bluuebunny/crossref_metadata_2025 huggingface dataset:
A Special Orogenic‐type Rare Earth Element Deposit in Maoniuping, Sichuan, China: Geology and Geochemistry
Authors: WANG Denghong , YANG Jianmin , YAN Shenghao , XU Jue , CHEN Yuchuan , PU Guangping , LUO Yaonan
Published: November 2008

Abstract: The Maoniuping REE deposit is the second largest light rare earth elements deposit in China, explored recently in the northern Jinpingshan Mountains, a Cenozoic intracontinental orogenic belt in southwestern China. It is a vein‐type deposit hosted within, and genetically related to, carbonatite‐alkalic complex. Field investigation and new geochemical data of the carbonatites from the carbonatite‐alkalic complex support an igneous origin for the Maoniuping carbonatites and related REE mineralization. Carbonatite itself carries rare earth elements which were enriched by hydrothermal solution.

It is known that most of the REE deposits related to carbonatite‐alkalic complexes were formed in relatively stable tectonic setting such as cratonic or rifting environment. The Maoniuping deposit, however, was formed during the processes of Cenozoic orogeny. Although the Maoniuping deposit is located in the north sector of the Panxi paleo‐rift zone, the rift had been closed before early Cenozoic and evolved into an intracontinental orogenic belt, i.e., the Jinpingshan Orogen, which was formed since later Mesozoic to early Cenozoic. Geochronological and geochemical data also prove that the Maoniuping REE deposit was formed in an intracontinental orogenic belt instead of rift system or stationary block.

The Maoniuping REE deposit is similar to the Mountain Pass REE deposit in many respects such as the high contents of bastnaesite and barite, the low content of niobium, and the common occurrence of sulfides. The discovery of the Maoniuping deposit and other REE deposits during the past two decades suggest a good potential for prospecting REE deposits along the alkalic complex belt located on the eastern side of the Qinghai–Xizang–West Sichuan Plateau.
Geochemical Cycles of Bio‐essential Elements on the Early Earth and Their Relationships to Origin of Life
Authors: KAKEGAWA Takeshi , NODA Masakazu , NANNRI Hideyuki
Published: November 2008

Abstract: The bio‐essential elements are demanded for the metabolic action of all living organisms. These elements are continuously supplied to biosphere through the elemental cycle on the surface Earth. The geochemical cycle of bio‐essential elements was most likely different in the pre‐biotic era (ca. 4.4 to 4.0 Ga) compared to the modern Earth. The difference was probably made by the absence of continents and biological mediation in the pre‐biotic environments. Geochemical cycle models of bio‐essential elements (P, B and Mo) on the pre‐biotic Earth are proposed in this study, and these models are examined using available geochemical data.

The input flux of phosphorous in pre‐biotic oceans was probably dominated by submarine hydrothermal activities associated with carbonatized oceanic crusts. Such input flux by submarine hydrothermal activities is not known in the present‐day oceans, and probably a unique flux in the pre‐biotic oceans. Boron chemistry of pre‐biotic oceans was also controlled by submarine hydrothermal input flux. The Mo exchange between the pre‐biotic ocean and lithosphere may have restricted only at the submarine hydrothermal areas. These suggest that the submarine hydrothermal discharging areas were only locations to obtain bio‐essential elements for the earliest life. This model is consistent with the previously proposed model for hydrothermal origin of life.
Metallogenesis of Porphyry Cu Deposits of the Western Luzon Arc, Philippines: K‐Ar ages, SO3 Contents of Microphenocrystic Apatite and Significance of Intrusive Rocks
Authors: IMAI Akira
Published: November 2008

Abstract: K–Ar ages of the following porphyry Cu deposits in the western Luzon arc are determined: Lobo‐Boneng (10.50.4 Ma), Santo Niño (9.50.3 Ma), Black Mountain (2.10.1 Ma), Dizon (2.50.2 Ma) and Taysan (7.30.2 Ma). Microphenocrys‐tic apatite in the late Cenozoic intermediate to silicic intrusions associated with porphyry Cu deposits in the western Luzon arc contains sulfur as SO3 detectable by electron probe microanalyzer. Sulfur is supposed to have been accommodated dominantly as oxidized species in oxidizing hydrous magmas that generated porphyry Cu deposits. Likewise, such high SO3 contents in microphenocrystic apatite are common characteristics of the intermediate to silicic magmatism of the western Luzon arc, from tonalitic rocks of the Luzon Central Cordillera of about 15 Ma to an active magmatism at Mount Pinatubo. Thus, the western Luzon arc has been generating porphyry Cu mineralization associated with oxidizing hydrous intermediate to silicic magmatism related to eastward subduction, since Miocene to the present day. Intermediate to silicic rocks since 15 Ma to present‐day western Luzon arc generally show high whole‐rock Sr/Y ratio ranging from 20 to 184. However, porphyry Cu deposit is not necessarily related to the rocks that show higher Sr/Y ratios compared to the other barren rocks in the western Luzon arc. The characteristics of the intermediate to silicic magma associated with porphyry Cu deposit are not attributed to the composition of the source material of the magma, but to the properties defined by the high activity of oxidized species of sulfur in the fluid phase that is encountered during the generation of intermediate to silicic magmas.
Late Cenozoic Metallogeny of Southwest Hokkaido, Japan
Authors: WATANABE Yasushi
Published: November 2008

Abstract: This paper reviews the Miocene to Pleistocene tectonic framework, geology, magmatic style and stress field of southwest Hokkaido, Japan, and compiles deposit form, type, ore and alteration minerals, strike and length of mineralized veins, and associated igneous activity. The late Cenozoic tectonic regime of the Sapporo‐Iwanai ore district is divided into five periods on the basis of the subduction mode of the Pacific plate: Period 1 (15.0–12.1 Ma) oblique‐subduction setting with an orthogonal convergence rate (OCR) of 51–81 mm/y; Period 2 (12.1–6.2 Ma) normal subduction with an OCR of 81–94 mm/y; Period 3 (6.2–3.6 Ma) oblique subduction setting with an OCR of 73–99 mm/y; Period 4 (3.6–1.5 Ma) normal‐subduction setting with an OCR of 99–103 mm/y and Period 5 (1.5–0 Ma) oblique‐subduction setting with an OCR from 99 to 57 mm/y.

The hydrothermal deposits in the district include Kuroko deposits of Period 1 and epithermal vein‐type deposits of Periods 2 to 5. The Kuroko deposits were accompanied by submarine monogenetic rhyolite volcanism associated with tholeiitic basalt in the backarc region. In contrast, Late Miocene to Pliocene epithermal vein‐type deposits were associated mainly with polygenetic andesite and monogenetic rhyodacite volcanism of calc‐alkaline series. These different styles of magmatism occurred in an extensional tectonic regime (Period 1), and weakened extensional (Periods 2–3) or neutral tectonic regimes (Periods 4). Periods 2–5 epithermal vein‐type deposits are divided into base‐metal and precious‐metal deposits. The base‐metal deposits are associated mainly with large (>5 km in diameter) polygenetic andesitic volcanoes and subvol‐canic intrusions. The precious‐metal deposits are associated with small (<5 km in diameter) polygenetic or monogenetic volcanoes and/or subvolcanic intrusions of andesite, dacite and rhyolite near the volcanic arc front. This difference in distribution is ascribed to different states of horizontal differential stress.

Productive vein‐type deposits, such as Toyoha, Inakuraishi, Ohe and Chitose, formed in the neutral regime with a large horizontal differential stress during Period 4, which may have promoted strike‐slip faulting and non–extrusive, subvol‐canic intrusion. This tectonic regime and stress field resulted from the normal subduction of the Pacific plate with elevated velocity. This observation leads to the conclusion that large metallic deposits in southwest Hokkaido are expected to have formed primarily during Pliocene magmatic‐hydrothermal activity, when the orthogonal convergence rate was highest and strike‐slip faulting was active.
Petrochemistry of Volcanic Rocks in the Hishikari Mining Area of Southern Japan, with Implications for the Relative Contribution of Lower Crust and Mantle‐derived Basalt
Authors: Hosono Takahiro , Nakano Takanori
Published: November 2008

Abstract. This study presents the petrographical, mineralogical, and geochemical characteristics of Late Pliocene‐Pleistocene volcanic rocks distributed in the Hishikari gold mining area of southern Kyushu, Japan, and discusses their origin and evolution. The Hishikari volcanic rocks (HVR), on the basis of age and chemical compositions, are divided into the Kurosonsan (2.4–1.0 Ma) and Shishimano (1.7–0.5 Ma) Groups, which occur in the northern and southern part of the area, respectively. Each group is composed of three andesites and one rhyodacite. HVR are characterized by high concentrations of incompatible elements compared with other volcanic rocks in southern Kyushu, and have low Sr/Nd and high Th/U, Th/Pb, and U/Pb ratios compared with typical subduction‐related arc volcanic rocks.

Modal and whole‐rock compositions of the HVR change systematically with the age of the rocks. Mafic mineral and augite/hypersthene ratios of the andesites decrease with decreasing age in the Kurosonsan Group, whereas in the Shishimano Group, these ratios are higher in the youngest andesite. Similarly, major and trace element compositions of the younger andesites in the former group are enriched in felsic components, whereas in the latter group the youngest andesite is more mafic than older andesites. Moreover, the crystallization temperature of phenocryst minerals decreases with younger age in the former group, whereas the opposite trend is seen in the latter group. Another significant feature is that rhyodacite in the Shishimano Group is enriched in felsic minerals and incompatible elements, and exhibits higher crystallization temperatures of phenocryst minerals than the rhyodacite of the Kurosonsan Group.

Geochemical attributes of the HVR and other volcanic rocks in southern Kyushu indicate that a lower subcontinental crust, characterized by so‐called EMI‐type Sr‐Nd and DUPAL anomaly‐like Pb isotopic compositions, is distributed beneath the upper to middle crust of the Shimanto Supergroup. The HVR would be more enriched in felsic materials derived from the lower crust by high‐alumina basaltic magma from the mantle than volcanic rocks in other areas of southern Kyushu. The Kurosonsan Group advanced the degree of the lower crust contribution with decreasing age from 51 %, through 61 and 66 % to 77 %. In the Shishimano Group, the younger rhyodacite and andesite are derived from hotter magmas with smaller amounts of lower crust component (58 and 57 %) than the older two andesites (65 % and 68 %). We suggest that the Shishimano rhyodacite, which is considered to be responsible for gold mineralization, was formed by large degree of fractional crystallization of hot basaltic andesite magma with less lower crustal component.
Subsurface Occurrence of Natural Gas Hydrate in the Nankai Trough Area: Implication for Gas Hydrate Concentration
Authors: Uchida Takashi , Lu Hailong , Tomaru Hitoshi
Published: November 2008

Abstract. The Nankai Trough runs along the Japanese Islands, where extensive BSRs have been recognized in its forearc basins. High resolution seismic surveys and site‐survey wells undertaken by the MITI have revealed the gas hydrate distribution at a depth of about 290 mbsf. The MITI Nankai Trough wells were drilled in late 1999 and early 2000. The highlights were successful retrievals of abundant gas hydrate‐bearing cores in a variety of sediments from the main hole and the post survey well‐2, keeping the cored gas hydrate stable, and the obtaining of continuous well log data in the gas hydrate‐dominant intervals from the main hole, the post survey well‐1 and the post survey well‐3. Gas‐hydrate dominant layers were identified at the depth interval from 205 to 268 mbsf. Pore‐space hydrate, very small in size, was recognized mostly filling intergranular pores of sandy sediments. Anomalous chloride contents in extracted pore water, core temperature depression, core observations as well as visible gas hydrates confirmed the presence of pore‐space hydrates within moderate to thick sand layers. Gas hydrate‐bearing sandy strata typically were 10 cm to a meter thick with porosities of about 40 %. Gas hydrate saturations in most hydrate‐dominant layers were quite high, up to 90 % pore saturation.

All the gas hydrate‐bearing cores were subjected to X‐ray CT imagery measurements for observation of undisturbed sedimentary textures and gas‐hydrate occurrences before being subjected to other analyses, such as (1) petrophysical properties, (2) biostratigraphy, (3) geochemistry, (4) microbiology and (5) gas hydrate characteristics.
Redox and Compositional Parameters for Interpreting the Granitoid Metallogeny of Eastern Australia: Implications for Gold‐rich Ore Systems
Authors: Blevin Phillip L.
Published: November 2008

Abstract. Granitoids and related rocks of eastern Australia can be classified according to their metallogenic potential using a scheme based on compositional character, degree of compositional evolution, degree of fractionation, and oxidation state. The scheme is based on empirical and theoretical considerations and satisfactorily describes the known distribution of granite‐related mineralisation.

The granitoids range from unevolved, mantle compatible compositions to highly evolved and fractionated. They exhibit age‐ and region‐specific variations in silica content, compositional evolution and oxidation state. The most unevolved intrusive igneous rocks comprise those of the Ordovician of the Lachlan Orogen, and the Devonian of the New England Orogen. Strongly fractionated and evolved I‐type granites occur in western Tasmania, the southern New England Orogen, and far north Queensland. Other fractionated suites tend to occur relatively rarely in the Lachlan Orogen and elsewhere. Oxidation states vary markedly. The most consistently oxidised rocks occur in the Ordovician of the central Lachlan Orogen, and the northernmost New England Orogen. The Carboniferous I‐types of the northeastern Lachlan Orogen are consistently more oxidised than other Lachlan Orogen I‐types.

Gold‐rich, Cu‐poor systems associated with felsic I‐types in eastern Australia are associated with W‐Mo mineralised suites with gold occurring within a predictable metallogenic zonation. Gold mineralised I‐types comprise weakly to moderately oxidised, high‐K granitoid suites that, at least in the east Australian context, have low K/Rb ratios and show strong fractionation trends. Gold is readily removed from granitic magmas through the early precipitation of sulfides, or to a lesser extent by magnetite. Crystallisation of Fe‐poor, silica‐rich granitic magmas in a relatively narrow oxidation window between the FMQ and NNO buffers may provide conditions where retention of Au in magmas in felsic granitic magmas is optimised.
The Northern Cordilleran Mid‐Cretaceous Plutonic Province: Ilmenite/Magnetite‐series Granitoids and Intrusion‐related Mineralisation
Authors: Hart Craig J. R. , Goldfarb Richard J. , Lewis Lara L. , Mair John L.
Published: November 2008

Abstract.Twenty‐five Early and mid‐Cretaceous (145–90 Ma) plutonic suites and belts are defined across Alaska and Yukon, in the northern North American Cordillera, on the basis of lithological, geochemical, isotopic, and geochronometric similarities. These features are combined with aeromagnetic characteristics, magnetic susceptibility measurements, and whole‐rock ferric: ferrous ratios to ascertain the distribution of magnetite‐ and ilmenite‐series plutonic belts. Magnetite‐series plutonic belts are dominantly associated with the older parts of the plutonic episode and comprise subduction‐generated metaluminous plutons that are distributed preferentially in the more seaward localities dominated by primitive tectonic elements. Ilmenite‐series plutonic belts comprise slightly younger, slightly peraluminous plutons in more landward localities in pericratonic to continental margin settings. They were likely initiated in response to crustal thickening following terrane collision. The youngest plutonic belt forms a small, but significant, magnetite‐series belts in the farthest inboard position, associated with alkalic plutons that were emplaced during weak extension.

Intrusion‐related metallogenic provinces with distinctive metal associations are distributed, largely in accord with classical redox‐sensitive granite‐series. Copper, Au, and Fe mineralisation are associated with magnetite‐series plutons and tungsten mineralisation associated with ilmenite‐series plutons. However, there are some notable deviations from expected associations, as intrusion‐related Ag‐Pb‐Zn deposits are few, and significant tin mineralisation is rare. Most significantly, many gold deposits and occurrences are associated with ilmenite‐series plutons: these form the basis for the newly recognized reduced intrusion‐related gold deposit model.
Helium Isotope Geochemistry of Ore‐forming Fluids from Furong Tin Orefield in Hunan Province, China
Authors: Li Zhao‐li , Hu Rui‐zhong , Peng Jian‐tang , Bi Xian‐wu , Li Xiao‐min
Published: November 2008

Abstract. The Furong tin orefield, located in southern Hunan, China, is a newly‐discovered super‐large tin orefield. In contrast to most other tin deposits associated with S‐type granites, the Furong tin deposit is closely associated with the Qitianling A‐type granite. The 3He/4He ratios of fluid inclusions in pyrite and arsenopyrite from this orefield range from 0.13 to 2.95 Ra. The influence of various post‐mineralization processes on the helium isotopic composition of ore‐forming fluid inclusions are estimated negligible. Thus, the analytical values of helium isotopic composition basically represent the original values of ore‐forming fluids at the time they were trapped.

The 3He/4He ratios of ore‐forming fluids from the Furong orefield indicate the existence of mantle‐source components. It supports the idea that both the Furong tin orefield and Qitianling granite formed under the geodynamic background of mantle upwelling and crustal extension.
REE Mineralization of Weathered Crust and Clay Sediment on Granitic Rocks in the Sanyo Belt, SW Japan and the Southern Jiangxi Province, China
Authors: Murakami Hiroyasu , Ishihara Shunso
Published: November 2008

Rare earth element (REE) geochemistry and mineralogy have been studied in the weathered crusts derived from the Early Yanshanian (Jurassic) biotite granites of Dabu and Dingnan, as well as in the Indosinian (Permian) muscovite–biotite granite of Aigao in southern Jiangxi province, China, and the weathered crusts and clay sediments on biotite granites in the Sanyo belt, SW Japan, that is, Okayama, Tanakami, and Naegi areas. In all of the weathered crusts, biotite and plagioclase commonly tend to decrease toward the upper part of the profile, whereas kaolinite and residual quartz and K‐feldspar increase. The weathered crusts of the Dingnan granites and some Naegi granites, which are characterized by the enrichment in light REE (LREE) in C horizons, have higher total REE (ΣREE) content than the parent REE‐enriched granites. Weathering of LREE‐bearing apatite and fluorocarbonates in the Dingnan granites and allanite and apatite in some Naegi granites may account for the leaching of LREE at the B horizons. The leached LREE must result in subsequent enrichment of LREE in the C horizons. The enrichment is probably associated with mainly adsorption onto kaolinite and partly formation of possible secondary LREE‐bearing minerals. In Japan it was found that REE mineralization occurs not in the weathered granitic crusts but in reworked clay sediments, especially kaolinite‐rich layers, derived mainly from the weathering materials of REE‐enriched granitic rocks. The clay sediments are more enriched in LREE, which likely adsorbed onto kaolinite. Concentration of heavy REE within almost all the weathered crusts and clay sediments, however, may reflect mainly residual REE‐bearing minerals such as zircon, which originated in the parent granitic rocks. The findings of the present study support the three processes for fractionation of the REE during weathering: (i) selective leaching of rocks containing both stable and unstable REE‐bearing minerals; (ii) adsorption onto clay minerals; and (iii) presence of possible secondary LREE‐bearing minerals.
Rare Earth Element Enrichment in Late Archean Manganese Deposits from the Iron Ore Group, East India
Authors: Moriyama Takeru , Panigrahi Mruganka K. , Pandit Dinesh , Watanabe Yasushi
Published: November 2008

The major, trace and rare earth element (REE) composition of Late Archean manganese, ferromanganese and iron ores from the Iron Ore Group (IOG) in Orissa, east India, was examined. Manganese deposits, occurring above the iron formations of the IOG, display massive, rhythmically laminated or botryoidal textures. The ores are composed primarily of iron and manganese, and are low in other major and trace elements such as SiO2, Al2O3, P2O5and Zr. The total REE concentration is as high as 975 ppm in manganese ores, whereas concentrations as high as 345 ppm and 211 ppm are found in ferromanganese and iron ores, respectively. Heavy REE (HREE) enrichments, negative Ce anomalies and positive Eu anomalies were observed in post‐Archean average shale (PAAS)‐normalized REE patterns of the IOG manganese and ferromanganese ores. The stratiform or stratabound shapes of ore bodies within the shale horizon, and REE geochemistry, suggest that the manganese and ferromanganese ores of the IOG were formed by iron and/or manganese precipitation from a submarine, hydrothermal solution under oxic conditions that occurred as a result of mixing with oxic seawater. While HREE concentrations in the Late Archean manganese and ferromanganese ores in the IOG are slightly less than those of the Phanerozoic ferromanganese ores in Japan, HREE resources in the IOG manganese deposits appear to be two orders of magnitude higher because of the large size of the deposits. Although a reliable, economic concentration technique for HREE from manganese and ferromanganese ores has not yet been developed, those ores could be an important future source of HREE.
Chemical Evolution of Zircons in the Paleogene Naegi Granite, Central Japan
Authors: Ishihara Shunso
Published: November 2008

The chemical composition of zircons from S‐ and I‐type ilmenite‐series granitic rocks in the Chubu district is summarized based upon recent electron probe microanalysis. Zircons in S‐type Busetsu granite of the Ryoke Metamorphic Belt have a homogeneous composition with minimum impurities, whereas those of I‐type Naegi granite in the non‐metamorphic Sanyo Belt are enriched in Hf, Y, REE, Th and U along the crystal rims. Similar enrichment has been observed in a variety of zircon called Naegite. These minor components are concentrated in the F‐rich fluid phase of residual melts of the Naegi granite magma, and are crystallized in pegmatites during the latest magmatic stage. High values of Nb and Ta in some Naegite reported previously are attributed to micro‐inclusion of fergusonite.
Valuation of investment projects by an international oil company: a new proof of a straightforward, rigorous method
Authors: Pierru Axel , Babusiaux Denis
Published: November 2008

The problem studied is that of valuing investment projects of an international oil company subject to tax schemes that vary from one country to another. The existing disparities in the tax treatment of interest paid can lead the firm to seek an optimal allocation of its debt capacity among the various projects. In this context, the generalised ATWACC (After‐Tax Weighted Average Cost of Capital) method presents numerous advantages over standard methods and is particularly well suited to the valuation of oil‐field development projects where debt financing differs from the amount that would correspond to the debt ratio targeted by the firm at the corporate scale. In this paper, we discuss adapting the generalised ATWACC method to the specificities of the oil industry and offer new proof of its validity based on a model that maximises, under constraints, the firm's equity value.
Gasoline subsidy and consumer surplus in the Islamic Republic of Iran
Authors: Shahmoradi Asghar , Honarvar Afshin
Published: November 2008

Gasoline subsidy in Islamic Republic of Iran is a controversial issue. While a group of politicians believe that its merits outweigh its costs, some economists believe that its harms exceed the benefits. A new approach is taken to study the changes in social welfare because of gasoline subsidies for the period 1987–2005. The findings indicate that the consumers’ surplus has declined over time for a representative consumer. A large population growth, inflation and non‐substitutability of gasoline with other goods might have caused this phenomenon.
The benefits of allogeneic erythrocyte transfusion: what evidence do we have?
Authors: SONI NEIL , THOMAS BENJAMIN
Published: November 2008

Restrictive blood transfusion practice has modified the indications for blood transfusion. There is still a need for succinct definition of transfusion thresholds in different situations, based on physiological argument balancing the mechanisms by which blood is potentially beneficial against the deleterious effects of transfusion, whether known, speculative or unknown. The latter still need identification. The key physiological benefit is through oxygen delivery and thereby the provision of a margin of safety in tissue oxygenation. This can be achieved by a range of methods that safeguard blood volume, conserve blood or increase hemoglobin as well as by transfusion, and in many situations conservation methods can or could now preclude transfusion. There are still acute and less controlled or controllable situations where conservation methods are difficult to implement or may need to be complemented by transfusion. These are the indications that still need clarification. Difficult and confusing areas of practice include the management of patients with ischemic heart disease. This is a potential driver for transfusion to prevent ischemia, but clarity of efficacy or detriment is elusive beyond acknowledging that both too high and too low hemoglobin values are detrimental. The issue in all clinical situations, whether acute or chronic, is to continue to reevaluate the safety of current thresholds. This will help limit blood usage and ensure that blood is used when necessary but not otherwise.
Pathogen inactivation of blood components
Authors: PROWSE CHRIS
Published: November 2008

Blood donations are screened for infectious agents of concern, but this approach is always challenged when a new infection is identified. Ideally, each donation or blood component would be treated to inactivate pathogens, as is now done for fractionated plasma products. Technology that allows this is now being developed for red cell and platelet products, and has been available for some time for whole plasma. For plasma and platelets, clinical trials have been completed and show some loss of potency as a result of treatment to reduce pathogens. Most of the methods developed arte effective against lipid‐enveloped viruses and bacteria but less so for non‐enveloped viruses.

Some European countries have already implemented provision of pathogen‐reduced plasma and are in the process of large‐scale field evaluations of platelet technologies, now that these are licensed (CE marked) in Europe. As yet there is no licensed technology for pathogen reduction of red cells, and no licenses for component pathogen reduction are in place in the USA.

Cost‐effectiveness of pathogen reduction is very poor if one bases assessment only on those pathogens for which mandatory screening is already in place, as the residual risks of infection are already very low. However, if other factors such as emerging infections, bacterial contamination or the risk of transfusion‐related acute lung injury are also included in the evaluation, the economic case becomes more attractive.
MEASURING THE ALLOCATION OF ESKOM'S PRODUCTIVITY DIVIDEND1
Authors: Lawrence Denis A. , Van Der Westhuizen Gert
Published: November 2008

The methodology developed by Lawrence, Diewert and Fox and Lawrence and Richards is used to determine the contribution of productivity and price changes to changes in Eskom's profitability over time. This methodology enables the calculation of the distribution of the benefits of Eskom's productivity improvements – its “productivity dividend”– among the three key stakeholder groups: consumers, input suppliers (including employees) and Eskom's owners. The results of this study show that Eskom passed on substantially more than the benefits from productivity improvements over the 10 years to 2002 to consumers in the form of real price reductions and to labour in the form of higher real wages.
IS THERE EVIDENCE OF A WAGE PENALTY TO FEMALE PART‐TIME EMPLOYMENT IN SOUTH AFRICA?
Authors: Posel Dorrit , Muller Colette
Published: November 2008

In this paper, we investigate female part‐time employment in South Africa. Using household survey data for South Africa from 1995 to 2004, we show that women are over‐represented in part‐time employment, and that the growth in part‐time work has been an important feature of the feminisation of the labour force. In contrast to many studies of part‐time work in other countries, however, we find evidence of a significant wage premium to female part‐time employment. The premium is also robust to fixed effects estimations using Labour Force Survey panel data from 2001 to 2004, where controlling for unobservable differences increases its size. The premium persists with different hourly thresholds defining part‐time employment and when we account for possible reporting errors in hours worked.
DOMESTIC AND INTERNATIONAL INNOVATION PARTNERSHIPS: DO THEY MATTER FOR INNOVATION OUTCOMES OF SOUTH AFRICAN FIRMS?
Authors: Bakker René m. , Oerlemans Leon A.g. , Pretorius Tinus
Published: November 2008

This paper studies the impact of the diversity of domestic and international innovation partnerships on the innovation outcomes of South African firms. A number of competing hypotheses are formulated and tested empirically using a sample of South African firms in manufacturing and services by applying Ordinary Least Squares regression analyses. Results show that having an innovation partnership, particularly an international partnership, is beneficial to innovation outcomes. However, it also emerges that too diverse a set of international partnerships is detrimental to innovation outcomes. The paper concludes with a discussion and a number of proposals for future research.
FISCAL ILLUSION AT THE LOCAL SPHERE: AN EMPIRICAL TEST OF THE FLYPAPER EFFECT USING SOUTH AFRICAN MUNICIPAL DATA1
Authors: Amusa Hammed , Mabunda Robert , Mabugu Ramos
Published: November 2008

While South Africa operates a relatively decentralised governance and administrative structure, an important feature of the country's intergovernmental fiscal relations system is the gap that exists between the expenditure responsibilities of sub‐national authorities and their assigned revenue bases. The resulting vertical fiscal imbalance is mainly addressedviasignificant intergovernmental transfers to provinces and local governments. This factor presents stronga priorigrounds for assuming that in the South African context, the heavy dependence of many local governments on intergovernmental transfers may generate fiscal illusion. Despite this, there have not been many empirical studies of fiscal illusion in South Africa's intergovernmental transfer system. This paper extends existing literature on fiscal illusion by using the fiscal year 2005/06 financial and expenditure data from 237 local government authorities in South Africa to evaluate the flypaper variant of the fiscal illusion hypothesis. Empirical results indicate that the marginal effects of municipal own‐source revenues on local expenditure exceed those of intergovernmental transfers. No statistical evidence in support of the flypaper hypothesis within the context of municipal expenditures in South Africa is found.
Aerodynamic Instability and Life Limiting Effects of Inlet and Interstage Water Injection Into Gas Turbines
Authors: Brun Klaus , Kurz Rainer , Simmons Harold R.
Published: November 2008

Gas turbine power enhancement technologies such as inlet fogging, interstage water injection, saturation cooling, inlet chillers, and combustor injection are being employed by end-users without evaluating the potentially negative effects these devices may have on the operational integrity of the gas turbine. Particularly, the effect of these add-on devices, off-design operating conditions, non-standard fuels, and compressor degradation/fouling on the gas turbine’s axial compressor surge margin and aerodynamic stability is often overlooked. Nonetheless, compressor aerodynamic instabilities caused by these factors can be directly linked to blade high-cycle fatigue and subsequent catastrophic gas turbine failure; i.e., a careful analysis should always proceed the application of power enhancement devices, especially if the gas turbine is operated at extreme conditions, uses older internal parts that are degraded and weakened, or uses non-standard fuels. This paper discusses a simplified method to evaluate the principal factors that affect the aerodynamic stability of a single shaft gas turbine’s axial compressor. As an example, the method is applied to a frame type gas turbine and results are presented. These results show that inlet cooling alone will not cause gas turbine aerodynamic instabilities but that it can be a contributing factor if for other reasons the machine’s surge margin is already slim. The approach described herein can be employed to identify high-risk applications and bound the gas turbine operating regions to limit the risk of blade life reducing aerodynamic instability and potential catastrophic failure.
Axial Compressor Performance Maintenance
Authors: Levine Philip , Angello Leonard
Published: November 2008

Methods of compressor performance maintenance for large utility combustion turbines continue to evolve. On-line water wash systems used to recover performance loss due to fouling are evolving that use less water. This paper derives a water wash model based on a thin film of water covering the airfoil surfaces. The economic potential for recovering “unrecoverable” losses due to increased roughness and erosion is evaluated. As an outage is needed to remove the compressor cover and perform the maintenance, the approach is to identify the most beneficial maintenance actions and an optimal maintenance interval.
A Generalized Procedure to Estimate Matching of Power Turbine With Aeroderivative Gas Generator at High Speed Settings
Authors: Haq Inam U.
Published: November 2008

This paper encapsulates generalized considerations of power turbine matching with aeroderivative gas generator at high power settings. A computation route is set up to estimate the magnitude of the desired parameters from design point knowledge of a gas generator. Then, a method is delineated to verify matching of power turbine inlet nozzle area with exhaust of gas generator by measuring tangible tested parameters. Data manipulation revealed that there exists a favorable correlation between pressure ratio of high pressure turbine and gas generator speed that may directly reflect the influence of physical area change of power turbine inlet nozzle area. A practical example is presented to demonstrate the procedure. From engine design to retirement, the generalized considerations may be applied on several occasions where question of matching may become important and require explanation for performance and financial justifications. Some generalized rules of matching are condensed and their applications are suggested.
Prototype Development of a Novel Radial Flow Gas Turbine
Authors: Brun Klaus , McKee Robert J. , Moore Jeff , Gernentz Ryan S. , Hollingsworth Justin R. , Smalley Anthony J.
Published: November 2008

A prototype of a novel gas turbine concept is being developed to demonstrate the technical feasibility of a gas turbine design based on a straight radial flow with no axial flow turning. The prototype gas turbine consists of only two structural elements — a rotor disk and a stator shroud. The rotor consists of a centrifugal compressor and high impulse radial outward-flow turbine connected to an electric generator. The stator shroud contains the combustor and nozzles. The difference between this novel design and conventional radial gas turbine is that the compressor and turbine section are installed on the same side of the rotating wheel, while the combustor and nozzle are mounted on the stationary shroud. Thus, the entire assembly consists of two components. Technical advantages are: • Single Rotating Disk; • Compact Two-Piece Construction; • Ease of Repair and Maintenance; • High Power to Weight Ratio. This paper discusses the test set-up, instrumentation, and initial mechanical testing of the radial gas turbine. Performance predictions, rotordynamics analysis, and aerodynamic component verification are also discussed.
Artificial Intelligence for the Diagnostics of Gas Turbines: Part II — Neuro-Fuzzy Approach
Authors: Bettocchi R. , Pinelli M. , Spina P. R. , Venturini M.
Published: November 2008

In the paper, Neuro-Fuzzy Systems (NFSs) for gas turbine diagnostics are studied and developed. The same procedure used previously for the set up of Neural Network (NN) models was used. In particular, the same database of patterns was used for both training and testing the NFSs. This database was obtained by running a Cycle Program, calibrated on a 255 MW single shaft gas turbine working in the ENEL combined cycle power plant of La Spezia (Italy). The database contains the variations of the Health Indices (which are the characteristic parameters that are indices of gas turbine health state, such as efficiencies and characteristic flow passage areas of compressor and turbine) and the corresponding variations of the measured quantities with respect to the values in new and clean conditions. The analyses carried out are aimed at the selection of the most appropriate NFS structure for gas turbine diagnostics, in terms of computational time of the NFS training phase, accuracy and robustness towards measurement uncertainty during simulations. In particular, Adaptive Neuro-Fuzzy Inference System (ANFIS) architectures were considered and tested, and their performance was compared to that obtainable by using the NN models. An analysis was also performed in order to identify the most significant ANFIS inputs. The results obtained show that ANFISs are robust with respect to measurement uncertainty, and, in all the cases analyzed, the performance (in terms of accuracy during simulations and time spent for the training phase) proved to be better than that obtainable by MIMO and MISO Neural Networks trained and tested on the same data.
Arrangement and Optimisation Turbocompressors in an Off-Shore Natural Gas Extraction Station
Authors: Pinelli M. , Mazzi A. , Russo G.
Published: November 2008

In this paper, a methodology for the optimization of a single off-shore gas compression station is developed. The station is composed of three gas turbines, each one driving a centrifugal compressor. The study concerns the feasibility of the most suitable arrangement to face the depletion of wells and the consequent reduction of the head top pressure. Once the arrangement is chosen, an optimization procedure is developed and carried out. The procedure, which is aimed at obtaining either high production rates or good station efficiency, is based on knowledge of the centrifugal compressor characteristics and on the availability of gas turbine thermodynamic cycle program, the latter allowing the definition of the machine actual operating state.
Conceptual Engine Design Study for a 400kWe ICR Turbogenerator
Authors: Rodgers C.
Published: November 2008

The thermodynamic performance and relative sizing of an intercooled recuperative (ICR) cycle turbine engine, for a 400 kWe turbogenerator with a thermal efficiency goal of 40% was studied. The study encompassed four candidate ICR engine flowpath configurations comprising of single shaft and two spools designs with the various methods of power output extraction. The study confirmed that the basic attributes of the ICR cycle are higher specific power, kWe/kgs inlet flow, and a high thermal efficiency characteristic. The major challenge to attaining a turbogenerator thermal efficiency of 40% is inexorably linked with the ability to operate at turbine inlet temperatures of the order 1100C, together with high compressor and turbine efficiencies. This is perceived attainable without internal blade cooling, or ceramic materials by adopting an externally cooled high tip speed radial turbine to drive the high pressure spool of a conceptually simplified ICR turbogenerator. The conceptual engine flowpath would comprise two separate non-concentric spools, wherein the low pressure “supercharging” spool might feasibly be an existing variable turbine nozzle turbocharger.
Thermomechanical Analysis of a Turbocharger Based on Conjugate Heat Transfer
Authors: Heuer Tom , Engels Bertold , Wollscheid Patrick
Published: November 2008

One of the most challenging tasks in designing a turbocharger is to guarantee a sufficient lifetime. Turbine housings are critical parts due to their very complex geometry and consequently complicated temperature and stress distributions. Therefore, high thermal loads as well as thermo-mechanical fatigue have to be considered. Calculating the thermal stress distribution in the turbine housing, steady state and transient, can indicate the regions of crack initiation. From this information selective design improvements can be deduced to increase the component lifetime. But the quality of the stress analysis is strongly dependent on a reliable temperature distribution. Taking into account the interdependency of heat transfer between solid walls and fluid, conjugate heat transfer (CHT) calculations can provide temperature data of high accuracy. Since a transient CHT-calculation is still beyond state of the art, a new approach has been developed. Two steady state CHT-calculations serve to determine heat transfer coefficients at engine brake and full load. Beginning with the engine brake temperature distribution, it is assumed that the gas temperature and the mass flow change immediately. Therefore heat transfer coefficients at full load serve as a boundary condition for a subsequent transient solid body calculation simulating the acceleration process. For the deceleration process the full load temperature field is combined with the engine brake heat transfer coefficients. Monitor points give information about the steepest temperature gradients in the material. At discrete time points a steady state stress analysis has to be performed to detect the regions of highest loads. This subsequent step is essential because in a complex geometry like in a spiral housing with a divider and regionally different wall thicknesses, the stress maxima are not necessarily located at the same places as the temperature peaks. For the two steady state CHT-calculations the turbine wheel has been included in order to consider a realistic flow field. Compared to a transient calculation the degree of abstraction is as low as possible because the assumed frozen rotor boundary condition takes into account centrifugal and coriolis forces. This paper demonstrates the calculation procedure considering a twin-entry turbine housing with an integrated manifold designed for a truck application. The computational results are in excellent agreement with thermal shock test data. A second loop with an improved design proves the success of the method.
The Nature of NOx Formation Within an Industrial Gas Turbine Dry Low Emission Combustor
Authors: Syed Khawar J. , Buchanan Eoghan
Published: November 2008

The NOx formation within a practical lean premixed gas turbine combustor concept has been investigated. The effects of chemical kinetics and fuel/air mixing have been isolated, by adopting an approach, which combines high pressure combustion testing, CFD and chemical reactor modelling. Given the complexities of the underlying fluid dynamic and chemical processes and their interactions, consistency has been sought between experimental and numerical approaches, prior to drawing any conclusions. Two variants of Siemens Industrial Turbomachinery’s dry low emissions combustor have been investigated, one exhibiting near-ideally premixed combustion over a wide range of combustor pressure drop. Perfectly Stirred Reactor analysis, utilising the GRI 3.0 NOx mechanism, shows that NOx formation is dominated by the N2O and Zeldovich routes, with the N2O route being the larger at flame temperatures below 1800–1900K, for systems operating at 14bars, 400°C inlet temperature and at residence times of interest. Other reactions involving H-N-O chemistry are also significant, however the C-H-N-O chemistry has a negligible impact.
URANS Prediction of Flow Instabilities of a Novel Atomizer Combustor Configuration
Authors: Jochmann P. , Sinigersky A. , Koch R. , Bauer H.-J.
Published: November 2008

In this paper, the flow in a gas-turbine combustor with a novel air blast atomizer configuration is studied by URANS (unsteady Reynolds-averaged Navier-Stokes) calculations and compared to experimental data. The flow is characterized by a Reynolds number of 52000, a swirl number of 0.52 and an expansion ratio of 5. It is well known that at this high swirl level, flows exhibit a vortex breakdown which is characterized by a sudden axial deceleration in combination with a radial expansion and the formation of a stagnation point followed by a recirculation zone. At high Reynolds numbers, like in the present case, the vortex breakdown is either of a quasi-axisymmetric bubble type or of a precessing spiral type. Previous experimental studies confirmed the presence of a spiral type vortex breakdown for the configuration under concern. For the non-reacting flow, the structure as well as the frequency of the precessing vortex core is captured almost perfectly by the URANS predictions which is demonstrated by a direct comparison to LDV (Laser-Doppler Velocimetry) measurements. However, it was found that a suitable discretization as well as full three-dimensional computations are crucial in order to successfully predict the precessing spiral structure. In this context also the impact of two-equation and full transport Reynolds-stress turbulence models is discussed. After validation of the URANS method, it has been applied for developing improved designs which aim to suppress the unsteady flow pattern. The investigation of different design variants revealed that, if the mean axial velocity distribution of the flow upstream of the stagnation point is jet-like, the flow is more stable and less susceptible to the spiral type vortex breakdown. This fact which is known from laminar vortex breakdown investigations seems to be also valid for the turbulent mean flow and can be used as a design guideline for achieving a stable nearly symmetric bubble-like recirculation zone.