Shell-and-Tube Minichannel Condenser for Low Refrigerant Charge

The design of an innovative shell-and-tube heat pump condenser using 2 mm ID minichannels is presented. This condenser has been designed aiming at the minimization of the charge, which can be required by safety or environmental restrictions. Nevertheless, minichannels represent also a solution to the high-pressure challenge when using carbon dioxide as a refrigerant. The present prototype was realized for the use with propane in the framework of the European project SHERHPA, concerning the development of heat pumps working with natural fluids. Experimental data for heat transfer and pressure drop are reported in the present paper. The measurements have been obtained using refrigerant R22, which displays a temperature versus pressure saturation curve pretty close to the one of propane. The data have also been compared against a computational procedure for shell-and-tube heat exchangers design. The refrigerant charge has been computed by means of different void fraction correlations, showing that the expected charge is less than half the quantity required by a brazed plate condenser giving the same capacity.     

Benin 2025—Balancing Future Water Availability and Demand Using the WEAP ‘Water Evaluation and Planning’ System

In Benin, annual water availability per capita far exceeds the critical threshold of about 1,700 m³, but during the dry season, water scarcity occurs at the local scale. By modeling the water balance of the Ouémé–Bonou catchment with WEAP (Water Evaluation and Planning System), this study aimed at analyzing Benin’s future water situation under different scenarios of socio-economic development and climate change until 2025. The results show that the pressure on Benin’s water resources will increase, leading to greater competition for surface water. Furthermore, financial and technological constraints hinder a satisfactory development, and exploration of groundwater and reservoir resources. However, improvements are most needed, especially in rural areas. Decreasing inflows and groundwater recharge due to climate change aggravate this situation. Even though there are uncertainties and constraints concerning the model and input data, this study shows that the WEAP results offer a solid basis to assist planners in developing recommendations for future water resource management by revealing hot spots of action.     

Comparative analysis of the outdoor performance of a dye solar cell mini‐panel for building integrated photovoltaics applications

New generation photovoltaic (PV) devices such as polymer and dye sensitized solar cells (DSC) have now reached a more mature stage of development, and among their various applications, building integrated PVs seems to have the most promising future, especially for DSC devices. This new generation technology has attracted an increasing interest because of its low cost due to the use of cheap printable materials and simple manufacturing techniques, easy production, and relatively high efficiency. As for the more consolidated PV technologies, DSCs need to be tested in real operating conditions and their performance compared with other PV technologies to put into evidence the real potential. This work presents the results of a 3 months outdoor monitoring activity performed on a DSC mini‐panel made by the Dyepower Consortium, positioned on a south oriented vertical plane together with a double junction amorphous silicon (a‐Si) device and a multi‐crystalline silicon (m‐Si) device at the ESTER station of the University of Rome Tor Vergata. Good performance of the DSC mini‐panel has been observed for this particular configuration, where the DSC energy production compares favorably with that of a‐Si and m‐Si especially at high solar angles of incidence confirming the suitability of this technology for the integration into building facades. This assumption is confirmed by the energy produced per nominal watt‐peak for the duration of the measurement campaign by the DSC that is 12% higher than that by a‐Si and only 3% lower than that by m‐Si for these operating conditions. Copyright © 2013 John Wiley & Sons, Ltd.     

Rawseeds ground truth collection systems for indoor self-localization and mapping

A trustable and accurate ground truth is a key requirement for benchmarking self-localization and mapping algorithms; on the other hand, collection of ground truth is a complex and daunting task, and its validation is a challenging issue. In this paper we propose two techniques for indoor ground truth collection, developed in the framework of the European project Rawseeds, which are mutually independent and also independent on the sensors onboard the robot. These techniques are based, respectively, on a network of fixed cameras, and on a network of fixed laser scanners. We show how these systems are implemented and deployed, and, most importantly, we evaluate their performance; moreover, we investigate the possible fusion of their outputs.     

Reliable indirect competitive ELISA used for a survey of ochratoxin A in green coffee from the North of Paraná State, Brazil.

The performance of an indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) based on a monoclonal antibody (mAb) for ochratoxin A (OTA) detection was evaluated in a comparative study with high-performance liquid chromatography (HPLC) analysis using 68 freshly harvested coffee samples from the North of Paraná State, Brazil. The anti-OTA mAb showed high specificity and low cross-reactivity with OTA analogues (OTB and OTalpha), but cross-reacted with OTC. This ic-ELISA showed a detection limit of 3.75 ngg-1 sample, when compared to 0.80 ngg-1 by HPLC, with an ic-ELISA/HPLC correlation coefficient of 0.90. As regards OTA analysis of these coffee samples, natural contamination was detected in 10 samples (14.7%) by both methods, where the ic-ELISA values (range 3.9-7.3 ngg-1) were 1.1 to 1.6-fold higher than HPLC data (2.7-4.7 ngg-1). Five samples (7.4%) were OTA positive (range 0.84-1.30 ngg-1) only by HPLC assay, probably due to the higher detection limit reached by ic-ELISA. OTA was undetectable in 53 samples (77.9%) by both methods, while all positive samples (range 0.84-7.30 ngg-1) showed OTA levels lower than 8 ngg-1 (maximum limit recommended by the European Union). The matrix interference of green coffee was minimized by dilution of sample extracts before carrying out the ELISA assay. This mAb-based ic-ELISA can be effectively applied for OTA screening in coffee, because it is simple, sensitive and sample preparation is easy.     

Timed CCP compositionally embeds Argos and Lustre

We prove that both the synchronous data-flow language Lustre restricted to types with finite values and the synchronous state-oriented language Argos are embedded in the synchronous paradigm Timed Concurrent Constraint Programming (tccp). In fact, for each of the two languages we provide a tccp language encoding it compositionally with respect to the syntax of programs and linearly with respect to the size of programs. Besides giving results of expressiveness for tccp, our encodings permit us to obtain a language tailored for programming reactive systems where both control handling aspects and data processing aspects are relevant.Author partially supported by MIUR progetto cofinanziato Modelli Formali per la Sicurezza e il Tempo and by ESPRIT Working Group Constraint Programming for Time Critical Applications, Project Number 23677Accepted in revised form 22 October 2003 by M. Broy, G. Lüttgen and M. Mendler     

Skin nanostructural features determine suture biomechanics

The stress state surrounding wounds in the skin plays an important role in the healing process; it affects the tissue strength, its aesthetic, and its resistance to infections. In this paper, the collagen fibril and elastin matrix damage mechanics following suture point application is investigated at the nanoscale; to this purpose, a model has been developed, which accounts for the architectural and mechanical features of the tissue components. Results indicate that the force displacement caused by the suture point application curve initially stiffens and subsequently softens. Softening occurs due at first to the enlargement of the elastin matrix damaged area and second to the collagen fibril disruption. Three regions may be identified: the first one, (0-0.38 N) refers to skin withstanding the force both in the collagen and elastin components; the second one (0.38-0.75 N) concerns the mechanism of elastin matrix damage; in the last one (>0.75 N), the collagen fibrils also fail. Accordingly, by properly choosing the number of suture points, it is possible to define the optimal suture points number for a given wound closure force.     

Learning independent components on the orthogonal group of matrices by retractions

Neural independent component learning algorithms based on optimization on manifolds have attracted interest in the neural network community. In the past years, we have developed learning algorithms specialized for the orthogonal group of matrices as parameters manifold. Here, we sketch a view of these algorithms by the help of ‘retractions’ on manifolds.     

First data from the EGLE experiment onboard the ISS

EGLE is a wide frequency band search- coil magnetometer designed and built at the Roma Tre University. It has been installed onboard the ISS by the Italian astronaut Roberto Vittori on April 25, 2005 within the LAZIO- EGLE experiment carried out during the ENEIDE Soyuz mission. The scope of the experiment is to test EGLE in space and to investigate geomagnetic field variations. The main applications of EGLE are the study of electromagnetic environment inside the ISS, the correlation of magnetic field data with particle fluxes detected by LAZIO particle detector, and the monitoring of ionospheric perturbations possibly caused by Earth seismic activity. Since continuous electromagnetic field measurements on board the ISS are important for diverse space applications, a magnetometer with a suitable design is requested. Appropriate solutions for these applications, which have been adopted by EGLE, are in particular the use of 1- Wire technology and the possibility to detect by means of a search- coil magnetometer a large portion of the ULF frequency band, usually measured by flux- gate probes. To investigate the topside ionosphere electromagnetic environment and stability of Van Allen radiation belts in relation with seismic and anthropogenic electromagnetic emissions, a specific satellite mission (the ESPERIA project) has been designed for the Italian Space Agency (ASI), and up to now a few instruments of its payload have been built and tested in space. One of them is exactly the EGLE search- coil magnetometer. The first magnetic observations performed by this instrument reveal to be promising and demand for a further and deeper analysis based on a longer time series of data.