Methodology to demonstrate pile capacity In relaxing ground

Driven pre-stressed concrete piles have been used as a foundation system to support abutments and piers of a bridge constructed near Ballina in New South Wales, Australia. In order to achieve the required geotechnical capacity, the piles were required to be driven through soft clay and sand to moderately weathered rock. Pile Driving Analyser (PDA) testing together with CAPWAP analysis was performed to assess the integrity and geotechnical capacity of the driven piles. Pile damage was observed during driving. To prevent damage a rock shoe was retrofitted to the piles prior to installation. Reductions in pile capacity (or relaxation) were observed between end of drive (EOD) and later restrike testing (RST). A substantial amount of additional pile testing was performed at different times after driving to assess the changes in pile capacity over time. Most piles were re-driven to achieve higher capacity. Pile capacity could not be achieved in one pier and additional piles were installed to reduce the required pile test loa

GEOGRAPHIC INFORMATION SYSTEM FOR URBAN PLANNING: A CASE STUDY IN THIMBIRIGASYAYA WARD, COLOMBO

This study aims to improve land clearance processes in the Urban Development Authority (UDA) with the support of Geographic Information Systems (GIS). The objective is realized through the conduct of geographical analysis, query, and modeling. The study takes the Thimbirigasyaya Ward in the City of Colombo as a case for developing the land clearance system was taken into consideration under the study. The study was done to understand the context of land clearance processes in the UDA and to develop a digital system for land clearances. The study takes a critical look at how the UDA practices land clearances and monitoring, and applies information technology tools to support such functions. It reviews UDA regulations and identifies issues in land clearances and database management. The method that has been exercised in developing a Land Information System (LIS) is basically in three forms. They are (1) Identifications of shortcomings in the present system, (2) Identifications of target, (3) Finding ways in reaching the targets. Collection of data was first subjected to detailed study in order to find its accuracy and a database has been developed using data layers and attributes by converting analog maps and statistical data into digital form. Then land information was tested and verified for its accuracy. Selection of the study area was done through a suitability analysis and availability of updated data. A model was then developed using GIS tool. Its data accuracy was checked and found that the results had been in proper order. The developed LIS was compared with the existing processing system and was proved effective. The accuracy of the data is very important in the process of developing a good LIS. In this study checks were carried out to ensure data accuracy. Numerical checks including stepwise calculations and field measurements were done to verify the model. The system developed using GIS has a significant advantage over the existing system. Clear improvements were visible in the area of labor and time saving and also in the provision of alternative solutions. System output identified the present distribution and use of land parcels. This gives rise to the need of establishing norms for rational decision making. The UDA is basically benefited by this system on following: (1) Serve as platform to integrate data and facilitate data exchange, (2) Provides immediate access to data, (3) Spatial analysis for selection of alternative sites, and (4) Easy decision-making. Keywords: Geographic Information Systems, Land Information System For full Paper: [email protected]

Enhanced performance of flexible dye-sensitized solar cells: Electrodeposition of Mg (OH) 2 on a nanocrystalline TiO2 electrode

Nanocrystalline TiO2 photoanodes were prepared on a conductive indium–tin oxide coated polyethylene naphthalate (ITO-PEN) plastic substrate by the doctor-blade method to fabricate flexible dye-sensitized solar cells (DSCs). The surface of the photoanode was coated with Mg(OH)2 by electrodeposition and the deposition time was systematically varied (2, 4, 6, 8, and 10 min). Electrodeposited Mg(OH)2 was confirmed by IR and energy dispersive X-ray (EDX) analysis. The surface morphology was studied by scanning electron microscopy. The internal surface area of TiO2 was studied against the deposition time by taking into account the projected surface area of the photoelectrode and it shows that the internal surface area of the photoelectrode was reduced as the Mg(OH)2 deposition time increased. The performance of flexible DSCs on various deposition times of Mg(OH)2 was evaluated on the basis of their photocurrent density–voltage characteristics. Among the deposition times, 2 min showed the best performance in Voc on a treated flexible DSC, with resulting 847 mV and a photocurrent density of 7.13 mA/cm2, providing an overall light-to-electricity conversion efficiency of 4.01%. This photovoltage is among the highest attained for a flexible DSC to date. This notable increment in Voc at a thin layer of Mg(OH)2 was attributed to the suppression of recombination of photogenerated electrons via the exposed surface of ITO as well as TiO2 without influencing the internal surface area of the photoanode significantly

Preparation of nanocrystalline TiO2 electrodes for flexible dye-sensitized solar cells: influence of mechanical compression

Nanocrystalline TiO2 electrodes were prepared using binder-free TiO2 paste on conductive ITO-PEN substrates by the doctor-blade method at significantly low temperature (140 °C), and the electrodes were further processed under different compressions (10–60 MPa) in order to improve interparticle connections and adhesion between the nanoparticles and the ITO-PEN substrate. TiO2 electrodes compressed at 30 and 40 MPa had relatively less cracks with low crack width. Electrode compressed at 30 MPa showed the highest internal surface area. Electrode prepared at this compression showed the best dye-sensitized solar cell (DSC) performance with Voc of 805 mV, Jsc of 9.24 mA cm–2, and an overall efficiency of 4.39%. Electrochemical impedance spectroscopy (EIS) studies of the sandwiched cells employing bare nanocrystalline TiO2 electrode and Pt counter electrode in I–/I3– electrolyte showed that electrode compression significantly influences the stability of the cells. EIS data suggested that degradation/corrosion processes may take place on ITO-PEN for sandwiched cells made by TiO2 electrodes compressed at all pressures. Thirty and 40 MPa compressions showed a minor degradation of ITO. The recombination dynamics at the TiO2/electrolyte interface were influenced by the changes in the nanostructured electrode internal surface area, changes in electron transport properties (due to improved sintering), and possible degradation/corrosion of ITO-PEN. Open-circuit voltage decay (OCVD) measurements showed that the DSC made by the 30 MPa compressed TiO2 electrode had the highest decay time, indicating low recombination properties, which is in a good agreement with other data

Preparation of nanocrystalline TiO2 electrodes for flexible dye-sensitized solar cells: influence of mechanical compression

Nanocrystalline TiO2 electrodes were prepared using binder-free TiO2 paste on conductive ITO-PEN substrates by the doctor-blade method at significantly low temperature (140 °C), and the electrodes were further processed under different compressions (10–60 MPa) in order to improve interparticle connections and adhesion between the nanoparticles and the ITO-PEN substrate. TiO2 electrodes compressed at 30 and 40 MPa had relatively less cracks with low crack width. Electrode compressed at 30 MPa showed the highest internal surface area. Electrode prepared at this compression showed the best dye-sensitized solar cell (DSC) performance with Voc of 805 mV, Jsc of 9.24 mA cm–2, and an overall efficiency of 4.39%. Electrochemical impedance spectroscopy (EIS) studies of the sandwiched cells employing bare nanocrystalline TiO2 electrode and Pt counter electrode in I–/I3– electrolyte showed that electrode compression significantly influences the stability of the cells. EIS data suggested that degradation/corrosion processes may take place on ITO-PEN for sandwiched cells made by TiO2 electrodes compressed at all pressures. Thirty and 40 MPa compressions showed a minor degradation of ITO. The recombination dynamics at the TiO2/electrolyte interface were influenced by the changes in the nanostructured electrode internal surface area, changes in electron transport properties (due to improved sintering), and possible degradation/corrosion of ITO-PEN. Open-circuit voltage decay (OCVD) measurements showed that the DSC made by the 30 MPa compressed TiO2 electrode had the highest decay time, indicating low recombination properties, which is in a good agreement with other data

Aerosol-assisted CVD of bismuth vanadate thin films and their photoelectrochemical properties

Thin film bismuth vanadate (BiVO4) photoelectrodes are prepared by aerosol-assisted (AA)CVD for the first time on fluorine-doped tin oxide (FTO) glass substrates. The BiVO4 photoelectrodes are characterised by X-ray diffraction (XRD), Raman spectroscopy (RS), and energy-dispersive X-ray (EDX) spectroscopy and are found to consist of phase-pure monoclinic BiVO4. Scanning electron microscopy (SEM) analysis shows that the thin film is uniform with a porous structure, and consists of particles approximatively 75-125 nm in diameter. The photoelectrochemical (PEC) properties of the BiVO4 photoelectrodes are studied in aqueous 1 M Na2SO4 and show photocurrent densities of 0.4 mA cm-2, and a maximum incident-photon-to-electron conversion efficiency (IPCE) of 19% at 1.23 V vs. the reversible hydrogen electrode (RHE). BiVO4 photoelectrodes prepared by this method are thus highly promising for use in PEC water-splitting cells