Numerical simulation of Goertler/Tollmien-Schlichting wave-interaction

The problem of nonlinear development of Goertler vortices and interaction with Tollmien-Schlichting (TS) waves is considered within the framework of incompressible Navier-Stokes equations which are solved by a Fourier-Chebyshev spectral method. It is shown that two-dimensional waves can be excited in the flow modulated by Goertler vortices. Due to nonlinear effects, this interaction further leads to the development of oblique waves with spanwise wavelength equal to the Goertler vortex wavelength. Interaction is also considered of oblique waves with spanwise wavelength twice that of Goertler vortices

Computer Simulation of Current Forces on Motion of Floating Production Storage and Offloading in Irregular Waves

This paper presents the effect of current forces on the motion of forces on Floating Production Storage and Offloading (FPSO) in irregular waves. The objective of this research is to compute the motion of FPSO in irregular waves by time domain simulation including the effect of current forces. A study is made on the slowly varying oscillations of a moored single body system in a current and waves. Linear potential theory is used to describe the fluid motion, and three-dimensional source distribution techniques are applied to obtain the hydrodynamic forces and transfer function of the wave exciting forces. OCIMF (1994) data are used for estimation of the current forces. The non-linear time domain simulations have been carried out in irregular waves. Based on it, slowly varying motion responses are examined including the effect of the current forces. Several environmental conditions, such as the current angle of attack, current velocity, significant wave height and mean wave period are considered, which may significantly affect FPSO motion in surge, sway and yaw moments. It is found that the effect of current forces is quite significant when the current velocity is increased. In this simulation, while the current velocity is increased to 3.0 meter/seconds, the impact on FPSO motion is quite significant, which should be taken into consideration from the point of view of safety, failure of mooring systems, operating responses and the dynamic positioning of the FPSO

Performance Enhancement of Wideband Reflectarray Antennas Embedded on Paper Substrate Materials

This research presents an innovative solution to address the bandwidth limitation of microstrip reflectarray antennas. Organic substrate materials with controlled compositions have been characterized to be employed as substrate materials for microstrip reflectarrays. The three proposed materials show low dielectric permittivity values of 1.81, 1.64 and 1.84 along with loss tangents of 0.053, 0.047 and 0.057 respectively. The proposed substrate materials have been verified by modelling reflectarray unit elements in CST MWS and measured using a waveguide simulator technique. The comparison between measured and simulated results show a good agreement with promising broadband performance of 312, 340 and 207 MHz for S1, S2 and S3 substrate materials respectively

New Lie group of transformation for the non-Newtonian fluid flow narrating differential equations

In this endeavour, a new Lie point of transformation for the fluid flow narrating differential equations are proposed. For this purpose a non-Newtonian fluid named tangent hyperbolic fluid is considered towards the flat surface in a magnetized flow field. In addition, equation of concentration admits the role of chemically reactive species. A mathematical model in terms of the coupled PDE’s is constructed. Lie group of analysis is implemented to yield the new Lie point of transformation for tangent hyperbolic fluid flow narrating differential equations when the heat and mass transfer individualities are considered. The resultant system of PDE’s is reduced into system of ODE’s via obtained set of transformation. The self-coded computational scheme is accomplished and the outcomes are reported by way of graphs. It is noticed that tangent hyperbolic fluid velocity, temperature and concentration is decreasing function of magnetic field parameter, Prandtl number and chemical reaction parameter respectively

Design and analysis of dual U slot reflectarray antenna for X-band applications

A novel design of a dual frequency single layer reflectarray antenna is presented for X-band frequency applications. Dual U slots embedded on conventional rectangular microstrip reflectarray have been designed to attain a dual frequency operation. A detailed analysis of the effect on surface current distributions with the introduction of dual U slots is presented. Moreover a parametric study on the variation of significant dimensions of the design have been carried out and analysed thoroughly using a commercially available CST computer model. Proposed design configurations were fabricated above a 0.508 mm thick substrate of Rogers Duroid 5880. The dual U slot configuration offers a significant dual frequency behavior at 8.54 and 11.56 GHz with 10% bandwidth improvement of 47 and 56 MHz with a reflection loss of -4.54 and 4.11 dB respectively

Design and analysis of dual U slot reflectarray antenna for X-band applications

A novel design of a dual frequency single layer reflectarray antenna is presented for X-band frequency applications. Dual U slots embedded on conventional rectangular microstrip reflectarray have been designed to attain a dual frequency operation. A detailed analysis of the effect on surface current distributions with the introduction of dual U slots is presented. Moreover a parametric study on the variation of significant dimensions of the design have been carried out and analysed thoroughly using a commercially available CST computer model. Proposed design configurations were fabricated above a 0.508 mm thick substrate of Rogers Duroid 5880. The dual U slot configuration offers a significant dual frequency behavior at 8.54 and 11.56 GHz with 10% bandwidth improvement of 47 and 56 MHz with a reflection loss of -4.54 and 4.11 dB respectively

Effect of crossflow on Goertler instability in incompressible boundary layers

Linear stability theory is used to study the effect of crossflow on Goertler instability in incompressible boundary layers. The results cover a wide range of sweep angle, pressure gradient, and wall curvature parameters. It is shown that the crossflow stabilizes Goertler disturbances by reducing the maximum growth rate and shrinking the unstable band of spanwise wave numbers. On the other hand, the effect of concave wall curvature on crossflow instability is destabilizing. Calculations show that the changeover from Goertler to crossflow instabilities is a function of Goertler number, pressure gradient, and sweep angle. The results demonstrate that Goertler instability may still be relevant in the transition process on swept wings even at large angles of sweep if the pressure gradient is sufficiently small. The influence of pressure gradient and sweep can be combined by defining a crossflow Reynolds number. Thus, the changeover from Goertler to crossflow instability takes place at some critical crossflow Reynolds number whose value increases with Goertler number

Comparative study of different hill climbing MPPT through simulation and experimental test bed

Hill climbing MPPT technique is commonly used in photovoltaic systems in order to achieve maximum power from it. Due to the massive numbers of the MPPT techniques in this field, it becomes essential to find and verify the most effective, simplest and reliable technique to be used. In this paper comparative studies of two different climbing MPPTs that are conventional perturb and observe and modified perturb and observe has been performed. The paper verifies their tracking performance through calculations. Simulations are also performed using MATLAB SIMULINK and results are analyzed. In addition, hardware implementation has been carried out which verifies simulation results. This study should serve as a strong evidence for practical feasibility of the modified perturb and observe method for MPPT

DIET COMPOSITION OF ANOA (Buballus sp.) STUDIED USING DIRECT OBSERVATION AND DUNG ANALYSIS METHOD IN THEIR HABITAT

Anoa are fully protected under Indonesian Law since 1931 (Law of Protection of Wild Animals 1931, no 134). Increasing law enforcement regarding hunting as well as promoting awareness of the Anoas unique threatened the existence of conservation measures. The modern concept of conservation based on the sustainability utilization, and therefore the knowledge of the Anoa preference in feeding to support the sustainability conservation should be studied. In the present study, the combination of direct observation methods which was done in the Lore Lindu National Park in Toro village at District Kulawi, Central Sulawesi and the epidermal analysis method which was carried out to Anoa’s dung were aimed to identify the vegetations preferred by Anoa in their habitat. The result showed 28 species of vegetations was used as feed by Anoa on in situ area. According to its percentage, the first ten were Freycinetia insignis Blume (17%), Microlepia todayensis Christ (8.9%), Disoxylum sp (8.6%), Lasianthus clementis Merr (7.7%), Clusia sp (7.5%), Schleria sp (6%), Podocarpus imbricatus (5.4%), Smilax leucophylla (5.1%), Elastostema sp (4.2%), and Garcinia sp (3.8%), respectively. Furthermore, it can be concluded that Anoa was eat more leafs and shrubs/bushes (each 24%, respectively) compared to flowers (18%), fruits (12%), shoots (8%), grasses, tubers, young grooves (each 4%, respectively) and moss (2%). Nutritionally, Anoa consumed 8.8% protein and 25.6% crude fiber. Keywords: Diet Composition, Dung Analysis, Ano

Self concept, level of aspiration and academic achievement of physically challenged and normal students at secondary level in district Barramullah

This study was undertaken to study the self concept, level of aspiration and academic achievement of normal and physically challenged secondary school students of district Baramullah(J and k).The sample for the study was 300 including 150 normal and 150 physically challenged secondary school students by using random and purposive sampling technique. Sagar and Sharma's self concept inventory, Mahesh Bhargava and M.A.Shah's level of aspiration scale were administered for the collection of data. The result of the study highlight that the normal secondary school students have high real self, level of aspiration and academic achievement as compared to physically challenged students. On the other hand, physically challenged students were found to have high ideal self as compared to normal students. Key words: Self concept, level of aspiration, academic achievement, physically challenged, normal student