- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Effects of TiO2 on the performance of silver coated on side-polished optical fiber for alcohol sensing applications
摘要： This work reports the experimental and numerical investigations on the effect of titanium oxide (TiO2) integrated on the optical fiber silver (Ag) surface plasmon resonance (SPR) sensors. In this paper, the numerical simulation is also analyzed using the finite element method (FEM) which shows good agreement. Results are compared with the experimental findings, focusing on the SPR phenomena for refractive index sensing using side-polished optical fiber, where the characteristics of the Ag layer with the integration of TiO2 are optimized. The essential parameters include the thickness of Ag namely 20 nm, 30 nm and 40 nm for optimization studies of SPR properties. TiO2 was then coated on the Ag thin layer to sense isopropanol at different concentration. It is shown that the combination of a 30 nm thickness of Ag layer with a dielectric TiO2 improves sensor performance in terms of sensitivity reading of 268 nm/RIU with a detection limit of 0.012. The main interest is to develop the device with cost effective, ease fabrication and less cumbersome of sensors using TiO2 which one of an alternative material to defeat the oxidation process and avoid charge recombination. If the sensitivity increases at a higher wavelength, it indicates that the TiO2 holds great potential in photonic applications.
关键词： Fiber Optic Alcohol Sensor,Surface plasmon resonance (SPR),Finite element method (FEM)
更新于2025-11-28 14:23:57
-
Tailored nanocomposite energy harvesters with high piezoelectric voltage coefficient through controlled nanowire dispersion
摘要： Composites composed of piezoelectric nanomaterials dispersed in a flexible polymer have emerged as promising materials for highly durable and flexible energy harvesters and sensors. Although piezoelectric materials in their bulk form have a high electromechanical coupling coefficient and can efficiently convert mechanical energy to electrical energy, the ceramic form has low fracture toughness and thus they are limited in certain applications due to difficulty in machining and conforming to curved surfaces. Recently, additive manufacturing processes such as direct write, have been developed to incorporate piezoelectric nanowires into a polymer matrix with controlled alignment to realize printed piezoelectrics. Given the multiphase structure of a nanocomposite, it is possible to control the material structure such that the piezoelectric coupling and dielectric properties can be varied independently. In this paper, experimentally validated finite element (FE) and micromechanics models are developed for calculation and optimization of the piezoelectric voltage coefficient, g31, of a nanocomposite. It is shown that by using high aspect ratio nanowires with controlled alignment, the piezoelectric coupling can be disproportionately increased with respect to the dielectric constant which yields a g31 coefficient that can be enhanced more than seven times compared to the bulk piezoelectric material. Moreover, it is demonstrated that the use of high aspect ratio nanowires in the energy harvester resulted in significant improvement on the output electrical power of an energy harvester.
关键词： Energy harvesting,Nanowires,Finite element modeling (FEM),Voltage coefficient,Piezoelectric,The Mori-Tanaka method,Direct write,Nanocomposite
更新于2025-11-14 17:28:48
-
High spatial resolution identification of hematoma in inhomogeneous head phantom using broadband fNIR system
摘要： This paper presents a novel method for early detection of hematomas using highly sensitive optical fNIR imaging methods based on broadband photon migration. The NIR experimental measurements of inhomogeneous multi-layer phantoms representing human head are compared to 3D numerical modeling over broadband frequencies of 30–1000 MHz. A finite element method (FEM) simulation of the head phantom are compared to measurements of insertion loss and phase using custom-designed broadband free space optical transmitter (Tx) and receiver (Rx) modules that are developed for photon migration at wavelengths of 670 nm, 795 nm, 850 nm, though results of 670 nm are discussed here. Standard error is used to compute error between 3D FEM modeling and experimental measurements by fitting experimental data to the a√frequency + b . Error results are shown at narrowband and broadband frequency modulation in order to have confidence in 3D numerical modeling. A novel method is established here to identify presence of hematoma based on first and second derivatives of changes in insertion loss and phase (?IL and ?IP), where frequency modulated photons sensitive to different sizes of hematoma is identified for wavelength of 670 nm. The high accuracy of this comparison provides confidence in optical bio-imaging and its eventual application to TBI detection.
关键词： Optical receiver Rx,IL,TBI,Optical transmitter Tx,FEM,fNIR,DE,COMSOL,IP,PDW,Tri-wavelength VCSEL
更新于2025-09-23 15:23:52
-
High quality factor cold sintered Li2MoO4BaFe12O19 composites for microwave applications
摘要： Ceramics-ceramic composites (1-x)Li2MoO4-xBaFe12O19 (LMO-BF12, 0.00≤x≤0.15) have been cold sintered at 120oC and their structure and properties characterized. X-ray diffraction, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) confirmed that compositions were dual phase and had a dense microstructure. Composites in the xBF12-(1-x)LMO (0.0≤x≤0.15) series resonated at MW frequencies (~6GHz) with 5.6≤e r≤5.8 and Qf =16,000-22,000 GHz, despite the black colour of compositions with x > 0. The permeability of the composites was measured in the X band (~8 GHz) and showed an increase from 0.94 (x=0.05) to 1.02 (x=0.15). Finite element modelling revealed that the volume fraction of BF12 dictates the conductivity of the material, with a percolation threshold at 10 vol.% BF12 but changes in e r as a function of x were readily explained using a series mixing model. In summary, these composites are considered suitable for the fabrication of dual mode or enhanced bandwidth microstrip patch antennas.
关键词： Finite element modeling (FEM),Composite,Cold sintering process,Dielectric,Ceramic material
更新于2025-09-23 15:23:52
-
FEM and CIP-FEM for Helmholtz Equation with High Wave Number and Perfectly Matched Layer Truncation
摘要： The Helmholtz scattering problem with high wave number is truncated by the perfectly matched layer (PML) technique and then discretized by the linear continuous interior penalty–finite element method (CIP-FEM). It is proved that the truncated PML problem satisfies the inf-sup condition with inf-sup constant of order O(k?1). Stability and convergence of the truncated PML problem are discussed. In particular, the convergence rate is twice the previous result. The preasymptotic error estimates in the energy norm of the linear CIP-FEM as well as FEM are proved to be C1kh + C2k3h2 under the mesh condition that k3h2 is sufficiently small. Numerical tests are provided to illustrate the preasymptotic error estimates and show that the penalty parameter in the CIP-FEM may be tuned to reduce greatly the pollution error.
关键词： perfectly matched layer,FEM,CIP-FEM,Helmholtz equation with high wave number,wave-number-explicit estimates
更新于2025-09-23 15:22:29
-
The Oscillation Dynamics of Droplets Subject to Electrowetting Actuation
摘要： The dynamic behavior of an Electrowetting-on-Dielectrics (EWOD) actuation process can be linked to certain fluid properties of the actuated polar liquid droplet. After actuation, inertia will lead to droplet oscillations where the contact angle asymptotically approaches the newly created surface tension equilibrium value. The decay behavior, frequency and amplitude of these oscillations can be related to material parameters such as density, viscosity and mass. In this work we study the characteristics of these oscillations, present simulation results and develop a measurement setup for first observations of oscillations on deionized water droplets. We show that there is a big difference between two grounding schemes, in particular regarding the dynamic movement of the liquid-gas interface. It turns out that only an electrical grounding from below leads to utilizable oscillations. Finally we point towards applications for future Lab-on-a-Chip applications.
关键词： actuator,FEM simulation,electrowetting,viscosity sensing,droplet oscillations,Lab-on-a-Chip
更新于2025-09-23 15:22:29
-
[IEEE 2018 IEEE International Ultrasonics Symposium (IUS) - Kobe, Japan (2018.10.22-2018.10.25)] 2018 IEEE International Ultrasonics Symposium (IUS) - A Hybrid 3D Thermal / 1D Piezoelectric Finite Element Model for Rapid Simulation of FBAR Filter Response Under High Power
摘要： The increasingly stringent power requirements imposed on BAW filter technologies has made coupling between thermal and piezoelectric physics relevant to the design process. Existing lumped filter models do not account for the effect of a 3D temperature distribution over each resonator. Here we report a new finite element based method for rapid simulation of filter response under high power that captures the effect of heat flow within the filter die as well as its path through the PCB to thermal ground.
关键词： thermo-piezoelectric,BAW,self-heating,nonlinear,FBAR,FEM,fully coupled
更新于2025-09-23 15:22:29
-
[IEEE 2018 IEEE International Ultrasonics Symposium (IUS) - Kobe, Japan (2018.10.22-2018.10.25)] 2018 IEEE International Ultrasonics Symposium (IUS) - Hierarchical Cascading in FEM Simulations of SAW Devices
摘要： Application of the finite element method (FEM) for the simulation of SAW devices has traditionally been constrained by the large number of degrees-of-freedom required, resulting in large memory usage and long computation times, and limiting the accuracy of the simulation. In this paper we review the recently introduced hierarchical cascading method, which offers drastically reduced memory consumption and simulation times in 2D simulations. In 3D, the advantages of hierarchical cascading are diminished due to the high number of cross-sectional degrees-of-freedom. As a partial solution to this problem, an iterative hierarchical cascading method is proposed, with reduced number of effective degrees-of-freedom. Examples of simulations of finite devices in 2D and of a periodic array in 3D are provided.
关键词： FEM,SAW simulation,SAW
更新于2025-09-23 15:22:29
-
The Impact of Peltier Effect on the Temperature Field During Spark Plasma Sintering of Thermoelectric Materials
摘要： We report about the modelling of spark plasma sintering of a line of thermoelectric materials. A significant difference of sintering temperature DTs from 15 K to 110 K was found in the samples studied. The Peltier effect on the graphite-thermoelectric interfaces results in such temperature difference. The rise of sintering temperature leads to the DTs increase. DTs in the vertical direction is 2–3 times higher than in the radial one. Electric insulation modelled in the horizontal graphite–thermoelectric interfaces reduced DTs in all the types of numerically studied samples by 59–92%.
关键词： spark plasma sintering,FEM,SPS,Thermoelectrics,finite elements simulation
更新于2025-09-23 15:22:29
-
A Domain Decomposition Finite Element Method for Modeling Electromagnetic Scattering from Rough Sea Surfaces with Emphasis on Near-Forward Scattering
摘要： A high fidelity full-wave simulator is presented to perform numerical experiments for rough sea scattering problem by considering different polarizations, frequencies, grazing angles, wind speeds and sea surface spectra. The simulator is based on a novel Finite Element Domain Decomposition (FEDD) method for solving the problem of two dimensional electromagnetic scattering over one-dimensional sea surface. This non-iterative method partitions the computational domain into a number of overlapping subdomains and solves each domain individually by employing the Locally-Conformal Perfectly Matched Layer (LC-PML) at the truncation boundaries. LC-PML has a unique feature such that it can be applied to irregular domains on the contrary to standard PML methods, and hence inspired the birth of FEDD. The FEDD method is used at each Monte Carlo realization corresponding to a sample from random rough surfaces, and decreases the computational load especially for electrically-large problems. The accuracy and computational efficiency of the method is investigated through several simulations. Using the FEDD method, the statistical behavior of the bistatic Radar Cross Section (RCS) is obtained for both horizontal and vertical polarizations. A special emphasis is given to forward-scattered RCS and the mean reflection coefficient for sea surface especially at low grazing angles, and it is shown that the simulator produces results in agreement with the Ament and Miller-Brown approximations, and experimental data, proving the reliability of the simulation approach. The results are also compared with the standard finite element method and method of moments. Rough sea surfaces are created by using both Pierson-Moskowitz and Elfouhaily spectra.
关键词： Locally-Conformal Perfectly Matched Layer (PML),forward scattering,sea surface,Domain decomposition,Monte Carlo,rough surface scattering,Finite Element Method (FEM),propagation,reflection coefficient,bistatic Radar Cross Section (RCS),multipath
更新于2025-09-23 15:21:21