Feedforward Information Research Articles

A Model Predictive Control for Coal Beneficiation Dense Medium Cyclones

The purpose of the controller presented is to maintain the proportion of carbon content in the products of the coal washing dense medium cyclone (DMC) at a certain level by optimally manipulating the density of the heavy medium. In practice, the DMC processes are mainly controlled by empirical methods which are process specific and cannot satisfy the industrial requirements today. As a result, industries are looking at introducing sensors to monitor the coal quality from the DMC process. Application of such sensors requires the development of new controllers that can handle large delays and sampled measurement. Therefore, a model based closed-loop control approach is presented to improve the separation efficiency of DMC plants. The feed coal quality is taken as the feed forward information and the sampled and delayed measurement from the DMC output is utilized as feedback for the controller to improve the quality of coal product and ensure the robustness of the controller. In addition, a state updating scheme is presented for the controller because the time delay of the measured feedback can be one hour or longer. The effectiveness of the designed controller is demonstrated by simulations.

Neurology of volition

Neurological disorders of volition may be characterized by deficits in willing and/or agency. When we move our bodies through space, it is the sense that we intended to move (willing) and that our actions were a consequence of this intention (self-agency) that gives us the sense of voluntariness and a general feeling of being "in control." While it is possible to have movements that share executive machinery ordinarily used for voluntary movement but lack a sense of voluntariness, such as psychogenic movement disorders, it is also possible to claim volition for presumed involuntary movements (early chorea) or even when no movement is produced (anosognosia). The study of such patients should enlighten traditional models of how the percepts of volition are generated in the brain with regard to movement. We discuss volition and its components as multi-leveled processes with feedforward and feedback information flow, and dependence on prior expectations as well as external and internal cues.

A predictive coding perspective on autism spectrum disorders

A predictive coding perspective on autism spectrum disorders

Quantitative analysis of defects in university buildings: user perspective

PurposeDefect management is an important segment in building maintenance management. Although defect management requires systemic approach, the purpose of this paper is to focus on the measurement of defects in university buildings based on user perspective.Design/methodology/approachThe paper reviews related literature and presents the outcome of a survey of 550 university buildings users, derived from a convenience sample from five universities.FindingsA total of 20 defects were found to be very critical to the building users. Faulty electrical systems, faulty air conditioning system and roof damages were the defects requiring urgent maintenance. Based on the findings, it was concluded that resources be directed towards defects that affect security, safety and comfort.Research limitations/implicationsThe list of 32 defects may not be exhaustive, but are indicative of defects that affect university building performance. Because the buildings are not prototypes, some of the findings required adaptation. The conclusions were based on data from five universities.Practical implicationsThis study is useful to maintenance organizations in efforts to increase users’ satisfaction, productivity and building performance by guiding resources allocation and at the same time reducing rework, dissatisfaction and waste. The findings would provide feedback and feed forward information and knowledge to the design and construction teams. The study provides a platform to integrate maintenance issues into the design and construction phases of building projects.Originality/valueThere is no such conclusive study on the maintenance of university buildings. Both academics and practitioners can apply the findings to their respective maintenance management scenarios.

Spike suppression in a local cortical circuit induced by transcranial magnetic stimulation

Transcranial magnetic stimulation (TMS) noninvasively interferes with human cortical function, and is widely used as an effective technique for probing causal links between neural activity and cognitive function. However, the physiological mechanisms underlying TMS-induced effects on neural activity remain unclear. We examined the mechanism by which TMS disrupts neural activity in a local circuit in early visual cortex using a computational model consisting of conductance-based spiking neurons with excitatory and inhibitory synaptic connections. We found that single-pulse TMS suppressed spiking activity in a local circuit model, disrupting the population response. Spike suppression was observed when TMS was applied to the local circuit within a limited time window after the local circuit received sensory afferent input, as observed in experiments investigating suppression of visual perception with TMS targeting early visual cortex. Quantitative analyses revealed that the magnitude of suppression was significantly larger for synaptically-connected neurons than for isolated individual neurons, suggesting that intracortical inhibitory synaptic coupling also plays an important role in TMS-induced suppression. A conventional local circuit model of early visual cortex explained only the early period of visual suppression observed in experiments. However, models either involving strong recurrent excitatory synaptic connections or sustained excitatory input were able to reproduce the late period of visual suppression. These results suggest that TMS targeting early visual cortex disrupts functionally distinct neural signals, possibly corresponding to feedforward and recurrent information processing, by imposing inhibitory effects through intracortical inhibitory synaptic connections.

Characterizing “information transfer” by using a Joint Cognitive Systems model to improve continuity of care in the aged

PurposeThis study explores multidisciplinary and cross-sector health professional experiences with the information needs for safe patient transfers across the care continuum using a Joint Cognitive Systems (JCS) model. Qualitative experiences of three JCS components and their attributes and are presented. MethodsA qualitative content analysis using Joint Cognitive Systems constructs were extracted from sixteen multidisciplinary and cross-sector health professional interviews. Participants were asked to describe their information needs and experiences with the patient transfer process. ResultsInformation transfer associated with three JCS constructs (alignment of goals, enhanced control, and co-agency dynamics) was examined. The breakdown in the information transfer process might be due to the relative strengths of each sector's core expertise. Alignment must cross settings and disciplines and consist of the: (1) transfer of goal relevant and integrated information; (2) accommodation to the control attributes of increased clinical complexity, lack of systematic work processes and feedback or feed forward information; and (3) improvement in the co-agency dynamics of interdependency, trust, inter-related actions and expertise. ConclusionsEconomic pressures and care complexities of the aged require improved effectiveness and efficiencies in the information transfer process. This study aims to understand the information transfer needs from hospitals to skilled nursing care laying a foundation towards a medical informatics solution. An informatics solution must accommodate the differing contextual environments and subsequent information needs and paradigms of the Joint Cognitive System of care across the continuum.

Feed-forward and visual feed-back control of head roll orientation in wasps (Polistes humilis, Vespidae, Hymenoptera)

Flying insects keep their visual system horizontally aligned, suggesting that gaze stabilization is a crucial first step in flight control. Unlike flies, hymenopteran insects such as bees and wasps do not have halteres that provide fast, feed-forward angular rate information to stabilize head orientation in the presence of body rotations. We tested whether hymenopteran insects use inertial (mechanosensory) information to control head orientation from other sources, such as the wings, by applying periodic roll perturbations to male Polistes humilis wasps flying in tether under different visual conditions indoors and in natural outdoor conditions. We oscillated the thorax of the insects with frequency-modulated sinusoids (chirps) with frequencies increasing from 0.2 to 2 Hz at a maximal amplitude of 50 deg peak-to-peak and maximal angular velocity of ±245 deg s(-1). We found that head roll stabilization is best outdoors, but completely absent in uniform visual conditions and in darkness. Step responses confirm that compensatory head roll movements are purely visually driven. Modelling step responses indicates that head roll stabilization is achieved by merging information on head angular velocity, presumably provided by motion-sensitive neurons and information on head orientation, presumably provided by light level integration across the compound eyes and/or ocelli (dorsal light response). Body roll in free flight reaches amplitudes of ±40 deg and angular velocities greater than 1000 deg s(-1), while head orientation remains horizontal for most of the time to within ±10 deg. In free flight, we did not find a delay between spontaneous body roll and compensatory head movements, and suggest that this is evidence for the contribution of a feed-forward control to head stabilization.

A high-speed tunable beam splitter for feed-forward photonic quantum information processing

We realize quantum gates for path qubits with a high-speed, polarization-independent and tunable beam splitter. Two electro-optical modulators act in a Mach-Zehnder interferometer as high-speed phase shifters and rapidly tune its splitting ratio. We test its performance with heralded single photons, observing a polarization-independent interference contrast above 95%. The switching time is about 5.6 ns, and a maximal repetition rate is 2.5 MHz. We demonstrate tunable feed-forward operations of a single-qubit gate of path-encoded qubits and a two-qubit gate via measurement-induced interaction between two photons.

Central circuitries for body temperature regulation and fever

Body temperature regulation is a fundamental homeostatic function that is governed by the central nervous system in homeothermic animals, including humans. The central thermoregulatory system also functions for host defense from invading pathogens by elevating body core temperature, a response known as fever. Thermoregulation and fever involve a variety of involuntary effector responses, and this review summarizes the current understandings of the central circuitry mechanisms that underlie nonshivering thermogenesis in brown adipose tissue, shivering thermogenesis in skeletal muscles, thermoregulatory cardiac regulation, heat-loss regulation through cutaneous vasomotion, and ACTH release. To defend thermal homeostasis from environmental thermal challenges, feedforward thermosensory information on environmental temperature sensed by skin thermoreceptors ascends through the spinal cord and lateral parabrachial nucleus to the preoptic area (POA). The POA also receives feedback signals from local thermosensitive neurons, as well as pyrogenic signals of prostaglandin E(2) produced in response to infection. These afferent signals are integrated and affect the activity of GABAergic inhibitory projection neurons descending from the POA to the dorsomedial hypothalamus (DMH) or to the rostral medullary raphe region (rMR). Attenuation of the descending inhibition by cooling or pyrogenic signals leads to disinhibition of thermogenic neurons in the DMH and sympathetic and somatic premotor neurons in the rMR, which then drive spinal motor output mechanisms to elicit thermogenesis, tachycardia, and cutaneous vasoconstriction. Warming signals enhance the descending inhibition from the POA to inhibit the motor outputs, resulting in cutaneous vasodilation and inhibited thermogenesis. This central thermoregulatory mechanism also functions for metabolic regulation and stress-induced hyperthermia.

Bi-level optimizing control of a simulated moving bed process with nonlinear adsorption isotherms

Abstract A bi-level optimizing control scheme originally proposed for a simulated moving bed (SMB) with linear isotherms has been extended to an SMB with nonlinear isotherms. Cyclic steady state optimization is performed in the upper level to determine the optimum switching period and time-varying feed/desorbent flow rates, and repetitive model predictive control is run in the lower level for purity regulation, taking the decision variables from the upper level as feed-forward information. Experimental as well as numerical study for an SMB process separating a high-concentration mixture of aqueous l-ribose and l-arabinose solutions showed that the proposed scheme performs satisfactorily against various disturbances. In contrast, an alternative scheme based on an SMB model with linear isotherms showed a limitation in the control performance; this scheme was apt to fail in purity regulation.

Feed-forward neural network assisted by discriminant analysis for the spectroscopic discriminantion of cracked spores Ganoderma lucidum: A prospective biotechnology production tool.

A major problem for manufacturers of cracked spores Ganoderma lucidum, a traditional functional food/Chinese medicine (TCM), is to ensure that raw materials are consistent as received from the producer. To address this, a feed-forward artificial neural network (ANN) method assisted by linear discriminant analysis (LDA) and principal component analysis (PCA) was developed for the spectroscopic discrimination of cracked spores of Ganoderma lucidum from uncracked spores. 120 samples comprising cracked spores, uncracked spores and concentrate of Ganoderma lucidum were analyzed. Differences in the absorption spectra located at ν1 (1143 - 1037 cm-1), ν2 (1660 - 1560 cm-1), ν3 (1745 - 1716 cm-1) and ν4 (2845 - 2798 cm-1) were identified by applying fourier transform infra-red (FTIR) spectroscopy and used as variables for discriminant analysis. The utilization of spectra frequencies offered maximum chemical information provided by the absorption spectra. Uncracked spores gave rise to characteristic spectrum that permitted discrimination from its cracked physical state. Parallel application of variables derived from unsupervised LDA/PCA provided useful (feed-forward) information to achieve 100% classification integrity objective in ANN. 100% model validation was obtained by utilizing 30 independent samples. ν1 was used to construct the matrix-matched calibration curve (n = 10) based on 4 levels of concentration (20%, 40%, 60% and 80% uncracked spores in cracked spores). A coefficient of correlation (r) of 0.97 was obtained. Relative standard deviation (RSD) of 11% was achieved using 100% uncracked spores (n = 30). These results demonstrate the feasibility of utilizing a combination of spectroscopy and prospective statistical tools to perform non destructive food quality assessment in a high throughput environment.

Evaluating the effectiveness of a priori information on process measures in a virtual reality inspection task

Due to the nature of the complexity of the aircraft maintenance industry, much emphasis has been placed on improving aircraft inspection performance. One proven technique for improving inspection performance is the use of training. Several strategies have been implemented for training, one of which is giving feedforward information. The use of a priori (feedforward) information is known to positively affect inspection performance (Ernst and Yovits, 1972; Long and Rourke, 1989; McKernan, 1989; Gramopadhye et al., 1997). This information can consist of knowledge about defect characteristics (types, severity/criticality, and location) and the probability of occurrence. Although several studies have been conducted that demonstrate the usefulness of feedforward as a training strategy, there are certain research issues that need to be addressed. This study evaluates the effects of feedforward information on process measures in a simulated 3-dimensional environment (aircraft cargo bay) by the use of virtual reality

Evaluating the effectiveness of a priori information on process measures in a virtual reality inspection task

72 1024x768 Normal 0 false false false Due to the nature of the complexity of the aircraft maintenance industry, much emphasis has been placed on improving aircraft inspection performance. One proven technique for improving inspection performance is the use of training. Several strategies have been implemented for training, one of which is giving feedforward information. The use of a priori (feedforward) information is known to positively affect inspection performance (Ernst and Yovits, 1972; Long and Rourke, 1989; McKernan, 1989; Gramopadhye et al., 1997).   This information can consist of knowledge about defect characteristics (types, severity/criticality, and location) and the probability of occurrence. Although several studies have been conducted that demonstrate the usefulness of feedforward as a training strategy, there are certain research issues that need to be addressed. This study evaluates the effects of feedforward information on process measures in a simulated 3-dimensional environment (aircraft cargo bay) by the use of virtual reality.

Hierarchical computation in the canonical auditory cortical circuit

Sensory cortical anatomy has identified a canonical microcircuit underlying computations between and within layers. This feed-forward circuit processes information serially from granular to supragranular and to infragranular layers. How this substrate correlates with an auditory cortical processing hierarchy is unclear. We recorded simultaneously from all layers in cat primary auditory cortex (AI) and estimated spectrotemporal receptive fields (STRFs) and associated nonlinearities. Spike-triggered averaged STRFs revealed that temporal precision, spectrotemporal separability, and feature selectivity varied with layer according to a hierarchical processing model. STRFs from maximally informative dimension (MID) analysis confirmed hierarchical processing. Of two cooperative MIDs identified for each neuron, the first comprised the majority of stimulus information in granular layers. Second MID contributions and nonlinear cooperativity increased in supragranular and infragranular layers. The AI microcircuit provides a valid template for three independent hierarchical computation principles. Increases in processing complexity, STRF cooperativity, and nonlinearity correlate with the synaptic distance from granular layers.

Neural Activity in the Middle Temporal Area and Lateral Intraparietal Area during Endogenously Cued Shifts of Attention

We measured the behavioral time course of endogenously cued attentional shifts while recording from neurons in the middle temporal area (MT) and lateral intraparietal area (LIP) of two macaque monkeys. The monkeys were required to detect a subtle speed change of one of two continuously moving stimuli. The likely location of the speed change was cued throughout each trial but could switch at an unpredictable time. Attention was evident as an improvement in detection ability and reaction time at the cued location, and the focus of attention shifted over a 400 ms period in response to a switch of the cued stimulus. Attention modulated the ongoing neural response in both MT and LIP, and the sign of this modulation also rapidly shifted after a cue switch. Our data provide a framework for understanding the link between the neural and behavioral effects of attention. The responses of single neurons to the test stimulus in MT and LIP were correlated with stimulus detection and reaction time and, at the population level, a spike-rate threshold model was able to account for the effect of attention on detection rate and reaction time. In this view, the time course of the attentional shift can be understood as an interaction between the emerging attentional modulation and the neural response to the test stimulus in LIP. We also present evidence that the threshold model is not wholly explained by sensory (feedforward) information but may also be influenced by cognitive (feedback) processes at the time of stimulus detection.

A Feasibility Study of Bihormonal Closed-Loop Blood Glucose Control Using Dual Subcutaneous Infusion of Insulin and Glucagon in Ambulatory Diabetic Swine

We sought to test the feasibility and efficacy of bihormonal closed-loop blood glucose (BG) control that utilizes subcutaneous (SC) infusion of insulin and glucagon, a model-predictive control algorithm for determining insulin dosing, and a proportional-derivative control algorithm for determining glucagon dosing. Thirteen closed-loop experiments (approximately 7-27 h in length) were conducted in six ambulatory diabetic pigs weighing 26-50 kg. In all experiments, venous BG was sampled through a central line in the vena cava. Efficacy was evaluated in terms of the controller's ability to regulate BG in response to large meal disturbances ( approximately 5 g of carbohydrate per kilogram of body mass per meal) based only on regular frequent venous BG sampling and requiring only the subject's weight for initialization. Closed-loop results demonstrated successful BG regulation to normoglycemic range, with average insulin-to-carbohydrate ratios between approximately 1:20 and 1:40 U/g. The total insulin bolus doses averaged approximately 6 U for a meal containing approximately 6 g per kilogram body mass. Mean BG values in two 24 h experiments were approximately 142 and approximately 155 mg/dl, with the total daily dose (TDD) of insulin being approximately 0.8-1.0 U per kilogram of body mass and the TDD of glucagon being approximately 0.02-0.05 mg. Results also affirmed the efficacy of SC doses of glucagon in staving off episodic hypoglycemia. We demonstrate the feasibility of bihormonal closed-loop BG regulation using a control system that employs SC infusion of insulin and glucagon as governed by an algorithm that reacts only to BG without any feed-forward information regarding carbohydrate consumption or physical activity. As such, this study can reasonably be regarded as the first practical implementation of an artificial endocrine pancreas that has a hormonally derived counterregulatory capability.

Modelling of cortical and thalamic 600 Hz activity by means of oscillatory networks

The purpose of this study is to investigate information processing in the primary somatosensory system with the help of oscillatory network modelling. Specifically, we consider interactions in the oscillatory 600 Hz activity between the thalamus and the cortical Brodmann areas 3b and 1. This type of cortical activity occurs after electrical stimulation of peripheral nerves such as the median nerve. Our measurements consist of simultaneous 31-channel MEG and 32-channel EEG recordings and individual 3D MRI data. We perform source localization by means of a multi-dipole model. The dipole activation time courses are then modelled by a set of coupled oscillators, described by linear second-order ordinary delay differential equations (DDEs). In particular, a new model for the thalamic activity is included in the oscillatory network. The parameters of the DDE system are successfully fitted to the data by a nonlinear evolutionary optimization method. To activate the oscillatory network, an individual input function is used, based on measurements of the propagated stimulation signal at the biceps. A significant feedback from the cortex to the thalamus could be detected by comparing the network modelling with and without feedback connections. Our finding in humans is supported by earlier animal studies. We conclude that this type of rhythmic brain activity can be modelled by oscillatory networks in order to disentangle feed forward and feedback information transfer.

めまいと前庭脊髄路系異常‐タクタイル・センサーによる歩行分析‐（末梢前庭障害を中心に）

Integration of the normal equilibrium function, space orientation and cognitive functions is needed to complete straight-line walking. Also, visual and vestibular inputs play important roles in a constantly varying 3-dimensional environment to ensure smooth locomotion. However, in vestibular disorders, patients suffer problems of gait instability. The characteristics of the instability might reflect the site and severity of the lesion. How can these abnormalities be delineated objectively? To gain an understanding from the physiological viewpoint, gait analysis under eyes-opened and blindfolded conditions was conducted using tactile sensors (F-scan system) in patients with various types of vestibular lesions. All of the data were reviewed and summarized to evaluate the usefulness and limitations of this analysis method.The coefficients of variation of gait phase-related parameters were evaluated, such as stance, swing and double support, integrated foot pressure, stability, movement and average length of the trajectories of the center of force (TCOF), and the pattern of foot pressure progression during stance which can be divided into three phases: body weight acceptance, body weight translation, and body weight thrust. Comparison of the mean values was conducted using the two-tailed t-test, with p<0.05 set as the criterion for statistical significance.The patients enrolled were those with vestibular neuritis (VN; 14 cases), acoustic tumors (AT; 61 cases: 27cases of small AT and 34 cases of large AT), and spinocerebellar degeneration (SCD; 12 cases). Healthy adults (23 subjects) served as controls.Gait instability is depicted by increment of the coefficient of variation of each gait phase. Visual cue plays an important role in providing feed-forward information for steady locomotion. Unilateral vestibular lesions could shift the body center of gravity towards the lesion side, which leads to greater foot pressure on the lesion-side foot with greater horizontal sway of the TCOF during gait, especially during gait with eyes closed. An irregular pattern of foot pressure progression could also reflect gait instability, and was most prominently found in the patients with SCD. As for the average length of TCOF, significantly longer trajectories were found in SCD patients, especially as compared with the findings in vestibular neuritis.In conclusion, gait analysis with the use of a foot pressure sensor can provide useful information for understanding gait abnormalities caused by vestibular disorders. It would be clinically useful to perform gait testing for the evaluation of gait abnormalities in vertigo patients.

Exploiting Transmit Buffer Information at the Receiver in Block-Fading Channels

It is well known that channel state information at the transmitter (CSIT) leads to higher throughput in fading channels. We motivate the use of transmit buffer information at receiver (TBIR). The thesis of this paper is that having partial or complete instantaneous TBIR leads to a lower packet loss rate in block-fading channels assuming the availability of partial CSIT. We provide a framework for the joint design and analysis of feedback (FB) and feed-forward (FF) information in fading channels. We then introduce two forms of TBIR—statistical and instantaneous—and show the gains of each form of TBIR using a heuristic scheme. For a Rayleigh fading channel, we show that in certain cases the packet error rate reduces by nearly an order of magnitude with just one bit of feed-forward information of TBIR.

Visual attention amplifies response priming of pointing movements to color targets

We studied the influence of spatial visual attention on the time course of primed pointing movements. We measured pointing responses to color targets preceded by color stimuli priming either the same response as the target or the opposite response. The effects of visual attention at the prime and target locations were studied by varying both the cue-prime and prime-target intervals when presenting either exogenous attentional cues or, in a separate experiment, endogenous cues whose processing was a precondition for performing the task. Pointing trajectories revealed large priming effects in which pointing responses were first controlled by prime signals and then captured in midflight by target signals. Priming effects were strongly amplified when the relevant prime locations were visually attended at optimal cue-prime SOAs, with attention modulating the entire time course of the primed pointing movements. We propose that visual attention amplifies the earliest waves of visuomotor feedforward information, elicited in turn by primes and by targets.