Feedback Term Research Articles

Demografik değişkenler açısından işgörenlerin Johari Penceresi modeli

Araştırmanın temel amacı, otel işletmelerinde işgörenlerin iletişim düzeylerini Johari Penceresi modeli ile incelemek, bulundukları iletişim boyutunu tespit etmek, Kişisel Açılım ve Geri Bildirim açısından demografik değişkenlere ait puan ortalamalarını karşılaştırmaktır. Veriler Antalya’da 5 yıldızlı otel işletmelerindeki işgörenlerden elden bırakma ve yüz yüze olarak anket formu aracılığıyla elde edilmiştir. Yapılan analizler sonucunda işgörenlerin açık alan içerisinde bir yoğunlaşma olduğu bulunmuştur. Cinsiyet, medeni durum, yaş, çalışma süresi değişkenleri açısından kişisel açılım boyutunda anlamlı bir farklılık bulunmamaktadır fakat öğrenim durumu açısından anlamlı bir farklılık vardır. Geri bildirim boyutunda ise medeni durum, yaş, öğrenim durumu değişkenleri açısından anlamlı bir farklılık bulunmaktadır fakat cinsiyet, çalışma süresi açısından anlamlı bir farklılık bulunmamaktadır.

Observer-based motion axis control for hydraulic actuation systems

Unknown dynamics including mismatched mechanical dynamics (i.e., parametric uncertainties, unmodeled friction and external disturbances) and matched actuator dynamics (i.e., pressure and flow characteristic uncertainties) broadly exist in hydraulic actuation systems (HASs), which can hinder the achievement of high-precision motion axis control. To surmount the practical issue, an observer-based control framework with a simple structure and low computation is developed for HASs. First, a simple observer is utilized to estimate mismatched and matched unknown dynamics for feedforward compensation. Then combining the backstepping design and adaptive control, an appropriate observer-based composite controller is provided, in which nonlinear feedback terms with updated gains are adopted to further improve the tracking accuracy. Moreover, a smooth nonlinear filter is introduced to shun the “explosion of complexity” and attenuate the impact of sensor noise on control performance. As a result, this synthesized controller is more suitable for practical use. Stability analysis uncovers that the developed controller assures the asymptotic convergence of the tracking error. The merits of the proposed approach are validated via comparative experiment results applied in an HAS with an inertial load as well.

Tactile Robotic Telemedicine for Safe Remote Diagnostics in Times of Corona: System Design, Feasibility and Usability Study.

The current crisis surrounding the COVID-19 pandemic demonstrates the amount of responsibility and the workload on our healthcare system and, above all, on the medical staff around the world. In this work, we propose a promising approach to overcome this problem using robot-assisted telediagnostics, which allows medical experts to examine patients from distance. The designed telediagnostic system consists of two robotic arms. Each robot is located at the doctor and patient sites. Such a system enables the doctor to have a direct conversation via telepresence and to examine patients through robot-assisted inspection (guided tactile and audiovisual contact). The proposed bilateral teleoperation system is redundant in terms of teleoperation control algorithms and visual feedback. Specifically, we implemented two main control modes: joint-based and displacement-based teleoperation. The joint-based mode was implemented due to its high transparency and ease of mapping between Leader and Follower whereas the displacement-based is highly flexible in terms of relative pose mapping and null-space control. Tracking tests between Leader and Follower were conducted on our system using both wired and wireless connections. Moreover, our system was tested by seven medical doctors in two experiments. User studies demonstrated the system's usability and it was successfully validated by the medical experts.

Examination of The Perceptions of Students Learning Arabic Language through Drawings

The Arabic language is one of the essential and lively communication languages of today's world, making it inevitable to benefit from new methods that will develop four basic language skills in an equal and balanced way in Arabic teaching. However, it is essential to determine how effective and appropriate this teaching is in terms of feedback. Therefore, this study aimed to examine the perceptions of 5th and 6th-grade students towards Arabic through the pictures they drew. Participants in the study were determined using the criterion sampling strategy. The research data consists of pictures drawn by 168 students about the Arabic language. The content analysis technique was used to analyze the obtained data. Student drawings were examined in five categories: theme, environment, human characters, tools and motifs, and expressions and symbols that reflect emotions. As a result of the evaluations, most students associate Arabic with foreign language and religious phenomena. At the same time, in light of the data obtained, it is concluded that the students have a favorable view of Arabic.

Adaptive Control of Time-Varying Parameter Systems With Asymptotic Tracking

A continuous adaptive controller is developed for nonlinear dynamical systems with linearly parameterizable uncertainty involving time-varying uncertain parameters. Through a unique stability analysis strategy, a new adaptive feedforward term is developed along with specialized feedback terms, to yield an asymptotic tracking error convergence result by compensating for the time-varying nature of the uncertain parameters. A Lyapunov-based stability analysis is shown for Euler–Lagrange systems, which ensures asymptotic tracking error convergence and boundedness of the closed-loop signals. Additionally, the time-varying uncertain function approximation error is shown to converge to zero. A simulation example of a two-link manipulator is provided to demonstrate the asymptotic tracking result.

Price Prediction Model for Restaurants In Istanbul By Using Machine Learning Algorithms

Today, companies have created new products based on data and accelerated the digitalization processes of businesses with the concept of data science. In this study, a price prediction model is proposed with machine learning algorithms by collecting the data of businesses in the food and beverage sector in Istanbul. In this study, different machine learning modeling algorithms such as XGBoost, Random Forest, Artificial Neural Network, K-Nearest Neighbor, Multi Linear Regression and CatBoost were used for restaurant price prediction. Classification algorithms were tested for price prediction, and as a result of the evaluation, it was observed that XGBoost algorithm achieve the highest performance with 0.023236 RMSE and 0.0005399 MSE error rates. By this study, business owners will be able to understand how new developments they will make in their businesses will benefit in terms of price and customer feedback. It will enable entrepreneurs to have information about what features a new business should have and the average price they will offer to their customers according to these features. In addition, entrepreneurs who want to open a restaurant will learn how much they should cost, provide price performance, and increase their profitability by selling more products because they will sell their products at affordable prices. Accurate pricing is one of the four important concepts of marketing. The company needs to make the right pricing in order to hold on and create customer loyalty.

Dynamic analysis and circuit realization of a novel variable-wing 5D memristive hyperchaotic system with line equilibrium

By introducing flux-controlled memristor and linear feedback term into the three-dimensional (3D) chaotic system, and using the state feedback control method to increase dimension, a novel variable-wing 5D memristive hyperchaotic system has been proposed in this paper. The proposed memristive hyperchaotic system has a line equilibrium point whose position is directly determined by the control parameter. The remarkable feature of the system is that the influence of positive feedback memristor and negative feedback memristor on the system and their similarities and differences are considered. Meanwhile, by analyzing the complex dynamic behavior of the system under different control parameters and initial values, it can be found that the proposed memristive hyperchaotic system shows many interesting phenomena including hidden extreme multistability, transient chaotic transition behavior and variable-wing characteristics. Finally, the hardware electronic circuit of the memristive hyperchaotic system is designed. The hardware experimental results are highly consistent with the numerical simulation ones, which demonstrate the physical realizability of the proposed system.

Preferences Amongst Radiation Oncology Residents for Virtual and In-Person Radiation Treatment Planning Review

<h3>Background</h3> Broadly, medical education e-learning is equivalent to in-person in student satisfaction, knowledge, skills, and outcomes. However, when e-learning is best used, and in what form is still being determined. For instance, e-learning with greater interactivity, practice, and feedback is associated with improved learner satisfaction and outcomes. Considering the computer-basis of radiation treatment planning, radiation oncology residents plausibly may prefer virtual treatment planning and review formats. We aimed to assess resident use of Virtual, In-Person, or a combination of Both review formats, to elicit their format preferences, and reasons for their preferences. We theorized virtual-preferring residents would endorse areas previously associated with enhanced e-learning outcomes more than in-person peers. <h3>Methods</h3> Online questionnaires were emailed to current PGY1-PGY5 residents in Canadian radiation oncology programs. Questionnaires examined level of training, typical review format, preferred format, and reasons for format preference. Chi-square tests compared differences in format preference and reasons for preference. <h3>Results</h3> 52 respondents were included for analysis; PGY1s were excluded due to limited treatment planning exposure. 76.9% of residents typically review with Both virtual and in-person formats, significantly more than 17.3% who review In-Person (p<0.0001) or 5.8% who review Virtually (p<0.0001). When asked which format they preferred, 44.2% preferred Virtual, 36.5% In-Person, and 19.2% preferred a combination of Both. Preference was significantly greater for Virtual versus Both (p=0.006) and In-Person versus Both (p=0.049). Reasons for preference were thematically grouped, reflecting focus upon Interactivity, Practice, Feedback, Convenience, and Teaching Quality. Significant differences were not found between In-Person and Virtual-preferring respondents in terms of Feedback, Interactivity, or Practice. However, significant within-group differences existed between Convenience versus Teaching Quality (Virtual-preferring: 84.3%>61%, p=0.0198; Both-preferring: 76.7%>40%, p=0.0324; In-person-preferring: 25%<63%, p=0.00214), and between Feedback versus Interactivity (Virtual-preferring: 66.7%>45.4%, p=0.0048; In Person-preferring: 59.7%>37%, p=0.00634). <h3>Discussion</h3> Our results suggest residents review contours and treatment plans with a combination of virtual and in-person formats, more than either format alone, despite low resident preference for this approach. While use of either format appears acceptable to residents, differences in emphasis on convenience with virtual-preferring and teaching quality in residents preferring in-person review suggests that educational priorities may differ between residents. Feedback more than interactivity seems important for residents irrespective of preferred format. Thus, residents and attendings should identify a format that best meets resident's educational needs and priorities. Further research should explore attending preferences.

Energy computation, infinitely coexisting patterns and their control from a Hindmarsh–Rose neuron with memristive autapse: Circuit implementation

An autapse is a particular synapse with its axon and dendrites interconnected. In this contribution, the effect of a memristive autapse is investigated on the dynamics of a 2D Hindmarsh–Rose neuron. The Hamilton energy of the proposed model is established using the Helmholtz theorem. It is found after monitoring the parameters that the frequency of the external current has no effect on the energy while only the memristive autapse strength and the amplitude of the stimuli are able to affect the energy released by the considered neuron. The study of the dynamics of the proposed model revealed exotic neuronal behaviors such as reverse period doubling route to chaos, and the phenomenon of interior and exterior crises. In addition, the striking phenomenon of homogeneous extreme multistability is captured. It is characterized by the coexistence of firing patterns with identical shapes for the same set of parameters. Of particular interest, a non-invasive control method exploiting a temporal feedback term is applied to enable the basin of attraction of all the undesired dynamics to merge with the desired one for a suitable value of the controller coupling strength. The electronic circuit of the proposed model is constructed and simulated in the PSpice environment. The obtained results match well with those from the direct investigations of the mathematical model of the introduced neuron.

Stability analysis of delayed-feedback control effect in the continuum traffic flow of autonomous vehicles without V2I communication

In this paper, a deterministic acceleration model is developed considering the sensor detection range to capture the underlying process of car following dynamic of autonomous vehicles. A delayed-feedback control is proposed using the difference between current state of throttle angle and previous one as feedback term and incorporated into the developed deterministic acceleration model to suppress the traffic congestion and increase the stability of traffic flow without the aid of Vehicle-to-Everything (V2I) communication. The feasible ranges of control parameters that ensure smooth traffic flow is derived from the perspective of the frequency domain via Hurvitz criteria and H∞ norm of transfer functions. The impact of proposed control strategy on the stability of macroscopic traffic flow is studied. The numerical-based simulations reveal that using the delayed-feedback of throttle angle with proper designed gains and delay time improves traffic efficiency, maintains scalable for large systems of autonomous vehicles, suppress the traffic congestion effectively, and dissipate shockwaves.

Preassigned-time bipartite synchronization of complex networks with quantized couplings and stochastic perturbations

By using the preassigned-time (PAT) control method, this paper considers bipartite synchronization of complex networks (CNs) with quantized couplings and stochastic perturbations. According to the characteristics of CNs and bipartite synchronization, a new controller is designed. In the controller, some control parameters are switched with the information of the error system, and the linear feedback term is not considered. Based on the properties of the Weiner process, a PAT criterion is given to guarantee the stochastic bipartite synchronization of CNs with a different Lyapunov function. In order to compare, a fixed-time control is designed and a synchronization criterion is also established. Moreover, experimental results effectively demonstrate the correctness of the theoretical analysis.

Modeling and Synchronized Control of a Dual-Drive “Checkerboard” Gantry With Composite Adaptive Feedforward and RISE Feedback

In this article, the design of a novel dual-drive “checkerboard” gantry is introduced with symmetric layout, rigid structure, and decoupled X–Y motion. However, its double redundantly actuated configuration and the strong interaxis coupling force challenges the coordinate motion and real-time force distribution between parallel axes. With consideration of stiffness of bearings, the dynamical model revealing the interaxis coupling effect due to asymmetric load from the moving platform is established. Thereby, the force allocation between pairs of parallel axes is naturally solved by the upcoming controller design. To compensate disturbance due to both structural and unstructural uncertainties, a 2-degree-of-freedom control scheme is proposed. It takes both tracking error and the model prediction error to update the dynamical model in real time, thus achieves an effective feedforward control without setting up the deadzone. Meanwhile, a rule is developed to tune the proportional-integral-derivative feedback term in the task-space control from its joint-space counterpart. Additionally, the robust integral of signum of error term is proposed with gain adaptation so that bandwidth of control is fine adjusted according to the velocity tracking error. Real-time experiments on the actual testbed indicate that both improvement of planar motion precision and prevention of parameter drifting over a large workspace are successfully achieved compared with the conventional control methods.

Dynamical Behavior of Fractional-Order Delayed Feedback Control on the Mathieu Equation by Incremental Harmonic Balance Method

In this study, the dynamical analysis of the Mathieu equation with multifrequency excitation under fractional-order delayed feedback control is investigated by the incremental harmonic balance method (IHBM). IHBM is applied to the fractional-order delayed feedback control system, and the general formulas of the first-order approximate periodic solution for the Mathieu equation are derived. Caputo’s definition is adopted to process the fractional-order delayed feedback term. The general formulas of this system are suitable for not only the weakly but also the strongly nonlinear fractional-order system. Through the analysis of the general formulas of this system, it shows that fractional-order delayed feedback control has two functions, which are velocity delayed feedback control and displacement delayed feedback control. Next, the numerical simulation of the system is carried out. The comparison between the approximate analytical solution and the numerical iterative result is made, and the accuracy of the approximate analytical result by IHBM is proved to be high. At last, the effects of the time delay, feedback coefficient, and fractional order are investigated, respectively. It is generally known that time delay is common and inevitable in the control system. But the fractional order can be used to adjust the influence caused by time delay in fractional-order delayed feedback control. Those new system characteristics will provide theoretical guidance to the design and the control of this kind system.

A Nonlinear Power Feedback Improvement of the Ship Course-Keeping Controller

In order to simplify the design process of the controller, improve the robustness of the system, and save the energy output of the controller, a controller improved by nonlinear feedback is designed. First of all, by constructing the Lyapunov function, the controller design process is simplified, and the nonlinear control law is avoided to cancel the nonlinear term of the system; then, the heading error processed by the power function is used to replace the nonlinear feedback term of the heading error itself; finally, the training ship “Yupeng” was used as an example for system simulation. Compared with the pure backstepping method, the simulation results show that the average energy cost of heading keeping of the proposed algorithm is reduced by 21.7%, and the maximum energy cost of heading tracking is reduced by 34.9%, with the strong anti-interference ability. Studies have shown that the introduction of nonlinear feedback terms can optimize the control system, save energy, and enhance robustness, which is of great significance in practical engineering applications.

Reduced-order intermediate variable observer based fault estimation and fault-tolerant control for fuzzy stochastic systems with exogenous disturbance

This paper studies fault estimation and fault-tolerant control problems for fuzzy systems with exogenous disturbance and stochastic noise. The fuzzy reduced-order intermediate variable observers and the disturbance observers are proposed to reconstruct the sensor fault, the actuator fault and the disturbance. According to the estimated results, the observer based fault-tolerant controllers are devised. Compared with the full-order observer design method, the designed reduced-order observers are with lower dimensions and less cost. Different from the classic intermediate observer, the feedback term of the output estimation error is introduced into our observers, which increases the design freedom. And the obtained linear matrix inequality conditions can ensure that the whole closed-loop systems are mean-square exponentially stable. Finally, two examples are offered to verify the feasibility of the proposed method.

THE USE OF RPMS - CLASSROOM OBSERVATION TOOL (COT), THE EDUCATIONAL MANAGEMENT AND THE LEVEL OF TEACHERS’ PROFICIENCY IN THE PROVINCE OF LAGUNA

The main purpose of this study was to determine the effectiveness of the use of classroom observation tool, educational management and teachers` proficiency in the Province of Laguna. This study used a descriptive method of research that involved the participation of two hundred thirty (230) teacher-respondents. The validated survey questionnaire containing ninety (90) items that covered factors related with the RPMS ? Classroom Observation Tool (COT). The level of the conduct of RPMS - Classroom Observation Tool (COT) in terms of feedback and support and in terms of monitoring and coaching were interpreted as highly evident among the respondents in the province of Laguna. The level of educational management as to curriculum, teaching-learning process, school management, organizational funding, and professional development were all attained a verbal interpretation as highly evident among the respondents. Furthermore, the level of teachers` instructional proficiency as to content mastery, instructional design skills, instructional delivery skills, instructional assessment skills, and classroom management were all verbally interpreted as highly evident among the respondents. Moreover, the level of teachers` professional competency as to speakership, as to research, as to awards/recognition, as to chairmanship, and as to coaching and mentoring were all interpreted verbally as highly evident. The findings and the result of the study also revealed that the use of Classroom Observation Tool (COT) in terms of Feedback and support were not observed to have significant effect to the teachers? instructional proficiency and to the teachers? professional competency. Moreover, the monitoring and coaching were also not observed to have significant effect to the teachers? instructional proficiency and professional competency. Therefore, the null hypothesis stating that ?The use of classroom observation tool (COT) has no significant effect on teachers? proficiency in the Province of Laguna? is accepted. On the other hand, in terms of Educational Management, the curriculum was not observed to have significant effect to the teachers? instructional proficiency but was observed to have significant effect to the teachers? professional competency. As to teaching-learning process, it was not observed to have significant effect to the teachers? instructional proficiency as well as to teachers` professional competency. Furthermore, school management were not observed to have significant effect to the teachers? instructional proficiency and to the teachers` professional competency. Moreover, organizational funding was not observed to have significant effect to the teachers? instructional proficiency as well as to the teachers` professional competency. And lastly, in terms of professional development, it was not observed to have significant effect to the teachers? instructional proficiency and to the teachers` professional competency. Therefore, the null hypothesis stating that ?The educational management has no significant effect on teachers? proficiency in the Province of Laguna? is accepted.

A Simple memristive chaotic system with complex dynamics and ITS image encryption application

In this paper, a new memristive chaotic system with a relatively simple structure and complex dynamic behavior is proposed by introducing an absolute memristor into the VB19 chaotic system as a positive feedback term. The analysis shows that the new system is a fractional dimensional dissipative system and is unstable at the line equilibrium point. The system’s dynamic characteristics are studied using a bifurcation diagram and Lyapunov exponent’s spectrum. The numerical simulation shows that the period-doubling bifurcation phenomenon occurs when changing the parameters and system change from period to chaos. When the initial condition changes, the dynamic evolution of the system indicates that the coexistence of multiple attractors and chaotic signals can be controlled by local amplitude. In addition, a new image encryption algorithm based on the system is designed and the performance of this algorithm is tested through numerical analyses. The system’s analog circuit is built using electronic components and also realized by the microprocessor. The circuit realization results consistent with the numerical simulation results are obtained to verify the physical existence of the system.

Cognitive Diagnostic Assessment of IELTS Listening: Providing Feedback from its Internal Structure

High stakes testing, such as IELTS, is designed to select individuals for decision-making purposes (Fulcher, 2013b). Hence, there is a slow-growing stream of research investigating the subskills of IELTS listening and, in feedback terms, its effects on individuals and educational programs. Here, cognitive diagnostic assessment (CDA) performs it through breaking down the abstract listening concepts into fine-grained subcomponents, and applying it to in-class assessment and teaching. Therefore, the strengths and weaknesses of language learners concerning various subsections of the IELTS listening test were explored with use of three CDMs, i.e., DINA, DINO and mixed DINA-DINO. As a result, the analysis of the participants’(N=463) performances revealed that the mixed-DINA-DINO model using the original Q-matrix was the most effective model. On the other hand, all three models indicated that gap-filling was cognitively less demanding than the other subsections. However, they did not show any agreement on multiple-choice sub-competency. Accordingly, it can be argued that the CDM-driven diagnostic information related to the sub-sections of the IELTS listening test can be used in educational systems to explore the underlying structure of a test and detect the learners’ potential strengths and weaknesses with mastery and non-mastery of the intended items.

Online Antiswing Trajectory Planning for a Practical Rubber Tire Container Gantry Crane

Rubber tire container gantry cranes (RTG) are the most commonly used equipments to stack containers in ports. With four sets of ropes hoisting the cargo, the system dynamics become much more complicated and unpredictable when compared with traditional gantry cranes, which imposes higher requirements to the skills of operators. During the delivering process, large sway motion of the container is often excited by inappropriate manual operations, which badly impairs efficiency and safety. This issue is made even worse when considering the elasticity of rubber tire, wind disturbances, and many other practical disturbances. To improve the working efficiency of ports, an automatic antiswing trajectory planning method is proposed for RTG in this article. Specifically, reference trajectories are first generated to ensure that the trolley/rope accurately reach the desired position. After that, appropriate feedback terms are incorporated to online optimize the trajectories, so that the container swing motion is sufficiently suppressed even under unfavorable conditions. Lyapunov-based analysis is presented to guarantee the correctness of our conclusion. Furthermore, extensive hardware experiments on a practical RTG are performed to demonstrate the efficiency of the proposed method. To our best knowledge, with concise structure and superior antiswing ability, the proposed method is one of the very few methods which can be successfully applied to the practical RTG systems.

An Output Feedback Controller for a Second-Order System Subject to Asymmetric Output Constraint Based on Lyapunov Function with Unlimited Domain

In this work, a new robust controller is designed for a second-order plant model, considering asymmetric output constraints. The tracking error convergence and output constraint are achieved by using a control law whose output feedback term is user-defined and bounded: it takes on large but finite and user-defined values for tracking error values equal to or higher than the constraint boundary, and it comprises a previously known user-defined function for tracking error values far from the constraint boundary. This is a significant contribution that remedies two important limitations of common output constraint control designs: the infinite control effort for tracking error equal to or higher than the constraint boundary, and the impossibility of using previously known user-defined functions in the output feedback function for tracking error values far from the constraint boundary. As another contribution, the control design is based on the dead-zone Lyapunov function, which facilitates the achievement of convergence to a compact set with user-defined size, avoidance of discontinuous signals in the controller, and robustness to model uncertainty or disturbances. The proposed output feedback term consists of the product between two functions of the tracking error, an increasing function and a sigmoid function, whose exact expressions are user-defined. Finally, the effectiveness of the developed controller is illustrated by the simulation of substrate concentration tracking in a continuous flow stirred bioreactor.