Phase Angle Relationship Research Articles

Indirect matrix converter drives for unity displacement factor and minimum switching losses

With sinusoidal input currents and no dc-link capacitor, a matrix converter offers remarkable advantages over other alternatives in applications requiring improved utility interaction and critical weight/volume reduction. Lately, indirect matrix converter topologies have also been investigated, leading to possibility of reduced switch number and multi-drive applications. However, due to off-line input current regulation of the converters, the input displacement factor varies with LC input filters and load conditions. This fact results in non-unity displacement factor and increased reactive power flow. In this paper, a novel on-line input current control strategy is proposed based on a closed-loop control in the synchronous reference frame. The approach allows independent control of two input current components (active and reactive), yielding zero reactive components. In addition, this paper specifies a relationship of input current phase angle and switching losses in semiconductors. Based on the specification, it is proved that the indirect matrix converter has minimum switching losses with the input currents in phase with the input voltages. Thus, the proposed control algorithm yields minimum switching losses and no reactive power flow. The feasibility of the proposed technique has been verified in the paper.

Phase resolved electroluminescence measurements in thin films of low density polyethylene using a charge coupled device camera

Electroluminescence (EL) produced by a commercially available additive free low density polyethylene film has been investigated under a 50 Hz AC electrical stress. The spatial distribution, spectral characteristics and the phase angle relationship of EL with respect to the 50 Hz applied AC voltage were studied using a sensitive Peltier cooled charge-couple device (CCD) camera. The experimental results from several test samples show that the EL can be divided into two different groups according to the EL spatial distribution: (1) homogeneous EL and (2) inhomogeneous EL. At the same applied voltage, the spectra of the homogenous and inhomogeneous EL were found to be significantly different. Homogeneous EL had maximum emission intensity in the red and near infrared (>700 nm), whereas the inhomogeneous emission had maximum intensity at shorter wavelengths (550-600 nm). Phase resolved measurements showed that homogeneous EL always produced equal emission intensity in the positive and negative half-cycles (symmetric distribution), whereas, inhomogeneous EL produced an asymmetric intensity distribution. To explain these results, it is suggested that homogeneous emission is associated with charge injection and bipolar recombination in the surface states on both sides of the sample, whereas inhomogeneous emission is associated with field enhancement at defects on one of the two sides of the film which allow charge to be injected into states more representative of the bulk material.

Tidal flow asymmetry in the diurnal regime: bed-load transport and morphologic changes around the Red River Delta

The relation between tidal flow asymmetry and net transport of sediment in the semidiurnal regime has been extensively described. This study reveals that in the diurnal regime, the direction of long-term net bed-load transport and resulting morphologic changes is partly determined by the phase-angle relationship of O1, K1, and M2. Simple analytical formulations of time-averaged bed-load transport were derived which separate the relative contributions of tidal asymmetry from that of residual flow with tidal stirring. In this particular case, the Red River Delta in Vietnam, transports related to tidal asymmetry are larger than those induced by the monsoon currents, and are an order of magnitude larger than those associated with topographic residual flow around the delta. Tide-induced morphologic changes dominate at water depths between 10 and 25 m, of which the patterns of erosion and deposition overlap with observed bathymetric changes. Additional observed changes that occur in more shallow water cannot be explained by tidal asymmetry and are probably related to wave action and to deposition from the buoyant river plume.

Joint coordination during whole-body lifting in women with low back pain after pregnancy

Commissaris DA, Nilsson-Wikmar LB, van Dieën JH, Hirschfeld H. Joint coordination during whole-body lifting in women with low back pain after pregnancy. Arch Phys Med Rehabil 2002;83:1279-89. Objective: To quantify differences in the kinematics of lifting between women with low back and/or pelvic pain after pregnancy and women without. Design: Comparison study. Setting: Research laboratory. Participants: Volunteer sample of 7 women with pain (positive pain drawing, no physical examination) and 9 female controls (not matched). Interventions: Not applicable. Main Outcome Measures: Duration of downward and upward phases, relative instant of box lift-off, joint angles, spatial angles of trunk and pelvis, pelvic angle relative to trunk, and phase angle relationships between joints. Results: The duration of the upward phase ± standard deviation was longer in the pain group (1731±290ms vs 1489±187ms, P=.031). At box lift-off, this group had less hip joint flexion (101.9°±20.8° vs 78.7°±12.4°, P=.015) but more backward pelvis tilt relative to the trunk, that is, more lumbar spine flexion (126.3°±16.8° vs 109.0°±12.3°, P=.031). The pain group showed an immediate transition from lumbar spine flexion to extension, whereas the controls maintained peak flexion for about 600ms. The peak phase lag between knee and hip joint extension in the upward phase was larger for the pain group (−29.7°±8.3° vs −17.2°±5.5°, P=.003). Conclusion: Women with low back and/or pelvic pain after pregnancy showed different kinematics of lifting. Further research is needed to determine the exact relationship between the altered kinematics and the underlying disorder. © 2002 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation

Tidal inlet velocity asymmetry in diurnal regimes

Tidal velocity asymmetry at inlets influences sediment transport pathways and the morphological evolution of estuaries/lagoons connected to these inlets. Generation of overtides is generally seen as the main cause of tidal velocity asymmetry. Whilst majority of studies examining tidal velocity asymmetry have concentrated on inlets located in semi-diurnal tidal regimes, here, attention is focused on the processes responsible for causing tidal velocity asymmetry at inlets located in diurnal tidal regimes. Using field data collected from three West Australian inlets, it is shown that tidal velocity asymmetry in this type of system is caused by the oceanic tidal conditions. It is also shown that in these systems, the occurrence of flood/ebb dominance can be determined using oceanic tidal elevations, which are more readily available than inlet current data. In contrast to semi-diurnal systems the flood/ebb dominance in diurnal systems varies throughout the year depending on the phase angle relationship between the significant oceanic tidal constituents. The net sediment transport in to/out of these systems, which determines the morphological evolution of the systems, is shown to be governed more by the degree of tidal velocity asymmetry rather than the number of occurrences or duration of flood/ebb-dominant periods.

Chronic administration of imipramine and lithium changes the phase-angle relationship between the activity and core body temperature circadian rhythms in rats.

Evidence suggests that there is an association between the pathophysiology of depression and a disturbance of circadian rhythms. Accordingly, attention has focused on the possible effects of antidepressants on circadian rhythms. In the present study, we examined the effects of chronic administration of two clinically effective antidepressant agents, imipramine and lithium, on several circadian rhythms in the rat. Activity, core body temperature, and drinking rhythms were assessed in constant darkness (DD) and light-dark (LD) conditions. In DD, lithium significantly lengthened the circadian period of the activity, temperature, and drinking rhythms, while imipramine had no effect. In LD, both drugs significantly delayed the phase of the activity rhythm, but did not change that of the other two rhythms. As a result, the phase-angle differences between the activity and temperature rhythms significantly increased. Neither lithium nor imipramine produced any effect on the resynchronization of these rhythms after an 8-h delay in the LD cycle. These results indicate that although both drugs produced different effects on the circadian period of individual rhythms, both caused a relative phase advance of the temperature rhythm as compared to the activity rhythm, and this effect may be related to the similarity in their antidepressant effects.

Adaptive synchrophaser for reducing aircraft cabin noise and vibration

An "adaptive synchrophaser" is disclosed for modifying the phase angle relationship between aircraft propellers to reduce cabin noise and/or vibration. Rather than use a constant pre-selected angle for a specific passenger cabin configuration during a particular flight mode (e.g., during liftoff or cruise), the synchrophaser periodically monitors actual operating conditions and modifies the phase angle accordingly. In the preferred embodiment, a plurality of transducers (microphones) are installed at several cabin locations to sample noise periodically. The signals are then transmitted via a signal conditioner, a multiplexer and an analog-to-digital converter to a signal processor. The processor calculates the maximum acoustic noise at each microphone location for all possible phase angles. It then identifies the optimum phase angle that resulted in the lowest maximum noise anywhere in the cabin, and signals a synchrophaser to set that angle. This process not only reduces noise based on actual on-going conditions, but also balances the cabin noise so that there are not any "hot" seats with high noise levels.

Activity patterns of the New Zealand cancrid crab Cancer novaezelandiae (Jacquinot) in the field and laboratory

The activity patterns of the sublittoral crab Cancer novaezelandiae (Jacquinot) were investigated in the laboratory and field. Subtidal and intertidal potting surveys showed that timing of foraging activity in the field is influenced by daily and tidal variables. Subtidally, catches of crabs were greatest during night-time fishing periods. Catch rates also appeared to vary with timing of high tide relative to the diel period. Crabs were only caught in the intertidal zone during night high tides, indicating that their response to the tidal stimuli that initiate migration is strongly modulated by the light-dark (LD) cycle. When subjected to a normal LD cycle in the laboratory crabs confined most of their activity to the “night-time” with hourly activity values highest just after “dusk”. Under constant laboratory conditions crabs exhibited an endogenous, circadian, nocturnal locomotor rhythm, with little evidence of a circatidal component within the pattern of activity. Lack of an endogenous tidal oscillator was also indicated by the stable phase-angle relationship between initial onset of activity to time of expected sunset, regardless of daily timing of high tides. Results indicate that tide-related activity in the field is based entirely upon a direct responsiveness to tidal stimuli and illustrate the importance of both exogenous and endogenous factors in regulation of timing of activity of epifaunal crustaceans.

Poles, Shapes, Senses of Rotation, and Sidereal Periods of Asteroids

A method of determination of poles, triaxial ellipsoid model shapes, senses of rotation, and sidereal periods of asteroids is presented. These parameters have been obtained simultaneously by solving a set of nonlinear equations, combining the well-known methods of photometric astrometry, amplitude-aspect, and magnitude-aspect. The results for 30 asteroids are presented. For 12 objects these parameters have been determined for the first time and for 8 others they have been improved. The remaining 10 asteroids were used mainly as test objects for the method. The rotational poles continue to show a tendency to avoid the ecliptic plane. Amplitude-solar phase angle and magnitude-phase angle relationships are obtained for most of the asteroids.

Relative phase quantifies interjoint coordination

This note illustrates by example how expression of joint movement on a phase plane can quantitatively describe multijoint coordination during complex actions. Automatic digitisation of high-speed video records was used to obtain lumbar vertebral, hip, knee and ankle joint angular kinematics in the sagittal plane of a subject performing a symmetric two-handed lifting movement. A consistent proximal-to-distal coordination was illustrated via angle-angle and relative phase angle presentations. During bending to pick up a load, the joints began their movement in the order proximal to distal while the reverse order of joint involvement occurred during extension. Phase angle relationships between joints may provide sufficiently sensitive measurements to identify changes in multijoint coordination induced by alterations in task variables such as (in the case of lifting) object mass, lifting height and load moment. Information regarding multijoint coordination is likely to be important in attempting to understand the respective roles and interaction between the bi and monarticular muscles which are involved in everyday complex actions like lifting.

Mutual interactions between optic lobe circadian pacemakers in the cricket Gryllus bimaculatus

The coupling mechanism between the bilaterally paired optic lobe circadian pacemakers in the cricket Gryllus bimaculatus was investigated by recording locomotor activity, under constant light or constant red light, after the optic nerve was unilaterally severed. 1. The majority (about 70%) of the animals showed a locomotor rhythm with 2 rhythmic components; one freerunning with a period of 25.33 ± 0.41 (SD) h and the other with 24.36 ± 0.37 (SD) h under constant light (Fig. 3A). 2. Removal of the intact side optic lobe abolished the longer period component (Fig. 4A), while the operation on the operated side caused a reverse effect (Fig. 4B), indicating that the longer and the shorter period components are driven by the pacemaker on the intact and the operated side, respectively. 3. The activity driven by a pacemaker was inhibited during the subjective day of the contralateral pacemaker (circadian time 0–10, Fig. 5). 4. The freerunning periods of the two components were not constant but varied as a function of the mutual phase angle relationship (Figs. 3A, 7, 8).

Ground-based Training for the Stimulus Rearrangement Encountered during Spaceflight

Approximately 65-70% of the crew members now experience motion sickness of some degree during the first 72 h of orbital flight on the Space Shuttle. Lack of congruence among signals from spatial orientation systems leads to sensory conflict, which appears to be the basic cause of space motion sickness. A project to develop training devices and procedures to preadapt astronauts to the stimulus rearrangements of microgravity is currently being pursued. The preflight adaptation trainers (PATs) are intended to: demonstrate sensory phenomena likely to be experienced in flight, allow astronauts to train preflight in an altered sensory environment, alter sensory-motor reflexes, and alleviate or shorten the duration of space motion sickness. Four part-task PATs are anticipated. The trainers are designed to evoke two adaptation processes, sensory compensation and sensory reinterpretation, which are necessary to maintain spatial orientation in a weightless environment. Recent investigations using one of the trainers indicate that self-motion perception of linear translation is enhanced when body tilt is combined with visual surround translation, and that a 270 degrees phase angle relationship between tilt and surround motion produces maximum translation perception.

A systematic approach to faradaic current, charging current and phase angle measurement by digital alternating current polarography

In microprocessor-based digital ac polarography, the simultaneous measurement of total alternating current polarograms at 10° phase angle intervals allows the calculation of both the faradaic and charging current components of the experiment as well as their phase-angle relationship to the applied potential. The data evaluation procedure is based upon extrapolation of the background current at potentials removed from the faradaic process so as to enable the charging current to be calculated in the presence of the faradaic current. The faradaic current can then be calculated by subtraction of the charging current. Curve fitting of the separated faradaic and charging current functions to an equation of the kind Y = A sin (X + φ), where φ is the phase angle, enables interpolated phase angles for the faradaic response to be calculated with an accuracy of better than 1°. Data are presented for the process [Fe(ox) 3] 3− + e − ⇌ [Fe(ox) 3] 4− (ox = oxalate) at a mercury electrode and provide a frequency-independent phase angle of (45 ± 1) 0 as expected theoretically for a reversible process. The two-electron reduction of copper(II) in 1 M NaNO 3 to produce a copper amalgam exhibits the theoretical frequency-dependent phase angle of less than 45° expected for a quasi-reversible process. The microprocessor-based digital ac method of phase-angle measurement is considered to be superior to conventional analog approaches, but not as accurate as the Fast Fourier Transform method developed by Smith and co-workers with more elaborate and expensive expensive laboratory computer-based instrumentation.

Application of Noise Analysis Technique for Monitoring the Moderator Temperature Coefficient of Reactivity in Pressurized Water Reactors

A new technique, based on the noise analysis of neutron detector and core-exit coolant temperature signals, is developed for monitoring the moderator temperature coefficient of reactivity in pressurized water reactors (PWRs). A detailed multinodal model is developed and evaluated for the reactor core subsystem of the loss-of-fluid test (LOFT) reactor. This model is used to study the effect of changing the sign of the moderator temperature coefficient of reactivity on the low-frequency phase angle relationship between the neutron detector and the core-exit temperature noise signals. Results show that the phase angle near zero frequency approaches - 180 deg for negative coefficients and 0 deg for positive coefficients when the perturbation source for the noise signals is core coolant flow, inlet coolant temperature, or random heat transfer.

Effects of light intensity on the circadian temperature and feeding rhythms in the squirrel monkey

The circadian rhythms of body temperature and feeding appear to be timed by separate pacemakers. Tonic administration of light has been used to investigate the response of the pacemaker timing behavioral rhythms; however, the response of the body temperature rhythm has not been similarly examined. This study investigates the circadian timing of the body temperature rhythm under conditions of different light intensity. We simultaneously recorded the patterns of both feeding and body temperature in squirrel monkeys free-running in an environment free of external time cues. In each lighting condition, the periods of the body temperature and feeding rhythms were identical. In constant bright light the rhythm periods were longer than when the animals were exposed to constant dim light. In addition, the variability of the periods was dependent on light intensity. The feeding rhythm period variance of animals in constant bright light was smaller than when in dim light. Conversely, the period of the free-running body temperature rhythm exhibited more variability in bright light than in dim light. Further, in each condition, there were changes in phase angle relationship between feeding and body temperature which were qualitatively similar to those observed in humans, although quantitatively smaller in magnitude. Thus, in the squirrel monkey, tonic light studies reveal that the mean circadian period of the body temperature and feeding rhythms are similar. However, changes in phase relationship, and differential rhythm period stabilities suggest differences in the period of the underlying, tightly coupled pacemakers.

The phase relationship between gyrophase‐bunched ions and MHD‐like waves

Recent calculations and computer simulations of the right‐hand resonant ion beam instability have indicated that gyrophase‐bunched ion distributions may be generated as a first step in the disruption of field‐aligned beams. Theory predicts a distinct phase angle relationship between the gyrovelocity of the phase‐bunched ions and the wave magnetic field. In this paper, observations of such a relationship between gyrophase‐bunched ions and MHD‐like waves upstream from the Earth's bow shock are presented. The observed phases are in accord with the theoretical predictions of the right‐hand resonant ion beam instability.

Freerunning and entrained circadian rhythms in body temperature in the domestic cat

Abstract The body temperature of the domestic cat was determined by radiotelemetry from implants in the peritoneal cavity. Longitudinal data were collected and analyzed with a periodic regression technique. Thermograms and actograms were constructed in order to study the transients that follow a phase shift of the LD cycle and to discern the freerun in body temperature and activity in constant dark. The main results indicate that the domestic cat has a prominent circadian rhythm in body temperature. Prominent transients occur after a phase shift of the LD cycle, and the temperature rhythm freeruns in constant dark, maintaining a constant phase angle relationship with the freerunning rhythm in activity.

Eccentric vibrator with shifting coupling

An eccentric vibrating machine which includes parallel shafts each carrying an eccentric mass. A gear rotatably journalled on a first of the shafts is drivingly connected to the second shaft for mutual rotation of the gear and second shaft. A shifting coupling is mounted on the first shaft and is selectively engageable with the gear at multiple angular positions around the gear to couple the first shaft to the gear and thereby selectively vary the phase angle relationship of the eccentric masses carried on the two shafts. A manual shifting control device is carried on the first shaft, and can be manually actuated to selectively engage the shifting coupling with the gear.

A user-interactive graphics-based computer system for analysis of the EEG

Computer technology provides a powerful high-resolution tool for the analysis and understanding of the electroencephalogram (EEG). A system of user-interactive graphics-based computer programs analyzing the power spectral density (PSD), coherence, and phase-angle relationships of the EEG is described, along with the mathematical algorithms used. The analytic variables inherent in coherence analysis are reviewed. These variables include choices of sampling parameters, auto- and cross-spectral algorithms, smoothing techniques, and use of the γ2(f) or γ(f) value for coherence. These variables in the analysis itself have a net interactive effect on the calculated results that often makes comparability of data across studies impossible. Thus, it is proposed that studies include a graph showing the authors’ derived coherence values for a set of standard test signals to enhance scientific communication.

Acoustic velocities and electrical properties of frozen sandstones and shales

Ultrasonic velocities and electrical properties have been measured in the laboratory at permafrost temperatures on a number of samples of sandstones and a shale which had been recovered from boreholes in the arctic and stored in their natural frozen state. Compressional and shear-wave velocities, electrical resistivity, and phase-angle relationships in the frequency range 0.005–100 kHz have been measured on the permafrost samples, at temperatures in the range −18 °C–+4 °C.Results of the tests show that, at a particular temperature, there is a small decrease in the electrical resistivity measured on all samples tested as the frequency is increased. The phase-angle differences measured show no consistent relationship with either frequency or temperature, but they are all less than 12° in magnitude. The electrical resistivity at a particular frequency and the ultrasonic velocities are affected in a similar manner by changes in temperature. Whereas the sandstones show a sharp reduction in velocities and resistivity as the temperature is raised to 0 °C or above, the shale shows little dependence of these parameters on changes in temperature in the range tested. An increase in shale content of the sandstone results in behavior intermediate between that of a clean sandstone and that of a shale.