cavity

摘要： In this study,a duct is considered and special attention is paid to a passive method for the control of the base pressure relying on the use of a cavity with a variable aspect ratio.The Mach number considered is 1.8,and the area ratio of the duct is 2.56.In particular,two cavities are examined,their sizes being 3:3 and 6:3.The used L/D spans the interval 1–10 while the NPRs(nozzle pressure ratio)range from 2 to 9.The results show that the control becomes effective once the nozzles are correctly expanded or under-expanded.The pressure contours at different NPR and L/D are presented.It is shown that the NPR and cavity location strongly influence the base pressure.The NPR,Mach number,and cavity aspect ratio have a strong effect on the base pressure in the wake region.

摘要： Dear editor,Traumatic pneumocephalus describes the presence of gas in the brain cavity,with an incidence of 0.5%–9.7%.^([1])It was first reported by Luckett.^([2])It is primarily self-limiting.However,traumatic tension pneumocephalus(TTP)due to increased intracranial gas is extremely rare.It is a neurological emergency manifested by headaches,seizures,loss of consciousness,and even death resulting from high intracranial pressure.

摘要： The most important components of electrical vehicles are the battery and the related cooling system.These subsystems play a major role in determining the overall electric vehicle performances.In this study,a novel cooling system with fluid in the battery cell is proposed,by which the energy storage system can be optimized through control of the temperature of the batteries.A sensitivity analysis is conducted considering the maximum temperature,the heat rate,the coolant temperature,and the geometry of the cavities.The numerical simulations show that the parameters for the trapezoidal compartment have an impact on the thermal performance of battery.An optimal geometry is proposed accordingly.It is concluded that for high values of Reynolds number for which the flow becomes turbulent,a decrease in the battery temperature can be obtained thereby avoiding thermal stresses.

摘要： When a high-speed body with cavity passes through water-air free surface and exits water,its mechanical environment and dynamic characteristics change significantly due to the great difference in density and viscosity between water and air.With focusing on this problem,the Computational Fluid Dynamics(CFD)method is applied to perform numerical calculation on the process of this vapor-liquid-gas flow during the water exit of a high-speed cylinder,with the Volume of Fraction(VOF)multiphase flow interface-capturing techniques and the overset grid technology.After the verification and validation of the CFD model through mesh convergence study and a water-entry experiment,cavity evolution and flow characteristics including pressure and velocity distribution during the water exit are analyzed.The effects of different initial velocities on the pressure distribution and drag characteristics of the cylinder are investigated.Calculated results show that the cavity collapse during water exit causes strong pressure fluctuation on the cylinder;when the cylinder exits water enveloped in a supercavity,the pressure distribution on its wall surface and surrounding water region is relatively uniform,and the drag changes gently,and thus the cylinder has good motion stability.

摘要： Sinkholes and cavities can represent serious hazards to human safety and urban infrastructures,cause roadbed subsidence,and so on.It is therefore essential to evaluate various sinkholes in different depths and sizes to assess the risk of collapse.This paper evaluates the effect of different cavities on Rayleigh-wave propagation and body(P)wave refraction.Rayleigh(R)wave propagation is analyzed according to the classical multi-channel analysis of surface waves(MASW)method also considering the R-wave backscattering.Synthetic seismic traces are computed by means of finite element modeling(FEM)for cavity and intrusion at different depths and sizes.Furthermore,field acquisition data is used to verify the detection effect of a cavity on R-and P-waves.The results show that the presence of backscattered R-waves and the changes in the R-wave velocity spectrum can help in cavity identification.Additional possible evidence is represented by significant changes in the refraction travel times over the cavity location.It can be concluded that the field data are in good agreement with the synthetic,and it could be effective to consider the results of both R-and P-wave analysis in order to efficiently identify the cavities.

摘要： Hepatocellular carcinoma(HCC)is a common form of cancer,and it ranked sixth for cancer incidence and fourth for cancer deaths globally in 2015(1).HCC treatment strategies include resection,transplantation,ablation,local therapy,systemic therapy,and palliative care depending on the stage,where metastasis indicating poor prognosis(2).Rare HCC metastases such as those in the oral cavity indicate aggressive malignancy and even poorer outcome,and it may be the initial manifestation of HCC(2).

摘要： Prof. Gunter Larisch graduated from the Technical University ofBerlin. Since 2018, he has been engaged in research work relatedto the fabrication, characterization, and application of energyefficient,high-speed vertical-cavity surface-emitting lasers(VCSELs) at the Center of NanoPhotonics. He has won the SPIEPhotonics West “Green Photonics Award” three times. In 2019,he joined Changchun Institute of Optics, Fine Mechanics andPhysics through the CAS President’s International FellowshipInitiative (PIFI), and started to work in the Bimberg Chinese-German Green Photonics Research Center.

摘要： In the case of lid-driven deep cavity flow, the effects of different resolutions of local grid refinement have been studied in the frame of multiple relaxation times (MRT) lattice Boltzmann method (LBM). In all the cases, the aspect ratio and Reynolds number are set as 1.5 and 3.200, respectively. First, the applied method is validated by comparing it with two reported works, with which agreements are reached. Then, six separate degrees of local grid refinement at the upper left corner, i.e. purely coarse grid, including 1/64, 1/32, 1/16, 1/8, 1/4 refinements of the lattice number in the width direction have been studied in detail. The results give the following indications:① The refinement degrees lower than 1/8 produce similar results;② For single corner refinement, 1/4 refinement is adequate for clearing the noises in the singularity zone to a large extent;③ New noise around the interface between coarse and fine zones are introduced by local grid refinement. Finally, refinement of entire subzone neighboring the lid is examined to avoid introducing new noises and it has been found effective.

摘要： This paper presents the effects of surface effects in the cavity of variable curvature. The wave function expansion method and the conformal mapping method are used in the solution of dynamic stress concentration factor around an irregularly shaped cavity at nano-scale. The stress boundary conditions on the surface are obtained by using the generalized Young-Laplace equation. The results show that the degree of stress concentration becomes more obvious with curvature increasing. Taking the elliptical cavity as an example, the influence of the ration of the major and minor axis of the ellipse, the numbers of the incident wave and the surface effects on the dynamic stress concentration factor are analyzed. The ration of the major and minor axis, the incident wave frequency and the surface effects show the pronounced effects on the dynamic stress concentration distributions.

摘要： This paper discussed how to set up an injection model of iniection molding machine and set the injection pressure by a kind of engineering experiment,to realize the setting of injection velocity classification parameters.Set model curve of Mold Filling according to the physics process of Mold Filling and use computers to solve model curve in order to obtain the classification injection pressure and velocity.This method can obtain the injection velocity classification parameters but needn't to set up accurate mathematical model,specially be suitable for setting up the injection parameters automatically when installing die in injection molding machine.

摘要： This paper discussed how to set up an injection model of iniection molding machine and set the injection pressure by a kind of engineering experiment,to realize the setting of injection velocity classification parameters.Set model curve of Mold Filling according to the physics process of Mold Filling and use computers to solve model curve in order to obtain the classification injection pressure and velocity.This method can obtain the injection velocity classification parameters but needn't to set up accurate mathematical model,specially be suitable for setting up the injection parameters automatically when installing die in injection molding machine.

摘要： This paper discussed how to set up an injection model of iniection molding machine and set the injection pressure by a kind of engineering experiment,to realize the setting of injection velocity classification parameters.Set model curve of Mold Filling according to the physics process of Mold Filling and use computers to solve model curve in order to obtain the classification injection pressure and velocity.This method can obtain the injection velocity classification parameters but needn't to set up accurate mathematical model,specially be suitable for setting up the injection parameters automatically when installing die in injection molding machine.

摘要： This paper discussed how to set up an injection model of iniection molding machine and set the injection pressure by a kind of engineering experiment,to realize the setting of injection velocity classification parameters.Set model curve of Mold Filling according to the physics process of Mold Filling and use computers to solve model curve in order to obtain the classification injection pressure and velocity.This method can obtain the injection velocity classification parameters but needn't to set up accurate mathematical model,specially be suitable for setting up the injection parameters automatically when installing die in injection molding machine.

摘要： 本发明实施例适用于PCB生产技术领域，提供了一种PCB Cavity设计区域的制作工艺。PCB Cavity设计区域的制作工艺包括如下步骤：a、在Cavity设计区域的位置定深成型出回型槽；b、通过镭射将所述回型槽底部的打通至最上层的绝缘板下表面；c、在回型槽内曝光的最底层的铜箔层壁上通过影像转移及显影蚀刻生产铜垫；d、通过PTH电镀在回型槽的槽壁上镀铜；e、将回型槽的中间部分成型掉，从而形成内壁有铜、底部无铜的局部凹陷。本发明在Cavity设计区域位置的局部凹陷内壁有铜能够使外部的铜箔层与内部的铜箔层导通，局部凹陷的底部无铜能够确保其上方高频区域不受信号传输的影响。

摘要： 本发明公开了一种Cavity PCB制作工艺，包括：在内层或次外层芯板上依次进行：锣Cavity、手动修理板批锋、水洗、AOI及棕化；在半固化片上依次进行：开料、锣Cavity，并与上述棕化后的芯板进行预排；在铜箔上进行开料，然后与上述预排后的半固化片及线路板进行排板；压板，将芯板、半固化片和铜箔压合在一起；焗板，消除板料内应力，防止板翘；钻孔。在内层或次外层芯板上锣Cavity后，通过手动修理板批锋及水洗流程，清理锣Cavity产生的批锋，并通过AOI检查芯板是否有缺陷，有效避免锣Cavity产生的批锋而导致线路板短路报废的问题。

摘要： 本发明实施例适用于PCB生产技术领域，提供了一种PCB Cavity设计区域的制作工艺。PCB Cavity设计区域的制作工艺包括如下步骤：a、在Cavity设计区域的位置定深成型出回型槽；b、通过镭射将所述回型槽底部的打通至最上层的绝缘板下表面；c、在回型槽内曝光的最底层的铜箔层壁上通过影像转移及显影蚀刻生产铜垫；d、通过PTH电镀在回型槽的槽壁上镀铜；e、将回型槽的中间部分成型掉，从而形成内壁有铜、底部无铜的局部凹陷。本发明在Cavity设计区域位置的局部凹陷内壁有铜能够使外部的铜箔层与内部的铜箔层导通，局部凹陷的底部无铜能够确保其上方高频区域不受信号传输的影响。

摘要： 本实用新型公开了一种5G通讯用多层Cavity印制线路板，包括第一基板，在第一基板的上表面和下表面分别设置有上内层铜层和下内层铜层，在上内层铜层上方设置有第二基板，在第二基板的上表面设置有上外层铜层，在下内层铜层的下方设置有第三基板，在第三基板的下方设置有下外层铜层，在下内层铜层的上方设置有Cavity区域，Cavity区域贯穿第一基板、上内层铜层、第二基板和上外层铜层，在Cavity区域下端与下内层铜层的上表面之间设置有阻胶区，在阻胶区上设置有阻胶胶带，阻胶胶带贴在下内层铜层的上表面。本实用新型结构简单、设计合理，产品生产成本低、保证了5G线路板的电性能，良品率高。

摘要： 本发明公开了一种PCB cavity结构的制作工艺，包括如下步骤：在压合制程中，于欲形成cavity区域的位置进行化学处理后，制作离型材料，该离型材料可抗压合高温制程，在压合制程后，仍具有离型特性；在防焊制程后，制作保护膜，该保护膜可在去除离型材料时，保护电路板，避免在后续制程中损伤防焊及基材表面等，并可减少后续一次线路制程，然后雷射盲捞至离型材料的阻挡层；去除cavity区域的离型材料，然后蚀刻去除阻挡层，再去除保护膜，得到PCB cavity结构；该制作工艺成本低、良率高，通过该方法得到的PCB cavity结构底部平坦度高。

摘要： 本实用新型涉及毫米波板加工技术领域，具体为一种毫米波板大尺寸cavity加工装置，包括毫米波板加工机箱，所述毫米波板加工机箱的内部设置有电机，所述电机的输出端固定连接有第一转动齿轮，所述第一转动齿轮的一侧啮合有第二转动齿轮，所述第二转动齿轮的一侧转动连接有转动块，所述转动块的一侧固定连接有限位框，所述限位框的另一侧固定连接有毫米波板加工机箱，所述第二转动齿轮的一侧固定连接有螺纹杆，所述螺纹杆上螺纹连接有螺纹滑块，所述螺纹滑块滑动连接在所述限位框的内侧，所述限位框的一侧开设有槽道，通过上述结构，不仅能够对毫米波板进行快速夹持，还能够防止夹持过程中损坏毫米波板。