scholarly journals Design issues and performance analysis of CCM boost converters with RHP zero mitigation via inductor current sensing

2020 ◽  
Author(s):  
Mauro Leoncini ◽  
Salvatore Levantino ◽  
Massimo Ghioni
Keyword(s):  
Half Plane ◽  
Dynamic Performance ◽  
Tracking Error ◽  
Boost Converter ◽  
Design Guidelines ◽  
System Stability ◽  
Current Sensing ◽  
Practical Applications ◽  
The Right ◽  
The Impact

AbstractThe right-half plane (RHP) zero in the control to output voltage transfer function of a boost converter operating in the continuous conduction mode limits the loop bandwidth. By injecting a scaled version of the inductor current into the loop, it is possible to shift the zero from the right-half plane to the left-half plane, which leads to increased stability of the control loop. This solution generates a static voltage error at the output of the converter (tracking error), which may be unacceptable in practical applications. A few strategies to mitigate or correct this tracking error have been suggested. However, they have never been fully assessed. This paper thoroughly investigates the impact of the RHP zero mitigation technique on the dynamic performance of a boost converter, and identifies the complex trade-off between the system stability, transient response, and tracking error correction capability. Based on these findings, design guidelines are provided to help maximize system performance. A representative case study is considered to highlight the performance benefits and simulation results are presented to validate the analysis.

Investigation on the impact of nongeometric uncertainty in dynamic performance of serial and parallel robot manipulators

2018 ◽  
Vol 233 (10) ◽  
pp. 3487-3511 ◽  
Author(s):  
Ying-Kuan Tsai ◽  
Kuei-Yuan Chan
Keyword(s):  
Degrees Of Freedom ◽  
Robot Manipulators ◽  
Dynamic Performance ◽  
Uncertainty Modeling ◽  
Parallel Robot ◽  
Positional Error ◽  
Robot Manipulation ◽  
Practical Applications ◽  
Uncertainty Parameters ◽  
The Impact

Uncertainty in robot manipulations is a fundamental source of inaccuracy. Most nongeometric uncertainties is caused by the mechanical components of robot manipulators such as gear transmission systems and joints. This study integrates existing uncertainty models for practical applications of both three-degrees-of-freedom serial robot and parallel robot (closed-loop 5R mechanism). We first review the literature on uncertainty and existing methods for improving the precision of robot manipulation. For existing methods for uncertainty modeling: (1) the mathematical model of a harmonic drive considering kinematic error and compliance is derived; (2) joint clearance analysis that includes models of contact force and friction force is presented; (3) Archard’s wear model is used to estimate the effect of joint wear, based on which the geometry of joints is updated. Computer simulation is then used to demonstrate the application of the proposed method for serial and parallel robot manipulators. Simulations are used to examine the behavior of robot manipulators operating under uncertainty, with performance-evaluated positional error and trajectory error. The proposed method can provide some insight into nongeometric uncertainty in robot manipulations. The proposed methodology can be further used to improve the accuracy of robot manipulation under uncertainty by identifying uncertainty parameters.

Dynamic Analysis of a Rotor System Supported on Squeeze Film Damper with Air Entrainment

2017 ◽  
Vol 27 (14) ◽  
pp. 1750212 ◽  
Author(s):  
Wei Zhang ◽  
Bingbing Han ◽  
Kunpeng Zhang ◽  
Qian Ding
Keyword(s):  
Dynamic Performance ◽  
Air Entrainment ◽  
Rotor System ◽  
System Stability ◽  
Squeeze Film ◽  
Dynamical Response ◽  
Two Phase ◽  
Practical Applications ◽  
Rolling Ball ◽  
Frequency Components

Squeeze film dampers (SFDs) are widely used in compressors and turbines to suppress the vibration while traversing critical speeds. In practical applications, air ingestion from the outside environment and cavitation may lead to a foamy lubricant that weakens oil film damping and dynamic performance of rotor system. In this paper, a rigid rotor model is established considering both lateral and pitching vibration under different imbalance excitations to evaluate the effect of air entrainment on rotor system. Tests with three different imbalances are carried out on a rotor-SFD apparatus. Volume controlled air in mixture ranging from pure oil to all air are supplied to the SFD. The transient response of rotor is measured in the experiments. The results show that two-phase flow produces significant influence on the system stability and dynamical response. The damping properties are weakened by entrained air, such as the damping on high frequency components of rolling ball bearing. Super-harmonic resonance and bifurcation are observed, as well as the low frequency components due to air entrainment.

Fuzzy Logic Control of Constant Power Regulated Swash Plate Axial Piston Pumps

2001 ◽  
Author(s):  
S. A. Kassem ◽  
M. K. Bahr
Keyword(s):  
Fuzzy Logic ◽  
Fuzzy Logic Controller ◽  
Dynamic Performance ◽  
Pd Controller ◽  
Constant Power ◽  
Practical Applications ◽  
Axial Piston Pumps ◽  
Swash Plate ◽  
The Impact ◽  
Axial Piston

Abstract This paper presents a theoretical study of some aspects of the dynamics of electrically controlled constant power regulated swash plate axial piston pumps with conical cylinder blocks. The mathematical model of the pump is derived. Simulation of the pump dynamic characteristics is carried out when the controller is a conventional PD one used currently in practical applications. The good agreement between the simulation and the experimental results validates the derived model. A fuzzy logic controller (FZC) is proposed to replace the PD controller. The simulation results show that the FZC yields better dynamic performance and is more robust as compared with the PD controller. The FZC is also shown to reduce the oscillations of the proportional valve spool at each swash plate inclination angle, which increases the valve service life and reduces the generated heat in it. In case of pumps of large geometric volumes the FZC is found also to reduce the impact of the control piston at the end of the stroke.

scholarly journals The Role of Banking Concentration on Financial Stability

2021 ◽  
Vol 13 (6) ◽  
pp. 103
Author(s):  
Atellu Antony ◽  
Muriu Peter ◽  
Sule Odhiambo
Keyword(s):  
Financial Stability ◽  
Structural Equation ◽  
Global Financial Crisis ◽  
System Stability ◽  
Equation Modeling ◽  
Policy Makers ◽  
The Right ◽  
The Impact ◽  
Bank Concentration

Globally, financial instability is a major source of concern among policy makers and bank regulators, particularly after the 2007-09 global financial crisis. Motivated by inconsistent theoretical evaluations on the impact of bank concentration on the likelihood of a systemic banking crisis, this paper investigates the role of bank concentration on financial stability in Kenya with competition as an intervening variable. The novelity of this study lies on the use of structural equation modeling (SEM) in the analysis of direct and indirect effects of bank concentration on financial stability. Results show that higher concentration induces banks to increase cost of service provision which may aggravate credit risks and expose banks to systemic risks. Further, competition plays a significant role in ensuring financial system stability which supports the ‘competition-stabiliy’ hypothesis. Uncompetitive banking industry may therefore provide incentive for banks to take excessive risks, which renders them vulnerable to systematic risks. We also establish that tight regulations enhances concentration and financial stability but hinders competition. These new insights give bank regulators and policy makers an incentive to formulate and implement the right policies to improve financial stability.

Emotional Reactivity to Visual Content as Revealed by ERP Component Clustering

2015 ◽  
Vol 29 (4) ◽  
pp. 135-146 ◽  
Author(s):  
Miroslaw Wyczesany ◽  
Szczepan J. Grzybowski ◽  
Jan Kaiser
Keyword(s):  
Emotional Reactivity ◽  
Brain Activity ◽  
Affective State ◽  
Occipital Lobe ◽  
Stimulus Onset ◽  
Emotional States ◽  
Neural Basis ◽  
Temporoparietal Junction ◽  
The Right ◽  
The Impact

Abstract. In the study, the neural basis of emotional reactivity was investigated. Reactivity was operationalized as the impact of emotional pictures on the self-reported ongoing affective state. It was used to divide the subjects into high- and low-responders groups. Independent sources of brain activity were identified, localized with the DIPFIT method, and clustered across subjects to analyse the visual evoked potentials to affective pictures. Four of the identified clusters revealed effects of reactivity. The earliest two started about 120 ms from the stimulus onset and were located in the occipital lobe and the right temporoparietal junction. Another two with a latency of 200 ms were found in the orbitofrontal and the right dorsolateral cortices. Additionally, differences in pre-stimulus alpha level over the visual cortex were observed between the groups. The attentional modulation of perceptual processes is proposed as an early source of emotional reactivity, which forms an automatic mechanism of affective control. The role of top-down processes in affective appraisal and, finally, the experience of ongoing emotional states is also discussed.

The Impact of Internal Work Environment on the Retention of Healthcare Providers at Turaif General Hospital

2019 ◽  
Vol 10 (12) ◽  
pp. 1183-1199
Author(s):  
Mohammed Alrouili ◽  
Keyword(s):  
Work Environment ◽  
General Hospital ◽  
Professional Growth ◽  
Healthcare Providers ◽  
Entire Study ◽  
Internal Work ◽  
Research Findings ◽  
Study Population ◽  
The Right ◽  
The Impact

This study attempted to identify the impact of internal work environment on the retention of healthcare providers at Turaif General Hospital in the Kingdom of Saudi Arabia. In particular, the study aimed to identify the dimensions of work circumstances, compensation, and relationship with colleagues, professional growth, and the level of healthcare providers’ retention. In order to achieve the study goals, the researcher used the descriptive analytical approach. The researcher used the questionnaire as the study tool. The study population comprised all the healthcare providers at Turaif General Hospital. Questionnaires were distributed to the entire study sample that consisted of 220 individuals. The number of questionnaires valid for study was 183 questionnaires. The research findings were as follows: the participants’ estimate of the work circumstances dimension was high (3.64), the participants’ estimate of the compensation dimension was moderate (3.32), the participants’ estimate of the relationship with colleagues dimension was high (3.62), the participants’ estimate of the professional growth dimension was weak (2.39), and the participants’ estimate of healthcare providers’ retention level was intermediate (2.75). Accordingly, the researcher’s major recommendations are: the need to create the right atmosphere for personnel in hospitals, the interest of the hospital to provide the appropriate conditions for the staff in terms of the physical and moral aspects for building the work adjustment in the staff, and conducting training courses and educational lectures for personnel in hospitals on how to cope with the work pressures.

The Right to Housing: Challenges Associated with the ‘Waiting List System’ Ekurhuleni Metropolitan Municipality V Various Occupiers, Eden Park Extension 5 2014 3 SA 23 (SCA)

2017 ◽  
Vol 30 (1) ◽  
pp. 112-121
Author(s):  
Shamier Ebrahim
Keyword(s):  
Supreme Court ◽  
Waiting Lists ◽  
The State ◽  
Waiting List ◽  
Allocation Process ◽  
The Supreme Court ◽  
The Right ◽  
The Impact ◽  
Court Of Appeal

The right to adequate housing is a constitutional imperative which is contained in section 26 of the Constitution. The state is tasked with the progressive realisation of this right. The allocation of housing has been plagued with challenges which impact negatively on the allocation process. This note analyses Ekurhuleni Metropolitan Municipality v Various Occupiers, Eden Park Extension 51 which dealt with a situation where one of the main reasons provided by the Supreme Court of Appeal for refusing the eviction order was because the appellants subjected the unlawful occupiers to defective waiting lists and failed to engage with the community regarding the compilation of the lists and the criteria used to identify beneficiaries. This case brings to the fore the importance of a coherent (reasonable) waiting list in eviction proceedings. This note further analyses the impact of the waiting list system in eviction proceedings and makes recommendations regarding what would constitute a coherent (reasonable) waiting list for the purpose of section 26(2) of the Constitution.

Global tolerance and its impact on peace

2019 ◽  
pp. 247-284
Author(s):  
م.د.فاتن محمد رزاق
Keyword(s):  
Islamic Law ◽  
Mutual Recognition ◽  
International Community ◽  
World Peace ◽  
Clash Of Civilizations ◽  
Democracy And Education ◽  
Moral Necessity ◽  
International Identity ◽  
The Right ◽  
The Impact

The concept of tolerance is gaining its importance in the midst of an international society suffering from violence, wars and internal and international crises. It is practiced by extremist and extremist forces and movements acting in the name of religion to exclude the different Muslim and non-Muslim people according to the unethical practices and methodologies of Islamic law and reality. , Cultural, civilization .. that distinguish our world today. The society today is suffering from the ideas of the intellectual and aesthetic views of the different ideologically, ethnically, culturally and religiously in the world of the South. This is what the end-of-history thesis of Fukuyama and the clash of civilizations represented to Huntington. Therefore, it is necessary to confront these extremist and extremist ideas and behaviors. Peace, security and freedom in the international community of justice and equality, needs to be addressed intellectual, cultural, moral and political before they are legal, these treatments are based on dialogue and cooperation and trust and respect and mutual recognition and tolerance so we find the importance of tolerance to The international community is concerned about the need for mechanisms that confront terrorism and violence with an ideology based on respect for the right of diversity, diversity and pluralism. Accordingly, tolerance is a political, cultural and moral necessity based on international legal foundations represented by the United Nations. Through its conferences, declarations and international resolutions issued by it and its specialized agencies, culminating in the Universal Declaration of Tolerance and the International Day of International Peace, and the political foundations represented by democracy and global citizenship that respects all identities and seeks to respect the rights of other identities under the umbrella of international identity Nsanhuahdh respects everyone, a society with a humanitarian goal of a global civil and Ahdlaaaraf borders and the identity of certain Qomahdolh, cultural and educational foundations through plans and programs with educational encourage a spirit of tolerance and world peace. The study was divided into three topics: the first dealt with the concept of tolerance and world peace, and the second topic dealt with the impact of international law and citizenship. In the promotion of world peace "as one of the elements of global tolerance. The last topic included" the role of democracy and education education "in the promotion of world peace and concluded the study by conclusion.

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