Design of Fuzzy Optimized Controller for Satellite Attitude Control by Two State actuator to reduce Limit Cycle based on Takagi-Sugeno Method

In this paper, an algorithm was presented to control the satellite attitude in orbit in order to reduce the fuel consumption and increase longevity of satellite. Because of proper operation and simplicity, fuzzy controller was used to save fuel and analyze the uncertainty and nonlinearities of satellite control system. The presented control algorithm has a high level of reliability facing unwanted disturbances considering the satellite limitations. The controller was designed based on Takagi-Sugeno satellite dynamic model, a powerful tool for modeling nonlinear systems. Inherent chattering related to on-off controller produces limit cycles with low frequency amplitude. This increases the system error and maximizes the satellite fuel consumption. Particle Swarm Optimization (PSO) algorithm was used to minimize the system error. The satellite simulation results show the high performance of fuzzy on-off controller with the presented algorithm.DOI:http://dx.doi.org/10.11591/ijece.v4i3.583

The dual role of Haemonchus contortus ABC transporters in macrocyclic lactone resistance and their extrusion activity on the parasite's lipidomics

La résistance aux lactones macrocycliques (LM) constitue une préoccupation croissante dans le contrôle des nématodes parasitaires, notamment l'Haemonchus contortus chez les ruminants. Parmi les mécanismes étudiés dans la résistance aux LM chez les nématodes d’importance en santé animale, il y a les pompes ABC, principalement les glycoprotéines-p, connues pour leur rôle dans la détoxification des LM chez les strongles. Il n'existe toutefois aucune étude sur l'extrusion des lipides par les pompes ABC en tant que produits excrétoires/sécrétoires provenant d'H. contortus (Hc-PES). Nous émettons l’hypothèse que les pompes ABC chez H. contortus sont à la fois impliquées dans l’extrusion de LM (contribuant à la résistance aux antihelminthiques) et dans l’efflux de lipides secrétés par le parasite. Notre objectif était de caractériser le rôle des pompes ABC chez H. contortus dans le contexte de la résistance aux LM et de l'extrusion des lipides. L'efficacité de l'ivermectine, un membre de LM, a été évaluée dans 8 fermes étudiées par un test de réduction de la numération des œufs dans les selles (TRNOS). Les niveaux d'expression des pompes ABC ont été évalués dans des isolats de champ d’H. contortus avec des résultats TRNOS faibles (présumé souches résistantes). D’ailleurs, des vers adultes d’H. contortus ont été incubés avec trois inhibiteurs de pompes ABC, dont le Fumitremorgin C, le Kétoconazole et le Mk-571 à concentrations différentes. Les lipides ont été identifiés par CL/SM dans les milieux de culture récupérés à 2 h, à 4 h et à 8 h après l'incubation d’H. contortus dans les groupes contrôle et traités. L'expression des gènes Hco-pgp-2 et Hco-pgp-3 était augmentée chez les isolats de champ d’H. contortus. Nous avons identifié 1045 lipides appartenant à diverses catégories. L'extrusion des lipides en Hc-PES a changé en présence d'inhibiteurs de pompes ABC, en particulier pour les lipides composés de structures correspondant à celles pour le transport par les pompes ABC. Nous avons donc conclu que les pompes ABC chez H. contortus représentent un système de multi-extrusion et sont impliquées dans la sécrétion de lipides avec importance dans l’interaction avec l’hôte, mais aussi dans la résistance aux LM chez le nématode.Macrocyclic lactones (MLs) resistance is a growing concern in controlling parasitic nematodes, particularly Haemonchus contortus in the ruminants’ industry. ABC transporters are known to participate in translocating various lipophilic molecules, including MLs and lipids. Some ABC transporters, mostly P-glycoproteins are known to be involved in MLs detoxification in parasitic nematodes; but there is no data about extrusion of lipids by ABC transporters as Excretory/Secretory Products in H. contortus (Hc-ESP). We hypothesize that ABC transporters in H. contortus have a dual role participating in the efflux of MLs, thus contributing to anthelmintic resistance, and in the extrusion of lipids out of the parasite. This study aimed to characterize the role of H. contortus ABC transporters in the context of ML resistance and the extrusion of lipids. Ivermectin (a member of MLs) efficacy was evaluated in 8 studied farms by the fecal egg count reduction test (FECRT). The expression levels of ABC transporters were evaluated in field isolates of H. contortus with low FECRT results (suspected of resistance). H. contortus adult worms were incubated with three ABC inhibitors, such as Fumitremorgin C, Ketoconazole and Mk-571 with different concentrations. Lipids were identified by LC/MS in culture media at 2h, 4h and 8h post incubation with H. contortus in control and treated groups. Hco-pgp-2 and Hco-pgp-3 were found upregulated in H. contortus field isolates. We identified 1045 lipid molecules belonging to different categories. Interestingly, the lipid profile in Hc-ESP was altered in the presence of ABC transporter inhibitors, which shows structural features compatible as substrates for nematode transporters’ activity. Therefore, ABC transporters in H. contortus participate in extrusion of lipids and also may help in detoxification of MLs, becoming a multipurpose pumping system involved in ML resistance and secretion of lipids at the interplay with the host and among nematodes

Academic Word List: Coverage Range in Local/Global Textbooks and Exploring Effective Ways of Teaching and Testing of AW

Coxhead’s (2000) AcademicWord List (AWL), consists of 570 word ‘families’, each including a headword (stem noun or verb forms) and other family members. This paper highlights the pedagogical value of the AWL, specifically applied in setting vocabulary goals for English for Academic Purposes (EAP) or English for Specific Purposes (ESP). What led the researchers to conduct this study was an aim to profile the presence of the AWL items in local (General English for Science and Engineering Students, 2010) and global (Active 4, 2008) EAP textbooks taught in Iran. The textbook corpus of these two books was analyzed using the concordance program which is a vocabulary analysis program. The chi-square value of 200.42 (P = .000 < .05) made it clear that a significant difference exists between the two books. The local textbook has used more words (Residual = 493.9) while the global book covered less AWL (Residual = -493.9). Our next purpose was to consider an aspect of this work that has been little researched: exploring some effective ways of teaching and testing of AWL in EAP textbooks to facilitate the pedagogical purposes. In conclusion, we found that the local book did much better than the global book in EFL context and we could come up with some suggestions on teaching and testing of AWL in textbooks. In addition, the results of this study would have important implications for textbook developers, material designers, EFL teachers and even EFL students to have a more cautious look at local books prepared in the context of their own country

Experimental Study of Fingering Flow in Porous Hele-Shaw Cells

With the aim of studying the physical process concerning the unstable fingering phenomena in two dimensions, experiments of vertical infiltration through layered sand were carried out in the laboratory using Hele-Shaw cells. We developed a light transmission method to measure the dynamics of water saturation within flow fingers in great detail with high spatial and temporal resolution. The method was calibrated using X-ray absorption. We improved the measured light transmission with correction for scattering effects through deconvolution with a point spread function which allows us to obtain quantitative high spatial resolution measurements. After fingers had fully developed, we added a dye tracer in order to distinguish mobile and immobile water fractions. Fully developed fingers consist of a tip, a core with mobile water, and a hull with immobile water. We analyzed the dynamics of water saturation within the finger tip, along the finger core behind the tip, and within the fringe of the fingers during radial growth. Our results confirm previous findings of saturation overshoot in the finger tips and revealed a saturation minimum behind the tip as a new feature. The finger development was characterized by a gradual increase in water content within the core of the finger behind this minimum and a gradual widening of the fingers to a quasi-stable state which evolves at time scales that are orders of magnitude longer than those of fingers' evolution. In this state, a sharp separation into a core with fast convective flow and a fringe with exceedingly slow flow was detected. All observed phenomena, with the exception of saturation overshoot, could be consistently explained based on the hysteretic behavior of the soil-water characteristic

Experimental study of fingered flow through initially dry sand

International audienceWater infiltration into coarse textured dry porous media becomes instable depending on flow conditions characterized through dimensionless quantities, i.e. the Bond number and the Capillary number. Instable infiltration fronts break into flow fingers which we investigate experimentally using Hele-Shaw cells. We further developed a light transmission method to measure the dynamics of water within flow fingers in great detail with high spatial and temporal resolution. The method was calibrated using x-ray absorption and the measured light transmission was corrected for scattering effects through deconvolution with a point spread function. Additionally we applied a dye tracer to visualize the velocity field within flow fingers. We analyzed the dynamics of water within the finger tips, along the finger core behind the tip, and within the fringe of the fingers during radial growth. Our results confirm previous findings of saturation overshoot in the finger tips and revealed a saturation minimum behind the tip as a new feature. The finger development was characterized by a gradual increase in water content within the core of the finger behind this minimum and a gradual widening of the fingers to a quasi-stable state which evolves on time scales that are orders of magnitudes longer than those of fingers' evolution. In this state, a sharp separation into a core with fast convective flow and a fringe with exceedingly slow flow was detected. All observed phenomena could by consistently explained based on the hysteretic behavior of the soil- water characteristic and on the positive pressure induced at the finger tip by the high flow velocity

Examining the Effect of Pore Size Distribution and Shape on Flow through Unsaturated Peat using Computer Tomography

The hydraulic conductivity of unsaturated peat soil is controlled by the air-filled porosity, pore size and geometric distribution as well as other physical properties of peat materials. This study investigates how the size and shape of pores affects the flow of water through peat soils. In this study we used X-ray Computed Tomography (CT), at 45μm resolution under 5 specific soil-water pressure head levels to provide 3-D, high-resolution images that were used to detect the inner pore structure of peat samples under a changing water regime. Pore structure and configuration were found to be irregular, which affected the rate of water transmission through peat soils. The 3-D analysis suggested that pore distribution is dominated by a single large pore-space. At low pressure head, this single large air-filled pore imparted a more effective flowpath compared to smaller pores. Smaller pores were disconnected and the flowpath was more tortuous than in the single large air-filled pore, and their contribution to flow was negligible when the single large pore was active. We quantify the pore structure of peat soil that affects the hydraulic conductivity in the unsaturated condition, and demonstrate the validity of our estimation of peat unsaturated hydraulic conductivity by making a comparison with a standard permeameter-based method. Estimates of unsaturated hydraulic conductivities were made for the purpose of testing the sensitivity of pore shape and geometry parameters on the hydraulic properties of peats and how to evaluate the structure of the peat and its affects on parameterization. We also studied the ability to quantify these factors for different soil moisture contents in order to define how the factors controlling the shape coefficient vary with changes in soil water pressure head. The relation between measured and estimated unsaturated hydraulic conductivity at various heads shows that rapid initial drainage, that changes the air-filled pore properties, creates a sharp decline in hydraulic conductivity. This is because the large pores readily lose water, the peat rapidly becomes less conductive and the flow path among pores, more tortuous

Influence of nano wollastonite on physical, mechanical and morphological properties of gypsum composites manufactured from bagasse

We investigated the effect of adding nano-wollastonite on the physical, mechanical and morphological properties of gypsum Composites. The ratio percentage of bagasse mixing as lignocellulosic material with gypsum at three levels (85:15; 75:25; 65:35) and nano-wollastonite at three levels of 0 %, 5 % and 10 %. Specimens were prepared according to the ISO 11925 specifications for the fire resistance (weight loss) properties and according to the DIN EN 634-1: 1195-04 specifications for the mechanical and physical properties. Scanning Electron Microscopy (SEM) were also used to study the properties of composite morphology and distribution of samples. The results showed that by increasing the amount of nano wollastonite, physical and mechanical properties improved. The MOR, MOE and IB of boards decreased with increased bagasse usage amount, and its maximum value was obtained in using 15 % bagasse. The results also showed that increasing the amount of bagasse in boards caused a significant increase in the TS of the boards. The results from microscopic images showed that the optimal level of nano-wollastonite can fill the empty holes and create a uniform structure, thereby improving the properties of the boards

Tunnel MOS Heterostructure Field Effect Transistor for RF Switching Applications

GaN RF switches are widely used in today’s communication systems. With digital communications getting more and more popular nowadays, the need for improving the performance of involved RF switches is inevitable. Designing low ON-state resistance GaN switches are exceedingly important to improve the switch insertion loss, isolation and power loss. Moreover, considerations need to be taken into account to improve the switching speed of the involved GaN HEMTs. In this dissertation, a new GaN HEMT structure called “Tunnel MOS Heterostructure FET (TMOSHFET)” is introduced which has lower ON-state resistance and faster switching speed compared to conventional AlGaN/GaN HEMTs. In the switch ON process, the channel of this device is charged up by electron tunneling from a layer underneath the channel as opposed to typical AlGaN/GaN HEMTs in which electron injection from the source is charging up the channel. The tunneling nature of this process together with the shorter travel distance of electrons in TMOSHFET provide for a faster switching speed. In order to understand the tunneling mechanisms in TMOSHFET, the fabrication of AlGaN/GaN Schottky Barrier Diodes (SBDs) with various AlGaN thicknesses is demonstrated on Si (111) substrate. The impacts of SF6 dry etching on the trap density and trap state energy of AlGaN surface are investigated using the GP/w- w method. Various tunneling mechanisms at different biases are then characterized in samples and compared with each other. To improve the source and drain resistances in TMOSHFET, a model is generated to optimize the 2DEG density and electric field in AlGaN/GaN heterostructure based on Al mole fraction, AlGaN thickness and the thickness of SiN passivation layer and it is experimentally verified by non-contact Hall 2DEG density measurements. The spontaneous and piezoelectric polarizations together with strain relaxation have been implemented into the model, taking into account the annealing effects. From the experimental data on obtained parameters, the operation and device parameterization of the TMOSHFET is outlined and design considerations to improve the device R_(ON)-V_(BR) figure of merit are discussed