Analysis of Students’ English-Speaking Ability through Media of Learning Video

This study aims to describe the ability of students’ fifth semester of English STAIN Mandailing Natal to speak English through learning video media in the Instructional Media for ELT (English Language Teaching) course. This research is descriptive qualitative research in which the writer describes and analyzes students' speaking abilities. The population in this study were 10 students from the fifth semester of the English Department at STAIN Mandailing Natal for the academic year of 2022-2023. Based on the results of the study it can be concluded that students' speaking abilities are between the "above average" and "excellent" levels. In other words, it can be concluded that learning videos can be an interesting alternative media that students can use to improve students' speaking abilit

Robust control of longitudinal flight with handling qualities constraints

Classical flight control systems are still widely used in industry because of acquired experience and good understanding of their structure. Nevertheless, with more stringent constraints, it becomes difficult to easily fulfill all the criteria with this classical control laws. This article aims at showing that this problem can be solved by first designing a high order controller satisfying all the constraints, then by reducing and structuring it in order to make it look like a classical controller. Firstly, an H∞ synthesis is performed in order to get a robust controller versus mass and center of gravity variations, which will satisfy the handling qualities; then it will be reduced by using robust modal control techniques

Robust scheduled control of longitudinal flight with handling quality satisfaction

Classic flight control systems are still widely used in the industry because of acquired experience and good understanding of their structure. Nevertheless, with more stringent constraints, it becomes difficult to easily fulfil all the criteria with these classic control laws. On the other hand, modern methods can handle many constraints but fail to produce low order controllers. The following methodology proposed in this paper addresses both classic and modern flight control issues, to offer a solution that leverages the strengths of both approaches. First, an H∞ synthesis is performed in order to get controllers which satisfy handling qualities and are robust withrespect to mass and centre of gravity variations. These controllers are then reduced and structured by using robust modal control techniques. In conclusion, a self-scheduling technique is described that will schedule these controllers over the entire flight envelope

Longitudinal flight control design with handling quality requirements

This work presents a method for selecting the gain parameters of a C* control law for an aircraft’s longitudinal motion. The design incorporates various handling quality requirements involving modal, time- and frequency-domain criteria that were fixed by the aircraft manufacturer. After necessary model order- reductions, the design proceeds in essentially two-step s: Stability Augmentation System (SAS) loop design and Control Augmentation System (CAS) loop design. The approach partly relies on the use of guardian maps to characterize, in each case, the set of gain parameters for which desired handling quality requirements are satisfied. The approach is applied throughout the full flight envelope of a business jet aircraft and yields satisfactory results

Polymer nanocomposites from natural clay: Understanding clay-PEG interaction and their effect on spacing between clay-plates

International audienceThe interactions between clay-plates and hydrophilic polymer are investigated assuming that the polyethylene glycol chains are grafted onto face-to-face clay-plates. Besides the usual van der Waals attractive interaction, the clay-plates experience a repulsive effective interaction, due to the excluded volume force between monomers along the grafted PEG chains. The face-to-face clay-plates then play the role of polymer brushes. The free energy (per unit area) of a clay-plate pair is the sum of these interactions, and from its expression, we determine the minimal inter-sheet distance, after intercalation, which corresponds to a critical percentage of PEG. Finally, our results are found to be in good agreement with some recent experimental work

dSPACE Implementation for a Fuzzy Logic Voltage Control using a Self-Excited Induction Generator and a Voltage Source Inverter

The present work describes the analysis  of a control scheme for keeping  the  RMS voltage output  constant, the system is  supplying  by a self-excited induction generator with variable speed and load. A comparison is examined between simulation and experimental results using dSPACE board. the results are provided to verify the effectiveness of this approach and gives very high performance

The Multivariate Regression Models Suggested as Standardising Tools for Categorising Solitarious and Gregarious Groups of the Main Pest Locust, Schistocerca gregaria, Produce Reproducible Results

Outbreaks of the desert locust Schistocerca gregaria affect some of the poorest parts of Africa, with devastating outcomes. The key to understanding and dealing with this problematic adaptation to environmental changes is comparing gregarious and solitarious locusts, either in nature or in laboratories. Categorising locusts and detecting changes in their phase status is key to such comparisons, which have been hitherto based on applying mathematical models that use behavioural parameters and that each laboratory has to build anew for each experiment. All the models used thus far are different from one another. This implies differences in the tools used for the different experiments and by the different laboratories and, thus, potential noise in the results and interpretations. Standardising the way locusts are categorised is necessary if we want to reduce noise and errors. It is crucial if we seek to make the results and interpretations transferable and comparable between experiments and laboratories for such an important research area. To tackle this problem, we suggested two models as possible standardising tools. However, the problem of a lack of standardised tools re-emerged due to the doubts cast on the validity of those models. Here, we use samples from independent S. gregaria populations in order to test and validate those models. We discuss how successful the two models were at categorising solitarious, intermediate (transient), and gregarious nymph and adult S. gregaria samples. We highlight shortcomings and make more specific recommendations on the use of those models based on the precision differences they show when categorising solitarious and gregarious S. gregaria nymph and adult samples. Overall, both models have proven to be valid since their results were largely replicated and seem reproducible.Agencia Estatal de Investigación, Ministerio de Ciencia e Innovación, Spain, grant number PGC2018.097678.B.I00ERASMUS+ International Dimension Programme at the University of Granad

Crossflow microfiltration of fungal fermentation broths to obtain natural extracts

Motivation: One of the main milestones after developing a laboratory scale product is to transform the acquired knowledge into an economic production structure. The production of natural extracts in BioflowSur is carried out by using a fermentation process; then, natural extracts are separated from the fungus by vacuum filtration. However, this type of filtration is not feasible with large volumes so that the use of tangential microfiltration with membrane technology was studied.Methods: The fungal fermentation broth was filtrated using a bench-scale crossflow filtration unit (Prozesstechnik GmbH) equipped with a ceramic membrane either of 0,2 μm pore diameter (with active layer) or 5-8 μm pore diameter (without active layer). Two modes of operation were used: concentration and diafiltration. In the first mode the product concentrates in small volumes and in the second mode water is added to facilitate the filtration [1].Results: The diafiltration was discarded as mode of operation after the first test due to the generation of large volumes that complicate the subsequent extraction of the active principle. In addition, results reveal that the optimal temperature is 30ºC because higher temperatures facilitate the passage of residues to the permeate.The concentration tests performed with the membrane of 0.2 μm showed that there was active principle in the concentrate and in the permeate, while the membrane of 5-8 μm allowed fungus to pass to the permeate after several rounds of filtration. In addition, the high pressures generated due to the fouling drastically reduced the flow and, hence, increased the time of the process [2]

Gain scheduling with guardian maps for longitudinal flight control

A new approach to gain scheduling of linear controllers is proposed and applied to a longitudinal flight control pro-blem. Traditionally, gain scheduling is done a posteriori by the interpolation of controller gains designed for several operating points or conditions. The method proposed here is based on guardian maps and does not require as many linear controller syntheses as there are design points. Rather, it extends the performance of an initial single controller carried out on an arbitrary operating point to the entire domain while ensuring generalized stability all along the process. The method, which uses a given fixed architecture controller, is successfully applied on the longitudinal flight control of a business jet aircraft

Experimental feedback linearisation of a vibrating system with a non-smooth nonlinearity

Input-output partial feedback linearisation is demonstrated experimentally for the first time on a system with non-smooth nonlinearity, a laboratory three degrees of freedom lumped mass system with a piecewise-linear spring. The output degree of freedom is located away from the nonlinearity so that the partial feedback linearisation possesses nonlinear internal dynamics. The dynamic behaviour of the linearised part is specified by eigenvalue assignment and an investigation of the zero dynamics is carried out to confirm stability of the overall system. A tuned numerical model is developed for use in the controller and to produce numerical outputs for comparison with experimental closedloop results. A new limitation of the feedback linearisation method is discovered in the case of lumped mass systems e that the input and output must share the same degrees of freedom