bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the Sick Father, the Repentant Sinner, and Other Problems in Medieval Deontic Logic
Authors: Hilpinen Risto 
Published: November 2019

AbstractMany medieval philosophers and logicians regarded modal logic as a model for epistemic, normative and optative concepts on the basis of their apparent similarities to modal concepts. These interpretations of modal logic led to critical studies of the applicability of modal principles to deontic concepts. Some philosophers presented apparent counterexamples to the deontic interpretation of the Consequence Principle, according to which the consequences of what is obligatory (or permitted) are also obligatory (permitted). These examples are variants of Lennart Åqvist's paradox of the Good Samaritan. In this article it is argued that the examples involve a confusion between the compounded and the divided senses of deontic propositions, and are not genuine counterexamples to the Consequence Principle. If the concept of knowledge is analysed as epistemically satisfactory belief, the paradox of epistemic obligation can be solved in a similar way.
Consumption and exchange rate uncertainty: Evidence from selected Asian countries
Authors: Iyke Bernard Njindan , Ho Sin‐Yu 
Published: November 2019

AbstractWe set out to assess the effects of exchange rate uncertainty on real consumption in selected Asian countries. Consumption influences business cycles, which in turn shape short‐run monetary policy decisions. Hence, understanding factors driving consumption is appealing to policymakers. To date, few studies have analysed the effects of uncertainty on consumption. The available ones generally focus on the long‐run effects, in spite of the fact that the short‐run persistence and adjustments to equilibrium are equally relevant. Our study takes these limitations seriously by distinguishing the short‐ and long‐run effects of exchange rate uncertainty on consumption. Using a flexible dynamic panel data technique that allows long‐run effects to be homogeneous and the short‐run effects to be heterogeneous, we find that uncertainty impedes consumption in the long run. In the short run, however, the effects are immaterial. This evidence remains robust to the measure of uncertainty, asymmetric uncertainty, inflation and the global financial crisis of 2008. By decomposing uncertainty into its temporary and permanent components, we find that the latter have a stronger effect on consumption in the long run than the former. Although both components demand policy attention, the evidence suggests that policymakers should be more concerned with permanent uncertainty.
Fabrication of porous bovine pericardium scaffolds incorporated with bFGF for tissue engineering applications
Authors: Liu Xiaohong , Wu Hao , Lu Fanglin , Li Qin , Xu Zhiyun 
Published: November 2019

AbstractBackgroundThe design and fabrication of porous scaffolds are important issues for tissue engineering applications. In this study, we attempted to fabricate porous scaffolds using bovine pericardium (BP) and examined whether these scaffolds were beneficial for cell ingrowth and bioactive factors delivery.MethodsA vacuum‐freeze‐thawing‐Triton X‐100 (VFTT) protocol was used to fabricate porous BP scaffolds. The porous and mechanical properties were assessed using histology, scanning electron microscopy, and mechanical assay. The fabricated scaffolds were seeded with mesenchymal stem cells (MSCs), and cell ingrowth was evaluated. Basic fibroblast growth factor (bFGF) was subsequently incorporated into the fabricated scaffolds. The bioactive factor delivery capacity was evaluated using loading and release studies. The bioactivity of released bFGF was assessed using a rat subcutaneous model.ResultsThe BP scaffolds fabricated by the VFTT protocol displayed interconnected porous structures with porosity of 6.82 ± 1.36%.There were no significant differences in thickness, ultimate load, Young's modulus, and ultimate tensile strength between the fabricated porous BP scaffolds and native BPs (all P > .05). However, the water content of BPs was slightly reduced after VFTT treatment (P < .05). Cell ingrowth analysis showed that the seeded MSCs penetrated into the porous BP scaffolds with time of culture, while MSCs were limited to the surface layers of native BPs. Furthermore, bFGF was observed to be effectively loaded onto and released from the porous BP scaffolds. The released bFGF increased the phosphorylation levels of Akt, ERK 1/2, and MEK1/2, promoted host MSC recruitment, and inhibited myofibroblast differentiation in vivo.ConclusionsThe porous BP scaffolds fabricated using a VFTT protocol were promising natural scaffolds for tissue engineering applications, since they had considerable mechanical properties as native BPs, supplied porous channels for cell ingrowth, and possessed bioactive factors delivery capability.
Arterial and venous cerebral blood flow responses to long‐term head‐down bed rest in male volunteers
Authors: Ogoh Shigehiko , Sato Kohei , de Abreu Steven , Denise Pierre , Normand Hervé 
Published: November 2019

New Findings
What is the central question of this study?
A heterogeneous cerebral blood flow (CBF) response in the cerebral arteries has been demonstrated in several physiological conditions, and it might be attributable to different physiological properties. However, the whole cerebral haemodynamic response to weightlessness remains unknown.

What is the main finding and its importance?
Long‐term head‐down bed rest caused a heterogeneous CBF response between the anterior and posterior cerebral arteries and between the cerebral arteries and veins. Especially, in contrast to the anterior cerebral circulation, the posterior arterial and venous CBFs were well maintained throughout weightlessness.

AbstractIn this study, we investigated the whole cerebral haemodynamic response to long‐term head‐down bed rest (HDBR). We hypothesized that long‐term exposure to weightlessness influences cerebral blood flow (CBF) or CBF distribution among cerebral arteries and veins because of the different physiological roles of each cerebral vessel. To test this hypothesis, 10 male volunteers were exposed to −6 deg HDBR for 60 days. Blood flows in the internal carotid artery, external carotid artery and vertebral artery or internal jugular vein and vertebral vein were measured using ultrasonography before and on days 30 and 57 of the HDBR. The internal carotid artery blood flow was reduced on day 30 (P = 0.019) and had returned to the baseline level by day 57. In contrast, the vertebral artery blood flow remained unaltered throughout the HDBR (P = 0.626). The internal jugular vein blood flow was reduced on day 30 (P = 0.009), whereas the vertebral vein blood flow remained unaltered (P = 0.397). These findings suggest that long‐term HDBR causes a heterogeneous CBF response between the anterior and posterior cerebral circulation in the both arteries and veins. The posterior arterial and venous CBFs were well maintained throughout HDBR, and these CBF responses to HDBR were different from the anterior cerebral circulation.
Design and Experimental Validation of Two Cam-Based Force Regulation Mechanisms
Authors: Li Ming , Cheng Wei , Xie Ruili 
Published: November 2019

Abstract
This paper presents the design and experimental validation of two force regulation mechanisms (FRMs) containing a translational cam and a rotational cam, respectively. With the friction-considered profile identification method (FCPIM) to define the cam and through the squeezing between the cam and the spring-supported slider, the FRMs can passively output the desired force over the designed displacement. Under the premise of that the friction coefficient can be accurately obtained, the friction-considered design principle will be significant for the realization of FRMs in actual applications since it is no longer necessary to achieve high accuracy by pursuing the frictionless condition. Hence, the conventional materials and mechanical parts can be directly used to assemble the FRMs without sacrificing the force regulating accuracy. We are highly interested in the actual experimental behavior of the proposed FRMs under the friction-considered condition. Then, prototypes of the two FRMs capable of outputting multiple types of forces including in zero-stiffness, positive and negative stiffness are specially designed, fabricated, and tested quasi-statically. The experimental results verify the correctness of FCPIM since they agree with the design objective well. Meanwhile, the effectiveness of the FCPIM is proved as the errors of the experimental results considering friction is much lower than those ignoring friction. The experiments also show that the noise phenomenon in the testing curves that may affect the judgment of test accuracy can be highly degraded by using more stable and controllable loading tools, which is helpful for future research.
Aero-Thermal Investigation of Convective and Radiative Heat Transfer on Active Clearance Control Manifolds
Authors: Da Soghe Riccardo , Bianchini Cosimo 
Published: November 2019

Abstract
The present paper deals with the characterization of heat transfer on blade tip Active Clearance Control manifolds. Real engine geometries and operating conditions were considered in validated CFD computations to understand the impacts of both manifold surfaces convective and radiative heat transfer on the aero-thermal performance of the system. Different manifold geometries were accounted for also.
The study sorted out that both the radiation and the convective heat transfer on the manifold surfaces are responsible of performance deteriorations as the impingement heat transfer on the casing is considered. The last evidence is motivated by the fresh fluid heat up along the feeding pipe. Radiative heat transfer from the casing to the manifold is found to be relevant, especially in case of high casing temperature or low undercowl flow rates. As a result of the study, is remarked that ACC manifold radiative and convective heat transfer should be considered for a proper system design.
3D Computational Loss Analysis of a Compressor for Heavy Duty Truck Engine Turbochargers
Authors: Abel Matthias , Martinez-Botas Ricardo F. , Wöhr Michael , Müller Markus , Leweux Johannes 
Published: November 2019

Abstract
This paper presents a detailed loss analysis of a centrifugal compressor stage with a vaned diffuser for application in a heavy duty engine turbocharger. The analysis is carried out in order to investigate the loss distribution in the stage. To quantify the impact of different loss types and locations, a detailed validated steady-state 3D CFD solution is employed. The local entropy production rate is calculated for two operating points (full load and part load), which are most relevant to the real world operation of the compressor in a truck application. Two methods are suggested as the procedure for the division of the whole fluid volume into sub-volumes, because this is key for the resulting loss distribution.
The primary loss generating mechanisms are shown at main operating conditions to reveal the regions of improvement. A detailed grid study was conducted to enable the calculation of the entropy ratio. It was possible to capture around 78% (partial load) and 70% (full load) of the entropy production with a mesh with circa 100 million elements. Around half of the losses were due to the boundary layer friction, followed by losses associated with a boundary layer separation resulting from the back-flow at the shroud contour close to the impeller exit and back disk friction accounted for with 6–7% of the stage’s losses.
Determination of Simultaneous Steady-State Movements Using Blade Tip Timing Data
Authors: Mohamed Mohamed , Bonello Philip , Russhard Peter 
Published: November 2019

Abstract
Blade tip timing (BTT) includes a number of uncertainties that discourage its use. One of the main ones is the shift in the equilibrium position of the blade tip due to steady (non-oscillatory) bending and/or twisting of the blade, and axial movement of the bladed disk (blisk)-shaft system. This results in a shift in the effective measurement position of the probe relative to the blade chord, resulting in errors in the tip vibration measurement which can translate to a huge error in the corresponding stress estimate, which relies on calibration against finite element (FE) models. Previous experimentally validated research by the authors introduced a method for quantifying steady movement of a single type (axial, lean, or untwist), using BTT data from not more than two probes. In this paper, a development of the previous method is presented that provides a solution for the case of simultaneous types of blade steady movements. Additional probes are used for determining the direction, but these can be placed at any angular positions. The developed method is validated using a BTT simulator of a blisk, and accurate results obtained. The simultaneous axial and lean movements can be accurately determined when the untwist is negligible, and an uncertainty level can be specified when the untwist is not negligible. The untwist itself can be calculated accurately in all cases of simultaneous movements. Guidelines for the use of the method in different scenarios are provided.
A General Diagnostic Methodology for Sensor Fault Detection, Classification and Overall Health State Assessment
Authors: Manservigi Lucrezia , Venturini Mauro , Ceschini Giuseppe Fabio , Bechini Giovanni , Losi Enzo 
Published: November 2019

Abstract
Sensor fault detection and classification is a key challenge for machine monitoring and diagnostics. To this purpose, a comprehensive approach for Detection, Classification and Integrated Diagnostics of Gas Turbine Sensors (named DCIDS), previously developed by the authors, is improved in this paper to detect and classify different fault classes. For a single sensor or redundant/correlated sensors, the improved diagnostic tool, called I-DCIDS, can identify seven classes of fault, i.e. out of range, stuck signal, dithering, standard deviation, trend coherence, spike and bias. Fault detection is performed by means of basic mathematical laws that require some user-defined input parameters, i.e. acceptability thresholds and windows of observation.
This paper presents in detail the I-DCIDS methodology for sensor fault detection and classification. Moreover, this paper reports some examples of application of the methodology to simulated data to highlight its capability to detect sensor faults which can be commonly encountered in field applications.
Turbocharger Turbine Rotor Design for Low U/C Values
Authors: Chen Hua , Song Yuchao , Gu Aiguo , Zhang Yangfang , Li Hongwei 
Published: November 2019

Abstract
Emission regulations worldwide demand better low-end torque from internal combustion engines. This pushes the operating condition of turbocharger turbine to lower U/C values, where U is the blade tip speed and C is the turbine isentropic spouting velocity which increases with turbine expansion ratio. Traditional radial and some mixed flow turbines, dictated by their rotor design, have their efficiency peaks at U/C value around 0.70, a value considerably larger than desired. In this paper, we deliberate the measures to shift the peak efficiency of turbine rotor toward a lower U/C value than 0.7. The underlying physics of these measures are first explained, CFD and test results where available are then given. Implications to mechanical design, manufacturing and others are also discussed. Finally, an example of a turbine rotor design is given implementing these measures. Test results showed better efficiency was obtained from the design at lower U/C values than from the baseline.
Numerical Research on the Toroidal Shock Wave Focusing Detonation Initiation
Authors: Chen Xiang , Zhao Ningbo , Zheng Hongtao , Jia Xiongbin , Liu Shizheng , Liu Qingbo 
Published: November 2019

Abstract
Pressure gain combustion (PGC) is considered to be a potential technology to increase the cycle efficiency of gas turbine. As one viable candidate for PGC, rotating detonation engine (RDE) draws more attention due to its significant advances in continuous mode of operation. In practical, one of the basic challenges for RDE application is to reliably initiate detonation wave. For this purpose, both detonation initiation mechanism and enhancement approach are urgently needed to be understood. In this work, a toroidal shock wave focusing detonation initiator is presented. On this basis, the two-dimensional numerical simulations are carried out to investigate the detonation initiation characteristics by using the toroidal shock wave focusing. All of the flame acceleration, shock wave focusing, detonation wave forming and propagation are analyzed in detail. The numerical results show that the toroidal shock wave focusing initiator developed in this study can rapidly realize the detonation initiation over a short distance and performs significantly better than the traditional smooth or obstructed tube based imitators under different operating conditions. Under the same operating condition, the novel developed initiator decreases time of 59.2% and distance of 84.7% for the smooth tube based initiator, and time of 52% and distance of 78.9% for the obstructed one. Besides, the multi-fields analysis indicates that both the local explosion induced by shock wave focusing in concave cavity and the entrainment vortex generated by shock wave and jet flame in front of diaphragm are important mechanisms to initiate detonation wave. The present study is expected to enhance the understanding of the physical mechanism of shock wave focusing detonation initiation and contribute to the development of detonation propulsion technology.
Aerodynamic Numerical Investigation of Low-Pressure Steam Turbine Last Stage Under Low Load Conditions With Mode Decomposition Methods
Authors: Hu Ping , Lin Tong , Yang Rui , Zhu Xiaocheng , Du Zhaohui 
Published: November 2019

Abstract
It is common that steam turbine works at different operating points, especially under low load conditions, to cater to complex and varied demands for power generation recently. Considering the long and thin shape of last stage moving blades (LSMBs) in a low-pressure (LP) steam turbine, there are many challenges to design a suitable case which balances global efficiency against sufficient structure strength when suffering excitations at low load operating points. In present work, the aim is to extract specific aerodynamic excitations and recognize their distribution and propagation features. Firstly, steady 3D computational fluid dynamics (CFD) calculations are simulated at 25GV and 17GV (25% and 17% of design mass flow conditions) and corresponding unsteady calculations are performed with enough rotor revolutions to obtain integrated flow periodicities. Unsteady pressure signals near tip region of LSMBs are monitored circumferentially in both static and rotating coordinates. The fast Fourier transformation (FFT) results of unsteady pressure signals show that there are broadband humps with small disturbance amplitudes in low frequency spectrum at 25GV, however, a sharp spike is shown in low frequency spectrum at 17GV. Further, circumferential mode decomposition (CMD) method has been applied to distinguish different fluctuations in frequency and the mode numbers and circumferential propagating pace of which have been obtained. Finally, dynamic mode decomposition (DMD) method has been performed to describe detailed mode shapes of featured flow perturbances both in static and rotating coordinate system. These analyses indicate that at 25GV, a band of unsteady responses with very low amplitude was noted which has some features similar to rotating instability (RI). However, distribution and propagation features of flow unsteadiness at 17GV are in good agreement with rotating stall (RS) in compressor.
Detailed Heat Transfer Coefficient Measurements on a Scaled Realistic Turbine Blade Internal Cooling System
Authors: Shiau Chao-Cheng , Chen Andrew F. , Han Je-Chin , Krewinkel Robert 
Published: November 2019

Abstract
A realistic internal cooling system of a turbine blade includes both ribs and pin-fins inside the passages to enhance the heat transfer. However, the majority studies in the open literature assessing the heat transfer characteristics on a simplified cooling model by examining ribbed-roughen passages and pin-finned passage separately. This work presents the high-resolution heat transfer coefficients of a scaled realistic turbine blade internal cooling design. The cooling system, using a 3D-printed plastic material, consists of an S-shaped inlet, four serpentine passages (three U-bends) of variable aspect ratio, and the trailing edge ejection. Angled ribs are implemented inside the passages and the elongated fins and pins are used near the trailing edge. Two dust holes are realized on the blade tip, the injections are individually controlled to reflect the realistic coolant flow rate variation inside the entire internal cooling system. The tests are conducted at two Reynolds number, 45,000 and 60,000 based on the hydraulic diameter of the inlet passage. Transient heat transfer technique using thermochromic liquid crystal is applied to obtain the detailed heat transfer characteristic inside the cooling channel. The local and averaged Nusselt numbers are also compared with the correlations in the open literature. This paper provides gas turbine designers the difference of local heat transfer distributions between the realistic and simplified internal cooling designs.
A Model for System Instability Analysis in a Multi-Stage Intercooled Industrial Compressor
Authors: Gan Jiaye , Abdelwahab Ahmed , Kilchyk Viktor 
Published: November 2019

Abstract
Compression equipment used for industrial applications are typically comprised of multi-stage intercooled compressor stages. The presence of large volume intercoolers between individual stages adds a layer of complexity currently not present in publicly available surge models both in terms of system behavior and recovery analysis. In this work a compressible, temporal, and spatial model is developed in which the conservation equations are solved numerically for each of the system components, i.e. pipes, plenums and heat exchangers, valves, and individual compressor stages. The model can identify the onset of instability on an individual stage basis as well as the switching that can occur between the controlling stages of the instability onset when the operating conditions change, e.g. changes in inlet conditions, intercooler fouling or cooling tower performance reduction, and speed or guide vane changes. The model is therefore used both as a stage stacking model during the compressor stable operation as well as a model of the transient behavior of the system past the stable operation. An inertial model of the compressor drive train is also incorporated to analyze the effects of power transients, e.g. emergency shut down (ESD), on the system behavior. In this article details of the developed model are provided. Several test cases are presented. The model is then used to demonstrate the proper sizing of a vent valve of a base load compressor to meet the required system response specification in a surge event. The developed model represents an improvement over available transient system models in terms of predicting the post stable behavior of multi-stage intercooled compressors.