Feedback Phenomenon Research Articles

РЕЦЕНЗІЯ НА МОНОГРАФІЮ С. В. МАШКЕВИЧА «Історія Київського міського транспорту. Кінець XIX – початок XXI ст. Київ: ВАРТО, 2019. – 680 с.»

The monograph by S. V. Mashkevich «History of the Kiev Urban Transport. End of XIX – beginning of the XXI century» is reviewed. It is noted that the monograph in question is the first comprehensive study of the history of Kiev urban transport in historiography. It tells about the history of the Kiev City Railway Society as a private enterprise and describes in detail the urban transport as a new public urban subspace. The new tasks facing the transport system of Kiev in the XX and at the beginning of the XXI century and the methods of their solution are characterized. It is shown how the system emerged from three crises, and a comparison of these three situations is put forward. Patterns of the evolution of Kiev transport are established and analyzed; four transformations of Kiev urban transport as a system are analyzed; it is substantiated when and how feedback phenomena took place in this system and what was their effect. The conclusion is that the reviewed monograph as a whole makes a positive impression; the author has successfully carried out all his research tasks. This work is a significant contribution to the historiography of Kiev.

ALMA captures feeding and feedback from the active galactic nucleus in NGC 613

We report ALMA observations of CO(3–2) emission in the Seyfert/nuclear starburst galaxy NGC 613, at a spatial resolution of 17 pc, as part of our NUclei of GAlaxies (NUGA) sample. Our aim is to investigate the morphology and dynamics of the gas inside the central kiloparsec, and to probe nuclear fueling and feedback phenomena. The morphology of CO(3–2) line emission reveals a two-arm trailing nuclear spiral at r ≲ 100 pc and a circumnuclear ring at a radius of ∼350 pc that is coincident with the star-forming ring seen in the optical images. Also, we find evidence for a filamentary structure connecting the ring and the nuclear spiral. The ring reveals two breaks into two winding spiral arms corresponding to the dust lanes in the optical images. The molecular gas in the galaxy disk is in a remarkably regular rotation, however the kinematics in the nuclear region are very skewed. The nuclear spectrum of CO and dense gas tracers HCN(4–3), HCO+(4–3), and CS(7–6) show broad wings up to ±300 km s−1, associated with a molecular outflow emanating from the nucleus (r ∼ 25 pc). We derive a molecular outflow mass Mout = 2 × 106 M⊙ and a mass outflow rate of Ṁout = 27 M⊙ yr−1. The molecular outflow energetics exceed the values predicted by AGN feedback models: the kinetic power of the outflow corresponds to PK, out = 20%LAGN and the momentum rate is Ṁoutv ∼ 400LAGN/c. The outflow is mainly boosted by the AGN through entrainment by the radio jet, but given the weak nuclear activity of NGC 613, we might be witnessing a fossil outflow resulting from a previously strong AGN that has now faded. Furthermore, the nuclear trailing spiral observed in CO emission is inside the inner Lindblad resonance ring of the bar. We compute the gravitational torques exerted in the gas to estimate the efficiency of the angular momentum exchange. The gravity torques are negative from 25 to 100 pc and the gas loses its angular momentum in a rotation period, providing evidence for a highly efficient inflow towards the center. This phenomenon shows that the massive central black hole has significant dynamical influence on the gas, triggering the inflowing of molecular gas to feed the black hole.

Pengaruh Teacher Feedback terhadap Kemampaun Murid dalam Pembelajaran Writing

Abstract The research aimed to describe the phenomena of feedback given by the teacher in learning writing. In addition, this study was also described how the response given by the student when receiving feedback from the teacher. The long term goal to be achieved was the improvement of the teaching system so that every educational institution had aimed at teaching concepts to form an intelligent generation. This study was a descriptive qualitative research to be carried out in SMA Muhammadiyah 1 Unismuh Makassar which one of top schools Muhammadiyah. The ability of students in the school had been considered good in communication, but their ability to write was still lacking , especially in terms of grammatical . Therefore, the researcher was described the feedback given by the subject teachers of English subjects at the time of writing , especially when students learned making mistakes in the process of teaching and learning in the classroom . The extent, the teacher can give feedback to the students. The research was described the positive feedback and negative feedback given by the teacher so that it can be information and feedback in the learning process.Giving feedback subject teachers more English language based situation in the classroom. In writing instructional materials for example, most teachers use an explicit correction and metalinguistic feedback. This is because students are using written language than spoken language. Almost kinds of feedback used in teaching but not as often as with the two types of feedback. The students have different conditions, but most were more likely to agree given feedback after speaking or after making a mistake. The most powerful reason is the lack of experience of students in learning English so want to get direct feedback.Key words: Teacher Feedback, murid, Writing

Theoretical and experimental study of liquid refractive index measurement method based on the double external-cavity-laser feedback effect

A liquid refractive index (RI) measurement method based on the double external-cavity laser feedback effect is proposed. The method uses a laser beam to simultaneously enter the top and bottom surfaces of the liquid to be tested, with the light reflected from the two surfaces returning to the laser cavity along the original path, forming a double external-cavity system. When the liquid level rises, the self-mixing interference signal, caused by the optical path from the top and bottom liquid surfaces, superimposes on the tuning intensity of the laser, and the RI of the liquid can be obtained by demodulating the amplitude-frequency feedback tuning curve. This method offers the following innovative performances. Firstly, the structure of the system is simple and the measuring range is large. Secondly, the measurement results can be traced back to one physical quantity, i.e. the RI of air. Thirdly, it has been proved that the laser feedback effect is ubiquitous in all types of lasers, and the change of wavelength does not affect the feedback phenomenon, so that the method is not limited by the type and wavelength of the laser.

Creative Jolts: Responses to Existentially Threatening Feedback by Early Stage Entrepreneurs

Feedback constitutes an essential part of the creative process. While recent research has greatly improved our understanding of how feedback interactions can shape emerging ideas over time (Harrison & Rouse, 2015), it has largely omitted strongly affective episodes whereby the very point or viability of a creator’s idea are called into question. In this paper, we focus on unexpected instances where feedback sets up an existential threat condition for the creator, requiring him/her to respond in a potentially radical way. We label this affective trigger-response process the creative jolt episode and utilize an inductive multiple-case study design to examine 10 such episodes based on longitudinal qualitative research into the idea journeys of early-stage digital entrepreneurs in London (which we researched exhaustively for eight to thirteen months). We make an original contribution to organizational creativity research by (1) empirically investigating and preliminary theorizing the phenomenon of existential feedback; (2) demonstrating how and why such feedback can have generative effects, producing marked shifts in creators’ idea journeys; and (3) offering an original process model detailing two contrasting creative jolt pathways. We argue that disruptive episodes of existential feedback – that are relatively rare yet potentially transformative – should be incorporated into our understanding of the dynamic relationship between feedback and creativity over time. (This is an Academy of Management best paper proceedings contribution presented at AOM in 2019)

On the Dynamics of Distributed Energy Adoption: Equilibrium, Stability, and Limiting Capacity

The death spiral hypothesis in electric utility represents a positive feedback phenomenon in which a regulated utility is driven to financial instability by rising prices and declining demand. We establish conditions for the existence of death spiral and conditions of stable adoption of distributed energy resources. We show in particular that linear tariffs always induce death spiral when the fixed operating cost of the utility rises beyond a certain threshold. For two-part tariffs with connection and volumetric charges, the Ramsey pricing that optimizes myopically social welfare subject to the revenue adequacy constraint induces a stable equilibrium. The Ramsey pricing, however, inhibits renewable adoption with a high connection charge. In contrast, a two-part tariff with a small connection charge results in a stable adoption process with a higher level of renewable adoption and greater long-term total consumer surplus. Market data are used to illustrate various solar adoption scenarios.

SOCIAL ENTERPRISE IN SOCIAL MARKET ECONOMY

The aim of the article is to confirm the thesis that social enterprises have a big impact on maximizing social benefits and reducing disparities and social exclusion in the state with the social market economy, as well as in a country without a social market economy system. To achieve the goal, the assumptions of the social market economy and social enterprises were presented, both in terms of model and practical function-ing in Polish conditions. The authors use the deductive method of selected scientific publications, as well as the comparative method both in the efficiency of legal forms and business models of social enterprises, and the positive feedback phenomenon be-tween the social and micro-social dimension when the social enterprise penetrates complementarily through the order of the social market economy.

The effects of the “two-way feedback mechanism” on the maintenance of persistent heavy aerosol pollution over areas with relatively light aerosol pollution in northwest China

Persistent heavy aerosol pollution episodes (HPEs) often occur in the central and eastern regions of China during the wintertime. When PM2.5 mass concentration cumulates to a certain extent that normally exceeds 100 μg m−3, the PM2.5 pollution will then further worsen the meteorological conditions in boundary layer (BL), resulting in significant two-way feedback between the cumulative PM2.5 pollution and worsened meteorological conditions. In the less polluted northwest area of China, whether there is significant two-way feedback phenomenon mentioned above after the accumulation of PM2.5 mass concentration has always been an issue of concern for understanding the full picture of meteorological causes of HPEs in China. Here, measurements of PM2.5 concentration, meteorological data and an integrated pollution-linked meteorological index (PLAM) are used to characterize the relationship between meteorological elements and PM2.5 concentration in persistent HPEs from 1 December 2016 to 10 January 2017 in Lanzhou and Urumqi. In early stage of the HPEs formation, the general 500 hPa circulation situations are normally high-pressure ridge or zonal westerly airflow patterns, associating with worsened meteorological conditions. At this time, with the decrease of BL height, the mass concentration of PM2.5 also increases as the pollutants mix in a relatively small space as compared to the clean period. When PM2.5 cumulates to a certain extent (above 75 μg m−3 in Lanzhou and above 100 μg m−3 in Urumqi), there are often obvious inversion and humidification in the near-surface. The inversion is mainly caused by the accumulation of the PM2.5 concentration, which indicates that even in northwest China, where anthropogenic activities are less affected and PM2.5 pollution is less serious, the cumulative PM2.5 can nonetheless worsen meteorological conditions. The worsened meteorological conditions, which are quantified by the PLAM index, dominate the changes in PM2.5 in the explosive growth of persistent HPEs (accounted for 50–85%).

Are Bitcoin bubbles predictable? Combining a generalized Metcalfe's Law and the Log-Periodic Power Law Singularity model.

We develop a strong diagnostic for bubbles and crashes in Bitcoin, by analysing the coincidence (and its absence) of fundamental and technical indicators. Using a generalized Metcalfe’s Law based on network properties, a fundamental value is quantified and shown to be heavily exceeded, on at least four occasions, by bubbles that grow and burst. In these bubbles, we detect a universal super-exponential unsustainable growth. We model this universal pattern with the Log-Periodic Power Law Singularity (LPPLS) model, which parsimoniously captures diverse positive feedback phenomena, such as herding and imitation. The LPPLS model is shown to provide an ex ante warning of market instabilities, quantifying a high crash hazard and probabilistic bracket of the crash time consistent with the actual corrections; although, as always, the precise time and trigger (which straw breaks the camel’s back) is exogenous and unpredictable. Looking forward, our analysis identifies a substantial but not unprecedented overvaluation in the price of Bitcoin, suggesting many months of volatile sideways Bitcoin prices ahead (from the time of writing, March 2018).

The Place of Feedback in the Pedagogical System of the Lesson

The article deals with the place of feedback in the pedagogical system of the lesson. We made analysis of the phenomenon of psychological feedback in the context of its use in the educational process, the place of feedback in the pedagogical system of the lesson, the main feedback function.Feedback, as the main component of the management process, was investigated in the relation to the processes occurring in educational systems - pedagogical and psychological. We focused on the analysis of the information model of individual memory proposed by Richard Atkinson. The emergence of information and communication technology tools in the educational process makes it possible to use the postulates developed in control theory in the man-machine systems and, at the same time, creates new psychological and pedagogical problems requiring the search for new solutions. Undoubtedly, feedback remains an important factor in the learning process. We made the conclusion that the multifunctional feedback, its interaction with such psychological phenomena as communication barriers, communicative influence, levels and directions of information transfer make it an essential element of the entire lesson communication system with the use of information and communication technology tools.

Convective flow in the presence of a small obstacle: Symmetry breaking, attractors, hysteresis, and information.

This work explores the stability and hysteresis effects that occur when a small sink of momentum is introduced into a heat-driven, two-dimensional convective flow. As per standard fluid mechanical intuition, the system minimizes work generation and dissipation when one component of momentum is extracted. However, when the sink absorbs all incoming momentum, the system configures itself such that one of the convection plumes aligns directly with the sink. This state is the most hydrodynamically stable, but it maximizes, rather than minimizes extracted mechanical work. Furthermore, in the case of only vertical momentum extraction, there are two attractors, with different stabilities. Numerical experiments involving slow variations of the horizontal momentum extraction show a clear history dependence. This hysteresis preserves information about the system's past states, and hence represents a primitive memory. The momentum sink can also be used to manipulate the horizontal position of the flow field, with potential applications in microfluidics and laminar convection systems. This simple system exhibits the phenomena of autocatalysis (during the initial growth of the convection plumes), negative feedback (the attractors are either fully or quasistable), memory, and elementary computation.

Alleviation of Thermal Instability via Novel Collector-Up HBTs for Reliable Wireless Applications

We analyzed thermal characteristics of power transistors based on the complementary InGaP/InGaAs/GaAs collector-up heterojunction bipolar transistors (HBTs), and especially for stable wireless applications under extreme operations. A newly developed structure, incorporating the graded InGaAs base and the nonuniform collector, without employing additional thermal-removal design is presented. Significantly, the multi-finger devices achieved compelling high speed and heat dissipation. Results show that the fairly matched high-frequency performance has been exhibited and over 30% improvement in the surface-temperature-rise ratio is achieved. As a consequence of the effective alleviation of unstable feedback phenomena by this novel arrangement, exploiting the advantageous characteristics of complementary collector-up HBTs for thermally reliable high-speed wireless applications is feasible.

Clasp-Knife Model of Muscle Spasticity for Simulation of Robot-Human Interaction

The objective of this research was to replicate the muscle tone moment feedback of elbow upon passive mobilization and classify them based on modified ashworth scale criterion using a mathematical model. The proposed model enables the visualization of muscle tone pattern for robotic interaction simulation. A concurrent muscle tone model necessitates a jerk effect to fully replicate the catch and release effect, also known as, clasp-knife phenomenon of muscle tone feedback. However, the research of passive mobilization control interaction between robot and subject does not emulate such phenomenon. Thus, the model was improvised to replicate the clasp-knife phenomenon according to the robot’s gross kinematics and dynamics. The model was designed based on the quantitative pattern of muscle tone feedback from subject with spasticity. The simulated model was then correlated to clinical measures using similar kinematic and dynamic input. The velocity dynamic input was splined to obtain the velocity trend without the jerk effect. The results obtained from the proposed model were relatively promising with an overall $(n=9\times 4)$ linear (Pearson) correlated average of $\bar {r}=0.8348$ for nine subjects with correlation significant at the 0.01 level ( $p ) and five of them presented a distinctive clasp-knife phenomenon with correlation average of $\bar {r}=0.8631$ .

Steep Slope Silicon-On-Insulator Feedback Field-Effect Transistor: Design and Performance Analysis

Feedback field-effect transistor (FBFET), an alternative switching device, has received attention due to its ideal steep switching feature. By utilizing the positive feedback phenomenon, the total amount of electrons and holes contributing to drain current is sharply surged. Although the device has conspicuous subthreshold slope (SS) properties, advanced research for structure and performance of it is lacking. In this paper, single-gated and spacer-less silicon-on-insulator (SOI) FBFET with extremely steep switching (~1 mV/decade) characteristic is studied in various aspects; SS attribute, performance variation of scaled FBFET, the impact of structural variation, the gate margin for the device layout, and the hysteresis window. The prospect of SOI FBFET as a future candidate for CMOS logic application is investigated in detail.

Molecular gas content in obscured AGN at z > 1

Aims. The standard active galactic nuclei (AGN)-galaxy co-evolutionary scenario predicts a phase of deeply “buried” supermassive black hole growth coexisting with a starburst (SB) before feedback phenomena deplete the cold molecular gas reservoir of the galaxy and an optically luminous quasar (QSO) is revealed (called the SB-QSO evolutionary sequence). The aim of this work is to measure the cold gas reservoir of three highly obscured QSOs to test if their gas fraction is similar to that of submillimetre galaxies (SMGs), as expected by some models, and to place these measurements in the context of the SB-QSO framework. Methods. We target CO(1-0) transition in BzK4892, a Compton thick (CT) QSO at z = 2.6, CO(1-0) in BzK8608 and CO(2-1) in CDF153, two highly obscured (NH ≈ 6 × 1023 cm−2) QSOs at z = 2.5 and z = 1.5, respectively. For these targets, we place 3σ upper limits on the CO lines, with L′CO < (1.5 ÷ 2.8)×1010 K km s−1 pc2. We also compare the molecular gas conditions of our targets with those of other systems at z > 1, considering normal star-forming galaxies and SMGs, and unobscured and obscured AGN from the literature. For the AGN samples, we provide an updated and almost complete collection of targets with CO follow-up at z > 1. Results. BzK4892 displays a high star formation efficiency (SFE = LIR/L′CO > 410 L⊙/(K km s−1 pc2 )) and a gas fraction fgas = Mgas/(Mstar + Mgas)< 10%. Less stringent constraints are derived for the other two targets (fgas < 0.5 and SFE > 10 L⊙/(K km s−1 pc2 )). From the comparison with the literature data we found that, on average, i) obscured AGN at z > 1 are associated with higher SFE and lower fgas with respect to normal star-forming galaxies and SMGs; ii) mildly and highly obscured active galaxies have comparable gas fractions; iii) the SFE of CT and obscured AGN are similar to those of unobscured AGN. Conclusions. Within the SB-QSO framework, these findings could be consistent with a scenario where feedback can impact the host galaxy already from the early phases of the SB-QSO evolutionary sequence.

Graphene Packaging for Thermal Management of Innovative Complementary Collector-Up Heterojunction Bipolar Transistors

This exploration emphasizes the juxtaposition of thermal stability in InGaP/GaAs p-n-p and n-p-n collector-up (C-up) heterojunction bipolar transistors (HBTs), and specially for the performance-matched complementary wireless applications under extreme operations. High-quality graphene packaging, beneath the graded InGaAs base and the nonuniform collector of C-up HBTs, is proposed. Significantly, the multifinger devices achieved compeling high speed and heat dissipation. The results show that the reasonably matched performance has been exhibited, and a remarkable improvement in the surface temperature rise is attained. Due to the effective alleviation of adverse feedback phenomena by using this innovation, a better thermal stability in the p-n-p device than in the n-p-n device has been evidently observed.

Revealing magnetic fields towards massive protostars: a multi-scale approach using masers and dust

AbstractMagnetic fields play a significant role during star formation processes, hindering the fragmentation and the collapse of the parental cloud, and affecting the accretion mechanisms and feedback phenomena. However, several questions still need to be addressed to clarify the importance of magnetic fields at the onset of high-mass star formation, such as how strong they are and at what evolutionary stage and spatial scales their action becomes relevant. Furthermore, the magnetic field parameters are still poorly constrained especially at small scales, i.e. few astronomical units from the central object, where the accretion disc and the base of the outflow are located. Thus we need to probe magnetic fields at different scales, at different evolutionary steps and possibly with different tracers. We show that the magnetic field morphology around high-mass protostars can be successfully traced at different scales by observing maser and dust polarised emission. A confirmation that they are effective tools is indeed provided by our recent results from 6.7 GHz MERLIN observations of the massive protostar IRAS 18089-1732, where we find that the small-scale magnetic field probed by methanol masers is consistent with the large-scale magnetic field probed by dust (Dall’Olio et al. 2017 A&A 607, A111). Moreover we present results obtained from our ALMA Band 7 polarisation observations of G9.62+0.20, which is a massive star-forming region with a sequence of cores at different evolutionary stages (Dall’Olio et al. submitted to A&A). In this region we resolve several protostellar cores embedded in a bright and dusty filamentary structure. The magnetic field morphology and strength in different cores is related to the evolutionary sequence of the star formation process which is occurring across the filament.

Effects of free-stream turbulence on the global pressure fluctuation of compressible transitional flows in a low-pressure turbine cascade

PurposeThis paper aims to investigate global pressure fluctuations in compressible transitional flows in a low-pressure turbine cascade because of variations in the free-stream turbulence and its interaction with the boundary layers.Design/methodology/approachTransition process resolving numerical simulations are performed with different types of inflow turbulence. The unsteady three-dimensional fully compressible Navier–Stokes equations are solved using a sixth-order compact difference and a tenth-order filtering method. First, simulations of both K-regime and bypass transitions are conducted for a flat plate boundary layer to validate the use of the filter in computing different transition routes. Second, computations of the cascade flows are conducted. Cases of no free-stream turbulence, isotropic free-stream turbulence of 5 per cent and wakes from an upstream cylinder are compared. For wakes, variations in wake trajectory depending on the cylinder blade relative position are also taken into account.FindingsThe different transition routes are successfully reproduced by the present method even with strong filtering. When feedback phenomena occur near the trailing edge, high-frequency oscillations dominate in the flow field. Low-frequency oscillations become dominant when the blade boundary layer becomes turbulent. Thus, the effects of the free-stream turbulence and its interaction with the boundary layer appear as changes in the global pressure fluctuation.Originality/valueThe free-stream turbulence qualitatively affects global pressure fluctuations, which become a medium to convey boundary-layer information away from the cascade.

Are Bitcoin Bubbles Predictable? Combining a Generalized Metcalfe's Law and the LPPLS Model

We develop a strong diagnostic for bubbles and crashes in bitcoin, by analyzing the coincidence (and its absence) of fundamental and technical indicators. Using a generalized Metcalfe’s law based on network properties, a fundamental value is quantified and shown to be heavily exceeded, on at least four occasions, by bubbles that grow and burst. In these bubbles, we detect a universal super-exponential unsustainable growth. We model this universal pattern with the Log-Periodic Power Law Singularity (LPPLS) model, which parsimoniously captures diverse positive feedback phenomena, such as herding and imitation. The LPPLS model is shown to provide an ex-ante warning of market instabilities, quantifying a high crash hazard and probabilistic bracket of the crash time consistent with the actual corrections; although, as always, the precise time and trigger (which straw breaks the camel’s back) being exogenous and unpredictable. Looking forward, our analysis identifies a substantial but not unprecedented overvaluation in the price of bitcoin, suggesting many months of volatile sideways bitcoin prices ahead (from the time of writing, March 2018).

De-Correlated Improved Adaptive Exponential FLAF-Based Nonlinear Adaptive Feedback Cancellation for Hearing Aids

Modern-day digital hearing aids are prone to an unavoidable acoustic feedback phenomenon, degrading sound quality and speech intelligibility. The linear adaptive feedback cancellation (AFC) systems based on finite-impulse-response filters do not yield satisfactory performance under nonlinearity encountered in the feedback path. In an endeavor to overcome this, a de-correlated improved adaptive exponential functional link adaptive filter (DI-AEF)-based nonlinear AFC (NAFC) system is developed in this paper. It utilizes cross terms of the input samples and trigonometrical expansion with exponentially varying amplitude. To save computations, the delayed outputs of the feedback canceler are appended at the input layer, inspired by the IIR filtering technique. The adaptive de-correlation filter is updated by variable convergence and forgetting factor windowed recursive least square algorithm to address the biased estimation problem. The corresponding update rules, convergence, and bounded-input bounded-output stability conditions have been derived. Extensive simulation results demonstrate the efficacy of the proposed NAFC system for real input signals in terms of perceptual evaluation of speech and audio quality and added stable gain (ASG). The DI-AEF-based system achieves nearly 4-dB improvement in ASG while consuming 53% and 37% less multiplications and additions than the existing nonlinear methods.