14,365 research outputs found
Full field image ranger hardware
No full textWe describe the hardware designed to implement a full field heterodyning imaging system. Comprising three key components - a light source, high speed shutter and a signal generator - the system is expected to be capable of simultaneous range measurements to millimetre precision over the entire field of view. Current modulated laser diodes provide the required illumination, with a bandwidth of 100 MHz and peak output power exceeding 600 mW. The high speed shutter action is performed by gating the cathode of an image intensifier, driven by a 50 Vpp waveform with 3.5 ns rise and fall times. A direct digital synthesiser, with multiple synchronised channels, provides high stability between its outputs, 160 MHz bandwidth and tuning of 0.1 Hz
Tomographic particle-image velocimetry in an IC engine
No full textThe flow structures during the intake and compression phase within the cylinder of an internal combustion(IC)engine strongly influence the mixing and combustion process. To gain a better understanding of the flow field, fully three-dimensional quantitative measurement techniques have to be applied to the flow field. Analog off-axis holographic particle-image velocimetry is capable of resolving the whole flow field of an IC engine with very high resolution (van Overbrueggen et. al [21]). On the other hand, long processing procedures make this technique not feasible for a statistic flow field analysis. Tomographic particle-image velocimetry (Tomo-PIV) is another three-component/three-dimensional (3C/3D) measurement technique that could be used. It is digital and therefore possesses the advantage of relatively short processing time. In this study, cycle resolved tomographic particle-image velocimetry measurements are performed in a four-valve IC engine to resolve the highly three dimensional flow in a large area of the cylinder. The resolved volume has a size of about 60 x 60 x 80 mm3 for the 160? measurements. The three-dimensional structure of the flow field is analyzed for 80?, 160?, and 240? after top dead center (aTDC) during the intake and compression phase at an engine speed of 1,500 rpm. The flow fields are analyzed by ensemble-averaged velocity fields, turbulent kinetic energy (TKE), and the G1 vortex center criterion. The results provide detailed inside in the highly three-dimensional flow field inside an internal combustion engine and show the feasibility of tomographic PIV to resolve such a large volume in a complex geometry
Development of Long Coated Conductors with High In-field Ic Performance by PLD Method at High Production Rate
No full textAbstractWe fabricated short samples and a 93 m long coated conductor (C. C.) of EuBa2Cu3O7-δ (EuBCO) with BaHfO3 (BHO) by the IBAD and the PLD methods, which exhibited the high in-field minimum Ic value, (Ic(min)), performance of 141.2 (77K in 3 T) and 411.3 (65K in 3 T) A/cm-w for a short sample, and 133.9 (77K in 3 T) A/cm-w for 93 m long C. C. with 3.6μm in thickness, respectively. Moreover, this long EuBCO with BHO coated conductor also showed high uniform longitudinal Ic distributions and n-value in magnetic fields. However, the deposition rate for obtaining the high in-field Ic performance was comparatively slow down to 10μm/h. To realize the low production cost for EuBCO with BHO coated conductors, improvement of the deposition rate of the EuBCO with BHO layer with high Ic is required. To solve this problem, we optimized growth conditions including deposition conditions. One of the objectives of this work was changing the layer growth mode from the vapor-solid (VS) mode to the vapor-liquid-solid (VLS) one to fabricate EuBCO with BHO layers for achievement of high production rate and maintaining the high in-field Ic and Jc performance of the films deposited at slow deposition rates. As a result, we fabricated EuBCO with BHO coated conductors at a high deposition rate of about 40μm/h and production rate of about 10 m/h, which revealed the Ic(min) value of 48.7 A/cm-w at 77K in 3 T for 1.35μm in thickness
Electric field effects on nematic wetting layers
No full textWe present a theoretical investigation of the temperature and electric field dependence of nematic liquid crystal wetting layers close to an aligning substrate within a confined system. Using a mesoscopic Q tensor theory coupled to Maxwell's equations for the electric field, we consider the existence and stability of homogeneous nematic wetting layers close to the substrate. Numerical results are presented showing the phase diagram for the isotropic (paranematic), nematic and wetting layer states. The effect on the isotropic-wetting transition, from first order to second order, when an electric field is applied is then investigated
Studies of the electrical properties and electroforming of thin insulating films
No full textThis thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Evaporated thin film sandwich structures of Au-SiOX-Au have been studied. These normally show electroforming effects and subsequently electron emission, electroluminescence, negative resistance and thermal-voltage memory effects. Previous work in the field is critically reviewed.
It was shown that the time dependence of the device current and emission current can be explained by making certain modifications to the filamentary conduction theory of Dearnaley. Detailed direct current-voltage measurements have revealed the existence of two different types of breakdown behaviour. At voltages less than 20 V single-hole breakdowns were observed, while in the voltage range 20-30 V large scale irreversible breakdown behaviour took place. The dependence of the voltage at which this occurs (Vß) on insulator thickness and temperature, together with measurements of the device temperature at breakdown and visual evidence of damage after breakdown, has led to the conclusion that this type of breakdown is a thermal effect. Such measurements also pointed to the existence of a high field region within the insulator, and potential distribution measurements confirmed this hypothesis. The high field region was also in evidence at low temperatures where the device current (Ic) showed a log Ic α Vb1/2 dependence on applied voltage (Vb).
Measurements of electron attenuation lengths in SiOx gave values of 400-1000 Å irrespective of temperature. The temperature independence was consistent with the emitted electron energy distributions at 77 and 300 K.
It was shown that electrons underwent Bragg diffraction through the top Au electrode. The angular distribution of emitted electrons became more isotropic with increasing voltage. Measurements on other systems showed that Al-SiOx/B2O3-Al devices could withstand very high voltages and give improved emission efficiency, while Au-CaBr2-Au and Au-Si3N4-Au devices showed very high initial currents and current-voltage characteristics which were irreversible
Predicting Field Coupling to an IC using Measured Coupling Factors
No full textHigh-strength electric and magnetic fields can capacitively or inductively couple energy to integrated circuits (ICs) and cause them to fail. While measurements can show when an IC will fail, they do not provide insight into the mechanisms for failure. Modeling the response of the IC to these fields is challenging, in part because of the small features of the IC and the large amount of circuitry information that must be included from the IC and printed circuit board. The goal of the following work is to develop a methodology for predicting the voltage or current on the pins of the IC from incident electric or magnetic fields. The method is based on measuring coupling factors, which show the relationship between a specific field component and the IC response. These coupling factors can be determined by placing the IC in a known electric or magnetic field within a transverse electromagnetic cell and measuring the response. The developed technique was validated by predicting the response of a commercially available 8-bit microcontroller to the electromagnetic fields generated by the nearby discharge of an electrostatic discharge gun. The proposed approach allows the prediction of the waveforms and a better understanding of failure mechanisms without the need to know or model IC geometry and circuitry
A 23-μW Keyword Spotting IC With Ring-Oscillator-Based Time-Domain Feature Extraction
No full textThis article presents the first keyword spotting (KWS) IC that uses a ring-oscillator-based time-domain processing technique for its analog feature extractor (FEx). Its extensive usage of time-encoding schemes allows the analog audio signal to be processed in a fully time-domain manner except for the voltage-to-time conversion stage of the analog front end. Benefiting from fundamental building blocks based on digital logic gates, it offers better technology scalability compared to conventional voltage-domain designs. Fabricated in a 65-nm CMOS process, the prototyped KWS IC occupies 2.03 mm 2 and dissipates 23- power consumption, including analog FEx and digital neural network classifier. The 16-channel time-domain FEx achieves a 54.89-dB dynamic range for 16-ms frame shift size while consuming 9.3 . The measurement result verifies that the proposed IC performs a 12-class KWS task on the Google Speech Command dataset (GSCD) with >86% accuracy and 12.4-ms latency. Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic
The attractions of medicine: the generic motivations of medical school applicants in relation to demography, personality and achievement
No full textBACKGROUND: The motivational and other factors used by medical students in making their career choices for specific medical specialities have been looked at in a number of studies in the literature. There are however few studies that assess the generic factors which make medicine itself of interest to medical students and to potential medical students. This study describes a novel questionnaire that assesses the interests and attractions of different aspects of medical practice in a varied range of medical scenarios, and relates them to demographic, academic, personality and learning style measures in a large group of individuals considering applying to medical school. METHODS: A questionnaire study was conducted among those attending Medlink, a two-day conference for individuals considering applying to medical school for a career in medicine. The main outcome measure was the Medical Situations Questionnaire, in which individuals ranked the attraction of three different aspects of medical practise in each of nine detailed, realistic medical scenarios in a wide range of medical specialities. As well as requiring clear choices, the questionnaire was also designed so that all of the possible answers were attractive and positive, thereby helping to eliminate social demand characteristics. Factor analysis of the responses found four generic motivational dimensions, which we labelled Indispensability, Helping People, Respect and Science. Background factors assessed included sex, ethnicity, class, medical parents, GCSE academic achievement, the 'Big Five' personality factors, empathy, learning styles, and a social desirability scale. RESULTS: 2867 individuals, broadly representative of applicants to medical schools, completed the questionnaire. The four generic motivational factors correlated with a range of background factors. These correlations were explored by multiple regression, and by path analysis, using LISREL to assess direct and indirect effects upon the factors. Helping People was particularly related to agreeableness; Indispensability to a strategic approach to learning; Respect to a surface approach to learning; and Science to openness to experience. Sex had many indirect influences upon generic motivations. Ethnic origin also had indirect influences via neuroticism and surface learning, and social class only had indirect influences via lower academic achievement. Coming from a medical family had no influence upon generic motivations. CONCLUSION: Generic motivations for medicine as a career can be assessed using the Medical Situations Questionnaire, without undue response bias due to demand characteristics. The validity of the motivational factors is suggested by the meaningful and interpretable correlations with background factors such as demographics, personality, and learning styles. Further development of the questionnaire is needed if it is to be used at an individual level, either for counselling or for student selection
A 15-nW per Sensor Interference-Immune Readout IC for Capacitive Touch Sensors
No full textThis paper presents a readout IC that uses an asynchronous capacitance-to-digital-converter (CDC) to digitize the capacitance of a touch sensor. A power-efficient tracking algorithm ensures that the CDC consumes negligible power consumption in the absence of touch events. To facilitate its use in wake-on-touch applications, the CDC can be periodically triggered by a co-integrated ultra-low-power relaxation oscillator. At a 38-Hz scan rate, the readout IC consumes 15 nW per touch sensor, which is the lowest reported to date.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic InstrumentationMicroelectronic
TESTER IC DIGITAL BERBASIS AVR ATMEGA 8535
No full textDigital ic tester is a tool used ic tester for testing integrated circuits in the ic. Ic tester consists of several units in the relevant field of engineering and digital microcontroller. Ic tester is made for the program study diii instrumentasi dan elektronika did not have a tool that can help to test the ic isstill good and worthor
not used this project focuses on creating a series of ic tester which is used and the microcontroler type avr atmega 8535. Ic tester was to test whether the ic that is
used is still feasible to see the condition of each gate in the ic. Each gate will be provided with appropriate input from the working principles of the ic will be
tested. Because the type of ic which will be tested more than one author use the keypad as a means to select the ic will be tested. The advantages of the ic tester is
to combine a series of writers using microcontroler 8952 and output results can be seen on display in the lcd, which is a condition of the ic , in addition to the authors hope that this tool can be operated easily by those who do not know about this tool before
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