The Impact of Return Orifices on the Stability of a Four-Way Valve–Controlled Double-Acting Actuator

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
Shusen Zhang
Keyword(s):  
Nonlinear System ◽  
Nonlinear Model ◽  
Stability Boundary ◽  
Stable Limit ◽  
Limit Circle ◽  
Spring Rate ◽  
Valve Spring ◽  
System A ◽  
The Stability ◽  
The Impact

This paper studies the influence of the return and the valve spring rate on the stability of a four-way valve–controlled double-acting actuator. A fully nonlinear model for this system is developed based on the orifice equation. The new model contains both the upstream chamber and downstream chamber for each orifice. The geometry of the return orifice and the valve spring rate has an impact on the stability boundary of the four-way valve–controlled double-acting actuator. A larger return orifice requires using a stronger valve spring to ensure the stability of the system. It is shown that, for the nonlinear system, a stable limit circle can be born from an unstable origin as bifurcation occurs.

Fear Induced Stabilization in an Intraguild Predation Model

2020 ◽  
Vol 30 (04) ◽  
pp. 2050053
Author(s):  
Mainul Hossain ◽  
Nikhil Pal ◽  
Sudip Samanta ◽  
Joydev Chattopadhyay
Keyword(s):  
Growth Rate ◽  
Hopf Bifurcation ◽  
Intraguild Predation ◽  
Equilibrium Points ◽  
Stable Limit ◽  
Interior Equilibrium ◽  
The Rich ◽  
The Stability ◽  
The Cost ◽  
The Impact

In the present paper, we investigate the impact of fear in an intraguild predation model. We consider that the growth rate of intraguild prey (IG prey) is reduced due to the cost of fear of intraguild predator (IG predator), and the growth rate of basal prey is suppressed due to the cost of fear of both the IG prey and the IG predator. The basic mathematical results such as positively invariant space, boundedness of the solutions, persistence of the system have been investigated. We further analyze the existence and local stability of the biologically feasible equilibrium points, and also study the Hopf-bifurcation analysis of the system with respect to the fear parameter. The direction of Hopf-bifurcation and the stability properties of the periodic solutions have also been investigated. We observe that in the absence of fear, omnivory produces chaos in a three-species food chain system. However, fear can stabilize the chaos thus obtained. We also observe that the system shows bistability behavior between IG prey free equilibrium and IG predator free equilibrium, and bistability between IG prey free equilibrium and interior equilibrium. Furthermore, we observe that for a suitable set of parameter values, the system may exhibit multiple stable limit cycles. We perform extensive numerical simulations to explore the rich dynamics of a simple intraguild predation model with fear effect.

Modeling Software Patch Management Based on Vulnerabilities Discovered

2019 ◽  
Vol 27 (02) ◽  
pp. 2040003 ◽  
Author(s):  
Adarsh Anand ◽  
Navneet Bhatt ◽  
Deepti Aggrawal
Keyword(s):  
Real Life ◽  
Integrative Approach ◽  
Software System ◽  
System A ◽  
Novel Approach ◽  
Time Period ◽  
Modeling Software ◽  
Vulnerability Discovery ◽  
The Stability ◽  
The Impact

A software system deals with various security implications after its release in the market. Correspondingly, firm releases security patches to counter those flaws discovered in the software system. A vendor releases a patch only if a vulnerability has been discovered in a software. It is an important aspect that encompasses the prediction of potential number of patches to be released to maintain the stability of a software. Vulnerability Discovery Models (VDMs) help a software vendor to acknowledge the security trends, forecast security investments and to plan patches, but very few attempts have been made to model the Vulnerability Patch Modeling (VPM) based on the impact of vulnerabilities discovered over the time period. In this proposal, we deduce a novel approach that addresses trend in the sequential development of patches based on the vendor or reporters fetching out the vulnerabilities in a software. The vulnerability trends in a software significantly affect the discovery process and later trigger a patch deployment to suppress the possible likelihood of a breach. The integrative approach underlines the association of vulnerability patch modeling with the vulnerability discovery phenomenon. To exemplify the proposed systematic structure, a statistical analysis has been conducted using real life vulnerability and patch datasets.

THE ROLE OF ADDITIONAL FOOD IN A PREDATOR–PREY MODEL WITH A PREY REFUGE

2016 ◽  
Vol 24 (02n03) ◽  
pp. 345-365 ◽  
Author(s):  
SUDIP SAMANTA ◽  
RIKHIYA DHAR ◽  
IBRAHIM M. ELMOJTABA ◽  
JOYDEV CHATTOPADHYAY
Keyword(s):  
Stable Equilibrium ◽  
Predator Population ◽  
Stable Limit ◽  
Prey Refuge ◽  
Additional Food ◽  
Predator Prey ◽  
Predator Prey Model ◽  
Prey Model ◽  
The Stability ◽  
The Impact

In this paper, we propose and analyze a predator–prey model with a prey refuge and additional food for predators. We study the impact of a prey refuge on the stability dynamics, when a constant proportion or a constant number of prey moves to the refuge area. The system dynamics are studied using both analytical and numerical techniques. We observe that the prey refuge can replace the predator–prey oscillations by a stable equilibrium if the refuge size crosses a threshold value. It is also observed that, if the refuge size is very high, then the extinction of the predator population is certain. Further, we observe that enhancement of additional food for predators prevents the extinction of the predator and also replaces the stable limit cycle with a stable equilibrium. Our results suggest that additional food for the predators enhances the stability and persistence of the system. Extensive numerical experiments are performed to illustrate our analytical findings.

On the Dynamical Systems Stability Control and Applications

2014 ◽  
Vol 555 ◽  
pp. 361-368
Author(s):  
Marcel Migdalovici ◽  
Daniela Baran ◽  
Gabriela Vlădeanu
Keyword(s):  
Dynamical System ◽  
Dynamical Systems ◽  
Nonlinear System ◽  
Stability Control ◽  
Necessary Condition ◽  
Linear Dynamical Systems ◽  
System A ◽  
First Approximation ◽  
Free Parameters ◽  
The Stability

The stability control analyzed by us, in this show, is based on our results in the domain of dynamical systems that depend of parameters. Any dynamical system can be considered as dynamical system that depends of parameters, without numerical particularization of them. All concrete dynamical systems, meted in the specialized literature, underline the property of separation between the stable and unstable zones, in sense of Liapunov, for two free parameters. This property can be also seen for one or more free parameters. Some mathematical conditions of separation between stable and unstable zones for linear dynamical systems are identified by us. For nonlinear systems, the conditions of separation may be identified using the linear system of first approximation attached to nonlinear system. A necessary condition of separation between stable and unstable zones, identified by us, is the sufficient order of differentiability or conditions of continuity for the functions that define the dynamical system. The property of stability zones separation can be used in defining the strategy of stability assurance and optimizing of the parameters, in the manner developed in the paper. The cases of dynamical systems that assure the separations of the stable and unstable zones, in your evolution, and permit the stability control, are analyzed in the paper.

An Investigation of an Impact Vibration Absorber

1967 ◽  
Vol 89 (4) ◽  
pp. 653-657 ◽  
Author(s):  
D. M. Egle
Keyword(s):  
Approximate Expression ◽  
Small Mass ◽  
Vibration Absorber ◽  
Primary System ◽  
Maximum Displacement ◽  
State Response ◽  
System A ◽  
The Stability ◽  
The Impact ◽  
Impact Vibration

The impact vibration absorber consists of a small mass, moving unidirectionally, impacting against the ends of a container which is rigidly attached to the primary vibrating system. A simplified theory for the forced steady-state response of a linear, single-degree-of-freedom system with an impact vibration absorber is presented. The assumption of two impacts per cycle at equal time intervals is known to lead to two possible solutions near the resonant frequency of the primary system. A criterion for determining the stability of the solutions is developed. An approximate expression for the maximum displacement of the primary system is given and the theory is compared to experimental results.

scholarly journals Adaptive Control for a Class of Nonlinear System with Redistributed Models

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Haisen Ke ◽  
Jiang Li
Keyword(s):  
Adaptive Control ◽  
Nonlinear System ◽  
Adaptive Controller ◽  
Multiple Models ◽  
Multiple Model ◽  
Transient Performance ◽  
Feedback Form ◽  
System A ◽  
Multiple Model Adaptive Control ◽  
The Stability

Multiple model adaptive control has been investigated extensively during the last ten years in which the “switching” or “switching and tuning” have emerged as the mainly approaches. It is the “switching” that can improve the transient performance to some extent and also make it difficult to analyze the stability of the system with multiple models adaptive controller. Towards this goal, this paper develops a novel multiple models adaptive controller for a class of nonlinear system in parameter-strict-feedback form which not only improves the transient performance significantly, but also guarantees the stability of all the states of the closed-loop system. A simulation example is proposed to illustrate the effectiveness of the developed multiple models adaptive controller.

scholarly journals Research on Applicability of the Practical Transient Voltage Stability Criterion Based on Voltage Magnitude and Sag Duration

2021 ◽  
Vol 11 (10) ◽  
pp. 4569
Author(s):  
Guoteng Wang ◽  
Zheng Xu ◽  
Zheren Zhang
Keyword(s):  
Power Systems ◽  
Voltage Stability ◽  
Stability Boundary ◽  
Theoretical Derivation ◽  
System A ◽  
Transient Voltage Stability ◽  
Practical Engineering ◽  
Transient Voltage ◽  
The Stability ◽  
Application Scope

Voltage sags threaten the transient voltage stability of power systems. To evaluate the transient voltage stability, practical criteria based on voltage magnitude and sag duration are widely used in practical engineering. However, the applicability of practical criteria needs to be studied. In this paper, in a single-load system, a theoretical derivation was first made to obtain the transient voltage stability boundary. Then, by studying the relationship between the practical criteria and the stability boundary, the application scope of the practical criteria was determined. The application scope described in this paper can guide operators to use the practical criteria correctly and avoid misjudgment of the transient voltage stability as much as possible. Finally, a case study based on PSCAD/EMTDC is presented, and the simulation results verified the conclusions proposed in this paper.

Research of the Adaptation of Turbine Model Related to the Grid

2014 ◽  
Vol 960-961 ◽  
pp. 1437-1441
Author(s):  
Ge Jin ◽  
Shu Chang Liu ◽  
Yu Jia Ma
Keyword(s):  
Power System ◽  
Rapid Development ◽  
System Stability ◽  
System A ◽  
The Stability ◽  
Turbine Speed ◽  
The Impact ◽  
Safety And Stability ◽  
Important Basis ◽  
Turbine Model

With the rapid development of China's interconnected power grid, power system operation environment has become increasingly complex. The safety and stability of the power system requirements are also increasing. Turbine is an important basis for the analysis of power system stability. This paper studied the influence of turbine parameters related to network on the stability of the grid from the perspective of the frequency domain, and obtained the impact properties of turbine speed control system parameters related to different oscillation frequency of the power system. The conclusions are validated from time domain. So that when analyzing the stability of the power system, a more targeted turbine model according to different research purposes can be chosen because the parameters’ importance can show the necessity of the modules.

scholarly journals Evaluation of the impact of food technology on the allergenicity of cow’s milk proteins

1999 ◽  
Vol 58 (3) ◽  
pp. 587-592 ◽  
Author(s):  
M. Heyman
Keyword(s):  
Immune System ◽  
Milk Proteins ◽  
Food Proteins ◽  
Complex Interactions ◽  
System A ◽  
Food Antigens ◽  
Système Immunitaire ◽  
The Stability ◽  
The Individual ◽  
The Impact

The quantitative evaluation of the allergenicity of food proteins and the clinical tolerance towards antigens are problems the food industry and the clinicians have to face. The allergenicity of a protein depends on multiple factors, including the stability to digestion and the interaction with the intestinal environment. In addition to the possible reduction in allergenicity by technological treatments such as heat and enzymic hydrolysis, the complex interactions existing between the antigens, the intestinal epithelium and the underlying immune system, as well as the individual susceptibility to the sensitizing epitopes, have to be taken into account. Indeed, the intestinal cells are able to take up and process proteins, and possibly to present them directly to mucosal lymphocytes. On the other hand, pathophysiological conditions can modify the interactions between food antigens and the immune system. A large number of methods has been developed to assess the residual antigenicity of food proteins, based on the various immune responses leading to intestinal or extradigestive pathologies. Thus, the difficulty in measuring the residual allergenicity of hypoallergenic formulas is partly due to the physiology of the gastrointestinal tract, since an intricate network of interactions between enterocytes and immune cells governs the development of the immune response to food antigens. RésuméL’évaluation de l’allergénicité des aliments et leur bonne tolérance clinique est une question touchant à la fois les industriels de l’agro-alimentaire et les cliniciens. L’allergénicité d’une protéine dépend de multiples facteurs parmi lesquels la résistance à la digestion, les interactions avec le tractus digestif et les facteurs environnementaux. L’allergénicité d’un produit alimentaire peut être modifiée non seulement par les traitements technologiques industriels, mais aussi par le tractus gastrointestinal. La susceptibilité individuelle aux epitopes peptidiques formés est également un facteur primordial. En effet, les interactions complexes existant entre les antigènes, l’épithelium intestinal et le système immunitaire muqueux peuvent conduirent à des réponses immunitaires différentes selon les individus. De nombreuses méthodes existent pour mesurer l’antigénicité résiduelle des aliments, basées sur la nature des différentes réactions immunitaires anormales conduisant à une pathologie intestinale ou extradigestive. La difficulté de mesurer l’allergénicité résiduelle de formules hypoallergéniques repose donc sur les relations complexes entre les antigènes alimentaires, l’épithelium intestinal et le système immunitaire muqueux.

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