Showing papers on "Cavity wall published in 2009"

High-Speed Jet Formation after Solid Object Impact

Abstract: A circular disc hitting a water surface creates an impact crater which after collapse leads to a vigorous jet. Upon impact an axisymmetric air cavity forms and eventually pinches off in a single point halfway down the cavity. Two fast sharp-pointed jets are observed shooting up- and downwards from the closure location, which by then has turned into a stagnation point surrounded by a locally hyperbolic flow pattern. This flow, however, is not the mechanism feeding the jets. Using high-speed imaging and numerical simulations we show that jetting is fed by the local flow around the base of the jet, which is forced by the colliding cavity walls. We show how the well-known theory of a collapsing void (using a line of sinks on the symmetry axis) can be continued beyond pinch-off to obtain a new and quantitative model for jet formation which agrees well with numerical and experimental data

Rubble stone anchoring system

Abstract: Anchoring systems for use in cavity wall structures having an inner wythe and an outer wythe constructed of rubble stone are disclosed The anchoring system employs an anchor fastened to or set within the inner wythe that extends into the cavity and connects to a J-hook A vertically adjustable veneer tie enwraps the J-hook, limiting lateral movement and front-to-back displacement, and is set within the bed joint of the outer wythe The anchoring system minimizes cavity size and provides stability for an uncoursed outer wythe equivalent to that of anchoring systems for standards coursed bed joints

Wind load anchors and high-wind anchoring systems for cavity walls

Abstract: High-wind load wall anchors and high-wind load wall anchoring systems for cavity walls are described which utilize double-walled anchor constructs with interengaging wire formative veneer ties. The high wind load anchors are mounted upon an interior cavity wall and the veneer ties are embedded within joints of an exterior cavity wall. The anchors have an aperture, for threading the veneer ties therethrough and restricting undesired movement, coupled with a double-walled wing structure to resist anchor deformation by high-wind forces. For resistance against seismic forces, the high-wind load wall anchoring system has a reinforcement wire which snaps into contoured veneer ties.

Effective emissivity of a cylindrical cavity with an inclined bottom: I. Isothermal cavity

Abstract: The Monte Carlo method is applied to the computation of the effective emissivity of a specular–diffuse isothermal blackbody cavity shaped by a cylindrical generatrix, a flat inclined bottom and a flat diaphragm. The dependences of the normal effective emissivity on the bottom inclination angle are studied for different cavity depths and various values of the diffuse component of the cavity wall reflectance. The distributions of the local normal effective emissivity over the cavity aperture and the dependences of the integrated effective emissivity on the distance between the aperture and the radiation detector are computed. The choice of optimal geometrical parameters for improving the radiometric performance of artificial blackbodies is discussed.

A Cost-Effective MEMS Cavity Packaging Technology for Mass Production

Abstract: Cost effective microelectromechanical system (MEMS) packaging methods have been required, because the cost portion of the MEMS package is more than 80% of the manufacturing cost of a MEMS device. For this reason, cost-effective MEMS packaging is proposed in this paper for mass production using copper (Cu) lead frames (L/F) as a preplated frame (PPF). Package types include an epoxy molding compound (EMC) cavity wall and an on-frame type. The EMC-cavity package consists of a substrate, a cavity wall and a flat lid on top of the cavity. The on-frame package has a folded lid without a cavity wall. Finite element method (FEM) numerical modeling is performed to anticipate the mechanical warpage and stress of the packages. Assembled MEMS cavity packages were tested for wire pulling, lid pulling, hermetic test, and reliability tests in order to prove the feasibility of this packaging. The wire bonding strength was improved by 40% using plasma cleaning before wire bonding. Through a lid pulling test, a lid bonding strength of 2.40 kgf on average was obtained using an epoxy adhesive. Finally, all samples of the packages passed the reliability tests of the TC, HAST, and HTST, standardized by Joint Electron Device Engineering Council (JEDEC). Also, this cavity package showed excellent hermeticity through leak tests.

Numerical Simulations of High-Speed Turbulent Cavity Flows

Abstract: Detached-Eddy Simulations (DES) of flows over clean and controlled cavities with and without doors are presented in this paper. Mach and Reynolds numbers (based on cavity length) were 0.85 and one million respectively. Spectral analyses showed that the DES computations were able to correctly predict the frequencies of the Rossiter modes for both uncontrolled and controlled cases. Flow visualisations revealed that the impact of the shear layer formed along the cavity on a slanted aft wall no longer creates a large source of acoustic noise. Therefore little acoustic propagation was seen up the cavity. This was confirmed by the analysis of the cavity wall forces, which showed that the oscillations of the shear layer were reduced when the wall was slanted. This aided in reducing the overall Sound Pressure Levels throughout the cavity and far-field. Comparisons of the flow-fields suggested that the addition of the doors also aided in stabilising the shear layer, which was also shown in the analysis of the wall forces. As a result, the addition of the doors was found to affect the clean cavity configuration significantly more than the controlled one.

On the jump in the frequency of acoustic oscillations in supersonic flows over rectangular cavity

Abstract: In this study, we analyze the jump in the frequency of acoustic oscillations that is observed in supersonic flows over a rectangular cavity. Frequency jumps have previously been observed in experiments when the length-to-depth ratio of a cavity is gradually varied. However, the reason for their occurrence has not been well understood. In order to explain the occurrence of the frequency jump, we improved the classical acoustic oscillation model by taking the acoustic reflections at the cavity walls into account. The results obtained using our analytical model are found to agree with experimental results with respect to both the frequency jump and the variation in frequency with the length-to-depth ratio. On the basis of the analytical model, a simple model is also proposed; in the simple model, it is assumed that the acoustic waves in the cavity are one-dimensional waves. This simple model can provide clearly the fundamental reason for the occurrence of the jump in the frequency of acoustic oscillations in the cavity.

Modeling of Surface Charge Decay in a Spherical Cavity within a Solid Dielectric Material using Finite Element Analysis

Abstract: The modelling of cavity surface charge decay through conduction along the cavity wall using the Finite Element Analysis (FEA) method is presented in this paper. A field-dependent cavity surface conductivity is proposed and the Phase-Resolved Partial Discharge (PRPD) patterns obtained from experimental measurements used to validate the simulation results generated using the model. A comparison between the simulation and measurement results has also been undertaken to verify the surface charge decay effect.

Collapse of Non-axisymmetric Cavities

Abstract: A round disk with a harmonic disturbance impacts on a water surface and creates a non-axisymmetric cavity which collapses under the influence of hydrostatic pressure. We use disks deformed with mode m=2 to m=6. For all mode numbers we find clear evidence for a phase inversion of the cavity wall during the collapse. We present a fluid dynamics video showing high speed imaging of different modes, pointing out the characteristic features during collapse.

Mold system and method for making helmet

Abstract: A method for forming a resin-fiber composite shell includes introducing a resin-fiber pre-preg packet between a rigid cavity (10) and a rigid core (22). A flexible member (24) is introduced between the rigid cavity and the rigid core. The flexible member has a first side and a second side that is opposite the first side. The resin-fiber pre-preg packet (36) is positioned on the first side of the flexible member. A fluid is introduced between the flexible member and one of the cavity wall and the core wall for applying a substantially uniform pressure on the second side of the flexible member. The first side of the flexible member applies the substantially uniform pressure to the resin-fiber pre-preg packet for forming the resin-fiber pre-preg packet into a shape of one of the cavity wall and the core wall.

Hie-isolde high beta cavity study and measurements

Abstract: The upgrade of the ISOLDE machine at CERN foresees a superconducting linac based on two gap independently phased Nb sputtered Quarter Wave Resonators (QWRs) working at 101.28MHz and producing an accelerating field of 6MV/m on axis. A careful study of the fields in the cavity has been carried out in order to pin down the crucial e-m parameters of the structure such as peak fields, quality factor and e-m power dissipated on the cavity wall. A tuning system with ≈200kHz frequency range has been developed in order to cope with fabrication tolerances. In this paper we will report on the cavity simulations. The tuning plate design will be described. Finally the frequency measurements on a cavity prototype at room temperature will be presented.

Method for manufacturing a micromechanical diaphragm structure having access from the rear of the substrate

Abstract: A method for manufacturing a micromechanical diaphragm structure having access from the rear of the substrate includes: n-doping at least one contiguous lattice-type area of a p-doped silicon substrate surface; porously etching a substrate area beneath the n-doped lattice structure; producing a cavity in this substrate area beneath the n-doped lattice structure; growing a first monocrystalline silicon epitaxial layer on the n-doped lattice structure; at least one opening in the n-doped lattice structure being dimensioned in such a way that it is not closed by the growing first epitaxial layer but instead forms an access opening to the cavity; an oxide layer being created on the cavity wall; a rear access to the cavity being created, the oxide layer on the cavity wall acting as an etch stop layer; and the oxide layer being removed in the area of the cavity.

Sound Generation and Radiation of an Open Two-Dimensional Cavity

Abstract: This work studies differences in sound generation and radiation between incompressible and compressible flowfields at the corresponding Mach number of 0.15 by evaluating the two dominant dipole terms in a temporal form of Curie's equation. The present work adds incompressible simulation results to a previously reported direct simulation of an open two-dimensional cavity oscillating in wake mode. The length-to-depth ratio of the cavity is L/D = 4, and the flow is considered to be laminar. The Reynolds number based on the cavity depth is Re D = 1500. At these conditions, the flow is characterized by large variations in the streamwise force coefficient, showing similarities to a bluff-body wake flow, which makes the present case an attractive candidate for an incompressible approach. The root-mean-square levels of the two acoustic source terms show good agreement in the vicinity of the cavity, and the agreement in the radiated sound is almost perfect when isolating the cavity walls in the surface integration. The agreement in the radiated sound for the two flowfields is equally good when isolating the downstream wall extending from the cavity trailing edge and 10D downstream. However, when the surface integration comprises both the cavity walls and the downstream wall, a major mismatch in the directivity arises, and it is shown that this mismatch is primarily caused by an almost complete cancellation of the sources at the cavity bottom and the downstream wall in the incompressible simulations.

Multiwell culture plate for three-dimensional cultures

Abstract: In a multiwell plate 1 the multitude of cavities 2 are each formed by a rigid wall 21 and a flat bottom part 22, said bottom part being hermetically bonded to the cavity wall 21, while at the same time individually detachable from the wall 21 along its rim 23. To transfer a three- dimensional culture 4 to a second device, the bottom part 22 of the cavity 2 is individually detached from the cavity wall with a suitable device 5, that allows to detach the bottom part along its rim, e.g. by applying pressure. The three-dimensional culture 4 remains on the detached bottom part, while the multiwell plate with the cavity wall is lifted away. Since the culture 4 itself is not mechanically strained, no damage to the culture can take place.

Microwave directional coupler with crimp type connector

Abstract: Disclosed is a microwave directional coupler with a crimp type connector, wherein a coupler body is a cavity structure, an air medium is filled in the cavity, an isolating terminal and a pair of coupling bars are disposed in the cavity, the body is externally connected with radio frequency connectors of an input end, an output end and a coupling end, and a cover plate is covered on the body. The microwave directional coupler with a crimp type connector is characterized in that the body is provided with bosses (1-1) at the positions of the three ports, stepped holes running through the cavity wall are arranged in the bosses (1-1), large through holes (1-2) are arranged close to the outer side of the cavity, small through holes (1-3) are arranged close to the inner side of the cavity, the tail portion of an outer conductor of a radio frequency connector (2) is in interference fit with the stepped holes, and a step (1-4) is formed between each boss (1-1) and the lateral wall of the body (1). The utility model has the advantages that the coupler has lower cost and better directivity, compensates discontinuity of the coupling bars, and resolves problems of transition between the connector and the coupling bars and the like well.

Radial piston fuel supply pump

Abstract: An hydraulic head features two, three, or four individual radial pumping pistons and associated pumping chambers, annularly spaced around a cavity in the head where an eccentric drive member with associated outer rolling actuation ring are situated. The piston shoe or foot smoothly enlarges from the piston stem, thereby avoiding the concentration of stress at the interface. Another improvement is in the capture of the piston foot through beveled holes at the ends of a C-band spring such that the bevel substantially conforms to the contour of the foot and thereby reduces stresses and wear. Yet another improvement is that the C-band spring is retained within a guide channel of the cavity wall thereby permitting apparent reciprocating displacement of the spring in parallel with the reciprocation of the pistons, while avoiding axial movement or tilting within the cavity.

Precision liquid-gas transmission and matching machine based on piezoelectric material

Abstract: The invention relates to a precision liquid-gas transmission and matching machine based on a piezoelectric material of the electromechanical technical field. The machine comprises a piezoelectric material body, a rigid cavity, an elastic input valve, an elastic output valve and a control power supply. A left electrode plate and a middle electrode plate in the piezoelectric material body are respectively communicated with an external coated conducting layer on a left piezoelectric material body, and the middle electrode plate and a right electrode plate are respectively communicated with an external coated conducting layer on a right piezoelectric material body. The piezoelectric material body is arranged in the rigid cavity and separates the rigid cavity into two independent chambers, the two chambers are separated from each other, an upper cavity wall and a lower cavity wall of each chamber are respectively provided with a fluid inlet and a fluid outlet, outer ends of the inlet and the outlet are respectively connected with a tube, and the elastic input valve or the elastic output valve is arranged at the inlet and the outlet. The precision liquid-gas transmission and matching machine has the advantages of compact structure, simple driving, easy realization, high reliability and accuracy, can realize infinite precision matching of two or more two fluids, and the functions of simultaneous liquid and gas transmission and precise liquid and/or gas matching.

An analysis of shear waves generated by the Sterling explosion

Abstract: [1] We show that the near-field shear waves from the decoupled explosion Sterling were likely caused by the cavity shape, which was approximately spherical except for a flat floor due to melted and recrystallized salt. We model the impact of the explosion shock wave on the cavity walls using a two-dimensional (2-D) Eulerian finite difference code that simulates the evolution of the air shock in the cavity coupled with 2-D Lagrangian finite difference code that simulates the nonlinear region outside the cavity. Calculated shear waves generated by the asymmetric impact of the shock wave on the cavity walls match the observed initial shear wave amplitudes and radiation pattern. The observations also have substantial P and S coda, which are not reproduced by the calculations. Similarity of coda waveforms with distance indicates that their source is at or very near the cavity. Longer time modeling of the air shock evolution appears to produce a more realistic source function and provide a better match to the coda and indicates that the coda are caused by air reverberations between the top and bottom of the cavity. We assess the likelihood that fractures created by the tamped explosion that formed the cavity Salmon were reopened by Sterling. Modeling of hydrofracture propagation driven by the Sterling explosion, by coupling stress wave dynamics in rock with fluid mechanics in the fractures, shows that the cavity pressure is insufficient to overcome the overburden to propagate fractures into rock, except for the area immediately below the explosion on the cavity floor.

Influence of cavity wall elasticity on resonant frequency of small underwater cylindrical Helmholtz resonator

Abstract: Influence of cavity wall elasticity on resonant frequency of small underwater cylindrical Helmholtz resonator is studied theoretically and experimental. Based on the theory of electroacoustic analogy, the simplified low frequency lumpedparameter model of the Helmholtz resonator is constructed. A general, convenient for calculation expression of the resonant frequency is given by circuit analysis. The influence of the thickness and the material of the resonator on the resonant frequency is investigated by numerical method. And the approximate rigid conditions for small underwater cylindrical Helmholtz resonators of different sizes are given. Small cylindrical Helmholtz resonators of different wall thickness and material were tested in a standingwave tube filled with water. Experimental results well testified the theoreticl results and the approximate rigid condition. This paper is useful for the design and application of the underwater cylindrical Helmholtz resonators.

Energy-saving wall filled with light renewable material

Abstract: The invention relates to an energy-saving wall filled with lightweight and renewable material and used a framework structure, wherein, a wall framework is installed among frame beams, a bamboo woven net is used for covering the wall framework and being fixed on the wall framework to form a cavity wall, and then the renewable material with low coefficient of thermal conductivity is used for filling the cavity of the wall. The energy-saving wall has good sound insulation and heat preservation capacity, thin body, light self-weight and no use of solid clay bricks, saves energy and material, and is applicable to rural houses.

Multi-stage pulverizer

Abstract: The utility model relates to a multilevel crusher. A blade fixed on a main shaft which runs through a crusher body divides a crushing cavity into a coarse crushing cavity, a fine crushing cavity and a material discharge cavity, wherein, the inlet of the coarse crushing cavity is communicated with a feeding hole which is internally embedded with a material limiting valve through a feeding cavity; the outlet of the coarse crushing cavity is communicated with the fine crushing cavity; the outlet of the fine crushing cavity is communicated with the inlet of the material discharge cavity; the outlet of the material discharge cavity is correspondingly communicated with a sedimentation classification cavity; and an extrapositioned intake which ensures the circulation of the airflow in the cavity body is embedded in the front cavity wall of the coarse crushing cavity. The utility model has compact structure, small equipment volume, low energy consumption, high efficiency and very convenient installation, operation and maintenance, realizes the tight combination of multilevel crushing and material discharge, causes the crushing course to be continuous and effective, and simultaneously limits the dust pollution.

Wall heat accumulating type greenhouse

Abstract: The invention belongs to the improvement of solar greenhouse structure, more particularly relates to a wall heat accumulating type greenhouse comprising a back wall, gable walls at the two sides and a greenhouse consisting of a lighting plastic tent supported by an arch frame. Cuboid regenerators parallel to the back wall are uniformly distributed and arranged at the back side of the back wall; heat conducting pipes extending into soil layer are uniformly distributed and arranged at the two side cavity walls of the regenerators; blast pipes which respectively pass through the back wall to be communicated with the regenerators and are inclined upwards are uniformly distributed and arranged at the lower part of the back wall along the horizontal line; draft fans are arranged at inlets of the blast pipes; air-out pore channels which pass through the back wall to be communicated with the regenerators and are inclined downwards are uniformly distributed and arranged at the upper part of the back wall; the back part of the back wall and the regenerators are all covered by the soil layer; and a heat preservation and thermal insulation layer is arranged outside the soil layer. The wall heat accumulating type greenhouse not only stores the heat in the greenhouse during the day, but also can reduce the temperature in the greenhouse simultaneously, and can release the stored heat at night, thus increasing the temperature in the greenhouse and saving energy.

Laser cutting device of embroidery machine and laser embroidery integrated machine thereof

Abstract: The invention relates to an embroidery machine laser cutting device and a laser embroidery unity machine thereof, which belongs to the technical field of a textile fabrication plant A laser cutting head comprises a hollow pipe, a hollow motion bar which is connected with the interior of the hollow pipe in a sliding way, a mask body which is arranged at the lower end of the hollow motion bar; the pipe wall of the hollow pipe is provided with at least a first strip-shaped through hole which is parallel to the axes of the hollow pipe; a shank which is connected with the hollow motion bar is arranged in the first strip-shaped through hole, and one end of the shank extends to the outside of the first strip-shaped through hole; a lifting actuating mechanism is connected with the shank; the body of the mask body takes the hollow structure and is divided into an upper cavity and a lower cavity by a medial conical surface; the cavity wall of the upper cavity is provided with a fanning hole which is communicated with the upper cavity; the lower cavity is provided with a smoking hole which is communicated with the lower cavity The invention facilitates to the movement of an embroidery frame of the embroidery machine, has smaller convex focus in the mask body, more accurate cutting operation and facilitates that the mask body absorbs smoke generated by laser cutting, thus having no pollution to working environment

Exhausting silencer with variable volume

Abstract: The utility model discloses a variable-volume exhaust muffler, comprising a gas inlet pipe, an expansion cavity and an exhaust pipe; the expansion cavity comprises a cavity wall, a front end cover and a rear end cover; a mobile partition board is arranged in the expansion cavity and divides the expansion cavity into a cavity I and a cavity II; the cavity I and the cavity II are communicated with each other through at least a resonance hole; the gas outlet of the gas inlet pipe and the gas inlet of the exhaust pipe are arranged in the cavity I; the mobile partition board is provided with at least a flexible pre-tightening force device; the pre-tightening force direction of the flexible pre-tightening force device right faces the cavity I; the utility model can achieve self-regulation of the cavity volume so as to reach the dynamic elimination effect that the noise elimination frequency of the muffler is able to be increased along with the increase of the engine rotating speed, or is able to be reduced along with the decrease of the engine rotating speed, thereby achieving low frequency dynamic noise elimination; therefore, the utility model has good low-frequency noise elimination effect and can effectively eliminate the exhaust noise; at the same time, through the movement of the mobile partition board, the utility model can achieve the function of attenuating and reducing the exhaust pressure in the expansion cavity, and has compact and simple structure.

Novel injection device for injection molding machine

Abstract: The invention provides a novel injection device for an injection molding machine, comprising a hollow stator and a columnar rotor, wherein, the hollow stator is provided with a cylinder inner cavity; and the columnar rotor is arranged in the inner cavity of the stator and is eccentric to the stator. The rotator is driven by a driving device and can positively and reversely turn within the range of 0-180 degrees; a blade is arranged in a through hole at the radial section of the rotor, wherein, the two ends of the blade slide on the periphery of the inner cavity wall of the stator all the time when the blade turns with the rotor and slides in the through hole; the shortest distance from the vertical axis of the rotor to the inner cavity wall of the stator is equal to the radius of the rotator; the inner cavity of the stator is divided into two spaces by the external surface of the rotor and the blade, wherein, one space is a material-filling space; the stator surface at which the material-filling space is arranged is respectively provided with a charge hole for receiving molten plastic and a discharge hole which is connected with the charge hole of a mould; and when the volume of the material-filling space changes from large to small, the discharge hole is communicated with the mould and is not communicated with the charge port, when the volume of the material-filling space changes from small to large, the charge hole opens and works. The invention has simple structure, low manufacture and maintenance cost and wide application range.

Structural fitting for a building

Abstract: A structural fitting (1 ) for a cavity wall within a building comprises elongate plates (2) (3) adapted to be supported within the cavity wall, the plate (2) being formed with a plurality of drain holes (4) extending along the length of the structural fitting so as to allow water which enters the cavity wall from above to drain down through the fitting (1 ) to the lower part of the cavity wall, where it is deflected away from the cavity by the imperforate plate (3). The structural fitting (1 ) is of cruciform cross-section.

Low-frequency vibration acoustic wave deashing device

Abstract: The utility model relates to a low frequency vibrating sound wave dust cleaner which comprises a die cavity assembly of the prior art, a ring-shaped die cavity body fixed on a bottom plate of the die cavity assembly and provided with an air inlet of a pressurized air source, a vibration source film sheet arranged in the die cavity body and on the upper opening of a sound cavity of the die cavity assembly, a die cavity body cover arranged on the die cavity body, and a trumpet-shaped loudspeaker arranged below the bottom plate of the die cavity assembly and also correspondingly connected to the central hole of the die cavity assembly, and the sound cavity wall of the die cavity assembly is altered into a sphere notch shape. The utility model can cause the transition of the sound cavity wall of the die cavity assembly to be smooth and the flow of airflows to be smoother by altering the shape of the sound cavity wall of the die cavity assembly, thereby enhancing the integral property of the low frequency vibrating sound wave dust cleaner and ensuring the normal operation of the low frequency vibrating sound wave dust cleaner.