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This paper presents the design and development of an X-band LFM sweep generator. The proposed waveform generator utilizes a fully synthesized hybrid architecture that combines the advantages of both DDS and PLL. The architecture consists of a synthesized PLL source with DDS as a reference generator. At start up, the PLL is programmed for a fixed frequency while DDS is programmed for a linear triangular...
Cost-effective and compact systems are required for modern airborne earth surveillance and observation platforms. Frequency Modulated Continuous Wave (FMCW) technology and synthetic aperture techniques together yield such systems. FMCW systems are very useful for earth surveillance in both civil and military applications. Huge computation power is required for real time Synthetic Aperture Radar (SAR)...
The design of a narrowband low noise amplifier (LNA) module at Ka band is presented. A low noise MMIC chip fabricated in GaAs pHEMT process is employed. Since the LNA is narrowband, its matching is sensitive to parasitic associated with the bond-wire interconnects and the fixture connectors. A T-type matching network which comprises of a high-low impedance lines is realized on microstrip substrate...
In pursuit of bringing high end applications on radio platforms, recent and evolving wireless standards impose stringent requirements in the shape of high throughputs, error rate performance close to theoretical limits and multi mode transmissions to efficiently use bandwidth in different channel conditions. In the presence of these requirements, the designer comes across contradicting requirements...
High altitude long endurance (HALE) UAVs have very flexible wing because of mission requirements. High lifts to drag ratio and more surveillance time in air requirements make their structure highly flexible and large tip deflections can occur which can be as large as 30% of wing semi span. Linear theory fails to accurately analyze such deformation and the changes in the structural and aerodynamic...
To model the Multiphase flow along with phase transition process is a challenging task. In the present paper, capability of Lattice Boltzmann method (LBM) to simulate flow through complex geometries and multiphase flow has been discussed. LBM is an innovative computational fluid dynamics (CFD) approach based on kinetic models. It describes the physical system as an artificial micro-world of the particles...
Rectangular shaped sieve plate column was installed for study of transport parameters through high speed photography and image analysis. Two Immiscible liquids consisting of the dispersed phase (water) and continuous phase (kerosene oil) were introduced in countercurrent operation. Experiments were performed for dispersed and continuous phase superficial velocities 0.16–0.44 cm/sec and 0.37–0.47 cm/sec...
This study investigates the flow visualization using PIV technique. It is tried to indigenously develop PIV technique with the help of low power laser, ordinary camera, and available tracer particles. PIV results are obtained with the help of some open software. Flow patterns of water containing tracer particles are studied. Flows are induced by magnetic stirrer and rotor. Flow visualization study...
It has been broadly reported in the literature that the large segmented solid rocket motors (SRMs), such as Ariane 5 solid booster (P230) and Space Shuttle RSRM (Re-designed SRM), experience undesirable pressure oscillations that lead to thrust oscillations during combustion due to a complex coupling between the combustion and the internal aerodynamics of the combustion chamber. These fluctuations...
The aerodynamic behavior of delta wing has been investigated both computationally and experimentally. Force measurement experiment has been performed on a 70 degree sweep delta wing model with sharp leading and trailing edges in wind tunnel for a range of angle of attack. A steady-state RANS investigation has been performed using the commercial CFD code ANSYS FLUENT-14. Different visualizations offered...
Flow controlling of boundary layers separation of low-pressure (LP) turbine blade is still a high leverage area for advent of high lift and ultra-high lift LP turbines. At cruising conditions, the Reynolds number in the LP turbine reduces (due to the decrease in air density) to the critical value that flow starts to separate from the blade suction surface. In the present study, cascade T106A is used...
Present study is about free surface effects over shallowly immersed hydrofoil. Naca0012 hydrofoil at angle of attack 5 degree, Froude number of 0.5672 and Reynolds number of 1.7695e6 is studied using unsteady Reynolds average Navier-stokes code with a k-epsilon turbulence model and free surface volume of fluid (VOF) tracking method. Naca0012 hydrofoil is moved with various depths using moving mesh...
A three level layout optimization strategy is proposed in this paper for large-scale composite wing structures. Design requirements are adjusted at the primary level according to structural deformation and strength, then the stringers and ribs layout are designed by the instability criteria at the second level, at last the laminate optimization is used to increase the composite panel carrying efficiency...
The breadth of supramolecular chemistry has progressively increased with the synthesis of numerous unique supramolecules each year. Coordination-driven self-assembly that employ strong and directional metal-ligand bonds for the assembly process is a powerful and facile method to construct the functional and advance materials. This review has scanned some examples in literatures and reported some research...
In order to enhance the catalytic activity of Alumina supported cobalt catalyst (Co/Al2O3) for Fischer Tropsch synthesis, 1.5 and 2.5 wt% Au promoted 10% Co/Al2O3 is synthesized by coprecipitation and impregnation methods. The synthesized catalysts are characterized using XRD, TPR, TGA and BET techniques while fixed bed micro reactor is used to evaluate the activity and selectivity of prepared catalysts...
In this study, the perforation failure of honeycomb sandwich structures is numerically simulated by using homogenized equivalent model. The high velocity impact behavior of aluminum honeycomb core with reinforced carbon/epoxy face sheets is modeled by using commercial finite element (FE) analysis code AUTODYN-3D. It is observed that the detailed three dimensional FE modeling of honeycomb core is complex,...
Presents the front cover or splash screen of the record of the Proceedings of 2013 10th International Bhurban Conference on Applied Sciences & Technology (IBCAST).
Technology Computer Aided Design (TCAD) provides an alternate method to study the power amplifier (PA) design prior to fabrication and is very useful for the extraction of an accurate large signal model. This paper presents a design approach from device to circuit level to study the performance of a broadband PA based on computational load-pull (CLP) analysis. To validate TCAD approach, we have designed...
In the recent years streaming accelerators like GPUs have been pop-up as an effective step towards parallel computing. The wish-list for these devices span from having a support for thousands of small cores to a nature very close to the general purpose computing. This makes the design space very vast for the future accelerators containing thousands of parallel streaming cores. This complicates to...
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