bluuebunny/crossref_metadata_2025 huggingface dataset:
Surface Modification of Tool Steel Using Tungsten Arc Heat Source
Authors: Khan T.I. , Khalid F.A. , Orhan N.
Published: June 2004

Many steels and, particularly, low alloy steels, are commonly used in agricultural, transport and metal working industries. The wear resistance of such steels can be increased by employing heat treatments or surface coatings. Heat treatments are not limited to the surface and result in a change in the microstructure of the component. Therefore, although a wear resistant surface is obtained, other mechanical properties (e.g. toughness) of the substrate are compromised. When coatings are used, these have a tendency to fail along the coating/substrate interface and are lost from the surface. In the present study, intrinsic surface modification of a tool steel (H13) is undertaken by melting using a tungsten arc heat source and gaseous alloying of the surface achieved using nitrogen gas. The change in wear resistance is compared between untreated surfaces and surfaces modified under an argon shield. Changes in the wear behaviour of the steels are characterised using pin on plate wear testing equipment. The results show that the best wear resistance is achieved when surfaces are melted under a pure nitrogen or nitrogen–hydrogen shield. Metallurgical analysis and microindentation measurements are used to explain the differences between untreated and modified surfaces. SE/S283
Electric Probe Measurements in Pulsed Magnetron Plasmas
Authors: Bradley J.W. , Karkari S. , Vetushka A.
Published: June 2004

The temporal and spatial evolution of the plasma potential Vp in a pulsed magnetron discharge was determined using time resolved emissive probing techniques. Spatial maps of Vp in plasma were constructed and, at all positions, Vp followed the large changes in the cathode voltage Vd. Downstream, the potential always remained at least several volts above the most positive surface in the discharge. In the driven ‘on’ phase, the results showed an axial electric field generated in the bulk, with a potential drop ΔVp of ∼30 V over a distance of 4 cm from plasma to sheath edge, consistent with that observed in the dc magnetron. During the stable ‘reverse’ period of the discharge, the electric fields in the bulk were found to collapse. The temporal evolution of Vp confirms a simple picture of the behaviour of the pulsed magnetron, predicted from previous mass spectroscopic measurements of high energy ions in the plasma. Some implications of these results for the pulsed deposition process are suggested. SE/515
Novel Enhanced Magnetron Sputtering System
Authors: Yehya M. , Kelly P.J.
Published: June 2004

Magnetron sputtering is the process of choice for the deposition of a wide range of industrially important coatings. However, current processes have inherent limitations. In particular, the energy delivered to the growing film, the mass flux and the ion to atom ratio incident at the substrate, which have a profound effect on coating properties, cannot be readily varied using present technology. Consequently, film properties may not be optimal. In order to overcome these limitations, studies are being made of an enhanced sputtering system, in which alternative plasma sources have been incorporated into an otherwise standard magnetron sputtering system. The new system combines a gridless linear ion source (LIS) and a conventional magnetron to form a variable energy charge flux magnetron sputtering system (termed M-LIS). Detailed characterisation studies of this system were carried out and are reported here. Included are models of the magnetic field in the system, performance data of the M-LIS in different modes of operation and the impact of this source on the structure and properties of metallic and ceramic coatings. The relation between the energy delivered and the chemical composition of the surface is also discussed in comparison with films grown in a standard system. Results to date demonstrate that the enhanced system improves the flexibility of control of the growth parameters in a magnetron sputtering system. SE/516
Economic implications of hormesis
Authors: Hammitt James K
Published: June 2004

The implications of hormesis for decision making about control of environmental exposures are examined. From an economic perspective, environmental exposures should be controlled to a level that optimizes health effects and minimizes control costs. The possibility that substances are, or may be, hormetic poses no fundamental challenge for economic analysis. In contrast with the linear no-threshold model, optimal control may be either less or more stringent under the hormetic model, depending on the incremental control cost. When exposure levels or exposure-response functions differ across individuals or are uncertain, the optimal population-level control of exposure must balance possible benefits and harms to individuals against control costs. Economic-incentive-based regulatory instruments, such as tradable permits, are likely to offer less improvement relative to command-and-control regulations under a hormetic model than under a linear no-threshold model.
Economic implications of hormesis in policy making
Authors: Griffiths Charles
Published: June 2004

Economists face no fundamental problem in calculating the optimal exposure of a hormetic substance and this could potentially be set as a regulatory level. This level would be where the marginal cost of control is equal to the slope of the exposure-response function. There are a number of reasons, however, to expect public resistance to assuming hormesis. These reasons include the fact that hornesis implies a lower level or risk for any given exposure; it might be viewed as weakening regulatory standards; and it could justify low emissions if marginal costs are low. If all we care about are the negative effects measured by a single health endpoint, then the RfD (the level of exposure below which there is no appreciable risk) may be appropriate. Hormesis maintains the single endpoint, but accepts beneficial as well as deleterious effects. If we are going to accept beneficial effects then we should consider all health endpoints and all costs and benefits. This is simply benefit-cost analysis with a hormetic exposure-response curve. Because of legal constraints, this type of analysis may be of little use in setting tolerance levels, but may be important if the EPA chooses to adopt more voluntary policy measures.
Cryopreserved rat, dog and monkey hepatocytes: measurement of drug metabolizing enzymes in suspensions and cultures
Authors: Hewitt Nicola J , Utesch Dietmar
Published: June 2004

Metabolism in fresh and cryopreserved (CP) rat, dog and monkey hepatocyte suspensions and cultures was measured using midazolam (CYP3A), tolbutamide (CYP2C), dextromethorphan (CYP2D) and p-nitrophenol (glucuronosyl S-transferases (UGT), sulphotransferases (ST)).

CYP3A, CYP2C9, CYP2D6, UGT and ST enzyme functions in fresh and CP rat, dog and monkey hepatocyte suspensions were retained - CP rat hepatocytes lost some CYP2C activity but this was restored by adding NADPH or by placing the cells in culture, suggesting that the enzyme was still functional. Phase 2 activities were equivalent in fresh and CP hepatocyte suspensions. In some cases, incubation conditions increased the rate of metabolism, possibly reflecting de novo cofactor synthesis. However, this effect was substrate and species dependent and was not always the same in fresh and CP cells. CYP3A, CYP2C, CYP2D, UGT and ST activities at 24 hours of culture of rat and monkey hepatocytes were not compromised by cryopreservation. CYP3A, CYP2D but not CYP2C were lower in 24-hour cultures of CP dog hepatocytes than in fresh cells. Despite being lower than fresh cells, UGT activity in dog CP hepatocytes did not decrease from 0 to 24 hours of culture. Speciesspecific metabolism of p-nitrophenol could be demonstrated in both CP cell suspensions and cultures.

In conclusion, these data suggest that the enzyme characteristics of fresh and CP hepatocytes from each species and under specific incubation conditions should be considered when carrying out metabolism studies of new compounds.
Information technology and rural development
Authors: Richards Caspian
Published: June 2004

This paper outlines how the widespread belief that we are experiencing an ‘information technology revolution’ has aroused concerns about unequal access to its perceived benefits. These concerns are explored both through general perspectives on the information revolution and in the specific context of approaches to rural development in Europe, in particular the Highlands and Islands of Scotland. Various levels of government have launched initiatives to stimulate the use of information technology (IT) in the territories under their jurisdiction. This paper focuses on the rationale behind one widely employed strategy, encouraging IT use through promotional campaigns.
A spatial model with ordinal responses for grazing impact data
Authors: Brewer Mark J , Elston David A , Hodgson Matthew EA , Stolte Anneke M , Nolan Andrew J , Henderson David J
Published: June 2004

We propose a model for use with ordinal spatial data arising from field assessments of the grazing and trampling impact by animals on vegetation, and study the predictive performance of the model on partial surveys. We employ a mixed effects model, including a term for spatial correlation, which assumes a continuous underlying scale of grazing impact, and where the classification into discrete categories is made via cut-points. We analyse two classes of data: full census data and sample data drawn from the full census. In the latter case, we show that the estimation of nonsampled data improves as the spatial information included within the model increases.
Bioinformatics Strategies for Translating Genome‐Wide Expression Analyses into Clinically Useful Cancer Markers
Authors: RHODES DANIEL R. , CHINNAIYAN ARUL M.
Published: June 2004

Abstract: The DNA microarray has revolutionized cancer research. Now, scientists can obtain a genome‐wide perspective of cancer gene expression. One potential application of this technology is the discovery of novel cancer biomarkers for more accurate diagnosis and prognosis, and potentially for the earlier detection of disease or the monitoring of treatment effectiveness. Because microarray experiments generate a tremendous amount of data and because the number of laboratories generating microarray data is rapidly growing, new bioinformatics strategies that promote the maximum utilization of such data are necessary. Here, we describe a method to validate multiple microarray data sets, a Web‐based cancer microarray database for biomarker discovery, and methods for integrating gene ontology annotations with microarray data to improve candidate biomarker selection.
Evolutionary Fuzzy Modeling Human Diagnostic Decisions
Authors: PEÑA‐REYES CARLOS ANDRÉS
Published: June 2004

Abstract: Fuzzy CoCo is a methodology, combining fuzzy logic and evolutionary computation, for constructing systems able to accurately predict the outcome of a human decision‐making process, while providing an understandable explanation of the underlying reasoning. Fuzzy logic provides a formal framework for constructing systems exhibiting both good numeric performance (accuracy) and linguistic representation (interpretability). However, fuzzy modeling—meaning the construction of fuzzy systems—is an arduous task, demanding the identification of many parameters. To solve it, we use evolutionary computation techniques (specifically cooperative coevolution), which are widely used to search for adequate solutions in complex spaces. We have successfully applied the algorithm to model the decision processes involved in two breast cancer diagnostic problems, the WBCD problem and the Catalonia mammography interpretation problem, obtaining systems both of high performance and high interpretability. For the Catalonia problem, an evolved system was embedded within a Web‐based tool—called COBRA—for aiding radiologists in mammography interpretation.
World Estimates of Hydrate Resources, Basic Properties of Hydrates, and Azerbaijan Hydrates
Authors: Lerche Ian , Bagirov Elchin
Published: June 2004

Assessments of the available amounts of onshore and offshore hydrates have been given over the last twenty years. The first part of this paper evaluates all that is currently known about such estimates in respect of variations and also in respect of the date the estimate was made. The general conclusion is that the estimates have not yet stabilized with increasing amounts of information with time in respect of amount of hydrate resource.

The second part of the paper considers the basic physical properties of hydrates, ranging from density, speed of wave propagation, stability with respect to pressure and temperature, through to composition effects. The influence of these properties on detecting hydrates and also on their long-term stability is considered, particularly with respect to climate and sea level changes with time.

The third part of the paper considers an application to the offshore hydrates in the South Caspian basin, including the explosive hazard potential such hydrates provide and their ability to release copious amounts of methane into the atmosphere with time.
Activation and Impregnation of Chars — Nutshells and Pinewood Sawdust
Authors: Alvim-Ferraz Maria C.M. , Gaspar Carla M.T.B.
Published: June 2004

The utilization of activated carbons as catalyst supports for the treatment of gaseous effluents contaminated with volatile organic compounds allows advantage to be taken both of the adsorption of the pollutant on the well-developed porous texture of activated carbons and the possibility of an efficient catalytic conversion. The step of catalyst impregnation should be optimized to obtain a catalyst dispersion compatible with good conversions at sufficiently low temperatures.

Textural evolution when impregnation is performed either on the raw material or after activation of the latter has already been well studied. The work described in this paper was directed towards an analysis of the textural evolution of impregnated active carbons when the impregnation step was performed between carbonization and activation. To date, such knowledge is quite scarce. To allow comparison, impregnation with CoO, Co3O4 or CrO3 was carried out both after activation and after carbonization of nutshells and pinewood sawdust.

For both raw materials, impregnation after activation involved deposition of the impregnated oxides on the internal surface of the materials thereby blocking part of the initial micro- and meso-porous textures. When impregnation was conducted after carbonization, metal species acted as catalysts during the subsequent activation step (Co3O4 being the most efficient and CrO3 the least efficient) and allowed the better development of the porous texture. In nutshell carbons, the metal species remained dispersed in micropores with a smaller volume but a larger size and in the mesoporous texture with a larger volume. Sawdust carbons retained a microporous texture with narrow pores in which the deposition of catalysts did not occur.
Adsorption of Aromatic Compounds from Aqueous Solution by a Hypercrosslinked Polymeric Adsorbent with Sulphonic Groups
Authors: Wang Hai-Ling , Chen Jin-Long , Li Ai-Min , Zhai Zhi-Cai , Fei Zheng-Hao , Zhang Quan-Xing
Published: June 2004

A hypercrosslinked polymeric adsorbent with sulphonic groups, NG-5, was employed to remove p-toluidine, p-aminophenol and phenol from aqueous solutions and its performance and thermodynamic behaviour compared to that of the hypercrosslinked polymeric adsorbent CHA-111 containing no functional groups. It was found that the equilibrium adsorption data for the three aromatic compounds could be well fitted by the Langmuir and Freundlich isotherms. The results showed that the equilibrium adsorption capacities for p-toluidine and p-aminophenol on NG-5 were all greater than on CHA-111. This may be attributed to the strong hydrogen-bonding interaction between the adsorbent and the adsorbate, electrostatic interaction and π–π interaction. However, the adsorption capacity for phenol on NG-5 was lower than that on CHA-111 because of the larger surface area and micropore volume of the latter adsorbent. The sorption enthalpy changes were used to interpret the adsorption mechanism. In addition, the sorption of p-toluidine and p-aminophenol onto NG-5 was studied kinetically. The results showed that the adsorption process was mainly controlled by intraparticle diffusion.
Effect of Gas Stirring on External Mass Transfer, Intraparticle Diffusion and Energy Consumption during Adsorption
Authors: Fadali Olfat A.
Published: June 2004

Gas stirring was used to study the adsorption of basic dyes onto montmorillonite clay. This technique had been demonstrated previously as being more efficient than mechanical stirring. The experimental set-up employed was a fixed-bed column connected to an air-supply system with provision for controlling different airflow rates at different temperatures. The dyestuff used was Basic Red (a commercial dye). The rate of dye removal was found to increase with increasing gas flow and increasing temperature. Dye removals of 86% to 55% could be achieved for contact times of 35 min to 50 min using dye concentrations between 200 mg/l and 500 mg/l at a gas flow rate of 100 cm3/s. The calculated Langmuir constants demonstrated that clay is a favourable adsorbent for the basic dye. Compared to powdered activated carbon (PAC), the adsorption capacity of the clay was 41.3% while the relative cost of basic dye removal was 0.024-times that of PAC.

The external mass-transfer coefficient (Ks) and the intraparticle diffusion rate parameter (Kp) were calculated and evaluated as functions of gas stirring and temperature. It was found that an increase in the rate of adsorption effected by gas stirring was double that obtained by increasing the temperature due to the high turbulence induced by axial and radial flow created by gas stirring. The activation energy (E) of 5.95 kcal/mol demonstrated that adsorption of the basic dye onto clay was diffusion-controlled. The energy consumption (W) for removing a known percentage of the dye was evaluated and found to correlate with the equation W = 8.56Q1.02X8.63 for 50 < Q < 100 cm3/s, where Q is the gas flow rate and X is the percentage dye removal.
Adsorption of Cobalt(II) Ions from Aqueous Solution onto Activated Carbon Prepared from Hazelnut Shells
Authors: Demirbaş Erhan
Published: June 2004

Activated carbon prepared from hazelnut shells was used to remove Co(II) from aqueous solution by adsorption. Batch-mode adsorption experiments were carried out varying parameters such as the initial metal ion concentration (13.30–45.55 mg/l), agitation speed (50–200 rpm), pH (2–8), temperature (293–323 K) and particle size (0.80–1.60 mm). The kinetics of the adsorption of Co(II) followed the pseudo-second-order equation, being pH-dependent since the removal rate increased with the pH value of the aqueous solution. The adsorption equilibrium data obeyed the Langmuir isotherm. The adsorption capacity (Q0) calculated from the Langmuir isotherm was 13.88 mg Co(II)/g carbon at 303 K employing a pH value of 6 and a particle size of 1.00–1.20 mm. The thermodynamic parameters evaluated for the carbon revealed that the adsorption of Co(II) was endothermic in nature.
Adsorption Kinetics for the Removal of Co(II) and Zn(II) from Wastewater by Indion BSR — A Chelating Ion-Exchange Resin
Authors: Agrawal Archana , Sahu Kamala K.
Published: June 2004

A comparative study on the adsorption of zinc(II) and cobalt(II) from aqueous solutions onto Indion BSR, an indigenous cation-exchange resin, was undertaken in the present work. Various parameters for the removal of Co(II) and Zn(II) such as the initial solution pH, contact time, resin and metal ion concentration were optimized. The equilibrium data obtained were well fitted by both the Langmuir adsorption isotherm at pH 6.0 for 500 mg resin and the Freundlich adsorption isotherm under optimum conditions of contact time and pH 5.0 for 250 mg resin at 30°C. The adsorption of Zn(II) and Co(II) on this cation-exchange resin followed first-order reaction kinetics. Film diffusion of Co(II) and Zn(II) in this ion-exchange resin was shown to be the main rate-limiting step over the concentration range studied. The studies showed that the resin could be used as an efficient adsorbent for the removal of Co(II) and Zn(II) from aqueous solutions.
Adsorption of Aromatic Hydrocarbons on BTEA–Bentonites
Authors: Yıldız N. , Erol M. , Aktas Z. , Çalımlı A.
Published: June 2004

Organobentonites were synthesized using benzyltrimethyl-ammonium bromide (BTEA) with five different exchange degrees. At low concentrations, the amounts of BTEA exchanged did not reach the value of the cation-exchange capacity (CEC) of the bentonite. To obtain full displacement, it was necessary to add an amount of BTEA four-times greater than the CEC. Synthesized organobentonites were characterized by X-ray diffraction, particlesizeanalysis and infrared spectroscopy. The basal spacings of the organobentonites increased slightly with increasing amounts of BTEA cations. Particle-size analyses of the original bentonite and organobentonites showed that the organobentonites contained a greater number of coarse particles than present in the original bentonite. Toluene and xylenes were used as solutes to determine the adsorption properties of the BTEA–bentonites. The 4BTEA–bentonite was evaluated as an adsorbent of water-soluble aromatic hydrocarbons including toluene and xylenes.
Use of Electrochemical Noise Measurements for Determining the Rate of Corrosion and the Surfactant Aggregate Transition Concentration at the Mild Steel–Liquid Interface
Authors: Ryu Dong Y. , Free Michael L.
Published: June 2004

Corrosion events such as uniform corrosion, localized corrosion and hydrogen evolution at metal–liquid interfaces can be monitored by a combination of electrochemical noise and corrosion inhibition measurements. The effective prediction of corrosion inhibition by surfactants can be accomplished by determining the surfactant aggregation transition concentration (atc) at the metal–liquid interface. This paper discusses the use of electrochemical noise measurements for determining the atc as well as the rate of corrosion.
The Adsorption of Pentachlorophenol from Aqueous Solutions onto Exchanged Al-MCM-41 Materials
Authors: Marouf-Khelifa Kheira , Khelifa Amine , Belhakem Ahmed , Marouf Reda , Abdelmalek Fatiha , Addou Ahmed
Published: June 2004

The ability of a mesoporous molecular sieve to adsorb chlorinated phenols was studied experimentally. Thus, the adsorption isotherms of pentachlorophenol (PCP) from aqueous solutions were measured on (M)Al-MCM-41 (M = Na+, K+, Cu2+, Cr3+) at intervals of 10 K between 303 K and 323 K. The experimental isotherms obtained were of the S-type in terms of the classification of Giles and co-workers. The best fit of the adsorption isotherm data was obtained using the Freundlich model. The adsorption affinity of PCP increased in the order (K)Al-MCM-41 < (Cr)Al-MCM-41 < (Na)Al-MCM-41 < (Cu)Al-MCM-41. At the same temperature, the adsorption of PCP on (Cu)Al-MCM-41 was more pronounced compared to its adsorption on alumina-pillared montmorillonite and mesoporous alumina aluminium phosphates. Analysis of the isosteric curves showed that (Cu)Al-MCM-41 and (Na)Al-MCM-41 presented a heterogeneous profile. In contrast, (K)Al-MCM-41 and (Cr)Al-MCM-41 did not exhibit energetic heterogeneity throughout the entire range of coverage.
Equilibrium Adsorption of Single Component and Binary Mixtures of Aromatic Compounds onto a Polyfunctional Hypercrosslinked Polymeric Adsorbent
Authors: Fuqiang Liu , Jinlong Chen , Aimin Li , Zhenghao Fei , Junjie Ge , Quanxing Zhang
Published: June 2004

A polyfunctional hypercrosslinked polymeric adsorbent, LA-8, was synthesized and characterized. It was first used to investigate the adsorption properties of 1-amino-2-naphthol-4-sulphonic acid (1,2,4-acid), including the corresponding adsorption isotherms, thermodynamics and binary competitive adsorption with 2-naphthol. The Freundlich model gave good fits to both the single and binary adsorption isotherms, indicating an endothermic and favourable adsorption process. The positive value of ΔH0 for the single solute system was in the range of 30–60 kJ/mol showing the existence of integrated processes involving chemical interaction. The values of ΔG0 demonstrated the spontaneous nature of the adsorption process while the value of ΔS0 showed increased randomness at the solid–solution interface, thereby indicating the presence of stoichiometric displacement. Both ΔH0 and ΔS0 appeared to vary linearly with increased solid loading, qe.

Pre-adsorbed 2-naphthol molecules supplied another adsorption site for 1,2,4-acid, despite the existence of an antagonistic interaction with 2-naphthol. In simultaneous processes, the mechanism for 1,2,4-acid adsorption probably mainly involved van der Waals forces and hydrogen-bonding interaction. Furthermore, the adsorption of a greater amount of 2-naphthol onto the solid phase demonstrated the occurrence of interaction between the tested binary solutes. It was concluded that direct competition for adsorption sites was the dominant competitive mechanism.
Adsorption of Iron and Manganese Ions Using Low-Cost Materials as Adsorbents
Authors: Nassar Mamdouh M. , Ewida Kamal T. , Ebrahiem Ebrahiem E. , Magdy Yehia H. , Mheaedi Mansour H.
Published: June 2004

The removal of toxic metal ions (iron and manganese) from aqueous solution by adsorption was studied. The batch process was used either to remove each metal ion singly or both metals as a multi-component system. The adsorbents used were low-cost materials, viz. palm fruit bunch and maize cob. The adsorption isotherms demonstrated that the adsorbents behaved in a favourable manner towards metal ion adsorption. The adsorption capacities for iron ions on palm fruit bunch and maize cob were in the 57–80% range and for the manganese ion in the 50–79% range for initial concentrations between 1 ppm and 10 ppm. With mixtures of both metal ions, removal of iron ions from the mixture was in the 54–79% range and for the manganese ion in the 54–76% range. The extended Langmuir model gave poor agreement with the data for the adsorption of mixtures of the two metal ions while the P-factor model yielded good agreement.
Regeneration of Modified Bentonite Loaded with Phenol Using Supercritical Fluids
Authors: Salgın Uğur , Yıldız Nuray , Çalımlı Ayla
Published: June 2004

The desorption of phenol from organically modified bentonite (ODTMA–bentonite) using supercritical fluids was studied. Parameters such as pressure, temperature, supercritical fluid flow rate and co-solvent (entrainer) concentration were investigated. The maximum desorption of phenol (ca. 98 w/w%) using supercritical CO2 (SC CO2) was obtained by operating at 500 bar, 353 K and 3.33 × 10−8 m3 SC CO2/s. In the presence of ethanol as a co-solvent (10 v/v%), the maximum desorption of phenol attained a value of 97 w/w% using supercritical CO2 at low temperature (313 K) and pressure (300 bar) and a high supercritical fluid flow rate (3.33 × 10−8 m3 SC CO2/s). In addition, the results showed that the regenerated ODTMA–bentonite retained its adsorption power towards phenol even after several regeneration cycles. It was therefore concluded that exhausted/used organobentonites might be regenerated via processes involving supercritical fluid extraction.
Chitosan: A Natural Biopolymer for the Adsorption of Residue Oil from Oily Wastewater
Authors: Ahmad A.L. , Sumathi S. , Hameed B.H.
Published: June 2004

Chitosan, poly-β-(1,4)-2-acetamido-2-deoxy-Đ-glucose ( N-deacetylated) was used as an adsorbent to adsorb the excess oil from oily wastewater. Chitosan is a biodegradable cationic biopolymer achieved by the extensive deacetylation of chitin obtained from prawn shell waste.

Palm oil mill effluent (POME) is one of the major problematic oily wastewaters in Malaysia. Preliminary analysis showed that POME contains ca. 2000 mg/l residue oil. A bench-scale study of the adsorption by chitosan of residue oil in POME was conducted using a jar-test apparatus. Effects of experimental parameters such as the dosage of chitosan in powder and flake form, contact time, mixing rate, settling time and pH were studied in order to obtain the optimum conditions for the adsorption of residue oil from POME.

The results obtained showed that chitosan powder, at a dosage of 0.5 g/l and employing a contact time of 15 min, a mixing rate of 100 rpm, sedimentation for 30 min and a pH value of 5.0, provided the most suitable conditions for the removal of residue oil from POME. The removal efficiencies obtained were ca. 97–99%. FT-IR spectra and SEM micrographs of chitosan before and after adsorption were presented to prove that the residue oil had been adsorbed by chitosan.
Validated Digital Wind Atlas for Poland
Authors: Sander Johannes , Chun Stefan
Published: June 2004

A new Wind Atlas of Poland has been developed and established as a digital data base. The atlas compiles wind data of Poland and off-shore areas of the Baltic Sea. It includes maps of wind speed, air temperature and solar radiation. In addition, maps show the Weibull parameters of the statistical distribution of the wind speed. Time series of wind speed and wind direction are available every 6 km. Data are provided at 50 m, 75 m, 100 m, 125 m or 150 m above the surface. The wind data are validated with in-situ measurements of wind speed and with operational results from existing wind power plants. To access the huge amount of data a new interface was developed, which allows extremely fast access to the data. This Digital Wind Atlas of Poland is adapted to the needs of the wind industry and is probably the most advanced wind atlas of Poland of today.
Benefits for Wind Energy in Electricity Markets from Using Short Term Wind Power Prediction Tools; A Simulation Study
Authors: Usaola Julio , Ravelo Oswaldo , González Gerardo , Soto Fernando , Dávila Mª Carmen , Díaz–Guerra Belén
Published: June 2004

One of the characteristics of wind energy, from the grid point of view, is its non-dispatchability, i.e. generation cannot be ordered, hence integration in electrical networks may be difficult. Short-term wind power prediction-tools could make this integration easier, either by their use by the grid System Operator, or by promoting the participation of wind farms in the electricity markets and using prediction tools to make their bids in the market. In this paper, the importance of a short-term wind power-prediction tool for the participation of wind energy systems in electricity markets is studied. Simulations, according to the current Spanish market rules, have been performed to the production of different wind farms, with different degrees of accuracy in the prediction tool. It may be concluded that income from participation in electricity markets is increased using a short-term wind power prediction-tool of average accuracy. This both marginally increases income and also reduces the impact on system operation with the improved forecasts.
Cost Reduction Prospects for Offshore Wind Farms
Authors: Junginger Martin , Faaij André , Turkenburg Wim C.
Published: June 2004

The economics of offshore wind farms are presently less favorable than for onshore wind energy. Consequently there is a strong need for significant cost reductions in order to become competitive. About 70% of the electricity cost of offshore wind farms is determined by the initial investment costs, which mainly consist of the wind turbines, foundations, internal and external grid-connections and installation. Possible cost reductions until 2020 are explored for each of these components. Technological developments and cost reduction trends in both the offshore and onshore wind sector are analyzed. Information is also taken from offshore oil and gas sector and from the experience with high-voltage submarine transmission of electricity. Where possible, cost reduction trends are quantified using the experience curve concept, or otherwise based on expert judgments. Main drivers for cost reduction appear to be (a) design improvements and upscaling of wind turbines, (b) the continuing growth of onshore wind capacity, and (c) the development and high utilization rates of purpose-built installation vessels. Other factors are: reduction of steel prices, technological development of HVDC converter stations and cables, standardization of turbine and foundation design, and economies of scale for the wind turbine production. It is concluded that under different growth scenarios, investment costs of offshore wind farms may decline about 25–39% by 2020. Assuming an identical decline of annual O&M costs, the levelized electricity production costs are reduced from 6.8–7.2 to 4.2–5.4 €ct/kWh.
Wind Penetration Studies on the Island of Ireland
Authors: Doherty Ronan , Bryans Leslie , Gardner Paul , O'Malley Mark
Published: June 2004

This paper summarises two reports that were commissioned to analyse impacts of increasing the wind power penetration on the Island of Ireland. The first report was commissioned by Northern Ireland Electricity (NIE) and assesses the contribution renewable sources can make to the Northern Ireland electricity system. The second report was commissioned by the Commission for Energy Regulation (CER) and the Office for the Regulation of Electricity and Gas (Ofreg); it examines the possible effects increasing wind generation would have on the combined systems of Northern Ireland and the Republic of Ireland. The reports undertake a detailed analysis of the potential wind resource available, and the likely impact it may have on the respective transmission and distribution systems. The possible effects that increased amounts of wind generation may have on the system operation are examined and various economic implications are assessed.
Timber for High Efficiency Small Wind Turbine Blades
Authors: Peterson P. , Clausen P.D.
Published: June 2004

This paper explores technical and other issues arising from using shaped timber for a 1 metre long high efficiency blade for a small 600 W wind turbine. Two readily available Australian grown softwood timber species, radiata pine and hoop pine, were selected. Reasons for selecting these timbers are detailed in the paper. The fatigue life of the both timbers was determined using four point flexural testing. Results show that hoop pine is 25% stronger and 6% more fatigue resistant than radiata pine. A fatigue test procedure for the 1 m blade has been created based on the aeroelastic response of a 2.5 m long composite wind turbine blade and wind data from the Australian Bureau of Meteorology. Blade fatigue-life predictions, using Miners rule for fatigue damage accumulation, indicated effectively unlimited fatigue-life for a blade constructed from hoop pine, with the turbine operating at design performance in wind speeds up to 20 m/s. The blade's life was reduced to a few months when it was constructed from radiata pine for the same operating conditions to 20 m/s. However for an upper wind speed of 17 m/s, the predicted blade fatigue-life is effectively unlimited for both species. Test blades were machined in both radiata pine and hoop pine on a 3-axis milling machine with tool paths created using Pro/Manufacture software. Some of the important issues with respect to creating the blades out of timber are discussed.
Challenges of Increased Wind Energy Penetration in Ireland
Authors: Bazilian Morgan , Denny Eleanor , O'Malley Mark
Published: June 2004

Ireland is a facing a critical time in the formation of a robust renewable energy (RE) policy, due to its size, relative isolation, grid infrastructure, and fuel import dependency. The inherent intermittency and unpredictability of wind power make its increased penetration into the electricity network an area requiring significant further analysis. This paper details the state of the Irish electricity system at the end of 2003, describes the status of the electricity market and puts into perspective the technical issues which need to be resolved to increase wind penetration on the island of Ireland.
Assessing the Potential of Wind Energy Generation into the Santa Catarina Grid Network in Brazil
Authors: Beyer H.G. , Silva G. Kuhnen , Picht A. , Reguse W. , Passos J.C.
Published: June 2004

Electricity supply in Brazil is now dominated by hydro power plants (∼90% of the generation capacity) and suffers from instability of supply due to shortages in the hydro resource. In addition, problems due to the limitations in the capacity of the transmission and distribution network occur. Therefore the utility companies in Brazil are being forced to broaden the base of their electricity generation capacity and to implement power generation units located close to the consumption. In particular Celesc, the regional utility company in the State of Santa Catarina in Southern Brazil, is considering the introduction of wind power in its area. Celesc presently bases its supply on generation from of its own small hydro plants, from a few power stations of independent producers and, mainly, from the purchase of electricity on the national market. The first 600 kW wind turbine was commissioned in April 2002 and a total installed capacity of about 12 MW of wind power is foreseen in the coming years. To support these activities, the first assessment of the regional wind power potential and its load carrying capability is in progress.
Principles of a Simulation Model for a Variable-Speed Pitch-Regulated Wind Turbine
Authors: Camblong H. , Vidal M. Rodriguez , Puiggali J.R.
Published: June 2004

This paper considers the basic principles for establishing a simulation-model of a variable speed, pitch regulated, wind turbine. This model is used to test various control algorithms designed with the aim of maximising energetic yield and robustness and minimising flicker emission and dynamic drive train loads. One of the most complex elements of such a system is the interaction between wind and turbine. First, a detailed and didactic analysis of this interaction is given. This is used to understand some complicated phenomena, and to help design a simpler and more efficient (in terms of processing time) mathematical model. Additional submodels are given for the mechanical coupling, the pitch system and the electrical power system, before the entire model is validated by comparison with filed measurements on a 180 kW turbine. The complete simulation model is flexible, efficient and allows easy evaluation of different control algorithms.
Algorithm for the Estimation of the Long-Term Wind Climate at a Meteorological Mast Using a Joint Probabilistic Approach
Authors: García-Rojo Ramón
Published: June 2004

A new automatic method of calculation of a long-term representative wind climate is proposed. The procedure is based on the calculation of the joint probability distribution of the wind at a local station and at a long-term reference meteorological mast. The results obtained with this algorithm are compared with estimations of the long-term climate obtained with a Measure-Correlate-Predict method. The agreement found is good, even for very different periods of measurement.
Bimodal versus Weibull Wind Speed Distributions: An Analysis of Wind Energy Potential in La Venta, Mexico
Authors: Jaramillo O. A. , Borja M. A.
Published: June 2004

The International Standard IEC 61400-12 and other international recommendations suggest the use of the two-parameter Weibull probability distribution function (PDF) to estimate the Annual Energy Production (AEP) of a wind turbine. Most of the commercial software uses the unimodal Weibull PDF as the default option to carry out estimations of AEP, which in turn, are used to optimise wind farm layouts. Furthermore, AEP is essential data to assess the economic feasibility of a wind power project. However, in some regions of the world, the use of these widely adopted and recommended methods lead to incorrect results. This is the case for the region of La Ventosa in Mexico, where the frequency of the wind speed shows a bimodal distribution. In this work, mathematical formulations by using a Weibull PDF and a bimodal distribution are established to compare the AEP, the capacity factor and the levelised production cost for a specific wind turbine. By combining one year of wind speed data with the hypothetic power performance of the Vestas V27-225 kW wind turbine, it was found that using the Weibull PDF underestimates AEP (and thus the Capacity Factor) by about 12%.
Input-Output Analysis for Installing Renewable Energy Systems
Authors: Itoh Yoshinori , Nakata Toshihiko
Published: June 2004

Renewable energy facilities have been installed in many regions, because of their possibility to be an alternative to fossil fuels for mitigating global warming. Besides the profitability of renewable energy businesses, indirect economic effects of installing renewable energy facilities should be clarified. This study examines the possibility that the renewable energy facilities give renewed impetus to regional economic progress. The economic effects are analysed with input-output techniques in a rural area in Japan. As a consequence, both positive and negative effects on the rural economy are derived. In addition, we will focus on the changes in sectors such as construction, business services, banking, etc. as a result of economic activities for renewable systems. The business benefits of renewable energy system are discussed.
R&D and Innovation Policy — Preconditions for Making Steps towards a 2000 WATT/CAP Society
Authors: Jochem Eberhard
Published: June 2004

The paper reports on the methodology and results of several studies on the long-term efficiency potentials in the two energy transformation steps from primary energy to final and useful energy and, more importantly, from useful energy to energy services. The examination of these potentials considers the lifetimes and periods of refurbishment of manufactured artefacts: Buildings and infrastructure that will save or waste energy in 2050 that are being built or restored today. The paper emphasises the enormous size of energy conservation potentials achievable not only by reducing energy losses but also by decreasing the specific activity levels for several energy services through improved material efficiency and intensified use of products, plants, and vehicles. It also reports on major definitive conclusions on R&D needs and challenges to R&D-policies as well as immediate policy action in OECD-countries in order to realise the vision of reducing primary energy use per capita by two thirds in industrialised countries within the next five decades.
Regulation and Competition in the Lithuanian District Heating Sector
Authors: Gatautis Ramunas
Published: June 2004

Practice shows that long experience in the development and management of district heating in Denmark and Finland cannot be directly transferred to Eastern European countries. Unfortunately, strict regulation in post Soviet countries is not very effective and results are not as good as in Western countries, who have a long tradition of public regulation. State or municipally owned vertical monopolies are inflexible to consumers' needs. Given today's tendency to attract private capital for the modernization and management of district heating systems a new problem arises because a private vertical monopoly is much more difficult to regulate effectively than the state owned monopoly (as demonstrated by Lithuanian practice). Stimulating competitive activities, wherever possible and regulating monopolistic behaviour, could be an attractive way of seeking to solve fundamental problems in the district heating sector of Lithuania and other Central and East European countries. A scheme for a liberalized district heating sector with harmonized competitive and monopolistic activities is presented in the article.
Experience Curves Vs Dynamic Cost-Resource Curves and Their Impact on the Assessment of the Future Development of Renewables
Authors: Resch Gustav , Faber Thomas , Haas Reinhard , Huber Claus
Published: June 2004

The recent development of several Renewable Energy Sources for electricity generation (RES-E) is characterised by decreasing investment costs and limited resources. In this paper we analyse the ambiguous role of these two effects and the consequences for deriving effective promotion policies for RES-E. Dynamic costresource curves will be derived which combine both approaches. They represent a tool to assist policy makers in deriving efficient and effective promotion instruments. By its application results can be gained with respect to both costs (i.e. efficiency) and penetration (i.e. effectiveness). Due to the combined consideration of resource restrictions and dynamic cost developments, dynamic cost-resource curves assist in deriving the optimal time-path for policy instruments.
Incompatible 4-node Element for Gradient-Dependent Plasticity
Authors: Chen G. , Baker G.
Published: June 2004

In gradient-dependent plasticity theory, the yield strength depends on the Laplacian of an equivalent plastic strain measure (hardening parameter), and the consistency condition results in a differential equation with respect to the plastic multiplier. The plastic multiplier is then discretized on the mesh, in addition to the usual discretization of the displacements, and the consistency condition is solved simultaneously with the equilibrium equations. The notorious disadvantage is that the plastic multiplier requires a Hermitian interpolation which has four degrees of freedom at each node. However, in this article, an incompatible (trigonometric) interpolation is proposed for the plastic multiplier. This incompatible interpolation uses only the function values of each node, but both the function and first-order derivatives are continuous across element boundaries. It greatly reduces the degrees of freedom for a problem, and is shown through numerical examples on localization to give good results.
Npa1p is an essential trans-acting factor required for an early step in the assembly of 60S ribosomal subunits in Saccharomyces cerevisiae
Authors: ROSADO IVÁN V. , DE LA CRUZ JESÚS
Published: June 2004

Ribosome biogenesis requires >100 nonribosomal proteins, which are associated with different preribosomal particles. The substrates, the interacting partners, and the timing of action of most of these proteins are largely unknown. To elucidate the functional environment of the putative ATP-dependent RNA helicase Dbp6p from Saccharomyces cerevisiae, which is required for 60S ribosomal subunit assembly, we have previously performed a synthetic lethal screen and thereby revealed a genetic interaction network between Dbp6p, Rpl3p, Nop8p, and the novel Rsa3p. In this report, we extended the characterization of this functional network by performing a synthetic lethal screen with the rsa3 null allele. This screen identified the so far uncharacterized Npa1p (YKL014C). Polysome profile analysis indicates that there is a deficit of 60S ribosomal subunits and an accumulation of halfmer polysomes in the slowly growing npa1-1 mutant. Northern blotting and primer extension analysis shows that the npa1-1 mutation negatively affects processing of all 27S pre-rRNAs and the normal accumulation of both mature 25S and 5.8S rRNAs. In addition, 27SA2 pre-rRNA is prematurely cleaved at site C2. Moreover, GFP-tagged Npa1p localizes predominantly to the nucleolus and sediments with large complexes in sucrose gradients, which most likely correspond to pre-60S ribosomal particles. We conclude that Npa1p is required for ribosome biogenesis and operates in the same functional environment of Rsa3p and Dbp6p during early maturation of 60S ribosomal subunits.