bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of the peginterferon‐α 2a and ribavirin plasma levels on viral kinetics and sustained virological response in genotype 1 HCV/HIV‐co‐infected patients with the unfavourable non‐CC IL28B genotypes
Authors: Torres‐Cornejo A. , Ruiz‐Valderas R. , Jimenez‐Jimenez L. , Abad‐Molina C. , Gutierrez‐Valencia A. , Viciana P. , Lopez‐Cortes L. F.
Published: July 2013

Studies on the association between the peginterferon‐α and ribavirin levels and sustained virological response (SVR) have shown yielded conflicting results, but most of them were performed before the influence of IL28B polymorphisms was known. Our aim was to assess the effects of peginterferon‐α 2a and ribavirin plasma levels on viral kinetics and SVR in hepatitis C virus genotype 1 HCV‐1/HIV‐co‐infected patients according to IL28B genotype. This was a cohort study of HCV‐1/HIV‐co‐infected patients who were HCV‐treatment naïve and for whom the efficacy of peginterferon‐α 2a plus ribavirin was evaluated by per‐protocol analysis. The peginterferon‐α 2a and ribavirin levels were measured by ELISA and HPLC‐UV, respectively. The relationships among host and viral factors, the trough drugs levels and virological responses were analysed by multivariate regression analyses. A total of 131 Caucasian patients were included (cirrhosis:38.9%). Overall, SVR rate was 39.6%. In patients with CC IL28B genotype, SVR was related neither to peginterferon‐α 2a nor to ribavirin plasma levels, while higher levels of both drugs were the only variables independently associated with SVR in individuals with CT/TT IL28B genotypes (OR, 5.02; CI95, 1.45–17.1; P = 0.001 and 4.0; CI95, 1.08–14.7; P = 0.038, respectively). Moreover, faster viral declines were observed in CT/TT patients when pegIFN‐α 2a and ribavirin plasma levels were greater than 3400 pg/mL and 1.6 μg/mL, respectively. In contrast to the results for CC patients, the results in patients carrying the unfavourable CT/TT IL28B genotypes showed that plasma levels of both drugs have significant effects on viral kinetics and SVR.
IL28RA polymorphism (rs10903035) is associated with insulin resistance in HIV/HCV‐coinfected patients
Authors: Jiménez‐Sousa M. A. , Berenguer J. , Fernández‐Rodríguez A. , Micheloud D. , Guzmán‐Fulgencio M. , Miralles P. , Pineda‐Tenor D. , García–Álvarez M. , López J. C. , Aldámiz‐Echevarria T. , Carrero A. , Resino S.
Published: July 2013

Hepatitis C virus (HCV) infection is associated with insulin resistance (IR), although mechanisms leading to IR in these patients are not completely understood. The aim of this study was to evaluate the association of interleukin 28B (IL28B) and interleukin 28 receptor alpha (IL28RA) polymorphisms with IR among human immunodeficiency virus (HIV)/HCV‐coinfected patients. We carried out a cross‐sectional study on 203 patients. IL28B (rs8099917) and IL28RA (rs10903035) polymorphisms were genotyped by GoldenGate® assay. IR was defined as homeostatic model assessment (HOMA) values ≥3.00. Univariate and multivariate generalized linear models (GLM) were used to compare HOMA values and the percentage of patients with IR according to IL28B and IL28RA genotypes. In total, 32% (n = 65/203) of the patients had IR. IL28B rs8099917 TT was not significantly associated with HOMA values and IR. In contrast, rs10903035 AA was significantly associated with high HOMA values taking into account all patients (P = 0.024), as well as the subgroups of patients with significant fibrosis (P = 0.047) and infected with HCV genotype 3 (P = 0.024). Additionally, rs10903035 AA was significantly associated with IR (HOMA ≥3.00) in all patients (adjusted odds ratio (aOR) = 2.02; P = 0.034), in patients with significant fibrosis (aOR = 2.86; P = 0.039) and HCV genotype 3 patients (aOR = 4.89; P = 0.031). In conclusions, IL28RA polymorphism (rs10903035) seems to be implicated in the glucose homeostasis because AA genotype increases the likelihood of IR, but this association was different depending on hepatic fibrosis and HCV genotype.
The SpoIIQ landmark protein has different requirements for septal localization and immobilization
Authors: Fredlund Jennifer , Broder Dan , Fleming Tinya , Claussin Clémence , Pogliano Kit
Published: July 2013

Bacillus subtilis sporulation depends on the forespore membrane protein SpoIIQ, which interacts with the mother cell protein SpoIIIAH at the septum to localize other sporulation proteins. It has remained unclear how SpoIIQ localizes. We demonstrate that localization of SpoIIQ is achieved by two pathways: SpoIIIAH and the SpoIID, SpoIIM, SpoIIP engulfment proteins. SpoIIQ shows diffuse localization only in a mutant lacking both pathways. Super‐resolution imaging shows that in the absence of SpoIIIAH, SpoIIQ forms fewer, slightly larger foci than in wild type. Surprisingly, photobleaching experiments demonstrate that, although SpoIIQ localizes without SpoIIIAH, it is no longer immobilized, and is therefore able to exchange subunits within a localized pool. SpoIIQ mobility is further increased by the additional absence of the engulfment proteins. However an enzymatically inactive SpoIID protein immobilizes SpoIIQ even in the absence of SpoIIIAH, indicating that complete septal thinning is not required for SpoIIQ localization. This suggests that SpoIIQ interacts with both SpoIIIAH and the engulfment proteins or their peptidoglycan cleavage products. They further demonstrate that apparently normal localization of a protein without a binding partner can mask dramatic alterations in protein mobility. We speculate that SpoIIQ assembles foci along the path defined by engulfment proteins degrading peptidoglycan.
Heterophoria adaptation during the viewing of 3D stereoscopic stimuli
Authors: Karpicka Edyta , Howarth Peter Alan
Published: July 2013

Purpose

In this experiment two hypotheses were tested. The first hypothesis was that viewing 3D stereoscopic stimuli which are located geometrically beyond the screen on which the images are displayed would induce exophoric heterophoria (phoria) changes (adaptation). The second hypothesis was that participants whose phoria changed as a consequence of adaptation during the viewing of the stereoscopic stimuli would experience less visual discomfort than people whose phoria did not adapt.

Methods

Twenty participants aged between 19 and 45 were recruited to play a computer game in 3D and 2D conditions for 20 min each. Heterophoria was measured before and after viewing the stimuli, and visual discomfort was assessed by questionnaire on both occasions.

Results

Statistically significant changes in heterophoria were found in the 3D conditions (p = 0.007), but not in the 2D conditions (p = 0.16). The difference between the two conditions was statistically significant (p = 0.035). On average, there were also significant differences in visual discomfort between pre and post viewing, for both 2D and 3D conditions, however not everyone reported experiencing discomfort. The sample was then divided into groups, those who had reported an increase in discomfort whilst viewing 3D stimuli, and those who had not. No significant differences in heterophoria, or heterophoria change, were found between these two groups.

Conclusions

The present study has shown that heterophoria can change as a result of viewing 3D stereoscopic stimuli, a change which is similar to prism adaptation. There was appreciable variability in the magnitude of this adaptation between individuals, but there was no correlation between the heterophoria change and visual discomfort.
Atypical antipsychotics in the treatment of delirium
Authors: Wang Hee Ryung , Woo Young Sup , Bahk Won‐Myong
Published: July 2013

The aim of this study was to review the efficacy and safety of atypical antipsychotics, comparing within class, placebo, or compared to another active treatment for delirium. A literature search was conducted using PubMed, EMBASE, and the Cochrane database (1 January 1990–5 November 2012). Selection criteria for review were prospective, controlled studies (comparison studies), using validated delirium rating scales as outcome measures. A total of six prospective, randomized controlled studies were included in the review. It was found that atypical antipsychotics are effective and safe in treating delirium, even though there seemed to be no difference between each agent. In particular, comparison studies with haloperidol showed that the efficacy of atypical antipsychotics was similar to that of low‐dose haloperidol. It was concluded that atypical antipsychotics appear to be effective and tolerable in the management of delirium, even though the evidence is limited.
Zur Rolle der Ökonometrie in der wissenschaftlichen Politikberatung
Authors: Kirchgässner Gebhard
Published: July 2013

Because economic theory alone does in many situations not provide unambiguous policy advice, most of the time empirical analyses are needed in addition. Thus, today econometric analyses are often parts of reports for political institutions or courts. However, it is not unusual that reports with contradicting evidence are presented by different groups or parties. Using the relation between government size and economic growth as an example, it is shown how such contradicting results are possible even if all scientists involved behave sincerely and adhere to the rules of scientific research. Our second example, studies investigating whether the death penalty serves as a deterrent to homicide, shows that the results of empirical analyses might to a large extent depend on a priori convictions of the scientists. Thus, the process of scientific policy advice has to be organised in a way so that - similar to the genuinely scientific discourse - open discussion and criticisms of methods and results are possible. In order to disclose possible conflicts of interests, this demand transparency of the whole process and, in particular for empirical analyses, that data and programmes are made available for re-estimations.
Flexible Work Time in Germany: Do Workers Like It and How Have Employers Exploited It Over the Cycle?
Authors: Hunt Jennifer
Published: July 2013

After describing qualitatively the increasingly flexible organization of work hours in Germany, I turn to the German Socio-Economic Panel to quantify practices and trends, and assess their effects on workers and employers. Measuring flexibility as the extent to which overtime is compensated with time off, and hence receives no overtime premium, I show that hourly-paid workers have undergone a regime shift towards more flexibility since 1984, while salaried workers have maintained an already high level of flexibility. I find weak evidence that flexibility causes workers to be slightly less satisfied with their work and more satisfied with their leisure. Over the boom and bust cycle of 2005-2009, I find that for hourly-paid workers in manufacturing, paid and unpaid overtime hours were equally cyclical, but that the cycle for unpaid overtime led the cycle for paid overtime. The results suggest that while the new practices do free employers to make more cyclical adjustments in hours, they have not eliminated the need for adjustments in paid overtime. I identify as constraints ceilings on cumulated overtime hours to be compensated with time off and the window within which the compensation in time off must occur.
Risk of Very Low Birth Weight Based on Perinatal Periods of Risk
Authors: Demont‐Heinrich Christine M. , Hawkes Allison P. , Ghosh Tista , Beam Rita , Vogt Richard L.
Published: July 2013

Objective

To determine the risk factors associated with having a very low birth weight (VLBW) infant as a follow‐up to the first phase of a Perinatal Periods of Risk approach.

Design and Sample

Retrospective cohort analysis of birth certificates. Population‐based sample of 53,427 birth certificates for the city under study during the years 1999–2006.

Measures

The relationship of selected maternal characteristics as predictors of VLBW using multivariate logistic regression analysis.

Results

The maternal characteristics associated with VLBW were as follows: no prenatal care (OR = 4.04), inadequate weight gain (OR = 3.97), Black, non‐Hispanic race (OR = 1.50), less than 20 years old (OR = 1.42) and more than 35 years old (OR = 1.43). After analyzing age and race/ethnicity together, Black non‐Hispanic women less than 20 years of age (OR = 2.70) or over 35 years of age (OR = 2.45) still had an increased odds for having a VLBW infant whereas Black non‐Hispanic women between the ages of 20 and 35 did not.

Conclusions

The findings of this study suggest educating women on the importance of preconception care, prenatal care, and adequate pregnancy weight gain to reduce the odds of having a VLBW infant.
The Impacts of Technical Barriers to Trade on Different Components of International Trade
Authors: Bao Xiaohua , Chen Wei‐Chih
Published: July 2013

This research studies the impacts of technical barriers to trade (TBT) on trade performance of 103 countries over the period 1995–2008. The paper analyzes how TBT influences the trade probability, trade volume and trade duration. The trade volume is further decomposed into the number of products traded (extensive margin) and the trade value of each product (intensive margin). It is found that TBT imposes inconsistent impacts on the different components of trade, and that the effects differ by country. First, TBT reduces trade probability, but increases the volume and duration of existing trade relationships. Second, the positive effect of TBT on trade volume is mainly driven by an increase in the extensive margin, and the effect on the intensive margin is not statistically significant. Finally, TBT raised by developed countries have a stronger negative impact on trade probability, while TBT implemented by developing countries have a greater positive effect on trade volume.
Religiosity as a Determinant of Happiness
Authors: Gundlach Erich , Opfinger Matthias
Published: July 2013

The empirical relation between happiness and religiosity is considered from the perspective of basic utility theory. An unbalanced cross‐country panel data set is used to study whether religiosity can be considered as a substitute in the happiness function, which itself is held to be a proxy for the utility function. We find that the same level of happiness can be maintained with high and low levels of religiosity as a result of substitution along a standard indifference curve. Our empirical results are consistent with three stylized facts of the empirical literature, namely a positive correlation between happiness and religiosity, a positive correlation between happiness and income, and a negative correlation between religiosity and income.
Environment, Urban Unemployment, and Tariffs in the Harris–Todaro Model
Authors: Nakamura Azusa
Published: July 2013

By incorporating the environment into the Harris–Todaro model, this paper examines how introduction of an import tariff on manufactured goods affects urban unemployment and the environment in a less‐developed country. In the Harris–Todaro model, introduction of an import tariff increases urban unemployment when there is no environmental pollution. In contrast, this paper shows that introduction of a tariff may decrease unemployment if the environment is incorporated into the model. Moreover, it is shown that introduction of a tariff improves the environment.
Water‐Soluble Vitamins in People with Low Glomerular Filtration Rate or On Dialysis: A Review
Authors: Clase Catherine M , Ki Vincent , Holden Rachel M
Published: July 2013

People with low glomerular filtration rate and people on dialysis are spontaneously at risk for vitamin deficiency because of the potential for problems with decreased appetite and decreased sense of smell and taste, leading to decreased intake, and because decreased energy or decreased cognitive ability results in difficulties in shopping and cooking. Imposed dietary restrictions because of their renal dysfunction and because of comorbidities such as hypertension and diabetes exacerbate this problem. Finally, particularly for water‐soluble vitamins, loss may occur into the dialysate. We did not identify any randomized trials of administering daily doses close to the recommended daily allowances of these vitamins. In people who are eating at all, deficiencies of B5 and B7 seem unlikely. It is unclear whether supplements of B2 and B3 are necessary. Because of dialyzability and documented evidence of insufficiency in dialysis patients, B1 supplementation is likely to be helpful. B6, B9, and B12 are implicated in the hyperhomocysteinemia observed in patients on dialysis. These vitamins have been studied in combinations, in high doses, with the hope of reducing cardiovascular outcomes. No reductions in patient‐important outcomes were seen in adequately powered randomized trials. Because of their involvement in the homocysteine pathway, however, supplementation with lower doses, close to the recommended daily allowances, may be helpful. Vitamin C deficiency is common in patients on dialysis who are not taking supplements: low‐dose supplements are warranted. Vitamins for dialysis patients contain most or all of the B vitamins and low‐dose vitamin C. We are not aware of any medical reasons to choose one over another.
Dynamic Tensile Fracture Behaviours of Selected Aluminum Alloys under Various Loading Conditions
Authors: Wang Y. G. , Jiang Z. X. , Wang L. L.
Published: July 2013

Experiments investigating dynamic tensile fracture were performed on the extruded rods of 2024‐T4 and 7075‐T6 aluminum alloys under varying loading conditions. The initial yield stress and fracture strain of 7075‐T6 alloy obtained in spilt Hopkinson tension bar tests are higher than that of 2024‐T4 alloy. But the initiation fracture toughness and spall strength of 2024‐T4 alloy are higher than those of 7075‐T6 alloy in three‐point bending and plate impact experiments, which indicates that 2024‐T4 alloy has better crack initiation tolerance and stronger spall failure resistance. Based on metallurgical investigations by using optical and scanning electron microscopes, it is revealed that the microstructure has a profound effect on the dynamic tensile fracture mechanism of each aluminum alloy. The 2024‐T4 alloy is relatively brittle due to voids or cracks nucleated at many coherent CuMgAl2 precipitate phases in the grain interiors, and the fracture mode is predominantly transgranular. The 7075‐T6 alloy exhibits relatively ductile fracture because voids or cracks growth is partly intergranular along the grain boundaries and partly transgranular by void formation around coarse intermetallic particles. The obvious differences of damage distribution and void coalescence mechanisms for 2024‐T4 and 7075‐T6 alloys under plate impact are also discussed.
Experimental Investigation of Hard Turning Mechanisms by PCBN Tooling Embedded Micro Thin Film Thermocouples
Authors: Li Linwen , Li Bin , Li Xiaochun , Ehmann Kornel F.
Published: July 2013

Temperature-distribution measurements in cutting tools during the machining process are extremely difficult and remain an unresolved problem. In this paper, cutting temperature distributions were measured by thin film thermocouples (TFTCs) embedded into polycrystalline cubic boron nitride (PCBN) cutting inserts in the immediate vicinity of the tool-chip interface. The embedded TFTC array provides temperature measurements with a degree of spatial resolution (100 μm) and dynamic response (150 ns) that is not possible with currently employed methods due to the micro-scale junction size of the TFTCs. Using these measurements during hard turning, steady-state, dynamic, as well as chip morphology and formation process analyses were performed based on the cutting temperature and cutting force variations in the cutting zone. It has been shown that the temperature changes in the cutting zone depend on the shearing band location in the chip and the thermal transfer rate from the heat generation zone to the cutting tool. Furthermore, it became evident that the material flow stress and the shearing bands greatly affect not only the chip formation morphology but also the cutting temperature field distributions in the cutting zone of the cutting insert.
A Review of Engineering Research in Sustainable Manufacturing
Authors: Haapala Karl R. , Zhao Fu , Camelio Jaime , Sutherland John W. , Skerlos Steven J. , Dornfeld David A. , Jawahir I. S. , Clarens Andres F. , Rickli Jeremy L.
Published: July 2013

Sustainable manufacturing requires simultaneous consideration of economic, environmental, and social implications associated with the production and delivery of goods. Fundamentally, sustainable manufacturing relies on descriptive metrics, advanced decision-making, and public policy for implementation, evaluation, and feedback. In this paper, recent research into concepts, methods, and tools for sustainable manufacturing is explored. At the manufacturing process level, engineering research has addressed issues related to planning, development, analysis, and improvement of processes. At a manufacturing systems level, engineering research has addressed challenges relating to facility operation, production planning and scheduling, and supply chain design. Though economically vital, manufacturing processes and systems have retained the negative image of being inefficient, polluting, and dangerous. Industrial and academic researchers are re-imagining manufacturing as a source of innovation to meet society's future needs by undertaking strategic activities focused on sustainable processes and systems. Despite recent developments in decision making and process- and systems-level research, many challenges and opportunities remain. Several of these challenges relevant to manufacturing process and system research, development, implementation, and education are highlighted.
Assembly System Reconfiguration Planning
Authors: Bryan April , Hu S. Jack , Koren Yoram
Published: July 2013

Decreasing product life cycles and reduced product development times have led to a need for new strategies for coping with the rapid rate of product family design changes. In this paper, assembly system reconfiguration planning (ASRP) is introduced as a method for cost effectively designing several generations of assembly systems in order to produce a product family that gradually evolves over time. In the ASRP approach, the possible assembly systems for each generation are first considered and then the sequence of assembly system configurations that minimize the life cycle cost of the process are selected. A nonlinear integer optimization formulation is developed for finding the cost minimizing assembly system reconfiguration plan using the ASRP approach. Dynamic programming and genetic algorithm are used to solve the optimization problem. Simulation results indicate that the ASRP approach leads to the minimum life cycle costs of the assembly system, and the relative cost of reconfiguration and production have an impact on the assembly system reconfiguration plan selected. Comparison of the results of the dynamic program and genetic algorithm indicate that the dynamic program is more computationally efficient for small problems and genetic algorithm is preferred for larger problems.
Analysis of Three-Dimensional Cutting Process With Thin Shear Plane Model
Authors: Shamoto Eiji , Kato Masahiro , Suzuki Norikazu , Hino Rei
Published: July 2013

A new and basic analytical model of three-dimensional cutting is proposed by assuming multiple thin shear planes with either the maximum shear stress or minimum energy principle. The three-dimensional cutting process with an arbitrarily shaped cutting edge in a flat rake face is formulated with simple vector equations in order to understand and quickly simulate the process. The cutting edge and workpiece profile are discretized and expressed by their position vectors. Two equations among three unknown vectors, which show the directions of shear, chip flow, and resultant cutting force, are derived from the geometric relations of velocities and forces. The last vector equation required to solve the three unknown vectors is obtained by applying either the maximum shear stress or minimum energy principle. It is confirmed that the directions and the cutting forces simulated by solving the proposed vector equations agree with experimentally measured data. Furthermore, the developed model is applied to consider the three-dimensional cutting mechanics, i.e., how the chip is formed in the three-dimensional cutting with compressive stress acting between the discrete chips, as an example.
Design, Manufacturing, and Calibration Process of One Piece Lathe Dynamometer for Measurement in Two Axes
Authors: Ateş Ergun , Aztekin Kadir
Published: July 2013

Many pieces in structure of a dynamometer may negatively affect the accuracy of the measurements since each piece may display a different strain and stress depending on its material and construction. A one piece dynamometer has been designed to eliminate these negative effects and to facilitate reliable force measurements. A dynamometer that its dimensions were confirmed following strength calculations was manufactured and calibrated in two different ways. The first one was multipoint calibration method in which certain loads were applied to the dynamometer and strain values corresponding to these loads were matched. The second calibration method was implemented using Kistler dynamometer that its results are accepted to be accurate by everyone and it was based on equivalency of force values resulted from work piece processing and force values resulting from machining work pieces with the same parameters to the manufactured dynamometer. The manufactured dynamometer was capable of measuring cutting forces and feeding forces.
A Study on Fabricating Microdeep Recessed Part on Copper Foil Using Laser Indirect Shock Forming
Authors: Liu Huixia , Shen Zongbao , Wang Xiao , Li Pin , Hu Yang , Gu Chunxing
Published: July 2013

Laser indirect shock forming is a novel microfabrication technique to introduce 3D profiles in metallic thin films. Experiments were performed by allowing the laser-driven flyer to impact the thin film, which is placed above a micromould. The effects of laser energy and sample thickness on deformation mechanism were investigated experimentally. The experimental results show that increasing the laser energy could increase the deformation depth, but may induce fracture along the edges of the micromould when the laser energy is too high. Moreover, the target plate was completely sheared off for 10 μm copper when the pulse energy is 1200 mJ. So it can be found that the technique can also realize micro punching of metallic thin films. The transient deformation of copper foil impacted by laser-driven flyer is simulated in this paper. Experimental data obtained were then used to validate the corresponding simulation model. Good agreement has been obtained between the numerical simulation and the experiments under different laser energy. The rising temperature due to the adiabatic conditions is taken into account. And the strain distribution has been also calculated numerically.
Stability Analysis of Milling Via the Differential Quadrature Method
Authors: Ding Ye , Zhu LiMin , Zhang XiaoJian , Ding Han
Published: July 2013

This paper presents a time-domain semi-analytical method for stability analysis of milling in the framework of the differential quadrature method. The governing equation of milling processes taking into account the regenerative effect is formulated as a linear periodic delayed differential equation (DDE) in state space form. The tooth passing period is first separated as the free vibration duration and the forced vibration duration. As for the free vibration duration, the analytical solution is available. As for the forced vibration duration, this time interval is discretized by sampling grid points. Then, the differential quadrature method is employed to approximate the time derivative of the state function at a sampling grid point within the forced vibration duration by a weighted linear sum of the function values over the whole sampling grid points. The Lagrange polynomial based algorithm (LPBA) and trigonometric functions based algorithm (TFBA) are employed to obtain the weight coefficients. Thereafter, the DDE on the forced vibration duration is discretized as a series of algebraic equations. By combining the analytical solution of the free vibration duration and the algebraic equations of the forced vibration duration, Floquet transition matrix can be constructed to determine the milling stability according to Floquet theory. Simulation results and experimentally validated examples are utilized to demonstrate the effectiveness and accuracy of the proposed approach.
Slow-Roll of 40 MW Condensing-Extraction Steam Turbines in a 420 MW Cogeneration Plant
Authors: Ingistov Steve , Milos Michael , Bhargava Rakesh K.
Published: July 2013

This paper describes efforts required to operate condensing-extraction steam turbine generators with flexible rotor design on a slow-roll (also called, true stand-by) mode of operation. This mode of operation became necessary as a result of changing steam demand from the refinery and the resulting decreased performance of the existing steam turbine generators and the associated economic losses for the cogeneration facility. Design modifications implemented to achieve slow-roll of steam turbine generators and produce maximum power output obtainable with new steam flow conditions without affecting reliability and availability of the entire cogeneration facility are discussed in this paper. Successful implementation of the proposed design approach was demonstrated through extensive field testing completed in the summer of 2011. A simple life cycle economic analysis shows that the payback period associated with the proposed design modifications implemented to two steam turbine generators at the plant is approximately six (6) months.
Noise Controlling Using Porous Stabilizers in a Cross-Flow Fan
Authors: Lai Huanxin , Zhang Hongbo , Yao Jin , Xing Gailan
Published: July 2013

Experimental measurements and simulations are carried out to study the performances and the unsteady internal flow fields of a cross-flow fan (CFF), which uses a kind of porous stabilizers proposed by the authors in an attempt to control the noise. The performance curve and sound radiation of the fan as well as instantaneous pressure fluctuations in the flowfield are measured and analysed. Transient calculations of the flowfield are carried out to study the vortical flows inside the fan as well as in the porpous stabilizers. The results show that the porous stabilizers have not produced considerable effect on the cross-flow fan’s performance curve, but the amplitude of the pressure fluctuation and the level of radiated noise are affected. This qualitative study indicates the cross-flow fan noise may be controlled by using the porous stabilizers if the porosity is properly selected.
Study on Design and Performance of Low Temperature Heat Pump Evaporation System for Corrosive and Thermal-Sensitive Raw Material
Authors: Han Dong , Yue Chen , Peng Tao , Pu Wenhao , Lu Peng , Zhao Jinjie
Published: July 2013

To relieve problems of high-energy consumption and poor corrosion-resistant during the conventional corrosive and thermal-sensitive material evaporation-concentration process, a closed low temperature heat pump evaporation-concentration scheme has been recommended. Through compared with the usual mechanical vapor recompression (MVR) heat pump evaporation-concentration process, a vitamin E solution evaporation-concentration scheme was analyzed as an example, key equipments size, cost, integrated thermodynamic performance and economic performance of the proposed system scheme have been explored. The results showed, compared with the MVR scheme, the closed low temperature heat pump evaporation-concentration scheme hold advantages in comprehensive performance. And raw material evaporation temperature selection affected integrated performance of the proposed scheme less. The comprehensive performance index is decreased with evaporation temperature for both of the two schemes. At the same evaporation temperature increase, the comprehensive performance is decreased less than that of the MVR scheme. Advantage of the proposed scheme became obvious when the evaporation temperature lower than 44 °C. Furthermore, thermodynamic performance of the proposed suggested worse than that of the MVR heat pump, while the key equipment- compressor of the proposed scheme was compact, cost less, and regardless considering the processed corrosive material causticity impaction.
Advanced Hydrogen Turbine Development Update
Authors: Bradley Tim , Marra John
Published: July 2013

Siemens Energy, Inc. was awarded a contract by the U.S. Department of Energy for the first two phases of the Advanced Hydrogen Turbine Development Program. The 3-Phase, multi-year program goals are to develop an advanced syngas, hydrogen and natural gas fired gas turbine fully integrated into coal-based Integrated Gasification Combined Cycle (IGCC) plants.

The program goals include demonstrating:

• A 3–5% point improvement in combined cycle efficiency above the baseline,

• 20–30% reduction in combined cycle capital cost

• Emissions of 2 ppm NOx @ 15% O2 by 2015.

Siemens is currently well into Phase 2 of the program and has made significant progress in several areas. This includes the ability to attain the 2015 Turbine Program performance goals by developing component and systems level technologies, developing and implementing validation test plans for these systems and components, performing validation testing of component technologies, and performance demonstration through system studies.

Siemens and the Advanced Hydrogen Turbine Program received additional funds from the American Recovery and Reinvestment Act (ARRA) in 2010. The additional funding serves to supplement budget shortfalls in the originally planned spend rate.

The development effort has focused on engine cycles, combustion technology development and testing, turbine aerodynamics/cooling, modular component technology, materials/coatings technologies and engine system integration/flexibility considerations. High pressure combustion testing continues with syngas and hydrogen fuels on a modified premixed combustor. Advanced turbine airfoil concept testing continues. Novel manufacturing techniques were developed that allow for advanced castings and faster time to market capabilities. Materials testing continues and significant improvements were made in lifing for Thermal Barrier Coatings (TBC’s) at increased temperatures over the baseline. Studies were conducted on gas turbine/IGCC plant integration, fuel dilution effects, varying air integration, plant performance and plant emissions. The results of these studies and developments provide a firm platform for completing the advanced Hydrogen Turbine technologies development in Phase 2.
Thermodynamic Analysis of a Novel Cryogenic Rankine Cycle for Wind Energy Storage
Authors: Zotter G. , Hermeling W. , Sanz W.
Published: July 2013

A novel electrical energy storage system based on cryogenic liquid nitrogen as storage medium was developed and investigated in order to integrate fluctuating wind energy into the electrical grid. In times of surplus electric power from wind turbines the electrical energy is used to generate very cold liquid nitrogen with an air separation unit which will be stored in cryogenic tanks. In times of electricity demand the energy which is stored in the coldness of the liquid nitrogen will be transferred into electrical energy by a Rankine cycle. The external heat input is solely supplied from the ambience because all changes of state of this cryogenic Rankine cycle are below the ambient temperature level. The cycle drives an expansion turbine for power generation with a power of 10 MW.

In this work two variants of the cryogenic Rankine cycle are presented.

The thermodynamic analyses show that the volumetric energy density of this liquid nitrogen energy storage system (LINESS) amounts > 50 kWh/m3, which is much higher than of many alternative energy storage systems. But the overall efficiency of this storage system is moderate and amounts 13%.

The investigations also show that the technical feasibility of the turbine is given, but a standard steam turbine cannot be adopted for this cycle. The main advantage of this novel storage system compared to compressed air or hydrogen power storage systems is that it can be built independent of geological premises due to the high volumetric energy density.
An Innovative Inlet Air Cooling System for IGCC Power Augmentation: Part I—Analysis of IGCC Plant Components
Authors: Morini Mirko , Venturini Mauro
Published: July 2013

Integrated Gasification Combined Cycle (IGCC) power plants are energy systems mainly composed of a gasifier and a combined cycle power plant. Since the gasification process usually requires oxygen as the oxidant, an Air Separation Unit is also part of the plant. Moreover, a producer gas cleaning unit is always present between the gasifier and the gas turbine.

With respect to Natural Gas Combined Cycles (NGCCs), IGCCs are characterized by a consistent loss in the overall plant efficiency due to the conversion of the raw fuel in the gasifier and the electrical power parasitized for fuel production which considerably reduces plant net electric power. In order to reduce this loss, synergies among the different components of the plant should be improved.

In this paper, an analysis of state-of-the-art IGCC plant components is presented. Particular interest is given to characteristic energy and flow streams in order to evaluate possible synergies and optimizations. Moreover, a simulation model of an IGCC plant, built in a commercial energy system simulation environment, is set up and the influence of ambient conditions on IGCC net power output is analyzed. The suggestions gained from the current paper and the simulation model will be used in the Part II of this paper to evaluate the capability of a strategy for IGCC power augmentation, based on ASU discharged nitrogen utilization.
Extending Useful Life of F-Class Gas Turbine Components
Authors: Scheibel John R. , Aluru Rajeev
Published: July 2013

This paper addresses the engineering evaluation of F-Class hot section components from an owner/operator perspective, with the practical objective of extending their interval of useful service beyond the limits recommended by the OEM. Starting with the first stage, the initial aim is to extend operation from two to three intervals. A multi-disciplinary approach to hot section life management is described, which is used to assess the component condition and possible risks involved with extending the active service life. The assessment draws from many sources: design analysis (durability, weak points, material and coating limitations), inspection (when, where, limits and tolerances), service (base load, cycling, turbine inlet temperature and hours) and repair techniques (welding, brazing, heat treatments). Results of the modeling, damage tracking, NDT and metallurgical and mechanical testing are summarized.
Thermodynamic Analysis of Gas Turbine Performance With Different Inlet Air Cooling Techniques
Authors: Pereira dos Santos Ana Paula , de Andrade Claudia Regina
Published: July 2013

For geographic regions where significant power demand and highest electricity prices occur during the warm months, a gas turbine inlet air cooling technique is a useful option for increasing output. Inlet air cooling increases the power output by taking advantage of the gas turbine’s feature of higher mass flow rate, due the compressor inlet temperature decays. Industrial gas turbines that operate at constant speed are constant-volume-flow combustion machines. As the specific volume of air is directly proportional to the temperature, the increases of the air density results in a higher air mass flow rate once the volumetric rate is constant. Consequently, the gas turbine power output enhances. Different methods are available for reducing compressor intake air temperature. There are two basic systems currently available for inlet cooling. The first and most cost-effective system is evaporative cooling. Evaporative coolers make use of the evaporation of water to reduce the gas turbine inlet air temperature. The second system employs two ways to cool the inlet air: mechanical compression and absorption. In this method, the cooling medium flows through a heat exchanger located in the inlet duct to remove heat from the inlet air. In the present study, a thermodynamic analysis of gas turbine performance is carried out to calculate heat rate, power output and thermal efficiency at different inlet air temperature and relative humidity conditions. The results obtained with this model are compared with the values of the condition without cooling herein named of Base-Case. Then, the three cooling techniques are computationally implemented and solved for different inlet conditions (inlet temperature and relative humidity). In addition, the gas turbine was performed under different cooling methods applied for two Brazilian sites, the comparison between chiller systems (mechanical and absorption) showed that the absorption chiller provides the highest increment in annual energy generation with lower unit energy costs. On the other hand, evaporative cooler offers the lowest unit energy cost but associated with a limited cooling potential.
Smart Polygeneration Grid: Control and Optimization System
Authors: Bozzo Maximiliano , Caratozzolo Francesco , Traverso Alberto
Published: July 2013

This study aims at the development of a software tool for supply and demand matching of electrical and thermal energy in an urban district.

In particular, the tool has been developed for E-NERDD, the experimental district that TPG-DIMSET is going to build in Savona, Italy.

E-NERDD is an acronym for Energy and Efficiency Research Demonstration District. It is one of the districts that will be used within the project to demonstrate how different software tools and algorithms perform in thermodynamic, economic and environmental terms.

The software tool originally developed for and implemented in this work, called E-NERDD Control System, is targeted on enabling the operation of the hardware, when connected in a district mode.

Supply and demand are matched to reach a thermoeconomic optimum. An optimization algorithm is organized into two different levels of optimization: a first level that resolves a constrained minimization problem in planning power supply for each generator on the basis of day-before forecasting; and a second level that distributes among the different machines the gap between planned and real-time demand.

The algorithm developed is demonstrated in four test cases in order to test it in different working conditions.
Alstom Gas Turbine Technology Trends
Authors: Marchmont Caroline , Florjancic Stefan
Published: July 2013

The power generation mix is in transition with more and more electricity generated by renewable sources. Combined cycle power plants will have to partner with renewable sources and compensate for their fluctuating nature. In preparation for the next generation combined cycles, gas turbine technology development needs to continue to lower the lifecycle costs through increased efficiency, extended maintenance cycles, and reduced emissions. It must now also develop fast ramping capability, account for a wider variation in fuel composition and provide an emission effective part load operation. These needs will be met by refining state of the art technologies and by adding new technologies. This paper provides an overview of the research and development activities and resulting trend in Alstom gas turbine technologies.
A New Sensor Diagnostic Technique Applied to a Micro Gas Turbine Rig
Authors: Tipa Andrea , Sorce Alessandro , Pascenti Matteo , Traverso Alberto
Published: July 2013

This paper describes the development and testing of a new algorithm to identify faulty sensors, based on a statistical model using quantitative statistical process history. Two different mathematical models were used and the results were analyzed to highlight the impact of model approximation and random error. Furthermore, a case study was developed based on a real micro gas turbine facility, located at the University of Genoa. The diagnostic sensor algorithm aims at early detection of measurement errors such as drift, bias, and accuracy degradation (increase of noise). The process description is assured by a database containing the measurements selected under steady state condition and without faults during the operating life of the plant. Using an invertible statistical model and a combinatorial approach, the algorithm is able to identify sensor fault. This algorithm could be applied to plants in which historical data are available and quasi steady state conditions are common (e.g. Nuclear, Coal Fired, Combined Cycle).
Thermodynamic Analysis of a Steam Injected and Recuperated Gas Turbine Air Compressor
Authors: Blom Matthew J. , Wiese Ashley P. , Brear Michael J. , Manzie Chris , Kitchener Anthony
Published: July 2013

Compressed air and steam are perhaps the most significant industrial utilities after electricity, gas and water, and are responsible for a significant proportion of global energy consumption. Microturbine technology, in the form of a Gas Turbine Air Compressor (GTAC), offers a promising alternative to traditional, electrically driven air compressors providing low vibration, a compact size, reduced electrical consumption and potentially reduced greenhouse gas emissions. With high exhaust temperatures, gas turbines are well suited to the cogeneration of steam. The compressed air performance can be further increased by injecting some of that cogenerated steam or by conventional recuperation.

This paper presents a thermodynamic analysis of various forms of the GTAC cycle incorporating steam cogeneration, steam injection (STIGTAC) and recuperation. The addition of cogeneration leads to improved energy utilisation, while steam injection leads to a significant boost in both the compressed air delivery and efficiency. As expected, for a low pressure ratio device, recuperating the GTAC leads to a significant increase in efficiency. The combination of steam injection and recuperation forms a recuperated STIGTAC with increased compressed air performance over the unrecuperated STIGTAC at the expense of reduced steam production. Finally, an analysis using a simplified model of the STIGTAC demonstrates a significant reduction in CO2 emissions, when compared to an equivalent air compressor driven by primarily coal-based electricity and a natural gas fired boiler.
Performance Evaluation of the Integration Between a Thermo-Photo-Voltaic Generator and an Organic Rankine Cycle
Authors: Ferrari Claudio , Melino Francesco , Barbieri Enrico , Morini Mirko , Pinelli Michele , De Pascale Andrea , Peretto Antonio
Published: July 2013

The present study deals with the integration between a Thermo-Photo-Voltaic generator (TPV) and an Organic Rankine Cycle (ORC) named here TORCIS (Thermo-photo-voltaic Organic Rankine Cycle Integrated System). The investigated TORCIS system is suitable for CHP applications, such as residential and tertiary sector users. The aim of the research project on this innovative system is the complete definition of the components design and the pre-prototyping characterization of the system, covering all the unresolved issues. This paper shows the results of a preliminary thermodynamic analysis of the system. More in details, TPV is a system to convert into electric energy the radiation emitted from an artificial heat source (i.e., combustion of fuel) by the use of photovoltaic cells; in this system, the produced electric power is strictly connected to the thermal one, as their ratio is almost constant and cannot be changed without severe loss in performance; the coupling between TPV and ORC allows to overcome this limitation and to realize a cogenerative system which can be regulated with a large degree of freedom changing the electric-to-thermal power ratio. The paper presents and discusses the TORCIS achievable performance, highlighting its potential in the field of distributed generation and cogenerative systems.