bluuebunny/crossref_metadata_2025 huggingface dataset:
Disturbance observer-based fuzzy fault-tolerant control for high-speed trains with multiple disturbances
Authors: Wang 王 Qian-Ling 千龄 , Ma 马 Cai-Qing 彩青 , Lin 林 Xue 雪
Published: June 2023

The fault-tolerant control problem is investigated for high-speed trains with actuator faults and multiple disturbances. Based on the novel train model resulting from the Takagi–Sugeno fuzzy theory, a sliding-mode fault-tolerant control strategy is proposed. The norm bounded disturbances which are composed of interactive forces among adjacent carriages and basis running resistances are rearranged by the fuzzy linearity technique. The modeled disturbances described as an exogenous system are compensated for by a disturbance observer. Moreover, a sliding mode surface is constructed, which can transform the stabilization problem of position and velocity into the stabilization problem of position errors and velocity errors, i.e., the tracking problem of position and velocity. Based on the parallel distributed compensation method and the disturbance observer, the fault-tolerant controller is solved. The Lyapunov theory is used to prove the stability of the closed-loop system. The feasibility and effectiveness of the proposed fault-tolerant control strategy are illustrated by simulation results.
Unveiling phonon frequency-dependent mechanism of heat transport across stacking fault in silicon carbide
Authors: Wang 王 Fu 甫 , Sun 孙 Yandong 彦东 , Zou 邹 Yu 宇 , Xu 徐 Ben 贲 , Fu 付 Baoqin 宝勤
Published: June 2023

Stacking faults (SFs) are often present in silicon carbide (SiC) and affect its thermal and heat-transport properties. However, it is unclear how SFs influence thermal transport. Using non-equilibrium molecular dynamics and lattice dynamics simulations, we studied phonon transport in SiC materials with an SF. Compared to perfect SiC materials, the SF can reduce thermal conductivity. This is caused by the additional interface thermal resistance (ITR) of SF, which is difficult to capture by the previous phenomenological models. By analyzing the spectral heat flux, we find that SF reduces the contribution of low-frequency (7.5 THz–12 THz) phonons to the heat flux, which can be attributed to SF reducing the phonon lifetime and group velocity, especially in the low-frequency range. The SF hinders phonon transport and results in an effective interface thermal resistance around the SF. Our results provide insight into the microscopic mechanism of the effect of defects on heat transport and have guiding significance for the regulation of the thermal conductivity of materials.
Improving physical properties of poly(vinyl alcohol)/montmorillonite nanocomposite hydrogels via the Hofmeister effect
Authors: Guo Rongrong , Yu Deshuai , Huang Yifan , Wang Sen , Fu Cong , Zhu Shuihong , Yi Jia , Wang Hanqi , Lin Youhui
Published: June 2023

Hydrogel is a kind of three-dimensional crosslinked polymer material with high moisture content. However, due to the network defects of polymer gels, traditional hydrogels are usually brittle and fragile, which limits their practical applications. Herein, we present a Hofmeister effect-aided facile strategy to prepare high-performance poly(vinyl alcohol)/montmorillonite nanocomposite hydrogels. Layered montmorillonite nanosheets can not only serve as crosslinking agents to enhance the mechanical properties of the hydrogel but also promote the ion conduction. More importantly, based on the Hofmeister effect, the presence of (NH4)2SO4 can endow nanocomposite hydrogels with excellent mechanical properties by affecting PVA chains' aggregation state and crystallinity. As a result, the as-prepared nanocomposite hydrogels possess unique physical properties, including robust mechanical and electrical properties. The as-prepared hydrogels can be further assembled into a high-performance flexible sensor, which can sensitively detect large-scale and small-scale human activities. The simple design concept of this work is believed to provide a new prospect for developing robust nanocomposite hydrogels and flexible devices in the future.
The Impact of Tidal Migration of Hot Jupiters on the Rotation of Sun-like Main-sequence Stars
Authors: Guo Shuai-Shuai
Published: June 2023

The tidal interactions of planets affect the stellar evolutionary status and the constraint of their physical parameters by gyrochronology. In this work, we incorporate the tidal interaction and magnetic braking of the stellar wind into MESA and calculate a large grid of 25,000 models, covering planets with masses of 0.1–13.0 M
J with different orbital distances that orbit late-type stars of different metallicities. We also explore the effect of different stellar initial rotations on the tidal interactions. Our results show that in the case of tidal inward migration, the stellar rotation periods are always lower than that of the star without planet before the planet is engulfed and the difference in the rotation period of its host star always increases with time. After the planet is engulfed, the stellar rotation periods are still lower than that of star without planet, but the difference of periods can be quickly eliminated if the star has a thick convective envelope (smaller mass and larger metallicity), regardless of the mass of the planet and the initial rotation period of the star. In the case of stars with thinner convective envelopes (larger mass and smaller metallicity), the stars will be spun up and remain the faster rotation in a long time. Meanwhile, the planet is easily swallowed and the period differences are large if the initial rotation period of its host star is higher. Finally, we also study the evolution of WASP-19 and estimate the range of tidal quality parameter

Q

*

′

=
(
4.6
±
0.9
)
×

10

6

and the initial semimajor axis as (0.035 ± 0.004) au.
Direct measurement of the electron turbulence-broadening edge transport barrier to facilitate core–edge integration in tokamak fusion plasmas
Authors: Wang H.Q. , Hong R. , Jian X. , Rhodes T.L. , Guo H.Y. , Leonard A.W. , Ma X. , Watkins J.G. , Ren J. , Grierson B.A. , Shafer M.W , Scotti F. , Osborne T.H. , Thomas D.M. , Yan Z.
Published: June 2023

The integration of a high-performance core and a dissipative divertor, or the so-called ‘core–edge integration,’ has been widely identified as a critical gap in the design of future fusion reactors. In this letter, we report, for the first time, direct experimental evidence of electron turbulence at the DIII-D H-mode pedestal that correlates with the broadening of the pedestal and thus facilitates core–edge integration. In agreement with gyrokinetic simulations, this electron turbulence is enhanced by high η
e (η
e = Ln
/LT

e, where Ln
is the density scale length and LT

e is the electron temperature scale length), which is due to a strong shift between the density and temperature pedestal profiles associated with a closed divertor. The modeled turbulence drives significant heat transport with a lower pressure gradient that may broaden the pedestal to a greater degree than the empirical and theoretically predicted pedestal width scalings. Such a wide pedestal, coupled with a closed divertor, enables us to achieve a good core–edge scenario that integrates a high-temperature low-collisionality pedestal (pedestal top temperature T
e,ped > 0.8 keV and a pedestal top collisionality ν*ped < 1) under detached divertor conditions. This paves a new path toward solving the core–edge integration issue in future fusion reactors.
Electromagnetic turbulence simulation of tokamak edge plasma dynamics and divertor heat load during thermal quench
Authors: Zhu Ben , Xu Xue-qiao , Tang Xian-Zhu
Published: June 2023

The edge plasma turbulence and transport dynamics, as well as the divertor power loads during the thermal-quench phase of tokamak disruptions, are numerically investigated with BOUT++’s flux-driven six-field electromagnetic turbulence model. Here, transient yet intense particle and energy sources are applied at the pedestal top to mimic the plasma power drive at the edge induced by a core thermal collapse, which flattens the core temperature profile. Interesting features, such as surging of divertor heat load (up to 50 times) and broadening of heat-flux width (up to four times) on the outer-divertor target plate, are observed in the simulation, in qualitative agreement with experimental observations. The dramatic changes in divertor heat load and width are due to the enhanced plasma turbulence activities inside the separatrix. Two cross-field transport mechanisms, namely, the E × B turbulent convection and the stochastic parallel advection/conduction, are identified to play important roles in this process. First, an elevated edge pressure gradient drives instabilities and subsequent turbulence in the entire pedestal region. The enhanced turbulence not only transports particles and energy radially across the separatrix via the E × B convection, which causes the initial divertor heat-load burst, but it also induces amplified magnetic fluctuation

B
˜

. Once themagnetic fluctuation is large enough to break the magnetic flux surface, magnetic flutter effect provides an additional radial transport channel. In the late stage of our simulation,

|

B
˜

r

/

B
0

|

reaches to 10−4 level that completely breaks magnetic flux surfaces such that stochastic field lines are directly connecting pedestal top plasma to the divertor target plates or first wall, further contributing to the divertor heat-flux width broadening.
Study on the Phosphogypsum Proportion in Foamed Concrete Based on Concrete Strength and Carbon Emission
Authors: Peng Longfan , Yang Baochun , Deng Jingwen , Xu Xiaoyang , Zhang Shilu
Published: June 2023

The production of concrete will produce a lot of carbon dioxide and pollute the environment. Phosphogypsum is a solid waste generated during wet phosphoric acid treatment, and the use of phosphogypsum blending instead of cement in concrete production can effectively reduce carbon dioxide emissions. Then, experiments were conducted for six concrete groups with different phosphogypsum content as 0%~50% to test the strength in 3 days, 7 days, and 28 days. The results show that as the curing day rise, the compressive strength of concrete increases, meanwhile, with the increment of phosphogypsum content, the 28-day strength decreases significantly. The analysis for the consideration of the balance in carbon emission and the strength evolved, and results could be concluded that although the decrement of 28-day strength as well as the carbon dioxide emissions with the increasing phosphogypsum content in concrete, different trends were found. As the strength and emissions vary, a suggested range of content for phosphogypsum in concrete can be found. Based on these results, the proportion of phosphogypsum in concrete is proposed to achieve the purpose of energy saving and emission reduction and improve the utilization rate of phosphogypsum.
Research on Water-saving, Moisture-keeping and Curing Technology of Cement Stabilized Base Course of Highway
Authors: Wang Jie , Wang Jiangjiao , Xu Yang , Wang Wenyuan
Published: June 2023

The cement stabilized macadam base has excellent road performance and economy, and it is widely used. However, cement stabilized macadam also has some shortcomings such as poor anti-scour ability and insufficient frost resistance. To solve this problem, this study uses Scanning Electron Microscope (SEM) to analyze the micro-morphology of the specimen surface under four curing methods, namely moisturizing film, sack, polyethylene film and curing room, explaining the mechanism of curing methods affecting the anti-scour performance of cement stabilized macadam. Through the experimental study of anti-scour performance, it was found that the water-saving and moisturizing film was the closest to the experimental condition of curing in the curing room; the scour rates of the specimens of health-preserving sacks and polyethylene films were both high, and they were respectively 12.1g and 16.7g at 15m; through the experimental study of frost resistance, it was found that these curing methods had little influence on the frost resistance of cement stabilized macadam, and the ratio of compressive strength exceeded 0.6%.
Thermal Elastohydronamic Lubrication Characteristics of Inclined Double-roller Enveloping Hourglass Worm Drive
Authors: Li Jinkuan , Wen Yujie , Liu Zaixin
Published: June 2023

To grasp thermal elastohydrodynamic lubrication (TEHL) characteristics of the conjugating tooth-pairs of inclined double-roller enveloping hourglass worm drive in transmission process. The numerical solutions of line contact thermal EHL were obtained based on meshing theory of this worm drive and the theory of EHL. The TEHL line contact numerical solution of this worm drive is solved by using the multigrid method, and the TEHL film pressure and thickness are got at the same time. The effects of roller radius, offset distance, orifice coefficient and inclined angler on the TEHL characteristics and temperature rise are analysed and compared. The results show that with the increase of roller radius, offset distance and inclined angler, the secondary pressure peak decreases and moves to the outlet region, and the oil film thickness decreases accordingly, with increase in orifice coefficient the second pressure peak rises and move toward the inlet, the film thickness increases. The maximum temperature rises of film, worm and worm gear contact surface reduce as the roller radius, orifice coefficient and inclined angler increase, rose as the offset distance increases. It can reduce temperature rise and improve the oil film thickness thought the optimization calculation in the design.
Research Status and Development Trend of Sintered Solid Waste-based Wall Insulation Materials
Authors: Zhao Liang , Yao Shuang , Nan Yunxi , Qin Linyuan , Yi Shanmei
Published: June 2023

Improving the thermal performance of the building envelope and reducing the energy consumption of heat transfer are particularly important for building energy conservation. Wall insulation materials can be divided into sintered and non-sintered two types. Sintered wall insulation materials have unique advantages in the development of self-insulating wall because of their high strength, good insulation ability and wide range of raw materials. In this paper, the research status of shale, fly ash, coal gangue and phosphogypsum as raw materials to develop wall insulation materials are introduced, feasible research direction in view of the significantly reduced thermal performance and durability of sintered self-insulating wall materials in high humidity environment and high sintering temperature are put forward. The research on the formation and control mechanism of high closed porosity structure and the action mechanism of multiple fluxes can provide theoretical support for the design and optimization of self-insulation wall materials with light, high strength, low sintering temperature and meeting the requirements of building energy conservation.
Study on the Vibration Displacement of Hydraulic Pipeline System Excited by Fluid Impact
Authors: Zhou Zhijin , Wen Duo , Liu Aijun
Published: June 2023

Hydraulic impact had an effect on pipeline vibration displacement, so it was important to study the external lateral impact periodic force on fluid-structure coupling vibration displacement of hydraulic pipeline. Based on Bernoulli beam model, the fluid-structure coupling vibration equation of flexible pipeline was established by analyzing the stress of flexible pipeline under the action of internal flow. The hydraulic system pipeline was simulated whether the pipeline was subject to periodic impact force. The displacement-time curves in x, y and z directions of vibration monitoring points of hydraulic flexible pipelines were obtained, and the maximum displacement-time curves of fluid-structure coupling vibration under different pressure hydraulic impact were obtained. The simulation results were shown that the vibration of monitoring points in x, y and z directions of hydraulic impact pressure increased and the total displacement of the pipeline middle section of the hydraulic system decrease continuously, and then they tend to stabilize after a period of attenuation. The maximum displacement value of the X-direction monitoring point in the middle part of the hydraulic system pipeline was 9.5e
−5
m, and the displacement vibration was stable at 0.135s. The maximum y-displacement was 3.1e
−4m, and the vibration was stable at 0.2 s. The maximum z displacement was 1.32e-4 m, and the vibration was stable at 0.36 s. The total displacement was 3.35e
−4
m, and the vibration was stable at 0.43s. Increasing the impact pressure, the maximum displacement of the hydraulic pipeline vibrations were larger, and the attenuation of the maximum values were faster. The research results provide a reference for the hydraulic system to prevent pressure shock and reduce vibration.
The Method for Selecting Analogous Reservoirs Based on SEC
Authors: Liu Zhaolong , Geng Meng , Zhang Yongzhong
Published: June 2023

To support remaining economic recoverable reserves and undeveloped reserves compliant with SEC rules, different types of recovery analogous reservoir sequences need to be established. Based on the SEC reserves estimation standards and the actual development characteristics of the oilfield, a classified and optimal evaluation method of analogous reservoirs, which can select a reasonable analogous reservoir fast, has been proposed. This method mainly includes 7 steps to select analogous reservoirs. With practical application in an oilfield, this method has obtained good effects. Selection results can cover all the typical reservoir blocks, and it provides a reliable basis for analogizing the target reservoir in the future. The method herein could provide a new method to select analogous reservoirs based on SEC, and it can be widely used in other oil fields.
Modelling of Photovoltaic Modules Based on Hybrid Artificial Bee Colony Algorithm
Authors: Li Xiaofeng
Published: June 2023

In recent decades, the application of photovoltaic (PV) power generation and other new energy begins to attract people’s attention. The modelling of PV modules is significant for accurately estimating the generation power and electrical characteristic of the PV modules or arrays under complicated outdoor conditions. In this paper, a hybrid ABC algorithm is proposed. The model parameters of PV modules can be identified. In the proposed algorithm, three kinds of bees are hybrid, and they can complement each other and change roles dynamically, which makes the performance of the algorithm better than other basic optimization algorithms. Experimental results verify that the proposed hybrid ABC can effectively identify the model parameters and achieves better modelling accuracy of the I-V characteristics.
Laboratory Investigation of Cryogenic Fracturing of HDR Wellbores Under Triaxial-Confining stresses
Authors: Yang Zheqi , Zhang Baosheng , Bi Jianfei
Published: June 2023

Hot dry rock (HDR) contains abundant thermal energy, which can be extracted through fracturing and used for electricity generation. Due to its deep depth, high temperature and high-pressure conditions, it is difficult to initiate fractures for conventional hydraulic fracturing technology. This paper studies the advantage of cryogenic fracturing on the HDR. We have carried out a series of laboratory experiments on granite samples with different lengths of the open hole under triaxial-confining stresses (10 MPa). The nitrogen fracturing wellbores of high temperature (100−300 °C) granites are processed by LN2 (liquid nitrogen) and NoLN2 (no liquid nitrogen) and retained with 20 mm and 30 mm open hole to form four control groups. The fracturing results showed that LN2 cryogenic stimulation is more effective in reducing the HDR initiation pressure. With a 20 mm open hole, the breakdown pressure of samples with LN2 decreases by 13.9%-18.7% compared with untreated samples. When the open hole changes from 20 mm to 30 mm, the breakdown pressure of samples with NoLN2 is reduced by 6.7%-15%. The longer the open hole of the samples is, the more complex the fracture patterns after the nitrogen fracturing are. This can be attributed to the length of the open hole. The longer it is, the more complex the micro-fractures on the surface are, and the force of the direction parallel to the cross-section is significantly increased. The results of our research afford Enhanced Geothermal Systems (EGS) basics and help the early realization of thermal power generation from HDR.
Comprehensive Recovery of Valuable Metals from Lead-zinc Tailings by Flotation
Authors: Gao Tengyue , Ji Qiang , Li Guangsheng , Zhu Xingfu
Published: June 2023

This study takes lead-zinc flotation tailings as the research object. The process of “tailings regrinding-lead-zinc mixed floatation-activation zinc separation” is used to comprehensively recover valuable metal elements from the original tailings. The results show that the grinding fineness is -74 μm under the condition that m accounts for 82%; the recovery rates of lead and zinc in the lead-zinc mixed concentrate obtained from the open-circuit test are 36.4% and 18.0%, respectively; the recovery rate of zinc in the coarse zinc concentrate is 57.6%; the valuable metal elements in the original tailings are effectively recovered.
Study on Overpressure Explosion of Oil and Gas Pipelines and Risk Prevention & Control Measures
Authors: Liu Yan , Chen Lin , Wang Xuting , Zhao Yaqi , Zhao Zhen , Zhang Chen , Xu Jinghan
Published: June 2023

In view of the flammable and explosive characteristics of oil and gas pipeline transportation medium, once it leaks, production safety accidents are easy to occur. This study uses explosions with severe consequences caused by natural gas pipeline leakage as an example. The risk factors and accident modes of oil and gas storage and transportation pipelines are analyzed; the explosion load is calculated by a scaling explosion prediction model with the TNO multi-energy method; the relationship between overpressure load and combustible gas cloud radius is studied. The methane-air explosion volume fraction of 9.5% is taken as another example, with which the overpressure attenuation law of explosion wave is obtained. Based on the above research, safety risk prevention and control measures are proposed. The research results can provide technical support for daily management and risk prevention and control of oil and gas storage and transportation pipelines.
Unit health state prediction based on VMD-TCN
Authors: Xie Jie-min , Huang Bo , Tian Hai-ping , Pan wei-feng , Mo jian , Zheng hui-juan
Published: June 2023

To address the problem that it is difficult to accurately predict the health status of hydropower units using real-time monitoring data, this paper proposes a method for predicting the health status trend of hydropower units based on variational modal decomposition (VMD) and time convolution network (TCN); considering the nonlinear factors of the trend series of hydropower unit vibration index, a time series prediction model based on VMD-TCN is established to achieve accurate prediction of unit health status. And multiple sets of comparison experiments are designed to verify the higher accuracy and faster time of the proposed model.
Study on Hydrate Control Measures in Deepwater Gas Wellbore under Intervention Operations
Authors: Zou Fabao , Zhang Haixiang , Gan Bicheng , Xuan Yinglong , He Jingang , Zhang Zhibo
Published: June 2023

Hydrate control research is of great significance to the efficient development of deepwater gas wells. A deepwater gas well intervention wellbore hydrate suppression experimental device was built to simulate the field intervention operation and monitor the hydrate generation in the kettle in real time. The physical simulation experiments were conducted for the injection concentration, injection volume, and injection rate of the glycol inhibitor for different working conditions of the intervention operation. The results show that the hydrate inhibition effect is good when the injection concentration of glycol solution is 40%, the hydrate plugging in the wellbore is slow when the injection volume is 20 mL, and the hydrate inhibition is effective when the injection rate is 4 mL/min. The injection of glycol inhibitor can effectively delay the time required for wellbore hydrate plugging and ensure the intervention operation. The above research results provide ideas for in-wellbore hydrate control in deepwater gas well intervention operations in the field.
Online Calibration Based on Laser-Encoder Odometry
Authors: Gao Bingshu , Yu Dongdong , Chen Gong , Lu Wei
Published: June 2023

This paper proposes a new online calibration method for the differential-drive mobile robot equipped with a laser scanner. Our algorithm can jointly estimate the 3-DoF extrinsic parameters of the laser scanner and the intrinsic parameters (radii and wheel spacing) of the differential-drive kinematic model. Applying the pre-integration theory initially developed the for IMU sensor to the differential-drive kinematic model, we adopt iterative nonlinear optimization to minimize the cost derived from laser and encoder measurements. Experiments results confirm that the proposed method can do online calibration precisely.
Fiber Raman Amplifier Based on Improved Whale Algorithm
Authors: Yao Jiajia , Deng Huaqiu
Published: June 2023

In this paper, an improved whale algorithm to optimize pump power and wavelengths of second-order fiber Raman amplifier (FRA) has been proposed. Adopted by the strategies of adaptive gradients and reverse learning, the normal whale algorithm is greatly improved. An optimized FRA is designed based on the six-wavelength backward pump structure. Compared by optimizing both wavelength and power with optimizing only power, the gain flatness curves of the two algorithms, the optimal combination scheme, and the corresponding noise characteristics are got. A 6-pumped FRA has been designed in which the error of on-off gain is 0.08% and the ripple is only 0.18dB.
Infrared image enhancement algorithm based on improved wavelet threshold function and weighted guided filtering
Authors: Yang Haitao , Tong Yaonan , Cao Zhiqi , Chen Zhenguang
Published: June 2023

Aiming at the problems such as the poor visual effect of infrared thermal imaging under low illumination conditions, an enhanced infrared image recognition method based on wavelet decomposition is proposed for this paper. First, according to wavelet decomposition, the infrared image is divided into a low-frequency sub-band (LFS) and high-frequency sub-band (HFS) in each orientation, and HFS in each orientation is denoised using a modified wavelet threshold function to strengthen the denoising effect of the infrared image; Second, the multi-scale Retinex (MSR) algorithm based on weighted guided filtering (WGIF) is used to evaluate the component of illumination in the basic layer of the LFS, and the WGIF-segmented detail layer images are fused with the MSR processed ones to effectively highlight the texture details of the LFS; Finally, the LFS and the HFS are wavelets reconstructed (WR) to obtain the infrared enhanced images. This paper applies the algorithm to a low-resolution (resolution 32x32 pixels) infrared thermal imaging module, and the results of combining subjective and objective evaluation indexes show that the overall property index of the algorithm in this paper is superior to other contrasting algorithms and can effectively improve the infrared image quality.
A Novel Wave-transparent and Decoupling Antenna in Broadband Dual-Polarized Dual-Band Shared-Aperture Array
Authors: Lan Zhe-Peng , Zhang Rui , Sun Bao-Hua
Published: June 2023

This letter proposes a novel wave-transparent and decoupling antenna in broadband dual-Polarized dual-Band shared-aperture array. It is implemented by kneading the double-arrow-stripe-shaped decoupling structure into the frequency-selective metasurface structure of the lower-frequency-band (LFB) antenna arms. The LFB antenna radiator can be considered as frequency-selective and array-decoupling metasurface for the higher-frequency-band (HFB) antennas placed below. The antenna system consists of 2 × 2 HFB (3.3-3.6 GHz)arrays and an LFB (1.65-2.58 GHz) antenna with wave-transparent and decoupled structure (WTDS). Then, without adding additional structure, the in-band isolations of co- and cross-polarized between HFB antennas are promoted to >25.6 dB and >25 dB only by relying on the antenna form of the LFB antenna itself.
A Four-cell Division Method for Pilot Sequence Design to Reduce Pilot Pollution in Massive MIMO systems
Authors: Wang Qiong , Xiang Mo , Miao Sha
Published: June 2023

A method for pilot sequence design with the Zadoff-Chu (ZC) sequence as a base sequence is proposed to address the problem of pilot pollution in massive multi-input multi-output (MIMO) systems. Instead of the odd-length ZC sequence currently in use, the ZC sequence of even length serves as the basis of the pilot. It has the advantage of a very small cross-correlation coefficient under the premise that the sum of cyclic displacement is odd. The results of the four-cell division method are compared between the even-length and odd-length ZC pilot sequences. The MATLAB simulation shows that the signal-to-noise ratio and the channel estimation mean square error of the designed even-length ZC pilot sequence are better than those of the existing odd-length ZC pilot sequence in the case of four-cell division.
Research on Transmission Efficiency Optimization of WPT System
Authors: Li Zhongkui , Rong Qingfeng
Published: June 2023

In this paper, a Buck converter is designed to make the transmission of WPT stable and not susceptible to load changes. This converter ensures the stability of the load end by changing the duty cycle, so that the WPT always works efficiently. The hardware structure design and program design of the converter are discussed in this paper, and the correctness of the design is verified by the simulation design of PSIM.
Self-healing and De-icing Functions of Graphene-carbon Nanotube Synergistic Reinforced Thermoplastic Polyurethane Composites Induced by Current
Authors: Wen Zhen , Luan Yunbo , Li Yongcun
Published: June 2023

The integration of structure and function is an important demand for new composite materials in high-technology areas like aerospace, automobile, rail transportation, etc. In this paper, the carbon nanotubes (CNTs) modified graphene (G) reinforced thermoplastic polyurethane (TPU) composites were prepared to improve the interfacial properties of graphene-polyurethane composites and enhance the functionality (self-healing, deicing) of the composites. Firstly, the G-CNT/TPU composites with graphene weight percentages of 1%, 3%, 5%, and 7% were prepared by the solution blending method. Then, the current-induced self-healing behaviors of the composites with prefabricated cracks were studied. Finally, the virgin composite and the healed composite films were tested in tension and the self-healing properties of the CNT-G/TPU composite films. Furthermore, the thermogenic effects of G-CNT/TPU composite with different contents of graphene under various voltages were studied, and the variation of voltage and temperature was obtained. The findings show that the surfaces of the composite films with a graphene content of 1 wt% show little change in temperature and do not have the current repair properties. With the increase in graphene content, the composite film gradually increases in temperature after passing the point and its repair effect also increases, and the repair efficiency of the G-CNT/TPU composite film with 7 wt% graphene content reaches 95%. It also achieves energization and de-icing functions based on its conductive properties. These studies will provide positive guidance for the functionalization of lightweight composites.
Design of the particle swarm optimization simulated annealing MPPT control method based on motion shadow
Authors: Lin Yan , Hou Zikun , Zhang Jianjun , Zhang Yue , Liang Donjian , Lu Wei , Liang Shufen
Published: June 2023

Under the same environmental conditions, photovoltaic arrays at different operating voltages will significantly affect the size of solar power. To obtain as much power as possible, the maximum power point tracking (MPPT) control method has been invented. Previous studies focused on the tracking problem under local shadow conditions, but the dynamic shadow problem with rapid changes in local shadow was rarely discussed. To solve the tracking problem that the maximum power point has multi-peak and fast-changing characteristics under this condition, this paper proposes a simulated annealing MPPT control method based on particle swarm optimization, which compensates the disadvantages of the memoryless Markov chain in the optimization algorithm by adaptive asymmetric memory factor, thus improving the local search ability and convergence speed in the later stage. The control effect is verified by modeling and simulation in Simulink of MATLAB, and the adaptability of the heuristic control method is reflected by simulating the tracking mode under the moving shadow condition through the actual hardware deployment on the moving car.
Defective WO3-x/N-C Composite as an Anode Material for Lithium-ion Batteries
Authors: Zhao Zhiwei , Ma Ying , Du Quanhui , Qiu Ming , Zhang Tianxing , Chen Zhihao , Ju Hao
Published: June 2023

Lithium-ion batteries, as an important power source, play significant roles in current daily life, while the performances highly depend on anode materials. Herein, defective WO3-x/N-C composites containing defective WO3-x nanowires and conductive N-C are successfully prepared via a two-step procedure. As shown in test results, the WO3-x/N-C composites demonstrate an encouraging capacity of 1004.3 mAhg−1 (0.1 Ag−1). After 150 cycles, a remarkable reversible capacity of 520 mAhg−1 can be retained. Furthermore, the WO3-x/N-C composites display a remarkable performance compared to WO3-x. The excellent reversible capacity and cycling stability of WO3-x/N-C composites are associated with the abundant oxygen vacancies in WO3-x/N-C nano-composites as well as the conducting carbon layer.
Energy Saving and Loss Reduction Measures Optimization for Distribution Networks
Authors: Liang Chen , Ma Xiping , Bao Chengjia , Dong Xiaoyang , Li Yaxin , Yang Junting , Xu Rui
Published: June 2023

High conversion rate energy plays an increasingly important role in the “double carbon” goal as well as the energy saving and emission reduction goals. The technology of loss reduction and energy saving has become the focus of modern power system construction. A technical line loss reduction technique is implemented in this work for feeders in the distribution network with abnormal losses in the technical circuit. Power flow calculations, analysis, and comparison are conducted using the Newton-Lafson method. Considering the best single investment benefit ratio measure under the same type of multi-measure loss reduction, the genetic mutation algorithm was used to sort the combination schemes, the efficient algorithm was used to solve the optimal scheme, and the multi-type measure solving model of the distribution network was established.
Research on Lightweight Authentication and Key Agreement Protocol in Power Grid Based on the SM9 Cryptographic Algorithm
Authors: Li Jiawei , He Chuan , Zhang Liang , Zhang Bo , Fang Yuan , Xi Zesheng , Wang Yunfan
Published: June 2023

With the wide application of power grids, the massive heterogeneous terminals become important data collection nodes and data relay nodes. However, the openness of the power system exposes the power grid to various security threats. Authentication key agreement protocol can provide authentication and session key sharing services and is the most important technical means to protect the communication security of power grids. However, the design of authentication key agreement protocols for power grids faces many challenges. Firstly, the members of the power grid change frequently, and each new member needs to be authenticated with the edge side equipment every time it joins, so the existing authentication scheme has a large computational overhead. Furthermore, the network communication bandwidth is limited, and the existing schemes have a high time overhead due to the number of communication interactions when performing terminal authentication with the edge side equipment. Finally, the existing schemes all use non-national secret algorithms, which cannot achieve autonomous control. This paper designs a lightweight power grid authentication key agreement protocol based on the state-secure SM9 algorithm to address the above technical challenges. Also, corresponding security proofs based on the threat model of power grids and the existing attack patterns are offered, and code implementation is carried out. It is experimentally verified that the computation time overhead and communication overhead of this scheme are smaller than those of the existing authentication key agreement protocols based on identification cryptosystems.
Health Condition Identification and Quantitative Assessment of Emergency Diesel Generator Sets Based on Back Propagation Neural Network and Mahalanobis Distance
Authors: Han Zhijun , Liu Chaozhang , Xu Yonggang , Sui Can , Gong Zichao , Han Hong
Published: June 2023

To address the problem of a comprehensive assessment of emergency diesel generator set health status, a quantitative assessment method of emergency diesel generator set health status based on data-driven and distance measurement is proposed. BP neural network was used to extract the feature sequences of emergency diesel generator sets under different health states. An emergency diesel generator set health state identification model was established. To further quantitatively evaluate the health level of the emergency diesel generator set, the distance between each state of the emergency diesel generator set and the health state is measured by introducing the Mahalanobis distance algorithm, which realizes the unification of both qualitative and quantitative evaluation of the health state of the emergency diesel generator set. The operating states of diesel generator sets were subdivided into four states: healthy, sub-healthy, abnormal, and fault, and a simulation test study was conducted using the actual measurement data set of emergency diesel generator set operation. It is verified that the proposed method can classify the operating status of diesel generator sets more accurately and obtain the health assessment score index. The integration of qualitative and quantitative assessment of the health status of emergency diesel generator sets is realized, and the status warning is carried out accordingly, which provides an accurate basis for taking different maintenance and repair measures in a targeted manner.
A method to simulate Twin Frisch-grid ionization chamber response to fission fragments
Authors: Liu Changqi , Tao Kai , Peng Ruiying , Hu Zhiming , Huang Liming , E Dejun , Guo Zhiqi , Bai Xiaohou , Ma Zhanwen
Published: June 2023

In this study, the response of a Twin Frisch-grid ionization
chamber (TFGIC) to fission fragments (FFs) was investigated using
finite element and Monte Carlo methods. The entire process of the
fission experiments, including FFs generation, gas ionization,
electron drift and collection, and induced charge signal were well
reproduced. Through data analysis, pulse height spectra from the
anode and grid were transformed into energy and emission-angle
information for the FFs. By means of double energy method, the
pre-neutron emission fission fragment mass and total kinetic energy
(TKE) can be finally determined. Experimental and calculated
data of the mass and TKE distribution are shown in good
agreement.
Study of the mechanism of ultrasound-induced enhanced therapeutic effects of a chitosan-based nanoplatform
Authors: Zhang Peixia , Zhu Fangyin , Long Haixin , Wang Jun , Zhu Lisheng , Chen Haijun , Gao Yu
Published: June 2023

Ultrasound (US) has been used in drug delivery systems for controlling drug release and activation of US-sensitive drugs for sonodynamic therapy of cancer. In our previous work, we found that erlotinib-grafted chitosan nanocomplexes loading perfluorooctyl bromide and hematoporphyrin under US irradiation showed satisfactory therapeutic effects for non-small cell lung cancer treatment. However, the underlying mechanism of US-mediated delivery and therapy has not been fully explored. In this work, the underlying mechanisms of the US-induced effects of the nanocomplexes were evaluated at the physical and biological levels after the chitosan-based nanocomplexes were characterized. The results showed that US could activate the cavitation effects and promote nanocomplexes penetrating into the depth of three-dimensional multicellular tumor spheroids (3D MCTSs) when nanocomplexes were selectively uptaken by targeted cancer cells, but push the extracellular nanocomplexes out of the 3D MCTSs. US demonstrated strong tissue penetration ability to effectively induce obvious reactive oxygen species production deep inside the 3D MCTSs. Under the US condition of 0.1 W cm−2 for 1 min, US caused little mechanical damage and weak thermal effect to avoid severe cell necrosis, whereas cell apoptosis could be induced by collapse of mitochondrial membrane potential and the nucleus damage. The present study indicates that US can potentially be used jointly with nanomedicine to improve targeted drug delivery and combination therapy of deep-seated tumors.
Extraction of Zinc from Zinc Sublimber with Sulfuric, Thermal and Extraction Phosphoric Acid
Authors: Ramazonova Dilbar , Turaev Zokirjon , Mamurov Bakhodir , Usmanov Ilkham , Qodirov Sherzod , Makhmayorov Jasur , Samadiy Murodjon
Published: June 2023

The study was conducted to extract zinc and the results on the extraction of Zn from zinc sublime with the solution of sulfuric, thermal and extraction phosphoric acids are presented depending on Solid: Liquid (S:L), concentration and duration of the leaching process. Sulfuric acid was used with a content of 8% which is a waste product of non-ferrous metallurgy, thermal phosphoric extraction phosphoric acid from phosphorites of the Central Kyzylkum. It has been established that the maximum degree of zinc extraction is noted when using extraction phosphoric acid, which is 96-98%, S:L=1:(10-15), with the temperature of 90°C and washing sulfuric acid, which is 99.8% at S:L=1:10 and above at room temperature. Increasing the duration of the process over 30 minutes has virtually no effect on the extraction percentage of zinc.
Influence of topography on electrical contact resistance of copper-based materials
Authors: Alderete Bruno , Nayak U Pranav , Mücklich Frank , Suarez Sebastian
Published: June 2023

The design of an electrical contact is crucial to ensure optimal performance, reliability, and efficiency of connectors. One key aspect is the surface quality of the contacting bodies—among other factors such as material selection, contact geometry, etc. In this work, we evaluated the influence on electrical contact resistance (ECR) of a smooth copper-based surface (brass, bronze, and tin-plated copper) when contacted against surfaces with different degrees of roughness. Furthermore, a carbon nanotube (CNT) coating was proposed with the goal of mitigating the topography-induced influence of the textured counter electrodes. The electrodes and counter electrodes were thoroughly characterized to understand the contacting mechanisms through numerical modeling,—namely, Greenwood-Williamson and Jackson-Green models—as well as using a practical-oriented slope analysis. Load-dependent ECR measurements were carried out to quantify the effect of roughness on contact resistance. When contacting against brass and bronze, a clear correlation between roughness and ECR can be established, with higher roughness equating to lower ECR In tin-plated copper, on the other hand, this hierarchy is not as well defined due to the ease with which the tin plating deforms, thus enabling the penetration of outstanding asperities and consequently establishing a better electrical contact. CNT-coated counter electrodes showed promising results, partially confirming the hypothesis proposed. However, unforeseen topography-related interactions with the CNT coating produced exceptions in the ECR measurements. Nonetheless, for most cases studied the coating did mitigate the influence of roughness.
Dot-product computation and logistic regression with 2D hexagonal-boron nitride (h-BN) memristor arrays
Authors: Afshari Sahra , Radhakrishnan Sritharini , Xie Jing , Musisi-Nkambwe Mirembe , Meng Jian , He Wangxin , Seo Jae-sun , Sanchez Esqueda Ivan
Published: June 2023

This work reports on the hardware implementation of analog dot-product operation on arrays of two-dimensional (2D) hexagonal boron nitride (h-BN) memristors. This extends beyond previous work that studied isolated device characteristics towards the application of analog neural network accelerators based on 2D memristor arrays. The wafer-level fabrication of the memristor arrays is enabled by large-area transfer of CVD-grown few-layer (8 layers) h-BN films. Individual devices achieve an on/off ratio of >10, low voltage operation (∼0.5 V
set/V
reset), good endurance (>6000 programming steps), and good retention (>104 s). The dot-product operation shows excellent linearity and repeatability, with low read energy consumption (∼200 aJ to 20 fJ per operation), with minimal error and deviation over various measurement cycles. Moreover, we present the implementation of a stochastic logistic regression algorithm in 2D h-BN memristor hardware for the classification of noisy images. The promising resistive switching characteristics, performance of dot-product computation, and successful demonstration of logistic regression in h-BN memristors signify an important step towards the integration of 2D materials for next-generation neuromorphic computing systems.
Effects of electrospun membrane surface morphology on cellular behaviours and osteogenesis of bone marrow mesenchymal stem cells
Authors: Chen Yongcheng , Long Shengyu , Liu Zhui , Wang Wentong , Yuan Ping , Yang Zongwan , Yang Zisheng , Shi Yajie , He Fei
Published: June 2023

Electrospun membranes are widely used in bone tissue engineering because of their similar bone extracellular matrix. The morphological characteristics of electrospun membranes, which include fibre diameter and alignment, play crucial roles in determining cellular behaviour and osteogenesis. Therefore, to investigate the effects of these two parameters on bone marrow mesenchymal stem cells (BMSCs), we prepared electrospun poly-L-lactic acid membranes using different diameters (nanoscale and microscale) and alignments (aligned and random) to investigate the effects of different surface morphologies on the proliferation, adhesion, migration, cell morphology, and osteogenesis of BMSCs. Our results showed that electrospun membranes with different surface morphologies have good biocompatibility and can regulate cell morphology, and the parallel aligned fibre orientation can promote cell migration. More importantly, BMSCs cultured on aligned nanofibres have a higher osteogenic potential than aligned microfibres and random fibres. Furthermore, our study shows that the surface morphology of electrospun membranes, which is one of the characteristics of biomaterials, can regulate the cellular behaviour of BMSCs, and that aligned nanofibre electrospun membranes can contribute to promoting osteogenesis, which can be used as the surface morphology of bone repair materials.