Cessation Of Oscillation Research Articles

Dew point fast measurement in organic vapor mixtures using quartz resonant sensor.

A fast dew point sensor has been developed for organic vapor mixtures by using the quartz crystal with sensitive circuits. The sensor consists of the quartz crystal and a cooler device. Proactive approach is taken to produce condensation on the surface of the quartz crystal, and it will lead to a change in electrical features of the quartz crystal. The cessation of oscillation was measured because this phenomenon is caused by dew condensation. Such a phenomenon can be used to detect the dew point. This method exploits the high sensitivity of the quartz crystal but without frequency measurement and also retains the stability of the resonant circuit. It is strongly anti-interfered. Its performance was evaluated with acetone-methanol mixtures under different pressures. The results were compared with the dew points predicted from the universal quasi-chemical equation to evaluate the performance of the proposed sensor. Though the maximum deviations of the sensor are less than 1.1 °C, it still has a fast response time with a recovery time of less than 10 s, providing an excellent dehumidifying performance.

A new type of fast dew point sensor using quartz crystal without frequency measurement

Aiming at solving the problem of atmospheric humidity measurement, a new dew point sensor using quartz crystal without frequency measurement has been developed. The sensor is composed of the Peltier module and the quartz crystal. When active condensation begins to occur in the quartz crystal surface, the electrical characteristics of the quartz crystal will change. Consequently, the oscillation characteristics of the resonant circuit containing the quartz crystal will also change. Hence, the oscillation characteristics change can be used to identify the time of condensation. The cessation of oscillation was measured, due primarily to signal attenuation caused by dew formation. This method uses the sensitive properties of quartz crystal but with no frequency measurement and also exploit the stability of the circuit. The sensor we have developed has fast response time and recovery time, especially with excellent dehumidifying performance. The accuracy of the dew point sensor when compared with the MICHELL S4000 dew point meter is found to be ±0.3°C DP in the range of −20°C to 20°C DP. The low-cost sensor is easy to carry and has certain corrosion resistance.

Using Quartz Crystal Microbalance for Field Measurement of Liquid Viscosities

The field measurement of liquid viscosities, especially the high viscous liquids, is challenging and often requires expensive equipment, long processing time, and lots of reagent. We use quartz crystal microbalances (QCMs) operating in solution which are also sensitive to the viscosity and density of the contacting solution. QCMs are typically investigated for sensor applications in which one surface of QCM completely immersed in Newtonian liquid, but the viscous damping in liquids would cause not only large frequency shifts but also large losses in the quality factorQleading to instability and even cessation of oscillation. A novel mass-sensitivity-based method for field measurement of liquid viscosities using a QCM is demonstrated in this paper and a model describing the influence of the liquid properties on the oscillation frequency is established as well. Two groups of verified experiments were performed and the experimental results show that the presented method is effective and possesses potential applications.

Synchronization and Oscillator Death in Diffusively coupled lattice oscillators

We consider the synchronization and cessation of oscillation of a positive even number of planar oscillators that are coupled to their nearest neighbours on one, two, and three dimensional integer lattices via a linear and symmetric diffusion-like path. Each oscillator has a unique periodic solution that is attracting. We show that for certain coupling strength there are both symmetric and antisymmetric synchronization that corresponds to symmetric and antisymmetric non-constant periodic solutions respectively. Symmetric synchronization persists for all coupling strengths while the antisymmetric case exists for only weak coupling strength and disappears to the origin after a certain coupling strength.

Entrainment, instability, quasi-periodicity, and chaos in a compound neural oscillator.

We studied the dynamical behavior of a class of compound central pattern generator (CPG) models consisting of a simple neural network oscillator driven by both constant and periodic inputs of varying amplitudes, frequencies, and phases. We focused on a specific oscillator composed of two mutually inhibiting types of neuron (inspiratory and expiratory neurons) that may be considered as a minimal model of the mammalian respiratory rhythm generator. The simulation results demonstrated how a simple CPG model--with a minimum number of neurons and mild nonlinearities--may reproduce a host of complex dynamical behaviors under various periodic inputs. In particular, the network oscillated spontaneously only when both neurons received adequate and proportionate constant excitations. In the presence of a periodic source, the spontaneous rhythm was overridden by an entrained oscillation of varying forms depending on the nature of the source. Stable entrained oscillations were inducible by two types of inputs: (1) anti-phase periodic inputs with alternating agonist-antagonist drives to both neurons and (2) a single periodic drive to only one of the neurons. In-phase inputs, which exert periodic drives of similar magnitude and phase relationships to both neurons, resulted in varying disruptions of the entrained oscillations including magnitude attenuation, harmonic and phase distortions, and quasi-periodic interference. In the absence of significant phasic feedback, chaotic motion developed only when the CPG was driven by multiple periodic inputs. Apneic episodes with repetitive alternation of active (intrinsic oscillation) and inactive (cessation of oscillation) states developed when the network was driven by a moderate periodic input of low frequency. Similar results were demonstrated in other, more complex oscillator models (that is, half-center oscillator and three-phase respiratory network model). These theoretical results may have important implications in elucidating the mechanisms of rhythmogenesis in the mature and developing respiratory CPG as well as other compound CPGs in mammalian and invertebrate nervous systems.

A new photo-oscillometric method employing the delta-algorithm for accurate blood pressure measurement.

To measure blood pressure accurately, by developing a new algorithm and an indirect method employing a non-elastic cuff with a photosensor. A non-elastic cuff was wrapped around the brachium. A reflecting plate (10 mm x 40 mm) was sited on the inner central part of the cuff on the arterial side. On the opposite side of the cuff, a photosensor consisting of light-emitting and light-receiving elements was positioned. Oscillation due to arterial pulsation was measured photologically during cuff inflation. Cessation of oscillation was taken as the systolic blood pressure (SBP) and, when the delay time between photo-oscillation and cuff-pressure oscillation upstrokes was at its minimum, the transition from rapid to more stable changes in photo-oscillation was taken as the diastolic blood pressure (DBP; the delta-algorithm). We compared the blood pressures measured directly in the brachial artery with those obtained by this method and by the conventional auscultatory method in 10 normotensive and 26 hypertensive subjects [12 women and 24 men, mean age 45 +/- 16 years (mean +/- SD), with mean brachial circumference 27 +/- 2.6 cm]. The blood pressure of each subject was measured simultaneously by the direct and indirect methods five times. Errors (differences from direct blood pressure measurements) produced with this new method [SBP -0.8 +/- 3.1 mmHg, (mean +/- SD) DBP 0.6 +/- 2.8 mmHg] were significantly smaller than errors obtained by use of the auscultatory method (SBP -7.4 +/- 5.6 mmHg, DBP 3.0 +/- 7.1 mmHg; P < 0.001, n = 180). The delta-algorithm was easily applicable to an automatic blood pressure measuring device. This new photo-oscillometric method was more accurate than the auscultatory method for measuring blood pressure. The delta-algorithm is logical and will be useful for accurate blood pressure measurement.