bluuebunny/crossref_metadata_2025 huggingface dataset:
The Relationship between Bone Mineral Densitometry and Visceral Adiposity Index in Postmenopausal Women
Authors: Elmas Halis , Duran Cevdet , Can Mustafa , Tolu Ismet , Guney Ibrahim
Published: March 2023

Objective It was aimed to compare visceral adiposity index (VAI) levels in patients with normal bone mineral density (BMD), osteopenia, and osteoporosis.

Methods One hundred twenty postmenopausal women (40 with normal BMD, 40 with osteopenia, and 40 with osteoporosis) between the ages of 50 to 70 years were included in the study. For females, the VAI was calculated using the formula (waist circumference [WC]/[36.58 + (1.89 x body mass index (BMI))]) x (1.52/High-density lipoprotein [HDL]-cholesterol [mmol/L]) x (triglyceride [TG]/0.81 [mmol/L]).

Results The time of menopause from the beginning was similar in all groups. Waist circumference was found to be higher in those with normal BMD than in the osteopenic and osteoporotic groups (p = 0.018 and p < 0.001, respectively), and it was also higher in the osteopenic group than in the osteoporotic group (p = 0.003). Height and body weight, BMI, blood pressure, insulin, glucose, HDL-cholesterol, and homeostasis model assessment-insulin resistance (HOMA-IR) levels were similar in all groups. Triglyceride levels were found to be higher in the normal BMD group, compared with the osteoporotic group (p = 0.005). The level of VAI was detected as higher in those with normal BMD, compared with the women with osteoporosis (p = 0.002). Additionally, the correlation analysis showed a positive correlation between dual-energy X-ray absorptiometry (DXA) spine T-scores, WC, VAI, and a negative correlation between DXA spine T-scores and age.

Conclusion In our study, we found higher VAI levels in those with normal BMD, compared with women with osteoporosis. We consider that further studies with a larger sample size will be beneficial in elucidating the entity.
Recent progress in polymeric gene vectors: Delivery mechanisms, molecular designs, and applications
Authors: Xiu Kemao , Zhang Jifeng , Xu Jie , Chen Y. Eugene , Ma Peter X.
Published: March 2023

Gene therapy and gene delivery have drawn extensive attention in recent years especially when the COVID-19 mRNA vaccines were developed to prevent severe symptoms caused by the corona virus. Delivering genes, such as DNA and RNA into cells, is the crucial step for successful gene therapy and remains a bottleneck. To address this issue, vehicles (vectors) that can load and deliver genes into cells are developed, including viral and non-viral vectors. Although viral gene vectors have considerable transfection efficiency and lipid-based gene vectors become popular since the application of COVID-19 vaccines, their potential issues including immunologic and biological safety concerns limited their applications. Alternatively, polymeric gene vectors are safer, cheaper, and more versatile compared to viral and lipid-based vectors. In recent years, various polymeric gene vectors with well-designed molecules were developed, achieving either high transfection efficiency or showing advantages in certain applications. In this review, we summarize the recent progress in polymeric gene vectors including the transfection mechanisms, molecular designs, and biomedical applications. Commercially available polymeric gene vectors/reagents are also introduced. Researchers in this field have never stopped seeking safe and efficient polymeric gene vectors via rational molecular designs and biomedical evaluations. The achievements in recent years have significantly accelerated the progress of polymeric gene vectors toward clinical applications.
Simulating supercontinua from mixed and cascaded nonlinearities
Authors: Voumard Thibault , Ludwig Markus , Wildi Thibault , Ayhan Furkan , Brasch Victor , Villanueva Luis Guillermo , Herr Tobias
Published: March 2023

Nonlinear optical frequency conversion is of fundamental importance in photonics and underpins countless of its applications: Sum- and difference-frequency generation in media with quadratic nonlinearity permits reaching otherwise inaccessible wavelength regimes, and the dramatic effect of supercontinuum generation through cubic nonlinearities has resulted in the synthesis of broadband multi-octave spanning spectra, much beyond what can be directly achieved with laser gain media. Chip-integrated waveguides permit to leverage both quadratic and cubic effects at the same time, creating unprecedented opportunities for multi-octave spanning spectra across the entire transparency window of a nonlinear material. Designing such waveguides often relies on numeric modeling of the underlying nonlinear processes, which, however, becomes exceedingly challenging when multiple and cascading nonlinear processes are involved. Here, to address this challenge, we report on a novel numeric simulation tool for mixed and cascaded nonlinearities that uses anti-aliasing strategies to avoid spurious light resulting from a finite simulation bandwidth. A dedicated fifth-order interaction picture Runge–Kutta solver with adaptive step-size permits efficient numeric simulation, as required for design parameter studies. The simulation results are shown to quantitatively agree with experimental data, and the simulation tool is available as an open-source Python package (pychi).
MBE growth and abnormal magnetic behaviors of epitaxial Fe100−xGax on SrTiO3
Authors: Tran Thi Toan , Vu Thi Hoa , Pham Anh Tuan , Nguyen Thi Huong , Nguyen Van Quang , Hwang Chanyong , Cho Sunglae
Published: March 2023

Here, we present the magnetic behaviors of disordered bcc α-Fe phase Fe100−xGax (x = 10, 20, and 30) thin films grown on a SrTiO3 substrate using molecular beam epitaxy. With the Ga content increasing from 10% to 30%, the saturation magnetization decreased from 1575 to 991 emu/cm3 while the coercivity increased from 23 to 197 Oe. A two-step-hysteresis loop was observed in all films. Specifically, the hysteresis loop of the film with 10% Ga concentration reveals an obvious kink. Magneto-optical Kerr images confirmed the abnormal magnetic domain switching in the films, which is due to the appearance of perpendicular domains under external magnetic field.
Structural and queue characterization of a non-Markovian boundary value problem
Authors: Karthikeyan K. , Maragathasundari S. , Kameswari M.
Published: March 2023

In this study, we investigate a single server architecture in which the customer service system is not aware of the length of the line that was sent to them. Thus, the system-controlling equations here become what are known as the vacation differential equations. Here, we argue specifically that this vacation is what is causing the oscillations in the performance measurements of the system. The symbolic structure of the differential equation of the non-Markovian queuing problem is introduced in this study. A procedure of maintenance work is included in this model in terms of the vacation stage to support this minimal non-interrupted service system. The findings offer a thorough analysis of the system that enables it to operate more profitably even if it is interrupted by any associated activities. The supplemental variable method solves the queuing problem caused by the aforementioned subsequent outcomes. Estimates are made for the queue size, server idle time, use, and probability generating factors for each operating method. Numerical analysis was performed on specific examples using mathematical software. This strategy is perfectly acceptable because it is regularly employed and makes use of a statistical demarcation method. The graphical representation of this perspective provides precise calculations of the apparent constraints.
Wearable pulmonary monitoring system with integrated functional lung imaging and chest sound recording: a clinical investigation in healthy subjects
Authors: Frerichs I , Paradiso R , Kilintzis V , Rocha B M , Braun F , Rapin M , Caldani L , Beredimas N , Trechlis R , Suursalu S , Strodthoff C , Pessoa D , Chételat O , Paiva R P , de Carvalho P , Maglaveras N , Weiler N , Wacker J
Published: March 2023

Objective. Current wearable respiratory monitoring devices provide a basic assessment of the breathing pattern of the examined subjects. More complex monitoring is needed for healthcare applications in patients with lung diseases. A multi-sensor vest allowing continuous lung imaging by electrical impedance tomography (EIT) and auscultation at six chest locations was developed for such advanced application. The aims of our study were to determine the vest’s capacity to record the intended bio-signals, its safety and the comfort of wearing in a first clinical investigation in healthy adult subjects. Approach. Twenty subjects (age range: 23–65 years) were studied while wearing the vests during a 14-step study protocol comprising phases of quiet and deep breathing, slow and forced full expiration manoeuvres, coughing, breath-holding in seated and three horizontal postures. EIT, chest sound and accelerometer signals were streamed to a tablet using a dedicated application and uploaded to a back-end server. The subjects filled in a questionnaire on the vest properties using a Likert scale. Main results. All subjects completed the full protocol. Good to excellent EIT waveforms and functional EIT images were obtained in 89% of the subjects. Breathing pattern and posture dependent changes in ventilation distribution were properly detected by EIT. Chest sounds were recorded in all subjects. Detection of audible heart sounds was feasible in 44%–67% of the subjects, depending on the sensor location. Accelerometry correctly identified the posture in all subjects. The vests were safe and their properties positively rated, thermal and tactile properties achieved the highest scores. Significance. The functionality and safety of the studied wearable multi-sensor vest and the high level of its acceptance by the study participants were confirmed. Availability of personalized vests might further advance its performance by improving the sensor-skin contact.
Updated constraints on axion-like particles from temporal information in supernova SN1987A gamma-ray data
Authors: Hoof Sebastian , Schulz Lena
Published: March 2023

We revise gamma-ray limits on axion-like particles (ALPs) emitted from supernova SN1987A based on Solar Maximum Mission data. We improve and simplify the computation of the expected gamma-ray signal from ALP decays, while also extending it to non-instantaneous ALP emission. For the first time we make use of the temporal information in the data to update the associated ALP-photon coupling limits. For ALP decays, our updated likelihood only mildly affects the limit compared to previous works due to the absorption of gamma rays close to SN1987A. However, for ALP conversions in the Galactic magnetic field, temporal information improves the limit on the ALP-photon coupling by a factor of 1.4.
Stability and multistability of synchronization in networks of coupled phase oscillators
Authors: Zhai Yun , Wang Xuan , Xiao Jinghua , Zheng Zhigang
Published: March 2023

Coupled phase oscillators usually achieve synchronization as the coupling strength among oscillators is increased beyond a critical value. The stability of synchronous state remains an open issue. In this paper, we study the stability of the synchronous state in coupled phase oscillators. It is found that numerical integration of differential equations of coupled phase oscillators with a finite time step may induce desynchronization at strong couplings. The mechanism behind this instability is that numerical accumulated errors in simulations may trigger the loss of stability of the synchronous state. Desynchronization critical couplings are found to increase and diverge as a power law with decreasing the integral time step. Theoretical analysis supports the local stability of the synchronized state. Globally the emergence of synchronous state depends on the initial conditions. Other metastable ordered states such as twisted states can coexist with the synchronous mode. These twisted states keep locally stable on a sparse network but lose their stability when the network becomes dense.
Transport properties of CrP
Authors: Zhou Xuebo , Zheng Ping , Wu Wei , Sui Yu , Luo Jianlin
Published: March 2023

CrP has many exotic physical properties due to a four-fold degenerate band crossing at the Y point of the Brillouin zone, which is protected by the nonsymmorphic symmetry of the space group. We carried out the heat capacity, electrical and thermal transport measurements on CrP and extracted the electron thermal conductivity. Due to the difference in energy and momentum relaxation time during electron–phonon inelastic scattering, the normalized Lorentz number decreases below about 160 K. Below 25.6 K, the normalized Lorentz number begins to recover, which is due to the dominance of elastic scattering between electrons and defects at low temperatures.
A center of mass free equation of motion method and its application to 4He
Authors: Veselý P. , De Gregorio G. , Knapp F. , Lo Iudice N.
Published: March 2023

We report on an upgraded version of the equation of motion phonon method (EMPM) which exploits the singular value decomposition (SVD) of rectangular matrices to decouple completely and exactly the intrinsic from the center of mass (c.m.) translational motion under no restrictions and for an arbitrary single particle (s.p.) basis. Its numerical implementation on 4He illustrates the way such a decoupling is achieved and its important effects on spectra and nuclear response functions.
Study of the one-neutron transfer reaction in 18O + 76Se collision at 275 MeV in the context of the NUMEN project
Authors: Ciraldo Irene , Cappuzzello F. , Cavallaro M. , Carbone D. , Burrello S. , Spatafora A. , Gargano A. , De Gregorio G. , Magaña Vsevolodovna R. I. , Acosta L. , Agodi C. , Amador-Valenzuela P. , Borello-Lewin T. , Brischetto G. A. , Calabrese S. , Calvo D. , Capirossi V. , Chávez Lomeli E. R. , Colonna M. , Delaunay F. , Djapo H. , Eke C. , Finocchiaro P. , Firat S. , Fisichella M. , Foti A. , Hacisalihoglu A. , Iazzi F. , La Fauci L. , Linares R. , Medina N. H. , Moralles M. , Oliveira J. R. B. , Pakou A. , Pandola L. , Petrascu H. , Pinna F. , Russo G. , Santopinto E. , Sgouros O. , Guazzelli M. A. , Solakci S. O. , Soukeras V. , Souliotis G. , Torresi D. , Tudisco S. , Yildirim A. , Zagatto V. A. B.
Published: March 2023

Heavy-ion one-nucleon transfer reactions are promising tools to investigate single-particle configurations in nuclear states, with and without the excitation of the core degrees of freedom. An accurate determination of the spectroscopic amplitudes of these configurations is essential for the study of other direct reactions as well as beta-decays. In this context, the 76Se(18O,17O)77Se one-neutron transfer reaction gives a quantitative access to the relevant single particle orbitals and core polarization transitions built on 76Se. This is particularly relevant, since it provides data-driven information to constrain nuclear structure models for the 76Se nucleus.

The excitation energy spectrum and the differential cross section angular distributions of this nucleon transfer reaction was measured at 275 MeV incident energy for the first time using the MAGNEX large acceptance magnetic spectrometer. The data are compared with calculations based on distorted wave Born approximation and coupled channel Born approximation adopting spectroscopic amplitudes for the projectile and target overlaps derived by large-scale shell model calculations and interacting boson-fermion model.

These reactions are studied in the frame of the NUMEN project. The NUMEN (NUclear Matrix Elements for Neutrinoless double beta decay) project was conceived at the Istituto Nazionale di Fisica Nucleare–Laboratori Nazionali del Sud (INFN-LNS) in Catania, Italy, aiming at accessing information about the nuclear matrix elements (NME) of neutrinoless double beta decay (0νββ) through the study of the heavy-ion induced double charge exchange (DCE) reactions on various 0νββ decay candidate targets. Among these, the 76Se nucleus is under investigation since it is the daughter nucleus of 76Ge in the 0νββ decay process.
Efficient few-body calculations in finite volume
Authors: König S
Published: March 2023

Simulating quantum systems in a finite volume is a powerful theoretical tool to extract information about them. Real-world properties of the system are encoded in how its discrete energy levels change with the size of the volume. This approach is relevant not only for nuclear physics, where lattice methods for few- and many-nucleon states complement phenomenological shell-model descriptions and ab initio calculations of atomic nuclei based on harmonic oscillator expansions, but also for other fields such as simulations of cold atomic systems. This contribution presents recent progress concerning finite-volume simulations of few-body systems. In particular, it discusses details regarding the efficient numerical implementation of separable interactions and it presents eigenvector continuation as a method for performing robust and efficient volume extrapolations.
Microscopic Optical Potentials: recent achievements and future perspectives
Authors: Finelli Paolo , Vorabbi Matteo , Giusti Carlotta
Published: March 2023

Few years ago we started the investigation of microscopic Optical Potentials (OP) in the framework of chiral effective field theories [1, 2] and published our results in a series of manuscripts. Starting from the very first work [3], where a microscopic OP was introduced following the multiple scattering procedure of Watson [4], and then followed by Refs. [5, 6], where the agreement with experimental data and phenomenological approaches was successfully tested, we finally arrived at a description of elastic scattering processes off non-zero spin nuclei [7]. Among our achievements, it is worth mentioning the partial inclusion of three-nucleon forces [8], and the extension of our OP to antiproton-nucleus elastic scattering [9]. Despite the overall good agreement with empirical data obtained so far, we do believe that several improvements and upgrades of the present approach are still to be achieved.

In this short essay we would like to address some of the most relevant achievements and discuss an interesting development that, in our opinion, is needed to further improve microscopic OPs in order to reach in a near future the same level of accuracy of the phenomenological ones.
Influence on Harmonic Reducer Coaxiality to Transmission Efficiency of Solar Array Driving Mechanism
Authors: Tan Honggen , Wang Jie , Huang Xiaochu , Han Zili
Published: March 2023

In order to ensure the stability and reliability of the assembly performance of the solar array driving mechanism, research on the influence of assembly and adjustment coaxiality of harmonic reducer to transmission efficiency of solar array driving mechanism was carried out. With the research, the assembly and adjustment coaxiality mode of the harmonic reducer was analyzed. The driving mechanism simulator and harmonic reducer test piece were developed. Based on a piece of special test equipment, a fully systematic test was carried out. According to the characteristics of different products, the assembly and adjustment coaxiality parameters of harmonic reducer can be accurately and reasonably formulated. The best transmission efficiency of the solar array driving mechanism has been achieved. The on-orbit stable operation of the solar array was effectively ensured.
Research on FPGA Functional Reliability based on Petri Net
Authors: Cheng Yongsheng
Published: March 2023

Engineering reliability ground verification for space FPGA devices is one of the important aspects of space load digital system design. At present, there are three methods: code correctness verification, system functional test, and formal verification. Based on the Petri Net theory, this paper proposes a macroscopic and accurate description of the functional characteristics of FPGA engineering with the functional module as the granularity and the control variable as the core. On this basis, combined with the state-reachability graph theory, functional execution reliability is proposed. This evaluation method evaluates the degree of influence of the core control data error on the execution of the system function in a workflow and provides a new basis for the improvement of the protection method and the evaluation of the protective effect.
Aircraft Panel Sound Insulation Testing Techniques and Optimization of Sound Insulation Characteristics
Authors: Zhang Shenghai
Published: March 2023

As the safety of aircraft increases, aircraft comfort is becoming an increasing concern, with aircraft cabin noise being one of the main factors affecting aircraft comfort. To ensure the comfort of the aircraft, it is, therefore, necessary to reduce cabin noise and to ensure that its volume is within an appropriate range. The sound insulation performance of aircraft panels is a key indicator in determining aircraft cabin noise. Based on experimental sound insulation testing techniques, this paper performs tests on the sound insulation of typical panel constructions. Then possible measures to improve the sound insulation performance are discussed with ARJ21 fuselage panels as an example. Results show that the addition of acoustic wool and honeycomb decorative panels, as well as the necessary sealing treatment, can effectively improve the sound insulation capacity of the panels.
Analysis of the Present Situation of the Aerodynamic Stability of Transportation Vehicles
Authors: Fang Tianyang , Shi Yanting , Xu Chang
Published: March 2023

The rise and development of the knowledge of aerodynamics and fluid mechanics have solved many key problems in the engineering field, and have been applied in life. For example, in the aspect of vehicle appearance design, the appearance is often designed to be streamlined to reduce the impact of air resistance on cars in the process of moving forward, and the friction between fluid and aircraft, submarines, and other common appearance designs are considered. It can be seen that the application of fluid mechanics has brought great changes to life. To help reduce air resistance and improve the aerodynamic stability of vehicles, this paper attempts to investigate and summarize the existing improvements in vehicle design. At the end of the paper, a list of pre-designs for automobiles, trains, and aircraft is given, and the applicability of these designs is commented. The review can help the public to understand the cutting-edge improvements in modern vehicle design.
Design of Double Closed Loop Control System for DC Motor Based on TX8C1010 Single Chip
Authors: Wang Zhouyi , Yu Jianding , Lou Yuanchao
Published: March 2023

In order to improve the operational strength and control precision of the DC motor, a double closed-loop control system based on TAIXIN TX8C1010 MCU is proposed. The single chip is based on a high-speed 8051 core, which is applied to home appliances and can realize the double closed-loop motor control algorithm. The given speed value provided by the potentiometer is compared with the real-time speed value and inputs the error to the speed loop function, which is based on the incremental PID algorithm, to calculate the reference current value. Then it is compared with the real-time current value and inputs the error into the current loop. The PWM signal duty cycle is determined by the output value of the current loop to adjust and stabilize the motor speed. The drive circuit outputs the PWM signal in the inverse amplification way to control the operation of the DC motor, and finally tests the function on the MAGTROL M-TEST7 motor test platform. The test results show that the control system has fast response speed, strong load capacity, good robustness and safety. Hence, TAIXIN TX8C1010 single-chip machine is feasible in the DC motor control. It can be improved to strengthen its load characteristics according to the parameters and applied to a variety of power DC motor control.
Research on Dynamic Modeling Measurement and Control of Cable Traction Devices for Electro-Optical Unmanned Systems
Authors: Shen Cheng , Chen Yukang , Zhu Wenliang , Zhang Lianchao , Fan Dapeng
Published: March 2023

In order to realize the high-precision variable direction cable control of the electro-optical unmanned system in non-electromagnetic remote control, a cable traction device measurement and control with characteristics of variable direction traction, rapid installation, and lightweight portability were proposed. Fan-shaped connect rod mechanism and U-shaped groove fixed pulley group were added to it, which can realize multi-direction traction without derailment on the basis of the cable limit and alleviate the cable fracture caused by mechanical wear. Introducing Euler transformation and analyzing the dynamics of the cable, the whole operation process, and the tension detection model was established. A Kalman Filter traction planning method was proposed to solve the problems of inertia delay and emergency stop of the unmanned vehicles after a sudden direction change. In order to verify the effectiveness, an experimental platform for the cable traction system of a 50kg wheeled and 150kg tracked unmanned system was built for simulation and experimental testing. The results show that the cable system has good dynamic variable traction, which can meet the multi-terrain control ability of an electro-optical unmanned system in a complex field environment.
Study on Optimization of Chilldown Process for A New Generation Launch Vehicle
Authors: Zhang Qing , Ye Xin , Sun Yi-long , Zheng Yan , Xu Fei-ran
Published: March 2023

Focused on chilldown procedure of liquid oxygen filling for second stage of a new generation launch vehicle, the method of chilldown through liquid oxygen pump has been put forward and compared with traditional method that of gas pressurization. The results showed that it could reduce total time, lower system state changes, and improve efficiency and reliability of liquid oxygen loading operations. Aimed at liquid oxygen flow of chilldown through the pump, the model of liquid oxygen pump operating has been established by considering variable frequency, regulating valve opening and liquid level of vehicle tank. It can provide scientific guidance and basis for flow control of chilldown through the pump and liquid oxygen tests.
An Effective Small Electrodynamic Shaker Modeling Method
Authors: Li Jinpeng , Deng Ke , Wang Gang , Zhang Gangming , Bai Zhiqing , Yang Lu
Published: March 2023

Currently, the discussion on the modeling method characterized by the small electrodynamic shakers, especially the mathematic analytical method, is relatively sparse. In this paper, taking BK4809 as an example, a modeling method for small shakers based on analytical formulations is discussed. The detailed mathematical analysis and derivation process for the small shakers are performed, and the corresponding modeling formulations are concluded; then, the simulation tests are carried out in MATLAB. Through comparison with the reference data, the validation tests show that based on analytic formulations combined with the MATLAB built-in system identification functions, the results of modeling methods match well with the experiment data, and the concluded method is effective.
Research on the Controller Deployment Strategy of Aviation Information Network
Authors: Fu Haotong , Wang Xiang , Song Xinkang , Peng Cong , Zhao Shanghong
Published: March 2023

With the development of intelligent aviation platforms, Aviation Information Networks (AIN) has emerged as a promising architecture to accommodate various aviation missions. However, the current Airborne Ad Hoc Networks (AANETs) suffer from the challenges of tightly-coupled devices and complex aviation environments. To tackle the issues, the Software Defined Network (SDN) is introduced to manage the AINs by decoupling the control plane from the data plane and allocating the network resources logically. Considering the large-scale and dynamic changing characteristics of the AINs, we utilize the hybrid architecture consisting of multiple controllers to establish the control system. To construct the AIN of the SDN paradigm, the first issue that needs to be reckoned with is the controller deployment. This paper proposes a controller deployment strategy that includes network division and regional deployment. Firstly, the network is rapidly divided into areas according to the key performance indicators of the network, and then the platform with the highest reliability is selected as the controller to be deployed in each area. The experimental results show that the proposed algorithm has low computational complexity and can effectively improve the network performance in terms of average requirement delay, load balance index, controller deployment cost, and reliability, which is suitable for addressing the controller deployment issue in aviation scenarios.
Research on Cascading Effect Analysis of Civil Aircraft Inertial Reference System Parameters Failures
Authors: Wang Yuqing , Shi Zhijian
Published: March 2023

Inertial Reference System (IRS) is one of the important onboard systems; it can provide the attitude, heading, angle rate and accelerations, etc. to the display system, flight control system and other systems on the aircraft; and it can be the navigation source of the flight management system to provide the position data. The consequences of IRS parameters failure effects are difficult to determine. This paper applies the cascading effect analysis method to carry out IRS parameters failure safety assessment. A method is given to identify the initiating state of the IRS parameters. An initiating state of IRS parameters is taken as an example to analyze safety effects and obtain the aircraft-level safety classification. The safety classification is compared with source analysis to determine whether the aircraft safety requirement is met.
Optimization Design of the Wing of Cruise Missile on the Basis of the Vortex Lattice Approach
Authors: Fuzhen Shi , Jinrui Guo , Mingze Ren
Published: March 2023

Aerodynamic performance of missile wings is a vital factor affecting the endurance and combat effectiveness of cruise missiles. Given the current situation that the aerodynamic design of conventional cruise missile wings is less and there is more room for improvement, a missile wing shape with a winglet is considered designed to improve the cruise characteristics of cruise missiles effectively. Firstly, the EPPLER 66 is selected as the wing shape by the combination of vortex surface element approach batch calculation and CFD simulation analysis. According to the dimensional parameters of a typical patrol wing, the design variables and corresponding optimization intervals are determined, and the aerodynamic optimization is carried out by combining the genetic approach as well as the vortex lattice approach. CFD is used to verify the aerodynamic performance of the optimized wing. The calculation outcomes reveal that the optimized wing has a ratio of lift-to-drag of 23.43, which is 12.32% higher than that of the conventional flat wing.
Application of Cascading Effect Analysis Method in Air Data Failure Impact Grading
Authors: Qiu Zhifan , Wang Yuqing
Published: March 2023

Air data for civil aircraft provides important flight information and is the basis for guiding pilots to maneuver the aircraft. It is necessary to clarify the impact of air data failure on the aircraft and pilot operation. By formulating the principles of Cascading Effect Analysis(CEA) of air data failure, including failure scenario determination, direct impact judgment, indirect impact analysis, and comprehensive impact analysis of the whole aircraft, this paper studies the problem of grading the impact of air data failure based on CEA Method. The architecture of the air data system and the data voting logic, and the air data failure mechanism are analyzed so as to define the air data failure scenarios. Using CEA Method, this paper analyzes all the impacts of air data failure on aircraft systems iteratively, determines the impact on the whole aircraft and flight operations, and judges whether the impact results meet the analysis expectations.
Scheme Design and Simulation Analysis of Recoverable Rocket Based on Rotor
Authors: Tao Zhelun , Li Zechen , Yu Peng , Zhong Sheng
Published: March 2023

The reuse of rockets is one of the most important methods to reduce launch costs. Based on the design scheme of the “Roton” space helicopter, this paper proposes a recovery method for rockets - rotors, which can not only accurately control the landing posture but also have high fuel utilization. To recover the first stage of the rocket, this paper carries out the scheme design and sets up the landing deceleration action with the engine reverse thrust and rotor lift. The simulation result shows that the scheme allows the first stage of the rocket to land safely, which provides a theoretical reference for engineering development in the future.
Time-space intelligent management and dispatch of electric Beidou based on Beidou and digital twin technology
Authors: Su Zanyou , Lin Liming , Wang Yifei
Published: March 2023

Aiming at the increasingly complex management and dispatching problems of power system, this paper combines Beidou precise space-time technology with digital twin system theory, and puts forward a method of constructing intelligent management and dispatching platform of power grid. The method combines Beidou and IoT (Internet of Things) sensors to form a digital twin management and scheduling platform which can perform state prediction, fault diagnosis, self-healing and other functions. Firstly, this paper analyzes the overall architecture of Beidou digital power twin system, then discusses the construction method of digital twin in power system from the aspects of digital twin modeling theory, data acquisition intelligent terminal based on Beidou, operation mode of digital twin platform, etc. Finally, the application test analysis is carried out. The research results show that the method proposed in this paper has reference value for improving the management and dispatching capability of smart grid.
Study of the Hydraulic Characteristics of Slug Flow in the Microfluidic Y-shaped Junctions of Three Different Cross Angles
Authors: Han Yu
Published: March 2023

The slug flow in microchannels has been applied for microdroplet/bubble production in recent years. The comparison investigation of hydrodynamic properties of slug flow in three different Y-shaped microchannels was conducted by numerical methods. The numerical simulation results show that the VOF model can describe the velocity and pressure field in the Y-shaped microchannel. It was found that the pressure in the microchannel from upstream to downstream showed an overall decreasing trend, and the liquid phase pressure between the two gas slugs was less than the internal pressure of the adjacent gas slug. The midline pressure of the bubble generation moment is less than the rest of the state. Among the three Y-shaped junctions, the absolute value of the pressure difference at the moment of slug bubble formation is the smallest when the angle of the Y-junction is 90°. Compared to 120° and 90° Y-junctions, the pressure and velocity field of the 60° Y-junction is the most unstable when the slug flow generates.
Study of Near-field Acoustic Pressure in Near-coastal Ice-water Media Based on Angular Spectrum Method
Authors: Wang Chen , Zhang Hua
Published: March 2023

For seawater detection, acoustic means is currently one of the most promising technical means of development. According to the physical properties of acoustic waves, they can be effectively propagated in seawater and ice, and at the interface of different media, there will be reverse acoustic scattering. Using the theory of acoustic propagation in solids, the propagation velocity and refractive index of transverse and vertical, and taking the longitudinal wave as an example, we use the angular spectrum method to solve the fluctuation equation and obtain the beam angle spectrum. Numerical software simulation calculates the time domain characteristics of acoustic scattering at different incidence angles. The effect of evanescent waves on solid sound transmission is also considered. Considering the effect of apocalyptic waves on thin ice on the ocean surface, it provides a theoretical basis for further research on detecting offshore ice using acoustic methods.
Numerical Simulation Analysis of Flow Noise Characteristics of Underwater Vehicle
Authors: Leng Kaijing , Deng Leilei , Zhang Haozheng , Hao Shijia
Published: March 2023

Based on the standard large eddy simulation and k-epsilon model, the steady flow field and navigation flow noise of the underwater vehicle shell are simulated. In this paper, the underwater vehicle model is established by referring to classic SUBOFF model. The standard k-epsilon method is used to study the pressure distribution characteristic, velocity distribution characteristic, and velocity vector distribution characteristic on and around the shell of the underwater vehicle at different speeds. The results indicate that the pressure increases with the increase of the speed and in the bow of the shell is the largest. A large eddy simulation was used to analyze the noise characteristics of sailing flow at different speeds. The results show that the sound pressure level of navigation flow noise is higher in the low-frequency band, and will increase with the increase in speed.
Experimental Study on the Airborne Noise of Rain
Authors: Li Zekun , Liu Hengqi
Published: March 2023

Rainfall noise is investigated experimentally in this paper. The modern high-speed camera and microphone are employed to study both drop dynamics and sound signals. Sound signals produced by single-drop impacts on deep pools, thin liquid films, steel plates, and sandy surfaces were analyzed through a combination of videos and audio. Classical Fourier transforms are performed for converting the original signal to a power spectrum. Results show that in the deep-water cases, the noise is proved to be the entrapment of a tiny breathing bubble that sheds from the dimple. The dominant frequencies of droplets impacting water film, rigid walls, and sandy surfaces are much compared with deep pool cases.
Research on Robust CS-DOA Estimation Method Based on Signal Sparsity Reconstruction
Authors: Su Peilin , Huang Di , Zhu Jieqi
Published: March 2023

The application of compressed sensing theory in DOA estimation of underwater signals has always been difficult. Aiming at the slow operation speed of the current L1-SVD algorithm and the poor robustness under various conditions such as multi-array elements, this paper proposes an improved CS-DOA estimation algorithm combined with the greedy algorithm. The algorithm sparsely reconstructs the received signal itself, which effectively improves the strict sparsity of the processed signal. The feasibility of the new algorithm is proved through theoretical analysis and simulation experiments. Compared with the L1-SVD algorithm, the measurement performance under different conditions is significantly improved. It has development prospects in academic research and engineering applications.
Finite Element Analysis of Acoustic Performance of Water-filled Helmholtz Resonator with the Effect of Elastic Cavity Walls
Authors: Su Shengli , Wu Shuyou
Published: March 2023

Water-filled Helmholtz resonator is a primary means to reduce the hydrodynamic noise of pump and valve in naval vessels. The predicted acoustic performance of water-filled Helmholtz resonators with the effect of elasticity of cavity walls using finite element method is compared with theoretical and experimental results in references, which demonstrated the applicability and accuracy of the finite element numerical method. And then, the effect of thickness and materials of cavity walls on resonance frequency and transmission loss of resonators is discussed, including the comparison of rigid and elastic cavity walls predictions simultaneously. The results of the discussion in this paper show that the acoustic performance of water-filled Helmholtz resonators is influenced by the elasticity of cavity walls to a great extent, which must be taken into consideration in the process of design.
Analysis of Intake Performance of Forebody and Inlet on Pre-deformation
Authors: Li Siyi , Liu Lei , Liu Shenshen , Yang Xiaofeng , Wang Ziyi , Du Yanxia
Published: March 2023

Under long cruise conditions, the forebody and inlet of a hypersonic vehicle were sensitive to deform under the aerodynamic thermal load, which hurt aerodynamic characteristics, intake performance, and aircraft safety. A pre-deformation method was proposed by using the numerical method of fluid-thermal-structural coupling based on the in-house software, aiming at the static deformation of a typical forebody-inlet model. Three pre-deformed models were combined by the forebody/inlet deformation and then compared the intake performance between the pre-deformed models and the ideal rigid model. The results show that the pre-deformation of the forebody can not only ensure the intake performance partly but also avoid the risk of excessive pressure on the intake wall. The pre-deformation of the inlet can reduce the flow separation near the ramp wall and reduce the pressure of intake, but it also reduces the total pressure recovery coefficient and affects intake performance negatively.
Optimize the Rectifier Structure to Improve the Accuracy of Gas Ultrasonic Flowmeter Under Low Flow Conditions
Authors: Yang Bin , Zhang Ying , Shi Limiao , Zhan Xingyu
Published: March 2023

With the promotion of the coal-to-gas policy, the consumption of civil natural gas in China is increasing rapidly. Improving the measurement accuracy of the flowmeter is of great significance in reducing transportation costs. Computational fluid dynamics software (FLUENT) was used for simulation, the upstream choke model of a single elbow pipe was established, and the flow field in the urban pipe network’s transition area was analyzed and optimized to improve the existing commercial flow Conditioner. The effects of the Reynolds number, the installation location of the ultrasonic gas flowmeter, and aperture depth on measurement accuracy were investigated. The results show that installing the flow Conditioner can improve the velocity distribution of the flow field in the pipeline. Optimizing the flow Conditioner can shorten the installation position of the flowmeter. The optimum thickness of the flow Conditioner is 0.25D. The research results provide important theoretical significance and application value for improving the industry’s ultrasonic gas flowmeter measurement accuracy.
Three-Dimensional Computational Fluid Dynamics Simulation of the Turbine Blades of a Micro Turbojet Engine
Authors: Zhang Haotian
Published: March 2023

Micro turbojet engine has been widely used in both civil and military applications and their turbine blades are the key components that determine their performance. The paper analyses the influence of adjusting rotational speed and attack angle on the pressure ratio and kinetic energy efficiency of a typical type of micro turbojet engine named KJ66 using computational fluid dynamics in three-dimensional. The objective is to analyse a basic research methodology using CFD for future micro turbojet engine research and workshops to maximize efficiency. Once the related statistic and the aerodynamic performance characteristic are obtained, the attack angle and rotational speed of the turbine blade can be set respectively according to the actual requirements to meet the needs of users. Based on the simulation results, it can be derived that the highest efficiency is 93.46% at the attack angle change of -10° and rotational speed of 110000 rpm. However, the numerical simulation of other conponents such as nozzle are not included in this paper. Therefore, the results would be more accurate and convictive if the object of research can be extended to the entire micro turbojet engine.
Research on Process and Mechanical Properties of PLA Composites in Melt Deposition Molding Based on Computer Software Analysis
Authors: Cui Haijun , Meng Fanrong , Yong Ping
Published: March 2023

Fused deposition polylactic acid (PLA) von berg system materials have been widely used in automotive, aerospace and other fields, and in these areas, inevitably need under static load and dynamic load, so the fused deposition PLA materials under quasi-static and dynamic loading of mechanical properties, establish its parameters such as temperature and strain rate, and constitutive model is related to material performance evaluation and optimization of fused deposition parameters and key for promoting the development of the fused deposition technology.
Co-N decorated three-dimensional graphene as an efficient electrocatalyst for boosting hydrogen evolution reaction
Authors: Lyu Xiao , Li Sicheng , Chen Hao , Zhou Xianmin , Dong Zhenwei
Published: March 2023

Hydrogen evolution reaction (HER) is important for hydrogen generation. Due to the scarcity and high cost of noble metal-based electrocatalysts, it is eager to develop non-precious metal electrocatalysts. In this work, atomic cobalt decorated on N-doped three-dimensional graphene (Co SA/3D-NG) electrocatalyst has been synthesized. Due to the hierarchical porous structure of three-dimensional graphene by coupling effects between Co and N, the Co SA/3D-NG electrocatalyst exhibits an enhanced HER activity. The potential is -180 mV at -10 mA cm−2 and the Tafel slope is 102.53 mV dec−1. It also presents highly electro-catalytic stability in acidic electrolytes. The work reveals a facile pathway to synthesizing efficient HER electrocatalysts.
Study on the Influence of Cu Content on Phase Transition Characteristics of Fe75Ni(25-x)Cu
x
Elastocaloric Refrigeration Alloys
Authors: Chen JiaXian , Shi YongJun , Li XianFa , JunYuAn  , Yang YaBin
Published: March 2023

In this study, the mechanical alloying (AM) and powder metallurgy (PM) techniques were adopted to synthesize the Fe75 Ni(25-x) Cu
x
elastocaloric refrigeration alloys to research the effect of Cu contents on phase transition characteristics and microstructure of Fe75Ni(25-x) Cux elastocaloric refrigeration alloys. The conclusion was drawn that, with increasing Cu content, the phase transition characteristics changed and presented different changing trends. It was found that the phase enthalpy change value was 43.34J/g when the Cu content was 7at%, which was about 1.26 times of Fe15Ni (wt%) alloy. In addition, the FeNiCu alloy was a single-phase alloy with a crystal space group structure of Im-3m when the Cu content was 7at%, and the FeNiCu alloy was a two-phase alloy with crystal space group structures of Im-3m and Fm-3m when the Cu content was more than 7at%. This study provided an experimental basis for the theoretical investigation of the phase transition mechanism of FeNiCu elastocaloric refrigeration alloys.
Study on the Influence of Wire Electrical Discharge Machining on Fatigue Properties of Q345B Materials
Authors: Wang Yue , Wang Cuiying
Published: March 2023

To study the effect of wire electrical discharge machining (WEDM) on the fatigue performance of materials, the mechanical properties of Q345B material used in the grader frame were tested by the single-surface and double-surface of WEDM in this paper. Through the comparison and analysis of the test results, it is found that the yield strength and fatigue strength of the material processed by double-surface machining are 5.2% and 4.2% higher than those processed by single-surface machining, and the tensile strength has no obvious change.