Measurement of the Current Density Distribution of the Electron Beam Welding Over Its Cross Section

В процессе проведения электронно-лучевой сварки важное практическое значение имеет правильный подбор размера пятна электронного пучка на стыке свариваемых конструкций, расположение фокуса электронного пучка относительно границы «поверхность стыка – вакуум», а также распределение удельной мощности по поперечному сечению пучка. Цель работы – представить метод измерения распределения плотности тока электронного пучка электронно- лучевой сварки по его поперечному сечению, заключающийся в осциллографировании тока электронов, проходящих через узкую измерительную щель металлической пластины в цилиндр Фарадея при быстрой развёртке измеряемого пучка электронов поперёк измерительных щелей. Представленный метод позволит находить положение фокуса сварочного электронного пучка, определять размер профиля электронного пучка в необходимом месте траектории сварочного пучка, а также автоматизировать процесс измерения этих параметров сварочного электронного пучка. При данном методе точность измерения ухудшается из-за того, что от полезного сигнала цилиндра Фарадея вычитается величина тока отражённых из цилиндра Фарадея электронов, а термоэмиссионные электроны от измерительной решётки при работе на высоком уровне измеряемого тока добавляются. Чтобы минимизировать их влияние, использован дополнительный решётчатый экран, электрически связанный с цилиндром Фарадея. Измеряемый сварочный ток создаёт высокую тепловую нагрузку на измерительную решётку, поэтому развёртка пучка по ней производится на максимально быстрой скорости, какую позволяет полоса пропускания системы развертки с минимальной нелинейностью. Измерительная решётка изготовлена из тугоплавкого тантала. Основную часть тепловой нагрузки импульса измеряемого тока вне времени развёртки пучка принимают массивные медные экраны, один из которых имеет форму решётки, щели которых шире, чем щели у измерительной решётки. Данным методом проведено измерение распределения плотности тока источника пучка электронов с энергией 90 кэВ в диапазоне от 1 мА до 80 мА. Предлагаемый способ позволяет проводить измерение распределения плотности тока электронного пучка электронно-лучевой сварки по его поперечному сечению с точностью до ±10 %In the process of electron-beam welding, the correct selection of the size of the electron beam spot at the junction of the structures to be welded, the location of the focus of the electron beam relative to the “junction surface – vacuum” boundary, and the distribution of specific power over the beam cross section are of great practical importance. The purpose of the work is to present a method for measuring the current density distribution of an electron beam of electron beam welding over its cross section, which consists in oscillography of the electron current passing through a narrow measuring slit of a metal plate into a Faraday cup with a fast sweep of the measured electron beam across the measuring slits. The presented method will make it possible to find the position of the focus of the welding electron beam, determine the size of the electron beam profile in the required place of the welding beam trajectory, and also automate the process of measuring these parameters of the welding electron beam. With this method of measurement, the measurement accuracy deteriorates due to the fact that the value of the current of electrons reflected from the Faraday cup is subtracted from the useful signal of the Faraday cup, and thermionic electrons from the measuring grid are added when operating at a high level of the measured current. To minimize their influence, an additional grating shield electrically connected to the Faraday cup was used. The measured welding current creates a high thermal load on the measuring grating, so the beam is scanned along it at the fastest possible speed, which is allowed by the bandwidth of the scanning system with minimal nonlinearity. The grid is made of refractory tantalum. The main part of the thermal load of the measured current pulse outside the beam sweep time is taken by massive copper screens, one of which has the shape of a grating, the slots of which are wider than those of the measuring grating. This method was used to measure the distribution of the current density of a source of an electron beam with an energy of 90 keV in the range from 1 mA to 80 mA. The proposed method allows measuring the current density distribution of the electron beam of electron beam welding over its cross section with an accuracy of ±10

Compact Source of Electron Beam for Facility of Electron-Beam Welding with the Location of the Electron Gun and the Source of High Voltage in a Single Monoblock. Concept and Bench Tests of the Monoblok Prototype

Представлен прототип компактного источника электронного пучка для установок электронно-лучевой сварки с расположением электронной пушки и источника высоковольтного напряжения в едином моноблоке. Размещение электронной пушки, источника высоковольтного напряжения, электроники управления пучком и питания накала катода источника электронного пучка для электронно-лучевой сварки в едином корпусе-моноблоке снижает вес и стоимость (за счёт уменьшения количества используемых материалов), объём и занимаемые производственные площади. Это существенно расширяет возможности применения представляемого типа источников электронного пучка в разнообразных областях деятельности человека, в том числе в космических технологиях в открытом пространстве космоса. Цель работы – показать целесообразность концепции компоновки источника электронного пучка в едином корпусе-моноблоке на примере стендовых испытаний прототипа источника-моноблока. Спроектирован и изготовлен прототип источника-моноблока. Проведены его предварительные стендовые испытания с лазерным подогревом катода. Обсуждаются возможные применения. Получен электронный ток источника до 70 мА с энергией 90 кэВ. Данный результат демонстрирует возможность практической реализации нового способа компоновки источника электронного пучкаA prototype of an electron beam compact source for electron-beam welding is presented. The electron gun and a high-voltage source are united in a single monoblock. The placement of the electron gun, the high-voltage source, the beam control electronics and the power supply of the cathode heating of the electron beam source for electron beam welding in a single monoblock housing reduces weight and cost by reducing the amount of materials used, volume and occupied production areas. This significantly expands the possibilities of using the presented type of electron beam sources in various fields of human activity, including space technologies in the open space of space. The purpose of the work is to show the expediency of the concept of arranging the electron beam source in the single monoblock housing as the example of bench tests of the source prototype. The prototype of the monoblock was designed and manufactured. Its preliminary bench tests with laser cathode heating were carried out. Its possible applications are discussed. An electron source current up to 70 mA with an energy of 90 keV was obtained. The result obtained demonstrates the possibility of practical implementation of a new method of arranging an electron beam sourc

Penilaian Kinerja Keuangan Koperasi di Kabupaten Pelalawan

This paper describe development and financial performance of cooperative in District Pelalawan among 2007 - 2008. Studies on primary and secondary cooperative in 12 sub-districts. Method in this stady use performance measuring of productivity, efficiency, growth, liquidity, and solvability of cooperative. Productivity of cooperative in Pelalawan was highly but efficiency still low. Profit and income were highly, even liquidity of cooperative very high, and solvability was good

Juxtaposing BTE and ATE – on the role of the European insurance industry in funding civil litigation

One of the ways in which legal services are financed, and indeed shaped, is through private insurance arrangement. Two contrasting types of legal expenses insurance contracts (LEI) seem to dominate in Europe: before the event (BTE) and after the event (ATE) legal expenses insurance. Notwithstanding institutional differences between different legal systems, BTE and ATE insurance arrangements may be instrumental if government policy is geared towards strengthening a market-oriented system of financing access to justice for individuals and business. At the same time, emphasizing the role of a private industry as a keeper of the gates to justice raises issues of accountability and transparency, not readily reconcilable with demands of competition. Moreover, multiple actors (clients, lawyers, courts, insurers) are involved, causing behavioural dynamics which are not easily predicted or influenced. Against this background, this paper looks into BTE and ATE arrangements by analysing the particularities of BTE and ATE arrangements currently available in some European jurisdictions and by painting a picture of their respective markets and legal contexts. This allows for some reflection on the performance of BTE and ATE providers as both financiers and keepers. Two issues emerge from the analysis that are worthy of some further reflection. Firstly, there is the problematic long-term sustainability of some ATE products. Secondly, the challenges faced by policymakers that would like to nudge consumers into voluntarily taking out BTE LEI

Search for stop and higgsino production using diphoton Higgs boson decays

Results are presented of a search for a "natural" supersymmetry scenario with gauge mediated symmetry breaking. It is assumed that only the supersymmetric partners of the top-quark (stop) and the Higgs boson (higgsino) are accessible. Events are examined in which there are two photons forming a Higgs boson candidate, and at least two b-quark jets. In 19.7 inverse femtobarns of proton-proton collision data at sqrt(s) = 8 TeV, recorded in the CMS experiment, no evidence of a signal is found and lower limits at the 95% confidence level are set, excluding the stop mass below 360 to 410 GeV, depending on the higgsino mass

Differential cross section measurements for the production of a W boson in association with jets in proton–proton collisions at √s = 7 TeV

Measurements are reported of differential cross sections for the production of a W boson, which decays into a muon and a neutrino, in association with jets, as a function of several variables, including the transverse momenta (pT) and pseudorapidities of the four leading jets, the scalar sum of jet transverse momenta (HT), and the difference in azimuthal angle between the directions of each jet and the muon. The data sample of pp collisions at a centre-of-mass energy of 7 TeV was collected with the CMS detector at the LHC and corresponds to an integrated luminosity of 5.0 fb[superscript −1]. The measured cross sections are compared to predictions from Monte Carlo generators, MadGraph + pythia and sherpa, and to next-to-leading-order calculations from BlackHat + sherpa. The differential cross sections are found to be in agreement with the predictions, apart from the pT distributions of the leading jets at high pT values, the distributions of the HT at high-HT and low jet multiplicity, and the distribution of the difference in azimuthal angle between the leading jet and the muon at low values.United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio

Severe early onset preeclampsia: short and long term clinical, psychosocial and biochemical aspects

Preeclampsia is a pregnancy specific disorder commonly defined as de novo hypertension and proteinuria after 20 weeks gestational age. It occurs in approximately 3-5% of pregnancies and it is still a major cause of both foetal and maternal morbidity and mortality worldwide1. As extensive research has not yet elucidated the aetiology of preeclampsia, there are no rational preventive or therapeutic interventions available. The only rational treatment is delivery, which benefits the mother but is not in the interest of the foetus, if remote from term. Early onset preeclampsia (<32 weeks’ gestational age) occurs in less than 1% of pregnancies. It is, however often associated with maternal morbidity as the risk of progression to severe maternal disease is inversely related with gestational age at onset2. Resulting prematurity is therefore the main cause of neonatal mortality and morbidity in patients with severe preeclampsia3. Although the discussion is ongoing, perinatal survival is suggested to be increased in patients with preterm preeclampsia by expectant, non-interventional management. This temporising treatment option to lengthen pregnancy includes the use of antihypertensive medication to control hypertension, magnesium sulphate to prevent eclampsia and corticosteroids to enhance foetal lung maturity4. With optimal maternal haemodynamic status and reassuring foetal condition this results on average in an extension of 2 weeks. Prolongation of these pregnancies is a great challenge for clinicians to balance between potential maternal risks on one the eve hand and possible foetal benefits on the other. Clinical controversies regarding prolongation of preterm preeclamptic pregnancies still exist – also taking into account that preeclampsia is the leading cause of maternal mortality in the Netherlands5 - a debate which is even more pronounced in very preterm pregnancies with questionable foetal viability6-9. Do maternal risks of prolongation of these very early pregnancies outweigh the chances of neonatal survival? Counselling of women with very early onset preeclampsia not only comprises of knowledge of the outcome of those particular pregnancies, but also knowledge of outcomes of future pregnancies of these women is of major clinical importance. This thesis opens with a review of the literature on identifiable risk factors of preeclampsia

Impacts of the Tropical Pacific/Indian Oceans on the Seasonal Cycle of the West African Monsoon

The current consensus is that drought has developed in the Sahel during the second half of the twentieth century as a result of remote effects of oceanic anomalies amplified by local land–atmosphere interactions. This paper focuses on the impacts of oceanic anomalies upon West African climate and specifically aims to identify those from SST anomalies in the Pacific/Indian Oceans during spring and summer seasons, when they were significant. Idealized sensitivity experiments are performed with four atmospheric general circulation models (AGCMs). The prescribed SST patterns used in the AGCMs are based on the leading mode of covariability between SST anomalies over the Pacific/Indian Oceans and summer rainfall over West Africa. The results show that such oceanic anomalies in the Pacific/Indian Ocean lead to a northward shift of an anomalous dry belt from the Gulf of Guinea to the Sahel as the season advances. In the Sahel, the magnitude of rainfall anomalies is comparable to that obtained by other authors using SST anomalies confined to the proximity of the Atlantic Ocean. The mechanism connecting the Pacific/Indian SST anomalies with West African rainfall has a strong seasonal cycle. In spring (May and June), anomalous subsidence develops over both the Maritime Continent and the equatorial Atlantic in response to the enhanced equatorial heating. Precipitation increases over continental West Africa in association with stronger zonal convergence of moisture. In addition, precipitation decreases over the Gulf of Guinea. During the monsoon peak (July and August), the SST anomalies move westward over the equatorial Pacific and the two regions where subsidence occurred earlier in the seasons merge over West Africa. The monsoon weakens and rainfall decreases over the Sahel, especially in August.Peer reviewe

Measurement of associated W plus charm production in pp collisions at √s=7 TeV

Peer reviewe

Search for anomalous production of events with three or more leptons in pp collisions at √s = 8TeV

Published by the American Physical Society under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published articles title, journal citation, and DOI.A search for physics beyond the standard model in events with at least three leptons is presented. The data sample, corresponding to an integrated luminosity of 19.5fb-1 of proton-proton collisions with center-of-mass energy s=8TeV, was collected by the CMS experiment at the LHC during 2012. The data are divided into exclusive categories based on the number of leptons and their flavor, the presence or absence of an opposite-sign, same-flavor lepton pair (OSSF), the invariant mass of the OSSF pair, the presence or absence of a tagged bottom-quark jet, the number of identified hadronically decaying τ leptons, and the magnitude of the missing transverse energy and of the scalar sum of jet transverse momenta. The numbers of observed events are found to be consistent with the expected numbers from standard model processes, and limits are placed on new-physics scenarios that yield multilepton final states. In particular, scenarios that predict Higgs boson production in the context of supersymmetric decay chains are examined. We also place a 95% confidence level upper limit of 1.3% on the branching fraction for the decay of a top quark to a charm quark and a Higgs boson (t→cH), which translates to a bound on the left- and right-handed top-charm flavor-violating Higgs Yukawa couplings, λtcH and λctH, respectively, of |λtcH|2+|λctH|2<0.21