Cavity Height Research Articles

The study of N-polar GaN/InAlN MOS-HEMT and T-gate HEMT biosensors

The sensing performance of N-polar GaN/InAlN MOS-HEMT biosensors for neutral biomolecules was investigated and compared with the Ga-polar MOS-HEMT and N-polar T-gate HEMT by numerical simulation. The results indicate that the N-polar GaN/InAlN MOS-HEMT biosensor has higher sensing sensitivity than the Ga-polar MOS-HEMT and N-polar T-gate HEMT biosensors. Furtherly, to improve the sensing performance of N-polar MOS-HEMT, the influence of cavity dimensions, GaN channel layer thickness, and InAlN back barrier layer thickness on device performance was investigated. It is demonstrated that the sensitivity of the biosensor increases as the cavity height decreases and the cavity length increases. Therefore, the sensing performance of the N-polar MOS-HEMT device will be enhanced by thinning the GaN channel layer thickness or increasing the InAlN back barrier thickness, which can be mainly attributed to the variation of the energy band structure and two-dimensional electron gas concentration in the HEMT heterostructure. Finally, the highest sensitivity can be obtained for the N-polar MOS-HEMT with 6 nm-thick GaN channel layer, 30 nm-thick InAlN back barrier layer, and two 0.9 μm-long and 5 nm-high cavities. This work provides structural optimal design guidance for the N-polar HEMT biosensor.

Optimal Design of Microchannel Heat Sink with Staggered Fan-Shaped Cavities and Ribs

In the present study, a three-dimensional numerical simulation is conducted to study the characteristics of fluid flow and heat transfer in a newly designed microchannel heat sink with fan-shaped cavities and ribs (MC-FCFR). The Reynolds number ranges from 147 to 736. A straight rectangular microchannel (MC-RC) is used as the baseline. The geometric parameters include the relative spacing θ, relative width α, and relative height β of the fan-shaped cavities and ribs. The overall performance index (OPI) of the MC-FCFR is evaluated in terms of the friction factor and Nusselt number. The OPI for the MC-FCFR with θ=3.56, α=1.63, and β=0.5 reaches 1.70.

A deep learning-based approach for the inverse design of the Helmholtz resonators

This article discusses the use of artificial neural networks in the design of Helmholtz resonators. A large database is constructed analytically by using the classical approach for computing the transmission loss and resonance frequencies of the Helmholtz resonators. In DNN, four geometric parameters, neck radius (rn), corrected neck length (ln) (derived from neck length (hn)), cavity radius (rc), and cavity height (hn) of the Helmholtz resonator, are the final output of the designed model which are mapped with the transmission loss and resonance frequency of the Helmholtz Resonators through our proposed neural network. A Feed-forward deep neural network (DNN) based on pre-transfer learning approach is used to map feature variables to target variables. The training follows the three major steps i.e., (a) Generalised pre-training in unsupervised manner, (b) Decoder pruning and regressor head training and (c) End to End regressor training using full backpropagation. This modularized approach removes the chances of overfitting, by effectively tuning the weights at each layer of the network. Each step focuses on creating a more structured and organized model. The best combination of the weight and biases is used for the prediction of the geometric parameters. Also, the finite element study of the transmission loss and resonance frequency supports the predicted geometric parameter of the randomly chosen sample for testing with the true value of the sample. It has been found that the accuracy of the model can be improved by training in a modular way. The approach discussed in this article can be useful to bypass the complex wave analysis approach for designing the Helmholtz resonators.

Bleb Morphology on Anterior-Segment Optical Coherence Tomography after XEN Gel Stent Implantation.

We investigated the internal morphology of filtration blebs after XEN gel stent implantation using anterior segment optical coherence tomography (AS-OCT) and identified factors related to intraocular pressure (IOP) postoperatively. Eighteen eyes of 18 patients who had undergone XEN gel stent implantation were analyzed. Blebs were imaged using Visante OCT (Carl Zeiss Meditec AG, Germany) at 6 months and 1 year after surgery and evaluated for quantitative parameters including bleb height, maximum height of internal cavity, maximum bleb wall thickness, and maximum bleb epithelial thickness. Subjects were classified into two groups according to the presence or absence of a definite internal cavity between the conjunctiva and sclera using AS-OCT imaging. Nine eyes (50%) were assigned to the internal cavity group and 9 (50%) to the uniform group. Postoperative IOP was significantly lower in the internal cavity group than in the uniform group both at 6 months and 1 year after surgery (p = 0.024 and p = 0.040). Postoperative IOP showed statistically significant negative correlations with bleb height and the height of the internal cavity (Spearman correlation coefficient r = -0.518, p = 0.028 and r = -0.453, p = 0.034, respectively). AS-OCT facilitates analysis of bleb morphology after XEN gel stent implantation. A larger height of the internal cavity of the bleb appeared to correlate with lower IOP after XEN implantation.

Structural optimization of slot-die heads with T-shaped cavity for fabrication of large-area OLEDs

With an attempt to achieve highly uniform large-area organic thin films for potential applications in solution-processable organic light-emitting diodes (OLEDs), we have optimized the structure of slot-die heads with T-shaped cavity (manifold) by computational fluid dynamics (CFD) simulation. Depending on the viscosity of coating solutions, the pressure distribution inside the cavity and the velocity distribution at the outlet are analyzed by varying the structure parameters such as the shim thickness, cavity volume (cavity depth, cavity height, cavity width), and land length. From CFD simulation results, we have derived the maximum shim thickness at which the pressure non-uniformity becomes less than 5 %, which can provide a simple and intuitive design guideline. It is addressed that the maximum shim thickness is most affected by the cavity width, followed by the cross-sectional area of the cavity and then the land length. Using the structurally optimized slot-die head, we have carried out slot-die coating of low-viscosity (80 cPs) poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and high-viscosity (4,800 cPs) polydimethylsiloxane (PDMS) and achieved thin films with the thickness non-uniformity less than 10 %. Furthermore, we have successfully fabricated 120 mm × 20 mm OLED devices with the slot-coated conductive PEDOT:PSS layer, exhibiting the luminance of 801 cd/m2 at 6 V.

Large eddy simulation of thermal stratification effects on tracer gas dispersion in a cavity

This paper assesses the effect of thermal stratification on the prediction of inert tracer gas dispersion within a cavity of height (H) 1.0 m, and unity aspect ratio, using large eddy simulation. The Reynolds number of the cavity flow, was 67 000. Thermal stratification was achieved through the heating or cooling of one or more of the walls within the cavity. When compared to an isothermal (neutral) case, unstable stratification from surface heating generally has a weak influence on the primary recirculating cavity vortex, except in the case where the windward wall is heated. For windward wall heating, a large secondary vortex appears at the corner of the windward wall and cavity floor. Unstable stratification has no significant influence on the removal of pollutant mass from the cavity. Stable stratification through surface cooling drastically alters the flow pattern within the cavity, pushing the cavity vortex towards the upper quadrant of the cavity. As a result, large regions of stagnant fluid are present within the cavity, reducing the effectiveness of the shear layer at removing pollutant concentration from the cavity. Some stable stratification configurations can increase the pollutant mass within the cavity by over a factor of five, when compared to the neutral case. Pollutant concentration flux maps show that, in stably stratified cases, the majority of pollutant transport from the cavity is the result of entrainment into the primary cavity vortex. The results show that pollutant concentrations in urban street canyon-type flows are substantially altered by diurnal heating and cooling, which may influence pedestrian management strategies in urban environments.

Improved Technology for Rounding Graphite: Machine Structure and Industrial Test

The graphite, which is treated to be potato-shaped, is widely applied in Li-ion batteries as the anodic material. Sequential batch shaping is the main method at present. However, the small height of the shaping cavity of the existing structure leads to the problem of low processing capacity and high cost. In this work, a new structure of the shaping machine was developed with the aim of shaping graphite by large output and costless. The equipment system for graphite rounding in a pilot scale at a treatment amount of 25 kg raw material each run was established. The results showed that the ratio of the diameters of the final product by an undersized percentage corresponding to 10% was 11.15 μm, 50% was 18.94 μm, and 90% was 29.54 μm, and tap density was 0.945 g/cm3, the yield reached 48%, under the optimized conditions of 1833 rpm rotating speed of shaping disk, 2646 rpm rotating speed of classifier, and 40 min shaping period. All the above characteristics of the rounded graphite are in line with the requirements for applying in the anode of Li-ion batteries. In short, the present study aims to provide a new structure of the shaping machine, contributing to the efficient and cost-effective rounding of graphite and revealing the structure of the shaping machine, contributing to promoting the wide improvement of the shaping machine.

Mechanical Response Law and Parameter Influence Analysis of Karst Tunnel Dynamic Excavation

To ensure the stability of the tunnel structure, this paper simulates the excavation process of shield tunneling in karst areas, and monitors the top of the arch, the bottom of the arch and the waist of the arch within the influence of the cave. It obtains the displacement and stress change laws under the influence of the upper cave and the lower cave. Finally, the main factors causing karst collapse in tunnels are explored through orthogonal tests. The results indicate that the displacement of the surrounding rock within the influence of the cave decreases and the stress increases. When the cavity and the tunnel reach the safety limit distance, the effect of the lower cavity on the stress around the tunnel is more obvious than that of the upper cavity. The results of the orthogonal test show that when the cavity is above the tunnel, the tunnel burial depth has the greatest influence on the stability of the surrounding rock; when the cavity is below the tunnel, the cavity height has the greatest influence on the stability of the surrounding rock.

Numerical Investigation of Electrical Efficiency with the Application of Hybrid Nanofluids for Photovoltaic Thermal Systems Contained in a Cavity Channel

Photovoltaic thermal systems (PV/T) are devices used to collect both electrical and thermal energies from solar energy. By passing a coolant through flow channels that are connected to the PV/T systems, the temperature of the cells is reduced to enhance their electrical efficiency. Therefore, this study aims at investigating a photovoltaic thermal system via the transport of hybrid nanofluids based on Cu-Al2O3/water. We assume that the flow channel can be considered in two dimensions and is composed of the silicon panel, absorber, and flow channel. The flow channel consists of a cavity along the absorber with a fixed length and a certain height. This will be a combined conduction and convection problem, with conduction occurring on the top two layers of the silicon panel and absorber. Modeling and simulation problems are performed using COMSOL Multiphysics 5.6. The aspect ratio from inlet height to cavity height is defined by Ar, and the volume fraction of Al2O3 is taken double that of Cu. The cell efficiency is analyzed by performing a parametric study by altering the Reynold number (100–1000), inlet temperature (50°C–450°C), the volume fraction of copper (0.01%–10%), and the aspect ratio (0.5, 0.7, 0.9, and 1). It is found that increasing the inlet temperature and aspect ratio decreases the cell efficiency while increasing the Reynolds number and volume fraction increases it. The maximum efficiency of the cell, about 6%, is achieved when the inlet temperature is 50°C, the volume fraction of copper is 10%, Re = 1000, and Ar = 0.5. It was also concluded that when the volume fraction of copper is 0.1, the increase in Reynolds number from 100 to 1000 is improving the cell efficiency by 0.5%. On the other hand, when increasing the volume fraction of copper from minimum to maximum at Re = 1000, the cell efficiency is increasing by 0.3%.

Shear capacity of the Hollow- Reinforced concrete beam with stirrup distance

The ability of reinforced beams to carry loads is determined by two factors, namely the ability to carry bending loads due to moments and the ability to carry shear forces. Previous tests have proven that the flexural capacity of hollow concrete beams is the same as that of normal reinforced concrete beams. This study aims to obtain the effect of shear force on the shear capacity of hollow reinforced concrete beams. In this study used reinforced concrete beams with a cross-section size of 175x350mm with a length of 3000mm. main reinforcement 3D16mm, stirrup reinforcement 8mm, spacing 150mm Material quality f'c = 25 MPa and fy = 400 MPa as control beams. (BN15). Next, blocks are made with the same size and material quality with a stirrup spacing of 10 cm (BN10) then the beams are given cavities using plastic bottles with a length of 3240mm (12 bottles), cavity height: 180mm/3 bottles. 2 hollow concrete beams were made with variations in the spacing of stirrups, namely 150mm (BR15) and 100mm (BR10). The load distribution was regulated by a 2-point load system, namely (a): 50 cm from each position so the value a/d = 1.6, Thus according to the Nawy theory a shear failure will be obtained. The loading is given gradually and gradually increased until failure occurs in the beam. The research aims to obtain the shear capacity of hollow reinforced concrete beams, thus the ability of hollow reinforced concrete beams to carry loads can be relied upon.

Nasal and Sellar Anatomic Variations in Pituitary-Dependent Cushing Disease.

Adrenocorticotrophic hormone excessive secretion in pituitary-dependent Cushing disease (CD) patients may lead to anatomic variations of the nasal-sphenoidal corridor as a result of hormone-induced abnormal soft tissue change. However, there is still a lack of data on anatomic dimensions in CD patients. In this study, magnetic resonance images were analyzed to determine the anatomic variations of the nasal cavity and sphenoid sinus in CD patients. A retrospective radiographic analysis was conducted on CD patients undergoing endonasal transsphenoidal surgery as primary treatment between January 2013 and December 2017. A total of 97 CD patients and 100 controls were included. The nasal and sphenoidal anatomic dimensions of CD patients were compared with the control group. Both sides of nasal cavity height, middle nasal meatus width, and inferior nasal meatus width in CD patients were narrower than that of controls. When compared with controls, the ratio of the middle turbinate to middle nasal meatus and the ratio of inferior turbinate to inferior nasal meatus was found to increase on both sides in CD patients. Intercarotid distance of CD patients was shorter than that of controls. The most prevalent pneumatization pattern of CD patients was postsellar, followed by sellar, presellar, and conchal. Cushing disease patients have nasal and sphenoidal anatomic variations affecting the endonasal transsphenoidal surgical corridor, especially the shorter intercarotid distance. The neurosurgeon should be aware of these anatomic variations, and adapt surgical techniques and optimal approaches to reach the sella safely.

Estimated Age Calculation with Tooth Coronal Index (TCI) Method Using Orthopanthomography in Malang City Population

Age estimation is an important aspect in forensics because it plays a role in determining individual identity. In cases of forensic identification of bodies that are difficult to identify visually or in poor condition, radiography is the choice of non-invasive method that can be used for age estimation, one of which is panoramic radiography. The Tooth Coronal Index (TCI) method is one method that can be used to identify a person's biological age through panoramic radiography. The purpose of this study was to compare the chronological age with the biological age obtained from the measurement of the TCI method on the mandibular premolars using panoramic radiography in the Malang City population. TCI measurement was done by measuring the height of the pulp chamber (Coronal Height) and the height of the crown of the tooth (Coronal Pulp Cavity Height) vertically from the Cemento Enamel Junction (CEJ) on the mandibular premolars. Then the value is entered in the regression equation that has been determined to obtain an estimate of biological age. Then, the results of the estimated biological age are compared with their chronological age. At last, the difference between biological and chronological age is calculated to determine the approximate age. The mean difference between chronological age and biological age was ± 1.32 years and there is no significant difference between the biological age and the chronological age (p value 0.11). TCI method on the mandibular premolars using panoramic radiography can be used to estimate age in Malang City Population.

Double-enhanced LIBS system with N2 atmosphere and cylindrical cavity confinement for quantitative analysis of Sr element in soil

To effectively improve the quality of laser-induced plasma spectra and the detection accuracy of laser-induced breakdown spectroscopy (LIBS) simultaneously for Sr element in soil, the dual mechanism of N2 atmosphere combined with cylindrical cavity confinement for laser-induced Sr plasma emission enhancement was proposed and investigated in this paper, and a multi-spectral fusion internal standard analysis model was established. Optimum enhancement effect can be achieved under the conditions of 2 mm diameter and 6 mm height of the confinement cavity in N2 atmosphere, where the enhancement factor was about 3.25, the signal-to-noise ratio reached 710.28, and the LIBS spectrum quality was the best; the relative standard deviation value (2.64%) was the smallest, and the LIBS signal reproducibility was the best. For the samples in this study, the limit of detection of the sample Sr elements under the dual enhancement mechanism was 34.60 mg kg−1, which was 40.43% lower than the limit of detection (LOD) without enhancement mechanism (58.08 mg kg−1), and the R 2 of the multispectral fusion internal standard model was 1.23% higher and the relative error was 3.41% lower than that of the internal standard method. The results showed that the dual enhancement mechanism combining N2 atmosphere and cylindrical cavity confinement improved the spectral quality, signal reproducibility, and detection sensitivity.

Research on the influence of cavity on compressive strength of electron beam controlled projectile

Fragments were premade on the cylindrical projectile using electron beam controlled technology, which induces cavities inside the material. Axial maximum compressive strength of the projectile is influenced by the structural parameters of cavity, including height, width, depth, slant angle, included angle, and circumferential quantity. Nonlinear dynamic software LS-DYNA was used to calculate the maximum compressive strength of each projectile with different cavity structure. Strength Influence Coefficient (SIC) was introduced to quantitatively characterize the influence of the cavity parameters on the axial maximum compressive strength of the projectile. The functions between the SIC and the cavity structure parameters were fitted, and an engineering predictive model was derived. Linear relationship was found between the maximum compressive strength and cavity height, width and circumferential quantity. The influence of cavity depth, slant angle and included angle on the maximum compressive strength was not obvious. The error between the calculation results of the predictive model and the experimental tests is 0.51%, which verifies the accuracy of the engineering predictive model.

D-Band Air-Filled Substrate Integrated Waveguide (AFSIW) and Broadband Stripline to AFSIW Launcher Embedded in Multi-Layer PCBs

We report <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$D$</tex-math> </inline-formula> -band air-filled substrate integrated waveguides (AFSIWs) with solid copper sidewalls fabricated inside a multi-layer printed circuit board (PCB) with broad wall width of 1.6 mm and cavity height of 300 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu$</tex-math> </inline-formula> m. Measurements show a loss of 0.07–0.08 dB/mm across 115–155 GHz. This result is the first demonstration of an AFSIW above 100 GHz in a low-cost mass manufacturable PCB and has the lowest loss compared to reported planar PCB lines or substrate integrated waveguides (SIWs) in PCBs and Interposers. We also introduce a broadband stripline to the AFSIW launcher using a broad wall transverse slot which offers ease of manufacturability over existing transitions having a measured insertion loss of 1.1 dB and 27% bandwidth. The combination of a low-loss AFSIW and wideband launcher allows both striplines and AFSIWs to coexist in the same multi-layer PCB.

Breakdown characteristics in dielectric-confined microcavity discharge of plate electrodes

Breakdown characteristics in dielectric-confined microcavity discharge of plate-to-plate electrodes under DC voltage are investigated in this paper. Experimental and particle-in-cell/Monte Carlo code simulated results show that the breakdown characteristic curve (the relation between the breakdown voltage V br and the product pd of gas pressure p and electrode gap d or the V br–pd curve) with a microcavity effect will deviate from the traditional Paschen curve, and seed electron adsorption by the dielectric wall is considered as the deviation mechanism. A smaller microcavity height will enhance this deviation. Based on the extent of deviation, there exist two critical microcavity heights, h cr1 and h cr2, for the breakdown characteristic curve. When the cavity height h is larger than h cr1, the V br–pd curve conforms to Paschen’s law due to the minor adsorbed electrons. When h < h cr1, the V br values in the V br–pd curve begin to increase overall, compared to those in the Paschen curve. Specifically, when h cr2 < h < h cr1, the V br–1/h curve exhibits a positive linear relation; when h < h cr2, V br increases sharply with 1/h as a nonlinear relationship due to the massive adsorbed electrons. Additionally, the type of dielectric material used to construct the microcavity also has a significant impact on V br, which is related to the different electron adsorbility η of various dielectric walls. For deeper insight, a ‘microcavity effect’ analysis model was developed to discuss the modified V br–pd curve and provide the explanation for the critical values of microcavity heights and the influence of the dielectric material. Significant adsorption of charged particles (especially the seed electrons) by the dielectric wall will reduce the electron multiplication and further improve the breakdown voltage when the cavity height h is comparable to the product ηλ e (the dielectric electron adsorbility and electron mean free path). On this basis, the modified breakdown criterion considering the microcavity effect was derived. The analytical expressions of the two critical height values h cr1 and h cr2 (h cr1 = 100ηλ e, h cr2 = 10ηλ e) and the linear relation of V br–1/h curve in h cr2 < h< h cr1 are presented quantitatively.

A high sensitivity and multi-axis fringing electric field based capacitive tactile force sensor for robot assisted surgery

This paper presents a design of multi-axis tactile force sensor using the fringe effect of an electric field between stationary patterned electrodes. The unique configuration of the electrodes consisting of four separate square-shaped sensing electrodes, with each encircled by excitation electrodes, allows to achieve enhanced fringe field effect and hence sensitivity. The proposed sensor can decouple the normal, shear and angular shear applied forces. The sensor is fabricated using low-cost rapid prototyping techniques with flexible Ecoflex 00–30 and silicone rubber RTV-528 as the elastomers for contact with the environment. An analytical model is developed that correlates the nominal capacitance of the sensor with that of the geometric dimensions of the stationary electrodes and air cavity height between the electrodes and elastomer. The force measurement ranges in the normal, shear, and angular axis are 5 N, 1.5 N, and 1 N respectively. The sensor shows a perfectly linear response, repeatability, and a low hysteresis error, thermal stability and robustness to the environmental interferences that makes it suitable to be used for force feedback in minimally invasive robotic surgery.

Gain Enhancement and Cross-Polarization Suppression of Cavity-Backed Antennas Using a Flared Ground Cavity and Iris.

Herein, we present new design principles for gain enhancement and cross-polarization suppression in dual-polarized cavity-backed antennas and demonstrate the capability in an octagonal cavity-backed open prism antenna (OCROP). In our approach, the gain is enhanced through an optimal flaring procedure and a novel metallic iris is used to control the electromagnetic fields and thereby reduce the cross-polarization. Previously, we investigated a dual-polarized OCROP antenna configuration and were able to simultaneously achieve 50% impedance bandwidth, 40% cross-polarization bandwidth (≤25 dB), and 10.2 dBi peak gain. In this study, we investigated gain enhancement by flaring an upper section of the ground cavity sidewalls, while maintaining a constant cavity height. Two cases were investigated: (1) the flare angle was modified, while the ratio of the non-flared to flared sidewall heights was kept constant, and (2) the ratio of the non-flared to flared sidewall heights was varied. In case 1, we established that, while increasing the flare angle results in a gain increase, there is a limit, as cross-polarization at the upper operating frequencies increases. In case 2, we were able to reduce the aperture phase error and achieve a higher peak gain of 12.8 dBi. To address the increased cross-polarization at the high frequency end when a large flare was used, we added a metallic iris at the junction of non-flared and flared sidewalls. We showed that increasing the iris width generally decreases the cross-polarization at high frequencies, without compromising the gain and impedance bandwidth. At an optimal width, it provides a nearly constant, low cross-polarization (below -25.8 dB) and a peak gain of 13.3 dBi, across the entire 50.7% impedance bandwidth of the antenna. We fabricated and successfully tested a prototype to verify the design and simulation approach. These results prove that incorporating an aperture flare with a metallic iris can significantly improve the gain and cross-polarization performance of cavity-backed antennas.

Morphological study of glenoid cavity of scapula

Scapula is a flat triangular bone lies on chest wall from second to sixth ribs. Its lateral angle is truncated and shows variable morphology in shape. The objectives of the present study were to obtain morphometric data of scapulae and the glenoid cavity specifically the diameters and various shape of glenoid.: The present study was conducted on 90 right scapulae and 90 left scapulae. Metrical and nonmetrical measurements were noted. Length of scapulae, breadth of scapulae, height of Glenoid cavity, antero-posterior diameter 1 and antero-posterior diameter 2 were observed. Shape of Glenoid cavity was noted.Length of scapula on right side was 135.40±13.2mm and on left side it was 136.5±12.9mm. Breadth of scapula on right side was 98.7 ±7.2mm on left side it was 98.2±6.8mm but the difference was not statistically significant. The height of Glenoid cavity on right side was 35.2±2.9mm and on left side it was 35.8±3.1. Antero-posterior diameter 1 of Glenoid cavity on right side was 24.2±2.3 mm and on left side it was 23.9±2.1 mm. Antero-posterior diameter 2 of Glenoid cavity on right side was16.8±2.5 mm and on left side it was 16.7±2.4mm. The most common shape of glenoid cavity was pear shaped followed by oval and least common was inverted comma shape.Knowledge of various measurements of Glenoid cavity is important for prosthesis of shoulder orthoplasty. It is useful in evaluation of various pathological conditions of shoulder joint. Since this study was conducted on limited number of scapulae further clinical, cadaveric and radiological studies are required.

Broadband low-frequency sound absorption of honeycomb sandwich panels with rough embedded necks

A hexagonal honeycomb sandwich panel with rough embedded necks is proposed as a new structure for broadband low-frequency sound absorption. A theoretical model is established to study the sound absorption performance of the structure, and a finite element model is also developed to explore its sound absorption mechanism. The results show that the structure has excellent broadband low-frequency sound absorption performance. The energy dissipation mainly occurs in the neck, and the energy dissipation of the neck can be enhanced by adjusting the relative roughness of the neck. As a result, the sound absorption peak of the structure increases and the peak frequency shifts towards low frequencies. Also, thinner structures will shift the peak frequency to high frequencies. By reasonably adjusting the height of the honeycomb cavity and the relative roughness of the neck, the effects of these two changes can be balanced to achieve the perfect sound absorption of the thinner structure in the low frequency band. Based on the electro-acoustic analogy method, the broadband perfect sound absorption of thin structure in low frequency can be realized by reasonably paralleling different units with rough embedded necks. Experimental measurements are carried out, and favorably verify the theoretical model and the finite element model, as well as the broadband low-frequency design scheme. This work opens up a new way to design thin acoustic metamaterials for broadband low-frequency sound absorption.