Cavity Heights Research Articles

Loose particle Detection: The optimal detection condition and weak loose particle impulse extraction

To achieve effective detection of loose particles within small cavities in microelectronic devices, this paper proposes the optimal detection conditions of loose particles in ceramic packaging for microelectronic devices based on simulation, and presents a method for weak signal reconstruction using weighted sparse representation. To address the challenge of ineffective detection of loose particles under recommended vibration conditions, a particle-cavity collision dynamics model is established. Subsequently, the detection laws of loose particles under different accelerations, frequencies, and cavity heights are studied through simulation, leading to the establishment of optimal detection conditions for microelectronic devices with varying cavity heights. To address the issue of weak impulses being submerged in background noise under optimal detection conditions, sparse representation is utilized for signal reconstruction. First, a Laplace wavelet dictionary is constructed according to the impulse characteristics. Second, the generalized minimax-concave (GMC) penalty function is applied as a sparse regularization term to preserve signal amplitude. Meanwhile, a weight matrix based on kurtosis and singular value is designed to threshold sparse coefficients. The results demonstrate that the proposed optimal detection conditions and signal reconstruction method effectively detect loose particles. Compared with other algorithms, the proposed method reduces background noise in the particle impact noise detection (PIND) signals while maintaining impulse amplitude; it also improves signal reconstruction accuracy and offers valuable insights into effective loose particle detection in microelectronic packaging devices.

Spalling characteristics of sandstone containing rectangle hole with gradient cavity height: An experimental and DEM numerical study

Spalling failure commonly exists during the progressive excavation of underground engineering, and the stepped excavation of underground mining stope is rarely simulated in previous studies. Therefore, the biaxial compression test is finished by sandstone samples containing rectangular hole (with different cavity heights), and the corresponding numerical simulation is conducted by the discrete element method. Based on the mechanical, optical and acoustic data captured during the test, the main results and conclusions are as follows: 1) There are two paths to activate the typical spalling failure, the first way is caused by the rapid energy release (manifested as sudden AE burst), and the second way is that the released energy accumulates to a threshold over a long period and finally causes large-scale damage. 2) The relatively larger cavity height delayed the initiation of central tensile failure in the roof & bottom surrounding rocks and the spalling failure in sidewalls. 3) The relatively larger confining pressure contributes to the early construction of the spalling failure and limits the extension of the central tensile crack bands. 4) The construction of spalling failure is very fast, the ejected rock plates are caused by several rounds of spalling failure, and the final V-shaped groove is built by the spalling failure and internal crushing failure.

A common ecogeographic trend in the internal nasal cavity variation across Mesolithic to Bronze Age Eastern European and Caucasian populations

AbstractThe ecogeographic trends in the shape of the internal nasal cavity and external facial skeleton were explored in a sample of Mesolithic, Neolithic, and Bronze Age skulls from Northeastern Europe and the Caucasus and tested against a background of the variation in recent populations from the same area. The volume, surface area, and several linear dimensions of the internal nasal cavity as well as a set of 3D landmarks of the external mid‐face were collected in a sample of computed tomography (CT) scans of 121 adult male skulls from six modern human populations of Eastern Europe, Anatolia, and Caucasus (74 individuals) and seven ancient burial sites (47 individuals). Various measures of the association between nasal cavity morphology and climate revealed moderate to high levels of correlation. The modern populations from colder climates and all but one ancient group display a substantial decrease in the nasal cavity heights and widths, volume and nasal protrusion, a relative narrowing of the nasal cavity, and a substantial increment in length of the maxillary part of the cavity. These groups also exhibit a less protruding external nose, smaller orbits, and a vertically taller zygomatic region. Our results show that the suite of morphological features associated with living in a cold climate is more strongly pronounced in ancient Europeans compared with the Medieval or modern groups of the same continent.

Analytical model for junctionless accumulation‐mode cylindrical surrounding gate (JAM‐CSG) MOSFET as a biosensor

AbstractThis article proposes analytical modeling for Junctionless Accumulation‐Mode Cylindrical Surrounding Gate (JAM‐ CSG) MOSFET‐based biosensor used for label free electrical detection of the biomolecules (enzymes, cells, DNA, etc.). Modeling has been performed using the Poisson's equation and considering parabolic potential profile. A nanogap cavity is being created for providing a binding site for the biomolecules. Influence of both the neutral and charged biomolecules immobilized in the nanogap cavity has been studied. The change in the threshold voltage is being utilized as a measure for detecting the existence of the biomolecules inside the cavity region. The sensitivity parameter has also been found considering different cavity heights. ATLAS device simulator has been utilized for conducting the simulations. Furthermore, the analytical model outcomes are validated with the simulated ones. Results acquired verify the considered device to be able to work as a highly sensitive biosensor.

Examine the lattice Boltzmann method for the mixed convection simulation of water/Al2O3 nanofluid in a 2D rectangular cavity under radiation with isothermal semicircular obstacles

The present study simulated the mixed convection (MCXN) of the water/Al2O3 nanofluid (NFs) in a two-dimensional rectangular cavity in the presence of radiation. The top and bottom walls were assumed to be cold and hot, respectively, with the lateral walls being insulated. A magnetic field (MGF) with a Hartmann number (Ha) of 0–40 was applied to the NFs within the cavity. The simulations were carried out at a Richardson number (Ri) of 1 and a Rayleigh number (Ra) of 105 for cavity heights of 0.5–2.0 to evaluate heat transfer (HTF) on the walls and analyze fluid rotation within the cavity. The lattice Boltzmann method (LBM) was used to perform the simulations. It was found that the incorporation of radiation into the system reversed the flow rotation in the cavity and increased the Nu. A rise in the radiation parameter from 0 to 0.2 led to a 2.8-fold larger Nu on the cold wall. A rise in the cavity height decreased the Nu, and a further increase in the height increased the Nu on the wall. An increased Ha had an insignificant effect on the Nu at small cavity heights but decreased the Nu on the wall at large cavity heights.

Simulation Analysis and Performance Test of a Compressible Piezoelectric Pump Fluid Cavity.

The large load loss of piezoelectricity pumps leads to fluid energy in the fluid chamber during fluid transportation. In this paper, the output performance of a piezoelectricity pump is improved by changing the structure parameters of the fluid chamber to reduce the fluid load. The mechanism of fluid flow energy loss in the body cavity of hydraulic pumps is simulated and analyzed, and the influence of the dimensions of the inlet and outlet valves and the height of the cavity on fluid energy loss is obtained. The flow rate and pressure of inlet and outlet valves with different cavity heights and different driving frequencies are obtained. The results show that the flow rate and output pressure of the hydraulic pump are optimized when the cavity height is 3 mm, and the inlet and outlet valve diameters are 2.5 mm.

Land Cover Analysis and Habitat Identification of Tanimbar Corella (Cacatua Goffiniana) on Tanimbar Islands, Maluku

The Tanimbar Corella (Cacatua goffiniana) is a protected bird species endemic to the Tanimbar Islands (Yamdena and its satellite islands) in the Maluku province of Indonesia. The major threats identified to this species are hunting, illegal trade, and habitat loss. Therefore, this study aims to classify the land cover, distribution, and habitat types occupied by C. goffiniana on the Tanimbar Islands. Classification of land cover was analyzed using a supervised classification method of the Erdas Imagine 2014 software. Direct field observations were conducted to identify the distribution of Tanimbar Corella and its habitat use. The land cover was classified into six classes: forest (54.26 %), open area (20.76%), plantation (14.81%), mangrove (6.89%), settlement (1.85%), and wetland (1.43%). C. goffiniana is distributed on five islands, Yamdena, Selaru, Larat, Sera, and Molu. Furthermore, this species was observed in forest, plantation, and open land habitats. The results identified seventeen nest trees of six species: Canarium Indicum, Pometia pinnata, Instia bijuga, Sterculita foetida, Maranther corymbosa, and Alstonia scholaris, with a range diameter of 40.00-136.71 cm and nest cavity heights of 9.00-34.22 m (n = 17). This research brings new data in three areas: 1) a reassessment of the distribution of C. goffiniana on the Tanimbar Islands; 2) a detailed classification of the land cover concerning habitat types of the Tanimbar Islands; 3) an identification of the tree species utilized by nesting Tanimbar Corellas. Information on preferred habitats and nesting trees is crucial for selecting release sites of confiscated birds to ensure post-release survival.

Numerical Study on Vortex Structures and Loss Characteristics in a Transonic Turbine with Various Squealer Tips

Cavity width and height are two key geometric parameters of squealer tips, which could affect the control effect of squealer tips on tip leakage flow (TLF) of gas turbines. To explore the optimal values and the control mechanisms of cavity width and height, various cases with different cavity widths and heights are investigated by solving the steady Reynolds Averaged Navier–Stokes (RANS) equations. In this study, the range of cavity width is 9.2–15.1 τ, and that of cavity height is 1.0–3.5 τ. The results show that the optimal value of cavity height is 2.5–3.0 τ, and that of cavity width is about 10.0–10.5 τ. The small cavity width could restrain the breakdown of tip leakage vortex (TLV) and reduce the extra mixing loss. Both small cavity width and large cavity height could enhance the blocking effect on the TLF, reducing the corresponding mixing loss. However, both of them will inhibit the length of the scraping vortex (SV), which is bad for the control of loss. In addition, large cavity height could reduce the loss inside the clearance, while small cavity width could not. This work could provide a reference for the design of squealer tip.

Design of Large-Scale Microwave Cavity for Uniform and Efficient Plastic Heating.

To reduce carbon emissions during heating in the manufacturing processes, microwave technology has attracted significant attention. Microwaves have considerable advantages over traditional heating methods, including more rapid heating, lower thermal damage, and eco-friendly processes. To apply microwaves to the manufacturing process, uniform and efficient heating is required. We analyzed the effect of various design parameters for uniform and efficient heating by changing the cavity heights, application of the reflector, and number and positions of waveguides. We conducted a numerical simulation and verified the findings by experiments. The results showed that a slight change in the cavity height altered the electromagnetic field distribution and heating parameters, such as the coefficient of variance and power absorption efficiency. With reflectors installed, 66% of cases exhibited better comprehensive evaluation coefficient (CEC) with consideration of uniform heating and power absorption. The spherical reflector showed 81% of cases, better than those of the ordinary model without a reflector. Furthermore, when double waveguides were installed, the average coefficient of variance (COV) was improved by 22%, and power absorption efficiency was increased by 53% compared to the single waveguide case. When the power applied to the waveguides was doubled, the average COV values improved by 18%. This large-scale analysis will be helpful in applying microwaves to actual industrial sites.

Dynamic compartmentalization of double-skin façade for an office building with single-sided ventilation

In this study, a compartmentalized double-skin façade (DSF) is developed for an office room with single-sided ventilation to enhance the performance of the passive design strategy. We designed a DSF that has both an inlet and an outlet to ensure compatibility with single-sided natural ventilation, increased the air cavity heights to overcome the effects of limited ventilation rate, and compartmentalized to suit seasonal conditions. The performance of the dynamically compartmentalized DSF was evaluated using four key parameters: cavity height, cavity depth, opening-to-glazing ratio (O/G ratio), and solar heat gain coefficient (SHGC). Two different seasons, namely summer and winter, were targeted. The results revealed the interdependency of each parameter and indicated the potential energy savings in terms of both cooling and heating. In summer, a greater cavity depth with a higher O/G ratio was helpful when the cavity height was increased. A higher SHGC increased the airflow rate, but it increased the room temperature because the solar heat gain was more influential than the increased airflow rate. In winter, the interdependency between the parameters increased with the SHGC. When airflow rate was restricted to fulfill the minimum ventilation requirement, a higher inlet cavity height helped increase the room temperature by 2 °C on average in winter.

Hydraulics of Fluidized Cavities in Porous Matrices: Cavity Heights and Stability for Upward Water Jets

Theoretical and experimental results for the evolution of cavities generated by upward vertical leakage jets in porous media are presented. The formulation is based on the conservation principles of mass, momentum, and energy. Two conditions were considered: two-dimensional isotropic medium and three-dimensional isotropic medium. The results of the cavity height are given in nondimensional form and related to the Froude number that considers the inlet flow characteristics (width of the slot or diameter of the orifice, and inlet velocity). Both the two-dimensional and the three-dimensional cases provided theoretical results for the length of the cavity limited by a maximum Froude number. This characteristic implies that the cavity destabilizes for Froude numbers higher than this maximum critical value. It was observed that parameters of the porous medium (soil parameters) not present in the conservation formulation must be added a posteriori to cover a larger spectrum of soil possibilities. The experimental results show that the theoretical proposition follows the main characteristics of the observations.

Experimental Study of Impingement Effusion Cooled Double-Wall Combustor Liners: Aerodynamic Analysis with Stereo-PIV

A new experimental study is presented for a combustor with a double-wall cooling design. The inner wall at the hot gas side features effusion cooling with 7-7-7 laidback fan-shaped holes, and the outer wall at the cold side features an impingement hole pattern with circular holes. Data are acquired to asses the thermal and aerodynamic behavior of the setup, using a new, scaled up, engine similar test rig. Similarity includes Reynolds, Nusselt and Biot numbers for hot gas and coolant flow. Different geometrical setups are studied by varying the cavity height between the two walls and the relative alignment of the two hole patterns at two different impingement Reynolds numbers. This article focuses on the aerodynamic performance of the setup. Instationary flow data are acquired, using a high speed stereo PIV setup. For each geometrical configuration, approximately 20 planes are recorded with a data rate of 1000 Hz by traversing the flow region of interest in the cavity between the two specimen. This fine resolution allows the reconstruction of 3D flow fields for the mean data values and an extensive analysis of transient phenomena at each plane. Time averaged data and jet-center plane transient data are presented in detail. The results show a complex flow field with a hexagonal vortex pattern in the cavity, which is mainly influenced by the cavity height and the relative alignment of the two walls. The jet Reynolds number shows small influence when analyzing normalized data. Small cavity heights show a less developed flow field with less stable vortex systems. The alignment shows a similar influence on vortex system stability, with the aligned case performing better. Additionally, statistical analysis of the jet flow and frequency domain analysis of the jet and the effusion flow are presented, showing the damping capability of the cavity, especially at increased cavity heights, and a residual low frequency pulsation of the effusion cooling inflow.

Investigation on Design Theory and Performance Analysis of Vacuum Capacitive Micromachined Ultrasonic Transducer.

The capacitive micromachined ultrasonic transducer (CMUT), as a new acoustic-electric conversion element, has a promising application prospect. In this paper, the structure of the vacuum capacitive micromachined ultrasonic transducer is presented, and its performance-influencing factors are investigated. Firstly, the influencing factors of the performance parameters of the vacuum CMUT are analyzed theoretically based on the circular plate model and flat plate capacitance model, and the design principles of the structural parameters of the CMUT cell are proposed. Then, the finite element simulation software COMSOL Multiphysics is used to construct CMUT cell models with different membrane materials, membrane shapes, membrane radius thicknesses, and cavity heights for simulation verification. The results show that both the membrane parameters and the cavity heights affect the performance parameters of the Vacuum CMUT. In order to improve the efficiency of the CMUT, materials with low bending stiffness should be selected, and the filling factor of the membrane should be increased. In order to achieve high-transmission sound pressure, a smaller radius thickness and a larger cavity height should be selected. To achieve high reception sensitivity, a larger membrane radius thickness and a smaller cavity height should be selected. In order to obtain high fractional bandwidth, a larger membrane radius thickness should be selected. The results of this paper provide a basis for the design of Vacuum CMUT cell structure.

Experimental Study of Impingement Effusion-Cooled Double-Wall Combustor Liners: Thermal Analysis

A new experimental study is presented for a combustor with a double-wall cooling design. The inner wall at the hot gas side features effusion cooling with 7-7-7 laidback fan-shaped holes, and the outer wall at the cold side features an impingement hole pattern with circular holes. Data have been acquired to assess the thermal and aerodynamic behavior of the setup using a new, scaled up, engine-similar test rig. Similarity includes Reynolds, Nusselt, and Biot numbers for hot gas and coolant flow. Different geometrical setups are studied by varying the cavity height between the two walls and the relative alignment of the two hole patterns at several different blowing ratios. This article focuses on the thermal performance of the setup. The temperature data are acquired using two infrared systems on either side of the effusion wall specimen. In addition to cooling effectiveness evaluations, finite element simulations are performed, yielding the locally resolved wall heat fluxes. Results are presented for three cavity heights and two longitudinal specimen alignments. The results show that the hot gas side total cooling effectiveness can achieve values as high as 90% and is mainly influenced by the effusion coverage. Impingement cooling has a small influence on overall effectiveness, and the area of influence is mainly located upstream where effusion cooling is not built up completely. The analyzed geometric variations show a major influence on cavity flow and impingement heat transfer. Small cavities lead to constrained flow and high local Nusselt numbers, while larger cavities show more equalized Nusselt number distributions. A present misalignment shows especially high influence at small cavity heights. The largest cavity height, in general, showed a decrease in heat transfer due to reduced jet momentum.

In-plane permeability changes of plain weave glass fabric induced by tufting

The presence of the tufts has direct influence on the permeability of textile preforms. In this paper, new insights are presented into the mechanisms responsible for changes to the in-plane permeability of tufted preforms according to three different tufting patterns relative to flow direction with a constant tufting distance. The saturated permeabilities are measured based on the rectilinear flow in a tool constituted by a steel base, a transparent PMMA top, and steel supports. Beforehand, the permeability measurements of textile preform composed of eight layers of plain weave glass fabric without tufting are conducted at three different cavity heights. The results show that the in-plane permeability values for the tufted preforms are lower than the permeability values of the preform without tufting. The paper reveals the significant influence of the tufting patterns on the permeability values for three different fibre volume fractions.

Shrinkage induced flow during directional solidification of pure substance in a bottom cooled cavity: A study on flow reversal phenomena

Development and proposition of a numerical model to capture the shrinkage induced flow during directional solidification of a pure substance in a bottom cooled cavity are carried out. A novel numerical scheme involving fixed grid-based volume fraction updating is proposed to track the solid–liquid interface, considering the inclusion of the shrinkage effect. Directional solidification in bottom cooled orientation is of particular interest since shrinkage and buoyancy effects oppose each other. The results from the proposed numerical model indicated the existence of an unprecedented flow reversal phenomenon during the progression of the solidification process, caused by the opposing nature of shrinkage and buoyancy effects. The flow reversal phenomena predicted by the numerical model are validated by conducting experiments involving directional solidification of coconut oil in a bottom cooled cavity. Qualitative and quantitative measurements of the velocity field and interface growth are obtained using the particle image velocimetry technique and compared with three dimensional numerical results. Once the flow reversal phenomena are established through numerical and experimental evidences, case studies are performed, considering varying material properties, cold boundary temperatures, initial temperatures of the melt, and cavity heights to find the effect of each of these parameters on flow reversal phenomena. The parametric study also allowed us to check the robustness and consistency of the proposed model. The proposed model will serve as an important milestone toward the development of numerical models for capturing macro-scale shrinkage defects and prediction of composition heterogeneity during directional alloy solidification.

Experimental Study of Thermal Buoyancy in the Cavity of Ventilated Roofs

Pitched wooden roofs are ventilated through an air cavity beneath the roofing in order to remove heat and moisture from the roof construction. The ventilation is driven by wind pressure and thermal buoyancy. This paper studies ventilation driven by thermal buoyancy in the air cavity of inclined roofs. The influence of air cavity design and roof inclination on the airflow is investigated. Laboratory measurements were carried out on an inclined full-scale roof model with an air cavity heated on one side in order to simulate solar radiation on a roof surface. Equipment to measure temperature was installed in the roof model, while air velocity in the cavity was determined by smoke tests. Combinations of different roof inclinations, air cavity heights and applied heating power on the air cavity top surface were examined. The study showed that increased air cavity height led to increased airflow and decreased surface temperatures in the air cavity. Increased roof inclination and heating power applied to the roofing also increased the airflow. The investigations imply that thermal buoyancy in the air cavity of pitched roofs could be a relevant driving force for cavity ventilation and important to consider when evaluating the heat and moisture performance of such a construction.

Does Le Fort I osteotomy have an influence on nasal cavity and septum deviation?

Le Fort I (LI) osteotomy has been used for the correction of dento-facial deformities of the midface. The aim of this study was to determine the effects of advancement and impaction of the maxilla with LI osteotomy on the nasal cavity and septum. In this study, 40 adult patients, 23 females and 17 males (mean age 20.52 ± 4.4 years), who underwent single-piece LI advancement and impaction surgery combined with a bilateral sagittal split osteotomy (BSSO) were included. Posterior-anterior (PA) and lateral cephalometric radiographs taken before surgery (T0) and at least three months after surgery (T1) were evaluated. The superior and anterior movements of maxilla, changes of the nasal cavity, nasal septum and maxillo-mandibular parameter were measured on the cephalometric radiographs. Treatment changes were statistically analyzed using paired sample t-test, and Pearson correlation analysis was applied for the determination of the relationship between variables. There was no statistically significant change in the deviation parameters (P > 0,05). However, a statistically significant decrease was found for left and right nasal cavity heights after LI osteotomy (P < 0.05). Furthermore, no significant correlation was found between septal deviation angle and extent of maxillary movement (P > 0.05). Positive correlation was found between nasal cavity width and amount of maxillary impaction. (P < 0.05). The influence of maxillary impaction with LI osteotomy on nasal septum deviation was not found significant but maxillary impaction with LI osteotomy significantly increased the nasal cavity width.

Prediction of shallow salt cavity geometry from surface subsidence configurations

Physical model tests are used to simulate surface subsidence induced by shallow salt cavity occurred at the interface between salt bed and overlying soil formation. Uniform fine sand with properties similar to the overburden soil is used in the models. The width and depth of sinkhole or subsidence trough induced under various cavity widths, heights, and depths are measured using 3-D laser scanner. The results indicate that for relatively shallow cavity, the increase of sinkhole depth closely relates to the increase of cavity height. The extent of subsidence area is sensitive to depth and width of the cavity. The maximum subsidence is not sensitive to cavity depth. The physical model results are fitted to empirical equations. They can be used to estimate the cavity height and width from the subsidence configurations under similar geologic conditions.

Usability of dental pulp visibility and tooth coronal index in digital panoramic radiography in age estimation in the forensic medicine.

Age estimation has a great importance due to legal requirements. The aim of our study was to determine the applicability of two different methods in age estimation; one of them based on the calculation of the visibility of the root pulp of mandibular third molar teeth and the other based on the calculation of the tooth coronal index (TCI) in the mandibular first and second molar teeth in the 9059 digital orthopantomogram of people aged between 15 and 40 in Bursa. In the first method in which the visibility of the fully mineralized root pulp of the mandibular third molar teeth was evaluated in 4 stages; the stages 0, 1, 2, and 3 were observed regardless of sex at the earliest 17.2; 19.1; 20.1, and 25.1 years, respectively. In the second method in which TCI was regressed on chronological age using measuring crown and coronal pulp cavity heights, the most accurate age estimation model based on simple linear regression for all cases without any sex difference was found to be with right first molar tooth (SEE ±7304 years) and the most accurate age model based on multiple regression model was found to be with bilateral first molar teeth (SEE ±7413 years). In conclusion, we believe that the root pulp visibility of the third molar teeth can be applied safely for stages 1, 2, and 3 at 16, 17, and 21 years of ages, respectively. A correlation was also found between TCI and age, and our findings have shown that both methods are available for forensic purposes.