scholarly journals Acceptable-and-attractive Approximate Solution of a Continuous Non-Cooperative Game on a Product of Sinusoidal Strategy Functional Spaces

2021 ◽  
Vol 46 (2) ◽  
pp. 173-197
Author(s):  
Vadim Romanuke

Abstract A problem of solving a continuous noncooperative game is considered, where the player’s pure strategies are sinusoidal functions of time. In order to reduce issues of practical computability, certainty, and realizability, a method of solving the game approximately is presented. The method is based on mapping the product of the functional spaces into a hyperparallelepiped of the players’ phase lags. The hyperparallelepiped is then substituted with a hypercubic grid due to a uniform sampling. Thus, the initial game is mapped into a finite one, in which the players’ payoff matrices are hypercubic. The approximation is an iterative procedure. The number of intervals along the player’s phase lag is gradually increased, and the respective finite games are solved until an acceptable solution of the finite game becomes sufficiently close to the same-type solutions at the preceding iterations. The sufficient closeness implies that the player’s strategies at the succeeding iterations should be not farther from each other than at the preceding iterations. In a more feasible form, it implies that the respective distance polylines are required to be decreasing on average once they are smoothed with respective polynomials of degree 2, where the parabolas must be having positive coefficients at the squared variable.

1981 ◽  
Vol 92 (1) ◽  
pp. 305-321 ◽  
Author(s):  
T. M. WARD ◽  
W. F. HUMPHREYS

Locomotion in the vagrant wolf spider Trochosa ruricola is compared to that in the burrow dwelling wolf spider Lycosa tarentula (Araneae: Lycosidae). L. tarentula takes relatively shorter steps than T. ruricola. At high speeds T. ruricola approximates an alternating tetrapod gait but this does not occur in L. tarentula. Phase lag differs between species and varies marginally with speed except for ipsilateral phase lags in L. tarentula which are erratic if they include leg 1. In both species the protraction/retraction ratio is directly related to both running speed and stepping frequency, but the relationship is more marked in L. tarentula. The protraction/retraction ratio is more variable in leg 1 and varies between legs along the body but by a greater amount in L. tarentula. In these spiders, in contrast to the situation in many insects, both the duration of protraction and retraction show marked inverse relationships to stepping frequency. The power stroke (retraction) occupies a variable proportion of the stepping cycle, which is not the case in other spiders, and this proportion is lower than for other spiders. It is suggested that the first pair of legs is used more for sensory than for locomotory purpose and that this is more marked in the burrow dwelling species, L. tarentula.


2021 ◽  
Vol 38 (5) ◽  
pp. 937-949
Author(s):  
Minjie Xu ◽  
Yuzhe Wang ◽  
Shuya Wang ◽  
Xianqing Lv ◽  
Xu Chen

AbstractSufficient and accurate tide data are essential for analyzing physical processes in the ocean. A method is developed to spatially fit the tidal amplitude and phase lag data along satellite altimeter tracks near Hawaii and construct reliable cotidal charts by using the Chebyshev polynomials. The method is completely dependent on satellite altimeter data. By using the cross-validation method, the optimal orders of Chebyshev polynomials are determined and the polynomial coefficients are calculated by the least squares method. The tidal amplitudes and phase lags obtained by the method are compared with those from the Finite Element Solutions 2014 (FES2014), National Astronomical Observatory 99b (NAO.99b), and TPXO9 models. Results indicate that the method yields accurate results as its fitting results are consistent with the harmonic constants of the three models. The feasibility of this method is also validated by the harmonic constants from tidal gauges near Hawaii.


1996 ◽  
Vol 76 (6) ◽  
pp. 4094-4103 ◽  
Author(s):  
K. A. Sigvardt ◽  
T. L. Williams

1. Experiments have been performed on in vitro preparations of lamprey spinal cord bathed in D-glutamate, which induces a pattern of activity recorded from ventral roots that is similar to that seen in the intact animal during swimming. The frequency of fictive swimming increases with increasing D-glutamate concentration, but intersegmental phase lag remains unaffected. 2. The effects on intersegmental phase lags of unequal activation of the rostral and caudal halves of a preparation were determined. Unequal activation was produced by placing a diffusion barrier in the middle of the chamber and perfusing the two halves with different concentrations of D-glutamate. 3. Within the rostral compartment, the phase lag increased from control when the rostral D-glutamate concentration was higher than the caudal concentration, and decreased from control when it was lower. By contrast, the phase lags within the caudal compartment did not depend on the ratio of D-glutamate concentration between the two compartments. 4. The frequency of the ventral root activity during differential activation was not significantly different from that of control experiments that had the same concentration as in the rostral compartment. 5. The results are discussed within the context of the mathematical analysis of chains of coupled oscillators by Kopell and Ermentrout and other current theories about the mechanisms of intersegmental coordination in the lamprey.


2019 ◽  
Vol 6 (10) ◽  
pp. 191387 ◽  
Author(s):  
Mitchell P. Ford ◽  
Hong Kuan Lai ◽  
Milad Samaee ◽  
Arvind Santhanakrishnan

Negatively buoyant freely swimming crustaceans such as krill must generate downward momentum in order to maintain their position in the water column. These animals use a drag-based propulsion strategy, where pairs of closely spaced swimming limbs are oscillated rhythmically from the tail to head. Each pair is oscillated with a phase delay relative to the neighbouring pair, resulting in a metachronal wave travelling in the direction of animal motion. It remains unclear how oscillations of limbs in the horizontal plane can generate vertical momentum. Using particle image velocimetry measurements on a robotic model, we observed that metachronal paddling with non-zero phase lag created geometries of adjacent paddles that promote the formation of counter-rotating vortices. The interaction of these vortices resulted in generating large-scale angled downward jets. Increasing phase lag resulted in more vertical orientation of the jet, and phase lags in the range used by Antarctic krill produced the most total momentum. Synchronous paddling produced lower total momentum when compared with metachronal paddling. Lowering Reynolds number by an order of magnitude below the range of adult krill (250–1000) showed diminished downward propagation of the jet and lower vertical momentum. Our findings show that metachronal paddling is capable of producing flows that can generate both lift (vertical) and thrust (horizontal) forces needed for fast forward swimming and hovering.


2014 ◽  
Vol 10 (4) ◽  
pp. 562-592 ◽  
Author(s):  
Rajneesh Kumar ◽  
Vandana Gupta

Purpose – The purpose of this paper is to depict the effect of thermal and diffusion phase-lags on plane waves propagating in thermoelastic diffusion medium with different material symmetry. A generalized form of mass diffusion equation is introduced instead of classical Fick's diffusion theory by using two diffusion phase-lags, one phase-lag of diffusing mass flux vector, represents the delayed time required for the diffusion of the mass flux and the other phase-lag of chemical potential, represents the delayed time required for the establishment of the potential gradient. The basic equations for the anisotropic thermoelastic diffusion medium in the context of dual-phase-lag heat transfer (DPLT) and dual-phase-lag diffusion (DPLD) models are presented. The governing equations for transversely isotropic and isotropic case are also reduced. The different characteristics of waves like phase velocity, attenuation coefficient, specific loss and penetration depth are computed numerically. Numerically computed results are depicted graphically for anisotropic, transversely isotropic and isotropic medium. The effect of diffusion and thermal phase-lags are shown on the different characteristic of waves. Some particular cases of result are also deduced from the present investigation. Design/methodology/approach – The governing equations of thermoelastic diffusion are presented using DPLT model and a new model of DPLD. Effect of phase-lags of thermal and diffusion is presented on different characteristic of waves. Findings – The effect of diffusion and thermal phase-lags on the different characteristic of waves is appreciable. Also the use of diffusion phase-lags in the equation of mass diffusion gives a more realistic model of thermoelastic diffusion media as it allows a delayed response between the relative mass flux vector and the potential gradient. Originality/value – Introduction of a new model of DPLD in the equation of mass diffusion.


2020 ◽  
Vol 494 (1) ◽  
pp. 1375-1386 ◽  
Author(s):  
Liang Zhang ◽  
Mariano Méndez ◽  
Diego Altamirano ◽  
Jinlu Qu ◽  
Li Chen ◽  
...  

ABSTRACT We present a systematic analysis of the phase lags associated with the type-C quasi-periodic oscillations (QPOs) in GRS 1915+105 using RXTE data. Our sample comprises 620 RXTE observations with type-C QPOs ranging from ∼0.4 to ∼6.3 Hz. Based on our analysis, we confirm that the QPO phase lags decrease with QPO frequency, and change sign from positive to negative at a QPO frequency of ∼2 Hz. In addition, we find that the slope of this relation is significantly different between QPOs below and above 2 Hz. The relation between the QPO lags and QPO rms can be well fitted with a broken line: as the QPO lags go from negative to positive, the QPO rms first increases, reaching its maximum at around zero lag, and then decreases. The phase-lag behaviour of the subharmonic of the QPO is similar to that of the QPO fundamental, where the subharmonic lags decrease with subharmonic frequency and change sign from positive to negative at a subharmonic frequency of ∼1 Hz; on the contrary, the second harmonic of the QPO shows a quite different phase-lag behaviour, where all the second harmonics show hard lags that remain more or less constant. For both the QPO and its (sub)harmonics, the slope of the lag–energy spectra shows a similar evolution with frequency as the average phase lags. This suggests that the lag–energy spectra drive the average phase lags. We discuss the possibility for the change in lag sign, and the physical origin of the QPO lags.


2014 ◽  
Vol 2014 ◽  
pp. 1-10
Author(s):  
Lei Zhou ◽  
Jiangang Li ◽  
Wennong Zhang ◽  
Zexiang Li

Wire bonder is a typical high speed machine. The motion speed of XY-stage is the key factor of bonding efficiency. However, phase lag elements in the servo system limit the bandwidth and slow down the system’s response. A predictive velocity observer is proposed to compensate for those phase lags. Then, the velocity loop controller can be designed as for a servo system which does not have those phase lags. Loop gains are enlarged and bandwidth is enlarged correspondingly. Then, the motion speed is improved and settling time is decreased. Experiment results verify that the predictive velocity observer provided a significant phase lead and the performance of wire bonder is improved.


1997 ◽  
Vol 9 (6) ◽  
pp. 1251-1264 ◽  
Author(s):  
Roger D. Traub ◽  
Miles A. Whittington ◽  
John G. R. Jefferys

Gamma-frequency electroencephalogram oscillations may be important for cognitive processes such as feature binding. Gamma oscillations occur in hippocampus in vivo during the theta state, following physiological sharp waves, and after seizures, and they can be evoked in vitro by tetanic stimulation. In neocortex, gamma oscillations occur under conditions of sensory stimulation as well as during sleep. After tetanic or sensory stimulation, oscillations in regions separated by several millimeters or more occur at the same frequency, but with phase lags ranging from less than 1 ms to 10 ms, depending on the conditions of stimulation. We have constructed a distributed network model of pyramidal cells and interneurons, based on a variety of experiments, that accounts for near-zero phase lag synchrony of oscillations over long distances (with axon conduction delays totaling 16 ms or more). Here we show that this same model can also account for fixed positive phase lags between nearby cell groups coexisting with near-zero phase lags between separated cell groups, a phenomenon known to occur in visual cortex. The model achieves this because interneurons fire spike doublets and triplets that have average zero phase difference throughout the network; this provides a temporal framework on which pyramidal cell phase lags can be superimposed, the lag depending on how strongly the pyramidal cells are excited.


2000 ◽  
Vol 83 (1) ◽  
pp. 465-476 ◽  
Author(s):  
William L. Miller ◽  
Karen A. Sigvardt

Timing of oscillatory activity along the longitudinal body axis is critical for locomotion in the lamprey and other elongated animals. In the lamprey spinal locomotor central pattern generator (CPG), intersegmental coordination is thought to arise from the pattern of extensive connections made by propriospinal interneurons. However, the mechanisms responsible for intersegmental coordination remain unknown, in large part because of the difficulty in obtaining quantitative information on these multisegmental fibers. System-level experiments were performed on isolated 50-segment preparations of spinal cord of adult silver lampreys, Ichthyomyzon unicuspis, to determine the dependence of CPG performance on multisegmental coupling. Coupling was manipulated through use of an experiment chamber with movable partitions, which allowed separate application of solution to rostral, middle, and caudal regions of the spinal cord preparation. During control trials, fictive locomotion, induced by bath application ofd-glutamate in all three regions, was recorded extracellularly from ventral roots. Local synaptic activity in a variable number of middle segments was subsequently blocked with a low-Ca2+, high-Mn2+ saline solution in the middle compartment, whereas conduction in axons spanning the middle segments was unaffected. Spectral analysis was used to assess the effects of blocking propriospinal coupling on intersegmental phase lag, rhythm frequency, correlation, and variability. Significant correlation and a stable phase lag between the rostral and caudal regions of the spinal cord preparation were maintained during block of as many as 16 and sometimes 20 intervening segments. However, the mean value of this rostrocaudal phase decreased with increasing number of blocked segments from the control value of approximately 1% per segment. By contrast, phase lags within the rostral and caudal end regions remained unaffected. The cycle frequency in the rostral and caudal regions decreased with the number of blocked middle segments and tended to diverge when a large number of middle segments was blocked. The variability in cycle frequency and intersegmental phase both increased with increasing number of blocked segments. In addition, a number of differences were noted in the properties of the motor output of the rostral and caudal regions of the spinal cord. The results indicate that the maximal functional length of propriospinal coupling fibers is at least 16–20 segments in I. unicuspis, whereas intersegmental phase lags are controlled at a local level and are not dependent on extended multisegmental coupling. Other possible roles for multisegmental coupling are discussed.


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