bluuebunny/crossref_metadata_2025 huggingface dataset:
The Citation Relationships between Journals of Geography and Cognate Disciplines
Authors: LAFFAN SHAWN W.
Published: December 2009

There is an ongoing debate concerning the relationship between the disciplinary ends of the broad spectrum that is geography and also the relationship between geography and other disciplines, including the extent to which it is self‐focussed or inward looking. These issues were assessed using an analysis of citation relationships between journals in the Thompson Scientific Journal Citation Reports databases at the category level. Thirty‐four categories were used, comparing the two geography categories (‘Geography’, representing human geography and ‘Geography, Physical’, representing physical geography) with 32 other cognate categories. A matrix of the citation relationships between each category was developed using a relatedness factor that corrects for the opportunity for citations to occur. The resultant matrix of factors indicates that human geography journals are considerably more likely to cite their own papers than are those of physical geography, but that they are by no means the most self‐citing of the journals assessed. Both human and physical geography journals have strong citation relationships with several other disciplines, with those for human geography most often being net export relationships in the sense of a balance of trade. This finding contradicts previous assertions that human geography imports more than it exports. The citation relationships of physical geography are smaller than those of human geography, and are typically small net imports. The relationship between human and physical geography journals is a small net export from physical geography to human geography, but their total trade volume is considerably smaller than their respective relationships with other disciplines. These results are likely to be caused by many factors in addition to the actual relatedness between disciplines and sub‐disciplines, but they do represent a benchmark against which more detailed analyses can be assessed.
Unpacking Social Exclusion in Western Sydney: Exploring the Role of Place and Tenure
Authors: RANDOLPH B. , RUMING K.J. , MURRAY D.
Published: December 2009

Over the past decade social exclusion has increasingly been positioned at the forefront of political, academic and lay discourse as the cause of disadvantage. While the definition, measurement and solutions to social exclusion remain open to debate, housing has progressively been positioned as a central variable creating neighbourhoods of exclusion. Much of this debate has positioned areas of public housing as being the most disadvantaged and socially excluded neighbourhoods. However, the multidimensionality of social exclusion brings into question the simple identification of areas of public housing as being the most excluded. By exploring six dimensions of exclusion (neighbourhood, social and civic engagement, access, crime and security, community identity and economic disadvantage) we explore the differences between areas dominated by public housing and those characterised by private market housing in terms of their scores on each of these individual dimensions of exclusion. We find that it is the experience of households with multiple dimensions of exclusion, especially locational and economic disadvantage, that differentiate areas of public housing from private housing locations.
The Historical Geographies of Showing Livestock: a Case Study of the Perth Royal Show, Western Australia
Authors: YARWOOD RICHARD , TONTS MATTHEW , JONES ROY
Published: December 2009

This paper examines changes in the entries of livestock to competitions at the Perth Royal Show in the course of the twentieth century. It identifies trends in the showing of animals at the Show and explains these with reference to the wider geographies of state and national agricultural change in Western Australia (WA). In doing so, it provides a longitudinal perspective on the socioeconomic contexts of farming in WA and identifies some of the key cultural and economic drivers that have influenced livestock farming in that locality. In turn, these findings contribute to wider understandings of the global countryside and of the imagined ruralities that exist within and beyond the spaces of showgrounds.
Divergent Regional Trajectories in Australia's Tropical Savannas: Indicators of a Multifunctional Rural Transition
Authors: HOLMES JOHN
Published: December 2009

As elsewhere in affluent, western nations, Australia's tropical savanna zone is experiencing a complex transition towards multifunctional occupance in which emerging consumption, protection and Indigenous values are contesting the former dominance of production values, tied to extensive pastoral occupance and agricultural development projects. This transition is contributing to increased complexity and diversity within and between regions. Divergent regional functional trajectories, evident over the three decades from 1976 to 2006, can be identified and depicted within the triangular relativities between production, consumption and protection values. Core pastoral regions have experienced discernible, if variable, functional trajectories while retaining a modified productivist orientation. In marginal, ‘frontier’ regions limited scope for capital accumulation has created an expansive space for both market and non‐market interests and ideologies to propel functional transitions towards more complex, contested occupance modes. Lack of success in pursuit of productivist goals enhances capability in satisfying emerging national aspirations in recognising Indigenous land rights, in preserving unique biota and valued semi‐natural landscapes, in fostering sustainable resource use and in promoting distinctive styles of tourism and recreation. The Darwin region has experienced a transition towards urban amenity occupance shaped by consumption and protection values. Tenure changes recognising Aboriginal ownership in the Arnhem region have facilitated regionwide self‐managed Indigenous occupance. Divergent regional functional trajectories are starkly revealed in a comparison of driving forces, decision processes and functional trajectories between the Barkly Tableland and the adjoining Gulf Country.
Impact of Background on Color Performance of False Clownfish, Amphiprion ocellaris, Cuvier
Authors: Yasir Inayah , Qin Jian G.
Published: December 2009

Color performance of false clownfish, Amphiprion ocellaris, Cuvier was first examined at four color backgrounds (blue, green red, and white) for 4 wk, then all fish were transferred to a white background for another 4 wk to test whether the impact of background colors on fish skin could have a lasting effect when the environment colors are changed. The experiment was conducted in 10‐L rectangular plastic buckets with three replicates. Thirty fish were stocked in each bucket and three fish were randomly sampled from each tank in Weeks 1, 4, and 8. The color hue, saturation, and brightness were quantified using image analysis. In addition to the whole body analysis, each fish image was divided into ventral and dorsal parts to examine the body position‐dependent response. Furthermore, color differences among the dorsal fin, anal fin, ventral fin, and caudal fin were also quantified. Blue or green background enhanced red orange color on fish skin, whereas white background made fish color brighter. Irrespective of background color, the dorsal side of fish exhibited more red orange, but the color was less bright and less saturated than that of ventral side. Upper fins (dorsal and caudal fins) were more red orange in a blue background than in a white background. Transferring fish from colored backgrounds to a white background made the fish skin and fins brighter, the color of ventral body and ventral fins less saturated, and the bottom fins more yellow orange. The results indicate that blue or green background could strengthen the orange color, whereas white background made fish color less saturated but brighter. The impact of background on the performance of fish color is temporary and likely to disappear when environmental color changes.
Formulated Feed Supports Weight Gain and Survivorship in Juvenile Sea Urchins Lytechinus variegatus
Authors: Taylor Anna M. , Powell Mickie L. , Watts Stephen A. , Lawrence Addison L.
Published: December 2009

In adult sea urchins, formulated feeds can support both weight gain and gonad production; however, studies demonstrating the effects of formulated feeds on juvenile sea urchin growth are limited. In this study, juvenile sea urchins (test diameter: 3.20–7.33 mm, N = 12 per treatment) were reared individually in artificial seawater and fed with one of four experimental feeds: (1) mixed‐taxa algal biofilm (MTAB), (2) freeze‐dried MTAB, (3) a commercial, small‐mammal feed (Friskies® cat treats), or (4) a semipurified feed formulated for sea urchins. The MTAB and sea urchin feed supported weight gain and survival throughout the study; however, those individuals fed with the sea urchin feed exhibited a short lag period at the onset of feeding. This short lag period may be, in part, because of an initial lack of attraction of the urchins to the formulated feed. Furthermore, we hypothesize that gut physiology or gut flora must acclimatize to a new diet (all sea urchins were reared initially on the MTAB diet). The freeze‐dried MTAB and mammal feed did not support substantial weight gain. This study suggests that sea urchin juveniles as small as 3–4 mm can utilize formulated feeds for growth.
The Impact of B‐type Natriuretic Peptide, New York Heart Association Classification and Depression on Quality of Life in Nonhospitalized Heart Failure Patients
Authors: Ancheta Irma B. , Battie Cynthia , Cobb Sarah , Ancheta Christine , Miller Alan , Chiong Jun R.
Published: December 2009

Healthcare providers should be concerned with improving the quality of life (QOL) of patients with heart failure (HF) because disease‐specific QOL is linked to disease progression. The present study investigated the significance of elevated b‐type natriuretic peptide (BNP), NYHA classification and depression to HF‐related QOL to develop better management strategies. Outpatient subjects with left ventricular systolic dysfunction (n=108; mean age=64.9±12) completed the self‐administered Minnesota Living with Heart Failure questionnaire and the Center for Epidemiologic Studies Depression Scale. Functional status was measured using the New York Heart Association Classification (NYHA) and BNP concentrations were measured in plasma samples. Multiregression analysis determined that plasma BNP levels did not contribute significantly to the total QOL score while depression (r=0.63, t ratio=7.43, P<.0001) and NHYA class (r=0.47, t ratio=3.31, P<.001) were significant contributors. NYHA III subjects exhibited worse depression scores (II 15±7 and III: 22±10, P<.001) and elevated plasma BNP (II: 2.0±0.5 and III: 2.4±0.6, P<.001). Low‐cost psychological assessments are recommended to evaluate depression and suggest that those HF patients with NYHA III be closely monitored for depression and reduced QOL.
Lipoprotein‐Associated Phospholipase A2: A Promising Vascular‐Specific Marker for Screening Cardiovascular Risk?
Authors: Lee Joung Hee , Engler Marguerite M.
Published: December 2009

Atherosclerosis is an inflammatory disease that can be assessed by circulating biomarkers. Lipoprotein‐associated phospholipase A2 (Lp‐PLA2) is an enzyme produced in atherosclerotic plaque and is bound to low density lipoprotein and high‐density lipoprotein cholesterol. It has a role in the pathogenesis of atherosclerosis by promoting vascular inflammation. It is emerging as a vascular‐specific marker and predictor of risk for cardiovascular disease (CVD) events. Increasing evidence from many prospective epidemiologic studies have shown that elevated levels of Lp‐PLA2 are associated with future CVD events. Measurement of Lp‐PLA2 in individuals may provide clinically relevant information about their future risk of CVD events. Pharmacologic therapies and/or risk factor modification could be initiated after identification of individuals at risk for CVD. This review provides an overview of the pathophysiology, epidemiologic evidence, and clinical utility of Lp‐PLA2.
Use and exchange of genetic resources of Nile tilapia (Oreochromis niloticus)
Authors: Eknath Ambekar E. , Hulata Gideon
Published: December 2009

The worldwide use of Nile tilapia (Oreochromis niloticus Linnaeus, 1758) in aquaculture represents a somewhat unique scenario. The natural distributions and global genetic resources of tilapias are in Africa, yet the main centers of utilization for aquaculture are primarily in Asia. Within a few decades, Nile tilapia graduated from being an ‘orphan commodity’ (i.e. of interest to only resource‐poor fish farmers) to a globally traded commodity. Most aquaculture production of Nile tilapia in Asia and elsewhere has relied on a narrow genetic base. The natural genetic resources have not yet been fully documented and tapped for use in aquaculture, and many natural populations are under severe threat of irreversible change or loss. Although genetic improvement is now well underway, an important question is how the wealth of Nile tilapia wild genetic resources shall be used for the benefit of a wide range of users, at present outside Africa. This review focuses on documenting the status of Nile tilapia genetic resources (including the potential threats), providing a case for their conservation and for the judicious utilization of genetic diversity for the benefit of all stakeholders; and on analysis of the lessons learnt from a major Nile tilapia genetic improvement initiative, the genetic improvement of farmed tilapia (GIFT) project. Information about other genetic improvement efforts by means of hybridization, sex reversal and YY male technology is also presented.
Detection of Coxiella burnetii by Nested PCR in Bulk Milk Samples from Dairy Bovine, Ovine, and Caprine Herds in Iran
Authors: Rahimi E. , Doosti A. , Ameri M. , Kabiri E. , Sharifian B.
Published: December 2009

The epidemiology of Q‐fever in Iran is essentially unknown. This study was conducted to determine the prevalence rate of Coxiella burnetii in bulk milk samples from dairy bovine, ovine, and caprine herds in Chaharmahal va Bakhtiari province, Iran. In this study, 376 bulk milk samples from 79 dairy bovine, ovine, and caprine herds were tested for C. burnetii using a nested PCR assay. The animals whose milk samples collected for this study were clinically healthy. In total, 13 of 210 (6.2%) bovine milk samples were positive; the positive samples originated from 5 of 28 (17.9%) commercial dairy herds. All 110 ovine bulk milk samples from 31 sheep breeding farms were negative and only 1 of 56 (1.8%) caprine bulk milk samples from 20 goat breeding farms was positive for C. burnetii. Although no extensive prevalence study was undertaken, the results of this study indicate that clinically healthy cattle are important sources of C. burnetii infection in Iran. To our knowledge, this study is the first report of direct identification of C. burnetii by PCR in bulk milk samples from dairy bovine and caprine herds in Iran. Further intensive prevalence studies on Coxiella infection among farmers, milk‐processing workers, veterinarians, and slaughterhouse workers and on possible dangers of dairy products will be needed to elucidate the epidemiology of Q fever in Iran.
Produit eulérien motivique et courbes rationnelles sur les variétés toriques
Authors: Bourqui David
Published: December 2009

We study the asymptotical behaviour of the moduli space of morphisms of given anticanonical degree from a rational curve to a split toric variety, when the degree goes to infinity. We obtain in this case a geometric analogue of Manin’s conjecture about rational points of bounded height on varieties defined over a global field. The study is led through a generating series whose coefficients lie in a Grothendieck ring of motives, the motivic height zeta function. In order to establish convergence properties of this function, we use a notion of motivic Euler product. It relies on a construction of Denef and Loeser which associates a virtual motive to a first order logic ring formula.
Design Option of Heat Exchanger for the Next Generation Nuclear Plant
Authors: Oh Chang H. , Kim Eung S. , Patterson Mike
Published: December 2009

The next generation nuclear plant (NGNP), a very high temperature gas-cooled reactor (VHTR) concept, will provide the first demonstration of a closed-loop Brayton cycle at a commercial scale, producing a few hundred megawatts of power in the form of electricity and hydrogen. The power conversion unit for the NGNP will take advantage of the significantly higher reactor outlet temperatures of the VHTRs to provide higher efficiencies than can be achieved with the current generation of light water reactors. Besides demonstrating a system design that can be used directly for subsequent commercial deployment, the NGNP will demonstrate key technology elements that can be used in subsequent advanced power conversion systems for other Generation IV reactors. In anticipation of the design, development, and procurement of an advanced power conversion system for the NGNP, the system integration of the NGNP and hydrogen plant was initiated to identify the important design and technology options that must be considered in evaluating the performance of the proposed NGNP. As part of the system integration of the VHTRs and the hydrogen production plant, the intermediate heat exchanger is used to transfer the process heat from VHTRs to the hydrogen plant. Therefore, the design and configuration of the intermediate heat exchanger are very important. This paper describes analyses of one stage versus two-stage heat exchanger design configurations and simple stress analyses of a printed circuit heat exchanger (PCHE), helical-coil heat exchanger, and shell-and-tube heat exchanger.
An Experimental and Numerical Investigation of Spark Ignition Engine Operation on H2, CO, CH4, and Their Mixtures
Authors: Li Hailin , Karim Ghazi A. , Sohrabi A.
Published: December 2009

The knock and combustion characteristics of CO, H2, CH4, and their mixtures were determined experimentally in a variable compression ratio spark ignition (SI) cooperative fuel research (CFR) engine. The significant effects of gaseous fuel mixtures containing H2 in enhancing the combustion and oxidation process of CH4 were examined. The unique combustion characteristics of CO in dry air and its distinct performance in mixtures with H-containing fuels were investigated. The addition of a simulated synthesis gas (2H2+CO) to CH4 was found to enhance the combustion process of the resulting mixture and lowers its knock resistance. The effectiveness of such an addition is slightly weaker than that of a comparable H2 addition but much stronger than that with CO addition only. A predictive model with detailed kinetic chemistry was used successfully to simulate SI engine operation fuelled with CH4, H2, CO, and their mixtures. The predicted engine performance and knock limits of CH4, H2, CO, and their mixtures agree well with experimental data with the exception around pure CO operation in dry air with the presence of small amounts of CH4 or H2. A remedial approach to improve the prediction of the knock limits of fuel mixtures containing mainly CO with a small amount of H-containing fuels such as H2 and CH4 was proposed and discussed.
Kinetic Study of the Thermo-Oxidative Degradation of Squalane (C30H62) Modeling the Base Oil of Engine Lubricants
Authors: Diaby Moussa , Sablier Michel , Le Negrate Anthony , El Fassi Mehdi
Published: December 2009

On the basis of ongoing research conducted on the clarification of processes responsible for lubricant degradation in the environment of piston grooves in exhaust gas recirculation (EGR) diesel engines, an experimental investigation was aimed to develop a kinetic model, which can be used for the prediction of lubricant oxidative degradation correlated with endurance test conducted on engines. Knowing that base oils are a complex blend of paraffins and naphthenes with a wide range of sizes and structures, their chemistry analysis during the oxidation process can be highly convoluted. In the present work, investigations were carried out with the squalane (C30H62) chosen for its physical and chemical similarities with the lubricant base oils used during the investigations. Thermo-oxidative degradation of this hydrocarbon was conducted at atmospheric pressure in a tubular furnace, while varying temperature and duration of the tests in order to establish an oxidation reaction rate law. The same experimental procedures were applied to squalane doped with two different phenolic antioxidants usually present in engine oil composition: 2,6-di-tert-butyl-4-methylphenol and octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate. Thus, the effect of both antioxidants on the oxidation rate law was investigated. Data analysis of the oxidized samples (Fourier transform infrared spectroscopy and gas chromatography/mass spectrometry) allowed rationalization of the thermo-oxidative degradation of squalane. The resulting kinetic modeling provides a practical analytical tool to follow the thermal degradation processes, which can be used for prediction of base oil hydrocarbon aging. If experiments confirmed the role of phenolic additives as an effective agent to lower oxidation rates, the main results lie in the observation of a threshold temperature where a reversed activity of these additives was observed.
Turbocharger Nonlinear Response With Engine-Induced Excitations: Predictions and Test Data
Authors: San Andrés Luis , Maruyama Ash , Gjika Kostandin , Xia Sherry
Published: December 2009

Turbochargers (TCs) aid to produce smaller and more fuel-efficient passenger vehicle engines with power outputs comparable to those of large displacement engines. This paper presents further progress on the nonlinear dynamic behavior modeling of rotor-radial bearing system by including engine-induced (TC casing) excitations. The application is concerned with a semifloating bearing design commonly used in high speed turbochargers. Predictions from the model are validated against test data collected in an engine-mounted TC unit operating at a top speed of 160 krpm (engine speed=3600 rpm). The bearing model includes noncylindrical lubricant films as in a semifloating-ring bearing with an antirotation button. The nonlinear rotor transient response model presently includes input base motions for the measured TC casing accelerations for increasing engine load conditions. Engines induce TC casing accelerations rich in multiple harmonic frequencies; amplitudes being significant at two and four times the main engine speed. Fast Fourier transfor frequency domain postprocessing of predicted nonlinear TC shaft motions reveals a subsynchronous whirl frequency content in good agreement with test data, in particular, for operation at the highest engine speeds. Predicted total shaft motion is also in good agreement with test data for all engine loads and over the operating TC shaft speed range. The comparisons validate the rotor-bearing model and will aid in reducing product development time and expenditures.
A Novel Coal-Based Hydrogen Production System With Low CO2 Emissions
Authors: Xu Gang , Jin HongGuang , Yang YongPing , Duan Liqiang , Han Wei , Gao Lin
Published: December 2009

In this paper, we have proposed a novel coal-based hydrogen production system with low CO2 emission. In this novel system, a pressure swing adsorption H2 production process and a CO2 cryogenic capture process are well integrated to gain comprehensive performance. In particular, through sequential connection between the pressure swing absorption (PSA) H2 production process and the CO2 capture unit, the CO2 concentration of PSA purge gas that enters the CO2 capture unit can reach as high as 70%, which results in as much as 90% of CO2 to be separated from mixed gas as liquid at a temperature of −55°C. This will reduce the quantity and quality of cold energy required for cryogenic separation method, and the solidification of CO2 is avoided. The adoption of cryogenic energy to capture CO2 enables direct production of liquid CO2 at low pressure and thereby saves a lot of compression energy. Besides, partial recycle of the tail gas from CO2 recovery unit to PSA inlet can help enhance the amount of hydrogen product and lower the energy consumption for H2 production. As a result, the energy consumption for the new system’s hydrogen production is only 196.8 GJ/tH2 with 94% of CO2 captured, which is 9.2% lower than that of the coal-based hydrogen production system with Selexol CO2 removal process and is only 2.6% more than that of the coal-based hydrogen production system without CO2 recovery. More so, the energy consumption of CO2 recovery is expected to be reduced by 20–60% compared with that of traditional CO2 separation processes. Further analysis on the novel system indicates that synergetic integration of the H2 production process and cryogenic CO2 recovery unit, along with the synthetic utilization of energy, plays a significant role in lowering energy penalty for CO2 separation and liquefaction. The promising results obtained here provide a new approach for CO2 removal with low energy penalty.
Advanced Braze Alloys for Fast Epitaxial High-Temperature Brazing of Single-Crystalline Nickel-Base Superalloys
Authors: Laux Britta , Piegert Sebastian , Rösler Joachim
Published: December 2009

High-temperature diffusion brazing is a very important technology for filling cracks in components from single-crystalline nickel-base superalloys as used in aircraft engines and stationary gas turbines: Alloys, which are similar to the base material, are enhanced by a fast diffusing melting-point depressant (MPD) like boron or silicon, which causes solidification by diffusing into the base material. Generally, epitaxial solidification of single-crystalline materials can be achieved by use of conventional braze alloys; however, very long hold times are necessary to provide a complete diffusion of the MPD out of the braze gap. If the temperature is lowered before diffusion is completed, brittle secondary phases precipitate, which serve as nucleation sites for stray grains and, therefore, lead to deteriorating mechanical properties. It was demonstrated in earlier works that nickel-manganese-based braze alloys are appropriate systems for the braze repair of particularly wide gaps in the range of more than 200 μm, which allow a significant shortening of the required hold times. This is caused by the complete solubility of manganese in nickel: Epitaxial solidification can be controlled by cooling in addition to diffusion. In this work, it will be shown that the nickel-manganese-based systems can be enhanced by chromium and aluminum, which is with regard to high-temperature applications, a very important aspect. Furthermore, it will be demonstrated that silicon, which could be identified as appropriate secondary MPD in recent works, can be replaced by titanium as this element has additionally a γ′ stabilizing effect. Several braze alloys containing nickel, manganese, chromium, aluminum, and titanium will be presented. Previously, the influence of the above mentioned elements on the nickel-manganese-based systems will be visualized by thermodynamic simulations. Afterward, different compositions in combination with a heat treatment, which is typical for nickel-base superalloys, will be discussed: A microstructure, which is very similar to that within the base material, can be presented.
Computational Studies of the Unbalance Response of a Whole Aero-Engine Model With Squeeze-Film Bearings
Authors: Bonello Philip , Hai Pham Minh
Published: December 2009

The computation of the unbalance vibration response of aero-engine assemblies fitted with nonlinear bearings requires the retention of a very large number of modes for reliable results. This renders most previously proposed nonlinear solvers unsuitable for this application. This paper presents three methods for the efficient solution of the problem. The first method is the recently developed impulsive receptance method (IRM). The second method is a reformulation of the Newmark-beta method. In addition to these two time-domain methods, a whole-engine receptance harmonic balance method (RHBM) is introduced that allows, for the first time, the frequency domain calculation of the periodic vibration response of a real engine. All three methods use modal data calculated from a one-off analysis of the linear part of the engine at zero speed. Simulations on a realistically-sized representative twin-spool engine model with squeeze-film damper bearings provide evidence that the popular Newmark-beta method can be unreliable for large-order nonlinear systems. The excellent correlation between the IRM and RHBM results demonstrates the efficacy of these two complementary tools in the computational analysis of realistic whole-engine models.
Influence of Blade Deterioration on Compressor and Turbine Performance
Authors: Morini M. , Pinelli M. , Spina P. R. , Venturini M.
Published: December 2009

Gas turbine operating state determination consists of the assessment of the modification due to deterioration and fault of performance and geometric data characterizing machine components. One of the main effects of deterioration and fault is the modification of compressor and turbine performance maps. Since detailed information about actual modification of component maps is usually unavailable, many authors simulate the effects of deterioration and fault by a simple scaling of the map itself. In this paper, stage-by-stage models of the compressor and the turbine are used in order to assess the actual modification of compressor and turbine performance maps due to blade deterioration. The compressor is modeled by using generalized performance curves of each stage matched by means of a stage-stacking procedure. Each turbine stage is instead modeled as two nozzles, a fixed one (stator) and a moving one (rotor). The results obtained by simulating some of the most common causes of blade deterioration (i.e., compressor fouling, compressor mechanical damage, turbine fouling, and turbine erosion), occurring in one or more stages simultaneously, are reported in this paper. Moreover, compressor and turbine maps obtained through the stage-by-stage procedure are compared with the ones obtained by means of map scaling. The results show that the values of the scaling factors depend on the corrected rotational speed and on the load. However, since the variation in the scaling factors in the operating region close to the design corrected rotational speed is small, the use of the scaling factor as health indices can be considered acceptable for gas turbine health state determination at full load. Moreover, also the use of scaled maps in order to represent compressor and turbine behavior in deteriorated conditions close to the design corrected rotational speed can be considered acceptable.
Accurate Representation of the Rail Geometry for Multibody System Applications
Authors: Marquis Brian , Zaazaa Khaled E. , Sinokrot Tariq , Shabana Ahmed A.
Published: December 2009

The objective of this study is to examine the geometric description of the spiral sections of railway track systems, in order to correctly define the relationship between the geometry of the right and left rails. The geometry of the space curves that define the rails are expressed in terms of the geometry of the space curve that defines the track center curve. Industry inputs such as the horizontal curvature, grade, and superelevation are used to define the track centerline space curve in terms of Euler angles. The analysis presented in this study shows that, in the general case of a spiral, the profile frames of the right and left rails that have zero yaw angles with respect to the track frame have different orientations. As a consequence, the longitudinal tangential creep forces acting on the right and left wheels, in the case of zero yaw angle, are not in the same direction. Nonetheless, the orientation difference between the profile frames of the right and left rails can be defined in terms of a single pitch angle. In the case of small bank angle that defines the superelevation of the track, one can show that this angle directly contributes to the track elevation. The results obtained in this study also show that the right and left rail longitudinal tangents can be parallel only in the case of a constant horizontal curvature. Since the spiral is used to connect track segments with different curvatures, the horizontal curvature cannot be assumed constant, and as a consequence, the right and left rail longitudinal tangents cannot be considered parallel in the spiral region. Numerical examples that demonstrate the effect of the errors that result from the assumption that the right and left rails in the spiral sections have the same geometry are presented. The numerical results obtained show that these errors can have a significant effect on the quality of the predicted creep contact forces.
Influence of Imperfect Internal Waves on Long-Range Underwater Acoustic Propagation
Authors: Andreeva T. A. , Durgin W. W. , Wojcik S. E.
Published: December 2009

This work presents a numerical analysis of the effect of random fluctuations of internal waves on the chaotic dynamics of ray trajectories in ocean acoustics. The Eikonal equation is considered in a form of the second order, nonlinear ordinary differential equation. Random phase modulations in the form of zero mean Gaussian white noise are considered for modeling an imperfectly periodic single mode internal wave. It is shown that in the presence of random fluctuations the intersection of acoustic rays with the ocean surface occurs sooner and becomes more frequent than predicted by deterministic ocean models.
On-Line Bleeds Detection in Continuous Casting Processes Using Engineering-Driven Rule-Based Algorithm
Authors: Pan Ershun , Ye Liang , Shi Jianjun , Chang Tzyy-Shuh
Published: December 2009

This paper describes the development of an on-line quality inspection algorithm for detecting the surface defect (“bleeds”) generated in continuous casting processes. The challenges of bleed detection in visual images lie in the low signal-to-noise ratio, the irregularity of bleed contour patterns, and significant false positives. In order to solve these problems, an engineering-driven rule-based detection (ERD) method is proposed. The ERD consists of three detection stages using the pixel features of bleeds, which are transferred from the physical features generated via engineering knowledge. The detailed strategy, ERD algorithm, parameter selection, and casting knowledge are presented. The real case study demonstrates that the developed algorithm is effective and applicable.
High Strain, High Strain Rate Forming of Difficult to Deform Tubular Parts
Authors: Kluz K. , Geskin E. S.
Published: December 2009

High demand for formed tubular components and the necessity to increase their strength to weight ratio have established a need for new, effective, and low cost forming technologies. This work investigates the application of a propellant-driven water stream to the formation of high tensile strength alloys such as stainless steel 321, Inconel 625, and Ti–3Al–2.5V. The proposed forming technology is based on the utilization of high pressure developed in liquid flowing through a tubular work piece. This pressure results from superposition of compression waves generated in the course of the impact of the liquid by products of propellant combustion. An experimental setup, used for the study of the technology in question, consisted of a tubular component, inserted into a split die assembly, and a combustion chamber, which generated gas, driving water through a work piece. This setup was successfully used for high strain, high strain rate forming of tubular components. In particular, the formation of various shapes in the course of an expansion of seamless tubing was examined. Despite large strains, exceeding in some cases the static test elongation limit, the generated samples were characterized by a uniform wall thinning and structural integrity. For example, a 55% expansion of Ti–3Al–2.5V tube was attained using a simple setup. The acquired experimental data show that the technology can be applied to form alloys characterized by high tensile strength, low static elongation limits, and low modulus of elasticity. Simplicity and low capital cost of the process determine its competitiveness in comparison to conventional quasistatic hydroexpansion, hot forming, and high-energy rate explosive forming processes.
Coherent diffraction lithography: Periodic patterns via mask-based interference lithography
Authors: Fucetola Corey P. , Patel Amil A. , Moon Euclid E. , O’Reilly Thomas B. , Smith Henry I.
Published: December 2009

Periodic structures, such as gratings and grids, are required in a variety of applications including spectroscopy, photonic and phononic devices, and as substrates for basic studies in materials science. Interference lithography readily forms periodic patterns in photoresist, but conventional approaches, using a Lloyd’s mirror or Mach–Zehnder configuration, suffer from a number of shortcomings including difficulty in aligning patterns with respect to pre-existing structures on a substrate and difficulty in precisely repeating a given spatial period. Coherent diffraction lithography (CDL), a mask-based approach, utilizes the well-known Talbot effect to accurately replicate the one- or two-dimentional pattern on a mask by reimaging the mask pattern in photoresist. Moreover, with appropriate alignment marks on the mask, one can align the replicated pattern relative to pre-existing patterns on the substrate. The authors describe the design, construction, and utilization of a dedicated CDL apparatus that permits replication, at a well-defined mask-substrate gap, of the periodic structure of a phase mask. The system also incorporates interferometric-spatial-phase imaging for aligning the replicated pattern relative to fixed fiducials on a substrate. They obtained high quality replications of a mask pattern, consisting of a 600 nm period grating, from the 1st to the 52nd plane of reimaging, i.e., from 1.55 to 40.16 μm.
Solid-state dye-sensitized solar cell based on semiconducting nanomaterials
Authors: Lee Tao-Hua , Sun Dazhi , Zhang Xi , Sue Hung-Jue , Cheng Xing
Published: December 2009

A solid-state dye-sensitized solar cell based on semiconducting nanomaterials is introduced. The device consists of a thin film of ZnO nanoparticles that is loaded with light-absorbing dyes. A p-type semiconductor film is then deposited on top of the dye molecules as a hole transport material. Both pristine poly(3-hexylthiophene) (P3HT) and P3HT doped with XD-grade single-walled carbon nanotube (XDSWNT) are used as the p-type semiconducting films. By having a weight ratio of XDSWNT and P3HT equaled to 0.1:1, short-circuit current was quadrupled from 0.12to0.48mA∕cm2 and solar cell efficiency was tripled from 0.023% to 0.07%, compared to devices with pure P3HT as a hole transport material.
Influence of polarization on absorbance modulated subwavelength grating structures
Authors: Foulkes J. E. , Blaikie R. J.
Published: December 2009

The feasibility of using absorbance modulated structures as subwavelength optical transmission gratings was studied using both analytical techniques and finite element method simulations. Particular note was taken of the relevance of this work to absorbance modulation optical lithography (AMOL) and the understanding of the authors of how to control and improve the transmission of light through the photochromic layer. It was found that absorbance gratings share many characteristics with similar-sized metal gratings, in particular, transmitting transverse magnetic (TM) polarized light better than transverse electric polarized light. For both polarizations the transmission through an absorbance grating produces lower contrast intensity profiles compared to both metal and dielectric gratings; however, there was reasonable contrast to a depth of approximately 40 nm beneath the grating in the TM case for gratings with half-pitch as small as 20 nm. Full vector-field AMOL simulations demonstrate similar trends in which there was improved propagation and confinement of TM polarized light at the short resist-exposing wavelength.
Thermal development of a calixarene resist
Authors: Auzelyte V. , Langner A. , Solak H. H.
Published: December 2009

Thermal development of photoresist films in lithography is an interesting alternative to the common wet development technique, which can result in problems such as swelling, line edge roughness, and pattern collapse. The authors investigated thermal development of a nonchemically amplified calixarene type high-resolution electron beam resist. Isolated and dense structures were developed at 250–400 °C in air and in low vacuum conditions. They achieved 25 nm half-pitch dense line/space patterns and 17 nm isolated lines without sacrificing resist resolution, sensitivity, or contrast. The obtained lines were smoother with more than two times smaller line edge roughness. The results demonstrate the feasibility of using thermal development for high-resolution nanolithography.
UV irradiation effect on sol-gel indium tin oxide nanopatterns replicated by room-temperature nanoimprint
Authors: Kang Yuji , Okada Makoto , Nakamatsu Ken-Ichiro , Kanda Kazuhiro , Haruyama Yuichi , Matsui Shinji
Published: December 2009

The authors report the first room-temperature nanoimprint lithography (RT-NIL) process using sol-gel indium tin oxide (ITO) as a replicated material. The spin-coated ITO film has to be annealed over 600°C to obtain a low resistivity. The spin-coated ITO film can be delineated by RT-NIL, but the patterns disappear after annealing at 200°C. To overcome the above problem, they examined UV irradiation effects on a spin-coated ITO film. As a result, they found that the ITO patterns imprinted by RT-NIL stayed the same after being annealed at 600°C for 1h due to 254nm UV irradiation before annealing.
Characterization of pattern-placement error for sub-40-nm memory devices
Authors: Shin Jangho , Cha Dongho , Yeo Jeongho , Kim Hochul , Choi Seong-Woon , Park Chan-Hoon
Published: December 2009

Pattern-placement error (PPE) due to lens aberration is characterized for sub-40-nm memory devices. The amount of PPE depends on the feature size. PPE difference between memory cell and traditional box-in-box or advanced imaging metrology marks of KLA-Tencor Corporation is 4nm in the worst case for a given illumination condition. To avoid this kind of problem, a cell-like segmentation may be applied for alignment and overlay marks. However, the cell-like segmentation could degrade the alignment-signal intensity. In this article, a simple but effective methodology is introduced so that optimum segmentation size is determined. As a result, PPE error of alignment/overlay marks is close to memory cells with enough alignment-signal intensity.
Fabrication of nanoscale ZnO field effect transistors using the functional precursor zinc neodecanoate directly as a negative electron beam lithography resist
Authors: Jones G. A. C. , Xiong G. , Anderson D.
Published: December 2009

The authors demonstrate ZnO based thin-film transistors (TFTs) fabricated using a metal-organic sol-gel solution process with zinc neodecanoate as precursor. The ZnO films were produced by spin coating the precursor solution onto a substrate and subsequently annealing the film in air for 1h at 500°C. Atomic force microscopy and scanning electron microscopy characterizations show that the films consist of particles which have an average size of 45nm and are closely packed. X-ray diffraction measurement reveals that the particles have a hexagonal structure and are randomly orientated. TFT devices were fabricated by patterning 100nm thick aluminum source and drain electrodes on top of the ZnO film using standard optical lithographic processes. The devices exhibit n-channel enhancement mode behavior, with a saturation mobility of 1.16cm2V−1s−1, a drain-current on-to-off ratio of 8.1×107 and a threshold voltage of 16.1V in ambient environment. Zinc neodecanoate may also be used as a negative resist, and electron beam patterning can be introduced after spin coating to directly “write” cross-linked nanowires into the film. Subsequent development removes the unpatterned areas prior to the annealing process at 500°C. This process is capable of forming ZnO nanowires down to ∼10nm width. Field effect transistors based on these ZnO nanowires show similar behavior to the thin film devices, operating as n-channel devices in enhancement mode. The results imply that high-performance ZnO transistor devices can be produced by a simple and low-cost technique which may be applicable to integrated electronic systems.
Lithographically directed surface modification
Authors: Kingsborough Richard P. , Goodman Russell B. , Fedynyshyn Theodore H.
Published: December 2009

The directed assembly of polystyrene-block-poly(methyl methacrylate) films on a variety of photolytically nanopatterned siloxane-modified surfaces was investigated. The amount of siloxane removal is related to the exposure dose of a 157 nm laser. The modified surfaces were imaged using a 157 nm interference exposure system to lithographically define areas of different surface energies to direct the assembly of the diblock copolymer films. The analysis of the surface energy aerial image provided insights into the exposure doses required to result in defect-free films. While the slope of the surface energy aerial image was not found to be important by itself, in concert with the difference in high and low surface energy regions, as well as the maximum value of the low surface energy region, it provided insight into conditions needed to direct self-assembly of the block copolymer films. Preliminary investigations concerning the extension of this methodology to 193 nm showed that the polar surface energy of arylsiloxane-modified surfaces can also be affected by 193 nm exposure.
Design specific variation in via/contact pattern transfer: Full chip analysis
Authors: Choy Jun-Ho , Sukharev Valeriy , Markosian Ara , Kteyan Armen , Granik Yuri , Bliznetsov Vladimir
Published: December 2009

A novel model-based algorithm provides a capability to control full chip design specific variation in pattern transfer caused by via/contact etch processes. This physics-based algorithm is capable of detecting and reporting hot spots based on the fab defined thresholds of acceptable variations in the critical dimension of etched shapes. It can also be used as a tool for etch process optimization to capture the impact of a variety of patterns presented in a particular design. A realistic set of process parameters employed by the developed model allows using this novel via-contact etch electronic design automation tool for the design-aware process optimization in addition to the “standard” process-aware design optimization. Measurements of the postetch geometries of contact holes etched in the organosilicate glass with fluorocarbon plasma (C4F8∕N2∕Ar) are used for model validation and calibration.
Graphitization at interface between amorphous carbon and liquid gallium for fabricating large area graphene sheets
Authors: Fujita Jun-ichi , Ueki Ryuuichi , Miyazawa Yousuke , Ichihashi Toshinari
Published: December 2009

The authors have found that liquid gallium exhibits as a good graphitizing catalyst for a large area graphene sheet. While gallium and carbon are known to be an insoluble system, the authors have found that the catalytic reaction occurs at a very narrow interfacial region between amorphous carbon and liquid gallium. Amorphous carbon film was transformed into graphite layer composed of a few layers of graphene sheet. This thin graphene film can be easily transferred into silicon substrate through the intermediation of poly-dimethyl-siloxane rubber stamping.