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Kinases are phosphate catalysing enzymes that have traditionally proved difficult to target against ligands,and hence inefficacious in drug development. There are two colluding reasons for this. First is the issue of specificity. The homogeneity that exists between the kinase ATP-binding pockets makes it a non-realisable target to developcompounds that would inhibit only one out of 538 protein kinases encoded by the human genome, without inhibitingsome of the others. Second, producing compounds with the required efficacy to rival the millimolar ATP concentrations present in cells is stoichiometrically inefficient. This study uses a recently propounded computational strategy based onStructure Based Virtual Screening (SBVS) that was previously benchmarked on 999 DUD-E protein decoys(Chattopadhyay et al, Int Sc. Comp. Life Sciences 2022), to rank potential ligands, or by extension rank kinase-ligand pairs, identifying best matching ligand:kinase docking pairs. The results of the SBVS campaign employing severalcomputational algorithms reveal variations in the preferred top hits. To address this, we introduce a novel consensusscoring algorithm by sampling statistics across four independent statistical universality classes, statistically combining docking scores from ten docking programs (DOCK, Quick Vina-W, Vina Carb, PLANTS, Autodock, QuickVina2,QuickVina21, Smina, Autodock Vina and VinaXB) to create a holistic SBVS formulation that can identify active ligandsfor any target. Our results demonstrate that CS provides improved ligand:kinase docking fidelity when compared to individual docking platforms, requiring only a small number of docking combinations, and can serve as a viable andthrifty alternative to expensive docking platforms.

Dry machining is receiving immense attention worldwide to eliminate or minimize the harmful environmental effects of cutting fluids. The present work investigates dry machining performance of a bil...

Lubricious WS x was codeposited with hard TiN to improve tribological property of the latter. Effects of substrate bias on structural and tribo-mechanical properties of composite coatings were investigated. Tribologically favourable (002) orientation of WS 2 diminished with increase in bias. Surface morphology became increasingly compact up to −70 V. Adhesion, hardness and tribological characteristics were strongly influenced by applied bias. At 0 V, low hardness and adhesion led to localized detachment and consequent lump formation of coating in pin-on-disc test. At −90 V, pulverisation of hard, brittle coating material was observed. Superior tribological performance at intermediate bias of −40 V has been discussed in light of balanced combination of WS x content, adhesion and hardness of the composite coating.

The paper proposes an improved low speed performance of classical rotor flux (RF)-based model reference adaptive system (MRAS) for field oriented controlled induction motor (IM) drives. The improved performance of the RF-MRAS estimator is obtained by using voltage reference vector to compute the rotor flux vector in the reference model instead of actual voltage signal vector in the process of speed estimation. The voltage reference vector is estimated by using proportional integral controller over the error signal vectors obtained from the difference between the reference and the measured current vectors. This modification allows satisfactory low or zero speed estimation of IM drive using RF-MRAS-based estimator. The proposed drive's performance is compared with classical RF-MRAS and its performance for the low-speed operation is also authenticated with ${\vec{V}^ * } \times \vec{I}$ based MRAS in MATLAB/ Simulink. Stability and sensitivity studies are further carried out to ensure the robustness of the drive system. Experimental results as obtained by a dSPACE-1104 based IM laboratory prototype are also presented to validate the simulation study.

High speed dry machining is the key manufacturing technology for higher productivity and for preserving green environment. To successfully implement this technology it is essential to understand the wear mechanism of the cutting tool engaged in high speed dry machining. Understanding of flank wear mechanism helps to design new coating material that improves the tool life. Among various types of wear taking place on cutting tool, flank wear is the most crucial one as it limits the service life of the tool. Therefore, to accomplish this goal two work materials, C20 and C80 steel were turned at 300 m/min and 600 m/min with CVD Al2O3/TiC, TiCN/TiC bilayer coated and PVD TiAlN single layer coated inserts and flank wear was studied. As the intention was to study only the wear mechanism of the top Al2O3, TiCN and TiAlN coatings, the machining was done for 15 s only to avoid any exposure of the underlayer coating or substrate. It was found that, the flank wear mechanism substantially differed for different coatings. Plastic deformation induced necking and ridge formation, grain spallation induced ridge and groove formation, dissolution-diffusion and abrasion was found to be the responsible flank wear mechanism depending on the machining environments (cutting speed and work material) and coatings. A new flank wear model was presented to explain the groove and ridge formation on Al2O3 coating.

Cubic boron nitride (cBN) abrasive grits are often brazed on steel to produce monolayer grinding wheels. Establishing a strong cBN brazement is a challenge. In the current work, performance of three different active Ag-Cu alloys have been investigated in-depth considering microstructure of alloys, interfacial reaction phase formation and wetting capability of the reaction product towards the alloy. In the current study, all three alloys contain Ti as active element but with different wt%. One of alloys was so chosen that Indium (In) was present as an additional alloying element, which is responsible for its low liquidus temperature, high Young's modulus and good ductility. Segregation of Ti towards the interface was critically examined. To evaluate joint strength, a miniature twin-ring grinding wheel was produced with these alloys. Interestingly, the alloy containing higher Ti, which required higher brazing temp, resulted in intense reaction but with inferior joint strength. On the other hand, the very presence of indium in Ag-Cu alloy, containing low wt% of Ti not only lowered the brazing temperature but also led to effective wetting and higher joint strength. Failure pattern indicates the prevalence of high residual stress at the bond level for the alloy containing the highest percentage of titanium.

The paper discusses the potential ingress and combined effect of moisture and temperature on pre-fatigued glass fibre-reinforced polymers standard test specimens. An experimental investigation was conducted to analyse the behaviour of glass fibre-reinforced polymers’ in environmental conditions similar to that of tropical environments. The standard pre-fatigued glass fibre-reinforced polymers specimens were subjected to varying hygrothermal conditions: three different temperatures, i.e. natural bath, 45 ℃ and 55 ℃ to study the degradation in strength and related properties. Several macro-structural and micro-structural tests were conducted to determine the damage. The effect of these conditions on characteristics such as diffusivity, weight gain, resin volume fraction, conductivity and deterioration of ultimate tensile strength was determined. The maximum reduction in strength is found to be approximately 39% for the specimen exposed to 55 ℃ water bath for 60 days. This study shall be helpful in estimating the characteristics of glass fibre-reinforced polymers composites subjected to cyclic fatigue loads in the tropical conditions.

This study presents a comparison between a well-known instantaneous reactive power (Q)-based model reference adaptive system (MRAS) (Q-MRAS) and a relatively new X-MRAS used for the speed estimation of induction motor drive without speed sensor from the stability point of view. Stability aspects and sensitivity analysis of both the schemes to machine parameters variation are examined. The instantaneous and steady-state values of Q are considered to develop the reference and adaptive models respectively for the former, whereas those of a fictitious quantity X (i.e. * × ) are considered in the said models for the later. Non-computation of flux in these schemes leads to the satisfactory estimation of speed over a wide range maintaining the drive's stability in all the 4-quadrants. Both the Q- and X-MRAS are found to be dependent on the rotor resistance variation, whereas X-MRAS is also influenced by the stator resistance variation. A small signal stability study over a wide range of stator and rotor resistance variations is carried out to investigate the drive's stability in the low-speed region for both the MRAS schemes. Matlab/Simulink is used to obtain the simulation results for the proposed study. Experimental results are obtained through a dSPACE-1104-based laboratory prototype.

Hard-lubricious composite coatings of TiN–WS x with pure TiN under layer were deposited by pulsed DC closed field unbalanced magnetron sputtering in Ar and N 2 mixed environment from separate Ti and WS 2 targets. The effect of WS x content on the structural, mechanical and tribological properties of the coatings was investigated. EDS analysis of the deposited films revealed that (W + S) content varied from 6.2 to 51.6 wt.%. The films were sulphur deficient with S/W at.% ratio in the range of 0.8 to 0.26. The agglomerated grain size, observed through FESEM, progressively became finer with increase in WS x content. Maximum nanohardness of 23.5 GPa was obtained for the coating containing minimum content i.e. 6.2 wt.% of WS x which gradually decreased with the increase in the WS x content. The adhesion of the coatings, evaluated through scratch adhesion test and indentation adhesion test, also improved with the WS x content up to 14.2 wt.%, after which a gradual drop was observed. The pin-on-disc tribological test, revealed lower friction coefficient and lesser wear for the composite bilayer coatings as compared to pure TiN, with the least obtained for the coating exhibiting the maximum adhesion and an intermediate nanohardness. Raman spectra suggested the presence of soft lubricious WS 2 phase in the wear debris of composite coating which resulted in less severe three-body abrasion as compared to pure TiN leading to lesser wear.

A novel hard composite solid lubricant coating combining TiN and MoSx has been developed using pulsed DC closed-field unbalanced magnetron sputtering (CFUBMS). The tribological and mechanical properties together with their interdependencies with the coating microstructures have been assessed and reported elsewhere. This article evaluates the machining performance and correlates the underlying tribological aspects of different TiN-MoSx coating architectures (deposited at titanium (Ti) cathode currents of 1, 3.5, and 5 A) when dry turning AISI 1080 high-carbon steel. A comparative performance study clearly established the supremacy of the composite coating (deposited at 3.5 A Ti cathode current with ∼12 wt% of MoSx) with a hard TiN underlayer over monolayer TiN, MoSx, and other related coating architectures in terms of cutting force, tool wear, and workpiece surface roughness. The superlubricity behavior of the said composite coated tool resulted in a reduction of cutting force (by up to ∼45% compared to the uncoated tool) and exhibited a tool life of 8 min, which was eight times and more than two times longer than that of the uncoated and conventional hard TiN coated counterparts, respectively. The workpiece surface roughness, Ra, also decreased by 13 to 21% when machined with the TiN-MoSx coated tool in comparison to the uncoated cemented carbide.

The present work reports on the structural, mechanical and tribological properties of WS 2 and WS 2 -Ti composite coating with and without hard under layer of TiN. Pulsed DC closed field unbalanced magnetron sputtering was employed for deposition of the films. The films were characterised with energy dispersive X-ray microanalysis (EDX), grazing incidence X-ray diffraction (GIXRD), field emission scanning electron microscopy (FESEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scratch adhesion test, nanoindentation test and pin-on-disc tribological test. The GIXRD spectrum for WS 2 film showed prominent orientation of (002) basal plane parallel to the substrate which was also supported by its morphology showing a fine granular structure. Addition of around 13 at.% Ti to the WS 2 matrix induced turbostratic stacking of the 10 L (L = 0, 1, 2,…) planes, however, the (002) orientation was retained. The film’s hardness, adhesion to the substrate, as well as the tribological properties improved with Ti addition. Addition of a hard under layer of TiN resulted in a denser top WS 2 -Ti layer because of enhanced nucleation promoted by structural defects of the hard under layer. The tribological performance of the top WS 2 -Ti layer also improved on TiN under layer addition because of the enhanced load bearing capacity of the top layer.

A non-invasive diagnostic technique based on tomographic reconstruction has been developed for the design optimisation of tomographic diagnostic system to be used in Indian Test Facility (INTF) neutral beam injector. The technique uses measured line integrated value of optical emissions from the beam particles using an optical detection system. The 2D spatial profile of the beam can be obtained from the tomographic inversion of the line integrated emission data. The inversion technique often constitutes an underdetermined problem because of the restricted viewing port available for installing sufficient detectors, making it difficult for direct inversion without invoking any suitable constraint. For obtaining the 2D emission profile of such a system, a tomography algorithm taking “maximum entropy” concept has been developed. The detailed theory of the algorithm and its application in INTF is presented. A suitable detection system, its components and features to obtain the line integrated data is also discussed. The quality of reconstruction of the algorithm is tested for different detector configurations. Reconstructions after adding noise to the detector signals are also obtained. An error analysis for all the reconstructions is studied and based on that the number of detectors for complete reconstruction of the beam is optimised.

An investigation was carried out to explore the grinding capability of brazed type cBN grinding wheel on two engineering steel-bearing steel and high speed steel. The grinding forces were measured and the chips were collected and the surface features of ground cBN grinding wheel were examined by SEM. The SEM photographs showed that cBN grits were distributed uniformly on the peripheral wheel. The results indicate that material removal mechanisms are different for both the steel. In spite of high hardness of the bearing steel, the brazed type wheel was grind very effectively without having any wheel loading and rise of unusual forces. But while grinding the high speed steel; the tangential forces (proportional to the specific energy) were quite high due to hot hardness of the work material. The formation of chips was favourable in different mode of grinding condition. In long duration grinding test, the surface topography showed almost unchanged i.e. no grits pull out without having any substantial fracture.

Line synchronised phase-controlled thyristor power converters produce notches in synchronising signals at the instant of turning on thyristors. These synchronising signals are derived from three-phase supply to generate gate pulses for a converter. The presence of notches leads to malfunctioning of the connected power converters whose operations decisively rely on the proper zero-crossing information of the synchronising signal. Denoising these notches is difficult because of the non-stationary pattern of the synchronising signal. The small drift of supply frequency is the main cause for this non-stationary pattern. A filtering technique based on wavelet transform (WT) is proposed in this work. The application of filtering banks using multi-resolution analysis (MRA) of discrete wavelet transform (DWT) with `Daubechies1` as mother wavelet is found effective in denoising synchronising signals from such noises. The simulation study and the experimental results are presented to justify the proposed filter structure.

The synthesis of diamond at low pressure using Hot Filament Chemical Vapor Deposition (HFCVD) method has received significant attention in recent years for the unique characteristics of diamond. Among various input parameters, chamber pressure plays an important role in controlling nucleation, growth and morphology of coating. In this investigation, the morphology of diamond was analyzed after (1) pretreatment with acid, (2) pretreatment with acid and without diamond seeding and (3) pretreatment with acid and seeding. Keeping other input parameters constant the chamber pressure varied from low pressure (0.133 kPa) to high pressure (6.666 kPa). The variation of the crystal size with different input parameters were studied with Scanning Electron Microscope (SEM) micrographs and Raman spectroscopy. It was observed that cobalt inhibited diamond growth on the received carbide insert. Pretreatment with acid without seeding has improved diamond morphology. The pretreatment with acid and diamond powder seeding has improved diamond coating significantly.

According to some patented literatures, grit pull-out in single layer galvanic wheels can be arrested by a physical vapor deposited (PVD) coating on the wheels. It has been assumed, therein, the uniform high energy bombardment of TiN caused a reinforcement of the bond as well as increased the stability of the cBN layer on the core. However, an in-depth study on the performance of PVD coated grinding wheel is still lacking. The present research deals with exploring the effect of grinding parameters and substrate bias voltage on the performance of TiN coated galvanic cBN wheels compared to their uncoated counterpart in dry surface grinding of AISI 52100 hardened bearing steel. TiN was deposited at the bias voltages of 0, −60, and −90 V in an in-house PVD coating system. The coating microstructure and post-grinding condition of the wheels were observed using scanning electron microscopy (SEM) and phase detection was carried out using grazing incidence X-ray diffraction (GIXRD). With the increase in negative ...

This study deals with the effect of coating thickness on the characteristics and dry machining performance of TiN film deposited on cemented carbide inserts using closed-field unbalanced magnetron sputtering (CFUBMS). The turning inserts were coated with TiN film of varying thickness ranging from 1.8 µm to 6.7 µm. The deposited coatings were characterized using grazing incidence X-ray diffraction (GIXRD), Vickers and Knoop microhardness tester, and scratch tester. The machining performance of uncoated and coated carbide inserts was evaluated in dry turning of C40 steel. The in-house developed TiN-coated carbide insert exhibited around 16 times higher tool life compared to that of the uncoated insert. Performance test clearly showed the weakness of the uncoated K-type carbide relative to its TiN coated counterpart in machining of long chipping material like C40 steel. The present investigation clearly reveals that the developed TiN-coated tool has a potential for augmenting the cutting capability of uncoat...

Chip formation in grinding involves high specific energy compared to other machining processes due to high negative rake angle of grains, adverse grinding process parameters and physical–mechanical properties of the workpiece material. This causes excessive friction between chip-grit and chip-bond interfaces as there are no free flow of chip between grits and work surface. It generates high heat, which can have harmful effects on workpiece surface in case of dry grinding. But single layer brazed type (BT) or galvanic bonded (GB) cBN wheel could be the solution for the above mentioned problem, as the protrusion and gap of the grits may be monitored during manufacturing. Unlike conventional grinding, the single layer counterpart produces favorable chips during grinding bearing steel in ductile mode with lesser grinding forces and specific energy. This investigation also shows that the chips of larger volume cannot be accommodated in the intergrit spaces, which are very small in the GB wheel due to dense gri...

Grinding of low-carbon steel often exhibits severe wheel loading due to the formation of long chips and high adhering tendency of the work material with the grits. Conventional composite-type alumina wheels are commercially utilised for grinding low-carbon steel. However, the actual nature of grit wear cannot be truly understood in a composite wheel. The truing and dressing conditions also have some influences on the wear mechanism. Therefore, in order to explore the wear pattern on a single layer of grits, monolayer brazed cBN, white and grey Al2O3 wheels were used in the present study. The grindability of AISI 1020 steel was evaluated under dry, liquid nitrogen and neat oil environments. The surface profile of the workpiece after being ground in each environmental condition was traced with a surface profilometer to reveal the mechanism of grit wear. The post-grinding conditions of the wheels were observed using scanning electron microscopy. The cBN wheel was found to outperform the alumina wheels in terms of grinding forces and grit wear. The wear of the cBN wheel was remarkably arrested with the application of neat oil. On the other hand, large-scale adhesion and breakage of grits in white alumina wheel were observed under cryogenic environment. In fact, the beneficial role of liquid nitrogen could not be realised in reducing grinding forces and grit wear with all the three types of wheel. A lubricating agent like neat oil appeared to be more suitable than cryogenic cooling when grinding low-carbon steel.

The monolayer grinding wheels, coated with a physical vapour deposited (PVD) coating (viz. TiN, HfN, TiN + ZrN etc.), have been reported to outperform their uncoated counterparts as claimed in some patented literatures. The present work aims at exploring the mechanism how PVD TiN augments the performance of nickel electroplated monolayer superabrasive wheels. This study also includes the effect of negative substrate bias voltage on performance of TiN coated electroplated cBN wheels during grinding of hardened bearing steel. TiN was deposited by pulsed DC closed-field unbalanced magnetron sputtering (CFUBMS) technique in an in-house PVD coating system. The structure of the TiN coating and post-grinding condition of the wheels were observed using scanning electron microscopy (SEM). Energy dispersive X-ray (EDX) line scan, Electron probe micro analysis (EPMA) and secondary ion mass spectrometry (SIMS) depth profiling at the junction of TiN and nickel layer indicated the occurrence of inter-diffusion between them and grazing incidence X-ray diffraction (GIXRD) confirmed the formation of Ni–Ti intermetallic phases at their interface. The scratch test revealed a significant increase in cohesive and adhesive strengths of nickel layer when TiN was deposited at a bias voltage of −60 V or beyond that. The uncoated cBN wheel exhibited large number of grit fracture at the bond level and some grit pull-out. Such failures of grit were significantly arrested with TiN coating deposited at the bias voltages of −60 V and −90 V.

In the present investigation, AA6005 (ISO: AlSiMg) alloy was machined in turning operation with different cutting tools, such as uncoated cemented carbide insert, PVD TiN coated, CVD diamond coated and PCD insert, under dry environment. Effect of cutting speed was studied for each of the cutting tools with regard to the formation of built-up layer (BUL) or built-up edge (BUE). The rake surface of the tools was characterized by optical microscopy, scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopic microanalysis. Particular emphasis was given on wear mechanism of PVD TiN coated insert, conventionally used in machining ferrous alloys, during dry turning of AA6005 alloy. It has been observed that increase of cutting speed from 200 m/min to as high as 1000 m/min could not substantially reduce formation of BUL over tool rake surface during dry machining of AA6005 alloy with uncoated or PVD TiN coated cemented carbide inserts. The potential of diamond-based tools in dry machining ...

The present research involves the deposition of pulsed DC CFUBM sputtered TiN on nickel plated steel discs and electroplated monolayer cBN wheels at seven different target frequencies and ten different bias voltages separately. The coating microstructures and the interaction between TiN and nickel were studied using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and electron probe micro analysis (EPMA). Phase detection was carried out using grazing incidence X-ray diffraction (GIXRD) technique. The cohesive and adhesive strengths of nickel layer were assessed by scratch test. After grinding of low carbon steel (AISI 1020) and hardened bearing steel (AISI 52100), the conditions of the uncoated and coated cBN wheels were observed under Stereo Zoom Microscope and SEM. Average column size of TiN was found to decrease with increase in both target frequency and negative bias voltage. The structure of the coating gradually transformed from porous and open columnar (at 0 V bias) to very compact, dense and featureless (at − 80 V bias). EDX line scan and EPMA confirmed the cross-diffusion between TiN and nickel and GIXRD indicated the formation of nickel–titanium intermetallic phases at their interface. The cohesive strength of nickel layer was not effectively enhanced with increase in target frequency, whereas the same was significantly improved with increase in negative bias voltage. Seemingly, TiN coated wheel could not perform better than the uncoated wheel in grinding AISI 1020 steel due to high wheel loading. However, the uncoated wheel was found to undergo fracture wear, which was remarkably absent in the coated wheels. On the other hand, many fractured grits and some grit pull-out were observed in the uncoated wheel when grinding AISI 52100 steel, whereas almost no pull-out along with much less fractured grits were observed in the wheels coated at bias voltages like − 60 V and − 90 V.

Application of MoS2-based solid lubricant has extreme potential as a coating material of cutting tools because of its superlubricity against most of the engineering materials. However, a detailed study on the effect of such lubricious coating in grinding has never been carried out before. In the present research, the tribological behaviour of MoS2-Ti composite coating with TiN underlayer on electroplated nickel and braze alloy was investigated separately in comparison to TiN coated and uncoated counterparts. Grinding of AISI 52100 steel was also carried out with uncoated, TiN coated and MoS2-Ti coated (with TiN underlayer) monolayer (both electroplated and brazed) cBN wheels. The structure of the coatings and the condition of the grinding wheels were observed under SEM. In tribology test, MoS2-Ti composite coating was found to be best performing on both nickel and braze alloy in terms of coefficient of friction and depth of the wear track. Minimum variation in normal force and remarkably steady behaviour of tangential force were obtained with both MoS2-Ti coated electroplated and brazed wheels over the total experimental run. Large number of grit fracture at and above bond level with some amount of grit pull-out was observed in uncoated electroplated wheels. Uncoated brazed wheels have undergone grit breakage at bond level. However, such failures of grit were significantly arrested with both TiN and MoS2-Ti composite coatings.

TiN–MoS x composite coatings were deposited by pulsed DC closed-field unbalanced magnetron sputtering (CFUBMS) using separate Ti and MoS 2 targets in an Ar and N 2 gas environment. The effect of substrate bias voltage on the structure and mechanical properties of TiN–MoS x composite coating has been studied. The structure and composition of the coating were evaluated using field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS) by X-ray and grazing incidence X-ray diffraction (GIXRD). Scratch adhesion tests, Vickers microhardness tests and ball-on-disc tests with a cemented carbide (WC-6%Co) ball were carried out to investigate mechanical properties of the coating. Application of substrate bias was found to transform the structure of TiN–MoS x composite coating from open columnar to a dense columnar structure. The changes in grain size and texture coefficient appear to be associated with variation in substrate bias voltage. The mechanical properties of the coating such as adhesion and composite microhardness were also observed to be related to the change in bias voltage. A maximum hardness of 22 GPa was obtained for a coating deposited at substrate bias voltage of −40 V. The improved structural and mechanical properties of the coating deposited at −40 V were also reflected in its excellent wear resistance property.

In the current study, TiN–MoS x composite coatings were deposited by co-sputtering of MoS2 and Ti targets under a mixture of Ar and N2 gas environment using pulsed DC closed-field unbalanced magnetron sputtering. The tribological response of TiN–MoS x composite coatings was studied against two different counter bodies: cemented carbide (WC–6% Co) ball and pin made of aluminium alloy (AlSiMg). First, the effect of substrate bias was studied on tribological properties using cemented carbide ball. Lowest coefficient of friction in the range of 0.03–0.04 was obtained for the specimen deposited at a substrate bias of −60 V. Wear coefficient was also found to be minimum for the same specimen. Coatings were further deposited at an optimum bias of −60 V in order to vary MoS x content of TiN–MoS x composite coating. Effect of variation of chemical composition of the coating was then studied on tribological performance of the coating against aluminium alloy counterface. Excellent anti-sticking property of MoS x was found to have enabled the TiN–MoS x composite coating to achieve considerably low coefficient of friction against aluminium alloy. It was shown that with optimum MoS x content of TiN–MoS x composite coating, it was possible to attain as low coefficient of friction as 0.09 against aluminium alloy even under normal atmospheric condition.

The wide application of aluminum in different industries has increased the need for finding the suitable cutting tool. In contrast to ferrous materials, the dry machining of aluminum is a great challenge. Wetting test is widely used to find out the chemical affinity of aluminum with different tool materials before proceeding for actual machining. Wettability tests were carried out in a high vacuum brazing chamber to find out the spreadability of aluminum on cutting tools. Mono or multilayer coated carbide tools with a top coating of TiC, TiN, Al2O3, TiB2, MoS2 and diamond on cemented carbide (WC–Co) cutting tool inserts were used in the experiment. The results revealed that diamond/graphite is the most inert for aluminum.

This work reports on the morphological, mechanical and wear properties of MoS x –TiN composite films, deposited by closed-field unbalanced magnetron sputtering (CFUBMS) process applying pulsed DC power supply simultaneously to the targets and substrate bias. The structure of the coating was studied using grazing incidence X-ray diffraction (GIXRD), field emission scanning electron microscopy (FESEM) and energy dispersive X-ray (EDX) microanalysis. EDX analysis showed presence of around 30% Ti in the composite matrix. Presence of MoS x peak in GIXRD profile confirmed the presence of MoS x as a compound, not as elemental Mo and S. One improvement of the composite architecture was attempted by combining the composite architecture with hard TiN underlayer and soft MoS x top layer. The adhesion, hardness and wear properties were studied by scratch test, Rockwell and Vickers indentation and pin-on-disc test respectively. Adhesion was found to be improved in the composite architecture compared to pure MoS x and TiN coating. The composite architecture also showed superior tribological performance as compared to pure MoS x and TiN coatings.

An investigation has been undertaken to study the compatibility of cutting materials in dry machining of aluminium and Al–Si alloys. Mono or multilayer coated carbide tools with a top coating of TiC, TiN, TiAlN, Al2O3, TiB2, MoS2 etc. on WC–Co inserts already made a major breakthrough in dry machining of ferrous materials. But in contrast dry machining of aluminium and Al-alloys is a great challenge. But wide application of aluminium different parts has increased the need to find out the correct cutting tool. Experimental results of turning test, SEM pictures and chip morphology investigation of the cutting tool after machining clearly reveals the inefficiency of TiC, TiN, TiB2, Al2O3, and AlON in dry machining of aluminium. This is because of the formation of very large amount of metal built-up in both rake and flank surface leading to high magnitude of cutting forces and high roughness of the work-piece during machining. The natural diamond and polycrystalline diamond (PCD) can be used as a cutting tool, when the required shape is attached on the edge/tip for machining non-ferrous materials. But both of them are limited for finishing cut because of high cost. So CVD diamond coated tool is a better option to machine these materials. CVD diamond coated tool was free from built-up edge formation leading to clean cut, low magnitude of cutting forces and improved surface finish of the work-piece. However, performances of the diamond tool depend mainly on adhesion of the diamond coating with the carbide substrate.

Effect of MoS x content has been studied in TiN–MoS x composite coating deposited by closed-field unbalanced magnetron sputtering (CFUBMS) using separate MoS 2 and Ti target in N 2 gas environment. Pulsed dc power was applied for both the targets as well as for substrate biasing. Crystallographic orientation and structure of the coating was analysed by grazing incidence X-ray diffraction (GIXRD) technique. The surface morphology and coating fractograph were studied with field emission scanning electron microscopy (FESEM) whereas the composition of the coating was determined by energy dispersive spectroscopy (EDS) by X-ray. Scratch adhesion test, Vickers microhardness test and pin-on-disc test with cemented carbide (WC–6%Co) ball were carried out to investigate mechanical and tribological properties of the coating. Increase in MoS x content (from 6.22 wt.% to 30.43 wt.%) was found to be associated with decrease in grain size (from 63 nm to 24 nm). Maximum hardness of 32 GPa was obtained for TiN– MoS x composite coating. Film substrate adhesion was also observed to depend on MoS x content of the composite coating. Significant improvement in tribological properties was observed. With optimal MoS x content, it was possible to achieve low friction ( µ = 0.02–0.04) and wear resistant (wear coefficient = 5.5 × 10 − 16 m 3 /Nm) composite solid lubricant coating.

An investigation has been conducted to study wetting characteristics of aluminium towards different cutting tool materials for assessing the compatibility for dry machining of aluminum. For this purpose uncoated carbide (94%WC + 6%Co) and mono or multi-layer coated carbide tools with top coating of TiC, TiN, Al 2 O 3 and diamond have been used. It was observed that aluminium had a tendency to wet uncoated carbide (94%WC + 6%Co) inserts. However, wetting was more pronounced when surface was enriched with cobalt. In contrast, wetting of aluminium was less when the WC content of the carbide tool surface increased. Coatings like TiC, TiN or Al 2 O 3 could not show pure non-wetting characteristics for aluminium. The aluminium appeared to dissolve the coatings in different degrees. On the other hand, coating of diamond exhibited inertness towards aluminum leading to non-wetting behaviour. Turning test with aluminium indicated heavy material built up on uncoated (94%WC + 6%Co) tool. Built up edge formation could not be avoided when carbide inserts with a top coating of TiC, TiN, Al 2 O 3 were engaged in machining of aluminium. However, the non-wetting characteristic of diamond coating was reflected during machining of aluminium. The chips slided smoothly over the rake face leaving no trace of edge built up.

One of the major steps in diamond deposition on tungsten carbide cutting tools by the CVD method is nucleation of diamond precursors on the substrate surface. Application of substrate biasing is one of the promising techniques for the enhancement of nucleation in HFCVD diamond coating. The objective of the present work is to study the effect of negative bias voltage to the substrate on the morphology and adhesion of the diamond coating to the substrate and to test the performance of the coated tool in machining. The beneficial effect of negative substrate bias at definite system pressure range towards achieving favourable coating having high nucleation density and good uniformity, ultimately leading to better machining performance has been confirmed.

The direct deposition of diamond on carbide tools is difficult because formation of graphitization and thus leading to poor adhesion, due to presence of cobalt on the surface. Various methods were adopted to suppress the effect of cobalt during deposition. One of them was by putting an interlayer. In this study, carbide substrates with coatings of Ti, TiN and TiC were used. Ti coating has a strong tendency to form intermediate carbide leading to the highest nucleation density of diamond. A comparison was made on nucleation and growth of diamond crystals on various interlayers by hot filament CVD method. At the same time, the variations of diamond film growth morphology have been studied on unseeded and seeded carbide inserts. The SEM pictures revealed that among interlayer, Ti coating gave highest nucleation density compared to TiN and TiC coatings. At the same time, diamond seeded inserts, pretreated by Treat 1 [HCl + HNO 3 + H 2 O (1:1:1)] for 15 min ultrasonically resulted in the highest nucleation density, compared to Treat 2 [K 3 [Fe(CN) 6 ] + KOH + H 2 O] solution in (1:1:10) for 15 min, at constant process parameters.

In the present investigation, diamond coating was deposited on cemented carbide substrate by hot filament chemical vapour deposition. The effect of substrate pretreatment methods and chamber pressure on morphology, quality, and adhesion of the diamond film were studied. The carbide inserts were pretreated with acid, Murakami's solution, and Murakami's solution followed by acid, respectively. The chamber pressure was set at 6.6, 13.2, 26.4, 39.6 and 66 mbar. Deposition carried out at pressure of 26.4 and 39.6 mbar on inserts pretreated with acid exhibited uniform crystal habit and provided coating-substrate adhesion adequate for machining application. Good coating morphology was obtained when deposition was done at 6.6 mbar on carbide inserts treated with Murakami's solution. Pretreatment with Murakami's solution followed by acid and deposition at 6.6 mbar also resulted in good morphology of diamond film. Indentation (Rockwell C scale) was done on diamond-coated inserts to assess coating-substrate adhesion under three loads of 294, 588 and 980 N. The diameter of the indentation crack at the coating-substrate interface was observed under SEM. The results suggested that diamond coating deposited at medium pressure of 26.4 mbar on carbide substrate treated with acid not only exhibited best morphology but also highest coating-substrate adhesion and improved machining performance.

This work investigated the effectiveness of TiN coating in enhancing the performance of two different types of single-layer cBN grinding wheels. One was galvanically bonded type where galvanic metal layer covered less than 50% of the grit height. In this paper, it is termed as underplated wheel. The other one was brazed cBN wheel which was developed in-house. In this case, the grits were bonded by a braze alloy layer. TiN coating, well known for its anti-wear and anti-friction characteristics, finds use in cutting tools and tribological applications. In this case study, such TiN was successfully deposited on the above-mentioned two types of grinding wheels with a dual cathode closed-field unbalanced magnetron sputtering (CFUBMS) system. Performance of those TiN-coated wheels was compared with that of uncoated counterparts in terms of grinding force and percentage of grit failure. Grinding tests were carried out in plunge mode and under dry condition. Experimental results clearly revealed the fact that the role of TiN coating was not that significant in reducing the friction at the wheel-workpiece contact zone. However, it was able to substantially reduce grit pullout of the underplated cBN wheel. On the other hand, uncoated brazed cBN wheel did not suffer from grit pullout, but severe premature breakage of cBN grits at the bond level was observed. This was remarkably arrested when TiN coating was applied on the active surface of the wheel.

Electroplated single-layer grinding wheels, in spite of offering unique useful features like geometrical flexibility, large chip accommodation volume in the inter-grit space, etc., produce high transverse surface roughness on the ground surface of the workpiece. Non-participation of all the superabrasive particles (grits) attributes to this limiting factor. Moreover, in plunge grinding the situation is the worst to deal with. This work is an attempt to reduce the same to an acceptable magnitude so that post-grinding finishing operations can be executed effectively. However, this procedure has been implemented on indigenously developed brazed-type single-layer cBN wheels. This class of grinding wheel has been found superior to its galvanically bonded counterpart in the view of larger grit protrusion and flexibility to print any pattern of grit distribution. In this investigation, brazed cBN wheels with different grit distribution patterns have been conditioned by touch-dressing method so that grit tips get micro-conditioned and allow the underlying grits to participate and consequently increase the quality of finish. The outcome of this attempt appeared highly encouraging. A substantial improvement of transverse surface roughness could be achieved with all three categories of brazed wheels and the role of grit distribution pattern in obtaining good finish was thoroughly investigated.

The present work deals with a single layer brazed type cBN grinding wheels, which have been developed in-house. Grits were actively brazed on the working surface of the wheels in a regularly distributed pattern so that it could perform grinding without loading. In general, such a wheel produces substantially high transverse roughness. This happens because of its low active grain density. A touch-dressing technique, developed in-house, has been successfully applied on these brazed wheels so that most of the grits did participate and the average roughness could be brought down to an acceptable magnitude. This work investigated the co-relation between the grit size and cumulative depth of dressing required to achieve an acceptable magnitude of transverse roughness. It was found that the required cumulative depth of dressing was dependent on the size of cBN grits. This paper also shows the effect of gradual touch-dressing on improvement of roughness of the surface ground by such new class of recently develope...

Ataxia and peripheral neuropathy are the most common neurological manifestations of gluten sensitivity. Myopathy is a less common and poorly characterized additional neurological manifestation of gluten sensitivity. We present our experience with 13 patients who presented with symptoms and signs suggestive of a myopathy and in whom investigation led to the diagnosis of gluten sensitivity. Three of these patients had a neuropathy with or without ataxia in addition to the myopathy. The mean age at onset of the myopathic symptoms was 54 years. Ten patients had neurophysiological evidence of myopathy. Inflammatory myopathy was the most common finding on neuropathological examination. One patient had basophilic rimmed vacuoles suggestive of inclusion-body myositis. Six patients received immunosuppressive treatment in addition to starting on a gluten-free diet; five improved and one remained unchanged. Among seven patients not on immunosuppressive treatment, four showed clinical improvement of the myopathy with a gluten-free diet. The improvement was also associated with reduction or normalization of serum creatine kinase level. The myopathy progressed in one patient who refused the gluten-free diet. Myopathy may be another manifestation of gluten sensitivity and is likely to have an immune-mediated pathogenesis. A gluten-free diet may be a useful therapeutic intervention.

High quality performance of vector controlled induction motor (IM) drives to a large proportion depends upon the rotor resistance which varies significantly with temperature notably at low speed. Many techniques are proposed till date but, model reference adaptive controller (MRAC) is one of the ace methods among the numerous due to its performance and straightforward stability approach. The rotor flux (RF) -error based MRAC consists of two models, viz. reference and adaptive models used simultaneously to estimate the d-q components of the rotor flux using IM line currents and voltages. However, in the case of conventional RF-MRAC based drive, the accuracy of the measured voltage drastically falls because of the significant amount of voltage drop across the stator resistance in the low speed region. To overcome this limitation, in this paper, the d-q components of the stator voltages are computed using the error signal between the reference and measured d-q current components with Proportional Integral (PI) controllers and representing the relevant equations in the synchronously rotating frame. Hence, instead of using voltage and current sensors, only current sensor is required in the proposed scheme. Thus, the proposed RF-MRAC based drive performs satisfactorily at the low speed as direct dependence on the measured voltage is eliminated. The proposed drive's performance with the RF-MRAC is validated for various speed ranges and patterns, both by Matlab simulation and experimental verification. A stability study in all the four quadrants of drive's operation and sensitivity study against motor parameter variations are carried out in Matlab/ Simulink. Experimental results obtained by a dSPACE-1104 based laboratory prototype are presented in the paper.

This paper proposes a simplified analytical averaged model of a thyristorized commutatorless series motor. The motor operation is generally complicated due to the complexities present in the three-phase synchronous machine used and the nonlinearities introduced by the switching operation of the power electronic converter that is feeding the electrical machine. The simple analytical model is formulated in light of a conventional dc series motor and is found to be approaching the simplicity of a conventional dc series motor both in dynamic condition and steady state. The developed simplified model is found to yield results closely tallying with those obtained from a "detailed numerical model" developed earlier, which is totally numerical in nature. The results are also validated experimentally on a small laboratory-built prototype. The developed model lays the foundation of controlling the motor for different industrial loading applications. One such application, viz., constant torque loading, is considered to show that the control strategy adopted on the basis of the discussed model works satisfactorily to develop a constant torque according to a given torque reference irrespective of load disturbances

High-power synchronous motor drives are usually fed from naturally commutated cycloconverters. The output voltage of the cycloconverter contains interharmonics/subharmonics which affect the power quality and restrict the allowable frequency range. Further, a practical circulating current-free cycloconverter usually gives rise to stator current discontinuities. The present paper deals with a simulation method to study the performance of a cycloconverter-fed synchronous motor drive in the presence of interharmonics/subharmonics taking into account the discontinuities in the output current as well as the effect of ripple in the output current on the input current of the cycloconverter. Interharmonics in output phase voltage, output phase current, input supply current, and the field current are estimated and verified with experimental results on a laboratory prototype. The significant oscillating torque components due to these interharmonics are identified in a typical case. The simulation results are useful in power quality studies for such drives and in devising methods for suppression of these interharmonics/subharmonics.

This paper presents a comparative study between a wellknown instantaneous reactive power (Q) based MRAS (QMRAS) and a relatively new X-MRAS used for sensorless speed estimation of induction motor drive from the stability point of view. The instantaneous and steady state values of Q are considered to develop the reference and adaptive models respectively for the former whereas those of a G fictitious quantity X (i.e., vrarro*×ī) are considered in the said models for the later. Non computation of flux in these schemes makes the speed estimation possible over a wide speed range maintaining the drive's stability in all the 4-quadrants. Moreover, Q-/X-MRAS are dependent on rotor resistance variation whereas X-MRAS is also influenced by the stator resistance variation. A small signal stability analysis over a wide range of stator and rotor resistance variations is carried out to ensure the drive's stability for both MRASs. Matlab/Simulink is used to carry out the proposed study and results are being validated in a prototype experimental setup using dSPACE 1104 controller.

The paper presents a short-switch fault diagnosis scheme for a cascaded five-level inverter with phase disposition PWM using Discrete Wavelet Transform (DWT) and Artificial Neural Network (ANN). The Multi Resolution Analysis (MRA) property of DWT is used for the extraction of the detailed components form the inverter line-to-line voltage and subsequently, these are used for the computation of energy at each level. Additionally, various voltage ratios from the line-to-line voltage are computed. In fact, line-to-line voltage is independent of the nature of load and hence, it is considered as the analysing signal. The voltage ratios together with the calculated energies are considered as the important features for the ANN training for short-switch faults. The whole scheme is implemented by simulation in Matlab/ Simulink. The simulation results show that the scheme successfully identifies the short switch fault for any switch health conditions. Moreover, the scheme is simple and does not involve too many computations. This ensures the real time applicability of the proposed algorithm in any fast acting digital signal processor. The scheme is universal and can be applied to any other inverter topology as well.

This paper presents a simplified analytical model of a silicon-controlled-rectifier based, load-commutated inverter driven, commutatorless series motor to predict its speed-current, torque-current and torque-speed characteristics. The model has been formulated, keeping in view the steady state equivalent circuit of a conventional DC series motor. The proposed analytical expressions relating torque and current with speed are found to follow an inverse law and that relating torque and current is found to be parabolic, as is expected in a "series" machine. The drive has been implemented, loaded with a DC generator and experimentally similar characteristics have been obtained, as predicted by the analytical model. The characteristics obtained experimentally are seen to follow the ones, predicted by the analytical model closely.

Childhood disintegrative disorder (CDD) (ICD-10 F84.3) is defined by a period of normal development before onset followed by gradual loss of previously acquired skills with the development of characteristic abnormalities of social, communicative and behavioural functioning. We report two children with apparent CDD, who showed amelioration of behaviour, language and motor regression after corticosteroid treatment.

The paper presents an iterative solution for the problems related to steady state performance of self-excited induction generators operating in parallel. The analysis is based on voltage and current balance equations derived from an inverse-model for the steady state equivalent circuit of induction machines. The nonlinearity in the magnetization characteristics has been taken into account by piecewise linearisation. The proposed method is general and can be applied for analysis of any number of parallel connected machines. Theoretical predictions and experimental results are presented to study different performance characteristics of the system.

Summary Background Ataxia is the commonest neurological manifestation of coeliac disease. Some individuals with genetic susceptibility to the disease have serological evidence of gluten sensitivity without overt gastrointestinal symptoms or evidence of small-bowel inflammation. The sole manifestation of disease in such patients may be ataxia. We describe the clinical, radiological, and neurophysiological features of this disorder. Methods Patients with ataxia attending the neurology outpatient clinics at the Royal Hallamshire Hospital, Sheffield, UK, were screened for gluten sensitivity as shown by the titre of antibody to gliadin. Those with other causes of ataxia were excluded. We carried out clinical, neurophysiological, neuroradiological, and, in two cases, neuropathological examinations. Findings 28 patients with gluten ataxia were identified. All had gait ataxia and most had limb ataxia. Those with more severe gait ataxia had longer disease duration. No patient had tremor or other extrapyramidal features. 19 patients showed some form of peripheral neuropathy on neurophysiological examination. 16 patients had no gastrointestinal symptoms. Distal duodenal biopsy showed lymphocytic infiltration in two patients, and changes compatible with coeliac disease in 11. Six patients had evidence of cerebellar atrophy on magnetic-resonance imaging. Necropsy was done on two patients who died; there was lymphocytic infiltration of the cerebellum, damage to the posterior columns of the spinal cord, and sparse infiltration of the peripheral nerves. Interpretation Gluten sensitivity is an important cause of apparently idiopathic ataxia and may be progressive. The ataxia is a result of immunological damage to the cerebellum, to the posterior columns of the spinal cord, and to peripheral nerves. We propose the term gluten ataxia to describe this disorder.

A novel method of online detection and frequency-selective feedback to suppress the subharmonic frequency components in a naturally commutated cycloconverter is described. Simulation results show a significant reduction of these components over a wide range of frequency and load power factor angle. The scheme also includes a loop for compensating the voltage distortion due to discontinuous current in a practical noncirculating-type cycloconverter.