Zeal Press
Not a member yet
427 research outputs found
Sort by
Comparative Characteristics of Hemp Nanocellulose Extracted by Different Methods
Get PDFAbstract: The study describes the extraction of nanocellulose from organosolv hemp pulp (OHP) by different methods: acid hydrolysis, oxidation in the medium of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) and in deep eutectic solvent (DES). OHP was obtained from renewable plant material - hemp fibers by extraction with NaOH solution and cooking using a mixture of acetic acid and hydrogen peroxide. SEM and FTIR data confirmed the reduction of cellulosic fibers and the removal of non-cellulosic components from hemp samples during their sequential thermochemical treatment. The data of X-ray structural and thermogravimetric analyzes confirmed that with increasing crystallinity index and resistance of cellulose-containing hemp samples to the influence of temperature, the obtained nanocelluloses are arranged in the following order: OHP – NCD – NCT – NCH. The values of physical and mechanical parameters of hemp nanocelluloses obtained by different methods are compared. It was established that with approximately the same values of the transverse size of hemp nanoparticles, nanocellulose obtained in the process of acid hydrolysis (NСH) has higher values of physical and mechanical parameters than nanocellulose obtained in TEMPO-medium (NCT) and in the DES (NCD)
About Wave Nature of the Formation of Gradient and Microcomposite Zones Near Non-Metallic Inclusions During Laser Processing of the Steels
Get PDFAbstract: The goal of this investigation was to research the wave nature of the formation of gradient and composite zones near non-metallic inclusions during laser treatment of the steels. The materials for investigation were commercial steels containing different non-metallic inclusions. The specimens of different steels were exposed to laser beaming on the installations GOS-30M. The research methods were applied: petrography, X-ray microscopy (MS-46 Cameca, "Nanolab - 7") and optical microscopy (Neophot-31) to study steel matrix near non-metallic inclusions and to identify of the inclusions. Nanohardness of the steel matrix near inclusions ("Nano Indenter II") was analyzed. Peculiarities of wave saturation of the steel matrix by chemical elements of non-metallic inclusions during laser action were investigated. It was shown the role of wave relaxation of stresses in the formation of cascade type structure of steel matrix near non-metallic inclusions. The features of the formation of gradient and micro composite saturation zones of cascade type in a steel matrix under conditions of abnormal mass transfer from nonmetallic inclusions during laser processing are discussed. It has been established that the formation of gradient saturation zones with a cascade and “spot” distribution of elements and nanohardness is due to the wave nature of the relaxation of thermal and deformation stresses near non-metallic inclusions at the time of laser exposure. The difference in the rates of abnormal mass transfer of chemical elements of non-metallic inclusions into a steel matrix at the moment of laser melting is shown, which is associated with different solubility and mobility of the atoms of alloying elements in liquid iron
Optimization with a Genetic Algorithm for Multilayer Electromagnetic Wave Absorption Cement Mortar Filled with Expended Perlite
Get PDFAbstract: Due to the complexity of the design of multilayer electromagnetic (EM) wave absorbing materials, it is difficult to establish the relationship between material parameters (type and filling ratios) and EM properties using traditional trial and error methods. Based on the measured EM parameters within a few materials and Boltzmann mixing theory, a database of EM parameters was thereafter built up. In this study, the genetic algorithm (GA) was used to design the multilayer wave-absorbing cement mortar. In order to verify this method, a multilayer mortar was fabricated and measured. The simulated and measured results are well consistent, which convincingly verifies computer-aided design. In addition, the optimized result expresses that the first layer as a matching layer guides EM waves into the interior of the material, while the other layers as absorption layers attenuate EM waves. The multilayer material may not meet the impedance gradient principle but still exhibits better EM wave absorption performance. The reflection loss (RL) of all optimized three layer sample is below –6.89 dB in the full frequency band and the minimum RL is –26.21 dB. This composite absorbing material and the GA method provide more design ideas for the design of future cement-based wave-absorbing materials and save a lot of time and material cost
Crystal Structure and Magnetic Properties of Bi1-yBa(Sr)Fe1-yTiyO3 Solid Solutions
Get PDFAbstract: Usages of various chemical substitution schemes of the initial multiferroic BiFeO3 can significantly reduce known drawbacks specific for the functional oxides based of iron ions and thus foster a creation of novel magnetoelectric compounds perspective for various technological applications. In the present study the co-doped compounds of the system Bi1-y(Ba1- xSrx)yFe1-yTiyO3 (x = 0.0 – 1.0; y ≤ 0.4) synthesized using sol-gel technique were analyzed focusing on the crystal structure stability and the correlation between the structure and magnetic properties. The concentration driven evolution of the crystal structure as well as the unit cell parameters were investigated based on the X-ray diffraction data, the correlation between the crystal structure and the magnetic properties of the compounds has been studied by magnetometry techniques. The compounds Bi1-y(Ba1- xSrx)yFe1-yTiyO3 with x = 0; y = ≤ 0.2 are characterized by single-phase rhombohedral structure, and increase in the dopant concentration to y = 0.4 leads to the stabilization of the pseudocubic phase. An increase in the Sr content leads to the phase transition in the compounds to the single phase state with the cubic structure which is accompanied by an increase in the value of the remanent magnetization
Data-Driven and Model-Based Control Techniques for a Wind Turbine Benchmark Model
Get PDFAbstract: Wind turbine plants are complex dynamic and uncertain processes driven by stochastic inputs and disturbances, as well as different loads represented by gyroscopic, centrifugal, and gravitational forces. Moreover, as their aerodynamic models are nonlinear, both modelling and control become challenging problems. On one hand, high–fidelity simulators should contain different parameters and variables in order to accurately describe the main dynamic system behaviour. Therefore, the development of modelling and control for wind turbine systems should consider these complexity aspects. On the other hand, these control solutions have to include the main wind turbine dynamic characteristics without becoming too complicated. The main point of this paper is thus to provide two practical examples of development of robust control strategies when applied to a simulated wind turbine plant. Extended simulations with the wind turbine benchhmark model and the Monte–Carlo tool represent the instruments for assessing the robustness and reliability aspects of the developed control methodologies when the model–reality mismatch and measurement errors are also considered. Advantages and drawbacks of these regulation methods are also highlighted with respect to different control strategies via proper performance metrics
Design and Implementation of a Traffic Control System Based on Congestion
Get PDFAbstract: The traffic issues have garnered more and more attention on a global scale as the number of cars has grown. One of the biggest problems is the traffic congestion, also the fixed-time settings are still used by the majority of traffic systems today. These technologies are unable to dynamically alter the timing of traffic lights in response to heavy traffic. Thanks to technological advancements, sensors or cameras can now collect data on traffic volume and wait times. This study provided an illustration of a traffic light control system that can manage traffic according to the number of vehicles in each road. Additionally, it showed how the system was designed using the Proteus design suite software and how a prototype of the system was implemented using an Arduino Mega 2560 and an infrared sensor. Through the results obtained, the efficiency of the proposed system is clear by comparing it with the system that depends on the fixed time of traffic signals
Finite Horizon Memory Control of Networked Systems Using Chain-like Lyapunov Function
Get PDFAbstract: This paper proposes a novel finite horizon memory control (FHMC) design framework for networked systems by using input delay approach. A chain-like input delay model is established to characterize the networked control system (NCS) under memory control architecture in order to make full use of historic sampled-data. Based on the proposed chain-like delay model, the corresponding chain-like Lyapunov-Krasovskii function, which records the historic sampling information of NCS, is well constructed for facilitating further analysis and synthesis of the proposed FHMC scheme. Both state feedback controllers and static output feedback controllers are derived by solving LMIs (Linear matrix inequalities). The proposed FHMC scheme is skilled in improving control performance of networked systems. Simulations show the effectiveness of the presented FHMC scheme
Exploring the Potential of Chicken Feather-Reinforced Thermoplastic Polyurethane Composites for Sustainable Materials
Get PDFThis study explores the viability of chicken feather-reinforced thermoplastic polyurethane (TPU) composites as environmentally sustainable materials. Chicken feathers, an abundant keratin-rich biowaste generated by the poultry industry, were processed into both powder and fiber forms and subsequently subjected to chemical modification using (3-aminopropyl) triethoxysilane to enhance interfacial compatibility with the TPU matrix. Four composite formulations were produced via melt compounding, incorporating TPU-to-feather weight ratios of 90:10 and 85:15 for each morphological variant. Standardized test specimens were fabricated and evaluated through tensile, compressive, hardness, and density analyses. Among the formulations, the composite containing 85% TPU and 15% feather fiber exhibited the most favorable mechanical properties. The improved interfacial adhesion was attributed to the dual functional role of the silane coupling agent, which facilitated both covalent and hydrogen bonding at the filler–matrix interface. The findings underscore the potential of chemically treated feather waste as an effective and economical reinforcement for polymeric materials, advancing the development of high-performance, sustainable composites
Structural, Morphological and Optical Study of Manganese Doped FeS (Mackinawite) Nanostructures by Chemical Bath Deposition (CBD) Technique
Get PDFAbstract: Fe1-xMnxS thin films with concentration x=0.02, 0.04, 0.06, 0.08, 0.1 have been deposited on glass substrates by a simple Chemical Bath Deposition (CBD) method at 90 oC. The X-ray Diffraction analysis of deposited thin films revealed the growth of mono-phasic mackinawite (FeS) structure with crystallite size in the range from 4.06 to 5.95 nm as a function of manganese concentrations. The other structural parameters like stacking faults, dislocation density and lattice strain affirmed the improvement in crystal structure and phase stability in manganese doped FeS thin films. Scanning Electron Micrographs depicted the growth of nano-flakes and nano-flowers in case of pure FeS thin films while for manganese doped iron sulfide thin films, homogeneity of the deposited material was observed to improve with distinct boundaries of almost spherical nanostructures. The direct energy band gap of FeS mono-phasic thin films was observed to decrease from 2.23 to 1.89 eV as the concentration of manganese increases in host lattice. The prepared thin films with tunable optical properties would have potential applications in energy conversion and optoelectronic devices
Advanced Control Subsystem for Mobile Robotic Systems in Precision Agriculture
Get PDFAbstract: This concept paper presents Mobile Agricultural Robots (MARs) for the development of precision agriculture and implicitly the smart farms through knowledge, reason, technology, interaction, learning and validation. Finding new strategies and control algorithms for MARs has led to the design of an Autonomous Robotic Platform Weed Control (ARoPWeC). The paradigm of this concept is based on the integration of intelligent agricultural subsystems into mobile robotic platforms. For maintenance activities in case of hoeing crops (corn, potatoes, vegetables, vineyards), ARoPWeC benefits from the automatic guidance subsystem and spectral analysis subsystem for differentiation and classification of the weeds. The elimination of weeds and pests is done through the Drop-on-Demand spray subsystem with multi-objective control, and for increasing efficiency through the Deep Learning subsystem