Studies in photochemistry

Imperial Users onl

The economics of photovoltaics in the commercial, institutional and industrical sectors

This paper describes the application of a model which computes system break-even capital costs, array break-even capital costs and profits from photovoltaic investments in the industrial, commercial and institutional sectors. Several tax and accounting combinations are described and utilized in this paper. Results indicate that, at rates of return usually found in the industrial and commercial sectors, photovoltaic investments will not be attractive when the costs of those investments are based on the Department of Energy's cost goals for 1986

The impact on photovoltaic worth of utulity rate and reform and of specific market, financial, and policy variables : a commercialindustrialinstitution sector analysis

This work provides an assessment of the economic outlook for photovoltaic systems in the commercial, industrial and institutional sectors in the year 1986. We first summarize the expected cost and performance goals for photovoltaic technology, and then estimate aspects of the market and financial environment pertinent to assessment of a PV investment beginning in that year. Our analysis covers three geographic regions of the U.S., characterized by Boston, Madison, and Phoenix, and examines PV economic performance when operating against five different means for establishing utility backup rates. In addition, we assess the potential of a photovoltaic array to reduce a firm's monthly capacity charge.Our results break down as follows. For our initial analysis, utilizing a base case set of financial parameters, we find that a peak-shaving credit (reduction in monthly capacity charge) attributed to a photovoltaic array can be significant, but not so much as to prove photovoltaics economic in the commercial sector in 1986. The institutional sector will find photovoltaics profitable if they discount at rates reflective of the returns on long-term government bonds. In our extended analysis, we perform sensitivity studies and examine the impact of combinations of government incentives. We find that photovoltaics will just turn economic in 1986 for the commercial/industrial sector given an optimistic set of incentive policies. We finalize our analysis with an important list of caveats to our conclusions

Simulation analysis of energy production in the B. C. pulp and paper industry

ABSTRACT This paper describes a dynamic simulation model of energy production and use by pulp and paper mills. The model can be used to assess the costs and benefits of the use of different proportions of wood waste (referred to as 'hog fuel') and fossil fuels to generate process steam and electricity, with the costs and benefits measured from several points of view, principally those of the mill management and of the economy as a whole. Using either point of view, the model has been fitted to the eighteen major pulp and paper mills in British Columbia, and used to assess the consequences of the size and nature of optimal hog fuel projects. Some results are reported in this paper and references are given to other papers containing more complete results of various aspects of the research project. INTRODUCTION Whenever there are big changes in technology or relative prices, many of the standard rules of thumb for optimal choices fall apart, and many new alternatives have to be considered in a systematic way. This offers great scope for the design and use of simulation models that capture the key elements of an industrial process and expose the key alternatives for This paper was presented to the conference on Simulation Modelling and Decision in Energy Systems, held in Montreal in June, 1978 and sponsored by the International Association of Science and Technology for Development. It represents early results of work also reported in [1], [2], [3] and [4]. While Helliwell is a continuing member of U.B.C.'s Department of Economics, Cox is currently at M.I.T.'s Energy Laboratory Cambridge, Mass

Determination of cloud optical depth from multiple fields of view pyrheliometric measurements, The

December, 1982.Includes bibliographical references.Sponsored by the National Science Foundation ATM-8010691

Role of radiative processes in the diffusional mass evolution of cirrus hydrometeors, The

November, 1986.Includes bibliographical references

Identification of Carbohydrate Metabolism Genes in the Metagenome of a Marine Biofilm Community Shown to Be Dominated by Gammaproteobacteria and Bacteroidetes

Polysaccharides are an important source of organic carbon in the marine environment and degradation of the insoluble and globally abundant cellulose is a major component of the marine carbon cycle. Although a number of species of cultured bacteria are known to degrade crystalline cellulose, little is known of the polysaccharide hydrolases expressed by cellulose-degrading microbial communities, particularly in the marine environment. Next generation 454 Pyrosequencing was applied to analyze the microbial community that colonizes and degrades insoluble polysaccharides in situ in the Irish Sea. The bioinformatics tool MG-RAST was used to examine the randomly sampled data for taxonomic markers and functional genes, and showed that the community was dominated by members of the Gammaproteobacteria and Bacteroidetes. Furthermore, the identification of 211 gene sequences matched to a custom-made database comprising the members of nine glycoside hydrolase families revealed an extensive repertoire of functional genes predicted to be involved in cellulose utilization. This demonstrates that the use of an in situ cellulose baiting method yielded a marine microbial metagenome considerably enriched in functional genes involved in polysaccharide degradation. The research reported here is the first designed to specifically address the bacterial communities that colonize and degrade cellulose in the marine environment and to evaluate the glycoside hydrolase (cellulase and chitinase) gene repertoire of that community, in the absence of the biases associated with PCR-based molecular techniques

GMEM: Generalized Memory Management for Peripheral Devices

This paper presents GMEM, generalized memory management, for peripheral devices. GMEM provides OS support for centralized memory management of both CPU and devices. GMEM provides a high-level interface that decouples MMU-specific functions. Device drivers can thus attach themselves to a process's address space and let the OS take charge of their memory management. This eliminates the need for device drivers to "reinvent the wheel" and allows them to benefit from general memory optimizations integrated by GMEM. Furthermore, GMEM internally coordinates all attached devices within each virtual address space. This drastically improves user-level programmability, since programmers can use a single address space within their program, even when operating across the CPU and multiple devices. A case study on device drivers demonstrates these benefits. A GMEM-based IOMMU driver eliminates around seven hundred lines of code and obtains 54% higher network receive throughput utilizing 32% less CPU compared to the state-of-the-art. In addition, the GMEM-based driver of a simulated GPU takes less than 70 lines of code, excluding its MMU functions.Comment: Finished before Weixi left Rice and submitted to ASPLOS'2

Site Characterization Using Integrated Imaging Analysis Methods on Satellite Data of the Islamabad, Pakistan, Region

We develop an integrated digital imaging analysis approach to produce a first-approximation site characterization map for Islamabad, Pakistan, based on remote-sensing data. We apply both pixel-based and object-oriented digital imaging analysis methods to characterize detailed (1:50,000) geomorphology and geology from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) satellite imagery. We use stereo-correlated relative digital elevation models (rDEMs) derived from ASTER data, as well as spectra in the visible near-infrared (VNIR) to thermal infrared (TIR) domains. The resulting geomorphic units in the study area are classified as mountain (including the Margala Hills and the Khairi Murat Ridge), piedmont, and basin terrain units. The local geologic units are classified as limestone in the Margala Hills and the Khairi Murat Ridge and sandstone rock types for the piedmonts and basins. Shear-wave velocities for these units are assigned in ranges based on established correlations in California. These ranges include Vs30-values to be greater than 500 m/sec for mountain units, 200–600 m/sec for piedmont units, and less than 300 m/sec for basin units. While the resulting map provides the basis for incorporating site response in an assessment of seismic hazard for Islamabad, it also demonstrates the potential use of remote-sensing data for site characterization in regions where only limited conventional mapping has been done