bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical Study on Flow Physics of Damaged Vane Trailing Edge
Authors: Thammachote B , Premyothin J , Khumhaeng S , Tanpradit D , Dipasquale D , Prapamonthon P 
Published: June 2024

Abstract
According to practical applications in gas turbines, the turbine’s nozzle guide vane (NGV) is the first downstream component of the combustor that experiences high thermal loads from burned gases. This situation can severely damage the vane material, particularly the trailing edge (TE). This is because of the limitation of TE thickness and the difficulty of effective cooling in that region. Moreover, the deterioration of the TE surface leads to vane fatalities and has a negative impact on turbine performance because the flow field is unfavorably changed during the operation. This paper aims to numerically study the flow physics of a damaged vane TE using a 3D steady-flow CFD simulation with the SST k-turbulence model. Under the assumptions of ideal gas and compressible flow, air is used as the burned gas. To simplify the vane damage shape, the broken pattern at the TE is given in a long cutback geometry in the simulation. Numerical results in terms of turbulent kinetic energy (TKE), vorticity magnitude, turbulent viscosity, and streamlines are compared and discussed. The interesting findings show that with the inclusion of the damaged TE, the TKE and turbulent viscosity in the broken region increase dramatically on both the midspan and vertical planes. Furthermore, an increment in the vortex size is observed on the midspan plane. However, the vortex centers along the broken region disappear and are replaced by smooth streamlines.
Optimizing the control strategy of redundant motor-inverter systems for aircraft propulsion application
Authors: Staudacher M , Kallo J , Willich C , Bauer C 
Published: June 2024

Abstract
Propulsion systems based on e-motor/inverter systems e.g. for operation of fuel cell battery hybrid powertrains are a key technology for enabling all electric aircraft. The efficiency of e-motor/inverter systems depends strongly on system design and control strategy. Two redundant motor systems were examined: one based on a direct-drive-system and the other based on a gear-drive-system. The study is based on the data of a previously performed manned flight of a 120 kW propulsion system. The flight data was used to test in a laboratory under real flight conditions. The study examines the energy utilization rate of the two motor systems along the flight profiles phases take-off, climb and cruise. An optimized control strategy with variable power distribution between the redundant e-motor/inverter systems for the gear-drive-system demonstrated a possible increase in energy efficiency of 2% over the duration of the tested flight profile. For the direct-drive system further optimization potential by changing the ratio of motor speed and torque for the same power was identified.
Design and Application of Servicing Method for Extravehicular Payload of Manned Spacecraft
Authors: Zhao Zhenhao , Yin Zhao , Yang Xinhai , Cheng Zhao , Yin Wang , Liu Yanwei 
Published: June 2024

Abstract
Aiming at the servicing requirements of extravehicular payloads for manned spacecraft, on the basis of comparative analysis of servicing extravehicular payloads methods for manned spacecraft, combined with the design of extravehicular payload support system, a servicing extravehicular payload method based on space manipulator operation is proposed in this paper. At the same time, the method of eliminating the position and attitude errors of space manipulator operation is given, and the servicing process for extravehicular payloads in the whole life cycle is developed. This method avoids the risk of EVA, reduces the work burden of astronauts, greatly improves the payload support efficiency of manned spacecraft, and has been successfully applied in practice.
Application of Adjoint Aerodynamics Optimization for a High-Speed Vehicle Moving in a Tube
Authors: Abdulla Mohammed , Alzhrani Seraj , Juhany Khalid A , AlQadi Ibraheem 
Published: June 2024

Abstract
This work explores the application of adjoint-based optimization for a self-propelled vehicle moving in a tube at a low-pressure of 10 KPa with a small suspension gap (d) between the vehicle and the tube. The objective is to minimize the drag force for air-ingested vehicles. The thrust was a design constraint to maintain the cruise conditions. The nose and tail parts of the model were parametrized using elliptical approximation. Gradient-based optimization was utilized in the adjoint-based optimization to deform the vehicle’s external shape. The optimization remarkably enhanced the aerodynamic vehicle’s performance by eliminating of shock waves and flow separation observed in the baseline design. As a result, a reduction of ~13% in drag force was achieved. The study shows that adjoint-based optimization provides a robust tool for enhancing the performance of the vehicle-tube system.
Experiment research on regression rate of aluminized solid propellant with HMX using reconstruction techniques
Authors: Wei T F , Cai G B , Tian H , Lu Y D , Niu X T 
Published: June 2024

Abstract
In this research, a firing test was conducted on a Hybrid Rocket Motor (HRM) that operates using an aluminized solid propellant containing HMX and Hydrogen Peroxide (HP). The instantaneous regression rate of HRM is determined using reconstruction techniques, and the formula of regression rate is fitted by reconstruction techniques and traditional weight-loss method. The utilization of the reconstruction method presents a notable advantage, as it allows for the determination of the regression rate’s sensitivity to variations in oxidizer mass flux. Additionally, this method enables the fitting of the regression rate formula based on data obtained from a single firing test. The average value of regression rate of four times firing test are 0.944, 0.529, 0.595 and 0.486 mm/s. According to the weight-loss method and reconstruction techniques, the coefficients of determination (R2
) of regression rate formula fitting are 0.8867 and 0.93 respectively, indicating that the accuracy of the fitting is better than that of traditional method. Overall, this paper presents a comparison of traditional weight-loss method and reconstruction techniques for providing a critical preference for the research of regression rate of HRM.
Minimum-fuel low-thrust trajectory optimization using adaptive wavelet collocation and sequential convex programming
Authors: Qian Changzheng , Cui Hutao , Zhao Yang , Ma Wenlai , Liang Lei 
Published: June 2024

Abstract
The minimum-fuel transfer problem is a common challenge encountered in low-thrust orbit trajectory optimization, typically solved with Bang-Bang control solution. This paper proposes a novel approach to solve the optimization problem by employing an adaptive wavelet collocation method for grid refinement and a synergistic integration of sequential convex programming, which results in an effective and precise solution methodology. The method introduces a spline wavelet to convert the infinite-dimensional state and control variable into finite dimensions. The dynamic nonlinear programming (NLP) problem is then convexified and linearized into a second-order cone programming (SOCP) problem using a small perturbation method, which can be rapidly solved by convex optimization tools. By iteratively solving the sequential SOCP problems, state and control variables converge quickly and accurately to the optimal control solution. A numerical simulation of a low-thrust transfer trajectory from Earth to Mars is performed to demonstrate the effectiveness of the proposed method. The results show that the adaptive method achieves higher accuracy in determining the switching time compared to conventional methods.
Temperature Dependent Photocatalytic Activity of Bifeo3 Nanoparticles by Sol Gel Method
Authors: Thorat S M , Kakade S B , Kalange A E 
Published: June 2024

Abstract
The synthesis of ethylene glycol (EG) based Bismuth Ferrite (BiFeO3) (BFO) nanoparticles were carried out with molar ratio of Bi:Fe as 1:1 annealed at different temperatures for 4 h by auto combustion sol-gel technique. The purity of phase, crystal structure and microstructure of sample was examined by using X-ray Diffraction Spectrometer (XRD) and Field Emission Scanning Electron microscopy (FESEM). The obtained results of XRD pattern of BFO demonstrated the presence of rhombohedral phase and perovskite crystal structure. The FESEM micrograph of synthesized sample gave brief picture of structure pattern of BiFeO3 nanoparticles which follows an agglomerated form with nearly spherical morphology. The presence of different functional groups in sample was examined by using Fourier Transform Infrared spectroscopy (FT-IR). The energy band gap of BFO was investigated by using UV-Visible absorbance spectroscopy. The stability of sample under various temperatures was investigated by using thermo gravimetric and differential scanning calorimetry (TGA-DSC). Further the photocatalytic activity of BiFeO3 nanoparticles was investigated by observing through degradation of methylene blue in an aqueous solution under incident visible light. In this study, the photocatalytic mechanism of BFO is proposed through the computation of band position and various indicative experiments. It was observed that produced hydroxyl radicals from electron hole pairs were the major reactive species accountable for the pollutant decomposition. In addition, with variation of the annealing temperature, crystallinity and mean crystallite size of BFO sample could be changed which in turn affected the photocatalytic performance of the corresponding samples.
Conductivity and Bandgap Engineering in PVA-TiO2 Nanocomposites for Optoelectronic Device Applications
Authors: Venugopal R , Srinivas CH 
Published: June 2024

Abstract
This study investigates the structural, electrical, and optical properties of polyvinyl alcohol (PVA) and Titanium Dioxide(TiO2) NC films. The PVA-TiO2 NC films were prepared using a simple solution casting method, with varying concentrations of TiO2 nanoparticles. The structural analysis revealed the incorporation of TiO2 nanoparticles into the PVA matrix, resulting in a uniform dispersion and improved crystallinity. SEM micrographs demonstrated the uniform dispersion of TiO2 nanoparticles in the PVA matrix. FTIR spectroscopy indicated interaction between TiO2 nanoparticles and the PVA matrix through -OH functional groups. The electrical properties were assessed through DC electrical conductivity studies, which showed an increase in conductivity with increasing TiO2 concentration. The optical properties were characterized using UV-Vis spectroscopy, indicating a significant enhancement in the absorption and transmittance properties of the films with the incorporation of TiO2 nanoparticles. A significant peak of absorption was observed at a wavelength of 225 nm for the nanocomposite films incorporating 8.0 wt.% TiO2 into PVA. The incorporation of 8.0 wt.% TiO2 NPs in PVA polymer led to notable alterations in the direct bandgap, with a decrease from 6.09 eV to 5.28 eV, as well as in the indirect bandgap, with a decrease from 5.53 eV to 4.64 eV. Additionally, the Urbach energy decreased from 0.82 eV to 0.548 eV. Among the samples, the one with 8.0 wt.% TiO2 exhibited the highest DC electrical conductivity at 338 K, measuring 5.59x10−13 Scm−1, and at 393 K, measuring 4.01x10−8 Scm−1. The PVA-TiO2 NC films exhibited excellent potential for applications in optoelectronic devices due to their enhanced electrical and optical properties. UV-Vis spectroscopic studies revealed that these nanocomposites can be utilized in UV-shielding and optoelectronics devices. There is significant room for further study of these materials for potential applications.
Topology optimization study of interior door hinge
Authors: Wu Ming , Liu Wen , Song Yidan , Lu Jintong , Guo Qiong 
Published: June 2024

Abstract
As a crucial element in architectural design, interior doors play a vital role with their hinges connecting the door panel and door frame. Traditional designs face challenges such as insufficient strength, material waste, and aesthetics. This study introduces the Bi-Directional Evolutionary Structural Optimization (BESO) algorithm, exploring the improvement of interior door hinge structures based on structural performance. The process involves grid partitioning, constraint conditions, load analysis, structural simulation, material settings, and iterative form generation. While ensuring structural strength, the algorithm reduces material usage, prolongs the lifespan, and enhances economic efficiency. The proposed design practice validates the feasibility of applying this algorithm. Utilizing the Ameba plugin on the Grasshopper platform, the operation is user-friendly, providing a new direction and perspective for the algorithm’s diverse applications in various fields.
Determining the tectonic velocity of some continuously operating reference stations (CORS) in Vietnam 2019-2022 using precise point positioning method
Authors: Lau Nguyen Ngoc , Dinh Vu Trinh 
Published: June 2024

Abstract
We use precise point positioning (PPP) technique to process the Global Navigation Satellite Systems (GNSS) data of 10 continuously operating reference stations (CORS) in Vietnam during the period 2019-2022. PPP processing results show that the time series of the North, East and Up components of CORS fluctuate with a period of approximately 1 year. After modelling this variation using a sine function with a fixed period of 351.6 days, we calculate the mean displacement velocity of the CORSs according to the North, East and Up components as follows: (-9.2, +29.5, -4.6) mm/year. The general movement direction of all CORSs is East-Southeast. In which the North, East and Up components of 3 big cities Ha Noi, Da Nang and Ho Chi Minh city are (-9.1, +32.7, +1.0) mm/year, (-9.1, +30.5, -6.0) mm/year and (-7.9, +28.4, -1.9) mm/year, respectively. Compared with the period 2016-2018, the velocities of the tectonic plate change less than 4 mm/year in the horizontal component, and 8 mm/year in the Up component. We have processed three more International GNSS Service (IGS) stations in Thailand (CUSV) and China (HKSL and KMNM) for testing. Our results are consistent with JPL at 1 mm/year in the horizontal and 2 mm/year in the Up component.
Inventory and classification of geosites in the South-Central Coast of Vietnam
Authors: Chi Hoang Thi Phuong , Hai Ha Quang 
Published: June 2024

Abstract
The establishment of a connection to sustainability is evident through the expansion of the Global Geoparks network and geotourism initiatives, emphasizing the protection of geodiversity alongside biodiversity conservation. The outcomes of the geosite inventory laid the foundation for the development of the geopark. In the South-Central Coast of Vietnam, characterized by its small and narrow area, intricate tectonic structure, distinctive topography, and unique climate, where conservation efforts are yet to be initiated, the geosite inventory assumes particular significance. The geosite inventory was conducted using four research approaches, which are as follows: 1) Studying documents on geosite inventory, geological and geomorphological investigation documents; 2) Field survey; 3) Expert methods and 4) GIS techniques. The results of the inventory demonstrate how diverse the geosite types and geometries are along Vietnam South-Central Coast. The research findings reveal a total of 90 geosites distributed among 10 geo-theme groups, categorized into 5 types: area, section, point, viewpoint, and complex. These geosites align with 5 primary scientific interests, encompassing tectonics, lithology stratigraphy, hydrology, and geomorphology. Notably, three distinct tectonic units characterize the geosites, with the Kon Tum massif exhibiting the highest number and diversity. Across the eight provinces/cities along the South-Central coast, all are endowed with rare or precious geosites. Despite Ninh Thuan province’s arid climate, it boasts a notable count of 16 geosites. In contrast, Quang Nam province has the fewest geosites (only 6), while other provinces range between 8 and 13 geosites. Remarkably, three provinces – Quang Nam, Khanh Hoa, and Binh Thuan – showcase geosites of all five types.
Assessment of environmental quality using biological index - The case of Can Tho city, Vietnam
Authors: Nguyen V C N , Le N Y , Nguyen T G 
Published: June 2024

Abstract
Many countries have used the biodiversity indexes to monitor environmental quality as well as assess ecosystem impacts, but most provinces and cities in Vietnam carrying out water monitor through physicochemical sampling that cause of costly. In this study, zoobenthos were collected from the rivers’ bottoms, where received wastewater from domestic activities (3 points) and from industrial productions (3 points) in Can Tho city. At domestic wastewater effected sampling points, there are 29 species belonging to 6 classes including Oligochaeta, Polychaeta, Bivalvia, Gastropoda, Crustacea and Insecta; the species density of 1,930 and 7,700 individuals/m2 in December and March. The industrial wastewater effected sampling points recorded 17 species belonging to 5 classes including Oligochaeta, Polychaeta, Bivalvia, Gastropoda, and Insecta; the species density during December and March are 3,890 and 5,680 individuals/m2. For the diversity index, the H’, DM, d, and ASPT values show better environmental quality received domestic wastewater than that of industrial wastewater. The biological index derived from benthic assessment could applied for environmental quality monitoring program at studied sites.
Assessment of surface water quality in the Sai Gon and Dong Nai Rivers, Vietnam
Authors: Loi Pham Thi 
Published: June 2024

Abstract
The Sai Gon and Dong Nai Rivers are important for the social and economic development of Southern Vietnam. They also serve as crucial water supply sources for Ho Chi Minh City and its surrounding provinces. The objectives of the present study are to evaluate the surface water quality of these rivers and to detect the possible sources of pollutants between 2015 and 2019. The study utilized various methods, including single factor evaluation, water quality index (WQI), and principal component analysis (PCA). Water quality data, such as pH, dissolved oxygen (DO), chemical oxygen demand (COD), biochemical oxygen demand (BOD5), ammonia (N-NH4
+), phosphate (P-PO4
3-), and Coliform, from eight monitoring sites along the rivers were used for the evaluation. The results stated that the water quality of the study region generally varied from ‘moderate’ to ‘good’ and had a decreasing trend from the upstream to the downstream during the study period. In addition, PCA results indicated that domestic sewage and industrial wastewater were significant factors affecting water quality in the middle stream of the rivers. The findings of this study can be used by local environmental management authorities to gain insights into water pollution and propose potential solutions for better protection and management of water resources.
Spatiotemporal evolution laws of sector-shaped dielectric-barrier-discharge plasma actuator
Authors: ZHENG 郑 Borui 博睿 , ZHANG 张 Jianbo 剑波 , QI 齐 Shaojie 少杰 , XU 续 Jianghua 绛华 , LI 李 Yiche 一澈 , JIN 金 Yuanzhong 元中 , BIAN 卞 Dongliang 栋梁 
Published: June 2024

Abstract
Dielectric barrier discharge (DBD) plasma actuators are widely used in active flow control due to their simple design and rapid responsiveness. However, they need more effectiveness and discharge extension. To overcome these limitations, a sector-shaped dielectric barrier discharge (SS-DBD) plasma actuator with an adjustable jet angle was developed to enhance flow control effectiveness. The flow field dynamics induced by the SS-DBD plasma actuator were quantitatively analyzed using particle image velocimetry (PIV). Experimental investigations showed that precise adjustments to the actuation voltage can modulate the maximum velocity of the induced jet. Furthermore, a quasi-linear relationship between the sector-shaped angles of the SS-DBD and the deflected jet angles was established, indicating that changes in the sector-shaped angles directly influence the direction of the deflected jet. This correlation enables precise control over jet angles, significantly enhancing flow control by adjusting the SS-DBD-PA’s sector-shaped angle.
The First Fusion
Authors: Strawson Galen 
Published: June 2024

AbstractChapter 5 presents the main argument for Sein ist Sosein: the view that an object or substance or portion of stuff considered at any given time is strictly identical with the totality of its intrinsic or categorical propertiedness or qualitiedness at that time. It argues against the separatist or categorial pluralist view that substance and property are fundamentally distinct metaphysical categories, and in favour of the categorial monist view, particularly well expressed by R. W. Sellars and Kant, that there is only one fundamental ontological category, which it calls stuff. It argues that Descartes, Spinoza, Nietzsche, and Schlick are among those who hold the same view, and that the name ‘bundle view (of objects)’ is unacceptable—irredeemably misleading—as a name for Sein ist Sosein.
Gravity as the cradle of cause and effect
Authors: Zaanen Jan 
Published: June 2024

Abstract
The case is made that gravity (general relativity) is a necessary physical condition for the existence of a causal nature of time. This is already the case for cosmologies ruled by Newtonian gravity, but it becomes a very deep affair in full general relativity. It is highlighted how this is implied by the Lorentzian signature of space-time: the peculiar fact that the time dimension knows about the square root of minus one. Combining this with Riemann’s non-Euclidean geometry, the ramification is that causality gets hard-wired in the geometry. This is highlighted in the form of the Penrose diagrams: the famous eternal black hole causality diagram is explained in detail. Finally, the ‘time circle’ associated with the black hole in Euclidean signature geometry, where time is acausal like a space dimension, is explained.
The measurement postulate: God is playing dice when cause yields effect
Authors: Zaanen Jan 
Published: June 2024

Abstract
Modern ideas regarding the origin of the collapse of the wavefunction are reviewed. This departs from recent advances in quantum non-equilibrium with its quantum thermalization insights. Working backwards from the stochastic equations underlying irreversible thermodynamics, governing the flow of heat and work in the macroscopic world, the hypothesis has been forwarded that this may be rooted in repeated spontaneous collapses. The text returns to the gravity-quantum conflict highlighting the problem with time as emphasized by Penrose, leading to the idea of gravitational wavefunction collapse. This is illustrated by an argument involving Shapiro time delays. This chapter ends with an original discussion: can the idea of repeated spontaneous collapses be combined with the gravitational collapse, and are there observable consequences?
Epilogue
Authors: Zaanen Jan 
Published: June 2024

Abstract
A tongue-in-cheek cheerful completion of the narrative, not intended to be taken seriously in any way. The case is made on the basis of the book Sapiens by Harari that the origin of mankind’s natural talent for story-telling is not at all obvious. It is argued that artificial intelligence/neural networks precisely fail in this regard, speculating instead that this story-telling capacity may have dealings with the forms and ideals of Platonic metaphysics. If true, story-telling involves a yet different and unique form of information processing. Assuming that all forms of information processing emerge when wavefunctions collapse, this may mean that human consciousness plays a role in the collapse process, in the spirit of e.g. the 1970s book The Dancing Wu-Li Masters.