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61.
Baumann Stephen B. Joines William T. Berman Ezra 《IEEE transactions on bio-medical engineering》1987,(9):754-757
Batteryless temperature transponders have been constructed and tested. The design employs a sensing element consisting of a miniature cavity resonator loaded with a ceramic material of high dielectric constant and large temperature coefficient of resonant frequency. This is connected by thin coaxial cable to a small dipole or sector antenna. Prototypes with sensors 3 mm in diameter have been fabricated and can resolve temperature differences of 0.1°C in air. Signals have been obtained from transponders implanted in anesthetized rats, but antenna orientation is a critical and limiting factor that will require further efforts before a system is capable of operating in freely roaming animals. 相似文献
62.
James M. Watkins Ronald Dermott Stephen J. Lozano Edward L. Mills Lars G. Rudstam Jill V. Scharold 《Journal of Great Lakes research》2007,33(3):642-657
The status of invasive dreissenid mussels (Dreissena polymorpha and D. bugensis) and native amphipods (Diporeia spp.) in Lake Ontario was assessed in 2003 and compared with historical data. D. polymorpha (zebra mussels) were rarely observed in 2003, having been displaced by D. bugensis (quagga mussels). D. bugensis expanded its depth range from 38 m depth in 1995 to 174 m in 2003 and this dreissenid reached densities averaging 8,000/m2 at all sites < 90 m. During the same time period, Diporeia populations almost completely disappeared from 0–90 m depth, continuing a declining trend from 1994–1997 reported in previous studies. The average density of Diporeia in the 30–90 m depth interval decreased from 1,380/m2 to 63/m2 between 1997 and 2003. Prior to 2003, areas deeper than 90 m represented a refuge for Diporeia, but even these deep populations decreased, with densities declining from 2,181/m2 in 1999 to 545/m2 in 2003. Two common hypotheses for the decline of Diporeia in the Great Lakes are food limitation and a toxin/pathogen associated with dreissenid pseudofeces. The Diporeia decline in deep waters preceded the expansion of D. bugensis to these depths, and suggests that shallow dreissenid populations remotely influence profundal habitats. This pattern of decline is consistent with mechanisms that act from some distance including nearshore dreissenid grazing and downslope transport of pseudofeces. 相似文献
63.
Research presented in this paper deals with the systematic examination, development, and evaluation of a novel multimodal registration approach that can perform accurately and robustly for relatively close range surveillance applications. An analysis of multimodal image registration gives insight into the limitations of assumptions made in current approaches and motivates the methodology of the developed algorithm. Using calibrated stereo imagery, we employ maximization of mutual information in sliding correspondence windows that inform a disparity voting algorithm to demonstrate successful registration of objects in color and thermal imagery. Extensive evaluation of scenes with multiple objects at different depths and levels of occlusion shows high rates of successful registration. Ground truth experiments demonstrate the utility of the disparity voting techniques for multimodal registration by yielding qualitative and quantitative results that outperform approaches that do not consider occlusions. A basic framework for multimodal stereo tracking is investigated and promising experimental studies show the viability of using registration disparity estimates as a tracking feature. 相似文献
64.
Gabriele Pannocchia Author Vitae Author Vitae Stephen J. Wright Author Vitae 《Automatica》2007,43(5):852-860
Partial enumeration (PE) is presented as a method for treating large, linear model predictive control applications that are out of reach with available MPC methods. PE uses both a table storage method and online optimization to achieve this goal. Versions of PE are shown to be closed-loop stable. PE is applied to an industrial example with more than 250 states, 32 inputs, and a 25-sample control horizon. The performance is less than 0.01% suboptimal, with average speedup factors in the range of 80-220, and worst-case speedups in the range of 4.9-39.2, compared to an existing MPC method. Small tables with only 25-200 entries were used to obtain this performance, while full enumeration is intractable for this example. 相似文献
65.
A multiparameter wearable physiologic monitoring system for space and terrestrial applications. 总被引:4,自引:0,他引:4
Carsten W Mundt Kevin N Montgomery Usen E Udoh Valerie N Barker Guillaume C Thonier Arnaud M Tellier Robert D Ricks Robert B Darling Yvonne D Cagle Nathalie A Cabrol Stephen J Ruoss Judith L Swain John W Hines Gregory T A Kovacs 《IEEE transactions on information technology in biomedicine》2005,9(3):382-391
A novel, unobtrusive and wearable, multiparameter ambulatory physiologic monitoring system for space and terrestrial applications, termed LifeGuard, is presented. The core element is a wearable monitor, the crew physiologic observation device (CPOD), that provides the capability to continuously record two standard electrocardiogram leads, respiration rate via impedance plethysmography, heart rate, hemoglobin oxygen saturation, ambient or body temperature, three axes of acceleration, and blood pressure. These parameters can be digitally recorded with high fidelity over a 9-h period with precise time stamps and user-defined event markers. Data can be continuously streamed to a base station using a built-in Bluetooth RF link or stored in 32 MB of on-board flash memory and downloaded to a personal computer using a serial port. The device is powered by two AAA batteries. The design, laboratory, and field testing of the wearable monitors are described. 相似文献
66.
67.
Dobutamine stress echocardiography is a safe method for the evaluation of coronary artery disease, myocardial function, and viability. The potential for cardiac rupture exists. Although clinical and electrocardiographic criteria may be helpful in identifying those patients at risk for cardiac rupture, the criteria are neither sensitive nor specific enough to exclude patients or make recommendations regarding which patients should undergo dobutamine stress echocardiography in the post-infarction period. Physicians must be aware of the possibility and be prepared to treat cardiac rupture when performing dobutamine stress echocardiography. 相似文献
68.
Stephen V. Stehman 《Remote sensing of environment》1997,60(3):258-269
Cluster sampling is a viable sampling design for collecting reference data for the purpose of conducting an accuracy assessment of land-cover classifications obtained from remotely sensed data. The formulas for estimating various accuracy parameters such as the overall proportion of pixels correctly classified, the kappa coefficient of agreement, and user's and producer's accuracy are the same under cluster sampling and simple random sampling, but the formulas for estimating standard errors differ between the two designs. If standard error formulas appropriate for cluster sampling are not employed in an accuracy assessment based on this design, the reported variability of map accuracy statistics is likely to be grossly misleading. The proper standard error formulas for common map accuracy statistics are derived for one-stage cluster sampling. The validity of these standard error formulas is verified by a small simulation study, and the standard errors computed according to the usual simple random sampling formulas are shown to underestimate the true cluster sampling standard errors by 20–70% if the intracluster correlation is moderate. 相似文献
69.
A new method is outlined which aims to predict high-cycle fatigue behavior of components which fail from stress-concentrators. This involves examination of the stress field in the vicinity of the stress-concentrator, and comparison with stress fields for cracks at known stress intensities. Methods which are currently used for simple notch geometries can thus be generalised, making the approach applicable to stress concentrators of any geometry. The method of prediction is shown to be stable, providing a solution of good accuracy when compared to analytical methods for standard specimen geometries. Favourable comparisons with experimental data have been achieved both for standard notches and for a corner geometry which represents a typical component case. 相似文献
70.
Stephen E. Sussman-Fort 《国际射频与微波计算机辅助工程杂志》1991,1(3):288-305
Matching networks, as used between the consecutive stages of an amplifier to manage the transfer of power between the complex source impedance, the active devices, and the load, continue to be of importance, particularly in microwave systems. Synthesis techniques for these networks have evolved from the classical theory to novel numerical approaches that yield significant practical advantages. We review here several well-known design methods, including the classical derivation, sloped-approximation synthesis, and the real-frequency technique. Also considered are enhancements and variations of these methods. Furthermore, we describe the iterated analysis approach, which appears to provide the greatest design flexibility, efficiency, and accuracy to date. Examples are given which illustrate the relative merits of some of the more modern computer-assisted techniques. Finally, we discuss ideas for further research in the area of matching network synthesis. 相似文献