bluuebunny/crossref_metadata_2025 huggingface dataset:
Study on aerodynamic force and aerothermal effect of two-dimensional wedge wave rider with different passivation shape of the head
Authors: Guo Liuming , Fang Shuzhou
Published: December 2022

With the rapid development of space technology, hypersonic vehicles flying at altitudes of 20-100 km near space are showing more and more important application value, and how to solve the serious aerodynamic heating problem caused by hypersonic vehicles in the process of flight is the focus of current research. In this paper, the simplified two-dimensional wedge-shaped waveride is treated with the passivation leading edge by the Computational Fluid Dynamics (CFD) method, and the aerodynamic and aerothermal properties of the hypersonic continuous flow basin are numerically simulated. The flow field structure of the model is analyzed, and the law of heat-resistant rise is revealed. The research contents mainly include the characteristics of body head heat flux and body lift-drag ratio under different passivation shapes. Within the research scope: 1. The larger the passivation radius, the more effective it is to reduce the head heat flux. When the passivation radius is 2 mm, the reduction is about 82.5%. 2. The larger the passivation radius, the more serious the lift-drag ratio reduction. When the passivation radius is 2mm, the maximum reduction is about 72.4%; 3. The four passivation leading edge modes have the best thermal protection effect when the passivation radius R is the same, and the lift-drag ratio of the Bezier curve passivation leading edge mode is the largest.
Impact Analysis of Thermo-mechanical Deformation to the Unlocking Performance of Locking Device for Manipulator on Chinese Space Station
Authors: Zhang Li , Tang Zixin , Chen Ming , Fu Yang , Li Delun , Ma Kai
Published: December 2022

As one kind of large-scale on-orbit deployable motion mechanism, the launch state of the manipulator on the Chinese Space Station is fixed on the external surface of the Tian-He module by 41 locking-releasing devices. It covers an area of 3.5 meters in arc length and 4.6 meters in length. The locking-releasing device should not only be able to withstand the environmental load conditions of the launch stage and in-orbit stage but also can release the manipulator reliably after going through the thermal and dynamic changes. Three factors cause the deformation of the locking-releasing device before unlocking the manipulator. The first deformation is caused by the module from the atmospheric conditions to the vacuum conditions. The second deformation is thermal deformation which is caused by the temperature changes in the module and manipulator. The locking-releasing devices bear the overload force during the launch stage will cause the third deformation. The numerical simulating analysis shows that the deformation is not beyond the allowable range. The manipulator was unlocked successfully after it was launched together with the Tian-He module. It is verified that the deformation caused by the change of thermo-mechanical conditions from the launch stage to the orbit stage does not affect the unlocking performance of the locking-releasing device.
Application of different porous materials for hydrogen storage
Authors: Wang Yujue
Published: December 2022

Energy is regarded as a key resource that may encourage numerous companies to expand and flourish given the rapid advancement of technology. However, due to the contamination of the usage of traditional fossil fuels, deploying new and clean energy resources is the concentrated solution. New energy sources such as wind energy and solar energy are constantly being developed. In addition, three methods exist for storing hydrogen that is a typical clean energy source, including compressed gas storage, cryogenic liquid gas storage, and hydrogen storage materials via adsorption and desorption. As a result, hydrogen storage is receiving more and more attention, and different hydrogen storage materials have been developed. This research will introduce the application of four different types of porous materials in the field of hydrogen storage, including zeolites, activated carbons (AC), carbon nanotubes (CNTs), and metal-organic frameworks (MOFs). Hydrogen can be successfully adsorbed on these materials to varying degrees through chemisorption and physisorption. For improving the hydrogen storage capability (HSC), synthetic strategies such as doping metal elements and synthesizing composite porous materials were designed and used to enhance the hydrogen storage properties of the materials. In the future, satisfying the U.S. Department of Energy (DOE) target would stimulate more and more great-performing porous materials to be synthesized, which can provide a new idea for new hydrogen storage technologies.
Research on the vacuum aging performance of HTPB propellant based on the DSC method
Authors: Tang Yuqing , Deng Hanyu , Liao Tenghui , Qi Yingjian
Published: December 2022

The space environment has extreme conditions such as high vacuum and rapid temperature changes, which will lead to problems such as energy drop, irregular burning rate, and abnormal ignition of solid propellants. To obtain the space aging law of HTPB propellant, the aging performance of HTPB (hydroxyl-terminated polybutadiene) propellant in a vacuum environment was studied and compared with that under the atmosphere. According to the DSC test results of the propellant before and after aging, the behaviors of oxidative crosslinking, chain-scission degradation, and oxidant decomposition during the aging process of solid propellant were investigated. The research showed that the low-temperature endothermic peak and “V-type” high-temperature exothermic peak temperature of HTPB propellant increased after aging, and the high-temperature peak bifurcated into “W-type” double peaks. The right peak caused by the “decarboxylation” reaction was more obvious after atmospheric aging while the left peak caused by AP decomposition was remarkable after vacuum aging. In addition, the oxidative crosslinking reaction occurred after aging, and the activation energy characterized by low-temperature peaks continued to increase. In the later stage of atmospheric aging, chain-scission degradation occurred due to OA moisture absorption, and the activation energy decreased. It firstly increased by 126% within 93 days, and then decreased by 23.4%. No degradation and chain-scission reaction occurred in a vacuum environment, the crosslinking reaction rate was high, and the activation energy increased by 40.4% within 49 days. After the aging of the HTPB propellant, the internal AP decomposed, and the activation energy characterized by the high-temperature exothermic right peak continued to increase. The activation energy increased by 40.5% within 49 days after vacuum aging, and increased by 29.9% within 93 days after atmospheric aging, indicating that the decomposition of AP in the HTPB propellant was more obvious under a vacuum environment.
Analysis and Research on Vibration Characteristics of Nuclear Centrifugal Pumps Rotor Rubbing Fault
Authors: Luo Xiaohui , Yang Jie
Published: December 2022

To investigate the vibration characteristics of nuclear centrifugal pumps rotor rubbing fault, the mechanical model of rotor rub is established, and the causes, types, and mechanisms of rotor rub fault are introduced. Taking the HAZ50-250 Type Horizontal single-stage centrifugal pump prototype as the object, through a reasonable test scheme, the vibration test and analysis of the rotor under different rub conditions were carried out using the Enpac2500 Dual channel spectrum analyzer, and the fault data of different rub impact degrees were collected. Combining the characteristics of vibration parameters such as time-domain, frequency-domain, and axis trajectory, it is found that the time-domain signal of rub fault shows an obvious “Top Clipping phenomenon.” The frequency-domain signal is mainly concentrated in one-time rotation frequency, two times rotation frequency, and a large number of nonlinear high harmonics. The axis trajectory will produce a concave image in the rub direction. In the actual rotor rub vibration fault diagnosis, it is necessary to comprehensively judge the vibration caused in combination with the operating state of the centrifugal pump, the state of the time domain, the frequency domain, and the axis trajectory. Based on the analyzed spectrum characteristics of the rub impact vibration, it is applied to the vibration fault diagnosis case of the centrifugal pump in the power plant, which timely prevents the pump damage and other faults caused by the deterioration of the rub impact fault, and plays a key role in the safe and stable operation of the centrifugal pump. It also provides an important reference for pump design and vibration fault diagnosis of rotating equipment in nuclear power plants.
GPU-Accelerated infrared signature analysis model based on the Reverse Monte Carlo method
Authors: Liu Xinyuan , Yang Qingzhen , Shi Yongqiang
Published: December 2022

High-fidelity scene simulations are now possible thanks to advancements in computer technology. A fast analysis model for target infrared signature was developed by using the Graphics Processor Unit (GPU) device. The Malkmus statistical narrow band model is used to calculate the gas band-averaged transmittance. Mie scattering theory is used to calculate the particle scattering parameters, and based on the assumption that particles scatter light independently, the albedo and phase functions of the participating media are determined. The Reverse Monte Carlo method (RMCM) is used to complete the radiative transfer. Finally, a GPU device is used to accelerate the ray tracing process and achieve fast calculation of radiation. The calculation results show that the fast analysis model with high accuracy, and compared to Central Processing Unit (CPU) serial programs, the computational performance is greatly improved, with an acceleration ratio of more than 60. The thread block size has a significant impact on the occupancy and acceleration ratio, and the highest computational performance is obtained with the thread block size of 128. The scattering will reduce the acceleration ratio of the fast analysis model, and the performance will be reduced as the particle mass flow rate increases.
Study on electrical conductivity of detonation products of aluminized explosives
Authors: Yao Baoxin , Cao Bing
Published: December 2022

Using the thermodynamic equilibrium constant method and JWL-Miller equation of state, based on the calculation of the thermodynamic parameters such as the composition, pressure, and explosion temperature of the detonation products of aluminized explosives in the Magnetocumulative generator, the Saha ionization equation, and gas conductivity calculation model are used to write Matlab code to calculate the electron density and conductivity of the detonation products of the magnetic flux compression generator. The temporal and spatial variation law of electron density and conductivity is revealed. The simulation shows that the thickness of the maximum conductivity layer in the detonation process is about 1 mm and moves at a uniform speed following the CJ surface. The maximum conductivity of HMX/Al (70/30) is 1.88e5 Ω−1·m−1, with an error of 6%, and the maximum conductivity of RA1 (HMX / DNAN / Al) is 2.7e4 Ω−1·m−1
Research on foreign object damage and grinding repair schemes of compressor blades
Authors: Daiand Hongfu Zuo Weijie
Published: December 2022

Foreign object damage (FOD) on compressor blades of aero-engines lowers the capacity of blades and poses a serious threat to civil aviation safety, so the repair of blades with FOD deserves more attention. The finite element model of the aero-engine compressor blade was established, and the finite element analysis was carried out on the damaged blades with FOD notches and the blades after grinding and repair. The natural frequencies of different types of blades and the global and local peak stress under rotating conditions were compared. It was confirmed that the stiffness of the repaired blades was acceptable, and the optimal grinding repair scheme was selected.
A yaw attitude determination method based on coarse sun sensor information for the GEO satellite
Authors: Yin Jing , Liu Jiang , Yang Fan
Published: December 2022

The coarse sun sensor is used to measure the satellite’s attitude relative to the sun. If the satellite can maintain the earth-pointing attitude by the high-precision sensor, the coarse sun sensor information can be used to determine the satellite’s yaw attitude, which is effective in coping with the short-term failure of the satellite’s yaw attitude sensor. This paper proposes a method to determine the yaw attitude of the satellite using the coarse sun sensor information. In view of the main factors affecting the accuracy of the coarse sun sensor, the measures to improve the yaw accuracy are proposed: the sensor calibration method based on historical data and effective measurement range selection. Simulation with satellite onboard data, the expected function can be achieved, and by correcting the measurement data, the yaw attitude accuracy can be significantly improved.
Research on factors affecting the assembly accuracy of deployable arms
Authors: Li Pengfei , Lu Ligang , Wu Dongbo , Liang Jiawei , Wang Hui , He Pengpeng
Published: December 2022

A spacecraft deployable arm is one of the key components of spacecraft. The assembly accuracy of space deployable arms restricts the improvement of spacecraft performance. Therefore, it is important to analyze the factors influencing the assembly accuracy of deployable arms to optimize the assembly process. This paper studies the precision assembly of deployable arms, with a spacecraft deployable arm as the specific research object. In the study, the assembly process is modeled theoretically and analyzed by Finite Element Analysis. Finally, the assembly experiment of the deployable arm is carried out based on the research.
Fault analysis and troubleshooting of nitrogen supply system for a ship’s nitrogen generator
Authors: Chen Zuotian , He Xiaodong , Ge Quan , Zhou Yang
Published: December 2022

This paper introduces the working principle and system work flow of the marine nitrogen generator. Emphasis is laid on the air pretreatment subsystem, nitrogen membrane separation subsystem and automatic control system of the nitrogen generator. In view of the automatic alarm shutdown fault of a ship’s nitrogen generator in the course of operation, the reason is analyzed, and it is found that the refrigeration device fault of the nitrogen generator leads to the excessive air temperature before the film inlet group, thus causing the failure shutdown. Finally, the fault location and troubleshooting are carried out.
Structural optimization and fatigue life analysis of landing gear upper lock
Authors: Hou Dingqi , Li Guanghui , Zhu Yan , Wang Yu , Ma Xiaochen , Wang Lipeng , Qiao Jing , Zhao Jun
Published: December 2022

The upper lock is a key component of the landing gear system, and its fatigue life affects its service life and reliability. In this paper, the modal analysis, random vibration analysis, and fatigue life calculation are carried out for the upper lock. According to the analysis results, the upper lock structure is optimized, and the optimization scheme is proposed. The natural frequency, stress, and fatigue life are analyzed, and the scheme meets the design requirements. Finally, the optimized structure is verified to be reasonable and feasible through experiments.
Simulation research on transmission characteristics of double drum excitation governor
Authors: Gang Cheng , Donghua Song , Jianbing Chao , Chao Wang , Zhongsheng Cui
Published: December 2022

Aiming at the disadvantage that traditional permanent magnet governor needs an additional air gap adjusting mechanism, a double-barrel excitation speed adjusting device is proposed, which adjusts the air gap by adjusting current instead of the air gap. Due to the uncertainty of current speed regulation, the simulation design is analyzed. A structural model and key components of excitation speed regulation are designed. Structural characteristics and principles of the model are introduced. Due to the complexity of the multi-physical field, the finite element analysis method is used. Based on the three-dimensional moving eddy current field, the simulation model of the double-barrel excitation governor is established; the variation law and speed characteristics of the electromagnetic field in transient excitation governor are analyzed; the magnetic induction intensity cloud diagram, eddy current density vector diagram, and circumferential variation curve of air gap magnetic induction intensity are obtained, and the relationship between speed difference on output torque under different current is got. The results show that the output torque increases with the increase of excitation current. With the increase in slip ratio, it will first increase and then decrease. Its laws and conclusions can provide a novel method for further design and optimization of excitation governor.
Construction of High Dynamic Flight Closed-loop Simulation System
Authors: Liu Hengyi , Zou Guoji , Meng Bin
Published: December 2022

In this study, a high dynamic flight closed-loop simulation system was designed and based on the flight characteristics of flight combat systems (missiles, fighters, etc.), the real-time simulation of 6DoF (six degrees of freedom) flight parameters such as position, velocity, acceleration, and attitude of typical flight combat system models in high dynamic flight was implemented. The proposed system, together with the high dynamic Beidou RNSS signal simulator and automated test and evaluation device, forms the high dynamic positioning test platform of the flight simulation system and realizes the closed-loop simulation test and verification of the navigation device of the high dynamic flight combat system.
Research and Prospect of Wave maker Design and Wave making Application
Authors: Lin Xiangyang , Wang Xu , Li Kai , Liu Xia , Duan Derong
Published: December 2022

Wave energy is clean energy with huge development potential. At present, structural energy reform is an important issue in my country’s development. Therefore, the research on the application of wave energy can promote the structural reform of my country’s energy to a certain extent. This paper summarizes the history of wave simulation development and the current status of wave applications, and compares and analyzes wave-making by pushing plate-type wave machines, rocking plat-type wave machines, box-type wave machines, and combined wave-making according to different wave-making methods. Machine building characteristics. Combined with the application status of wave energy, the wave energy power generation is summarized, and the economic and technical status of wave energy power generation is described in detail. Finally, the development trend and application prospect of wave application are summarized.
Design and Simulation Study of Shipboard UAV Net Recovery Device
Authors: Wei Xiaoran , Wei Dingjiang , Sui Xianhui , Cao Liyuan , Su Qibin
Published: December 2022

Shipborne UAVs (Unmanned Aerial Vehicles) play an irreplaceable role in the future maritime war. Countries around the world have been studying and looking for a safe and economical way of shipborne recovery. In this paper, based on the technical scheme and performance characteristics of shipborne UAV net collision recovery, a multi-layer recovery net device is proposed for shipborne UAV recovery. Based on the motion model of the shipborne UAV, Simulink software was used to simulate the final guidance stage of the UAV. The results show that the multi-layer recovery net of the shipborne UAV can adapt to the error caused by ship rocking in the process, and make up for the tracking error and net collision error of UAV in 3D motion simulation. This device has a broad application prospect and has reference significance for comprehensively improving the recovery efficiency of UAVs.
G100S axial flow fan simulation comparison analysis
Authors: Li Zehao , Chen Ming , Yang Liusiyu , Liu Liming
Published: December 2022

This paper conducts a comparative simulation for different structural layout schemes of the new G100S axial flow fan, with the motor layout position and its supporting guide vane as the main modification direction, while the fan length and guide tongue angle are appropriately adjusted according to the motor position. CFD analysis and calculation are used to compare and study the performance of the axial-flow fan. The results show that the axial flow fan with rear motor, air outlet cone integration, and large angle guide tongue layout has greater wind speed, longer injection distance, more uniform distribution of outlet flow field traces, greater wind pressure at the air outlet, and faster flow stability convergence. This work will provide technical support for designing orthogonal experiments in the direction of fan miniaturization and lightweight.
Simulation research on thermal protection performance of firefighting robots and design of protection system
Authors: Fei Yuyang , Zhu Xinrui , Wang Xiao
Published: December 2022

In response to manufacturing strategy demand, fire accidents in petroleum, chemical, forestry, and high-rise buildings are on the rise. Although the firefighting robot can replace fire rescue workers who come into the dangerous rescue site, electronic devices’ thermal failure problem caused by high temperatures in the whole electronic equipment problem is bigger. The proportion of electronic device thermal failure has a significant impact on the normal operation of electronic equipment. How to dissipate heat quickly and avoid local high temperatures becomes a key problem. Most domestic and foreign scholars only study the influence of thermal protection materials themselves on robot protection systems, and few study the influence of heat insulation materials and heat dissipation materials on robot protection systems through appropriate structure combinations. Therefore, the establishment of comprehensive high-temperature fire situations on the fire protection robot automatic detection of smoke concentration and temperature of heat insulation material and heat dissipation material composition of folded tensile structure and liquid nitrogen cooling system thermal protection model of robot thermal protection performance research is of great significance, at the same time through COMSOL Multiphysics software to simulate the proposed model, Select the best heat dissipation materials and heat insulation materials, protect the internal electronic components in the fire accident sustained high temperature, can adjust the temperature as soon as possible, make it adapt to the change of temperature field, for the rescue process to gain 2~15 minutes time duration.
Research on space pursuit and escape strategy of spacecraft based on the artificial immune algorithm
Authors: Zhang Xiran , Du Hongfeng , Liu Yunzheng , Hu Jingjing , Wang Gege , Zeng Dexian
Published: December 2022

This paper attempts to solve the space pursuit and escape problems of a spacecraft with a fixed stay period. The artificial immune algorithm is used to solve the Nash equilibrium solution in the process of both parties’ pursuit and escape, which reduces the complexity of the bilateral optimal planning problem. According to the game process of the pursuit-and-escape, a mathematical model is established. Under the condition that both spacecraft are subjected to continuous thrust, the relative distance relationship between the two ends is defined as the objective function. To shorten the algorithm optimization time to ensure the calculation accuracy, the thrust pointing angle of the spacecraft is designed by integer coding, and the antigen-antibody affinity function is established accordingly. In this paper, the immune operator is designed and defined, which improves the searchability and convergence speed of the algorithm in three-dimensional space. The simulation example gives the optimal control strategy and the corresponding chasing trajectories of both parties, which effectively solves the problem of spacecraft chasing and escaping under a fixed time.
Research on Multi-objective Optimal Dispatch of Power System Based on Demand Response
Authors: Ma Yu , Zhong Libo , Zhao Bin
Published: December 2022

Due to the fluctuation of charge demand at the user side, the rationality of power system operation control with a single parameter setting will be reduced. Therefore, research on multi-objective optimal dispatching of power systems based on demand response is proposed. Firstly, the optimal configuration model of the power system is constructed from the perspectives of energy utilization rate and load demand at the user side. Then, the parameters in the actual executable threshold range are substituted into the model with the balance relationship between the output power of each unit as the constraint. Finally, the parameter setting result with the highest fitting degree between the system and the objective function is calculated and taken as the dispatching objective. The test results show that under the control of the dispatching method designed in this paper, the output of the power system always keeps a high fit with the actual load demand, which has high rationality.
Fault Location Method for the Double-circuit Transmission Line Based on Electromagnetic Time Reversal
Authors: Yang Yu , Liu Xinhui
Published: December 2022

The current fault location ways for the double-circuit transmission lines on the same tower do not consider the coupling relationship of transmission lines. The fault location accuracy is low in practical application. Therefore, a fault location method for the double-circuit transmission lines on the same tower basing on electromagnetic time reversal is proposed in this paper. The six-sequence component method is used to transform the transmission line’s impedance matrix to eliminate the coupling between the lines of the double-circuit transmission line on the same pole. The positive and negative phase characteristics of the transmission line are analyzed by using the fault section identification function to decide the transmission lines’ fault section. The mirror line is constructed by applying the electromagnetic time reversal to measure the distance of the fault point. The experimental results indicate that the maximum error of fault location is only 0. 01 km for a double-circuit transmission line on the same tower, which has high measurement accuracy and good practicability.
Digital twin-oriented multi-physics field simulation analysis of high-voltage SF6 circuit breakers
Authors: Chen Jing , Zhang Keqi , Liang Zhenguang , Du Zongzhan , Zhang Hengxu
Published: December 2022

Circuit breakers are important components for removing short circuits in power systems and ensuring safe operation. The operation of circuit breakers may not be predicted and thus cause accidents, so there is an urgent need to innovate means to assess the operation status of power equipment and monitor the operation status of power grids in full real time, to improve the monitoring capability of major key equipment, and to study key technologies for the digital twin of circuit breakers to support the safe and stable operation of transmission networks and the digital transformation of energy systems. This paper establishes the multi-physics field coupling calculation model of the circuit breaker opening process, completes the simulation calculation of the circuit breaker opening process, gets the distribution and change trend of parameters such as electric field, pressure, temperature, density, and airflow speed inside the interrupting chamber, and analyzes the flow characteristics inside the interrupting chamber in different opening processes. We select the characteristic parameters and provide data support for the establishment of fault diagnosis based on the digital twin of the circuit breaker.
Design and Research of Automatic Error Correction Algorithm for Electric Energy Metering Device
Authors: Li Ze , Liu Xiaoze , Guo Linlang , Sui Jiarui , Xiao Yubai
Published: December 2022

Aiming at the problems of long error correction time and poor correction effect of electric energy metering device, an automatic correction algorithm design of electric energy metering error is proposed. First, the stationary characteristics of the electric energy metering device when errors occur are extracted, and the regular interval of error correction is found. Second, in the regular interval, the average power of the quantization error of the metering device is determined, and the location of the error is found. Finally, the stability is corrected according to the error. According to the interval and error position, an automatic error correction model is constructed, which shortens the error correction time, enhances the automatic error correction of the power calculation device, and realizes the accurate correction of the power calculation error. The comparative experimental results show that the error correction time of the algorithm is short, and it has the ability of real-time error correction, which can be applied in real life.
Intelligent Detection Algorithm of Medium and Low Voltage Switch Performance Based on the Improved K-means Clustering
Authors: Fu Ming , Lu Qifu , Ran Wang , Shi Quan , Fu Dong
Published: December 2022

The performance of medium and low voltage switches will directly affect the reliability of medium and low voltage distribution networks. The medium and low voltage switch algorithm’s failure form is mainly mechanical. In order to realize its intelligent detection, a medium and low voltage switch detection algorithm based on the improved K-means clustering algorithm is proposed. Optimizing the algorithm’s clustering center selection establishes a model of the switch working state under different vibration signals and an intelligent detection algorithm for medium and low voltage switches with intelligent judgment, adaptive adjustment, and remote fault diagnosis. Experiments show that: the detection algorithm of the medium and low voltage switch controller based on the improved K-means algorithm can more accurately identify the fault of the switch algorithm according to the vibration signals, which provides a new idea for the fault identification and monitoring of the medium and low voltage switch.
Design and Implementation of an Intelligent Power Metering and Measurement System based on IoT Technology
Authors: Dong Yongle , Bai Luwei , Yu Jia , Xi Jia , Jin Zhao , Zhang Qi
Published: December 2022

Intelligent power metering and measurement systems are important for expanding the category and quantity of power metering. This paper proposes a design and implementation method of an intelligent power metering and measurement system based on IoT technology. Composed of the perception layer, the network layer, the data layer, the analysis layer, and the application layer, the overall design scheme can not only realize the intelligence, automation, and data visualization of power metering and measurement but also improves the standardization of laboratory management through a standardized metering and measurement system.
Design considerations for hardware implementation of nanoseconds time synchronization low-cost system based on precise time protocol
Authors: Zhang B. , Tao T. , Zhu J.
Published: December 2022

Precise time synchronization is the key for coordinating every node of the distributed
system to complete tasks. The widespread use of Field Programmable Gate Array (FPGA) in
distributed nodes has a positive effect on improving time synchronization accuracy. Although the
use of FPGA could significantly improve time synchronization accuracy, there is not a universal
design guideline. This work has analyzed and summarized three factors that should be considered
when building a low-cost clock synchronization system using FPGA: where the timestamp should be
generated, the calculation and correction of time offset, and how to handle Precise Time Protocol (PTP) messages. Based on these design considerations, the time synchronization system
intellectual property (IP) core was constructed. The synchronization accuracy experiments have
been performed on Zynq system-on-chip (SoC) evaluation boards of different architectures. The
experimental results demonstrated that the time synchronization system constructed in this article
could achieve nanoseconds accuracy.
Sustainable intensification of small-scale aquaculture production in Myanmar through diversification and better management practices
Authors: Wang Quanli , Rossignoli Cristiano M , Dompreh Eric Brako , Su Jie , Ali Syed Aman , Karim Manjurul , Gasparatos Alexandros
Published: December 2022

Small-scale aquaculture systems can contribute significantly to food and nutritional security, poverty alleviation, and rural development, especially in developing countries. However, the intensification of aquaculture systems often has negative environmental outcomes. The adoption of diversification practices (e.g. polyculture, pond-dike cropping (PDC)) and better management practices (BMPs) has been identified as a possible approach to intensify sustainably small-scale aquaculture production. This study assesses the sustainability outcomes of the adoption of diversification practices and BMPs in small-scale production models. We focus on Myanmar, a developing country characterized by a rapidly expanding small-scale aquaculture sector. We analyze 624 household surveys with small-scale aquaculture producers in central and northern Myanmar. We estimate the effects of diversification practices and BMPs on different sustainability outcomes, namely economic outcomes (i.e. aquaculture yield and benefit-cost ratio), environmental outcomes (i.e. nitrogen and phosphorus use efficiency), and food security outcomes (i.e. fish self-consumption and household dietary diversity) through linear mixed-effects models. Our results reveal that diversified production models (whether integrating or not integrating BMPs) could have significant positive effects on economic and food security outcomes, as well as phosphorus use efficiency, compared to ‘unimproved monoculture’. However, such production models do not seem to have any major effect on nitrogen use efficiency. The adoption of BMPs on diversified production models seems to have little (if any) added effect on any of the studied sustainability outcomes, which suggests the need to improve existing BMPs or even develop new BMPs fit for Myanmar’s context. These findings have implications about the possible contribution of diversification practices and BMPs for enabling sustainable intensification in small-scale aquaculture settings in Myanmar, and other rural developing contexts.
Disconnectivity matters: the outsized role of small ephemeral wetlands in landscape-scale nutrient retention
Authors: Cheng Frederick Y , Park Junehyeong , Kumar Mukesh , Basu Nandita B
Published: December 2022

Wetlands protect downstream waters by filtering excess nitrogen (N) generated from agricultural and urban activities. Many small ephemeral wetlands, also known as geographically isolated wetlands (GIWs), are hotspots of N retention but have received fewer legal protections due to their apparent isolation from jurisdictional waters. Here, we hypothesize that the isolation of the GIWs make them more efficient N filters, especially when considering transient hydrologic dynamics. We use a reduced complexity model with 30 years of remotely sensed monthly wetland inundation levels in 3700 GIWs across eight wetlandscapes in the US to show how consideration of transient hydrologic dynamics can increase N retention estimates by up to 130%, with greater retention magnification for the smaller wetlands. This effect is more pronounced in semi-arid systems such as the prairies in North Dakota, where transient assumptions lead to 1.8 times more retention, compared to humid landscapes like the North Carolina Pocosins where transient assumptions only lead to 1.4 times more retention. Our results highlight how GIWs have an outsized role in retaining nutrients, and this service is enhanced due to their hydrologic disconnectivity which must be protected to maintain the integrity of downstream waters.
A reduction scheme for coupled Brownian harmonic oscillators
Authors: Colangeli Matteo , Duong Manh Hong , Muntean Adrian
Published: December 2022

We propose a reduction scheme for a system constituted by two coupled harmonically-bound Brownian oscillators. We reduce the description by constructing a lower dimensional model which inherits some of the basic features of the original dynamics and is written in terms of suitable transport coefficients. The proposed procedure is twofold: while the deterministic component of the dynamics is obtained by a direct application of the invariant manifold method, the diffusion terms are determined via the fluctuation-dissipation theorem. We highlight the behavior of the coefficients up to a critical value of the coupling parameter, which marks the endpoint of the interval in which a contracted description is available. The study of the weak coupling regime is addressed and the commutativity of alternative reduction paths is also discussed.
Identification of the PLAG1 polymorphisms in Peranakan Ongole cattle population
Authors: Akmalputra M R , Sukaryo S , Yanti Y , Riyanto J , Bramastya T A , Volkandari S D , Sudrajad P , Cahyadi M
Published: December 2022

Genetic factor plays a very important role in determining of cattle performance. A gene which is reported to be controlling cattle growth and body size is pleomorphic adenoma gene 1 (PLAG1). Therefore, the goal of this study was to identify PLAG1 polymorphisms in PO cattle population. A total of 43 unproductive PO cows from the slaughterhouse at Kebumen were used in this study. Blood samples were collected individually when the cattle were slaughtered. Furthermore, DNA genome was harvested from blood samples and used as DNA template for polymerase chain reaction (PCR) targeting g.48308 C>T, g.32212 (19 bp indel) and g.45233 T>C polymorphisms. g.48308 C>T and g.45233 T>C SNPs were genotyped using PCR-restriction fragment length polymorphism (PCR-RFLP) technique and a 19 bp indel of PLAG1 was directly genotyped by observing PCR products. Both allele and genotype frequencies were calculated to test Hardy-Weinberg equilibrium (HWE) status. The results showed that g.48308 C>T SNP and 19 bp indel varied. Three genotypes of the g.48308 C>T SNP namely CC, CT and TT were found in this study and two genotypes (DD and DI) of 19 bp indel were also identified. Moreover, heterozygous CT genotype frequency of g.48308 C>T SNP was 0.51 and T allele frequency was 0.60. In term of 19 bp indel, DD genotype frequency was 0.88 and D allele frequency was 0.94. In conclusion, two polymorphisms of the PLAG1 were identified in PO cattle population.
Assessing the impacts of local intention on community-based wildlife ecotourism in Tangkahan, Gunung Leuser National Park (GLNP) and the development strategy in the post- COVID-19 outbreak
Authors: Situmorang R O P , Hussain M
Published: December 2022

Theory of Planned Behavior (TPB) has been implemented to evaluate the structure of behavioral change of the local communities in the forest and wildlife conservation program in Tangkahan, the eastern part of GLNP. This study has the purpose to reveal the determinant factors of local community behavior to support forest and wildlife conservation through ecotourism activities and to formulate a strategy to recover wildlife ecotourism in the post-COVID-19 outbreak. The study was conducted in Tangkahan through a survey method to collect the data. The data were analyzed using linear regression analysis. This study found that the determinant factors of behavioral intention are the conservation attitude and perceived behavioral control and behavioral intention significantly affects the behavior to participate in conservation activities. To improve the visiting number and the ecotourism service in Tangkahan in the post-COVID 19 outbreak, the community should transform and develop the management system from a conventional to virtual/digital method, develop and follow the COVID-19 protocol of ecotourism, re-arrange the ticket fee and the tour packages to cope with domestic visitors and improve the access to the area by constructing the roads and provision of transportation services.
Tree diversity in Medan Ahmad Yani Park
Authors: Harahap M M , Ahmad A G , Simatupang J , Ulfa M , Wirabuana P Y A P
Published: December 2022

Medan is the capital city of North Sumatra Province. It is one of the biggest cities on Sumatra Island. Big cities in Indonesia generally have problems with environmental degradation. One of the efforts to preserve the environment in urban areas is to provide public green spaces. Ahmad Yani Park is a green space dominated by trees that grow compactly and tightly in 1.3 ha of area. The research has been conducted at Ahmad Yani Park, one of the favorite places for people to gather and enjoy the freshness of clean air. Research on tree diversity in several public green spaces is needed to conduct as one of the efforts to provide biodiversity data and information in urban. This research is aimed to analyze the tree structure, composition, and diversity in Ahmad Yani Park to support sustainable development goals, especially in an urban area. The parameters of vegetation collecting by using census methods. The condition of vegetation and environment were assessed by using relative density, Shannon Wienner Diversity Index, and Evenness Index. The Ahmad Yani Park contained 240 individuals of 32 species It dominated by 62 individuals of Mahogany (S. macrophylla). The dominant vegetation is in 20 - 150 cm diameter class (59%). It is a mature phase of tree. While the juvenile and seedling stage have 26% and 15%. The Ahmad Yani Park has 2.75 score of Shannon Wiener Diversity index. It means this park is moderate diverse with a fairly stable environment.
Soil Permeability in Various Vegetation Stands at USU Campus Padang Bulan Medan
Authors: Anggraini N , Syahputra OKH
Published: December 2022

The University of Sumatera Utara (USU) campus is one of the green campuses with a reasonably high diversity of tree species. The ability of stands on the USU Campus to pass water (soil permeability) must be considered for flood prevention. Soil permeability studies in field surveys were carried out by taking soil samples—determination of soil samples for soil permeability properties based on the constant head method. Soil chemical analysis was carried out for soil organic fraction content and physical properties in soil fraction and texture. The analysis showed that saga stands (SS) showed the highest permeability among mahogany stands (MS), cape stands (CS), glodokan tiang stands (GTS), and oil palm stands (OPS).
eDNA envisaged conservation of IUCN threatened taxa of the tropical mangrove ecosystems
Authors: Kannan S , Balamurugan S , Ragavan P , Deivasigamani B , Wee A K S , Salmo S G , Basyuni M , Kajita T
Published: December 2022

eDNA sampling is a more affordable, quick, and consistent method to understand the aquatic ecosystem, especially the ocean, with freely associated DNA in water suitable for estimating diversity, composition, and behaviour. Furthermore, it helps to propose management plans to use sustainable ocean resources. The world's mangroves are currently under threat, and they also provide habitat for International Union Conservation of Nature (IUCN)-listed threatened species (e.g., Dugong, Bengal Tiger, etc.). These species are inextricably linked to the mangrove ecosystem, forming a sustenance chain that can be disrupted if lost. On the other hand, the more reliable methods to monitor threatened species are not clearly established and mostly depend on the non-standardized method, which requires practical and taxonomic expertise and limits the data-driven conservation acts. The implementation of eDNA in ocean data collection and monitoring of endangered species is still in a progressive stage and the studies on the eDNA of threatened species from mangrove ecosystems are few. Environmental DNA surveys have also mapped the distribution of endangered European eel (Anguilla anguilla) during spring and documented threatened sharks and rays across eastern Indonesia. As a hallmark, UNESCO recently launched a project to understand the richness of biodiversity. The main objective is to monitor fishes, including the IUCN red-listed species, through eDNA collected across the selected marine World Heritage sites. The recent observations ensure that eDNA might be used to monitor the IUCN-designated threatened taxa found in the tropical mangrove ecosystem. The outcomes of this eDNA technique are crucial for providing information regarding conservation priorities.
Bolt-bearing strength parallel and perpendicular to the grain of four Indonesian hardwoods
Authors: Herawati E , Hartono R , Harahap T N
Published: December 2022

Bearing strength is an important factor in determining the load-carrying capacity of a bolt-timber connection besides the bolt-bending yield strength. This study aims to determine the bolt-bearing strength parallel and perpendicular to the grain using three bolt diameters (6, 9 and 12 mm) in four hardwoods species with different specific gravities, namely terap (Artocarpus odoratissimus), durian (Durio zibethinus), mindi (Melia azedarach L) and rubberwood (Hevea brasiliensis Muell. Arg). The bolt-bearing strength was determined as described in ASTM D5764 using half-hole testing. The moisture contents ranged from 13.49–14.77% and specific gravities were 0.33–0.60. The higher the specific gravity, the higher the bearing strength. The bearing strength values parallel to the grain were higher than those perpendicular to the grain. The bearing strengths parallel to the grain were 3–18% and 2–24% lower than those based on the Indonesian National Standard (SNI) 7973 and National Design Specification (NDS) for Wood Construction 2015, respectively. In contrast, the experimental bearing strength of mindi was 8% higher than the SNI. Except for mindi, which was 22% exceed SNI and 9% above NDS, bearing strengths perpendicular to the grain were 3-32% and 14-41% less than values based on SNI and NDS, respectively.
Experimental Study of Solar Cold Energy Storage with Additional PCM and Without PCM
Authors: Calvin  , Samar  , Ambarita H
Published: December 2022

This Increased energy efficiency and comfort conditions in the building environment are increasingly needed. Therefore, phase change materials (PCM) are devoted to reducing the energy consumption of buildings. This research is an experiment with a solar-powered CES working system with dimensions of 740 mm × 410 mm × 310 mm which is used to supply cold air to a room with dimensions of 4.8 m × 3.7 m × 3.3 m. The main component of the CES cooling system consists of a combination of a thermoelectric system and an actively applied PCM. In active applications, forced convection is the dominant heat transfer mechanism between PCM and air in CES where some additional electrical devices are required. In this test, the results of CES without PCM were obtained, on the first and second days there were differences in the outlet temperature for the room and the inlet temperature for the room which were almost the same with an average of 1.43°C and 1.5°C. While CES with PCM on the first and second days with an average of 7.36°C and 3.85°C. For COP values obtained CES without PCM on the first and second days has an average value of 0.25. While the value of COP CES with PCM on the first and second days was 0.39 and 0.33.