1,560 research outputs found
Adoption of Indigenous Dairy Management Practices among Tribal Farm Women
The study was conducted among the tribal farm women of West Garo Hills District of Meghalaya, India with the objective to determine the extent of adoption of indigenous dairy management practices. Proportionate random sampling was used in selection of 120 respondents. Practices having rationality for adoption of indigenous dairy management practices were collected and the data were analyzed using percentage analysis. The findings revealed that majority of the respondents adopted care and management of dry and pregnant cows. This was followed by adoption of other practices viz.., selection of breed and feeding, care during and after calving and milking technique
Spacecraft Rendezvous Guidance via Factorization-Free Sequential Convex Programming using a First-Order Method
We implement a fully factorization-free algorithm for nonconvex,
free-final-time trajectory optimization. This algorithm is based on sequential
convex programming and utilizes an inverse-free, exact discretization procedure
to ensure dynamic feasibility of the converged trajectory and PIPG, a fast,
first-order conic optimization algorithm as the subproblem solver. Although
PIPG requires the tuning of a hyperparameter to achieve fastest convergence, we
show that PIPG can be tuned to a nominal trajectory optimization problem and it
is robust to variations in initial condition. We demonstrate this with a monte
carlo simulation of the free-final-time rendezvous problem, using
Clohessy-Wiltshire dynamics, an impulsive thrust model, and various state and
control constraints including a spherical keepout zone.Comment: AAS Rocky Mountain Guidance, Navigation and Control Conference, 202
Fabrication of micro separation column for miniaturized gas chromatography system
The emphasis of this work is on the fabrication of a micro separation column for applicaton in
miniaturized gas chromatography system. The micro column was made by microchannels fabricated
on the silicon wafer and sealed with a glass lid. The microchannels were fabricated by wet etching
process and the channels were of length 2m , width 200 μm and depth 100 μm. The channels were
closed by sealing with Pyrex glass. Silicide bonding was done for the bonding of silicon with Pyrex
glass. Ti was used as an intermediate layer and bonded at a temperature of 377 ◦C and a force of
1kN. During bonding Ti forms an alloy with silicon and forms Titanium silicide and this helps to
bond the glass wafer with silicom wafer with microchannels etched on it
Measurement and modeling of pulsatile flow in microchannel
An experimental study of pulsatile flow in microchannel is reported in this paper. Such a study is important because time-varying flows are frequently encountered in microdevices. The hydraulic diameter of the microchannel is 144 μm and deionized water is the working fluid. The pressure drop across the microchannel as a function of time is recorded, from which the average and r.m.s. pressure drops are obtained. The experiments have been performed in the quasi-steady flow regime for a wide range of flow rate, frequency of pulsations, and duty cycle. The results suggest that the pressure with pulsations lies between the minimum and maximum steady state pressure values. The average pressure drop with pulsation is approximately linear with respect to the flow rate. The theoretical expression for pressure has also been derived wherever possible and the experimental data is found to lie below the corresponding theoretical values. The difference with respect to the theoretical value increases with an increase in frequency and a decrease in flow rate, with a maximum difference of 32.7%. This is attributed to the small size of the microchannel. An increase in frequency of square waveform leads to a larger reduction in pressure drop as compared to rectangular waveform, irrespective of the duty cycle. The results can be interpreted with the help of a first-order model proposed here; the model results are found to compare well against the experimental results. A correlation for friction factor in terms of the other non-dimensional governing parameters is also proposed. Experimental study of mass-driven pulsatile flow in microchannel is being conducted for the first time at these scales and the results are of both fundamental and practical importance
Eikonal solutions to optical model coupled-channel equations
Methods of solution are presented for the Eikonal form of the nucleus-nucleus coupled-channel scattering amplitudes. Analytic solutions are obtained for the second-order optical potential for elastic scattering. A numerical comparison is made between the first and second order optical model solutions for elastic and inelastic scattering of H-1 and He-4 on C-12. The effects of bound-state excitations on total and reaction cross sections are also estimated
The stability of tide gauges in the South Pacific determined from multi-epoch geodetic levelling, 1992 to 2010
Tide gauge data is important for determining global or local sea level rise with respect to a global geocentric reference frame. Data from repeated precise levelling connections between the tide gauges and a series of coastal and inland benchmarks, including Continuous GPS (CGPS) benchmarks, are used to determine the stability of tide gauges at 12 locations in the South Pacific. The method for determining this stability is based on a constant velocity model which minimises the net movement amongst a set of datum benchmarks surveyed since the installation of the tide gauges. When assessed at a 95% confidence interval, and with the exception of the Solomon Islands, none of the tide gauges were found to be in motion relative to their CGPS benchmarks. The Solomon Islands estimate is considered to be unreliable since the CGPS benchmark was recently established and has been surveyed fewer than three times. In Tonga and Cook Islands, the tide gauges were found to be disturbed or affected by survey errors whereas the Vanuatu results were affected by earthquakes
Computational Modeling of Semiconductor Dynamics at Femtosecond Time Scales
The Interchange No. NCC2-5149 deals with the emerging technology of photonic (or optoelectronic) integrated circuits (PICs or OEICs). In PICs, optical and electronic components are grown together on the same chip. To build such devices and subsystems, one needs to model the entire chip. PICs are useful for building components for integrated optical transmitters, integrated optical receivers, optical data storage systems, optical interconnects, and optical computers. For example, the current commercial rate for optical data transmission is 2.5 gigabits per second, whereas the use of shorter pulses to improve optical transmission rates would yield an increase of 400 to 1000 times. The improved optical data transmitters would be used in telecommunications networks and computer local-area networks. Also, these components can be applied to activities in space, such as satellite to satellite communications, when the data transmissions are made at optical frequencies. The research project consisted of developing accurate computer modeling of electromagnetic wave propagation in semiconductors. Such modeling is necessary for the successful development of PICs. More specifically, these computer codes would enable the modeling of such devices, including their subsystems, such as semiconductor lasers and semiconductor amplifiers in which there is femtosecond pulse propagation. Presently, there are no computer codes that could provide this modeling. Current codes do not solve the full vector, nonlinear, Maxwell's equations, which are required for these short pulses and also current codes do not solve the semiconductor Bloch equations, which are required to accurately describe the material's interaction with femtosecond pulses. The research performed under NCC2-5149 solves the combined Maxwell's and Bloch's equations
Schwinger-Dyson operator of Yang-Mills matrix models with ghosts and derivations of the graded shuffle algebra
We consider large-N multi-matrix models whose action closely mimics that of
Yang-Mills theory, including gauge-fixing and ghost terms. We show that the
factorized Schwinger-Dyson loop equations, expressed in terms of the generating
series of gluon and ghost correlations G(xi), are quadratic equations S^i G = G
xi^i G in concatenation of correlations. The Schwinger-Dyson operator S^i is
built from the left annihilation operator, which does not satisfy the Leibnitz
rule with respect to concatenation. So the loop equations are not differential
equations. We show that left annihilation is a derivation of the graded shuffle
product of gluon and ghost correlations. The shuffle product is the point-wise
product of Wilson loops, expressed in terms of correlations. So in the limit
where concatenation is approximated by shuffle products, the loop equations
become differential equations. Remarkably, the Schwinger-Dyson operator as a
whole is also a derivation of the graded shuffle product. This allows us to
turn the loop equations into linear equations for the shuffle reciprocal, which
might serve as a starting point for an approximation scheme.Comment: 13 pages, added discussion & references, title changed, minor
corrections, published versio
Procurement of IT Consulting Services and Firm-Specific Characteristics
Information technology investments and the management consulting industry witnessed unprecedented growth in the last decade. This led to regulators\u27 (SEC and Congress) allegations that consulting services that are provided by incumbent auditors may be disguised extra payments to auditors for favorable financial reporting. However, there may be alternative valid reasons for procurement of consulting. Under new legislation (proclaimed in the aftermath of spectacular failures like Enron and Worldcom), publicly traded corporations that engage professional services firms to provide both audit services and consulting services must now disclose the extent and nature of these services. Using the data made available by these new mandated disclosures and using the theoretical backdrop of the resource-based view (RBV), this paper examines whether investments by firms in consulting services follow predictable patterns driven by economic factors. Thus, rather than examine whether IT consulting has any ex-post value or whether procurement of consulting impairs auditor independence, this study focuses on whether investments, ex-ante, follow logical patterns consistent with microeconomic principles. Our analysis shows that procurement of IT and management consulting is consistent with the resource-based view -companies seek to develop organizational capabilities they lack as dictated by their strategic business need. In contrast to the narrow IT Doesn\u27t Matter view, it can be argued that even in the current environment of IT outsourcing, firms must carefully match their IT capability (in-house or outsourced) with organizational strategy and capability to develop unique and inimitable resources as put forth by RBV. We find that companies are indeed investing consistent with fundamental tenets of financial value analysis and based on market expectations of performance. More specifically, after controlling for pressure to perform and cash availability, low margin and low turnover companies spend more on consulting services. Low-margin strategy companies expend more on consulting when their asset turnover is also low, while low-turnover strategy companies expend more on consulting when their earnings margin is also low
- …