Advancing Al-doped ZnO thin films structural,optical and electrical properties of low temperature PET substrates via flash lamp annealing

In this study,aluminum-doped zinc oxide(AZO)thin films were deposited onto a low-temperature polyethylene terephthalate(PET)substrate using DC magnetron sputtering.Deposition parameters included power range of 100-300 W,a working pressure of 15 mTorr,and a substrate temperature of 50°C.Post-deposition,flash lamp annealing(FLA)was employed as a rapid thermal processing method with a pulse duration of 1.7 ms and energy density of 7 J·cm-2,aimed at enhancing the film's quality while preserving the temperature-sensitive PET substrate.FLA offers advantages over conventional annealing,including shorter processing times and improved material properties.The structural,optical,and electrical characteristics of the AZO films were assessed using X-ray diffraction,field emission scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy,ultraviolet-visible spectroscopy,and Hall effect measurements.The results demonstrated that properties of AZO films varied with deposition and annealing conditions.Films deposited at 200 W and subjected to FLA exhibited superior crystallinity,with average visible light transmittance exceeding 80%and resistivity as low as 0.38Ω·cm representing 95%improvement in transmittance.Electrical analysis revealed that carrier concentration,mobility,and resistivity were influenced by both sputtering and annealing parameters.These findings underscore the effectiveness of FLA in optimizing AZO thin film properties,highlighting potential in optoelectronics applications.

Microstructure, texture and mechanical properties of Mg-8Gd-4Y-1Nd-0.5Zr alloy prepared by pre-deformation annealing, hot compression and ageing

An extruded Mg-8Gd-4Y-1Nd-0.5Zr alloy was pre-heated at 470℃ for 1 h and subsequently compressed at 470℃ and two strain rates of 0.2 and 0.0003 s^-1. Microstructure, texture and mechanical properties of the alloy were examined by optical microscopy (OM), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), hardness test and tensile test. The results show that the post-deformed microstructures of alloy are non-uniform at both strain rates due to the dissolution of RE-rich particles and the occurrence of DRX. The textures of post-deformed alloy are affected by strain rate. The alloy exhibits a strong basal texture of (0001)//ND (normal direction) after compression at 0.2 s^-1, while a weak texture component of (0001)//ED (extrusion direction) is formed in the compression obtained at 0.0003 s^-1. Compared with the alloy compressed at 0.0003 s^-1, the compressed alloy obtained at 0.2 s^-1 presents better comprehensive mechanical properties with the ultimate tensile strength of 426 MPa, yield strength of 345 MPa and ductility of 2.1% when being aged at 225℃ for 8 h.

Research on the flow stability and noise reduction characteristics of quasi-periodic elastic support skin

To enhance flow stability and reduce hydrodynamic noise caused by fluctuating pressure,a quasiperiodic elastic support skin composed of flexible walls and elastic support elements is proposed for fluid noise reduction.The arrangement of the elastic support element is determined by the equivalent periodic distance and quasi-periodic coefficient.In this paper,a dynamic model of skin in a fluid environment is established.The influence of equivalent periodic distance and quasi-periodic coefficient on flow stability is investigated.The results suggest that arranging the elastic support elements in accordance with the quasi-periodic law can effectively enhance flow stability.Meanwhile,the hydrodynamic noise calculation results demonstrate that the skin exhibits excellent noise reduction performance,with reductions of 10 dB in the streamwise direction,11 dB in the spanwise direction,and 10 dB in the normal direction.The results also demonstrate that the stability analysis method can serve as a diagnostic tool for flow fields and guide the design of noise reduction structures.

Damage evolution and removal behaviors of GaN crystals involved in double-grits grinding

Elucidating the complex interactions between the work material and abrasives during grinding of gallium nitride(GaN)single crystals is an active and challenging research area.In this study,molecular dynamics simulations were performed on double-grits interacted grinding of GaN crystals;and the grinding force,coefficient of friction,stress distribution,plastic damage behaviors,and abrasive damage were systematically investigated.The results demonstrated that the interacted distance in both radial and transverse directions achieved better grinding quality than that in only one direction.The grinding force,grinding induced stress,subsurface damage depth,and abrasive wear increase as the transverse interacted distance increases.However,there was no clear correlation between the interaction distance and the number of atoms in the phase transition and dislocation length.Appropriate interacted distances between abrasives can decrease grinding force,coefficient of friction,grinding induced stress,subsurface damage depth,and abrasive wear during the grinding process.The results of grinding tests combined with cross-sectional transmission electron micrographs validated the simulated damage results,i.e.amorphous atoms,high-pressure phase transition,dislocations,stacking faults,and lattice distortions.The results of this study will deepen our understanding of damage accumulation and material removal resulting from coupling between abrasives during grinding and can be used to develop a feasible approach to the wheel design of ordered abrasives.

Mechanical Properties and Fracture Mechanism of a Glass Fiber Reinforced Polypropylene Composites

To study the effect of some parameters, such as, length and fraction of glass fiber (GF), and the fraction of maleic anhydride grafted polypropylene (PP-g-MAH), on the mechanical properties of glass fiber reinforced polypropylene (GF/PP) composites, tensile tests, bending tests and impact tests were conducted. Scanning electron microscope (SEM) was used to characterize the fracture mechanisms of the composites. The results show that, compared with 3 mm GF, 9 mm GF can significantly improve the strength of the composite better. Addition of PP-g-MAH, a kind of grafting agent, into the PP-30% LGF composite can result in a better mechanical properties because of the strengthening of the bonding interface between the matrix and the fiber. When the mass fraction of GF is 30% and the PP-g-MAH fraction is 6%, the mechanical properties of the composite are the best.

Tensile mechanical analysis of anisotropy and velocity dependence of the spinal cord white matter:a biomechanical study

In spinal cord injuries,external forces from various directions occur at various velocities.Therefore,it is important to physically evaluate whether the spinal cord is susceptible to damage and an increase in internal stress for external forces.We hypothesized that the spinal cord has mechanical features that vary under stress depending on the direction and velocity of injury.However,it is difficult to perform experiment because the spinal cord is very soft.There are no reports on the effects of multiple external forces.In this study,we used bovine spinal cord white matter to test and analyze the anisotropy and velocity dependence of the spinal cord.Tensile-vertical,tensile-parallel,shear-vertical,and shear-parallel tests were performed on the white matter in the fibrous direction(cranial to caudal).Strain rate in the experiment was 0.1,1,10,and 100/s.We calculated the Young’s modulus of the spinal cord.Results of the tensile and shear tests revealed that stress tended to increase when external forces were applied parallel to the direction of axon fibers,such as in tensile-vertical and shear-vertical tests.However,external forces those tear against the fibrous direction and vertically,such as in tensile-parallel and shear-parallel tests,were less likely to increase stress even with increased velocity.We found that the spinal cord was prone to external forces,especially in the direction of the fibers,and to be under increased stress levels when the velocity of external forces increased.From these results,we confirmed that the spinal cord has velocity dependence and anisotropy.The Institutional Animal Care and Use Committee of Yamaguchi University waived the requirement for ethical approval.

Investigation of the Structure Design and Heat Transfer Characteristics of Heating Cable

Indoor heating with an electrical heating cable,which has no harmful emissions to the environment,is an attractive way for radiant floor heating.To improve the heat transfer efficiency,a novel structure of the heating cable was designed by proposing the concept of the aluminum finned sheath.The transient heat transfer model from the embedded heating cables to the floor is established to validate the feasibility of this novel cable.The effects of the fin number and shape on the cable’s temperature and heat flux distribution were analyzed.The results show that,with the specific volume of the sheath,increasing the number of fins can enhance the thermal diffusion capacity of the heating cable and reduce its temperature.Rectangular fins exhibit higher performance for heat dissipation than triangular fins due to their larger surface area.The simulation result shows that the floor temperature above the cable rises from 5°C to 22.5°C after a 2-h heating process,which was validated with experimental results.The results and suggestions can provide reference to guide the design of the heating cable.

Thermo-mechanical properties of bowl-shaped grinding wheel and machining error compensation for grinding indexable inserts

In order to meet the technical requirements of grinding the circumferential cutting edge of indexable inserts, thermo-mechanical properties of bowl-shaped grinding wheel in high speed grinding process and the influence of dimension variations of the grinding wheel on machining accuracy were investigated. Firstly, the variation trends of the dimension due to centrifugal force generated in different wheel speeds were studied and the effect of stress stiffening and spin softening was presented. Triangular heat flux distribution model was adopted to determine temperature distribution in grinding process. Temperature field cloud pictures were obtained by the finite element software. Then, dimension variation trends of wheel structure were acquired by considering the thermo-mechanical characteristic under combined action of centrifugal force and grinding heat at different speeds. A method of online dynamic monitoring and automatic compensation for dimension error of indexable insert was proposed. By experimental verification, the precision of the inserts satisfies the requirement of processing.

Study on Training Innovation Ability of Forestry and Agricultural Mechanical Post-graduates

For training forestry and agricultural mechanical post-graduates＇ innovation ability. This paper studied some problems hindering students improvement, mean value and standard deviation of time management tendency of students were researched. The results showed, graduate enthusiasm should be mobilized, curriculum should be optimized, new teaching methods should be introduced, practice should be strengthened and paid more attention, a strict system of management and evaluation should be established

Image Analysis on Detachment Process of Dust Cake on Ceramic Candle Filter

Based on the analysis of high-speed video images, the detachment behavior of dust cake from the ceramic candle filter surface during pulse cleaning process is investigated. The influences of the dust cake loading,the reservoir pressure, and the filtration velocity on the cleaning effectiveness are analyzed. Experimental results show that there exists an optimum dust cake thickness for pulse-cleaning process. For thin dust cake, the patchy cleaning exists and the cleaning efficiency is low; if the dust cake is too thick, the pressure drop across the dust cake becomes higher and a higher reservoir pressure may be needed. At the same time there also exists an optimum reservoir pressure for a given filtration condition.

Bifurcation control of nonlinear oscillator in primary and secondary resonance

A weakly nonlinear oscillator was modeled by a sort of differential equation, a saddle-node bifurcation was found in case of primary and secondary resonance. To control the jumping phenomena and the unstable region of the nonlinear oscillator, feedback controllers were designed. Bifurcation control equations were obtained by using the multiple scales method. And through the numerical analysis, good controller could be obtained by changing the feedback control gain. Then a feasible way of further research of saddle-node bifurcation was provided. Finally, an example shows that the feedback control method applied to the hanging bridge system of gas turbine is doable.

Modeling and simulation of crushing process of spiral mining head

According to the characteristics of spiral mining head for deep seabed cobalt-rich crust, the kinematic model, cutting loads model, quantity of cutting picks model of mining head, granularity distribution model and energy consumption model were constructed. Based on these models, computer simulation program of cutting loads was developed with VB software. The mechanical parameters of mining head were obtained in the cutting depth range of 5160 mm. Making use of the simulation results, the effect of cutting depth of spiral mining head on the mining process was studied. The results show that the maximum force of single pick is 4.7051kN, the maximum force and torque of spiral drum of mining head are respectively 34.1668kN and 3.8795kN·m at the cutting depth of 160mm.

Analyzing the Flow Field in the Oil Chamber of a Hydrostatic Guide Rail Used for Ultra-Precision Machining: Numerical Simulation and Performance Optimization

In order to explore the impact of different structural design parameters and environmental factors on the performance of the hydrostatic guide rail,the flow field inside its oil chamber is simulated,which provides direction and guidance for the design and optimization of the guide rail system.Based on the theory of fluid lubrication and the Reynolds equation,numerical simulations are performed through a mathematical model.The results suggest that the bearing capacity of the oil film increases with the oil supply pressure.The film thickness and the film stiffness share a positive correlation.Different oil film thickness and different input pressure parameters can have a significant impact on bearing capacity and oil film stiffness.The correlations identified in the present analysis can be used as a basis to optimize the guide rail design.

Reduction and subsequent carburization of pre-oxidation magnetite pellets

Magnetite is a kind of iron ore that is difficult to carburize.In order to improve the carburizing performance of magnetite pellet,pre-oxidation treatment was carried out,and the oxidation,reduction and carburization behaviors of magnetite pellet were investigated in this study.The magnetite pellet was oxidized in the air and carburized in CO-CO_(2)-H_(2) gas mixtures,the oxidation,reduction and carburization behaviors were demonstrated by detecting phase change,microstructure,carburizing index via thermogravimetry,X-ray diffraction(XRD),infrared carbon-sulfur analyzer,and scanning electron microscope(SEM).The results show that the dense magnetite particles inside pellet are oxidized to porous hematite particles,and the Fe_(3)O_(4) transforms to Fe_(2)O_(3) with high lattice defect concentration during the pre-oxidation process.Then the porous hematite particles and newly formed Fe_(2)O_(3) significantly promote the reduction efficiency.Porous metallic iron particles are produced in the reduction process.Finally,both high reduction efficiency and the porous structure of metallic iron particles dramatically enhance the carburization efficiency of pellet.High preoxidation temperature favors to the carburization of magnetite pellet.However,the carburized index decreases due to the recrystallization of iron oxide when the temperature extends to 1000℃.The optimum pre-oxidation temperature for magnetite pellet carburization is 900℃.

Microstructure and properties of Al-Cu-Mg-Ag alloy exposed at 200℃ with and without stress

The effect of stress on the microstructure and properties of an Al-Cu-Mg-Ag alloy under-aged at 165 ℃ for 2 h during thermal exposure at 200 ℃ was investigated. The tensile experimental results show that the remained tensile strength of both specimens at room temperature after being exposed at 200 ℃ with and without applying stress rises firstly, and then drops with the increasing of exposure time. The peak value of the remained strength reaches 439 MPa for non-stress-exposure for 10 h, and 454 MPa after being exposed with stress loaded for 20 h at 220 MPa. The elongation change is similar to that of strength. After being exposed for 100 h, specimen exposed at 220 MPa still remains a tensile strength of 401 MPa, larger than that exposed without applying stress. TEM shows that the microstructure of under-aged alloy is dominated by - phase mainly and a little θ′ phase. The θ′ and - phases are believed competitive with increasing exposure time. The width of precipitation free zone(PFZ) increases and the granular second phase precipitates at grain-boundary correspondingly. It is shown that the mechanical properties of alloy decrease slightly and present good thermal stability after thermal exposure at 200 ℃ and 220 MPa for 100 h.

Compression analysis of the gray and white matter of the spinal cord

The spinal cord is composed of gray matter and white matter.It is well known that the properties of these two tissues differ considerably.Spinal diseases often present with symptoms that are caused by spinal cord compression.Understanding the mechanical properties of gray and white matter would allow us to gain a deep understanding of the injuries caused to the spinal cord and provide information on the pathological changes to these distinct tissues in several disorders.Previous studies have reported on the physical properties of gray and white matter,however,these were focused on longitudinal tension tests.Little is known about the differences between gray and white matter in terms of their response to compression.We therefore performed mechanical compression test of the gray and white matter of spinal cords harvested from cows and analyzed the differences between them in response to compression.We conducted compression testing of gray matter and white matter to detect possible differences in the collapse rate.We found that increased compression(especially more than 50%compression)resulted in more severe injuries to both the gray and white matter.The present results on the mechanical differences between gray and white matter in response to compression will be useful when interpreting findings from medical imaging in patients with spinal conditions.

Contrasting Behaviours of AC and DC Excited Plasmas in Contact with Liquid

A comparative study of the needle-to-liquid plasma in the continuous mode with DC and AC excitations is detailed in this paper. All plasmas studied here are shown to be glow discharges. This study is based on measurements of several key parameters, including electrical energy, optical emission intensities of active species, rotational and vibrational temperatures, and temperatures of the needle and liquid electrodes. AC plasmas can produce 1.2～5 times higher excited state active species than DC plasmas under the same dissipated power. AC excited liquid plasmas have the highest energy utilization efficiency among the three systems （AC excited plasmas, DC excited plasmas with water anode and DC excited plasmas with water cathode）; most of the energy is used to produce useful species rather than to heat the electrodes and plasmas.

Cooling and Crack Suppression of Bone Material Drilling Based on Microtextured Bit Modeled on Dung Beetle

In recent years,the number of patients with orthopedic diseases such as cervical spondylosis has increased,resulting in an increase in the demand for orthopedic surgery.However,thermal necrosis and bone cracks caused by surgery severely restrict the development and progression of orthopedic surgery.For the material of cutting tool processing bone in bone surgery of drilling high temperature lead to cell death,easy to produce the problem such as crack cause secondary damage effects to restore,in this paper,a bionic drill was designed based on the micro-structure of the dung beetle's head and back.The microstructure configuration parameters were optimized by numerical analysis,and making use of the optical fiber laser marking machine preparation of bionic bit;through drilling test,the mathematical model of drilling temperature and crack generation based on micro-structure characteristic parameters was established by infrared thermal imaging technology and acoustic emission signal technology,and the cooling mechanism and crack suppression strategy were studied.The experimental results show that when the speed is 60 m/min,the cooling effects of the bionic bit T1 and T2 are 15.31%and 19.78%,respectively,and both kinds of bits show obvious crack suppression effect.The research in this paper provides a new idea for precision and efficient machining of bone materials,and the research results will help to improve the design and manufacturing technology and theoretical research level in the field of bone drilling tools.

Diamond Film Synthesis with a DC Plasma Jet:Effect of the Contacting Interface between Substrate and Base on the Substrate Temperature

The contacting interface between the substrate and water-cooled base is vital to the substrate temperature during diamond films deposition by a DC （direct current） plasma jet. The effects of the solid contacting area,conductive materials and fixing between the substrate and the base were investigated without affecting the other parameters. Experimental results indicated that the preferable solid contacting area was more than 60% of total contacting areal; the particular Sn-Pb alloy was more suitable for conducting heat and the concentric fixing ring was a better setting for controlling the substrate temperature. The result was explained in terms of the variable thermal contact resistance at the interface between substrate and base. The diamond films were analyzed by scanning electron microscopy （SEM） for morphology, X-ray diffraction （XRD） for the intensity of characteristic spectroscopy and Raman spectroscopy for structure.

A new method for particle manipulation by combination of dielectrophoresis and field-modulated electroosmotic vortex

A field-modulated electroosmotic flow （FMEOF） in a microchannel can be obtained by applying modulating electric fields in a direction perpendicular to the channel wall. Micro-vortexes are generated around the electrodes along with an EOF due to the surface charge on the modulated wall. When polarizable particles are suspended near the electrodes, they experience dielectrophoretic forces due to a non-uniform electric field. In this paper, micro-vortexes and dielectrophoretic forces are combined to achieve separation and trap different sized particles in a continuous flow. Numerical results indicate that by adjusting the driving electric field parallel to the channel wall and the modulating electric field, the ratio of dielectrophoretic and hydrodynamic forces can be altered. One type of particles can be trapped by micro-vortexes （negative dielectrophoresis （DEP））, and the other particles are transported to the downstream so that the particles are separated. The influence of the electrode length and the channel height on the trapping rate is investigated.