Self modulated dynamics of a relativistic charged particle beam in plasma wake field excitation

Self modulated dynamics of a relativistic charged particle beam is reviewed within the context of the theory of plasma wake field excitation. The self-consistent description of the beam dynamics is provided by coupling the Vlasov equation with a Poisson-type equation relating the plasma wake potential to the beam density. An analysis of the beam envelope self-modulation is then carried out and the criteria for the occurrence of the instability are discussed thereby.Comment: This is a 10 pages manuscript which contain 4 figures. This manuscript is recently submitted in 'Nuclear Instruments and Methods in Physics Research Section A' as a proceeding of the conference 'EAAC 2015

Sensor failure detection for jet engines

Revisions to the advanced sensor failure detection, isolation, and accommodation (DIA) algorithm, developed under the sensor failure detection system program were studied to eliminate the steady state errors due to estimation filter biases. Three algorithm revisions were formulated and one revision for detailed evaluation was chosen. The selected version modifies the DIA algorithm to feedback the actual sensor outputs to the integral portion of the control for the nofailure case. In case of a failure, the estimates of the failed sensor output is fed back to the integral portion. The estimator outputs are fed back to the linear regulator portion of the control all the time. The revised algorithm is evaluated and compared to the baseline algorithm developed previously

Sensor failure detection system

Advanced concepts for detecting, isolating, and accommodating sensor failures were studied to determine their applicability to the gas turbine control problem. Five concepts were formulated based upon such techniques as Kalman filters and a screening process led to the selection of one advanced concept for further evaluation. The selected advanced concept uses a Kalman filter to generate residuals, a weighted sum square residuals technique to detect soft failures, likelihood ratio testing of a bank of Kalman filters for isolation, and reconfiguring of the normal mode Kalman filter by eliminating the failed input to accommodate the failure. The advanced concept was compared to a baseline parameter synthesis technique. The advanced concept was shown to be a viable concept for detecting, isolating, and accommodating sensor failures for the gas turbine applications

Comparing Food and Cash Transfers to the Ultra-Poor in Bangladesh

"Bangladesh has some social safety net programs that transfer food to the poor, some that transfer cash, and some that provide a combination of both. This study evaluates the relative impacts of food and cash transfers on food security and livelihood outcomes among the ultra poor in Bangladesh. The programs impacts are evaluated according to various measures, including how well transfers are delivered; which transfers beneficiaries prefer; how accurately the programs target the extremely poor; effects on food security, livelihoods, and women’s empowerment; and cost effectiveness. The report identifies what has and has not worked in food and cash transfers and recommends ways of improving these programs. This study will be valuable to policymakers and others concerned with poverty reduction in Bangladesh and elsewhere." from textCash transfers, cost effectiveness, food security, Poverty, Poverty reduction, safety net programs, women empowerment,

HYTESS: A hypothetical turbofan engine simplified simulation

A users manual for a hypothetical turbofan engine simplified simulation is presented. This digital simulation exists as FORTRAN source code. The program is self-contained and was developed to offer those interested in engine dynamics and controls research an efficient, realistic, and easily used engine simulation. The engine is modeled using a state space formulation. Matrix elements within the linear state space structure are nonlinear functions of various engine variables

The Brahmaputra tale of tectonics and erosion:early Miocene river capture in the Eastern Himalaya

The Himalayan orogen provides a type example on which a number of models of the causes and consequences of crustal deformation are based and it has been suggested that it is the site of a variety of feedbacks between tectonics and erosion. Within the broader orogen, fluvial drainages partly reflect surface uplift, different climatic zones and a response to crustal deformation. In the eastern Himalaya, the unusual drainage configuration of the Yarlung Tsangpo–Brahmaputra River has been interpreted either as antecedent drainage distorted by the India–Asia collision (and as such applied as a passive strain marker of lateral extrusion), latest Neogene tectonically-induced river capture, or glacial damming-induced river diversion events. Here we apply a multi-technique approach to the Neogene paleo-Brahmaputra deposits of the Surma Basin (Bengal Basin, Bangladesh) to test the long-debated occurrence and timing of river capture of the Yarlung Tsangpo by the Brahmaputra River. We provide U–Pb detrital zircon and rutile, isotopic (Sr–Nd and Hf) and petrographic evidence consistent with river capture of the Yarlung Tsangpo by the Brahmaputra River in the Early Miocene. We document influx of Cretaceous–Paleogene zircons in Early Miocene sediments of the paleo-Brahmaputra River that we interpret as first influx of material from the Asian plate (Transhimalayan arc) indicative of Yarlung Tsangpo contribution. Prior to capture, the predominantly Precambrian–Paleozoic zircons indicate that only the Indian plate was drained. Contemporaneous with Transhimalayan influx reflecting the river capture, we record arrival of detrital material affected by Cenozoic metamorphism, as indicated by rutiles and zircons with Cenozoic U–Pb ages and an increase in metamorphic grade of detritus as recorded by petrography. We interpret this as due to a progressively increasing contribution from the erosion of the metamorphosed core of the orogen. Whole rock Sr–Nd isotopic data from the same samples provide further support to this interpretation. River capture may have been caused by a change in relative base level due to uplift of the Tibetan plateau. Assuming such river capture occurred via the Siang River in the Early Miocene, we refute the “tectonic aneurysm” model of tectonic–erosion coupling between river capture and rapid exhumation of the eastern syntaxis, since a time interval of at least 10 Ma between these two events is now demonstrated. This work is also the first to highlight U–Pb dating on detrital rutile as a powerful approach in provenance studies in the Himalaya in combination with zircon U–Pb chronology

CT scan in children with acute bacterial meningitis: experience from emergency department of a tertiary-care hospital in Karachi, Pakistan

Objective: To determine the role of computed tomography scan in children presenting to emergency department with symptoms and signs of suspected acute bacterial meningitis. Methods: The retrospective analysis was done on children who were admitted through the Emergency Department at Aga Khan University Hospital, Karachi, from September 2009 to September 2011 with the diagnosis of acute bacterial meningitis. Information related to age, gender, presenting complaints, clinical signs and symptoms, computed tomography scan findings and final outcome of patients was gathered from the medical records. SPSS 19 was used for statistical analysis. Results: A total of 192 patients were admitted with the relevant diagnosis. The male-female ratio was 2.3:1. Computed tomography scan was done in 114 (59.4%) patients. The scan was reported normal in 90 (78.94%) patients. However, cerebral oedema was found in 16 (14.03%) patients, cerebral infarct in 6(5.26%) and hydrocephalus in 2 (1.75%) patients. Overall, there were 6 (3.1%) deaths. Conclusion: Comuted tomography scan may have a beneficial role in children with acute bacterial meningitis. However, further studies are required to use the scan as a routine investigation for such a diagnosis

Amelioration of a saline sodic soil through cultivation of a salt-tolerant grass Leptochloa fusca

Reclamation of saline lands seems difficult for climatic and economic reasons, but cultivation of salt-tolerant plants is an approach to increasing productivity and improvement of salt-affected wastelands. A five-year field study was conducted to evaluate the effects of growing a salt-tolerant species Leptochloa fusca (L.) Kunth (kallar grass) on chemical properties of a saline sodic soil irrigated with poor quality groundwater. Soil salinity, sodicity and pH decreased exponentially by growing kallar grass as a result of leaching of salts from surface (0–20 cm) to lower depths (>100 cm). Concentrations of soluble cations (Na+, K+, Ca2+ and Mg2+) and anions (Cl−, SO42− and HCO3−) were reduced through to greater soil depths. A significant decline in soil pH was attributed to release of CO2 by grass roots and solublization of CaCO3. Both soil salinity and soil pH were significantly correlated with Na+, Ca2+, Mg2+, K+, Cl−, HCO3− and sodium adsorption ratio (SAR). Significant correlations were found between soluble cations (Na+, Ca2+ and K+), soluble anions (Cl−, SO42− and HCO3−) and the SAR. In contrast, there were negative correlations between soil organic matter content and all chemical properties. The ameliorative effects on the soil chemical environment were pronounced after three years of growing kallar grass. Cultivation of kallar grass enhanced leaching and interactions among soil chemical properties and thus restored soil fertility. The soil maintained the improved characteristics with further growth of the grass up to five years suggesting that growing salt-tolerant plants is a sustainable approach to biological amelioration of saline wastelands.J. Akhter, K. Mahmood, K.A. Malik, S. Ahmed and R. Murra