bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the Correlation Between Spanwise Inducer Incidence and Impeller Diffusion for Ruled Surface and Barreled Sweep-Bow Impeller Design at Inlet Guide Vane-Off-Design
Authors: Hildebrandt A. , Ceyrowsky T. , Klausmann J. , Metz K. A. 
Published: August 2021

AbstractIn the present paper, three centrifugal stages of high volume flow coefficient are compared to each-other regarding their aerodynamic performance in design point and off-design point conditions at different speed and inlet guide vane (IGV)-setting angle: two stages with full-blade design (no splitter blades) have been numerically designed with different design geometry methodology. One geometry is based on a classical ruling surface design with a linear leading edge, the second geometry based on a fully-three-dimensional surface including a blade bow at the trailing edge and a barreled sweep at the leading edge. According to impeller test rig measurements and computational fluid dynamics (CFD) calculation, the classical ruling surface designed impeller outperforms the more sophisticated centrifugal stage with fully 3D-blade at fully axially guided IGV-flow. In the contrary, at closing IGV-off-design setting angles, toward surge operation, the fully 3D-blade impeller performs with higher efficiency and steeper negative pressure slope. On the search of the geometrical causes for the different aerodynamic performance (especially at IGV-off-design conditions), focus is set on the analysis of IGV-flow-interaction with the inducer flow and impeller diffusion. The one-dimensional analysis of the spanwise flow at the impeller leading edge reveals that, compared with the ruling surface impeller, the fully 3D-blade performs with lower flow incidence losses in favor to IGV-off-design operation than at IGV-neutral position. The streamwise flow analysis confirms the improved flow incidence characteristics of the 3D-blade impeller due to reduction of aerodynamic blockage and entropy production in the vicinity of the impeller leading edge. Based on CFD calculations, a new correlation of secondary flow and flow incidence is proposed, to be used for one-dimensional modeling.
Combustion Turbine Exhaust Duct, Silencer, and Stack Scale Modeling
Authors: Craven Robert , Kirkpatrick Keith , Idem Stephen 
Published: August 2021

Abstract
After constructing a scale model of planned changes to a power plant exhaust system, tests were performed to measure pressure losses in the transition, silencer, and stack. A dimension of 0.30 m (1.0 ft) for the scale model corresponded to 3.7 m (12.0 ft) at full scale. To the extent possible, the scale model tests exhibited geometric similarity with the actual power plant. Total pressure loss coefficients varied between 2.122, 1.969, and 1.932, for three separate scale model configurations that were considered. A combination of turning vanes and splitter vanes in the five-gore elbow, coupled with the use of turning vanes in the rectangular elbow yielded the lowest total pressure loss. Although Reynolds number similarity between the scale model experiments and the actual power plant was not attained, Reynolds number independence was achieved in the tests. The results from this study was applied to model pressure loss in the actual power plant. The scale model testing revealed that utilization of the exhaust ducting design designated as Case A would yield a sufficiently low pressure loss that it would not degrade the performance of the combustion turbine in the power plant to be repaired. Therefore it was selected for inclusion in the retro-fitting of the power plant to facilitate its being quickly brought back on-line.
Socio-Environmental Impacts of Hydro Power Technology- a Review
Authors: Singh Aanya , Mandavkar Rohit , Singh Sanjay , Prabhu Bhembre Raunak , Jain Devansh , Rufuss D. DSilva Winfred 
Published: August 2021

Abstract
Renewable energy, is the primary load bearer of a sustainable circular economy and hydropower being one of the earliest forms of it, has a wide application base. With unprecedented situations being faced by the people every day, power consumption patterns and requirements are changing and so are the faces of the leading economies. However, like other renewable strategies it is assayed based on the greenhouse gas emissions during its operation. This unfortunately presents a true but blurry picture. Some of the long-term issues with creating a dam, are soil quality degradation in downstream regions, loss of aquatic life due to high-speed turbine blades, disbalance in the nutrient cycle of aquatic systems, water contamination with machinery oils, displacement of local communities, loss of soil fertility near the site due to drilling and tunnelling, landslides and seismic issues due to excavation of land which loosens the nearby soil cover. Therefore, our goal is to analyze and compile various case studies of hydro power projects throughout the globe which caused some environmental or social disruption in their respective regions and the various steps that were taken by the government or the locals to tackle these problems. Many areas faced seismic problems, environmental degradation, water profile alterations and social displacement. But, by opting for new turbine technologies, fish friendly channel designs and landscaping procedures featuring indigenous vegetation to restore surrounding ecology, those regions were able to amend the problems with their hydropower project.
Transient Exergy Analysis of the Dynamic Operation of a Combined Cycle Power Plant
Authors: Wittenburg Raphael , Hübel Moritz , Holtz Dorian , Müller Karsten 
Published: August 2021

Abstract
The increasing share of fluctuating electricity feed-in from wind energy and photovoltaic systems has a significant impact on the operating regime of conventional power plants. Since frequent load changes were not the focus of optimization in the past, there is still potential for improving the transient operating behavior. Exergy analyses are increasingly used to determine optimization potentials in energy conversion processes, but are mostly limited to stationary conditions.
In order to perform an exergy analysis of the transient operation of a combined cycle power plant on component level, detailed information on the state and process variables of the individual components is required. These are not completely accessible via measurement data alone. For this reason, a comprehensive dynamic simulation model was developed, which includes the process components and the power plant control system. With the help of the implemented exergetic balance and state equations, the desired exergy quantities can be determined.
The simulation results are used to evaluate the transient operating behaviour at different load change gradients and control actions on the basis of exergetic parameters. The exergy analysis results in an improved understanding of the causes of exergy destruction in the system, which can be used for optimization approaches. As expected, the main causes of exergy destruction are combustion processes and increased temperature gradients during transient operation. Overall, however, only moderately increased exergy destruction can be determined for the transient operation of the investigated plant compared to the steady state.
Numerical Study on the Adaptation of Diesel Wave Breakup Model for Large-Eddy Simulation of Non-Reactive Gasoline Spray
Authors: Sok Ratnak , Zhou Beini , Kusaka Jin 
Published: August 2021

Abstract
Gasoline direct injection (GDI) is a promising solution to increase engine thermal efficiency and reduce exhaust gas emissions. The GDI operation requires an understanding of fuel penetration and droplet size, which can be investigated numerically. In the numerical simulation, primary and secondary breakup phenomena are studied by the Kelvin-Helmholtz/Rayleigh-Taylor (KH-RT) wave breakup models. The models were initially developed for diesel fuel injection, and in the present work, the models are extended to the GDI application combined using large-eddy simulation (LES). The simulation is conducted using the KIVA4 code.
Measured data of experimental spray penetration and Mie-scattering image comparisons are carried out under non-reactive conditions at an ambient temperature of 613K and a density of 4.84 kg/m3. The spray penetration and structures using LES are compared with traditional Reynolds-Averaged Navier-Stokes (RANS). Grid size effects in the simulation using LES and RANS models are also investigated to find a reasonable cell size for future reactive gasoline spray/combustion studies. The fuel spray penetration and droplet size are dependent on specific parameters. Parametric studies on the effects of adjustable constants of the KH-RT models, such as time constants, size constants, and breakup length constant, are discussed. Liquid penetrations from the RANS turbulence model are similar to that of the LES turbulence model’s prediction. However, the RANS model is not able to capture the spray structure well.
Uncertain Gain and Time-Delay Control of 300-kW SOFC-GT
Authors: Emami Tooran , Tucker David , Watkins John 
Published: August 2021

Abstract
This paper presents a Proportional Integral Derivative (PID) controller design with the presence of an uncertain internal gain and additional time delay in the forward path of a 300 kW Solid Oxide Fuel Cell-Gas Turbine (SOFC-GT). The outputs of the system are turbine speed and the fuel cell mass flow rate. A fixed set of proportional controller coefficients are determined to graphically develop an area of selection for the integral and derivative coefficients of the PID controller. The inputs to the power plant are the electric load and cold air valve. The decentralized controllers are applied to four sub-systems as a Single Input Single Output (SISO). The PID controller coefficients are selected from a singular matrix solution that stabilizes the system and satisfies the internal gain and time delay uncertainties. Two sub-systems are the transfer functions of the turbine speed over the electric load and the cold air valve. The other two sub-systems are the transfer functions of the fuel cell mass flow rate over the electric load and the cold air bypass valve. Multiple options for selecting PID controller coefficients are beneficial to the SOFC-GT plant due to the wide range of operations and internal uncertainty interactions. The specific internal time delay and gain margins increase the reliability and robustness of the SOFC-GT with multiple uncertain parameters.
Gas Turbine Evaporative Cooling, A Novel Method for Combined Cycle Plant Part Load Optimization
Authors: Carmona Jose 
Published: August 2021

Abstract
In power plant engineering, gas turbine (GT) evaporative cooling is traditionally thought as one of the few power augmentation alternatives for existing plants.
For most combined cycle plants operating at part load, the GT Inlet Guide Vanes (IGV) will throttle the air flow to the combustor to maintain the turbine exhaust temperature (TET) as high as possible, thus maximizing the overall combined cycle efficiency. The IGV air throttling results in a reduction of the turbine inlet air temperature (TIT) due to a reduction on the mass of fuel burned in the combustors as the available combustion air decreases due to IGV throttling to maintain an optimum air to fuel ratio, resulting on a lower TET compared with the same GT at base load. The compounded result of these effects limits the maximum steam production capacity on the heat recovery steam generator, particularly for the high-pressure section, hampering the efficiency of the steam turbine.
The methodology developed in the subject study aims at counteracting the afore-mentioned effects by optimizing the evaporative cooler air/water ratio which results in the lower possible heat rate for full load and part load operation. By dynamically controlling the air/water ratio, a preheating effect can be achieved in the compressor inlet air, which results on higher exhaust gas temperature, thus augmenting the high-pressure steam production on the heat recovery steam generator and accordingly the steam turbine efficiency.
For a newly built 907 MWe Combined Cycle Gas Turbine (CCGT) plant, application of the evaporative cooling part load optimization methodology presented in this study could lead to a potential reduction of up to 158kJ/kWh on heat rate and 9.318 g/kWh of CO2 emissions if compared with the same plant without dynamic control of the evaporative cooler air/water ratio.
Combined Cycle Gas Turbines With Electrically-Heated Thermal Energy Storage for Dispatchable Zero-Carbon Electricity
Authors: Stack Daniel , Forsberg Charles 
Published: August 2021

Abstract
A low-carbon world needs a replacement for natural gas-fired power to provide variable heat and electricity. The coupling of simple or combined cycle gas turbines (CCGTs) with advanced electrically-heated thermal energy storage (E-TES) systems is an alternative approach to energy storage with cost advantages over batteries or hydrogen production. CCGTs with E-TES may use stored low-value electricity to run the power cycle in place of fossil fuels. This (1) saves money for the power plants by allowing them to switch heat sources based on price, and (2) reduces carbon emissions by making use of otherwise curtailed renewable energy. The development of electrically conductive firebricks enables temperatures approaching 2000°C, hotter than existing E-TES options, sufficient to run CCGTs. Levelized cost of storage (LCOS) calculations show that the use of CCGTs with novel E-TES increases the cost of energy by less than a factor of 2, compared to a factor of 9 increase when using lithium-ion batteries. Unlike batteries, the CCGT with E-TES, provides assured generating capacity by normal operation of the gas turbine. A case study of CCGT coupled with E-TES is included based on 2019 electricity prices in Southern California, which showed an 18% reduction in fuel consumption and $11M savings based purely on the arbitrage case. The arbitrage case is expected to improve dramatically over the decade as deployment of renewable energy in California increases.
Are Self-Efficacy and Perceived Environmental Characteristics Determinants of Decline in Physical Activity Time?
Authors: Silva Eduarda Cristina da Costa , Barbosa Arthur Oliveira , Silva Juliana Maria da Penha Freire , de Farias Júnior José Cazuza 
Published: August 2021

Context: This study analyzed whether self-efficacy (SE) and perceived environmental characteristics (EC) are determinants of the decline in physical activity (PA) time in adolescents. Methods: This used longitudinal observational approach, with 4 years of data collection, involving 355 adolescents (57.7% girls and 42.3% boys), average age of 11.8 years (0.1 y), from João Pessoa, Paraiba, Brazil. SE and EC were measured by scales and PA by a questionnaire. Ordinal logistic regression was used to associate SE and EC with a decline in PA. Results: There was a linear trend toward a decrease in average PA duration (58.3 [13.7] min/wk/y) and a rise in average access to places for PA (point per year) (0.6 [0.1]), urban safety (0.2 [0.1]), and traffic safety scores (0.5 [0.1]). The results of multivariable analysis indicated that SE and EC were not associated with the decline in PA. Conclusion: There was a decline in PA time, and SE and perceived EC were not determinants of this decline.
Erosion due to a century of road construction and maintenance at Mount Diablo State Park, California
Authors: Fuller Michael S. , Roffers Peter D. 
Published: August 2021

ABSTRACT
Mount Diablo State Park exemplifies many other conservation areas where managers balance the dual missions of protecting natural resources while providing public access. Roads and trails that crisscross the park are etched into the geomorphic surface, capturing and redirecting storm runoff, and presenting both a challenge for soil conservation and a consequence of construction and maintenance.
We used field mapping, remote sensing, and modeling to assess erosion along the roads and trails in Mount Diablo State Park, which encompasses the headwaters of several urbanized watersheds. The field mapping in 2011 determined that 56% of the assessed roads and trails required either repair or reconstruction to control erosion and that ~67% of the culverts in the park required either repair or replacement. Aerial photography and modeling showed that other erosion (unrelated to roads or trails) preferentially occurred during wet periods, in specific lithologies, and on convergent slopes.
Although lithology and climate drive slope-forming geomorphic processes, we found that the road and trail system (1) expanded the stream network with a capillary-like system of rills, (2) catalyzed prolonged erosion, and (3) altered the timing and pattern of sediment yield. In addition to water-driven erosion during wet periods, road and trail surfaces were subject to mechanical and wind erosion during dry periods. Spatially, dry erosion and runoff both conformed with and crossed topographic gradients by following the road and trail network. Road- and trail-induced erosion occurred across a wider range of rock properties and slope geometries than is typical for other erosion. Hence, the roads and trails have expanded the spatial and temporal boundary conditions over which geomorphic processes operate and, due to continual soil disturbance, have accelerated erosion rates.
Although road density is a commonly used metric to rank road-related impacts at watershed scales, it misses both spatial variability and the opportunity to identify specific road and trail segments for remediation. We developed a spatially explicit scoring scheme based on actual erosion and the potential for sedimentation of discrete waterbodies. The data were incorporated into the park’s road and trail management plan in 2016.
Mid-Cenozoic succession on the northeast limb of the Mount Diablo anticline, California—A stratigraphic record of tectonic events in the forearc basin
Authors: Sullivan Raymond , Sullivan Morgan D. , Edwards Stephen W. , Sarna-Wojcicki Andrei M. , Hackworth Rebecca A. , Deino Alan L. 
Published: August 2021

ABSTRACTThe mid-Cenozoic succession in the northeast limb of the Mount Diablo anticline records the evolution of plate interactions at the leading edge of the North America plate. Subduction of the Kula plate and later Farallon plate beneath the North America plate created a marine forearc basin that existed from late Mesozoic to mid-Cenozoic times. In the early Cenozoic, extension on north-south faults formed a graben depocenter on the west side of the basin. Deposition of the Markley Formation of middle to late? Eocene age took place in the late stages of the marine forearc basin. In the Oligocene, the marine forearc basin changed to a primarily nonmarine basin, and the depocenter of the basin shifted eastward of the Midland fault to a south-central location for the remainder of the Cenozoic. The causes of these changes may have included slowing in the rate of subduction, resulting in slowing subsidence, and they might also have been related to the initiation of transform motion far to the south. Two unconformities in the mid-Cenozoic succession record the changing events on the plate boundary. The first hiatus is between the Markley Formation and the overlying Kirker Formation of Oligocene age. The succession above the unconformity records the widespread appearance of nonmarine rocks and the first abundant appearance of silicic volcanic detritus due to slab rollback, which reversed the northeastward migration of the volcanic arc to a more proximal location. A second regional unconformity separates the Kirker/Valley Springs formations from the overlying Cierbo/Mehrten formations of late Miocene age. This late Miocene unconformity may reflect readjustment of stresses in the North America plate that occurred when subduction was replaced by transform motion at the plate boundary. The Cierbo and Neroly formations above the unconformity contain abundant andesitic detritus due to proto-Cascade volcanism. In the late Cenozoic, the northward-migrating triple junction produced volcanic eruptive centers in the Coast Ranges. Tephra from these local sources produced time markers in the late Cenozoic succession.
Factors influencing the readiness to tackle the burden of ischaemic heart disease in India: a systematic review protocol
Authors: Bhattacharjee Shuvarthi , Yaghmaei Nima , Phuong Cao Tran Le , Neupane Dinesh 
Published: August 2021

IntroductionIschaemic heart disease (IHD) is one of the leading causes of death and disease burden in India affecting all age groups. To reduce the deaths and tackle the burden of existing IHD, the government approach has been mostly through the National Health Policy (2017) and National Programme for Prevention and Control of Diabetes, Cardiovascular diseases and Stroke. This paper offers a protocol for the systematic review of studies exploring the factors influencing service readiness of the public health system of India to tackle the burden of IHD.Methods and analysisElectronic databases of Embase (Ovid), AMED (Ovid), HMIC (Ovid), BNI (ProQuest), CINAHL (EBSCO), EMCARE (Ovid), PsycINFO (ProQuest), MEDLINE/PubMed and Web of Science (Clarivate Analytics) will be searched till 2020 for primary studies. Grey literature will be accessed through OpenGrey, TRIP Medical, WHO database, MoHFW website, Open Government Data (OGD) Platform of India and Google Scholar (between 2010 and 2020). Primary studies meeting the eligibility criteria and grey literature published in English between 2010 and 2020 will be included. Data will be analysed through a conceptual framework, and the primary outcome will constitute both quantitative and qualitative data. The quality of included studies will be assessed based on study design. Data will be managed on the COVIDENCE platform. All authors will be involved in data extraction, quality appraisal, data synthesis and formulation of the final draft.Ethics and disseminationThis study, being a systematic review, does not involve any clinical trial, primary data collection or empirical study involving humans or animals. Therefore, no ethical permissions were sought by reviewers.PROSPERO registration numberCRD42020219490.