bluuebunny/crossref_metadata_2025 huggingface dataset:
International comparison CCQM-K150: particle number concentration (100 to 20 000 cm-3) and particle charge concentration (0.15 to 3 fC cm-3)
Authors: Brown Andrew S , Quincey Paul , Ebert Volker , Nowak Andreas , Tompkins Jordan T , Hessey Isabel , Ciupek Krzysztof , Schaefer Carlo , Werhahn Olav , Vasilatou Konstantina , Lüönd Felix , Macé Tatiana , Gaie-Levrel François , Bregonzio-Rozier Lola , Oganyan Narine , Belenkii Dmitrii , Sakurai Hiromu , Murashima Yoshiko , Liu Junjie , Jung Jinsang , Seeger Stefan
Published: May 2023

Main text

This report presents the results of CCQM-K150, a key comparison between nine National Measurement Institutes (NMIs) which tested the capability of the NMIs to measure particle number concentration (in the range of 100 to 20 000 cm-3) using condensation particle counters (CPCs), and particle charge concentration (in the range of 0.15 to 3 fC cm-3) using aerosol electrometers (AEs).

Measurements of aerosol particle number concentration are needed to demonstrate compliance to vehicle emission legislation and are becoming increasingly important in other areas such as ambient air and workplace monitoring. The measurements are typically carried out using condensation particle counters, which are calibrated using either reference CPCs or reference AEs.

An analogous report is available for the CCQM-P189 comparison. CCQM-P189 was identical to and used the same experimental data as CCQM-K150 with one exception: data from TROPOS, which is not an NMI or Designated Institute (DI), were only included in CCQM-P189.

CCQM-K150 was an amount-of-substance Track C comparison.

To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.

The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
EBWeyl: a code to invariantly characterize numerical spacetimes
Authors: Munoz Robyn L , Bruni Marco
Published: May 2023

Relativistic cosmology can be formulated covariantly, but in dealing with numerical relativity simulations a gauge choice is necessary. Although observables should be gauge-invariant, simulations do not necessarily focus on their computations, while it is useful to extract results invariantly. To this end, in order to invariantly characterize spacetimes resulting from cosmological simulations, we present two different methodologies to compute the electric and magnetic parts of the Weyl tensor,

E

α
β

and

B

α
β

, from which we construct scalar invariants and the Weyl scalars. The first method is geometrical, computing these tensors in full from the metric, and the second uses the 3 + 1 slicing formulation. We developed a code for each method and tested them on five analytic metrics, for which we derived

E

α
β

and

B

α
β

and the various scalars constructed from them with computer algebra software. We find excellent agreement between the analytic and numerical results. The slicing code outperforms the geometrical code for computational convenience and accuracy; on this basis we make it publicly available in github with the name EBWeyl. We emphasize that this post-processing code is applicable to any numerical spacetime in any gauge.
Identifying native point defect configurations in α-alumina
Authors: Kononov Alina , Lee Cheng-Wei , Shapera Ethan P , Schleife André
Published: May 2023

Intimately intertwined atomic and electronic structures of point defects govern diffusion-limited corrosion and underpin the operation of optoelectronic devices. For some materials, complex energy landscapes containing metastable defect configurations challenge first-principles modeling efforts. Here, we thoroughly reevaluate native point defect geometries for the illustrative case of α-Al2O3 by comparing three methods for sampling candidate geometries in density functional theory calculations: displacing atoms near a naively placed defect, initializing interstitials at high-symmetry points of a Voronoi decomposition, and Bayesian optimization. We find symmetry-breaking distortions for oxygen vacancies in some charge states, and we identify several distinct oxygen split-interstitial geometries that help explain literature discrepancies involving this defect. We also report a surprising and, to our knowledge, previously unknown trigonal geometry favored by aluminum interstitials in some charge states. These new configurations may have transformative impacts on our understanding of defect migration pathways in aluminum-oxide scales protecting metal alloys from corrosion. Overall, the Voronoi scheme appears most effective for sampling candidate interstitial sites because it always succeeded in finding the lowest-energy geometry identified in this study, although no approach found every metastable configuration. Finally, we show that the position of defect levels within the band gap can depend strongly on the defect geometry, underscoring the need to conduct careful searches for ground-state geometries in defect calculations.
Online measurement system of slab front-end bending in hot rough rolling based on line structured light vision
Authors: Yan Shuzong , Xu Dong , He Wanzhang , Yan Huiqing , Zhou Jinhang , Jin Guangyin , Wu Tongqing , Liu Lihui , Yu Haijun , Wang Xiaochen , Yang Quan
Published: May 2023

Front-end bending is one of the most significant defects of slabs in hot rough rolling. To address the lack of effective methods to detect slab front-end bending in hot rolling, a measurement system based on line structured light vision is proposed in this paper. Line structured light lasers and area-scan cameras are arranged on the supports on both the exit and entrance of a roughing mill. First, the calibration of the measurement system is completed by camera calibration and the random sampling consistency algorithm. Second, multiple regions of interest gray thresholds and the Steger algorithm are used to realize laser centerline extraction on the surface of a large-scale and high-temperature slab. Last, the actual value of the slab front-end bending is obtained and calculated through coordinate transformation. The proposed measurement system can detect slab front-end bending in real time and the relative mean deviation is 0.93%.
New insight into the dynamics of non-Newtonian Powell-Eyring fluid conveying tiny particles on Riga plate with suction and injection
Authors: Shah Syed Asif Ali , Alanazi Meznah M , Malik Muhammad Fawad , Abbas Zafar
Published: May 2023

The purpose of the current work is to determine how a magnetic field, nonlinear thermal radiation, a heat source or sink, a Soret, and activation energy affect bio-convective nanofluid flow across a Riga plate in terms of heat transfer qualities. The major goal of this investigation is to enhance the heat transfer rate. The flow problem is demonstrated in the form of a collection of PDEs. Since the generated governing differential equations are nonlinear, we use a suitable similarity transformation to change them from partial to ODEs. The bvp4c package in MATLAB is used to numerically solve the streamlined mathematical framework. The impacts of numerous parameters on temperature, velocity, concentration, and motile microorganisms profiles are examined through graphs. Whereas, skin friction and Nusselt number are illustrated using tables. As the magnetic parameter values are raised, the velocity profile is seen to decrease and the temperature curve exhibits the opposite tendency. Additionally, the heat transfer rate expands as the nonlinear radiation heat factor is enhanced. Moreover, the outcomes in this investigation are more consistent and precise than in earlier ones.
Metastable argon atom kinetics in a low-pressure capacitively coupled radio frequency discharge
Authors: Donkó Zoltán , Hartmann Peter , Korolov Ihor , Schulenberg David , Rohr Stefan , Rauf Shahid , Schulze Julian
Published: May 2023

The kinetics of excited atoms in a low-pressure argon capacitively coupled plasma source are investigated by an extended particle-in-cell/Monte Carlo Collisions simulation code coupled with a diffusion-reaction-radiation code which considers a large number of excited states of Ar atoms. The spatial density distribution of Ar atoms in the 1s5 state within the electrode gap and the gas temperature are also determined experimentally using tunable diode laser absorption spectroscopy. Processes involving the excited states, especially the four lower-lying 1s states are found to have significant effects on the ionization balance of the discharge. The level of agreement achieved between the computational and experimental results indicates that the discharge model is reasonably accurate and the computations based on this model allow the identification of the populating and de-populating processes of the excited states.
Brewster angle-cavity ringdown spectroscopy for low temperature plasma measurements in multiphases
Authors: Cohen Rongrong W , Wang Chuji
Published: May 2023

We report on the development of a Brewster angle-cavity ringdown spectroscopy (BA-CRDS) system for low temperature plasma diagnostics. The system can measure gas species in solutions, with a detection limit (minimum detectable absorbance) of 9.1 × 10−5, which is equivalent to a detection limit of 0.04 parts per billion for measuring OH radicals in water at 308 nm. With higher reflectivity ringdown mirrors and improved design of a Brewster angle cell, the detection limit can potentially be up to 10−6 or lower. In this exploratory study, the absorption cross sections of HgBr2 and H2O2 in the aqueous phase at 256 nm are measured to be (1.8 ± 0.1) × 10−18 cm2 and (5.2 ± 0.5) × 10−20 cm2, respectively. Furthermore, temporal profiles of absorbance from distilled water, HgBr2, and H2O2 solutions when interacting with a helium atmospheric plasma jet are individually characterized at different plasma powers, gas flow rates, and/or solute concentrations. The observed linear temporal profiles of absorbance from the plasma-interacted water suggest formation of H2O2 from plasma-generated OH radicals, while the nonlinear temporal profiles from the plasma-treated HgBr2 solutions reveal possible removal of HgBr2 by OH radicals. Our results demonstrate that the new BA-CRDS system is a powerful tool for quantification of reactive plasma species in multiphases or other complex settings.
Nambu-Goto dynamics of field theory cosmic string loops
Authors: Blanco-Pillado Jose J. , Jiménez-Aguilar Daniel , Lizarraga Joanes , Lopez-Eiguren Asier , Olum Ken D. , Urio Ander , Urrestilla Jon
Published: May 2023

We perform a detailed comparison of the dynamics of cosmic string
loops obtained in cosmological field theory simulations with their expected motion according to the
Nambu-Goto action. We demonstrate that these loops follow the
trajectories predicted within the NG effective theory except in regions
of high curvature where energy is emitted from the loop in the form of massive
radiation. This energy loss continues for all the loops
studied in this simulation until they self-intersect or become small enough that they annihilate
and disappear well before they complete a single oscillation. We comment on the relevance of this
investigation to the interpretation of the results from cosmological field theory simulations
as well as their extrapolation to a cosmological context.
Bio-inspired environmental adaptability of swarm active matter
Authors: Jin Yangkai , Wang Gao , Yuan Daming , Wang Peilong , Wang Jing , Chen Huaicheng , Liu Liyu , Zan Xingjie
Published: May 2023

How biologically active matters survive adaptively in complex and changeable environments is a common concern of scientists. Genetics, evolution and natural selection are vital factors in the process of biological evolution and are also the key to survival in harsh environments. However, it is challenging to intuitively and accurately reproduce such long-term adaptive survival processes in the laboratory. Although simulation experiments are intuitive and efficient, they lack fidelity. Therefore, we propose to use swarm robots to study the adaptive process of active matter swarms in complex and changeable environments. Based on a self-built virtual environmental platform and a robot swarm that can interact with the environment, we introduce the concept of genes into the robot system, giving each robot unique digital genes, and design robot breeding methods and rules for gene mutations. Our previous work [Proc. Natl. Acad. Sci. USA
119 e2120019119 (2022)] has demonstrated the effectiveness of this system. In this work, by analyzing the relationship between the genetic traits of the population and the characteristics of environmental resources, and comparing different experimental conditions, we verified in both robot experiments and corresponding simulation experiments that agents with genetic inheritance can survive for a long time under the action of natural selection in periodically changing environments. We also confirmed that in the robot system, both breeding and mutation are essential factors. These findings can help answer the practical scientific question of how individuals and swarms can successfully adapt to complex, dynamic, and unpredictable actual environments.
Ferroelectricity of hafnium oxide-based materials: Current status and future prospects from physical mechanisms to device applications
Authors: Yang Wanwang , Yu Chenxi , Li Haolin , Fan Mengqi , Song Xujin , Ma Haili , Zhou Zheng , Chang Pengying , Huang Peng , Liu Fei , Liu Xiaoyan , Kang Jinfeng
Published: May 2023

The finding of the robust ferroelectricity in HfO2-based thin films is fantastic from the view point of both the fundamentals and the applications. In this review article, the current research status of the future prospects for the ferroelectric HfO2-based thin films and devices are presented from fundamentals to applications. The related issues are discussed, which include: 1) The ferroelectric characteristics observed in HfO2-based films and devices associated with the factors of dopant, strain, interface, thickness, defect, fabrication condition, and more; 2) physical understanding on the observed ferroelectric behaviors by the density functional theory (DFT)-based theory calculations; 3) the characterizations of microscopic and macroscopic features by transmission electron microscopes-based and electrical properties-based techniques; 4) modeling and simulations, 5) the performance optimizations, and 6) the applications of some ferroelectric-based devices such as ferroelectric random access memory, ferroelectric-based field effect transistors, and the ferroelectric tunnel junction for the novel information processing systems.
Quantum fluctuation theorem for initial near-equilibrium system
Authors: Xu Bao-Ming
Published: May 2023

Quantum fluctuation theorem (FT) commonly requires the system initially prepared in an equilibrium state. Whether there exists universal exact quantum FT for initial states beyond equilibrium needs further discussions. In the present paper, we initialize the system in a near-equilibrium state, and derive the corresponding modified Jarzynski equality by using perturbation theory. The correction is nontrivial since it directly leads to the principle of maximum work or the second law of thermodynamics for near-equilibrium system, and also offers a much tighter bound of work. Two prototypical near-equilibrium systems driven by a temperature gradient and an external field, are taken into account, to confirm the validity and the generality of our theoretical results. Finally, a fundamental connection between quantum critical phenomenon and near-equilibrium state at really high temperature is revealed.
Wide Area Standby Automatic Switching Control Scheme Considering Renewable Energy
Authors: Yan Yabing , Xu Liqiang , Huang Yong , Li Hui , Su Tiantian , Wang Ding
Published: May 2023

The backup automatic switch (BPAS) will refuse to operate when considering the support of bus voltage provided by the distributed renewable energy, thus threatening the stable operation of the distributed network. To address this problem, an optimized control scheme based on the wide-area BPAS is proposed. The mechanism of the refusal of BPAS caused by distributed renewable energy is analysed. Then, to improve the reliability of the power supply without discarding renewable energy, the existence of renewable energy is judged with the help of the energy management system, and the capacity ratio of the renewable energy and load is calculated. Then the capacity ratio is used to optimize their coordinated operation, e.g., their adjustments and recovery. Simulation results show that the optimized BPAS control scheme can effectively ensure the consumption of renewable energy and the power quality of load.
Feasibility Analysis of a Direct-drive PV Heat Pump System Based on Phase Change Heat Storage
Authors: Liu Junjie , Fan Yi , Shi Zhengrong , Zhang Tao
Published: May 2023

A direct-drive PV pump system based on phase change heat storage is proposed to address the current building energy consumption problem in heating/cooling. The system can solve the problems of unstable solar energy, high battery cost, and short battery service life. Taking a 45m
2 office in Shanghai as the research object, the annual dynamic simulation model of the system is built through TSNSYS. The linear weighted evaluation function method is used for multi-objective optimization analysis of system performance and cost. The results show that the selection scheme with a PV area of 26 m2, a phase change volume of 0.14 m3, and a valley electricity storage ratio of 1 has the best-combined performance and cost of the system.
Optimal Design of Biomass-centered Integrated Energy System under Uncertainty
Authors: Zhao Pengxiang , Zhu Jianjun , Zhang Yanru , Wang Qiang , Yang Xian , Cong Lin
Published: May 2023

To achieve the goal of carbon peak and carbon neutrality, China is actively promoting the production and consumption of clean and sustainable energy such as biomass. The optimization of integrated energy system (IES) configuration including biomass has gradually become a research hotspot. In this paper, aiming at the configuration optimization problem of biomass-centered IES under uncertainty, considering the uncertainty of user load and energy price, the maximum annual profit is selected as the objective function, and the configuration planning model of IES under uncertainty is established. Then, the artificial bee colony (ABC) algorithm is used to solve the optimization model, and the influence of uncertainty factors on the configuration optimization of IES is explored. The results of the example show that with the two-stage stochastic programming model used to deal with the uncertainty factors in the IES, the equipment configuration capacity and operating parameters in the system are changed compared with the results of the deterministic conditions. It can overcome the problem of over-optimism in the deterministic condition and reduce the system operation risk due to the random variation of uncertainty factors.
Research on Key Technology of 110/220 kV High Voltage Smooth Aluminum Sheath Cable
Authors: Ye Haoqiang , Fang Jiong , Wang Chengzhu , Han Qifang , Hu Menglong , Yue Zhenguo
Published: May 2023

In order to solve the problem of frequent body and buffer layer discharge ablation of Corrugated Aluminum Sheath XLPE cable in China, in this paper, the discharging principle and influencing factors caused by corrugated aluminum sheathed cables are analyzed, and a smooth aluminum sheathed cable design scheme to slow down the discharge ablation phenomenon is proposed. Furthermore, the production process of smooth aluminum sheath high voltage cable is deeply studied, and the integrated new process production line is designed. The nano-mold drawing process of the aluminum sheath (Compact Wheel Diameter Reduction), the multi-layer co-extrusion process of the anti-corrosion layer (Hot Melt Adhesive), the outer sheath and the conductive layer are developed, the buffer layer structure is optimized, and a number of technologies such as wire cloth are added. Finally, the application and technical effect of the smooth aluminum sheath are analyzed, which provides a reference for the production and practical engineering application of the smooth aluminum sheath technology.
Static Test Verification on Retrofitting Method for On-service Transmission Tower
Authors: Wu Huifeng , Huang Zenghao , Wu Lilin , Liao Yongli , Li Yue
Published: May 2023

Retrofitting methods for transmission tower on-service conditions should avoid punching and welding. This paper presents a non-destructive retrofitting method, the T-shaped composite angles method, to meet the demand. The original angle was combined with retrofitting components by V-shaped clamps. Both numerical analysis and static loading test were carried out to verify the effectiveness of this retrofitting method. The test results show that compared with the lateral stiffness of the original transmission tower segment, the stiffness of the reinforced one increased. The load-bearing capacity of the reinforced transmission tower segment almost doubled that before the reinforcement. The proposed retrofitting method is non-destructive and effective.
Design of A Mobile Photovoltaic Direct-drive Refrigeration Compartment
Authors: Zhang Wenyuan , Shi Zhengrong , Zhang Tao
Published: May 2023

The large consumption of nonrenewable energy has caused energy shortages and environmental climate problems, and improper food storage has caused a large amount of food waste. To solve the problem of energy shortage and waste in grain transportation, a photovoltaic direct-drive refrigeration compartment based on apple transportation is designed. The design adopts a 15-foot refrigeration compartment and uses lightweight crystalline silicon PV modules to reduce the overall weight of the refrigeration compartment. According to the room size, eight parallel PV modules are selected for power generation. In conjunction with the PV modules, the rated power of the chosen compressor is 2.6 kW. Based on the storage conditions of apples, the design storage temperature is 0 °C, and HM-EO-2 is used as the refrigerant for cold storage. According to the transportation requirements of apples, the designed cold storage capacity of the cryogen should meet the 48h cold load. The mathematical models of the cold load of refrigeration compartments, refrigerant storage, and solar irradiation are established, which verify that the refrigeration system is correctly selected, and the critical parameters of the cold storage system are designed. It is calculated that the maximum hourly cold load and the daily total cold load of the refrigeration compartment are taken on June 29. The maximum hourly load is 1.355 kW, and the daily total load is 16.781 kW. The selected compressor can meet the real cooling demand.
Short-term power forecasting model based on GWO-LSTM network
Authors: Li Cong , Lu Renxiang
Published: May 2023

In view of the time-series characteristics of the grid load data, this paper proposes a method to predict electricity demand by optimizing a long-and short-term memory (LSTM) neural network model using the grey wolf optimization algorithm, taking into account the effects of time, weather conditions and holiday conditions on electricity loads. The model overcomes the disadvantage that the backpropagation through the time algorithm tends to converge to a local optimum. The experimental results show that the prediction results outperform those of the traditional LSTM for short-term electricity loads, providing a reference direction for future electricity forecasting models.
Power Cable Terminal Fault Detection Method Based on Infrared Thermal Imaging
Authors: Zheng Yang , Sun Baiqiang
Published: May 2023

According to the analysis results, most conventional power cable terminal fault detection methods use the time-domain joint analysis principle to determine whether the terminal has abnormal and fault-hidden dangers. Then, it carries out fault detection. The detection process is complex and time-consuming, and the cable terminal fault information cannot be obtained the first time. Based on this, infrared thermal imaging technology is introduced, and a new fault detection method is proposed. The method comprises the following steps. Firstly, acquire operation data of a power cable terminal and preliminarily judge whether the cable terminal is abnormal according to dynamic changes of conductive thermal resistance and convective thermal resistance of the terminal. Secondly, introduce an infrared thermal imaging technology on the basis and capture infrared rays radiated by the power cable terminal. Lastly, acquire temperature information of the surface of the terminal, combine the temperature with infrared ray quantity results in two directions, and make all-round detection of cable terminal faults. The experimental analysis indicates that the proposed cable terminal fault detection method can complete the fault detection in a shorter time. The detection time is shorter, and the efficiency is higher.
Research on Power Line Extraction and Modeling Technology Based on Laser Point Cloud
Authors: Yu Yongrui , Shi Lei , Ran Zhihong , Qiu Shi , Ou JinYong , Wu Shan
Published: May 2023

For the operation and maintenance management of Power Lines, this paper uses laser scanners to collect data from the research lines, and proposes a method combining random sampling consistency with Euclidean clustering to extract the traverse point cloud data. Firstly, the idea of random sampling consistency is used to eliminate a large number of ground points unrelated to target points. Secondly, Euclidean clustering is used to extract traverse and tower points, and then the tower and traverse are divided by combining tower coordinates and threshold. Finally, the polynomial model is used to construct a fitting traverse. The results show that this method can effectively extract the traverse points and accurately fit the traverse model, and it has certain applicability.
Transformer Vibration Signal Feature Extraction Based on Compressed Sensing and Wavelet Packet
Authors: Ning Xin , chi Wu , Xiao Lei , Zhu Ke
Published: May 2023

Transformers are important equipment in the power system. Aiming at the collection, transmission, storage, and processing of massive high-dimensional vibration data in the process of transformer vibration online monitoring, this paper proposes a transformer vibration signal feature extraction method based on compressed sensing and wavelet packets. Firstly, the PartHadamard measurement matrix is used to compress the transformer vibration signal, and then the characteristics of the transformer vibration signal are extracted based on the wavelet packet decomposition and normalized wavelet information entropy. The proposed method completes feature extraction on the measured vibration data of the transformer, and three classification algorithms are applied to carry out simulation experiments. The results show that the proposed feature extraction method can effectively extract the vibration characteristics reflecting the operating state of the transformer while greatly reducing the dimension of vibration data, which provides a reference for the online monitoring of transformer vibration.
Optimization of W-DCGAN Fault Diagnosis Method Based on Self-attention Mechanism
Authors: Sun Shilin , Lu Renxiang
Published: May 2023

Bearing component is the most important component of wind turbine, the harsh operating environment makes the bearing prone to failure, and the maintenance cost is very expensive when a failure occurs. Complex environmental noise brings serious noise pollution to fault samples. In addition, the serious sample imbalance between fault samples and normal samples brings great challenges to bearing fault diagnosis. In view of the above mentioned problems, this paper uses a self-attention mechanism optimization and Wasserstein distance improvement deep convolutional adversarial network model based on self-attention mechanism optimization and Wasserstein distance improvement deep Bearing fault diagnosis method based on the convolution generative Adversarial Network Model (SAW-DCGAN). The experimental results show that W-DCGAN has excellent generating ability and can generate samples like real samples to achieve the balance of samples. The addition of self-attention makes the classification features more expressive, and can accelerate the training speed of the model while having a higher fault diagnosis rate, which verifies the practicability of the method.
Performance Analysis of Beidou Precise independent point locationconsidering ISB parameters in complex Transmission Line Environment
Authors: Zhang Hui , Zhao Jian , Yu Jiangshun , Yu Rong , Liu Wei , Wang Di , Liu Dandan
Published: May 2023

This paper analyzes the inter-system deviation between B1I/B3I semaphores and B1I/B3I and B1C/B2a semaphores of Beidou-2 and Beidou-3 semaphores, and analyzes the precision single independent point locationperformance of Beidou-2 / Beidou-3 semaphores under the condition of B1I/B3I and B1C/B2a semaphores. Through the experiment, the system deviation parameters between B1C/B2a semaphores of the two satellite systems are greater than that of B1I/B3I semaphores, and both have good intra-day and inter-day stability. The participation of Beidou-3 satellite system can significantly improve the positioning function precision one point positioning of Beidou-2. The location astringent time is reduced by about 51.9%, and the positioning accuracy is increased by about 46.1%. Compared with B1I/B3I semaphores, after B1C/B2a semaphores of Beidou-3 participate in precision single independent point locationcalculation, the astringent time of precision single point location is greatly shortened. After estimating and correcting the system deviation parameters, the astringent time of static and dynami PPP of the two satellite systems is shortened by 8.8% and 12.6% respectively, and the positioning precision is promoted by 7.1%.
Research on optimization of power dispatching under the constraint of deviation electricity
Authors: Cheng Dan , Zhang Xiaoqing , Li Yujie , Zhu Lina , Tang Lei , Ye Xuwei , Xu Wei
Published: May 2023

In the medium- and long-term electricity market, uncertain power output, and power load will lead to the deviation between the actual generation and the signed medium- and long-term contract electricity. In order to reduce the system deviation balance cost and ensure the balance of power supply and demand, it is necessary to find a suitable dispatch method. First, a monthly electricity decomposition model of thermal power units is proposed in this paper. After that, we propose a power dispatching model under the constraint of deviated electricity quantity to minimize the cost of electricity deviation. The simulation results of numerical examples show that the proposed dispatching model and method can effectively reduce the monthly contract power deviation and the balance cost.
Temperature simulation of oil-immersed transformerbased on fluid-thermal coupling
Authors: Li Min , Yao Wei , Gao Xin , Ren Yan
Published: May 2023

The main components of the transformer face overheating and insulation aging caused by electromagnetic losses, which affect their service life. This paper analyzes an oil-immersed transformer with a rated voltage of 800kV based on heat transfer and fluid dynamics principles. The temperature distribution is carried out by magnetic-thermal coupling simulation. The influence of insulation oil flow rate on temperature is analyzed in the thermal field calculation, and the overall temperature rise of transformer and insulating oil is obtained. It turned out that the highest hot spot of the transformer occurs in the low-voltage winding, and the flow speed of insulation oil between the winding is the fastest.
Electrical Performance Analysis of Grading Electrodes After Scaling in Converter Valves
Authors: Wu Shuya , Yin Jiliang , Zhang Chao , Zhai Beihong , Ouyang Taoyu , Guo Jingyi , Wang Quantao , Ding De , Liu Lei , Wu Yuewei
Published: May 2023

It is necessary to take out the electrode when detecting the scaling degree of the conventional grading electrode. The steps are cumbersome and there are safety risks. In this paper, through the analysis of the equivalent circuit model before and after the scaling of the grading electrode on the cooling water manifold in the converter valve, the loop resistance model suitable for the positive and negative potential sides is obtained. The constant voltage DC source is used as the driving voltage of the circuit, and the leakage current of the circuit is measured under different temperatures and conductivity conditions of the internal cooling water. The degree of scaling of the grading electrode is determined by analyzing the leakage current. The leakage current in the non-scaling state of the grading electrode and the leakage current in the scaling failure state of the grading electrode are taken as the reference values. It is concluded that when the leakage current of the measurement circuit decreases to 68 % - 80 % of the leakage current in the non-scaling state of the grading electrode, the grading electrode can be considered to fail.
The Design and Simulation of Associated Protection for Low Voltage Shore-to-ship Power Supply System in Inland Port
Authors: He Shengli , Deng Renren , Zhou Rongbin , Ren Jialei , Yang Ping
Published: May 2023

Due to the complex environmental conditions of inland ports, it is of great significance to adopt associated protection to ensure the safe and reliable operation of the shore-to-ship power supply system. To accurately simulate the operating conditions of the shore-to-ship power supply system, the simulation model of the ship power system is established completely. According to the characteristics of the inland port, the simulation model of the shore-based power supply system is designed and established. Based on the established simulation model of a low voltage shore-to-ship power supply system, to meet its protection requirements of it, an associated protection method including safety interlock, under-voltage protection, and short-circuit protection is proposed. To verify the effectiveness of the associated protection, power faults are set in the shore-to-ship power supply system, and the action of the associated protection during the fault is analyzed by comparing the voltage and current waveforms of the shore-to-ship power supply system with associated protection and unprotected ones. The results show that the associated protection can effectively detect the power failures of the shore-to-ship power supply systems and take timely protection measures to ensure equipment safety.
Modeling and Simulation of Indirect Collector Solar Hot Water Heating System Based on TRNSYS
Authors: Hu Dawei , Liu Hengyu , Zhu Yidong , Zhang Tianyu , Wang Jun , Zhang Zhongrui , Sun Jiazheng , Yuan Jingwei , Zhang Zhe , Yang Luyu
Published: May 2023

The use of solar energy is one of the important ways of clean energy heating in rural areas in the north, and the collector solar water heating system is an effective way to use solar energy. This paper takes a typical single residential house in a rural area of Shenyang as a research case to design an indirect collector solar hot water heating system. Based on the meteorological data of the winter heating period (November 1 - March 31 of the following year) in Shenyang, TRNSYS software was used to research the heat collection efficiency and scheme design of the heating system. The research results showed that: 1) The best material of the heat exchange coil of the hot water storage tank in the solar water heating system of the indirect collector is stainless steel with a thickness of 0.8mm; 2) The optimal installation angle of solar collectors in Shenyang is 55°; 3) The optimal area of the heat exchanger coil in the hot water storage tank is 4.40m2.
Research on Path Planning of Manipulator for Terahertz Time-domain Imaging System of Power Insulators
Authors: Luo Guofang , Chen Hongtao , Liu Ping-an , Wang Yujian , Liu Yongli , Zhou Kuan , Han Jingxin , Wang Dong , Chen Xi
Published: May 2023

To ensure detection accuracy, the focus of the terahertz lens is required to be located on the surface of the workpiece in the process of terahertz imaging detection, and the outgoing optical axis of the lens is also required to be perpendicular to the surface of the workpiece. Therefore, when imaging curved samples, a 6-degree freedom manipulator is generally used to drive the terahertz lens, and the lens realizes non-destructive testing along the workpiece surface. The mechanical arm is required to drive the terahertz lens to move along the rotation curve in a two-dimensional plane when the mechanical arm is used to detect the power insulator of the rotating structure. This paper focuses on the path planning of the manipulator, that is, the curve is divided into several connected straight lines and arcs, and the manipulator moves continuously in each characteristic line segment. The D-H dynamic model of the manipulator was established to analyze the joint velocity and acceleration to ensure the stability of the moving process.
Design of Secondary Circuit Visualization System for UHVDC Converter Stations
Authors: Liu Ruopeng , He Kai , Zhang Liming , Geng Xiangrui
Published: May 2023

For the problems of complicated work content and error-prone workload of secondary circuits, a three-dimensional visualization method is proposed for the visualization and management of the physical circuits of the control and protection system of the converter station based on digital twin technology. The system can be used to improve the work efficiency of operation and maintenance personnel by constructing a secondary circuit information data model, generating corresponding data through artificial intelligence image recognition and manual review of secondary circuit drawings and schematics, and performing accurate corresponding circuit data analysis and 3D visualization management of the secondary physical circuits of control and security equipment, which can visualize the circuit information of control and security equipment in the station from outside to inside at multiple levels and multiple dimensions.
Simulation and Analysis of Harmonic High Voltage Filters for Wind Farm
Authors: Li Shupeng , Wu Bin , Li Qirui , Li Zhenbin , Chen Zhaoyu , Song Chao
Published: May 2023

With the rapid development of the wind power industry, the total installed capacity of wind power has increased dramatically worldwide, and a large number of wind power installations need to be connected to the grid. In wind turbines, voltage flicker due to output power fluctuations caused by wind speed changes, and the application of a Voltage Source Converter (VSC) cause harmonic richness and other power quality problems to become more and more prominent. In this regard, the research is focused on the harmonic and reactive current distribution, impedance frequency characteristics, and voltage distortion rate of several offshore wind farm access systems, including the establishment of a harmonic current simulation model of the offshore wind farm delivery system, simulation analysis of network impedance frequency characteristics, simulation analysis of harmonic currents, and proposed a preferred filtering scheme. Taking into full consideration the characteristic harmonics of the wind farm, the system resonance generated by the submarine cable and the background harmonic level of the power grid, combined with the simulation results of the harmonic voltage, harmonic current, and network impedance frequency characteristics of each node, the technical solution of adding a direct-mounted high-voltage filtering device to the 220 kV bus at the metering station is proposed, which can destroy the system resonance conditions of the 3rd to 6th times of the submarine cable. Various wind farms and system operating conditions are able to form a stable harmonic absorption point to avoid the problem of harmonic amplification.
Numeerical Calculation and Test of the Influence of Environmental Vibration on Coriolis Flowmeter
Authors: Lian Mingming , Zheng Jin , Li Zhen , Huang Dongkui , Xue Qingfeng , Zhou Zhaoming
Published: May 2023

Coriolis mass flowmeters are resonant meters. In this paper, the intrinsic mode of the CMF300 model Coriolis flowmeter under fluid-structure interaction is calculated numerically, and the excitation mode and Coriolis force mode of the Coriolis mass flowmeter in the working state are analyzed. According to the results of modal analysis, the harmonic response analysis of the flowmeter was carried out, and the displacement, stress, and strain response curves of CMF300 under the action of excitation force of different frequency loads were obtained. It provides ideas for the modeling and design of Coriolis mass flowmeters in the future.
Closed-loop Control of Biaxial Fatigue Loading of Wind Turbine Blades Based on Visual Inspection
Authors: Liao Gaohua , Zhao Ying , Hong Zhimin , Zhang Zhiyi , Zeng Haoyu
Published: May 2023

Based on the inertial vibration excitation device, a biaxial fatigue loading system for wind turbine blades is established by using visual inspection technology and virtual spindle decoupling to control the vibration excitation motion of wind turbine blades. The image feature point tracking method is used to detect the blade vibration state. Considering the system vibration frequency characteristics, the phase difference between the exciting force and the vibration displacement is detected based on the phase detector, and the system resonance frequency is adaptively tracked to achieve accurate control of the double-free amplitude of the blade. The fatigue test shows that the control system can maintain the amplitude error of the blade, the adaptive tracking control method is reliable and effective, and the accuracy and reliability of the fatigue test are improved.
Numerical Calculation of Wet Exhaust Gas Condensation in the Heat Exchanger
Authors: Guo Jingzhong , Gu Yuheng , Zheng Tianshuai , Cui Shujie , Ye Aqu , Yu Xiaobing , Zhao Ruoyu , Jiang Feng
Published: May 2023

Based on the background of waste heat recovery of gas-fired boiler, this paper studied wet exhaust gas condensation heat transfer using numerical methods. The calculated results indicated that with the exhaust gas Re number increases, heat flux, and Nu number gradually increase, while the Eu number decreases simultaneously. Besides, the variation trend of the Nu and Eu number gradually reduced with Re number increases. With inlet exhaust gas temperature increase, the Nu number increases, and the Eu number decreases. Meanwhile, Nu number and Eu number increases with the increase in wall temperature. On this basis, the empirical correlations for calculating Nu and Eu numbers are obtained, and the deviation between the calculated values and the numerical results is within ±8%. The conclusion of this study provides basis for heat exchanger design in wet exhaust gas waste heat recovery.
Research and Design of RF Ion Source Impedance Matching Network
Authors: Pan Jun-jun , Jiang Cai-chao , Liu Zhi-min , Chen Shi-yong , Liu Sheng
Published: May 2023

The radio frequency (RF) ion source is the key component of the neutral beam injector to achieve high power and long pulse operation. The key technology is feeding RF power from the power source to the ion source and producing stable plasma. It is impossible to calculate the exact equivalent impedance of plasma during discharge, and the impedance will change with the change in discharge pressure and feed power. In order to transfer the maximum output power of the RF power source to the coil antenna of the ion source, an impedance-matching network must be added between the power source and the ion source. Four possible matching network structures are designed by the Smith diagram circle method, and two kinds of capacitor structures are calculated and analyzed. The influence of capacitance change on impedance matching state is analyzed, and the electrical parameters of capacitance under the two structures are compared. After comparison and analysis, the structure of the parallel capacitor is first, and then the series capacitor is selected. Finally, the plasma discharge can be stable through experiments. The research on the matching network is of great significance for the development and experimental operation of the RF feeding system of the high-power RF ion source in the future
Transfer Deep Learning Network for Rolling Bearing Fault Diagnosis of Wind Turbines
Authors: Cheng Zhiwei , Li Xuejiao , Peng Guangbin , Deng Yongsheng , Xie Zhihong , Liu Lian
Published: May 2023

Fault diagnosis of rolling bearings has become a critical measure to ensure the security, efficiency, and availability of wind turbine systems. In this work, an approach called a transfer deep learning network is reported to resolve the drawbacks of existing rolling bearing fault algorithms on the basis of deep learning, such as large training parameters, long training time, and insufficient training samples. The reported approach mainly consists of two steps: feature transfer using transfer component analysis and network transfer using the pre-trained convolutional neural network. One dataset of rolling bearings with four fault types is gathered to estimate the classification performance, and the peer model is employed for a comparison study. The derived research results show that the reported algorithm based on the feature transfer and the network transfer can yield outstanding results in the rolling bearing fault diagnosis.
Research on Finite Element Analysis and Torque Ripple Suppression of the Switched Reluctance Motor
Authors: You XiaoXiao , Chu ChunLin , Zhang TianYuan , Sun BaoJiang
Published: May 2023

To repress the torque ripple of the switched reluctance motor, this study takes a three-phase 12/8-pole switched reluctance motor as an instance and simulates the electromagnetic field of the motor using Maxwell finite element software to analyze the influence of electromagnetic characteristics and pole arc parameters on the torque ripple of the motor. In conjunction with the Workbench platform, the response surface method and multi-objective genetic algorithm are used to optimize the pole arc coefficients so the average torque of the optimized motor meets the operating requirements while the torque ripple is suppressed. The findings demonstrate that various structural parameters have diverse impacts on motor torque and that multi-objective optimization can significantly diminish the torque ripple of the motor.
Redox-responsive self-assembled podophyllotoxin twin drug nanoparticles for enhanced intracellular drug delivery
Authors: Ma Yingyu , Chen Lei , Deng Lian , Li Xuebing , Zhao Xiu , Jiang Daobing , Liu Jiabao , Song Yang , Liu Junda , Cui Nan , Qiu Neng
Published: May 2023

Podophyllotoxin (PPT) is an active natural pharmaceutical component with potent anticancer activity. However, due to its poor water solubility and serious side effects, its medical applications are limited. In this work, we synthesized a series of PPT dimers, which can be self-assembled into stable nanoparticles of 124–152 nm in aqueous solution and can significantly increase the solubility of PPT in aqueous solution. In addition, PPT dimer nanoparticles exhibited high drug loading capacity (>80%) and could store at 4 °C in aqueous state with good stability for at least 30 d. In vitro release studies showed that nanoparticles with disulfide bonds (SS NPs) can quickly release (about 96.5% drug released within 24 h) the conjugated drug in PBS buffer (pH = 7.4) in the presence of DTT. Cell endocytosis experiments showed that SS NPs enhanced cell uptake (18.56 times higher than PPT for Molm-13, 10.29 times for A2780S and 9.81 times for A2780T) and maintained antitumor effect against human ovarian tumor cells (A2780S and resistant A2780T) and human breast cancer cells (MCF-7). In addition, the endocytosis mechanism of SS NPs was revealed that these nanoparticles were mainly up-taken by macropinocytosis-mediated endocytosis. We believe that these PPT dimer-based nanoparticles will become an alternative formula for PPT, moreover the assembly behavior of PPT dimer can be extended to other therapeutic drugs.