The Early Development of Control Theory

1976 ◽  
Vol 98 (2) ◽  
pp. 109-118 ◽  
Author(s):  
A. T. Fuller
Keyword(s):  
Control Theory ◽  
Closed Loop ◽  
Block Diagram ◽  
Feedback System ◽  
Nyquist Diagram ◽  
System A ◽  
Integral Action ◽  
History Of ◽  
History Of Control ◽  
Diagram Techniques

The early history of control theory is explored, beginning with the contributions of Hooke and Huygens in the seventeenth century, and ending with Airy’s papers of 1840 and 1851. It is argued that, despite appearances to the contrary, Huygens’ speed control system is actually a feedback system. A proof is given that the Huygens-Hooke parabolic governor has integral action, thus eliminating offset. A detailed exposition of Airy’s techniques is given. It is shown that he used a disguised form of linearization. Airy’s system is also investigated using block diagram and Nyquist diagram techniques. The centrifugal governor is shown to have a tendency to resonance which adversely affects closed-loop stability; in agreement with Airy’s findings. Biographical notes on the main contributors are included in order to bring out the background and motivations of their theories.

The Early Development of Control Theory. II

1976 ◽  
Vol 98 (3) ◽  
pp. 224-235 ◽  
Author(s):  
A. T. Fuller
Keyword(s):  
Control Theory ◽  
Control Systems ◽  
Early Development ◽  
Speed Control ◽  
Integral Control ◽  
History Of ◽  
History Of Control

In a previous paper Airy’s contributions to control theory were reviewed, and the developments in control which led up to Airy’s 1840 paper were summarized. The present paper continues the investigation into the history of control theory, and is mainly concerned with Maxwell’s paper of 1868. A preliminary background study deals with the development of integral control during 1837–1868. Then an expanded version is given of Maxwell’s rather terse exposition of stability of speed control systems.

Closed Loop Vibrational Control: Theory and Applications

1993 ◽  
Author(s):  
Semyon M. Meerkov ◽  
Pierre T. Kabamba ◽  
Eng-Kee Poh
Keyword(s):  
Control Theory ◽  
Closed Loop ◽  
Vibrational Control

DETERMINING ROBUST PARAMETERS IN STABILIZING SET OF BACKSTEPPING BASED NONLINEAR CONTROLLER FOR SHIP COURSE KEEPING

2021 ◽  
Vol 158 (A3) ◽  
Author(s):  
X K Zhang ◽  
G Q Zhang
Keyword(s):  
Closed Loop ◽  
Simulation Experiment ◽  
Empirical Knowledge ◽  
Backstepping Method ◽  
Nonlinear Controller ◽  
Closed Loop System ◽  
Robust Performance ◽  
System A ◽  
Uniformly Asymptotic Stability ◽  
Novel Method

In order to solve the problem that backstepping method cannot effectively guarantee the robust performance of the closed-loop system, a novel method of determining parameter is developed in this note. Based on the ship manoeuvring empirical knowledge and the closed-loop shaping theory, the derived parameters belong to a reduced robust group in the original stabilizing set. The uniformly asymptotic stability is achieved theoretically. The training vessel “Yulong” and the tanker “Daqing232” are selected as the plants in the simulation experiment. And the simulation results are presented to demonstrate the effectiveness of the proposed algorithm.

scholarly journals Association of family risk and lifestyle/comorbidities in ovarian cancer patients

2015 ◽  
Vol 61 (3) ◽  
pp. 234-239 ◽  
Author(s):  
Natália Teixeira ◽  
Maria Aparecida Azevedo Koike Folgueira ◽  
Simone Maistro ◽  
Giselly Encinas ◽  
Geertruida Hendrika de Bock ◽  
...  
Keyword(s):  
Ovarian Cancer ◽  
Mutation Detection ◽  
Regression Analyses ◽  
Family Risk ◽  
Familial Predisposition ◽  
Factors Associated ◽  
System A ◽  
History Of ◽  
Psychiatric Conditions ◽  
The Impact

Summary Objectives: to analyze factors that might indicate familial predisposition for ovarian cancer in patients diagnosed with this disease. Methods: in a prospective single center cohort study at the Institute of Cancer of the State of São Paulo (ICESP), 51 women diagnosed with ovarian cancer were included. Familial predisposition for ovarian cancer was defined as having a higher than 10% chance of having a BRCA1/2 mutation according to the Manchester scoring system, a validated method to assess the likelihood of mutation detection. Each patient was interviewed with a standardized questionnaire on established risk factors for ovarian cancer and other factors that might influence the risk to develop ovarian cancer. Logistic regression analyses were performed to estimate the impact of the evaluated factors on the likelihood of mutation detection, by calculating odds ratios and 95% confidence intervals. Results: seventeen out of 51 patients had a family history of breast and/or ovarian cancer, four patients had a history of breast or endometrial cancer, 11 were diagnosed before the age of 50, and 12 presented a risk of familial predisposition to ovarian cancer higher than 10%. Patients with comorbidities, such as hypertension, diabetes, hormonal disorders, dyslipidemia and psychiatric conditions, presented a lower chance of having a familial predisposition for ovarian cancer (OR: 0.22; 95% CI: 0.06-0.88; p=0.03). Conclusion: in this study, having comorbidities was associated with a lower risk of having a familial predisposition for ovarian cancer. Other factors associated with the risk of ovarian cancer did not have an impact on this predisposition.

scholarly journals Features of Implementation of the System of Assessing the Security of Critically Important and Potentially Hazardous Objects Based on the Clements-Hofman Method

2019 ◽  
Vol 16 (4) ◽  
pp. 169
Author(s):  
I M Yannikov ◽  
M V Telegina
Keyword(s):  
Block Diagram ◽  
The State ◽  
Security System ◽  
Functional Diagram ◽  
Stages Of Development ◽  
System A ◽  
Protection Mechanisms

The paper assesses the existing approaches to the problem of assessing the security of hazardous facilities. It is proposed to carry out an assessment using the system of modeling and calculating the state of protection of hazardous objects developed on the basis of the Clements-Hoffman method, in which a set of threats, protection mechanisms and objects of protection are used to describe the system of protection with full overlap. This system can be used to calculate any type of protection of hazardous objects when entering data on any threats and appropriate means of protection. The paper provides a block diagram of the security system, a functional diagram, the main parameters and stages of development and testing.

scholarly journals Patterns of smallpox mortality in London, England, over three centuries

PLoS Biology ◽  
2020 ◽  
Vol 18 (12) ◽  
pp. e3000506
Author(s):  
Olga Krylova ◽  
David J. D. Earn
Keyword(s):  
Public Health ◽  
Infectious Disease ◽  
Time Series ◽  
Spectral Analysis ◽  
Infectious Diseases ◽  
Health Policies ◽  
Human Populations ◽  
Public Health Policies ◽  
History Of ◽  
History Of Control

Smallpox is unique among infectious diseases in the degree to which it devastated human populations, its long history of control interventions, and the fact that it has been successfully eradicated. Mortality from smallpox in London, England was carefully documented, weekly, for nearly 300 years, providing a rare and valuable source for the study of ecology and evolution of infectious disease. We describe and analyze smallpox mortality in London from 1664 to 1930. We digitized the weekly records published in the London Bills of Mortality (LBoM) and the Registrar General’s Weekly Returns (RGWRs). We annotated the resulting time series with a sequence of historical events that might have influenced smallpox dynamics in London. We present a spectral analysis that reveals how periodicities in reported smallpox mortality changed over decades and centuries; many of these changes in epidemic patterns are correlated with changes in control interventions and public health policies. We also examine how the seasonality of reported smallpox mortality changed from the 17th to 20th centuries in London.

scholarly journals Sole Mate: Safe Path-Finding by Obstacle Detection and Distance Estimation for the Blind

2019 ◽  
Vol 8 (6S4) ◽  
pp. 50-54
Keyword(s):  
Haptic Feedback ◽  
Distance Estimation ◽  
Feedback System ◽  
Obstacle Detection ◽  
Video Footage ◽  
System A ◽  
The World ◽  
Distance Sensor ◽  
Visually Challenged ◽  
Additional Device

The world has increased its demand for assistive technology (AT). There are a lot of researches and developments going on with respect to AT. Among the AT devices which are being developed, the need for a reliable and less expensive device which serves as an assistance for a visually challenged person is in serious demand all around the world. We, therefore, intend to provide a solution for this by constructing a device that has the capability to detect the obstacles within a given range for a visually challenged person and alerting the person about the obstacles. This involves various components like a camera for image detection, an ultrasonic distance sensor for distance estimation and a vibration motor which works on the principle of Haptic feedback and rotates with varied intensities depending on how far the obstacle is from the user. This paper presents a model which is a part of the footwear of the user and hence, no additional device is required to hold onto for assistance. The model involves the use of a microcontroller, a camera, to dynamically perceive the obstacles and a haptic feedback system to alert the person about the same. The camera dynamically acquires the real time video footage which is further processed by the microcontroller to detect the obstacles. Simultaneously, one more algorithm is being executed to estimate the distance with the help of an ultrasonic distance sensor. Depending on the distance, the frequency of the vibration motor, which acts as the output for notifying the user about the obstacle, is varied (haptic feedback). With this system, a visually challenged person will be able to avoid the obstacles successfully without the use of any additional device.

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