Journal articles on the topic 'Impedance'
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Kurniawan, Widodo Budi. "PENGUKURAN NILAI DIELEKTRIK MATERIAL CALCIUM COPPER TITANAT ( CaCu3Ti4O12) MENGGUNAKAN SPEKTROSKOPI IMPEDANSI TERKOMPUTERISASI." Jurnal Sains Dasar 6, no. 1 (May 22, 2017): 26. http://dx.doi.org/10.21831/jsd.v6i1.13565.
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Telah dilakukan pengukuran tetapan dielektrik kompleks dan besarnya impedansi kapasitor pada material keramik Calcium Copper Titanate dengan struktur material CaCu3Ti4O12 (CCTO) dengan kemurnian 99 % menggunakan metode spektroskopi impedansi terkomputerisasi dalam rentang frekuensi 5 kHz – 120 kHz. Tetapan dielektrik maksimum terukur pada sampel yang disintering dengan suhu 7000C yaitu 745 pada frekuensi 5 kHz dan besarnya impedansi kapasitor maksimum terjadi pada sampel CCTO non sintering yaitu 150434 Ω. Hasil penelitian menunjukkan adanya pengaruh frekuensi terhadap tetapan dielektrik kompleks dan impedansi kapasitor dari material yang diteliti. Kata kunci : spektroskopi impedansi, CaCu3Ti4O12, tetapan dielektrik kompleks dan impedansi kapasitor. MEASUREMENT OF THE DIELECTRIC CONSTANT CALCIUM COPPER TITANATE (CaCu3Ti4O12) MATERIALS USING COMPUTERIZED IMPEDANCE SPECTROSCOPY ABSTRACT The measurement of the complex dielectric constant and the magnitude of the capacitor impedances of the ceramic materials Calcium Copper Titanate CaCu3Ti4O12 (CCTO) with purity of 99% has been done by using the method of computerized impedance spectroscopy in the frequency range 5 kHz - 120 kHz. The highest dielectric constant of the material was found to be 745 at 5 kHz in the sample sintered 7000C and the highest impedance of capacitor occured in CCTO sample non sintered that is 150434Ω. The results showed that complex dielectric constant and impedance of the capacitor of the material under study was frequency dependent. Keywords : impedance spectroscopy, CaCu3Ti4O12,complex dielectric constant and impedance of capacitor
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Zhang, Wei-Bo, Dong-Myong Jeong, Yong-Heum Lee, and Myeong Soo Lee. "Measurement of Subcutaneous Impedance by Four-Electrode Method at Acupoints Located with Single-Power Alternative Current." American Journal of Chinese Medicine 32, no. 05 (January 2004): 779–88. http://dx.doi.org/10.1142/s0192415x04002351.
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A Single-Power Alternating Current (SPAC) instrument was used to measure the low-impedance acupoints around Ho-Ku (LI-4), Yang-Hsi (LI-5), Yang-Ch'ih (TB-4), Yang-Ku (SI-5), T'ai-Yuan (Lu-9), Ta-Lung (EH-7) and Shen-Men (He-7). A four-electrode instrument was used to measure the subcutaneous impedance at these low-impedance acupoints and adjacent control points on 12 healthy people. The mean subcutaneous impedance at the acupoints was 49.8±8.4 Ω, significantly lower than the impedance of 53.5±9.3 Ω for the control points (P<0.005). Of the seven acupoints, five (71%) had significantly lower impedances than the mean impedance for the adjacent control points. Seven of the 14 control points had significantly higher impedances than the adjacent acupoints, with most control points (93%) having higher impedances than adjacent acupoints. In conclusion, subcutaneous impedance is lower at the low-impedance points as measured with the SPAC two-electrode method. One interpretation of these results is that more interstitial fluid lies beneath the low-impedance acupoints.
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Thompson, D. "Partially Fractal Impedance Networks." Zeitschrift für Naturforschung A 53, no. 10-11 (November 1, 1998): 819–22. http://dx.doi.org/10.1515/zna-1998-10-1103.
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Abstract We analyse linear networks of impedances in the case when the impedances at every level differ by a factor of b from those at the previous level. Such networks can be used as models for rough surfaces, in which case there will exist a level of finest detail which must be taken into account in any calculation. We obtain an exact expression for the ratio of the impedance of the network to the outer impedance for an arbitrary number of elements in the network. We show that this class of networks shows a transition from a fractal geometric structure to a non-fractal structure according to the value of b. However, their effective impedance is never fractal.
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Lee, Woochan, and Dukju Ahn. "Wireless Power Transfer under Wide Distance Variation Using Dual Impedance Frequency." Electronics 9, no. 1 (January 7, 2020): 110. http://dx.doi.org/10.3390/electronics9010110.
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A dual-impedance operation, where coil impedance is controlled by operating frequency selection, is proposed to maintain optimum reflected impedance across coupling variation. More specifically, this work focuses on how high coupling between coils presents excessively high reflected resistance to transmitter (Tx) inverters, degrading the efficiency and output power of the inverter. To overcome this problem, the proposed system is equipped with dual-impedance coil and selects high- or low-impedance coil based on the ability to operate both at 200 kHz and 6.78 MHz frequencies. The reactive impedances of 6.78 MHz coils are designed to be higher than that of 200 kHz coils. Since the reflected resistance is proportional to the coil impedances and coupling squared, at close distance with high coupling coefficient, 200 kHz coils with low coil impedances are activated to prevent an excessive rise in reflected resistance. On the other hand, at large distance spacing with low coupling coefficient, 6.78 MHz coils with high coil impedances are activated so that sufficient reflected resistance is obtained even under the small coupling. The proposed system’s advantages are the high efficiency and the elimination of bulky mechanical relay switches. Measured efficiencies are 88.6–50% across 10 coupling variations.
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Liu, Hongmei, Yongquan Guo, Xinshuo Wang, Shaojun Fang, and Zhongbao Wang. "Design of Compact Complex Impedance Transformer with Frequency and Terminal Impedance Tunability." Electronics 11, no. 7 (March 22, 2022): 983. http://dx.doi.org/10.3390/electronics11070983.
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In the paper, a compact complex impedance transformer (CIT) composed of the cascading of three varactors loaded coupled lines and two variable shunt susceptances was proposed. Highly flexible tunability functions including only frequency tunable, only impedance tunable, and both frequency and impedance tunable can be achieved by tuning the capacitance of two types of varactors and the value of the susceptance. Design equations were derived using the even–odd mode analysis and examples are given for descripting the design procedures. For validation, a prototype was designed and fabricated. During measurement, three cases were exhibited. When the termination impedance was fixed, the measured center frequency can be tuned in the range of 1.1–2.1 GHz (62.5%). When the frequency was determined, different terminal impedances can be matched by the prototype. The function of frequency tunable at different terminal impedances is also trated by the measured results. After comparison, the potential of the proposed CIT for applications in radio frequency front-end were demonstrated.
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Cai, Zheng, Sainan Li, Qi Zhang, Chenyuan Wang, Zhen Jin, Ming Fu, Shuai Zhang, Ming Liang, Zulu Wang, and Yaling Han. "Derivation and Verification of the Relationship between Ablation Index and Baseline Impedance." Cardiology Research and Practice 2021 (July 12, 2021): 1–6. http://dx.doi.org/10.1155/2021/5574125.
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Objective. To explore the quantitative adjustment of ablation index (AI) under different baseline impedance to achieve similar lesion dimensions. Methods. (1) Keeping the AIs relatively constant, the lesion dimensions in different baseline impedances were studied. (2) According to Joule's law, Q = I2RT, keeping the current (I) unchanged, the powers corresponding to different baseline impedances can be obtained. Under different baseline impedances and corresponding powers, the swine hearts were ablated for 30 s in simulated human circumstances. The baseline impedances, the lesion dimensions, and AIs were recorded. And the derivation of empirical formula was achieved according to the AIs and baseline impedance values in similar lesions dimension. (3) Basic AI and baseline impedance (AI0/R0) were set as 400/120 Ω in the common AI groups and 550/120 Ω in the high AI groups, AI values in different baseline impedances were calculated using the empirical formula, and the corresponding lesion dimensions were measured to verify this formula. Results. (1) Higher baseline impedances were related to smaller lesion dimensions at similar AIs. (2) The lesion dimensions were roughly the same after modulating the baseline impedance and power to keep the electric current relatively constant. The relationship between AI and R fitted with experimental data is AI = 1.9933R + 203.61 (r = 0.9649), and the formula derived is ΔAI = (AI0 − 203)/R0 × ΔR. (3) Under the guidance of the empirical formula, there was no significant difference in lesion dimensions between the standard group and the formula guiding groups when AI0 = 400, but there was a shrinking tendence when AI > 700. Conclusion. The lesion depths are negatively correlated with baseline impedance at a certain AI. The relationship between baseline impedance and AI is “ΔAI = (AI0 − 203)/R0 × ΔR”. It is verified that when the AI is not too high, the empirical formula can be used to guide the quantitative adjustment of AIs at different baseline impedance, and the lesion depths achieved are roughly the same.
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Irastorza, Ramiro M., Timothy Maher, Michael Barkagan, Rokas Liubasuskas, Juan J. Pérez, Enrique Berjano, and Andre d’Avila. "Limitations of Baseline Impedance, Impedance Drop and Current for Radiofrequency Catheter Ablation Monitoring: Insights from In Silico Modeling." Journal of Cardiovascular Development and Disease 9, no. 10 (October 3, 2022): 336. http://dx.doi.org/10.3390/jcdd9100336.
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Background: Baseline impedance, radiofrequency current, and impedance drop during radiofrequency catheter ablation are thought to predict effective lesion formation. However, quantifying the contributions of local versus remote impedances provides insights into the limitations of indices using those parameters. Methods: An in silico model of left atrial radiofrequency catheter ablation was used based on human thoracic measurements and solved for (1) initial impedance (Z), (2) percentage of radiofrequency power delivered to the myocardium and blood (3) total radiofrequency current, (4) impedance drop during heating, and (5) lesion size after a 25 W–30 s ablation. Remote impedance was modeled by varying the mixing ratio between skeletal muscle and fat. Local impedance was modeled by varying insertion depth of the electrode (ID). Results: Increasing the remote impedance led to increased baseline impedance, lower system current delivery, and reduced lesion size. For ID = 0.5 mm, Z ranged from 115 to 132 W when fat percentage varied from 20 to 80%, resulting in a decrease in the RF current from 472 to 347 mA and a slight decrease in lesion size from 5.6 to 5.1 mm in depth, and from 9.2 to 8.0 mm in maximum width. In contrast, increasing the local impedance led to lower system current but larger lesions. For a 50% fat–muscle mixture, Z ranged from 118 to 138 W when ID varied from 0.3 to 1.9 mm, resulting in a decrease in the RF current from 463 to 443 mA and an increase in lesion size, from 5.2 up to 7.5 mm in depth, and from 8.4 up to 11.6 mm in maximum width. In cases of nearly identical Z but different contributions of local and remote impedance, markedly different lesions sizes were observed despite only small differences in RF current. Impedance drop better predicted lesion size (R2 > 0.93) than RF current (R2 < 0.1). Conclusions: Identical baseline impedances and observed RF currents can lead to markedly different lesion sizes with different relative contributions of local and remote impedances to the electrical circuit. These results provide mechanistic insights into the advantage of measuring local impedance and identifies potential limitations of indices incorporating baseline impedance or current to predict lesion quality.
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Arada, Gerald Pacaba. "A Study on Input Impedance and Self/Mutual Impedances of Orthogonal Crossed Circular Loops." Journal of Advanced Research in Dynamical and Control Systems 12, SP8 (July 30, 2020): 1062–72. http://dx.doi.org/10.5373/jardcs/v12sp8/20202619.
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Nie, Yafei, Jie Wang, Chengshi Zheng, Jian Xu, Xiaodong Li, Yu Wang, Bo Zhong, Juanjuan Cai, and Jinqiu Sang. "Measurement and modeling of the mechanical impedance of human mastoid and condyle." Journal of the Acoustical Society of America 151, no. 3 (March 2022): 1434–48. http://dx.doi.org/10.1121/10.0009618.
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Bone conduction devices are used in audiometric tests, hearing rehabilitation, and communication systems. The mechanical impedance of the stimulated skull location affects the performance of the bone conduction devices. In the present study, the mechanical impedances of the mastoid and condyle were measured in 100 Chinese subjects aged from 22 to 67 years. The results show that the mastoid and condyle impedances within the same subject differ significantly and the impedance differences between subjects at the same stimulation position are mainly below the resonance frequency. The mechanical impedance of the mastoid is significantly influenced by age, and not related to gender or body mass index (BMI). While the mechanical impedance of the condyle is significantly affected by BMI, followed by gender, and not related to age. There are some differences in mastoid impedance between the Chinese and Western subjects. An analogy model predicts that the difference in mechanical impedance between the mastoid and condyle leads to a significant difference in the output force of the bone conduction devices. The results can be used to develop improved condyle and mastoid stimulators for the Chinese.
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Huang, Shichun, Liang Yu, and Weikang Jiang. "Measurement of loudspeaker mechanical impedance by changing the sound load at the throat of loudspeaker." INTER-NOISE and NOISE-CON Congress and Conference Proceedings 263, no. 1 (August 1, 2021): 5457–66. http://dx.doi.org/10.3397/in-2021-3112.
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A loudspeaker is a device that converts electrical energy into acoustic energy by coupling between electrical impedance, mechanical impedance, and radiation impedance. The loudspeaker electro-mechanical-acoustic coupling model provides the experimental feasibility to measure the characteristic parameters. In this paper, an economical and practical measurement method of loudspeaker mechanical impedance is proposed. First, the mathematical relationship between loudspeaker electrical impedance and mechanical impedance is obtained based on the loudspeaker electro-mechanical-acoustic coupling model. Second, two electrical impedances with different known radiation impedance are measured by using a developed measurement system. Finally, the real and imaginary parts of the mechanical impedance are obtained according to the mathematical relationship. This method neither assumes that the loudspeaker mechanical impedance is constant in a frequency band nor does it build FEM models based on structural parameters. A loudspeaker is measured by using a developed measurement system. The result shows that the mechanical impedance and the force factor are functions of frequency. Moreover, a radiation impedance measurement is performed to verify the feasibility and accuracy of the proposed method.
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Feng, Guoli, Zhihao Ye, Yihui Xia, Liming Huang, and Zerun Wang. "Impedance Modeling and Stability Analysis of Three-Phase Four-Wire Inverter with Grid-Connected Operation." Energies 15, no. 8 (April 8, 2022): 2754. http://dx.doi.org/10.3390/en15082754.
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With the continuous penetration and development of renewable energy power generation, distributed grids and microgrids are becoming increasingly important in power systems. In the distribution networks and microgrids, the grid impedance is comparatively large and cannot be ignored. Usually, the parallel compensation is used to improve the grid quality. In these three-phase four-wire power systems, analyzing the impedance characteristics of the grid-connected inverter is vital to carry out the small-signal stability analysis. Thus, it is vital to consider the influence of the zero-sequence component in addition to the positive-sequence component and the negative-sequence component when it comes to analyzing system stability. In this paper, the impedances of three-phase four-wire split capacitor inverter and three-phase four-leg inverter are established. Based on the achieved impedance, the similarities and differences between the impedances of three-phase four-wire split capacitor inverter and impedance of three-phase four-leg inverter are studied. The main difference is reflected in zero-sequence impedance. Additionally, the zero-sequence impedance characteristics and the dominating factors deciding the zero-sequence impedance are analyzed. Then, the stability of the system considering the grid impedance and impedance of three-phase four-wire inverter is investigated by separately considering the stability of the positive–negative-sequence component and the stability of the zero-sequence component. Several cases of small-signal instability caused by the positive–negative-sequence component or zero-sequence component are revealed. The experimental results validate the theoretical analysis.
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Yang, Ling, Yandong Chen, Hongliang Wang, An Luo, and Kunshan Huai. "Oscillation Suppression Method by Two Notch Filters for Parallel Inverters under Weak Grid Conditions." Energies 11, no. 12 (December 8, 2018): 3441. http://dx.doi.org/10.3390/en11123441.
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With plenty of parallel inverters connected to a weak grid at the point of common coupling (PCC), the impedance coupling interactions between the inverters and the grid are enhanced, which may cause high-frequency harmonic oscillation and further aggravate the system instability. In this paper, a basic technique for inverter output impedance is proposed to suppress the oscillation, showing that the inverter output impedance should be designed relatively high at the harmonic oscillation frequency, while relatively low at other frequencies. On the basis of the proposed technique, two virtual impedances are added to be in parallel and in series with the original inverter output impedance, respectively. Thus, an oscillation suppression method by two notch filters is proposed to realize the virtual impedances and increase the whole system damping. The implementation forms of the virtual impedances are presented by the proposed PCC voltage feedforward and grid-side inductor current feedback with two notch filters. Finally, simulation and experimental results are provided to verify the validity of the proposed control method.
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Zayed, E. M. E., and A. I. Younis. "On the spectrum of the negative Laplacian for general doubly-connected bounded domains." International Journal of Mathematics and Mathematical Sciences 18, no. 2 (1995): 245–54. http://dx.doi.org/10.1155/s0161171295000305.
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This paper is devoted to asymptotic formulas for functions related with the spectrum of the standard Laplace operator in two and three dimensional bounded doubly connected domains with impedance boundary conditions, where the impedances are assumed to be positive functions. Moreover, asymptotic expressions for the difference of eigenvalues related to impedance boundary value problems with different impedances are derived. Further results may be obtained.
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Wang, N., Y. Zhang, H. S. Xu, Y. D. Liu, J. T. Li, C. T. Lin, Y. T. Wang, H. J. Zheng, and J. Y. Zhai. "Impedance driven collective effects in CEPC." Journal of Instrumentation 19, no. 02 (February 1, 2024): P02016. http://dx.doi.org/10.1088/1748-0221/19/02/p02016.
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Abstract The Circular Electron Positron Collider is a double ring lepton collider covering beam energy from 45 GeV (Z) to 180 GeV (tt-bar). Beam coupling impedance and the collective effects that are triggered by the impedance are important subjects when targeting high machine performance of an electron positron collider. A robust impedance model is required for the instabilities evaluations as well as to investigate their possible mitigations. Meanwhile, a thorough investigation on the collective effects is essential to identify the critical issues on the beam instabilities. In this paper, a detailed impedance model has been built for the collider ring and dominant impedance contributors have been identified by evaluating the effective impedances. The potential collective instabilities driven by the impedance are also discussed.
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ZHU, YI-SHENG, and WAI-KAI CHEN. "SHORT-STEP BUTTERWORTH IMPEDANCE TRANSFORMERS." Journal of Circuits, Systems and Computers 11, no. 02 (April 2002): 165–72. http://dx.doi.org/10.1142/s0218126602000331.
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Based on a relationship among the order n (= 2m) of the impedance transformer, the impedance transformation ratio r and the 3-dB frequencies ωa and ωb, a 2m-order Butterworth semi-lumped-element impedance transformer is designed by using a coaxial structure, consisting of a cascade of line sections having various line impedances zi with the same effective length l. The performance of the resulting transformer is comparable to that of a smaller size quarter-wavelength transformer.
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Santos, José, and Pedro Ramos. "DSPIC-Based Impedance Measuring Instrument." Metrology and Measurement Systems 18, no. 2 (January 1, 2011): 185–98. http://dx.doi.org/10.2478/v10178-011-0002-0.
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DSPIC-Based Impedance Measuring Instrument An implemented impedance measuring instrument is described in this paper. The device uses a dsPIC (Digital Signal Peripheral Interface Controller) as a processing unit, and a DDS (Direct Digital Synthesizer) to stimulate the measurement circuit composed by the reference impedance and the unknown impedance. The voltages across the impedances are amplified by programmable gain instrumentation amplifiers and then digitized by analog to digital converters. The impedance is measured by applying a seven-parameter sine-fitting algorithm to estimate the sine signal parameters. The dsPIC communicates through RS-232 or USB with a computer, where the measurement results can be analyzed. The device also has an LCD to display the measurement results.
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Zhang, Sheng Guo, and Xiao Ping Dang. "Proof and Application of Complex Impedance of Inductor and Capacitor." Applied Mechanics and Materials 568-570 (June 2014): 1213–16. http://dx.doi.org/10.4028/www.scientific.net/amm.568-570.1213.
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This paper aims at proving the complex impedance of the inductor and capacitor elements and applying the proved complex impedance concept to directly obtain the transfer function model of the complicated circuit network. Based on Laplace Transformation method, the complex impedances of the inductor and capacitor elements are proved. Using the proved complex impedances and the equivalent complex impedances in series and in parallel, both the transfer functions of the passive and active circuit networks are modeled. This facilitates the transfer function modeling of the complicated circuit network very much.
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Morozov, Igor B. "Exact elastic P/SV impedance." GEOPHYSICS 75, no. 2 (March 2010): C7—C13. http://dx.doi.org/10.1190/1.3318268.
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Several extensions of the concept of acoustic impedance (AI) to oblique incidence exist and are known as elastic impedances (EI). These quantities are constructed by heuristic integrations of reflectivity series but still involve approximations and do not represent a unique medium property. Nevertheless, for unambiguous interpretation, it is desirable to have an EI that would (1) be a mechanical property of the medium and (2) yield exact reflection coefficients at all angles of incidence. Here, such a definition is given for P- and/or SV-wave propagation in an arbitrary isotropic medium. The exact elastic P/SV impedance is a matrix quantity and represents the differential operator relating the stress and strain boundary conditions. With the use of the matrix form of the reflectivity problem, no approximations are required for accurate modeling of reflection (P/P and SV/SV) and mode-conversion (P/SV and SV/P) coefficients at all angles and for any contrasts in elastic properties. The matrix EI can be computed from real well logs and inverted from ray-parameter-dependent seismic reflectivity. Known limiting cases of P- and S-wave acoustic impedances are accurately reproduced and the approach also allows the extension of the concept of impedance to an attenuative medium. The matrix impedance readily lends itself to inversion with uncertainties typical of the standard acoustic-impedance inversion problem.
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Gouda, Mohammed Fathy, Abdul Halim Abdul Latiff, and Seyed Yasser Moussavi Alashloo. "Estimation of Litho-Fluid Facies Distribution from Zero-Offset Acoustic and Shear Impedances." Applied Sciences 12, no. 15 (August 1, 2022): 7754. http://dx.doi.org/10.3390/app12157754.
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Seismic data are considered crucial sources of data that help identify the litho-fluid facies distributions in reservoir rocks. However, different facies mostly have similar responses to seismic attributes. In addition, seismic anisotropy negatively affects the facies predictors extracted from seismic data. Accordingly, this study aims at estimating zero-offset acoustic and shear impedances based on partial-stack inversion by two methods: statistical modeling and a multilayer feed-forward neural network (MLFN). The resulting impedance volumes are compared to those obtained from isotropic simultaneous inversion by using impedance logs. The best impedance volumes are applied to Thomsen’s anisotropy equations to solve for the anisotropy parameters Epsilon and Delta. Finally, the shear and acoustic impedances are transformed into elastic properties from which the facies and fluid distributions are predicted by using the logistic regression and decision tree algorithms. The results obtained from the MLFN show better matching with the impedance and facies logs compared to those obtained from isotropic inversion and statistical modeling.
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Liu, Wang Sheng, Ya An Li, Lin Cui, and Ming Huan Wang. "The Mutual Impedance Analysis of a Broadband Dense Plane Array." Advanced Materials Research 443-444 (January 2012): 1019–25. http://dx.doi.org/10.4028/www.scientific.net/amr.443-444.1019.
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Due to the mutual radiation impedance may influence acoustics performance of a broadband dense plane array seriously, the expression of mutual radiation impedance among the transducers is developed according to the definition of mutual radiation impedance based on BEM（Boundary Element Method）. BEM model is established for acoustic radiation of a broadband dense plane array with nine elements. Sound pressure distribution of the nine-element array is solved using SYSNOISE software. And mutual radiation impedances are calculated on the condition of knowing surface normal velocity. Acoustic performance of the nine-element array is analysed through mutual radiation impedance. The influence of mutual impedance on acoustics performance for nine-element array is verified by comparing with measured curve of transducer conductance. The results show that it is successful to calculate mutual impedance of the array and predict acoustics performance using BEM.
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Neroni, M., M. Barnes, L. Ducimetiere, A. Lasheen, A. Mostacci, B. Popovic, P. Trubacova, and C. Vollinger. "Characterization of the longitudinal beam coupling impedance and mitigation strategy for the fast extraction kicker KFA79 in the CERN PS." Journal of Physics: Conference Series 2687, no. 6 (January 1, 2024): 062012. http://dx.doi.org/10.1088/1742-6596/2687/6/062012.
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Abstract In the framework of the High Luminosity Upgrade of the LHC (HL-LHC) the beam intensity from the injectors must be doubled while keeping longitudinal beam parameters unchanged. As such, high-quality beams with high intensities are required also from the Proton Synchrotron (PS). The beam coupling impedance plays a crucial role and mitigation measures must be taken to remain within a stringent impedance budget. Kicker magnets are important contributors to the overall broadband impedance of the PS. Moreover, the detailed study of kicker impedances revealed additional resonant modes which may be critical for the beam stability. The longitudinal beam coupling impedance for the fast extraction kicker KFA79 is presented in this study, and a solution to reduce the impedance of the critical resonant modes is introduced. Electromagnetic (EM) simulations have been performed to determine the impedance behaviour. Finally, the insertion of transition pieces between magnet modules is presented as a measure for mitigating the low frequency resonant impedance contributions.
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Redfield, R. C., and S. Krishnan. "Dynamic System Synthesis With a Bond Graph Approach: Part I—Synthesis of One-Port Impedances." Journal of Dynamic Systems, Measurement, and Control 115, no. 3 (September 1, 1993): 357–63. http://dx.doi.org/10.1115/1.2899110.
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This is the first part of a two-part paper developing a procedure for impedance synthesis and dynamic system conceptual design using a bond graph approach. The first part examines impedance synthesis with bond graphs and develops some useful properties of impedance related to bond graph structure. The second part of the paper uses the impedance synthesis approach as a tool in conceptual design for generating dynamic system solutions meeting frequency domain input-output specifications. In Part I, impedance and transfer functions are directly formulated from bond graphs. An invertible procedure is developed in order to allow for synthesis. Frequency domain properties of bond graphs are developed that will aid in impedance synthesis and the synthesis of bond graph structures from impedance specifications is formulated with a view toward conceptual design. The synthesis is not unique, a given impedance can be synthesized into multiple bond graph structures depending on its complexity. The work presented focuses on the synthesis of passive impedances but may be generalized for active systems.
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Križaj, Dejan, and Borut Pečar. "Analysis of impedance measurements of a suspension of microcapsules using a variable length impedance measurement cell." Journal of Electrical Bioimpedance 3, no. 1 (July 23, 2019): 42–50. http://dx.doi.org/10.5617/jeb.215.
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Abstract Electrical impedance measurements of a suspension have to take into account the double layer impedance that results from a very thin charged layer formed at the electrode-electrolyte interface. A dedicated measuring cell that enables variation of the distance between the electrodes was developed to investigate the electrical properties of suspensions using two-electrode impedance measurements. By varying the distance between the electrodes it is possible to separate the double layer and the suspension impedance from the measured data. Electrical ‘lumped’ models have been developed from measured and extracted impedances. The error of non-inclusion of the double layer impedance has been analyzed. The error depends on the frequency of the measurement as well as the distance between the electrodes.
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Darabundit, Champ C., and Gary Scavone. "Acoustic impedance measurement head design and evaluation." Journal of the Acoustical Society of America 155, no. 3_Supplement (March 1, 2024): A150. http://dx.doi.org/10.1121/10.0027128.
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Acoustic input impedance measurements are a useful tool for characterizing the behavior of a wind instrument. Methods for measuring acoustic input impedances include the two-microphone three-calibration (TMTC) technique (Gibiat and Laloë, 1990) and the multi-microphone method (Jang and Ih, 1998). We present and evaluate the design of a new impedance measurement head based on the multi-microphone method. We will discuss practical aspects such as impedance head calibration, measurement stimulus, and leak detection.
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Purnamasari, Anastasia Neni Candra. "Metode Inversi AVO Simultan untuk Mengetahui Sebaran Hidrokarbon Formasi Baturaja, Lapangan "Wine”, Cekungan Sumatra Selatan." Jurnal Offshore: Oil, Production Facilities and Renewable Energy 1, no. 1 (July 13, 2017): 26. http://dx.doi.org/10.30588/jo.v1i1.239.
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<p>Data seismik 3D (<em>CDP</em> <em>gather</em>) pada daerah penelitian dilakukan proses inversi prestack yaitu inversi AVO simultan untuk mengetahui sebaran hidrokarbon. Data seismik 3D terbentang dengan jangkauan <em>inline</em> 1003-1302 dan <em>xline</em> 5002-5300. Metode inversi AVO simultan dilakukan dengan data masukan berupa <em>angle stack</em> yang diinversi secara bersama-sama (simultan) untuk menghasilkan impedansi-P, impedansi-S dan densitas. Dari hasil inversi impedansi-P dan inversi impedansi-S didapatkan nilai <em>lambda-rho</em><em> </em>dan <em>mu-rho</em><em> </em>sebagai hasil turunannya. Kisaran nilai hasil inversi impedansi-P, impedansi-S, densitas, <em>lambda-rho </em>dan<em> mu-rho</em> pada <em>porous limestone</em> formasi Baturaja yaitu nilai impedansi-P sekitar 11000-13500 m/s*g/cc, nilai impedansi-S sekitar 6500-7400 m/s*g/cc, nilai densitas sekitar 2,52-2,6 g/cc, nilai <em>lambda-rho</em><em> </em>sekitar 36-70 Gpa*g/cc dan nilai <em>mu-rho</em><em> </em>sekitar 41-59 Gpa*g/cc. Berdasarkan <em>map slice</em><em> </em>hasil inversi impedansi-P, <em>map slice</em><em> </em>hasil inversi impedansi-S, <em>map slice</em><em> </em>hasil inversi densitas, <em>map slice</em><em> </em>hasil inversi <em>lambda-rho</em><em> </em>dan <em>map slice</em><em> </em>hasil inversi <em>mu-rho</em> dapat diketahui area persebaran hidrokarbon pada formasi Baturaja. Persebaran hidrokarbon berada di sekitar sumur TT.</p><p><em>3D seismic data (CDP gather) in the study area was carried out a prestack inversion process, namely simultaneous AVO inversion to determine the distribution of hydrocarbons. 3D seismic data stretches with inline range 1003-1302 and xline 5002-5300. Simultaneous AVO inversion method is done with input data in the form of angle stack which is inverted together (simultaneously) to produce P-impedance, S-impedance and density. From the results of P-impedance inversion and S-impedance inversion, the values of lambda-rho and mu-rho are derived as a result of their derivatives. The range of values of P-impedance inversion, S-impedance, density, lambda-rho and mu-rho in porous limestone formation i.e. the P-impedance value around 11000-13500 m/s*g/cc, the S-impedance value around 6500-7400 m/s*g/cc, the density value around 2.52-2.6 g/cc, the lambda-value rho around 36-70 Gpa*g/cc and your value around 41-59 Gpa*g/cc. Based on the P-impedance inversion map slice, S-impedance inversion map slice, density inversion map slice, lambda-rho inversion map slice and mu-rho inversion map slice can be known the area of hydrocarbon distribution in the Baturaja formation. Hydrocarbon spread is around the TT well.</em></p>
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Chou, Jung-Chuan, Chin-Hui Huang, Yi-Hung Liao, Yu-Jen Lin, Chia-Ming Chu, and Yu-Hsun Nien. "Analysis of Different Series-Parallel Connection Modules for Dye-Sensitized Solar Cell by Electrochemical Impedance Spectroscopy." International Journal of Photoenergy 2016 (2016): 1–8. http://dx.doi.org/10.1155/2016/6595639.
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The internal impedances of different dye-sensitized solar cell (DSSC) models were analyzed by electrochemical impedance spectrometer (EIS) with an equivalent circuit model. The Nyquist plot was built to simulate the redox reaction of internal device at the heterojunction. It was useful to analyze the component structure and promote photovoltaic conversion efficiency of DSSC. The impedance of DSSC was investigated and the externally connected module assembly was constructed utilizing single cells on the scaled-up module. According to the experiment results, the impedance was increased with increasing cells connected in series. On the contrary, the impedance was decreased with increasing cells connected in parallel.
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Pathan, Erum, Afarulrazi Abu Bakar, Mubashir Hayat Khan, Muhammad Asad, and Haider Arshad. "Multiloop low bandwidth communication-based power sharing control for microgrids." Indonesian Journal of Electrical Engineering and Computer Science 21, no. 2 (February 1, 2020): 682. http://dx.doi.org/10.11591/ijeecs.v21.i2.pp682-690.
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<span>In parallel-connected inverter-based microgrids, the reactive power sharing accuracy can not have satisfactory results effortlessly. Mismatch in feeder impedances of the parallel-connected inverter-based microgrids is a significant cause of inaccurate reactive power-sharing. In voltage source inverters (VSI) based microgrids, especially for the islanded mode of operation, the conventional centralized or decentralized control techniques are not much helpful to control the voltage deviations due to impedance mismatch. Mismatch of the feeder impedance is compensated by the addition of fixed virtual impedance. Whereas, the change in the virtual impedance is compensated by adaptive virtual impedance-based control techniques which are helpful to mitigate power-sharing errors, but in most of the control schemes virtual impedance-based control mechanism needs pre-knowledge of feeder impedance which increases the computational burden. This paper presents a decentralized virtual impedance-based power sharing control. In the proposed control solution to mitigate reactive power sharing errors in distributed generation (DG) units, mismatch of the parallel-connected feeder impedance is equalized by regulating the addition of equivalent impedance to each DG inverter. Proposed control technique offers an independent implementation without any pre-knowledge of the feeder impedance. Hence, the implementation of the control scheme is a straightforward and computational burden is also reduced. Simulation results show the effectiveness of the control scheme. </span>
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Cao, Qinghua, Dingfang CaoChen, Quanguo Lu, Jianwu LuYan, Gang Tang, Zhifang Zhu, Zhang Xiaoxing, and Tao Zhen. "Laminated Structures and Measurement of Magnetostriction for Transducer Applications." Open Mechanical Engineering Journal 8, no. 1 (September 16, 2014): 279–84. http://dx.doi.org/10.2174/1874155x01408010279.
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This paper aims to designed a prototype for achieving the full magnetostriction of Galfenol, Lamination struction of transducer is designed and the radiation impedance is expressed in mechanical terms, a simplified onedimensional modeling of SPICE magnetostrictive transducer is established, the electrical input impedance is simulated as the function of frequency and experimentally adjusting the values is to match an existing impedance curve. a good fit between model and measurement is shown by measured and simulated electrical input impedances for the device.
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Atre, Shashank R., and Charles R. Bentley. "Laterally varying basal conditions beneath ice Streams B and C, West Antarctica." Journal of Glaciology 39, no. 133 (1993): 507–14. http://dx.doi.org/10.1017/s0022143000016403.
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AbstractThe study of the phase of reflections of Ρ waves off the base of Ice Streams Β and C, and Ridge BC, indicates that acoustic impedances of the beds of both ice streams vary laterally. In some places, the impedance is higher than in the ice (a high-impedance bed) and in some places it is less (a low-impedance bed). The estimated impedances in a dilated bed (porosity 0.4) and in a model of the lowermost ice that takes into account the relatively low P-wave speed in ice at or very near the melting point are nearly the same. Whether the impedance in the bed is greater or less than in the ice could depend on minor changes in the nature of the sediments composing the bed, or the physical state of the bed (e.g. porosity) that could occur laterally. Lateral variations of this kind provide a ready explanation for the observations on Ice Stream B. The bed under a substantial part of Ice Stream C that exhibits a low-impedance bed also must be dilated. The evaluation of the state of the bed under the rest of Ice Stream C and on Ridge BC requires further analysis, which is in progress.
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Atre, Shashank R., and Charles R. Bentley. "Laterally varying basal conditions beneath ice Streams B and C, West Antarctica." Journal of Glaciology 39, no. 133 (1993): 507–14. http://dx.doi.org/10.3189/s0022143000016403.
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AbstractThe study of the phase of reflections of Ρ waves off the base of Ice Streams Β and C, and Ridge BC, indicates that acoustic impedances of the beds of both ice streams vary laterally. In some places, the impedance is higher than in the ice (a high-impedance bed) and in some places it is less (a low-impedance bed). The estimated impedances in a dilated bed (porosity 0.4) and in a model of the lowermost ice that takes into account the relatively low P-wave speed in ice at or very near the melting point are nearly the same. Whether the impedance in the bed is greater or less than in the ice could depend on minor changes in the nature of the sediments composing the bed, or the physical state of the bed (e.g. porosity) that could occur laterally. Lateral variations of this kind provide a ready explanation for the observations on Ice Stream B. The bed under a substantial part of Ice Stream C that exhibits a low-impedance bed also must be dilated. The evaluation of the state of the bed under the rest of Ice Stream C and on Ridge BC requires further analysis, which is in progress.
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Chiu, Wei-Chih, Wei-Ling Chen, Yi-Ting Lai, Yu-Han Hung, and Chun-Min Lo. "Cell–Electrode Models for Impedance Analysis of Epithelial and Endothelial Monolayers Cultured on Microelectrodes." Sensors 24, no. 13 (June 28, 2024): 4214. http://dx.doi.org/10.3390/s24134214.
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Electric cell–substrate impedance sensing has been used to measure transepithelial and transendothelial impedances of cultured cell layers and extract cell parameters such as junctional resistance, cell–substrate separation, and membrane capacitance. Previously, a three-path cell–electrode model comprising two transcellular pathways and one paracellular pathway was developed for the impedance analysis of MDCK cells. By ignoring the resistances of the lateral intercellular spaces, we develop a simplified three-path model for the impedance analysis of epithelial cells and solve the model equations in a closed form. The calculated impedance values obtained from this simplified cell–electrode model at frequencies ranging from 31.25 Hz to 100 kHz agree well with the experimental data obtained from MDCK and OVCA429 cells. We also describe how the change in each model-fitting parameter influences the electrical impedance spectra of MDCK cell layers. By assuming that the junctional resistance is much smaller than the specific impedance through the lateral cell membrane, the simplified three-path model reduces to a two-path model, which can be used for the impedance analysis of endothelial cells and other disk-shaped cells with low junctional resistances. The measured impedance spectra of HUVEC and HaCaT cell monolayers nearly coincide with the impedance data calculated from the two-path model.
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Korobitsina, Margarita, Alexander Kovalenko, and Andrey Kolomiets. "Simulation of the dynamics of an intense proton beam in a collider NICA." EPJ Web of Conferences 201 (2019): 08003. http://dx.doi.org/10.1051/epjconf/201920108003.
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In the physics of accelerators and colliders there is one important parameter as “impedance”. Impedance determines the level of the influence of the field induced by the beam in the longitudinal and transverse directions on the beam motion. Knowledge of the impedances is necessary for estimating the conditions for the stability of the beam motion in the designed accelerator. Thus, the main objective at the moment is the calculation of the impedance of each device in the collider for further calculation of their contribution to the general impedance. In the report the physics of the beam motion in an accelerator chamber is considered, the method of calculating the impedance - the method of electro-magnetic simulation through the CST Studio Suit software package is described, an example of the calculation of the impedance for the part of vacuum chamber of the quadrupole magnet, which is a part of the arch of the collider NICA is shown.
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Sharp, D. B., A. Mamou-Mani, and M. van Walstijn. "A Single Microphone Capillary-Based System for Measuring the Complex Input Impedance of Musical Wind Instruments." Acta Acustica united with Acustica 97, no. 5 (September 1, 2011): 819–29. http://dx.doi.org/10.3813/aaa.918462.
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Capillary-based systems for measuring the input impedance of musical wind instruments were first developed in the mid-20th century and remain in widespread use today. In this paper, the basic principles and assumptions underpinning the design of such systems are examined. Inexpensive modifications to a capillary-based impedance measurement set-up made possible due to advances in computing and data acquisition technology are discussed. The modified set-up is able to measure both impedance magnitude and impedance phase even though it only contains one microphone. In addition, a method of calibration is described that results in a significant improvement in accuracy when measuring high impedance objects on the modified capillary-based system. The method involves carrying out calibration measurements on two different objects whose impedances are well-known theoretically. The benefits of performing two calibration measurements (as opposed to the one calibration measurement that has been traditionally used) are demonstrated experimentally through input impedance measurements on two test objects and a Boosey and Hawkes oboe.
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ABRAMOVITZ, ALEXANDER. "SEVERAL ALTERNATIVE DERIVATIONS OF BLACKMAN'S IMPEDANCE RELATION." Journal of Circuits, Systems and Computers 18, no. 05 (August 2009): 909–21. http://dx.doi.org/10.1142/s0218126609005435.
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The Blackman's impedance relation formula holds several unique and important features. First and most important is generality. The formula is truly universal and could be applied regardless of feedback topology. The impedances of canonical cases could be presented as special cases of Blackman's impedance relation. This paper revisits the concepts of Blackman's impedance relation. Several alternative derivation approaches are suggested to stand in accord with the gain evaluation procedure. The derivation of the Blackman's impedance relation formula by Superposition, Thevenin, Trans-Admittance and Trans-Impedance methods are offered. The paper extends the ideas and completes the methodology of unified approach to analysis of feedback amplifiers presented earlier. The paper also discusses some additional features of the feedback amplifier model. The paper advocates that the described method of obtaining the loop-gain makes a real difference in application of the formula. Overcoming the loop-gain computational difficulties helps reestablish the Blackman's impedance relation as a viable tool in analysis of feedback circuits.
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Renzi, P. E., C. A. Giurdanella, and A. C. Jackson. "Improved frequency response of pneumotachometers by digital compensation." Journal of Applied Physiology 68, no. 1 (January 1, 1990): 382–86. http://dx.doi.org/10.1152/jappl.1990.68.1.382.
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To measure impedance one measures or estimates flow, which is commonly done by measuring the pressure drop across a pneumotachometer. The frequency response characteristics of standard pneumotachometer/pressure transducers (PPT) limit their use to relatively low frequencies. Also, the frequency response of PPTs has been reported to be “load” dependent. Thus, the frequency response characteristics measured under “no-load” conditions, which theoretically could be used to compensate subsequent measurements, may not be appropriate for measurements made under loaded conditions. Another method of measuring impedance exists which depends on a reference impedance element other than a pneumotachometer. In this method, an oscillatory flow signal with known amplitude is generated and used to force the system being tested. Unlike PPTs, this oscillatory flow generator (OFG) is a closed system that allows measurements to be made only during breath holding. Our objective was to determine whether the frequency response of a PPT could be compensated using measurements made under no-load conditions, such that it accurately measured an impedance load. The frequency response of the PPT under no-load conditions was measured by the OFG and used to compensate the output of the PPT in subsequent impedance measurements. The compensated PPT was used to measure the impedance of a mechanical structure and the impedances of four human subjects. The impedances of the mechanical structure and the subjects were also measured using the OFG.(ABSTRACT TRUNCATED AT 250 WORDS)
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Barnas, G. M., N. C. Heglund, D. Yager, K. Yoshino, S. H. Loring, and J. Mead. "Impedance of the chest wall during sustained respiratory muscle contraction." Journal of Applied Physiology 66, no. 1 (January 1, 1989): 360–69. http://dx.doi.org/10.1152/jappl.1989.66.1.360.
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We measured total chest wall impedance (Zw), "pathway impedances" of the rib cage (Zrcpath), and diaphragm-abdomen (Zd-apath), and impedance of the belly wall including abdominal contents (Zbw+) in five subjects during sustained expiratory (change in average pleural pressure [Ppl] from relaxation = 10 and 20 cmH2O) and inspiratory (change in Ppl = -10 and -20 cmH2O) muscle contraction, using forced oscillatory techniques (0.5–4 Hz) we have previously reported for relaxation (J. Appl. Physiol. 66: 350–359, 1989). Chest wall configuration and mean lung volume were kept constant. Zw, Zrcpath, Zd-apath, and Zbw+ all increased greatly at each frequency during expiratory muscle contraction; increases were proportional to effort. Zw, Zrcpath, and Zd-apath increased greatly during inspiratory muscle contraction, but Zbw+ did not. Resistances and elastances calculated from each of the impedances showed the same changes during muscle contraction as the corresponding impedances. Each of the resistances decreased as frequency increased, independent of effort; elastances generally increased with frequency. These frequency dependencies were similar to those measured in relaxed or tetanized isolated muscle during sinusoidal stretching (P.M. Rack, J. Physiol. Lond. 183: 1-14, 1966). We conclude that during respiratory muscle contraction 1) chest wall impedance increases, 2) changes in regional chest wall impedances can be somewhat independent, depending on which muscles contract, and 3) increases in chest wall impedance are due, at least in part, to changes in the passive properties of the muscles themselves.
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Zhang, Feng, and Xiang-Yang Li. "Exact elastic impedance matrices for transversely isotropic medium." GEOPHYSICS 81, no. 2 (March 1, 2016): C1—C15. http://dx.doi.org/10.1190/geo2015-0163.1.
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Conventional elastic impedances are derived as scalars by means of the integration of reflectivity. In this sense, they are attributes of the seismic reflection but not the intrinsic physical property of the subsurface media. The derivation of these expressions shares the same assumptions as the reflectivity approximations, such as weak impedance contrast, small angle of incidence, or weak anisotropic media, and thus it limits the accuracy and interpretation capability. The exact P/SV impedance matrices relating the stress and strain represent the mechanical property of the subsurface media and yield reflection coefficients at an arbitrary angle of incidence. We have extended the impedance matrices to a transversely isotropic medium. The resulting elastic impedances (stress/velocity ratios) can be used to characterize those unconventional reservoir formations with strong seismic anisotropy, such as shale-gas and coal-bed methane. Our numerical analyses determined their variations with the phase angle and anisotropy parameters. The exact expressions of the P- and S-wave elastic impedances are used to model the seismic reflection coefficients, and thus they can be inverted simultaneously if all of the types of reflection waves are available. We then derive approximations of quasi-P-wave elastic impedances for seismic inversion of anisotropy parameters and further interpretation. Our applications on real logs and seismic data for a turbidite fan reservoir and a shale-gas reservoir determined the robust interpretation capability of derived elastic impedances in lithology characterizations.
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MAHESHWARI, SUDHANSHU, JITENDRA MOHAN, and DURG SINGH CHAUHAN. "CASCADABLE ALL-PASS AND NOTCH FILTER CONFIGURATIONS EMPLOYING TWO PLUS-TYPE DDCCs." Journal of Circuits, Systems and Computers 20, no. 02 (April 2011): 329–47. http://dx.doi.org/10.1142/s0218126611007281.
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In this paper, twelve new circuit configurations for realization of first-order, second-order voltage-mode all-pass and notch filters with high input impedance and low output impedance are presented. The proposed circuit configurations use two plus type DDCCs, and two impedances. The circuits use one grounded capacitor and two grounded resistors for realizing first-order all-pass filters, and two grounded capacitors and two resistors for realizing second-order all-pass/notch filters. High input impedance and low output impedance of the configuration enable the circuits to be cascaded without additional buffers. As an application, a quadrature oscillator is realized. The theoretical results are verified with PSPICE simulations using 0.5 μm CMOS parameters.
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Jeong, Yongchae, Girdhari Chaudhary, and Phirun Kim. "Frequency Selective Impedance Transformer With High-Impedance Transforming Ratio and Extremely High/Low Termination Impedances." IEEE Transactions on Circuits and Systems I: Regular Papers 68, no. 6 (June 2021): 2382–92. http://dx.doi.org/10.1109/tcsi.2021.3063352.
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Wu, Hao, Shu Li, Yingpin Chen, and Zhenming Peng. "Seismic impedance inversion using second-order overlapping group sparsity with A-ADMM." Journal of Geophysics and Engineering 17, no. 1 (November 22, 2019): 97–116. http://dx.doi.org/10.1093/jge/gxz094.
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Abstract The anisotropic total variation with overlapping group sparsity (ATV_OGS) regularisation term is an improvement on the anisotropic total variation (ATV) regularisation term. It has been employed successfully in seismic impedance inversion as it can enhance the boundary information and relieve the staircase effect by exploring the structured sparsity of seismic impedance. However, because ATV_OGS constrains only the structured sparsity of the impedance's first-order difference and ignores the structured sparsity of the second-order difference, the staircase effect still occurs in an inversion result based on ATV_OGS. To further fit the structured sparsity of the impedance's second-order gradients, we introduce the overlapping group sparsity into the second-order difference of the impedance and propose a novel second-order ATV with overlapping group sparsity (SATV_OGS) seismic impedance inversion method. The proposed method reduces the interference of the large amplitude noise and further mitigates the staircase effect of the ATV_OGS. Furthermore, the accelerated alternating direction method of multipliers (A-ADMM) framework applied to this novel method. It can increase the efficiency of inversion. The experiments are carried out on a general model data and field data. Based on the experimental results, the proposed method can obtain higher resolution impedance than some impedance inversion methods based on total variation.
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Fouda, M. E., A. S. Elwakil, A. G. Radwan, and B. J. Maundy. "Fractional-Order Two-Port Networks." Mathematical Problems in Engineering 2016 (2016): 1–5. http://dx.doi.org/10.1155/2016/5976301.
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We introduce the concept of fractional-order two-port networks with particular focus on impedance and admittance parameters. We show how to transform a2×2impedance matrix with fractional-order impedance elements into an equivalent matrix with all elements represented by integer-order impedances; yet the matrix rose to a fractional-order power. Some examples are given.
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Wulandari, Darmawati, Ahmad Zarkasi, and Kholis Nurhanafi. "IMPEDANCE ANALYSIS FOR FOUR TYPES OF MINERAL WATER AND AQUADES USING ELECTRICAL IMPEDANCE SPECTROSCOPY (EIS) AT FREQUENCIES OF 1 Hz - 50 kHz." Indonesian Physical Review 7, no. 1 (December 26, 2023): 84–94. http://dx.doi.org/10.29303/ipr.v7i1.269.
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The Electrical Impedance Spectroscopy (EIS) method can be used to identify minerals in mineral water. The EIS method measures the impedance of a material by injecting alternating current in a certain frequency range, which is non-invasive and non-destructive. This study aims to analyze the impedance of mineral water and aquades based on the influence of the dissolved content using EIS equipment that provides flexibility in adjusting the desired frequency spectrum. The study used a frequency range from 1 Hz to 50 kHz with a four-electrode configuration. The measurement graph results were analyzed using Bode graph with impedance plot and phase shift angle to determine the impedance characteristics of mineral water. Equivalent circuit modeling helped to identify the electrochemical properties of materials such as the Warburg circuit, Constant Phase Element (CPE), and Randles circuit. The results show that the aquades has a higher impedance compared to the four mineral waters. Additionally, the four mineral waters exhibit varying impedances, attributed to their respective mineral content. Mineral water is characterized by an impedance that is dominated by Warburg impedance (Zw) at low frequencies, charge transfer resistance (Rct) and double layer capacitance (Cdl) at middle frequencies, and electrolyte resistance at high frequencies. However, the impedance of aquades dominated by electrolyte resistance (Re) at low frequency and Re+Rct at high frequency.
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Yang, Eunjin, Jiwan Kim, and Wonju Jeon. "Noise reduction in an open structure by tailoring complex impedances on acoustic metasurfaces." Journal of the Acoustical Society of America 154, no. 4_supplement (October 1, 2023): A156. http://dx.doi.org/10.1121/10.0023110.
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In this study, we design acoustic metasurfaces to the inner surfaces of the open structure to mitigate noise emanating through the opening by manipulating complex impedances along unit cells called impedance tiles. The impedance tile is comprised of subwavelength Helmholtz resonators, which have a theoretical model that accurately predicts the effective impedance, considering visco-thermal losses in narrow orifices. By adjusting thegeometrical parameters of these resonators, the surface impedance of the impedance tiles can be finely tuned to minimize noise escaping from the open structure at any desired target frequency. To evaluate the noise reduction performance, the designed metasurfaces were fabricated via 3D printing, and the sound pressure levels (SPLs) were measured before and after applying the metasurfaces inside the open structure. The experimental results show that the λ/31-thick metasurfaces achieve SPL reduction exceeding 12.6 dB at the target frequency of 360 Hz.
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Serrano, L., and A. Carlosena. "GB-R impedances: new approach to impedance simulation." Electronics Letters 31, no. 9 (1995): 689. http://dx.doi.org/10.1049/el:19950490.
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Zhang, Y., and J. L. Liu. "Impedance matching condition analysis of the multi-filar tape-helix Blumlein PFL with discontinuous dielectrics." Laser and Particle Beams 30, no. 4 (October 16, 2012): 639–50. http://dx.doi.org/10.1017/s026303461200050x.
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AbstractIn this paper, the characteristic impedance matching of the inner line and outer line of the multi-filar tape-helix Blumlein pulse forming line (BPFL) is analyzed in detail by dispersion theory of tape helix. Analysis of the spatial harmonics of multi-filar tape-helix BPFL shows that the integer harmonic numbers of the excited spatial harmonics are not continuous. In addition, the basic harmonic component still dominates the dispersion characteristics of the multi-filar tape-helix BPFL at low frequency band. The impedance mismatching phenomenon caused by the discontinuity of filling dielectrics in the inner line of BPFL is studied as an important issue. Effects of dielectric discontinuity on the coupled electromagnetic fields and the parameters of the outer line are also analyzed. The impedance matching conditions are both obtained under the situations of continuous filling dielectric and discontinuous dielectrics, respectively. Impedance characteristics of these two situations are analyzed by comparison, and effects of the thickness of support dielectric on the impedance are also presented. When the 6 mm-thickness nylon support of the multi-filar tape helix is used in the filling dielectric of de-ionized water, the characteristic impedances of the inner line and outer line of BPFL are 53 Ω and 14.7 Ω, respectively. After the improvement about substituting de-ionized water by castor oil, the relative permittivities of the support dielectric and filling dielectric are almost the same, and the impedances of the inner and outer line of BPFL become 80 Ω and 79 Ω, respectively. That is to say, the impedance mismatching problem caused by dielectric discontinuity is solved. Circuit simulation and experimental results basically correspond to the theoretical results, and the fact demonstrates that impedance analysis of the multi-filar tape-helix BPFL based on dispersion theory is correct.
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Grivelet, Pierre A. "Inversion of vertical seismic profiles by iterative modeling." GEOPHYSICS 50, no. 6 (June 1985): 924–30. http://dx.doi.org/10.1190/1.1441971.
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I present an application of iterative modeling to the inversion of vertical seismic profiles (VSPs). This method is derived from linear inversion which allows the extraction from VSP data of an impedance profile as a function of time and thus permits the prediction of impedance ahead of the drill bit. There are two steps in this process: first, detection of the major events on the seismogram which is achieved by a recursive detection algorithm; and second, an optimal estimate of the impedances carried out by a gradient algorithm. Seismic data are band‐limited, and consequently the solution of the inversion is nonunique. This nonuniqueness is handled by assuming a piecewise‐constant or blocked impedance model and by adding a priori constraints. Some synthetic examples are used to illustrate the method, and a field example shows a comparison between an impedance profile extracted from VSP data with this inversion method and an impedance profile from well logging data. In this example the accurate prediction of impedance values illustrates the usefulness of the method.
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Melnyk, V. G., P. I. Borshchov, O. D. Vasylenko, O. L. Lameko, and S. V. Dzyadevyc. "DETERMINATION OF FARADAY IMPEDANCE PARAMETERS TO INCREASE ACCURACY IN CONDUCTOMETRY AND OBTAIN ADDITIONAL DATA." Sensor Electronics and Microsystem Technologies 19, no. 3 (October 18, 2022): 38–52. http://dx.doi.org/10.18524/1815-7459.2022.3.265297.
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A simple algorithm for determining the set of parameters of the equivalent circuits of the impedance of a planar conductometric transducer with an interdigital comb topology, consisting of interelectrode and Faraday impedances is proposed. The frequency characteristics of the impedance parameters of the transducer samples and the electrical equivalent with averaged values of the parameters have been studied. A technique for determining the parameters of a three-element equivalent circuit, including solution resistance, double layer capacitance, and charge transfer resistance, has been developed and tested on a series of transducer samples. The optimal operating frequencies of the impedance-measuring channel are determined, and its schemes are developed. A technique for estimating the parameters of the Warburg impedance of transducer samples is demonstrated. The results obtained in the work make it possible to determine the optimal operating frequency range of biosensor systems and reduce errors from the influence of the Faraday impedance. The possibility of extending the functions of such transducers by using the near-electrode layer impedance parameters as informative ones is shown.
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Jia, Shan Jie. "Measurement of Harmonic Impedances of Supply Systems Using Natural Disturbances." Advanced Materials Research 354-355 (October 2011): 1321–28. http://dx.doi.org/10.4028/www.scientific.net/amr.354-355.1321.
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This paper presents a novel and practical method for monitoring harmonic impedances of power systems seen at load serving substations. The method uses the natural load fluctuations measured at the substation for impedance estimation. It avoids the needs for intrusive disturbances and can be used for online tracking of impedance parameters. The method has been verified through several real field measurements.
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Rose, W. C., and A. A. Shoukas. "Two-port analysis of systemic venous and arterial impedances." American Journal of Physiology-Heart and Circulatory Physiology 265, no. 5 (November 1, 1993): H1577—H1587. http://dx.doi.org/10.1152/ajpheart.1993.265.5.h1577.
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Hemodynamic properties of the systemic vasculature were measured in eight anesthetized dogs using two-port impedance analysis. Blood pressures and flows were measured at the aortic root and the caval-atrial junction. Impedances were computed from 0.05 to 20 Hz to characterize the systemic vasculature. Pseudorandom variations in flow were produced with an extracorporeal perfusion system. Impedance measurements were made at carotid baroreceptor pressures of 50, 125, and 200 mmHg. A six-parameter lumped-element model best fitted the measured impedance spectra. At 125 mmHg, the mean parameter values were venous inertance, 13.5 g.kg.cm-4; venous and arterial compliances, 0.769 and 0.0214 ml.mmHg-1.kg-1; venous and arterial characteristic impedances, 0.028 and 0.084 mmHg.kg.min.ml-1; and arterial-to-venous small-vessel resistance, 0.706 mmHg.kg.min.ml-1. Regression analysis showed significant dependence of small-vessel resistance on baroreceptor pressure. The other parameters were not dependent on carotid sinus pressure, which is consistent with baroreflex control of venous unstressed volume but not compliance. We conclude that two-port impedance analysis is a useful tool for studying venous hemodynamics and the dynamic coupling between the veins and the right heart.
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Kalinin, Sergei V., and Dawn A. Bonnell. "Scanning Impedance Microscopy: From Impedance Spectra to Impedance Images." Microscopy Today 10, no. 1 (February 2002): 22–27. http://dx.doi.org/10.1017/s1551929500050471.
Full textAbstract:
The properties and performance of electronic devices are crucially dependent on interface-related phenomena. The presence of interfaces can enable electronic device functionality (p-n diodes, solar cells); alternatively, non-functional interfaces can degrade device performance (ohmic vs. non-ohmic contacts). The most versatile tools for semiconductor interface characterization are ac (impedance spectroscopy, C-V) and dc (I-V) transport measurements. However, due to the lack of spatial resolution, these methods often cannot separate the contributions from electroactive interfaces and contacts. This is especially true for the non-traditional electronic materials such as semiconductive oxides, nitrides, conductive polymers, etc. Combined with the tendency towards miniaturization of electronic devices, this clearly necessitates spatially resolved ac and dc transport measurements.