System Analysis of the Circadian Rhythm of Euglena gracilis, I. Linearities and Non-Linearities in the Response to Temperature Signals

1982 ◽  
Vol 37 (11-12) ◽  
pp. 1240-1252
Author(s):  
Wolfram Lork ◽  
Til Kreuels ◽  
Wolfgang Martin ◽  
Klaus Brinkmann
Keyword(s):  
Euglena Gracilis ◽  
System Analysis ◽  
Superposition Principle ◽  
Reference Signal ◽  
Circadian System ◽  
Masking Effect ◽  
Cellular Motility ◽  
Apparent Lack ◽  
Non Linear ◽  
Non Stationary Signal

Abstract The approach of control theory is used to describe the structure of the circadian system of Euglena gracilis. As a first step we discriminate linear and non linear properties of the dynamics. The cellular motility as measured via long time records of sedimentation parameters in cultures is defined as the system output; sinusoidal temperature signals are used as input. By means of non stationary signal processing procedures we estimate gain and phase of the output signal. The problem of defining an appropiate gain of a cell suspension with an undefinite number of cells is solved by using the superimposition of two different input signals and by keeping one of them fixed as a reference signal. Linear properties are shown with a linear frequency transfer and with the validity of the superposition principle at least within distinct regions of amplitude and frequency. Non linear properties are the signal distortion, the restriction of linear amplification to a distinct range of input temperature and the ambiguity of phase coupling near the circadian eigenfrequency. The apparent lack of a limit of entrainment -an unexpected linear property - is explained by the masking effect of thermokinesis. A model is proposed describing the simultaneous control of motility by thermokinesis and the circadian system. On the base of that model further experiments are outlined.

System Analysis of the Circadian Rhythm of Euglena gracilis, II: Masking Effects and Mutual Interactions of Light and Temperature Responses

1984 ◽  
Vol 39 (7-8) ◽  
pp. 801-811 ◽  
Author(s):  
T. Kreuels ◽  
R. Joerres ◽  
W. Martin ◽  
K. Brinkmann
Keyword(s):  
Circadian Rhythms ◽  
Euglena Gracilis ◽  
System Analysis ◽  
Limited Range ◽  
Circadian System ◽  
System A ◽  
Input Signals ◽  
Free Running ◽  
Single Input ◽  
White Mutant

Abstract Motility of Euglena gracilis shows free running circadian rhythms. The circadian system is sensitive to light and temperature signals, but it is always masked by direct responses of motility to light (photokinesis) and temperature (thermokinesis). By means of a compartimental model which defines the interrelations between the pathways of thermokinesis, photokinesis and the circadian system a unifying view of effects of temperature and light input signals is outlined. According to the model, and using double sine input signals the dynamics of thermokinesis is described by a differential amplifier with constant gain. Although thermokinesis heavily masks circadian responses to temperature signals, the limited range of circadian entrainment is indirectly demonstrated by a limited reappearance of free running circadian oscillations after stopping the temperature program. Free running circadian oscillations do reappear only after pretreatment with temperature periods near the circadian eigenperiod.A white mutant lacking photosynthesis is used to investigate the role of photosynthesis in the signal processing. Although light synchronizes the circadian rhythms of the white mutant if applied as single input, it does not affect the motility if applied together with temperature inputs near the circadian eigenperiod. These results indicate frequency dependent mutual interactions between the model compartments.

Energy resources demand-supply system analysis and empirical research based on non-linear approach

Energy ◽  
2011 ◽  
Vol 36 (9) ◽  
pp. 5460-5465 ◽  
Author(s):  
Mei Sun ◽  
Xiaofang Wang ◽  
Ying Chen ◽  
Lixin Tian
Keyword(s):  
Empirical Research ◽  
System Analysis ◽  
Supply System ◽  
Energy Resources ◽  
Linear Approach ◽  
Non Linear

COMPREHENSIVE ANALYSIS OF NORMAL AND DIABETIC HEART RATE SIGNALS: A REVIEW

2012 ◽  
Vol 12 (05) ◽  
pp. 1240033 ◽  
Author(s):  
OLIVER FAUST ◽  
V. RAMANAN PRASAD ◽  
G. SWAPNA ◽  
SUBHAGATA CHATTOPADHYAY ◽  
TEIK-CHENG LIM
Keyword(s):  
Heart Rate ◽  
Organ Damage ◽  
Extraction Methods ◽  
Time Frequency ◽  
Ecg Signals ◽  
Cardiac Health ◽  
Non Linear ◽  
Non Stationary Signal ◽  
Early Diagnosis Of Diabetes ◽  
Typical Range

A large section of the world's population is affected by diabetes mellitus (DM), commonly referred to as "diabetes." Every year, the number of cases of DM is increasing. Diabetes has a strong genetic basis, hence it is very difficult to cure, but can be controlled with medications to prevent subsequent organ damage. Therefore, early diagnosis of diabetes is very important. In this paper, we examine how diabetes affects cardiac health, which is reflected through heart rate variability (HRV), as observed in electrocardiography (ECG) signals. Such signals provide clues for both the presence and severity of diabetes as well as diabetes-induced cardiac impairments. Heart rate (HR) is a non-linear and non-stationary signal. Thus, extracting useful information from HRV signals is a difficult task. We review several sophisticated signal processing and information extraction methods in order to establish measurable relationships between the presence and the extent of diabetes as well as the changes in the HRV signals. Furthermore, we discuss a typical range of values for several statistical, geometric, time domain, frequency domain, time–frequency, and non-linear features for HR signals from 15 normal and 15 diabetic subjects. We found that non-linear analysis is the most suitable approach to capture and analyze the subtle changes in HRV signals caused by diabetes.

Non-linear optimal fuzzy control synthesis for robust output tracking of uncertain micro-electro-mechanical systems

2016 ◽  
Vol 39 (8) ◽  
pp. 1146-1160 ◽  
Author(s):  
Alireza Modirrousta ◽  
Mostafa Shokrian Zeini ◽  
Tahereh Binazadeh
Keyword(s):  
Fuzzy Control ◽  
Sliding Mode ◽  
Reference Signal ◽  
Mechanical Systems ◽  
Control Synthesis ◽  
Sliding Mode Controller ◽  
Micro Electro Mechanical Systems ◽  
Output Tracking ◽  
Non Linear ◽  
Variable Universe Fuzzy Control

This paper considers the output tracking problem for micro-electro-mechanical systems (MEMS) under uncertainties and external disturbances. The robust non-linear controllers are designed by two methods. The first method consists of a backstepping strategy combined with a first-order sliding mode controller. Also, in order to reduce the chattering effect and to improve the robustness of the proposed scheme, a new variable universe fuzzy control action with an adaptive coefficient is used instead of the signum function in the switching control law. In the proposed fuzzy scheme, the centres of the output membership functions are optimized via three heuristic optimization algorithms including the artificial bee colony (ABC) algorithm, ant colony optimization (ACO) and particle swarm optimization (PSO). In the second method, a class of second-order sliding mode controller is combined with the backstepping strategy. The second controller includes the proposed optimal fuzzy controllers of the first method. The stability of the closed-loop systems in both approaches are proved via the Lyapunov stability criterion and the conditions of stabilization are provided by linear matrix inequalities (LMIs). Numerical simulations are carried out to verify the theoretical results and to demonstrate the robust performance of the proposed controller in output tracking of the time-varying reference signal.

Feature Extraction Technology for Rolling Bearings Based on Local Tangent Space Alignment

2015 ◽  
Vol 764-765 ◽  
pp. 274-279
Author(s):  
Zhi Wen ◽  
Chen Lu ◽  
Hong Mei Liu
Keyword(s):  
Tangent Space ◽  
Feature Vector ◽  
Wavelet Packet ◽  
Linear Structure ◽  
Extraction Technology ◽  
Rolling Bearings ◽  
Time Frequency ◽  
Non Linear ◽  
Non Stationary Signal ◽  
Local Tangent

Health assessment and fault diagnosis for rolling bearings mostly adopt traditional methods, such as time-frequency, spectral, and wavelet packet analyses, to extract the feature vector. These methods are suitable for processing data with a linear structure. However, for the non-linear and non-stationary signal, the result of these methods is not ideal. Thus, this study proposes a suitable method to extract the feature vector in nonlinear signals. Local tangent space alignment of a manifold algorithm is employed to extract the feature vector from the rolling bearings. Results verify the advantage of the manifold algorithm for non-linear and non-stationary signals.

Motion-based active disturbance rejection control for a non-linear full-car suspension system

2017 ◽  
Vol 232 (5) ◽  
pp. 616-631 ◽  
Author(s):  
Panshuo Li ◽  
James Lam ◽  
Kie Chung Cheung
Keyword(s):  
Disturbance Rejection ◽  
Control Method ◽  
Reference Signal ◽  
Suspension System ◽  
Ride Quality ◽  
Active Disturbance Rejection Control ◽  
Active Disturbance Rejection ◽  
Car Suspension ◽  
Disturbance Rejection Control ◽  
Non Linear

This paper investigates the vibration attenuation problem of a non-linear full-car suspension system and aims to stabilize the vehicle attitude to provide a good ride quality. First, with respect to heave motion, pitch motion and roll motion, the full-car suspension system is separated into three interconnected subsystems. For each subsystem, corresponding motion-based controllers are designed to attenuate the vibrations of the sprung mass. A non-linear tracking differentiator is used to track the reference signal and to obtain its derivative. An extended state observer is established to estimate the total disturbance, which includes all the uncertainties and the external disturbance. Based on the principle of active disturbance rejection control, proportional–derivative and fuzzy proportional–derivative controllers are designed to control the resulting linear system with total disturbance compensation. Finally, four actuator forces are computed online using the three motion-based controllers obtained. Simulations are carried out in different road conditions; the results illustrate the merits of the proposed control method.

scholarly journals Feeding behavior and entrainment limits in the circadian system of the rat

1998 ◽  
Vol 275 (2) ◽  
pp. R372-R383 ◽  
Author(s):  
J. A. Madrid ◽  
F. J. Sánchez-Vázquez ◽  
P. Lax ◽  
P. Matas ◽  
E. M. Cuenca ◽  
...  
Keyword(s):  
Food Intake ◽  
Feeding Behavior ◽  
Feeding Activity ◽  
Circadian System ◽  
The Other ◽  
Masking Effect ◽  
Meal Frequency ◽  
Feeding Duration ◽  
Feeding Rhythms ◽  
Number Of Cycles

The entrainment limits of the circadian rhythms of feeding activity were studied in Wistar rats exposed to gradually increasing and decreasing or to static light-dark cycles. In the former, the entrainment limits of feeding behavior were 22 h 10 min and 26 h 40 min. In the latter, the upper limit was higher, because rats under zeitgeber period ( t) length = 27 h ( t27) and t28 met the criteria of entrainment. The lower limit, on the other hand, was not modified because none of the t22 animals showed entrained rhythms and one-half of the t23 rats exhibited two components in their circadian feeding rhythms, one with a period of 23 h and the other free running. This 23-h component reflected not only the masking effect of light-dark cycles but also seemed a true light-entrained component. In well-synchronized animals, food intake seemed to depend more on the number of cycles that the animal experienced than on actual time lived; however, other feeding parameters, such as meal frequency and feeding duration, remained constant when expressed per 24 h, irrespective of the t cycle. These results concerning feeding duration, meal frequency, and food intake revealed that the homeostatic and circadian controls interacted to a degree that depended on the type of variable considered. In conclusion, the entrainment limits appeared much more imprecise than they were previously thought to be, because the circadian system can only be partially synchronized near its entrainment limits. The hypothesis that the rat’s circadian system is composed of multiple oscillators with different intrinsic frequencies and varying capacities for light synchronization would explain the partial desynchronization observed near the entrainment limits.

Parallel Adaptive Neural Network Control of Robots

1994 ◽  
Vol 208 (4) ◽  
pp. 231-237 ◽  
Author(s):  
S S Ge ◽  
T H Lee
Keyword(s):  
Neural Network ◽  
Reference Signal ◽  
Network Control ◽  
Radial Basis Function Networks ◽  
Neural Network Control ◽  
Adaptive Neural Network ◽  
Linear Controller ◽  
Adaptive Neural Network Control ◽  
Non Linear ◽  
Asymptotic Tracking

In this paper, a parallel adaptive neural network (NN) control design for robots motivated by the work by Lee and Tan is presented. The controller is based on direct adaptive techniques and an approach of using an additional parallel NN to provide adaptive enhancements to a basic fixed controller, which can be either a NN-based non-linear controller or a model-based non-linear controller. It is shown that, if Gaussian radial basis function networks are used for the additional parallel NN, uniformly stable adaptation is assured and asymptotic tracking of the position reference signal is achieved.

Non-linear rolling friction of a tyre-caster system: analysis of a rugby wheelchair

2011 ◽  
Vol 225 (4) ◽  
pp. 1015-1020 ◽  
Author(s):  
J J C Chua ◽  
F K Fuss ◽  
A Subic
Keyword(s):  
Friction Coefficient ◽  
Wind Tunnel ◽  
System Analysis ◽  
Aerodynamic Drag ◽  
Rolling Friction ◽  
Constant Component ◽  
Wind Tunnel Experiments ◽  
Non Linear ◽  
The One ◽  
Rolling Friction Coefficient

Tyre-caster systems such as wheelchairs consist of several components with different bearing and rolling friction, with the latter depending on the tyre pressure. The aim of this study was to determine the rolling friction of a rugby wheelchair with deflated and maximally inflated tyres. The rolling friction was determined with coast-down tests by instrumenting the wheelchair with an accelerometer. As the energy loss of coasting down comes primarily from the rolling friction and aerodynamic drag, the latter (including the lift) was determined using wind tunnel experiments. The ratio of the sum of horizontal forces (drag and inertial) to the sum of vertical forces (lift and gravitational) determined the rolling friction coefficient. The rolling friction coefficient expressed as a function of the velocity was found to be highly non-linear, consisting of an initial viscous spike at low velocities, a constant component, and a parabolic component increasing with velocity. The rolling friction coefficient of the wheelchair with deflated tyres was on average three times higher than the one with maximally inflated tyres.

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