Feedback Messages Research Articles

Generating efficient toolpath by cutter posture optimization in five-axis machining based on inverse feedback mechanism

This paper proposes a tool posture optimization method in five-axis machining using configuration space (C-Space) transformation according to the inverse feedback message. In conventional computer numerical control (CNC) manufacture process, the machining status information transmission is in single direction, and the CNC system interpolates the toolpaths without feedback. However, considering the drives’ acceleration and deceleration, the interpolation situation would greatly affect the machining efficiency and the trajectory should be adjusted in CNC. In this case, the toolpath efficiency is deteriorated and unable to be evaluated exactly by traditional computer-aided manufacturing (CAM) system, where the efficiency is approximately estimated by the length of toolpath. In this paper, an inverse feedback mechanism is proposed; the simulated information on CNC system interpolation can be feedback to CAM system to help evaluate the toolpath efficiency. An axis-based dynamic confined feedrate schedule model is used to find the feed sensitive zones of the toolpaths. A C-Space method is adopted to adjust the tool postures in the sensitive zones. Several examples are given to verify the method, and the machining efficiency is raised by 10% on the whole after feedback optimization.

Effectiveness and cost-effectiveness of a guided Internet- and mobile-based intervention for the indicated prevention of major depression in patients with chronic back pain\u2014study protocol of the PROD-BP multicenter pragmatic RCT

BackgroundReducing the disease burden of major depressive disorder (MDD) is of major public health relevance. The prevention of depression is regarded as one possible approach to reach this goal. People with multiple risk factors for MDD such as chronic back pain and subthreshold depressive symptoms may benefit most from preventive measures. The Internet as intervention setting allows for scaling up preventive interventions on a public mental health level.MethodsThis study is a multicenter pragmatic randomized controlled trial (RCT) of parallel design aiming to investigate the (cost-) effectiveness of an Internet- and mobile-based intervention (IMI) for the prevention of depression in chronic back pain patients (PROD-BP) with subthreshold depressive symptoms. eSano BackCare-DP is a guided, chronic back pain-specific depression prevention intervention based on cognitive behavioral therapy (CBT) principles comprising six weekly plus three optional modules and two booster sessions after completion of the intervention. Trained psychologists provide guidance by sending feedback messages after each module. A total of 406 patients with chronic back pain and without a depressive disorder at baseline will be recruited following orthopedic rehabilitation care and allocated to either intervention or treatment-as-usual (TAU). Primary patient-relevant endpoint of the trial is the time to onset of MDD measured by the telephone-administered Structured Clinical Interview for DSM (SCID) at baseline and 1-year post-randomization. Key secondary outcomes are health-related quality of life, depression severity, pain intensity, pain-related disability, ability to work, intervention satisfaction and adherence as well as side effects of the intervention. Online assessments take place at baseline and 9 weeks as well as 6 and 12 months post-randomization. Cox regression survival analysis will be conducted to estimate hazard ratio at 12-month follow-up. Moreover, an economic analysis will be conducted from a societal and public health perspective.DiscussionThis is the first study examining an IMI for depression prevention in a sample of chronic pain patients. If this implementation of a depression prevention IMI into orthopedic aftercare proves effective, the intervention could be integrated into routine care with minimal costs and extended for use with other chronic diseases. Results will have implications for researchers, health care providers and public health policy makers.Trial registrationThe trial is registered at the WHO International Clinical Trials Registry Platform via the German Clinical Studies Trial Register (DRKS): DRKS00007960. Registered 12 August 2015.

Eye Tracking Analysis of EAP Student’s Regions of Interest in Computer-based Feedback on Grammar, Usage, Mechanics, Style and Organization and Development

Much research has been conducted on the nature, role and effect of feedback. While it is generally claimed that feedback on L2 writing can improve learning, the role which feedback plays in the development of a learner’s writing remains unclear. An attempt can be made to infer the effect of feedback from a student’s subsequent written products, however the way in which a student engages with feedback messages and acts on them is hard to investigate, principally because this is generally an individual, private process, and so hard to externalise. The current study is concerned with using a range of methods for examining such student reactions to computer-based feedback, including eye-tracking data which provides a record of which errors and feedback messages the participants appear to read, in which order and for how long. The results suggest a marked tendency to focus on feedback on grammar, and on organisation and development. It is hypothesised that the former is due to participants’ perception of the role of grammar in writing in their EFL exam-oriented contexts. The latter appears to be the result of the nature of the computer-based feedback they received

A Method for Correcting Preposition Errors in Learner English with Feedback Messages

A Method for Correcting Preposition Errors in Learner English with Feedback Messages

Distributed MIMO Multicast With Protected Receivers: A Scalable Algorithm for Joint Beamforming and Nullforming

We consider the problem of multicasting a common message signal from a distributed array of wireless transceivers by beamforming to a set of beam targets , while simultaneously protecting a set of null targets by nullforming to them. We describe a distributed algorithm in which each transmitter iteratively adapts its complex transmit weight using common aggregate feedback messages broadcast by the targets, and the local knowledge of only its own channel gains to the targets. This knowledge can be obtained using reciprocity without any explicit feedback. The algorithm minimizes the mean square error between the complex signal amplitudes at the targets and their desired values. We prove convergence of the algorithm, present geometric interpretations, characterize initializations that lead to minimum total transmit power, and prescribe designs for such initializations. We show that the convergence speed is nondecreasing in the number of transmitters $N$ if a step size parameter is kept constant. For Rayleigh fading channels, as $N$ goes to infinity: 1) convergence can be made arbitrarily fast and 2) beams and nulls can be achieved with vanishing total transmit power even with noise, both with probability one. These results add up to some remarkable scalability properties: the feedback overhead does not grow with the number of transmitters, and with high probability, the algorithm can be configured to converge arbitrarily fast and use vanishingly small total transmit power.

Effects of Pleasant or Unpleasant Feedback Messages on the Learning of Timing

We investigated the effects of pleasurable and unpleasurable messages on the learning of timing using a ten-key pressing task. The messages affected the participants’ emotions and provided them with knowledge of the results (KR). A total of 42 university students participated in this experiment. They were divided into three groups: the pleasurable message group (PMG), the unpleasurable message group (UMG), and the control group (CG). Participants were required to 1) press “2”, “4”, “8”, and “6” in order on the ten-key pad, 2) finish within 1100 ms of pressing “2”, and 3) press with relative time intervals of 22.2%, 44.4%, and 33.3%. All groups were provided with the following KR after every practice trial: total time and relative time intervals. Participants in the PMG and UMG groups were provided with pleasurable or unpleasurable messages, respectively, if their total times were within ±5% of the range, or when any of their time intervals fell outside of ±10% of the range. Three pretest trials, 30 practice trials, and three posttest trials were performed on Day 1. Three retention trials and 3 transfer trials were performed on Day 2. The transfer trials total time was 1800 ms, and that of the relative time interval was the same as on Day 1. The results indicate that although all groups learned the timing task, the UMG had higher variable and root mean square errors on the transfer test compared to the PMG and CG. These results suggest that unpleasurable messages are disadvantageous for learning stable timing during the ten-key pressing task because unpleasurable emotions may negatively affect cognitive processing.

Longitudinal analysis of normative energy use feedback on dormitory occupants

Behavior interventions aiming to reduce energy consumption in the built environment are becoming increasingly common. The application of individual feedback and use of social norms have shown promise in the short-term at improving occupant energy use behavior. Yet, the long-term effects, role of messaging duration, and relative effect of normative elements in feedback messages remain less clear. This paper attempts to address these gaps in the literature by conducting and analyzing two yearlong field experiments that test the effect of normative feedback messages on energy consumption in dormitories. The analysis finds that adding normative elements to feedback messages had no effect on energy consumption in the short-term. When examining behavior change conditional on an occupant’s concern for social norms, it was found that individuals with a high concern for social norms positively responded to the normative elements with an estimated treatment effect of −14% (consumed less). Conversely, individuals with a low concern for social norms had the opposite reaction, with an estimated treatment effect of 5%. Further, it was discovered that the duration of messaging positively influenced the long-term durability of behavior change. The long-term effect of behavior change was twice as prevalent in individuals with high concern for social norms.

Green Small Cell Operation of Ultra-Dense Networks Using Device Assistance

As higher performance is demanded in 5G networks, energy consumption in wireless networks increases along with the advances of various technologies, so enhancing energy efficiency also becomes an important goal to implement 5G wireless networks. In this paper, we study the energy efficiency maximization problem focused on finding a suitable set of turned-on small cell access points (APs). Finding the suitable on/off states of APs is challenging since the APs can be deployed by users while centralized network planning is not always possible. Therefore, when APs in small cells are randomly deployed and thus redundant in many cases, a mechanism of dynamic AP turning-on/off is required. We propose a device-assisted framework that exploits feedback messages from the user equipment (UE). To solve the problem, we apply an optimization method using belief propagation (BP) on a factor graph. Then, we propose a family of online algorithms inspired by BP, called DANCE, that requires low computational complexity. We perform numerical simulations, and the extensive simulations confirm that BP enhances energy efficiency significantly. Furthermore, simple, but practical DANCE exhibits close performance to BP and also better performance than other popular existing methods. Specifically, in a small-sized network, BP enhances energy efficiency 129%. Furthermore, in ultra-dense networks, DANCE algorithms successfully achieve orders of magnitude higher energy efficiency than that of the baseline.

Smartphone text message service to foster hand hygiene compliance in health care workers.

Health care-associated infections are a major worldwide public health issue. Hand hygiene is a major component in the prevention of pathogen transmission in hospitals, and hand hygiene adherence by health care workers is low in many studies. We report an intervention using text messages as reminders and feedback to improve hand hygiene adherence. The study is a historical comparison proof-of-concept study. Eighteen health care workers were monitored during 12 months by a radiofrequency identification system. Afterward we sent 2 types of text messages, congratulation or encouragement, and we studied the evolution of hand hygiene adherence. We recorded 15,723 hand hygiene opportunities, 8,973 before intervention and 6,750 during and after the intervention. Using a multilevel logistic regression analysis, we found a significant increase in hand hygiene adherence during the intervention (odds ratio, 1.68) compared with the historical period. Despite limitations due to the type of study, a text message encouraging personnel to be more vigilant is effective in increasing hand hygiene adherence in health care workers. Text message feedback should be incorporated into multimodal approaches for improving hand hygiene compliance.

Using video technology to enable student voice in assessment feedback

AbstractStudents’ voices have been remarkably absent in feedback research, yet research shows that the way students engage with feedback significantly impacts on its effect on learning. Feedback research has mainly focused on aspects of the feedback message between a sender and receiver, with little consideration of the positioning of students in this process. This article (a) provides an overview of the literature about feedback in education and the role of the student in these processes and (b) provides findings from a pilot project that explored the use of video technology as a self‐reflection tool for six teachers and six students to capture assessment interactions and give students a voice in feedback conversations. The pilot employed iPads to facilitate video‐aided self‐reflection on feedback practices. The results suggest that not only is video a powerful tool for teacher reflection on their feedback practices, it can also provide better understanding of the student perspective in feedback conversations. Importantly, involving students themselves in video‐stimulated recall of feedback conversations has the potential to contribute to students’ self‐reflection of their involvement in the feedback process, encouraging them to make their voices heard and participate in feedback as a dialogic practice.

Generalized HARQ Protocols with Delayed Channel State Information and Average Latency Constraints

In many wireless systems, the signal-to-interference-and-noise ratio that is applicable to a certain transmission, referred to as channel state information (CSI), can only be learned after the transmission has taken place and is thereby delayed (outdated). In such systems, hybrid automatic repeat request (HARQ) protocols are often used to achieve high throughput with low latency. This paper put forth the family of expandable message space (EMS) protocols, that generalize the HARQ protocol and allow for rate adaptation based on delayed CSI at the transmitter (CSIT). Assuming a block-fading channel, the proposed EMS protocols are analyzed using dynamic programming. When full delayed CSIT is available and there is a constraint on the average decoding time, it is shown that the optimal zero outage EMS protocol has a particularly simple operational interpretation and that the throughput is identical to that of the backtrack retransmission request (BRQ) protocol. We also devise EMS protocols for the case in which CSIT is only available through a finite number of feedback messages. The numerical results demonstrate that BRQ approaches the ergodic capacity quickly compared with HARQ, while EMS protocols with only three and four feedback messages achieve throughputs, that are only slightly worse than that of BRQ.

An Approach of Handling Packet Loss for Delay Sensitive Video Streaming in MANETs

Wireless communication networks became ubiquitous. Mobile ad hoc networks (MANETs) have become an exactly right option that can be chosen for on-demand infrastructure less communications. Besides the enhancements in Mobile ad hoc networks (MANETs) communications, more research can be done on these networks, if they have to be used for video streaming. The reason behind this is that, the Mobile ad hoc networks (MANETs) devices are resource constrained and thus efficient methods to support multimedia communications supporting video streaming is a defiance problem. This is because videos are delay sensitive and thus good quality streaming is inevitable. In the proposed work we use AODV protocol and an idea of Dynamic congestion detection and routing. In this work we define Signal to noise ratio threshold at nodes in all the previously visited paths from source to destination in order to identify the congestion level at the nodes dynamically and construct an optimal path for the transmission of video packets in Mobile ad hoc networks (MANETs) . This decreases the traffic which occurs due to multiple feedback messages from nodes in the network. Hence this approach decreases the loss of packets and this leads to the improvement in the performance.

An Agent-Based Intervention to Assist Drivers Under Stereotype Threat: Effects of In-Vehicle Agents' Attributional Error Feedback.

For members of a group negatively stereotyped in a domain, making mistakes can aggravate the influence of stereotype threat because negative stereotypes often blame target individuals and attribute the outcome to their lack of ability. Virtual agents offering real-time error feedback may influence performance under stereotype threat by shaping the performers' attributional perception of errors they commit. We explored this possibility with female drivers, considering the prevalence of the "women-are-bad-drivers" stereotype. Specifically, we investigated how in-vehicle voice agents offering error feedback based on responsibility attribution (internal vs. external) and outcome attribution (ability vs. effort) influence female drivers' performance under stereotype threat. In addressing this question, we conducted an experiment in a virtual driving simulation environment that provided moment-to-moment error feedback messages. Participants performed a challenging driving task and made mistakes preprogrammed to occur. Results showed that the agent's error feedback with outcome attribution moderated the stereotype threat effect on driving performance. Participants under stereotype threat had a smaller number of collisions when the errors were attributed to effort than to ability. In addition, outcome attribution feedback moderated the effect of responsibility attribution on driving performance. Implications of these findings are discussed.

Cognitive and Social Factors Influencing Students׳ Response and Utilization of Facilitator Feedback in a Problem Based Learning Context

PurposeFeedback within a problem-based learning tutorial can only influence learning if it is efficiently utilized. The purpose of this study was to explore perceived factors that influence student utilization of facilitator feedback within a problem-based learning tutorial. MethodsIt was an exploratory qualitative study that was conducted at an African Health Sciences University that has been using problem based learning for over a decade. The study involved third year students from across five health sciences disciplines that included: medicine, radiography, dentistry, nursing and pharmacy. Purposive sampling was the technique used to select the participants. These students had been previously exposed to problem based learning tutorials since their first year. Data was collected using both individual interviews and focus-group discussions. In total, twenty-five individual interviews and five focus group discussions were conducted. ResultsBoth cognitive and social factors were discovered to influence students׳ use of feedback in a tutorial, and these have a reciprocal relationship, reinforcing each other to influence student learning. Key cognitive influencing factors included: overloaded feedback, unspecific and unfocused feedback, perceived limited knowledge of the tutor, differing feedback across tutorial groups and de-linking feedback from learning outcomes. The major social influencing factors included: language of feedback and communication, facilitator interpersonal skills, degree of participation of the facilitator, gender stereotyping and individualization of feedback. ConclusionBoth cognitive and socio-contextual factors have the potential in influencing ways in which students receive and utilize facilitator feedback in PBL tutorials. Therefore, tutorial facilitators need to be cognizant of these factors when framing their feedback messages.

Effective Capacity of Delay-Constrained Cognitive Radio Links Exploiting Primary Feedback

In this paper, we study the effective capacity (EC) of cognitive radio (CR) networks operating under statistical quality-of-service (QoS) constraints in an attempt to support real-time applications at the secondary users (SUs). In particular, we analyze the performance gains, in terms of EC and average transmitted power, attributed to leveraging the primary user (PU) feedback overheard at the SU, at no additional complexity or hardware cost. We characterize the EC performance improvement for the SU, in the presence of a feedback-based sensing scheme, under the signal-to-interference-plus-noise ratio (SINR) interference and collision models. Toward this objective, we develop a Markov chain model for feedback-based sensing to compare the performance of a two-link network, a single secondary link, and a primary network abstracted to a single primary link, with and without primary-feedback exploitation. We prove that exploiting the primary feedback at the secondary transmitter improves the EC of the SU under the SINR interference model. On the other hand, interestingly, exploiting the PU feedback messages does not enhance the EC of the SU under the collision model. Nevertheless, exploiting the PU feedback reduces the SU average transmitted power under the two aforementioned models. Finally, we present numerical results, for plausible scenarios, that support our analytical findings.

Analyzing Change Processes Resulting from a Smartphone Maintenance Intervention Based on Acceptance and Commitment Therapy for Women with Chronic Widespread Pain.

This study investigated change processes resulting from a randomized controlled trial smartphone-delivered maintenance intervention with daily electronic diaries and personalized written feedback based on acceptance and commitment therapy (ACT) following a rehabilitation program for patients with chronic widespread pain. This study included 48 women who during a 5-week period completed electronic diaries three times daily, totaling 3372 entries. In response to the completed diaries, they received daily feedback from a therapist for 4weeks (excluding weekends), totaling 799 feedback messages. To analyze the change processes, we explored the associations between feedback and daily ratings of participants' physical activities, positive emotions, pain fear and avoidance, pain acceptance, and self-management. Commitment to physical activities and the participants' evaluation of feedback were also analyzed. Multilevel models were used in the statistical analyses. Participants' average pain fear and avoidance decreased over the intervention period (mean -0.019, P=0.05). Self-management, pain acceptance, and positive feelings increased (mean -0.030, P<0.01; mean -0.015, P<0.01; and mean -0.011, P=0.01, respectively). Participants' performance of physical activities decreased slightly over time, but the level of commitment was high and they evaluated the feedback as supportive for staying sufficiently active. No correlation between diary contents and feedback messages was found, even though most of the participants evaluated the feedback as supportive. No support was found for an association between diary content and feedback based on ACT. However, diary measures were consistent with the ACT model and may have influenced positively the change processes.

E-Mailed Prompts and Feedback Messages to Reduce Energy Consumption: Testing Mechanisms for Behavior Change by Employees at a Green University

ABSTRACTE-mail is a common mechanism for communication within organizations. Extending prior research on effects of informational messages on behavior change, the present study evaluated effects of e-mailed prompts and feedback on energy consumption at a green university. A nonconcurrent multiple baseline design was used to evaluate the effects of messages to occupants of 5 campus buildings over a period of 12 weeks. Energy consumption changes were tracked using the university’s energy dashboard. Results and implications for further research and organizational behavior change efforts are discussed.

Retrospective cognitive feedback for progress monitoring in serious games

AbstractAlthough the importance of cognitive feedback in digital serious games (DSG) is undisputed, we are facing some major design challenges. First of all, we do not know to which extend existing research guidelines apply when we stand the risk of cognitive feedback distorting the delicate balance between learning and playing. Unobtrusive cognitive feedback has to be interspersed with gameplay. Second, many effective solutions for providing cognitive feedback we do know might simply be too costly. To face both challenges, this study offers an efficient approach for providing unobtrusive and retrospective cognitive feedback (RCF) in DSG. This approach was applied onto a game where feedback messages were triggered via simple rules about learners' questioning behavior on four dimensions. We found the experimental condition including such RCF to yield better learning outcomes while maintaining similar motivation.

Staged Growth Codes: Intermediate Performance and Overhead Analysis

It is well known that the overhead and error performances of LT codes are primarily determined by the degrees of output symbols. This letter derives a novel relationship using the AND–OR tree analytical technique between the redundancy and release probabilities, and the degree of output symbols in LT codes. Armed with this new relationship, we propose a new class of so-called staged growth codes (SGCs), which can provide the intermediate performance. We investigate the asymptotic performance of the proposed SGCs. In comparison with the conventional growth codes, the SGCs need less feedback messages and the overhead is nearly the same as LT codes when the number of blocks is not too much. Observed from the numerical results, an additional attractive feature of the SGCs in comparison with the growth codes is that the SGCs can provide the often desirable unequal error protection property.

Belated Analyses of Three Credit-Based Adaptive Polling Algorithms

We study the problem of credit-based adaptive polling in undirected arbitrary point-to-point asynchronous networks. Polling consists of two rounds, namely propagation (broadcast) and feedback (confirmation, response) rounds. By adaptive polling, a spanning tree of unknown topology is built dynamically during the propagation round, and feedback messages are free to choose their paths back to the initiator — a specific node who initiates the polling algorithm. The freedom in the feedback round relies on the use of credits in the propagation round. We re-visit three existing algorithms and analyse their average case communication bit complexities incurred by the credits in the propagation round, and these analyses match with the numerical results. We also give an optimal lower bound on the worst case bit message complexity for the case when the number of nodes in the network is unknown.