bluuebunny/crossref_metadata_2025 huggingface dataset:
A random batch method for efficient ensemble forecasts of multiscale turbulent systems
Authors: Qi Di , Liu Jian-Guo
Published: February 2023

A new efficient ensemble prediction strategy is developed for a multiscale turbulent model framework with emphasis on the nonlinear interactions between large and small-scale variables. The high computational cost in running large ensemble simulations of high-dimensional equations is effectively avoided by adopting a random batch decomposition of the wide spectrum of the fluctuation states, which is a characteristic feature of the multiscale turbulent systems. The time update of each ensemble sample is then only subject to a small portion of the small-scale fluctuation modes in one batch, while the true model dynamics with multiscale coupling is respected by frequent random resampling of the batches at each time updating step. We investigate both theoretical and numerical properties of the proposed method. First, the convergence of statistical errors in the random batch model approximation is shown rigorously independent of the sample size and full dimension of the system. Next, the forecast skill of the computational algorithm is tested on two representative models of turbulent flows exhibiting many key statistical phenomena with a direct link to realistic turbulent systems. The random batch method displays robust performance in capturing a series of crucial statistical features with general interests, including highly non-Gaussian fat-tailed probability distributions and intermittent bursts of instability, while requires a much lower computational cost than the direct ensemble approach. The efficient random batch method also facilitates the development of new strategies in uncertainty quantification and data assimilation for a wide variety of general complex turbulent systems in science and engineering.
High-gain low-excess-noise MWIR detection with a 3.5-µm cutoff AlInAsSb-based separate absorption, charge, and multiplication avalanche photodiode
Authors: Dadey Adam A. , McArthur J. Andrew , Kamboj Abhilasha , Bank Seth R. , Wasserman Daniel , Campbell Joe C.
Published: February 2023

Mid-wavelength infrared (MWIR) detection is useful in a variety of scientific and military applications. Avalanche photodiodes can provide an advantage for detection as their internal gain mechanism can increase the system signal-to-noise ratio of a receiver. We demonstrate a separate absorption, charge, and multiplication avalanche photodiode using a digitally grown narrow-bandgap Al0.05InAsSb absorber for MWIR detection and a wide bandgap Al0.7InAsSb multiplier for low-excess-noise amplification. Under 2-µm illumination at 100 K, the device can reach gains over 850. The excess noise factor of the device scales with a low k-factor of ∼0.04. The unity-gain external quantum efficiency of the device attains a peak of 54% (1.02 A/W) at 2.35 µm and maintains an efficiency of 24% (0.58 A/W) at 3 µm before cutting off at ∼3.5 µm. At a gain of 850, the device has a gain-normalized dark current density of 0.05 mA/cm2. This device achieves gains more than double that of the state-of-the-art InAs detectors and achieves gain-normalized dark current densities over two orders of magnitude lower than that of a previously reported MWIR Al0.15InAsSb-based detector.
N-WASP is competent for downstream signaling before full release from autoinhibition
Authors: Dey Souvik , Zhou Huan-Xiang
Published: February 2023

Allosteric regulation of intrinsically disordered proteins (IDPs) is still vastly understudied compared to the counterpart of structured proteins. Here, we used molecular dynamics simulations to characterize the regulation of the IDP N-WASP by the binding of its basic region with inter- and intramolecular ligands (PIP2 and an acidic motif, respectively). The intramolecular interactions keep N-WASP in an autoinhibited state; PIP2 binding frees the acidic motif for interacting with Arp2/3 and thereby initiating actin polymerization. We show that PIP2 and the acidic motif compete in binding with the basic region. However, even when PIP2 is present at 30% in the membrane, the acidic motif is free of contact with the basic region (“open” state) in only 8.5% of the population. The very C-terminal three residues of the A motif are crucial for Arp2/3 binding; conformations where only the A tail is free are present at a much higher population than the open state (40- to 6-fold, depending on the PIP2 level). Thus, N-WASP is competent for Arp2/3 binding before it is fully freed from autoinhibition.
Collision regimes and dynamic behaviors of a viscous droplet impacting on a spherical particle at high temperatures
Authors: Geng Pengfei , Ma Jiliang , Chen Xiaoping , Liu Daoyin , Pan Suyang , Liang Cai
Published: February 2023

Understanding droplet–particle collision behaviors is essential for the pyrohydrolysis process of pickling liquor, where the pickling liquor is sprayed and dried into particles. This study systematically investigated the collision characteristics between a viscous droplet and a heated stainless steel particle whose temperature ranged from 100 to 700 °C. The results indicate that the vapor thrust promotes droplet rebound in smaller spreading diameters but induces disintegration in larger spreading diameters under the film boiling regime. The collision regime map is summarized, and the transition thresholds of collision patterns are significantly increased with increasing liquid viscosity. The spreading factor and contact line velocity are strongly affected by the particle temperature at high liquid viscosities. In addition, the hydrophobic nature of particle surface in film boiling regime is favorable for droplet spreading. The dynamic contact angle significantly depends on the particle temperature and droplet properties. The dimensionless contact time shows a power law dependency on the Weber number in the rebound pattern, but it is almost a constant in the disintegration pattern.
A derivation of the conditions under which bosonic operators exactly capture fermionic structure and dynamics
Authors: Montoya-Castillo Andrés , Markland Thomas E.
Published: February 2023

The dynamics of many-body fermionic systems are important in problems ranging from catalytic reactions at electrochemical surfaces to transport through nanojunctions and offer a prime target for quantum computing applications. Here, we derive the set of conditions under which fermionic operators can be exactly replaced by bosonic operators that render the problem amenable to a large toolbox of dynamical methods while still capturing the correct dynamics of n-body operators. Importantly, our analysis offers a simple guide on how one can exploit these simple maps to calculate nonequilibrium and equilibrium single- and multi-time correlation functions essential in describing transport and spectroscopy. We use this to rigorously analyze and delineate the applicability of simple yet effective Cartesian maps that have been shown to correctly capture the correct fermionic dynamics in select models of nanoscopic transport. We illustrate our analytical results with exact simulations of the resonant level model. Our work provides new insights as to when one can leverage the simplicity of bosonic maps to simulate the dynamics of many-electron systems, especially those where an atomistic representation of nuclear interactions becomes essential.
An ab initio method on large sized molecular aggregate system: Predicting absorption spectra of crystalline organic semiconducting films
Authors: Liu Wenlan , Andrienko Denis
Published: February 2023

Theoretical description of electronically excited states of molecular aggregates at an ab initio level is computationally demanding. To reduce the computational cost, we propose a model Hamiltonian approach that approximates the electronically excited state wavefunction of the molecular aggregate. We benchmark our approach on a thiophene hexamer, as well as calculate the absorption spectra of several crystalline non-fullerene acceptors, including Y6 and ITIC, which are known for their high power conversion efficiency in organic solar cells. The method qualitatively predicts the experimentally measured spectral shape, which can be further linked to the molecular arrangement in the unit cell.
Temperature dependence of DNA elasticity: An all-atom molecular dynamics simulation study
Authors: Zhang Yahong , He Linli , Li Shiben
Published: February 2023

We used all-atom molecular dynamics simulation to investigate the elastic properties of double-stranded DNA (dsDNA). We focused on the influences of temperature on the stretch, bend, and twist elasticities, as well as the twist–stretch coupling, of the dsDNA over a wide range of temperature. The results showed that the bending and twist persistence lengths, together with the stretch and twist moduli, decrease linearly with temperature. However, the twist–stretch coupling behaves in a positive correction and enhances as the temperature increases. The potential mechanisms of how temperature affects dsDNA elasticity and coupling were investigated by using the trajectories from atomistic simulation, in which thermal fluctuations in structural parameters were analyzed in detail. We analyzed the simulation results by comparing them with previous simulation and experimental data, which are in good agreement. The prediction about the temperature dependence of dsDNA elastic properties provides a deeper understanding of DNA elasticities in biological environments and potentially helps in the further development of DNA nanotechnology.
Black carbon aerosols over Indian Ocean have unique source fingerprint and optical characteristics during monsoon season
Authors: Budhavant Krishnakant , Andersson August , Holmstrand H. , Satheesh S. K. , Gustafsson Örjan
Published: February 2023

Effects of aerosols such as black carbon (BC) on climate and buildup of the monsoon over the Indian Ocean are insufficiently quantified. Uncertain contributions from various natural and anthropogenic sources impede our understanding. Here, we use observations over 5 y of BC and its isotopes at a remote island observatory in northern Indian Ocean to constrain loadings and sources during little-studied monsoon season. Carbon-14 data show a highly variable yet largely fossil (65 ± 15%) source mixture. Combining carbon-14 with carbon-13 reveals the impact of African savanna burning, which occasionally approach 50% (48 ± 9%) of the total BC loadings. The BC mass-absorption cross-section for this regime is 7.6 ± 2.6 m
2
/g, with higher values during savanna fire input. Taken together, the combustion sources, longevity, and optical properties of BC aerosols over summertime Indian Ocean are different than the more-studied winter aerosol, with implications for chemical transport and climate model simulations of the Indian monsoon.
Effective bet-hedging through growth rate dependent stability
Authors: de Groot Daan H. , Tjalma Age J. , Bruggeman Frank J. , van Nimwegen Erik
Published: February 2023

Microbes in the wild face highly variable and unpredictable environments and are naturally selected for their average growth rate across environments. Apart from using sensory regulatory systems to adapt in a targeted manner to changing environments, microbes employ bet-hedging strategies where cells in an isogenic population switch stochastically between alternative phenotypes. Yet, bet-hedging suffers from a fundamental trade-off: Increasing the phenotype-switching rate increases the rate at which maladapted cells explore alternative phenotypes but also increases the rate at which cells switch out of a well-adapted state. Consequently, it is currently believed that bet-hedging strategies are effective only when the number of possible phenotypes is limited and when environments last for sufficiently many generations. However, recent experimental results show that gene expression noise generally decreases with growth rate, suggesting that phenotype-switching rates may systematically decrease with growth rate. Such growth rate dependent stability (GRDS) causes cells to be more explorative when maladapted and more phenotypically stable when well-adapted, and we show that GRDS can almost completely overcome the trade-off that limits bet-hedging, allowing for effective adaptation even when environments are diverse and change rapidly. We further show that even a small decrease in switching rates of faster-growing phenotypes can substantially increase long-term fitness of bet-hedging strategies. Together, our results suggest that stochastic strategies may play an even bigger role for microbial adaptation than hitherto appreciated.
Molecular mechanism and energetics of coupling between substrate binding and product release in the F
1
-ATPase catalytic cycle
Authors: Badocha Michał , Wieczór Miłosz , Marciniak Antoni , Kleist Cyprian , Grubmüller Helmut , Czub Jacek
Published: February 2023

F
1
-ATPase is a motor protein that couples the rotation of its rotary

γ

subunit with ATP synthesis or hydrolysis. Single-molecule experiments indicate that nucleotide binding and release events occur almost simultaneously during the synthesis cycle, allowing the energy gain due to spontaneous binding of ADP to one catalytic

β

subunit to be directly harnessed for driving the release of ATP from another rather than being dissipated as heat. Here, we examine the unknown mechanism of this coupling that is critical for an exceptionally high mechanochemical efficiency of F
1
-ATPase by means of all-atom free-energy simulations. We find that nondissipative and kinetically fast progression of the motor in the synthesis direction requires a concerted conformational change involving the closure of the ADP-binding

β

subunit followed by the gradual opening of the ATP-releasing

β

subunit over the course of the 30 to 40° rotary substep of the

γ

subunit. This rotary substep, preceding the ATP-dependent metastable state, allows for the recovery of a large portion of the ADP binding energy in the conformation of ATP-bound

β

that gradually adopts the low-affinity conformation, captured also by the recent cryo-EM structure of this elusive state. The release of ATP from this nearly open conformation leads to its further opening, which enables the progression of the motor to the next catalytic metastable state. Our simulations explain this energy conversion mechanism in terms of intersubunit and ligand–protein interactions.
La negociación de la autenticidad en el lenguaje dialógico del turismo digital
Authors: Vittoria Calvi Maria , Suau-Jiménez Francisca
Published: February 2023

Este artículo se propone realizar un análisis socio-discursivo de cómo se construye y se negocia la autenticidad en el discurso del turismo, asumiendo el acercamiento imparable que ha tenido lugar hacia la figura del cliente (Austin 2009) a través de un fenómeno comunicativo esencial como es la dialogicidad. Este discurso ha ido encarnando progresivamente unaautenticidad negociada(Cohen 1988), que va ajustándose a variables sociales, como ocurre con la pandemia por COVID-19, pero que incluye igualmente variables culturales. Utilizamos 100 muestras de oralización dialógica en español e inglés de varios cibergéneros (páginas web institucionales y redes sociales de turismo) que apoyan nuestra argumentación. Pretendemos ofrecer una visión contrastiva sobre la negociación de la autenticidad discursiva y de las emociones como elemento central en el turismo digital, según el trinomio turismo-sociedad-lenguaje, que permita una mejor comprensión de la tendencia comunicativa social actual con propósito mercantilista.
Robot 3D spatial motion measurement via vision-based method
Authors: Wu Lulu , Liu Yi , Wang Yuan , Du Xin , Xiong Xinyan , Jiang Benchi
Published: February 2023

Measuring the motion of a robot accurately is an important and integral part of evaluating the dynamic and static performance of the robot. The performance index of a robot, such as kinematic accuracy, bearing capacity, deformation, vibration, stability, and structural mode can all be calculated according to the motion displacement of the robot. Therefore, improving the robot motion measurement method, promoting the measurement accuracy, and enriching the measurement content have received considerable scholarly attention worldwide. In this paper, an approach based on binocular vision was proposed to measure the 3D spatial motion of a robot. In the process of reconstructing robot movement, a mathematical model that can facilitate the solving process and improve the accuracy of results was derived to build 3D coordinates information. A novel coordinate transformation method that is based on the singular value decomposition was drawn up to realize the transformation from camera coordinates to robot coordinates. Several experiments were carried out on the self-built three-degree-of-freedom rectangular coordinate robot platform. The marker was designed specially and glued to the end of robot, and a new train of thought was adopted to extract the marker’s feature point. The vision-based measurement results were compared with the actual coordinate value. Results of experiments demonstrated that the proposed method can successfully reconstruct the 3D spatial motion of a robot more exactly, which can meet the requirements of high-precision motion control, motion performance evaluation, and operation state evaluation.
Stylized versus voxel phantoms: quantification of internal organ chord length distances
Authors: Coleman D , Griffin K T , Dewji S A
Published: February 2023

Dosimetric calculations, whether for radiation protection or nuclear medicine applications, are greatly influenced by the use of computational models of humans, called anthropomorphic phantoms. As anatomical models of phantoms have evolved and expanded, thus has the need for quantifying differences among each of these representations that yield variations in organ dose coefficients, whether from external radiation sources or internal emitters. This work represents an extension of previous efforts to quantify the differences in organ positioning within the body between a stylized and voxel phantom series. Where prior work focused on the organ depth distribution vis-à-vis the surface of the phantom models, the work described here quantifies the intra-organ and inter-organ distributions through calculation of the mean chord lengths. The revised Oak Ridge National Laboratory stylized phantom series and the University of Florida/National Cancer Institute voxel phantom series including a newborn, 1-, 5-, 10- and 15 year old, and adult phantoms were compared. Organ distances in the stylized phantoms were computed using a ray-tracing technique available through Monte Carlo radiation transport simulations in MCNP6. Organ distances in the voxel phantom were found using phantom matrix manipulation. Quantification of differences in organ chord lengths between the phantom series displayed that the organs of the stylized phantom series are typically situated farther away from one another than within the voxel phantom series. The impact of this work was to characterize the intra-organ and inter-organ distributions to explain the variations in updated internal dose coefficient quantities (i.e. specific absorbed fractions) while providing relevant data defining the spatial and volumetric organ distributions in the phantoms for use in subsequent internal dosimetric computations, with prospective relevance to patient-specific individualized dosimetry, as well as informing machine learning definition of organs using these reference models.
An all-fiber high-power picosecond amplifier with Yb-doped polarization-maintaining tapered fiber
Authors: Wang Jianlei , Lu Jingqi , Zhang Ning , Wang Chao , Wang Chun , Zhuo Zhuang
Published: February 2023

A high-power picosecond all-fiber master oscillator power amplifier (MOPA) was demonstrated based on the Yb-doped polarization-maintaining (PM) tapered double-clad fiber (T-DCF). An all-fiberized pumping unit instead of the free space pumping structure was adopted in the MOPA system to provide a compact robust solution for high-performance amplifiers. The total average output power of 180.3 W was achieved with a slope efficiency of 80.8% by taking advantages of the large fiber mode area and the suppression of nonlinear effects in the T-DCF. The peak power was calculated to be 27.7 kW at the pulse width of 260.8 ps and the repetition rate of 24.91 MHz. The polarization extinction ratio and beam quality (M
2 factor) were measured to be ∼10 dB (91%) and ∼12, respectively.
Experimental Study on Effects of Different Water Flow Rates on Heat Transfer Characteristics of Evaporator
Authors: Yang Maoli , Wu Xianyun , Zhou Wenping , Liu Xiangshu , Qiang Rui , Huang Fuchuan
Published: February 2023

Since China set forth the goal of “dual carbon”, studies on heat transfer characteristics of evaporators have been one of the hot spots in the field of refrigeration and heating. This paper conducts an experimental study on the heat transfer performances of evaporators under different flow rates by changing the water flow of the evaporator and condenser. The results shows that on the premise of unchanged water flow of condenser, cooling coefficient of performance (COP) and heat transfer coefficient (HTC) grow with the increases in flow rates of evaporator and temperatures of inlet and outlet water. However, the changes in HTC are relatively smooth; the compressor’s inhalation and expulsion temperatures grow with the increases in water flow rates of the evaporator, and the changes are quite evident. The paper also discusses and analyzes deeply those manifestations, which provides experimental evidence for the experiments and improvement of the evaporator, optimization of evaporator design, and the enhancement of the economic performance of the system.
Research of Distributed Photovoltaic Output Fluctuation Suppression Method Based on Improved FPA
Authors: Li Shilong , Zhang Hua , Ding Lijie , Chen Yufan , Li Ao
Published: February 2023

Due to weather changes, the distributed photovoltaic (PV) output power has fluctuations, seriously affecting the power quality of the distribution network. This paper proposes a distributed PV power output fluctuation suppression method based on the improved Flower Pollination Algorithm (FPA) to solve the above problem. This method uses an annihilation perturbation mechanism and linear weights to update the pollen position, which mainly affects the output power of photovoltaic power plants. The time constant of the first-order low-pass filter is optimized, and the improved flower pollination algorithm is utilized for optimization to obtain the optimal time constant of the first-order low-pass filter, suppressing the fluctuation of distributed photovoltaic output and integrating the photovoltaic power station’s output. The simulations indicate that the improved flower pollination algorithm is better than other evaluated algorithms and has an improvement of about 11% over the particle swarm algorithm.
CO2 capture based on polyanthraquinone/carbon nanotube composites
Authors: Ling Junyi , Feng Jingsong
Published: February 2023

Carbon neutralization is a new way of environmental protection, in which carbon capture is the core of carbon neutralization. Firstly, the preparation method of polyanthraquinone/multi-walled carbon nanotube composites (PAQ/MWCNTs) was studied. The composites were prepared by magnetic stirring and centrifugal separation. The working electrode was prepared by using the composite material for carbon capture. A three-electrode system was established to capture carbon dioxide when the reduction potential was applied and to release carbon dioxide when the oxidation potential was applied by cyclic voltammetry. It is found that the carbon dioxide capture effect of the polyanthraquinone/multi-walled carbon nanotube composite prepared in this study reaches 7.80mmol/g, and the material utilization rate reaches 73.4%.
Comprehensive Energy System Evaluation Method of Low-carbon Park Based on Improved Entropy Weight
Authors: Fan Libo , Zhong Xiaohong , Chen Jiawei , Tu Yongwei , Jiang Jian
Published: February 2023

To improve the consistency between the evaluation results and the actual situation of the comprehensive energy system in the low-carbon park, the improved entropy weight algorithm is introduced to carry out the design and research of the evaluation method. Based on the principles of quantifiability, scientificity and systematicness and combined with the actual situation of system operation and the development needs of low-carbon parks, the evaluation index system of the comprehensive energy system in low-carbon parks is constructed. According to the process of primary evaluation, multi-level evaluation and comprehensive evaluation value calculation, the comprehensive energy system grade evaluation is completed. The comparative experiment proves that the evaluation results of the new evaluation method are basically consistent with the radar chart of the actual situation of the system, which shows that the evaluation results are more realistic.
Comparison of wind-induced responses of transmission tower in normal wind field and downburst wind field
Authors: Chen Keji , Zhang Linlin , Li Guoqiang , Kang Lili , Yao Jianfeng
Published: February 2023

To study the difference in the wind-induced response of the transmission tower caused by the downburst and the well-conditioned wind field, this paper uses the harmonic superposition method to simulate the well-conditioned wind field and the downburst wind field. The wind-induced responses of the transmission tower under the two wind farms are obtained and compared through the analysis. The wind-induced responses caused by the two wind fields on the transmission tower are quite different, and the downburst can cause a larger wind-induced response.
Study on mechanical properties of the cross arm-insulator system under strong wind load
Authors: Huang Xiaoyu , Tang Ziqiang , Cheng Nuo , Lin Rui , Weng Lanxi
Published: February 2023

High-voltage transmission tower-line systems in coastal areas are often affected by strong winds, which leads to structural damage to the towers. Detailed analysis of the damage mechanism of towers is very useful to ensure the safety and stability of the power system. This paper examines the mechanical properties of the cross-insulator structure under horizontal wind load, and then the load-carrying capacity and deformation performance were analyzed based on ABAQUS. The results show that the structure is stable under the load, and the main structure is basically in the elastic working stage with insignificant flexural and torsional effects. On the contrary, the local stress of the combined link rod connected with the insulator is large; the bending deformation characteristics of the combined link rod are obvious under the maximum horizontal load the insulator can withstand. This result can provide a reference for cross-arms structural safety design.
Optimization of Lateral Interlock Protection for Thermal Power Units
Authors: Zhang Lingli
Published: February 2023

According to the Twenty-Five Key Requirements for Preventing Electric Power Production Accidents, the protection of important capital and auxiliary equipment should adopt the “Two Out of Three” logic judgment method, and the protection signal should follow the whole process from the sampling point to the input module. The principle of relative independence is that the number of measuring points is insufficient due to system reasons, and measures to prevent disoperation should be taken. Considering that a coal-fired power plant’s third-phase engineering steam turbine, boiler, and generator lateral protection signals are single-point design and do not meet the requirements of countermeasures, the abnormality of a single circuit of the protection signal will cause abnormal protection actions and affect the safe and stable operation of the unit. Therefore, the original control strategy is systematically optimized by adopting the “Two Out of Three” logic and successfully passes the ETS, DEH, FSSS, and lateral interlock protection tests. The result provides a reference for equipment malfunction in the operation of the same type of units.
Study on the Electron Density Measurement of 1 m Rod-plate Gap Discharge Process under the Lightning Impulse
Authors: Zhang Yaqi , Han Yongxia , Zheng Wenbo , Yang Jie , Qu Lu , Liu Gang
Published: February 2023

Observation and measurement of the microscopic parameters in the long air gap discharge process play an important role in studying its physical mechanism and the discharge simulation model. In this paper, we combined an electron-multiplying intensified charge-coupled device (EMICCD) camera and a spectrometer, and built a lightning discharge spectrum observation platform of spatiotemporal distribution for the 1 m rod-plane air gap with nanosecond exposure time. The spatiotemporal distributions of the spectral information of the 1 m air gap discharge under positive and negative lightning impulses were obtained. Based on the atomic emission spectroscopy diagnostic method, N and O atomic spectral lines were used to calculate the corresponding electron density at different positions and time points during the breakdown discharges. The testing results were compared with other literature and the differences also were discussed.
Simulation of Branch Pipes Fracture Condition in Low-Pressure Safety Injection System of PWR
Authors: Deng Chunyin , Chen Guoxing , Lu Zhuang , Wu Shuhui
Published: February 2023

In the low-pressure injection system (LHSI) of the PWR unit, two branch pipes of the recirculation pipeline are vulnerable to fracture during minimal-flow operation. Flowmaster was used to create a hydraulic model for the LHSI minimal-flow operation and to simulate the branch double-end shear fracture condition in order to predict the leakage flow volume and the water level drop rate of the refueling water storage tank (RWST) in order to analyze the impact of branch pipe fracture on the water leakage of the RWST. According to the study results, there is very little deviation between the operating condition of the system as it actually is and the Flowmaster model, and the leakage volume following branch pipe fracture is considerably less than that of the RWST. Leakage volume per minute is around 0.025% of the RWST’s overall volume, which has negligible influence on the unit’s safety. Based on the results of the simulation, this study suggests LHSI system operation recommendations.
Research on Optimal Ratio of Wind-PV Capacity and Energy Storage Optimization Configuration of Regional Power Grid
Authors: Lv Xiaoxu , Wang Zhengfeng , Li Zhi , Shao Yijun , Zheng Cheng , Hao Lili
Published: February 2023

Reasonable optimization of the wind-photovoltaic-storage capacity ratio is the basis for efficiently utilizing new energy in the large-scale regional power grid. Firstly, a method of wind-photovoltaic capacity ratio optimization for improving new energy accommodation is proposed, including the evaluation model of new energy accommodation and the model of wind-photovoltaic capacity ratio optimization. An optimal allocation method of Energy Storage for improving new energy accommodation is proposed to reduce the power abandonment rate further. Finally, according to the above method, the optimal ratio of wind-photovoltaic capacity and the optimal allocation of energy storage in the target year of the regional power grid are studied. The results can provide a reference for the subsequent construction of wind and photovoltaic power plants and the region’s allocation of energy storage capacity.
Anti Interference Clock Error Correction Technology Based on BD3 System
Authors: Zhao Ruifeng , Li Shiming , Lu Jiangang , Xu Zhanqiang , Chen Zhiwei
Published: February 2023

Beidou-3 (BD3) uses the pseudo range transmission method to calculate the clock difference through the pseudo range. However, due to the influence of electromagnetic interference, the clock difference measurement error is too large, which affects the timing accuracy of the power system. This paper first introduces the principle of Beidou timing service; Secondly, it introduces the clock error calculation method; Finally, combined with the clock difference calculation method, this paper presents an anti-interference clock difference correction method based on Least Mean Square (LMS) filter. According to the principle of LMS filter, the influence of electromagnetic interference on pseudo distance can be eliminated, and the clock difference can be calculated. Then the clock difference can be corrected. The simulation results show that the method is feasible and effective.
Effects of polar molecules on direct current performance of EPDM for cable accessories
Authors: Li Zhongyuan , Chen Shiyu , Zhang Weichao , Guo Yuenan , Liu Heqian , Yang Hongda
Published: February 2023

Due to the excellent insulation performance, ethylene-propylene-diene monomer (EPDM) is used as cable accessories. To obtain EPDM materials with high dielectric breakdown strength (DBS), special polar molecules and chemistry grafting/crosslinking technique are used in this paper. In this paper, we choose Maleic anhydride (MAH) as an additive to introduce deep traps, which generates an increase in dielectric breakdown strength(DBS) and a decrease in conductivity. The result shows that MAH molecules can be grafted onto EPDM molecular chains in the process of cross-linking. Thermal stimulation currents (TSC) tests and the first-principles calculations consistently demonstrate that MAH can introduce deep charge traps, inhibiting migration of carriers, and increasing the DBS of EPDM. The grafting weight of MAH is small, which does not affect the process properties of the material.
Fast Computation Method of Energization Overvoltage in Cable Lines Based on Numerical Inverse Laplace Transform
Authors: Wang Hanfeng , Gu Borui , Zhu Guozhu , Lin Tao , Zhao Xuefeng , Duan Wei
Published: February 2023

Currently, the research on the energization overvoltage in cable lines is mainly realized through simulation calculation. However, the operation process is complex and the computation speed is slow when using the simulation software to calculate the energization overvoltage in the whole line. This paper presents a numerical calculation method of energization overvoltage in the entire cable line, which can greatly improve the calculation speed, simplify the operation process and have accurate calculation results. The method is based on transmission line theory, modal theory, transmission line equation’s complex frequency domain solution and Numerical Inverse Laplace Transform (NILT). This method first performs phase-to-mode conversion on the cable line and converts the mutually coupled cable conductors into mutually independent propagation modes. Furthermore, each independent propagation mode is conducted by Laplace Transform to obtain the complex frequency domain of its voltage. Finally, after the NILT is performed on the voltage complex frequency domain solution of each propagation mode and the time domain solution is obtained, the energization overvoltage of the full cable is obtained through the inverse phase-to-mode conversion. This method is applied to a 330kV cable line, and the calculation speed is significantly improved. The overvoltage calculation results have a small error compared to the obtained results using the simulation software, indicating that the method has high accuracy.
Design and application of double stove wires high-temperature furnace in high-temperature creep rupture test
Authors: Yang Leigang , Sun Jisong , Wang Weiguo
Published: February 2023

This paper presented a high-temperature furnace with double electric stove wires for the test of high-temperature creep rupture, adopted the 5 mm electric stove wire in diameter, and the wires are made up of the working stove wire and the alternate stove wire. When the tester system detects the working stove wire is fractured, it will automatically and quickly switch the power supply circuit from the working stove wire to the alternate stove wire. Then the alternate stove wire starts to heat to keep the high-temperature furnace working, reducing the loss caused by the interruption of the test on account of the fractured stove wire. Experimental result indicates that the high-temperature furnace with double electric stove wires can solve the problem that when the stove wire is fractured, the test is difficult to proceed for a long time and high-temperature creep rupture test with the classical high-temperature furnace. Besides, the 5 mm in diameter electric stove wire can also meet the temperature control on the ultra-high-temperature (such as 1200 °C) Creep test.
Micro-mechanism Analysis of Heat conductivity Enhancement of Argon-based Copper Nanofluids
Authors: Zhang Liang , Qu Pingping , Jing Yuyan , Yao Xinyue , Wang Wenjie
Published: February 2023

Enhancing heat transfer is the consistent goal in current industrial production. Nanofluids have greater advantages than traditional fluids.In this in the passage, MDS was used to research the mechanism of improving the heat conductivity of Cu-Ar nanofluids compared with conventional fluids. The effects of nanoparticles with various volume fractions (1% - 3%) and different sizes (r = 1.03 nm, 1.26 nm, 1.50 nm) on the heat conductivity of nanofluids were mainly discussed. The results showed that the insertion of Cu nanoparticles increased the heat conductivity of the base fluid in studied range. The heat conductivity of the nanofluid was proportional to the volume fraction of the nanoparticles, and the maximum increase was 29.1%. Inversely ratio to the particle size, the maximum increase was 15.3%. The microscopic mechanism of the systems was statistically analyzed by the radial distribution function. It was found that the addition of nanoparticles caused the change in the atomic arrangement of the nanofluids, which made the nanofluids exhibit a microstructure similar to that of the solid. This is why the heat transfer efficiency of nanofluids is higher.
Research on the Design of UAV Relay Charging High-rise Platform for Electrical Equipment Live Detection in Substation
Authors: Zhang Yanyan , Ning Xuefeng , Zhang Haipeng , Yang Youhang , Wang Shaorong
Published: February 2023

The multi-rotor UAV inspection technology has received extensive attention in the live detection of electrical equipment in substations and has begun to be practically applied. However, due to the short endurance and the characteristics of intermittent operations, the UAV needs to frequently travel between the operational airspace and the cabin, which seriously affects the operational efficiency of the inspection. This paper first introduces the traditional substation electrical equipment live detection technology and then summarizes the application of UAV inspection in the substation electrical equipment live detection. Finally, in view of the shortcomings of the existing technology, this paper proposes a design scheme of a relay-charging high-rise platform for live detection and inspection of electrical equipment in substations. The relay charging high-rise platform can be divided into six parts according to the functional structure: high-altitude apron, UAV landing guidance system, UAV automatic binding system, high insulation strength power supply system, and platform monitoring system. In this paper, the overall structure of the relay charging high-level platform and the technical solutions of each component are described in detail. The technical solution can effectively improve the efficiency and safety of multi-rotor UAV inspection operations for live detection of electrical equipment in substations.
Electrical equipment identification method in infrared images based on VGG
Authors: Li Yan , Du Jinqiao , Zhang Lin , Tian Jie , Yang Fan , Li Zhimin
Published: February 2023

Temperature is widely used to detect the state of electric equipment. Almost all the data is collected and sorted. And image analyzed by manual, which cause some trouble. In order to improve the intelligence level of power equipment detection, this paper proposes an infrared scene identification method for 220 kV current transformers, including target identification, temperature extraction, and image fusion. Firstly, a semantic segmentation model is built on VGG, which can effectively extract the target temperature information in complex environments. Then combined with the method of data set expansion, 3224 images of 220 kV current transformers were used for training. Finally, an image fusion method is used to extract equipment temperature. The experimental show that the method proposed in this paper for semantic segmentation and identification of 220 kV current transformers accuracy reaches 99.68%. In contrast, the traditional CNN identification method is 44%, effectively improving the target identification efficiency of 220 kV current transformers and has a good reference for electric equipment intelligence detection.
Economic dispatch for microgrids with communication delays and flexible load
Authors: He Ping , Dong Jie , Wu Xiaopeng
Published: February 2023

The consensus algorithm is widely used in the microgrid, but it is affected by the communication of distributed generators. If the communication delay is serious, it can affect the system’s performance and cause the system’s instability. To ensure the stability of the microgrid under communication constraints, aiming at the extensive penetration of the flexible loads in the microgrid, the transmission delay of the communication network is considered, this paper proposes a microgrid distributed economic dispatch method based on the consensus algorithm under communication constraints. By coordinating the information exchanges between the generator and the total load demand, the flexible load and output of the generator are optimized in the system. Compared with the traditional consensus control strategy, this strategy can ensure that the system has higher stability and convergence speed under the same delay. Finally, the IEEE-14 node system is used to verify the effectiveness and correctness of the proposed algorithm.
Low Carbon Operation Mode of Large High Power Consumption Venues Based on Big Data Mining Technology
Authors: Tang Dehai , Zhao Yueying , Zhang Wenbin , Xue Wenbin , Dou Haoping
Published: February 2023

Given the high power consumption rate of large venues with high power consumption, excessive carbon emissions, and severe environmental pollution, this paper proposes a low-carbon operation mode for large venues with high power consumption based on big data mining technology. The DEA model of high-power consumption venues is constructed by linear programming. Then the preliminary indicators of low-carbon operation mode are selected based on big data mining technology. Finally, the selected indicators are used to set up the operation system. Through experimental analysis, it is found that the low-carbon operation mode of large venues with high power consumption can reduce 2 million kg of carbon emissions on the basis of the initial value of carbon emissions. This mode can effectively reduce the carbon emissions of high-power consumption venues and play a great role in curbing environmental pollution and improving the social benefits of venues.
Power Source Optimal Configuration Method of New Energy Microgrid Based on Improved Particle Swarm Optimization
Authors: Feng Mingcan , Zheng Yuguang , Wan Zhiwei , Cui Kai , Sun Chongbo
Published: February 2023

The power source optimal allocation method is studied based on the improved particle swarm optimization in order to ensure the superiority and rationality of microgrid voltage optimal allocation. According to the weight coefficient optimization configuration objective function and constraint conditions, a microgrid voltage optimization configuration model is established. The inertia weight value in the particle swarm is optimized according to the optimal similarity. The distance scale and the fitting degree are combined. The power source optimization configuration is completed on the basis of increasing the improved particle swarm. The test results show that the average value of the load fluctuation is 4.279, and the average reduction is 7%, which improves the effectiveness and superiority of power source optimal allocation.
Research on Working Mode of Intelligent Terminal of Distribution Automation Based on Public Wireless Communication Network
Authors: Li Kewen , Chen Qianyi , Ou Shifeng , Chen Shaonan , Zhang Wei , Pan Jueming
Published: February 2023

Targeting the situation that the wireless communication terminal commonly exists in the pilot project of distribution automation has an unstable power supply under extreme conditions, this paper proposes a non-real-time online working mode that is different from the traditional real-time online working mode. The switching method of the two working modes was designed, and the comparison and analysis between the two working modes were performed in terms of the timeliness of event active reporting, communication flow, the impact on the processing mechanism of the master station system and the impact on the working duration of the power supply. The results show that the average power consumption of the wireless communication terminal under the non-real-time working mode is reduced from the watt level to the mill watt level, thus the power supply problem of the wireless communication terminal under extreme conditions is solved.
Trajectory planning for unmanned skid-steering vehicle
Authors: Meng Zhaoxia , Zeng Dequan , Hu Yiming , Leng Bo , Zhan Zhengkai , Shao Liang , Li Qiang , Luo Chagen , Sun Zhipeng
Published: February 2023

To make a trajectory enough to track unmanned skid-steering vehicles, a planning method is proposed in this paper. The planner consists of velocity planning, curvature planning, and path planning. Subject to the constraints of jerk and acceleration, velocity planning has five possibilities. Then taking curvature constraints into account, curvature planning has three possibilities. And according to the velocity sequence and curvature sequence, the path information of the trajectory can be obtained by the kinematic model. To verify the presented method, a simulation scenario is designed. The test result shows that the proposed method could generate a sufficiently smooth trajectory with satisfying all the constraints, including acceleration, jerk, and curvature.
Electric Vehicle Charging Scheduling Optimization Method Based on Improved Ant Colony
Authors: Cheng Nuo , She Lizhen , Chen Dacai
Published: February 2023

The influx of electric vehicles significantly impacts the power grid. In the process of power grid operation, the operation of charging and discharging of electric vehicles can be used to dispatch the load of power grid operation. The optimization method of charging and dispatching electric vehicles based on improved ant colony is studied. Pheromones generated during the charging of the electric vehicle are obtained, and the charging limit range of the battery is delimited. The dynamic window constructs the charging scheduling model improved ant colony algorithm, and the optimal charging path is selected to complete the scheduling method design. The experimental results show that the proposed method can adjust the charging and discharge in the period of valley price and peak price, play the role of peak clipping, and realize the load regulation in different periods, which has application value.