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A motion characteristics modeled angular position sensor by nonlinear transfer of differential Capacitance for miniaturized scanning mirrors

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Microsystems & Nanoengineering 2023年第6期9卷 129-147页

作者： Songtao Liu Gaofei Zhang Lingyun Zhang Junya Wang Minghao Gong Zheng You Department of Precision Instrument Tsinghua UniversityBejing 100084China Key Laboratory of Smart Microsystem(Tsinghua University) Ministry of EducationBeijing 100084China State Key Laboratory of Precision Measurement Technology and Instruments Tsinghua UniversityBeijing 100084China School of Mechanical Science&Engineer Huazhong University of Science and TechnologyWuhan 430074China

In this paper,an angular position sensor(APS)designed for a resonant miniaturized scanning mirror(M-SM)is presented.The APS operates based on the principle of differential variable Capacitance,significantly expanding the detectable bandwidth from a few hertz to several kilohertz.By modeling the motion characteristics,the sampling rates of the biaxial scanning angles are 1473.6 times and 539.4 times higher than those of conventional sensors.Initially,the motion characteristics model is presented as a simple harmonic motion,converting sampled Capacitance into continuous Capacitance.Subsequently,the nonparallel state of the M-SM and sensor is transformed into a parallel state through the space coordinate system transformation.Furthermore,a 2D nonlinear angle transfer function is developed to convert the differential Capacitance into an angle,thereby mitigating the nonlinear errors resulting from large angles.Achieving an accuracy better than 0.014°,the measuring range expands from±0.5729°(±10 mrad)to±5.026°(±87 mrad).Additionally,the capturing mode and tracking mode are proposed to monitor real-time angular changes of the M-SM with an accuracy of 0.017°.High-precision APSs have enhanced beam pointing accuracy and resolution and can thereby be used to advance the development of laser components,including light detection and ranging(LiDAR).

关键词： Capacitance angular nonlinear

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Investigation of replacing tracer flooding analysis by Capacitance resistance model to estimate interwell connectivity

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Petroleum 2023年第1期9卷 61-71页

作者： Adilet Aliyev Davood Zivar Peyman Pourafshary School of Mining and Geosciences Nazarbayev UniversityAstanaKazakhstan PanTerra Geoconsultants B.V LeiderdorpNetherlands

Interwell connectivity is an essential parameter for managing waterflooding operations in a field.Analysis of the tracer injection operation is a well-known approach to studying injected fluids distribution in a reservoir and toward producer wells.Developed in the early 2000s,Capacitance-resistance model(CRM)is an analytical approach for waterflooding modeling and optimization.Production/injection data are used as input to model the mass balance and estimate parameters such as the interwell connectivity.In this work,we investigated the accuracy of applying the Capacitance-resistance model to mimic a tracer test.Such an approach helps assess the connection between the wells and decide on further field development steps cheaper and quicker.Connectivity values estimated by tracer tests and CRM were analyzed and compared for synthetic and real fields.CRM was capable of modeling waterflooding and estimating production in both fields with acceptable accuracy.Parameters such as well spacing and fluid loss during the injection were considered to improve the accuracy of the CRM approach to calculate the interwell connectivity between injector/producer pairs.Our study showed that CRM could serve as a tool for a quick approximate estimation of interwell connectivity under certain assumptions and is recommended as a replacement for tracer flooding analysis,where the tracer test is not possible or is expensive.

关键词： connectivity Capacitance analysis

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Theoretical connection from the dielectric constant of films to the Capacitance of capacitors under high temperature

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High Voltage 2023年第4期8卷 707-716页

作者： Yongxin Zhang Qikun Feng Shaolong Zhong Jiayao Pei Fangyi Chen Lei Huang Zhe Yang Zhimin Dang Department of Electrical Engineering Tsinghua UniversityBeijingChina Department of Electrical and Computer Engineering Carnegie Mellon UniversityPittsburghPennsylvaniaUSA Department of Energy Technology Aalborg UniversityAalborgDenmark

In the process of coping with energy and environmental protection issues,technologies such as energy materials,energy devices,and energy systems have made great progress.With excellent performance,film capacitors play an increasingly important role in energyrelated fields.With the increase of application scenarios and the continuous development of film material technology,it is urgent to establish a better theoretical connection from films to capacitors.First,the main components of the capacitor including the film and the positional relationships among them are given.Then,from the two perspectives of indirect calculation according to the volume and the direct calculation according to the winding process,the equation between the dielectric constant of films and the corresponding Capacitance of capacitors is established.Further,the measurement data and error analysis results of the built test platform prove the accuracy and great potential of the proposed calculation methods.In addition,error sources,including film thickness uniformity,are listed.Finally,the challenges faced by the proposed calculation methods and the paths that can be referenced for future research are summarised and discussed.

关键词： film dielectric Capacitance

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A side-effect-free method of reducing Capacitance requirement for modular multilevel converters

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High Voltage 2022年第3期7卷 461-472页

作者： Zhijie Liu Kejun Li Jinyu Wang Liangzi Li School of Electrical Engineering Shandong UniversityJinanChina School of Electrical Engineering Xi'an Jiaotong UniversityXi'anChina

In modular multilevel converters(MMCs),the huge capacitor almost takes over half of the cost and weight of a submodule;as a result,the Capacitance requirement reduction has attracted wide attention for using smaller capacitors.However,the existing methods have side effects,such as increasing the arm current and adding additional semi-conductors,which restrict their practical applications.Thus,a side-effect-free Capacitance requirement reduction(CRR)method is proposed in this paper.In the method,the capacitor voltage can be decreased by injecting a specific dc signal into the original control system;and the specific dc signal is outputted from the proposed CRR controller according to the transmitted power of the MMC.For ensuring the safe operation,the extent to which the capacitor voltage can be reduced is also studied;and an optimisation model is presented to obtain the minimum allowed capacitor voltage and the safety domain of CRR.The effectiveness of the proposed method is proved by both simulation and experiment.The results show that the Capacitance requirement can be reduced by 32.4%without neither increasing the arm current nor adding additional semiconductors.

关键词： Capacitance requirement effect

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Enhancing Capacitance Performance of Ti3C2Tx MXene as Electrode Materials of Supercapacitor: From Controlled Preparation to Composite Structure Construction

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Nano-Micro Letters 2020年第6期12卷 152-175页

作者： Xiaobei Zang Jiali Wang Yijiang Qin Teng Wang Chengpeng He Qingguo Shao Hongwei Zhu Ning Cao School of Materials Science and Engineering China University of Petroleum(East China)Qingdao 266580People’s Republic of China School of Materials Science and Engineering Tsinghua UniversityBeijing 100084People’s Republic of China

Ti3C2Tx,a novel two-dimensional layer material,is widely used as electrode materials of supercapacitor due to its good metal conductivity,redox reaction active surface,and so on.However,there are many challenges to be addressed which impede Ti3C2Tx obtaining the ideal specific Capacitance,such as restacking,re-crushing,and oxidation of titanium.Recently,many advances have been proposed to enhance Capacitance performance of Ti3C2Tx.In this review,recent strategies for improving specific Capacitance are summarized and compared,for example,film formation,surface modification,and composite method.Furthermore,in order to comprehend the mechanism of those efforts,this review analyzes the energy storage performance in different electrolytes and influencing factors.This review is expected to predict redouble research direction of Ti3C2Tx materials in supercapacitors.

关键词： Ti3C2Tx MXene Capacitance performance Storage mechanism Electrode materials Supercapacitor

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Self-sensing concrete:from resistance-based sensing to Capacitance-based sensing

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International Journal of Smart and Nano Materials 2021年第1期12卷 1-19页

作者： D.D.L.Chung Composite Materials Research Laboratory Department of Mechanical and Aerospace EngineeringUniversity at Buffalothe State University of New YorkBuffaloNYUSA

Self-sensing uses the cement-based material without sensor incor-poration to sense itself.This paper reviews self-sensing cementbased materials,with coverage of the well-studied resistance-based sensing as well as the less-studied Capacitance-based sensing.This review is the first that covers Capacitance-based self-sensing.Capacitance-based sensing is advantageous over resistance-based sensing in that no particular admixture is required,so that it is applicable to both existing and new structures.In contrast,resis-tancebased sensing that is comparable to Capacitance-based sen-sing in stress/strain sensitivity requires conductive admixtures,such as carbon fiber.Resistance-based strain sensing is based on piezo-resistivity,which is associated with the resistance increasing upon tension and decreasing upon compression.Capacitance-based strain sensing is based on piezopermittivity,which is associated with the permittivity decreasing upon tension and increasing upon compression.Damage causes the resistance to increase and causes the permittivity to decrease.Increase in temperature decreases the resistance but increases the permittivity.This review also covers the methodology of the electrical measurements.

关键词： Cement concrete sensing resistance Capacitance

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Visualization of flow structures inside a conical spouted bed by electrical Capacitance volume tomography

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Particuology 2019年第1期17卷 15-25页

作者： Hoon Chae Park Hang Seok Choi Department of Environmental Engineering Yonsei UniversityWonju 26493Republic of Korea

Electrical Capacitance volume tomography (ECVT) was conducted to measure instantaneous gas–solid flow structures in a conical spouted bed. The sensor has 24 electrodes/channels and was used to make three-dimensional measurements of the solid volume fraction. Flow structures in the conical spouted bed were analyzed using quantitative ECVT images. Three-dimensional images of gas–solid flow structures and time-averaged vertical and radial solid volume fraction profiles are presented. Different fluidization regimes in spouted beds were characterized by analyzing pressure fluctuation signals and ECVT images. ECVT was shown to be robust and powerful for the three-dimensional visualization and quantitative measurement of a gas–solid fluidization system.

关键词： Conical spouted bed Electrical Capacitance volume tomography Multiphase flow

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Elegant procedure to estimate series Capacitance of a uniform transformer winding from its measured FRA:implementable on existing FRA instruments

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High Voltage 2020年第4期5卷 444-453页

作者： Ashiq Muhammed Lakshminarayana Satish Udaya Kumar HV Laboratory Department of Electrical EngineeringIndian Institute of ScienceBangalore 560012India

A simple procedure to estimate series Capacitance of a uniform transformer winding from its measured frequency response analysis(FRA)and shunt Capacitance is presented.Unlike previously published approaches,this method does not involve any cumbersome and time-consuming curve-fitting nor running optimisation/search algorithms,and neither does it require data of winding geometry.The procedure relies on a property that is observable in the impedance function of a lossless winding,viz.,the ratio of the product of squares of open circuit natural frequencies to the product of squares of short circuit natural frequencies bears a special relation to impedance function coefficients.Its feasibility was initially verified by simulation,and then by experiments on small-sized continuous-disk and interleaved-disc windings,followed by a large-sized 33 kV,3.5 MVA continuous-disc winding,and finally on a 315 kVA 11/13.8 kV transformer.After measuring FRA,the process involves just finding roots of a polynomial,from which the initial impulse voltage distribution constant and series Capacitance can directly be determined.Given these attractive features,authors believe that this method is implementable on existing FRA instruments,so that,along with routinely measured FRA,these two important constants of a winding can be displayed.

关键词： Capacitance sized uniform

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Dominant role of wettability in improving the specific Capacitance

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Green Energy & Environment 2019年第2期4卷 171-179页

作者： Tongtong Liu Kai Wang Yongxiu Chen Shuangliang Zhao Yongsheng Han State Key Laboratory of Multiphase Complex Systems Institute of Process Engineering Chinese Academy of Sciences School of Chemical Engineering University of Chinese Academy of Sciences State Key Laboratory of Chemical Engineering and School of Chemical Engineering East China University of Science and Technology

Here we report a strategy to enhance the energy density of supercapacitors by increasing the utilization rate of the specific surface area(SSA)via wettability improvement. The nonporous gold(NPG) film is used as the electrodes and the ionic liquid [EMIM]BF4 is the electrolyte. When the electrode is coated by paraffin, an increase of the contact angle leads to a remarkable reduction of the specific Capacitance. While when acetonitrile is added into the electrolyte, the contact angle is decreased and the utilization rate of SSA is improved, which results in an increase of the specific Capacitance. The addition of isopropyl acetate into the electrolyte leads to a further increase of the specific Capacitance. To generalize the role of the wettability in improving the energy density, a carbon-based electrode is evaluated in the solution of potassium hydroxide. An addition of propyl alcohol into the potassium hydroxide solution leads to an increase of the specific Capacitance, as well as a long-term stability of the supercapacitor. The role of conductivity in this study is excluded by designing experiments. This paper highlights the significance of wettability in determining the specific Capacitance, showing an alternative to improve the energy density of supercapacitors.

关键词： Supercapacitor Energy density Specific Capacitance Effective surface area Wettability

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Strain control of layer-resolved negative Capacitance in superlattices

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npj Computational Materials 2020年第1期6卷 127-130页

作者： Raymond Walter Sergey Prosandeev Charles Paillard L.Bellaiche Department of Physics and Institute for Nanoscience and Engineering University of ArkansasFayettevilleAR 72701USA Department of Mathematical Sciences University of ArkansasFayettevilleAR 72701USA Identity Engineering Kinesso LLCConwayAR 72032USA Institute of Physics and Physics Department of Southern Federal University Rostov-na-Donu 344090Russia Laboratoire Structures Propriétés et Modélisation des SolidesCentraleSupélecUMR CNRS 8580UniversitéParis-Saclay91190 Gif-sur-YvetteFrance

Negative Capacitance in BaTiO_(3)/SrTiO_(3) superlattices is investigated by Monte Carlo simulations in an atomistic effective Hamiltonian model,using fluctuation formulas for responses to the local macroscopic field that incorporates depolarizing fields.We show that epitaxial strain can tune the negative Capacitance of the BaTiO_(3) ferroelectric layer and the overall Capacitance of the system.In addition,we predict and explain an original switching of the negative Capacitance from the BaTiO3 layer to the SrTiO_(3) layer at low temperatures for intermediate strains.

关键词： Capacitance layer resolved

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