Mass transfer enhancement and hydrodynamic performance with wire mesh coupling solid particles in bubble column reactor

It is of vital significance to investigate mass transfer enhancements for chemical engineering processes.This work focuses on investigating the coupling influence of embedding wire mesh and adding solid particles on bubble motion and gas-liquid mass transfer process in a bubble column.Particle image velocimetry(PIV)technology was employed to analyze the flow field and bubble motion behavior,and dynamic oxygen absorption technology was used to measure the gas-liquid volumetric mass transfer coefficient(kLa).The effect of embedding wire mesh,adding solid particles,and wire mesh coupling solid particles on the flow characteristic and kLa were analyzed and compared.The results show that the gas-liquid interface area increases by 33%-72%when using the wire mesh coupling solid particles strategy compared to the gas-liquid two-phase flow,which is superior to the other two strengthening methods.Compared with the system without reinforcement,kLa in the bubble column increased by 0.5-1.8 times with wire mesh coupling solid particles method,which is higher than the sum of kLa increases with inserting wire mesh and adding particles,and the coupling reinforcement mechanism for affecting gas-liquid mass transfer process was discussed to provide a new idea for enhancing gas-liquid mass transfer.

Challenges and opportunities in the production of magnesium parts by directed energy deposition processes

Mg-alloys have gained considerable attention in recent years for their outstanding properties such as lightweight,high specific strength,and corrosion resistance,making them attractive for applications in medical,aerospace,automotive,and other transport industries.However,their widespread application is hindered by their low formability at room temperature due to limited slip systems.Cast Mg-alloys have low mechanical properties due to the presence of casting defects such as porosity and anisotropy in addition to the high scrap.While casting methods benefit from established process optimization techniques for these problems,additive manufacturing methods are increasingly replacing casting methods in Mg alloys as they provide more precise control over the microstructure and allow specific grain orientations,potentially enabling easier optimization of anisotropy properties in certain applications.Although metal additive manufacturing(MAM)technology also results in some manufacturing defects such as inhomogeneous microstructural evolution and porosity and additively manufactured Mg alloy parts exhibit lower properties than the wrought parts,they in general exhibit superior properties than the cast counterparts.Thus,MAM is a promising technique to produce Mg alloy parts.Directed energy deposition processes,particularly wire arc directed energy deposition(WA-DED),have emerged as an advantageous additive manufacturing(AM)technique for metallic materials including magnesium alloys,offering advantages such as high deposition rates,improved material efficiency,and reduced production costs compared to subtractive processes.However,the inherent challenges associated with magnesium,such as its high reactivity and susceptibility to oxidation,pose unique hurdles in the application of this technology.This review paper delves into the progress made in the application of DED technology to Mg-alloys,its challenges,and prospects.Furthermore,the predominant imperfections,notably inhomogeneous microstructure evolution and porosity,observed in Mg-alloy components manufactured through DED are discussed.Additionally,the preventive measures implemented to counteract the formation of these defects are explored.

C1C2 Wiring and Posttraumatic Atlantoaxial Dislocation: An Effective and Cheap Surgical Procedure in a Developing Country

Objectives: Atlantoaxial dislocation remains a rare and serious condition with a high preoperative and postoperative morbidity and mortality. Its successful surgical management is still challenging and gratifying for neurosurgeons. Several technics have been described such as wiring, trans articular screwing, C1C2 screwing with plate and screw introduced by Goel et al., and modified by insertion of polyaxially screw and rod many years later by Harms. Unavailability and expensiveness of upper cervical spine instrumentation device led us to C1C2 Wiring resulting in a good outcome. Finally, a quadriplegic patient with a more comfortable financial condition had ordered devices from abroad and benefit for Goel and Harms screwing technique and improved dramatically from ASIA A to ASIA E. Material and methods: This is a retrospective study of patients managed in our department by a same neurosurgeon from January 2019 to April 2024. Results: We defined 6 men and 1 woman with an average age of 33 years. Unrestrained driver in a rollover motor vehicle accident was most common. Only one patient was neurologically intact on admission. Neurovegetative disorders were noticed in one patient. Dislocation was associated to a fracture of the dens in two patients. Three patients have been successfully operated with remarkable outcome, mostly from ASIA A to E. Conclusion: C1C2 dislocation is a serious condition and C1C2 Wiring represents an effective and cheaper technic. Therefore, this technic should deserve consideration above all in low incomes countries when screwing devices are not available. Seatbelt should be demanded for motor vehicle drivers and passengers.

Robust interface and excellent as-built mechanical properties of Ti–6Al–4V fabricated through laser-aided additive manufacturing with powder and wire

The feasibility of manufacturing Ti-6Al-4V samples through a combination of laser-aided additive manufacturing with powder(LAAM_(p))and wire(LAAM_(w))was explored.A process study was first conducted to successfully circumvent defects in Ti-6Al-4V deposits for LAAM_(p) and LAAM_(w),respectively.With the optimized process parameters,robust interfaces were achieved between powder/wire deposits and the forged substrate,as well as between powder and wire deposits.Microstructure characterization results revealed the epitaxial prior β grains in the deposited Ti-6Al-4V,wherein the powder deposit was dominated by a finerα′microstructure and the wire deposit was characterized by lamellar α phases.The mechanisms of microstructure formation and correlation with mechanical behavior were analyzed and discussed.The mechanical properties of the interfacial samples can meet the requirements of the relevant Aerospace Material Specifications(AMS 6932)even without post heat treatment.No fracture occurred within the interfacial area,further suggesting the robust interface.The findings of this study highlighted the feasibility of combining LAAM_(p) and LAAM_(w) in the direct manufacturing of Ti-6Al-4V parts in accordance with the required dimensional resolution and deposition rate,together with sound strength and ductility balance in the as-built condition.

UG/Wiring在电子设备布线设计中的应用

以某型号记录舱检查仪三维模型为基础,在UG/Wiring环境下探讨了接插件的建模,输入元件表和接线表的创建,实现了接插件、电缆和设备结构的虚拟装配,并生成二维的工程图,提高了电子设备的线缆组件的设计的效率,缩短的研发周期。

Numerical simulation on residual stress and deformation for WAAM parts of aluminum alloy based on temperature function method

Wire arc additive manufacture(WAAM) is a new technique to fabricate large-scale complex aluminum alloy components.However, the performance of the parts is critically influenced by residual stresses and deformation. A sequentially thermal-mechanical coupled model of residual stress and deformation for aluminum alloy WAAM parts was established based on commercial FE software ABAQUS. The temperature field was calculated by the moving heat source(MHS) method. The temperature function was obtained according to the distribution of the peak temperature. Furthermore, the MHS method and segmented temperature function(STF) method were used to calculate the residual stress and deformation. The results show that the STF method satisfies both the efficiency and accuracy requirements. 1-segment, 3-segment, and 5-segment STF methods can shorten the time for mechanical analysis by 91%, 79%, 63%, respectively.The error of the residual stress and deformation are all less than 20%. STF method provides an effective way to predict the residual stress and deformation of large-scale WAAM parts.

Automatic wiring method for switchgear design

An automatic 3D wiring method for switchgear design is proposed in this paper. First, wiring constraints are created, and a corresponding evaluation model is proposed. Then, based on the structure of the cabinet, we propose a contour expansion scheme to construct rough paths. Different wiring features of the switchgear are used to connect rough local paths. All the paths are represented in a uniform data structure and forma path network. Finally, an improved A* algorithm is used to search the wiring path between the components in the routing network; the evaluation model is considered as heuristic rules for path searching. The result can satisfy the practical requirements of switchgear design. Experimental results are also provided.

面向UG/Wiring模块的接插件建模研究

利用UG的建模功能和Excel的表格功能,研究了一种面向UG/Wiring模块的接插件模型库创建方法,并讨论了接插件端口属性定义的方法。以J30J-9TJ接插件为例说明了这种建模的方法的操作流程,建立了该系列接插件的模型库,有效的减少了重复工作,提高了设计效率。

基于UG/WIRING模块在电子机柜上布线应用

通过UG/WIRING模块在电子机柜上三维布线的应用,可以解决我们电子机柜设计制造过程中的线缆滞后上架的问题,满足我们对线缆互连设计的要求;将布线精确地三维设计,完成机柜整机数字化样机,达到线缆与结构同步设计,实现产品快速设计与应用。

DETERMINATION OF THERMAL CONDUCTIVITY FOR PARTICULATE MATERIALS

A modified hot wire method was applied to measure the thermal conductivity of different kinds of parti culate materials. With a cylindrical device, a heating rod and two thermocouples, the measurement can be finished within several minutes. Compared with the reference data, the results obtained from the measurements were quite reasonable.

Mechanical alloying of platinum with 5% ZrO_2 nanoparticles for glass making tools

Synthesis and characterization of mechanically alloyed Pt-5%ZrO2(volume fraction) for structural components in the glass industry were described. Zirconia(ZrO2) nanoparticles(<100 nm) were produced by the electrical explosion of zirconium(Zr) wires, and blended with platinum(Pt) powders(<44 ?m) for 2-72 h in ambient atmosphere. The Pt particle size followed the typical decreasing trend of the normal ball milling process up to 48 h, but particle agglomeration was observed at 72 h. The grain size evolution was similar to that of the particle size, dropping down to around 50 nm at 48 h. The root mean square strain of the Pt crystallites showed the opposite behavior, maximizing at 48 h with a subsequent relaxation process. For the 48 h ball milled powders, spark plasma sintering was carried out to form a bulk disk. The measured mass loss of the sintered bulk sample shows a decent thermal stability despite its relatively low density.

Laser-manipulated the of a harmonically multiphoton transitions trapped particle

A single particle magneto-confined in a one-dimensional （1D） quantum wire experiences a harmonic potential, and imposing a sharply focused laser beam on an appropriate site shapes a δ potential. The theoretical investigation has demonstrated that for a sufficiently strong δ pulse the quantum motional stationary state of the particle is one of the eigenstates of the free harmonic oscillator, and it is determined by the site of the laser beam uniquely, namely a quantum state is admissible if and only if the laser site is one of its nodes. The numerical computation shows that all the nodes of the lower energy states with quantum numbers n ≤ 20, except the coordinate origin, are mutually different. So we can manipulate the multiphoton transitions between the quantum states by adjusting the position of the laser δ pulse and realize the transition from an unknown higher excitation state to a required lower energy state.

A nanoparticle formation model considering layered motion based on an electrical explosion experiment with AI wires

To study the evolution of nanoparticles during Al wire electrical explosion,a nanoparticle formation model that considered layered motion was developed,and an experimental system was set up to carry out electrical explosion experiments using 0.1 mm and 0.2 mm Al wires.The characteristic parameters and evolution process during the formation of nanoparticles were calculated and analyzed.The results show that the maximum velocities of the innermost and outermost layers are about 1200 m·s-1and 1600 m·s-1,and the velocity of the middle layer is about 1400 m·s-1,respectively.Most of the nanoparticles are formed in the temperature range of2600 K-2500 K.The characteristic temperature for the formation of Al nanoparticles is~2520K,which is also the characteristic temperature of other parameters.The size distribution range of the formed nanoparticles is 18 to 110 nm,and most of them are around 22 nm.The variation of saturated vapor pressure determines the temperature distribution range of particle nucleation.There is a minimum critical diameter of particles(~25 nm);particles smaller than the critical diameter can grow into larger particles during surface growth.Particle motion has an effect on the surface growth and aggregation process of particles,and also on the distribution area of larger-diameter particles.The simulation results are in good agreement with the experiments.We provide a method to estimate the size and distribution of nanoparticles,which is of great significance to understand the formation process of particles during the evolution of wire electrical explosion.

One-step synthesis of FeO(OH)nanoparticles by electric explosion of iron wire underwater

In this study,we investigated electric explosion of iron wire in distilled water with different energy input adjusted by charging voltage.The as-prepared samples were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM)and X-ray photoelectron spectroscopy(XPS),showing the presence of iron and multiple iron-based compounds oxides with contents influenced by the experimental conditions.In particular,pure FeO(OH)nanoparticles were obtained using electric explosion of iron wire with energy input of 1125 J at charging voltage of 15 kV.Analysis of discharge current and resistive voltage data indicate that the high energy input induced bystrong plasma discharge at high charging voltage is a key factor to form FeO(OH).This study presents a one-step method to synthesize FeO(OH)nanoparticles using electric explosion of iron wire.

Understanding the Mechanism of Nanoparticle Formation in a Wire Explosion Process by Adopting the Optical Emission Technique

In the present study nano-tungsten carbide particles were generated in a wire explosion process.The plasma generated during the wire explosion process was analyzed using optical emission spectroscopy（OES）.The impact of ambient pressure on the plasma temperature,electron density and plasma lifetime was studied.Lifetime variations of the plasma produced under different experimental conditions were analyzed.The produced nanoparticles were characterized through wide angle X-ray diffraction（WAXD） and transmission electron microscopy（TEM） studies. Particles produced with a negative DC charging voltage had a larger mean size when compared to a positive charging voltage.Polarity dependence on the plasma duration was observed where plasma was sustained for a longer duration with a negative DC charging voltage.

An Analysis of the Formation Mechanisms of Abrasive Particles and Their Effects on Cutting Efficiency

Magnetic induction-free abrasive wire sawing(MIFAWS)is a method that combines magnetic fields with traditional free abrasive wire sawing technologies.Magnetic abrasive particles(MAPs)are attracted on a magnetized wire,thus leading to an increase in their number into the cutting zone.The number of instantaneous-effective abrasive particles(IEAPs)adsorbed on the wire surface has a great influence on the cutting efficiency of the saw wire.In this study,a mathematic model of the movement of the MAP is presented,and the factors influencing the IEAPs number,including slurry-supply speed and slurry dynamic viscosity,are investigated both by means of simulation analysis and experiments.The results indicate that the number of IEAPs decreases with an increase in the slurry supply speed.The cutting efficiency increases gradually with the increase of slurry supply speed,but the growth rate of wire saw cutting efficiency slows down when the slurry supply speed exceeds a given threshold.The number of IEAPs adsorbed by saw wire increases with a decrease in the dynamic viscosity of the cutting fluid,while the cutting efficiency first increases and then decreases.The cutting efficiency attains its highest value when the dynamic viscosity of the cutting fluid is 0.0047 Pa⋅s.The experimental results agree with the simulation results,and provide some guidance for the practical application of the MIFAWS process.

Recent design and applications of flexible electrodes based on Ag nanowires and nanoparticles:a review

The recent rapid growth in electronics has reached the point where there is a need for solid-state devices with excellent physical flexibility, which will be a significant advantage in modern electronic devices. In particular, metal nanowires and nano-particles are chosen for electrodes because of their low resistance and high mechanical stability. Among the various alternatives, Ag nanomaterials have recently garnered increasing attention due to the high intrinsic conductivity, a transparency with a low sheet resistance and relatively low cost. We herein summarize recent developments toward flexible electronics on the basis of Ag nanomaterials , which show promising performance and outperform the commonly used. The typical fabrication techniques along with the promising applications for flexible devices, are thoroughly discussed.

Webgis-Based Telecommunication Resource Management Auxiliary Wiring System

This paper introduces the necessity and superiority of auxiliary wiring WEBGIS, as well as system implementation difficulties and countermeasures. Then explained the general concept of auxiliary wiring systems, data interface response, and finally introduced the system wiring switchover function, and gave an example.

Preparation of Aluminum Nanoparticles by Exploding Wire in Different Liquids

The present work, provides a simple technique for the production of aluminum nanoparticles based on the explosion of thin aluminum wires in different liquids （distilled water, ethylene glycol and cyclohexane） by applying 36 Volte DC to two electrodes, one in the form of thin wire and the other in the form of plate and bring them to in touch mechanically. The nanoparticles are characterized by x-ray diffraction and UV-Visible spectroscopy. The x-ray diffraction results reveal that the nanoparticles continue to routine lattice periodicity at reduced particle sizes. The UV-Visible absorption spectrum of the liquid solution of the aluminum nanoparticles shows no characteristic Surface Plasmon Resonance （SPR） peak in the visible region. The TEM and SEM images show that the aluminum nanoparticles have narrow particle size distribution ranged from 20 to120 um with average particle size 80 nm. The aluminum nanoparticles prepared in water and that prepared in ethylene glycol show, no difference in their average particle size and distribution, while those prepared in cyclohexane show smaller sizes. It was observed that the particles have a little irregular shapes and low agglomerate was observed.

Algorithm of automatic generation of technology process and process relations of automotive wiring harnesses

Identifying each process and their constraint relations from the complex wiring harness drawings quickly and accurately is the basis for formulating process routes. According to the knowledge of automotive wiring harness and the characteristics of wiring harness components, we established the model of wiring harness graph. Then we research the algorithm of identifying technology processes automatically, finally we describe the relationships between processes by introducing the constraint matrix, which is in or- der to lay a good foundation for harness process planning and production scheduling.