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ABSTRACT: In this paper a novel Ka-band cavity-backed elliptically-shaped dipole antenna to be manufactured using multi-layer low temperature co-fired ceramic (LTCC) technology is presented. Ultra-wideband non-absorbing shielding has been developed to reduce backward antenna radiation. Differential feeding is used for easy matching to RF circuits with differential input/output. The antenna simulated impedance bandwidth is from 25.5 GHz to 29.5 GHz. Antenna has been manufactured and measured. The measurement results qualitatively confirmed simulation results.
Ultra-Wideband, 2008. ICUWB 2008. IEEE International Conference on; 10/2008
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ABSTRACT: To evaluate the influence of enterotoxigenic Escherichia coli (ETEC) F4 receptors on production traits in pigs, ETEC F4ab, F4ac, and F4ad adhesion phenotypes and 27 traits related to growth, carcass, meat quality, and length of the small intestine in a White Duroc x Erhualian intercross population were measured. Performance data revealed that pigs with the F4ab or F4ac receptor (adhesive phenotypes) had greater (P < 0.01) ADG during the fattening period (from 46 to 240 d) and carcass weight and length at 240 d than pigs lacking the receptors (nonadhesive phenotype). Conversely, animals having the F4ad receptor had less (P < 0.01) ADG during the fattening period and carcass weight than those lacking the receptor. In total, 8 adhesion patterns (A to H) for the 3 F4 strains were observed in this experimental population. Pigs with both F4ab and F4ac receptors (phenotype B) had greater (P < 0.01) ADG, carcass weight, and length at 240 d compared with pigs without the F4 receptors. No difference was found (P > 0.05) in traits related to meat quality, fatness, and length of the small intestine between pigs with or without the receptors. On the basis of the antagonistic relationship between susceptibility to F4ab/ac and production traits, we speculate that the prevalence of the ETEC F4ab/ac adhesive phenotype in pig populations is attributable to balanced natural and artificial selection.
Journal of Animal Science 09/2008; 87(1):334-9. · 2.10 Impact Factor
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ABSTRACT: To produce 3D high-resolution images of buried landmines, a novel UWB antenna array with electrically steered footprint has been developed in IRCTR. In this paper, focusing capabilities of the array are studied. The interaction between elements in the array and its influence on the near-field footprint is investigated. It is shown that the most interaction is due to scattering of incident field on array elements. This interaction not only changes the antenna input impedance, but also significantly influences the array focusing capability and footprint quality, which are closely related to the radar image quality. Thus, it is important to take these effects into account by array design.
Antennas and Propagation, 2007. EuCAP 2007. The Second European Conference on; 12/2007
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ABSTRACT: A probe-deconvolution technique for a buried probe is developed. The technique is based on an accurate electromagnetic model of a buried probe, which predicts voltage at the output terminals of the probe for any impinging wave. The model is based on analytical solution of a Pocklington equation describing surface current on the probe. The model does not take into account presence of air-ground interface close to the probe. The model has been successfully verified against direct numerical simulations based on Mixed Potential Integral Equation with an appropriate Green function. Special attention has been paid in the verification to the impact of the so-called head wave which is excited by GPR antennas operating in a close proximity to the ground and propagating along air-ground interface.
Antennas and Propagation, 2007. EuCAP 2007. The Second European Conference on; 12/2007
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ABSTRACT: A series of novel 3-phenyl-2-ethylthio/ethylsulfinyl/ethylsulfonyl/phenylthio/ phenylsulfonyl-quinoxaline 1,4-dioxide derivatives were synthesized and screened for their cytotoxicity in vitro on human leukaemia cell line HL-60, human esophagus cancer cell line ECA-109, human prostate cancer cell line PC-3, human gastric carcinoma cell line SGC-7901, and human breast cancer cell line MCF-7 in hypoxia and in normoxia. Half of tested compounds showed higher cytotoxic activity both in hypoxia and in normoxia. The mechanism of one potent compound, 67, in hypoxia showed that the mitochondria pathway is involved in the antitumor activity of this class of compounds.
Drug discoveries & therapeutics. 10/2007; 1(2):119-23.
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ABSTRACT: The duration of the x-ray pulse generated at a synchrotron light source is typically tens of picoseconds. Shorter pulses are highly desired by the users. In electron storage rings, the vertical beam size is usually orders of magnitude less than the bunch length due to radiation damping; therefore, a shorter pulse can be obtained by slitting the vertically tilted bunch. Zholents proposed tilting the bunch using rf deflection. We found that tilted bunches can also be generated by a dipole magnet kick. A vertical tilt is developed after the kick in the presence of nonzero chromaticity. The tilt was successfully observed and a 4.2-ps pulse was obtained from a 27-ps electron bunch at the Advanced Photon Source. Based on this principle we propose a short-pulse generation scheme that produces picosecond x-ray pulses at a repetition rate of 1 utilde2 kHz, which can be used for pump-probe experiments.
Particle Accelerator Conference, 2007. PAC. IEEE; 07/2007
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M. Borland,
J. Carwardine,
Y. Chae,
L. Emery,
P. Den Hartog,
K. Harkay,
A. Lumpkin,
A. Nassiri,
V. Sajaev,
N. Sereno,
G. Waldschmidt, B. Yang,
V. Dolgashev
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ABSTRACT: Recently, we have explored application to the Advanced Photon Source (APS) of Zholents[1] crab cavity scheme for production of short x-ray pulses. We assumed use of superconducting (SC) cavities in order to have a continuous stream of crabbed bunches and flexibility of operating modes. The challenges of the SC approach are related to the size, cost, and development time of the cavities and associated systems. A good case can be made [2] for a pulsed system using room-temperature cavities. APS has elected to pursue such a system in the near term, with the SC-based system planned for a later date. This paper describes the motivation for the pulsed system and gives an overview of the planned implementation and issues. Among these are overall configuration options and constraints, cavity design options, frequency choice, cavity design challenges, tolerances, instabilities, and diagnostics plans.
Particle Accelerator Conference, 2007. PAC. IEEE; 07/2007
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ABSTRACT: In this paper, we proposed a simple algorithm to increase the MC-CDMA system capacity in an indoor mobile environment. This algorithm combines an efficient blind adaptive beamforming based on maximum signal-to-interference-noise ratio (MSINR) with the power control (PC). It has low computational complexity and converges fast. Simulation results show that with the beamforming only, the SINR improves about 7.9 dB. With the power control add to it, the overall system capacity is further increased about 23%. In addition, the algorithm can assign different target BER to different users. This can further increase the overall system capacity.
Vehicular Technology Conference, 2007. VTC2007-Spring. IEEE 65th; 05/2007
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ABSTRACT: A generic numerical tool has been developed to compute/optimize the sensitivity of array antenna receiver systems. This antenna system simulator is comprised of an ElectroMagnetic (EM) simulator and a MicroWave simulator (MW) for modeling the signal and noise characteristics of each receiver component. This analysis includes accurate modeling of the background noise (sky+ground), which is essential in radio astronomical applications, as well as the losses, reflections and noise contributions that occur in the microwave beamforming network. Validation has been carried out for a 4x1 monopole array receiver system. The modeled absolute power levels for a noisy 'hot' and 'cold' environment are in very good agreement with the measured noise power levels.
Antennas and Propagation, 2006. EuCAP 2006. First European Conference on; 12/2006
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ABSTRACT: This paper investigates the influence of different types of disturbances to the estimation of voice quality parameters. Here, voice quality is not only based on the pitch or pitch contour as in many approaches. The parameters are estimated by spectral gradients of the vocal tract compensated speech signal. We present a set of five parameters for describing the voice quality. They are used to distinguish between gender, voice qualities, and many emotional states of the speaker. We estimate them from speech signals which are corrupted by background noise and room reverberation. The paper demonstrates a certain degree of robustness of the voice quality parameters against these real world disturbances
Acoustics, Speech and Signal Processing, 2006. ICASSP 2006 Proceedings. 2006 IEEE International Conference on; 06/2006 · 4.63 Impact Factor
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ABSTRACT: A method for producing short electron bunches in an electron storage ring using pulsed phase modulation has been demonstrated. A simple theoretical model was validated using the particle tracking code elegant, and the bunch compression process was observed experimentally in the Advanced Photon Source storage ring using a visible light streak camera. Compression to 54% of the initial bunch length was achieved.
Physical Review Special Topics. 12/2005; 9(12).
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ABSTRACT: A heterojunction has been fabricated by growing a La <sub>0.67</sub> Ca <sub>0.33</sub> Mn O <sub>3</sub> film on silicon with a buffer layer of yttrium-stabilized zirconia (YSZ). The current-voltage measurement shows that it is a diode with a good rectifying property. At low positive bias voltage, temperature dependence of the junction resistance shows a peak at a certain temperature, which shifts to low temperatures when the voltage is increased from 0.3 V to 0.7 V . This behavior is quite different from the previous reports on p-n junctions composed of manganites and Nb-doped Sr Ti O <sub>3</sub> . The heterojunction shows remarkable magnetoresistance for both positive and negative biases. The results were discussed by considering the depletion layers in both La <sub>0.67</sub> Ca <sub>0.33</sub> Mn O <sub>3</sub> and Si, and the tunneling through YSZ. This work shows the potential application of integrating manganite-based devices and semiconductor circuits.
Applied Physics Letters 09/2005; · 3.84 Impact Factor
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ABSTRACT: We report the colossal negative electroresistance (ER) in the p‐n heterostructure of La0.67Ca0.33MnO3−δ (LCMO) and Nb-doped SrTiO3. For a vacuum-annealed sample, a maximum ER of 4×104% can be reached by 1 mA current and magnetic field has remarkable influence on the ER of the sample. It is interesting that the magnetoresistance of the heterostructure can also be tuned by electric current. The results were explained by the current shunting model. In this scenario, the current shunting is determined by the resistance of LCMO and the junction resistance. On the other hand, the resistance of LCMO and the junction resistance are also affected by current. The interaction of these factors can tune the electrical transport of the heterostructure dramatically. This work shows that manganites combined with other materials can result in some interesting properties that may have potential applications.
Applied Physics Letters 08/2005; 87(7):072506-072506-3. · 3.84 Impact Factor
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ABSTRACT: We show that X-ray pulses one order of magnitude shorter than the electron bunch length can be obtained through synchrobetatron coupling. A 6-ps rms visible light pulse from a 30-ps rms electron bunch was observed using a streak camera. Theory, simulation, and experimental results are presented.
Particle Accelerator Conference, 2005. PAC 2005. Proceedings of the; 06/2005
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ABSTRACT: A vertical beam instability has been observed for some time in the particle accumulator ring (PAR) of APS. It appears at low beam current when a single linac bunch is selected for PAR injection and is highly reproducible. An investigation was conducted to characterize and understand this instability. We obtained some interesting data and believe this was due to ion trapping. A more stable lattice was established as result of the investigation. This report summarizes the experimental results and gives some preliminary analysis.
Particle Accelerator Conference, 2005. PAC 2005. Proceedings of the; 06/2005
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K. Harkay,
M. Borland,
Y.-C. Chae,
G. Decker,
R. Dejus,
L. Emery,
W. Guo,
D. Horan,
K.-J. Kim,
R. Kustom,
D. Mills,
S. Milton,
A. Nassiri,
G. Pile,
V. Sajaev,
S. Shastri,
G. Waldschmidt,
M. White, B. Yang,
A. Zholents
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ABSTRACT: There is growing interest within the user community to utilize the pulsed nature of synchrotron radiation from storage ring sources. Conventional third-generation light sources can provide pulses on the order of 100 ps but typically cannot provide pulses of about 1 ps that some users now require to advance their research programs. However, it was recently proposed by A. Zholents et al. to use rf orbit deflection to generate sub-ps x-ray pulses [1]. In this scheme, two crab cavities are used to deliver a longitudinally dependent vertical kick to the beam, thus exciting longitudinally correlated vertical motion of the electrons. This makes it possible to spatially separate the radiation coming from different longitudinal parts of the beam. An optical slit can then be used to slice out a short part of the radiation pulse, or an asymmetrically cut crystal can be used to compress the radiation in time. In this paper we present a feasibility study of this method applied to the Advanced Photon Source (APS). We find that the pulse length can be decreased down to a 1 ps range using superconducting crab cavities.
Particle Accelerator Conference, 2005. PAC 2005. Proceedings of the; 06/2005
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ABSTRACT: This paper presents a theoretical analysis of the Cramer-Rao lower bound for source localization from time differences of arrival. We derive properties of the Cramer-Rao bound and design optimum sensor arrays which minimize the bound.
Acoustics, Speech, and Signal Processing, 2005. Proceedings. (ICASSP '05). IEEE International Conference on; 04/2005 · 4.63 Impact Factor
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ABSTRACT: We demonstrate the new features of a polyurethane shape memory polymer: water-driven actuation and recovery in sequence (i.e., programmable). Hydrogen bonding is identified as the reason behind these features. In addition, the absorbed water is quantitatively separated into two parts, namely, the free water and bound water. Their individual contribution on the glass transition temperature is identified.
Applied Physics Letters 04/2005; · 3.84 Impact Factor
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ABSTRACT: Recently, significant progress has been made on GaAs metal-oxide-semiconductor field-effect transistors (MOSFETs) using atomic-layer deposition (ALD)-grown Al <sub>2</sub> O <sub>3</sub> as gate dielectric. We show here that further improvement can be achieved by inserting a thin In <sub>0.2</sub> Ga <sub>0.8</sub> As layer as part of the channel between Al <sub>2</sub> O <sub>3</sub> and GaAs channel. A 1-μm-gate-length, depletion-mode, n-channel In <sub>0.2</sub> Ga <sub>0.8</sub> As/GaAs MOSFET with an Al <sub>2</sub> O <sub>3</sub> gate oxide of 160 Å shows a gate leakage current density less than 10<sup>-4</sup> A/cm <sup>2</sup>, a maximum transconductance ∼105 mS/mm, and a strong accumulation current at V<sub> gs </sub>≫0 in addition to buried-channel conduction. Together with longer gate-length devices, we deduce electron accumulation surface mobility for In <sub>0.2</sub> Ga <sub>0.8</sub> As as high as 660 cm<sup>2</sup>/V s at Al <sub>2</sub> O <sub>3</sub>/ In <sub>0.2</sub> Ga <sub>0.8</sub> As interface. © 2004 American Institute of Physics.
Applied Physics Letters 02/2004; · 3.84 Impact Factor
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Advanced Materials 10/2003; 15(20):1712 - 1715. · 13.88 Impact Factor
