Two Staggered Elastic Cylinders in a Cross Flow

2002 ◽  
Author(s):  
Zhongdi Su ◽  
Yang Liu ◽  
Ronald M. C. So
Keyword(s):  
Structural Dynamics ◽  
Cross Flow ◽  
The Other ◽  
Published Data ◽  
Dynamics Model ◽  
Spacing Ratio ◽  
Elastic Cylinders ◽  
Inclined Angle ◽  
Two Degree Of Freedom ◽  
Good Agreement

Two staggered elastic cylinders in a cross flow have been numerically studied. The inclined angles change from 0° to 90° at 15° degree interval while the spacing ratio is maintained at 1.5. The two cylinders are mounted at the ends and are free to move under the action of the unsteady flow-induced forces. The present approach solves the flow field using a finite element method and models the cylinder motions using a two-degree-of-freedom structural dynamics model. Two different cases are considered; one is the rigid case where the cylinders are still, and the other is the elastic case where the cylinders undergo oscillations. Good agreement for the rigid case is obtained between the present 2-D calculations and the previously published data. The investigation also examines the influence of the inclined angle on the vibrations of the cylinders and their spectral analysis.

Vortex-Induced Vibration Characteristics of Two Fixed-Supported Elastic Cylinders

2003 ◽  
Vol 125 (3) ◽  
pp. 551-560 ◽  
Author(s):  
Z. J. Wang ◽  
Y. Zhou ◽  
R. M. C. So
Keyword(s):  
Fluid Dynamics ◽  
Flow Regime ◽  
Cross Flow ◽  
Dynamic Responses ◽  
Vortical Structures ◽  
Vortex Induced Vibrations ◽  
Spacing Ratio ◽  
Elastic Cylinders ◽  
Generation Mechanisms ◽  
Dominant Frequencies

Interference effects on vortex-induced vibrations of two side-by-side elastic cylinders, fixed at both ends (with no deflection and displacement) in a cross-flow, were experimentally investigated. The dynamic responses of the cylinders were measured using two fiber-optic Bragg grating (FBG) sensors. Simultaneously, a single hot wire was used to measure the velocity in the wake. It has been previously observed that violent resonance occurs when transverse cylinder spacing ratio, T/d, is either large (>2.0) or small (<1.2), but not for intermediate cylinder spacing, i.e., T/d=1.2∼2.0. This work aims to improve the understanding of the physics behind this observation, and mostly focuses on the fluid-structure interaction in the flow regime of intermediate cylinder spacing. It is well known that in this flow regime the fluid dynamics around one cylinder is totally different from that around the other; the vortical structures are characterized by different dominant frequencies, i.e., about 0.1 and 0.3 (normalized), respectively. The present data indicates that the vortical structures at these frequencies are either weak or different in the formation process from the case of T/d>2.0 or T/d<1.2, thus resulting in a weak excitation and subsequently an absence of violent resonance. The interrelationship between the vortical structures generated by the two cylinders is also investigated and interpreted in terms of different vortex generation mechanisms. The different fluid dynamics around each cylinder is further found to be responsible for a deviation between the natural frequencies of the combined fluid-cylinder system associated with each cylinder.

Numerical Simulation of Cross-Flow-Induced Fluidelastic Vibration of Tube Arrays and Comparison With Experimental Results

1995 ◽  
Vol 117 (1) ◽  
pp. 31-39 ◽  
Author(s):  
F. L. Eisinger ◽  
M. S. M. Rao ◽  
D. A. Steininger ◽  
K. H. Haslinger
Keyword(s):  
Tube Bundle ◽  
Experimental Testing ◽  
Nonlinear Modeling ◽  
Cross Flow ◽  
Published Data ◽  
Nonlinear Structure ◽  
Numerical Studies ◽  
Tube Arrays ◽  
Fluidelastic Instability ◽  
Good Agreement

Tube arrays exposed to air, gas or liquid cross-flow can vibrate due to vortex-shedding, turbulence, or fluidelastic instability. The major emphasis of this paper is on the phenomenon of fluidelastic instability (or fluidelastic vibration). A numerical model is applied to the simulation of fluidelastic vibration of representative tubes in a tube bundle, based on S. S. Chen’s unsteady flow theory. The results are validated against published data based on linear cases. The model is then applied to a nonlinear structure of a U-bend tube bundle with clearances at supports, and the computed results compared to those obtained by experimental testing. The numerical studies were performed using the ABAQUS-EPGEN finite element code using a special subroutine incorporating fluidelastic forces. It is shown that the results of both the linear and nonlinear modeling are in good agreement with experimental data.

Problems of species and the features of geographical distribution in colonial volvocine algae (Chlorophyta)

2020 ◽  
Vol 54 (2) ◽  
pp. 299-311
Author(s):  
A. G. Desnitskiy
Keyword(s):  
New Species ◽  
Geographical Distribution ◽  
World Literature ◽  
The Other ◽  
Disjunct Distribution ◽  
Published Data ◽  
Species Problem ◽  
Comprehensive Review ◽  
Volvocine Algae ◽  
Cryptic Taxa

More than ten new species of colonial volvocine algae were described in world literature during recent years. In present review, the published data on taxonomy, geographical distribution and the species problem in this group of algae, mainly from the genera Gonium, Pandorina, Eudorina, and Volvox, are critically discussed. There are both cosmopolitan volvocalean species and species with local or disjunct distribution. On the other hand, the description of new cryptic taxa in some genera of the colonial family Volvocaceae, such as Pandorina and Volvox, complicates the preparation of a comprehensive review on their geography.

Removal of Trace Metals From Wastewater by Activated Carbon

1973 ◽  
Vol 8 (1) ◽  
pp. 110-121
Author(s):  
A. Netzer ◽  
J.D. Norman
Keyword(s):  
Activated Carbon ◽  
Trace Metals ◽  
Organic Compounds ◽  
The Other ◽  
Published Data ◽  
Ph Adjustment ◽  
Nickel Silver ◽  
Ph Range ◽  
Carbon Treatment ◽  
Cobalt Copper

Abstract The merits of activated carbon for removal of organic compounds from wastewater have been well documented in the literature. On the other hand there is a lack of published data on the use of activated carbon for the removal of trace metals from wastewater. Experiments were designed to assess the possibility that activated carbon treatment would remove aluminum, cadmium, chromium, cobalt, copper, iron, lead, manganese, mercury, nickel, silver and zinc from wastewater. All metals studied were tested over the pH range 3-11. Greater than 99.5% removal was achieved by pH adjustment and activated carbon treatment for most of the metals tested.

scholarly journals Responses of the Pheromone-Binding Protein of the Silk Moth Bombyx mori on a Graphene Biosensor Match Binding Constants in Solution

Sensors ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 499
Author(s):  
Caroline Bonazza ◽  
Jiao Zhu ◽  
Roger Hasler ◽  
Rosa Mastrogiacomo ◽  
Paolo Pelosi ◽  
...  
Keyword(s):  
Bombyx Mori ◽  
Binding Protein ◽  
Binding Constants ◽  
Isoamyl Acetate ◽  
The Other ◽  
Oxide Surface ◽  
Binding Assays ◽  
Pheromone Binding Protein ◽  
Silk Moth ◽  
Good Agreement

An electronic biosensor for odors was assembled by immobilizing the silk moth Bombyx mori pheromone binding protein (BmorPBP1) on a reduced graphene oxide surface of a field-effect transistor. At physiological pH, the sensor detects the B. mori pheromones, bombykol and bombykal, with good affinity and specificity. Among the other odorants tested, only eugenol elicited a strong signal, while terpenoids and other odorants (linalool, geraniol, isoamyl acetate, and 2-isobutyl-3-methoxypyrazine) produced only very weak responses. Parallel binding assays were performed with the same protein and the same ligands, using the common fluorescence approach adopted for similar proteins. The results are in good agreement with the sensor’s responses: bombykol and bombykal, together with eugenol, proved to be strong ligands, while the other compounds showed only poor affinity. When tested at pH 4, the protein failed to bind bombykol both in solution and when immobilized on the sensor. This result further indicates that the BmorPBP1 retains its full activity when immobilized on a surface, including the conformational change observed in acidic conditions. The good agreement between fluorescence assays and sensor responses suggests that ligand-binding assays in solution can be used to screen mutants of a binding protein when selecting the best form to be immobilized on a biosensor.

Neuroblastoma—When are Urinary Catecholamines and Their Metabolites ‘Normal’?

1988 ◽  
Vol 25 (6) ◽  
pp. 620-626 ◽  
Author(s):  
D J Worthington ◽  
E M Hammond ◽  
B B Eldeeb ◽  
A Green ◽  
G M Addison ◽  
...  
Keyword(s):  
Urinary Excretion ◽  
The Other ◽  
Published Data ◽  
Single Test ◽  
Creatinine Concentration ◽  
Urinary Catecholamines ◽  
Clinical Sensitivity ◽  
Reference Limit ◽  
Upper Reference Limit ◽  
The Individual

The overproduction of catecholamines and their metabolites is a well recognised feature of neuroblastoma. Published data are scarce for their urinary excretion in children with neuroblastoma and in ill children in whom this diagnosis may be considered. We have determined a graphical upper reference limit for total catecholamines, total metadrenalines and HMMA in urine, expressed as a ratio to the creatinine concentration, for a group of 174 children with neuroblastoma and 704 hospitalised children with other disorders. This graph has been determined by examining the overlap region between the results for the two groups of children and avoids the irregularities caused by statistical outliers. The sensitivity and specificity of the individual tests indicate that total catecholamines is marginally the best single test to perform when trying to diagnose neuroblastoma, with the best clinical sensitivity being achieved by examining both total catecholamines and HMMA. Only two of the 174 children with neuroblastoma would not have been detected using these two tests. Total metadrenalines did not appear to add any further information and could be dropped from the repertoire in favour of the other two measurements.

APPLICATION OF A NEW HAMILTONIAN OF INTERACTION TO THREE-DIMENSIONAL STRUCTURES

2004 ◽  
Vol 18 (09) ◽  
pp. 1351-1368
Author(s):  
ANDREI DOLOCAN ◽  
VOICU OCTAVIAN DOLOCAN ◽  
VOICU DOLOCAN
Keyword(s):  
Experimental Data ◽  
Cohesive Energy ◽  
Noble Gases ◽  
Three Dimensional ◽  
The Other ◽  
Ionic Crystals ◽  
Coupling Constant ◽  
Good Agreement

Using a new Hamiltonian of interaction we have calculated the cohesive energy in three-dimensional structures. We have found the news dependences of this energy on the distance between the atoms. The obtained results are in a good agreement with experimental data in ionic, covalent and noble gases crystals. The coupling constant γ between the interacting field and the atoms is somewhat smaller than unity in ionic crystals and is some larger than unity in covalent and noble gases crystals. The formulae found by us are general and may be applied, also, to the other types of interactions, for example, gravitational interactions.

The Structural Framework of Pictorial Balance

Perception ◽  
1996 ◽  
Vol 25 (12) ◽  
pp. 1419-1436 ◽  
Author(s):  
Paul Locher ◽  
Sharon Gray ◽  
Calvin Nodine
Keyword(s):  
Visual Arts ◽  
Structural Features ◽  
Original Compositions ◽  
The Other ◽  
Global Integration ◽  
Artistic Style ◽  
Structural Framework ◽  
Museum Professionals ◽  
Balance Structure ◽  
Good Agreement

Two experiments were performed to examine how the subjective balance of a painting is created by its structural features and to determine if balance influences the way people look at paintings. Stimuli consisted of sixteen reproductions of twentieth-century paintings varying in artistic style and a reconstructed less-balanced version of each. Participants in experiment 1 determined the location of the balance center of each composition, assigned ‘weights’ to the pictorial features which contributed to the location of the balance center, and rated the picture for balance. It was found that design and museum professionals and individuals untrained in the visual arts were in good agreement as to the structural framework underlying the balance organization of a painting. For all participants, disruption of the balanced organizations of the original compositions led to reliable shifts in the location of the perceived balance centers of the originals compared with their less-balanced perturbations. Additionally, it was observed that particular features as such were not the origin of the balance phenomenon; rather, judgments concerning the balance structure and its center were dependent on the global integration of information across a wide area of the display field, but especially from its central region. Last, the subtle changes in balance structure between versions resulted in lower ratings of balance being assigned to the less-balanced perturbations by the design professionals only; the other two participant groups evaluated overall balance of the versions as comparable. In experiment 2, eye movements of a different group of untrained individuals were recorded as they performed similar tasks on the art stimuli. It was found that disruption of the balance structure of the original representational but not abstract compositions resulted in different regions of the original and perturbed versions being visually explored. Findings of both experiments are related to theoretical notions of balance.

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