Uncertainty in estimating the performance of solar thermal systems

The scope of this article is to present a methodology for the estimation of the uncertainty characterizing the energy performance of solar domestic hot water systems. The work concentrates on the uncertainty characterizing the expected annual energy output, as calculated through tests implemented according to the valid international standards. In order to cope with difficulties related to the algorithmic character of the measurement model, which cannot be explicitly formulated, Monte-Carlo simulation techniques are implemented. The component of uncertainty associated with measurement errors is estimated, on the basis of the metrological quality anticipated by the relevant testing standards. Errors due to imperfections of the energy model used through the test are also counted in, as well as uncertainties attributed to the variability of meteorological conditions. The proposed uncertainty analysis allows the realistic assessment of the actual energy provided to the user by a solar domestic hot water system. Implementation of the proposed methodology for a typical system leads to an expanded uncertainty in the order of 9% for the expected annual energy output.     

Optical performance and instantaneous efficiency calculation of linear Fresnel solar collectors

The main objective of this study is the investigation of the effect of the optical path of incident beam solar radiation on the performance of a linear Fresnel concentrating solar collector. The requirements regarding the kinematics of the reflectors are examined, allowing the effective focus of the reflected radiation on the receiver cover. A methodology for the calculation of the reflection angles of the sun rays incident on the mirrors, as well as of the incidence angles of the reflected rays on the cover, as a function of the sun position and the geometry of the collector is proposed. Specific scenarios, describing the effect of the solar radiation optical path on the collected heat, are formulated, each of them leading to a different form for the instantaneous efficiency equation. The evaluation and analysis of these scenarios, on the basis of actual operation conditions, has shown that the effect of the reflection and incidence angles throughout the modeling of the collector and the calculation of the useful thermal power cannot be neglected.     

Development of an innovative information system: a fish identification e-key with update capabilities

A dichotomous identification key organizes fishes based on their similarities and differences, and is an essential tool in which ichthyologists, biologists, fishery biologists and others can use for accurate identification of specimens or finding information on correct names, biology and distribution of species. This research work focuses on the development and implementation of a totally new information system that is able to identify correctly fish species names. The developed system is a fully interactive fish identification e-key, which can be used in both forms; locally and remotely via the World Wide Web. This new dichotomous classification e-key provides the capability to identify any species in a compact and easy to use environment, which gives the user excellent operation capabilities and complete information about all included fish species. Moreover, the application provides the capability to search for a random fish species and to show a list which includes all the fish species that currently exist in the application's database. There is an extra attribute that makes the new system novel, and this is its expandability: the information system is fully dynamic having the capability to be extended every time a new species is identified. This attribute is innovative because, until now, there is not any fish identification e-key that gives the user the capability to insert new fish species into the application's database.     

Assessment of the Efficacy and Clinical Utility of Different Circulating Tumor Cell (CTC) Detection Assays in Patients with Chemotherapy-Naïve Advanced or Metastatic Non-Small Cell Lung Cancer (NSCLC)

We herein investigated the detection frequency and clinical relevance of circulating tumor cells (CTCs) in chemotherapy-naïve stage IIIB/IV non-small cell lung cancer (NSCLC), by using the CellSearch and real-time CEACAM5mRNA assays. Blood samples from 43 patients were obtained at different time points during first-line chemotherapy. CellSearch revealed the detection of ≥1 CTCs in 41.9%, 40.9%, and 16.7% of patients at baseline, post-1st, and post-2nd treatment cycle, respectively, and of ≥5 CTCs in 11.6%, 9.1%, and 5.6%, respectively. CEACAM5mRNA+ CTCs were detected in 29.3% and 16% of patients pre- and post-treatment, respectively. The positivity concordance between the two assays was 2.2%. CTC-detection by CellSearch (≥5 CTCs: p = 0.004), CEACAM5mRNA (p = 0.010), or by any assay (p = 0.000) was associated with disease progression. Reduced survival was demonstrated for patients harboring ≥5 CTCs (progression-free survival; PFS: p = 0.000; overall survival; OS: p = 0.009), CEACAM5mRNA+ CTCs (PFS: p = 0.043; OS: p = 0.039), and CTCs by any assay (PFS: p = 0.005; OS: p = 0.006, respectively). CTC-detection by any assay independently predicted for increased risk of relapse (hazard ratio; HR: 3.496; p = 0.001) and death (HR: 2.866; p = 0.008). CellSearch-positivity either pre-, post-1st, or post-2nd cycle, was predictive for shorter PFS (p = 0.036) compared to negativity in all time points. Persistent CEACAM5mRNA-positivity pre- and post-treatment was associated with reduced PFS (p = 0.036) and OS (p = 0.026). In conclusion, CTC detection and monitoring using the CellSearch and CEACAM5mRNA assays provides valuable and complementary clinical information for chemo-naïve advanced or metastatic NSCLC.     

An integrated semantic framework supporting universal accessibility to ICT

As we are moving rapidly to a digital economy, accessing and effectively using Information and Communication Technologies (ICT) in everyday life is widely recognized as an important requirement. However, the accessibility technologies that we have up to date are meeting the needs of only some, at a very high cost and, as a consequence, accessible ICT for all people still remains a major research and development goal. This work presents an integrated ontological framework for the semantic representation of terms and concepts (i.e., related to user needs and preferences (N&P) with respect to ICT use, as well as solutions, platforms and devices) that are required for addressing the universal accessibility in the scope of the Cloud4all project and the Global Public Inclusive Infrastructure (GPII). Cloud4all aims at advancing and building upon the concept of GPII through the development of the necessary tools and models for making ICT accessible for all by exploiting the cloud computing paradigm. The main goal of the proposed framework lays in the separation between generalized accessibility concepts, user interaction mechanisms and N&P with the particular details of different ICT artifacts. Thus, the framework aims at integrating concepts related with user N&P, as well as ICT solutions, platforms, devices and their customizable settings along with information concerning their vendors or implementers, in order to (a) offer the necessary expressiveness for defining/representing personal N&P across applications, platforms and devices, (b) link N&P with the conditions/context according to which these shall be applicable for (e.g., considering the user activity and the physical environment), (c) link interaction requirements (originated from user characteristics) with N&P and (d) support the Cloud4all matchmaking process through the mapping between N&P and application-specific settings based on semantic rules and automatic reasoning techniques.     

Finding the K highest-ranked answers in a distributed network

In this paper, we present an algorithm for finding the k highest-ranked (or Top-k) answers in a distributed network. A Top-K query returns the subset of most relevant answers, in place of all answers, for two reasons: (i) to minimize the cost metric that is associated with the retrieval of all answers; and (ii) to improve the recall and the precision of the answer-set, such that the user is not overwhelmed with irrelevant results. Our study focuses on multi-hop distributed networks in which the data is accessible by traversing a network of nodes. Such a setting captures very well the computation framework of emerging Sensor Networks, Peer-to-Peer Networks and Vehicular Networks. We present the Threshold Join Algorithm (TJA), an efficient algorithm that utilizes a non-uniform threshold on the queried attribute in order to minimize the transfer of data when a query is executed. Additionally, TJA resolves queries in the network rather than in a centralized fashion which further minimizes the consumption of bandwidth and delay. We performed an extensive experimental evaluation of our algorithm using a real testbed of 75 workstations along with a trace-driven experimental methodology. Our results indicate that TJA requires an order of magnitude less communication than the state-of-the-art, scales well with respect to the parameter k and the network topology.     

Scanned images resolution improvement using neural networks

A novel method of improving the spatial resolution of scanned images, by means of neural networks, is presented in this paper. Images of different resolution, originating from scanner, successively train a neural network, which learns to improve resolution from 25 to 50 pixels-per-inch (ppi), then from 100 to 200 ppi and finally, from 50 to 100 ppi. Thus, the network is provided with consistent knowledge regarding the point spread function (PSF) of the scanner, whilst it gains the generalization ability to reconstruct finer resolution images unfamiliar to it. The novelty of the proposed image-resolution-enhancement technique lies in the successive training of the neural structure with images of increasing resolution. Comparisons with the image scanned at 400 ppi demonstrate the superiority of our method to conventional interpolation techniques.     

Wide-field Fizeau imaging telescope: experimental results

A nine-aperture, wide-field Fizeau imaging telescope has been built at the Lockheed-Martin Advanced Technology Center. The telescope consists of nine, 125 mm diameter collector telescopes coherently phased and combined to form a diffraction-limited image with a resolution that is consistent with the 610 mm diameter of the telescope. The phased field of view of the array is 1 murad. The measured rms wavefront error is 0.08 waves rms at 635 nm. The telescope is actively controlled to correct for tilt and phasing errors. The control sensing technique is the method known as phase diversity, which extracts wavefront information from a pair of focused and defocused images. The optical design of the telescope and typical performance results are described.