021234   Yadav T P;Mukhopadhyay N K;Tiwari R S; Srivastava O N (Dep of Phys, Banaras Hindu Univ, Varanasi-220 005, Email: mukho_nk@rediffmail.com) : On the evolution of a nanocrystalline phase from the Al-Cu-Fe quasicrystalline alloy during high energy ball milling. Trans Indian Inst Metals 2005, 58(6), 1169-76.

Mechanical milling of an Al-Cu-Fe quasicrystalline alloy was performed in a high energy ball mill (Szegvari attritor mill) at a constant speed of 400 rpm for various milling time (from 0.5 to 40 h) under liquid hexane medium with a ball to powder ratio of 40:1. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and x-ray diffraction (XRD) techniques were employed for characterizing the milled and unmilled samples. The evolution of nanocrystalline (NC) phase (bcc, a =0.29 nm) was observed from the quasicrystalline phase after 5h of milling. This nanocrystalline phase, which was quite stable up to 40h of milling, did not transform to amorphous or any other metastable phase. The size of crystalline particles was found to vary from 60nm to minimum 10nm for different milling durations. It is interesting to note that the strain induced in the milled samples tends to increase along with milling time. The possible mechanisms for the formation of nanocrystalline phase will be put forward based on the evolution of the structural and microstructural features.

ia6 illus, 33 ref

021233   Valiev R Z;Alexandrov I V (Inst of Phys of Advd Mater, Ufa St Aviat Tech Univ, K.marx St.12, 450000, Ufa Russia, Email: rzvaliev@mail.rb.ru) : Bulk nanometals produced by severe plastic deformation. Trans Indian Inst Metals 2005, 58(6), 1003-16.

Bulk nanostructured metallic materials, produced by the severe plastic defermation (SPD) methodhave been discussed. It has been successfully demonstrated that as a result of application of very large strains e<62>10, realized at relatively low temperatures under high imposed pressures of several GPa in different metallic materials, nanostructured states in bulk billets are being formed. Under certain conditions (predominantly high angle gain boundaries, structure homogeneity) the formed nanostructured states possess unique physical and mechanical properties, in particular, simultaneous appearance of high strength and ductility (SPD paradox), low temperature and/or high rate superplasticity, etc.

11 illus, 2 tables, 46 ref

021232   Ruikar S S (Kishor Pumps pvt. Ltd., , Pune-411 005) : Energy conservation in high-temperature sulphuric acid plants. Indian Pumps 2005, 37(4), 11-14.

2 illus, 1 table

021231   Ruhil A P; (Computer Cent, NDRI, Karnal-132 001, Email: anandpruhil@yahoo.com) : Effects of location update schemes on the performance of position based routing protocols in mobile ad hoc networks. IETE J Res 2006, 52(2-3), 169-76.

Number of position based routing algorithms for mobile ad hoc networks have been proposed in the literature. These algorithms have been tested either in proactive or reactive environment. Evaluated the performance of VD-GEDIR, CH-MFR, R-DIR, DREAM and LAR under both proactive and reactive routing approaches using different location update schemes. In proactive approach the location of a moving node is update independent of routing process i.e. based on regular time interval and based on number of links formed and broken while in reactive approach the locations updates are integrated with route discovery process. Through the simulation results it was found that VD-GEDIR, CH-MFR and R-DIR have performed better than DREAM and LAR under all the location update schemes applied in this work.

10 illus, 1 table, 10 ref

021230   Ramya T A;Vaidehi V;Ramesh C;Srinivasan R; Swetha B (Electron Dep Madras Inst of Technol Campus, Anna Univ, Chennai-600 044, Email: vaidehi@mitindia.edu) : Software design of CDMA based MAC scheme for microsatellite. IETE J Res 2006, 52(2-3), 113-19.

CDMA (Code Division Multiple Access) technology allows many users to access the medium concurrently. The store and forward (S&F) payload is to provide message relay service for terrestrial users with simple ground terminals. The widespread method of MAC (Medium Access Control) in S&F payload is ALOHA and it has poor channel throughput efficiency. This can be improved using CDMA based MAC. Two methods of code assignment namely, static & dynamic are considered. Their design methodologies and corresponding performance measures are discussed. The performance of the proposed CDMA MAC is compared with the existing ALOHA MAC and the results are presented.

8 illus, 2 tables, 10 ref

021229   Raju N;Suresh S (Weld Res Inst, BHEL, Tiruchirappalli-620 014) : Stress analysis on a retrofitted externally loaded pressure vessel. WRI Jl 2005, 26(4), 18-24.

A pressure vessel is usually designed based on the guidelines prescribed as per relevant codes of construction such as ASME Sec. VIII, BS 5500 Part I etc. Often designers encounter instances where the computation of peak stresses may not be possible with a desirable level of accuracy. Or whenever there is an extensive repair or retrofitting in the vessel experimental deformation analysis needs to be carried out, to ensure safety and integrity of the pressure vessel. This would enable to know the maximum deformation and stress levels in the repaired regions. This test is generally called as Proof Testing. Standard hydrostatic test is performed as a routine test while fabricating pressure vessels that are subjected to high pressure during service. This is carried-out to ensure leak proofness of the weld seams and other joints including gas cut joints and to measure the degree of permanent visible distortion when the vessel is subjected to hydrostatic testing at test pressure. Most of this hydro testing is done either by pressurizing the vessel from inside or by external means. The proof test involves installation of strain gauge transducer at critical locations of the pressure vessel and measurement of strains during hydro testing at different pressures of the pressure cycle or loading the vessel externally by hydro pressure. From the measured strains or deformation, the maximum stresses are computed using the standard relationship and bulk elastic constants of the material. The experimental stress analysis using strain gauges enables assessment of the adequacy of the retrofitted regions of the pressure vessel through the assessment of stress concentration zones, the peak stress areas, stress gradients and the residual strain in the pressure part. The nature, methodology and the results obtained while conducting experimental stress analysis in an externally loaded pressure vessle has been described.

3 illus, 2 tables, 4 ref

021228   Rajamohan N;Karthikeyan C (20/4 Theradi Pillayar Koil Street, , Chidambaram-608 001, Email: natrajmohan@yahoo.com) : Effect of operating parameters on aerobic treatment of dyehouse effluent by Galactomyces geotrichum. Ecol Envir Conserv 2005, 11(3-4), 487-90.

Dyehouse effluent treatment has became inevitable because of dyes, which originate from carcinogenic chemicals like benzidine. Galactomyces geotrichum was employed to degrade the dyehouse effluent under aerobic conditions. Effects of operating parameters such as concentration of the effluent, concentrations of glucose, pH of the effluent and concentration of peptone on percentage COD removal was determined. The fungi exhibited better COD removal efficiency under optimal glucose dosage of 5.0 g/L. The optimal pH range for better fungal activity was found to be 6-8. The fungi showed better COD removal efficiency under nitrogen limited environment with a peptone concentration of 5.0 g/L.

4 illius, 14 ref

021227   Paxal V M;Wien T;Thonstad H;Lexow H P (NO, Nera Broadband Satellite and Nera SatCom, Bergerveien 12, N-1375 Billingstad, Norway, Email: vp@satcom.nera.no) : DVB-RCS for mobile satellite applications. IETE J Res 2006, 52(2-3), 87-96.

Interactive services via satellite based on the open standard DVB-RCS are about to reach new markets. Initially standardised and developed for fixed services, the DVB-RCS equipment has become an interesting option also for mobile use. However, orienting the products towards the mobile market demands adjustments and special attention to new challenges. These new challenges are linked to positioning, line-up, tracking, power control, shadowing, Doppler effect and service provisioning. In addition come new environmental requirements as mobile terminals are subject to rougher conditions concerning shocks, vibration, extreme temperatures, dust and humidity. The environmental requirements has not be addressed in the paper. Use of DVB-RCS for mobile services is also a topic on the agenda in the DVB-RCS Forum, where a new appendix to the specification is currently being edited.

6 illus, 8 ref

021226   Padmanaban K (Weld Res Inst, BHEL, Tiruchirappalli-620 014) : Cored wires for hard facing. WRI Jl 2005, 26(4), 5-10.

Surfacing is an important aspect in material selection that would help to substantially improve the service life of the component working in operating environments incorporating different wear mechanisms. The severity of the operating environment and the wear resistance of the material of the component would determine the rate of material loss from the operating surface. Material with suitable wear resistant characteristics deposited on the operating surface by welding could reduce the loss of material from the component substantially, leading to the high improvement in the performance of the component. A very popular form filler wire used for hard facing of industrial components is continuous cored wire. An overview of the cored wires, wear types and the alloys employed for hard facing has been given.

1 illus, 5 ref

021225   Padalkar R G (Kirloskar Brothers Limited, , Pune) : Energy saving opportunities in industrial and agricultural pumps. Indian Pumps 2005, 37(4), 30-7.

13 illus, 1 table

021224   Onel I Y;Dalci K B;Senol I (Electrical-Electronics Fac Electl Engng, Yildiz Tech Univ, 34349 Besiktas-Istanbul, Turkey, Email: ionel@yildiz.edu.tr) : Detection of outer raceway bearing defects in small induction motors using stator current analysis. Sadhana 2005, 30(6), 713-22.

The application of induction motor stator current spacetral analaysis (MCSA) for detection of rolling element bearing damage from the outer raceway has been investigated. In this work, MCSA and vibration analysis are applied to induction motor to detect outer raceway defects in faulty bearings. Data acquisition, recording, and fast fourier transform (FFT) algorithms are done by using the Lab View programming language. Experimental results verify the relatonship between vibration analysis and MCSA, and identify the presence of outer raceway bearing defects in induction machines. This work also indicates that detecting fault frequencies by motor currents is more difficult than detecting them by vibration analysis. The use of intensive resolution FFT is recommended in MCSA for detecting faults easily. Reinstalling a faulty bearing can alter the characteristic frequencies and it is difficult to compare results from different bearings or even from the same bearing in different installations.

7 illus, 2 tables, 12 ref

021223   Murugan K; (Ramanujan Computing Cent, Anna Univ, Chennai-600 025, Email: murugan@annauniv.edu) : Performance study and effects of route caching mechanisms in on-demand routing algorithms for MANET. IETE J Res 2006, 52(2-3), 153-67.

Route caching strategy is an important part of any on-demand routing protocols to influence performance of wireless networks. Performance metrics like overhead and delay were found to vary with utilisation levels of route cache for protocols like Dynamic Source Routing (DSR) and Highest Energy Routing (HER). Hence, variations to these protocols have been presented in the paper to improve reliability of service and reduce the effects of cache staleness and network partitions. The variation is with respect to identification of route and cache validation of errors using different techniques namely Update Route Caching (URC), Temporal Cache Validation (TCV), Negative Cache Validation (NCV) and combined cache validation (CCV). These techniques refresh cache more often than the DSR and HER thereby initiating route requests earlier, when a route still being used is broken, thus reducing peer-to-peer delay to transmit packets. The results of GloMoSim simulator validates higher cache hit percentage and reliable delivery of packets in the technique Combined Cache Validation (CCV) when in comparison to DSR and HER.

26 illus, 10 ref

021222   Murty B S;Hono K (Dep of Metall and Mater Engng, Indian Inst of Technol Madras, Chennai-600 036, Email: murty@iitm.ac.in) : Understanding nanoquasicrystalline phase formation in Zr based alloys. Trans Indian Inst Metals 2005, 58(6), 1213-27.

Nano icosahedral phase formation was observed in a number of Zr-based metallic glasses. The present understanding on the nanoquasicrystalline phase formation in Zr-based alloys has been reviewed. The results indicate that oxygen stabilizes quasicrystalline phase. A large negative enthalpy of mixing and / or existence of Frank-Kasper-type phases.

ia19 illus, 30 ref

021221   Mukhopadhyay S M;Joshi P;Pulikollu R V (Mechanical & Mater Engng, Wright St Univ, Dayton, OH45435, Email: smukhopawright.edu) : Surface engineering issues in nanomaterials. Trans Indian Inst Metals 2005, 58(6), 1017-26.

In the paper some aspects of effective nano-meter scale coatings have been discussed. Since these are deposited by nonline of sight (plasma) techniques, they are capable of modifying nano-fibers, near net shape cellular foams, and other high porosity materials. Two type of coatings will be focused upon: (i) those that make the surface inert and (ii) those designed to enhance surface reactivity and bonding. The former has been achieved by forming 1-2 nm layer of -CF₂- (and/or CF₃) groups on the surface, and the latter by creating a nano-layer of SiO₂-type compound. Nucleation and growth study of these coatings at the initial stages of formation are performed on model single-crystal surfaces of silicon, sapphire and graphite. It is seen that these coatings completely cover the surface of all these materials within a 3-4 nm coating thickness, and are fully functional by then. They are therefore applicable to nano-structural solids. The effectiveness of these coatings in engineering applications is investigated by applying them on carbon nanofibers and micro-cellular foam structures. Coated and uncoated carbon structures are infiltrated with epoxy matrix to form composites and their mechanical behaviours are compared. Carbon nanofibers are also dispersed in an organic medium, and the influence of coating on their dispersion behavior is investigated by electron microscopy. In addition, the influence of these nano-films on graphite-metal interfaces is studied with the idea od understanding their applicability to metl matrix composites. The oxide coating is seen to provide significant improvement in epoxy-carbon and metal-carbon bond formation, thereby improving composite behavior. The fluorocarbon coating is seen to work as a deterrent to bond formation, and therefore may be used as a passivating layer on nanomaterials.h the idea of understanding their applicability to metal matrix composites. The oxide coating is seen to provide significant improvement in epoxy-carbon and metal-carbon bond formation, thereby improving composite behavior. The fluorocarbon coating is seen to work as a deterrent to bond formation, and therefore may be used as a passivating layer no nanomaterials.

11 illus, 1 table, 36 ref

021220   Mitra R;Ungar T;Weertman J R (Dep of Metall and Mater Engng, Indian Inst of Technol, Kharagpur-721 302, Email: rahul@metal.iitkgp.ernet.in) : Comparison of grain size measurements by x-ray diffraction and transmission electron microscopy methods. Trans Indian Inst Metals 2005, 58(6), 1125-32.

Grain sizes were measured in bulk nanocrystalline copper processed by inert gas condensation and compaction, using X-ray diffraction (XRD) and transmission electron microscopy (TEM) methods. The XRD peaks were analyzed using the Warren-A verbach, integral breadth and Williamson-Hall methods, modified to include the contributions of dislocations to peak broadening. Analysis using full-width half-maximum values provided the largest average grain sizes, while analyses of integral breadth and Fourier coefficients of XRD peak profiles gave the medium and smallest average grain sizes, respectively. A significant increase in the mean grain size accompanied by broadening of the grain size distribution could be observed upon increasing the temperature of compaction of nano-powders from 69°C (342 K = 0.25TM) to 180°C (453 K = 0.34TM) or after a six-month exposure of samples to ambient temperatures (TM is the absolute temperature of melting). Grain size distributions, obtained by direct measurement of the dimensions of ~500 grains per sample using bright and dark field transmission electron microscopy, were found to obey a log normal relationship. The TEM results agreed well with those of XRD measurements for narrow grain size distributions with smaller mean values, but they deviated significantly when the mean grain size increased and distributions widened, indicating that the information from XRD analyses could be misleading.

8 illus, 24 ref

021219   Mercimek M;Gulez K;Mumcu T V (Electrical-Electreonics Fac Electl Engng Dep, Yildiz Tech Univ, 34349 Besiktas-Istanbul, Turkey, Email: mercimek@yildiz.edu.tr) : Real object recognition using moment invariants. Sadhana 2005, 30(6), 765-75.

Moments and functions of moments have been extensively employed as invariant global features of images in pattern recognition. In this study, a flexible recognition system that can compute the good features for high classification of 3-D real objects is investigated. For object recognition, regardless of orientation, size and position, feature vectors are computed with the help of nonlinear moment invariant functions. Representations of objects using two-dimensional images that are taken from different angles of view are the main features leading to the objective of study. After efficient feature extraction, the main focus of the study, the recognition performance of classifiers in conjunction with moment-based feature sets, is introduced.

7 illus, 2 tables, 13 ref

021218   Mathur A;Kar S;Gupta H M (NO, Inter Solutions Pvt Ltd, B-21, Sector 58, Noida, Uttar Pradesh, Email: mathur abhinav@gmail.com) : Advance resource reservation protocols: Applications in mobile networks. IETE J Res 2006, 52(2-3), 215-27.

Users employing communication networks for their critical business needs expect a very high level of Quality of Service (QoS) and are aware of their requirements in advance in many cases. Proposes a model for a network that allows users to specify their requirements in advance and defer the decision to admit the call to optimize the usage of network resources. The application of this model for mobile networks has been especially studied.

9 illus, 32 ref

021217   Marchese M (Commun Computer and System Sci Dep (DIST) / CNIT (Italian Natn Consort, Univ of Genoa, via Opera Pia 13, 16145 Genova, Italy, Email: mario.marchese@cnit.it) : Modifications of the slow start algorithm to improve TCP performance over large delay satellite channels. IETE J Res 2006, 52(2-3), 121-37.

Presents a study and performance analysis of a modified version of the TCP (Transmission Control Protocol) over a GEO (Geostationary Orbit) satellite link. The Round Trip Time (RTT) is above 500 ms. The high delay to receive acknowledgements decreases the performance of the TCP but, if the application field has a limited extension (as it is the test-bed emulated in the paper) the characteristics of the links and of the devices traversed are well known and the congestion aspects may be treated differently than in a large cable network, where the number of devices in the path is difficult to control. So, even if the performance of TCP is not satisfying, improvements can be obtained by properly tuning some parameters and modifying algorithms. A new increase function of the slow start algorithm is introduced. It is called MTSI - Multi Threshold Smoothed Increase. The performance is measured by the throughput in bytes/s and by the overall transmission time. An ftp-like application designed for the aim has represented the reference application. The performance analysis is carried out by using both a real satellite test-bed and a satellite network emulator. The new proposal is compared with different strategies already in the literature, including the TCP New Reno, configurations with augemented buffer and initial window and transport layer solutions already adapted for the satellite environment. The analysis has included both the single and the multiple application case, where several connections share the satellite link at the same time. The file transfer dimension is varied along with the bandwidth available and the advantage of the new proposal depending on these two parameters is also evidenced. The performance has been measured both in clear sky condition (no packet loss) and during loss situations.

10 illus, 9 tables, 36 ref

021216   Manonmani K;Murugan N (Mechanical Engng Govt Coll of Technol, , Coimbatore) : Integration of robust design and simulation to predict optimum parameters for laser beam welding. Indian Weld J 2005, 38(4),39(1), 24-32.

An attempt is made to achieve a robust weld quality that is insensitive to uncontrollable factors. the best process parameters are identified by integrating the Robust Design Concept and simulation. The influence of process parameters of Laser Beam Welding are studied. The controllable parameters considered are heat flux, welding speed, focus diameter and plate thickness. The ambient temperature is taken as uncontrollable factor. Simulation of experiments is performed for different combinations of parameter using ANSYS software bgased on Taguchi's Robust technique. Three dimensional non-linear transient thermal analysis is performed and the temperature distribution along the laser welded plate is obtained in the form of contour plots. Bead width and penetration depth are determined from these plots. To find the effect of control factors on the responses, ANOVA table is formed. Also, the best parameters for different responses are identified using S/N curves.

20 illus, 9 tables, 6 ref

021215   Manna I;Chopkar M;Das P K (Dep of Metall and Mater Engng, Indian Inst of Technol, Kharagpur-721 302, Email: imanna@metal.iitkgp.ernet.in) : Nanofluid - a new concept in heat transfer and thermal management. Trans Indian Inst Metals 2005, 58(6), 1045-55.

Nanofluids are quasi-single phase heat transfer fluids with negligible (<60> 1 vol. %) amount of nanometric solid dispersion in a base fluid making a stable colloidal suspension. These fluids are of interest due to the extraordinary (40-200%) enhancement of thermal conductivity possible that eludes a precise scientific explanation as yet. In the present paper, some interesting results pertaining to the synthesis and characterization of nanometric Al-alloy particle dispersed water and ethylene glycol based nanofluids have been presented after a brief overview of the evolution of the concept of nanofluid. While the nano fluid is prepared by a two-stage process including mechano-chemical synthesis of nanocrystalline Al₇₀Cu₃₀ alloys powders, thermal conductivity is measured using an improvised thermal comparator method. The results indicate that the thermal conductivity ratio could be enhanced up to 100% with a dispersion of only 2 vol. % nanometric Al alloy particles in water or ethylene glycol.

11 illus, 1 table, 19 ref

021214   Lojkowski W;Ivanisenko Y;Fecht H J (High Pressure Res Cent, Polish Acad of Sci 01-142 Warsaw, Poland, Email: wl@unipress.waw.pl) : Strain induced cementite dissolution in pearlitic steels as a classical example of mechanical alloying. Trans Indian Inst Metals 2005, 58(6), 993-1001.

The mechanism of the strain induced cementite dissolution was analysed in terms of a model where a plastic phase (ferrite) flows under high pressure and high external stress around hard precipitates like a viscous fluid. The friction at the precipitate/matrix interface leads to two effects. One is a high strain energy accumulated in the carbides, which may strongly contribute to their thermodynamic instability, and the second is their wear due to the flow of the ferrite. The dissolution of carbon with the ferrite phase can be considered as a driven transformation, where two driving forces for mass transport flow are competing. One is the mechanically induced drag of carbon atoms, which depends mainly on the deformation rate. The second is diffusion of carbon induced by thermodynamic energy gradients, which are connected with high strains in the precipitates.

6 illus, 35 ref

021213   Li L;Stewart R (Laser Processing Res Cent, Sch of Mech Aerospace and Civ Engng The Univ of Manchester, Manchester M60 IQD, UK, Email: lin.li@manchester.ac.uk) : Laser processing of nano-foils in confined environment for security coding. Trans Indian Inst Metals 2005, 58(6), 1079-94.

Strips of thin (20 nm thick) aluminium foils laminated on both sides with transparent polymers are processed with a Q-switched Nd: YAG laser to generate specific microscopic features for security coding. The effect of laser processing parameters on material behaviour in the confined environment is analysed. Because of the confinement by the polymers, the particle generated (either by laser melting or vaporisation) of 100 nm to 2 nm in size are trapped and distributed within the polymer films not normally seen in open surface laser beam processing. This produces various microscopic features that have distinct "signatures" for identification. The interaction of the laser beam with the Al foil with a thickness close to the optical absorption length of the beam is another aspect that is different from laser processing of thicker materials. The thermal heating and cooling effects for laser processing of ultra-thin metallic foils together with the mechanisms of various microscopic feature formations are discussed.

14 illus, 2 tables, 25 ref

021212   Li H F;Ramanujan R V (Sch of Mater Sci and Engng, Nanyang Technol Univ, Singapore-639 798, Email: ramanujam@ntu.edu.sg) : Synthesis of Fe-Co based nanomagnetic materials. Trans Indian Inst Metals 2005, 58(6), 965-70.

Processing of FeCo based nanomagnetic materials was carried out by chemical synthesis, crystallization from amorphous precursors and mechanical alloying. It was found that the product from chemical synthesis depended on the concentration of reaction solution. Uniform fiber like and spheroidal nanopowders were produced using Fe⁺² rich and Co⁺² rich reaction solutions respectively. The chemically synthesized FeCo based alloys was found to be amorphous. Through crystallization of melt spun amorphous precursors, high density nanocrystalline Fe_44.5Co_44.5Zr₇B₄ alloy was obtained; the nanocrystals had a compacted dendritic morphology. Spheroidal nanocrystalline structure was successfully obtained after mechanical milling of Fe_44.5Co_44.5P₇B₄ for more than 20 h at 300 rpm. The fiber like and compact dendritic morphology was not suitable for soft magnetic properties. Due to the pinning of magnetic domains, the powder nanostructured FeCo based alloys had inferior soft magnetic properties to the ribbon form alloys. The fiber like chemically synthesized and mechanically alloyed FeCo based alloy powders showed large coercivities. The magnetization of chemically synthesized FeCo alloy powders was low, which was considered to be due to solid solution contaminations, amorphous phase formation and the oxidation layer.

5 illus, 19 ref

021211   Kulik T;Ferenc J;Burian A K (Fac of Mater Sci and Engng, Warsaw Univ of Technol ul, Woloska 141, 02-507 Warsaw, Poland, Email: tkulik@inmat.pw.edu.pl) : Magnetically soft nanocrystalline alloys for high temperature applications. Trans Indian Inst Metals 2005, 58(6), 1133-9.

In the study, it is shown that partial replacement of Fe with Co in amorphous (Fe_1XCoX)_73.5-Cu₁-Nb₃-Si_13.5B_{9< D> (X = 0.14 to 0.68) alloy increases the Curie temperature to 93°C. Another new class of nanocrystalline alloys was developed where Fe was replaced with Co in NANOPERM to obtain a composition of Fe45Co43Cu1-B3.6-Zr7.4 xRMx} (where x = 3.7, RM = Nb and Hf). The Curie temperature in this alloy increases to over 800°C allowing retention of ferromagnetic properties at reasonably high working temperatures up to 500-600°C. However, the Co doping increases the coercivity deteriorating the soft magnetic properties slightly. The alloy with 6 at. % B and 7 at. % Hf seems to show optimum properties, thermal stability and ease of synthesis. The cobalt-to-iron ratio should not exceed 1:1 to ensure high Curie temperature and good soft magnetic properties and good thermal stability.

13 illus, 10 ref

021210   Kim S (Inf & Telecommun Engng Dep, Hansung Univ, 389 Samsun-dong 2ga, Sungbuk-Gu, Seoul, Korea-136-792, Email: kimsc@hansung.ac.kr) : Performance improvement of reliable data transfer protocol in broadband satellite networks by using the reflecting signals. IETE J Res 2006, 52(2-3), 105-12.

Satellite is the most versatile component in telecommunication systems. While it can be used for long distance telephony communications, it can provide a feasible wide-range broadcasting channel for multimedia transmissions including television broadcasting and more recently the Internet. However, a reliable link connection is necessary in order to support high-speed and reliable data transfer over the satellite channel. The satellite channel suffers from unavoidable long delay and high power attenuation. After discussing the role and architecture of satellite networks in future multimedia networks, it has shown that how the traditional Goback-N ARQ technique can be improved over the satellite link by using reflecting signals from the satellites. In the proposed scheme, uses reflecting signal from the satellite in order to investigate if the transmitting frame experiences errors. Identification of the next arrving frame is also performed during the timeout event. Through numerical and simulation results, the superior performance of the proposed scheme in satellite networks will be demonstrated.

8 illus, 1 table, 13 ref

021209   Khare R N (NO, , ) : Bearing capacity of arsenic bearing soil. Res Link 2006, 26,5(1), 109-10.

Arsenic is leaching from rocks and contaminates the soil in Durg areas. In addition to environmental concerna about groundwater pollution and other possible effects, the geotechnical properties of the contaminated soil such as the shear strength and the hydraulic conductivity are also altered. Results of research to evaluate the variation of the shear strength of sand and clay contamined by 3 different types of arsenic with varying kinematic viscosities and thus the ultimate bearing capacity of shallow foundations have been presented. The results of the tests reported relate to only 1 type of sand and 3 types of arsenic. The arsenic contents varied from zero to 6%. Result of direct shear tests for determining the soil friction angles are given. Additionally presented are laboratory model test results to determine the ultimate bearing capacity of a surface strip foundation supported by arsenic-contaminated sand and clay. Based on these test results, the effect of arsenic contamination in drastically reducing the bearing capacity is discussed.

3 tables, 1 ref

021208   Keny A (Shri Shantadurga Electromechanical Works, , Goa) : Polymer wearing rings for small pumps. Indian Pumps 2005, 37(4), 27-9.

6 illus, 2 table

021207   Katayon S;Megat Johari M M N;Abdul Halim G; Azni I;Ratnasamy M (Dep of Civ Engng, Universiti Putra Malaysia 43400 Serdang, Selangor, Malaysia) : Utilization of sewage sludge as aggregate in asphalt mixes. Ecol Envir Conserv 2005, 11(3-4), 327-31.

Thermal treatment of sewage sludge has been identified as an attractive method in terms of sludge volume reduction and production of reusable by products. Molten slag is one of the by-products of thermal treatmemt, which is obtained by incinerating the dewatered sewage sludge up to 900°C for 3 hours and followed by melting at 1450°C for another 45 minutes. Study was carried out to determine the possibility of utilization of sewage sludge molten slag as aggregate in asphalt mixes. The results showed that molten slag fulfills certain requirements as aggregate in asphalt mixes. However, criteria such as flakiness and gradation of aggregate result indicated that molten slag could not be used as aggregate by itself and is recommended to be mixed with conventional aggregate with a ratio of 4:1 to produce an asphalt mixe with optimum asphalt content value of 5.22%.

4 illus, 3 tables, 4 ref

021206   Joshi S G;Padalkar R G (Kirloskar Brothers Limited, , Pune) : Energy saving opportunities in industrial and agricultural pumps. Indian Pumps 2005, 37(4), 5-10, 19.

14 illus, 1 table, 4 ref

021205   Jayanthi M;Mariappan M J;Thengaraj N J; Kannadevan T (Cent Inst for Brackishwater Aquacult, , 75, Santhome High road, R A Puram, Chennai-600 028, Email: mannan96@hotmail.com ) : Design and development of non convective solar pond. Ecol Envir Conserv 2005, 11(3-4), 359-62.

A non convective salt stratified mini solar pond with three distinct regions namely upper convecting zone (UCZ), non convecting zone (NCZ), lower convection zone (LCZ) was constructed to assess the performance. Sodium chloride salt was used to create the density gradient. Different density of salt water was maintained in different depth using diffuser by layer by layer method. pH was maintained at 7.5. The temperature values were high in the LCZ and NCZ. The maximum temperature attained at the LCZ was 48°C. The efficiency of the pond was 18.78 per cent and various losses from pond like top, side, bottom losses were measured as 42%, 5% and 3.4% respectively. The insulation resulted in 0.35 Mj/day energy saving at LCZ and increased the efficiency of the pond by 1.5%. The shadow effect was 3.82% (12.87Mj). The temperature at LCZ could go up to 70°C in summer and supply 4500Kj/day. The simple three zone model of the pond was considered, temperature variations and energy fluxes are calculated and the efficiency of the pond was arrived. The solar pond proved to be reliable and quite efficient storage system.

1 illus, 1 table, 9 ref

021204   Jayanthi K;Varadharajan K;Araunkumar A; Dananjayan P (Electron and Communs Engng Dep, Pondicherry Engng Coll, Pondicherry-605 014, Email: jayanthi_pec@rediffmail.com) : Performance enhancement using opportunistic schedulers in wireless networks. IETE J Res 2006, 52(2-3), 207-13.

Maximising system performance under various Quality of Service (QoS) constraints to cope with the rapidly growing demand of wireless applications is emerging as one of the important goals of future wireless networks. An obvious way to improve the performance is by incorporating appropriate scheduling mechanism in such networks. Although, scheduling has been extensively studied in different disciplines like operations research and wire-line networking, the unique characteristics of wireless networks, namely the time varying channel conditions and multi-user diversity necessitate the development of new scheduling solutions. Consequently, designing scheduling mechanisms that take advantage of time-varying channel conditions, is necessary to improve system performance. However, this has to be done in such a way as to ensure some level of fairness among the users. One such scheduling mechanism termed opportunistic scheduling has been investigated in the paper. An attempt has been made to maximise system throughput while satisfying the QoS metric, user temporal fairness. A performance comparison is made with the existing non - opportunistic scheduling schemes and the results are presented.

9 illus, 2 tables, 7 ref

021203   Imai H;Shin S;Kobara K (Res Cent for Inf Security, Natn Inst of Advd Industrial Sci and Technol (AIST), 1-18-13, Sotokannda, Chiyoda-ku, Tokyo 101-0021, Japan, Email: shinsh@imailab.iis.u-tokyo) : Secure channels for wireless communications. IETE J Res 2006, 52(2-3), 229-38.

Most fundamental security goals include authentication and confidentiality both of which can be achieved by an authenticated key establishment (so-called AKE) protocol where the involving parties authenticate each other and generate crytographically-secure (but temporal) session keys for their subsequent secure channels. As AKE protocols for wireless security, the IEEE 802.1x standard committee employed the Extensible Authenticated Protocol (EAP) methods: EAP-MD5, LEAP, EAP-SIM, EAP-AKA, EAP-TLS, EAP-TTLS and PEAP, In the paper, author has first revisited the EAP methods considering the following practical situation: (1) a user, who communicates with many different servers, remembers only one password and has insecure mobile devices (e.g, mobile phones or PDAs) with very-restricted computing power and built-in memory capacity; (2) the counterpart servers have enormous computing power, but they are not perfectly secure against various attacks (e.g, virus or hacker); (3) neither PKI (Public Key Infrastructures) nor TRM (Tamper-Resistant Modules) is available. For the above situation, introduced an RSA-based AKE (for short, RSA-AKE) protocol that satisfies both higher level of security and efficiency over their kinds.

1 illus, 2 tables, 27 ref

021202   Hellmig R J;Kim H S;Estrin Y (IWW TU Clausthal Agricolastr. 6, 38678 Clausthal-Zellerfeld, Germany, Email: juri.estrin@tu-clausthal.de) : Introducing misorientation evolution into ecap modelling: a possible approach. Trans Indian Inst Metals 2005, 58(6), 1107-11.

A three dimensional version of a dislocation density based constitutive model allows calculating the evolution of microstructure, mechanical properties and texture was used to simulate the equal channel angular pressing (ECAP) of copper. The paper focuses on the concomitant variation of the misorientation angle with increasing strain, Own experimental measurements and literature data ware used to obtain the parameters required for simulating the evolution of the misorientation angle. A comparison of the results of simulation with experimental data shows the possible applicability of this approach for predicting microstructure evolution, including the variation of the misorientation angel, under severe plastic deformation.

5 illus, 24 ref

021201   Haug F J;Patscheider J (Empa-Materials Sci & Technol Uberlandstrasse 129, Ch-8600 Dubendorf, Switzerland, Email: f.j.haugefz-juelich.de) : Plasma deposition processes for nanocomposite tin/SiN oatings. Trans Indian Inst Metals 2005, 58(6), 957-63.

Refractory transition metal nitrides like TiN show outstanding mechanical properties and high hardness which lead to their wide use as coating meterials for wear protection. In most cases, such coatings are deposited by plasma processes because they allow for comparatively low deposition temperatures. Furthermore, freedom in the choice of the deposition parameters makes it possible to improve the elastic and plastic properties by influencing crystal quality, grain size, texture, stress, etc, The formation of composite materials has become another attractive path for the development of new or enhanced properties, composites consisting of crystallites with typical sizes in the 10 mm regime and amorphous phases often show effects which go far beyond simple rules of mixture. Due to their nanostructure a certain composition range ot TiN/Si₃N₄ nanocomposites exhibits extraordinary hardness which exceeds those of Tin and Si₃N₄ and even approaches the values of the hardest known materials. These nanocomposites can be deposited by PACVD, UBM-PVD, and arc PVD processes. Aspects of these deposition methods are described and properties of nanocomposite films are discussed.

5 illus, 35 ref

021200   Han J;Pluth M J;Sekhar J A;Vasudevan V K (Dep of Chem & Mater Engineering, , OH, 45221-0012 USA) : Processing bulk structures from nanoparticles of aluminum. Trans Indian Inst Metals 2005, 58(6), 1189-1202.

The sinterability and processing of nanoparticles of aluminum to bulk nanocrystalline samples were studied. Pure Al nanoparticle, produced by the Exploding Wire Process, were uniaxially pressed at room temperature to compacts and sintered at various temperatures in the range from 500°C to 650°C. The as-synthesized powders had an average size of 130 nm with uniform 4-6 nm thick amorphous aluminum oxide coating around each particle. Studies carried out on the microstructure evolution and thermal stability of the processed materials indicated that temperature had a strong ifluence on the as-sintered microstructure, density and microhardness. Electron microscopy observations revealed that the sintering process at high temperature led to the breakup of the aluminum oxide scale around the particles resulting in a nanocomposite structure comprised of 100-200 nm Al oxide particles well dispersed in an Al matrix with a bimodal distribution of nanometer and micrometer size grains an Al gain matrix, with corresponding increase in sample density and hardness. Mechanisms governing the rupture of the oxide layer around the nanoparticles are discussed. Samples sintered at high temperature could be successfully rolled to high reduction in multiply passes, leading to full densification (100%) and high hardness. While cold rolling created many nanocracks in the Al matrix, hot rolling led to crack-free material.

ia12 illus, 41 ref

021199   Gupta H M (Commun Software Consultant, , L-84, Lajpat Nagar-2, New Delhi-110 024, Email: vimal_k@ieee.org) : CFPSM: an energy efficient multi-hop WLAN protocol. IETE J Res 2006, 52(2-3), 147-52.

IEEE 802.11 WLAN protocol defines an ad hoc network configuration in which stations communicate among each other without the need of centralised control functions. Ad hoc networks have low performance and their stations consume more power due to contention in the network. Devised an improved protocol, called the CFPSM protocol, which facilitates transmissions with reduced contention. Author has defined an announcement period in which the stations reserve the channel by announcing the frames to be transmitted. These frames are transmitted collision-free in the following transmission period. These mechanisms result in high throughput and low power consumption in the stations. Present extensions to CFPSM for multi-hop WLAN configuration to support mobile ad hoc routing. The suggested mechanisms lead to optimal frame transmissions across adjacent WLANs and avoid problems like indefinite postponement of transmissions or wastage of contension-free periods in WLANs.

6 illus, 7 ref

021198   Gunasundari R;Shanmugavel S (Telematics Lab ECE Dep, Anna Univ, Chennai-600 025, Email: r_gunasundari@rediffmail.com ) : Novel approach for fault tolerance in mobile IP based wireless networks. IETE J Res 2006, 52(2-3), 187-92.

Next generation wireless networks are envisioned to have an IP based infrastructure with the support of heterogeneous access technologies. One of the research challenges for next generation all IP based wireless networks is the design of intelligent fault tolerant technique to provide interruptionless service to mobile users. Mobile IP supports wireless users with continuous network connection while changing location. This is achieved by allocating number of mobility agents in the architecture of a wireless system. If failure occurs in a mobility agent, the users located in the coverage area of faulty agent will lose their network connection. In order to provide mobile users with satisfactory quality of service and fault tolerant service it is required to cope with failure of mobility agents. A new fault tolerant technique has been proposed which provides an efficient fault tolerant solution for Mobile IP based wireless networks.

8 illus, 8 ref

021197   Gondkar M M (M-tech Innovation Ltd, , Balajinagar, Pune) : Weatherfastness tests for surface coated materials and their evaluation methodds. Paintindia 2006, 56(1), 79-84.

It is important to understand that weather fastness or durability tests are comparative tests to obtain reliable indication of the "Relative Ranking " of materials. Artificial/ Lab weathering tests are standard driven test and the results obtained are repeatable & reproducible. The process of giving fastness rating using different scales by visual assessment is rather difficult & bit confusing. However, with the advent of colour computer measurment, gloss level measurements etc. it is made more informative & meaningful.

1 illus, 1 table

021196   Ghosh P K;Ravi Reddy M;Devakumaran K (Met & Mat. Engg. Dep, Indian Inst of Technol, Roorkee, Email: prakgfmt@litr.ernet.in) : Distortion and transverse shrinkage stress in butt welds of steel plates under different welding procedure and parameters of GMAW and SMAW processes. Indian Weld J 2005, 38(4),39(1), 15-23.

The transverse shrinkage stress generated in welding of 10, 12 and 25 mm thick steel plates using different welding processes and procedures has been estimated and its varying effect has been verified with the help of experimental measurement of distortion produced during welding. The weld joints of 10 and 12 mm thick plates have been prepared by using the GMAW and puised current GMAW (P-GMAW) processes with standard V-groove design whereas the 25 mm thick plate was welded by SMAW process employing V- groove and narrow groove design. At a given heat input and weld groove size the effect of welding processes and procedures on variation of shrinkage stresses in weld deposit causing distortion of weld joint has been substantiated by estimation of bending stress developed in the weld joint through measurement of bending of the plate. It is observed that the use of P-GMAW is advantageous over the GMAWwith respect to reduction in stress development in weld joint. The use of narrow groove design has also been found beneficial for reduction of stresses generated in the weld joint in comparison to those observed in case of using v- groove design.

12 illus, 3 tables, 10 ref

021195   Eckert J;Das J;Loser W;Kuhn U;Roy S K (FG Physikalische Metallkunde FB11 Material-und Geowissenschaften, Technische Universitat Darmstadt, Petersenstra, D-64284 Darmstadt, Germany, Email: j.eckert@phm.tu-darmstadt.de) : Ductile zr base bulk nanostructured composites: present state-of-the-art. Trans Indian Inst Metals 2005, 58(6), 1157-67.

Author has reviewed the present state-of-the-art in the production of Zr-base multicomponent structural bulk metallic glass/nanostructured composite materials by manipulating the microstructure to achieve high strength together with high ductility via controlling the instabilities responsible for early failure. Author has emphasized the possibilities to manipulate such composite microstructures in favor of either strength of ductility, or a combination of both, and also discussed the acquired ability to synthesize such in-situ high-strength composite microstructures in bulk form through inexpensive processing routes.

ia6 illus, 57 ref

021194   Dey G K;Neogy S;Srivastava D;Banerjee S (Mater Sci Div, Bhabha Atom Res Cent, Mumbai-400 085, Email: gkdey@apsara.barc.ernet.in) : Characterization of nanostructures by transmission electron microscopy. Trans Indian Inst Metals 2005, 58(6), 1113-23.

Characterization of nano-structures involves ascertaining their shape and size besides finding out the atomic arrangement inside these and their composition. Because of its ability to do imaging at an atomic scale, nanobeam diffraction and nanobeam composition analysis, the modern transmission electron microscope (TEM) has emerged as a complete characterization tool for examination of nanostructures. In the paper, examples are cited from the examination of various types of nanostructures in the TEM, with particular emphasis on the study of nanocrystalline materials. Besides nanocrystalline materials use of TEM in the study of nanotubes, mesoporous molecular materials and nanolayered materials have also been described.

14 illus, 28 ref

021193   Dev B N (NO, Inst of Phys, Sachivalaya Marg, Bhubaneswar-751 005, Email: bhupen@iopb.res.in) : Quantum dots. Trans Indian Inst Metals 2005, 58(6), 1177-88.

A quantum dot (QD) may be defined as a small patch of material confined in all three dimensions to nanometer lengths. When matter is structured and confined on the nanometer scale, some physics of little consequence for bulk systems may dominate important properties of the nanosystems. Interesting new properties of QDs are being exploited to fabricate devices like single-electron transistor, single-photon detectors, laser, quantum computers, new catalysts and for applications in cryptography, tracing specific proteins within cells etc. QDs can be fabricated by lithography or by self-assembly. The advantages of self-assembled QDs over those lithographically fabricated are explained. Many advanced applications require epitaxially grown QDs on single crystalline substrates, Molecular beam epitaxy (MBE) is the highest precision deposition method used in semiconductor processing. Examples of growth of self-assembled epitaxial QDs by MBE in the laboratory and characterizations of QDs are presented. Single-electron tunneling is an essential aspect of single-electron transistors. Results of single-electron tunneling in QDs showing Coulomb blockade, Coulomb staircase and quantum capacitance are presented. These results were obtained by scanning tunneling spectroscopy (STS) measurements at 103 K in a variable temperature scanning tunneling microscope operating under ultrahigh vacuum and attached to the MBE system. ostructures is described with examples of Si QDs fabricated on Si.

ia7 illus, 46 ref

021192   Deshpande R (Electron Dep, PDVVP Coll of Engng, Viladghat, Ahmednagar-414 001) : Novel centralised flow control scheme for ABR service in wireless ATM networks. IETE J Res 2006, 52(2-3), 139-46.

Proposes a novel Centralised Flow Control Scheme (CFCS) for ABR service in WATM network. The goal is to provide Quality-of-Service (QoS) guarantee to the users and to reduce the computational complexity at switches. A novel concept of monitoring the network status in the centralised controller in the form of rate allocation tables for flow control is the main theme of the algorithm. CFCS operates in ATM switches placed in the backbone of WATM network. The Network Controller Switch (NCS) monitors the current status of VC and bandwidth availability as well as tracking the current number of active sessions contending for capacity, to adjust the explicit bound in the source transmission rates. The simulation results show that the scheme is stable and efficient in achieving maximum utilisation of bandwidth occupacies, enhancing average throughput and achieving robustness under continuously varying network conditions. The simulation experiments also demonstrate the superiority of the proposed scheme to the other schemes in dealing with switch complexity.

14 illus, 1 table, 10 ref

021191   Deliwala (Del PD Pumps and Gears Pvt. Ltd., , ) : Energy efficienty gear pumps. Indian Pumps 2005, 37(4), 39-40.

2 illus

021190   Datta S;Bandyapadhyay A;Pal P K (Mechanical Engng Dep, P.Podar Inst of Mgmt & Technol, 137, V.I.P. Road, Kolkata-700 052, Email: bppimt@yahoo.com) : Quadratic response surface modeling for prediction of bead geometry in submerged arc welding. Indian Weld J 2005, 38(4),39(1), 33-43.

The effect of various process control parameters on bead geometry of submerged arc weldment has been aimed to investigate using quadratic response surface methodology. Each of the features of weld bead geometry has been assumed and expressed as a function of selected process parameters so that the function takes into account the linear, quadratic as well as interaction effects of the predictors. Experiments are conducted with different levels of process parameters like voltage, welding current, wirefeed rare and traverse speed to obtain bead-on-plate weld on mild steel plates. Based on multiple linear regression, mathematical models have been developed for prediction of bead geometry, for different settings of factor level. Using statistical software package MINITAB, reduced models are built up with significant factors and coefficients. MINITAB's Backward elimination option in stepwise regression is used to eliminate insignificant factors from the models and to recalculate the coefficients of the significant factors. Developed mathematical model for penetration has been optimized (maximized), considering (minimizing) the reinforcement, depth of HAZ and bead width as constraints. Sensitivity analysis was also carried out to study the change in value of the objective function (bead penetration) due to change of limit of the constraints from the optimum value. The direct and interactive effect of various process control parameters on the features of bead geometry and HAZ have been measured quantitatively and represented graphically. The methodology, proposed in the study can be used to obtain superior quality weld bead and also to achieve high productivity.

18 illus, 4 tables, 16 ref

021189   Das A K (Consultant (ESAB), , ) : Professional grade soft ferrites for welding power sources (inverter type). Indian Weld J 2005, 38(4),39(1), 44-8.

021188   Choyal Y;Gupta L;Vyas P;Deshpande P; Chaturvedi A;Mittal K C;Maheshwari K P (Sch of Phys, Devi Ahilya Vishwavidyalaya, Indore-452 001) : Development of a 300-kV Marx generator and its application to drive a relativistic electron beam. Sadhana 2005, 30(6), 757-64.

A twenty-stage vertical structure type Marx generator has been indigenously developed. At a matched load of 90-100 Ω, for 25 kV DC charging, an output voltage pulse of 230 kV, and duration 150 ns is obtained. This voltage pulse in applied to a relativistic electron beam (REB) planar diode. For a cathode anode gap of 7.5 mm, an REB having beam voltage 160 kV and duration 150 ns is obtained. Brass as well as aluminum explosive electron emission-type cathodes have been used.

5 illus, 1 table, 6 ref

021187   Buvanashekaran G;Manoharan S;Samidurai M (Weld Res Inst, BHEL, Tiruchirappalli-620 014) : Surface hardening of carbon manganese steel using laser beam irradiation. WRI Jl 2005, 26(4), 11-17.

Laser surface modification technology consists of surface hardening, alloying and cladding to improve the functional properties of the contact surface. Laser surface modifiation facilitates the change in properties of substrate without addition of any filler material and quenching but only needs to have a high energy beam. A conventional carbon manganese steel substrate was selected for Laser surface hardening due to its wider applications in Engineering industries. A solid state continuous wave (CW) Nd: YAG Laser source with spherical beam configuration was employed. Experiments were conducted at two different power levels, i.e., 450 and 500 watts and at 700 and 1000 mm/min scanning speeds. Argon gas shielding at a constant flow rate was used throughout the experimentation. Investigations revealed that 366μm depth of hardening could be obtained with 500w power and 800 mm/min scanning speed. The microhardness measurements showed at least two fold increase (400-450HV) in hardness in the irradiated zone cross section as compared to the base materials hardness. Microstructural studies revealed formation of martensitic structure in the hardened zone and a smooth transition in the inter face without affecting the structural integrity.

12 illus, 2 tables, 7 ref

021186   Bhattacharyya D;Jha S N;Das N C;Verma V; Markandeya S G;Ghosh A K (Spectroscopy Div, , Mumbai-400 085, Email: dibyendu@magnum.barc.ernet.in) : Simulation of temperature distribution by finite element analysis on different components of the EXAFS beamline at INDUS-II synchrotron source. Sadhana 2005, 30(6), 735-55.

An extended X-ry absorption fine structure (EXAFS) beamline is being developed for the INDUS-II synchrotron source. Several optical and mechanical components of the beamline are exposed to high intensity synchrotron radiation while in operation. The temperature rise on different components of the beamline on exposure to the synchrotron beam has been simulated by finite element analysis. Design of the cooling mechanism for each of these components has been carried out and estimation of the temperature rise has also been done incorporating the cooling mechanism.

18 illus, 5 tables, 18 ref

021185   Berger S (Fac of Materails Engng, Technion Haifa 32000, Israel, Email: berger@tx.technion.ac.il) : Particle size effect on ferroelectric behevior. Trans Indian Inst Metals 2005, 58(6), 1141-1156.

Paper reviews the subject of size effect on ferroelectric behavior form various points of view. It starts by describing three size regimes separated by two critical sizes, presenting experimental values of critical sizes as reported for various ferroelectric materials, giving details on structures of ferroelectric domains and domain walls as their size decreases to the nanometer scale, discussing theoretical models to predict the critical sizes, and showing specific cases where no size effect is present. The next section in this review presents the size effect on the stability of ferroelectric behavior as reflected in the transition temperature from ferroelectric to paraelectric phase. This section presents experimental evidence for a shift in the transition temperature with decreasing particle size and demonstrates the complexity of theoretical prediction the amplitude and direction of this shift. This last section of this review presents three different examples of nano-domain structures that exhibit forroelectric behavior different than that of bulk-size domain. Their ferroelectric behaivior is examined at different frequency and amplitude of applied electric field different temperatures and sizes. In some cases theoretical models and expressions are given to show the parameters controlling their ferroelectric behavior. In summary, this review is aimed to expose the possibilities and limitations of reducing the size of ferroelectric particles to the nanometer size scale.hich are needed for future applications.

ia5 illus, 90 ref