Maximum Impedance Research Articles

Effect of GO‐TiO2 to waterborne epoxy resin on microstructure and anti‐corrosion properties

AbstractTo enhance the anti‐corrosion of the waterborne epoxy resin coating, we filled GO‐TiO2 into the coating with ultrasound and stirring method. Results show that coatings rendered optimum properties at GO‐TiO2 content of 0.4 wt% with a hardness of 3H and rate of thermal weight loss reduce 8.3 wt%. After immersion for 30 days, coating exhibited water absorption ratio of merely 11.25% and open circuit potential of −0.871 V. After 1000 h of scratch‐neutral salt spray test, no obvious signs of corrosion were observed on surface. Moreover, Electrochemical results demonstrated that maximum impedance modulus of 0.4GO‐TiO2 coating was 2.18 × 106 Ω cm2, corresponding to superior corrosion resistance. What is more, anticorrosion mechanism was discussed. In conclusion, Filling GO‐TiO2 improved mechanical properties, thermal stability and corrosion resistance of waterborne epoxy resin coatings.

Effect of chromic acid anodization on the corrosion resistance of Fe-based alloy coatings by high-speed laser cladding

Fe-based alloy coatings were coated on surface of ductile cast iron by high-speed laser cladding, and the effects of chromic acid anodization on corrosion resistance of coatings were analyzed. The results show that as chromic acid anodization time increases, corrosion rate falls and then rises. After 20 min, the coating had Cr and Fe oxide passivation film, maximum impedance value (5.40 × 105 Ω·cm2) and polarization resistance (50.6 kΩ·cm2), and minimum self-corrosion current (0.77 μA/cm2). Its corrosion resistance had improved significantly.

Carbon dot complimentary green corrosion inhibitor for crystallographically textured Beta C titanium alloy for marine application: A state of art

The corrosion properties of Beta C titanium alloy were shown to differ remarkably, by more than one order of magnitude, with the crystallographic texture. More specifically, the maximum volume fraction of γ-fiber (ND//< 111 >) and large-sized grains were preferentially engineered by heat treatment to provide a corrosion-resistant surface. It was proposed that the ND//< 111 > grains, with lower dislocation content, are key in preferentially limiting corrosion. For 90% rolled plus annealed beta titanium alloy, the lowest corrosion current density, and maximum impedance were attained in nitrogen-based carbon dots containing NaCl electrolyte. Analysis using ultraviolet spectroscopy, and X-ray diffraction showed that the heteroatoms in the structural moiety of the carbon dots effectively bond to the titanium surface by physiochemical interaction.

Evaluating interfacial bonding quality of multilayered structure based on ultrasonic testing technology

An ultrasonic evaluation method of interfacial bonding quality from layered structures is proposed for enhancing the testing accuracy. The ultrasonic reflection and transmission characteristic is theoretically analyzed, which focus on the different quality of the single and double bonding interface with spring-type. The reflection coefficient and transmission coefficient mathematic models, which include multiple parameters, are derived from the transfer matrix. Taking the first, second, and the double bonding interface as the research objects, respectively, two types of resonant frequencies have been presented by numerical solving the model, namely, the first type resonance frequency (RFI) and the second type resonance frequency (RFII). The results show that the interval of the RFⅠ is related to medium thickness of the maximum acoustic impedance. Similarly, the interval of the RFⅡ depends on other layers’ thickness. In addition, the transmission coefficient shows a change in different trends with the bonding interface gradually tending to rigid. When the adhesive layer thickness is sufficiently small compared with the wavelength, the reflection coefficient shows many local minima points at a certain frequencies range, the frequency of local minimum point increases with the increase of the stiffness coefficient. The experimental results are in good agreement with the numerical solution results and finite element analysis results.

Fast response humidity sensor based on chitosan/graphene oxide/tin dioxide composite

In this paper, Chitosan(CS)/graphene oxide(GO)/SnO2 composite is proposed as the sensing material of an impedance-type humidity sensor. The composite was synthesized via a facile solution mixing method. And it was formed by adding CS and SnO2 to GO aqueous solution. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectrometer (FT-IR) were executed to characterize the structure and morphology of the composite. At room temperature, the CS/GO/SnO2 composite shows more favorable humidity-sensing properties compared with the CS, CS/GO, and CS/SnO2 material. The resulted sensor exhibits high response (72683%), high sensitivity (402.5 kΩ/%RH), rapid response and recovery time (8 s/8 s). Moreover, small humidity hysteresis value (<7%) under maximum impedance difference, good repeatability and long-term stability are demonstrated. Therefore, the CS/GO/SnO2 composite is a promising candidate for humidity sensing.

Novel mapping tool to identify drivers in persistent atrial fibrillation: first clinical experience

Abstract Funding Acknowledgements Type of funding sources: None. Background Developing ablation strategies beyond pulmonary vein isolation (PVI) in persistent atrial fibrillation (persAF) is still a challenge. To date, few diagnostic tools have allowed identification of potential drivers during AF, with questionable results. There is a need for a tool that allows to consistently display and detect EGMs and identify optimal ablations targets. A novel mapping tool can provide algorithmic detection of ablation targets based on EGM properties specific to relatively stable localized rotational activations. Objective Describing an initial series of patients (pts) where Ockham mapping was used during AF to identify ablation targets and treat PersAF. Methods PersAF pts presenting in AF for were mapped using an ultra-high density mapping system (RHYTHMIA). A novel PersAF mapping feature (Ockham) was used to detect ablation targets by calculating local cycle length (LCL) and local spread of activation time within that LCL (Duty Cycle) for consistent EGMs. A scatterplot tool (F1 A) was used to identify regions of consistent (relatively stable) local activation. Among these areas, those with fast CL and high DC (&amp;gt;90%) were used to guide the optimal PVI line placement. Additionally, during remapping the same approach was used to target ablation beyond PVI.RF was delivered at 40-45 W via a StablePointTM IntallaNav OI catheter aiming at the maximum impedance drop (30 ohms).Durable PVI was verified by EGM visualization. In case of ongoing AF at the end of the procedure patients were monitored for 48 h before eventual cardioversion. Follow-up was by Holter every 3 months (more if symptoms). Data are median [IQR]. Results The novel mapping tool was used on 31 PersAF pts (68±9.5 years, 71% male, 20 De Novo).A median of 41228 [32789-46512] EGMs was collected before PVI. After PVI, 3 de novo pts had AF terminate into AT. Additional targets were identified in the other ones from a second post-PVI map. 81% of the extra-venous potential drivers identified on the post-PVI maps were already present on the pre-PVI map, supporting the reproducibility of the tool. Pts had a median of 3 [1-4.25] extra-PV drivers targets. Across all pts, following PVI and targeted ablation, there was progressive AF organization demonstrated by global activation slowing (a rightward shift of CL; F1 B), which in approximately half of the patients formed bi-modal curves clustered around 2 discrete CL values. Acutely, 88% of patients had AF terminate to SR or AT. At 10 months [5.75-13] follow-up, 3 (15%) patients had recurrence of persAF, and 2 (10%) patients had AT recurrences. No complication occurred. Discussion This clinical experience demonstrates that this tool can identify limited, but highly selective, reproducible extra-PV AF drivers. Since PersAF pts have high variability in arrhythmogenic sites, this novel tool allows efficient identification of ablation targets based on EGM properties for an individualized approach to ablation beyond PVI.

Enhanced anticorrosion properties of composite coatings containing polyvinyl butyral and polyaniline-carbonized polyaniline

A kind of polyaniline-derived carbon material, polyaniline‑carbonized polyaniline composite (PANI-CPANI), was realistically applied to the polyvinyl butyral (PVB) resin matrix. The corrosion resistance of PVB/PANI-CPANI composite coating on 304 stainless steel has been investigated. The composites were characterized by Fourier transform infrared spectroscopy and X-ray diffraction. The surface morphology of the coating exhibited that the composite was uniformly dispersed. The tribological test proved the excellent mechanical properties of the coating. The adhesion of the coating reached grade 5B. Based on electrochemical test results, PVB/PANI-CPANI coating possessed the maximum low-frequency impedance and minimum corrosion rate under different corrosive environments. The long-term corrosion protection to the substrate could last for over 240 days in 3.5 wt% NaCl solution. This work could be a new application of polyaniline derivatives in the anticorrosive coating field.

Three‐dimensional‐printed strip and paint‐based semiellipsoidal helical antenna

AbstractA semiellipsoidal helical antenna (SEHA) is formed by scaling a hemispherical antenna in the axial direction. Effects of scaling factors on reflection coefficient (S11), axial ratio bandwidth (AR BW), and gains were analyzed thoroughly. By considering the best scaling factor, analysis is continued for strip‐based SEHA. It is observed that keeping the strip face parallel to the ground plane eliminates the concern of extra impedance matching issues and improves the overall performance over its wire‐based counterpart. For prototyping, the antenna is constructed independently on polylactic acid and acrylonitrile butadiene styrene plastic‐based supportive structures. Simulated and measured results are well agreed upon. When the height (h) in the axial direction is twice the hemispherical radius (r), the antenna provided maximum impedance and 3‐dB AR bandwidths of 144% and 77.53%, respectively, with a maximum gain of 8.83 dBi. The proposed antenna would be a good contestant in satellite communication where a broadband circularly polarized antenna is required.

Numerical Investigation on the Temperature dependent Impedance Characteristics of Far-Infrared Quantum Cascade Lasers

Quantum Cascade Lasers (QCLs) as Terahertz (THz) frequency sources offer a potentially viable solution for new applications in mid and far-infrared frequency bands. This research work exhaustively investigates the temperature dependence on the impedance of temperature dependent Quantum Cascade Lasers (QCLs) operating at 116μm, for the first time. In the 90-stage QCL considered for the work, the cold finger temperature is varied from 15K to 45K. When the device is biased at 0.6A current along with a cold finger temperature of 45K, the magnitude of intrinsic impedance was found to be 23.91mΩ, at a frequency of 4GHz. As the cold finger temperature is increased from 15K to 45K, the impedance response of the device becomes flat and stays constant. At 45K with an injected current of 1.5A, maximum impedance of 3.1mΩ is obtained. The resonant frequency characteristics of the device increase with increase in injected current and cold finger temperature. Also, it is observed that the magnitude of intrinsic impedance decreases with increase in injected current. The impact of cold finger temperature on the intrinsic impedance characteristics are detailed for prospective Radio over Fiber (RoF) applications.

Multifunctional Induction Coil Sensor for Evaluation of Carbon Content in Carbon Steel

Carbon steel has proven to be an important structural and functional material that plays an irreplaceable role in the worldwide economy. The influence of carbon on the mechanical and magnetic properties of the steel is well understood. Thus, the precise knowledge of the amount of carbon content in steel is crucial. Magnetic Barkhausen noise (MBN), magnetic hysteresis loop (MHL), and impedance measurements are reliable tools to assess carbon content. In this work, a multifunctional induction coil sensor used for MBN, MHL, and impedance measurements is designed and optimized. A multifunctional measurement system using the optimized induction coil is employed to measure MBN, MHL, and impedance signals. The parabolic dependence of the maximum value of MBN envelope on carbon content in steel is theoretically analyzed and experimentally verified. Coercive field and remanence from MHL measurements as well as the maximum impedance value are found to be proportional to carbon content and their dependence is explained with analytical simulations.

Design, characterization and preliminary usability testing of a portable robot for unsupervised therapy of hand function

Introduction:There is evidence that increasing therapy dose after stroke might promote recovery. Unfortunately, in clinical practice, therapy dose is limited by financial and organizational constraints. Simple robotic devices could be used without supervision in the clinic or at home to increase dose without requiring additional resources. For this purpose, we developed HandyBot, a portable three-degrees-of-freedom end-effector haptic device to perform sensorimotor task-oriented therapy of hand function (i.e., grasping, forearm pronosupination, wrist flexion-extension) in different environments.Methods:We present the mechatronic design of the device and its technical evaluation in terms of workspace, dynamics (i.e., max end-effector velocity, acceleration and force), sensing (i.e., position, velocity and force resolution) and haptic performance (i.e., transparency, maximum stable impedance range, rigid contact rendering accuracy). In addition, its feasibility and usability (in terms of System Usability Scale (SUS)) were assessed in a single-session experiment with four subjects with chronic stroke that tested the HandyBot therapy platform (i.e., haptic device with a graphical/physical user interface and a set of therapy exercises) while simulating unsupervised use (i.e., the subject used the device independently while a therapist was only observing the session).Results:HandyBot showed hardware and control performances comparable to other less portable therapy devices for hand function (e.g., 94% accuracy in stiffness rendering, low apparent mass of 0.2 kg in transparency mode), making it a suitable platform for the implementation of sensorimotor therapy exercises. HandyBot showed good platform usability in terms of SUS (i.e., above 75 out of 100 for device and graphical user interfaces, above 65 out of 100 for the exercises) when tested in simulated unsupervised settings. These tests underlined minor design improvements that should be considered to allow using such a device in uncontrolled settings.Discussion:HandyBot is a novel robot for hand rehabilitation after stroke that revealed high-quality hardware and haptic performance. HandyBot was usable for stroke patients at first exposure for (simulated) unsupervised robot-assisted sensorimotor therapy of hand function. This therapy approach combined with this novel portable robotic device has the potential to help increase therapy dose and decrease therapy-associated costs (e.g., therapist time to therapy time ratio) in different environments.

Adaptive fuzzy-based stability control and series impedance correction for the grid-tied inverter

The regenerative braking in the tram allows the energy to be returned to the power grid through a power inverter. Since the inverter location between the tram and the power grid is not fixed, resulting in a wide variety of impedance networks at grid coupling points, posing a severe threat to the stable operation of the grid-tied inverter (GTI). By independently changing the loop characteristics of the GTI, the adaptive fuzzy PI controller (AFPIC) can adjust according to different impedance network parameters. It is challenging to fulfill the stability margin requirements of GTI under high network impedance since the PI controller has phase lag characteristics. A correction method of series virtual impedance is proposed, which connects the inductive link in a series configuration with the inverter output impedance, correcting the inverter equivalent output impedance from resistance-capacitance to resistance-inductance and improving the system stability margin. Feedforward control is adopted to improve the system's gain in the low-frequency band. Finally, the specific series impedance parameters are obtained by determining the maximum network impedance and setting the minimum phase margin of 45°. The realization of virtual impedance is simulated by conversion to an equivalent control block diagram, and the effectiveness and feasibility of the proposed method are verified by simulation and a 1 kW experimental prototype.

Using GIS to Determine Tsunami Shelter Location in South Coast Pangandaran District, Pangandaran Regency, Indonesia

The geographical condition of the Pangandaran Regency affects the coastal area, periodically suffering hydrological hazards. Based on the Regional Disaster Management Agency of Pangandaran, Pangandaran Regency experienced Tsunami with a run-up height of 8 to 15.7 meters in 2006. The Tsunami caused 664 people to die, many to be injured, and caused social environment disruption. Therefore, this research aims to support disaster mitigation by identifying additional shelter locations and generating evacuation routes sequentially. This research uses the network analyst method of Geographic Information System (GIS). The identification of evacuation shelters utilizes several parameters, e.g., tsunami hazard catchment area, land slope levels, land cover, and street network. In addition, the spatial analysis considers average travel time as the impedance to resemble the actual evacuation process. The result indicates that 11 evacuation shelters scattered over the study area were dominantly located in Pangandaran Village. Moreover, this research generates 24 evacuation routes from the incident location to each shelter. The closest shelters accessed 8 minutes from incidents 4 and 18 are shelters 3 and 9, respectively. On the contrary, the farthest shelter is shelter 9, with a maximum impedance of 22 minutes from incidents 14 and 15. Furthermore, the most appropriate shelters are shelters 2 and 8, considering the elevation height of 10 and 7 in the open space.

Polydopamine coated Co2(OH)2BDC nanosheets for anticorrosive reinforcement of water-borne epoxy coating

In this study, Co2(OH)2BDC, a 2D metal-organic-framework (MOF) nanosheet (Co-MOF, BDC = 1,4-benzenedicarboxylate), was modified by using hydrophilic dopamine (DA) to construct a new anti-corrosion coating with excellent interface compatibility. Two-dimensional (2D) nanomaterials have attracted considerable attention because of their excellent barrier properties. However, enhancing the interfacial compatibility of epoxy coatings filled with 2D nanomaterials remains a challenge. DA contains several amine and catechol groups, which can effectively improve the interfacial compatibility between epoxy resin and 2D nanomaterials. Furthermore, Co-MOF/WEC (WEC = waterborne epoxy coating) and Co-MOF-PDA/WEC (PDA = polydopamine) were applied to steel substrates to systematically evaluate their anti-corrosion performance. The results indicated that the incorporation of well-dispersed Co-MOF-PDA nanosheets improved the anti-corrosion performance of the pure epoxy resin coating. The maximum impedance radius was exhibited by the 0.5 wt% Co-MOF-PDA/WEC coating, whose impedance after 60 days decreased to 3.945 × 107 Ω cm2, three orders of magnitude higher than that of epoxy resin. Experimental results showed the successful synthesis of Co-MOF-PDA nanoparticles, and adding an appropriate amount of nanomaterials effectively increased the initial resistance value and slowed the corrosion rate. This method will promote the practical application of MOF materials in the field of anti-corrosion coatings.

Electromechanical coupling model of variable-section piezoelectric composite beams in longitudinal vibration

The traditional step-reduction method is popular for modeling mechanical vibration of variable-section homogeneous beams (VHBs). However, this method cannot transfer electrical information and cannot depict electromechanical coupling behaviors of variable-section piezoelectric composite beams (VPCBs) in longitudinal vibration. To solve this defect, considering the structural continuity and parallel circuit factors, we propose the electromechanical step-reduction method for VPCBs. Longitudinal vibration transfer equations, linking input and output state vectors, are first created for VPCBs according to the proposed method. Then, a piezoelectric actuator excited by a VPCB is designed as a case study. Its transfer matrix model, involving mechanical and electrical properties, is developed to prove the correctness of the proposed method and the created transfer equations. Besides, an actuator prototype was manufactured for experimental verifications. The calculation results show that the longitudinal vibration frequency and velocity tend to be stable with the increase of the division number n. Their velocity vibration shapes are also consistent with each other. The calculated and experimental impedance curves have the same trend. The minimum and maximum impedance differences between the calculated and experimental are 107 ohm and 127 ohm, respectively. Finally, the modeling differences between the traditional and electromechanical step-reduction methods are compared and discussed in detail. The proposed method is more applicable to the modeling of VPCBs, which provides a theoretical tool for optimizing the excitation of the longitudinal vibration.

Preparation and properties of highly loaded SnO2-based porous electrodes by DLP 3D printing

In this study, highly loaded tin oxide-based (SnO2-based) porous electrodes were prepared by digital light processing (DLP) 3D printing technology. Firstly, the SnO2 light-cured slurry was prepared. The curing process and heat treatment process were analyzed and optimized. Then the best process parameters were obtained. Antimony oxide (Sb2O3) was selected as the conductive agent to improve the electrical conductivity of the SnO2-based electrode. Through the characterization of resistivity, SEM and XRD, the optimum doping amount of conductive agent Sb2O3 was determined to be 6 wt. %. Three kinds of porous electrodes with different shapes were prepared by DLP 3D printing, and the printing accuracy and mechanical properties were characterized. The results showed that the forming dimension error was about 1.7 % in the X and Y direction, 2.3 % in the Z direction. And the average compressive strength was 18.1 MPa, which effectively ensured the shape integrity and mechanical stability of the printed parts. Then the electrochemical properties of DLP 3D printed SnO2-based electrode and conventional coated electrode were tested and compared. The results showed that the 3D printed porous electrode showed lower charge transfer impedance and higher ion diffusion efficiency, and the maximum charge transfer impedance could be reduced to 1/25 of the traditional electrode; At the same time, it showed better cycle performance and rate performance, and the capacity retention of the 3D printed porous electrode could be improved by about 29.0 % compared with the traditional electrode. This work shows that high-performance high-load porous electrodes can be accurately prepared by DLP 3D printing, which provides a new strategy for the future development of high-load thick electrodes.

Analysis of Chicken Fat Quality Using Bioelectric Impedance Method

Animal fat tissue consists of liquid, and solid fats combined in fibrous tissues. Unpleasant odors characterize changes in fat quality, structure and color occur when fat is stored. This study aims to test the quality of chicken fat based on impedance measurements using the Multi I/O Card PCI 6221 National Instrument driven by LabVIEW software, where AC is injected into the fat sample using an electrode with a frequency variation of 10 Hz to 50 kHz at amplitude of 700 mV. The fat quality is influenced by storage time as well as the aging factor measured by varying the measurement time for 1 hours (fresh sample), 24 hours, and 48 hours, which resulted in a maximum impedance of 14.08k Ohms in fresh conditions and decreased 38.5% after 48 hours. Visually, the decrease in fat quality due to aging is indicated by changes in color, odor, and the appearance of water in the measuring vessel due to changes in the fat structure. Based on this, the impedance value can be used to determine the fat loss factor.

The Effect of Varying Current on the Impedance Phase Characteristics of CoFeSiB Amorphous Ribbon

The impedance magnitude characteristics of the giant magnetoimpedance (GMI) sensors have been extensively researched since the magnetoimpedance (MI) effect was discovered 20 years ago. However, unlike earlier impedance amplitude studies, the current study shows that the characteristic shift of the GMI impedance phase is more sensitive to the change in the magnetic field. CoFeSiB exhibits excellent GMI effect and soft magnetic characteristics. The impedance phase characteristics of an amorphous ribbon of CoFeSiB are examined in this work in relation to fluctuations in the excitation current. The impedance phase characteristics are significantly influenced by the magnitude and frequency of the ac excitation current as well as the degree to which the dc current overlapped the ac current. When the dc bias current is zero, the sensitivity in the weak field is roughly 0.79%/Oe. The sensitivity can reach up to 3.97%/Oe in the same field when the dc bias current is set to 20 mA. The GMI phase sensitivity change rate has seen a further increase of almost 402.5%. It indicates that the appropriate excitation current amplitude and frequency can excite the maximum impedance phase change.

Cold-sintered NaCa2Mg2V3O12–Li2MoO4 microwave dielectrics for the design and fabrication of high-bandwidth antennas

Preparation of (1 – x)NaCa2Mg2V3O12–xLi2MoO4 (NCMVO-LMO; x = 0.4, 0.5, 0.6, 0.7) composites via cold sintering technique under 200 °C using uniaxial pressure of 450 MPa for 50 min is reported in this article. Microstructures of these composites suggest their enhanced densification with increased LMO concentration. Relative permittivity (εr) of (1 – x) NCMVO–xLMO ceramics varies from 7 to 8, and the quality factor (Qu × f) changes from 7000 to 13,500 GHz. A cylindrical dielectric resonator antenna (CDRA) and a microstrip patch antenna (MPA) were outlined, fabricated, and tried using the 0.4NCMVO–0.6LMO composite. CDRA and MPA exhibit excellent performance with centre frequencies of 13.24 and 5.48 GHz, maximum return losses of –36 and –31 dB, and maximum impedance bandwidths of 0.77 and 1.4 GHz, respectively. These values suggest that the fabricated antennas hold the potential to be a key component in future microwave communication systems, especially for 5G and Ku-band applications.

Linear site responses from U.S. borehole arrays: Primary site-response parameters and proxies

Site response, site resonance in particular, is a great concern in earthquake engineering. However, scientists and engineers have yet to reach a consensus on the most important parameters or proxies to characterize or quantify site response. In this investigation, we identified the most important parameters at 12 borehole arrays in the United States by analyzing weak-motion empirical and theoretical site responses in terms of soil-to-rock spectral ratios and ratios of response spectra at each site in the frequency range of engineering interest, 0.1–10 Hz (i.e., a period range of 0.1–10 s). From these ratios, we extracted two sets of parameter pairs: the fundamental and peak mode frequencies, f0 and fp, respectively, and their corresponding amplifications, A0 and Ap, respectively. We also characterized the Vs profiles using the shear-wave velocity ratio (Rj) and impedance ratio IRj and determined the maximum velocity and impedance ratios (Rmax and IRmax) for these borehole arrays. Both the linear empirical and theoretical results confirm that site response is site-specific and controlled predominantly by each site's in situ shear-wave velocity (Vs) profile in terms of shear-wave velocity ratios or impedance ratios, the maximum velocity or impedance ratio in particular. Our studies suggest that a minimum bedrock-sediment shear-wave velocity ratio of about 2.5 (i.e., Rmax≥2.5) or impedance ratios of about 3.0 (i.e., IRmax ≥ 3.0) is required to generate site resonance. Our results show that the fundamental mode is the most important mode for quantifying site response for engineering purposes at sites where amplifications are controlled by site resonance because it is the dominant mode on the ratios of response spectra. We also compared five proxies derived from each site's velocity profile—the time-averaged shear-wave velocity for the top 30 m (VS30), depth to bedrock or basin depth (Zb), time-averaged shear-wave velocity of sediment (Vs‾), ratio of bedrock shear-wave velocity (Vsb) to Vs‾ (Rmax), and ratio of bedrock impedance to the average sediment impedance (IRmax)—with the empirical fundamental resonant mode parameters. The comparisons revealed that Zb and Rmax (or IRmax) are the best pair of proxies to parameterize the fundamental resonant mode parameters. The comparisons also show that VS30 is not the best proxy and that no single proxy is sufficient to parameterize the fundamental resonant mode parameters.