Voltage Wave Research Articles

Simultaneously Enhanced Thermal Conductivity and Breakdown Performance of Micro/Nano-BN Co-Doped Epoxy Composites.

Micro/nano- BN co-doped epoxy composites were prepared and their thermal conductivity, breakdown strength at power frequency and voltage endurance time under high frequency bipolar square wave voltage were investigated. The thermal conductivity and breakdown performance were enhanced simultaneously in the composite with a loading concentration of 20 wt% BN at a micro/nano proportion of 95/5. The breakdown strength of 132 kV/mm at power frequency, the thermal conductivity of 0.81 W·m−1·K−1 and voltage endurance time of 166 s were obtained in the composites, which were approximately 28%, 286% and 349% higher than that of pristine epoxy resin. It is proposed that thermal conductive pathways are mainly constructed by micro-BN, leading to improved thermal conductivity and voltage endurance time. A model was introduced to illustrate the enhancement of the breakdown strength. The epoxy composites with high thermal conductivity and excellent breakdown performance could be feasible for insulating materials in high-frequency devices.

Thermal Analyses of Reactor under High-Power and High-Frequency Square Wave Voltage Based on Improved Thermal Network Model

In order to quickly calculate the stable temperature of a reactor driven by high-frequency and high-power pulse voltage, an improved thermal network model suitable for a reactor under this condition is established in this paper. In power electronic equipment, the maximum temperature of the reactor is usually concentrated in its internal core. Moreover, with the increasing demand of high-power density in power electronic devices, the structure design of the reactor is more compact, and the internal magnetic field will affect the accuracy of the temperature-measuring device. Therefore, it is difficult to measure the internal temperature rise of the reactor directly. However, its stable operating temperature could be analyzed by the thermal network modeling methods and heat transfer analysis tool. Therefore, a convenient and accurate thermal network model of the reactor under high-frequency and high-power square wave voltage is established by considering the equivalent thermal resistance of the winding, the three-dimensional geometrical effect of the core and the effect of the high-frequency repeated pulse stress on the thermal penetration depth. Additionally, the internal temperature of the reactor can be obtained through the external temperature in terms of the presented model. To verify the feasibility of the thermal network model, the corresponding multiphysical field finite element simulation and the reactor temperature measurement platform is built. The simulation and experimental results show that the proposed thermal network model has a high precision and fast calculation speed, and it is an effective tool for thermal analysis of the reactor.

Effect of Bipolar Square Wave Voltage with Varied Frequencies on Electrical Tree Growth in Epoxy Resin

An electrical tree in epoxy resin induced by a bipolar square wave voltage at varied frequencies has been investigated. The morphology, growing characteristics, fractal dimension, and initiation proportion of anelectrical tree at 10 kV for a frequency ranging from 50 Hz to 20 kHz was studied. The results show that electrical trees are all branch-like in epoxy resin. It was revealed that there are three regions in the propagation of an electrical tree: 50 Hz~2 kHz (region A), 2~4 kHz (region B), and 4~20 kHz (region C). When imposed frequencies are increased from 50 Hz to 20 kHz, the number of tree branches, growing rate, and initiation proportion increase in region A; the number of tree branches and initiation proportion increase, while the growing rate decreases, in region B; and the growing rate and initiation proportion increase while the number of tree branches decrease in region C. The electrical tree length and width increase linearly with treeing time when frequencies were lower than 2 kHz, while increasing exponentially with treeing time when frequencies are higher than 4 kHz. The dielectric power loss of epoxy resin under varied frequencies is computed by an expansion in Fourier series, and the results indicate that the dielectric power loss increases with increasing frequency. The characteristics of an electrical tree are ascribed to a synergistic effect of the dielectric power loss of epoxy resin, space charge, and partial discharge under a bipolar square wave field.

Application of surface acoustic wave to enhance the photocatalytic degradation efficiency of methylene blue

The TiO2 thin film was grown on a [Formula: see text] Y-axis cut, X-axis propagation lithium niobate substrate by radio frequency magnetron sputtering to fabricate a surface acoustic wave device. The sputtering ratios of argon to oxygen at 20% and post-annealing temperature at [Formula: see text]C for 3 h were controlled to improve the photocatalytic activity of TiO2 thin film. The effects of work frequency and input voltage of the surface acoustic wave device on the methylene blue photocatalytic degradation efficiency of the TiO2 thin film were investigated. The TiO2 thin film was vibrated at radio frequency by surface acoustic wave device to increase the scattering and reactive frequency for methylene blue in liquid. The surface acoustic wave device operated at 28.65 MHz work frequency and 0.95 V input voltage revealed the highest photocatalytic degradation efficiency of methylene blue. Compared to the TiO2 thin film combined with and without surface acoustic wave device, the surface acoustic wave device enhanced the TiO2 thin film photocatalytic degradation efficiency to 46%.

P Wave Duration/P Wave Voltage Ratio Plays a Promising Role in the Prediction of Atrial Fibrillation: A New Player in the Game.

Background Atrial fibrillation (AF) is the most common sustained arrhythmia in clinical practice. Identification of patients at risk for developing AF and the opportunity for early targeted intervention might have a significant impact on morbidity and mortality. Prolonged P wave duration and decreased P wave voltage have been shown to be independent predictors of AF. The present study aimed to investigate the role of P wave duration/P wave voltage in predicting new-onset AF. Methods We screened a total of 640 consecutive patients who admitted to cardiology outpatient clinic with a complaint of palpitation between 2012 and 2014. 24-h Holter monitoring, echocardiography, and electrocardiography (ECG) recordings were reviewed to identify new-onset AF. Patients were assigned into two groups based on presence (n = 150) and absence (n = 490) of new-onset AF. Previous ECGs with sinus rhythm were analyzed. P wave duration was measured in inferior leads, and P wave voltage was measured in lead one. P wave duration/P wave voltage was also calculated for each patient. Results One hundred fifty subjects (23.4%) had new-onset AF among 640 patients. P wave duration (123.27 ± 12.87 vs. 119.33 ± 17.39 ms, p=0.024) and P wave duration/P wave voltage (1284.70 ± 508.03 vs. 924.14 ± 462.06 ms/mV, p < 0.001) were higher, and P wave voltage (0.12 ± 0.04 vs. 0.13 ± 0.04 mV, p < 0.001) was significantly lower in the new-onset AF group compared with non-AFs. P wave duration/P wave voltage, with a cut off of 854.5 ms/mV, had 83.3% sensitivity and 62.0% specificity in a receiver operating characteristic curve (AUC 0.728, 95% CI 0.687–0.769; p < 0.001). Their negative and positive predictive values were 78.7% and 68.6%, respectively. In a univariate regression analysis, age, smoking, C-reactive protein, brain natriuretic peptide, left atrial diameter, left atrial volume index, P wave duration, P wave voltage, and P wave duration/P wave voltage were significantly associated with the development of new-onset AF. Moreover, smoking (OR 4.008, 95% CI 1.707–9.409; p=0.001), left atrial volume index (OR 7.108, 95% CI 4.400–11.483; p < 0.001), and P wave duration/P wave voltage (OR 1.002, 95% CI 1.000–1.003; p=0.044) were found to be significant independent predictors of new-onset AF in a multivariate analysis, after adjusting for other risk parameters. Conclusion The P wave duration/P wave voltage ratio is a practical, easy-to-use, cheap, and reliable electrocardiographic parameter, which can play a promising role for both in predicting and elucidating a mechanism of new-onset AF.

ДОСЛІДЖЕННЯ ПЕРЕНАПРУГИ В ЕЛЕКТРИЧНИХ МЕРЕЖАХ.

The paper considers the processes that occur in power lines and power transformers at atmospheric and switching overvoltages. Atmospheric overvoltages are divided into two types: direct, which occur due to a direct lightning strike; and induction - occur at any switching. Direct overvoltages reach values sufficient to cover the insulation of any voltage class. Protection of power transmission lines from them - suspension of grounded lightning protection cables, protection of substation equipment - installation of lightning rods. It is important to study the wave processes in power lines that occur when switching, which occurs when the power supply is turned on, when disconnected from the power supply, in the event of short circuits, when power lines are struck by lightning. In addition, it is important to study the wave processes in power transformers, the effect of the pulse corona, the effect of overvoltage on the transformer windings. In a more detailed analysis of the processes, the following conclusions were made: 1) under the condition of the same mains voltage, the voltage wave will be higher in the cable transmission line than in the air, due to the difference in impedance. 2) in the XX mode, the load current will drop to zero, and the load voltage will double. The voltage of the reflected wave will keep the sign. In short-circuit mode, the load voltage will drop to zero and the load current will double. The voltage of the reflected wave will change the sign. Thus, when the substation equipment is under a voltage close to XX, there is a probability of equipment damage during atmospheric overvoltages. 3) For substations that are powered by overhead power lines, it is advisable to use a tank to smooth the slope of the refracted wave, and for substations that are powered by cable transmission lines, it is advisable to use inductance to smooth the slope of the refracted wave. 4) Inductance and capacitance can have a significant effect on the amplitude of the voltage wave, provided that. 5) Capacitance performs protective functions in all directions, both refracted and reflected wave, and inductance only smooths the refracted wave. The obtained relations can be used to study the overvoltage in the connection nodes of node substations.

Analysis of Electrocardiogram Indicators of Cows with Myocardial Dystrophy in Postpartum Period

The study of the myocardium state of cattle with the usage of electrocardiography makes it possible to diagnose many types of cardiac pathologies. This helps to select the optimal treatment and prevent loss of animal productivity. The purpose of the research is to study the features of the electrocardiogram (ECG) of cows with myocardial dystrophy during the postpartum period. The studies were conducted in “Gridino” - agricultural production cooperative in Kostroma region, on highly productive clinically healthy (n=5) cows and cows with the clinical symptoms of the myocardiodystrophy (n=15), both groups were of Kostroma breed, 20 days after calving (3-4 lactation). ECG traces were recorded in six cardiographic leads: three standard and three augmented leads (aVR, aVL, aVF) via veterinary electrocardiograph “Poly-Spectrum-8/B” (Russia). Animals were in a freestanding position, the leads were traced using clamp electrodes, which were fixed to the skin on the left and right side of the chest and pelvic limbs according to the standard technique. For the ECG analysis, the amplitude (mV) and the directions of the P, Q, R, S, T waves were considered as well as the duration of the P wave and the intervals P-Q, R-R, Q-T (ms). It was found that for clinically healthy cows the length of the P wave was 71,8±1,9 ms, and for others with the symptoms of the myocardiodystrophy it was 9,5% more. The P-R interval of clinically healthy animals lasted 181,2±8,0 ms, while the one of sick cows was 12,6% less. The height of the clinically healthy cows P wave in leads I and II was 0,15±0,02 and 0,19±0,01 mV, respectively, while the voltage of the P wave of sick cows was 40% lower in lead I (P <0,05), and in II – by 21%. The clinically healthy cows had the Q wave voltage in the range from -0.08±0,01 to -0,12±0,01 mV, and the R wave voltage – from 0,24 ± 0,02 to 0,53 ± 0,04 mV. The cows with symptoms of myocardiodystrophy showed similar tendency, but in lead II the R wave was 47.2% less (P <0.01). Among the sick cows, the S wave was absent in lead I in 80.0% of cases, in lead II – absent at all, and in lead III it was not recorded in 60.0% of animals, the rest 40% had the wave -0,28±0,18 mV, which was 2 times deeper than one of clinically healthy animals. The T wave of all cows with symptoms of myocardial dystrophy was low and variable in the direction in lead I, and in lead II in 80% of cases it was 3 times less (P <0.05) than one of clinically healthy animals. In lead III, it was observed negative in 20.0% of cows, but its voltage was within the normal range, while in 60.0% of animals it was positive (0.10 ± 0.02 mV), and in 20.0 % - not registered. Thus, according to the results of electrocardiography, clinically healthy cows in the postpartum period showed signs of left atrial hypertrophy. The cows with symptoms of myocardial dystrophy detected violation of the myocardial contractility ad function of conductivity, a decrease in the voltage of the P, R, T waves and a reduction of the time of impulse conducting through the atria.

Multi-Frequency Multi-Amplitude Superposition Modulation Method With Phase Shift Optimization for Single Inverter of Wireless Power Transfer System

In wireless charging devices, different wireless charging standards have caused charging incompatibility, and the utilization rate of the DC voltage at the transmitter is not high, which brings challenges to the application of wireless charging. To solve these two problems, this paper proposes a multi-frequency multi-amplitude (MFMA) superimposition modulation method. This method superimposes multiple frequency signals, and then compares the synthesized signal with a high-frequency triangular carrier to output a square wave voltage signal containing information such as the frequency and amplitude of the pre-output signal. Furthermore, a phase-shifting optimization algorithm is proposed, i.e., based on the proposed MFMA superimposition modulation method, the utilization rate of the DC voltage of the system is improved by reasonably adjusting the initial phase of each frequency. Simulation and experimental results show that the proposed method can output at least four frequencies simultaneously by using a single inverter, effectively reducing the volume of the transmitter, and being compatible with the frequency range of several charging standards. The proposed phase-shifting optimization has a significant effect on improving the utilization of DC voltage with an increase of 44.88%.

A Genetic-Based Hybrid Algorithm Harmonic Minimization Method for Cascaded Multilevel Inverters with ANFIS Implementation

Selective harmonic elimination pulse-width modulation (SHEPWM) is a widely adopted method to eliminate harmonics in multilevel inverters, yet solving harmonic amplitude equations is both time consuming and not accurate. This method is applied here for a 7-level cascaded multilevel inverter (CMLI) with erroneous DC sources. To meet the seven harmonic amplitude equations, two notches are applied with the use of higher switching frequency than nominal. These notches can be placed in six different positions in the voltage wave, and each was assessed in a separate manner. In order to solve the equations, a hybrid algorithm composed of genetic algorithm (GA) and Newton–Raphson (N-R) algorithm is applied to achieve faster convergence and maintain the accuracy of stochastic methods. At each step of the modulation index (M), different positions for the notches are compared based on the distortion factor (DF2%) benchmark, and the position with lowest DF2% is selected to train an artificial neural fuzzy interface system (ANFIS). ANFIS will receive the DC sources’ voltages together with required M and will produce one output; thus, eight ANFISs are applied to produce seven firing angles, and the remaining one is to determine which one of the notches’ positions should be used. Software simulations and experimental results confirm the validity of this proposed method. The proposed method achieves THD 8.45% when M is equal to 0.8 and is capable of effectively eliminating all harmonics up to the 19th order.

Response Times of Metal-Oxide Chemiresistors: Comparison Between the Isothermal and Temperature Modulation Modes.

The response time is one of the main functional parameter for gas sensors, including metal oxide chemiresistors. This parameter is widely investigated for devices working in isothermal mode but it is much less investigated for gas sensors working in temperature modulation mode. In this work, considering ethanol as target gas, we compare the response times of a metal oxide chemiresistor working according to these two modes. In order to compare them, we worked with nearly the same average temperature in both cases, supplying a constant voltage to the heater in the isothermal mode and a squared voltage wave in temperature modulation. Our results show that, depending on the average working temperature, one mode or the other may be faster. At high average working temperature, the response time recorded with the isothermal mode is shorter than the thermal-period of the temperature modulation mode. Lowering the average working temperature, the response time increases for both modes, but the increase is more marked for the isothermal mode, which become slower than the temperature modulation one.

Electrophysiological and Pathological Impact of Medium-Dose External Carbon Ion and Proton Beam Radiation on the Left Ventricle in an Animal Model.

BackgroundMedium‐dose (25 gray) x‐ray radiation therapy has recently been performed on patients with refractory ventricular tachyarrhythmias. Unlike x‐ray, carbon ion and proton beam radiation can deliver most of their energy to the target tissues. This study investigated the electrophysiological and pathological changes caused by medium‐dose carbon ion and proton beam radiation in the left ventricle (LV).Methods and ResultsExternal beam radiation in the whole LV was performed in 32 rabbits. A total of 9 rabbits were not irradiated (control). At the 3‐month or 6‐month follow‐up, the animals underwent an open‐chest electrophysiological study and were euthanized for histological analyses. No acute death occurred. Significant LV dysfunction was not seen. The surface ECG revealed a significant reduction in the P and QRS wave voltages in the radiation groups. The electrophysiological study showed that the local conduction times in each LV site were significantly longer and that the local LV bipolar voltages were significantly lower in the radiation groups than in the control rabbits. Histologically, apoptosis, fibrotic changes, and a decrease in the expression of the connexin 43 protein were seen in the LV myocardium. These changes were obvious at 3 months, and the effects were sustained 6 months after radiation. No histological changes were seen in the coronary artery and esophagus, but partial radiation pneumonitis was observed.ConclusionsMedium‐dose carbon ion and proton beam radiation in the whole LV resulted in a significant electrophysiological disturbance and pathological changes in the myocardium. Radiation of the arrhythmogenic substrate would modify the electrical status and potentially induce the antiarrhythmic effect.

POTENTIAL ROLE OF GLP-1 RECEPTOR AGONIST IN A RAT MODEL OF CARDIO-RENAL SYNDROME TYPE-3: EFFECTS ON OXIDATIVE, INFLAMMATORY AND INOS EXPRESSION AXIS

Background: Acute renal and cardiac diseases are common encounters in hospitalized and non-hospitalized patients. Kidney and heart pathology are continuously interrelated. The impact of acute kidney injury (AKI) on the cardiac function is demonstrated in both preclinical and clinical studies and is termed cardio-renal syndrome type 3.Aim of the work: The aim of this work is to establish an animal model of cardio-renal syndrome type 3, and to study the effect of glucagon-like peptide-1 receptor (GLP-1R) agonist “liraglutide” on this condition.Materials and methods: Sixty male Wistar rats were used in this study and were divided into six groups (10 per group). Group 1: control, Group 2: low dose liraglutide-treated rats(L-lira). Group 3: high dose liraglutide-treated rats (H-lira). Group 4: Gentamicin (GM) treated rats. Group 5: low dose liraglutide- and GM-treated rats (L-lira-GM). Group 6: high dose liraglutide- and GM-treated rats (H-lira-GM). Liraglutide was given daily by subcutaneous injection for three weeks. GM was injected intraperitoneally (IP) starting from day 15 to day 21.Results: GM treatment was associated with histopathological injuries of both renal and cardiac tissues, in addition to significant elevation of renal biomarkers (serum urea and creatinine) as well as cardiac biomarkers (cardiac troponin I (TnI), creatine kinase (CK-MB) and lactate dehydrogenase (LDH). ECG showed prolongation of QRS complex, Q-T and Q-Tc interval, in addition to increased T wave voltage. There was significant increase in the relative weight of the right ventricle and the absolute and relative weights of left ventricles and the whole heart of the GM group. Moreover, GM injection resulted in a significant increase in oxidative and inflammatory markers (MDA, NO, IL-1beta, IL-6 and TNF-α) and diminished antioxidants GSH, SOD, and catalase, in the serum as well as in renal and cardiac tissues. GLP-1R agonist administration before GM injection normalized all the measured parameters only in the high dose group. Liraglutide evidently prevented upregulation of the inducible nitric oxide synthase (iNOS) gene expression in both renal and cardiac tissue of GM-treated animals.Conclusion: GM injected rats exhibited renal and cardiac structural and functional damage. The GLP-1R agonist, liraglutide protects both the kidney and the heart through antioxidant and anti-inflammatory effects. In addition, it downregulates the iNOS expression in renal and cardiac tissues, thus decreasing production of nitric oxide (NO).

Synchrophasors Point the Way: The Emergence of a New Technology

I was a test engineer in the laboratory Division at the Bonneville Power Administration (BPA) in 1987. They needed someone to design, implement, and conduct a field test of a new computer-based device that measured the phasor equivalent of voltage and current sine waves. Knowing little about the technology and method, I went to a project meeting where Prof. Arun Phadke from Virginia Tech (VT), the principal investigator and primary creator of the concept, was leading the planning.

On the soliton solutions for an intrinsic fractional discrete nonlinear electrical transmission line

This paper focuses on finding soliton solutions for an intrinsic fractional discrete nonlinear electrical transmission lattice. Our investigation is based on the fact that for a realistic system, the electrical characteristics of a capacitor (and an inductor via skin effect) should include a fractional-order time derivative. In this respect for the model under consideration, we derive a fractional nonlinear partial differential equation for the voltage dynamics by applying the Kirchhoff’s laws. It is realized that the behavior of new soliton solutions obtained is influenced by the fractional-order time derivative as well as the coupling values. The fractional order also modifies the propagation velocity of the voltage wave notwithstanding their structure and tends to set up localized structure for low coupling parameter values. However, for a high value of the coupling parameter, the fractional order is less seen on the shapes of the new solitary solutions that are analytically derived. Several methods such as the Kudryashov method, the $$(G'/G)$$ -expansion method, the Jacobi elliptical functions method and the Weierstrass elliptic function expansion method led us to derive these solitary solutions while using the modified Riemann–Liouville derivatives in addition to the fractional complex transform. An insight into the overall dynamics of our network is provided through the analysis of the phase portraits.

Study of long non-coding RNA and mitochondrial dysfunction in diabetic rats

Diabetes mellitus (DM) is a worldwide health problem. The Micro- and macro-vascular complications are the major causes of morbidity and mortality of DM. Molecular regulation of mitochondrial fission/fusion cycles is being studied, but the results were not conclusive. The aim of this study is to investigate the possible functional role of lncRNA H19 and its relation to mitofusin-2 (Mfn-2) gene expression in diabetic rats with cardiac and renal complications. Streptozotocin-induced diabetic male, albino rats and a matched control group were investigated. Cardiac weights, blood pressure and ECG were recorded. Biochemical evaluation of cardiac and renal functions was performed. Molecular determination of lncRNA H19 and Mfn-2 gene expression and histological examination by light and electron microscopy for cardiac and renal tissues were performed. Diabetic rats showed a significant increase of left ventricle weight/whole body weight ratio, R wave voltage, and a significant decrease of blood pressure, heart rate, and P wave voltage. At the molecular level, lncRNA H19 and Mfn-2 mRNA showed altered expression with a statistically significant downregulation of Mfn-2 mRNA expression in renal tissues. In conclusion, the changes in lncRNA H19 and Mfn-2 mRNA expression may help better understanding of the pathogenesis of cardiac and renal dysfunctions associated with type 1 DM.

Design of Z-Source Inverter-Based Dynamic Voltage Restorer Circuitry with R-SOGI Control Scheme for Enrichment of Power Quality

Increased utilization of nonlinear loads in the power distribution system with profound integration of renewable energy requires improved power quality control. This paper proposes a Reformed Second Order Generalized Integrated (R-SOGI) control scheme for enhancing the output of the Dynamic Voltage Restorer (DVR) for the objective of achieving the desired sinusoidal voltage wave shape at the common point of services and harmonic reduction. The DVR incorporates a Solar Photovoltaic (SPV) system using the Z-source Inverter (ZSI), providing the necessary active power to mitigate the voltage sag/swell and power demand. ZSI offers step-down as well as step-up abilities, it makes the converters to operate in the conditions of shoot-through. Therefore, the application of ZSI-based DVR topology seems very promising. The compensating reference voltage is generated by the R-SOGI algorithm, which offers superior output under conditions for grid voltage irregularities, including voltage sag/swell and unbalanced and distorted utility grid voltages. In comparison to DVR based on the VSI voltage inverter (VSI), the response from ZSI-DVR to a reduction of voltage distortions and harmonics is investigated. An experimental SPV ZSI-DVR prototype is developed in the laboratory to check the effectiveness of the controller and is tested under balanced and unbalanced supply and dynamic load conditions.

Multilayer graphene frequency doubler using direct-current bias and reflector networks

A multilayer graphene frequency doubler (GFD) with inductance–capacitor resonators (LCRs) and microstrip reflective stubs (MRS) is proposed in this paper. Graphene has strong nonlinear characteristics. Under the excitation of electromagnetic waves, the output power of odd harmonic of graphene is greater than that of even harmonic. Under the joint excitation of electromagnetic wave and bias voltage, the even harmonic output power of graphene is enhanced and the odd harmonic is suppressed, which is very suitable for making GFD. On the basis of analyzing the conductivity of graphene, the symbolically defined device model of multilayer graphene is established, and the model is applied to GFD circuit, the simulation results are basically consistent with the experimental data. The multiplier efficiency of graphene can be effectively improved by the bias voltage and LCR and the MRS. At an operating frequency of 0.65–1.15 GHz, the minimum conversion loss (CL) of the GFD is 20.57 dB when the input power is 16 dBm.

Structure Optimization of a Superconducting Linear Generator With YBCO Tape Windings

The paper proposed double-sided superconducting linear generator with YBCO tape windings. An analytical model of linear generator was developed based on electromagnetic field theory. A parameter-scanning method is used to search for optimal dimension parameters with the purpose of minimizing the non-sinusoidal components of the induced voltage curve. The results obtained show a significant improvement in the quality of air-gap magnetic field, and reduction of the higher harmonic in voltage wave obviously. The induction voltage in the generator coils at the speed of 130 m/s are studied. Finally, the feasibility of the superconducting linear generator was analyzed and confirmed.

Controlled rotation of micro-objects using acoustically driven microbubbles

Micromanipulation has significantly advanced both biomedical and industrial fields. However, there is still an urgent demand for controlled rotational manipulation at the microscale. Here, we report a noncontact rotational micromanipulation method using the acoustically driven microbubble contained in a micropipette. Acoustic vibration of the microbubble close to its resonant frequency was used to generate radiation force and microstreaming in the aqueous medium, allowing for trapping and rotating the micro-object. Simulation and particle visualization of the flow field clearly showed the microstreaming pattern induced by the oscillating microbubble. Experiments with different microbeads demonstrated the highly stable immobilization and rotation that related to the size and density of the microbead. By adjusting the frequency and voltage of the sinusoidal wave applied to the piezoelectric transducer, we demonstrated that the rotation frequency could be controlled over a broad range.

Measuring Temperature Time Course using Membrane Capacitance

The study of temperature dependence of ion channels requires accurate measurement and control of the membrane temperature. We exploited the intrinsic temperature dependence of membrane capacitance to create a fast and reliable thermometer without the need of external probes. To assess the membrane capacitance in Xenopus laevis oocytes, we applied a sinusoidal voltage wave (500 Hz) with the cut-open voltage clamp and recorded the resulting currents. We used Hilbert transform to extract the instantaneous amplitude and phase from the voltage and current signal which allowed us to determine the capacitance and series resistance.