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排序方式: 共有349条查询结果,搜索用时 15 毫秒
251.
The article gives analytical review of the mining and dressing waste situation and the experience gained in the waste exploration and reprocessing in Russia. The authors offer a new procedural approach to the appraisal and calculation of mining and dressing waste accumulations with intent of their re-processing. The approach has been tested under conditions of diamond-containing mining and dressing waste sites. 相似文献
252.
Goldring S. Lavi R. Tal A. Lebiush E. Tzuk Y. Jackel S. 《Quantum Electronics, IEEE Journal of》2004,40(4):384-389
Heat generation and laser performance of Nd:YAG oscillators pumped in two regimes, band pumping at /spl sim/808 nm and "thermally boosted" (TB) pumping at 884.5 nm, are compared. The crystal, pumped with a Ti:sapphire laser, lased with slope efficiencies of 52% and 57% when pumped at 802 and 884.5 nm, respectively. The heat generated during lasing was found to be 27% lower with TB pumping as compared to traditional band pumping. Moreover, the experimental results suggest that the coupling efficiency between the pump band and the upper lasing level (the quantum efficiency) is unity, and about 8% of the upper lasing level population decays via nonradiative channels. 相似文献
253.
Indoor positioning systems based on Received Signal Strength Indicator (RSSI) in Wireless Sensor Networks (WSNs) are commonly used. The position accuracy in these systems is highly affected by the wireless medium variability, and therefore, a precise calibration is necessary to translate the power measurements to corresponding distance between each pair of nodes. In this paper, we propose a calibration scheme that is tailored to Body Area Networks (BANs) applications. The a priori knowledge about the environment conditions in these applications can increase the accuracy of the localization system, improve its robustness to interference, and reduce the number of RSSI measurements which are required for the calibration process compared to the traditional calibration methods. We define a criterion to obtain the calibration scheme using different a priori knowledge for both the mapping table and the path-loss model parameters. For evaluation of our new calibration scheme, we conducted a series of experiments in a real-world indoor environment, focusing on a proximate environment that is commonly used in BANs. We showed that for a tracking application, calibration methods utilizing the a priori knowledge are superior in terms of localization accuracy over other existing calibration methods with relatively small number of offline measurements. 相似文献
254.
Karimaghaloo Z Shah M Francis SJ Arnold DL Collins DL Arbel T 《IEEE transactions on medical imaging》2012,31(6):1181-1194
Gadolinium-enhancing lesions in brain magnetic resonance imaging of multiple sclerosis (MS) patients are of great interest since they are markers of disease activity. Identification of gadolinium-enhancing lesions is particularly challenging because the vast majority of enhancing voxels are associated with normal structures, particularly blood vessels. Furthermore, these lesions are typically small and in close proximity to vessels. In this paper, we present an automatic, probabilistic framework for segmentation of gadolinium-enhancing lesions in MS using conditional random fields. Our approach, through the integration of different components, encodes different information such as correspondence between the intensities and tissue labels, patterns in the labels, or patterns in the intensities. The proposed algorithm is evaluated on 80 multimodal clinical datasets acquired from relapsing-remitting MS patients in the context of multicenter clinical trials. The experimental results exhibit a sensitivity of 98% with a low false positive lesion count. The performance of the proposed algorithm is also compared to a logistic regression classifier, a support vector machine and a Markov random field approach. The results demonstrate superior performance of the proposed algorithm at successfully detecting all of the gadolinium-enhancing lesions while maintaining a low false positive lesion count. 相似文献
255.
We examined the effects of naturally occurring mastitis on bovine oocyte developmental competence in vitro. Specifically, we investigated the effects of intramammary infection on the ovarian pool of oocytes (i.e., follicle-enclosed oocytes) and their ability to undergo in vitro maturation, fertilization, and further development to the blastocyst stage. Culled Holstein cows (n = 50) from 9 commercial dairy farms in Israel were allotted to 3 groups according to somatic cell count (SCC) records of the last 3 monthly milk tests as well as of quarter samples collected before slaughter: (1) low SCC (n = 7), (2) medium SCC (n = 16), or (3) high SCC (n = 27). Means of SCC values differed among low-, medium-, and high-SCC groups: 148,000, 311,000 and 1,813,000 cell/mL milk, respectively. Milk yield and days in milk did not differ among the 3 groups. Bacterial isolates included coagulase-negative staphylococci, Escherichia coli, Streptococcus dysgalactiae, or no bacteria found. Ovaries were collected at the abattoir and brought to the laboratory. Cumulus oocyte complexes were recovered separately from each cow and subjected individually to in vitro maturation and fertilization, followed by 8 d in culture. The number of aspirated oocytes did not differ among groups, with a range of 17 to 21 oocytes per cow. The proportion of oocytes that cleaved into 2- to 4-cell-stage embryos (86.1 ± 3.4%) did not differ among groups. In contrast, mean percentages of embryos developed to the blastocyst stage on d 7 and 8 after fertilization were less in both medium- and-high SCC groups than in the low-SCC group (5.6 ± 2.3 and 4.1 ± 1.8 vs. 18.1 ± 4.6%, respectively). Additional analysis indicated that cleavage and blastocyst-formation rates did not differ among the bacterial types in the low-, medium-, and high-SCC groups. These are the first results to demonstrate that naturally occurring mastitis disrupts the developmental competence of the ovarian pool of oocytes, (i.e., oocytes at the germinal vesicle stage). The disruption was associated with elevation of SCC rather than bacterial type. The results may provide a partial explanation for the low fertility of cows that have contracted mastitic pathogens before insemination. 相似文献
256.
The problem of determining the pull-in range of phaselocked loops is solved indirectly by evaluating the limit cycles of the loop in which the frequency error has a constant average. The analytical results derived here are in complete agreement with simulation results. 相似文献
257.
Coyne James C.; Kessler Ronald C.; Tal Margalit; Turnbull Joanne; Wortman Camille B.; Greden John F. 《Canadian Metallurgical Quarterly》1987,55(3):347
This study explored the burdens experienced by 42 adults who lived with a depressed patient and related these burdens to their degree of psychological distress. The comparison group consisted of 23 adults who were living with someone who had been an in- or outpatient but who was not currently in a depressive episode. Respondents who were living with a patient in a depressive episode were quite distressed themselves, and over 40% met a standardized criterion for referral for therapeutic intervention. For these respondents, living with a patient currently in a depressive episode produced numerous burdens in response to the patients' symptoms, particularly patients' lack of interest in social life, fatigue, feelings of hopelessness, and worrying. Multiple regression analyses showed that these burdens accounted almost entirely for respondents' greater psychological distress. It is suggested that clinical depression is often indicative of a more generally distressed interpersonal context. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
258.
Investigates the visualization of geometric algorithms. We discuss how limiting the domain makes it possible to create a system that enables others to use it easily. Knowledge about the domain can be very helpful in building a system which automates large parts of the user's task. A system can be designed to isolate the user from any concern about how graphics is done. The application need only specify “what” happens and need not be concerned with “how” to make it happen on the screen. We develop a conceptual model and a framework for experimenting with it. We also present a system, GASP (Geometric Animation System, Princeton), which implements this model. GASP allows quick generation of 3D geometric algorithm visualizations, even for highly complex algorithms. It also provides a visual debugging facility for geometric computing. We show the utility of GASP by presenting a variety of examples 相似文献
259.
Steinherz T Rivlin E Intrator N Neskovic P 《IEEE transactions on pattern analysis and machine intelligence》2005,27(5):669-683
In this paper, we present a novel method to extract stroke order independent information from online data. This information, which we term pseudo-online, conveys relevant information on the offline representation of the word. Based on this information, a combination of classification decisions from online and pseudo-online cursive word recognizers is performed to improve the recognition of online cursive words. One of the most valuable aspects of this approach with respect to similar methods that combine online and offline classifiers for word recognition is that the pseudo-online representation is similar to the online signal and, hence, word recognition is based on a single engine. Results demonstrate that the pseudo-online representation is useful as the combination of classifiers perform better than those based solely on pure online information. 相似文献
260.
We extend the classical single-machine maximal lateness scheduling problem to the case where the job processing times are
controllable by allocating a continuous and nonrenewable resource to the processing operations. Our aim is to construct an
efficient trade-off curve between maximal lateness and total resource consumption using a bicriteria approach. We present
a polynomial time algorithm that constructs this trade-off curve assuming a specified general type of convex decreasing resource
consumption function. We illustrate the algorithm with a numerical example. 相似文献