Global nonlinear optimization for the estimation of static shift and interpretation of 1-D magnetotelluric sounding data

In the presence of conducting inhomogeneities in near-surface structures, apparent resistivity data in magnetotelluric sounding can be severely distorted. This is due to electric fields generated from boundary charges on surficial inhomogeneities. Such distortion persists throughout the entire recording range and is known as static shift in magnetotellurics. Frequencyindependent static shifts manifest as vertical, parallel shifts that occur in plots of the dual logarithmic scale of apparent resistivity versus time period. The phase of magnetotelluric sounding data remains unaffected by the static shift and can be used to remove the static shift to some extent. However, individual inversion of phase data yields highly nonunique results, and alone it will not work to correctly remove the static shift. Inversions of uncorrected magnetotelluric data yield erroneous and unreliable estimations, while static-shift-corrected magnetotelluric data provide better and reliable estimations of the resistivities and thicknesses of subsurface structures. In the present study, static shift (a frequencyindependent real constant) is also considered as one of the model parameters and is optimized together with other model parameters(resistivity and thickness) using the very fast simulated annealing global inversion technique. This implies that model parameters are determined simultaneously with the estimate of the static shift in the data. Synthetic and noisy data generated for a number of models are interpreted, to demonstrate the efficacy of the approach to yield reliable estimates of subsurface structures when the apparent resistivity data are affected by static shift. Individual inversions of static-shift-affected apparent resistivity data and phase data yield unreliable estimations of the model parameters. Furthermore, the estimated model parameters after individual data inversions do not show any systematic correlations with the amount of static shift in the data. The present study shows that only joint inversion of the apparent resistivity and phase data, without or with optimizing of the static shift, yields models that show good fits between the observed and the model data. Joint inversion results also reveal a systematic relationship between the estimated model parameters and the static shift in the data. The proposed approach also shows that estimated resistivities are ‘S’ (the static shift parameter) times the actual resistivities, and that estimated thicknesses are √S times the actual thicknesses without optimization of the static shift. This result is in good agreement with the existing relationship in the literature. Therefore, the global optimization procedure developed can be effectively used to optimize the static shifts in data, to obtain reliable estimations of model parameters. Subsequently, joint inversion of the apparent resistivity and phase data, with optimization of the static shift, is performed, which yields accurate estimates of subsurface structures. It is demonstrated that this approach can also be used when the data is not affected by the static shift. In such cases, the estimated static shift parameter ‘S’ will be close to unity. The efficacy of the approach is demonstrated with a field example from Singhbhum craton, eastern India, by providing an accurate estimation of the craton thickness and the conducting structure that lies below the craton

NADI PARIKSHA: WRIST PULSE ANALYSIS WITH TRADITIONAL AND MODERN INTERPRETATION

Nadi Pariksha (Pulse diagnosis) is considered the most important assessment in Traditional Medicine System (TMS) for health monitoring. Traditional pulse analysis is subjective and hard to quantify. It is difficult for a Ayurvedic doctor to understand the pulse by his own perception due to its arbitrariness. To realize due recognition of TMS, standard techniques and standard instruments are urgently to be developed. In view of the increasing popularity of traditional and alternative medicine worldwide, researchers have explored pulse sensing and analysis, but due to the conflict of research goals, methodologies and statistical tools applied, the outcome of studies till date is not focused in one direction. This study explores current status of pulse signal interpretation by researchers using latest electronic signal processing techniques in recent years. The aim of research is towards development of pulse sensing and analyzing techniques using latest technology to assist or help Ayurvedic doctors, in a way to promote our countrys traditional pulse sensing. Since no sensor is benchmarked as a standard in wrist pulse sensing till date, various sensors were explored to sense wrist pulse and the results were correlated with the recent research. Optical sensor HOA 709 in reflective mode, exhibited best results, it captured the minute details and was used to acquire pulse signal of healthy subjects at Pita point on radial artery. The sensor was explored further to record pre-meal and post-meal data of two subjects and significant variation in signal contour was noticed. It can further be explored to extract more parameters with the help of Ayurvedic doctors to make it useful in health care.

A Method for Dynamic Characterization and Response Prediction Using Ground Vibration Test(GVT)Data for Unknown Structures.

The Objective Of This Proposed Work Is To Develop A Reliable Method For Dynamic Characterization And Prediction Of Dynamic Response Of Structures Of Known/Unknown Configurations, By Processing The Free Vibration Data Generated Experimentally From The Ground Vibration Tests (GVT)Of The Prototype Vehicles. The Methodology Would Make Use Of The Measured Dynamic Data In Terms Of Mode Shapes, Natural Frequencies, Modal Damping, Point Impedances Etc.And Generate Modal (Scaled) Stiffness And Inertia Information That Will Be Used For Prediction Of Response Characteristics Of The Prototype Structure . With These Objectives, The Present Work Develops The Mathematical Formulation Of The Method, And Demonstrates Its Reliability By Performing The Experiment On A Simple Cantilever Beam To Determine Its Dynamic Characteristics. Results On Scaled Modal Stiffness And Inertia, Generated Through The Method Using Experimental (GVT) Data Show Excellent Agreement With Those Generated By FE And Analytical Models .It Must Be Noted That A Valid Benchmarking Is Performed With The Condition That The Experimental Procedure Is 'Blind' To The Actual Stiffness And Inertia Distributions As Used In FEM Or Analytical Models . Agreement Of The Predicted Response Of The Structure With That From Direct Experiment And Those From The FE And Analytical Models Indicates That This Method Will Be A Promising Tool To Predict The Dynamic And Aeroelastic Characteristics Of Any Prototype Vehicle In The Future. Once The Reliability Of The Method Is Established,It Can Be Extended To Determine The Dynamic And Aeroelastic Characteristics Of All Aircraft For Which Dynamic Characteristics Are Available From A Ground -; Vibration Test (GVT)

Grey Relational Analysis Based Optimization of Underwater Nd: YAG Laser Micro-channeling on PMMA

AbstractLaser based micro-channeling is emerging as the most widely used process for fabrication of polymer based micro-fluidic devices. Nd:YAG lasers are one of the most favoured laser system by industries involved in laser based material processing. However, they have not been fully explored for micro-level processing. In this research work, Nd:YAG laser has been utilized in fabrication of micro-channels on PMMA in underwater condition. The input parameters have been chosen as lamp current, scanning speed, pulse frequency and pulse width. Depth, burr height and burr width of the micro-channel have been taken as output quality characteristics. Taguchi methodology in combination with grey relational analysis has been employed to determine the optimal parametric condition for satisfying multiple objectives at same time. Underwater laser processing has resulted in minimization of undesirable effects of laser processing like heat affected zone and redeposition around the micro-channels resulting in cleaner and finer structure than open air processing

A comparative study of spin coated and floating film transfer method coated poly (3-hexylthiophene)/poly (3-hexylthiophene)-nanofibers based field effect transistors

A comparative study on electrical performance, optical properties, and surface morphology of poly(3-hexylthiophene) (P3HT) and P3HT-nanofibers based “normally on” type p-channel field effect transistors (FETs), fabricated by two different coating techniques has been reported here. Nanofibers are prepared in the laboratory with the approach of self-assembly of P3HT molecules into nanofibers in an appropriate solvent. P3HT (0.3 wt. %) and P3HT-nanofibers (∼0.25 wt. %) are used as semiconductor transport materials for deposition over FETs channel through spin coating as well as through our recently developed floating film transfer method (FTM). FETs fabricated using FTM show superior performance compared to spin coated devices; however, the mobility of FTM films based FETs is comparable to the mobility of spin coated one. The devices based on P3HT-nanofibers (using both the techniques) show much better performance in comparison to P3HT FETs. The best performance among all the fabricated organic field effect transistors are observed for FTM coated P3HT-nanofibers FETs. This improved performance of nanofiber-FETs is due to ordering of fibers and also due to the fact that fibers offer excellent charge transport facility because of point to point transmission. The optical properties and structural morphologies (P3HT and P3HT-nanofibers) are studied using UV-visible absorption spectrophotometer and atomic force microscopy , respectively. Coating techniques and effect of fiber formation for organic conductors give information for fabrication of organic devices with improved performance

Research Notes : India : Potential of an off-season soybean nursery

In India, soybean is generally sown during summer (June-October). However, due to tremendous variability in climatic conditions of the country, there is a scope for growing soybean in more than one season. The efficacy of yield improvement projects could be substantially enhanced by rapid genera-tion turnover

Adhesion stimulates Scar/WAVE phosphorylation in mammalian cells

The Scar/WAVE complex catalyzes the protrusion of pseudopods and lamellipods, and is therefore a principal regulator of cell migration. However, it is unclear how its activity is regulated, beyond a dependence on Rac. Phosphorylation of the proline-rich region, by kinases such as Erk2, has been suggested as an upstream activator. We have recently reported that phosphorylation is not required for complex activation. Rather, it occurs after Scar/WAVE has been activated, and acts as a modulator. Neither chemoattractant signaling nor Erk2 affects the amount of phosphorylation, though in Dictyostelium it is promoted by cell-substrate adhesion. We now report that cell-substrate adhesion also promotes Scar/WAVE2 phosphorylation in mammalian cells, suggesting that the process is evolutionarily conserved