Robust sensor fault estimation scheme for satellite attitude control systems

The present paper proposes two new schemes of sensor fault estimation for a class of nonlinear systems and investigates their performances by applying these to satellite control systems. Both of the schemes essentially transform the original system into two subsystems (subsystems 1 and 2), where subsystem-1 includes the effects of system uncertainties, but is free from sensor faults and subsystem-2 has sensor faults but without any uncertainties. Sensor faults in subsystem-2 are treated as actuator faults by using integral observer based approach. The effects of system uncertainties in subsystem-1 can be completely eliminated by a sliding mode observer (SMO). In the first scheme, the sensor faults present in subsystem-2 are estimated with arbitrary accuracy using a SMO. In the second scheme, the sensor faults are estimated by designing an adaptive observer (AO). The sufficient condition of stability of the proposed schemes has been derived and expressed as a linear matrix inequality (LMI) optimization problem and the design parameters of the observers are determined by using LMI techniques. The effectiveness of the schemes in estimating sensor faults is illustrated by considering an example of a satellite control system. The results of the simulation demonstrate that the proposed schemes can successfully estimate sensor faults even in the presence of system uncertainties.     

Effect of Arsenic Contaminated Drinking Water on Human Chromosome: A Case Study

Arsenic contamination of ground water has become a serious problem all over the world. Large number of people from Uttar Pradesh, Bihar and West Bengal of India are suffering due to consumption of arsenic contaminated drinking water. Study was carried out on 30 individuals residing in Ballia District, UP where the maximum concentration of arsenic was observed around 0.37 ppm in drinking water. Blood samples were collected from them to find out the problem related with arsenic. Cytogenetic study of the blood samples indicates that out of 30, two persons developed Klinefelter syndrome.     

I CARE: Development and Evaluation of a Campus Gatekeeper Training Program for Mental Health Promotion and Suicide Prevention

Addressing the need for suicide prevention on campus, I CARE training, developed and facilitated by counseling center clinicians, trains students, staff, and faculty to provide support to students experiencing distress or mental health problems. We assessed its impact using a mixed-methods approach. Quantitative analyses demonstrated significant increases in knowledge of intervention skills and readiness to intervene from pretraining to posttraining. Knowledge and readiness remained significantly higher than preworkshop for the entire follow-up evaluation period, extending 15 months posttraining. Qualitative analyses revealed the value of experiential activities and emotional processing in increasing participants’ comfort and preparedness to intervene in challenging situations.     

Effect of processing parameters on the electromagnetic radiation emission during plastic deformation and crack propagation in copper-zinc alloys

INTRODUCTION The physics of plastic deformation and crack propagation at atomic level is complex but is essential for the development of new materials. This requires an understanding of the atomic level phenomena associated with the plastic deformation. In this con- text, emission of electromagnetic radiation (EMR) during plastic deformation and crack propagation in metals and alloys, and generation of transient mag- netic fields during crack initiation in ferromagnetic materials are rep…     

Identification of strategy parameters for particle swarm optimizer through Taguchi method

INTRODUCTION The particle swarm optimization (PSO) method is a member of the broad category of swarm intelli- gence techniques for finding optimized solutions. The PSO algorithm is based on the social behavior of animals such as flocking of birds and schooling of fish, etc. PSO has its origin in simulation for visual- izing the synchronized choreography of bird flock by incorporating concepts such as nearest-neighbor ve- locity matching and acceleration by distance (Par- sopoulos and V…     

Theorema aureum — 2

In the first part of this article, we had introduced the notion of quadratic reciprocity and dwelt briefly on its history, which goes back all the way to the work of Fermat. Then we discussed the Law of Quadratic Reciprocity (‘QRL’), which Gauss named Theorema Aureum. Following this, we gave a not too well known proof of the QRL, due to G Rousseau. Now we give two more proofs of the QRL, drawing respectively from ideas in linear algebra and field extensions; they too are not very well known. Shivam Kumar graduated from Indian Statistical Institute, Bangalore and is joining the London School of Economics for MSc in applicable mathematics. His interest lies in expanding the existing applied paradigm of mathematics from stock market to unchartered subjects such as sociometrics.     

Chemistry at the Nanoscale

Traditionally the kinetics of a chemical reaction has been studied as a set of coupled ordinary differential equations. The law of mass action, a tried and tested principle for reactions involving macroscopic quantities of reactants, gives rise to deterministic equations in which the variables are species concentrations. In recent years, though, as smaller and smaller systems – such as an individual biological cell, say – can be studied quantitatively, the importance of molecular discreteness in chemical reactions has increasingly been realized. This is particularly true when the system is far from the ‘thermodynamic limit’ when the numbers of all reacting molecular species involved are several orders of magnitude smaller than Avogadro’s number. In such situations, each reaction has to be treated as a probabilistic ‘event’ that occurs by chance when the appropriate reactants collide. Explicitly accounting for such processes has led to the development of sophisticated statistical methods for simulation of chemical reactions, particularly those occurring at the cellular and sub-cellular level. In this article, we describe this approach, the so-called stochastic simulation algorithm, and discuss applications to study the dynamics of model regulatory networks.     

Scalars vectors in physics - II

In Part I, the nature of scalars and vectors was discussed for the Newtonian world. However, in the relativistic world, physical quantities follow Lorentz transformations. This change of transformation from Galilean to Lorentz results in interesting distinctions in their properties: mass and time are no longer scalars, time and space become intertwined, etc. This part discusses the nature of scalars and vectors in the relativistic world.