Development and Implementation of Some Controllers for Performance Enhancement and Effective Utilization of Induction Motor Drive

The technological development in the field of power electronics and DSP technology is rapidly changing the aspect of drive technology. Implementations of advanced control strategies like field oriented control, linearization control, etc. to AC drives with variable voltage, and variable frequency source is possible because of the advent of high modulating frequency PWM inverters. The modeling complexity in the drive system and the subsequent requirement for modern control algorithms are being easily taken care by high computational power, low-cost DSP controllers. The present work is directed to study, design, development, and implementation of various controllers and their comparative evaluations to identify the proper controller for high-performance induction motor (IM) drives. The dynamic modeling for decoupling control of IM is developed by making the flux and torque decoupled. The simulation is carried out in the stationary reference frame with linearized control based on state-space linearization technique. Further, comprehensive and systematic design procedures are derived to tune the PI controllers for both electrical and mechanical subsystems. However, the PI-controller performance is not satisfactory under various disturbances and system uncertainties. Also, precise mathematical model, gain values, and continuous tuning are required for the controller design to obtain high performance. Thus, to overcome these drawbacks, an adapted control strategy based on Adaptive Neuro-Fuzzy Inference System (ANFIS) based controller is developed and implemented in real-time to validate different control strategies. The superiority of the proposed controller is analyzed and is contrasted with the conventional PI controller-based linearized IM drive. The simplified neuro-fuzzy control (NFC) integrates the concept of fuzzy logic and neural network structure like conventional NFC, but it has the advantages of simplicity and improved computational efficiency over conventional NFC as the single input introduced here is an error instead of two inputs error and change in error as in conventional NFC. This structure makes the proposed NFC robust and simple as compared to conventional NFC and thus, can be easily applied to real-time industrial applications. The proposed system incorporated with different control methods is also validated with extensive experimental results using DSP2812. The effectiveness of the proposed method using feedback linearization of IM drive is investigated in simulation as well as in experiment with different working modes. It is evident from the comparative results that the system performance is not deteriorated using proposed simplified NFC as compared to the conventional NFC, rather it shows superior performance over PI-controller-based drive. A hybrid fuel cell (FC) supply system to deliver the power demanded by the feedback linearization (FBL) based IM drive is designed and implemented. The modified simple hybrid neuro-fuzzy sliding-mode control (NFSMC) incorporated with the intuitive FBL substantially reduces torque chattering and improves speed response, giving optimal drive performance under system uncertainties and disturbances. This novel technique also has the benefit of reduced computational burden over conventional NFSMC and thus, suitable for real-time industrial applications. The parameters of the modified NFC is tuned by an adaptive mechanism based on sliding-mode control (SMC). A FC stack with a dc/dc boost converter is considered here as a separate external source during interruption of main supply for maintaining the supply to the motor drive control through the inverter, thereby reducing the burden and average rating of the inverter. A rechargeable battery used as an energy storage supplements the FC during different operating conditions of the drive system. The effectiveness of the proposed method using FC-based linearized IM drive is investigated in simulation, and the efficacy of the proposed controller is validated in real-time. It is evident from the results that the system provides optimal dynamic performance in terms of ripples, overshoot, and settling time responses and is robust in terms of parameters variation and external load

Clinicopathological Study of Gastric Carcinoma with Special Reference to Helicobacter pylori

Gastric cancer (GC) is one of the most common malignancies. Although Helicobacter pylori (H. pylori) is being recognized as a Type I carcinogen for GC and primary gastric lymphoma (PGL), yet many studies especially from the Indian subcontinent do not show any such association. The aim of the study was to evaluate the clinicopathological characteristics of gastric adenocarcinoma and to determine the association of H. pylori infection. This prospective study included 50 cases of histologically proven gastric adenocarcinoma. A detailed clinical history, physical examination and upper gastrointestinal endoscopy were done in all the cases and mucosal biopsies were taken from the growth and the surrounding mucosa. Rapid urease test (RUT) was done to diagnose H. pylori infection. 50 patients of functional dyspepsia were taken as controls. GC was more common in males (70%). The maximum cases were recorded in elderly persons, mostly from 5th to 6th decades. Anorexia (60%), dyspepsia (54%) and weight loss (24%) were the commonest clinical presentation. Most of the patients presented within 3-12 month of onset of symptom. In majority of cases, the lesion was confined to the antrum (62%) and body (26%) of the stomach. H. pylori infection was more commonly isolated from the antrum. H. pylori infection was not significantly associated with GC as compared to patients with functional dyspepsia. No association was found between H. pylori infection and gastric carcinoma. Probably gastric cancer is multifactorial disease where dietary, genetic and environmental factors play contributing roles

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Analysis of the apparent nuclear modification in peripheral Pb–Pb collisions at 5.02 TeV

International audienceCharged-particle spectra at midrapidity are measured in Pb–Pb collisions at the centre-of-mass energy per nucleon–nucleon pair sNN=5.02 TeV and presented in centrality classes ranging from most central (0–5%) to most peripheral (95–100%) collisions. Possible medium effects are quantified using the nuclear modification factor ( RAA ) by comparing the measured spectra with those from proton–proton collisions, scaled by the number of independent nucleon–nucleon collisions obtained from a Glauber model. At large transverse momenta ( 8<pT<20GeV/c ), the average RAA is found to increase from about 0.15 in 0–5% central to a maximum value of about 0.8 in 75–85% peripheral collisions, beyond which it falls off strongly to below 0.2 for the most peripheral collisions. Furthermore, RAA initially exhibits a positive slope as a function of pT in the 8–20 GeV/c interval, while for collisions beyond the 80% class the slope is negative. To reduce uncertainties related to event selection and normalization, we also provide the ratio of RAA in adjacent centrality intervals. Our results in peripheral collisions are consistent with a PYTHIA-based model without nuclear modification, demonstrating that biases caused by the event selection and collision geometry can lead to the apparent suppression in peripheral collisions. This explains the unintuitive observation that RAA is below unity in peripheral Pb–Pb, but equal to unity in minimum-bias p–Pb collisions despite similar charged-particle multiplicities

Anisotropic flow of identified particles in Pb-Pb collisions at sNN=5.02 {\sqrt{s}}_{\mathrm{NN}}=5.02 TeV

The elliptic (v$_{2}$), triangular (v$_{3}$), and quadrangular (v$_{4}$) flow coefficients of π$^{±}$, K$^{±}$, $\mathrm{p}+\overline{\mathrm{p}},\kern0.5em \Lambda +\overline{\Lambda},\kern0.5em {\mathrm{K}}_{\mathrm{S}}^0$ , and the ϕ-meson are measured in Pb-Pb collisions at ${\sqrt{s}}_{\mathrm{NN}}=5.02$ TeV. Results obtained with the scalar product method are reported for the rapidity range |y| < 0.5 as a function of transverse momentum, p$_{T}$, at different collision centrality intervals between 0–70%, including ultra-central (0–1%) collisions for π$^{±}$, K$^{±}$, and $\mathrm{p}+\overline{\mathrm{p}}$ . For p$_{T}$ < 3 GeV/c, the flow coefficients exhibit a particle mass dependence. At intermediate transverse momenta (3 < p$_{T}$ < 8–10 GeV/c), particles show an approximate grouping according to their type (i.e., mesons and baryons). The ϕ-meson v$_{2}$, which tests both particle mass dependence and type scaling, follows $\mathrm{p}+\overline{\mathrm{p}}$ v$_{2}$ at low p$_{T}$ and π$^{±}$ v$_{2}$ at intermediate p$_{T}$. The evolution of the shape of v$_{n}$(p$_{T}$) as a function of centrality and harmonic number n is studied for the various particle species. Flow coefficients of π$^{±}$, K$^{±}$, and $\mathrm{p}+\overline{\mathrm{p}}$ for p$_{T}$ < 3 GeV/c are compared to iEBE-VISHNU and MUSIC hydrodynamical calculations coupled to a hadronic cascade model (UrQMD). The iEBE-VISHNU calculations describe the results fairly well for p$_{T}$ < 2.5 GeV/c, while MUSIC calculations reproduce the measurements for p$_{T}$ < 1 GeV/c. A comparison to v$_{n}$ coefficients measured in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV is also provided

Azimuthally-differential pion femtoscopy relative to the third harmonic event plane in Pb-Pb collisions at sNN\mathbf{\sqrt{\textit{s}_{_{\rm NN}}}} = 2.76 TeV

International audienceAzimuthally-differential femtoscopic measurements, being sensitive to spatio-temporal characteristics of the source as well as to the collective velocity fields at freeze out, provide very important information on the nature and dynamics of the system evolution. While the HBT radii oscillations relative to the second harmonic event plane measured recently reflect mostly the spatial geometry of the source, model studies have shown that the HBT radii oscillations relative to the third harmonic event plane are predominantly defined by the velocity fields. In this Letter, we present the first results on azimuthally-differential pion femtoscopy relative to the third harmonic event plane as a function of the pion pair transverse momentum kT for different collision centralities in Pb–Pb collisions at sNN=2.76 TeV . We find that the Rside and Rout radii, which characterize the pion source size in the directions perpendicular and parallel to the pion transverse momentum, oscillate in phase relative to the third harmonic event plane, similar to the results from 3+1D hydrodynamical calculations. The observed radii oscillations unambiguously signal a collective expansion and anisotropy in the velocity fields. A comparison of the measured radii oscillations with the Blast-Wave model calculations indicate that the initial state triangularity is washed-out at freeze out

Energy dependence and fluctuations of anisotropic flow in Pb-Pb collisions at sNN=5.02 \sqrt{s_{\mathrm{NN}}}=5.02 and 2.76 TeV

International audienceMeasurements of anisotropic flow coefficients with two- and multi-particle cumulants for inclusive charged particles in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ and 2.76 TeV are reported in the pseudorapidity range |η| < 0.8 and transverse momentum 0.2 < p$_{T}$ < 50 GeV/c. The full data sample collected by the ALICE detector in 2015 (2010), corresponding to an integrated luminosity of 12.7 (2.0) μb$^{−1}$ in the centrality range 0-80%, is analysed. Flow coefficients up to the sixth flow harmonic (v$_{6}$) are reported and a detailed comparison among results at the two energies is carried out. The p$_{T}$ dependence of anisotropic flow coefficients and its evolution with respect to centrality and harmonic number n are investigated. An approximate power-law scaling of the form v$_{n}$(p$_{T}$) ∼ p_{T}^{n}^{/3} is observed for all flow harmonics at low p$_{T}$ (0.2 < p$_{T}$ < 3 GeV/c). At the same time, the ratios v$_{n}$/v_{m}^{n}^{/ }^{m} are observed to be essentially independent of p$_{T}$ for most centralities up to about p$_{T}$ = 10 GeV/c. Analysing the differences among higher-order cumulants of elliptic flow (v$_{2}$), which have different sensitivities to flow fluctuations, a measurement of the standardised skewness of the event-by-event v$_{2}$ distribution P(v$_{2}$) is reported and constraints on its higher moments are provided. The Elliptic Power distribution is used to parametrise P(v$_{2}$), extracting its parameters from fits to cumulants. The measurements are compared to different model predictions in order to discriminate among initial-state models and to constrain the temperature dependence of the shear viscosity to entropy-density ratio