Design and development of a 10-kWe ORC installation working with low-temperature sources

This paper presents results of the experimental study for a 10-kWe Organic Rankine Cycle (ORC) unit that has been designed and developed in order to study its performance when solar or geothermal sources are used. A boiler was used to simulate those conditions and adjustments were made to generate the final heat by a solar or geothermal source in the same pace, size and way, which accurately reflects the operation of each system. R134a was selected as the working fluid. Measurements for key parameters at various points of the cycle were conducted and performance assessment was attempted. Based on the system operation under the conditions that were applied, and considering the various seasons of the year, it was found that the ORC unit working with low-temperature sources is likely to act as a complementary recovery system of heat quantities as the efficiency is rather small, but able to support other systems.     

Large scale multi-label learning using Gaussian processes

Machine Learning - We introduce a Gaussian process latent factor model for multi-label classification that can capture correlations among class labels by using a small set of latent Gaussian...     

PU learning-based recognition of structural elements in architectural floor plans

Multimedia Tools and Applications - This work introduces a computational method for the recognition of structural elements in architectural floor plans. The proposed method requires minimal user...     

Balloon angioplasty of totally and subtotally occluded coronary arteries: results using the Hydrophillic Terumo Radifocus Guidewire M (glidewire)

Balloon angioplasty was attempted, using hydrophillic Terumo guidewires, in 52 totally and subtotally occluded coronary arteries (50 patients), in which recanalisation by conventional angioplasty guidewires had failed. Hydrophillic guidewires had a crossing success rate of 65.4% (34/52); there was subsequently a technical success rate of 56% (29/52) and clinical success of 39% (20/52). Dissection of the coronary artery was seen in 16/29 technically successful cases. In 12/16 arteries, dissection was small and localised, whereas in 4/16 large and extended distally. There was one myocardial infarction and no peri-procedural deaths. Eleven out of 29 technically successful cases continued to be regarded as successful 12 mo postangioplasty. We conclude that the hydrophillic Terumo guidewire can improve the success rate in angioplasty of totally and subtotally occluded coronary arteries when conventional wires have failed.     

A novel semiautomated atherosclerotic plaque characterization method using grayscale intravascular ultrasound images: comparison with virtual histology

Intravascular ultrasound (IVUS) virtual histology (VH-IVUS) is a new technique, which provides automated plaque characterization in IVUS frames, using the ultrasound backscattered RF-signals. However, its computation can only be performed once per cardiac cycle (ECG-gated technique), which significantly decreases the number of characterized IVUS frames. Also atherosclerotic plaques in images that have been acquired by machines, which are not equipped with the VH software, cannot be characterized. To address these limitations, we have developed a plaque characterization technique that can be applied in grayscale IVUS images. Our semiautomated method is based on a three-step approach. In the first step, the plaque area [region of interest (ROI)] is detected semiautomatically. In the second step, a set of features is extracted for each pixel of the ROI and in the third step, a random forest classifier is used to classify these pixels into four classes: dense calcium, necrotic core, fibrotic tissue, and fibro-fatty tissue. In order to train and validate our method, we used 300 IVUS frames acquired from virtual histology examinations from ten patients. The overall accuracy of the proposed method was 85.65% suggesting that our approach is reliable and may be further investigated in the clinical and research arena.     

Mixture of experts classification using a hierarchical mixture model

A three-level hierarchical mixture model for classification is presented that models the following data generation process: (1) the data are generated by a finite number of sources (clusters), and (2) the generation mechanism of each source assumes the existence of individual internal class-labeled sources (subclusters of the external cluster). The model estimates the posterior probability of class membership similar to a mixture of experts classifier. In order to learn the parameters of the model, we have developed a general training approach based on maximum likelihood that results in two efficient training algorithms. Compared to other classification mixture models, the proposed hierarchical model exhibits several advantages and provides improved classification performance as indicated by the experimental results.     

THESUS: Organizing Web document collections based on link semantics

The requirements for effective search and management of the WWW are stronger than ever. Currently Web documents are classified based on their content not taking into account the fact that these documents are connected to each other by links. We claim that a pages classification is enriched by the detection of its incoming links semantics. This would enable effective browsing and enhance the validity of search results in the WWW context. Another aspect that is underaddressed and strictly related to the tasks of browsing and searching is the similarity of documents at the semantic level. The above observations lead us to the adoption of a hierarchy of concepts (ontology) and a thesaurus to exploit links and provide a better characterization of Web documents. The enhancement of document characterization makes operations such as clustering and labeling very interesting. To this end, we devised a system called THESUS. The system deals with an initial sets of Web documents, extracts keywords from all pages incoming links, and converts them to semantics by mapping them to a domains ontology. Then a clustering algorithm is applied to discover groups of Web documents. The effectiveness of the clustering process is based on the use of a novel similarity measure between documents characterized by sets of terms. Web documents are organized into thematic subsets based on their semantics. The subsets are then labeled, thereby enabling easier management (browsing, searching, querying) of the Web. In this article, we detail the process of this system and give an experimental analysis of its results.Received: 16 December 2002, Accepted: 16 April 2003, Published online: 17 September 2003     

Patient and personnel dosimetry in endovascular radiotherapy with 90Sr/90Y sources

Endovascular brachytherapy (EVBT) is an established treatment to reduce the probability of restenosis after a percutaneous coronary intervention. The purpose of this study was to assess (1) the manufacturer's stated dosimetric data for (90)Sr/(90)Y source trains to be used in EVBT and (2) the procedure-related radiation burden. The radiation fields in water around six (90)Sr/(90)Y source trains were studied using phantoms made of 'solid water' and MD55-2 radiochromic films. The water equivalence of the phantom material was tested by applying quantitative computed tomography. Thermoluminescence dosemeters were used to assess personal radiation burden and crosscheck the dose distribution along the source trains. Technical failure was observed in one source train and this train was excluded from analysis. The measured dose rate in water at 2 mm radial distance was on average 8% higher than the manufacture's stated value (range of measured to stated values 1.05--1.15). The dose rate decreased exponentially with radial distance between 2 and 6 mm. The dose rate in contact with the source viewing window of the delivery devices ranged between 0.5 and 7.5 mGy h(-1). Low-energy photons were the main contributors to personal dose.     

A method for partitioning applications in hybrid reconfigurable architectures

In this paper, we propose a methodology for accelerating application segments by partitioning them between reconfigurable hardware blocks of different granularity. Critical parts are speeded-up on the coarse-grain reconfigurable hardware for meeting the timing requirements of application code mapped on the reconfigurable logic. The reconfigurable processing units are embedded in a generic hybrid system architecture which can model a large number of existing heterogeneous reconfigurable platforms. The fine-grain reconfigurable logic is realized by an FPGA unit, while the coarse-grain reconfigurable hardware by our developed high-performance data-path. The methodology mainly consists of three stages; the analysis, the mapping of the application parts onto fine and coarse-grain reconfigurable hardware, and the partitioning engine. A prototype software framework realizes the partitioning flow. In this work, the methodology is validated using five real-life applications. Analytical partitioning experiments show that the speedup relative to the all-FPGA mapping solution ranges from 1.5 to 4.0, while the specified timing constraints are satisfied for all the applications.     

Performance Evaluation of a New MAC Protocol for the CDMA Interconnection Network

A CDMA mobile system consists of subsystems that transmit and receive call control messages and traffic messages through the CDMA Interconnection Network (CIN). To assure high throughput and short delay in the CIN, an efficient Medium Access Control (MAC) protocol should be provided.In this study, we propose a new MAC protocol for CDMA interconnection networks in order to provide real-time communications in CDMA mobile systems. Also, we evaluate the delay performance of the proposed MAC protocol and compare it with that of existing MAC protocol. Through numerical examples, we show that the proposed protocol provides better delay performance than the existing protocol.