Grooved tuning forks with hierarchical structures have become some of the most widely used piezoelectric quartz microelectromechanical system devices;however,fabricating these devices requires multi-step processes due...Grooved tuning forks with hierarchical structures have become some of the most widely used piezoelectric quartz microelectromechanical system devices;however,fabricating these devices requires multi-step processes due to the complexity of etching of quartz,particularly in specific orientations of the crystal lattice.This paper proposes a one-step fabrication strategy that can form a complete hierarchical structure with only a single etching process using novel lithography patterns.The core principle of this strategy is based on the effect of the size of the groove patterns on quartz etching,whereby trenches of varying depths can be created in a fixed etching time by adjusting the width of the hard mask.Specifically,the device outline and grooved structure can be completed using a seamlessly designed etching pattern and optimized time.Furthermore,the etching structure itself influences the etching results.It was found that dividing a wide trench by including a wall to separate it into two narrow trenches significantly reduces the etching rate,allowing for predictable tuning of the etching rate for wider grooves.This effectively increases the usability and flexibility of the one-step strategy.This was applied to the manufacture of an ultra-small quartz grooved tuning fork resonator with a frequency of 32.768 kHz in a single step,increasing production efficiency by almost 45%and reducing costs by almost 30%compared to current methods.This has great potential for improving the productivity of grooved tuning fork devices.It can also be extended to the fabrication of other quartz crystal devices requiring hierarchical structures.展开更多
The southern margin of the Gurbantunggut Desert,China,is characterized by alternating layers of aeolian and alluvial deposits.Investigating the characteristics of arenaceous sediment in this area is of significant imp...The southern margin of the Gurbantunggut Desert,China,is characterized by alternating layers of aeolian and alluvial deposits.Investigating the characteristics of arenaceous sediment in this area is of significant importance for understanding the interactive processes of wind and water forces,as well as the provenance of sediment.However,there are relatively few investigations on the characteristics of such sediment at present.In this study,we researched three aeolian-alluvial interactive stratigraphic profiles and different types of surface sediment on the desert-oasis transitional zone of southern margin of the Gurbantunggut Desert.Based on the optically stimulated luminescence(OSL)dating of aeolian sand and analyses of quartz sand grain size and surface micro-texture,we explored the aeolian-alluvial environmental change at southern margin of the desert in Holocene,as well as the provenance of sediment.The results indicated that the grain size characteristics of different types of sediment in the stratigraphic profiles were similar to those of modern dune sand,interdune sand,muddy desert surface soil,and riverbed sand.Their frequency curves were unimodal or bimodal,and cumulative probability curves were two-segment or three-segment,mainly composed of suspension load and saltation load.The quartz sand in the sediment at southern margin of the desert had undergone alternating transformation of various exogenic forces,with short transportation distance and time,and sedimentary environment was relatively humid.In Holocene,southern margin of the desert primarily featured braided river deposits,and during intermittent period of river activity,there were also aeolian deposits such as sand sheet deposits,stabilized dune deposits,and mobile dune deposits.The provenance for Holocene alluvial deposits at southern margin of the desert remains relatively constant,with the debris of the Tianshan Mountains being the primary provenance.Aeolian sand is mainly near-source recharge,which is formed by in situ deposition of fluvial or lacustrine materials in southern margin of the desert transported by wind erosion,and its provenance was still the weathered debris of the Tianshan Mountains.In addition,the sand in interior of the desert may be transported by northwest wind in desert-scale,thus affecting the development of dunes in southern margin of the desert.The results of this study provide a reference for understanding the composition and provenance changes of desert sand in the context of global climate change.展开更多
Objective: To explore the application value of disposable grooved negative pressure drainage tubes in rib fracture incision and internal fixation. Methods: Seventy-five patients admitted to our Department of Trauma Su...Objective: To explore the application value of disposable grooved negative pressure drainage tubes in rib fracture incision and internal fixation. Methods: Seventy-five patients admitted to our Department of Trauma Surgery from June 2022 to April 2024 who underwent rib fracture osteotomy and internal fixation were selected. According to the types of drainage tubes left in the patients after the operation, they were divided into the observation group (35 cases who were left with disposable grooved negative pressure drainage tubes) and the control group (40 cases who were left with closed silicone thoracic drainage tubes). Comparison of chest drainage, pain, postoperative complications, secondary chest penetration rate, drain placement time, hospitalization time, and treatment costs were compared between the two groups. Results: The total postoperative chest drainage volume of the observation group was less than that of the control group (P < 0.05);the degree of pain, the incidence of postoperative complications, and the rate of secondary chest puncture in the observation group were lower than that of the control group three days after the operation (P < 0.05);and the time of drain placement in the observation group was shorter than that of the control group (P < 0.05). Conclusion: The application of disposable grooved negative pressure drainage tubes in rib fracture incision and internal fixation can significantly improve patients’ postoperative pain and discomfort, reduce complications, lower the rate of secondary chest penetration, promote patients’ postoperative recovery, decrease the amount of postoperative chest drainage, and shorten the time of drain placement, which is worthy of clinical promotion and application.展开更多
Metamorphic mechanism has the advantages of variable topology and variable degrees of freedom, which can realize the requirements of multi-conditions and multi-tasks, and has a good application prospect. The configura...Metamorphic mechanism has the advantages of variable topology and variable degrees of freedom, which can realize the requirements of multi-conditions and multi-tasks, and has a good application prospect. The configuration transformation is prominent feature of the metamorphic mechanism. The number of constraints or properties of the kinematic pairs provided by the metamorphic kinematic pairs will change under certain conditions, its dynamic performance is much more complex than that of traditional kinematic pairs with immutable constraints. However, the clearance model about traditional kinematic pairs with immutable constraints established by long-term research is difficult to be directly applied to the metachromatic kinematic pairs. Referring to the experience of the traditional kinematic pairs with immutable constraints, the continuous contact model of Metamorphic Groove pin pair with clearance is established. According to the traditional continuous contact model of the kinematic pairs with immutable constraints, the forces between the elements of kinematic pair of the mechanism with clearance and the ideal mechanism without clearance are regarded as the same, and the inertia force and inertia moment of the components are also calculated according to the acceleration of the ideal mechanism. The clearance is regarded as a massless virtual bar with length r. For the rotating pair part, the massless virtual bar length r is the difference between the radius of the shaft and the hole, and for the sliding pair part, the massless virtual bar length r is half of the difference between the height of the slider and the guide groove. According to the new mechanism without gap after adding the imaginary bar, kinetic energy and potential energy of the system are calculated for the two configurations of mechanism with metamorphic Groove pin pair with clearance. The kinetic energy and potential energy of the system are calculated according to the new mechanism without clearance after adding the massless virtual bar. The kinetic energy, potential energy and generalized force are substituted into the Lagrangian equation to obtain the motion equation of the metamorphic mechanism, which lays the foundation for the dynamic performance study of the mechanism with metamorphic groove pin pair with clearance.展开更多
Taking the NACA0012 airfoil as the research object,the bio-inspired herringbone groove array,a new passive control method,is applied to relieve the flow separation under the large angle-of-attack conditions,and its ef...Taking the NACA0012 airfoil as the research object,the bio-inspired herringbone groove array,a new passive control method,is applied to relieve the flow separation under the large angle-of-attack conditions,and its effectiveness and mechanism in delaying airfoil stall are investigated by numerical simulations.The herringbone groove array is placed on the airfoil's upper surface near the trailing edge,and the effects of groove depth and yaw angle on the control effect are investigated.The results demonstrate that different designs of herringbone groove array can effectively broaden the stable operating range of the airfoil,and the application of herringbone groove array with a depth of only 0.00135 times the chord length and a yaw angle of 45°can result in a28.57%increase in the stable operating range.The flow details indicate that a pair of induced vortices with the same strength and opposite direction are formed near the converging line under the combined action of the accumulation effect of small-scale vortices in the grooves and the spanwise migration flow above the grooves.The induced vortices increase the mixing between the main flow and the boundary layer,allowing the boundary layer to gain sufficient energy to withstand the adverse pressure gradient at high angles of attack,effectively delaying airfoil stall.展开更多
Repairing the Ni-based superalloy component remains challenging due to the limited understanding of the role of the defect’s morphology on microstructure and related deformation responses.To address this issue,GH4099...Repairing the Ni-based superalloy component remains challenging due to the limited understanding of the role of the defect’s morphology on microstructure and related deformation responses.To address this issue,GH4099 Ni-based superalloy plate with U-shaped and V-shaped grooves was prepared and repaired by laser-directed energy deposition method using GH4099 powders.Both grooves exhibit three similar regions at the repaired interphase,which are the base metal region with equiaxed grains,repaired region with columnar or elongated equiaxed grains,and a transition region in between.High-temperature gradient in the repaired region induced a high density of substructures,and the repaired region in U-shaped grooves has an even higher temperature gradient due to fewer passes of the melted metal,which induces more metallic carbides in the subgrain boundaries and improves the tensile strength of the repaired samples.However,due to the steep side walls,local vortex might form at the bottom corner of the U-shaped groove,leaving macroscale holes and micro-cracks there.Such defects will decrease the alloy’s ductility.The relationship among groove morphology-macro-and microstructure-mechanical properties is then established,which suggesting the preferred V-shaped groove considering the flatter sidewall and more passes induced near equilibrium microstructure.展开更多
BACKGROUND Groove pancreatitis(GP)is a rare focal chronic pancreatitis of the pancreaticoduodenal groove that is usually diagnosed in chronic alcoholics.However,it is often difficult to differentiate from pancreatic o...BACKGROUND Groove pancreatitis(GP)is a rare focal chronic pancreatitis of the pancreaticoduodenal groove that is usually diagnosed in chronic alcoholics.However,it is often difficult to differentiate from pancreatic or periampullary cancers.In this study,we report a case of GP with the rare symptom of severe gastric outlet obstruction.CASE SUMMARY A 68-year-old man presented to our institution with severe gastric outlet obstruction accompanied by vomiting persisted for 3 days,severe electrolyte imbalance,and altered mental status with cardiac arrest.Differential diagnosis of cancers of the ampulla of Vater or duodenum was difficult due to discordant findings from preoperative imaging and an endoscopic biopsy of the lesion.In addition,the gastric outlet obstruction did not improve with conservative treatment;therefore,pancreatoduodenectomy was performed.Postoperatively,the histological findings revealed multiple cystic lesions in the duodenal wall that were collectively diagnosed as GP.The patient underwent a follow-up 3 years postoperatively and was found to have no postoperative sequelae.CONCLUSION In this case of GP,pancreatoduodenectomy safely treated severe gastric outlet obstruction when a cancer diagnosis could not be excluded.展开更多
A rotary swaging machine was applied to fabricating pipe reduction for miniature inner grooved copper tube （MIGCT） heat pipes. Compared with conventional swaging method, the axial feed of the designed rotary swaging...A rotary swaging machine was applied to fabricating pipe reduction for miniature inner grooved copper tube （MIGCT） heat pipes. Compared with conventional swaging method, the axial feed of the designed rotary swaging machine was reached by a constant pushing force. The deformation of grooves in pipe reduced section during rotary swaging was analyzed. The shrinkage and extensibility of pipe reduction were measured and calculated. Furthermore, four aspects, including outer diameter, surface roughness, extensibility and processing time of pipe reduction, which were influenced by the pushing force, were considered. The results show that the tube wall thickness increases gradually along the z-axis at sinking section. However, the outer diameters, surface roughness and micro-cracks at reduced section tend to decrease along the z-axis. Besides, the effect of variation in the pushing force on the extensibility is limited while an increase in the pushing force results in a decrease of surface roughness. Therefore, a large pushing force within the limit is beneficial to pipe reduction manufacturing during rotary swaging process.展开更多
A 0. 1μm SOI grooved gate pMOSFET with 5.6nm gate oxide is fabricated and demonstrated. The groove depth is 180nm. The transfer characteristics and the output characteristics are shown. At Vds = -1. 5V,the drain satu...A 0. 1μm SOI grooved gate pMOSFET with 5.6nm gate oxide is fabricated and demonstrated. The groove depth is 180nm. The transfer characteristics and the output characteristics are shown. At Vds = -1. 5V,the drain saturation current is 380μA and the off-state leakage current is 1.9nA;the sub-threshold slope is 115mV/dec at Vds = -0. 1V and DIBL factor is 70. 7mV/V. The electrical characteristic comparison between the 0.1μm SOI groovedgate pMOSFET and the 0. 1μm bulk grooved gate one with the same process demonstrates that a 0. 1μm SOI grooved gate pMOSFET has better characteristics in current-driving capability and sub-threshold slope.展开更多
Dynamic failure and ejection characteristics of a periodic grooved Sn surface under unsupported shock loading are studied using a smoothed particle hydrodynamics method. An ＂Eiffel Tower＂ spatial structure is observ...Dynamic failure and ejection characteristics of a periodic grooved Sn surface under unsupported shock loading are studied using a smoothed particle hydrodynamics method. An ＂Eiffel Tower＂ spatial structure is observed, which is com- posed of high-speed jet tip, high-density jet slug, longitudinal tensile sparse zone, and complex broken zone between grooves. It is very different from the spike-bubble structure under supported shocks, and has been validated by detonation loading experiments. In comparison with that under supported shocks at the same peak pressure, the high-speed ejecta decreases obviously, whereas the truncated location of ejecta moves towards the interior of the sample and the total mass of ejecta increases due to the vast existence of low-speed broken materials. The shock wave profile determines mainly the total ejection amount, while the variation of V-groove angle will significantly alter the distribution of middle- and high-speed ejecta, and the maximum ejecta velocity has a linear corretation with the groove angle.展开更多
In order to improve the efficiency of film cooling, numerical investigation was carried out to study the effects of different film-cooled plates on surface heat transfer. Both grooved and non-grooved surfaces were con...In order to improve the efficiency of film cooling, numerical investigation was carried out to study the effects of different film-cooled plates on surface heat transfer. Both grooved and non-grooved surfaces were concerned. The modeling was per- formed using Fluent software with the adoption of Shear-Stress Transport （SST） k-ωmodel as the turbulence closure. The coolant was supplied by a single film cooling hole with an inclination angle of 30°. The Mach numbers for the coolant flow and the mainstream flow were fixed at 0 and 0.6, respectively. At three blowing ratios of 0.5, 1.0 and 1.5, the aerodynamic behaviour of the mixing process as well as the heat transfer performance of the film cooling were presented. The numerical results were validated using experimental data extracted from a benchmark test. Good agreements between numerical results and the ex- perimental data were observed. For the film cooling efficiency, it shows that both local and laterally averaged cooling effectiveness can be improved by the non-smooth surface at different blowing ratios. Using the grooved surface, the turbulence intensity upon the plate can be reduced notably, and the mixing between the two flows is weakened due to the reduced turbu lence level. The results indicate that the cooling effectiveness of film cooling can be enhanced by applying the grooved surface.展开更多
A computational fluid dynamics （CFD） simulation method based on 3-D Navier Stokes equation and Arbitrary Lagrangian Eulerian （ALE） method is presented to analyze the grooved slip- per performance of piston pump. T...A computational fluid dynamics （CFD） simulation method based on 3-D Navier Stokes equation and Arbitrary Lagrangian Eulerian （ALE） method is presented to analyze the grooved slip- per performance of piston pump. The moving domain of grooved slipper is transformed into a fixed reference domain by the ALE method, which makes it convenient to take the effects of rotate speed, body force, temperature, and oil viscosity into account. A geometric model to express the complex structure, which covers the orifice of piston and slipper, vented groove and the oil film, is constructed. Corresponding to different oil film thicknesses calculated in light of hydrostatic equilibrium theory and boundary conditions, a set of simulations is conducted in COMSOL to analyze the pump characteristics and effects of geometry （groove width and radius, orifice size） on these characteristics. Furthermore, the mechanics and hydraulics analyses are employed to validate the CFD model, and there is an excellent agreement between simulation and analytical results. The simulation results show that the sealing land radius, orifice size and groove width all dramatically affect the slipper behavior, and an optimum tradeoff among these factors is conducive to optimizing the pump design.展开更多
To study the efect of micro-texture on the cutting performance of polyrystalline cubic boron nitide(PCBN)tools,five types of micro-textures(circular pits,eliptical grooves,transverse grooves,composite grooves,and wavy...To study the efect of micro-texture on the cutting performance of polyrystalline cubic boron nitide(PCBN)tools,five types of micro-textures(circular pits,eliptical grooves,transverse grooves,composite grooves,and wavy grooves)were applied to the rake surface of PCBN tools by an optical fber laser marking machine.Through a combination of three dimensional cutting simulations and experiments,the influences of micro-texture on chip-tool contact area,cutting force,chip morphology,shear angle,and surface roughness during the cuting process were analyzed.The results indicated that the chip--tool contact area and cutting force of both non-textured and micro textured tools increased with increasing cutting speed,while the shear angle decreased with increasing cutting speed.The chip-tool contact area and cutting force of the five types of micro-textured tools were smaller than those of the non textured tool The chip-tool contact area and cutting force obtained by the wavy-groove micro textured tool were the smallest.The chip radius produced by the five types of micro-textured tools was smaller than that produced by the non-textured tool,and the chip morphology was more stable.The transverse-groove micro-textured tool had a better chip breaking efect.The chip rnadius generated by the lliptical groove micro textured tool was 0.96 cm,while that generated by the wavy-groove tool varied from 0.55 cm to 1.26 cm.The presence of a micro-texture reduced the surface roughness of the workpiece by 11.73%-56.7%.Under the same cutting conditions,the five types of micro-textured tools gave a smaller chip--tool contact area,cutting force,chip radius,and surface roughness and a larger shear angle than the non-textured tool.In addition,the elliptical groove and wavy-groove micro-textured tools had better cuting performance.展开更多
Annular grooved projectiles(AGPs)have drawn ongoing concerns as an advanced penetrator for their excellent anti-rebound capability in impacting metal plates.They could become embedded solidly in the target surface dur...Annular grooved projectiles(AGPs)have drawn ongoing concerns as an advanced penetrator for their excellent anti-rebound capability in impacting metal plates.They could become embedded solidly in the target surface during low-velocity impact.In this investigation,the firm embedding behavior of AGP was observed by impact experiments.Corresponding numerical simulations provided a better understanding of this process.Experimental and numerical results indicated that the firm embedding behavior of AGP was mainly due to the filling-material in the groove rather than the friction between the projectile and target,unlike traditional shape such as conical projectile.According to observation,firm embedding process can generally be subdivided into four stages:initial-cratering stage,groove-filling stage,fillingmaterial failure stage and rebound vibration stage.Moreover,the damage mechanics of target material around crater was obtained through microscopic tests.A comparison of the cross-sectional figures between the experiment and simulation proved that the analysis and the proposed method were reasonable and feasible,which further demonstrated that the firm embedding behavior has application potential in new concept warheads.展开更多
To study the effect of impingement surface geometry, a cavitation erosion experiment was conducted using a submerged cavitating jet rig with hydraulic oil. The test setup comprised a test chamber with a long-orifice n...To study the effect of impingement surface geometry, a cavitation erosion experiment was conducted using a submerged cavitating jet rig with hydraulic oil. The test setup comprised a test chamber with a long-orifice nozzle, a hydraulic pump with an electric motor, hydraulic auxiliaries, including valves, a cooler, a filter, a reservoir, and measuring instruments, including pressure gages and a thermometer. Hexahedral specimens made of aluminum alloy with flat and grooved surfaces and oblique angles were prepared. Hydraulic oil with a viscosity grade of 32 was used at 40°C as the test fluid. The upstream absolute pressure was kept at 10.1 MPa and the cavitation numbers were set at 0.02 - 0.04. The results of this experiment yielded the following conclusions. The mass loss of the grooved specimens did not increase monotonically as the exposure time increased. The standoff distances at the maximum mass loss for the flat and grooved specimens were almost equivalent. The mass loss decreased as the oblique angle increased and the cavitation number increased, regardless of the presence of grooves. The surfaces were eroded in a ring-like region, but the region elongated as the angle increased. For the grooved specimens, the ridges on the ring were eroded, and when the directions of the grooves and the flow matched, the roots and flanks were severely eroded.展开更多
A novel particle-size conveying model was established to examine the effects of the dimension relationships of the groove depth and particle size on the solids conveying mechanism of the helically grooved feed section...A novel particle-size conveying model was established to examine the effects of the dimension relationships of the groove depth and particle size on the solids conveying mechanism of the helically grooved feed section. In the model, one or two shear interfaces were proposed based on the dimension relationships of the groove depth and particle size, and the solid-plug embedded in the groove and screw channel were divided into two or three layers by the shear interfaces to consider the solids conveying mechanism of each layer by the boundary condition equation for positive conveying. By the particle-size model, the effects of different dimension relationships on the transformation of solids conveying mechanisms between the friction-drag conveying and the positive conveying were discussed and compared with the on-line measuring experimental data. The results showed that the shear interfaces among the solids existed indeed and the dimension relationships determined the conveying mechanism and the throughput of helically grooved extruders, which was well confirmed by the excellent consistence between the predicted and measured data.展开更多
Zhang Y J et al.[Zhang Y J,Zhang Z D,Zhu L Z and Xuan L 2011 Liquid Cryst.38 355] investigated the effects of finite polar anchoring on the azimuthal anchoring energy at a grooved interface,in which polar anchoring wa...Zhang Y J et al.[Zhang Y J,Zhang Z D,Zhu L Z and Xuan L 2011 Liquid Cryst.38 355] investigated the effects of finite polar anchoring on the azimuthal anchoring energy at a grooved interface,in which polar anchoring was isotropic in the local tangent plane of the surface.In this paper,we investigate the effects of both isotropic and anisotropic polar anchoring on the surface anchoring energy in the frame of Fukuda et al.’s theory.The results show that anisotropic polar anchoring strengthens the azimuthal anchoring of grooved surfaces.In the one-elastic-constant approximation（K11 = K22 = K33 = K）,the surface-groove-induced azimuthal anchoring energy is entirely consistent with the result of Faetti,and it reduces to the original result of Berreman with an increase in polar anchoring.Moreover,the contribution of the surface-like elastic term to the Rapini-Papoular anchoring energy is zero.展开更多
Surface topographies such as micrometric edges and grooves have been widely used to improve neuron outgrowth.However,finding the mechanism of neuron–surface interactions on grooved substrates remains a challenge.In t...Surface topographies such as micrometric edges and grooves have been widely used to improve neuron outgrowth.However,finding the mechanism of neuron–surface interactions on grooved substrates remains a challenge.In this work,PC12 cells and chick forebrain neurons(CFNs)were cultured on grooved and smooth polyacrylonitrile substrates.It was found that CFNs showed a tendency of growing across groove ridges;while PC12 cells were only observed to grow in the longitudinal direction of grooves.To further investigate these observations,a 3D physical model of axonal outgrowth was developed.In this model,axon shafts are simulated as elastic 3D beams,accounting for the axon outgrowth as well as the focal contacts between axons and substrates.Moreover,the bending direction of axon tips during groove ridge crossing is governed by the energy minimization principle.Our physical model predicts that axonal groove ridge crossing is contributed by the bending compliance of axons,caused by lower Young’s modulus and smaller diameters.This work will aid the understanding of the mechanisms involved in axonal alignment and elongation of neurons guided by grooved substrates,and the obtained insights can be used to enhance the design of instructive scaffolds for nerve tissue engineering and regeneration applications.展开更多
Aluminum alloy plates were explosively cladded to stainless steel plates with trapezoidal grooves on the mating surface.The process parameters viz,loading ratio,standoff distance and flyer plate thickness were varied ...Aluminum alloy plates were explosively cladded to stainless steel plates with trapezoidal grooves on the mating surface.The process parameters viz,loading ratio,standoff distance and flyer plate thickness were varied based on the Taguchi analogy.The variation in the process parameters alters the kinetic energy dissipation and the deformation work performed at the interface,and dictates the interfacial wave amplitude and the mechanical strength of the dissimilar explosive clad.The optimum level of process parameters for attaining higher tensile and shear strength is computed by signal-to-noise ratio.Further,a mathematical model is developed for calculating tensile and shear strength of the clad,based on the regression analysis using statistical software Minitab-16,and the level of fit is determined by analysis of variance.展开更多
文摘Grooved tuning forks with hierarchical structures have become some of the most widely used piezoelectric quartz microelectromechanical system devices;however,fabricating these devices requires multi-step processes due to the complexity of etching of quartz,particularly in specific orientations of the crystal lattice.This paper proposes a one-step fabrication strategy that can form a complete hierarchical structure with only a single etching process using novel lithography patterns.The core principle of this strategy is based on the effect of the size of the groove patterns on quartz etching,whereby trenches of varying depths can be created in a fixed etching time by adjusting the width of the hard mask.Specifically,the device outline and grooved structure can be completed using a seamlessly designed etching pattern and optimized time.Furthermore,the etching structure itself influences the etching results.It was found that dividing a wide trench by including a wall to separate it into two narrow trenches significantly reduces the etching rate,allowing for predictable tuning of the etching rate for wider grooves.This effectively increases the usability and flexibility of the one-step strategy.This was applied to the manufacture of an ultra-small quartz grooved tuning fork resonator with a frequency of 32.768 kHz in a single step,increasing production efficiency by almost 45%and reducing costs by almost 30%compared to current methods.This has great potential for improving the productivity of grooved tuning fork devices.It can also be extended to the fabrication of other quartz crystal devices requiring hierarchical structures.
基金the National Natural Science Foundation of China(42071011)the 2023 Annual Postgraduate Research and Innovation Foundation of Fujian Normal University,China.
文摘The southern margin of the Gurbantunggut Desert,China,is characterized by alternating layers of aeolian and alluvial deposits.Investigating the characteristics of arenaceous sediment in this area is of significant importance for understanding the interactive processes of wind and water forces,as well as the provenance of sediment.However,there are relatively few investigations on the characteristics of such sediment at present.In this study,we researched three aeolian-alluvial interactive stratigraphic profiles and different types of surface sediment on the desert-oasis transitional zone of southern margin of the Gurbantunggut Desert.Based on the optically stimulated luminescence(OSL)dating of aeolian sand and analyses of quartz sand grain size and surface micro-texture,we explored the aeolian-alluvial environmental change at southern margin of the desert in Holocene,as well as the provenance of sediment.The results indicated that the grain size characteristics of different types of sediment in the stratigraphic profiles were similar to those of modern dune sand,interdune sand,muddy desert surface soil,and riverbed sand.Their frequency curves were unimodal or bimodal,and cumulative probability curves were two-segment or three-segment,mainly composed of suspension load and saltation load.The quartz sand in the sediment at southern margin of the desert had undergone alternating transformation of various exogenic forces,with short transportation distance and time,and sedimentary environment was relatively humid.In Holocene,southern margin of the desert primarily featured braided river deposits,and during intermittent period of river activity,there were also aeolian deposits such as sand sheet deposits,stabilized dune deposits,and mobile dune deposits.The provenance for Holocene alluvial deposits at southern margin of the desert remains relatively constant,with the debris of the Tianshan Mountains being the primary provenance.Aeolian sand is mainly near-source recharge,which is formed by in situ deposition of fluvial or lacustrine materials in southern margin of the desert transported by wind erosion,and its provenance was still the weathered debris of the Tianshan Mountains.In addition,the sand in interior of the desert may be transported by northwest wind in desert-scale,thus affecting the development of dunes in southern margin of the desert.The results of this study provide a reference for understanding the composition and provenance changes of desert sand in the context of global climate change.
文摘Objective: To explore the application value of disposable grooved negative pressure drainage tubes in rib fracture incision and internal fixation. Methods: Seventy-five patients admitted to our Department of Trauma Surgery from June 2022 to April 2024 who underwent rib fracture osteotomy and internal fixation were selected. According to the types of drainage tubes left in the patients after the operation, they were divided into the observation group (35 cases who were left with disposable grooved negative pressure drainage tubes) and the control group (40 cases who were left with closed silicone thoracic drainage tubes). Comparison of chest drainage, pain, postoperative complications, secondary chest penetration rate, drain placement time, hospitalization time, and treatment costs were compared between the two groups. Results: The total postoperative chest drainage volume of the observation group was less than that of the control group (P < 0.05);the degree of pain, the incidence of postoperative complications, and the rate of secondary chest puncture in the observation group were lower than that of the control group three days after the operation (P < 0.05);and the time of drain placement in the observation group was shorter than that of the control group (P < 0.05). Conclusion: The application of disposable grooved negative pressure drainage tubes in rib fracture incision and internal fixation can significantly improve patients’ postoperative pain and discomfort, reduce complications, lower the rate of secondary chest penetration, promote patients’ postoperative recovery, decrease the amount of postoperative chest drainage, and shorten the time of drain placement, which is worthy of clinical promotion and application.
文摘Metamorphic mechanism has the advantages of variable topology and variable degrees of freedom, which can realize the requirements of multi-conditions and multi-tasks, and has a good application prospect. The configuration transformation is prominent feature of the metamorphic mechanism. The number of constraints or properties of the kinematic pairs provided by the metamorphic kinematic pairs will change under certain conditions, its dynamic performance is much more complex than that of traditional kinematic pairs with immutable constraints. However, the clearance model about traditional kinematic pairs with immutable constraints established by long-term research is difficult to be directly applied to the metachromatic kinematic pairs. Referring to the experience of the traditional kinematic pairs with immutable constraints, the continuous contact model of Metamorphic Groove pin pair with clearance is established. According to the traditional continuous contact model of the kinematic pairs with immutable constraints, the forces between the elements of kinematic pair of the mechanism with clearance and the ideal mechanism without clearance are regarded as the same, and the inertia force and inertia moment of the components are also calculated according to the acceleration of the ideal mechanism. The clearance is regarded as a massless virtual bar with length r. For the rotating pair part, the massless virtual bar length r is the difference between the radius of the shaft and the hole, and for the sliding pair part, the massless virtual bar length r is half of the difference between the height of the slider and the guide groove. According to the new mechanism without gap after adding the imaginary bar, kinetic energy and potential energy of the system are calculated for the two configurations of mechanism with metamorphic Groove pin pair with clearance. The kinetic energy and potential energy of the system are calculated according to the new mechanism without clearance after adding the massless virtual bar. The kinetic energy, potential energy and generalized force are substituted into the Lagrangian equation to obtain the motion equation of the metamorphic mechanism, which lays the foundation for the dynamic performance study of the mechanism with metamorphic groove pin pair with clearance.
基金supported by the National Natural Science Foundation of China(No.52306058)the Natural Science Foundation of Tianjin Municipal Science and Technology Commission,China(No.22JCQNJC00050)。
文摘Taking the NACA0012 airfoil as the research object,the bio-inspired herringbone groove array,a new passive control method,is applied to relieve the flow separation under the large angle-of-attack conditions,and its effectiveness and mechanism in delaying airfoil stall are investigated by numerical simulations.The herringbone groove array is placed on the airfoil's upper surface near the trailing edge,and the effects of groove depth and yaw angle on the control effect are investigated.The results demonstrate that different designs of herringbone groove array can effectively broaden the stable operating range of the airfoil,and the application of herringbone groove array with a depth of only 0.00135 times the chord length and a yaw angle of 45°can result in a28.57%increase in the stable operating range.The flow details indicate that a pair of induced vortices with the same strength and opposite direction are formed near the converging line under the combined action of the accumulation effect of small-scale vortices in the grooves and the spanwise migration flow above the grooves.The induced vortices increase the mixing between the main flow and the boundary layer,allowing the boundary layer to gain sufficient energy to withstand the adverse pressure gradient at high angles of attack,effectively delaying airfoil stall.
基金support of the Mount Taishan Industrial Leading Talent Project.
文摘Repairing the Ni-based superalloy component remains challenging due to the limited understanding of the role of the defect’s morphology on microstructure and related deformation responses.To address this issue,GH4099 Ni-based superalloy plate with U-shaped and V-shaped grooves was prepared and repaired by laser-directed energy deposition method using GH4099 powders.Both grooves exhibit three similar regions at the repaired interphase,which are the base metal region with equiaxed grains,repaired region with columnar or elongated equiaxed grains,and a transition region in between.High-temperature gradient in the repaired region induced a high density of substructures,and the repaired region in U-shaped grooves has an even higher temperature gradient due to fewer passes of the melted metal,which induces more metallic carbides in the subgrain boundaries and improves the tensile strength of the repaired samples.However,due to the steep side walls,local vortex might form at the bottom corner of the U-shaped groove,leaving macroscale holes and micro-cracks there.Such defects will decrease the alloy’s ductility.The relationship among groove morphology-macro-and microstructure-mechanical properties is then established,which suggesting the preferred V-shaped groove considering the flatter sidewall and more passes induced near equilibrium microstructure.
文摘BACKGROUND Groove pancreatitis(GP)is a rare focal chronic pancreatitis of the pancreaticoduodenal groove that is usually diagnosed in chronic alcoholics.However,it is often difficult to differentiate from pancreatic or periampullary cancers.In this study,we report a case of GP with the rare symptom of severe gastric outlet obstruction.CASE SUMMARY A 68-year-old man presented to our institution with severe gastric outlet obstruction accompanied by vomiting persisted for 3 days,severe electrolyte imbalance,and altered mental status with cardiac arrest.Differential diagnosis of cancers of the ampulla of Vater or duodenum was difficult due to discordant findings from preoperative imaging and an endoscopic biopsy of the lesion.In addition,the gastric outlet obstruction did not improve with conservative treatment;therefore,pancreatoduodenectomy was performed.Postoperatively,the histological findings revealed multiple cystic lesions in the duodenal wall that were collectively diagnosed as GP.The patient underwent a follow-up 3 years postoperatively and was found to have no postoperative sequelae.CONCLUSION In this case of GP,pancreatoduodenectomy safely treated severe gastric outlet obstruction when a cancer diagnosis could not be excluded.
基金Project (U0834002) supported by the Key Program of NSFC Guangdong Joint Funds of ChinaProjects (51005079, 20976055) supported by the National Natural Science Foundation of China+1 种基金Project (10451064101005146) supported by the Natural Science Foundation of Guangdong Province, ChinaProject (20100172120001) supported by Specialized Research Fund for the Doctoral Program of Higher Education, China
文摘A rotary swaging machine was applied to fabricating pipe reduction for miniature inner grooved copper tube （MIGCT） heat pipes. Compared with conventional swaging method, the axial feed of the designed rotary swaging machine was reached by a constant pushing force. The deformation of grooves in pipe reduced section during rotary swaging was analyzed. The shrinkage and extensibility of pipe reduction were measured and calculated. Furthermore, four aspects, including outer diameter, surface roughness, extensibility and processing time of pipe reduction, which were influenced by the pushing force, were considered. The results show that the tube wall thickness increases gradually along the z-axis at sinking section. However, the outer diameters, surface roughness and micro-cracks at reduced section tend to decrease along the z-axis. Besides, the effect of variation in the pushing force on the extensibility is limited while an increase in the pushing force results in a decrease of surface roughness. Therefore, a large pushing force within the limit is beneficial to pipe reduction manufacturing during rotary swaging process.
文摘A 0. 1μm SOI grooved gate pMOSFET with 5.6nm gate oxide is fabricated and demonstrated. The groove depth is 180nm. The transfer characteristics and the output characteristics are shown. At Vds = -1. 5V,the drain saturation current is 380μA and the off-state leakage current is 1.9nA;the sub-threshold slope is 115mV/dec at Vds = -0. 1V and DIBL factor is 70. 7mV/V. The electrical characteristic comparison between the 0.1μm SOI groovedgate pMOSFET and the 0. 1μm bulk grooved gate one with the same process demonstrates that a 0. 1μm SOI grooved gate pMOSFET has better characteristics in current-driving capability and sub-threshold slope.
基金Project supported by the Joint Fund of the National Natural Science Foundation of China and the China Academy of Engineering Physics(Grant No.U1530261)the National Natural Science Foundation of China(Grant Nos.11402032 and 11502030)the Science Challenge Project,China(Grant No.TZ2016001)
文摘Dynamic failure and ejection characteristics of a periodic grooved Sn surface under unsupported shock loading are studied using a smoothed particle hydrodynamics method. An ＂Eiffel Tower＂ spatial structure is observed, which is com- posed of high-speed jet tip, high-density jet slug, longitudinal tensile sparse zone, and complex broken zone between grooves. It is very different from the spike-bubble structure under supported shocks, and has been validated by detonation loading experiments. In comparison with that under supported shocks at the same peak pressure, the high-speed ejecta decreases obviously, whereas the truncated location of ejecta moves towards the interior of the sample and the total mass of ejecta increases due to the vast existence of low-speed broken materials. The shock wave profile determines mainly the total ejection amount, while the variation of V-groove angle will significantly alter the distribution of middle- and high-speed ejecta, and the maximum ejecta velocity has a linear corretation with the groove angle.
文摘In order to improve the efficiency of film cooling, numerical investigation was carried out to study the effects of different film-cooled plates on surface heat transfer. Both grooved and non-grooved surfaces were concerned. The modeling was per- formed using Fluent software with the adoption of Shear-Stress Transport （SST） k-ωmodel as the turbulence closure. The coolant was supplied by a single film cooling hole with an inclination angle of 30°. The Mach numbers for the coolant flow and the mainstream flow were fixed at 0 and 0.6, respectively. At three blowing ratios of 0.5, 1.0 and 1.5, the aerodynamic behaviour of the mixing process as well as the heat transfer performance of the film cooling were presented. The numerical results were validated using experimental data extracted from a benchmark test. Good agreements between numerical results and the ex- perimental data were observed. For the film cooling efficiency, it shows that both local and laterally averaged cooling effectiveness can be improved by the non-smooth surface at different blowing ratios. Using the grooved surface, the turbulence intensity upon the plate can be reduced notably, and the mixing between the two flows is weakened due to the reduced turbu lence level. The results indicate that the cooling effectiveness of film cooling can be enhanced by applying the grooved surface.
基金the support from the National Natural Science Foundation of China(No.51205007)the Specialized Research Fund for the Doctoral Program of Chinese Higher Education(No.20131102120019)
文摘A computational fluid dynamics （CFD） simulation method based on 3-D Navier Stokes equation and Arbitrary Lagrangian Eulerian （ALE） method is presented to analyze the grooved slip- per performance of piston pump. The moving domain of grooved slipper is transformed into a fixed reference domain by the ALE method, which makes it convenient to take the effects of rotate speed, body force, temperature, and oil viscosity into account. A geometric model to express the complex structure, which covers the orifice of piston and slipper, vented groove and the oil film, is constructed. Corresponding to different oil film thicknesses calculated in light of hydrostatic equilibrium theory and boundary conditions, a set of simulations is conducted in COMSOL to analyze the pump characteristics and effects of geometry （groove width and radius, orifice size） on these characteristics. Furthermore, the mechanics and hydraulics analyses are employed to validate the CFD model, and there is an excellent agreement between simulation and analytical results. The simulation results show that the sealing land radius, orifice size and groove width all dramatically affect the slipper behavior, and an optimum tradeoff among these factors is conducive to optimizing the pump design.
基金the Basic Scientific Research Program of the Educational Commission of Liaoning Province,China(Grant No.L2017LQN024).
文摘To study the efect of micro-texture on the cutting performance of polyrystalline cubic boron nitide(PCBN)tools,five types of micro-textures(circular pits,eliptical grooves,transverse grooves,composite grooves,and wavy grooves)were applied to the rake surface of PCBN tools by an optical fber laser marking machine.Through a combination of three dimensional cutting simulations and experiments,the influences of micro-texture on chip-tool contact area,cutting force,chip morphology,shear angle,and surface roughness during the cuting process were analyzed.The results indicated that the chip--tool contact area and cutting force of both non-textured and micro textured tools increased with increasing cutting speed,while the shear angle decreased with increasing cutting speed.The chip-tool contact area and cutting force of the five types of micro-textured tools were smaller than those of the non textured tool The chip-tool contact area and cutting force obtained by the wavy-groove micro textured tool were the smallest.The chip radius produced by the five types of micro-textured tools was smaller than that produced by the non-textured tool,and the chip morphology was more stable.The transverse-groove micro-textured tool had a better chip breaking efect.The chip rnadius generated by the lliptical groove micro textured tool was 0.96 cm,while that generated by the wavy-groove tool varied from 0.55 cm to 1.26 cm.The presence of a micro-texture reduced the surface roughness of the workpiece by 11.73%-56.7%.Under the same cutting conditions,the five types of micro-textured tools gave a smaller chip--tool contact area,cutting force,chip radius,and surface roughness and a larger shear angle than the non-textured tool.In addition,the elliptical groove and wavy-groove micro-textured tools had better cuting performance.
基金financially supported by the National Natural Science Foundation of China [grant number 11472053]
文摘Annular grooved projectiles(AGPs)have drawn ongoing concerns as an advanced penetrator for their excellent anti-rebound capability in impacting metal plates.They could become embedded solidly in the target surface during low-velocity impact.In this investigation,the firm embedding behavior of AGP was observed by impact experiments.Corresponding numerical simulations provided a better understanding of this process.Experimental and numerical results indicated that the firm embedding behavior of AGP was mainly due to the filling-material in the groove rather than the friction between the projectile and target,unlike traditional shape such as conical projectile.According to observation,firm embedding process can generally be subdivided into four stages:initial-cratering stage,groove-filling stage,fillingmaterial failure stage and rebound vibration stage.Moreover,the damage mechanics of target material around crater was obtained through microscopic tests.A comparison of the cross-sectional figures between the experiment and simulation proved that the analysis and the proposed method were reasonable and feasible,which further demonstrated that the firm embedding behavior has application potential in new concept warheads.
文摘To study the effect of impingement surface geometry, a cavitation erosion experiment was conducted using a submerged cavitating jet rig with hydraulic oil. The test setup comprised a test chamber with a long-orifice nozzle, a hydraulic pump with an electric motor, hydraulic auxiliaries, including valves, a cooler, a filter, a reservoir, and measuring instruments, including pressure gages and a thermometer. Hexahedral specimens made of aluminum alloy with flat and grooved surfaces and oblique angles were prepared. Hydraulic oil with a viscosity grade of 32 was used at 40°C as the test fluid. The upstream absolute pressure was kept at 10.1 MPa and the cavitation numbers were set at 0.02 - 0.04. The results of this experiment yielded the following conclusions. The mass loss of the grooved specimens did not increase monotonically as the exposure time increased. The standoff distances at the maximum mass loss for the flat and grooved specimens were almost equivalent. The mass loss decreased as the oblique angle increased and the cavitation number increased, regardless of the presence of grooves. The surfaces were eroded in a ring-like region, but the region elongated as the angle increased. For the grooved specimens, the ridges on the ring were eroded, and when the directions of the grooves and the flow matched, the roots and flanks were severely eroded.
基金Funded by the National Natural Science Foundation of China(No.50873014)
文摘A novel particle-size conveying model was established to examine the effects of the dimension relationships of the groove depth and particle size on the solids conveying mechanism of the helically grooved feed section. In the model, one or two shear interfaces were proposed based on the dimension relationships of the groove depth and particle size, and the solid-plug embedded in the groove and screw channel were divided into two or three layers by the shear interfaces to consider the solids conveying mechanism of each layer by the boundary condition equation for positive conveying. By the particle-size model, the effects of different dimension relationships on the transformation of solids conveying mechanisms between the friction-drag conveying and the positive conveying were discussed and compared with the on-line measuring experimental data. The results showed that the shear interfaces among the solids existed indeed and the dimension relationships determined the conveying mechanism and the throughput of helically grooved extruders, which was well confirmed by the excellent consistence between the predicted and measured data.
基金Project supported by the Natural Science Foundation of Hebei Province,China (Grant No. A2010000004)the National Natural Science Foundation of China (Grant No. 60736042)the Key Subject Construction Project of Hebei Provincial University,China
文摘Zhang Y J et al.[Zhang Y J,Zhang Z D,Zhu L Z and Xuan L 2011 Liquid Cryst.38 355] investigated the effects of finite polar anchoring on the azimuthal anchoring energy at a grooved interface,in which polar anchoring was isotropic in the local tangent plane of the surface.In this paper,we investigate the effects of both isotropic and anisotropic polar anchoring on the surface anchoring energy in the frame of Fukuda et al.’s theory.The results show that anisotropic polar anchoring strengthens the azimuthal anchoring of grooved surfaces.In the one-elastic-constant approximation（K11 = K22 = K33 = K）,the surface-groove-induced azimuthal anchoring energy is entirely consistent with the result of Faetti,and it reduces to the original result of Berreman with an increase in polar anchoring.Moreover,the contribution of the surface-like elastic term to the Rapini-Papoular anchoring energy is zero.
基金This study was partially supported by the National Key Research and Development Program of China(Grant No.2018YFA0703000)the Key Research and Development Program of Zhejiang Province(Grant No.2017C01063)+2 种基金the Science Fund for Creative Research Groups of the National Natural Science Foundation of China(Grant No.51821093)the National Natural Science Foundation of China(Grant Nos.U1609207,11672268)ZJU Scholarship for Outstanding Doctoral Candidates and Scholarship Program supported by China Scholarship Council(No.201906320187).
文摘Surface topographies such as micrometric edges and grooves have been widely used to improve neuron outgrowth.However,finding the mechanism of neuron–surface interactions on grooved substrates remains a challenge.In this work,PC12 cells and chick forebrain neurons(CFNs)were cultured on grooved and smooth polyacrylonitrile substrates.It was found that CFNs showed a tendency of growing across groove ridges;while PC12 cells were only observed to grow in the longitudinal direction of grooves.To further investigate these observations,a 3D physical model of axonal outgrowth was developed.In this model,axon shafts are simulated as elastic 3D beams,accounting for the axon outgrowth as well as the focal contacts between axons and substrates.Moreover,the bending direction of axon tips during groove ridge crossing is governed by the energy minimization principle.Our physical model predicts that axonal groove ridge crossing is contributed by the bending compliance of axons,caused by lower Young’s modulus and smaller diameters.This work will aid the understanding of the mechanisms involved in axonal alignment and elongation of neurons guided by grooved substrates,and the obtained insights can be used to enhance the design of instructive scaffolds for nerve tissue engineering and regeneration applications.
文摘Aluminum alloy plates were explosively cladded to stainless steel plates with trapezoidal grooves on the mating surface.The process parameters viz,loading ratio,standoff distance and flyer plate thickness were varied based on the Taguchi analogy.The variation in the process parameters alters the kinetic energy dissipation and the deformation work performed at the interface,and dictates the interfacial wave amplitude and the mechanical strength of the dissimilar explosive clad.The optimum level of process parameters for attaining higher tensile and shear strength is computed by signal-to-noise ratio.Further,a mathematical model is developed for calculating tensile and shear strength of the clad,based on the regression analysis using statistical software Minitab-16,and the level of fit is determined by analysis of variance.
