PV-Pilot Plants in Europe - Status of Operation

In 1980, the CEC launched a call for tenders for photovoltaic pilot projects. Since mid 1984, all the relating plants are in operation. In late summer 198S, the WIP has been charged to inspect the PV plants, so as to gather information on the operational status of the systems.

This inspection showed that most of the plants are working satisfactorily. Nevertheless, optimization measures are possible for many installations in the field of power management and conditioning systems, data acquisition and recording, battery management and charge controlling, loads and load matching, software, maintenance and documentation.

So far, the PV modules themselves, the support structures and batteries have shown to be trouble-free components of PV systems.

In order to preserve the potential of the PV plants and make good use of it, the Commission sponsors, in the frame of the current photovoltaic R & D Programme, follow-up activities on the existing installations.     

Direct Comparison between Five Different Microchannels,Part 2: Experimental Description and Flow Friction Measurement

Abstract

Part one of this paper ^[1] Eason, C., Dalton, T., O'Mathúna, C., Slattery, O. and Davies, M. 2005. Direct Comparison between Five Different Microchannels, Part 1: Channel Manufacture and Measurement. Heat Transfer Engineering Journal, vol. 26(no. 3): pp. 00–00.  [Google Scholar] investigates the manufacture of five types of microchannels produced by wet and dry etching in silicon and precision mechanical sawing in silicon and thermoset plastic. This paper describes the experimental equipment and methods used to measure the pressure flow characteristics of the manufactured channels. A test system has been built to test each sample using the same inlet and outlet manifolds, pressure tappings, pumping system, and instrumentation. The measured pressure flow behavior was compared with theoretical values calculated from macroscale theory. Error analysis was carried out in order to determine the overall accuracy of the experimental work and determine the significance of any experimental deviation from theoretical values. An area compensation term is introduced to account for the difference in cross-section between the measured actual channels and the rectangles/trapeziums that share their overall dimensions.     

Crosstalk between finite ground coplanar waveguides over polyimide layers for 3-D MMICs on Si substrates

Finite-ground coplanar (FGC) waveguide lines on top of polyimide layers are frequently used to construct three-dimensional Si-SiGe monolithic microwave/millimeter-wave integrated circuits on silicon substrates. Requirements for high-density, low-cost, and compact RF front ends on silicon can lead, however, to high crosstalk between FGC lines and overall circuit performance degradation. This paper presents theoretical and experimental results and associated design guidelines for FGC line coupling on both highand low-resistivity silicon wafers with a polyimide overlay. It is shown that a gap as small as 6 /spl mu/m between two adjacent FGC lines can reduce crosstalk by at least 10 dB, that the nature of the coupling mechanism is not the same as with microstrip lines on polyimide layers, and that the coupling is not dependent on the Si resistivity. With careful layout design, isolation values of better than -30 dB can be achieved up to very high frequencies (50 GHz).     

Ultrasensitive Strain Gauges Enabled by Graphene‐Stabilized Silicone Emulsions

Here, an approach is presented to incorporate graphene nanosheets into a silicone rubber matrix via solid stabilization of oil‐in‐water emulsions. These emulsions can be cured into discrete, graphene‐coated silicone balls or continuous, elastomeric films by controlling the degree of coalescence. The electromechanical properties of the resulting composites as a function of interdiffusion time and graphene loading level are characterized. With conductivities approaching 1 S m^?1, elongation to break up to 160%, and a gauge factor of ≈20 in the low‐strain linear regime, small strains such as pulse can be accurately measured. At higher strains, the electromechanical response exhibits a robust exponential dependence, allowing accurate readout for higher strain movements such as chest motion and joint bending. The exponential gauge factor is found to be ≈20, independent of loading level and valid up to 80% strain; this consistent performance is due to the emulsion‐templated microstructure of the composites. The robust behavior may facilitate high‐strain sensing in the nonlinear regime using nanocomposites, where relative resistance change values in excess of 10⁷ enable highly accurate bodily motion monitoring.     

Feasibility analysis of stand-alone renewable energy supply options for a large hotel

This paper provides a feasibility analysis of renewable energy supply (RES) for a stand-alone supply large-scale tourist operation (with over 100 beds). The analysis utilises the power load data from a hotel located in a subtropical coastal area of Queensland, Australia. The assessment criteria of the analysis are net present cost, renewable factor and payback time. Due to the limited number of RES case studies in tourist operations and the absence of studies for large resorts, requiring facilities with a higher degree of comfort such as air-conditioning, it is not possible to establish with confidence the viability of RES in this industry. The specific operational characteristics of the tourism accommodation sector, such as 24-h operation, comfort provision and low tolerance for failure necessitates a separate assessment of RES viability for this sector, rather than relying on similar assessments from other commercial sectors. This study uses RES assessment software tools, HOMER (National Renewable Energy Laboratory, US) and HYBRIDS (Solaris Homes, Queensland, Australia), in order to compare diesel generator-only, RES-only and RES/diesel hybrid technologies. HOMER uses hourly load data, whilst HYBRIDS uses average daily energy demand for each month. The modelling results demonstrate that RES, in principle, has the potential to adequately and reliably meet power demand for a stand-alone large-scale tourist accommodation. Optimisation modelling demonstrates that 100% of power demand can be supplied by a RES-only configuration. A hybrid diesel/RES configuration provides the lowest NPC result with a resultant RF of 76%. In comparison to the diesel generator-only configuration, NPC is reduced by 50% and Greenhouse Gas (GHG) emissions by 65%. The payback time of the hybrid RES scenario is 4.3 years. Results indicate that wind energy conversion systems (WECS), rather than photovoltaics, are the most economically viable RES for large-scale operations. Large-scale WECS (over 1000 kW) are more efficient and economical than multiple small-scale WECS (0.1–100 kW). Both modelling tools produced similar results, with HYBRIDS producing on average slightly higher NPC results than HOMER. The modelling and resulting data from the analysis indicate that RES is technically feasible and economically viable as a replacement for conventional thermal energy supply for large-scale tourist operations dependent on stand-alone power supplies.     

nAIT: A source analysis and instrumentation framework for nesC

Automated software engineering methods support the construction, maintenance, and analysis of both new and legacy systems. Their application is commonplace in desktop- and enterprise-class systems due to the productivity and reliability benefits they afford. The contribution of this article is to present an applied foundation for extending the use of such methods to the flourishing domain of wireless sensor networks. The objective is to enable developers to construct tools that aid in understanding both the static and dynamic properties of reactive, event-based systems. We present a static analysis and instrumentation toolkit for the nesC language, the defacto standard for sensor network development. We highlight the novel aspects of the toolkit, analyze its performance, and provide representative case-studies that illustrate its use.     

Three-dimensional integrated optics using polymers

Some of the key components are demonstrated to make three-dimensional (3-D) optical integrated circuits possible using polymers. Fabrication techniques of shadow reactive ion etching, shadow photolithography, and gray-level photolithography to produce complex 3-D integrated optic structures are demonstrated. Vertical waveguide bends exhibit excess losses of <0.3 dB, and vertical power splitters possess predictable output splitting ratios between multiple core levels with excess losses of <0.5 dB. Vertical polarization splitters exhibit power extinction ratios of 15 dB between the output core layers. A 1×4 vertical-horizontal power splitter is also demonstrated. Additionally, these techniques are used to integrate different polymer materials into the same optical circuit while easily solving the mode mismatch problem. To show the technique, a polymer electrooptic modulator is vertically integrated with a low-loss waveguide     

Hydrophilic sponges based on 2-hydroxyethyl methacrylate Part VII: Modulation of sponge characteristics by changes in reactivity and hydrophilicity of crosslinking agents

Despite previous unsuccessful attempts to use hydrated poly(2-hydroxyethyl methacrylate) sponges as implantable biomaterials, recently these materials became important as peripheral components in an artificial cornea of the core-and-skirt design. The low mechanical strength of sponges prompted this study on possible improvement of tensile properties by the use of a variety of crosslinking agents. Three vinylic (dimethacrylates) and two allylic compounds were used at different concentrations (0.1 to 2% (mol)) as crosslinking agents in the production of sponges. Their influence on the mechanical properties, porous morphology and swelling behavior of resulting sponges was evaluated. The onset of phase separation during polymerization was also measured by visible spectrophotometry. The results suggested an inherent heterogeneity of sponges, i.e. pores of non-uniform size and structural inhomogeneities. While the effects of changes in the nature and concentration of crosslinking agents on the equilibrium water content of sponges were ambiguous, some of the mechanical properties, such as toughness and elasticity, were improved by crosslinking with allylic agents. Scanning electron microscopic examination suggested that the mechanical effect is related to the variation of size of the polymer particles constituting the sponge structure, which was proved to be dependent upon the onset of phase separation during polymerization. ©2000 Kluwer Academic Publishers     

Fabrication and characterization of high-speedpolyurethane-disperse red 19 integrated electrooptic modulators foranalog system applications

The fabrication and characterization of polymeric electrooptic modulators, made of a thermally crosslinkable polyurethane with Disperse Red 19 side chains, are summarized in this paper. Straight channel and Mach-Zehnder modulators have been fabricated, packaged and tested for the fiber-optic analog transmission system applications. Device performances including halfwave voltage, insertion loss, on-off ratio, and modulation frequency responses were measured. Long-term halfwave voltage stability, dc-bias voltage stability, and optical power handling capability at 1.3-μm wavelength were investigated. A carrier-to-noise ratio of 53 dB and 80-channel television transmission have been demonstrated using the packaged polymer modulators