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Bioceramics have been widely utilized for orthopaedic applications in which the biocompatibility and mechanical properties of the materials are vital characteristics to be considered for their clinical use. Till date, extensive studies have been devoted to developing a range of scientific ways for tailoring the microstructure of bioceramics in order to attain the trade-off of mechanical properties and biocompatibility of the final product. Owing to low reactivity, earlier stabilization and longer functional life of bioceramic, the developed implants are capable of replicating the mechanical behaviour of original bone. As the safety of the patient and its ultimate functionality are the ultimate goal of the selected implant material hence, the present literature survey investigates and brings forth the important aspects associated to the mechanical, biological and microstructural characteristics of bioceramics employed in orthopaedic applications. The review paper majorly focuses on effective utilization of various materials as an additive in bioceramics and processing techniques used for enhancement of properties, enabling the use of material in orthopaedic applications. The influence of various additives on the microstructure, mechanical properties and biological performance of developed bioceramics orthopaedic implants has been elaborately discussed. Furthermore, future prospects are proposed to promote further innovations in bioceramics research.

This paper reviews the basic understanding of Mg-based thermoelectric materials and various approaches for increasing their thermoelectric efficiency. Recent developments in terms of enhancement of electrical properties and reduction of thermal conductivity of Mg2(Si,Sn) materials through experimental investigation and applying modeling approaches are discussed in detail. Further, the role of deformation and heat treatment analysis for achieving optimum thermoelectric properties in this material system and its prospects for further developments as a commercially viable solution is enumerated. The solid solutions of Mg2X (X = Si,Ge,Sn) thermoelectric material are identified as the most favorable alloy class of thermoelectric materials for application in the intermediate temperature range (400–800 K). The reason for Mg2X alloys becoming the preferred choice over others is because they are cheap, abundant and non-toxic. Improving the efficiency of magnesium-based thermoelectric materials through various advancements in experimental methods has appeared as a matter of great commercial importance. However, theoretical understanding of the phenomenological issues confronting the attainment of desirably high thermoelectric properties has not been widely touched upon; this leads to enormous opportunities for optimizing the figure of merit of thermoelectric materials through numerical modeling and simulation techniques. Also, deforming the alloys has been proved to be favorable for the thermoelectric performance of the material; a lot of work has been carried out for other classes of thermoelectric materials, but there is a disparity in interpreting the deformation behavior of Mg2Si1−xSnx alloys and its impact on thermoelectric properties due to lack of adequate efforts to conduct systematic investigations in the area of concern.

This paper reports the results of investigation on 0.1C-17Mn-5.5Ni-1.8Al-2.7W-4.6Mo-2.3Cu-0.002B steel designed to assume excellent combination of strength and toughness. The air induction melted steel was subjected to hot forging at 1200 °C followed by hot rolling in six passes from 1100 °C. The rolled samples were reheat-quenched from 1050 °C in iced water. The quenched samples were isochronally aged at temperatures within 500-650 °C at interval of 50 °C. The mechanical properties were determined by hardness measurement and tensile testing. Structural characterization was accomplished by x-ray diffraction, optical and electron microscopy. Differential scanning calorimetric study was conducted to understand the precipitation kinetics. A typical age-hardening behavior was noted in the aged samples due to the precipitation of M2C and Ni3Al. Strain hardening of martensite, precipitation hardening due to the presence of nanosized precipitates and Orowan hardening were found to be instrumental in attaining a maximum hardness of 723 HV. The microstructure of aged samples consists of retained austenite, e-martensite, α′-martensite and uniformly distributed nanosized precipitates of Ni3Al and M2C, lying broadly within two different size regimes. The sample peak aged at 550 °C attained a strength of 1.4 GPa at a total elongation value of 25%. The combination of high strength and high ductility has resulted from precipitation strengthening, TRIP phenomenon and high degree of structural fineness.

The effect of multiwall carbon nanotube (MWCNT) content on the physical and mechanical properties of Fe-MWCNT composites has been studied. High-energy ball milling (HEBM) is employed to produce the composite powder; following this, spark plasma sintering (SPS) process has been adopted for powder consolidation. The composite powder and the sintered products were subjected to structural characterization by XRD. Microstructural studies were carried out by optical, field-emission scanning and high-resolution transmission electron microscopy. While Fourier transform infrared spectroscopic study of composites was done to understand the bonding characteristics, Raman spectroscopy was employed to assess the structural damage of MWCNT after HEBM. The effects of processing on the behavior of C-C, C-O and Fe-O bonds are studied by x-ray photoelectron spectroscopy. Microhardness and compressive strength of composites are also determined. Finally, magnetic and electrical properties of the composites were characterized. It was observed that optimized ball milling conditions help to preserve the structural identity of MWCNT. Consolidation by SPS insured good interfacial bonding. The microhardness and compression strength are significantly improved in MWCNT-reinforced iron matrix composite. MWCNT has appreciably improved the electrical conductivity of the composites. Tethering of MWCNT by iron oxide has led to appreciable improvement in saturation magnetization till 3 wt.% MWCNT.

Copper metal embedded fullerene C60 thin films are deposited on various substrates via resistive heating co evaporation technique. Rutherford back scattering simulated spectrum confirms the thickness and composition of thin film to be ~ 32 nm and ~ 18 at%, respectively. The deposited thin films are irradiated by 120 MeV Ag ion beam for different fluences within the range, from 1 × 1012 to 3 × 1013 ions/cm2. UV–vis absorption spectroscopy study reveals the appearance of surface plasmon resonance (SPR) band in pristine thin film at ~ 622 nm; this phenomenon is ascribed to the presence of copper nanoparticles in C60 matrix. The SPR band intensity increases with rising fluences, which is suggestive of the growth of Cu nanoparticles. Growth of Cu nanoparticles is further confirmed by transmission electron microscopic (TEM) and X-ray diffraction (XRD) study. Whereas the conversion of C60 into amorphous carbon (a-C) is confirmed by Raman spectroscopy, XRD results of pristine Cu–C60 thin film record the presence of Cu2O within the nanocomposite thin film. However, both X-ray photoelectron spectroscopy (XPS) and XRD studies on irradiated thin film samples authenticate the growth of Cu metal nanoparticles with concurrent removal of oxygen.

Introduction: Asymptomatic bacteriuria (ASB) is the presence of actively multiplying bacteria within the urinary tract with absence of any symptoms, resulting in adverse pregnancy outcomes. This research study was done in order to review prevalence, antimicrobial susceptibility profile, and factors associated with ASB occurring in female patients who are pregnant and being treated at a tertiary care hospital in Lucknow, India. Method and Materials: This is a cross-sectional study done among 216 pregnant women attending a hospital for antenatal check-ups. Clean catch midstream urine samples were collected and examined microscopically, and semi-quantitative culture was done on blood agar and MacConkey agar. Isolates were identified by colony morphology and biochemical tests, and antimicrobial susceptibility testing was done by using the Kirby-Bauer method. Results: Of the 216 pregnant women, 36 (16.7%) tested positive for ASB. The female gestational period, haemoglobin level, and BMI were significantly associated with ASB. Logistic regression also showed that higher haemoglobin level was less likely to ASB (AOR = 0.42, 95% confidence interval: 0.202–0.88, p = 0.021). The predominant and usual isolates were E. coli (n = 22, 61.1%), followed by Cons (n = 6, 16.7%), and S. aureus (3, 8.3%). All Gram-negative isolates were mostly sensitive to most of the drugs like piperacillin-tazobactam, cefepime, nitrofurantoin, and meropenem but were 100% resistant to ampicillin. Similarly, Gram-positive isolates were sensitive to ampicillin, vancomycin, linezolid, and nitrofurantoin but 100% resistant to co-trimoxazole. Conclusion: The present study shows the existence of ASB was 16.7% among women who are pregnant. Pregnancy duration, haemoglobin level, and BMI were significantly associated with ASB. The isolates identified more frequently were E. coli (61.16%), Cons (16.7%), and S. aureus (8.3%). All isolates which were Gram-negative were mostly sensitive to most of the drugs but were 100% resistant to ampicillin. Similarly, Gram-positive isolates were sensitive to most of the drugs but 100% resistant to co-trimoxazole.

High-energy ball milling (HEBM) of mixtures of iron powder and multi-walled carbon nanotube (MWCNT) has been performed in an attempt to synthesize nano-grained steel. Even after exposure to a harsh HEBM conditions, the MWCNTs are seen to have retained their structural identity, and therefore, an MWCNT-reinforced steel matrix composite could be finally produced. Moreover, the study has revealed that the minor addition of copper leads to a significant reduction in grain size of ferrite in the so-produced steel matrix–MWCNT composite. It is also noticed that the fine grain structure of ferrite remains intact even after consolidation of the powder composite by spark plasma sintering, followed by hot forging. The micro-hardness values obtained for the composites (with/without copper) are observed as comparable with the submicron-grained steels, so far reported in the literature.

Evolution of microstructure in the patented near-eutectoid steel, forged under varying situations, is critically examined in the present investigation. Steel with 0.74 wt.% carbon is isothermally annealed at 500 °C to obtain fine pearlite microstructure. Steel samples, so patented, are subjected to mechanical deformation by forging at various temperatures with different amount of thickness reduction. Microstructural analyses have revealed that mechanical deformation by forging at lower temperatures brings about partial dissolution of cementite, which is followed by the formation of e-carbide in the microstructures. In contrast, cementite is precipitated within ferrite matrix upon warm or hot forging at higher temperatures. It is further observed that increasing deformation percent during low-temperature forging reduces interlamellar spacing of pearlite, whereas an opposite trend is noticed in case of deformation at higher temperature; moreover, deformation induced the change in interlamellar spacing and formation of fine carbide phases in microstructures has caused appreciable enhancement in hardness of the steel.

Thermoelectric generator (TEG) that works in medium and high temperature ranges has appeared as a necessity in combating with the waste heat management from various industries. Therefore, design of TEG with thermoelectric materials capable to exhibit high capacity for thermoelectric power generation is of emerging technological interest. It is known that alloys based on Mg2(Si, Sn) and PbTe thermoelectric materials are best suited for the intermediate temperature scale (400–900 K). For constructing a TEG, higher manganese silicides (HMS) are often used for integration with n-type Mg2X (Si, Ge, Sn) alloys. The thermo-mechanical property-mismatch reasons out the option for such a combination in fabrication of a sustainable thermoelectric generator. This makes one focus on evolving a generation system that comprises of both n- and p-type thermo elements prepared from suitable Mg2X (Si, Ge, Sn) alloys. The present research analyses the feasibility of designing a Mg2 (Si, Sn) alloy based thermoelectric generator by modeling approach. It presents a comprehensive take on the effect of thermoelectric leg dimensions and contact resistances on the output voltage, output power and efficiency, with alteration in the operating temperature span. The COMSOL modeling results indicate that the power output reduces considerably with increment in the thermoelectric leg length, while the conversion efficiency enhances. Contrarily, augmenting the cross-sectional area of a thermoelectric leg follows an opposite trend i.e., it increases the power output and decreases the conversion efficiency. The power output and the conversion efficiency values diminish when contact resistances are considered in the modeling study. This study also incorporates an efficient heat exchanger system including contact resistances and conductive and convective heat losses for accurate estimation of power output and efficiency of the optimized TEG module.

In this work, low carbon of extremely fine grain structure was produced by mechanical alloying of powders of iron and activated charcoal with minor addition of copper (Cu); mechanically alloyed powder was consolidated by spark plasma sintering to obtain a high-density compact. The steel so produced was subsequently subjected to forging followed by normalizing. The characterization was carried out by means of nanoparticle size analyzer, X-ray diffraction, optical microscopy, scanning electron microscopy, transmission electron microscopy, and Vickers microhardness testing. The microhardness value obtained for the steel was found to be significantly high and comparable with that of nanocrystalline/ultrafine grained steels produced by other routes. The increased hardness resulted from the smaller grain size and presence of finely dispersed ultra small sized copper and cementite precipitates.

This paper reports the beneficial effect of silver addition (~0.1 wt%) on the structural stabilization of multiwalled carbon nanotube (MWCNT) reinforced in iron matrix by way of high energy ball milling (HEBM) and spark plasma sintering (SPS). Silver added Fe - x wt% MWCNT (x = 1, 2, 3 and 4) composites were prepared by HEBM followed by SPS. Structural characterization of silver bearing composite powder and its sintered mass was carried out by XRD. The structural damage of MWCNT after HEBM was assessed by Raman Spectroscopy. As a support, Fourier Transform Infrared (FTIR) spectroscopic study was used to look into the bonding characteristics. Detailed microstructural studies by optical, field emission scanning (FESEM) and high-resolution transmission electron microscopy were employed to further assess structural stabilization and evolution of micro constituents during processing. Finally, magnetic and electrical properties of the composites were determined. It was revealed that minor addition of silver aids in restoration of the structural integrity of MWCNT in iron matrix composite. Moreover, it was noted that silver added composite could achieve a contamination free matrix–reinforcement interface. It is propounded that silver atoms tether MWCNT surface and behave like coating over MWCNTs. Conductivity of silver doped iron-4 wt% MWCNT composites exhibited a conductivity value higher than that of electrical conductivity grade (EC grade) aluminum. Saturation magnetization of silver doped Fe-MWCNT composite was increased by 25% over pure iron at 3 wt% MWCNT. The observed improvement in properties of composite is ascribed to tethering of silver particles at MWCNT surface; this gave rise to better interfacial bonding and the physical properties.

In the present study, efforts have been made to assess and study the reduction of mill scale in the presence of single gaseous reductant (i.e. CO gas) in RI-RDI (reducibility index (RI) and reduction degradation index) equipment. While conducting this study optimal process parameters like reduction temperature, mill scale size, reduction time and mill scale to coal ratio were analysed. An exceptional experimental profile is maintained inside the furnace to attain the optimum metallization. The mill scales are reduced inside the furnace and the extent of reduction is evaluated from the weight loss. Post conducting reduction in the RI-RDI test apparatus, the reduced mill scale is characterized for the microstructural and morphological studies using SEM, EDS, XRD. The most optimum results of the reduction were attained in RI-RDI apparatus giving iron content of (metallization) 89.15 % at the reduction temperature of 1050°C for 240 mins holding time. During the entire study on RI-RDI apparatus, flow rate of CO is maintained at 4.5 LPM (litres per minute) and N2at 10.5 LPM. Finally, the degree of metallisation in the sample as well as the product material is calculated by using the chemical analysis process (dichromate and ferric chloride method). The characterization of produced iron powder was done by chemical analysis, XRD, and FE-SEM. The FE-SEM results confirm the presence of resultant pore characteristics. It is observed that mill scale can be significantly reduced to metallic iron by utilizing lean grade coal.

The present work reports the fabrication and characterization of high mobility thin-film transistors, where zinc nitride is used as the active layer (∼100 nm thick). For the TFT, the active layer was deposited at room temperature on different substrates (Si-p type and glass) by RF magnetron sputtering method and annealed at 350 °C post-fabrication and HfO2 was used as the gate insulation layer (∼50 nm thick). The obtained value of field-effect mobility was greater than 5 cm2 Vs−1, with optical bandgap ∼3.07 eV. The two MIS (metal insulator semiconductor) structures were analyzed using I–V and C–V measurements. It is demonstrated that Zinc Nitride is a potential candidate to be used as an active layer in TFT fabrication. The threshold voltages of the device built on Si and glass substrates were obtained as 0.8 volts and 2.6 volts respectively.

Bi doped Mg2Si0.4Sn0.6 had been synthesised in a high energy ball mill followed by compaction using a sintering hot press. The structural and compositional characterization of sintered mass indicated the formation of a highly densified single-phase product. The microstructure of the hot-pressed samples had been critically assessed. Thermoelectric properties were measured between room temperature and 723 K. A decrease in electrical conductivity was found with the increase in temperature but the Seebeck coefficient showed a reverse trend justifying the attainment of degenerate semiconducting behaviour. Meanwhile, the lattice thermal conductivity was subdued to 1.5 W/mK at 623 K. However, the highest zT value of 0.8 was achieved at 723 K. Moreover, the detailed X-ray photoelectron spectroscopic analysis was carried for the determination of binding energy of the constituent elements in the experimental alloy; it also provided the correct estimation of atomic percentage of the concerned elements. The Raman spectrum revealed a shift in F2g peak with respect to that of Mg2Sn and Mg2Si in correspondence with the composition of the synthesised alloy. The synthesised alloy showed micro and nano hardness of 3.7 and 4.03 GPa respectively, which implies that good mechanical strength could be achieved in the synthesised alloy.

Demand of today is to optimize the available resources and reutilize the waste materials. Mill scale is waste cum byproduct obtained during hot rolling operation of steels.In Rajasthan there are hundreds of hot rolling mills producing tons of mill scale everyday and in Nagaur, Rajasthan there are huge reserves of low grade coal. In this paper an attempt has been made to utilize the low grade coal for direct reduction of mill scale in laboratory to obtain sponge iron .The paper comprises the study on effects of variation in particle size(60-100,170-200 and

ique in a high energy planetary ball mill. Systematic study on microstructural evolution and magnetic properties after different milling time is conducted by X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM) and Vibrating Sample Magnetometer (VSM). It is revealed that formation of single phase alloy with an average of ~ 7 nm crystallite size is achieved after 20 hr milling by mechanically induced inter-diffusion of atoms. Moreover, changes in lattice parameters and lattice strain as a function of milling time is also studied. Change in morphology of particles with increasing milling time has been studied by SEM. In addition, d-spacing and diffraction planes obtained from analysis of HRTEM image and SAD pattern respectively corroborate with XRD results. Low coercivity indicated by hysteresis loop is suggestive of soft ferromagnetic behavior of the alloy powder.

Positron lifetime and coincidence Doppler broadening (CDBS) measurements were made on samples of Ti-6Al-4 V alloy subjected to different mechanical and thermal treatments. The results indicated the presence of point defects in moderate concentrations. The as-received sample was initially heat treated at 1343K for 30 minutes and slow-cooled to extract reference values. Even when subjected to heat treatment at 1343K and fast-quenched, the inherent defect structures did not show substantial reconfiguration in size or concentration. Yet in a separate case of heat treatment at the same temperature and duration followed by hot-rolling to 50% deformation, the deformation-induced defects were found retained in it on quenching. Soaking at the elevated temperature did not produce any significant difference. In another sample, when cold-rolling was performed after heat-treatment and fast-quenching, we found the retention followed by room-temperature migration and coalescence of the generated defects with the existing ones. The measured positron lifetimes suggested the existence of defects of smaller sizes and/or dislocations. In another sample of the alloy with identical treatments at 1248K (below the α to β transition), the positron lifetimes were slightly larger in magnitude.

Phase decomposition in Al–6Mg alloy doped with Sc up to 0.6 wt.% was first investigated through positron lifetime and coincidence Doppler broadening spectroscopic (CDBS) measurements. The results varied significantly with the degrees of doping and heat treatment conditions due to the entrapment and annihilation of positrons at vacancies and lattice irregularities like coherent and semi-coherent precipitate-matrix interfaces. Sc-vacancy complexes helped in fine scale precipitation of Al3Sc during the annealing. The substructure stabilization is effected more at low annealing temperature and shorter annealing times. The precipitation behaviour in 0.2 wt.% Zr-doped Al-6Mg-0.4Sc alloy under different annealing conditions was also studied. Although Sc has better diffusivity in Al-6Mg than Zr, the latter appeared to be an ideal additive to generate new precipitates of the form Al3Sc1- x Zr x and the differences are reflected in the positron lifetimes and CDBS ratio curves. Transmission electron microscopy showed spheroidal precipitates with complete absence of facets, implying the modification of the surface morphology of the precipitates.

The sintering and densification behavior of high energy ball milled (HEBM-ed) alumina–15 vol% zirconia nanocomposite were carried out and the probable tetragonal to monoclinic phase transformation of ZrO2 during sintering was investigated. Evolution of microstructure resulting from sintering was followed up by means of scanning electron microscopy (SEM) on polished samples, and the degree of phase transformation was determined by quantitative X-ray analysis (XRD). Moreover, synergetic effect of milling time and dopant composition on properties such as relative density, hardness, and fracture toughness was studied. The results have shown that mechanical properties of the composites were strongly dependent on the dopant content, structure and the fraction of tetragonal to monoclinic induced by HEBM and subsequent sintering. The extent of retention of t-ZrO2 depends on the balance of magnitude of the strain energy arising from HEBM and releasing from sintering. In fact, compacts with aggressive HEBM history showed improved fracture toughness. Also it is shown the homogeneous microstructure obtained by HEBM and subsequent sintering promotes better densification.

Effect of aging on the mechanical properties of Al-6Mg alloy doped with varying concentration of scandium ranging from 0.2 to 0.6 wt.% is analyzed. As-cast samples were aged isochronally for 60 min at different temperatures ranging from 100 to 500 °C. Evaluation of mechanical properties of the aged Al-6Mg (Sc) alloys was done by employing an Instron testing machine. Various strain rate of testing were used to find out the values of strain-rate sensitivity of the experimental alloys. The influence of scandium is much pronounced on yield strength than on the tensile strength. Alloys with higher scandium content have shown higher yield strength and the values of strain-rate sensitivity ‘m’ at peak-aged condition have been found to be comparatively high at higher scandium concentration. The fracture of the experimental alloys occurs through microvoid coalescence.

In the present work, three alumina–15 vol% zirconia composites with Y 2 O 3 , MgO as dopants and without oxide as dopant have been investigated. High energy ball milling (HEBM) provides the positive thermodynamic driving force for monoclinic to tetragonal transformation and it reduces starting temperature for the reverse martensitic transformation, meanwhile mobility of zirconium cations and oxygen anions are enhanced in zirconia by HEBM. The general, albeit heuristic, reasoning is corroborated by nanocrystallity, particle size and also the retained monoclinic seem to play an important role. After 10 h HEBM, approximately 28% zirconia tetragonal phase is achieved. Non-stoichiometric tetragonal zirconia phase; Zr 0.95 O 2 is seen to have been achieved by high energy ball milling (HEBM). The structural and compositional evolutions during HEBM have been investigated using X-ray diffraction method (XRD) and scanning electron microscopy (SEM). High resolution transmission electron microscope (TEM) is also used for further understanding about the phenomenological changes taking place during high energy ball milling.

The effect of microstructural parameters on the plane strain fracture toughness of scandium doped Al–6Mg alloys has been studied. Al–6Mg alloys with trace addition of scandium are subjected to annealing at different temperatures. Plane strain fracture toughness property ( K IC ) of the alloys under different thermal conditions is measured. It is found that fracture of coarse insolubles adversely affect the fracture toughness of binary Al–6Mg alloy. Scandium treated alloys have shown improvement in fracture toughness due to the reduction in size and amount of second phase particles. The isochronal age hardening behaviour of low scandium alloy is found similar to the variation of fracture toughness with ageing temperature. However, high scandium alloy records a minimum in fracture toughness value at the peak age hardening temperature due to extensive formation of planar slip bands.

In order to make a machining process cost effective as well as to assure the desired objective(s), it is important to find the optimal machining parameter(s) in considering all related output variable(s). However developing many models (each one corresponding to a single output variable) leads to more time consuming as well as difficult to interact them. Moreover it has been observed that some of the output variables are inter-related with each other. In this paper, an intelligent approach based on fuzzy basis function neural network (FBF-NN) is proposed to model the cylindrical plunge grinding process. Two approaches are adopted here for automatic design of rule base (each rule is characterized by the antecedent and consequent parts) of FBF-NN using a genetic algorithm. In the first approach the rule-consequent parts are determined individually and in the second approach, those are obtained based on the inter-relationship exist among the output variables. The results of the FBF-NNs and that obtained using the empirical expressions are compared with the real experimental values, which shows that the FBF-NN-based models give better predictions than mathematical models.

An unsupervised learning technique and an associative memory have been used for encoding weights by a special type of Petri network named Petri neural net for modelling the influence of alloying elements on the final property of the high strength low alloy steel. The combined effects of alloying elements for different strengthening mechanisms is predicted when weights and threshold values are chosen on the basis of metallurgical understanding. The technique is found to be effective to create an associative memory of input-output relations in unknown data sets so that the same can be subsequently be used as a predictive tool.

Development of ceramic particle reinforced aluminium metal matrix composites (MMCs) has recently resulted in advanced engineering materials for potential use in structural applications in aerospace, automobile and marine industries. In the present paper we have reported the corrosion behaviour of Al–Si–Mg–SiCp MMCs with minor alloying additions of scandium in the elemental state. The composites were prepared by mechanical alloying through a powder metallurgy route. Corrosion investigations were carried out in different levels of salinity and at variable values of pH using electrochemical techniques and immersion tests. Evaluated corrosion parameters are correlated with studies of metallurgical thermodynamics and surface morphology.

The effect of composition and controlled thermomechanical process parameters on the mechanical properties of HSLA steels is modelled using the Widrow-Hoff's concept of training a neural net with feed-forward topology by applying Rumelhart's back propagation type algorithm for supervised learning, using a Petri like net structure. The data used are from laboratory experiments as well as from the published literature. The results from the neural network are found to be consistent and in good agreement with the experimented results.

This progress report contains 36 items of research work done by ten members of the University of Maryland Nuclear Theory Group with 21 outside collaborators from various institutions in the US, Canada, Korea and Europe. The report is in four sections, each representing major and basic areas of interest in nuclear theory. The sections are as follows: (1) hadrons in nuclei and nuclear matter; (2) hadron physics; (3) relativistic dynamics in quark, hadron and nuclear physics; (4) heavy ion dynamics and related processes.

Under Hadrons in Nuclei and Nuclear Matter the authors research the ways in which the properties of nucleons and mesons are modified in the nuclear medium. Research progress is reported on a number of topics in this general area, including studies of the role of chiral symmetry for finite density or temperature nuclear matter, the use of QCD sum rules to describe baryons in nuclear matter, and color transparency. In the general field of Hadron Physics broad progress included studies of perturbative QCD, heavy quark physics, QCD sum rules, and QCD-based models. Notable progress was also achieved in Relativistic Dynamics in Quark, Hadron, and Nuclear Physics, where an explicit model of composite particles shows how the z-graph physics (which is an essential part of Dirac phenomenology) comes about. In addition, calculations of elastic electron-deuteron scattering based on two-body relativistic dynamics and meson exchange currents were completed, as were studies of quark-anti-quark bound states based on a relativistic quark model. Progress is also reported on the relativistic few-body problem. In the area of Heavy Ion Dynamics and Sharp Lepton Pairs, work continues on the Composite Particle Scenario for the `Sharp Lepton Problem`. In particular, the scenario can now encompass the anomalousmore » sharp leptons reported from positron irradiation of heavy neutral atoms, establishing such irradiations as an alternative experimental window to the heavy ion experiments.« less

A once-subtracted form of the Low equation for the pion-nucleon scattering amplitude is derived, with PCAC used to define the amplitude when one pion is off the mass shell. The static approximation is not made and both the seagull terms and the antinucleon contribution (z-graphs) are retained. The theory is applied to calculate the S-wave amplitudes in the elastic scattering region. Good agreement is found with the phase shift fits to the data when we use mod(g/sub ..pi../(4M/sup 2/)) = 11.69 and 25.5 MeV for the ..pi..N sigma-commutator. The implications of this work for the analysis of low-energy elastic scattering of pions from nuclei are discussed. In particular, it is pointed out how this work establishes the presence of a Laplacian term in the pion-nucleus optical potential with a magnitude that is fixed from the value of the sigma-commutator.

Primarily from the point of view of improvement of yield strength due to additions of niobium, titanium and boron in HSLA steels, the experimental steels are divided into five classes. The data are then supplied for learning a Self Organising Map (Kohonen network). It is found that the network with six neurons possesses better capacity of prediction with unknown data. Another effort of clustering the steels according to its major strength contributing mechanisms is also made. But the capacity of the network to cluster unknown data is found to be rather poor and has failed to follow from the metallurgical principles. To avoid this limitation, Learning Vector Quantisation method is adopted to impart a certain amount of supervision in the learning process and it is found that the training pattern of the network attains a good convergence thereby leading to a good predictive ability.

A boron treated copper bearing HSLA steel containing austenite formers like manganese and nickel, somewhat lower in amount than that in HSLA 100 variety of steel is chosen for the study. The role of thermomechanical processing on the microstructure and mechanical properties of the above steel has been investigated. Differential scanning calorimetric study is carried out for understanding the precipitation behaviour of copper in HSLA steel under the influence of boron. The microstructure of the experimental steel is found to consist of laths of martensites and bainite. MA constituents of ribbon like morphology are observed at the lath boundaries. Higher strength properties of the steel are attributed to the presence of finely distributed precipitates of copper and microalloy carbides.