Improved parametric empirical determination of module short circuit current for modelling and optimization of solar photovoltaic systems

Correct modelling of solar photovoltaic (PV) system yields is necessary to optimize system design, improve reliability of projected outputs to ensure favourable project financing and to facilitate proper operations and maintenance. An improved methodology for fine resolution modelling of PV systems is presented using module short-circuit current (I_sc) at 5-min time-scales, and clearly identifies pertinent error mechanisms that arise when working at this high resolution. This work used a modified version of the Sandia array performance model, and introduces new factors to the calculation of I_sc to account for identified error mechanisms, including instrumentation alignment, spectral, and module power tolerance errors. A simple methodology was introduced and verified where specific module parameters can be derived solely from properly filtered performance time series data. In particular, this paper focused on methodologies for determining the predicted I_sc for a variety of solar PV module types. These methods of regressive analysis significantly reduced the error of the predicted model, and demonstrate the need for this form of modelling when evaluating long term PV array performance. This methodology has applications for current systems operators, which will enable the extraction of useful module parameters from existing data in addition to more precise continuous monitoring of existing systems, and can also be used to more accurately model and optimize new systems.     

Analysis of Carbon Particle Deposition on Teflon Filters Using Fourier Transform Infrared Spectroscopy

Fourier transform infrared absorption measurements of particulate elemental carbon are compared with results obtained using a thermal combustion method of analysis. Ambient air samples were collected on Teflon and quartz filters on each day during the sampling study. The quartz filters were analyzed for elemental and organic carbon using a thermal combustion method of analysis. The Teflon filters were analyzed for elemental carbon by infrared transmission in the region 650–666 cm^?1. Good correlation was found between the infrared absorbance on the Teflon filters and the elemental carbon determined from analysis of the quartz filters. Calibration methods for the infrared technique are discussed     

Sustainable Housing – Priorities And Challenges A Case Study Of Australia'S First Green Home

All of us would have sympathy with the aim of achieving environmental sustainability in Australian housing. But where should we start on this noble endeavour?     

Surface Plasmon Measurement of the Bonding Potential between an Organic Fluid and a Gold Film

Abstract

The optical excitation of a surface plasmon-polariton (SPP) at a gold/air interface has been used to monitor the thickness of an organic fluid layer condensed on the gold. By passing a current through the gold film its temperature (as monitored directly by its resistance) is elevated above that of the organic fluid reservoir. Measurement of the SPP resonance position as a function of the difference in temperature between the gold film and the fluid reservoir gives a direct determination of the equilibrium film thickness for a known thermal energy. From the degrees of freedom available to the molecules the variation of the bonding potential with distance from the gold surface is established. For methanol and monochlorobenzene the extra contribution to the free energy μ_Au-organic takes the forms of a power law in distance: μ_Au-methanol ∝thickness^?0·53 and μ_{Au-chlorobenzene} ∝thickness^?1·25.     

Fine co-location of pre-corrected ATSR images

A fast and automatic algorithm is presented in this paper for co-locating nadir and forward views of the Along Track Scanning Radiometer (ATSR) images by using a binary cross-correlation matching technique. The proposed algorithm does not require any auxiliary information, a priori knowledge, or any human operation. Singlechannel thermal infrared (IR) data (11 μm) are used for this algorithm, giving faster processing and avoiding the imperfect coregistration problem observed with multiple channels. Coastlines in images are detected by a region segmentation and an automatic thresholding technique. The matching procedure is carried out with binary coastline images (nadir and forward), and it gives comparable accuracy and faster processing than a patch based matching technique. This technique reduces geometric errors between two views to ±0·7 pixel.     

Analysis of Autocorrelations in Dynamic Processes

Data collected by process information and control systems are almost always correlated due to process dynamics combined with short sampling times. The traditional time series approach for dealing with autocorrelated data has been to model the autocorrelation. This modeling effort is substantially more difficult than simply treating the time series as a sequence of independent data. In this article, we develop and demonstrate a methodology that yields insight into the error introduced by not modeling the autocorrelation of the process data when performing material balances around process equipment. This work shows that in many cases data analysis (e.g., gross-error detection) can be done using the simplified models.     

Kangaroos, Monopoly and Discrete Logarithms

The kangaroo method computes a discrete logarithm in an arbitrary cyclic group, given that the value is known to lie in a certain interval. A parallel version has been given by van Oorschot and Wiener with ``linear speed-up'. We improve the analysis of the running time, both for serial and parallel computers. We explore the variation of the running time with the set of ``jumps' of the kangaroos, and confirm that powers of two are a good choice (we do not claim they are the best choice). We illustrate the theory with some calculations of interest to Monopoly players, and the method itself with a card trick due to Kruskal. Received 23 January 1998 and revised 27 September 1999 Online publication 18 August 2000     

Technology education challenges and solutions in Latin America

The world has become dependent on information, technology, and telecommunications, better known as information technology and telecommunications (IT&T), a term that encompasses the fields of electrical and computer engineering, and computer science. Increasingly, IT&T is an effective indicator of the difference between developed and developing nations. The competitiveness of a nation is directly related to its incorporation of IT&T which requires a substantial restructuring of the forms and procedures in attempting to generate a base for development of science and technology. To achieve this, it is important to revise the education of human technical and scientific resources. This paper summarizes the experience of the Ibero-American Science and Technology Education (ISTEC) consortium in IT education in Latin America     

Structure and Composition of Nanometer-Sized Nitrides in a Creep-Resistant Cast Austenitic Alloy

The microstructure of a new and improved high-temperature creep-resistant cast austenitic alloy, CF8C-Plus, was characterized after creep-rupture testing at 1023 K (750 °C) and 100 MPa. Microstructures were investigated by detailed scanning electron microscopy, transmission electron microscopy, and energy-dispersive X-ray spectroscopy (EDS). Principal component analysis of EDS spectrum images was used to examine the complex precipitate morphology. Thermodynamic modeling was performed to predict equilibrium phases in this alloy as well as the compositions of these phases at relevant temperatures. The improved high-temperature creep strength of CF8C-Plus over its predecessor CF8C is suggested to be due to the modified microstructure and phase stability in the alloy, including the absence of δ-ferrite in the as-cast condition and the development of a stable, slow-growing precipitation hardening nitride phase—the tetragonal Z-phase—which has not been observed before in cast austenitic stainless steels.     

Building cameras for capturing documents

This paper explores those aspects of document capture that are specific to cameras. Each of them must be addressed in order to close the gap between taking a photograph of a document and capturing the document itself. We present results in five areas: (1) framing documents using structured light, (2) robustly dealing with ambient illumination when capturing glossy documents, (3) improving text quality when using mosaiced color sensors, (4) robustly and passively recovering perspective and image plane skew using text flow, and (5) measuring and undoing page curl using structured light and an applicable surface model. The ultimate success of subsequent document recognition will be heavily dependent on the successful completion of these tasks.Received: 8 December 2003, Revised: 6 April 2004, Published online: 11 March 2005