Flat Diaphragm Research Articles

Experimental, theoretical, and numerical evaluation of innovative precast-slab-joint connections under tensile scenarios

Four innovative mechanical connectors designed for improving the integrity of untopped flat diaphragms are proposed. Compared to traditional connectors, the innovative connectors avoid premature weld tearing, possess higher strength and ductility, which are not only suitable for double-tees but also applicable to untopped flat slabs with lower structural heights and smoother undersides. This allows for greater story heights or more stories within the same building height, which is important in driving the development of fully assembled structures. This paper summarizes the tensile performance of innovative connectors observed during the cyclic loading scenarios. Four sets of single-slab experiments were conducted, with each set consisting of a pair of connectors. Based on experimental findings, the theoretical formulas for connection strength and stiffness were provided. Connector optimization was performed in conjunction with the failure modes. Finally, using numerical simulation techniques, a parameter analysis was conducted on the influence of steel plate (or rebar) thickness (or diameter) and material strength on the resistance and deformability of innovative connectors. The results indicated that innovative connectors fully developed the ductility of steel and achieved a ductile failure mode. The strength and deformability of optimized connectors were improved due to the strong anchoring of L-shaped steel plate. The thickness (or diameter) of steel plate (or rebar) and the steel grade significantly impacted the tensile performance of the connectors. Design and application recommendation were proposed for innovative connectors.

Piezoelectric Micromachined Ultrasonic Transducers with Micro-Hole Inter-Etch and Sealing Process on (111) Silicon Wafer.

Piezoelectric micromachined ultrasound transducers (PMUTs) have gained significant popularity in the field of ultrasound ranging and medical imaging owing to their small size, low power consumption, and affordability. The scar-free "MIS" (micro-hole inter-etch and sealing) process, a novel bulk-silicon manufacturing technique, has been successfully developed for the fabrication of pressure sensors, flow sensors, and accelerometers. In this study, we utilize the MIS process to fabricate cavity diaphragm structures for PMUTs, resulting in the formation of a flat cavity diaphragm structure through anisotropic etching of (111) wafers in a 70 °C tetramethylammonium hydroxide (TMAH) solution. This study investigates the corrosion characteristics of the MIS technology on (111) silicon wafers, arranges micro-pores etched on bulk silicon around the desired cavity structure in a regular pattern, and takes into consideration the distance compensation for lateral corrosion, resulting in a fully connected cavity structure closely approximating an ortho-hexagonal shape. By utilizing a sputtering process to deposit metallic molybdenum as upper and lower electrodes, as well as piezoelectric materials above the cavity structure, we have successfully fabricated aluminum nitride (AlN) piezoelectric ultrasonic transducer arrays of various sizes and structures. The final hexagonal PMUT cells of various sizes that were fabricated achieved a maximum quality factor (Q) of 251 and a displacement sensitivity of 18.49 nm/V across a range of resonant frequencies from 6.28 MHz to 11.99 MHz. This fabrication design facilitates the achievement of IC-compatible and cost-effective mass production of PMUT array devices with high resonance frequencies.

Direct contractility measurement in cardiomyocytes via thin PDMS diaphragm integration with a moving coil actuator: Synergistic maturation through combined topographical and mechanical stimulation

Mechanical stimulation within diaphragm-based cell culture platforms presents a promising strategy to enhance cardiomyocyte maturation. However, most of the proposed techniques have met with limited success due to their inability to directly measure the contractile force of cardiomyocytes. This issue primarily stems from the typically thicker diaphragm structure which is necessary to withstand high strain ranges induced by mechanical stimulation. Herein, we propose a moving coil actuator integrated with a thin polydimethylsiloxane (PDMS) diaphragm for precise mechanical stimulation, cell culture, and drug screening applications. This mechanical stimulation system generates desired mechanical deformation to cultured cardiomyocytes without compromising the integrity of the diaphragm structure. The 10 µm thin diaphragm produces significant displacement from the contractility of cultured cardiomyocytes, which can be directly measured using a laser vibrometer system. Cardiomyocytes cultured on nanogroove PDMS diaphragms with and without stimulation and flat diaphragms with stimulation exhibited 4.25-, 2.81-, 2.39-fold enhancements in contraction force and 1.09-, 1.06-, 1.04-, and 1.32-, 1.17-, 1.16-fold enhancements in sarcomere lengths and Connexin 43 (Cx43) compared to counterparts cultured on flat and nanogroove PDMS diaphragms without stimulation. The practicality of the device as a drug screening platform is demonstrated by examining the drug-induced effects on cardiomyocytes using cardiovascular drugs.

Development of geometry variants and forming technology for metal diaphragms to increase the efficiency of diaphragm compressor

This article outlines the development of an elastically foldable, bistable diaphragm geometry that enables an increase in the compression volume of diaphragm compressors compared to the use of flat diaphragms. Using a Finite Element Model (FEM) in ABAQUS/Standard, several membrane geometries (truncated cone, cone, and dome) were calculated and analyzed with regard to their elastic deformation. Selected geometries were produced using Single Point Incremental Forming (SPIF) and tested by applying full-area pneumatic pressure to determine the diaphragm’s lifetime.

Parametric Analysis of Blast Load Effect On Diaphragm Wall In Basement

There are various kinds of loads acting on the basement structure of a building, blast load for an example. In this study, the effect of variation of the structural and soil parameter values on the response of the basement structure due to blast load will be analyzed. Thus, it can be seen the influence of the tested parameters. The deformation of the diaphragm wall will be the focus of this research. This research will be using Midas GTS NX program in modeling the basement structure of the building and the surrounding soil using the finite element method. The analyzed basement structure consists of flat slabs, diaphragm wall, king posts, raft, and pile foundation. The analyzed blast load is a surface blast load of 40000 liters of gasoline that occurs at a distance of 20m from the building and will be analyzed using the time history method. The analysis was carried out on 12 parameters: the void ratio of soil, the density of soil, cohesion, undrained shear strength, elasticity modulus of soil, poisson ratio of soil, porosity, structural damping ratio, damping ratio of soil, shear angle of soil, diaphragm wall’s thickness, and concrete’s quality of the diaphragm wall. From the results of the analysis, it is found that the parameters that affect the deformation of the diaphragm wall are the modulus of elasticity of the soil, density of soil, the poisson ratio of the soil, diaphragm wall’s thickness, and the concrete’s quality of the diaphragm wall. The soil modulus of elasticity has greatest influence on deformation changes, which is 282.27%, while concrete compressive strength of diaphragm wall has smallest influence, which is 0.87%.
 

The effect of topographical and mechanical stimulation on the structural and functional anisotropy of cardiomyocytes grown on a circular PDMS diaphragm

Due to their immature morphology and functional immaturity, cardiomyocytes have limited use as an in vitro disease model of the native heart. Mechanical stimulation induces structural growth in cardiomyocytes in vitro by addressing the electrical-mechanical interactions between the tissues. However, current in vitro models are restricted in their capacity to replicate the milieu observed in natural myocardium. Herein, we proposed a Galinstan strain sensor integrated nanogrooved circular PDMS diaphragm to mimic the native cardiac tissues. The impact of combined topographical and mechanical stimulation on cultured cardiomyocytes at various strain areas on a circular PDMS diaphragm is studied in detail. An inverted microscope is used to image live cells and video acquisition to study the contractility of cultured cardiomyocytes. The structural changes of the cultured cardiomyocytes are investigated by its sarcomere length and connexin-43 (Cx43) expression using immunocytochemistry analysis. Cyclic strain is found to promote structural development in cultured cardiomyocytes, and diaphragms with nano-groove patterns displayed increased contractile activity and gene expression (sarcomere length ∼1.97 ± 0.03 μm and normalized Cx43–1.57) as compared to flat diaphragms (sarcomere length ∼1.82 ± 0.02 μm and normalized Cx43–1.32). The nanogrooved circular diaphragm exhibited distinct stretching mechanisms at various places, with the equibi-axial stretching regions providing the optimal structural growth and formation of natural myocardium at the diaphragm's center. Cardiomyocytes that are more mature have the potential to produce a more realistic in vitro cardiac model for disease modeling and medication development.

Prune belly syndrome: Anesthetic challenges and management

Prune Belly syndrome (PBS) is a triad of absence of abdominal muscles, urinary tract malformations, and undescended testes. Due to partial or complete lack of abdominal muscles and flat diaphragm, there could be difficulty in breathing and effective coughing. It can also be associated with chest wall deformities which can cause increased incidence of respiratory infections and lead to complications in the peri and postoperative period. Here, we have discussed about the anesthetic challenges in 1-month-old baby diagnosed with PBS who was posted for cystoscopy.

MODEL TESTING OF THE "PILE-SOIL" INTERACTION UNDER AXIAL FORCE

Modern marine structures (berths, breakwaters, offshore platforms, etc.) often include steel tubular piles of essential length (80-100 m and more) that should provide high bearing capacity in case of external axial loads application. Interaction between elements of the system “piled structure – soil media” is not studied sufficiently yet. It relates also to the bearing capacity of the long steel tubular piles of large diameter. One of the interesting peculiarities of long tubular piles behavior is the formation of soil plug at the piles tip. There are a lot of suggestion and methods aimed to increase piles bearing capacity under static pressing load. One of them relates to use of the additional structural element, i.e., the internal diaphragm welded to the internal surface of the pile shaft. Such approach has been applied in some practical cases of marine construction and demonstrated its effectiveness. At the moment there are no researches focused on study of the peculiarities of internal diaphragm application. So proposed research aimed to study two connected processes during steel tubular pile driving: soil plug formation at the tip of the open-end pile and soil behavior under the internal diaphragm fixed inside the tubular pile shaft. To study mentioned processes we provided several series of laboratory experiments fulfilled at the Geotechnical laboratory of the Department “Sea, River Ports and Waterways” in Odessa National Maritime University. In these experiments the model of steel tubular pile has been driven (pressed) into fine sand by mechanical jack. The first series was devoted to determination of the conditions related to the soil plug formation at the pile tip. The next series were aimed to study the influence of the flat rigid diaphragm inside the pile shaft. Obtained experimental results allow to conclude that (a) in the fine sand the plug is formatted at the comparatively early stage of pile installation (in case of our modeling – at the penetration depth of some 4-5 pile diameter); (b) our empirical assessment of the conditions of soil plug formation corresponds to the approaches based on PLR and IFR characteristics; (c) formation of soil plug at the pile tip is followed by decreasing of soil level in the pile shaft relatively its initial value (on completing the plug formation the soil level in the shaft become stable); (d) regarding above mentioned, we may note that in case of use of internal diaphragm on the recommended depth (5-7 pile diameters) there may be no contact between diaphragm and the soil inside the pile (e) application of the diaphragm may lead to increasing of the pile’s bearing capacity. It was proposed (and checked by our tests) the technological improvement based on sand filling into space under the internal diaphragm to provide constant diaphragm-soil contact and related soil resistance.

Stress, sensitivity and frequency analysis of the corrugated diaphragm for different corrugation structures

Corrugated and flat circular diaphragm-based piezoresistive pressure sensors are designed and proposed for different applications. Regarding to different criteria including maximum stress, sensitivity and natural frequency, different diaphragms with semicircular, sinusoidal and trapezoidal corrugation are modeled, simulated and investigated in finite element software. The finite element model is validated by experimental results from the literature and also with theoretical formula to ensure the accuracy of the finite element modeling process. Wavelength and location of the corrugation are optimized to achieve best performing sensor. For the application with large acceptable induced stress, circular flat diaphragm is proposed. To enhance the sensitivity of the sensor as a crucial parameter, semicircular corrugation for circular diaphragm with 360 μmm wavelength and 240 μmm distance from the center is designed and proposed. This configuration shows obvious improvement of the sensitivity with more than 18% enhancement. To extend the working range of the sensor regarding to input frequency, trapezoidal corrugation with 360 μm wavelength and 240 μmm distance from the center is proposed to reach more than 29% enlargement in first natural frequency. Eventually, this paper tries to provide an overview to design the optimal pressure sensor according to desired specifications.

FCS technology: A novel electrodynamic transducer architecture

For a century now, acoustic electrodynamic transducers have been bound by axisymmetric motor structures for high performance due to the assumption in transducer theory that the diaphragm moves pistonically for all operating frequencies. This is of course a flawed assumption, and results in much research and development being focused on the vibro-acoustic components of the driver to minimize cone breakup at higher frequencies.A new architecture for the electrodynamic motor has been developed which helps to address this inherent problem. Flat Core Speaker (FCS) technology presents an architecture that is a rearrangement of the conventional electrodynamic motor structure with a planar voice coil and bobbin assembly that is situated between two parallel bar magnets. This results in a high aspect ratio design where the bobbin runs along the length of a flat diaphragm, leading to even force distribution, and therefore pistonic movement, while utilizing a thin profile with a flat diaphragm. COMSOL simulations and Klippel measurement data support these claims and show evidence of FCS technology having comparable performance to conventional drivers in a slimmer profile and blowing conventional high aspect ratio driver performance out of the water.

Impact of the diaphragm structure on the linearity and temperature sensitivity of low-pressure piezo-resistive MEMS pressure sensors

This paper presents result of a detailed simulation study aimed at optimizing the different diaphragm structures of silicon micro machined MEMS pressure sensor for operation and measurement of the low-pressure ranges(600mbar). We first show that the conventional arrangement of the Wheatstone bridge resistors realized using the “Flat diaphragms” give rise to large temperature dependence of the offset voltage which affects the sensitivity and linearity of the pressure sensors during operation in the temperatures ranging from-40°Cto+80°C, thus making the temperature compensation of the sensor output voltage rather tedious and impossible in certain instances. We further demonstrate that, this issue can be circumvented and excellent linearity with minimum dependence of the offset-voltage, sensitivity and linearity can be achieved by using “sculptured diaphragms” with optimized diaphragm dimensions. Towards this goal, in this paper, we present a set of simulation studies involving optimization of the pressure sensor diaphragm dimensions and structures with single and multiple boss structures to achieve better sensitivity, linearity, and at the same time minimize temperature drift, and to achieve better repeatability.

Reviews on Corrugated Diaphragms in Miniature Fiber-Optic Pressure Sensors

Corrugated diaphragms (CDs) have been widely used in many fields because of their higher pressure sensitivity and wider linear range compared to flat diaphragms (FDs) in the same circumstances. Especially in the application of miniature fiber-optic pressure sensors, the introduction of the corrugated structure gives the sensor high sensitivity, large dynamic range, good linearity, small hysteresis, good stability, and so on. Research on CD-based miniature fiber-optic pressure sensors has gradually attracted more attention in recent years. In this paper, the principles of operation of a miniature fiber-optic pressure sensor are briefly introduced, then the mechanical properties of FD and CD, as well as their influences on the performance of the sensor, are analyzed in detail. The application status of CDs in miniature fiber-optic pressure sensors is reviewed, and our conclusions and the prospects for the application of CDs in miniature fiber-optic pressure sensors are given finally.

Harnessing the bilinear nonlinearity of a 3D printed biomimetic diaphragm for acoustic sensor applications

Abstract This study presents an initial assessment of a newly shaped biomimetic diaphragm aimed at mimicking the function of the tympanic membrane (TM) of the human auditory system. The TM consists of three parts, namely, the malleus, pars tensa, and pars flaccida, and its dynamic behavior is typically known to be different from other common, thin membranes. The constructed membrane has a curved conical shape with the apex pointing medially, and with an initially bucked shape. The malleus is also firmly attached to the medial surface of the membrane at its center. In addition, the TM is connected to a surrounding annulus ligament (muscle) and is concave at its deepest part (the umbo). As a result, the TM does not move as a normal flat and thin diaphragm. In this study, we investigated the bilinear nonlinearity of an elliptic and conical shaped diaphragm similar to the actual TM of the human auditory system to deliver improved vibrating characteristics. It is reported that the proposed adaptively diaphragm structure fabricated by using 3D printing technology can exhibit bilinear nonlinearity when the sound pressure level (SPL) of the incoming sound is high, thus resulting in a flat sensitivity and a broad frequency response.

Design and analysis of hairpin piezoresistive pressure sensor with improved linearity using square and circular diaphragms

A novel structure for piezoresistive pressure sensors is proposed. The structure comprises two piezo-resistors, one mounted on a flat diaphragm and the other mounted outside of the diaphragm so that a hairpin-shaped structure is formed. As a result, one of the piezo-resistors will be affected by the input pressure and the other one will not. Also an inverting Operational Amplifier (OP-AMP) amplifier is utilised. The proposed pressure sensor can be designed using both square diaphragm or circular diaphragm and it has the advantage of higher linearity for input pressure range of 1 MPa in comparison with conventional structures. The value of nonlinearity (NL) is decreased from 0.5515% full-scale (FS), for the conventional sensor, to 0.1138% FS (for the proposed sensor with square diaphragm) and 0.0761% FS (for the proposed sensor with circular diaphragm), which shows an improvement in reducing NL about 80% in square diaphragm and about 86% when circular diaphragm is employed. The proposed structure is analysed and simulated using COMSOL multiphysics software.

청각기관 고막을 생체 모방한 다이어프램의 쌍선형 강성 특성

This study presents the preliminary study for a new shaped diaphragm structure aimed at mimicking the function of the tympanic membrane (TM) of human auditory systems. The TM consists of three parts: malleus, pars tensa, and pars flaccida, and the dynamic behavior of the TM is typically known to be different from other common thin membranes. In other words, the shape of human TM is elliptic and conical, and the TM does not move as a normal flat and thin diaphragm. We investigated the bilinear nonlinear stiffness of elliptic and conical shaped diaphragm similar to actual TM of human auditory system to deliver improved vibrating characteristics. The diaphragm structure made by 3-D printing technology can exhibits the bilinear nonlinearity when the sound pressure level (SPL) of incoming sound is high, resulting in the flat and broad frequency response.

Theory and Experimental Verification on Cymbal-shaped Slotted Valve Piezoelectric Pump

Valve piezoelectric pumps usually have larger flow rate than that of valveless ones. However, the traditional cantilever valve easily induces stress concentration which impacts the reliability of pumps. Therefore, a cymbal-shaped slotted check valve is proposed to be applied in a piezoelectric pump in order to reduce the stress concentration of the valve and thus improve the reliability of the piezoelectric pump. The structure and working principle of the piezoelectric pump are analyzed; the stress analysis of the cymbal-shaped slotted valve diaphragm is conducted. In addition, finite element software is employed to analyze the difference of the Von-Mises stress between the cymbal-shaped slotted diaphragm and the slotted flat diaphragm. The simulation results show that, the Von-Mises stress of cymbal-shaped slotted diaphragm is smaller than that of the slotted flat one. Furthermore, the cymbal-shaped slotted valve piezoelectric pump is also fabricated, and flow rate experiment is performed. The experimental results indicate that the flow rate of piezoelectric pump working in low frequencies (0 Hz < f < 50 Hz) is larger than that working in high frequencies (200 Hz < f < 2000 Hz). When driven at voltage of 160 V and frequency of 5 Hz, the pump reaches its maximum flow rate of 6.6 g/min. The experimental results validate the feasibility of the cymbal-shaped slotted check valve. This research can effectively solve the problem of stress concentration of valve piezoelectric pumps and is helpful for improving the reliability of them.

The "Flat Diaphragm": Does the Degree of Curvature of the Diaphragm on Postoperative X-Ray Predict Congenital Diaphragmatic Hernia Recurrence?

The appearance of the diaphragmatic curvature and the rib insertion level of the diaphragm on postoperative chest X-ray (CXR) may predict recurrence. Our purpose was to examine the relationship between the curvature of the diaphragm on postoperative CXR and recurrence. We performed a retrospective review of left-sided, Bochdalek congenital diaphragmatic hernia (CDH) surgical repairs from 2004 to 2015 at a single institution. We developed a tool to measure the flatness of the diaphragm on postoperative CXR, termed the diaphragmatic curvature index (τ). The primary outcome of interest was recurrence after surgical repair. Of the 127 patients identified, 54% (n = 69) had a primary repair, while 46% (n = 58) required a patch repair. The overall recurrence rate was 21.3% (n = 27). There was no difference in median lateral rib insertion level in patients with and without recurrence or those who had a primary or patch repair. The overall median diaphragmatic curvature index was 6.29 (interquartile range [IQR] 5.30-8.09) and was not significantly different among patients who had a recurrence (6.00, IQR 5.34-8.24) and those who did not (6.46, IQR 5.24-8.07) (P = .853). Within the primary repair group (6.34 versus 6.93, P = .84) and the patch repair group (5.59 versus 6.18, P = .46), the median diaphragmatic curvature index was not different among patients who had a recurrence and those who did not. A flat appearance of the diaphragm on postoperative CXR as measured by the median diaphragmatic curvature index (τ) is not associated with recurrence. The shape of the diaphragm on CXR after CDH repair may not be predictive of recurrence as previously thought.

A band-stop filter designed on a ridge waveguide with pin resonant elements

Results of the electromagnetic analysis of single pin resonant elements in ridge rectangular waveguides are presented. The equivalence of scattering characteristics of pin elements and thin flat transverse diaphragms is shown. Electromagnetic fields and cutoff wave numbers of ridge waveguides are determined by the partial domain method taking into account the field singularity at the edge. Results of the synthesis of a three-resonator band-stop filter with a stopband of 7.5% and a passband reflection level of no more than–20 dB in the entire waveguide operation band are presented.

Neck

ABSTRACTCystic hygroma (CH) is the most frequently seen fetal neck mass on the first-trimester ultrasound (US). Overall prognosis is poor with a high association with chromosomal and structural anomalies. When diagnosed prenatally, fetal karyotyping and detailed US evaluation should be offered. Prenatal and postnatal surgical or nonsurgical treatment options are available. Fetal goiter (FG) and fetal thyroid masses are rare fetal conditions and may occur as part of a hypothyroid, hyperthyroid, or euthyroid state. Screening for FGs should be carried out in pregnancies of mothers with thyroid disease. If a FG is detected, a detailed US examination should be performed. Congenital high airway obstruction syndrome (CHAOS) is characterized by bilaterally enlarged lungs, flat or inverted diaphragms, dilated tracheobronchial tree, and massive ascites. It is usually a lethal abnormality. Fetuses with suspected CHAOS should be referred to a fetal medicine center able to perform ex utero intrapartum treatment (EXIT) delivery. Neck teratomas are associated with high mortality rates. Prenatal US diagnosis of cervical teratoma can be made at 15 and 16 weeks of gestation. Planning of delivery in a tertiary center allows the performance of EXIT. Lymphangioma of the neck usually diagnosed in late pregnancy could be traditionally referred to as CH, but there is a different prenatal history and outcome.How to cite this articleVladareanu R, Vladareanu S, Berceanu C. Neck. Donald School J Ultrasound Obstet Gynecol 2016;10(3): 256-270.

The Design and Optimization of a Highly Sensitive and Overload-Resistant Piezoresistive Pressure Sensor.

A piezoresistive pressure sensor with a beam-membrane-dual-island structure is developed for micro-pressure monitoring in the field of aviation, which requires great sensitivity and overload resistance capacity. The design, fabrication, and test of the sensor are presented in this paper. By analyzing the stress distribution of sensitive elements using the finite element method, a novel structure incorporating sensitive beams with a traditional bossed diaphragm is built up. The proposed structure proved to be advantageous in terms of high sensitivity and high overload resistance compared with the conventional bossed diaphragm and flat diaphragm structures. Curve fittings of surface stress and deflection based on ANSYS simulation results are performed to establish the sensor equations. Fabricated on an n-type single crystal silicon wafer, the sensor chips are wire-bonded to a printed circuit board (PCB) and packaged for experiments. The static and dynamic characteristics are tested and discussed. Experimental results show that the sensor has a sensitivity as high as 17.339 μV/V/Pa in the range of 500 Pa at room temperature, and a high overload resistance of 200 times overpressure. Due to the excellent performance, the sensor can be applied in measuring micro-pressure lower than 500 Pa.