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排序方式: 共有426条查询结果,搜索用时 15 毫秒
1.
The cascade correlation is a very flexible, efficient and fast algorithm for supervised learning. It incrementally builds the network by adding hidden units one at a time, until the desired input/output mapping is achieved. It connects all the previously installed units to the new unit being added. Consequently, each new unit in effect adds a new layer and the fan-in of the hidden and output units keeps on increasing as more units get added. The resulting structure could be hard to implement in VLSI, because the connections are irregular and the fan-in is unbounded. Moreover, the depth or the propagation delay through the resulting network is directly proportional to the number of units and can be excessive. We have modified the algorithm to generate networks with restricted fan-in and small depth (propagation delay) by controlling the connectivity. Our results reveal that there is a tradeoff between connectivity and other performance attributes like depth, total number of independent parameters, and learning time. 相似文献
2.
Ron Kimmel Doron Shaked Michael Elad Irwin Sobel 《IEEE transactions on image processing》2005,14(6):796-803
Gamut mapping deals with the need to adjust a color image to fit into the constrained color gamut of a given rendering medium. A typical use for this tool is the reproduction of a color image prior to its printing, such that it exploits best the given printer/medium color gamut, namely the colors the printer can produce on the given medium. Most of the classical gamut mapping methods involve a pixel-by-pixel mapping and ignore the spatial color configuration. Recently proposed spatial-dependent approaches for gamut mapping are either based on heuristic assumptions or involve a high computational cost. In this paper, we present a new variational approach for space-dependent gamut mapping. Our treatment starts with the presentation of a new measure for the problem, closely related to a recent measure proposed for Retinex. We also link our method to recent measures that attempt to couple spectral and spatial perceptual measures. It is shown that the gamut mapping problem leads to a quadratic programming formulation, guaranteed to have a unique solution if the gamut of the target device is convex. An efficient numerical solution is proposed with promising results. 相似文献
3.
Hansen P.B. Raybon G. Koren U. Miller B.J. Young M.G. Newkirk M.A. Chien M.-D. Tell B. Burrus C.A. 《Electronics letters》1993,29(9):739-741
A 2 cm long three-contact multisection laser has been fabricated for modelocking at very low repetition rates. Active modelocking yields 8.0-12.3 ps pulses at 2.2, 4.3 and 6.5 GHz corresponding to the fundamental, first, and second harmonics of the cavity resonance frequency. This device demonstrates the feasibility of fabricating monolithic pulse sources operating at rates as low as the OC-48 Sonet transmission rate (2.488 Gbit/s).<> 相似文献
4.
Polarisation insensitive semiconductor optical amplifier withintegrated electroabsorption modulators
Koren U. Miller B.I. Young M.G. Chien M. Raybon G. Brenner T. Ben-Michael R. Dreyer K. Capik R.J. 《Electronics letters》1996,32(2):111-112
The authors demonstrate a 1.55 μm wavelength multiquantum well semiconductor optical amplifier, integrated with bulk layer electroabsorption modulators and passive waveguide beam expanders at the input and output ports. The device has a fibre to fibre gain of 9 dB, an extinction ratio of 15 dB per modulator, a spectral range >35 nm, and polarisation sensitivity <1 dB 相似文献
5.
Layout-synthesis techniques for yield enhancement 总被引:1,自引:0,他引:1
Several yield-enhancement techniques are proposed for the last two stages of VLSI design, i.e., topological/symbolic and physical layout synthesis. Our approach is based on modifications of the symbolic/physical layout to reduce the sensitivity of the design to random point defects without increasing the area, rather than fault tolerance techniques. A layout compaction algorithm is presented and the yield improvement results of some industrial layout examples are shown. This algorithm has been implemented in a commercial CAD framework. Some routing techniques for wire length and via minimization are presented, and the results of wire length reduction in benchmark routing examples are shown. We demonstrate through topological optimization for PLA-based designs that yield enhancement can be applied even at a higher level of design abstraction. Experimental results show that it is possible to achieve significant yield improvements without increasing the layout area by applying the proposed techniques during layout synthesis 相似文献
6.
FF Fassos J Klein D Fernandes D Matsui NF Olivieri G Koren 《Canadian Metallurgical Quarterly》1996,34(7):288-292
Recently, we demonstrated that administration of the orally active iron chelating agent deferiprone (1,2-dimethyl-3-hydroxypyrid-4-one (L1)) at 6-hour intervals results in significantly greater urinary iron excretion than that induced during administration of the drug at 12-hour intervals. That study was conducted in thalassemia patients, all of whom had received a packed red cell transfusion of 15 cc/kg. 72 hours prior to evaluation of urinary iron excretion, at a time when endogenous erythropoiesis would be expected to be at its lowest. In clinical practice however, thalassemia patients, suppression of endogenous erythropoiesis is not sustained between transfusions. We set out to determine the influence that administration of deferiprone has on urinary iron excretion at lower hemoglobin concentrations, immediately prior to transfusion. We hypothesized that hemoglobin levels will affect the ability of deferiprone to chelate iron. Ten regularly transfused patients with homozygous beta-thalassemia (HBT) aged mean +/- SD, 20.9 +/- 4.7, range 13 - 27 years, receiving long-term therapy with deferiprone, were treated with deferiprone 75 mg/kg/day, administered every 6 hours (or every 12 hours) for 72 hours immediately prior to a blood transfusion in the first month. One month later each patient received the other of the 2 dosing regimens for 72 hours immediately prior to transfusion. The deferiprone-induced 24-hour urinary iron excretion was similar during both dosing regimens; 0.56 +/- 0.45 mg/kg when L1 was given every 6 hours and 0.48 +/- 0.52 mg/kg when L1 was administered every 12 hours (p = 0.79). However, the calculated 24-hour area under the plasma concentration-time curve (AUC0-24) of deferiprone was significantly lower when deferiprone was administered at 6-hour intervals (6,762.8 +/- 1,601.6 mg*min/l), than that observed when deferiprone was administered every 12 hours (8,250.1 +/- 1,235.7 mg*min/l) (p = 0.04). The pharmacokinetics of deferiprone when administered immediately prior to transfusions are different from those following transfusions. More studies assessing total body iron excretion are needed to determine the contribution of the fecal route in iron excretion. 相似文献
7.
Shoval S. Borenstein J. Koren Y. 《IEEE transactions on bio-medical engineering》1998,45(11):1376-1386
This paper presents a new concept for a travel aid for the blind. A prototype device, called the NavBelt, was developed to test this concept. The device can be used as a primary or secondary aid, and consists of a portable computer, ultrasonic sensors, and stereophonic headphone. The computer applies navigation and obstacle avoidance technologies that were developed originally for mobile robots. The computer then uses a stereophonic imaging technique to process the signals from the ultrasonic sensors and relays their information to the user via stereophonic headphones. The user can interpret the information as an acoustic “picture” of the surroundings, or, depending on the operational mode, as the recommended travel direction. The acoustic signals are transmitted as discrete beeps or continuous sounds. Experimental results with the NavBelt simulator and a portable prototype show that users can travel safely in an unfamiliar and cluttered environment at speeds of up to 0.8 m/s 相似文献
8.
Tauber D. Nagar R. Livne A. Eisenstein G. Koren U. Raybon G. 《Photonics Technology Letters, IEEE》1992,4(3):238-240
The authors report on the noise characteristics of InGaAs/InGaAsP multiple-quantum-well optical amplifiers operating near 1.5 μm. A noise figure of 4.4 dB is reported, verifying the predicted low-noise properties of quantum-well amplifiers 相似文献
9.
Woodward S.L. Koren U. Miller B.I. Young M.G. Newkirk M.A. Burrus C.A. 《Photonics Technology Letters, IEEE》1992,4(12):1330-1332
A distributed Bragg reflector (DBR) laser tuned by resistive heating is presented. It has a tuning range greater than 10 nm with only a 33% reduction in output power and a 10% increase in linewidth. Its behavior is easily modeled, agreeing well with simple theory 相似文献
10.
Wiesenfeld J.M. Gnauch A.H. Raybon G. Koren U. 《Photonics Technology Letters, IEEE》1992,4(7):708-711
A multiple-quantum-well optical amplifier is used at 8 Gb/s with high input power such that the average gain is compressed by 2.6 dB. Under these conditions, the output signal level is 35 mW and there is negligible intersymbol interference (ISI) penalty at the receiver. This is possible because of a rapid (7 ps) gain recovery process in the amplifier. A conventional semiconductor amplifier operating at a similar level of gain compression shows 2 dB ISI penalty 相似文献