bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermohydrodynamic Modeling of a Tapered-Land Thrust Bearing With Validation Against Experimental Data
Authors: Gokaltun Seckin 
Published: September 2021

Abstract
In this work, a computational fluid-film bearing analysis model has been utilized in order to investigate the conjugate heat transfer problem for a tapered-land bearing using computational fluid dynamics (CFD) analysis. The academic model is based on the 2D Reynolds equation for the pressure distribution in the film the 3D energy equation is solved for the the bearing pad and the fluid film; therefore, the lubricant properties such as viscosity and density could be made temperature-dependent. The runner is modeled using a 2D axisymmetric mesh. The current analysis excludes the mechanical or thermal deformations of the bearing and the runner since it was observed that the results for output quantities such as film temperature, film pressure, torque and load capacity were within reasonable agreement with the benchmark data obtained from the experiments for the majority of the speed and load cases studied. Comparisons of modeling results against the benchmark data was obtained for cases ranging from 2000 rpm to 10,000 rpm at loads varying from 1000 N to 8000 N. The importance of proper boundary conditions used in the heat transfer model is emphasized as well as the coupling of heat transfer between the film and the solid surfaces of collar and the bearing is described. The results obtained here yielded that a thermohydrodynamic (THD) model that includes the energy transfer into the structures surrounding the fluid film is sufficient enough to predict the performance of a tapered-land bearing at a wide speed and load range in the case where the runner is thick enough that the effect of deformations on the results can be ignored.
Investigation of a Passive Flow Control Device in an S-Duct Inlet at High Subsonic Flow
Authors: Rider Courtney , Asghar Asad , Allan William D. E. , Ingram Grant , Stowe Robert , Pimentel Rogerio 
Published: September 2021

Abstract
This paper reports the investigation of a flow control strategy for an S-duct diffusers. The method incorporates stream-wise tubercles, and aims to enhance the performance of S-duct inlets by reducing the size and intensity of separated flow. These devices, bioinspired from humpback whale flippers’ leading edge protuberances, have been shown to be effective in increasing post-stall coefficients of lift of airfoils. In S-duct diffusers, the presence of convex curvature next to the separated region provides an ideal location for the installation of a tubercle-like device. The flow control effectiveness was evaluated by test-rig measurements and computational fluid dynamics (CFD) simulations of the flow in an S-duct at high subsonic flow conditions (Ma = 0.80). The S-ducts were rapid prototyped in plastic using 3D printing. Static surface pressure along the length and total pressure at the exit revealed pressure recovery, total pressure loss, swirl, and the nature of flow distortion at the S-duct exit. CFD simulations used ANSYS FLUENT with a RANS solver closed with the RKE turbulence model. The CFD simulation compared well with the test-rig data and provided useful information on flow mechanism and for understanding flow features. The performance of the baseline and variant with the flow control device was compared and flow control strategy was evaluated.
The Effect of Compressibility Factor on Turbine Performance
Authors: Baumgärtner David , Otter John J. , Wheeler Andrew P. S. 
Published: September 2021

Abstract
The compressibility factor Z is one of the most common properties that describes a fluid diversion from an ideal gas. Still, its effect on turbine performance is not well known. We determine a set of non-dimensional parameters that fix the gas dynamic behaviour, independent of Z, and thus isolate the effect that Z has on turbine performance. The results indicate that, contrary to the common perception, low values of Z and hence a strong diversion from an ideal gas lead to a reduction in loss for supersonic operating conditions, if all other non-dimensionals are accounted for. The aerodynamic mechanisms responsible are due to reductions in shock, boundary layer and trailing edge loss. The results from this paper are relevant for all future turbines operating with non-ideal working fluids.
Research on Fault Diagnosis of Steam Turbine Rotor Unbalance and Parallel Misalignment Based on Numerical Simulation and Convolutional Neural Network
Authors: Wang Chongyu , Zhang Di , Xie Yonghui 
Published: September 2021

Abstract
The steam turbine rotor is still the main power generation equipment. Affected by the impact of new energy on the power grid, the steam turbine needs to participate in peak load regulation, which will make turbine rotor components more prone to failure. The rotor is an important equipment of a steam turbine. Unbalance and misalignment are the normal state of rotor failure. In recent years, more and more attention has been paid to the fault detection method based on deep learning, which takes rotating machinery as the object. However, there is a lack of research on actual steam turbine rotors. In this paper, a method of rotor unbalance and parallel misalignment fault detection based on residual network is proposed, which realizes the end-to-end fault detection of rotor. Meanwhile, the method is evaluated with numerical simulation data, and the multi task detection of rotor unbalance, parallel misalignment, unbalanced parallel misalignment coupling faults (coupling fault called in this paper) is realized. The influence of signal-to-noise ratio and the number of training samples on the detection performance of neural network is discussed. The detection accuracy of unbalanced position is 93.5%, that of parallel misalignment is 99.1%. The detection accuracy for unbalance and parallel misalignment is 89.1% and 99.1%, respectively. The method can realize the direct mapping between the unbalanced, parallel misalignment, coupling fault vibration signals and the fault detection results. The method has the ability to automatically extract fault features. It overcomes the shortcoming of traditional methods that rely on signal processing experience, and has the characteristics of high precision and strong robustness.
Potential of Micro Gas Turbines to Provide Renewable Heat and Power in Off-Grid Applications for Desalination and Industrial Wastewater Treatment
Authors: Montes-Sánchez J. , de Weert B. , Petit B. , García-Rodríguez L. , Sánchez D. 
Published: September 2021

Abstract
The demand for all types of resources (food, freshwater, energy and raw materials) has increased alarmingly due to the continuous techno-economic development of society, bringing about a pressing shortage not only in low-income countries but also in more developed economies. Such is the case for the very wealthy countries in the Gulf Cooperation Council, which are currently struggling with the lack of fresh water supply, or certain countries in Latin America where the contamination of natural water sources poses a major environmental threat. In order to assess this water-energy nexus problem, this paper looks into systems where the production of renewable power is combined with either freshwater production (through desalination) or industrial wastewater treatment for effluent control. Three enabling renewable energy technologies are assessed: solar micro gas turbines, wind turbines and photovoltaic panels. In all cases, off-grid installations are considered.
The paper describes the characteristics of these three systems and provides a comparison of technical specifications, yield and costs. Wind and photovoltaic are the standard approach, as already proven by a number of commercial plants, but solar micro gas turbines exhibit additional flexibility (in particular when hybridisation is considered) and have the differential feature of producing not only electric power but also heat. This enables the combination of different types of water treatment technologies in order to increase water production/recovery which, in turn, reduces the environmental impact of the production process associated (either freshwater or other good or service).
Unlocking the Green Economy for Aeroderivative Gas Turbines
Authors: Corbett Nicholas C. , Houde Michel , Bohan Kathleen , Batt Simon 
Published: September 2021

Abstract
If existing gas turbine engines are to remain as the primary choice source of power for supplying short term peaking power capacity in an emergency, then they will need to be capable of directly using a alternative carbon neutral fuel supply. It is important that the fuel can be stored locally to ensure operation of the gas turbine can be provided without reliance upon supplies through distribution network infrastructure or stored hydrogen. Alternative carbon neutral fuels such as synthetic electro or biomass manufactured from hydrogen with nitrogen or CO2 to produce respectively; nitrofuel (Ammonia) or carbofuel (Methanol). Both fuels are renewable and compatible with existing carbon supply chain infrastructure as they can be similarly transported and stored as liquids with similar properties.
Digital technologies can help accelerate the uptake of carbon neutral solutions by operators by assisting them to make greener choices, from the data and information presented to them, promoting the use of their assets demonstrating their contribution and responsibilities to managing the environment. Whilst progress in adopting digital technology has been slow, it is by linking the investment to decarbonization that could then be considered as a value adder rather than a regulatory requirement.
The paper discusses the program of work to develop a bundle of digital services whilst decarbonizing aeroderivative gas turbine applications.
Condition Monitoring of Wind Turbines Based on the Scattering Transform of Vibration Data
Authors: Qi Junyu , Mauricio Alexandre , Gryllias Konstantinos 
Published: September 2021

Abstract
As a renewable, unlimited and free resource, wind energy has been intensively deployed in the past to generate electricity. However, the maintenance of Wind Turbines (WTs) can be challengeable. On the one hand, most wind farms operate in remote areas and on the other hand, the dimension of WTs’ tip/hub/rotor are usually enormous. In order to prevent abrupt breakdowns of WTs, a number of Condition Monitoring (CM) methods have been proposed. Focusing on bearing diagnostics, Squared Envelope Spectrum is one of the most common techniques. Moreover in order to identify the optimum demodulation frequency band, fast Kurtogram, Infogram and Sparsogram are nowadays popular tools evaluating respectively the Kurtosis, the Negentropy and the Sparsity. The analysis of WTs usually requires high effort due to the complexity of the drivetrain and the varying operating conditions and therefore there is still need for research on effective and reliable CM techniques for WT monitoring. Thus the purpose of this paper is to investigate a blind and effective CM approach based on the Scattering Transform. Through the comparison with state of the art techniques, the proposed methodology is found more powerful to detect a fault on six validated WT datasets.
Experimental Characterization of the Evolution of Global Flow Structure in the Passage of an Axial Compressor
Authors: Saraswat Ayush , Koley Subhra Shankha , Katz Joseph 
Published: September 2021

Abstract
Ongoing experiments conducted in a one-and-half stages axial compressor installed in the JHU refractive index-matched facility investigate the evolution of flow structure across blade rows. After previously focusing only on the rotor tip region, the present stereo-PIV (SPIV) measurements are performed in a series of axial planes covering an entire passage across the machine, including upstream of the IGV, IGV-rotor gap, rotor-stator gap, and downstream of the stator. The measurements are performed at flow rates corresponding to pre-stall condition and best efficiency point (BEP). Data are acquired for various rotor-blade orientations relative to the IGV and stator blades. The results show that at BEP, the wakes of IGV and rotor are much more distinct and the wake signatures of one row persists downstream of the next, e.g., the flow downstream of the stator is strongly affected by the rotor orientation. In contrast, under pre-stall conditions, the rotor orientation has minimal effect on the flow structure downstream of the stator. However, the wakes of the stator blades, where the axial momentum is low, are now wider. For both conditions, the flow downstream of the rotor is characterized by two regions of axial momentum deficit in addition to the rotor wake. A deficit on the pressure side of the rotor wake tip is associated with the tip leakage vortex (TLV) of the previous rotor blade, and is much broader at pre-stall condition. A deficit on the suction side of the rotor wake near the hub appears to be associated with the hub vortex generated by the neighboring blade, and is broader at BEP. At pre-stall, while the axial momentum upstream of the rotor decreases over the entire tip region, it is particularly evident near the rotor blade tip, where the instantaneous axial velocity becomes intermittently negative. Downstream of the rotor, there is a substantial reduction in mean axial momentum in the upper half of the passage, concurrently with an increase in the circumferential velocity. Consequently, the incidence angle upstream of the stator increases in certain regions by up to 30 degrees. These observations suggest that while the onset of the stall originates from the rotor tip flow, one must examine its impact on the flow structure in the stator passage as well.
Aerodynamic Characteristics of a Blended-Wing-Body Aircraft With A Serpentine Inlet Using Flow Control Techniques
Authors: Youn Min-Sik , Kim Youn-Jea 
Published: September 2021

Abstract
Demands of a modern aircraft regarding its aerodynamic performance and high efficiency are ever-growing. An S-shaped inlet, as known as a serpentine duct, plays a significant role in increasing fuel efficiency. Recently, the serpentine duct is commonly employed for military aircraft to block the front of the jet engine from radar. However, delivering a non-uniformly distorted flow to the engine face (aerodynamic interface plane, AIP) though a serpentine duct is inevitable due to the existence of flow separation and swirl flow in the duct. The effect of distortion is to cause the engine compressor to surge; thus, it may impact on the life-cycle of aircraft engine. In this study, aerodynamic characteristics of a serpentine duct mounted on a blended-wing-body (BWB) aircraft was thoroughly investigated to determine where and how the vortex flow was generated. In particular, both passive and active flow control were implemented at a place where the flow separation was occurred to minimize the flow distortion rate in the duct. The passive and active flow control systems were used with vortex generator (VG) vanes and air suctions, respectively. A pair of VG s have been made as a set, and 6 sets of VG in the serpentine duct. For the active flow control, 19 air suctions have been implemented. Both flow control devices have been placed in three different locations. To evaluate the performance of flow control system, it is necessary to quantify the flow uniformity at the AIP. Therefore, coefficient of distortion, DC(60) was used as the quantitative measure of distortion. Also, change in DC(60) value while the BWB aircraft is maneuvering phase was analyzed.
Accelerated Creep Test (ACT) Qualification of Creep-Resistance Using the WCS Constitutive Model and Stepped Isostress Method (SSM)
Authors: Cano Jaime A. , Stewart Calvin M. 
Published: September 2021

Abstract
In this study, a qualification of accelerated creep-resistance of Inconel 718 is assessed using the novel Wilshire-Cano-Stewart (WCS) model and the stepped isostress method (SSM) and predictions are made to conventional creep data. Conventional creep testing (CCT) is a long-term continuous process, in fact, the ASME B&PV III requires that 10,000+ hours of experiments must be conducted to each heat for materials employed in boilers and/or pressure vessel components. This process is costly and not feasible for rapid development of new materials. As an alternative, accelerated creep testing techniques have been developed to reduce the time needed to characterize the creep resistance of materials. Most techniques are based upon the time-temperature-stress superposition principle (TTSSP) that predicts minimum-creep-strain-rate (MCSR) and stress-rupture behaviors but lack the ability to predict creep deformation and consider deformation mechanisms that occur for experiments of longer duration. The stepped isostress method (SSM) has been developed which enables the prediction of creep deformation response as well as reduce the time needed for qualification of materials. The SSM approach has been successful for polymer, polymeric composites, and recently has been introduced for metals. In this study, the WCS constitutive model, calibrated to SSM test data, qualifies the creep resistance of Inconel 718 at 750°C and predictions are compared to CCT data. The WCS model has proven to make long-term predictions for stress-rupture, minimum-creep-strain-rate (MCSR), creep deformation, and damage in metallic materials. The SSM varies stress levels after time interval adding damage to the material, which can be tracked by the WCS model. The SSM data is calibrated into the model and the WCS model generates realistic predictions of stress-rupture, MSCR, damage, and creep deformation. The calibrated material constants are used to generate predictions of stress-rupture and are post-audit validated using the National Institute of Material Science (NIMS) database. Similarly, the MCSR predictions are compared from previous studies. Finally the creep deformation predictions are compared with real data and is determined that the results are well in between the expected boundaries. Material characterization and mechanical properties can be determined at a faster rate and with a more cost-effective method. This is beneficial for multiple applications such as in additive manufacturing, composites, spacecraft, and Industrial Gas Turbines (IGT).
Effects of Eight Methods and Five Steps of Tai Chi Practice on Balance Control Among Older Adults
Authors: Hu Xiu , Lyu Shaojun , Mao Min , Zhang Jianwei , Sun Wei , Zhang Cui , Song Qipeng 
Published: September 2021

The team developed the newly compiled eight methods and five steps of Tai Chi (EMFSTC), which includes introductory routines to Tai Chi characterized by simple structures. This study examined the effectiveness of EMFSTC practice on balance control. A total of 31 participants were randomly assigned to EMFSTC (n = 15, age = 66.4 ± 1.7 years, received 16-week EMFSTC practice) or control (n = 16, age = 66.7 ± 1.8 years, received no practice) groups. Significant group by training interactions were observed. After EMFSTC practice, balance control improved, as indicated by decreased root mean square and mean velocity of center of pressure, proprioception threshold during knee extension, and plantar tactile sensitivity threshold at the arch. EMFSCT can be an effective rehabilitation modality to improve balance control among older adults.
Social evolution in mammals
Authors: Clutton-Brock Tim 
Published: September 2021

Mammal societies
Although a few types of structures prevail, social systems among mammals are relatively varied. New techniques, from monitoring to genetics, have allowed for a deeper understanding of this variation, how it is related to the environment, and how it has evolved. Clutton-Brock reviews the forms of and drivers of the different types of breeding systems and how they have been shaped by ecology and history. The author discusses how mammalian social interactions may be affected by human activities that are driving environmental change. —SNV
Crustal deformation and exhumation within the India-Eurasia oblique convergence zone: New insights from the Ailao Shan-Red River shear zone
Authors: Zhang B. , Chen S.Y. , Wang Y. , Reiners P.W. , Cai F.L. , Speranza F. , Zhang J.J. , Zhong D.L. , Liu K. 
Published: September 2021

Abstract
During the collision of India and Eurasia, regional-scale strike-slip shear zones played a key role in accommodating lateral extrusion of blocks, block rotation, and vertical exhumation of metamorphic rocks as presented by deformation on the Ailao Shan-Red River shear zone (ARSZ) in the Eastern Himalayan Syntaxis region and western Yunnan, China. We report structural, mica Ar/Ar, apatite fission-track (AFT), and apatite (U-Th)/He (AHe) data from the Diancangshan massif in the middle segment of the ARSZ. These structural data reveal that the massif forms a region-scale antiform, bordered by two branches of the ARSZ along its eastern and western margins. Structural evidence for partial melting in the horizontal mylonites in the gneiss core document that the gneiss experienced a horizontal shear deformation in the middle crust. Muscovite Ar/Ar ages of 36–29 Ma from the core represent cooling ages. Muscovite Ar/Ar ages of 25 and 17 Ma from greenschist-facies mylonites along the western and southern shear zones, respectively, are interpreted as recording deformation in the ARSZ. The AFT ages, ranging from 15 to 5 Ma, represent a quiescent gap with a slow cooling/exhumation in the massif. AHe results suggest that a rapid cooling and final exhumation episode of the massif could have started before 3.2 Ma, or likely ca. 5 Ma, and continue to the present. The high-temperature horizontal shearing layers of the core were first formed across the Indochina Block, locally antiformed along the tectonic boundaries, and then cooled through the mica Ar-Ar closure temperature during Eocene or early Oligocene, subsequently reworked and further exhumed by sinistral strike-slip movement along the ARSZ during the early Oligocene (ca. 29 Ma), lasting until ca. 17 Ma, then final exhumation of the massif occurred by dextral normal faulting on the Weixi-Qiaohou and Red River faults along the limbs of the ARSZ since ca. 5 Ma. The formation of the antiform could indicate local crustal thickening in an early transpressional setting corresponding to India-Asia convergence. Large-scale sinistral ductile shear along the ARSZ in the shallow crust accommodated lateral extrusion of the Indochina Block, and further contributed to the vertical exhumation of the metamorphic massif from the late Oligocene to the middle Miocene. Furthermore, the change of kinematic reversal and associated cooling episodes along the ARSZ since the middle Miocene or early Pliocene imply a tectonic transfer from strain localization along the major tectonic boundaries to continuous deformation corresponding to plateau growth and expansion.