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排序方式: 共有139条查询结果,搜索用时 312 毫秒
31.
This paper presents a novel event detector for implantable devices. The algorithm is based on a signal model which describes an event as a linear combination of basis functions. The linear combination involves two fundamental electrogram waveforms represented at different time scales. An efficient, low-complexity detector is developed using the dyadic wavelet transform with integer filter coefficients, and a generalized likelihood ratio test. The results show that reliable detection is obtained at an intermediate signal-to-noise ratio (SNR = 25 dB) for various common noise sources. In terms of probabilities of missed events and false alarms, an over-all performance of 0.7% and 0.1%, respectively, was achieved on electrograms corrupted by the different noise types at an intermediate SNR. 相似文献
32.
Effect of dietary crude protein concentration on milk production and nitrogen utilization in lactating dairy cows 总被引:3,自引:0,他引:3
Forty lactating Holstein cows, including 10 with ruminal cannulas, were blocked by days in milk into 8 groups and then randomly assigned to 1 of 8 incomplete 5 × 5 Latin squares to assess the effects of 5 levels of dietary crude protein (CP) on milk production and N use. Diets contained 25% alfalfa silage, 25% corn silage, and 50% concentrate, on a dry matter (DM) basis. Rolled high-moisture shelled corn was replaced with solvent-extracted soybean meal to increase CP from 13.5 to 15.0, 16.5, 17.9, and 19.4% of DM. Each of the 4 experimental periods lasted 28 d, with 14 d for adaptation and 14 d for data collection. Spot sampling of ruminal digesta, blood, urine, and feces was conducted on d 21 of each period. Intake of DM was not affected by diet but milk fat content as well as ruminal acetate, NH3, and branched-chain volatile fatty acids, urinary allantoin, and blood and milk urea all increased linearly with increasing CP. Milk and protein yield showed trends for quadratic responses to dietary CP and were, respectively, 38.3 and 1.18 kg/d at 16.5% CP. As a proportion of N intake, urinary N excretion increased from 23.8 to 36.2%, whereas N secreted in milk decreased from 36.5 to 25.4%, as dietary protein increased from 13.5 to 19.4%. Under the conditions of this study, yield of milk and protein were not increased by feeding more than 16.5% CP. The linear increase in urinary N excretion resulted from a sharp decline in N efficiency as dietary CP content increased. 相似文献
33.
Guillermo Jorge-Botana Ricardo Olmos Alejandro Barroso 《International Journal of Speech Technology》2012,15(2):151-164
Semantic technology is commonly used for two purposes in the field of IVR (Interactive Voice Response). The first is to correct
the output of voice recognition devices based on coherence with a context. The second is to perform what is referred to as
“call routing”, requiring technology that categorizes utterances and returns a list of the most credible routes. Our paper
focuses on the latter, aiming to use the Latent Semantic Analysis (LSA henceforth) computational model (Deerwester et al.
in J. Am. Soc. Inf. Sci. 41:391–407, 1990) together with the Construction-Integration model (C-I henceforth), a psycholinguistically motivated algorithm (Kintsch in
Int. J. Psychol. 33(6):411–420, 1998), to interpret, manage and successfully route user requests in an efficient and reliable manner. By efficient we mean that
training is unnecessary when the destination model is altered, and exhaustive labeling of all utterances is not required,
concentrating instead only on some sample destinations. By reliable we mean that the construction-integration algorithm attenuates
the risks from intra-destination variability and word saliency. Technical and theoretical aspects are discussed. In addition,
some destination assignment methods are tested and debated. 相似文献
34.
Microwave Signal Generation and Transmission Based on Optical Frequency Multiplication With a Polarization Interferometer 总被引:1,自引:0,他引:1
Larrode M.G. Koonen A.M.J. Olmos J.J.V. Verdurmen E.J.M. 《Lightwave Technology, Journal of》2007,25(6):1372-1378
A novel scheme is proposed and experimentally demonstrated for the generation of microwaves, based on the optical frequency multiplication principle employing a polarization interferometer. Generation of 120-Mb/s 64-quadrature-amplitude-modulation microwave signals at 40 and 24 GHz and its transmission over 25 km of single-mode fiber and 4.4 km of multimode fiber, respectively, are successfully demonstrated. The scheme is robust against laser phase noise, presents tolerance against dispersion impairments in transmission, and shows high-performance stability. 相似文献
35.
In this work, a new material based on an epoxy thermoset modified with a thermoplastic filled with silica nanoparticles was investigated. When thermoplastic particles are filled with nanoparticles with unique properties such as high efficiency for absorbing ultraviolet light, electric or magnetic shielding, high electrical conductivity, and high dielectric constants, more than an enhancement of the mechanical properties is expected to be achieved for modified epoxy‐based thermosets. Particles of poly(methyl methacrylate) (PMMA) filled with silica nanoparticles were used to modify a thermoset based on a full reaction between diglycidyl ether of bisphenol A and 3‐(aminomethyl)benzylamine. When the preformed thermoplastic particles were mixed with the reactive constituents of the epoxy system under certain curing conditions in which total miscibility was avoided, uniform particle dispersions could be obtained. The relationships between the composition, morphology (nanoscale and microscale), glass‐transition temperature, mechanical properties, and fracture toughness were considered. Four main results were obtained for consideration of the potential of silica‐filled PMMA as an important modifier of brittle epoxy thermoset systems: (1) a good dispersion of the silica nanoparticles in the PMMA domains, (2) a good dispersion of the silica‐filled PMMA microparticles in the epoxy matrix, (3) the possibility of partial dissolution of the PMMA‐rich domains into the epoxy system, and (4) a slight increase in properties such as the hardness, indentation modulus, and fracture toughness. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 相似文献
36.
This paper presents a comprehensive design of electricity transmission charges that are meant to recover regulated network costs. In addition, these charges must be able to meet a set of inter-related objectives. Most importantly, they should encourage potential network users to internalize transmission costs in their location decisions, while interfering as least as possible with the short-term behaviour of the agents in the power system, since this should be left to regulatory instruments in the operation time range. The paper also addresses all those implementation issues that are essential for the sound design of a system of transmission network charges: stability and predictability of the charges; fair and efficient split between generation and demand charges; temporary measures to account for the low loading of most new lines; number and definition of the scenarios to be employed for the calculation and format of the final charges to be adopted: capacity, energy or per customer charges. The application of the proposed method is illustrated with a realistic numerical example that is based on a single scenario of the 2006 winter peak in the Spanish power system. 相似文献
37.
J.J.V. Olmos I.T. Monroy A.M.J. Koonen 《Photonics Technology Letters, IEEE》2006,18(3):496-498
We demonstrate an all-optical label and payload separator based on nonlinear optical signal processing with a semiconductor optical amplifier. The separator handles return-to-zero intensity modulated packets with high bandwidth efficiency utilization. 相似文献
38.
Novel inverted-F antennas, double-wire (DW-IFA) and double-strip (DS-IFA) were developed for f0 = 2.45 GHz, and a 0.8λ 0 in size square ground plate. The antennas are distinctive for their wideband match performance, 12% (numerical) for DW-IFA and 18% (numerical)/17% (experimental) for DS-IFA, and radiation characteristics suitable for the mobile environment scenario 相似文献
39.
40.
García J Sörnmo L Olmos S Laguna P 《IEEE transactions on bio-medical engineering》2000,47(9):1195-1201
A new detector is presented which finds changes in the repolarization phase (ST-T complex) of the cardiac cycle. It operates by applying a detection algorithm to the filtered root mean square (rms) series of differences between the beat segment (ST segment or ST-T complex) and an average pattern segment. The detector has been validated using the European ST-T database, which contains ST-T complex episodes manually annotated by cardiologists, resulting in sensitivity/positive predictivity of 85/86%, and 85/76%, for ST segment deviations and ST-T complex changes, respectively. The proposed detector has a performance similar to those which have a more complicated structure. The detector has the advantage of finding both ST segment deviations and entire ST-T complex changes thereby providing a wider characterization of the potential ischemic events. A post-processing stage, based on a cross-correlation analysis for the episodes in the rms series, is presented. With this stage subclinical events with repetitive pattern were found in around 20% of the recordings and improved the performance to 90/85%, and 89/76%, for ST segment and ST-T complex changes, respectively. 相似文献