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Investigation on Temperature Sensing of Nanostructured Zinc Oxide Synthesized via Oxalate Route  [PDF]
Richa Srivastava
Journal of Sensor Technology (JST) , 2012, DOI: 10.4236/jst.2012.21002
Abstract: A detailed study is reported of the synthesis and characterization of n- type ZnO nanomaterial and its application as temperature sensor. The ZnO nanomaterial has been synthesized through pyrolysis of the oxalate produced by a conventional precipitation method. It is synthesized by flash heating the oxalate at 450°C for 15 min. Pellet of this material was prepared and used as a sensing element. The variations in resistance of sensing pellet at different temperatures were recorded. The relative resistance was decreased linearly with increasing temperatures over the range, 120°C - 260°C. The activation energy of ZnO calculated from Arrhenius plot was found 1.12 eV. Temperature response in terms of the relative variation, ΔR, of sensor resistance to a given temperature was measured. Scanning electron micrograph of the sensing element has been studied. Pellet of the ZnO is comprised of nanorods of varying diameters and different lengths. Diameter of ZnO nanorods varies from 75 to 300 nm. X-ray diffraction pattern of the sensing element reveal their nano-crystalline nature. Optical characterization of the sensing material was carried out by UV-visible spectrophotometer. By UV-Vis spectra, the estimated value of band gap of ZnO was found 4.7 eV.
PHYSICOCHEMICAL AND PHYTOCHEMICAL INVESTIGATION OF THREE DIFFERENT SPECIES OF CURCUMA RHIZOME
Negi Richa Srivastava,Bindra Rattan Lal,Srivastava Vikas Kumar,Kumar Dhirendra
International Research Journal of Pharmacy , 2013, DOI: 10.7897/2230-8407.04333
Abstract: The Zingiberaceae, the largest family in the Zingerabales, comprises nearly 50 genera and 1000 species and is pantropical concentrated mainly in the old world, chiefly in Indomalaysia. Members of the family yield species, dyes, perfumes, medicines and a number of ornamental species are cultivated for their ornamental flowers. Curcuma is one of the important ‘Rasayana’ drugs mentioned in Ayurveda. In the present study three successive extractions of plant rhizomes viz. C. amada, C. malabarica and C. zedoaria were undertaken by using various solvent like alcohol, hydro-alcohol and water in their increasing polarity and the extracts thus obtained were subjected for their phytochemical analysis, followed by Thin Layer Chromatographic examination by optimizing the solvent system.
Delay-Dependent Stability Analysis of Discrete Time Delay Systems with Actuator Saturation  [PDF]
Richa Negi, Shubhi Purwar, Haranath Kar
Intelligent Control and Automation (ICA) , 2012, DOI: 10.4236/ica.2012.31005
Abstract: This paper focuses on the study and the characterization of stability regions of discrete time systems with a time varying state delay subjected to actuator saturation through anti-windup strategies. Delay-dependent stability conditions are stated in the local as well as global context. An optimization procedure to maximize the estimate of domain of attraction is given. The proposed technique is illustrated by means of numerical examples.
Digitally Programmable Voltage Mode Universal Filters—A Minimal Realization  [PDF]
Devesh Singh, Neelofer Afzal, Dinesh Prasad, Richa Srivastava, Kuldeep Panwar
Circuits and Systems (CS) , 2015, DOI: 10.4236/cs.2015.610022
Abstract: Three voltage mode universal filter biquads using digitally programmable second generation current conveyor (CCII) are presented in this paper. Salient features of proposed filter configurations include realization of all the filter functions except allpass, independently programmable filter parameters, no component matching constraint and low sensitivity figure. Component count of proposed filter configurations is proved to be minimal for offering aforementioned set of features. Workability of proposed circuit is verified by including the SPICE simulations.
Design of Low-Voltage, Low-Power FGMOS Based Voltage Buffer, Analog Inverter and Winner-Take-All Analog Signal Processing Circuits  [PDF]
Akanksha Ninawe, Richa Srivastava, Akanksha Dewaker, Maneesha Gupta
Circuits and Systems (CS) , 2016, DOI: 10.4236/cs.2016.71001
Abstract: This paper proposes novel floating-gate MOSFET (FGMOS) based Voltage Buffer, Analog Inverter and Winner-Take-All (WTA) circuits. The proposed circuits have low power dissipation. All proposed circuits are simulated using SPICE in 180 nm CMOS technology with supply voltages of ±1.25 V. The simulation results demonstrate increase in input range for FGMOS based voltage buffer and analog inverter and maximum power dissipation of 0.5 mW, 1.9 mW and 0.429 mW for FGMOS based voltage buffer, analog inverter and WTA circuits, respectively. The proposed circuits are intended to find applications in low voltage, low power consumer electronics.
Stability Analysis of 2D Discrete Linear System Described by the Fornasini-Marchesini Second Model with Actuator Saturation
Richa Negi,Haranath Kar,Shubhi Purwar
ISRN Computational Mathematics , 2012, DOI: 10.5402/2012/847178
Abstract:
Stability Analysis of 2D Discrete Linear System Described by the Fornasini-Marchesini Second Model with Actuator Saturation
Richa Negi,Haranath Kar,Shubhi Purwar
ISRN Computational Mathematics , 2012, DOI: 10.5402/2012/847178
Abstract: This paper proposes a novel antiwindup controller for 2D discrete linear systems with saturating controls in Fornasini-Marchesini second local state space (FMSLSS) setting. A Lyapunov-based method to design an antiwindup gain of 2D discrete systems with saturating controls is established. Stability conditions allowing the design of antiwindup loops, in both local and global contexts have been derived. Numerical examples are provided to illustrate the applicability of the proposed method. 1. Introduction An important problem which is always inherent to all dynamical systems is the presence of actuator saturation nonlinearities. Such nonlinearities may lead to performance degradation and even instability for feedback control systems. The stability analysis of the continuous as well as discrete time linear systems with saturating controls has been widely considered for one-dimensional (1D) systems [1–10]. The commonly used techniques to design controllers taking into account actuator saturation are (i) constrained model predictive control [4, 11], (ii) scheduled controllers [12], and (iii) antiwindup compensators [13–18]. Model predictive controllers find applications in chemical industries for the control of systems with saturations. Scheduled controllers also called piecewise linear controller or gain scheduling schemes are often used in aerospace industry. Antiwindup compensators are widely used in practice for the control systems with saturating actuators [14, 15]. Design of antiwindup controllers can be carried out using linear design methods which explain its usefulness and popularity among control engineers. The actuator saturation problem is tackled following the “antiwindup paradigm” which employs a two-step design procedure. The main idea here is to design a linear controller ignoring the saturation nonlinearities and then augment this controller with extra dynamics to minimize the adverse effects of saturation on the closed loop performance. Several results as well as design schemes on the antiwindup problem and compensation gain are formulated and the stability conditions have been mentioned for 1D systems [7–10, 14–18]. In the recent years, two-dimensional (2D) discrete systems have found various applications in many areas such as filtering, image processing, seismographic data processing, thermal processes, gas absorption, and water stream heating [19–22]. Mathematically, a 2D discrete system is represented by a set of difference equations with two space coordinates. The stability properties of 2D discrete systems described by
Real Time Implementation of Series Expansion Based Digital Controller for Magnetic Levitation System  [PDF]
Avadh Pati, Vijay Kumar Verma, Richa Negi, Shyam Krishna Nagar
Intelligent Control and Automation (ICA) , 2016, DOI: 10.4236/ica.2016.74011
Abstract: This paper addresses a digital controller for a real time magnetic levitation system using series expansion of pulse transfer function, which achieves desired closed loop response. The proposed digital controller designed, based on series expansion of pulse transfer function by solving a linear equation using the method of least squares, which improves the transient performance and step tracking capability of the compensated system. The designed algorithm used for the control input is not iterative, so the calculation is very fast. The proposed control scheme has successfully applied on maglev system and also validated through the simulation and hardware experimental results.
Dynamics of Mandelbrot set with Transcendental Function
Shafali Agarwal, Gunjan Srivastava, Dr. Ashish Negi
International Journal of Advanced Computer Sciences and Applications , 2012,
Abstract: These days Mandelbrot set with transcendental function is an interesting area for mathematicians. New equations have been created for Mandelbrot set using trigonometric, logarithmic and exponential functions. Earlier, Ishikawa iteration has been applied to these equations and generate new fractals named as Relative Superior Mandelbrot Set with transcendental function. In this paper, the Mann iteration is being applied on Mandelbrot set with sine function i.e. sin(zn)+c and new fractals with the concept of Superior Transcendental Mandelbrot Set will be shown. Our goal is to focus on the less number of iterations which are required to obtain fixed point of function sin(zn)+c.
High-Frequency and Low-Power Output Stages Based on FGMOS Flipped Voltage Follower
Maneesha Gupta,Urvashi Singh,Richa Srivastava
ISRN Electronics , 2013, DOI: 10.1155/2013/914058
Abstract:
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