Avitan, Lilach; Teicher, Mina; Abeles, Moshe
EEG generator-a model of potentials in a volume conductor. The potential recorded over the cortex electro-corticogram (ECoG) or over the scalp [electroencephalograph (EEG)] derives from the activity of many sources known as "EEG generators." The recorded amplitude is basically a function of the unitary potential of a generator and the statistical relationship between different EEG generators in the recorded population. In this study, we first suggest a new definition of the EEG generator. We use the theory of potentials in a volume conductor and model the contribution of a single synapse activated to the surface potential. We then model the contribution of the generator to the surface potential. Once the generator and its contribution are well defined, we can quantitatively assess the degree of synchronization among generators. The measures obtained by the model for a real life scenario of a group of generators organized in a specific statistical way were consistent with the expected values that were reported experimentally. The study sheds new light on macroscopic modeling approaches which make use of mean soma membrane potential. We showed major contribution of activity of superficial apical synapses to the ECoG signal recorded relative to lower somatic or basal synapses activity.
Faircloth, D; Kuchler, D; Lettry, L; Scrivens, R; CERN. Geneva. BE Department
The temperature distribution and heat flow at equilibrium of the plasma generator of the RF-powered non-cesiated Linac4 H- ion source have been studied with a finite element model. It is shown that the equilibrium temperatures obtained in the Linac4 nominal operation mode (100 kW RF power, 2 Hz, 0.4 ms pulse duration) are within material specifications except for the magnet cage, where a redesign may be necessary. To assess the upgrade of the Linac4 source for operation in the high-power operation mode of SPL, an extrapolation of the heat load towards 100 kW RF power, 50 Hz repetition rate and 0.4 ms pulse duration has been performed. The results indicate that a significant improvement of the source cooling is required to allow for operation in HP-SPL.
Analiza poluprovodničkih kvantnih generatora tipa A3B5 po nano nivoima / Analysis of semiconductor quantum generators of A3B5 type at nano levels / Наноуровневый анализ полупроводниковых квантовых генераторов типа A3B5
Leonid I. Grečihin
Full Text Available U članku se obrazlaže formiranje klasterne rešetkaste strukture poluprovodničkog kristala tipa A3B5. Predstavljen je način deformacije elektronskih opni atoma koji su u sastavu elemenata poluprovodničke kristalne strukture. Na primeru kristala iz jedinjenja indijuma i elemenata pete grupe Mendeljejeve tablice, utvrđeno je među kakvim energetskim nivoima dolazi do generisanja poluprovodničkog kvantnog generatora. Definisani su tehnološki uslovi za izradnju lasera tipa A3B5. / The article describes the formation of the cluster grid structure of semiconductor crystals of A3B5 type. The deformation of the electron shells of the atoms in semiconductor crystal structure elements has been presented. Crystals of the Indium compounds and the elements from Group 5 of the Mendeleev periodic table have been used to show the energy levels where a semiconductor quantum generator is generated. The technological conditions for an A3B5 type laser realisation have been defined. / Обосновано образование кластерной решеточной структуры полупроводниковых кристаллов типа А3В5. Показано, каким образом происходит деформация электронных оболочек атомов составных элементов полупроводниковой кристаллической структуры. На примере кристаллов из соединений индия с элементами пятой группы таблицы Менделеева установлено, между какими энергетическими уровнями реализуется генерация полу- проводникового квантового генератора. Сформулированы тре бования к технологии изготовления лазеров на основе А3В5.
resonator; it is driven at angular speeds up to 26,000 rpm by a dc motor . The Electronic unit consists of a square wave generator, a comparator circuit...two time delay networks, a trigger circuit, a dc motor , and a power supply. The modulator operates in the following manner: at a given angular
@@ Company Name:Fuzhou Changhua Power machinery Co.Ltd. Company Profile:We are professional electric machinery manufacturer in china,which specializes in producing diesel and gasoline engine,diesel and gasoline generator,as well as diesel and gasoline water pump.Our company has obtained ISO9001 certification and Chinese national CCC certification,most of our products now have passed CE certification.Our products have been exported to more than 30 countries and regions,mainly in Europe,Southeast of Asia,America and Middle East.
WANG Li; YAN Yangguang; CAO Xiaoqing; MENG Xiaoli
Considering the salient pole and high magnetic nonlinearity of the electromagnetic doubly salient (EMDS)DC generator,a 12/8 pole prototype EMDS generator is designed and calculated using a 2-D finite element method (FEM).The phenomenon is analyzed and that the phase voltage wave changes between 120°and 180°.The influence of the exciting current and armature reaction on the DC voltage ripple of the generator is discussed in detail.and the nonlinear rules are gained that DC voltage rippie changes accordingly.The theoretical analysis is verified by the simulation and expefimental results.The results are helpful for the optimal design of the generator and the optimal control of excitingwinding.We conelude mat the filter-capacitance of the rectifier can be designed.
Full Text Available Kontaktna krutost zubaca jedan je od glavnih generatora unutrašnjih dinamičkih sila u spregama zupčanika planetarnih prenosnika. Neophodan je pri opisivanju dinamičkog ponašanja planetarnih prenosnika, tj. pri postavljanju jednačina dinamičke ravnoteže. U radu je prikazan metodološki pristup analitičkom i eksperimentalnom određivanju krutosti posmatranog planetarnog prenosnika. / Gear mesh stiffness in planetary gearing is one of the main generators of internal dynamic forces. It is necessary in describing dynamic behavior of planetary trains, i.e. in defining their equations of dynamic balance. This paper presents a methodological approach to experimental and analytical calculation of stiffness in planetary gearing.
YANG Jun; LUO Xiao-Liang; LIU Guo-Fu; LIN Cun-Bao; WANG Yan-Ling; HU Qing-Qing; PENG Jin-Xian
The feasibility of using frequency gradient analysis (FGA),a digital method based on Fourier transform,to discriminate neutrons and γ rays in the environment of an 8-bit sampling system has been investigated.The performances of most pulse shape discrimination methods in a scintillation detection system using the time-domain features of the photomultiplier tube anode signal will be lower or non-effective in this low resolution sampling system.However,the FGA method using the frequency-domain features of the anode signal exhibits a strong insensitivity to noise and can be used to discriminate neutrons and γ rays in the above sampling system.A detailed study of the quality of the FGA method in BC501A liquid scintillators is presented using a 5 G samples/s 8-bit oscilloscope and a 14.1 MeV neutron generator.A comparison of the discrimination results of the time-of-flight and conventional charge comparison (CC) methods proves the applicability of this technique.Moreover,FGA has the potential to be implemented in current embedded electronics systems to provide real-time discrimination in standalone instruments.
Liu Chang; Yan Yuepeng; Goh Wang-Ling; Xiong Yongzhong; Zhang Lijun; Mohammad Madihian
This paper presents a broadband inductor-less variable gain amplifier (VGA) with a linear-in-dB gain control characteristic and DC-offset cancellation.The proposed VGA is composed of a variable gain block,an exponential voltage generator,a DC-offset canceller with common-mode voltage correction,and a gain peaking block.To achieve the broad band and reduce the chip area,the gain peaking block employs an inductor-less gain peaking scheme to compensate the high frequency gain drop of the variable gain block and the DC-offset canceller.The VGA fabricated in 0.13μm SiGe BiCMOS technology achieves a 3-dB bandwidth of 7.5 GHz and a variable gain range from -10 to 30 dB.Due to the inductor-less design,the die area is only 0.53 × 0.27 mm2 which is the smallest among other similar reported works.At 10-Gb/s,the VGA consumes 50 mW power from a single 1.2 V supply and exhibits an output data jitter of less than 30 pspp.
刘细平; 易靓; 刁艳美; 左亮平
In order to overcome the problem such as mechanical wear and noise existed in gear of traditional permanent magnet synchronous machine for wind power generator,a permanent-magnet synchronous wind power generator with magnetic gear was analyzed.By using Ansoft Maxwell 2D finite element analysis model of the generator was established,the magnetic field distribution was calculated and the electromagnetic characteristics for no-load was analyzed.The results show that the wind power generator with magnetic gear has good torque transmission ratio and reliability.It is suitable for the wind power generation system.%为克服传统永磁同步风力发电机中齿轮增速装置存在机械磨损和噪声等问题,分析研究了一种磁齿轮传动永磁同步风力发电机.利用Ansoft软件,建立了电机的二维有限元结构模型,计算其磁场分布,分析了电机的气隙磁密、感应电动势和电磁转矩等电磁特性.结果表明,磁齿轮传动永磁同步发电机具有较好的转矩传输比,可靠性较高,适合在风力发电系统中应用.
函数信号发生器是一种常用的信号源，广泛应用于各种电子系统中，三角函数发生器是函数发生器中最为常用的一种。随着电子技术的发展，传统的函数发生器已经不能满足电子系统应用的需要，基于直接频率合成技术的函数发生器，由于可以获得很高的频率稳定度以及精确度，因此发展迅速。介绍了一种基于 FPGA 的三角函数信号发生器，具体分析了 DDS 算法原理，用verilog 语言实现了相位累加器和波形存储器两个模块的设计，借助 MATLAB 软件生成了波形存储器中的三角函数波形数值，利用 Synplify 和 ModelSim 作为软件平台，对设计进行了综合和仿真。%The signal generator,as a common signal source,is widely used in electronic system.The trigonometric function generator, as one of the signal generators, is used commonly. With the development of electronic technology,traditional function generator doesn't meet the needs of electronic systems.The function generator based on DDS,because of the high stability and accuracy of frequency, is developed rapidly.This paper introduces a trigonometric function generator based on FPGA,concretely analyzes the algorithm of DDS,designs the phase accumulator and ROM with verilog language,uses MATLAB to generate wave value of trigonometric function in ROM,and applies Synplify and ModelSim as the soft platform to synthesize and simulate the design.
邹华杰; 陈荷娟; 赖长缨; 孙剑韬; 姜琦
针对声管固定方法对微环音气流压电发电机最大输入功率的影响，提出了应用有限元和间边界元相结合的方法，对不同固定方法下的声管，数值模拟腔体受谐波(正弦波)激励的振动响应。在满足压电换能器最大机械功率条件下，选择合适的声管固定方法。结果表明：结构尺寸一定时，固支-固支固定有利于提高固有频率；结构尺寸越小，不同固定方法所对应的固有频率差异越大；固支-固支固定下，声管的基频较高且其偏差影响小。不同固定方法和不同尺寸下声管的谐响应和基频变化趋势，为微环音气流压电发电机的设计提供参考，也为进一步的换能器设计和验证实验提供了依据。%Methods of sound tube fixation the have great effect on the input power of micro-ringtone airflow piezoelectric generator.A finite element method combined with indirect boundary element method was proposed, harmonic responses of the sound tube with various fixation methods were analyzed.To maximize mechanical power of piezoelectric transducer,it should be choosing proper fixation methods of the sound tube.The result showed that:for the given structure size,clamped-clamped fixation method was beneficial to improve the natural frequency;the smaller size,the greater difference of natural frequency corresponded to various fixation meth-ods;clamped-clamped sound tube possessed higher fundamental frequency,and its deviation was small.The harmonic response and trend of fundamental frequency of sound tube with various fixing boundaries and different diameters could provide valuable reference for the design of micro-ringtone airflow piezoelectric generator;and it also provided the basis for further the design of transducer and experimental verification.
Daphnée Beaulieu; Alan Barkun; Myriam Martel
AIM:To complete a quality audit using recently published criteria from the Quality Assurance Task Group of the National Colorectal Cancer Roundtable.METHtODS:Consecutive colonoscopy reports of patients at average/high risk screening,or with a prior colorectal neoplasia (CRN) by endoscopists who perform 11 000 procedures yearly,using a commercial computerized endoscopic report generator.A separate institutional database providing pathological results.Required documentation included patient demographics,history,procedure indications,technical descriptions,colonoscopy findings,interventions,unplanned events,follow-up plans,and pathology results.Reports abstraction employed a standardized glossary with 10％ independent data validation.Sample size calculations determined the number of reports needed.RESULTS:Two hundreds and fifty patients (63.2 ±10.5 years,female:42.8％,average risk:38.5％,personal/family history of CRN:43.3％/20.2％) were scoped in June 2009 by 8 gastroenterologists and 3 surgeons (mean practice:17.1 ± 8.5 years).Procedural indication and informed consent were always documented.14％ provided a previous colonoscopy date (past polypremoval information in 25％,but insufficient in most to determine surveillance intervals appropriateness).Most procedural indicators were recorded (exam date:98.4％,medications:99.2％,difficulty level:98.8％,prep quality:99.6％).All reports noted extent of visualization (cecum:94.4％,with landmarks noted in 78.8％-photodocumentation:67.2％).No procedural times were recorded.One hundred and eleven had polyps (44.4％) with anatomic location noted in 99.1％,size in 65.8％,morphology in 62.2％; removal was by cold biopsy in 25.2％ (cold snare:18％,snare cautery:31.5％,unrecorded:20.7％),84.7％ were retrieved.Adenomas were noted in 24.8％(advanced adenomas:7.6％,cancer:0.4％) in this population with varying previous colonic investigations.CONCLUSION:This audit reveals lacking reported items