Explore the vast range of titles available.

De Bruijn sequence is an important kind of nonlinear shift register sequence, which has a very wide range of applications in the fields of communication and cryptography. From the perspective of the relationship between linear terms, quadratic terms and cubic terms in the feedback functions of de Bruijn sequences, some new necessary conditions for feedback functions of de Bruijn sequences are obtained. Some examples show that the known necessary conditions cannot deduce the proposed necessary conditions.

The objectives of this study were to examine the EFL supervisors’ written feedback focus, and language functions at selected public universities in Ethiopia. To address the objectives of the study, qualitative and quantitative approaches with concurrent mixed methods design was adopted. 55 supervisees were randomly selected out of 205 for the questionnaire survey. Besides, four supervisors were selected for interviews. Moreover, feedback comments on five theses drafts were utilized as data sources. To decide the language functions and feedback foci, frequency counts and percentages were used. Nonetheless, content analysis was used to analyze the interview data. The results showed that thesis supervisors used the directive feedback language function most prevailingly over the expressive function. Besides, the result indicated there was no balance of praise, criticism, and suggestions in the provision of feedback comments. The supervisors largely focused on content knowledge, followed by genre knowledge, and then linguistic accuracy and appropriateness (forms), respectively. Based on the results, supervisors were recommended to write their feedback comments in helpful and constructive ways based on the needs and preferences of their supervisees for the development of writing skills.

We propose a novel transient chaotic neural network model with a nonlinear delayed self-feedback term, aiming to leverage its complex dynamical behavior for algorithm optimization. To avoid the influence of chance, we conduct experiments using randomly generated data and analyze the model’s chaotic dynamical behavior by visualizing the stability of the neurons through inverse bifurcation diagrams and maximum Lyapunov exponent diagrams. The simulation results demonstrate the remarkable effectiveness of this new model in network optimization, with a success rate even reaching 100%, surpassing previous chaotic neural network models. Notably, in the following sections, all nonlinear terms are represented using trigonometric functions.

Feedback is essential in the design and development process, occurring in the generation of new designs, in the adaptation of development projects to emerging information, and in coordination and collaboration of project participants—among many other aspects. Feedback also contributes to development project complexity and may cause resistance to desirable changes. But despite the importance of feedback in the design and development process (DDP), relatively few publications have examined this topic in an integrated way. This article makes two contributions towards addressing the gap. First, a conceptual framework is developed to organise perspectives on feedback in the DDP literature. The framework shows how feedback occurs at different levels of the design and development process and how it affects important DDP behaviours, namely goal-seeking, learning and emergence. Second, a system-theoretic model of feedback situations in the design and development process is introduced to synthesise key ideas. We provide concrete examples to show how this new model can be used to frame DDP situations and draw out feedback-related insight.

This study considers the formation control of differential-drive mobile robots subject to diamond-shaped input constraints. A basic controller form in terms of two feedback functions is proposed in a leader-follower setup. The existence of suitable feedback functions, guaranteeing the achievement of desired formation and the satisfaction of input constraints, is confirmed by a sufficient condition derived from geometric analysis. The geometric analysis also helps selections of feedback functions. Optimal feedback functions are designed to fully exploit the maneuverability of mobile robots. In addition, the performance assignment, which confines the velocities of the follower robot in a specified subset of diamond-shaped input domain to avoid slippage and reduce mechanical wear, is discussed. Simulation results are included to verify the effectiveness of the proposed controllers.

Species that shelter in a biogenic habitat can influence their refugia and, in turn, play an essential role in shaping local patterns of biodiversity. Here we explore a positive feedback loop between the provisioning rate of habitat-forming branching corals and their associated fishes and show how interactions between two groups of fish—the planktivorous damselfish and predatory hawkfish—altered the feedback. A field experiment confirmed that skeletal growth of branching coral (genus Pocillopora) increased substantially with increasing numbers (biomass) of resident fishes, likely because they greatly increased the interstitial concentrations of nutrients. Because there is a positive relationship between colony size and number (biomass) of associated fishes (primarily damselfishes in the Family Pomacentridae), a structure-function feedback loop exists in which increasing numbers of damselfish enhance coral growth and larger corals host greater abundances (and species richness) of fish. However, interactions between damselfishes and arc-eye hawkfish, Paracirrhites arcatus, a largely solitary resident, can disrupt this positive feedback loop. Field surveys revealed a marked pattern of fish occupancy related to coral size: Pocillopora colonies of sufficient size to host fish (> 40 cm circumference) had either groups of damselfish or an arc-eye hawkfish; only larger colonies (> 75 cm) were occupied by both the damselfish and hawkfish. Subsequent short-and long-term experiments revealed that on intermediate-sized Pocillopora colonies, arc-eye hawkfish prevented the establishment of damselfish by suppressing their recruitment. The demographic consequences to the host coral were substantial; in a 1-year-long experiment, intermediate-size Pocillopora occupied by hawkfish grew at half the rate of corals that hosted groups of damselfish. These findings indicate that: (1) species which occupy a biogenic habitat can enhance the provisioning rate of their habitat; (2) such positive feedbacks between community structure and ecosystem function can be disrupted by a strong interactor; (3) even substantial consequences on ecosystem processes that arise can be difficult to discern.

In this paper, a four-dimensional (4D) autonomous hyperchaotic system is dealt with. The stability criteria of equilibria of the controlled hyperchaotic chaotic system are established. Using the dislocated feedback control, enhancing feedback control, and nonlinear function feedback control methods, the chaos of the 4D hyperchaotic system can be suppressed to unstable equilibrium. Some numerical simulations revealing the effectiveness of our control strategies are given..

Small spacecraft requires capable processors with energy efficiency, low cost and low computational burden while maintaining the output tracking accuracy. This paper presents the extension of work in [1], to enhance the transient performance using particle swarm optimization (PSO) on decaying boundary layer and switching function thorough error feedback (DBLSF) in Sliding Mode Control (SMC). Generally, SMC is known for having chattering as the main drawback which can introduce wear and tear to moving mechanical parts. As a solution, a DBLSF proposed in [1] and capable of eliminating the chattering in SMC while considering the essential requirements for small spacecraft operation. Then, the extension implemented on spacecraft's attitude, which is one-of-six subsystems in spacecraft, used to orient the spacecraft referred to reference objects and control the dynamics of a spacecraft time-to-time according to the needs. However, the SMC's transient response can be tuned using some coefficients in the SMC algorithm. The parameters in [1] were tuned using outputs observation technique. In this paper, then, an improvement is introduced to optimize the outputs by adding a PSO in the SMC-DBLSF in term of transient performances and accuracy while reducing the chattering permanently.

Four pigeons were trained on two‐key concurrent variable‐interval schedules with no changeover delay. In Phase 1, relative reinforcers on the two alternatives were varied over five conditions from .1 to .9. In Phases 2 and 3, we instituted a molar feedback function between relative choice in an interreinforcer interval and the probability of reinforcers on the two keys ending the next interreinforcer interval. The feedback function was linear, and was negatively sloped so that more extreme choice in an interreinforcer interval made it more likely that a reinforcer would be available on the other key at the end of the next interval. The slope of the feedback function was −1 in Phase 2 and −3 in Phase 3. We varied relative reinforcers in each of these phases by changing the intercept of the feedback function. Little effect of the feedback functions was discernible at the local (interreinforcer interval) level, but choice measured at an extended level across sessions was strongly and significantly decreased by increasing the negative slope of the feedback function.

Dynamical models based on three steady‐state equations for the law of effect were constructed under the assumption that behavior changes in proportion to the difference between current behavior and the equilibrium implied by current reinforcer rates. A comparison of dynamical models showed that a model based on Navakatikyan's (2007) two‐component functions law‐of‐effect equations performed better than models based on Herrnstein's (1970) and Davison and Hunter's (1976) equations. Navakatikyan's model successfully described the behavioral dynamics in schedules with negative‐slope feedback functions, concurrent variable‐ratio schedules, Vaughan's (1981) melioration experiment, and experiments that arranged equal, and constant‐ratio unequal, local reinforcer rates.