Withdrawal: Numerical studies of a buoy system; a comparison between LES and SAS

2018 ◽  
Author(s):  
Marcel Ilie ◽  
Keaton Harris
Keyword(s):  
System A ◽  
Numerical Studies

Effect of Geometry Changes in an Aggressive Turbine Exhaust Delivery System

2013 ◽  
Author(s):  
Shweta Dobhal ◽  
A. M. Pradeep ◽  
Bhaskar Roy
Keyword(s):  
Delivery System ◽  
Pressure Rise ◽  
Exhaust System ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
System A ◽  
Numerical Studies ◽  
Annular Diffuser ◽  
Better Than ◽  
Turbine Exhaust

The paper reports numerical studies carried out on an aggressive turbine exhaust delivery system. A typical industrial turbine exhaust system has been used as the baseline configuration. Several geometry modifications of the diffuser system were attempted to study their effect on the diffuser performance. The geometrical modifications used were 1) Blended shapes — a blended strut-hub geometry; 2) Repositioning of the struts; and 3) contoured hub end. The performance of the diffusers has been quantified in terms of total pressure loss and static pressure rise coefficient across the diffuser. The last stage turbine tip leakage flow has been simulated by using annular casing injectors applied ahead of annular diffuser. The effect of varying the rate of injection has also been analyzed. In addition, the effect of shortening the length of the diffuser was studied. Modification-2, as stated above, has been applied on the shortened aggressive diffuser and it was observed that with injection the performance of shortened aggressive diffuser is better than that of the baseline configuration.

Experimental and numerical studies on the thermal performance of ventilated BIPV curtain walls

2015 ◽  
Vol 26 (9) ◽  
pp. 1243-1256 ◽  
Author(s):  
Chi-ming Lai ◽  
Shuichi Hokoi
Keyword(s):  
Thermal Performance ◽  
Flow Mechanism ◽  
Pv System ◽  
Cfd Simulations ◽  
Buoyant Force ◽  
System A ◽  
Numerical Studies ◽  
Building Integrated Photovoltaic ◽  
Double Skin ◽  
Computational Fluid Dynamics Cfd

In this study, we integrated a photovoltaic (PV) system, a double-skin structure and a thermal flow mechanism to design ventilated building-integrated photovoltaic (BIPV) curtain walls that can autogenously control an environment using buoyant force. Full-scale experiments and computational fluid dynamics (CFD) simulations were conducted to investigate the flow pattern characteristics for the channel airflow and the thermal performance of the ventilated BIPV curtain walls under various heating conditions, wall thicknesses and types of openings. Channel flows for different channel widths under the same wall heating exhibited different flow patterns and therefore variations in thermal performance. The developed ventilated BIPV curtain walls effectively removed their solar heat gain while maintaining adequate wall thermal performance.

scholarly journals ON A DYNAMICAL SYSTEM WITH MULTIPLE CHAOTIC ATTRACTORS

2007 ◽  
Vol 17 (09) ◽  
pp. 3235-3251 ◽  
Author(s):  
XIAODONG LUO ◽  
MICHAEL SMALL ◽  
MARIUS-F. DANCA ◽  
GUANRONG CHEN
Keyword(s):  
Dynamical System ◽  
Monte Carlo ◽  
Chaotic Behavior ◽  
Hypothesis Test ◽  
Surrogate Data ◽  
Chaotic Attractors ◽  
System A ◽  
Numerical Studies

The chaotic behavior of the Rabinovich–Fabrikant system, a model with multiple topologically different chaotic attractors, is analyzed. Because of the complexity of this system, analytical and numerical studies of the system are very difficult tasks. Following the investigation of this system carried out in [Danca & Chen, 2004], this paper verifies the presence of multiple chaotic attractors in the system. Moreover, the Monte Carlo hypothesis test (or, equivalently, surrogate data test) is applied to the system for the detection of chaos.

scholarly journals Negative Index Metamaterial Lens for Subwavelength Microwave Detection

Sensors ◽  
2021 ◽  
Vol 21 (14) ◽  
pp. 4782
Author(s):  
Srijan Datta ◽  
Saptarshi Mukherjee ◽  
Xiaodong Shi ◽  
Mahmood Haq ◽  
Yiming Deng ◽  
...  
Keyword(s):  
Refractive Index ◽  
Periodic Structures ◽  
Negative Refractive Index ◽  
Far Field ◽  
Lens Design ◽  
Theoretical Formulation ◽  
System A ◽  
Numerical Studies ◽  
Naturally Occurring

Metamaterials are engineered periodic structures designed to have unique properties not encountered in naturally occurring materials. One such unusual property of metamaterials is the ability to exhibit negative refractive index over a prescribed range of frequencies. A lens made of negative refractive index metamaterials can achieve resolution beyond the diffraction limit. This paper presents the design of a metamaterial lens and its use in far-field microwave imaging for subwavelength defect detection in nondestructive evaluation (NDE). Theoretical formulation and numerical studies of the metamaterial lens design are presented followed by experimental demonstration and characterization of metamaterial behavior. Finally, a microwave homodyne receiver-based system is used in conjunction with the metamaterial lens to develop a far-field microwave NDE sensor system. A subwavelength focal spot of size 0.82λ was obtained. The system is shown to be sensitive to a defect of size 0.17λ × 0.06λ in a Teflon sample. Consecutive positions of the defect with a separation of 0.23λ was resolvable using the proposed system.

scholarly journals Review of the hydraulic capacity of urban grate inlet: a global and Latin American perspective

2021 ◽  
Author(s):  
M. Cárdenas-Quintero ◽  
F. Carvajal-Serna
Keyword(s):  
Latin American ◽  
Numerical Models ◽  
Urban Drainage ◽  
Sewer Pipes ◽  
System A ◽  
American Perspective ◽  
Numerical Studies ◽  
Starting Point ◽  
Uptake Process ◽  
Urbanized Region

Abstract The most recent numerical models of urban drainage allow the integration of runoff from roads with the network of sewer pipes, thus evolving towards a holistic version of the system. A fundamental part of this integration is the capture of stormwater in urban drain inlets. These studies have recently increased, resulting in different methodologies to represent the uptake process and making it difficult to apply unified or general formulations. Therefore, this document intends to be a review of the most representative experimental and numerical studies on the capture of rainwater through grates. In addition, the review includes the proposed methodologies for estimating the flow captured by urban storm drains to define a starting point for new and complementary studies to be carried out by researchers, manufacturers, and operators involved in public drainage service systems. Particularly in Latin America, research on the subject is limited even though it is a highly urbanized region. In this context, this document has an additional interest in presenting a particular analysis of the concept of urban drainage in Latin American cities.

New Design for a Differentially Pumped Hydration Chamber for a Siemens IA

1971 ◽  
Vol 29 ◽  
pp. 44-45
Author(s):  
R. C. Moretz ◽  
G. G. Hausner ◽  
D. F. Parsons
Keyword(s):  
Electron Microscopy ◽  
Water Vapor ◽  
Electron Diffraction ◽  
Water Vapor Pressure ◽  
Biological Materials ◽  
Thin Membrane ◽  
Reliable System ◽  
System A ◽  
Water Films ◽  
Aperture Opening

Electron microscopy and diffraction of biological materials in the hydrated state requires the construction of a chamber in which the water vapor pressure can be maintained at saturation for a given specimen temperature, while minimally affecting the normal vacuum of the remainder of the microscope column. Initial studies with chambers closed by thin membrane windows showed that at the film thicknesses required for electron diffraction at 100 KV the window failure rate was too high to give a reliable system. A single stage, differentially pumped specimen hydration chamber was constructed, consisting of two apertures (70-100μ), which eliminated the necessity of thin membrane windows. This system was used to obtain electron diffraction and electron microscopy of water droplets and thin water films. However, a period of dehydration occurred during initial pumping of the microscope column. Although rehydration occurred within five minutes, biological materials were irreversibly damaged. Another limitation of this system was that the specimen grid was clamped between the apertures, thus limiting the yield of view to the aperture opening.

High-resolution electron microscopy of Cu2O surfaces

1986 ◽  
Vol 44 ◽  
pp. 396-397
Author(s):  
V. Castano ◽  
W. Krakow
Keyword(s):  
High Resolution ◽  
Natural Extension ◽  
High Resolution Electron Microscopy ◽  
Point Of View ◽  
Initial Oxidation ◽  
System A ◽  
Resolution Electron ◽  
Surface Reconstructions ◽  
Atomic Surface ◽  
Au Thin Films

In non-UHV microscope environments atomic surface structure has been observed for flat-on for various orientations of Au thin films and edge-on for columns of atoms in small particles. The problem of oxidation of surfaces has only recently been reported from the point of view of high resolution microscopy revealing surface reconstructions for the Ag2O system. A natural extension of these initial oxidation studies is to explore other materials areas which are technologically more significant such as that of Cu2O, which will now be described.

Twin boundary structure of a Y-Ba-Cu-O superconductor

1989 ◽  
Vol 47 ◽  
pp. 168-169
Author(s):  
Yimei Zhu ◽  
Masaki Suenaga ◽  
R. L. Sabatini ◽  
Youwen Xu
Keyword(s):  
Twin Boundary ◽  
Fine Particles ◽  
Imaging Techniques ◽  
Fine Powder ◽  
Orthorhombic Phase ◽  
Boundary Structure ◽  
Crystallographic Axis ◽  
System A ◽  
High Resolution Structure ◽  
Electron Microscopes

The (110) twin structure of YBa2Cu3O7 superconductor oxide, which is formed to reduce the strain energy of the tetragonal to orthorhombic phase transformation by alternating the a-b crystallographic axis across the boundary, was extensively investigated. Up to now the structure of the twin boundary still remained unclear. In order to gain insight into the nature of the twin boundary in Y-Ba-Cu-O system, a study using electron diffraction techniques including optical and computed diffractograms, as well as high resolution structure imaging techniques with corresponding computer simulation and processing was initiated.Bulk samples of Y-Ba-Cu-O oxide were prepared as described elsewhere. TEM specimens were produced by crushing bulk samples into a fine powder, dispersing the powder in acetone, and suspending the fine particles on a holey carbon grid. The electron microscopy during this study was performed on both a JEOL 2000EX and 2000FX electron microscopes operated at 200 kV.

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