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171.
A support vector machine approach for detection of microcalcifications   总被引:18,自引:0,他引:18  
In this paper, we investigate an approach based on support vector machines (SVMs) for detection of microcalcification (MC) clusters in digital mammograms, and propose a successive enhancement learning scheme for improved performance. SVM is a machine-learning method, based on the principle of structural risk minimization, which performs well when applied to data outside the training set. We formulate MC detection as a supervised-learning problem and apply SVM to develop the detection algorithm. We use the SVM to detect at each location in the image whether an MC is present or not. We tested the proposed method using a database of 76 clinical mammograms containing 1120 MCs. We use free-response receiver operating characteristic curves to evaluate detection performance, and compare the proposed algorithm with several existing methods. In our experiments, the proposed SVM framework outperformed all the other methods tested. In particular, a sensitivity as high as 94% was achieved by the SVM method at an error rate of one false-positive cluster per image. The ability of SVM to out perform several well-known methods developed for the widely studied problem of MC detection suggests that SVM is a promising technique for object detection in a medical imaging application.  相似文献   
172.
In the present work cyclic oligomers of poly(oxybutylene oxymaleoyl) were prepared successfully and cleanly from the polycondensation of the tetrahydrofuran with maleïc anhydride using the Maghnite-H+ (Mag-H) as catalyst. Maghnite is a montmorillonite sheet silicate clay exchanged with protons to produce Maghnite-H+ (M. Belbachir, U.S. Patent 066969.0101–2001). The effects of reaction temperature, amount of Maghnite-H+ and reaction time on the yield and the molecular weight are investigated. The results indicate that the polymerization yield increases with increasing the proportion of catalyst.  相似文献   
173.
To evaluate the role of practice and to establish statistically meaningful methods for assessing cognitive outcome after epilepsy surgery, test–retest scores for 47 left (LTL) and 49 right (RTL) temporal lobectomy patients on the Wechsler Adult Intelligence Scale—Revised (WAIS—R) and Wechsler Memory Scale—Revised (WMS—R) were compared with the scores of 40 epilepsy patients who had not received lobectomies (SZCs). Reliable change indexes were calculated to control for measurement error, and base-rate tables for individual change were constructed for each variable before and after adjustment for observed practice effects. More frequent positive Full Scale IQ changes were noted among LTL than among RTL patients following surgery, whereas negative changes on the WMS-R General Memory and Verbal Memory Indexes were more common among the LTL patients than among either the RTL or SZC groups. When practice effects were controlled, the RTL patients also exceeded base-rate expectations for negative outcomes on the Verbal Memory Index. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
174.
In the computer vision field, many real-world applications are based on detecting and tracking moving objects. One of the most important challenges in these applications is tracking occluded objects. Actually, when two or multiple objects occlude, the used tracking system suffers from information loss which negatively influences its tracking performance. The present paper introduces a new method to overcome this problem using only one target image and without any classification or learning phase. Indeed, a tracking system is established by combining the chromatic co-occurrence matrices and the particle filter in order to evaluate the occluded target position. The qualitative and quantitative studies show that the results obtained by the proposed approach are very competitive in comparison with several state-of-the-art methods.  相似文献   
175.
The objective of this study was to evaluate the addition of powdered activated carbon (PAC) to upflow floc-blanket reactors for the adsorption of natural and synthetic organic chemicals. A 15.5-1. bench-scale floc-blanket reactor was operated with PAC addition for the adsorption of 2,4,6-trichlorophenol (TCP) and natural organic matter from one groundwater and two surface waters under laboratory and field conditions, respectively. Influent TCP concentrations ranged from 21 to 415 μg/l. The PAC doses ranged from 2 to 12 mg/l. While the hydraulic residence time in the floc-blanket reactor varied from 15 to 30 min, the carbon residence time ranged from 9 to 34 h. This is due to the high solids concentration in the floc blanket, which ranged from 1200 to 8700 mg/l. Comparison between the extent of TCP adsorption through the floc-blanket reactor and the equilibrium adsorption isotherms of TCP on PAC showed that the maximum adsorption capacity of PAC for TCP was utilized in the reactor. However, this study showed that the maximum adsorptive capacity of the carbon in a continuous process is dependent on the influent adsorbate concentration. This was in agreement with isotherm studies conducted with varying initial TCP concentration. The maximum PAC adsorption capacity for natural organic matter was also achieved in the floc-blanket reactor.  相似文献   
176.
In this study, an experimental prototype was built to examine the use of an underground water tank as a heat exchange medium with the soil to reduce photovoltaic (PV) panel operation temperatures and simultaneously improve PV efficiency. Three PV systems were evaluated: a benchmark PV panel without cooling (panel A); a PV panel with water spray cooling (panel B); and a PV panel with evaporative cooling (panel C). The cooling techniques in modules (B) and (C) were used to investigate the effects of underground water on the performance of PV panels in arid conditions. Four cases were devised as follows: spray panel back cooling (I), spray front and back cooling (II), spray front and back cooling using an Arduino controller (III), and repeating case III with different water flow rates (IV). Readings were taken from 9:00 am to 4:00 pm  from May to August. The experimental results showed that the use of underground water spray cooling led to reductions in the temperature of PV panel B, 14°C, 17.6°C, 18.8°C, and 22.7°C for cases I, II, III, and IV, respectively, when compared with the uncooled panel, and efficiency improved by 3.5%, 4.8%, 18%, and 23.1%, respectively.  相似文献   
177.
The purpose of this study was to assess the in vitro performances of “vegetable” capsules in comparison to hard gelatin capsules in terms of shell weight variation, reaction to different humidity conditions, resistance to stress in the absence of moisture, powder leakage, disintegration and dissolution. Two types of capsules made of HPMC produced with (Capsule 2) or without (Capsule 3) a gelling agent and hard gelatin capsules (Capsule 1) were assessed. Shell weight variability was relatively low for all tested capsules shells. Although Capsule 1 had the highest moisture content under different humidity conditions, all capsule types were unable to protect the encapsulated hygroscopic polyvinylpyrrolidone (PVP) powder from surrounding humidity. The initial disintegration for all Capsule 1 occurred within 3?min, but for other types of capsules within 6?min (n?=?18). Dissolution of acetaminophen was better when the deionized water (DIW) temperature increased from 32 to 42?°C in case of Capsule 1, but the effect of temperature was not significant for the other types of capsules. Acetaminphen dissolution from Capsule 1 was the fastest (i.e. >90% in 10?min) and independent of the media pH or contents unlike Capsule 2 which was influenced by the pH and dissolution medium contents. It is feasible to use hypromellose capsules shells with or without gelling agent for new lines of pharmaceutical products, however, there is a window for capsule shells manufacturing companies to improve the dissolution of their hypromellose capsules to match the conventional gelatin capsule shells and eventually replace them.  相似文献   
178.
Balancing value creation and value capture is a fundamental strategic issue for the management of open innovation. Insufficient compensation for created value may hinder the participation of a firm or individual in open innovation. It can thus provide an obstacle to the open innovation process as a whole. Hackathons provide an attractive setting for studying value appropriation in open innovation by actors of different types and with varying bargaining power. We define hackathons as idea competitions on specific topics in the form of a time-limited event. These competitions have gained more popularity throughout the years and have recently become more prominent. Therefore, an abductive empirical study was carried out in an international set-up with multiple embedded cases of hackathons. Results indicate that hackathons offer coupled open innovation processes. The value captured by the initiator of a hackathon in the form of inbound open innovation is balanced by outbound knowledge flows towards participants as well as with sideways knowledge flows between participants, which are a result of the generation of collective intelligence. Collective intelligence is thus identified as an alternative mechanism for value capture from open innovation.  相似文献   
179.
The problem of an outdated tariff has become acute recently with increased water scarcity in Palestine. Therefore, the goals of the study were to analyse the factors that could affect the water consumption in Jericho governorate, Palestine; explore societal perceptions of alternative water sources; and to identify areas that need to be re-examined for tariff revision or changes to water source and delivery. A total of 76% of the respondents know the water tariff price, and 61% of the sample considers the tariff as high. Future suggestions to raise the price of water will meet resistance. Interestingly, 66% of the respondents agree with the possible future use of treated wastewater, and 46% of the respondents emphasize that treated wastewater is the most favoured solution for water scarcity. Overall, the results indicate the public identifies water conservation as possible and that alternative actions can be applied in order to manage and conserve water resources.  相似文献   
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