Effects Of Dimensional Parameters Research Articles

Microleverage Mechanism Assisted Novel Biaxial Piezoresistive Micro Accelerometer With Improved Sensitivity

A novel structure was presented for a microelectromechanical system (MEMS) piezoresistive accelerometer. Taking advantage of the effects of tiny piezoresistive beam (TPB) to generate stress concentration region and microleverage mechanism to amplify the force, a piezoresistive accelerometer was proposed with improved sensitivity. The measured sensitivity was determined by the amplified inertia force applied to the TPBs. Based on the model analyses, the force amplification factor was influenced by the beams’ spring constants and the distance between support beam and TPB. The simulations were further carried out to verify the effects of amplifying force and find out the effects of dimensional parameters on amplification factor. The results suggested that the amplification factor was influenced by support and hinge beam widths dramatically, and also affected by the distance between support beam and TPB. Based on the simulation findings, three prototypes (denoted as XJTU_11, XJTU_12 and XJTU_32) were proposed with different support and hinge beam widths along with the distance between support beam and TPB to verify the amplification effect. Furthermore, the prototypes were successfully fabricated by MEMS technology with a size of 4.4 mm × 4.4 mm and packaged for experimental tests. The sensitivities were determined to be 1.03 mV/g/5V, 0.871 mV/g/5V and 0.736 mV/g/5V for XJTU_11, XJTU_12 and XJTU_32, respectively. The sensitivity of XJTU_11 increased by 18.4% and 40.1% compared with XJTU_12 and XJTU_32 respectively. The results indicated that the higher amplification factor was beneficial to the device to obtain the higher sensitivity. The figure of merit showed that proposed accelerometer obtained a more favorable comprehensive performance. This new design provided a good strategy and revealed the promising potential in improving the accelerometer’s sensitivity.

A Circular-Arc-Type Magnetic Coupler with Strong Misalignment Tolerance for AUV Wireless Charging System

The wireless charging system (WCS) is widely employed to solve the problem of underwater charging of autonomous underwater vehicles (AUVs). However, the AUV is prone to misalignment caused by the tidal currents, which directly leads to fluctuations in transmission efficiency and output power. For this reason, a circular-arc-type (CA-type) magnetic coupler with strong misalignment tolerance was proposed in this article. Compared with the ring-type magnetic coupler, the proposed magnetic coupler had better magnetic field convergence and lower weight. Further, the effect of dimensional parameters on the CA-type magnetic coupler performance was analyzed by ANSYS Maxwell, with which the parameters of the magnetic coupler were optimized, and its coupling coefficient could finally reach 0.671. To analyze the influence of misalignment on the CA-type magnetic coupler, EE-type and UI-type magnetic cores are compared. Within the same range of rotation misalignment [−10°, 10°] and axial misalignment [−30, 30 mm], the CA-type magnetic core has stronger misalignment adaptability, and it can achieve a stable output power of 575 W and DC-DC efficiency of 92.51% when rotational misalignment occurs. A WCS experimental prototype is built based on one of the magnetic couplers and its experimental results verify the correctness of the theoretical analysis and simulation results.

Coupled Flexural–Torsional Forced Vibration Analysis of a Piezoelectrically Actuated Double-Cantilever Structure

Abstract In this paper, the forced coupled flexural–torsional vibration of a piezoelectrically actuated double-cantilever structure is investigated. The double-cantilever structure is composed of two uniform and identical Euler–Bernoulli cantilever beams connected by a rigid tip connection at their free ends. There is also a piezoelectric layer attached on the top surface of each cantilever beam. The characteristic equation for the coupled flexural–torsional vibrations of the structure is derived and solved to determine the natural frequencies. The time response to the forced vibrations of the structure is studied using the Galerkin approximation method. The effects of dimensional parameters, including the length of the cantilever beams and the length of the tip connection, and the piezoelectric input voltage on the coupled flexural–torsional natural frequencies and amplitude of vibrations of the structure are investigated analytically and experimentally. The results show that the coupled flexural–torsional fundamental frequency of the piezoelectrically actuated double-cantilever structure decreases as either the length of the cantilever beams or the tip connection is increased. Moreover, the amplitude of the coupled flexural–torsional vibrations of the structure is proportional to the piezoelectric input voltage; however, the slope of the curves depends on dimensional parameters. For a given voltage, the effect of either of the aforementioned dimensional parameters on the amplitude of vibrations depends on the other dimensional parameter such that there is a turning point in all the curves, whose location depends on the configuration of the structure.

Effect of dimensional parameters on the seismic performance of circular CFST columns

Due to the expansion of cities and increase in population, the need for construction of high rise buildings becomes more essential in the society. As earthquakes are of the greatest damaging natural hazards to the buildings, the design and construction of structures which are capable of resisting the adverse effects of earthquakes become necessary. Concrete Filled Steel Tubes (CFSTs) are the steel tubular sections in-filled with concrete and with a composite action. CFSTs are becoming a popular solution for structures located in seismic areas, due to their high strength, excellent ductility and large energy absorption capacity. This study was mainly concentrated to find out the effect of dimensional parameters on the seismic performance of CFSTs. Width - thickness ratio (D/t) and slenderness ratio (L/D) were taken as two parameters and the study was carried out using circular CFST buildings. It was observed that, there will be a particular limit for D/t and L/D ratio upto which the thickness and diameter of the CFSTs can be decreased. At that point the building will show a better seismic performance.

Generalized model for conic-V-shaped flexure hinges.

This paper presents a new class of flexure hinges, namely, conic-V-shaped flexure hinges (CFHs), which can be used as a generalized model for flexure hinges with profiles such as parabolic-V-shape, elliptical-V-shape, and hyperbolic-V-shape. Compliance and precision equations for the CFHs were derived as a set of nonlinear equations using Castigliano's second theorem. The parameters of the nonlinear equations inputted to the compliance and precision matrices were based on the generalized equations used for conic curves in polar coordinates. Furthermore, the compliance equations were verified by means of finite element analysis and experiments. The errors in the finite element and experimental results were within 10% and 8% compared to the analytical results, respectively. Finally, the effects of dimensional parameters on the analytical model could be effectively analyzed by numerical simulations and comparisons.

Hydrogen Diffusion Transport in an All-Iron Flow Battery Rebalance System

All-iron flow batteries (IFBs) are being developed for low-cost large-scale energy storage applications. IFBs use abundantly available, non-toxic and low cost electrolyte materials[1]. The all-iron flow battery involves plating and stripping of metallic iron in the negative half-cell and utilizes the Fe II/III (ferrous/ferric) redox couple reaction at its positive electrode[2-3]. Hydrogen evolution occurs as the iron deposits at the negative electrode during the flow battery charging and even if the amount might be small, there will be an impact on the electrolyte balance over many cycles. Recently, Selverston et al.[3] demonstrated a concept of hydrogen rebalance in an all-iron flow battery through designing a capillary-action galvanic reactor (CGR) to consume hydrogen and reduce excess ferric ions in the positive electrolyte reservoir. This design can maintain the balance of protons and reduce undesired precipitation reactions. A tube connects the negative tank headspace where hydrogen collects to the positive tank headspace where the CGR reactor is placed. An understanding of design factors on hydrogen transport through the tube between headspaces is desired and mathematical modeling[4-7] is the approach we took to achieve this. In this poster, we report a mathematical model of hydrogen diffusion between the headspaces of the negative electrolyte tank and the positive electrolyte tank. The effects of dimensional parameters, including diameter of tank, height of tank, diameter of tube, length of tube and diffusion coefficient on hydrogen diffusion rates and partial pressure are investigated during both battery charge and battery standby cases. In Figure 1, we demonstrate that the mathematical model is reasonably validated by the previous published experimental data for a specific all-iron flow battery rebalance device. Acknowledgements This work is supported by the all-iron flow battery project (grant number: DE-AR0000352) funded by Department of Energy (DOE) of the United States.

Ti–Ni–Cu/polyimide composite-film actuator and simulation tool

Polyimide/Ti49Ni33Cu18 composite films were fabricated by the sputtering of an alloy target. The composite films could be used as a simple actuator by cutting an appropriately shaped piece out of an as-sputtered films with scissors and then connecting it to a battery. In order to investigate the design parameters for the composite-film actuators, Ti–Ni–Cu films with various thicknesses (0.8–13μm) were deposited on two kinds of polyimide films (Kapton EN and H) with various thicknesses (25–175μm). The force and stroke of the composite-film actuators were found to vary largely with changes in various parameters such as the thickness ratio of Ti–Ni–Cu and polyimide films and the coefficient of thermal expansion of the polyimide films. A simulation tool based on a simple deformation model for a shape memory alloy was developed, and the effects of dimensional parameters (thickness, length, and width) and material parameters (Young's modulus, elastic strain limit, and transformation strain) on the actuation properties (force and stroke) of the composite-film actuators were systematically investigated on the basis of the simulation results. The simulation results revealed that composite-film actuators allow for various combination of force and stroke. Optimized actuators exhibited a long actuation stroke, a high response speed of 3Hz, and a large force of 0.4N.

Design of a compact ultra‐wide‐band monopole antenna with band rejection characteristics

This study presents a design of two compact monopole antennas with band-notched characteristics for ultra-wide-band application. The compact antennas are etched on an FR4 substrate with the size of 14 × 16 × 1 mm3, consists of a tree-shaped radiation patch with modified ground structure, providing a wide usable fractional bandwidth of more than 170% (2.8–19.2 GHz). To reject certain-frequency bands, two completely different approaches are proposed. First a shorted T-shaped quarter-wavelength resonator is used to omit undesired frequency band of 5.1–5.9 GHz. In the second approach, two L-shaped slots are inserted in the patch to act as a filter structure for worldwide interoperability for microwave access (3.4–3.6 GHz) and wireless local area network (5–5.6 GHz) applications. The band-notched can be controlled by adjusting the length of the rectangle slots. The effects of dimensional parameters on the antenna performance have been investigated through a parametric study. Furthermore, current density distribution on the antenna is also computed to gain a better insight of its behaviour. The antennas are investigated numerically and experimentally for their impedance matching properties, frequency notched characteristics and radiation performances.

Single-Layered SIW Post-Loaded Electric Coupling-Enhanced Structure and Its Filter Applications

A broadband post-loaded electric coupling structure in single-layered substrate integrated waveguide with enhanced coupling is proposed and investigated. The proposed structure can achieve the maximum electric coupling coefficient of more than 0.11. The effects of dimensional parameters on the electric coupling are studied by simulation. The proposed structure is verified by designing two bandpass filters, namely, a wideband fourth-order quasi-elliptic filter and a narrowband fourth-order quasi-elliptic filter. The measured results show that the designs are capable of providing the 12% bandwidth for the wideband fourth-order quasi-elliptic filter and the 3% bandwidth for the narrowband fourth-order quasi-elliptic filter at 5.8-GHz WiMax bands.

Modal Analysis of a Rotating Thin Plate via Absolute Nodal Coordinate Formulation

Modal analysis of a rotating thin plate is made in this paper through the use of the thin plate elements described by the absolute nodal coordinate formulation (ANCF). The analytical expressions of elastic forces and their Jacobian matrices of the thin plate elements are derived and expressed in a computationally efficient way. The static analysis of a cantilever thin plate and the modal analysis of a square thin plate with completely free boundaries are made to validate the derived formulations. The modal analysis of a rotating cantilever thin plate based on the ANCF is studied. The effect of rotating angular velocity on the natural frequencies is investigated. The eigenvalue loci veering and crossing phenomena along with the corresponding modeshape variations are observed and carefully discussed. Finally, the effects of dimensional parameters on the dimensionless natural frequencies of the thin plate are studied.

Miniature microstrip-fed ultra-wideband printed monopole antenna with a partial ground plane structure

A new microstrip-fed planar monopole antenna is presented for ultra-wideband (UWB) communication systems. The antenna structure consists of a dome-topped, bowl-shaped patch with a truncated ground plane structure. The ground plane is predominately tapered and includes a notch below the feed-line in the vicinity of the patch. The effects of dimensional parameters on the performance of the antenna have been investigated through a parametric study. Current density distribution on the antenna was also computed to gain a better insight of its behaviour. The antenna performance is validated through measurement, including its radiation patterns. The measured impedance bandwidth of the proposed antenna for |S11| ≤ −10 dB is 10.35 GHz (2.65–13.0 GHz), constituting 132% impedance bandwidth. The fabricated antenna has a compact size of 18×20×1.6 mm3. Additional features that make the antenna a suitable candidate for UWB systems are its simple configuration, compactness and low fabrication cost.

Curved Root Canals: Effects of Dimensional Parameters on the Insertion Depth of Irrigation Needles

Objective: To investigate the effects of size and taper of the apical preparation, root canal curvature and cannula diameter on the insertion depth of irrigation cannulas into root canals. Study Design: One hundred and four root canals were divided into four curvature groups (0-5°; 6°-15°; 16°-25°; >25°). After apical enlargement to size 25.06 a 25G and a 30G irrigation cannula were inserted until binding. The distance between the cannula tip and the working length was related to the root canal length. The insertion procedure was repeated after enlargement to 40.04. Results: In curved canals (>6°), the cannula never reached WL. With an apical preparation of 40.04 the 30G cannula could be introduced nearly to WL even in moderately curved canals (<26°). Conclusion: Only a 30G cannula allows delivery of the irrigant to the apex of a curved root canal. The cannula could be inserted closer to WL when the apical preparation size was wider with a smaller taper compared to a small apical preparation size with a wider taper.

Effects of dimensional parameters and various boundary conditions on axisymmetric vibrations of multi-walled carbon nanotubes using a continuum model

Axisymmetric vibrations of multi-walled carbon nanotubes (MWCNTs) with finite length are investigated in this paper. A multi-walled carbon nanotube is modeled with multiple elastic isotropic shells. Based on a continuum model and considering van der Waals forces between tubes, a two-dimensional finite element model is developed to obtain axisymmetric natural frequencies and mode shapes of MWCNTs. First, the axisymmetric vibrational characteristics of single-walled carbon nanotubes are investigated, and then, they are compared with those of MWCNTs. The effects of van der Waals forces on radial vibration of MWCNTs are also explained. Moreover, influences of end conditions on radial and axial natural frequencies of carbon nanotubes (CNTs) with wide range of length-to-thickness ratio are studied by considering the free-free (F-F) and simply supported (S-S) end conditions. Besides, it is focused on dependence of axisymmetric mode frequencies on dimensional parameters such as length, diameter, as well as number of layers of MWCNTs. Through this, explicit expressions are found for calculating the radial breathing mode and longitudinal mode frequencies of MWCNTs.

Compact printed antenna with novel radiating element for UWB applications

This paper presents a very compact printed antenna with simple and novel radiator for Ultra-Wideband applications. The proposed antenna is fed by a coplanar waveguide feed line to achieve wide bandwidth performance. The impedance bandwidth of the antenna is from 2.88 to 12.82GHz for which S11 < -10dB, which constitutes about 127%. The total size of the fabricated antenna is 18 × 27 × 0.787mm3. The radiation patterns of the antenna are measured and presented. Also the effects of dimensional parameters on the performance of the antenna are investigated through a parametric study. The agreement obtained between the measured and simulated results is excellent.

Variation risk analysis: MEMS fabrication tolerance for a micro CMM probe

This paper describes a methodology of variation risk analysis for microsystems using analytical modelling and simulation, a key characteristic (KC) method and statistical analysis considering MEMS fabrication tolerances. This methodology is applied to an innovative design for a micro co-ordinate measuring machine (CMM) probe utilising piezoelectric actuation and sensing currently being developed at the National Physical Laboratory. Analytical modelling is used to investigate the individual effects of dimensional parameters on the sensors’ open-circuit voltage output, which is a KC of the micro CMM probe. A computer simulation is performed using the finite-element method and compared with the analytical model. The KC variation is predicted and the variation contribution of the probe manufacturing processes is presented. This KC is mainly influenced by the thickness of the piezoelectric layer associated with the composite sol gel deposition process. Variation risk analysis results can be used to implement a variation risk mitigation strategy.

Vibrational characteristics of single-walled carbon-nanotube: Time and frequency domain analysis

In this paper, the vibrational characteristics of higher modes of single-walled carbon-nanotube (SWNT) modeled as the continuum axisymmetric cylinder are studied in both time and frequency domains. The modeling of SWNT for the high frequency dynamic analysis is done using the wavelet based spectral element method and this numerical technique involves the Daubechies scaling function approximation in time and one spatial (axial) dimension. This model is capable of capturing the coupled longitudinal-radial vibration arising due to the finiteness of SWNT. Here, first the phonon dispersion relation is obtained and validated with the atomistic and other continuum model simulations available. The effects of dimensional parameters on higher radial, longitudinal, and coupled radial-longitudinal vibrational modes are studied. Dependence of the higher mode frequencies on these parameters are much different from that of the first mode frequencies. Further time domain responses for broadband excitations are simulated and effects of the radius and thickness of the SWNT are studied. The prominent influence of the above geometrical parameters are observed in the time domain results.

Computational analysis on cymbal transducer

Finite Element Analysis in collaboration with experimental studies was conducted to investigate the effects of dimensional parameters on the performance of the cymbal transducer. ANSYS 5.5 FEM code was used for computational analysis. Cymbal transducers were fabricated with steel and brass endcap materials and piezoelectric ceramic, PZT-5A, as driving elements. Admittance spectrum was measured by using HP4194A Impedance/Gain phase analyzer. Displacement and generative force characteristics of the transducers were tested by using a LVDT sensor. Experimental and calculated results matched quite well. Device diameter and cavity diameter has strong effect on cymbal transducer characteristic. Adjusting the dimensional parameters can extend potential application areas of cymbal transducer.