bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantified effects of barriers and terrain elevations on design of buildings exposed to hemispherical open-air explosions
Authors: Flink PJ , Meijers SJH
Published: June 2024

The blast-resistant design of buildings has been of interest for decades, in petrochemical industry, military, legal courts, nuclear reactors, embassies and other vital facilities. Reliable analysis procedures have been established to determine the response of those buildings to a well-defined blast load. The overpressure caused by a hemispherical open-air explosion of a certain amount of TNT equivalents can be readily determined from literature. The reflected and side-on pressure and impulse are primary inputs for the blast-resistant design of buildings. That design can be more economical if barriers and terrain elevations are accounted for or provided. However, the effects of barriers and terrain elevations are not easily accessible in literature and consequently it is difficult to include in analyses. The influence must be estimated in practice, computed numerically, or neglected. In this present paper a series of hemispherical open-air explosions in geometrical configurations with barriers and elevations is addressed computationally with dedicated CFD software. Investigation of the results leads to a straightforward dependency of blast design parameters on geometrical parameters such as the scaled distances from the blast source to the obstacle or elevation and the building, as well as the height of the obstacle. The blast parameters can then be determined for future analyses based on the dependencies determined for this study. This can be considered as a practical supplement to the existing literature about open-air explosions, as it reduces the need for numerical analysis to determine the blast parameters in a range of configurations with barriers and terrain elevations.
Nonparametric ground motion models of arias intensity and significant duration for the Italian dataset
Authors: Hussaini Sayed Mohammad Sajad , Caicedo Daniel , Mohammadi Amirhossein , Karimzadeh Shaghayegh , Lourenço Paulo B
Published: June 2024

In the field of ground motion simulation, the stochastic site-based methodology relies on the existing database of ground shaking. Based on these methodologies, several properties of seismic signals are used to simulate seismic waves. These parameters could be evaluated either parametrically via linear or nonlinear regression techniques or non-parametrically via sophisticated machine-learning algorithms. Nonetheless, parametric models, which consist of a particular mathematical formulation, can be a source of large bias. In this study, machine learning techniques are employed to develop predictive models for two main input parameters of a stochastic site-based ground motion model: Arias intensity and significant duration, which control the time variation of the simulated ground shakings. The Arias intensity, defined by the integral of the square of the acceleration time series, and the significant duration, which is related to the strong shaking phase of an earthquake, are also of particular interest in structural and geotechnical engineering fields. For this purpose, the random forest approach is employed to develop prediction models for the Italian database. To guarantee the prediction accuracy of the models also for unseen future data, only 80 percent of the data is used for training, and the rest is reserved for testing the trained model. The model hyperparameters are tuned to control bias and variance trade-offs by k-fold cross-validation. For each model, a set of hyperparameters is selected, and a possible range is given. Then, a Bayesian optimization technique is implemented to find the best set of these hyperparameters among the given range. All these models provided promising results compared to the prior models in the literature.
Efficient time-dependent reliability analysis for a railway bridge model
Authors: Bittner M , Fritsch L , Hirzinger B , Broggi M , Beer M
Published: June 2024

This paper proposes a framework for efficient time-dependent reliability analysis for a parametrized stochastic dynamic system, namely a train bridge load model with uncertain design properties. The Probability Density Evolution Method is utilized to explore the multidimensional random space, identify specific failure paths contributing to the failure region, and provide a full probabilistic output of the desired target quantity. The framework is tested on an uncertain railway bridge subjected to train transit (moving loads). The peak acceleration as a function of the train speed in a certain interval is analysed and utilised as performance criteria. The main sources of uncertainties are the damping and the bridge’s moment of inertia. The full evolutionary Probability Density Function of the bridge’s maximum deck acceleration is obtained, the reliability is assessed and a probability of failure estimated. The results show that in the considered speed intervals, the velocities contributing to the failure region are depending on the underlying sampling method. The Probability Density Evolution Method offers additional insight on the evolution of the critical peak accelerations while at the same time performing a reasonable amount of full model evaluations. The study concludes that further discussion is needed to determine the appropriate prediction of the train speeds that may or may not significantly contribute to the probability of failure in this bridge train model.
Data-driven system identification of unknown systems utilising sparse identification of nonlinear dynamics (SINDy)
Authors: Pandey P , Haddad Khodaparast H , Friswell M I , Chatterjee T , Jamia N , Deighan T
Published: June 2024

This paper focuses on the application of experimental data-based system identification of unknown systems utilising sparse identification of nonlinear dynamics (SINDy). SINDy is used to detect the system dynamics in the three well-known nonlinear systems. Analyzed are SINDy’s abilities to accurately represent transient/steady-state behaviour, noise effect, and model structure. A sparse set of basis functions can effectively capture the dynamics of a system, according to the data-driven approach known as SINDy. The coefficients of these basis functions are determined via methods of sparse regression, and the final model is made up of a number of sparse ordinary differential equations. The findings demonstrate that SINDy, with sufficient time-series data, can capture both transient and steady-state phenomena. According to the analysis of the noise effect, SINDy’s performance declines as the system’s noise level rises. The feature library must contain the appropriate model structure in order for SINDy to function effectively. SINDy has the potential to extract unknown system dynamics from experimental data.
Comparing Open-Source BEM solvers for analysing wave energy converters
Authors: Raghavan V , Lavidas G , Metrikine A V
Published: June 2024

Ocean wave energy has immense potential and can provide at least twice as much electricity as globally produced now due to its high energy density. In order to efficiently extract this energy and make this commercially viable, Wave Energy Converters (WECs) need to interact with the resource in an optimized way for the expanse of sea states. This interaction is critical to power production by these devices and hence an accurate modelling of this is paramount. The Boundary element method (BEM) based on the linear potential flow theory has yielded accurate results at low computational costs when compared to complex Computational Fluid Dynamics methods. Hydrodynamic Analysis of Marine Structures (HAMS) and Capytaine are recently developed open-source BEM frequency domain solvers, originally created for large marine structures. These solvers have since been utilized for studying wave energy converters, though, for very few converter geometries. Owing to the implementation of parallelization in both HAMS and Capytaine, both these solvers could be capable for significantly lower computational costs as compared to the traditional BEM solvers such as Nemoh. This research aims to compare hydrodynamic coefficients and computational costs in Nemoh, HAMS and Capytaine for various WEC geometries.
Collective Identification of Superstructures and Dynamic Soil Springs Considering the Effects of Higher Modes Based on the MIEC Method
Authors: Tojo Takaki , Suzuki Takuya , Nakamura Naohiro , Nabeshima Kunihiko
Published: June 2024

The natural period and damping ratio are essential parameters that significantly impact the seismic response of buildings. Most recent seismic observation records have indicated that buildings are also affected by the dynamic soil-structure interaction (DSSI). In this study, we propose an identification method of vibration characteristics considering low-to high-order modes using the modal iterative error correction method and evaluate the influence of DSSI. First, we confirmed the validity of the proposed method using a numerical analysis model. Next, the proposed method was applied to the large shaking table test, and the stiffness and damping of the specimen were identified. The identification results for the test showed that the stiffness of the building or soil spring decreased, and the damping ratio tended to increase with the increase in the maximum deformation experienced. Upon evaluating the influence of DSSI on the foundation in the fixed condition, the effects of the first and second modes on the natural period were found to be more pronounced than the third mode. When the maximum deformation experienced increased, the natural period did not considerably change, whereas a part of modal damping ratios exhibited relatively large fluctuations.
Implementation of a Timoshenko beam within an elastodynamic halfspace modeled by the Wave Based Method
Authors: Lainer M , Müller G
Published: June 2024

The Wave Based Method (WBM) is an indirect Trefftz approach, which uses weighted wave functions to approximate the field response of a boundary value problem. These wave functions weakly fulfill the underlying differential equations and pass through a weighted residual approach by applying boundary conditions. This method has firstly been introduced for vibroacoustic problems to simulate excitations in the mid-frequency range. The accuracy of the WBM strongly depends on the relation between the geometrical size of a boundary value problem and the applied excitation frequency. This permits to transfer the WBM from vibroacoustic applications to soil halfspaces without significantly increasing the number of wave functions, and hence the number of unknown weighting values. Within this paper, a coupling approach between a Timoshenko beam and adjoining WBM domains is introduced as an efficient procedure for the simulation of a trench with two side walls. This trench is installed as a wave barrier against an incoming Rayleigh wave. The performance and accuracy of this coupling approach are analyzed and compared with results from literature. Moreover, different materials are tested for the side walls to assess the mitigation efficiency of the trench.
Numerical modelling of an impact resistance analysis of EN C45 steel pipe buried beneath the ground surface loaded with a detonation wave generated by an explosion of a cubic TNT charge
Authors: Olaleye Kayode , Pyka Dariusz , Bocian Mirosław , Jamroziak Krzysztof
Published: June 2024

The shock wave resulting from the explosion process is the main burden on the technical infrastructure facilities or people in contact with the epicentre of the high explosive (HE). The article presents the tests of EN C45 steel pipe of 10 mm thickness buried beneath the earth as a result of the impulse load of the detonation wave of the explosive charge. This process was modelled in one way using Abaqus Explicit code software using a 75 g Tri-Nitro Toluene (TNT) position 30 mm above the steel pipe. As a result of detonation, the samples were not fragmented, but visibly deformed displaying faster travelling of the explosion wave in air than in the soil. The main purpose of the work was to verify the impact resistance of EN C45 steel, which is commonly used in technical facilities. The impact numerical model results as a result of the shock wave on the steel tested material in the areas subjected to dynamic deformation are presented. The method used in this work is Coupled Eulerian-Lagrangian Method (CEL).
A SEM/FEM weak coupling for a more accurate definition of seismic input excitation in soil-structure interaction studies: An adaptation for a massively parallel FEM resolution
Authors: Korres M , Alves Fernandes V , Zentner I , Tardieu N , Voldoire F , Gatti F , Lopez-Caballero F
Published: June 2024

Numerical simulation of source-to-structure wave propagation consists of a challenging and demanding task in terms of computational capabilities and resources. Some difficulties related to the multi-scale character of the numerical problem can be alleviated using a spectral element (SEM) and finite element (FEM) weak coupling, such as the one described and verified in this study. In addition, the adaptation of the FEM resolution in a domain decomposition framework is developed allowing to utilize iterative solvers and ensure the scalability of the numerical solution in a High-Performance Computing (HPC) framework more efficiently. Comparisons with solutions adopting a direct parallel solver allow to demonstrate the important acceleration of the computation chain.
Identification of Building Parameters Considering Soil-Structure Interaction Based on Observed Earthquake Records
Authors: Kitaoka Hinata , Nakamura Naohiro , Nabeshima Kunihiko
Published: June 2024

A typical mid-to low-rise building is subject to strong dynamic interaction effects due to its relative degree of flexibility with the soil. Thus, it is necessary to take this effect into account when evaluating the seismic performance of such buildings. In this paper, we apply the modal iterative error correction method (MIEC method) to the foreshock records of the 2011 Tohoku earthquake to identify the coupled superstructure–foundation–soil system in a real building with few observation points. For this, observations made on the first, second, fifth, and eighth floors of an eight-story steel-reinforced concrete were used for identification of building parameters. In this earthquake, the response of each part of the building is within a linear range. First, the stiffness of the superstructure is identified as a parameter in the fixed-foundation model. Next, this stiffness value is used to create a Sway-Rocking model, and the identification was performed using soil spring as a parameter. The identification results for a real building with limited number of observation points, including soil springs in a linear range, showed good correspondence with the observed values.
An efficient pile-group foundation model to deal with ground-borne vibration problems
Authors: Conto Kenny F. , Arcos Robert , Clot Arnau , Liravi Hassan
Published: June 2024

This paper proposes a new efficient three-dimensional approach for modelling the dynamic response of pile-group foundations due to man-made ground-borne vibration excitations. The model employs the singular boundary method to account for the soil reaction, whilst the piles are modelled as rod or Euler-Bernoulli beams to account for axial/torsional or bending motions, respectively. The model is formulated considering strong coupling conditions between the two subsystems. The robustness of the model is discussed by comparing its results with the ones obtained by a three-dimensional finite element and boundary element approach. The comparison reveals that the robustness and efficiency of the proposed methodology provide accurate results without compromising its computational efficiency. A study of the dynamic interaction factors employed for modelling large pile-group systems using the superposition method is also presented. Particularly, the influence of including neighbouring piles in the calculation of dynamic interaction factors is discussed in the context of three pile-group foundation cases. This study shows considerable discrepancies above 10 Hz in the prediction of interaction factors between systems that do not consider neighbouring piles with the ones that do.
Development of a Low-Cost Resistivity Meter for Local Groundwater Survey
Authors: Monje J C , Guico M L , Oppus C M , Retirado M G , Cuezon A R , Torres J B
Published: June 2024

The researchers developed a low-cost resistivity meter with a built-in data file storage system using locally available parts. This effort was done in partnership with the National Water Resources Board and the Department of Science and Technology under the Water for Tourism project for water quality monitoring in tourist areas in the Philippines such as Boracay and Caticlan. The resistivity meter system consists of a power supply module, a sensor module, and an equipment module, built using locally available materials and equipment, emulating the commercially available PASI model 16 GL-N. Due to pandemic restrictions, the developed prototype could only be tested on one soil type area. Using a Schlumberger array configuration, the results are comparably similar to the benchmark test results using the PASI. Further work will be performed on future versions of this prototype such as the possibility of multi-electrode set-ups and some user design improvements, as recommended by partner organizations.
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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Chapter 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.
Prologue
Authors: Zaanen Jan
Published: June 2024

Overview of the contents of the book: concise summary of the most salient ingredients, and the way that these relate to each other in forming the plot of the book.
Gravity as the cradle of cause and effect
Authors: Zaanen Jan
Published: June 2024

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

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

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.
Clinical Assessment of Subjective Visual and Haptic Vertical Norms in Healthy Adults
Authors: van der Waal Charlotte , Saeys Wim , Truijen Steven , Embrechts Elissa
Published: June 2024

Background and objective

Accurate verticality perception is essential for daily life activities, such as correctly estimating object orientation in space. This study established normative data for the subjective visual vertical (SVV) and subjective haptic vertical (SHV) using the portable and self-constructable modified Bucket test and Rotating-Column test. Additionally, the contribution of age, sex, and starting position of the line/ column on SVV and SHV accuracy were evaluated.

Method

This study, part of the PRECISE project (ClinicalTrials.gov ID NCT05978596), was conducted following the STROBE guidelines. Healthy adults without visual/neurological/vestibular disorders were recruited. Subjective visual vertical and SHV accuracy were described in terms of constant errors (i.e., mean deviation from 0° [true vertical] respecting its direction), unsigned errors (i.e., mean deviation from 0° irrespective of direction), and variability (i.e., intra-individual standard deviation).

Results

Sixty participants were evaluated (mean age: 41.14 [SD = 16.74] years). Subjective visual vertical constant errors between −2.82° and 2.90°, unsigned errors up to 2.15°, and variability up to 1.61° are considered normal. Subjective haptic vertical constant errors ranged from −6.94° to 8.18°, unsigned errors up to 6.66° and variability up to 4.25°. Higher ages led to higher SVV unsigned errors and variability. SHV variability was higher in females compared to males. Certain starting positions led to higher SVV and SHV constants and SVV unsigned errors.

Discussion

Normative data are provided for affordable, self-constructable, and portable SVV and SHV tools. These norms are consistent with more sophisticated equipment and can be used to distinguish between normal and abnormal values.
CPC04 An atypical case of vasculitis: when immunosuppression is not the answer
Authors: Celebi Perin , Sherlock Hannah , Hawari Rand , Abid Maaz
Published: June 2024

Cutaneous vasculitis has a wide range of recognized causes, including drugs, autoimmune diseases, infection and malignancy. The management depends on the underlying cause, but the mainstay of treatment for severe disease is typically immunosuppressive agents such as corticosteroids. This case report discusses an unusual presentation and cause of small vessel vasculitis, and the challenges faced in diagnosis. A 53-year-old woman with a background history of renal sarcoidosis presented to dermatology with a 6-month history of a painful nodular and nonblanching purpuric rash on her lower legs. The clinical impression of cutaneous sarcoid was managed by increasing her prednisolone and later her azathioprine. However, despite this, her rash progressed into a bullous and necrotic ulcerating vasculitic eruption. An incisional biopsy was performed due to the atypical appearance of the rash, and the level of pain, which was not in keeping with cutaneous sarcoid or a usual vasculitic eruption. Sections of skin showed prominent epidermal necrosis, with focal blisters containing numerous dead keratinocytes. There were occasional viable keratinocytes showing intranuclear viral inclusions most in keeping with herpes infection. The underlying dermis showed prominent perivascular inflammation and fibrinoid necrosis of the superficial and deep blood vessels, even extending into the subcutaneous fat with areas of fat necrosis. Occasional leucocytoclastic debris was seen in the superficial blood vessels with numerous extravasated red blood cells. These histological features are in keeping with fulminant leucocytoclastic vasculitis with atypical herpes infection. Varicella zoster serology was positive, confirming the rare diagnosis of atypical fulminant herpes vasculitis. The patient improved on intravenous aciclovir 5 mg kg−1 and continues on a longer-term prophylactic oral dose. Atypical presentations of vasculitis are challenging to diagnose, resulting in delayed management and increasing the risk of postherpetic neuralgia. We aim to discuss this and other cases in the literature to improve awareness of this rare but important presentation, which, contrary to other vasculitides, should not be treated with immunosuppression.