Feedback Channel Research Articles

Time-Varying Formation Predictive Control of Second-Order Networked Multi-Agent Systems With Three-Channel Random Communication Constraints

This paper presents a time-varying formation tracking control scheme for second-order networked multi-agent systems with random network-induced delays and packet losses. Three types of communication channels are considered: the feedback and forward channels of each agent as well as the channels between agents. To mitigate the adverse effects of the three-channel communication constraints, a novel distributed predictive control scheme is proposed by combining the networked predictive control approach and the time-delay system approach. Then, the stability condition for the resulting closed-loop time-delay system is derived via the Lyapunov theory, which is independent of the random communication constraints in the forward and feedback channels. Finally, comparative simulation results verify the superiority of the proposed scheme.

Coexisting and cooperating light–matter interaction regimes in a polaritonic photovoltaic system

Common quantum frameworks of light–matter coupling demonstrate the interaction between an atom and a cavity occurring through a single feedback channel: an exciton relaxes by emitting a photon that is stored in the cavity for several roundtrips before being re-absorbed to create another exciton, and so on. However, the possibility for the excited system to relax through two different channels belonging to two different regimes has been, until now, neglected. Here, we investigate the case in which the strong coupling regime and the photovoltaic effect cooperate to enhance the wavelength-dependent photocurrent conversion efficiency (defined as the incident photons to converted electrons ratio, namely the external quantum efficiency—EQE) of a photovoltaic cell specifically engineered to behave as an optical cavity tuned to the excitonic transition of the embedded active material (CH3NH3PbI3 perovskite). We exploit the angular dispersion of such photovoltaic cell to show that when the cavity mode approaches the energy of the exciton, the strong coupling regime is achieved and the EQE is significantly enhanced with respect to a classic configuration serving as a benchmark. Our findings do not aim at demonstrating an immediate impact in enhancing the performance of photovoltaic systems but, rather, constitute a proof-of-principle experimental demonstration of how the photovoltaic effect can benefit from the generation of polaritons. Nonetheless, such a peculiar cooperating dual-light–matter interaction could be exploited in future polaritonic photovoltaic architectures.

The experiences of COVID-19 preprint authors: a survey of researchers about publishing and receiving feedback on their work during the pandemic.

The COVID-19 pandemic caused a rise in preprinting, triggered by the need for open and rapid dissemination of research outputs. We surveyed authors of COVID-19 preprints to learn about their experiences with preprinting their work and also with publishing their work in a peer-reviewed journal. Our research had the following objectives: 1. to learn about authors' experiences with preprinting, their motivations, and future intentions; 2. to consider preprints in terms of their effectiveness in enabling authors to receive feedback on their work; 3. to compare the impact of feedback on preprints with the impact of comments of editors and reviewers on papers submitted to journals. In our survey, 78% of the new adopters of preprinting reported the intention to also preprint their future work. The boost in preprinting may therefore have a structural effect that will last after the pandemic, although future developments will also depend on other factors, including the broader growth in the adoption of open science practices. A total of 53% of the respondents reported that they had received feedback on their preprints. However, more than half of the feedback was received through "closed" channels-privately to the authors. This means that preprinting was a useful way to receive feedback on research, but the value of feedback could be increased further by facilitating and promoting "open" channels for preprint feedback. Almost a quarter of the feedback received by respondents consisted of detailed comments, showing the potential of preprint feedback to provide valuable comments on research. Respondents also reported that, compared to preprint feedback, journal peer review was more likely to lead to major changes to their work, suggesting that journal peer review provides significant added value compared to feedback received on preprints.

Volunteer omnichannel behavior in nonprofit organizations: Key antecedents and implications for management

AbstractThe purpose of this research consists of identifying the antecedents that may influence the adoption of omnichannel behavior by volunteers. This behavior can be understood as the interchangeable use of online and offline channels, providing volunteers with multiple contact points with nonprofit organizations. To this end, we first propose a conceptual model based on Clary et al.'s motivations framework and other relevant literature. Second, we test our model through quantitative‐based research, employing an online questionnaire with a representative sample of 7822 volunteers working for the Spanish Red Cross. We then carry out a hierarchical cluster analysis to group similar volunteers into clusters according to the use they make of the different offline and online channels, followed by an ordered logistic regression analysis to test the hypotheses proposed. First, two volunteer profiles are identified: offline‐oriented volunteers with low or no omnichannel behavior, and online‐oriented volunteers with high or very high omnichannel behavior. Second, our results suggest that some types of motivations among volunteers (understanding the nonprofit, career or employment opportunities, the advice of family, friends, and acquaintances, and protective reasons), as well as the sense of belonging, perceived usefulness of new technologies, social influence and having feedback channels, all positively influence the adoption of omnichannel behavior by volunteers. Additionally, our findings reveal different effects for the two clusters identified. Finally, and using a contingency approach, implications for nonprofit–volunteer relationship management are drawn.

Work with citizens' applications in the context of digitalization: departmental aspects

Applications act as an important channel of feedback between the population and state authorities. An important element of the system of federal executive bodies of the Russian Federation, which are entrusted with the functions of ensuring the rights of citizens to appeal, is the Ministry of Internal Affairs of the Russian Federation. The article discusses the main provisions that determine the unified procedure for working with applications from citizens and organizations in accordance with the new conditions for the development of our state - the introduction of the "Digital Government" system. On the example of the Ministry of Internal Affairs of the Russian Federation, the possibilities and mechanisms for working with citizens' applications using the electronic document management service of the unified system of information and analytical support for the activities of the Ministry of Internal Affairs of Russia are specified. The author comes to the conclusion that information about working with citizens' appeals characterizes the state and effectiveness of the system of internal affairs bodies, since it is primarily associated with the accumulation of various information, quantitative and qualitative assessments of which can bring the system closer to solving priority tasks, namely, ensuring protection public order and the fight against crime. When analyzing the registration and control forms of the section "Appeals of citizens and organizations" of the application service for electronic document management of the unified system of information and analytical support for the activities of the Ministry of Internal Affairs of Russia, a number of problems were identified that arise in connection with the introduction of digital technologies, indicating that the procedure for considering applications in the bodies internal affairs is carried out in conditions of inferior legal regulation. The conclusion is made about the available resources in the development of the current classification system for incoming applications.

ГЕЙМИФИКАЦИЯ И ДРУГИ ПОДХОДИ ЗА ПОВИШАВАНЕ НА ИНТЕРЕСА НА ОБУЧАЕМИТЕ В ПРЕПОДАВАНЕТО НА PYTHON

This paper describes the challenges of teaching technological disciplines at high school and higher education levels. In particular four challenges are identified – participation motivation, motivation for cooperation, the need for feedback and the need for recognition. The strategies for answering these challenges are described as they were identified when teaching at university level, particularly taking into account the psychological peculiarities of the newer generation and using gamification techniques. A system for achievements and badges for unofficial channel feedback channel is described.

Stability of a Groucho-Style Bounding Run in the Sagittal Plane

This paper develops a three-degree-of-freedom sagittal-plane hybrid dynamical systems model of a Groucho-style bounding quadrupedal run. Simple within-stance controls using a modular architecture yield a closed-form expression for a family of hybrid limit cycles that represent bounding behavior over a range of user-selected fore-aft speeds as a function of the model’s kinematic and dynamical parameters. Controls acting on the hybrid transitions are structured so as to achieve a cascade composition of in-place bounding driving the fore-aft degree of freedom, thereby decoupling the linearized dynamics of an approximation to the stride map. Careful selection of the feedback channels used to implement these controls affords infinitesimal deadbeat stability, which is relatively robust against parameter mismatch. Experiments with a physical quadruped reasonably closely match the bounding behavior predicted by the hybrid limit cycle and its stable linearized approximation.

Uplink Assisted MIMO Channel Feedback Method Based on Deep Learning.

In order to solve the problem wherein too many base station antennas are deployed in a massive multiple-input-multiple-output system, resulting in high overhead for downlink channel state information feedback, this paper proposes an uplink-assisted channel feedback method based on deep learning. The method applies the reciprocity of the uplink and downlink, uses uplink channel state information in the base station to help users give feedback on unknown downlink information, and compresses and restores the channel state information. First, an encoder-decoder structure is established. The encoder reduces the network depth and uses multi-resolution convolution to increase the accuracy of channel state information extraction while reducing the number of computations relating to user equipment. Afterward, the channel state information is compressed to reduce feedback overhead in the channel. At the decoder, with the help of the reciprocity of the uplink and downlink, the feature extraction of the uplink's magnitudes is carried out, and the downlink channel state information is integrated into a channel state information feature matrix, which is restored to its original size. The simulation results show that compared with CSINet, CRNet, CLNet, and DCRNet, indoor reconstruction precision was improved by an average of 16.4%, and outside reconstruction accuracy was improved by an average of 21.2% under all compressions.

A preliminary study on the barriers and facilitators to improving the health, safety, and well-being of aging heavy vehicle drivers

Introduction. Managers from road freight transportation organizations were interviewed on barriers and facilitators to implementation of occupational health, safety, and well-being interventions for aging heavy vehicle drivers. As aging drivers are more likely to be seriously injured or die in a work-related incident than younger drivers, it is important to recognize strengths and weaknesses throughout the system to identify intervention that addresses their specific needs. Method: A Systems Theoretic Accident Model and Processes (STAMP) control structure was constructed to chart the controllers, controls, and feedback channels in the system to identify gaps in health, safety, and well-being intervention in the system. The STAMP control structure also charted the barriers and facilitators within levels across the system. Eleven managers were recruited into the study representing a range of road freight transportation organizations throughout Australia. Results: Interview data revealed that barriers and facilitators existed at most levels of the system. Facilitators included advice from external agencies, support from upper management, modern technology, and regular social communication with drivers. Barriers were a lack of guidance on aging issues, operational conflicts with health and safety objectives, and the drivers’ fear of disclosing health information associated with their driving role. In regards to formalized intervention in place to support aging heavy vehicle drivers, the system is reliant on fitness to drive medical assessments based on age and jurisdiction. Conclusions: As there was generally a lack of senior direction cited from the upper levels of the system on aging issues, there was much variation across the study on how aging risks are managed in the workplace for heavy vehicle drivers. Practical Applications: This study recommends that managers across the road freight transportation industry receive formalized aging-awareness health and safety training in how to manage work-related driving hazards for aging heavy vehicle drivers.

Virtual Synchronous Generator (VSG) Control Strategy Based on Improved Damping and Angular Frequency Deviation Feedforward

The output active power of a grid-connected inverter controlled by a traditional virtual synchronous generator (VSG) has the problems of oscillation and steady-state errors. A VSG control strategy based on improved damping and angular frequency deviation feedforward is proposed. This strategy reduces the steady-state error of active power by adding a transient damping link to a traditional VSG damping feedback channel. At the same time, the angular frequency deviation feedforward compensation is used to improve the response speed of the VSG to the active power instruction and reduce the active power overshoot in the dynamic process. First, the VSG active power closed-loop small-signal model is established. The effects of inertia and damping on the dynamic and steady-state performance of the VSG are analyzed by the root locus method. The effect of the proposed control strategy on the system is analyzed by using a closed-loop zero-pole diagram. This strategy improves the precision of active power control the dynamic performance of the system effectively. Finally, the effectiveness and superiority of the proposed control strategy are verified by Matlab/Simulink simulation and semi-physical simulation platform RT-LAB.

Limitations of energy SNR in control over channels with and without feedback

This paper presents limitations of energy signal-to-noise ratio (SNR) in control of discrete-time linear systems over noisy channels with and without feedback. The minimum SNR required for stabilization is shown to be the modulus of the product of unstable poles of the plants. Two types of optimal control laws that achieve this minimum are constructed based on the gains for expensive control, that is, LQ optimal control without input weight. It is observed that channel feedback does not improve the SNR limitation, which means feedback for control is efficient enough for communication.

Optimal acknowledgment signal attacks against remote estimation

In this paper, we consider a malicious attack issue against remote state estimation in cyber-physical systems. Due to the limited energy, the sensor adopts an acknowledgment-based (ACK-based) online power schedule to improve the remote state estimation. However, the feedback channel will also increase the risk of being attacked. The malicious attacker has the ability to intercept the ACK information and modify the ACK signals (ACKs) from the remote estimator. It could induce the sensor to make poor decisions while maintaining the observed data packet acceptance rate to keep the attacker undetected. To maximize the estimation error, the attacker will select appropriate attack times so that the sensor makes bad decisions. The optimal attack strategy based on the true ACKs and the corrosion ACKs is analytically proposed. The optimal attack time to modify the ACKs is the time when the sensor’s tolerance, i.e., the number of consecutive data packet losses allowed, is about to reach the maximum. In addition, such an optimal attack strategy is independent of the system parameters. Numerical simulations are provided to demonstrate the analytical results.

Characteristics of a novel fluidic oscillator with movable feedback channels and resonators

Characteristics of a novel fluidic oscillator with movable feedback channels and resonators

Tactual Articulatory Feedback on Gestural Input

The role of the sense of touch in Human–Computer Interaction as a channel for feedback in manipulative processes is investigated through the research presented here. The paper discusses how information and feedback as generated by the computer can be presented haptically, and focusses on the feedback that supports the articulation of human gesture. A range of experiments are described that investigate the use of (redundant) tactual articulatory feedback. The results presented show that a significant improvement of effectiveness only occurs when the task is sufficiently difficult, while in some other cases the added feedback can actually lower the effectiveness. However, this work is not just about effectiveness and efficiency, it also explores how multimodal feedback can enhance the interaction and make it more pleasurable—indeed, the qualitative data from this research show a perceived positive effect for added tactual feedback in the overall experience. The discussion includes suggestions for further research, particularly investigating the effect in free moving gestures, multiple points of contact, and the use of more sophisticated actuators.

Communicative competencies of civil servants: foreign experience

To date, the Law on the Civil Service of the Republic of Kazakhstan for civil servants has approved ethical rules, tasks, requirements that must be observed when interacting with society, however, explanations of communicative competencies, communication skills that must be observed when interacting with society are not given. The concept of development of local self-government in the Republic of Kazakhstan until 2025 outlines the need to clarify the status, functions, and powers of civil servants taken together of the current model of local self-government. The research paper uses the results of a sociological survey conducted by the Kazakhstan Institute for Strategic Studies under the President of the Republic of Kazakhstan in 2021, which indicate the main characteristics of the state body: accessibility of the state body, starting with the availability of contacts and addresses in the public domain; openness in providing information about activities and budget; availability of existing feedback channels with the population. This result once again confirms the need to improve the communicative competencies of civil servants of the Republic of Kazakhstan. In the course of writing the article, the analysis of the content and history of the development of the process of reforming the civil service of the countries of Great Britain, France, USA, Switzerland, Japan, Canada, South Korea, standards of conduct of civil servants was carried out. Based on foreign experience, on the full coordination of the functions of the Civil Servants Service, on the experience of introducing the benchmarking process into the public administration system, the principles of the Civil Service Commission, the School of Public Service, Charity and Care in the country, recommendations are given on the formation of a model of professional communicative competencies of Kazakhstan civil servants.

Channel Customization for Limited Feedback in RIS-Assisted FDD Systems

Reconfigurable intelligent surfaces (RISs) represent a pioneering technology to realize smart electromagnetic environments by reshaping the wireless channel. Jointly designing the transceiver and RIS relies on the channel state information (CSI), whose feedback has not been investigated in multi-RIS-assisted frequency division duplexing systems. In this study, the limited feedback of the RIS-assisted wireless channel is examined by capitalizing on the ability of the RIS in channel customization. By configuring the phase shifters of the surfaces using statistical CSI, we customize a sparse channel in rich-scattering environments, which significantly reduces the feedback overhead in designing the transceiver and RISs. Since the channel is customized in terms of singular value decomposition (SVD) with full-rank, the optimal SVD transceiver can be approached without a matrix decomposition and feeding back the complete channel parameters. The theoretical spectral efficiency (SE) loss of the proposed transceiver and RIS design is derived by considering the limited CSI quantization. To minimize the SE loss, a bit partitioning algorithm that splits the limited number of bits to quantize the CSI is developed. Extensive numerical results show that the channel customization-based transceiver with reduced CSI can achieve satisfactory performance compared with the optimal transceiver with full CSI. Given the limited number of feedback bits, the bit partitioning algorithm can minimize the SE loss by adaptively allocating bits to quantize the channel parameters.

Design and Analysis of Analog Feedback Communication System with Rayleigh Fading Channel Model

In this work, we mathematically model a wireless Analog feedback communication system (AFCS) using a Rayleigh fading channel. AFCS system is a new research area and has promising applications, especially in low-power devices such as sensors. Compared to AWGN, Rayleigh fading channel more closely models the real wireless environment. In this work, AFCS Rayleigh fading channel is considered in forward transmission while AWGN is considered in the feedback channel. We evaluated the performance of the system which is mostly based on the minimization of mean square error (MSE) at the receiver. Even in presence of a wireless fading environment, the AFCS attains a 0 MSE value in 2-3 iterations if a noise power of 10dB is considered while in 10-15 iterations if a noise power of 20dB is considered.

A cybernetic participatory approach for policy system of systems mapping: Case study of inclusive economies

Traditional participatory systems modelling demands synchronous time from many experts and face-to-face interaction. This is not always feasible (e.g., during a pandemic) and can restrict which participants can be included. There are additional limitations in the effectiveness of physical paper-based modelling when handling large complex systems with numerous variables and links between them. The key challenge facing practitioners is then how can we retain the benefits of traditional participatory modelling whilst exploiting the advantages of new technologies? This paper contributes to development of an original systematic methodology inspired by Cybernetic principles. The proposed method, referred to as 5X – standing for Expose, Explore, Exploit, Explain, and Expand – offers a fully virtual co-produced environment for iterative cycles of stakeholder engagement and feedback before, during and after workshops, leading to developing more confidence in systems mapping, and promoting knowledge across policy areas. A primary application of the proposed method in a real policy setting illustrates its capability to generate a shared policy understanding of a complex inclusive economy system, where there is conflicting or dispersed knowledge about system structure, refine this understanding through online feedback channels and dynamic visualisations, and transfer this understanding to wider policy and academic partners.

Relaxation Fluidic Oscillators: Design Parameters, New Operating Modes, and Characteristics of Their Internal and External Flows

AbstractFluidic oscillators are no-moving-part actuators that can be used to produce pulsating jets. The characteristics of these devices and of the flow fields they produce are of particular interest in the field of heat transfer, as pulsating impinging jets have been shown to improve heat transfer compared to steady jets. In this study, special focus is given to these characteristics as a preparation for a subsequent thermal study that will evaluate the performance of these pulsed jets against steady jets. The functioning of the device in response to different operating and design parameters is first considered. It was shown that a transition between different operating modes is possible, depending on both the inlet mass flowrate and the width of the feedback channel of the device. This was followed by a study of the velocity fields of the pulsed jets produced by the device. More specifically, attention is given to the developing characteristics and flow structures of the pulsating free jets of air which are then compared to equivalent steady jets. Finally, by taking advantage of the periodic aspect of the flow, the phase-averaged velocity field was reconstructed. Vortex dipoles were detected, tracked and their convection velocity computed from the same data and compared to a theoretical value from the literature. A proper orthogonal decomposition (POD) of the synchronized raw data was then performed to further highlight the presence of these vortex structures and other flow instabilities.

Event-Triggered Networked Predictive Output Tracking Control of Cyber–Physical Systems With Model Uncertainty and Communication Constraints

This brief investigates the output tracking control problem of cyber-physical systems with model uncertainty and random communication constraints. An event-triggered networked predictive output tracking control method is presented to actively compensate random communication constraints in the two-channel, namely the feedback channel and forward channel. To handle the communication overload issue caused by communication constraints in networked predictive control approach, two kinds of event-triggered mechanisms are designed in both sensor and controller to save network resources. Then, the stability conditions of closed-loop systems with model certainty and uncertainty cases are derived. Finally, numerical simulation is performed to verify the effectiveness of presented method.