bluuebunny/crossref_metadata_2025 huggingface dataset:
Research on predicting air resistance in complex pipelines with fans
Authors: Zhang Shengli , Zeng Zhichun , Sun Yupei , He Long , Wang Changhao
Published: July 2024

This article proposes a prediction method for air resistance in aircraft brake chambers by analyzing the theoretical resistance along the pipeline and local resistance. It develops an air resistance calculation software based on this method. Finally, the air resistance of aircraft brake chamber pipes with three different specifications of fans was predicted using the methods and software presented in this article. The comparison between the predicted results and the simulation results shows that the method is accurate and reliable, and can be used to predict the air resistance inside the aircraft brake chamber.
Simulation analysis of deformation during machining curved thin-walled structures of aluminum alloy
Authors: Zhao Kang , Kong Xiangru
Published: July 2024

Impeller parts are widely used in key parts of equipment such as aerospace, ocean, and energy. Their curved thin-walled structures are prone to local machining deformation and elastic tool yielding during the cutting process, reducing their machining quality. Therefore, to improve the machining accuracy of such parts, an empirical formula and simulation model for cutting force machining are established. Based on the Abaqus secondary development platform, the deformation patterns of parts machining are simulated and predicted, and the machining deformation amounts of different cutting methods are compared and analyzed. The results show that the deformation of single-side cutting is significantly greater than that of symmetrical and stepped cutting, and the maximum deformation is reduced from 0.047 mm to 0.029 mm, which can effectively improve the machining accuracy.
Research on electromagnetic environment inside linear motor
Authors: Li Yunfeng , Su Tianzan , Fu Shanqiang , Ding Sansan , Tang Zhiyuan
Published: July 2024

In the maglev system, the long stator linear motor provides power for the train, and electromagnetic disturbance will be generated during the operation of the motor, which will interfere with other equipment. In this paper, the influence of linear motors on the electromagnetic environment inside the train is analyzed by the finite element method, and the magnetic field intensity inside the train under two different working conditions is obtained by software simulation. It is found that under normal working conditions, the magnetic field radiation emission of the linear motor meets the requirements. Under phase absence conditions, the overall magnetic field intensity on the left side of the car body, the center of the axis, and the right side increases by 12 dB, 17 dB, and 19 dB respectively, so it is necessary to avoid such a situation. This paper further proposes that the external radiation emission of the vehicle can be improved through shielding.
Influence of carbon quantum dots on foam stability: a molecular dynamics study
Authors: Zhao Xingze , Chen Sihang , Zhang Lu , Su Hang , Wu Yining , Ren Hao
Published: July 2024

Carbon quantum dots are employed in foam for enhanced oil recovery. This study focuses on the impact of carbon quantum dots on the stability of oil displacement foam. Molecular dynamics simulations are conducted to investigate commonly used models of carbon quantum dots and surfactant foams in oil displacement. The research delves into the interfacial properties of the foam film, the flow characteristics of water molecules, and the interaction between carbon quantum dots and surfactants. Insights gained from these three aspects reveal the influence of carbon quantum dots on surfactant foam films. This work provides theoretical guidance for the utilization of carbon nanomaterials in foam-assisted oil recovery.
Study on the characteristics of the bypass flow field of the net structure under different Reynolds number conditions
Authors: Yang Liulin , Li Zhaolie , Zhao Tian
Published: July 2024

A double-row crossed cylindrical structure is used as a basic net unit, and the simulation method is used to simulate the winding process of the double-rowed crossed cylinders at different Reynolds numbers, to study and analyze the change of the surrounding flow field with Reynolds number when the uniform flow passes through the net structure, and to compare with the single cylinder. It is found that the fluid passing through the intersection of the cylinders will form a return flow at the back side, and the fluid will extend to the cylinder after the return flow to the near wall of the structure to develop into a spreading flow. The spreading flow makes the distance from the vortex shedding position to the structure surface of the double-row crossed cylinder significantly larger than that of the single cylinder.
Simulation of air pipe heat dissipation in civil aircraft water system based on flowmaster
Authors: Lei Meiling , Zhu Chong
Published: July 2024

The water supply method of civil aircraft water system is mainly from the bleed air system to pressurize the water tank. However, the gas temperature from the bleed air system is often too high. The AC-25.863 draft [1] stipulates that the maximum surface temperature of the equipment should be lower than 50°F below the spontaneous combustion point of flammable liquid in the area. Otherwise, it will become the ignition source of flammable materials. In this paper, by establishing the heat transfer model of an air pipeline, a set of air duct heat transfer calculation methods is proposed, and the variation rule of air pipe surface temperature is studied, to verify that the gas temperature from the bleed air system meets the requirements of the system, and the air pipe surface temperature meets the requirements of AC-25.863 draft.
Research on the influence of system drainage holes on the head loss of water transmission systems
Authors: Li Gaohui , Shang Yan , Gao Yue
Published: July 2024

To ensure the structural safety of the thin lining structure of the tailwater tunnel, this study used three-dimensional flow field numerical simulation technology to conduct an in-depth analysis of the drainage holes set along the tunnel body, to evaluate the impact of drainage holes on the overall and local head loss of the tunnel under different system layout types. It aims to provide scientific theoretical support and practical reference for engineering design and achieve more efficient and stable tunnel hydraulic operation conditions.
Simulation study on the road system of port collection and distribution in the harbor area
Authors: Zhang Jianbao , Zhang Tong , Du Linan , Li Zhenbao
Published: July 2024

This paper comprehensively considers the impact of both internal and external traffic environments on the collection and distribution road system in the harbor area. Utilizing Anylogic simulation software, we construct a test environment using Yulong Port’s collection and distribution scenario as a case study. The analysis examines the influence of changes in road construction and the growth of external traffic on the operational efficiency of the port’s road collection and distribution system. The results indicate that with the addition of new roads, the efficiency of car and freight vehicle operations improves, leading to a respective decrease in the average travel time within the system by 3.6% and 4.4%. However, under conditions where social traffic flow increases to 1.2 times, the average travel time of the traffic flow within the system significantly rises, and congestion occurs in the external traffic around the port. The findings of this research provide valuable decision-making insights for the construction of collection and distribution channels in port areas and the approval of governmental projects.
Research on erosion wear law of four-way flow channel of wellhead fracturing in ultra-deep wells
Authors: Wan Zhiyong , Lian Zhanghua , Sun Wei , An Nan
Published: July 2024

This paper establishes a 1/2 three-dimensional finite element model that considers multiple factors affecting the erosion rate of the four-way fracturing structure on site. The model can simulate the effects of different inlet velocities, dynamic viscosities, outlet quantities, outlet pressures, and channel wall angles on the velocity and streamline distribution of the four-way channel. It is also possible to analyze the effects of different factors such as inlet velocity, sand carrying mass flow rate, inlet quantity, fluid dynamic viscosity, fracturing fluid particle density, fracturing fluid particle diameter, four-way wall hardness, and channel wall inclination angle on the erosion of the inner wall. Through the established model calculation, it was found that as the inlet flow velocity increases, the maximum flow velocity in the channel also increases, and the value is close to 1.8 times the inlet velocity, with the maximum value appearing at the inlet corner. When the inlet velocity of the four-way valve is low, a significant vortex-like flow field appears in the closed flow channel of the four-way valve, which will lead to the accumulation of particles in the fracturing fluid. The calculation shows that the number and velocity of sand containing fracturing fluid inlets have the greatest impact on the erosion rate of the four-way flow channel, and the optimal inclination angle of the flow channel is 9 degrees. Increasing the hardness of the four-way wall can improve the maximum erosion rate of the flow channel wall, but changing the sand particle density and diameter has little significance in reducing the erosion rate of the four-way flow channel. It is recommended to perform corresponding heat treatment on the inner wall of the four-way valve to reduce the impact of sand containing fracturing fluid on wall erosion. This article provides a theoretical basis and guidance for controlling or avoiding erosion and thinning failure of four-way valves and also provides a theoretical basis for the design of wellhead four-way valves and various safe construction operations.
Anomaly detection of four-engine aircraft based on Parameter differences
Authors: Liu Jiahuan , Bai Jie , Wang Wenjin
Published: July 2024

In this paper, a real-time anomaly detection method combining GDN and Gaussian model is proposed for the real-time engine condition monitoring of four-engine aircraft. Firstly, the gas path parameters of the engine are selected and the difference of the gas path parameters is calculated to offset the influence of the external environment on the engine. Thirdly, the sliding time window method is used for real-time prediction, and the model prediction residuals are used for unsupervised anomaly detection. Finally, the Gaussian model is used to prune the anomalies detected by the GDN model to reduce the misjudgment of anomalies and improve the accuracy of anomaly detection. The experimental results show that the proposed method can detect 97.96% of the outliers in the test set and the accuracy reaches 89.47%, which is better than LSTM, AE, GDN, and Gaussian models alone.
Design and simulation of AGV control system based on V-REP
Authors: Zhu Jianchao , Yang Chen , Cao Zifan , Jiang Bo , Xue Yanjie , Lin Zhuorui
Published: July 2024

In this paper, the design and simulation method of the AGV control system is studied, a variable gain PID control method for the AGV-oriented speed control system is designed, a three-dimensional AGV model in the V-REP simulation platform is established for the directional control system, and a control strategy is designed. Finally, the AGV control system is simulated based on the V-REP simulation platform. The simulation results show that the control system in V-REP has a good control effect on AGV.
Driverless holographic simulation test integrated environment design
Authors: Leng Sixuan , Mo Liye , Pan Xiang , Lin Xingzhi
Published: July 2024

Aiming at the design problem of simulation test integrated environment for unmanned car, starting from the four aspects of unmanned simulation test [1], real scene quiz, scene analysis and layout, and data visualization and processing, through the combination of software and hardware, the use of various types of sensors, controllers, communication equipment, etc. for collaborative management of unmanned car driving, and the use of intelligent networked cars to collaboratively verify the multi-class algorithms and driving programs, and continuously improve the Overall environment design [2] [3], the integrated environment design is getting better and better. This overall environment is tested based on carla’s Apollo autonomous driving simulation software, and the test results show that the recognition accuracy rate reaches 87% and the simulation rate reaches 91%, etc. It shows that the unmanned holographic simulation test integrated environment technology program is feasible.
Numerical simulation of neural activity based on discrete Markov chains with stochastic differential equations
Authors: Wang Erhui , Luan Xuefei
Published: July 2024

With the development of new numerical calculation methods and computer software science and technology, people can have a good understanding of the potential mechanisms of cerebrovascular diseases. Here, we combine the stochastic differential equation (SDE) of discrete Markov chains to numerically simulate the dynamic changes of neural signals, and find that the changes of neural signals exhibit regular fluctuations. By analyzing the variation of voltage over time, we know that the voltage change at the next moment is closely related to the previous moment and has continuity. Based on the knowledge of neural ion channel dynamics, it was found that there will be longer peak changes in voltage, exhibiting a power-law distribution, which is consistent with the actual situation and statistical data related to resignation channels. By analyzing the voltage and peak changes of ion channels, we can gain a new understanding of the transmission laws of neural information and greatly improve the biological mechanisms.
The spectral conjugate gradient method in variational adjoint assimilation for model terrain correction III: convergence analysis
Authors: Tao Sulin , Li Yuhong
Published: July 2024

In the former parts of this paper, the spectral conjugate gradient (SCG) algorithm was proposed to identify the optimal bottom terrain used for predicting the meteorological fields. In this part, the convergence analysis of the SCG method is presented to verify its validity when solving a typical ill-posed inverse problem. The scaled cost function, the scaled gradient norm, the linear convergence rate, and the Hessian approximation condition number are evaluated for convergence analysis. The SCG method reduces the cost functional value and the gradient norm sufficiently. It always performs linear rates of convergence with a quickly reduced condition number of the Hessian matrix. Sometimes it provides very fast linear convergence rates. The SCG code with optimal step size and Andrei’s equation is effective on ill-posed test problems.
Numerical analysis and calculation of fractional neuron transmission model
Authors: Wang Erhui , Luan Xuefei
Published: July 2024

It is well known that the transmission of nerve signals is closely related to the incidence and production of vascular diseases. However, due to the multilayered and complex structure of the vascular wall, although a series of studies have been carried out, the mechanism of vascular diseases is difficult to fully understand. In this paper, the fractional constitutive equation is used to study numerically the transmission of nerve signals in the vascular wall. On the basis of considering the effect of substance transport in the vascular layer, a new comprehensive model was established to describe and analyze the voltage trajectory of neuron activity using multi-time-scale dynamics induced by correlated membranes combined with non-Markov processes. The results show that our fractional order model can better describe the process of neurotransmission. By changing the fractional order, we can show in vitro the up-and-down spike adaptation found in the experiments of neocortical pyramidal cells and parietal neurons.
Formal modeling and verification method for Simulink-MDL requirement model
Authors: Li Junan , Hu Jun , Wang Lisong , Wang Kangxing , Dai Jialei
Published: July 2024

As complex safety-critical system software becomes more powerful, so does the complexity of its design requirements. Modeling and analyzing design requirements at an early stage has become an integral part of the entire development process for complex safety-critical system software. Simulink is a system modeling and simulation tool used in aviation and other fields. Its model is stored in the form of MDL files. ART (Avionics Requirement Tools) is a requirement modeling and analysis verification tool for the aviation field. It uses VRM (Variable Relation Model) as the theoretical model and can accept VRM and its extended subsets as input models and verify them in the tool. The work of this paper is oriented to the typical software requirements in the field of avionics systems and proposes a formal modeling and verification method for Simulink-MDL models. First, the composition form and structure of the MDL model are analyzed in the article. The functions and semantics of various elements in the model are given. Then a formal modeling method of the MDL model is given. Finally, a simplified version of the flight guidance control system is used for modeling and verification to demonstrate the usability and effectiveness of this method.
LPI radar waveform recognition model based on multiple feature image and quasi-residual attention module
Authors: Li Zhe , Wu Lihua , Xia Bin , Song Lintao
Published: July 2024

Detecting and classifying the modulation type of the intercepted noisy LPI radar waveform has become a hot topic in the field of Electronic Countermeasures (ECM). In this paper, we propose a recognition model based on multiple feature images (MFI) and convolutional neural networks (CNN) with the quasi-residual attention module (QRAM). The core technologies of this model are divided into two parts. One is the MFI that combines the ambiguity function image (AFI) of the complete signal, covariance matrix image (CMI) of the reconstructed signal, and short-time Fourier transform image (STFTI) of the truncated signal into RGB color image in signal processing as the input for recognition network. The other is CNN with a QRAM recognition network, in which the input is sliced into two mappings called identity mapping and residual mapping to build the quasi-residual module, and the attention module is embedded in each mapping to denoise and enhance the feature. The performance of the MFI-QRAM model is demonstrated by recognizing 12 modulation types of the signals defined in this paper. The simulation experiments show that the model has strong robustness with the number of train sets and the variation of SNR. The overall probability of successful recognition (PSR) is 96.17% when the SNR is −6 dB.
Reliability analysis and optimization of BGA solder based on finite element simulation
Authors: Lei Ting , Yang Jiepeng , Liang Shizhang
Published: July 2024

For the reason of reliability improvement of BGA solder, ANSYS is used to establish a BGA solder model that contains information such as size, material, grid, etc. The thermal stress of solder is selected as the optimization objective by the optimization parameters of solder height, solder radial direction, and spacing of solder. Response surface methodology is used to design 17 sets of different level parameters for simulation calculations, and a regression equation between solder joint stress and optimization parameters is established to obtain the parameter combination with the minimum stress of solder. The analysis results show that the corner solder far from the chip are critical solder joint for failure. The optimized solder joint parameters are as follows. The solder height is 0.5 mm, the solder radial is 0.6 mm, and the solder spacing is 1 mm. The optimized solder joint stress value is 30.818 MPa, which reduces the stress by 27.71% compared to before optimization, which achieved the reliability improvement of BGA solder.
Research on natural ventilation of a community library related to epidemiological insight by using CFD simulation method
Authors: Deng Jie , Vongphantuset Jirawat , Sirivesmas Veerawat , Fang Lin , Guo Zhengquan
Published: July 2024

Spreading through airflow is one of the most common routes for the transmission of viruses, which may result in serious public health problems. To acquire a healthy space for the community library, designing a reasonable ventilation system is a vital measure which can reduce the risk of transmission of the virus effectively.

The purpose of this research is to study natural ventilation methods in an epidemiological insight for the design of a healthy community library by using computational fluid dynamics (CFD) software SOLIDWORKS Flow Simulation. Five typical opening types of windows were selected and studied in the research on the ventilation of the yoga room of a community library, with airflow evaluated by the ACH method, so as to search for the most suitable window type to avoid airborne virus transmission.

The results acquired by SOLIDWORKS simulation showed that 75%, 90%, and 100% openings corresponding to Jalousie, casement, and double casement window types respectively are optimal in community space. The natural ventilation design by proper windows can be applied in the community library and other public spaces.
Simulation of ideal blackbody based on multi-space boundary condition in FDTD
Authors: Wang Nan , Zhu Hongxian
Published: July 2024

Investigation shows that it is difficult to solve the electromagnetic field surrounding an ideal blackbody using the analytic method. To solve this problem, the simulation method should be adapted, and the Maxwell function should be expanded to multi space. In this paper, a multi space simulation scheme of finite difference time domain (FDTD) and a multi space boundary condition (MSBC) are proposed for the simulation of an ideal blackbody. Compared with the traditional absorbing boundary condition (ABC) or perfectly matched layer (PML), which can only be assigned in the outermost layers of the simulation space, the proposed MSBC is simpler and can be arranged inside the computing space. Numerical simulation shows that MSBC has good electromagnetic wave absorption performance and can simulate the ideal blackbody accurately. At the same time, the simulation results also show some interesting characteristics of electromagnetic waves around the ideal blackbody.
Calibration of discrete element method simulation parameters for lunar rover using simulated lunar soil
Authors: Zhao Liangliang , Zhang Hua , Ma Jia , Du Yupei , Hu Zhenyu , Zhang Rui , Zhou Guifen
Published: July 2024

To ensure the accuracy and scientific validity of simulation results in discrete element simulation of simulated lunar soil and sieve wheels for lunar surface probes, a method for calibrating the simulation parameters of an analog lunar soil simulation using a box-Behnken experimental design is proposed. First, the particle model and particle size distribution of the discrete element simulation were calibrated based on the determination of the intrinsic parameters, shape parameters, and particle size parameters of this simulated lunar soil. A Box-Behnken experimental design is employed to conduct response surface simulation experiments for the pile angle, obtaining optimal parameter values. The optimal parameter values are applied in the simulation validation, revealing a relative error of only 3% compared to the actual pile angle. This indicates that the obtained results can serve as calibrated values.
Research on experimental evaluation model of unmanned aerial vehicle autonomy based on digital twin
Authors: Zhang Lu , Wang Hao , Zhai Mingda , Yi Pinglang , Meng Chuanshu
Published: July 2024

The current focus of unmanned aerial vehicle (UAV) research lies in the scientific evaluation of UAV autonomy and the enhancement of belief in UAVs. Researchers are required to conduct numerous tests to assess the ability of UAVs to perform missions in complex environments. However, conducting real-world tests for UAVs costs a lot. Therefore, digital twin virtual simulation serves as a viable alternative to actual flight tests. Firstly, this paper establishes a digital twin framework that enables comprehensive perception and integration within a virtual environment, proposing a UAV autonomy experimental evaluation model. Additionally, an effective method for evaluating UAV autonomy is constructed, and test tasks targeting autonomous capability assessment are designed by using simulation software and verified through system examples. Finally, based on the simulation results, the autonomous capability of the UAV twin is evaluated and utilized as a reference for assessing the autonomy of physical UAVs, thereby providing support for scientific evaluation.
Evaluation of adaptability of software-defined telemetry systems for operational use
Authors: Wang Wanli , Li Yiyong , He Rong , Li Jian , Hu Jingjing
Published: July 2024

Aimed at solving the key problem of operational adaptability assessment of software-defined telemetry systems, the evaluation method of improved hierarchical method and fuzzy comprehensive evaluation is proposed. In the “general + expand + unique” flexible method to build an index system, the “expert decision matrix” index weight assignment and the fuzzy comprehensive evaluation method using operational adaptability assessment are used. According to the principle of maximum membership, the calculation results tend to be the largest. The proportion of 0.6524 shows that the equipment’s operational performance is good. At the same time, it was found that the proportion of qualified was 0.157, exposing its weaknesses and putting forward targeted suggestions, which provided a reference for the technical optimization and improvement, and forward-looking deployment of new equipment.
Estimation of winter wheat yield in Hebi city based on crop models and remote sensing data assimilation
Authors: Li Ying , Zou Chunhui , Feng Liping , Yao Xiaochuang , Li Tongxiao , Chen Xianguan , Zhao Jin
Published: July 2024

Assimilating remote sensing data with crop models is an effective approach to improve the accuracy of crop model applications at the regional scale. Sobol global sensitivity analysis and Markov Chain Monte Carlo methods were used to calibrate parameters in the WOFOST and WheatSM models within a gridded model framework in the study area. Time series data reconstruction techniques were employed to correct MODIS LAI and ET data. Four assimilation scenarios were tested, including assimilation of only leaf area index (LAI), assimilation of only evapotranspiration (ET), simultaneous assimilation of LAI and ET and a control scenario without assimilation. These scenarios were applied to model winter wheat yields in Hebi City, China, from 2013 to 2018. Statistical validation demonstrated that assimilating ET or LAI individually significantly improved model accuracy compared to the control scenario with similar levels of improvement. The highest model accuracy was achieved when assimilating both ET and LAI simultaneously, showing the highest correlation coefficients and the lowest root mean square errors among the four scenarios. This research provides a basis for selecting assimilation variables when applying crop models at the regional scale. The coupling of crop growth models with remote sensing data empowers governments and agricultural producers to devise more effective agricultural strategies, allocate resources efficiently, and implement disaster response measures. This enhances scientific management within the agricultural sector, promotes increased food production and elevates farmers’ incomes.
Temporal Estimators of Peculiar GRBs
Authors: Noriega N. , Cárdenas E. F. , Chacón J. A. , Vásquez N.
Published: July 2024

In our study, we analyze four peculiar Gamma-Ray Bursts (GRBs), namely GRB070724A, GRB070429B, GRB090426, and GRB120804A, all detected by the Swift space telescope. The focus of our investigation lies in evaluating the temporal estimators, such as emission time and spectral lag time in the third Swift GRB catalog sample. Our findings reveal that the calculated temporal estimators offer diverse insights into the classification of the examined GRBs, hinting at the distinctive nature of these events. This suggests that these GRBs can be considered as ‘peculiar’ when compared to standard GRBs in the spectral plane, specifically in the Amati-like relation. Whereas, the spectral lag analysis of the four GRBs increases the evidence to consider these as ‘peculiar’.
Cross-correlation between the multifractal spectra of the solar wind magnetic field from Parker Solar Probe and Solar Orbiter
Authors: Andy Rubio E.
Published: July 2024

The solar wind, a plasma emanating from the Sun and extending throughout the universe, continues to be a subject of intense study. This study focused on examining the multifractal spectra of the solar wind’s magnetic field in regions proximal and distal to the Sun, leveraging data collected by the Parker Solar Probe and Solar Orbiter satellites, respectively. Utilizing the box-counting method within multifractal analysis has provided insights into the distinctive characteristics of each satellite, including singularity exponents and multifractal spectra. However, the cross-correlation observed between the spectra obtained by both satellites has prompted further inquiry into its physical implications. This suggests the need for a more comprehensive investigation to elucidate the underlying dynamics driving these correlations and their significance in our understanding of solar wind behavior. Continued research in this area holds promise for advancing our comprehension of solar phenomena and their broader implications.
Galactic Superbubbles in 3D: Wind Formation and Cloud Shielding
Authors: Suárez-López O. , Villares A. S. , Banda-Barragán W. E.
Published: July 2024

Galactic superbubbles are triggered by stellar feedback in the discs of star-forming galaxies. They are important in launching galactic winds, which play a key role in regulating the mass and energy exchange in galaxies. Observations can only reveal projected information and the 3D structure of such winds is quite complex. Therefore, numerical simulations are required to further our understanding of such structures. Here, we describe hydrodynamical simulations targeting two spatial scales. Large-scale superbubble models reveal supernova-driven outflows, and their subsequent merging, which leads to galactic wind formation. Additionally, the turbulence parameter σt
not only affects disc formation, but also influences mass and energy characteristics, controlling gas distribution and the injection rate in the simulated star formation zone. Small-scale wind-multicloud models indicate that isolated clouds are susceptible to instabilities, leading to fragmentation and dense gas destruction. In contrast, in closer cloud configurations, the condensation mechanism becomes important owing to hydrodynamic shielding, which helps to maintain the cold material throughout the evolution of the system. These simulations provide a comprehensive picture of galactic winds, showing how large-scale superbubble dynamics create the environment where small-scale wind-multicloud interactions shape the interstellar and circumgalactic media, ultimately regulating galaxy evolution.
Exploring the Universe through Gamma-Ray Astronomy: Characterization and Performance of the LST-1 Telescope
Authors: Baquero Larriva A. , Contreras J.L. ,   CTA-LST Project
Published: July 2024

Gamma-ray astronomy allows for the exploration of the most energetic phenomena in the universe and has seen significant advances in the 21st century, as evidenced by the development of the LST-1 telescope, a part of the Cherenkov Telescope Array (CTA). The LST-1, situated at the Roque de los Muchachos Observatory in La Palma, Spain, commenced its commissioning phase in October 2018 and captured its first light in December of the same year. This research primarily addresses the characterization of the LST-1 telescope, utilizing Monte Carlo simulations and real data from observations of the Crab Nebula to assess its performance, which is already approaching the design requirements. Furthermore, the results obtained from observations of the Active Galactic Nuclei Markarian 421, Markarian 501, and 1ES 1969+560 agree with those obtained by other telescopes, thus validating the efficacy of the LST-1.
Comparative evaluation of wavelength-scanning Otto and Kretschmann configurations of SPR biosensors for low analyte concentration measurement
Authors: Araguillin Ricardo , Méndez Ángel , González José , Costa-Vera Ćesar
Published: July 2024

The growing demand for compound characterization has stimulated research, particularly in surface plasmon resonance technology. This technique monitors changes in the light-reflecting properties of a sample medium in close contact and in interaction with a plasmonic surface (typically a metal such as gold) due to shifts in the fundamental plasmon resonance of the surface. The Otto and Kretschmann configurations are commonly used in this method. When an analyte is expensive, scarce, or hazardous, it is advantageous to reduce the sample required for testing, making optimization of sample use interesting. This challenge requires trade-offs between sensitivity and LoD. This work compares two sensors in the indicated configurations designed for minimal analyte requirement (in this case, Ag nanoparticle suspensions) using the wavelength scanning technique. The results show that the Kretschmann configuration is the most efficient for characterizing nanoparticle suspensions due to its construction characteristics, ease of use, and the characteristics of the obtained response. The final arrangement is a quasi-point sensor that only requires 6μL of analyte and has a sensitivity of 4.17x10−4 RIU/λ (RIU is the refractive index unit). This study contributes to the exploration of advantages and limitations in the design and operation of SPR sensors. The work also underlies the need for future research to enhance the selectivity and versatility of these devices.
Assessing the impacts of El Niño events on the Ecuadorian territory: a computational analysis of climatologies, anomalies, and deprivation index.
Authors: Paredes A J , Cruz G L , Chimborazo O V
Published: July 2024

This study conducts a comprehensive computational analysis to assess the climatological and socio-economic impacts of El Niño events on Ecuador, employing a detailed examination of climatologies, anomalies, and deprivation indices from 1980 to 2023. We identify significant climatic shifts and implications on regional vulnerabilities by utilizing the Essential Climate Variables dataset, alongside the Oceanic Niño Index (ONI) and the Niño 1+2 index for sea surface temperature anomalies. Additionally, the Global Gridded Relative Deprivation Index (GRDI) is integrated to evaluate socio-economic impacts, highlighting areas of heightened deprivation. Notably, regions such as Chimborazo, Cotopaxi, Azuay, Tungurahua, and Bolívar emerge as significantly vulnerable, with pronounced susceptibility to temperature changes and precipitation anomalies. Several statistical methods, including Pearson Correlation, Spearman Rank Correlation, and Kendall’s Tau are employed to establish robust causal relationships between El Niño indices and climatic anomalies. The application of Convergent Cross Mapping (CCM) provides deeper insights, particularly demonstrating causality from ONI to air temperature anomalies and from the Niño 1+2 index to precipitation anomalies. The findings of this study may suggest targeted strategies for local adaptation and resilience, contributing to a broader understanding of global climate variability.
Visualization and Segmentation of Lung Tissue in DICOM-format CT Images
Authors: Ortega Jennifer
Published: July 2024

In this project, two tools were developed as a preliminary step towards the creation of future Computer-Aided Diagnosis systems for the automatic detection of lung diseases. The first methodology aimed to extract information from DICOM-format files using Python and the Jupyter Notebook programming environment. The implemented process enables the generation of images in various anatomical planes, using the pixel matrix in Hounsfield units. Additionally, a custom tool was developed for anonymizing and visualizing file information. The techniques employed are independent of the grayscale image generated and are not reliant on the type of window used. The second tool introduces a lung segmentation technique for chest CT images. The segmentation uses the pixel matrix in Hounsfield units to initially identify lung tissue based on its linear X-ray attenuation. Subsequently, the Watershed algorithm based on markers is employed as the primary foundation of the technique. Various morphological operations and transformations on axial slices are applied, resulting in successful lung segmentation.
A Survey on Energy Methods for Vibroacoustic Analysis of Random Dynamic Systems and Applications
Authors: Andrade Luis
Published: July 2024

Engineering can be considered a field of applied physics, as for the design of dynamic systems several aspects such as the strength, parameters of motion, among others, must be estimated for dimensioning, specifications of construction procedures, and operation. In the search for an appropriate model to estimate the dynamic response of a system to a prescribed input, several energy-based methods have been explored over the last decades to address three main issues. Firstly, it is quite rare that a solution for a purely analytical model exists, particularly for complex built-up structures. Secondly, numerical approaches to solve such complex equations of motion of a structure are computationally expensive. Lastly, even if a numerical or analytical solution can be found, there is no warranty that such estimation would be true for an ensemble of nominally identical built-up systems due to uncertainties that are not usually considered by the models. The aim of this work is to present a survey of existing approaches based on equations of energy rather than motion to simplify the computational process and include the effects of uncertainties in the dynamic response, and improvements to such models in regard of other engineering aspects. Additionally, several engineering applications are presented.
Study of the thermal diffusivity in low-response optical systems combining a thermal lensing approach with a standard addition method
Authors: Teran Ana , Costa Vera Cesar
Published: July 2024

Thermal lensing is a local effect produced by the incidence of a light beam that heats a part of an absorbent material. Mathematical modeling of this photothermal phenomenon allows the determination of the medium’s thermal diffusivity. A pumping-modulated laser (405nm) induces the thermal lensing effect, and a test laser (650nm) generates the photothermal signal measured as a function of the modulation. The thermal diffusivity is obtained from a curve fit of the signal (calibrated for ethanol). In this work, the thermal diffusion coefficients of low-absorbance nanoparticle suspensions are established. This was achieved through the application of a standard addition method. The added analyte, enhance the optical response of SiO
2 nanoparticle suspensions. Different aliquots of tartrazine (analyte) resulted in different values for the thermal diffusion of the samples. It was found that the experimental coefficients of this colloids agree with the theoretical model. Finally, a linear regression allowed to find the thermal coefficient in the zero concentration point.
Parameters of differential equations in four-flux and two-flux models approximated for scattering and absorption results on solar thermal collector black paints
Authors: Barrios David
Published: July 2024

The intrinsic and extrinsic scattering and absorption coefficients of a thin black paint substrate used as a solar thermal collector, deposited on a thick glass substrate, were obtained in an approximated single-layer method, using the new solved equations recently determined from the collimated and diffuse differential equations of the four-flux model, for the intrinsic coefficients, and considering the differential equations of the two-flux model with total light intensities, for the extrinsic coefficients. In a first step, the optical constants were determined from the measurements of regular transmittance and specular reflectance, fitting them to the collimated transmittance and reflectance solutions of the four-flux model. In a second step, the intrinsic coefficients were obtained from the diffuse transmittance and reflectance measurements, considering four forward scattering ratios (for collimated and diffuse light intensities and for forward and backward light directions) and two average crossing parameters (for forward and backward light directions). In a third step, the extrinsic coefficients were obtained, using the new solved equations recently determined considering the total differential equations as the sum of the collimated and diffuse differential equations. Due to the approximated single-layer method, a simple rule of three was applied to the intrinsic and extrinsic results, relating the extinction coefficients calculated from the optical constants to those calculated from the collimated differential equations. The same external and internal diffuse interface reflectance was observed by integrating the collimated interface reflectance up to the critical angle of total internal reflection.
Optical constants and thickness gradients for light intensities in glass substrate layers and for complex electric fields in indium tin oxide (ITO) transparent conductor thin film layer, using Bode and Nyquist wavelength-dependent diagrams
Authors: Barrios David
Published: July 2024

The optical constants of a thin film layer of transparent conductive indium tin oxide (ITO), deposited on a thick glass substrate (G), were obtained for an ITO-G sample using a multilayer matrix method by fitting the regular transmittance and specular reflectance measurements to the collimated equations of the four-flux model, once the optical constants of the glass substrate layer had previously been obtained from a G sample of a single glass substrate layer. The accuracy of the results was validated using a feedback system called the three-extinction matching requirement, that is, obtaining the same extinction coefficients from the optical constants and from the forward and backward collimated differential equations of the four-flux model. To calculate the extinction coefficients of the glass from optical constants, the compression of the wavelength of the incident light in the glass substrate and in the thin ITO film layer was demonstrated, with a thickness less than the wavelength of incident light. The thickness gradients of the forward and backward collimated light intensities, on the glass substrate of the ITOG sample, were compared with those obtained for the single-layer G sample. Then, the thickness gradients for the complex forward and backward electric fields of the ITO thin film layer were obtained and plotted using spectral magnitude and phase Bode plots and new Nyquist plots, i.e. imaginary versus real parts, dependent on wavelength.
Erythemal weighting function adjustment for a correct calculation of UV index in high-altitude cities
Authors: Iza Telmo S. , Vásconez C. L.
Published: July 2024

Andean cities are mostly characterized, and appreciated, by their high elevation. Commonly above 2500m above the sea level. However, a more subtle feature is their proximity to the Equator. These two characteristics provide these cities with unique climatological conditions. Complementary to this, the main autoethnography of the zone is “mestizo”, which is characterized by its type of skin (namely types III and IV). These kind of skins are highly adapted to radiation intensity (and atmosphere density) of the equatorial zone. We use measurements of radiation from sensors located at Quito in order to provide a novel method to computing the local ultraviolet-index range risk, taking into account an action spectrum of skin types III and IV, and the recommendations of the World Health Organization. The results of this study could be applied directly to cities with climatological conditions, and with population with skin types, similar to those from the Andean region.
Using VR experience to show new subjects to undergraduate students: HalDron Project.
Authors: Chancay Hugo , Martinez-Gallego Verónica , Perez Silvio , Lobos Juan
Published: July 2024

The present research aimed to test if immersive technologies would help STEM undergraduate students from Ecuador to conceptualize and connect with new subjects. An application was developed for Oculus Quest 2 on Introduction to Radioactivity. The test subjects were presented with a questionnaire containing a theoretical assessment and then were exposed to a short, interactive experience about the topic with audio and video explanations from a Virtual Learning Companion and animations with small interactions and hyper-lapses in the fashion of a futuristic laboratory. A majority of the test subjects were not gamers and had little exposure to virtual reality outside of smartphones or 3D films before the experience. In a posterior questionnaire, results show that regardless of their prior experience, the users obtained a high degree of immersion that helped them understand and develop an interest in the topic. None of the students reduced their initial grade on the questionnaire, 44.8% increased their grades from one to two times, and 44.8% increased their grades 2 times or higher. Another questionnaire was presented to learn about their user experience to understand better how the immersion and their previous exposition, or lack thereof, helped them conceptualize the concepts presented.
Multi-parameter quantum estimation of single- and two-mode pure Gaussian states
Authors: Bressanini Gabriele , Genoni Marco G , Kim M S , Paris Matteo G A
Published: July 2024

We discuss the ultimate precision bounds on the multiparameter estimation of single- and two-mode pure Gaussian states. By leveraging on previous approaches that focused on the estimation of a complex displacement only, we derive the Holevo Cramér–Rao bound (HCRB) for both displacement and squeezing parameter characterizing single and two-mode squeezed states. In the single-mode scenario, we obtain an analytical bound and find that it degrades monotonically as the squeezing increases. Furthermore, we prove that heterodyne detection is nearly optimal in the large squeezing limit, but in general the optimal measurement must include non-Gaussian resources. On the other hand, in the two-mode setting, the HCRB improves as the squeezing parameter grows and we show that it can be attained using double-homodyne detection.