Performance of Wind Farm Employing Type-4 Wind Turbine with D-Statcom

Wind power is environmentally friendly and cost-predictable nature. It is widely recognized as a promising alternative electric power generation source at a time of uncertain fossil fuel costs and concern over the harmful effects of climate change. Various problems arise due to the rapid injection of wind power in the electrical grid, affecting the power quality. Harmonics and various power quality problems like voltage sag and swell are of common occurrence due to the voltage injected by the wind generators in the electrical grid. These may result into severe problems such as system frequency mismatch and change in power line capability. To reduce such problems a distributed static compensator (DSTATCOM) is employed.  The DSTATCOM is an effective way of reducing power quality problems, removing the wind speed fluctuations and improving the transient stability of wind farm. Simulation results show the proposed effectiveness of wind farm stability and power quality. The generating system is modeled and simulated in MATLAB environment using Simulink and Simpower System toolboxes. Keywords: Wind Farms (WF), Wind Energy, Distributed static compensator (DSTATCOM

Ethnobotanical Studies of Nubra Valley - A Cold Arid Zone of Himalaya

An attempt has been made to explore traditional medicinal knowledge of Nubra valley, the cold arid zone of Himalaya. Ethnobotanical information were gathered through several visits, group discussions and cross checked with local medicine men. The study identified 65 plant species belonging to 30 families have been used to cure various diseases and ailments. Maximum number of species was recorded to be used in kidney complaints (14 spp.), cold & cough (13 spp.) and fever (11 spp.). Leaves of 27 species; whole plant extract of 20 species and root/bulb of 19 species were mostly used. Juice, raw items, paste and decoction of plant species were the common method of usage. A large number of ethnic groups with varied culture inhabiting the remote and isolated valleys of Ladakh offer a great scope for ethnobotanical studies. Over exploitation of medicinal herbs can lead to the local extinction of the valuable herbs indicating an urgent need to draw up the necessary plans for medicinal plant utilization and conservation

Characterization of the first hexacoordinate phosphorus compound with S→P←S bonds

The first example of a hexacoordinate phosphorus compound [S{6-t-Bu-4-Me-C6H2O}2]2P+(Cl-· C3H4N2) with two S→P bonds is reported. This compound can be construed as an oxophosphonium salt with double intramolecular coordination by sulfur atoms. X-ray structure reveals a facial arrangement of the ligands with two coordinating sulfur atoms cis to each other. The S→P distance of 2.334 (1) Å is one among very short coordinate bond distances between sulfur and phosphorus

Rare occurrence of sunfish Mola mola (Linnaeus) from the coastal waters off Visakhapatnam (Bay of Bengal)

The occurrence of sunfish in any sea is a rare event. It is so rare that even fishermen engaged in fishing throughout their lives find it totally strange when they come across one. On 6 May, 1986, a local fisherman reported to the Zoology Department of the Andhra University that a very strange looking fish was part of that day's catch

An Efficient Block Circulant Preconditioner For Simulating Fracture Using Large Fuse Networks

{\it Critical slowing down} associated with the iterative solvers close to the critical point often hinders large-scale numerical simulation of fracture using discrete lattice networks. This paper presents a block circlant preconditioner for iterative solvers for the simulation of progressive fracture in disordered, quasi-brittle materials using large discrete lattice networks. The average computational cost of the present alorithm per iteration is $O(rs log s) + delops$, where the stiffness matrix ${\bf A}$ is partioned into $r$-by-$r$ blocks such that each block is an $s$-by-$s$ matrix, and $delops$ represents the operational count associated with solving a block-diagonal matrix with $r$-by-$r$ dense matrix blocks. This algorithm using the block circulant preconditioner is faster than the Fourier accelerated preconditioned conjugate gradient (PCG) algorithm, and alleviates the {\it critical slowing down} that is especially severe close to the critical point. Numerical results using random resistor networks substantiate the efficiency of the present algorithm.Comment: 16 pages including 2 figure

Chemical Synthesis of PEDOT–Au Nanocomposite

In this work, gold-incorporated polyethylenedioxythiophene nanocomposite material has been synthesized chemically, employing reverse emulsion polymerization method. Infrared and Raman spectroscopic studies revealed that the polymerization of ethylenedioxythiophene leads to the formation of polymer polyethylenedioxythiophene incorporating gold nanoparticles. Scanning electron microscope studies showed the formation of polymer nanorods of 50–100 nm diameter and the X-ray diffraction analysis clearly indicates the presence of gold nanoparticles of 50 nm in size

New appraisal values of travel time saving and reliability in Great Britain

© 2017, The Author(s). This paper provides an overview of the study ‘Provision of market research for value of time savings and reliability’ undertaken by the Arup/ITS Leeds/Accent consortium for the UK Department for Transport (DfT). The paper summarises recommendations for revised national average values of in-vehicle travel time savings, reliability and time-related quality (e.g. crowding and congestion), which were developed using willingness-to-pay (WTP) methods, for a range of modes, and covering both business and non-work travel purposes. The paper examines variation in these values by characteristics of the traveller and trip, and offers insights into the uncertainties around the values, especially through the calculation of confidence intervals. With regards to non-work, our recommendations entail an increase of around 50% in values for commute, but a reduction of around 25% for other non-work—relative to previous DfT ‘WebTAG’ guidance. With regards to business, our recommendations are based on WTP, and thus represent a methodological shift away from the cost saving approach (CSA) traditionally used in WebTAG. These WTP-based business values show marked variation by distance; for trips of less than 20miles, values are around 75% lower than previous WebTAG values; for trips of around 100miles, WTP-based values are comparable to previous WebTAG; and for longer trips still, WTP-based values exceed those previously in WebTAG

Modulation-doping a correlated electron insulator

Correlated electron materials (CEMs) host a rich variety of condensed matter phases. Vanadium dioxide (VO2) is a prototypical CEM with a temperature-dependent metal-to-insulator (MIT) transition with a concomitant crystal symmetry change. External control of MIT in VO2—especially without inducing structural changes—has been a long-standing challenge. In this work, we design and synthesize modulation-doped VO2-based thin film heterostructures that closely emulate a textbook example of filling control in a correlated electron insulator. Using a combination of charge transport, hard X-ray photoelectron spectroscopy, and structural characterization, we show that the insulating state can be doped to achieve carrier densities greater than 5 × 1021 cm−3 without inducing any measurable structural changes. We find that the MIT temperature (TMIT) continuously decreases with increasing carrier concentration. Remarkably, the insulating state is robust even at doping concentrations as high as ~0.2 e−/vanadium. Finally, our work reveals modulation-doping as a viable method for electronic control of phase transitions in correlated electron oxides with the potential for use in future devices based on electric-field controlled phase transitions

International meta-analysis of stated preference studies of transportation noise nuisance

The final publication is available at Springer via http://dx.doi.org/10.1007/s11116-014-9527-4This paper reports the first meta-analysis and most extensive review of stated preference studies of transportation noise nuisance. The meta-analysis is based on a newly compiled data set of 258 values from 49 studies and 23 countries and spanning more than 40 years. Contrast this with the most extensive meta-analysis of the more conventional hedonic pricing approach which includes 53 noise valuations. Moreover, the sample compares favourably with the 444 observations from the very first meta-analysis of the value of travel time savings which is by far the most widely examined parameter in transport planning. A particularly significant finding of the study is that the intertemporal income elasticity is close to one, somewhat larger than the cross-sectional income elasticity typically obtained from individual studies. This demonstrates the importance of distinguishing the effects of 2 income variations that occur over time, which tend to drive policy, from variations across individuals at one point in time, and such findings are typical of those observed in other markets. Importantly, the values derived are transferable across countries and may be used to benchmark existing evidence and provide values in contexts where none exist. Other key results are that values for aircraft noise exceed those for other modes, whilst those exposed to higher noise levels and those who are highly annoyed also have higher values in line with expectations. A wide range of design effects were tested but few were significant and these included the consumer surplus measure, the representation of noise and the context

Rigid Rotor Stability Analysis on Finite Hydrostatic Double-Layer Porous Oil Journal Bearing with Velocity Slip

A theoretical investigation has been carried out for stability characteristics of a finite hydrostatic double-layer porous oil journal bearing considering the effect of Beavers-Joseph velocity slip at the porous film interface. A linearized perturbation method has been used to obtain the threshold of stability in terms of critical mass parameter. The effect of slip parameters, eccentricity ratios, bearing feeding parameter, and slenderness ratio on the stability is investigated. Furthermore, nonlinear transient analysis is carried out to determine the system stability by tracing the journal center locus. Several trajectories of the journal center locus have been obtained for different operating conditions and are depicted with the help of graphics