Feedback Reduction Research Articles

Leadership feedback reduction: Are high flyers flying in the dark?

Leadership feedback reduction: Are high flyers flying in the dark?

Visual feedbacks influence short-term learning of torque versus motion profile with robotic guidance among young adults

Robotic assistance can improve the learning of complex motor skills. However, the assistance designed and used up to now mainly guides motor commands for trajectory learning, not dynamics learning. The present study explored how a complex motor skill involving the right arm can be learned without suppressing task dynamics, by means of an innovative device with robotic guidance that allows a torque versus motion profile to be learned with admittance control. In addition, we assessed how concurrent visual feedback on this profile can enhance learning without creating dependency, by means of a fading procedure (i.e., feedback reduction across trials). On Day 1, a Control group performed an acquisition session (6 blocks) featuring concurrent visual feedback, while a Fading group performed the session with a gradual reduction in feedback (from 100% to 0% over the 6 blocks). On Day 2, both groups performed a block first without feedback (i.e., Transfer test), then with feedback (i.e., Retention test). Results revealed that on Day 1, movement rehearsal induced a significant improvement in spatiotemporal parameters for the Control group, compared with the Fading group. On Day 2, the opposite was found when this visual feedback was removed, as the Fading group performed significantly better than the Control group on the Transfer test. Vision allows a relationship to be established between the required torque and the motion profile. Its suppression then forces the processing of more intrinsic information, leading to the development of a stable internal representation of the task.

A neural model of modified excitation/inhibition and feedback levels in schizophrenia.

The strength of certain visual illusions, including contrast-contrast and apparent motion, is weakened in individuals with schizophrenia. Such phenomena have been interpreted as the impaired integration of inhibitory and excitatory neural responses, and impaired top-down feedback mechanisms. To investigate whether and how these factors influence the perceived contrast-contrast and apparent motion illusions in individuals with schizophrenia, we propose a two-layer network, with top-down feedback from layer 2 to layer 1 that can model visual receptive fields (RFs) and their inhibitory and excitatory subfields. Our neural model suggests that illusion perception changes in individuals with schizophrenia can be influenced by altered top-down mechanisms and the organization of the on-center off-surround receptive fields. Alteration of the RF inhibitory surround and/or the excitatory center can replicate the difference of illusion precepts between individuals with schizophrenia within certain clinical states and normal controls. The results show that the simulated top-down feedback modulation enlarges the difference of the model illusion representations, replicating the difference between the two groups. We propose that the heterogeneity of visual and in general sensory processing in certain clinical states of schizophrenia can be largely explained by the degree of top-down feedback reduction, emphasizing the critical role of top-down feedback in illusion perception, and to a lesser extent on the imbalance of excitation/inhibition. Our neural model provides a mechanistic explanation for the modulated visual percepts of contrast-contrast and apparent motion in schizophrenia with findings that can explain a broad range of visual perceptual observations in previous studies. The two-layer motif of the current model provides a general framework that can be tailored to investigate subcortico-cortical (such as thalamocortical) and cortico-cortical networks, bridging neurobiological changes in schizophrenia and perceptual processing.

Take Itself as a Mirror: Social Performance Feedback and Corporate Carbon Reduction Management

Take Itself as a Mirror: Social Performance Feedback and Corporate Carbon Reduction Management

Robust expansion planning and hardening strategy of meshed multi-energy distribution networks for resilience enhancement

As an integrated energy system (IES) incorporated with electricity, gas, and heating networks, the meshed multi-energy distribution network (MMDN) can operate more economically with higher energy utilization efficiency. To achieve high reliability, MMDN is mesh-constructed and radial-operated, complicating the operation scenarios involved in planning. Existing coordinated planning models seldom consider network reconfiguration and hardening strategies collaboratively for extreme contingencies, which is not consistent with actual conditions. In addition, considering the multi-stage discreteness of the expansion planning problem, the existing robust algorithms may feedback invalid cuts. The neglect of such issues could introduce a momentous impact on the optimality of solutions. This paper presents a resiliency-oriented expansion planning and hardening model of MMDN, and the hierarchical algorithm is developed. Specifically, the model is formulated as a min–max-min optimization problem including investment and operation levels. The investment level problem optimizes planning schemes constrained with the robustness verification of the operation level problem. The operation level problem examines the operational cost and feeds back iterative information to the investment level. An additional cuts generation method is developed in the operation level, which effectively deals with invalid feedback information caused by the existing binary variable parameterization. Furthermore, accelerating strategies including infeasible region reduction, multi-cut feedback, and contingency set reduction are developed. To be solved by off-the-shelf solvers, the model is cast as a mixed-integer linear programming (MILP) problem by adopting the convex hull relaxation and linearization techniques for operational constraints with high accuracy. Numerical test results justify the effectiveness of the model.

Compressed Feedback Using Autoencoder Based on Deep Learning for D2D Communication Networks

In this letter, we propose a feedback reduction scheme based on AutoEncoder and deep reinforcement learning for frequency division duplex (FDD) overlay device-to-device (D2D) communication networks. All D2D receivers and transmitters are equipped with an Encoder and Decoder, respectively, of the trained AutoEncoder. The D2D receivers compress the feedback information using the Encoder before transmitting while the transmitters decompress the received feedback information. We also employ a dueling deep Q network (DQN) to allow each D2D transmitter to autonomously determine whether to transmit data based on the decompressed feedback information. The performance of the proposed feedback reduction scheme is analyzed in terms of the average MSE of the AutoEncoder and the average sum-rate of a D2D communication network. Our numerical results show that the proposed feedback reduction scheme using the AutoEncoder can achieve 100%, 89%, and 86% of the average sum-rate of the perfect feedback scheme with no compression when the signal-to-noise ratio is 10dB, −5dB, and −20dB, respectively, while reducing the feedback by 50%.

Enhancement of paclitaxel production by reduced cellular accumulation and alteration in expression pattern of key genes using multi-walled carbon nanotube in Taxus baccata L. cell suspension culture

Paclitaxel (PTX) is an effective chemotherapeutic agent widely used against variety of cancers. PTX is found in the inner bark of several Taxus species. The small-scale of PTX production in Taxus spp. is improved by the platforms based on cell cultures through elicitation. Due to the accumulation of this metabolite in cells and the negative feedback effects, high PTX production level is unavailable. In this context, the effect of multi-walled carbon nanotube (MWCNT) was studied at 100 and 250 mg/L on PTX secretion, feedback reduction, and ultimately increased production of PTX in T. baccata cell suspension culture. The expression pattern of 10 key genes at the up- and downstream of PTX biosynthesis pathway was also evaluated 4 and 72 h after treatment. Our results revealed that under 100 mg/L MWCNT treatment, 18% of total PTX was secreted into the culture medium, while this strongly increased to 96% in 250 mg/L. Correspondingly, the total PTX production increased by 2.7-fold on the 23rd day at 100 mg/L and elevated to 6.7-fold by 250 mg/L compared to the control (non-treated with MWCNT). The expression pattern of ABC transporter gene confirmed the results and showed 2.3-fold reduction in response to 250 mg/L MWCNT compared to the 100 mg/L. The removal of PTX from the cells at 100 mg/L MWCNT enhanced the expression level of upstream genes including GGPP, TXS, T5αOH, T10BOH, T13αOH, and T14BOH. With more PTX secretion to the culture medium at 250 mg/L MWCNT, more expression level was also detected for the DBAT, BAPT, and DBTNBT genes close to the final product (PTX). Our results clearly demonstrated that reduction of negative feedback from PTX biosynthesis pathway by secretion out of the cell can highly improve PTX production, especially under elicitation treatments.

Feed-back Controller Reduction Considering the Variation of the Plant in 2DOF Control System

Feed-back Controller Reduction Considering the Variation of the Plant in 2DOF Control System

Enhancements on Type-II 5G New Radio Codebooks for UE Mobility Scenarios

This article focuses on potential enhancements of current 5G New Radio (NR) codebooks (CBs) for user equipment (UE) mobility scenarios. An overview of the incremental evolution of the 5G NR Type-II CBs is presented, and its inherent drawbacks in mobility scenarios are discussed. The current Type-II CBs fail to deliver adequate performance when used by moving UEs at medium to high speeds, mainly due to the current channel coherence time-based CSI measurement and reporting. Measured channel data from a number of real-world scenarios are analyzed by means of Doppler power spectrum and delay-Doppler power spectrum to verify the so-called channel stationarity time, which is several-fold higher than the channel coherence time. Based on the presented analysis, conclusions are drawn that for stationarity time-based CSI measurements and reporting, Doppler frequency components in addition to space and delay components can be exploited for Type-II CB enhancements. The enhanced Type-II CB achieves a drastic feedback reduction due to the sparse nature of the channel in the delay-Doppler domain and improved performance compared to the 5G NR Type-II CB.

Design refinement and evaluation of a mobile manual standing wheelchair

Purpose There are no manually propelled wheelchairs on the market that are mobile in both seated and standing positions. In response to this product gap, our group formerly designed a mobile manual standing wheelchair (MMSW) and gathered stakeholder feedback. The purpose of this study was to refine the MMSW based on feedback, including weight and width reduction, and evaluate its performance. Materials and methods The MMSW was subjected to ANSI/RESNA stability testing, and three male participants completed a subset of the wheelchair skills test, including a 100-m roll test in the MMSW (seated and standing) and in their ultralight wheelchair. Results The MMSW met ANSI/RESNA stability safety standards. During the 100-m roll test, participants reached speeds with the MMSW in both the standing and sitting postures similar or greater than those typical of moving in the home environment (1.11 m/s seated; 0.79 m/s standing). Mobility speeds in the MMSW in the standing position were about three times faster than average walking speeds in exoskeletons (0.26 m/s exoskeletons). With the addition of chain drive bracing to the MMSW, one user was able to reach speeds in the standing position similar to average neurotypical walking speeds indicating the possibility for wheelchair users to be able to move in pace with family and friends. Conclusion All participants expressed interest in the MMSW to facilitate improved quality of life. Further work is needed to test the utility of the MMSW in home and community settings, and its potential effects on standing time and health outcomes. Implications for rehabilitation Manual standing wheelchairs with standing mobility may increase functional utility and length of standing time for manual wheelchair users Increased standing time may lead to several health benefits for manual wheelchair users

Residual feedback suppression with extended model-based postfilters

When designing closed-loop electro-acoustic systems, which can commonly be found in hearing aids or public address systems, the most challenging task is canceling and/or suppressing the feedback caused by the acoustic coupling of the transducers of such systems. In many applications, feedback cancelation based on adaptive filters is used for this purpose. However, due to computational complexity such a feedback canceler is often limited in the length of the filter’s impulse response. Consequently, a residual feedback, which is still audible and may lead to system instability, remains in most cases. In this work, we present enhancements for model-based postfilters based on a priori knowledge of the feedback path which can be used cooperatively with the adaptive filter-based feedback cancelation system to suppress residual feedback and improve the overall feedback reduction capability. For this, we adapted an existing reverberation model such that our model additionally considers the presence and the performance of the adaptive filter. We tested the effectiveness of our approach by means of both objective and subjective evaluations.

Carbon Nanoparticle Exerts Positive Growth Effects with Increase in Productivity by Down-Regulating Phytochrome B and Enhancing Internal Temperature in Rice

The effects of carbon nanoparticle (CNP) on rice variety Swarna (MTU7029) were investigated. CNP induced effects similar to shade avoidance response (SAR) of Arabidopsis, with increase in shoot length, root length, root number, cotyledon area, chlorophyll content and total sugar content in rice seedlings. In mature plants, CNP treatment resulted increase in plant height, number of productive tillers per plant, normalized difference vegetation index, quantum yield and root growth. A total of 320mg of CNP per plant administered in four doses resulted in improved grain traits such as filled grain rate, 100-grain weight, grain length/width ratio, hulling rate, milling rate and head rice recovery. Seeds from the CNP-treated plants showed increase in amylose, starch and soluble sugar contents compared to controls. Strikingly, CNP treatment showed an average of 17.5% increase in yield per plant. Upon investigation to the molecular mechanism behind CNP induction of SAR, a significant downregulation of phytochrome B transcript was found. Decrease in perception of red wavelengths led to responses similar to SAR. Increase in plant's internal temperature by 0.5°C±0.1°C was recorded after CNP treatment. We suggest that the internalized CNP aggregates may serve to absorb extra photons thereby increasing the internal temperature of plants. Phytochrome B accounts the hike in internal temperature and initiates a feed-back reduction of its own transcription. We suggest that moderate SAR is beneficial for rice plants to improve agronomic traits and yield. It presents a potential non-transgenic method for improving rice yield by CNP treatment.

MSE minimized joint transmission in coordinated multipoint systems with sparse feedback and constrained backhaul requirements

In a joint transmission coordinated multipoint (JT-CoMP) system, a shared spectrum is utilized by all neighbor cells. In the downlink, a group of base stations (BSs) coordinately transmit the users’ data to avoid serious interference at the users in the boundary of the cells, thus substantially improving area fairness. However, this comes at the cost of high feedback and backhaul load; In a frequency division duplex system, all users at the cell boundaries have to collect and send feedback of the downlink channel state information (CSI). In centralized JT-CoMP, although with capabilities for perfect coordination, a central coordination node have to send the computed precoding weights and corresponding data to all cells which can overwhelm the backhaul resources. In this paper, we design a JT-CoMP scheme, by which the sum of the mean square error (MSE) at the boundary users is minimized, while feedback and backhaul loads are constrained and the load is balanced between BSs. Our design is based on the singular value decomposition of CSI matrix and optimization of a binary link selection matrix to provide sparse feedback—constrained backhaul link. For comparison, we adopt the previously presented schemes for feedback and backhaul reduction in the physical layer. Extensive numerical evaluations show that the proposed scheme can reduce the MSE with at least 25%, compared to the adopted and existing schemes.

Active Middle Ear Implant Patient Outcomes With Adaptive Feedback Canceller.

Evaluation of the audiological patient performance with an upgrade of the firmware from the fixed feedback canceller (FFC) to the adaptive feedback canceller (AFC) on an active middle ear implant. Retrospective observational nonrandomized group study. Private hospital. From March 2018 to September 2019, 15 patients implanted with an active middle ear implant, with 6 or more months of experience with a FFC system, were upgraded to an AFC algorithm. Functional gain, speech perception in silence and in noise, and sound localization capacities were examined. Feedback reduction was also analyzed. Thirteen patients were analyzed. Pure tone audiometric evaluation with FFC (mean value of 48.02 dB) compared with AFC at 1 (mean value of 49.12 dB) and 6 months (mean value of 42.75 dB) revealed no statistically significant differences (p = 0.889 and p = 0.358 respectively).In speech discrimination in silence, clinically relevant improvements were observed with AFC at 1 and 6 months, with a mean value of 41.5 and 38.3 dB, respectively (p = 0.03 and p = 0.021 correspondingly). In speech discrimination in noisy environments, we observed an improvement of the different conditions tested. No differences were found in localization capacities between FFC and AFC at the two different moments of evaluation. AFC is more effective than FFC in cancelling feedback and improving sound quality, allowing for better speech understanding in silence and in noise.

Suitability of infrared spectroscopy for drug checking in harm reduction centres

Drug checking is a service for people who use drugs that includes product analysis and an individual interview including results feedback and harm reduction counselling. It uses different analytical methods but few studies demonstrate their value in current practice. The main objective of this work is to compare the analytical performance of IR spectroscopy to laboratory reference method in the context of drug checking in a harm reduction centre. The secondary objectives are to carry out a description of the people who use drugs requesting a product analysis, and to compare the assumed compositions of products purchased with their real compositions. During 2018, all requests for drug testing analysis were included for on-site analysis by IR spectrometry in a harm reduction center and verified by the reference method (UPLC-HRMS) at Bordeaux University Hospital Center. Socioeconomic and product data were also collected. One hundred and thirty-six samples were collected. The results obtained with IR and UPLC-HRMS were compared. IR spectrometry results did not match with reference method in 8 % (n=11) of cases, corresponding to blotters, cannabis and some psychoactive substances present in mixture or in small quantities. Among the products collected, only 5.1 % (n=7) did not correspond to the declared product, either alone or with adulterants. The IR spectrometer allows a simple and rapid detection of at least one molecule, most often the one of interest. However, it is limited to powder and tablet type matrices and is not suitable for blotters, cannabis, mixed or low content substances for which high resolution mass spectrometry remains the reference method.

Effectiveness of Different Training and Testing Parameters on the Formation and Maintenance of Equivalence Classes: Investigating Prejudiced Racial Attitudes

This study aimed to verify the role of three parameters on the formation of equivalence classes between Black faces and a positive symbol, in children who demonstrated negative bias toward Black faces in a pretest. Maintenance was also verified 6 weeks after equivalence tests. Forty-six children (11 Black; 27 girls) who demonstrated racial bias in a pretest were divided into four groups. All groups first learned AB relations (A1 and A2 were, respectively, a positive and a negative symbol, and B were abstract stimuli) and then BC relations (C1 was a Black face and C2 was an abstract stimulus). The Control Group then advanced immediately to equivalence tests (AC, and CA, without differential consequences). For the Mixed Training Group, a block of trials mixing AB and BC relations, with differential consequences, preceded equivalence tests. For the Feedback Reduction Group, equivalence tests were preceded by a trial block mixing AB and BC relations, but with feedback in 50% of trials. The Symmetry Group received symmetry tests after training of each baseline relation. Thirty-three children showed class formation relating Black faces and the positive symbol, and 27 maintained at least one of the equivalence relations after 6 weeks. Average biases toward Black faces were positive in a posttest, for participants who formed equivalence classes, and remained negative for those that did not form classes. The Control Group showed less pronounced bias reduction and maintenance of relations after 6 weeks, suggesting that these outcomes may be affected by training parameters.

Error Rates and Uncertainty Reduction in Rule Discovery

Three new versions of Wason’s 2-4-6 rule discovery task incorporating error rates or feedback of uncertainty reduction, inspired by the error-statistical account in philosophy of science, were employed. In experiments 1 and 2, participants were instructed that some experimenter feedback would be erroneous (control was original 2-4-6 without error). The results showed that performance was impaired when there was probabilistic error. In experiment 3, participants were given uncertainty reduction feedback as they generated different number triples and the negative effects of probabilistic error were not observed. These findings are informative not only about rule discovery tasks in general but also about contexts of inference under uncertainty.

Trajectory Data Driven V2V/V2I Mode Switching and Bandwidth Allocation for Vehicle Networks

Maintaining efficient and reliable communication services in vehicle networks is challenging due to the high mobility of vehicle users. One of the key issues is to deal with the large amount of channel feedback and make better use of limited wireless resources in real time. In this letter, we propose a trajectory data driven method to maximize the total user utilities, which is characterized by intelligent channel state information (CSI) feedback reduction and vehicle-to-vehicle (V2V)/vehicle-to-infrastructure (V2I) mode switching. A deep neural network (DNN) model is trained using optimization approaches and vehicles’ trajectory data. Based on the well trained model, V2V/V2I mode is selected adaptively and bandwidth is allocated optimally with partial channel feedback. Simulation results show that our proposed method outperforms the comparison baseline and can achieve 96.23% of the performance obtained by exhausting searching with full CSI feedback.

Downlink Pilot Precoding and Compressed Channel Feedback for FDD-Based Cell-Free Systems

Cell-free system where a group of base stations (BSs) cooperatively serves users has received much attention as a promising technology for the future wireless systems. In order to maximize the cooperation gain in the cell-free systems, acquisition of downlink channel state information (CSI) at the BSs is crucial. While this task is relatively easy for the time division duplexing (TDD) systems due to the channel reciprocity, it is not easy for the frequency division duplexing (FDD) systems due to the CSI feedback overhead. This issue is even more pronounced in the cell-free systems since the user needs to feed back the CSIs of multiple BSs. In this paper, we propose a novel feedback reduction technique for the FDD-based cell-free systems. Key feature of the proposed technique is to choose a few dominating paths and then feed back the path gain information (PGI) of the chosen paths. By exploiting the property that the angles of departure (AoDs) are quite similar in the uplink and downlink channels (this property is referred to as angle reciprocity), the BSs obtain the AoDs directly from the uplink pilot signal. From the extensive simulations, we observe that the proposed technique can achieve more than 60% reduction in feedback overhead over the conventional CSI feedback scheme.

Signal enhancement for communication systems used by fire fighters

So-called full-face masks are essential for fire fighters to ensure respiratory protection in smoke diving incidents. While such masks are absolutely necessary for protection purposes on one hand, they impair the voice communication of fire fighters drastically on the other hand. For this reason communication systems should be used to amplify the speech and, therefore, to improve the communication quality. This paper gives an overview of communication enhancement techniques for masks based on digital signal processing. The presented communication system picks up the speech signal by a microphone in the mask, enhance it, and play back the amplified signal by loudspeakers located on the outside of such masks. Since breathing noise is also picked up by the microphone, it’s advantageous to recognize and suppress it – especially since breathing noise is very loud (usually much louder than the recorded voice). A voice activity detection distinguishes between side talkers, pause, breathing out, breathing in, and speech. It ensures that only speech components are played back. Due to the fact that the microphone is located close to the loudspeakers, the output signals are coupling back into the microphone and feedback may occur even at moderate gains. This can be reduced by feedback reduction (consisting of cancellation and suppression approaches). To enhance the functionality of the canceler a decorrelation stage can be applied to the enhanced signal before loudspeaker playback. As a consequence of all processing stages, the communication can be improved significantly, as the results of measurements of real-time mask systems show.