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Träfflista för sökning "AMNE:(TEKNIKVETENSKAP Elektroteknik, elektronik och fotonik Övrig elektroteknik, elektronik och fotonik) "

Sökning: AMNE:(TEKNIKVETENSKAP Elektroteknik, elektronik och fotonik Övrig elektroteknik, elektronik och fotonik)

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1.
  • Chiragwandi, Zackary, 1968-, et al. (författare)
  • Properties of a bio-photovoltaic nano-device
  • 2008
  • Ingår i: The Journal of Physical Chemistry C. - 1932-7455. ; 112:48, s. 18717-18721
  • Tidskriftsartikel (refereegranskat)abstract
    • Properties of an on-chip photovoltaic nanodevice are demonstrated. The dyes comprise green florescent proteins (GFP). Dependence of recently reported zero external potential bias (ZEPB) photocurrent (I) on temperature, power, and wavelength (lambda) is shown. Correlation between UV-vis spectrum of the GFP and the ZEPB I(lambda) of the device is reported. The temperature dependence suggests the ZEPB photocurrent to reflect a liquid crystal type ordering where the current declines monotonically with increasing temperature. The influence of an external bias on the photocurrent is demonstrated. The resulting light-induced current is analyzed in terms of resistive and quantum mechanical contributions.
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2.
  • Haasl, S., et al. (författare)
  • Hybrid mounted micromachined aluminium hot-wire for near-wall turbulence measurements
  • 2002
  • Ingår i: 15th IEEE International Conference on Micro Electro Mechanical Systems, Las Vegas, Nevada, USA. - 0-7803-7185-2 ; s. 336-339
  • Konferensbidrag (refereegranskat)abstract
    • We present the first micromachined metal hot-wire anemometer sensor for use in near-wall turbulence measurements. To measure close to the surface without the circuitry interfering with the flow, a novel hybrid assembly of the sensor has been developed. We present the design, fabrication and characteristics of this sensor.
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3.
  • Löfdahl, Lennart, et al. (författare)
  • Characteristics of a hot-wire microsensor for time-dependent wall shear stress measurements
  • 2003
  • Ingår i: Experiments in Fluids. - 0723-4864. ; 35:3, s. 240-251
  • Tidskriftsartikel (refereegranskat)abstract
    • Hot-wire microsensors for the purpose of measuring the instantaneous velocity gradient close to a wall were designed and their characteristics were evaluated. The sensors were made using MEMS (microelectromechanical systems) technology, which permits the fabrication of various microgeometrical configurations with high precision and good repeatability. The design is based on estimates of the heat rates from the sensor wire to the air, through the supports, and to the wall. Several hot-wire configurations were fabricated with wires positioned in the range 50-250 mum from the wall. Requirements for the design and details of the fabrication methodology are outlined. The hot-wire microsensors were calibrated and tested in a flat-plate boundary layer with and without pressure gradients and were found to have good steady-state characteristics. In addition, the developed sensors were used for preliminary studies of transitional phenomena and turbulence, and the sensors were found to have a good time-dependent response as well.
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4.
  • Bjorsell, Niclas, et al. (författare)
  • Post-correction of under-sampled analog to digital converters
  • 2007
  • Ingår i: 2007 IEEE INSTRUMENTATION & MEASUREMENT TECHNOLOGY CONFERENCE. - 978-1-4244-0588-6 ; s. 58-62
  • Konferensbidrag (refereegranskat)abstract
    • Applications with wide bandwidth and high center frequencies force the analog to digital converter (ADC) to be active in a working range with less dynamic performance in relation to lower frequency bands. However using under-sampling techniques in combination with post-correction methods enable a combination of high sampling rate, wide bandwidth and low distortion. In this paper the employed dynamic post-correction is a combination of look-up tables and model based correction. The results are mainly based on measurements on a 12-bit 210 MSPS ADC. The improvement in total harmonic distortion and spurious free dynamic range are acceptable over a wide frequency range and it is robust to variations in amplitude.
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5.
  • Andrae, Anders, 1973-, et al. (författare)
  • Uncertainty estimation by Monte Carlo Simulation applied to Life Cycle Inventory of Cordless Phones and Microscale Metallization Processes
  • 2004
  • Ingår i: IEEE Transactions on Electronics Packaging Manufacturing. ; 27:4, s. 233-245
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper focuses on uncertainty analysis, that is, how the input data uncertainty affects the output data uncertainty in small but realistic product systems. The motivation for the study is to apply the Monte Carlo simulation for uncertainty estimation in life cycle inventory and environmental assessment of microelectronics applications. The present paper addresses the question whether there is an environmental advantage of using digital enhanced cordless telecommunications (DECT) phones instead of global system for mobile (GSM) phones in offices. This paper also addresses the environmental compatibility of electrochemical pattern replication (ECPR) compared to classical photolithography-based microscale metallization (CL) for pattern transfer. Both environmental assessments in this paper consider electricity consumption and CO2 emissions and the projects undertaken are two comparative studies of DECT phone/GSM phone and ECPR/CL, respectively. The research method used was probabilistic uncertainty modeling with a limited number of inventory parameters used in the MATLAB tool. For the DECT/GSM study the results reflects the longer DECT technical life which is an environmental advantage. For the electrochemical pattern replication (ECPR)/classical photolithography based microscale metallization (CL) study the results reflects the fewer number of process steps and the lower electricity consumption needed by the ECPR to reach the functional unit. The difference in results is large enough to be able to draw conclusions, as the processes, having the highest electricity consumption within the system boundaries have been determined. Based on an earlier work, a straightforward method to include uncertainty for input life cycle inventory data is used to quantify the influence of realistic errors for input data in two microelectronic applications. The conclusion is that the ECPR technology is more electricity efficient than CL in producing one layer of copper on a silicon wafer having a diameter of 20.32 cm. Furthermore, the longer technical life of a cordless DECT phone is reflected in an electricity/CO2 comparison with a GSM phone, if office use is considered. Reasonable uncertainty intervals, used for the input life cycle inventory data for the studied DECT/GSM and ECPR/CL system, does affect the outcome of calculation of emission of CO2, but not to the degree that conclusions are not valid. Different uncertainty intervals and probability distributions could apply for different types of data and the interrelated input data dependencies should be investigated. Today there exist very few life cycle inventory (LCI) data with the range of uncertainty for input and output elements. It must be emphasized that the upcoming LCI databases should have standard deviation characterized LCI data just as the Swiss ecoinvent LCI database. More inventory parameters and probability distributions characteristic for microsystems could be included and error analysis should be applied to future life inventory methodology, especially for future packaging concepts such as system-in-a-package and system-on-a-chip comparisons.
6.
  • Hertz, Hans, et al. (författare)
  • Laboratory Water-Window X-Ray Microscopy
  • 2009
  • Ingår i: 2009 IEEE LEOS ANNUAL MEETING CONFERENCE PROCEEDINGS : VOLS 1 AND 2. - 978-1-4244-3680-4 ; s. 48-48
  • Konferensbidrag (refereegranskat)abstract
    • We review recent progress in laboratory water-window microscopy including 250 W/0.8 ns/2 kHz laser-plasma liquid-jet sources, 13-nm zone width diffractive optics, diffractive optical elements for phase-contrast microscopy, <25-nm resolution microscopy using compound zone plates, tomography and applications in soil science.
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7.
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8.
  • Fredenberg, Erik, 1979- (författare)
  • Spectral Mammography with X-Ray Optics and a Photon-Counting Detector
  • 2009
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • Early detection is vital to successfully treating breast cancer, and mammography screening is the most efficient and wide-spread method to reach this goal. Imaging low-contrast targets, while minimizing the radiation exposure to a large population is, however, a major challenge. Optimizing the image quality per unit radiation dose is therefore essential. In this thesis, two optimization schemes with respect to x-ray photon energy have been investigated: filtering the incident spectrum with refractive x-ray optics (spectral shaping), and utilizing the transmitted spectrum with energy-resolved photon-counting detectors (spectral imaging).Two types of x-ray lenses were experimentally characterized, and modeled using ray tracing, field propagation, and geometrical optics. Spectral shaping reduced dose approximately 20% compared to an absorption-filtered reference system with the same signal-to-noise ratio, scan time, and spatial resolution. In addition, a focusing pre-object collimator based on the same type of optics reduced divergence of the radiation and improved photon economy by about 50%.A photon-counting silicon detector was investigated in terms of energy resolution and its feasibility for spectral imaging. Contrast-enhanced tumor imaging with a system based on the detector was characterized and optimized with a model that took anatomical noise into account. Improvement in an ideal-observer detectability index by a factor of 2 to 8 over that obtained by conventional absorption imaging was found for different levels of anatomical noise and breast density. Increased conspicuity was confirmed by experiment. Further, the model was extended to include imaging of unenhanced lesions. Detectability of microcalcifications increased no more than a few percent, whereas the ability to detect large tumors might improve on the order of 50% despite the low attenuation difference between glandular and cancerous tissue. It is clear that inclusion of anatomical noise and imaging task in spectral optimization may yield completely different results than an analysis based solely on quantum noise.
9.
  • Xu, Tianhua, 1984-, et al. (författare)
  • Digital compensation of chromatic dispersion in 112-Gbit/s PDM-QPSK system
  • 2009
  • Ingår i: 2009 Asia Communications and Photonics Conference and Exhibition, ACP 2009. - Shanghai. - 9781557528773
  • Konferensbidrag (refereegranskat)abstract
    • Coherent optical receivers with digital filters can mitigate the impairments in optical transmission system. In this paper, an adaptive filter employing NLMS algorithm is developed for chromatic dispersion compensation in a 112-Gbit/s PDM-QPSK coherent communication system. The performance of the adaptive filter is analyzed by comparing with present digital filters . ©2009 Optical Society of America.
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10.
  • Xu, Tianhua, 1984-, et al. (författare)
  • Frequency-domain chromatic dispersion equalization using overlap-add methods in coherent optical system
  • 2011
  • Ingår i: Journal of optical communications. - 0173-4911. ; 27:2
  • Tidskriftsartikel (refereegranskat)abstract
    • The frequency domain equalizers (FDEs) employing two types of overlap-add zero-padding (OLA-ZP) methods are applied to compensate the chromatic dispersion in a 112-Gbit/s non-return-to-zero polarization division multiplexed quadrature phase shift keying (NRZ-PDM-QPSK) coherent optical transmission system. Simulation results demonstrate that the OLA-ZP methods can achieve the same acceptable performance as the overlap-save method. The required minimum overlap (or zero-padding) in the FDE is derived, and the optimum fast Fourier transform length to minimize the computational complexity is also analyzed. 
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