bluuebunny/crossref_metadata_2025 huggingface dataset:
Optomechanical simulation of a time-dependent parametric oscillator
Authors: Ventura-Velázquez C , Maldonado-Villamizar F H , Jaramillo-Ávila B R , Onah F E , Rodríguez-Lara B M
Published: September 2023

We explore a finite element model of a standard one-dimensional photonic crystal cavity etched on a nanobeam designed to enhance optomechanical coupling. We theoretically demonstrate that polychromatic driving of the mechanical sidebands produces an effective Hamiltonian model showing optical self- and cross-Kerr terms and parametric interaction between the optical and mechanical modes. For the sake of providing an example, we show that bi-chromating driving, near the first and second red-sidebands, produces an analog simulation of a mechanical parametric oscillator that exhibits a squeezed vacuum ground state in the time-independent case, and in the time-dependent case, the evolution of the mechanical ground state produces displaced squeezed vacuum.
Chair-like
N66−
in AlN3 with high-energy density
Authors: Guo 郭 Shi-Tai 世泰 , Xu 徐 Zhen-Zhen 真真 , Geng 耿 Yan-Lei 延雷 , Rui 芮 Qi 琦 , Du 杜 Dian-Chen 殿臣 , Li 李 Jian-Fu 建福 , Wang 王 Xiao-Li 晓丽
Published: September 2023

The search for stable novel polynitrogen clusters has garnered significant attention in the field of energetic materials due to their potential applications as high-energy-density materials. In this study, a chair-like

N
6

6
−

ring with N–N single bonds in the AlN3 compound is theoretically predicted through first-principles calculations in conjunction with an unbiased structure searching method. The predicted AlN3 phase exhibits high kinetic and thermodynamic stability, along with a high energy density of 5.04 kJ/g relative to AlN and N2 gas. Additionally, its detonation velocity and pressure are estimated to reach 12.93 km/s and 1009.63 kbar, respectively. These values are greater than those of TNT and HMX, positioning it as a promising candidate for high-energy-density materials in the field of explosive combustion. The analysis of electronic properties and the related chemical bonding patterns indicates that the compounds are stabilized by both Coulomb interactions and covalent bonds. More importantly, the calculated formation of enthalpy indicates that the

N
6

6
−

anions within AlN3 can be synthesized by compressing AlN and N2 at a moderate pressure (46 GPa). These findings present a viable approach for synthesizing and stabilizing the all-nitrogen

N
6

6
−

anions.
Study on optimal energy dispatch of electricity-heat-cool-gas agricultural industrial Park with renewable energy
Authors: Jia Dexiang , Liu Jianye , Gao Peng , Fu Chengcheng , Liang Chen , Ma Xiping
Published: September 2023

Since the release of China’s rural revitalization strategy, rural areas have experienced rapid development, but at the same time, the imbalance between rural energy demand and infrastructure has become more prominent. In this regard, this paper considers the use of abundant renewable energy in rural areas to participate in energy generation and build an integrated energy system for agricultural parks containing electricity, heat, cold and gas loads. Based on this idea, it is necessary to establish mathematical models for various equipment in agricultural parks. Then, the maximum output and daily load curves of the agricultural park were predicted, and the TOU price was added at the same time. Finally, the objective function is to minimize the cost of energy use, and the integrated energy system of the electricity-heat-cooling-gas agricultural park using renewable energy was optimized a few days ago. In addition, through simulation examples, it has been proven that this method can increase the utilization of renewable energy, improve energy utilization efficiency, and have dual economic and environmental benefits.
Risk Analysis of Integrated Energy System Based on Security Boundary
Authors: Yu Meng , Shi Liguo , Wang Kui , Hu Yang , Xiao Fan
Published: September 2023

In the face of an increasingly diversified energy supply, integrated energy systems (IES) are playing an increasingly important role. The operational risks of complex and diversified IES have also significantly increased. This article proposes an IES risk analysis based on security boundaries. Firstly, using the multi-energy flow equilibrium equation, construct equality constraints for the safety boundary. Then, N-1 safety analysis is conducted on each critical pipeline and equipment using the predicted accident set to obtain safety boundary inequality constraints. By combining the equality and inequality constraints of the safety boundary, the system safety boundary is solved, and the IES risk indicators are determined using the relationship between the operating state points and the safety boundary. Finally, the feasibility and effectiveness of the method were verified by calculating an example of electric heating combined supply.
Detection of water leakage defects in cable insulation sheath based on terahertz time-domain spectroscopy
Authors: Luo Guofang , Song Ping , Xiong Xianghong , Chen Hongtao , Zhu Zheng , Wang Dong , Han Jingxin , Chen Xi
Published: September 2023

Water leakage of the insulation sheath can lead to a decrease in the insulation performance of the power cable, which poses a hidden danger to the power cable. Accurate detection and positioning of the water leakage area are crucial for improving power safety and stability. In response to the water leakage defect of the cable insulation sheath, this article proposes a method based on reflective terahertz time-of-flight tomography technology to measure the water leakage area of the insulation sheath. A sample of insulation sheath water leakage defect was prepared by simulating real scenarios. By analysing the terahertz reflection time-domain optical spectrum and imaging results of the sample, the location and area of the insulation sheath water leakage defect can be accurately measured, verifying the application potential of reflective terahertz time-of-flight tomography technology in detecting water seepage defects in cable insulation sheaths.
A deep learning-based method detects dust from solar PV panels through Unmanned Aerial Vehicles
Authors: Gao Yuan , Li Sujian
Published: September 2023

As the number of solar photovoltaic (PV) panels increases, dust detection on the panels becomes particularly important. In this paper, we propose a deep learning-based method that detects dust from solar PV panels through Unmanned Aerial Vehicles. The model utilizes the improved YOLOv5 method to detect PV panel dust on aerial images. The model is a lightweight model that requires fewer computing resources and time and can work in real time on a regular CPU computer. Moreover, in this paper, a prediction head is added to YOLOv5 to cope with significant changes in target scales due to unmanned aerial vehicles capturing images at different altitudes. And the model introduces new tricks to help detect dust targets in images with large coverage areas. After experimental validation, the proposed method outperforms the state-of-the-art in terms of detection accuracy, detection speed, F1 score, etc., and is more suitable for the inspection of dust on PV panels of Unmanned Aerial Vehicles.
Benefit Evaluation of Hydrogen Production System Harnessing Curtailed Wind Considering Integrated Demand Response
Authors: He Xueqian , Lu Tianguang , Liu Zhifan
Published: September 2023

With the continuous increase of wind power installed capacity in China in recent years, the problem of wind curtailment has become increasingly serious. Using curtailed wind power for hydrogen production is an effective way to reduce wind curtailment. In this paper, based on the complementary characteristics of various energies in the electric-hydrogen system, a capacity planning model of the energy system considering wind curtailment wind-to-hydrogen technology and integrated demand response is established. The proposed model utilizes a fast unit commitment technology, with the function of solving the optimum capacity of various equipment in the electrolytic hydrogen production system under different wind curtailment utilization rates and different wind power installed capacities. A case study based on Xinjiang province, which has rich wind energy resources, is conducted to obtain the optimal composition of new-built capacities of the electrolytic hydrogen production system. In light of the simulation results, the levelized cost of hydrogen is proportional to the wind power installed capacity and inversely proportional to the utilization rate of wind curtailment.
The Seepage Mechanism of Micro Remaining Oil During Cyclic Waterflooding in Low-permeability Reservoir
Authors: Zhou Wei , Yin Daiyin , Zhou Yazhou
Published: September 2023

To explore the flow mechanism of micro-remaining oil during cyclic waterflooding in low-permeability reservoir, the displacement effect of micro-remaining oil under conventional waterflooding and different rounds of cyclic waterflooding was investigated by using a micro-visual displacement experiment based on microfluidics model. The produced ratio of different types of micro remaining oil during cyclic waterflooding was quantified, and major types of micro remaining oils that can be applied effectively during cyclic waterflooding were analyzed. Moreover, the flow mechanism of micro remaining oil during cyclic waterflooding was investigated. Research results demonstrated that clustering type remaining oil and columnar type remaining oil were major types that were applied during cyclic waterflooding. After three rounds of cyclic waterflooding, clustering-type remaining oil decreased by 2.50% on average, and columnar-type remaining oil decreased by 0.81% on average. The major mechanism of cyclic waterflooding is introduced as follows: at intervals of cyclic waterflooding, clustering type remaining oil and columnar type remaining oil exchange with water in pores, throats, and spaces between big and small pores due to the fluctuation of pressure field and effect of capillary force. As a result, oil and water redistribute. Clustering-type remaining oil and columnar-type remaining oil become movable oils.
Grid-connected Inverter Control Strategy of New Energy Microgrid
Authors: Wang Lihao , Liu Jinning , Xie Nengwang
Published: September 2023

The traditional power system is composed of a synchronous generator. Because the rotor of the synchronous generator has the characteristics of the moment of inertia and damping, it can provide or absorb excess energy when the system’s frequency fluctuates. The inertia and damping of synchronous generators determine the frequency dynamic response process of the power grid, which further affects the operation, control, and protection of the whole power grid. However, because renewable energy is connected to the power grid by power electronic equipment, it does not have mechanical inertia and damping characteristics. With the increase of installed capacity of new energy, the whole power system shows low inertia characteristics. In this case, the power grid is more sensitive to interference, which may further lead to load shedding or system instability, or even system collapse. Virtual synchronous generator technology can solve this problem.
The evaluation system for intelligent recycling of cold energy from LNG vessels
Authors: Li Qionglong , Huang Fengru , Lin Xingzhi
Published: September 2023

Through the study of LNG ship cold energy intelligent recycling technology, the analysis of ship propulsion efficiency improvement and LNG cold energy residual energy intelligent recycling is carried out to explore and solve the technical problems of imperfect cold energy recycling in LNG ship cold energy intelligent recycling technology. LNG ship cold energy intelligent recycling uses the combination of dual-fuel propulsion technology and LNG cold energy residual energy recycling technology. The LNG ship cold energy intelligent recycling technology uses various methods such as the direct expansion method, Rankine cycle method of the intermediate medium, and combined method to solve most of the power supply problems on the ship.
The effect of current-carrying friction on the internal crystal phase of diamond coatings on WC-Co substrate
Authors: Cao Chenyi , Chen Naichao
Published: September 2023

A great deal of attention has been paid to friction and wear caused by current-carrying friction. In this study, diamond coatings were deposited on the cemented carbides (WC-Co) substrate by hot filament chemical vapor deposition method. Although the diamond coating possessed a higher roughness than the WC-Co substrate, it was effective at reducing the friction coefficient and improving the effectiveness of WC-Co in the current-carrying friction process. In the presence of 1 A, the diamond coating exhibited a lower friction coefficient than the WC-Co matrix, and the diamond transformed into graphite as a result. The results show that diamond-coated surfaces have a better wear condition than WC-Co.
Experimental Study of Photovoltaic-thermal Integrated Heat Pump Building Heating System
Authors: Liu Chang , Zhang Xiaosong , Zhao Shanguo
Published: September 2023

Photovoltaic-thermal (PV/T) systems and hydronic radiant floor heating systems can enhance energy efficiency and economic viability. This study investigates their integration through experimental research and designs an experiment to test their performance under typical winter conditions. The heat pump system achieves an average COP of 5.66 and an average photovoltaic power output of 107.5 W. The underfloor heating system quickly reaches and maintains 20.47°C with a water supply temperature of 50°C.
The Improvement of Calibration Method of Power Transformer Oil Chromatography Online Monitoring System
Authors: Wang Junhua , Bi Haibo , Shen Tao , Wen Xiaohan
Published: September 2023

When the semiconductor sensors are applied to the power transformer oil chromatography online monitoring system, the error of the traditional linear fitting calibration method exceeds the limit value. Therefore, this paper carries out the research of improving the calibration method of oil chromatography online monitoring system, by calibrating the online monitoring values of seven dissolved gases in reference oil samples using linear function, quadratic function and power function models, respectively. Besides, by evaluating the fitting effect, it is confirmed that the quadratic function fitting result has better correlation and lower fitting error, which is expected to be used to improve the field calibration method of the oil chromatography online monitoring system.
Risk assessment and management system of transmission line equipment above 220 kV
Authors: Zhang Hui , Yu Jiangshun , Yu Rong , Wang Di
Published: September 2023

In this paper, a transmission line operation and maintenance mode based on equipment risk and state is proposed. According to the importance and health degree, the transmission line is divided into two dimensions, which are divided into four levels. By dividing the transmission line risk, which is the consequence after failure, the importance of the transmission line is divided into critical, important, concerned, and general. At the same time, the information management of the above research is realized. It is conducive to the formulation of different levels of line management and control measures. It is also conducive to the optimization of operation and maintenance resources and can improve the efficiency of operation and maintenance.
Diagnosis of Loose Core Fault in Saturable Reactor of Thyristor Valve Based on Vibration Signal Time-Frequency Analysis and CNN
Authors: Wei Xiaoguang , Sun Tianshu , Zheng Lin , Zhang Xiaolong
Published: September 2023

The saturable reactor is one of the core components of the thyristor valve, which plays a role in suppressing current changes and balancing voltage distribution. Due to long-term operation under complex working conditions, the vibration of the reactor can cause the core to loosen. To detect faults in time, a fault diagnosis method is proposed for loose cores in saturable reactors of thyristor valves based on time-frequency analysis of vibration signals and convolutional neural networks. The two-dimensional time-frequency spectrum of the vibration signal is obtained using the short-time Fourier transform method. A convolutional neural network model structure is designed to extract time-frequency spectrum features and diagnose different levels of core looseness faults through learning and training. An experiment was carried out to collect core fault information under variable working conditions. The effectiveness of the method proposed in this paper was verified based on experimental data validation. Through comparative experiments, it was found that the proposed method is superior to existing fault diagnosis methods.
Adaptive control strategy of inertia and damping coefficients based on virtual synchronous generator
Authors: Liu Hanbo , Li Zhuze
Published: September 2023

Virtual synchronous generator (VSG) has been generally concerned in the field of new energy power generation because of their ability to imitate the operational mechanism of synchronous generator. In order to solve the problem of power and frequency fluctuation or even off-limit caused by load changes, this paper summarizes the control strategy for the stable operation of the electricity grid supported by VSG. It combines the changes of various physical quantities in the transient process. It fully uses VSG virtual inertia and damping coefficient flexible and regulable advantages and puts forward an adaptive control strategy for inertia and damping coefficient. The control strategy can efficiently suppress the fluctuation of VSG output power and frequency in dynamic processes. It can cut down the transient adjustment time significantly and promote the stability of the system. The correctness and effectiveness of the proposed control strategy are verified by simulation experiment results.
Hybrid Modulation Strategy for Common-mode Voltage Suppression in Three-level Inverters
Authors: Dong Shiao , Li Yuxin , Dai Wen
Published: September 2023

A hybrid modulation strategy is proposed to suppress the common-mode voltage (V
com) of the three-level PWM inverter on the strength of the SVPWM modulation algorithm (space vector pulse width modulation) for V
com generated during the run of the three-level inverter. The three-level space vector is classified as two different modulation areas by modulation ratios. In the low modulation ratio region, according to the nearest three vectors principle, the spatial voltage vector is obtained by combining the small vector with the medium vector, which suppresses V
com and ensures that only one bridge arm is switched for any voltage vector. In the high modulation ratio region, the vector with large common-mode voltage is discarded, and the zero-vector, medium-vector, and large-vector are selected to synthesize the space voltage vector, which suppresses V
com and ensures the good output current waveform of the PWM inverter. From the simulation results, we can see the hybrid modulation strategy of dividing the region by modulation ratio reduces the magnitude of V
com to 1/6 of the dc bus voltage, and at the same time, a good current waveform is obtained at the output of the three-level inverter.
Hilbert Fractal Antenna for Abnormal Discharge Detection of Transmission Equipment
Authors: Qu Yongjie , Wu Yang , Hei Guoyu , Teng Da , Yan Xinli
Published: September 2023

The safe and stable operation of the power system can ensure people’s basic electricity needs. It also plays an important role in energy security and economic development and can contribute to environmental protection and energy conservation. If there are problems in the power system, it will not only affect people’s normal life and work but also lead to power loss or waste, thereby exacerbating the impact on the environment. With the long-term operation of transmission equipment, insulation devices are aging, leading to frequent abnormal discharges and affecting the safety and stability of the power system. Therefore, timely detection and troubleshooting are necessary. When abnormal discharge occurs in transmission equipment, it will radiate radio frequency (RF) electromagnetic waves, which are mainly concentrated between 200 MHz and 300 MHz. RF antennas that can capture signals in this frequency band can be used for detection to determine whether abnormal discharge has occurred. This article uses the Hilbert fractal antenna as the research object to analyze the impact of different orders on antenna performance and optimizes the different feeding point positions of the antenna. Finally, the antenna structure for detecting abnormal discharge is obtained. By making an actual antenna and conducting experimental analysis, the discharge detection function of the designed antenna is verified.
Parasitic Parameter Prediction for Planar Transformers Based on Neural Network
Authors: Tan Chang , Hong Jianxun , Wu Zihao , Huang Qiuyuan , Wang Cheng
Published: September 2023

Parasitic parameters such as leakage inductance and distributed capacitance of planar transformers have a direct impact on the performance and efficiency of transformers. Traditional methods for parasitic parameter prediction are commonly based on empirical formulas or simulation software, but they have problems of high computational complexity, time-consuming and low accuracy. In this paper, a method for predicting parasitic parameters of planar transformers based on a multilayer perceptron (MLP) under a specific winding structure is proposed, which can improve the efficiency of transformer design. The experiments demonstrate that the model can effectively predict the leakage inductance, distributed capacitance, and AC loss of planar transformers.
The grid simulation device for photovoltaic power generation
Authors: Qian Huifa
Published: September 2023

Solar photovoltaic power generation is the solar radiant energy directly into electricity method, namely the sun radiant energy by solar cells is converted into electrical energy, again through energy storage, control, and transformation, and into people’s dc or ac power that can be used directly. The so-called grid-connected network is simply said to be realized by using the principle of simultaneous operation of voltage, phase, phase sequence, and frequency. The simulation device of its inverter grid-connected is designed, the scheme of simulating grid-connected is given, the drive control system and filter system are designed, and the implementation scheme of the drive control system is introduced in detail. The design and parameter selection of the main circuit and the filter system are given in detail. The hardware and software implementation scheme and circuit structure of the system are given based on DSP. The entire system can meet the requirements of microgrid simulation operation.
Optimization and Performance Improvement of Automatic Generation Control (AGC) for 330 MW Subcritical Thermal Power Unit
Authors: Li Yuanyuan , Hua Zhi , Li Jun , Liu Enren , Gao Song
Published: September 2023

With the continuous assessment of the “Two Detailed Rules”, various power generation groups are paying increasing attention to AGC. A 350 MW subcritical unit has been in a poor performance state under AGC-R mode since the 2022 heating season, with a K1 value below 1.2 and a K2 value not reaching the qualified value. It is facing the cancellation of the qualification for AGC-R mode. In the face of the problem with the unit, this article analyzes three reasons. Firstly, the speed setting exceeds the requirements, but the actual unit action does not meet the standards. There is a deviation in power and a significant deterioration in control quality during the turning point and continuous climbing of AGC instructions. Based on the above analysis, this article proposes three renovation plans to optimize the instructions through nonlinear correction functions and achieve the elimination of instruction deviations. It calculates and judges the difference between the corrected AGC load command value and the actual power value of the unit. It calculates the deviation and sends the deviation to a saturated nonlinear link to generate the feedforward of the main turbine control, improving the output of the main turbine control. By setting a variable integral function, the main control output of the boiler is improved. After this technical transformation, the AGC performance of the unit has been significantly improved.
Flexible On-load Voltage Regulating Transformer by Floating Capacitor Three-level AC/AC Converter
Authors: Wang Ruiqiong , Ke Shengjin , Jiang Xuhui , Zhang Xi , Zhu Yuanhao , Xie Kaiji , Sun Longfei , Yin Jingyuan
Published: September 2023

The flexible on-load transformer can be adapted to different application scenarios by adding different power electronic converter structures through the use of existing transformers. In this paper, a flexible on-load regulator transformer structure based on a floating capacitor multi-level AC/AC converter is proposed, which can compensate the input voltage on the primary side of the transformer in the same direction or the opposite direction, combine with the existing on-load tap-changer, and also achieve fast stepless voltage regulation. Finally, the effectiveness of the proposed new topology is verified by simulation and experiment.
Fuzzy Control Strategy of Tunnel Lighting Based on Input Parameter Optimization
Authors: Li Lanjin , Wang Guo
Published: September 2023

The mismatch between illumination and traffic safety brightness in tunnels leads to much-wasted lighting energy and safety problems. Effective control of tunnel lighting can be achieved by lighting on demand and reducing lighting energy consumption. This paper uses the curve fitting and linear interpolation methods to optimize the luminance reduction factor K proposed in the Highway Tunnel Lighting Rules. It constructs a multi-zone division of traffic speed, traffic flow, and brightness outside the tunnel to obtain the K value under actual road conditions and to establish a fuzzy controller for dimming control. The simulation demonstrates that the proposed strategy can save about 37.38% of tunnel lighting compared to the graded lighting control strategy.
Wireless Charging System with Three Arc-Transmitting Coils for Autonomous Underwater Vehicle
Authors: Cai Bin , Yu Menghong , Lu Haozhou
Published: September 2023

To enhance the misalignment tolerance of the coupling device of the autonomous underwater vehicle wireless charging system, this paper proposes a magnetic coupling device with strong misalignment tolerance. Through the Ansys Maxwell finite element analysis software, it is concluded that, under the dislocation state of the proposed magnetic coupling device, the magnetic field is mainly distributed near the shell wall of the autonomous underwater vehicle. The coupling coefficient change range under the rolling dislocation state is 0.35~0.83, the axial dislocation coupling coefficient fluctuation range is 0.79~0.83, and the radial dislocation coupling coefficient variation range is 0.48~0.83. We design and calculate the compensation network in a wireless charging system and obtain the calculation method of the compensation network. A prototype of that wireless charging system containing arc-emitting coils applied to the AUV has been made, which transfers 48 W power with an efficiency of 87.3%.
Optimal Dispatching of Distributed Generation Cluster Systems Considering Multiply Optimization Objectives
Authors: Feng Ying , Zhu Jian , Kong Bojun , Wang Shengbo
Published: September 2023

In the trend of increasing energy shortages and environmental pollution, integrating clean micro sources as cluster systems has become the mainstream trend in the DG cluster system research field. In an effort to ensure the economy and environmental friendliness of Distributed Generation (DG) cluster systems, a multi-objective optimization scheduling model is established to minimize the operating and environmental costs of DG cluster systems. Based on a multi-objective particle swarm optimization algorithm, this paper conducts a study on the capacity optimal configuration of wind turbines, photovoltaic generators, and energy storage devices. The model proposed in this paper is applied to analyse a DG cluster system in a rural area dominated by agriculture. The results show that the proposed model has a significant effect in reducing the operating and environmental costs of the DG cluster system.
Analysis and Grid Performance Evaluation of Offshore Wind Power Direct Current Transmission System based on VSC and DRU
Authors: Li Haibo , Liu Yushan , Aisikaer  , Lv Hongmei , Wang Yinmei , Wang Xueyan
Published: September 2023

Offshore wind farms, with their abundant and stable wind energy resources, have become the main trend of wind power development in the future. Based on voltage source converter (VSC) transmission technology and diode rectifier unit (DRU) as the hot spot technologies for offshore wind power delivery, they have different characteristics in practical applications. This paper compares the engineering economy of VSC and DRU from the topology of offshore wind power delivery. It combines the key technologies of DRU control. It proposes grid connection performance testing indicators. It builds VSC and DRU offshore wind power DC delivery models, respectively, based on PSCAD/EMTDC simulation software to compare and analyze the operation effects after their faults. The research results show that DRU has a faster response and better support ability than the VSC scheme.
Nonlinear buckling analysis of cat-head transmission tower under strong wind load
Authors: Jiang Heng , Zhu Rui , Wang Zhenguo
Published: September 2023

Based on ANSYS APDL finite element analysis software and B-R criterion combined with displacement equality criterion, the dynamic stability of the cat-head transmission tower is analyzed. In this paper, the static characteristics of the cat-head transmission tower are analyzed first, and the wind load is gradually increased according to the wind speed gradient of 5 m/s. The results show that the cat-head transmission tower cannot be normally served under the wind speed of 45 m/s. In order to analyze the specific instability wind speed of the transmission tower in detail, the nonlinear buckling analysis is used to analyze the cat-head transmission tower. The nonlinear buckling analysis results of the cat-head transmission tower are as follows: the wind speed of instability is V10=43.65 m/s. Therefore, the influence of wind load fluctuation on the dynamic stability of the transmission tower should not be ignored, and the influence of fluctuating wind should be considered in the design of the transmission tower.
Ionospheric prediction algorithm and its application in low-latitude regions based on the physically constrained polynomial model
Authors: Huang Weizhao , Chen Yuan , Xin Tuo , Xie Huanhuan , Huang Linchao , Ji Liya
Published: September 2023

With sufficient consideration of the ionospheric variation subject to solar activity and geomagnetic variation, a high-precision ionospheric prediction model, i.e., a physically constrained polynomial model (PCPM), was constructed by adding the Kp index, Dst index, F10.7P, R sunspot number, and other geomagnetic and solar variation indexes. Based on the data of Continuously Operating Reference System (CORS) stations in China Southern Power Grid, the ionospheric prediction results of PCPM were compared with the widely used and well-recognized seasonal enhanced product autoregressive integrated moving average (Arima) model without additional physical parameters. The prediction performance of the two models in different prediction time spans and the influence of model products on Precise Point Positioning-Real Time Kinematic (PPP-RTK) was emphatically analyzed. The experimental results demonstrated that the accuracy of PCPM is better than that of the seasonal Arima model on the first day of prediction, the prediction accuracy of the two models decreases with the increase of prediction time span, and the lowest accuracy of the seasonal Arima model on the first three days is 1.5 TECU. The Arima model outperforms the PCPM over a long-time span; in light of the overall accuracy, PCPM is more available in five southern provinces, outperforming the seasonal Arima model; the results of the PPP-RTK experiment showed that the PCPM could not only improve the velocity of ambiguity fixing but also improve the positioning accuracy after ambiguity fixing. Compared with the seasonal Arima model, the velocity of ambiguity fixing is increased by 16.7%, and the positioning accuracy after ambiguity fixing is improved by 61.0% in the E direction and 6.9% in the U direction compared with the results without ionospheric constraints.
Analysis of Automatic and Fast Switching Scheme for Closed Loop Point of the Power Grid in the Baotou Area
Authors: Mu Ren , Guan Kai , Zhan Xueniu , Zhang Yi , Song Haitao
Published: September 2023

The influence of the access of different power source unloop points on the power grid is summarized. Transient simulation analysis is carried out on voltage fluctuation, power flow fluctuation, short-circuit current, and voltage unbalance degree after the power grid is closed. The feasibility of the fast-switching device configured on the distribution network side is demonstrated, and the possible problems of the fast-switching device in the operation process and their influence on the power grid are analyzed. Ultimately, it lays a theoretical foundation for researching automatic and fast-switching devices under specific operating modes.
Cross-Wavelet Analysis on Radiation Emitted by the plume of a small-size Solid Rocket Motor
Authors: Martellini Edoardo , Troiani Guido , Pagliaroli Tiziano
Published: September 2023

This work follow a previous activity that developed a non-intrusive measurements technique for particles velocity ejected from a solid rocket motor based on wavelet analysis. The aim was to detect the particles passage and calculate the axial velocity through an auto-conditioned cross-correlation algorithm. In this study, a wavelet based processing techniques are applied and an innovative methodology based on the cross-wavelet analysis is presented. The objective is to detect the impulsive events associated to the particles crossing the field of view of the acquisition system. Starting from two synthetic signals characterized by a Gaussian peak, each one located at a different time instants, cross-wavelet analysis identify an increase of energy for all the correlation time producing a structure in the time scale comparable to the delay between the peaks. On the experimental database a continuous wavelet transform and a local intermittency measurement are performed to localize high energy events with randomic occurrence in the time series that are associated to the passage of allumina particles. Cross-wavelet analysis present several correlation structures localized in time between the events highlighted by the LIM maps. Results are very promising and could be a very interesting bases for deeper analysis based on wavelet, LIM and cross-wavelet.
Droplets size characterization for cold water clouds by means of Generalised Scattering Imaging
Authors: Ceglia G , De Gregorio F
Published: September 2023

This paper describes an experimental investigation carried out at the Italian Aerospace Research Centre (CIRA) laboratory for the application of the Generalized Scattering Imaging (GSI) technique. The droplets were generated by a monodisperse droplet generator and a multi-disperse conical nozzle. This latter is currently used for making the artificial cloud in the CIRA Icing Wind Tunnel (IWT). The measurements are devoted to assessing the application of GSI for the characterization of the cold cloud of CIRA-IWT. The experiments were conducted considering two camera models and demanding technical solutions for the illumination and layout constraints faced for the future implementation of GSI in IWT. To reduce into a linear pattern the enlarged defocused interference fringes, it is found that the optimal aperture of the slit is 5 mm. For the monodisperse droplet distribution, the results show discrepancies between the predicted and the measured diameters regardless of the sharp distribution of the occurrences of the droplet diameters. However, the dispersion found for the droplets generated by the conical nozzle exhibits the expected large variability. This effect is more emphasized when the imaged region is discretized in sub-windows, the number of droplets in each dramatically decreases, however compromising the results of the statistics. Different camera models and imaging configurations led to a variety of measurements at different spatial resolutions.
Metrological issues in the use of mobile mapping systems for planning emergency response
Authors: Chiominto L , D’Emilia G , Gaspari A , Natale E
Published: September 2023

The paper intends to investigate some metrological aspects concerning data acquisition in determining the slope of escape routes in existing building, in order to provide this information as input for subsequent evacuation planning algorithms. The analysis is based on the point cloud acquired by a laser scanner and deepens different aspect that can impact on the slope uncertainty, linked to the choice of the algorithm for determining the slope itself, the values of the different parameters to set, and the different possible study strategies of the floor surface. The analysis will be conducted by using a commercial software, with the aim, in a future work, of investigating other kinds of algorithms and approaches, but also non-commercial data processing methods that may provide further useful information.
Sensitivity analysis of FBG sensors for detection of fast temperature changes
Authors: Aimasso Alessandro , Vedova Matteo Davide Lorenzo Dalla , Maggiore Paolo
Published: September 2023

In the last few decades, the use of optical fiber is becoming more widespread for communication technologies and sensor applications. In this sense, considering the physical characteristics of the fiber, there are many possibilities for its use in various engineering sectors, not least in the aerospace one. Indeed, using optical fibers to replace traditional electronic devices can provide significant advantages, such as using an extremely lightweight and minimally invasive technology. FBG (Fiber Bragg Grating) sensors are ones of the most widely used instruments for this purpose, and they allow the detection of different physical parameters, including temperature. The aim of the present work is to analyze the performances of FBGs, in particular by evaluating their ability to read short-term thermal transients and comparing it with that of a conventional thermal probe (PT100). More specifically, two optical fibers were used: the first with the FBG sensor area covered by the external coating and the second without this outer layer. All instrumentation was placed in a climatic chamber and subjected to different thermal cycles. Furthermore, the fiber sections with FBGs were not placed directly in contact with the plate on which they were installed. This made it possible to put optical sensors indications that were as independent as possible from the materials on which they were mounted. Tests have shown that optical sensors have an extremely high sensitivity and a much shorter reaction time than the PT100 probe. Data collected by this work allow strategic use of FBG for thermal monitoring using a minimally invasive and extremely accurate technology.
A multivariate statistical analysis of the noise emitted by an installed propeller
Authors: Falsi M. , Zaman I. , Meloni S. , Camussi R. , Zang B. , Azarpeyvand M.
Published: September 2023

Novel-aircraft concepts consider the possibility of placing the propulsor very close to the fuselage to ingest the incoming airframe boundary layer. In this configuration, the engine takes the inflow at a reduced velocity, consuming less fuel in the combustion process. However, this induces a series of noise consequences that alter tonal and broadband noise components. The present work reports an experimental investigation to analyse the sound emitted by a propeller ingesting a turbulent boundary layer. Experiments have been performed in the anechoic wind tunnel at the University of Bristol and the set-up consisted of a two-bladed propeller close to a tangential flat plate to simulate the installed effects. A tripping device was placed 1 m upstream of the propeller and was used to generate a turbulent boundary layer at the propeller location. The wind tunnel velocity was fixed at 33 m/s keeping the advance ratio at J = 0.65. Far-field noise has been acquired using a microphone array positioned parallel to the plate, directly overhead of the propeller. The data were analysed in the frequency domain, providing a characterisation of spectral quantities. Furthermore, wavelet analysis was performed to investigate the time evolution of the identified pressure features. Results show evident haystacking humps close to higher BPF harmonics, due to the ingestion of the boundary layer. Moreover, the wavelet analysis revealed the intermittent nature of the haystacking humps, clearly visible at higher BPF harmonics with low-frequency energy content.
Search for charged lepton flavor violation in J/ψ decays at BESIII
Authors: Li Jingshu , You Zhengyun
Published: September 2023

The observation of any charged lepton flavor violation (CLFV) process would be a clear signal of new physics beyond the Standard Model. Various decay modes, including lepton (μ, τ) decays, pseudoscalar meson (K,π) decays, vector meson (ϕ, J/ψ, Υ) decays, and Higgs decays, have been explored to detect CLFV. Focusing on the search for CLFV at the τ-charm region, the results of the search for J/ψ → eτ/eμ using the 10 billion J/ψ events collected by the BESIII experiment are presented. The upper limits (ULs) at the 90% confidence level are ℬ(J/ψ → e
±
τ
∓) < 7.5 × 10-8 and ℬ(J/ψ → e
±
μ
∓) < 4.5 × 10-9, respectively. Improving the previously published limits by two orders of magnitudes, the results are the most stringent CLFV searches in heavy quarkonium system.
California margin temperatures modulate regional circulation and extreme summer precipitation in the desert Southwest
Authors: Bhattacharya Tripti , Feng Ran , Maupin Christopher R , Coats Sloan , Brennan Peter R , Carter Elizabeth
Published: September 2023

In August 2022, Death Valley, the driest place in North America, experienced record flooding from summertime rainfall associated with the North American monsoon (NAM). Given the socioeconomic cost of these type of events, there is a dire need to understand their drivers and future statistics. Existing theory predicts that increases in the intensity of precipitation is a robust response to anthropogenic warming. Paleoclimatic evidence suggests that northeast Pacific (NEP) sea surface temperature (SST) variability could further intensify summertime NAM rainfall over the desert southwest. Drawing on this paleoclimatic evidence, we use historical observations and reanalyzes to test the hypothesis that warm SSTs on the southern California margin are linked to more frequent extreme precipitation events in the NAM domain. We find that summers with above-average coastal SSTs are more favorable to moist convection in the northern edge of the NAM domain (southern California, Arizona, New Mexico, and the southern Great Basin). This is because warmer SSTs drive circulation changes that increase moisture flux into the desert southwest, driving more frequent precipitation extremes and increases in seasonal rainfall totals. These results, which are robust across observational products, establish a linkage between marine and terrestrial extremes, since summers with anomalously warm SSTs on the California margin have been linked to seasonal or multi-year NEP marine heatwaves. However, current generation earth system models (ESMs) struggle to reproduce the observed relationship between coastal SSTs and NAM precipitation. Across models, there is a strong negative relationship between the magnitude of an ESM’s warm SST bias on the California margin and its skill at reproducing the correlation with desert southwest rainfall. Given persistent NEP SST biases in ESMs, our results suggest that efforts to improve representation of climatological SSTs are crucial for accurately predicting future changes in hydroclimate extremes in the desert southwest.
Accurate dynamics from self-consistent memory in stochastic chemical reactions with small copy numbers
Authors: Harsh Moshir , Sollich Peter
Published: September 2023

We present a method that captures the fluctuations beyond mean field in chemical reactions in the regime of small copy numbers and hence large fluctuations, using self-consistently determined memory: by integrating information from the past we can systematically improve our approximation for the dynamics of chemical reactions. This memory emerges from a perturbative treatment of the effective action of the Doi-Peliti field theory for chemical reactions. By dressing only the response functions and by the self-consistent replacement of bare responses by the dressed ones, we show how a very small class of diagrams contributes to this expansion, with clear physical interpretations. From these diagrams, a large sub-class can be further resummed to infinite order, resulting in a method that is stable even for large values of the expansion parameter or equivalently large reaction rates. We demonstrate this method and its accuracy on single and multi-species binary reactions across a range of reaction constant values.
Different perspective on biodiversity: high conservation value or high cultivation value
Authors: Soedomo S , Santoso N
Published: September 2023

High biodiversity tends to lead the public, including experts, towards one definite direction, namely conservation. Then came the idea of the need to identify areas with high biodiversity for conservation. Furthermore, any area with high biodiversity must be conserved and should not be cleared for cultivation. However, after being protected, how to use high biodiversity for public welfare is not done immediately, even never. In fact, many conservation areas have been damaged, even some conservation areas have undergone a total change in function. Using the same logic, cultivation is directed to areas with low biodiversity, unless the area has been designated as a conservation area. Once designated as a conservation area, whatever the circumstances, the status of the conservation area must be maintained as a conservation area. Based on the literature survey and its synthesis, this paper discusses the weaknesses and dangers of such a logic line. We need to understand biodiversity from different perspectives with different implications as well. High biodiversity does not necessarily lead merely to conservation, but can also lead to cultivation. Conversely, low biodiversity does not always have to lead to cultivation, but in certain cases it must be directed to conservation.