AIJR Journals
Not a member yet
475 research outputs found
Sort by
Design and Performance Evaluation of Modular Compliant Mechanisms
Get PDFIn this study, modular design for compliant stage using a parallelogram flexure module is proposed. The material of the proposed stages chosen is Aluminium alloy T6-6051 due to excellent phase stability, low internal stresses, low density etc. The stage is driven by a linear electromagnetic actuator i.e. voice coil actuator. The preliminary static structural analysis is used to determine the range of motion, stiffness by considering stress limitations. FEA results show a maximum range of motion up to 30mm without exceeding stress limit of 275 Mpa. The proposed mechanisms provide low stiffness in the degree of freedom directions and provide large stiffness in the degree of constraint direction.so it is adequately constrained. The stage provides high precision and repeatability with an increased range of motion, minimal parasitic motions (i.e.150 microns) and limited cross axes coupling
Biosorption of an Anionic Dye, Eosin Yellow onto Pineapple Peels: Isotherm and Thermodynamic Study
Get PDFEosin Yellow (EY), an anionic dye (acid dye) was adsorbed using an agricultural waste, pineapple peels (PP) as bio-sorbent in order to investigate its suitability as an alternative adsorbent, and to give insight into the mechanisms of binding. The study includes: equilibrium isotherms and thermodynamics studies. The adsorption isotherm and thermodynamics experiments were conducted using batch equilibrium techniques. The adsorption data were fitted into Langmuir, Freundlich and Temkin isotherm models; as a result, the data fitted well into the Langmuir model from which the adsorption capacity, qe was obtained as 11.76 mg/g. Experimental values of the thermodynamics parameters (ΔH, ΔS and ΔG) and separation factor (RL) in combination suggested that the adsorption process was endothermic, feasible, spontaneous, and had high degree of freedom. Combined results of the isotherms and thermodynamic study suggested a physisorption-chemisorption mechanism for the adsorption process. Therefore, the results of the study could provide useful information to evaluate the raw pineapple peel powder as a cheap source of adsorbent for the removal of EY from waste water
Solar Dynamical Processes I
Get PDFThe article gives a concise overview of solar dynamical processes and their impacts on the space weather. This article is based on the observational and theoretical developments made during last few decades. The article begins with a brief discussion of the Sun and the solar interior, from the core to the solar corona. We discuss the solar magnetic field and provide some basic understanding of the solar dynamo model. The solar dynamical processes, the transient as well as the gradual, are the manifestations of the Sun’s magnetic field. Magnetic reconnection, as well as submergence and emergence of magnetic flux tubes, plays an important role in the solar activities. This article tries to cover a range of dynamical processes, including sunspots, solar prominences and bright points. We also discussed various models of the dynamical processes along with their properties and effect on other activities occurring on the Sun.
Impacts of Sugarcane Farmland Expansion towards Food Security among Sugarcane-farming Households in Khon Kaen Province, Thailand
Get PDFThis study aimed to examine the impacts of sugarcane farmland expansion towards food security among the sugarcane-farming households in Khon Kaen Province, Thailand. A quantitative methodological approach was implemented in the study. The population of the study consisted of 3,332 sugarcane-farming households in Khon Kaen Province, who were associated with the Association of Sugarcane Farmers in the central-northeastern region during the production year of 2012/13. An interview schedule was implemented for data collection in order to collect data from the 357 sample households. Data was analyzed by the proportion of households who cultivated both sugarcane and rice. Four groups of sugarcane farming households were identified, including households where the proportion between sugarcane and rice plantation was 100:0, 75:25, 50:50, and 25:75. The research results indicated that the impact of expanding the cultivated area on the food security of farming households in Khon Kaen province could be seen at different levels, depending on the proportion of the area for cultivation of sugarcane to rice. The sugarcane-farming households with the proportion between sugarcane and rice plantation of 25:75 had the highest food security and the sugarcane-farming households with the proportion between sugarcane and rice plantation of 100:0 had the lowest food security. The study results suggested that the relevant agencies should support adequate food production in order to meet consumption requirements within the households. Promoting agricultural areas and resource management in farmland are considered to be necessary to enhance the food security of sugarcane farmers
Importance of Modeling and Simulation of Materials in Research
Get PDFAll researchers have experience with various complicated phenomena and processes in materials and have contact with understanding of different complex dynamical systems. Consequently, one has to predict and optimize the system under study and compare the output results to its experimental setup. The experimental setup is done to confirm and spread out information about the system; however still, many researchers are not familiar with the results arising from the experimental setup or fabrications processes. To obtain valid experimental results, it is necessary to pay carful attentions to the tools, devices and the applied techniques for measuring and observations detectors. This experimentations and fabrications process cover all area from forming and characterizations of nanostructures to macrostructures. In system characterizations, it is common to apply system modeling to predict and represent the system by a mathematical model that is accomplishable due to the relations between the inputs and outputs defined by formulas
Study of Combined Effect of Inclination and Partial Fins on Melting of Phase Change Material in A Rectangular Enclosure Using CFD
Get PDFThis study presents the combined effect of inclination and internal fins on melting rate of PCM in a rectangular enclosure (8.89cm×6.35cm). Rectangular enclosure has a hot wall with a temperature of 311K, a cold wall with a temperature of 301.3K and the other two walls are insulated. Gallium with very low prandtl number is taken as the PCM in this study. First, the individual effects of different inclinations (0⁰, 45⁰ and 90⁰) of the enclosure on melting rate of PCM are studied followed by the study of the effect of internal fins. Then we provide a combined environment of inclination and partial fins and obtain the results of liquid fraction, velocity contours and temperature distributions. Plots for liquid fraction and average temperatures with respect to time are also obtained. Finally, the results and plots of combined effect are compared with those of other conditions. From the comparison we conclude that combined effect of inclination and partial fins under constant normal gravity condition greatly enhances the heat transfer in PCM
Influence of Crack on Modal Parameters of Cantilever Beam Using Experimental Modal Analysis
Get PDFIn this paper, the dynamic behavior of a cantilever beam without and with crack is observed. An elastic Aluminum cantilever beams having surface crack at various crack positions are considered to analyze dynamically. Crack depth, crack length and crack location are the foremost parameters for describing the health condition of beam in terms of modal parameters such as natural frequency, mode shape and damping ratio. It is crucial to study the influence of crack depth and crack location on modal parameters of the beam for the decent performance and its safety. Crack or damage of structure causes a reduction in stiffness, an intrinsic reduction in resonant frequencies, variation of damping ratios and mode shapes. The broad examination of cantilever beam without crack and with crack has been done using Numerical analysis (Ansys18.0) and experimental modal analysis. To observe the exact higher modes of beam, discretize the beam into small elements. An experimental set up was established for cantilever beam having crack and it was excited by an impact hammer and finally the response was obtained using PCB accelerometer with the help sound and vibration toolkit of NI Lab-view. After obtaining the Frequency response functions (FRFs), the natural frequencies of beam are estimated using peak search method. The effectiveness of experimental modal analysis in terms of natural frequency is validated with numerical analysis results. This paper contains the study of free vibration analysis under the influence of crack at different points along the length of the beam
Periodic Solution and Stability Behavior for Nonlinear Oscillator Having a Cubic Nonlinearity Time-Delayed
Get PDFThe current paper investigates the dynamics of the dissipative system with a cubic nonlinear time-delayed of the type of the damping Duffing equation. A coupling between the method of the multiple scales and the homotopy perturbation has been utilized to study the complicated dynamic problem. Through this approach, a cubic nonlinear amplitude equation resulted in at the first-order of perturbation; meanwhile, a quintic equation appears at the second-order of perturbation. These equations are combined into one nonlinear quintic Landau equation. The polar form solution is used, and linearized stability configuration is applied to the nonlinear amplitude equation. Also, a second-order approximate solution is achieved. The numerical illustrations showed that the damping, delay coefficient, and time delay play dual roles in the stability behavior. In addition, the nonlinear coefficient plays a destabilizing influence
Mechanical Properties and Microstructure of Dissimilar Friction Stir Welding of Pure Aluminum to Low Carbon Steel
Get PDFThe purpose of this research is to use friction stir welding (FSW) to join dissimilar metals, annealed low carbon steel and A1050 pure aluminum. A butt joint with a similar sheet thickness of 1.9 mm was applied. The novelties of the research are relatively using high generated heat produced by a combination of low traverse speed and high rotational speed to perform the dissimilar joints and using a tool material (K107cold work tool steel) which has not been used in FSW with tool cooling. The present work studied the effect of FSW variables such as tilt angle, tool cooling, base metal location on mechanical properties. Tensile tests were used to evaluate the mechanical properties of the dissimilar joints. The microstructure specimens were examined using a scanning electron microscope (SEM). Sound dissimilar joints were successfully produced. The maximum joint efficiency obtained in this study is 51.7% of the aluminum tensile strength. The microstructure images showed that many steel fragments were sheared off from the steel surface by the tool action and scattered in the weld nugget, a continuous intermetallic compound (IMC) layer formed at the interface, the thickness of the IMC layer at the interface decreased in the thickness direction of the weld. FeAl3 IMC phase was only observed at the interface
Evaluating the Nasal Cytology in Acute Rhinosinusitis
Get PDFRhinitis has been found to have profound direct and indirect negative effects on business including costs attributed to loss of productivity and the amount of over the counter medications consumed. Several other studies have examined the immune system’s response in immunocompromised patients by using nasal cytology. This study focused on nasal cytology for a common illness such as acute rhinosinusitis (ARS), in otherwise healthy individuals. Most studies have used nasal cytology to analyze immunocompromised patients, however, this study considers otherwise healthy patients in order to better understand the basic immune response. This study aimed to examine the relationship between neutrophil frequencies found over the course of ARS and symptom severity experienced by subjects. Nasal smears were obtained from subjects at days five, nine, and fourteen of their ARS symptoms. A published symptom survey for ARS was given to participants to provide a qualifying score, signifying a high enough level of symptoms for this study. This survey monitored both emotional and physical symptoms throughout the fourteen-day illness period. Nasal smears were obtained on each visit and stained to observe the different cells present. Wilcoxon Sum Rank Tests were found to be significant between all symptom score visits 1,2, and 3 (p<0.05). The average neutrophil counts between all the visits were not significant (p>0.05). Less than ten percent of eosinophils were present in 88.89 percent of subjects. 55.5 percent of subjects did follow an increased amount of neutrophils over the course of their illness. This study reinforces the use of nasal cytology by obtaining nasal smears to demonstrate how neutrophil frequencies change with symptom severity