bluuebunny/crossref_metadata_2025 huggingface dataset:
Particle distribution and two-phase flow characteristics of twin-screw pump during solid-liquid transfer
Authors: Wang Zhenhao , Sun Shuaihui , Wu Pengbo
Published: March 2024

The twin-screw pump is a kind of positive displacement machinery with smooth pressure and flow pulsation and strong self-priming ability, which is widely used in the fields of oilfield production, marine engineering, and other fields. However, in the process of conveying liquid-phase media, it is difficult to avoid the inclusion of solid impurities and grit, resulting in wear of the pump casing and rotor, and the pump’s pressurization capacity is reduced or even shut down. At present, the solid-liquid two-phase flow characteristics within the twin-screw pump have not been clarified, which hinders the study of particle wear in the pump. In this paper, a solid-liquid two-phase flow study is carried out on a twin-screw pump through numerical simulation and experimental testing. The distribution of particles with different diameters in the rotor domain with the liquid-phase transport process is explored by simulating the two-phase flow under different differential pressures and particle concentrations. The results show that the particles in the rotor domain are mainly distributed in the region away from the male and female rotor engagement, and the number of particles near the engagement is small but the velocity is higher under the influence of the clearance jets; the elevation of the differential pressure and the particle concentration increase the risk of the particles to collide with the rotor more frequently and at higher velocity; at different particle concentrations, new localized vortices are caused by particle conveying which compared to pure liquid transport, but there are also cases where the original vortices are suppressed. The results will provide a theoretical basis for further research on particle wear characteristics in twin-screw pumps.
Numerical investigation the shape of groove on tip leakage vortex suppression of a NACA0009 hydrofoil
Authors: Wang L K , Mi J Z , Luo X Q , Yao L , Feng J J , Zhu G J , Li C H
Published: March 2024

To investigate the effect of different bionic grooves on the tip leakage vortex, four bionic grooves with different shapes were designed, which are semicircular, rectangular, triangular and trapezoid. The streamline, pressure, vortex strength and turbulence kinetic energy were analyzed to clarify the suppression mechanism. When the groove is arranged, the velocity of vortex center and the area of high-intensity vortex area decrease. The vortex strength in the triangular groove is higher than other groove shapes. The pressure in the center of the tip leakage vortex core increases. The low pressure area reduces obviously, which is the smallest in the trapezoidal groove condition. The turbulent kinetic energy in the main flow field increases, but decreases in the tip clearance. The high turbulent kinetic energy region is divided into small pieces by the bionic groove, which is the smallest in the rectangular groove condition. The bionic groove leads to the decrease in lift-to-drag ratio, which is the largest in the semicircular groove and smallest in the rectangular groove condition.
Study of the effects of modified draft tube with inclined conical diffuser on draft tube and upstream region
Authors: Zhou Xing , Huang Quanshui , Hu Xinyi , Dai Xiangyu
Published: March 2024

Various countermeasures including geometry optimization have been proposed and proved to have a huge impact on flow filed within the draft tube in order to mitigate the vortex rope and the induced pressure fluctuations for Francis turbine under part load operation. However, the effect of these approaches on the hydro-dynamics in upstream region still remains unclear, which is of great significance for the overall performance of the unit. This study aims to explore the influences of modified draft tube with inclined conical diffuser on the pressure fluctuations in whole flow passage. The results reveal that Generation-1 and Generation-2 draft tubes are effective in alleviating pressure fluctuations resided in the draft tube, but the former one would trigger a low-frequency pressure fluctuation with higher amplitude in the runner zone. In addition, the modified draft tube has a very limited effect on the high-frequency pressure fluctuations in the guide vane and vaneless areas. To eliminate the adverse effect of inclined conical diffuser, a design with a transitional section is put forward to smoothly connect the runner zone and inclined conical diffuser. This further developed Generation-2 draft tube presents a reasonably good performance in terms of improving flow stabilities, i.e. alleviating the pressure fluctuations not only in draft tube but also in upstream region such as runner zone. This study provides reference for obtaining a better mitigating effect on pressure fluctuations in the whole turbine flow passage.
Research on the influence of needle roughness of Pelton turbine on flow characteristics
Authors: Meng Han , Zhang Jing , Ge Xinfeng , Huang Jinwei
Published: March 2024

The needle in the jetting mechanism of Pelton turbine may be uneven on the surface of the needle due to the knife marks in the cutting process or the erosion of the sediment in the water flow, resulting in the surface roughness of the needle, which affects the flow at the wall. In order to study the influence of the surface roughness of the needle on the jet flow characteristics, the jet flow characteristics and sediment characteristics of the jetting mechanism under different roughnesses were analyzed in this paper. The results show that the flow characteristics of the smooth wall and the rough wall are obviously contrasted. With the increase of the needle roughness, the jet velocity of the jetting mechanism gradually decreases, the turbulent kinetic energy of the needle surface gradually increases, the shear stress on the needle surface gradually increases, the wear amount gradually increases, the wear area increases, and the efficiency of the jet mechanism with a 1mm roughness wall decreases by about 22.3% compared with the smooth wall.
Performance improvements of vertical axis wind turbines with modified gurney flaps
Authors: Yang P , Chen L , Zhang B X , He C C
Published: March 2024

Plain Gurney flap (PGF), as a passive flow control method, is widely used to improve the aerodynamic performance. Due to the drag penalty, a novel serrated Gurney flap (SGF) is proposed. The numerical simulation is carried out to investigate the effects of GFs on the aerodynamic performance of the NACA0018 airfoil and an associated two-blade rotor of a H-type Vertical Axis Wind Turbine (VAWT). The height of GF ranges from 1.5% to 6% of the airfoil chord length. The results show that the SGF doesn’t exhibit the same lift enhancement as PGF, but lower drag. When the flap height reaches 6% c, the SGF airfoil has the higher lift-to-drag ratio. The 3%-chord-length height of GFs is employed on the rotor and it implies that both PGF and SGF can enhance the output power of VAWT. SGF has superior performance than GF, especially at the TSR>2.5 conditions. At the optimal TSR=3.0, the output power of SGF turbine is 2.7% higher than that of PGF one. The highest improvement of power can reach 13.3% at TSR=4.0.
Experimental study on restraining outflow distortion of a waterjet inlet using vortex generator jets
Authors: Zhou J M , Wang Z J , Chen L , Ma X Q , Dai R
Published: March 2024

The internal flow of the flush-type waterjet intake duct is simulated through an experiment in a low speed wind tunnel. The distributions of static pressure along the intake duct wall and the total pressure in the pump face plane are measured to investigate the influence of the vortex generator jet (VGJ) on the outflow behavior. Test cases were screened by Taguchi method. Experiment results verify a pair of VG jets with a blowing ratio 2 and lateral spacing 4 has the best performance. The inlet’s outflow is improved that total pressure recovery coefficient is raised from 0.712 to 0.771 and uniformity coefficient of axial velocity component from 0.652 to 0.824. The distortion coefficient of total pressure is reduced from 0.381 to 0.177. Vortex generator jet is a promising active flow control for waterjet application.
The research of multi-dimensional flow mapping for proportional flow control valve based on long short-term memory network
Authors: Xu Yue , Yang Gang , Li Baoren
Published: March 2024

The multidimensional flow mapping illustrates the numerical correlation between the flow rate and three pertinent factors, namely spool displacement, valve port pressure difference, and oil temperature. This representation signifies a mapping of three-dimensional inputs to a one-dimensional output. Accurate mapping relationship lays solid foundation for the feasible flow control of the flow control proportional valve. Since the proportional flow control valve is a complex system with high nonlinearity, it is challenging to treat the flow mapping relationship as a simple parameter estimation problem. In this regard, this paper combines the relevant theories of signal processing and deep learning (DL) to propose a novel four-dimensional input-output mapping relationship learning method. This method adopts the long short-term memory (LSTM) network to model the multi-dimensional flow mapping relationship. And for better quality of the data, the initial measurement datasets, contaminated by environmental factors, are processed using a finite impulse response (FIR) filter to reduce noise before training the data. Moreover, the trained model is validated on test datasets. The experimental results shows that the mentioned method can accurately estimate the multidimensional mapping relationship of the proportional flow control valve.
Optimal scheduling for wind-solar-hydro hybrid generation system with cascade hydropower considering regulation energy storage requirements
Authors: Liu Yuanyuan , Guo Pengcheng , Zhang Hao
Published: March 2024

Large-scale integration of renewable energy into the grid can lead to significant changes in the net load, peak-to-valley difference, peak and valley occurrence time of the power system. As a result, the power of hydropower plants must take a rapid adjustment response. Aiming at the coordinated operation of multiple energy sources, such as wind power, solar power, cascade hydropower station and energy storage pumping station, a coordinated scheduling model is proposed which can fully improve the consumption capacity of wind and solar power by aiming at the maximum power generation, minimum net load fluctuation and minimum wind and solar abandonment. Through the configuration of three different pumping station capacities, the influence of energy storage pumping station capacity on the complementary power generation system is analyzed. When the pumping station capacity is large enough, the output of the wind and solar can be completely consumed. The studies show that the cascade power station and pump energy storage regulation have a strong net load filling valley effect, which can effectively reduce the impact of wind and solar access on system operation, maintain the efficient and stable operation of the unit, and ensure the absorption rate of renewable energy.
Analysis of the flow field of kerosene-fueled rotating detonation engine with film cooling
Authors: Li Jingzhe , Yu Jingtian , Li Jianghong , Lei Ying , Yao Songbai , Zhang Wenwu
Published: March 2024

The advance of the rotating detonation engine (RDE) toward practical applications demands the integration of effective cooling schemes. In this study, a three-dimensional simulation of the hydrogen-enhanced kerosene-air RDE with inclined cylindrical film cooling holes is conducted to analyze the influence of the cooling flow on the two-phase rotating detonation flow field based an Eulerian–Lagrangian model. The liquid kerosene is injected at the ambient temperature with hydrogen-assisted combustion enhancement. Results suggest that a stable propagation of the kerosene-fueled rotating detonation wave can be maintained after the introduction of cooling air and the three-dimensional structure of the flow field is analyzed. It is found that the periodic sweeping action of the detonation wave leads to temporary blockages of the film cooling holes, causing interruptions in the outflow of cooling air. Additionally, the investigation highlights the intensified heating and evaporation of kerosene droplets near the outer wall of the RDE, whereas the presence of cooling air prevents the accumulation of kerosene vapor near the outer wall. It is revealed that the film cooling efficiency exhibits a lower value in the vicinity of the fuel injection surface, but gradually increases along the length of the combustion chamber.
Multi-scale mechanical-thermal coupling analysis of multi-layer thermal protection structure of ceramic matrix composites
Authors: Xuan Liang , Yuanhong Wang , Tu Zecan , Jia Yang , Junkui Mao
Published: March 2024

The wall of combustion chamber needs to sustain the extremely high thermal and stress load in the engine environment, so the thermal protection structure is required to ensure its safe work. At present, the multi-layer thermal protection structure with ceramic matrix composite (CMC) materials has gradually been applied as the internal resistant layer, due to its high specific strength and high temperature resistance. The mechanical-thermal coupling analysis method for CMC multi-layer thermal protection structures needs to be established, considering the complex distributed thermal and stress loads inside the combustion chambers. Firstly, for the local periodic unit of multilayer thermal protection structure, the mesoscale braided structure model and the homogenized model are constructed respectively, to explore the influence of the braided structure inside CMC layer on the temperature and stress distribution. Then, the macroscale model of the multi-layer CMC thermal protection structure is established, based on the feasibility of the local periodic element model verification method. The mechanical-thermal coupling analysis of the overall multi-layer thermal protection structure is carried out, and the temperature distribution and structural deformation are explored.
Research on the effect of fretting wear on the vibration characteristics of the tenon joint bladed disk
Authors: Qu Zhen , Yao Can , Zhu Honglai , Lin Xingrong , Chen Lei , Zhang Zhanhai , Fang Jie
Published: March 2024

The tenon joint structure is a typical structure of aero-engine bladed disk. Under external excitation, micro-slip inevitably occurs between the tenon and the tenon groove of the blade, which will cause fretting wear on the contact surface. The resonance frequency and margin of the bladed disk structure will change after fretting wear occurs. In this paper, a finite element subprogram is compiled based on the basic principle of Archard wear, which realizes the generation of surface wear morphology and multi-step iterative update of the double-tooth fir-tree joint model under fretting load. The subroutine is used to quantitatively analyze the wear depth distribution of the tenon joint surface under fretting loads. On this basis, the resonance margin and the vibration response characteristics of the bladed disk are quantitatively studied after fretting wear. The research results show that the natural vibration frequency of the bladed disk structure decreases at different wear times. This caused a decrease in the resonance margin of more than 80% of the measuring points. In addition, the resonance response amplitudes all showed an upward trend with the increase of wear depth.
Experimental study on multi-condition of axial flow pump in the whole flow field based on piv test
Authors: Zhu Hualun , Feng Chao , Wang Zonglong
Published: March 2024

To study the internal flow characteristics of the axial flow pump in the whole flow field under different flow conditions, particle image velocimetry technology was used to measure the steady and unsteady flow fields of the axial flow pump, analyzed the velocity field distribution at the impeller inlet, impeller inner, guide vane inner, and guide vane outlet of the pump under different flow conditions (Q/Q
des=0.8, 1, 1.1). Through the test and data analysis: under the three flow conditions, the velocity distribution trend of the impeller inlet of the axial flow pump is consistent and basically along the axis direction; there is a large velocity gradient in the flow field inside the impeller, and there is a significant acceleration near the hub trend, and there is a high-speed concentrated area; the velocity distribution trend in the guide vane is basically the same, and the fluid velocity changes more uniformly at the rated flow rate, and the flow tends to be more stable; a local high-speed area appears at the outer edge of the guide vane outlet, but in the second half The flow velocity in the pipeline is relatively uniform. The test results can provide a reference for the internal flow characteristics and performance optimization design of the axial flow pump.
Numerical study of jet-plate interaction and its effects on aeroacoustics
Authors: Wang Xindi , Lai Huanxin
Published: March 2024

In modern under-wing-mounted high-bypass engines, the exhausted jet from the engine will interact strongly with the wing and high-lift devices. In this paper, simulations of an isothermal jet flow at Mach number Ma = 0.5 and close to a flat plate are carried out using large-eddy simulation. Far-field acoustic results are obtained via the surface integral method of Ffowcs Williams and Hawkings (FW-H). The studied cases include an isolated jet and other three configurations with the jet and a plate spaced at the distance H/D
j = 1.0, 1.5, and 2.0, respectively, from the jet axis. Validation against experimental data is carried out. Far-field acoustic results show that the overall noise levels are significantly increased for the installed cases, particularly for polar angles in upstream of the nozzle. The noise levels are increased more as the plate approaches the jet axis, indicating the installation effect is related to the H/D and the polar angle. The pressure fluctuations are shown to decay along the radial direction. The mean flow and power spectral density of the axial velocity show the characteristics of the jet flow is not significantly changed by the presence of the plate.
Numerical study on aerodynamic performance and noise of protrusions structures near the trailing edge
Authors: Wang R , Xie J L
Published: March 2024

Based on the NACA0012 airfoil, different types of protrusions namely serrated protrusions and arc-shaped protrusions are set near the trailing edge. Both new airfoils have a certain decrease in flow performance however there is a significant reduction in aerodynamic noise of airfoils. This is because the protrusions damage the vortex near the trailing edge. In addition, the noise reduction of serrated protrusions is more significant than t of arc-shaped protrusions, about 2.7dB.
PIV measurement of cavitating flow around a pitching hydrofoil
Authors: Zhang Mengjie , Chen Jie , Xu Zhongyi , Ruan Xinjian , Huang Biao
Published: March 2024

Particle Image Velocimetry (PIV) and hydrodynamic measurements were applied to investigate the cavitating flow of a pitching hydrofoil in the form of triangular wave motion (mean incidence α
0=10°, amplitude Δα=5° and pitching frequency f*=2Hz). The Reynolds number is Re=4.5×105. The cavitation number is set to σ=2.3, 1.36. Different typical cavity patterns are observed by PIV images in the whole pitching period, including sub cavitation, inception cavitation, sheet cavitation and cloud cavitation. As the σ decreases, the cavity area increases. And the the corresponding time and position of cavitation patterns also changed significantly. In the instantaneous velocity field of an oscillating hydrofoil, the low velocity zone (LVZ) and the mainstream zone (MZ) are observed. The LVZ corresponds to the cavitation region and changes with the change of cavitation morphology. Meanwhile, the LVZ has a large velocity gradient. The velocity gradient in the MZ is larger along the direction parallel to the incoming flow, and the velocity tends to increase first and then decrease gradually downstream. With the decrease of cavitation number, the area of LVZ increases. And the distribution of LVZ is more uneven, which is mainly caused by oscillation motion and uneven water vapor mixing.
Application of three cavitation models in centrifugal pump cavitation flow simulation
Authors: Xie H , Luo X Q , Feng J J , Zhu G J , Li C H
Published: March 2024

In order to solve the problems of difficult and inaccurate cavitation simulation in centrifugal pumps, this paper adopts the commercial software CFX and realizes the same-platform comparison of Zwart-Gerber-Belamri model, Kunz model and Schner-Saer model in the simulation of centrifugal pumps’ cavitation by using its own language. The research results show that the Schner-Saer model can predict the external characteristics of the pump more accurately without considering the coefficient correction; By adjusting the empirical coefficients, different cavitation models can achieve the same effect; The Kunz model can predict the pressure distribution in the impeller more accurately, and the error is basically kept within 10% except for the local complex flow area; The change of the pump head is more obviously affected by the volume of the vapour in impeller, but weakly affected by the morphology of the vapour.
CFD verification of total pressure loss coefficient for gas-liquid two-phase flow
Authors: Kawahara T , Feng C N , Miyagawa K , Katayama Y
Published: March 2024

Traditionally, we design gas-liquid two-phase flow systems with pressure loss that is assumed by homogeneous flow. However, in real phenomena, the flow rate of water or air through a system cannot be correctly predicted unless we evaluate by the total pressure loss. there are currently few methods for measuring total pressure loss, and the value of total pressure loss is not yet clearly. Therefore, we devised a method to measure total pressure loss by pump Q-H characteristic and succeeded in measuring total pressure loss indirectly. We compared the test results with the analysis to clarify the prediction accuracy of the analysis using commercial codes. We apply three two-phase flow models for the simulation: a VOF model, a homogeneous flow model, and a two-fluid model. The simulation results of comparison between each fluid model indicated that the VOF model predicted with the best accuracy, with the error of 46% compared to the test results. This study provides a benchmark for the current commercial code, and the prediction accuracy of the different models provides a direction for future improvements in the analysis.
Synthesis and performance of a new long-acting slump retention agent at different temperatures
Authors: Lin Xiaochen
Published: March 2024

Under high-temperature conditions, the fluidity retention properties of polycarboxylate superplasticizers remain a challenge. This study improved the molecular structure of traditional slow-release polycarboxylate superplasticizers (also known as slump-retention agents) by introducing hydroxypropyl acrylate, successfully synthesizing a novel slump-retention agent that maintains concrete slump for an extended period at high temperatures. Comparing its performance with two other conventionally synthesized slump-retention agents, the superior performance of the new agent was verified. We then delved into the behavior of this novel slump-retention agent under different temperature conditions.
Acoustic properties of underwater acoustic metamaterials based on multi-physical field coupling model
Authors: Dong Kaiyuan , Lv Yiwen , Wang Peng , Cheng Wei , Li Han
Published: March 2024

In this paper, according to the internal structure of underwater acoustic metamaterial, a multi-physical field coupling model of underwater acoustic metamaterial is established by using finite element analysis. Based on the model, the influence of typical underwater acoustic metamaterial structure and material parameters on sound absorption performance is studied. The results show that increasing the height or radius of the local resonance mass unit in the metamaterial is beneficial to improve the low frequency sound absorption performance. With the increase of the distance between mass elements and the thickness of elastic material, the acoustic absorption performance increases first and then decreases. Increasing the elastic modulus of elastic material of the local resonance unit or matrix will lead to the decrease of low frequency sound absorption performance of the material and the improvement of high frequency sound absorption performance. Increasing the loss factor of elastic material of the local resonance unit or matrix material can broaden the sound absorption band. These rules can provide guidance for the design of underwater acoustic metamaterials.
The Influences of Element Addition on Compression Properties of β-Ti-Mo (Nb)-based Alloys
Authors: Zhou Zhengcun , Zhu Xiaobin
Published: March 2024

The influences of the third element addition on the compression properties of Ti-12Mo-based and Ti-33Nb-based alloys was investigated, with emphasis on the influences of element addition on Young’s modulus, superelastic strain and yield strength of water-cooling samples. It is found that the water-cooling Ti-12Mo alloy has a lower modulus, lower yield strength, and higher hyperelastic strain than that of the furnace-cooled alloy of the same composition. Al and Sn can reduce the modulus and the yield strength, and increase the superelastic strain in the above two water-cooling alloys. The decrease in yield strength and modulus is due to orthogonal martensite ɑ’. The enhancement of the superelastic strain originated from the phase transformation of the ɑ”↔βM under stress. The effect of Sn in water-cooling quaternaryTi-18Nb-5Mo-5Sn alloy is different from the above two ternary alloys, and it increases β Phase stability and volume in water-cooling Ti-18Nb-5Mo-5Sn alloy.
Research on modification of polylactic acid multifunctional composite materials for 3d printing
Authors: Zhong Yanhui , Chen Yanfang , Geng Qingfen
Published: March 2024

Polylactic acid is an important 3D printing material, but its further development and application in the field of 3D printing are limited due to its flammability, poor toughness, and lack of high temperature resistance. This article modifies polylactic acid wire for 3D printing by adding flame retardants aluminum hypophosphate, polycarbonate, and chain extender to prepare multifunctional composite flame retardant materials. It was found that with the increase of aluminum hypophosphate addition, the flame retardancy of polylactic acid composite materials gradually improved, while the tensile strength, impact strength, and hardness showed a decreasing trend, and the flowability decreased, but the Vicat softening temperature increased. Through 3D printing testing, when the amount of aluminum hypophosphate added is 15-20 parts, the printing quality is good and the comprehensive performance is the best, which can meet the basic usage requirements.
Facile preparation of poly(melamine formaldehyde) sponge/bacterial nanocellulose composite for oil-water separation
Authors: Feng Jia , Jin Wende , Hu Jinpeng , Cai Yiming , Zhou Guowei , Chen Xiaogang , Du Miao
Published: March 2024

The treatment of a large amount of oil-water mixture generated by oil leakage accidents is an environmental issue that cannot be ignored. Achieving fast and efficient oil-water separation is a goal pursued by both academia and industry. In this paper, poly(melamine formaldehyde) (PMF) sponges were modified by the hydrophilic bacterial nanocellulose (BNC) through mild and facile conditions. With increasing the concentration of BNC dispersion used, the pore size of the composite decreases. The water contact angle of the obtained PMF/BNC composite surface is 0° or so, and the underwater oil contact angle is greater than 150°. Based on its hierarchical pore structure, hydrophilicity and oil repellency, the PMF/BNC composite exhibits excellent oil-water separation efficiency and water treatment flux for layered oil-water mixture (>1.0×107L/(m2·h·bar)). In addition, the PMF/BNC composite also exhibits high water treatment flux and oil-water separation efficiency (> 95%) for oil-water emulsion with and without surfactant. Stacking several composite slices could achieve higher oil-water separation efficiency.
Forming quality analysis of TC4 titanium alloy based on SLM orthogonal process
Authors: Huang Jie , Wang Qi , Peng HongBing , Ding XuQiang , Liu Xiaona , Lu Jun
Published: March 2024

The TC4 titanium alloy bulk and irregular porous structures were prepared using Selective Laser Melting (SLM). This study systematically investigated the effects of laser power, scanning speed, scanning spacing, and laser energy density on the forming quality of TC4 titanium alloy specimens, through orthogonal experimental design. The research results indicate that laser power is the primary factor affecting the density of TC4 titanium alloy bulk during the SLM process. With the increase of laser energy density, the density of the specimens shows an initial increase followed by a decrease, while Vickers hardness and surface roughness exhibit a decreasing trend followed by an increasing trend. Moreover, the surface of the specimens transforms from a rough surface with a significant presence of pores, voids, or unmelted powder particles to a relatively smooth and flat surface, accompanied by a reduction in the size and quantity of pore defects.
Study on efficient oil-containing wastewater purification with super-hydrophilic PVDF coating
Authors: Wang Xiepeng , Qi Zhouyu , Xia Mengsheng , Gao Junkai
Published: March 2024

The sustainable, low-energy, and cost-effective treatment of oily wastewater has become an important issue for aquatic ecosystems, environmental protection, and economic development. Improper treatment could have a significant impact on aquatic ecosystems, resulting in eutrophication and fish deaths. The method for preparing PVDF-CC by impregnation involves using polyvinylidene fluoride (PVDF), chitosan, and sodium citrate. Moreover, these performance improvements can be achieved at a lower cost compared to using many other chemical agents in membrane processing.
Study on efficient degradation of tetracycline by titania nanoribbons modified with silver
Authors: Fu Ying , Du Yuanyuan , Wang Ruixue , Zhang Xinyu , Gao Xing
Published: March 2024

TiO2 nanoribbons were prepared by hydrothermal method using P25 as titanium source, and Ag/TiO2 composites were prepared by REDOX method. Xenon lamp was used as the light source to study the photocatalytic degradation efficiency of tetracycline by Ag/TiO2 and tetracycline degradation efficiency under different conditions. When the initial concentration of tetracycline was 50mg/L, the pH value was 8, and the catalyst dosage was 0.05g. The optimal reaction conditions showed that the degradation efficiency of tetracycline by Ag/TiO2 composite could reach 88.9%, which was 12% higher than that of TiO2.
Constitutive model of piezoelectric/shape memory polymer composite
Authors: Zhao Fei , Zhou Bo , Zhu Xiuxing , Wang Haijing
Published: March 2024

The PZT/SMP composite material, combining piezoelectricity and shape memory effects, has emerged as a novel multifunctional smart material and has gained significant attention. The establishment of an effective constitutive model, describing the mechanical properties of the composites, holds tremendous importance in both theoretical and engineering realms. This study aims to develop a model to investigate the mechanical properties of PZT/SMP composites. By incorporating the deformation mechanisms of the PZT/SMP composites and the theories of viscoelasticity, the constitutive equation for PZT/SMP composites has been established. Based on composite material theory and the properties of transversely isotropic materials, combined with the material parameter equations for SMP, the material parameter equations of PZT/SMP composites have been established. Using the polarization direction of the composite material as an example, we conduct simulation analyses on PZT/SMP composites with various volume fractions of PZT particles by using the developed constitutive model. The variations in material parameter performance, piezoelectric performance, and shape memory performance are investigated. The simulation results demonstrate that an increase of PZT content in the PZT/SMP composite enhances both the piezoelectric and mechanical properties of the composite material, which significantly influences the shape memory process.
Research on corrosion behavior of safety valve spring in liquid chlorine tank
Authors: Li Qingshan , Jiang Jiwu , Yang Bing , Chen Zheming , Yang Lijun , Jin Muda , Xia Xinhua , Xie Xumeng
Published: March 2024

The corrosion behavior of the safety valve spring in the liquid chlorine tank is investigated in this study. The chemical composition, metallographic structure and hardness of the spring are also analyzed. The higher hardness of spring steel is caused by lower tempering temperatures. The corrosion product is grey with many cracks, spalling and pitting is also found. The phenomenon that where there is higher chloride, there is higher carbon is observed. Chloride ion is adsorbed by carbides and then pitting preferentially nucleate at carbides.
Effects of plasma surface quenching on strength and crack resistance property of PCrNi3 Mo steel
Authors: Jiang Qiang , Wang Shuogui
Published: March 2024

Plasma surface quenching technology uses a high-energy beam to rapidly heat the PCrNi3Mo steel material. Simultaneously, the treated workpiece is rapidly cooled by its own heat transfer to realize surface quenching. The metallographic structure showed that the grains of the PCrNi3Mo steel treated by plasma quenching were significantly refined. The DEFORM software was utilized to simulate the heat treatment process, and the results showed that the martensitic volume fraction of the plasma quenching treatment of PCrNi3Mo steel was as high as 83.6%~95.9%, and the simulated hardness value was HRC55~57. The actual hardness of the specimen after plasma surface quenching was HRC54~56, which was in good agreement with the simulation value. The plasma was employed to treat the PCrNi3Mo steel tensile specimen, the processing depth was only 1/10 of the thickness of the specimen. Through the MTS tensile experiment, it was observed that the tensile strength of specimens treated with plasma increased by 9.2% when compared to the untreated specimens. Despite the high hardness of the treated specimen, fracture strain exceeded 7%. Furthermore, before the fracture of the tensile specimen occurred, the plasma quenching part effectively prevented crack propagation and delayed fracture, and the fracture necking phenomenon of the specimen was not obvious.
The effect of chemical composition and heat parameter on Nano-sized precipitate dispersion characterization in ODS steels
Authors: Xie Rui , Lyu Zheng , Wang Qing , Liu Chunming
Published: March 2024

Oxide dispersion strengthened (ODS) supersaturated solid solution alloy powders with different Y/Ti atomic ratios were formed by mechanical alloying (MA) method and then heat treated under different conditions. The morphology, phase composition, and particle size distribution were researched. The precipitate distribution densities and hardness values of alloy powders after heat treatment were measured at the same time by the SAXS method and hard tester. The results show that the morphology of MA alloy powders is irregular in shape and only a small amount of MA alloy powders is bigger than 30 μm. During the MA process, alloy elements are solid solutions in the matrix. The work-harden effect of alloy powders formed in the MA process would be eliminated during the heat treatment process. The chemical composition and heat treatment parameters are crucial effects on nano-sized precipitate distribution characterization in ODS steels. The ODS sample with a Y/Ti atomic ratio of 0.99 has the highest distribution density of oxide precipitates at 1.89×1022/m3 resulting in the highest hardness value during the heat treatment process. The sample with a Y/Ti atomic ratio of 0.42 has the highest distribution density of nanoclusters 7.32×1023/m3.
ATLAS ITk strip detector for the Phase-II Upgrade
Authors: Herde H. ,   the ATLAS-ITk Strip collaboration
Published: March 2024

The inner detector of the present ATLAS experiment has been designed and developed to
function in the environment of the present Large Hadron Collider (LHC). At the ATLAS Phase-II
Upgrade, the particle densities and radiation levels will exceed current levels by a factor of
ten. The instantaneous luminosity is expected to reach unprecedented values, resulting in up to
200 proton-proton interactions in a typical bunch crossing. The new detectors must be faster and
they need to be more highly segmented. The sensors used also need to be far more resistant to
radiation, and they require much greater power delivery to the front-end systems. At the same
time, they cannot introduce excess material which could undermine tracking performance. For those
reasons, the inner tracker of the ATLAS detector was redesigned and will be rebuilt completely.

The ATLAS Upgrade Inner Tracker (ITk) consists of several layers of silicon particle
detectors. The innermost layers will be composed of silicon pixel sensors, and the outer
layers will consist of silicon microstrip sensors. This contribution focuses on the strip
region of the ITk. The central part of the strip tracker (barrel) will be composed of
rectangular short (∼2.5 cm) and long (∼5 cm) strip sensors. The forward regions
of the strip tracker (end-caps) consist of six disks per side, with trapezoidal shaped
sensors of various lengths and strip pitches. After the completion of final design reviews
in key areas, such as Sensors, Modules, Front-End electronics, and ASICs, a large scale
prototyping program has been completed in all areas successfully. We present an overview of
the Strip System and highlight the final design choices of sensors, module designs and
ASICs. We will summarise results achieved during prototyping and the current status of
pre-production and production on various detector components, with an emphasis on QA and QC
procedures.
Daytime cooling efficiencies of urban trees derived from land surface temperature are much higher than those for air temperature
Authors: Du Meng , Li Niantan , Hu Ting , Yang Qiquan , Chakraborty TC , Venter Zander , Yao Rui
Published: March 2024

Accurately capturing the impact of urban trees on temperature can help optimize urban heat mitigation strategies. Recently, there has been widespread use of remotely sensed land surface temperature (T
s) to quantify the cooling efficiency (CE) of urban trees. However, remotely sensed T
s reflects emitted radiation from the surface of an object seen from the point of view of the thermal sensor, which is not a good proxy for the air temperature (T
a) perceived by humans. The extent to which the CEs derived from T
s reflect the true experiences of urban residents is debatable. Therefore, this study systematically compared the T
s-based CE (CE
T

s) with the T
a-based CE (CE
T

a) in 392 European urban clusters. CE
T

s and CE
T

a were defined as the reductions in T
s and T
a, respectively, for every 1% increase in fractional tree cover (FTC). The results show that the increase in FTC has a substantial impact on reducing T
s and T
a in most cities during daytime. However, at night, the response of T
s and T
a to increased FTC appears to be much weaker and ambiguous. On average, for European cities, daytime CE
T

s reaches 0.075 °C %−1, which is significantly higher (by an order of magnitude) than the corresponding CE
T

a of 0.006 °C %−1. In contrast, the average nighttime CE
T

s and CE
T

a for European cities are similar, both approximating zero. Overall, urban trees can lower daytime temperatures, but the magnitude of their cooling effect is notably amplified when using remotely sensed T
s estimates compared to in situ T
a measurements, which is important to consider for accurately constraining public health benefits. Our findings provide critical insights into the realistic efficiencies of alleviating urban heat through tree planting.
More on symmetry resolved operator entanglement
Authors: Murciano Sara , Dubail Jérôme , Calabrese Pasquale
Published: March 2024

The ‘operator entanglement’ of a quantum operator O is a useful indicator of its complexity, and, in one-dimension, of its approximability by matrix product operators. Here we focus on spin chains with a global U(1) conservation law, and on operators O with a well-defined U(1) charge, for which it is possible to resolve the operator entanglement of O according to the U(1) symmetry. We employ the notion of symmetry resolved operator entanglement (SROE) introduced in Rath et al (2023 PRX Quantum
4 010318) and extend the results of the latter paper in several directions. Using a combination of conformal field theory and of exact analytical and numerical calculations in critical free fermionic chains, we study the SROE of the thermal density matrix

ρ
β

=

e

−
β
H

and of charged local operators evolving in Heisenberg picture

O
=

e

i
t
H

O

e

−
i
t
H

. Our main results are: i) the SROE of

ρ

β

obeys the operator area law; ii) for free fermions, local operators in Heisenberg picture can have a SROE that grows logarithmically in time or saturates to a constant value; iii) there is equipartition of the entanglement among all the charge sectors except for a pair of fermionic creation and annihilation operators.
Numerical analysis of scaffold degradation in cryogenic environment: impact of cell migration and cell apoptosis
Authors: Deshmukh Khemraj , Bit Arindam
Published: March 2024

The analysis of degradation in the presence of cell death and migration is a critical aspect of research in various biological fields, such as tissue engineering, regenerative medicine, and disease pathology. In present study, numerical study of degradation of scaffold were performed in present of cells, cell apoptosis and cell migration. A poly electrolyte complex (PEC) silk fibroin scaffold was used for degradation study. Degradation study in the presence of cells and migration were performed at fixed pH concentration 7.2. Similarly, degradation study of scaffold were performed at different pH cell apoptosis. A transient analysis of scaffold was evaluated in COMSOL 5.5 in presence of cryogenic temperature at different temperature gradient. The parameters; temperature, stress, strain tensor and deformation gradient associated with the degradation of polyelectrolyte complex scaffold were evaluated. Result shows that in both geometries minimum temperature had been achieved as 230.051 K at point P4 in series view and parallel view and at a point P3 for cell migration study for −5 k min−1 and −1 k min−1, respectively. The maximum stress had been generated for 5.57 × 107 N m−2 for the temperature gradient of −2 K min−1 at T cycle in the case of cell migration study. In contrast in series view the maximum stress 2.9 × 107 N m−2 were observed at P4 which was higher as compare to P3. Similarly, for a parallel view, maximum stress (3.93 × 107 N m−2) was obtained for point P3. It had been observed that the maximum strain tensor 5.21 × 10−3, 5.15 × 10−3 and 5.26 × 10−3 was generated in series view at 230 k on a point P3 for − 1, −2 and −5 K min−1, respectively. Similarly, the maximum strain tensor 8.16 × 10−3, 8.09 × 10−3 and 8.09 × 10−3 was generated in parallel view at 230 k on a point P3 for −1, −2 and −5 K min−1, respectively. In the presence of cells, at a point P4 for temperature gradient of −1 and −2 K min−1, it had been closed to the scaffold wall, which had a different temperature profile than the point P3 and scaffold comes to the contact with the cells. The analysis of PEC scaffold degradation in the presence of cells, including cell apoptosis and migration, offers significant insights into the relationship between scaffold properties, cell behaviour, and tissue regeneration.
Solar-powered fabric cools in the day and warms at night
Authors: Jarman Sam
Published: March 2024

Researchers in China have unveiled a new concept for solar-powered clothing that can regulate its wearer’s body temperature.
Baidu and Alibaba to quit quantum computing research
Authors: Boerkamp Martijn
Published: March 2024

Chinese search engine company Baidu has donated its quantum computing research facility to the Beijing Academy of Quantum Information Sciences, following a similar move by Chinese e-commerce giant Alibaba, which donated its quantum lab to Zhejiang University last November.
Opportunity knocks
Authors: Durrani Matin
Published: March 2024

Our 2024 careers guide showcases the many physics job options beyond academia.
What’s in a cover?
Authors: Coleman Jemima , Sadler Wendy
Published: March 2024

Jemima Coleman and Wendy Sadler say that science magazines have a responsibility to ensure that science is accessible and inclusive for all.
From cosmic rays to cardiology
Authors: Commissariat Tushna
Published: March 2024

Data scientist and artificial-intelligence researcher Azadeh Keivani talks to Tushna Commissariat about her journey from astronomy to healthcare, co-founding an educational non-profit organization and her work in outreach.
Ultrasound-driven triboelectric and piezoelectric nanogenerators in biomedical application
Authors: Kao Fu-Cheng , Hung Shih-Feng , Yang Chang-Chi , Parashar Parag , Huang Chun-Ju , Hsieh Ming-Kai , Liao Jen‐Chung , Lai Po-Liang , Fu Tsai-Sheng , Tsai Tsung-Ting , Lin Zong-Hong
Published: March 2024

Microelectronics play a crucial role in medical settings by monitoring physiological signals, treating illnesses, and enhancing human well-being. For implanted and wearable devices, a reliable and continuous energy source is essential. While conventional energy systems rely on batteries and external power connections, their drawbacks, including the need for frequent charging, limited battery lifespan, and the potential for reoperation, restrict their utility. This has spurred the exploration of self-sustaining, long-lasting power solutions. The ultrasound-driven nanogenerator, a promising energy source, harnesses biomechanical energy from activities like muscle movement, heartbeat, respiration, and gastric peristalsis. It converts this energy into electrical signals, enabling the detection of physiological and pathological markers, cardiac pacing, nerve stimulation, tissue repair, and weight management. In this review, we provide an overview of triboelectric (TENG) and piezoelectric (PENG) nanogenerator design with ultrasound and its applications in biomedicine, offering insights for the advancement of self-powered medical devices in the future. These devices hold potential for diverse applications, including wound treatment, nerve stimulation and regeneration, as well as charging batteries in implanted devices.