Average Oscillation Frequency Research Articles

Design and analysis of 7-stage MOS current mode logic power gated MOSFETs in current starved voltage-controlled oscillator for the phase locked loop application

This paper presents a new process, voltage and temperature (PVT) tolerant 7-stage ring type current starved voltage-controlled oscillator (CS-VCO). In this, a 7-stage ring VCO is proposed using power gated technique for phase locked loop (PLL) application. PLL plays a major role in clock and data recovery, Global Positioning System (GPS) system and satellite communications. For the high-speed application of PLL it is designed using 7-stage inverter delay cell with MOS current mode logic (MCML) technique. The circuit undergoes process, voltage and temperature variations with different parameters such as average power, oscillation frequency, phase noise, tuning range and output noise. The Monte-Carlo analysis justifies the proposed design provides better results. The circuit is simulated under 45 nm CMOS technology using cadence virtuoso. The average power consumption of the proposed circuit is 29.368 µW with the oscillation frequency of 3.06 GHz. The output noise and the phase noise of the proposed VCO are -161.55 dB and -125.92 dBc/Hz respectively. It achieves the frequency tuning range (FTR) of 95.09%. The obtained simulation results are highly robust with PVT making the circuit suitable for PLL application.

Electron energy gain due to a laser frequency modulation experienced by electron during betatron motion

Direct laser acceleration of electrons is an important energy deposition mechanism for laser-irradiated plasmas that is particularly effective at relativistic laser intensities in the presence of quasi-static laser-driven plasma electric and magnetic fields. These radial electric and azimuthal magnetic fields provide transverse electron confinement by inducing betatron oscillations of forward-moving electrons undergoing laser acceleration. Electrons are said to experience a betatron resonance when the frequency of betatron oscillations matches the average frequency of the laser field oscillations at the electron position. In this paper, we show that the modulation of the laser frequency as seen by an electron performing betatron oscillations can be another important mechanism for net energy gain that is qualitatively different from the betatron resonance. Specifically, we show that the frequency modulation experienced by the electron can lead to net energy gain in the regime where the laser field performs three oscillations per betatron oscillation. There is no net energy gain in this regime without the modulation because the energy gain is fully compensated by the energy loss. The modulation slows down the laser oscillation near transverse stopping points, increasing the time interval during which the electron gains energy and making it possible to achieve net energy gain.

Electric field-driven up-and-down motion of the flexible tail of Al13+ cluster system-a nano-scale flipper.

Dynamic metal nanoclusters have become a hot area of research in the field of nanoscience and nanotechnology due to their potential applications in micro devices. One such dynamic cluster is a quasi-planar ground state (GS) Al13+ cluster which exhibits anelectric field driven up and down flipping motion of the flexible tail which oscillates with respect to the mean plane. A Car-Parrinello molecular dynamics (CPMD) simulation has been carried out to understand the nature of dynamics of the cluster. CPMD simulation study reveals that the flexible tail region of the Al13+ isomeric system (two ground states M1, M2 and a transition state TS connecting them) can be engaged in a systematic up down flipping motion by the application of a transverse electric field. A saw tooth electric field of amplitude 5.19V/nm is sufficient to induce the up-and-down flipping oscillation of the cluster, which has an average oscillation frequency of around 20 THz. AIM, NICS and AdNDP analyses also have been carried out to understand the fluxional nature of the cluster from the electronic structural perspective. Electronic structural analysis of selected optimized intermediate states in the presence of transverse electric field has also been analyzed to correlate the electronic structure with the dynamic nature of the cluster. Single-point energies of all intermediate states between two minima of Al13+ clusters connected through a transition state cluster. Optimized geometries of Al13+ clusters in the presence of electric field of different strengths have been carried out by using the Gaussian 03 package. 6-311 + G(d) basis set and B3LYP hybrid density functional have been utilized for these studies. To establish the flipping motion, Car-Parrinello molecular dynamics (CPMD) has been performed using the cp.x module of the Quantum ESPRESSO 6.3.0 program package using the Perdew-Burke-Ernzerhof (PBE) functional, plane-wave basis set and ultrasoft pseudopotentials. ORTEP-3 and POV ray-3.7 software packages have been used for visualization and graphics generation. Atoms in molecule (AIM), Adaptive Natural Density Partitioning (AdNDP) analysis have been carried out using Multiwfn 3.7 program package.

Sleepy Stack CSVCO with wide tuning and low power for PLL applications

This paper describes the implementation of low power leakage technique called Sleep-Stack in a Current Starved Voltage Controlled Oscillator (VCO) a block of Phase Locked Loop (PLL). The VCO is a electronic oscillator, whose oscillation frequency is decided by the control voltage. The major issue in the VCO is the power consumption, which has an impact on the performance of the PLL. The VCO that limits the current is preferred than the other oscillator which is called as Current Starved VCO. The work i.e. the design of Current Starved VCO is implemented using low power leakage technique called Sleepy Stack. This has been implemented in 45nm CMOS Technology with a supply voltage of 1.2 V in Cadence Software. The parameters like average power, oscillation frequency, and delay are calculated for this technique. The corner analysis has been performed for all this technique to verify the stable/linearity even in the worst case scenario. It has been observed that the sleepy stack technique with gain 23.99 GHz/V, phase noise -63.8dBc/Hz, Figure of Merit value of -142.234dBc/Hz and having frequency tuning range of 77.79%.The average power obtained for the Sleepy Stack technique is 11.88nW which is less than that of the existing CSVCO.

Specific features of pressure pulsation control in combustion chambers of land based gas turbine units

LLC SPC Teplofizika, developing low-emission combustion chambers with premixing of fuel for ground application gas turbine installations, investigates the problems associated with the occurrence of pressure pulsations in the combustion chambers, as well as with the methods of their registration and measurement. To date, there is no unified method for assessing and calculating the amplitude-frequency characteristics of these pulsations and their measurement in general. This article is based on many years of experience in measuring and recording pressure pulsations under the conditions of a test bench and operation. Methods for evaluating and accumulating measurement results are presented, criteria for determining the average frequency and amplitude of oscillations are developed, reproducible in the course of experiments and during full-scale measurements. To detect vibrating combustion, an additional criterion of coherence of vibrations is also used with the aid of the entropy coefficient. As a result of the computational and experimental study, we find that the pulsation pressure in the volume of the combustion chamber does not allow the use of probes for measuring pressure pulsations in the air volume of the combustion chamber to reliably prevent the occurrence of vibrating combustion during its operation.

Modeling the activity of the dopamine signaling pathway by combination of analog electrical circuit and mathematical approaches

This paper demonstrates the application of the system biology principles on the example of the dopamine signaling pathway in neurons. Presented model is based on two approaches – cytomorphic electronic circuits and mathematical modeling. Transcription and phosphorylation of DARPP-32 was modeled by analog circuit, based on well-known approaches presented in [1]. It was shown that application of circuit helps to receive signal oscillations that close to described ones in real biological systems. This combination on the one hand gives possibility to simplify calculations, on another to show this signaling pathway dynamics. The expected effect of changes in the functioning of calcium channels is considered, and the mathematical model of the interaction of system components is proposed. The average frequency of calcium current oscillations due to the presence of dopamine was 30 Hz in presented model, that is consistent with the literature, where the frequency of such oscillations is up to several tens of Hz. All presented results shows good correlation with known data, which already published today.

Effects of high-pressure treatment on the structure and function of myofibrils.

The effects of high pressure (40–70 MPa) on the structure and function of myofibrils were investigated by high pressure microscopy. When this pressure was applied to myofibrils immersed in relaxing solution, the sarcomere length remained almost unchanged, and the A band became shorter and wider. The higher the applied pressure, the faster the change. However, shortening and widening of the A band were not observed when pressure was applied to myofibrils immersed in a solution obtained by omitting ATP from the relaxing solution. However, even under these conditions, structural loss, such as loss of the Z-line structure, occurred. In order to evaluate the consequences of this pressure-treated myofibril, the oscillatory movement of sarcomere (sarcomeric oscillation) was evoked and observed. It was possible to induce sarcomeric oscillation even in pressure-treated myofibrils whose structure was destroyed. The pressurization reduced the total power of the sarcomeric oscillation, but did not change the average frequency. The average frequency did not change even when a pressure of about 40 MPa was applied during sarcomeric oscillation. The average frequency returned to the original when the pressure was returned to the original value after applying stronger pressure to prevent the sarcomere oscillation from being observed. This result suggests that the decrease in the number of myosin molecules forming the crossbridge does not affect the average frequency of sarcomeric oscillation. This fact will help build a mechanical hypothesis for sarcomeric oscillation. The pressurization treatment is a unique method for controlling the structure of myofibrils as described above.

Oscillatory Reaction Rates in the Electro-Oxidation of Formaldehyde on Palladium

Formaldehyde has been used as a model system to investigate the electro-oxidation of small organic molecules, mainly on platinum[1]. This reaction is extremely dependent on the control conditions (potential and current) and it is also known to display self-organized oscillations on platinum[2]. In the present work we report a study of the oscillating reaction rates in the electro-oxidation of formaldehyde on polycrystalline palladium and in aqueous sulfuric acid media. The mapping of the existence region of potential oscillations was obtained by a slow current scan. Galvanodynamic oscillations were observed to range from 0.50 to 0.85 V. Further analysis was performed by galvanostatic measurements. The amplitude of potential oscillations increases in time. The potential-increase part of the cycle is formed by a rapid increase to about 0.60 V and then a slow one to 0.85 V, followed by an abrupt drop, with an average oscillation frequency of 0.15 Hz. Both the morphology and the frequency of oscillations differ from that observed for the electro-oxidation of formaldehyde on platinum, where the electrode potential varies from 0.40 to 0.90 V, and the it increases slowly until reaching 0.60 V followed by a rapid potential increase of up to 0.90 V, and then it decreases abruptly. Oscillations on platinum under comparable conditions were also about three times faster [3]. Overall, our results suggest the surface chemistry underlying the dynamics of formaldehyde elector-oxidation on palladium and platinum is considerably different, particularly under oscillatory regime. Some mechanistic aspects of the, far less studied, palladium system will be discussed.

Stim2b Knockout Induces Hyperactivity and Susceptibility to Seizures in Zebrafish Larvae.

In neurons, stromal interaction molecule (STIM) proteins regulate store-operated Ca2+ entry (SOCE) and are involved in calcium signaling pathways. However, STIM activity in neurological diseases is unclear and should be clarified by studies that are performed in vivo rather than in cultured cells in vitro. The present study investigated the role of neuronal Stim2b protein in zebrafish. We generated stim2b knockout zebrafish, which were fertile and had a regular lifespan. Using various behavioral tests, we found that stim2b−/− zebrafish larvae were hyperactive compared with wild-type fish. The mutants exhibited increases in mobility and thigmotaxis and disruptions of phototaxis. They were also more sensitive to pentylenetetrazol and glutamate treatments. Using lightsheet microscopy, a higher average oscillation frequency and higher average amplitude of neuronal Ca2+ oscillations were observed in stim2b−/− larvae. RNA sequencing detected upregulation of the annexin 3a and gpr39 genes and downregulation of the rrm2, neuroguidin, and homer2 genes. The latter gene encodes a protein that is involved in several processes that are involved in Ca2+ homeostasis in neurons, including metabotropic glutamate receptors. We propose that Stim2b deficiency in neurons dysregulates SOCE and triggers changes in gene expression, thereby causing abnormal behavior, such as hyperactivity and susceptibility to seizures.

Quantum-enhanced sensing of a single-ion mechanical oscillator.

Special quantum states are used in metrology to achieve sensitivities below the limits established by classically behaving states1,2. In bosonic interferometers, squeezed states3, number states4,5 and 'Schrödinger cat' states5 have been implemented on various platforms and have demonstrated improved measurement precision over interferometers using coherent states6,7. Another metrologically useful state is an equal superposition of two eigenstates with maximally different energies; this state ideally reaches the full interferometric sensitivity allowed by quantum mechanics8,9. Here we demonstrate the enhanced sensitivity of these quantum states in the case of a harmonic oscillator. We extend an existing experimental technique10 to create number states of order up to n=100 and to generate superpositions of a harmonic oscillator ground state and a number state of the form [Formula: see text] with n up to 18 in the motion of a single trapped ion. Although experimental imperfections prevent us from reaching the ideal Heisenberg limit, we observe enhanced sensitivity to changes in the frequency of the mechanical oscillator. This sensitivity initially increases linearly with n and reaches a maximum at n=12, where we observe a metrological enhancement of 6.4(4) decibels (the uncertainty is one standard deviation of the mean) compared to an ideal measurement on a coherent state with the same average occupation number. Such measurements should provide improved characterization of motional decoherence, which is an important source of error in quantum information processing with trapped ions11,12. It should also be possible to use the quantum advantage from number-state superpositions to achieve precision measurements in other harmonic oscillator systems.

A 13.4-MHz Relaxation Oscillator With Temperature Compensation

A low-phase-noise relaxation oscillator uses a digital compensation loop to reduce its temperature coefficient (TC). This relaxation oscillator is fabricated in the 0.18-μm CMOS process. The measured average oscillation frequency is 13.4 MHz. The whole oscillator consumes 157.8 μW under a 1.2-V supply. The measured average TCs of the oscillation frequency with and without compensation are 193.15 and 1098.7 ppm/°C, respectively. The TC achieves an improvement of 5.7 times. The measured frequency variation is within ±2% from -20 °C to 100 °C by using the digital compensation loop. The measured phase noise at 100-kHz offset frequency is -104.82 dBc/Hz, and the measured figure of merit (FOM) is -154.4 dBc/Hz.

An On-Chip Relaxation Oscillator With Comparator Delay Compensation

In this brief, a relaxation oscillator with comparator delay compensation is presented. Two digital compensation loops are introduced to compensate for the comparator delay. This relaxation oscillator is fabricated in the 0.18- $\mu \text{m}$ CMOS process. The measured average oscillation frequency is 943.1 kHz. The whole oscillator consumes $5.2~\mu \text{W}$ under a 0.9-V supply. The measured average temperature coefficients (TCs) of the oscillation frequency with and without compensation are 93.88 and 618.17 ppm/°C, respectively. It achieves a TC improvement of $6.6\times $ . The measured frequency variation is within ±0.7% from −10 °C to 100 °C by using the DCLs. The measured line sensitivity is 4.37%/V. The measured figure of merit (FOM2) is 173.3 dB.

Analysis of the natural frequencies of oscillations of a planar truss with an arbitrary number of panels

Introduction. Analytical solutions for problems of structural mechanics are not only an alternative approach to solving problems of strength, reliability and dynamics of structures, but also the possibility for simple performance evaluations and optimization of structures. Frequency analysis of planar trusses, most often used in construction and engineering, is an important part of the study of structures. Objectives - development of a three-parameter induction algorithm for deriving the analytical dependence of the natural oscillation frequencies of the truss on the number of panels. Materials and methods. A flat, statically definable truss with one additional external link and double braces has been considered. The inertia properties of the truss are modeled by point masses located in the nodes of the lower straight truss belt. Each mass is assumed to have only one vertical degree of freedom. The stiffness of all truss rods is assumed to be the same. The task is to obtain analytical dependences of the oscillation frequencies of the proposed truss model on the number of panels. The derivation of the desired formulas is performed by the method of induction in three stages - according to the numbers of rows and columns of the compliance matrix, calculated using the Maxwell - Mohr formula and the number of panels. To find common members of the obtained sequences of coefficients, an apparatus was used to compile and solve the recurrent equations of the Maple computer mathematics system. The task of determining frequencies has been reduced to the eigenvalue problem of a bisymmetric matrix. Results. For the elements of the compliance matrix, general formulas have been found, according to which the frequency equations are compiled and solved. It is shown that in the frequency spectra of trusses with different numbers of panels there is always one common frequency (middle frequency) located in the middle of the spectrum. An expression is found for the maximum value of the average oscillation frequency as a function of the height of the truss. Conclusions. The proposed truss scheme, despite its external static indeterminacy and the lattice, which does not allow for the calculation of forces by such methods as the method of cutting nodes and the cross section method, allows analytical solutions for the natural frequencies of loads in the nodes. The obtained formulas have a rather simple form, and some general properties, such as frequency coincidences for different numbers of panels and the presence of an analytically calculated maximum of the average frequency function of the truss height, make this solution convenient for practical structural evaluations.

Rüchardt’s experiment treated by Fourier transform

It is well known that topics in physics which rely heavily on mathematics can present difficulties for graduate students; for example, problems involving the application of the Fourier transform. To overcome some related difficulties, an integrated approach where physics, mathematics and laboratory activities are strongly interconnected can be helpful. In this view, the present paper describes a device and a data analysis approach whose physics and mathematics facets are jointly taken into account. More specifically, we shall deal with a revised Rüchardt’s device, a topic that plays an important role in the physics curriculum, and we shall introduce the Fourier transform operator in order to extract the average oscillation frequency, thus avoiding computation of the average period of oscillations in the time space. Within this framework, it is shown how the use of the Fourier transform furnishes a straightforward measure of the experiment’s relevant physical quantities.

Спектральные свойства флуктуаций концентрационного поля в электромембранных системах с сульфокатионообменными мембранами с разной дисперсностью ионообменника

Методом Фурье-анализа определен спектральный состав флуктуаций концентрационного поля в стратифицированных системах с экспериментальными гетерогенными сульфокатионообменными мембранами Ralex CM Pes («MEGA» a.s., Чехия), содержащими ионообменник различной дисперсности. С увеличением времени измельчения ионообменных частиц, соответственно степени их дисперсности, выявлено уменьшение размеров проводящих участков и расстояния между ними на поверхности мембран. Высокая шумовая составляющая колебаний концентрационного поля в растворе вследствие развития электроконвективных вихрей установлена на границе с мембраной, характеризующейся более однородной поверхностью.

High-speed video analysis of flame oscillations along a PMMA rod after stagnation region blowoff

During blowoff extinction of clear cast PMMA rods in concurrent axial flow for microgravity BASS-II experiments, a dynamic flame oscillation was observed after the flame was blown off of the stagnation point but briefly stabilized on the periphery of the rod. Complementary normal gravity experiments were conducted and flame oscillations were tracked using a high-speed color camera at 240 frames per second. The side-stabilized flame oscillated up and down the rod with increasing amplitude until the entire flame extinguished. In none of the BASS-II or normal gravity tests could the side-stabilized flames persist (Hopf subcritical bifurcation). Since the oscillations occurred even in microgravity, the mechanism does not depend on gravity. For the larger fuel radius tests, the flame developed asymmetric oscillation (pitchfork bifurcation). The oscillation time and the number of oscillations scale with the inverse square of the rod radius (∼ Fourier no.) for the preheated microgravity rods. The average flame oscillation frequency is found to be linearly dependent on the mixed convective stretch rate (inverse of the flow time). The flame intensity varied in concert with its direction, either increasing or decreasing as the flame moved upstream or downstream, respectively. The oscillation frequency decreased as the amplitude increased and the flame slipped slightly farther down the rod with each oscillation. The flame speed increased with each subsequent oscillation, both flashing forward upstream and retreating downstream. The oscillations were found to closely follow a power law log-periodic dependence similar to those that describe systems approaching a critical point, such as diffusion-limited aggregation clusters, earthquakes, ruptures, and even stock market crashes. The net flame speeds varied linearly with ambient oxygen concentration, and linearly with the mixed convective stretch rate. Based on these observations, a mechanistic theory of the oscillations is described, and is consistent with the thermodiffusive instability.

Novel closed-form equation for oscillation frequency range of differential ring oscillator

In this article, a novel efficient circuit level analysis is proposed for the oscillation frequency in the differential ring oscillator with N-stage, where N is larger than 3, and exact closed-form equations are achieved for the oscillation frequency range and average oscillation frequency ( $$ f_{av} $$ ). In order to attain the maximum oscillation frequency until the drain current of MOSFET is a square-wave, it is assumed which transistors are switching. At first, the amplitude of each harmonic of the output voltage is calculated by Fourier series expansion. Then, by some simplifications, the oscillation frequency range and $$ f_{av} $$ are derived in the closed-form equations. Comparatively, the time and frequency domain analyses have been dominantly employed for the previous and the proposed works, respectively. There is an excellent agreement among experimental, simulation and theoretical results.

Slow and Fast Neocortical Oscillations in the Senescence-Accelerated Mouse Model SAMP8.

The senescence-accelerated mouse prone 8 (SAMP8) model is characterized by accelerated, progressive cognitive decline as well as Alzheimer’s disease (AD)-like neurodegenerative changes, and resembles the etiology of multicausal, sporadic late-onset/age-related AD in humans. Our aim was to find whether these AD-like pathological features, together with the cognitive deficits present in the SAMP8 strain, are accompanied by disturbances in cortical network activity with respect to control mice (SAM resistance 1, SAMR1) and, if so, how the alterations in cortical activity progress with age. For this purpose, we characterized the extracellular spontaneous oscillatory activity in different regions of the cerebral cortex of SAMP8 and SAMR1 mice under ketamine anesthesia at 5 and 7 months of age. Under these conditions, slow oscillations and fast rhythms generated in the cortical network were recorded and different parameters of these oscillations were quantified and compared between SAMP8 and their control, SAMR1 mice. The average frequency of slow oscillations in SAMP8 mice was decreased with respect to the control mice at both studied ages. An elongation of the silent periods or Down states was behind the decreased slow oscillatory frequency while the duration of active or Up states remained stable. SAMP8 mice also presented increased cycle variability and reduced high frequency components during Down states. During Up states, the power peak in the gamma range was displaced towards lower frequencies in all the cortical areas of SAMP8 with respect to control mice suggesting that the spectral profile of SAMP8 animals is shifted towards lower frequencies. This shift is reminiscent to one of the principal hallmarks of electroencephalography (EEG) abnormalities in patients with Alzheimer’s disease, and adds evidence in support of the suitability of the SAMP8 mouse as a model of this disease. Although some of the differences between SAMP8 and control mice were emphasized with age, the evolution of the studied parameters as SAMR1 mice got older indicates that the SAMR1 phenotype tends to converge with that of SAMP8 animals. To our knowledge, this is the first systematic characterization of the cortical slow and fast rhythms in the SAMP8 strain and it provides useful insights about the cellular and synaptic mechanisms underlying the reported alterations.

Peculiarities in WC and W2C Eutectic Phases Dissolution in Interfacial Zones of Composites

The structural and phase composition of dissolution-and-diffusion interfacial zones at the particle-matrix interfaces of the composites reinforced with W–C particles infiltrated by a molten iron-base binder has been investigated. The peculiarities in the filler’s phases dissolution during infiltration have been explained within the framework of computed model allowing the estimation of an average atom oscillation frequency of the investigated phases.

Power Source for Wireless Sensors in Pipes

In this paper, we present investigations on wireless sensors for fluid control inside a pipe. Autarkic sensors are in the technical trend. They are typically connected with a transceiver unit for data transmission. Sensors usually need a lower amount of energy than data transceivers. Therefore, they are commonly supplied via wires or batteries with electricity. With common technologies, this request leads to high requirements on tightness in liquids since poor sealing could easily lead to failures. Replacement of batteries inside pipes is complicated and almost accompanied by a flow interruption. The application of energy harvesters as power supply is therefore a good alternative. In our studies we used flexible piezoelectric energy harvesters of PVDF (Poly-Vinylidene-Di-Fluoride). All harvesting units consist of piezoelectric PVDF-foils as active layers and Aluminum-foils as electrodes. The layers were stacked alternating on each other and wound to a spool. A LDPE-film wraps the spool and prevents the inflow of liquids. The device has following parameters: No. of windings: 4 in air, 4, 5, 7 in water Dimensions: 15 mm O 22mm Materials: PDVF: 25μm; Aluminimum: 6μm, LDPE: 25μm A ring shaped bluff body was placed inside the pipe to induce turbulence in the fluid stream. As the harvesters have been arranged downstream of the bluff body, they were forced to oscillate independent of the media. In each case, deformation of the active layers led to a polarization and a separation of electrical charges. Experiments were carried out in a wind channel as well as in a water pipe. In air, the spool oscillates with a frequency of about 30Hz, at a wind speed of about 7m/s. A -Voltage of about 4V (peak-peak) was measured. This delivers in case of power adjustment, power values of about 0.54μW. In water, the velocity of the fluid was limited to nearly one tenth. Oscillation starts only at a water speed above 0.6m/s. The average oscillation frequency is about 18Hz. At a velocity of 0.74m/s, a peak-peak-Voltage up to about 2.3V was found. In case of impedance adjustment, the power was about 0.33μW. This power is stored in a capacitor. Assuming a data transmission unit consumes about 0.2 mWs during one operational period of 1 second, the duty cycle time can be calculated to about 6.2 minutes for air harvesting and 10.1 minutes for harvesting in water.