₂O₅ and CoO or Sb₂O₃ and CoO show promising values of nonlinear coefficient (α) values (-11) with low breakdown voltages (E_B, <126>40 V mm^-1). The pentavalent antimony or niobium acts as donor and increases the electronic conductivity. The crucial parameter for obtaining low breakdown voltage is the grain size, which depends upon sintering duration and temperature of these oxide ceramics.

4 illus, 15 ref

020883   Das C;Dasgupta S;Sirshendu De (Chemical Engineering Dep, Indian Institute of Technology Kharagpur, Kharagpur-721 302, Email: sde@che.iitkgp.ernet.in) : Quantification of gel layer resistance during single- and multi-component micellar-enhanced cross flow ultrafiltration. Indian chem Engr 2007, 49(4), 341-50.

Quantification of gel layer resistance during micellar-enhanced ultrafiltration (MEUF) of single- and multi-component solute system was studied using micelles of sodium dodecyl sulfate. Single solute system was studied using three solutes - copper, calcium and beta naphthol. Multi-component solute system was studied using binary mixture of copper-calcium and copper-beta naphthol. An organic polyamide membrane of molecular weight cut-off 5 kDa was used in cross flow MEUF experiments. The effects of feed composition, transmembrane pressure drop and cross flow rate on the gel layer resistance were studied. For single solute systems, the gel layer resistance was in the range of 71-75% of the total resistance for copper whereas it was 67-71% for calcium. For beta naphthol, it was 54-58% of the total resistance. For all the systems, more than 90% of solute separation was achieved.

7 illus, 3 table, 17 ref

020882   Choudhury A B;Roy D;Abe K (Electrical Engineering Dep, Bengal Engineering and Science Univ, Shibpur, Howrah) : Investigation of the performance of a passive magnetic fault current limiter. J Instn Engrs-Pt EL 2008, 88(Mar), 32-5.

A magnetic fault current limiter (FCL) is a passive device consisting of a permanent magnet and saturable magnetic cores. The performance of FCL primarily depends on the type and characteristics of the magnetic material as well as on the geometry and configuration of the FCL assembly. This paper aims to highlight the performance of FCL under varying parametric conditions.

8 illus, 6 ref