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Roll transmissibility of the foam cushion during exposure to roll oscillation and roll-compensated lateral oscillation at 0.1, 0.2, and 0.4 m s−2 r.m.s. at frequencies from 0.25 to 1.0 Hz. Median values from 20 subjects. ... Lateral transmissibility of the foam cushion during exposure to lateral oscillation, roll oscillation, and fully roll-compensated lateral oscillation at 0.1, 0.2, and 0.4 m s−2 r.m.s. at frequencies from 0.25 to 1.0 Hz. Median values from 20 subjects. ... Effect of magnitude of oscillation on the roll velocity measured at the seat-body interface with the foam cushion during exposure to lateral oscillation and roll oscillation at frequencies between 0.25 and 1.0 Hz. Median values from 20 subjects. ... Root-sums-of-squares of frequency-weighted measured components at the seat-body interface during lateral oscillation, roll oscillation, and fully roll-compensated lateral oscillation on a rigid seat and on a foam cushion. Components weighted using axis multiplying factors and asymptotic weightings extrapolated horizontally at frequencies less than 0.5 Hz without band-pass filtering (BS 6841, 1987). Median values from 20 subjects. ... Percentages of subjects reporting discomfort localised at the ischial tuberosities when sitting on the rigid seat and on the foam cushion during exposure to lateral oscillation, roll oscillation, and fully roll-compensated lateral oscillation across all frequencies. ... The discomfort caused by lateral oscillation, roll oscillation, and fully roll-compensated lateral oscillation has been investigated at frequencies between 0.25 and 1.0 Hz when sitting on a rigid seat and when sitting on a compliant cushion, both without a backrest. Judgements of vibration discomfort and the transmission of lateral and roll oscillation through the seat cushion were obtained with 20 subjects. Relative to the rigid seat, the cushion increased lateral acceleration and roll oscillation at the lower frequencies and also increased discomfort during lateral oscillation (at frequencies less than 0.63 Hz), roll oscillation (at frequencies less than 0.4 Hz), and fully roll-compensated lateral oscillation (at frequencies between 0.315 and 0.5 Hz). The root-sums-of-squares of the frequency-weighted lateral and roll acceleration at the seat surface predicted the greater vibration discomfort when sitting on the cushion. The frequency-dependence of the predicted discomfort may be improved by adjusting the frequency weighting for roll acceleration at frequencies between 0.25 and 1.0 Hz.
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Top: Relaxation oscillations during a SINIS detector 6keV X-ray event (the detector replacing Rb). The amplitude modulation and sinusoidal oscillation are due to the externally applied band-pass filter. Bottom: Time sequence of inverse oscillation periods, equivalent to a time-dependent fr, extracted from the above analog signal (note the larger time scale, while the arrow indicates the range of the top graph). Circuit and device parameters were: L=48nH, Rs=91mΩ, Ic=7.28μA(κ=8). ... Scaling of multi-pixel cryogenic detectors for imaging becomes increasingly difficult with size due to complexity of readout circuitry and cryogenic constraints (thermal load from wiring). We propose and demonstrate a new readout scheme based on a highly stable RF oscillator composed of a superconducting tunnel junction which exhibits relaxation oscillations. The oscillation frequency is almost linear with the analog bias signal over a wide operation range. The frequency signals from different detectors can be combined into one single readout line. The current noise of an optimized circuit is about 5pA/Hz, which is comparable to standard SQUID amplifiers. We show experimental data from ‘stand-alone’ operation as well as response to microcalorimeter X-ray signals.... Relaxation oscillations... Analog-to-frequency converter
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Oscillation frequency selection... Sallen-Key HPF-based oscillator. ... Oscillation test... Sallen-Key LP filter turned to an oscillator. ... This paper is mainly focused on the investigation of the optimum value of the oscillation frequency in the Oscillation-based Built-In Self Tests (OBIST). It has been assumed that the proper frequency value might increase the test efficiency in covering hard-detectable short faults in analog integrated circuits (ICs) designed in nanoscale technology. In our research, active analog filters designed in 0.35μm and 90nm CMOS technologies were used as circuits under test (CUT). The tested circuits were brought to oscillation at different oscillation frequencies by varying the values of passive devices. The achieved results prove that the efficiency of OBIST approach can be increased in this way.
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Somatosensory evoked potentials of a normal subject. Two SEPs are superimposed in a single trace. A few small notches were seen on the ascending slope of N20 in raw SEPs (A). The onset of N20 component was 15.7 ms (dotted line). Oscillation potentials were clearly detectable and their amplitudes were measurable in SEPs filtered at 500 to 1000 Hz (B). Three potentials (indicated by arrows) were judged as significant (larger than 3 times mean amplitude range of background recordings) peaks of an oscillation. ... The amplitudes of oscillation potentials (A) and their size ratios to the main components of SEP (B,C) were plotted against the groups of their onset latencies. (•, controls; ○, Parkinson's disease; ×, myoclonus epilepsy). The latencies for the 1st to 10th groups were 0.0–1.2, 1.3–2.5, 2.6–3.9, 4.0–5.3, 5.4–7.0, 7.1–8.7, 8.8–10.4, 10.5–12.1, 12.2–12.8 and 12.9–14.5 ms. The amplitudes of oscillation potentials are shown in (A), the ratio of the amplitude of oscillation potential to that of N20o-N20p [ratio (osc/N20o-N20p)] in (B), and the ratio of oscillation potential to N20p-P25p [ratio (osc/N20p-N25p)] in (C). (A) In PD patients, the sizes of some oscillation potentials were abnormally larger than the normal oscillation potentials in the first to sixth groups. In contrast, in patients with ME, extremely enlarged oscillations were observed in the fourth to tenth groups. (B) The ratios (osc/N20o-N20p) for abnormally enlarged oscillation potentials were significantly larger than the normal values in both patients with PD and ME. (C) In PD patients, the ratios (osc/N20p-P25p) for enlarged oscillation peaks were again abnormally larger than the normal values. In ME patients, however, those for enlarged potentials were the same as the normal values for earlier (1st to 5th) group oscillation potentials. In patients with ME, oscillation potentials were present at late latencies when they were never seen in normal subjects. ... High-frequency oscillation... SEPs of a patient with Parkinson's disease. Several notches were clearly seen on the ascending and descending slopes of N20 even in conventional SEPs (A). The onset of N20 (14.4 ms) following the end of P14 subcortical component is shown by a dashed line. Six oscillation potentials (indicated by arrows) followed P14 in highly filtered (500–1000 Hz) SEPs (B). Four of them (indicated by large arrows) were abnormally enlarged (>mean+3 SD of normal values). This patient was considered to have a giant oscillation. ... Aim: A high-frequency oscillation in the range of 600–900 Hz has been shown to be a component of the somatosensory evoked potential (SEP) in humans. In the present communication, we studied these oscillation potentials in two neurological disorders.... Histograms of the onset latencies of oscillation potentials in normal subjects (A) and Parkinson's disease patients (B). There were five groups in the onset latencies of oscillation potentials in normal subjects (A). In patients with Parkinson's disease, oscillation potentials were observed at almost the same latency groups as normals (B). ... SEPs of a patient with myoclonus epilepsy (ME). In conventional SEPs (A), the latencies of N20, P25 and N33 components were within the normal range even though the N20-P25 and P25-N33 amplitudes were extremely enlarged. Several oscillation potentials were seen on the slope from P25 to N33 and descending slope of N33. Clearly differentiated 9 oscillation potentials (arrows) were detected in SEPs filtered 500–1000 Hz (B). Seven of them (third to ninth potentials) were abnormally large (large arrows). The onset of sixth potential was 8.9 ms. The last 4 oscillation potentials were evoked at the latencies when no oscillation potentials were observed in normals.
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A crystallization monitoring system using a quartz crystal oscillator was implemented in the cooling crystallization of dilute lauric acid solutions for the investigation of the nucleation process of the solute. In addition, the microscopic observation of the oscillator surface was conducted to examine the number and size of yielded nuclei, and the observed results and the resonant frequency variation of the oscillator were analyzed to explain the nucleation process.... Measured frequency drops from stearic acid deposition ... Comparison of the estimated masses from SEM photograph and frequency measurement and average mass ratio of SEM to frequency ... Variation of the resonant frequency of oscillator with lowered temperature in ethanol–water solution. ... Magnified plots of frequency variation while oscillator temperature decreases in lauric acid solutions of 0.05g/L (top), 0.15g/L (middle) and 0.25g/L (bottom). ... SEM photographs of bare oscillator (a) and oscillators taken at the coolant temperature of 7°C from 0.05g/L solution (b), 0.15g/L (c) and 0.25g/L (d). ... Quartz crystal Oscillator... Resonant frequency
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Photograph of the oscillator chip. ... Tuning curve of the LC oscillator. ... In this paper a voltage-controlled oscillator (VCO) is presented reaching oscillation frequencies well above 100GHz. The oscillator has been fabricated in a 200GHz SiGe:C BiCMOS technology with 0.25μm minimum feature size. In the design of the VCO two circuit approaches were considered. The first used transmission- lines in the resonator and the second used inductors above the silicon substrate. It is shown by simulation that by using inductors a higher oscillation frequency can be obtained. The fabricated oscillator has a tuning range from 113.2 to 117.2GHz at a supply voltage of −3V. This oscillation frequency is the highest reported so far for a silicon-based transistor technology.... Simulation results and measurement of the 117GHz oscillator (VEE=-3V) ... Circuit diagram of the high frequency oscillator. ... LC-oscillator
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He’s frequency–amplitude formulation is used to solve the Duffing harmonic oscillator problem. The solution procedure is simple, and the result obtained is valid for the whole solution domain with high accuracy.... Modified He’s frequency formulation method... Nonlinear oscillators
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The DRO's output waveforms with and without device mismatch between the two oscillators. ... A novel digitally-controlled oscillator (DCO) is reported. Utilizing a new capacitive load, the new DCO is capable of producing much higher output frequencies than existing DCOs. All other components are fully digital and modular, allowing portability to any CMOS process and customization for different applications. At the heart of the DCO is a digital ring oscillator (DRO) that utilizes the new shunt-capacitive loads. Unprecedented higher frequencies are obtained through a novel idea of electrically removing the effect of un-enabled loads. Simple design conditions for achieving proper operation of the DRO are provided and verified through simulations with several technologies. Spice simulations verified the correct and superior operation of the DCO even with device mismatch. A custom layout of the DRO was generated using LFoundry's 150nm technology. The total DRO area was found to be 418µm2. Comparison with other DCOs and VCO shows that the new DCO outperforms conventional DCOs in all aspects; maximum attainable frequency, power efficiency and required number of control bits to achieve a certain resolution.... The DRO's characteristics (period/frequency versus control word) using the two control methods. ... Power consumption of the DRO; power increases as frequency decreases. ... Digitally-controlled oscillator (DCO)... DCO's frequency characteristics. Code words 0–30 represent the basic DRO range. Other ranges are obtained through division with a 3-bit counter. ... Conventional techniques for implementing DCOs. (a) A digital oscillator based on shunt MOS capacitors, (b) a digital oscillator based on current starving, and (c) a digital oscillator based on path selection.
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Shape oscillations... PSDs of a2 the different fluids at (a) Re=639 and (b) Re=418. In (a), the green solid line denotes f=107Hz, the natural frequency of n=2 mode oscillation for water droplet and the green dashed line denotes f=90Hz, the natural frequency of n=2 mode oscillation for glycerol droplet. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.) ... The shape dynamics of droplets exposed to an air jet at intermediate droplet Reynolds numbers is investigated. High speed imaging and hot-wire anemometry are employed to examine the mechanism of droplet oscillation. The theory that the vortex shedding behind the droplet induces oscillation is examined. In these experiments, no particular dominant frequency is found in the wake region of the droplet. Hence the inherent free-stream disturbances prove to be driving the droplet oscillations. The modes of droplet oscillation show a band of dominant frequencies near the corresponding natural frequency, further proving that there is no particular forcing frequency involved. In the frequency spectrum of the lowest mode of oscillation for glycerol at the highest Reynolds number, no response is observed below the threshold frequency corresponding to the viscous dissipation time scale. This selective suppression of lower frequencies in the case of glycerol is corroborated by scaling arguments. The influence of surface tension on the droplet oscillation is studied using ethanol as a test fluid. Since a lower surface tension reduces the natural frequency, ethanol shows lower excited frequencies. The oscillation levels of different fluids are quantified using the droplet aspect ratio and correlated in terms of Weber number and Ohnesorge number.... Sequence of consecutive snapshots (5ms apart) of the oscillating droplets. The scale bar in the first image represents 1mm. ... Power spectral density of the instantaneous velocity measured at the wake of the oscillating droplets for water and glycerol at two different Reynolds numbers.
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Various biological processes regulated by cytosolic Ca2+ oscillations. ... Calcium oscillations... Cartoon illustrating the main mechanisms involved in the generation of cytosolic Ca2+ oscillations. Cytosolic Ca2+ oscillations are generated through the concerted action of cellular mechanisms that increase (red) and decrease (blue) the concentration of Ca2+ in the cytoplasm. Oscillatory signals are initiated by stimuli that trigger entry of external Ca2+ through receptor (R) or voltage (ΔV) gated Ca2+ channels in the plasma membrane or by activation of receptors (R) that stimulate PLC and InsP3-mediated Ca2+-release from the ER/SR. When the cytosolic level of Ca2+ increases, Ca2+ itself stimulates InsP3Rs and/or RyRs to release further Ca2+ into the cytoplasm. During this phase, Ca2+ buffers bind Ca2+ which contributes to the decrease in the cytosolic concentration of free Ca2+. When the Ca2+ concentration reaches high levels, the plasma membrane Ca2+-ATPase (PMCA) and Na+/Ca2+-exchanger (NCX) extrude Ca2+ to the outside, whereas the ER/SR Ca2+-ATPase (SERCA) pumps Ca2+ back into the ER/SR. ... Cytosolic calcium (Ca2+) oscillations are vastly flexible cell signals that convey information regulating numerous cellular processes. The frequency and amplitude of the oscillating signal can be varied infinitely by concerted actions of Ca2+ transporters and Ca2+-binding proteins to encode specific messages that trigger downstream molecular events. High frequency cytosolic Ca2+ oscillations regulate fast responses, such as synaptic transmission and secretion, whereas low frequency oscillations regulate slow processes, such as fertilization and gene transcription. Thus, the cell exploits Ca2+ oscillations as a signalling carrier to transduce vital information that controls its behaviour. Here, we review the underlying biochemical mechanisms responsible for generating and discriminating cytosolic Ca2+ oscillations.
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