The effects of geometric shapes at different assembly gaps to achieve the optimal hydrodynamic conditions

Author(s):  
Yao Zhang ◽  
Mohammad Javid Najafi ◽  
Mohsen Heydari Beni ◽  
Ali Davar ◽  
Davood Toghraie ◽  
...  
2019 ◽  
Vol 1 (1) ◽  
pp. 22
Author(s):  
Carla Marilia Ayala Valladares ◽  
Juana Maria Cruz Montero ◽  
Angel Saldarriaga Melgar

The main purpose of the research was to determine the effects of the program of ludic activities for the learning of geometry in children of five years in all their dimensions orientation and location, geometric shapes and measurement, through its components: location in space, identify locations and positions of objects, identify and characterize geometric figures and communicate the qualities of these, likewise identify, classify magnitudes and use various measuring instruments. The type of research was applied, with a quasi-experimental design, the population was constituted by 103 children, and a non-probabilistic sample was used for convenience with a sample of 51 children, divided into two control and experimental groups. The geometry instrument was used to collect information. The favorable effect of the program of playful activities in the learning of geometric notions in children of initial - Callao, 2018 was determined.


2016 ◽  
Vol 25 (1) ◽  
pp. 96-109
Author(s):  
Kristen Marangoni

The enigmatic setting of Beckett's novel Watt has been compared to places as diverse as an insane asylum, a boarding school, a womb, and a concentration camp. Watt's experience at Knott's house does seem suggestive of all of these, and yet it may more readily conform to the setting of a monastery. The novel is filled with chants, meditations, choral arrangements, hierarchical classifications, and even silence, all highly evocative of a monastic lifestyle. Some of Watt's dialogue (such as his requests for forgiveness or reflections on the nature of mankind) further echoes various Catholic liturgies. Watt finds little solace in these activities, however. He feels that they are largely rote and purposeless as they are focused on Knott, a figure who in many ways defies linguistic description and physical know-ability. Watt's meditations and rituals become, then, empty catechisms without answers, something that is reflected in the extreme difficulty that Watt has communicating. In the face of linguistic and liturgical instability, the Watt notebooks present a counter reading that can be found in the thousand plus doodles that line its pages. The drawings reinforce as well as subvert their textual counterpart, and they function in many ways as the images in medieval illuminated manuscripts. The doodles in Watt often take the form of decorative letters, elaborate marginal drawings, and depictions of a variety of people and animals, and many of its doodles offer uncanny resemblances in form or theme to those in illuminated manuscripts like The Book of Kells. Doodles of saints, monks, crosses, and scribes even give an occasional pictorial nod to the monastic setting in which illuminated manuscripts were usually produced (and remind us of the monastic conditions in which Beckett found himself writing much of Watt). Beckett's doodles not only channel this medium of illuminated manuscripts, they also modernize its application. Instead of neat geometric shapes extending down the page, his geometric doodle sequences are often abstracted, fragmented, and nonlinear. Beckett also occasionally modernized the content of illuminated manuscripts: instead of the traditional sacramental communion table filled with candles, bread and wine, Beckett doodles a science lab table where Bunsen burners replaces candles and wine glasses function as beakers. It is through these modernized images that Watt attempts to draw contemporary relevance from a classic art form and to restore (at least partial) meaning to rote traditions.


1998 ◽  
Vol 37 (4-5) ◽  
pp. 139-147 ◽  
Author(s):  
Harald Horn ◽  
Dietmar C. Hempel

The use of microelectrodes in biofilm research allows a better understanding of intrinsic biofilm processes. Little is known about mass transfer and substrate utilization in the boundary layer of biofilm systems. One possible description of mass transfer can be obtained by mass transfer coefficients, both on the basis of the stagnant film theory or with the Sherwood number. This approach is rather formal and not quite correct when the heterogeneity of the biofilm surface structure is taken into account. It could be shown that substrate loading is a major factor in the description of the development of the density. On the other hand, the time axis is an important factor which has to be considered when concentration profiles in biofilm systems are discussed. Finally, hydrodynamic conditions become important for the development of the biofilm surface when the Reynolds number increases above the range of 3000-4000.


2016 ◽  
Vol 11 (2) ◽  
pp. 210-217 ◽  
Author(s):  
A.T. Akhmetov ◽  
A.A. Valiev ◽  
A.A. Rakhimov ◽  
S.P. Sametov ◽  
R.R. Habibullina

It is mentioned in the paper that hydrodynamic conditions of a flow in blood vessels with the stenosis are abnormal in relation to the total hemodynamic conditions of blood flow in a vascular system of a human body. A microfluidic device developed with a stepped narrowing for studying of the blood flow at abnormal conditions allowed to reveal blood structure in microchannels simulating the stenosis. Microstructure change is observed during the flow of both native and diluted blood through the narrowing. The study of hemorheological properties allowed us to determine an increasing contribution of the hydraulic resistance of the healthy part of the vessel during the stenosis formation.


Water ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 340
Author(s):  
Wenjuan Ouyang ◽  
Zhe Li ◽  
Jixiang Yang ◽  
Lunhui Lu ◽  
Jinsong Guo

The resting stages of phytoplankton are usually regarded as the seed bank and source of harmful algal blooms because of the recruitment of phytoplankton from sediment to the water column under suitable environmental conditions. Information about resting stages of phytoplankton is abundant in shallow lakes and littoral sea; yet, studies on river–reservoir systems are rare. The river–reservoir continuum shows a unique structuring of longitudinal gradients of hydrological and hydrodynamic conditions. We hypothesized that the seed bank and algal blooms in reservoirs are influenced by the hydrodynamic conditions of each reservoir. We used Illumina Miseq sequencing to examine the spatio-temporal variation in the phytoplankton community in the sediment as reservoir drawdown and in surface water during algal blooms in Pengxi River, a tributary of China’s Three Gorges Reservoir. The results show that the cyanobacteria community in sediment is significantly influenced by temperature, total carbon, maximum flow velocity, and total phosphorous, the eukaryotic phytoplankton community in sediment is significantly influenced by total phosphorous, temperature, total carbon, maximum flow velocity, and total nitrogen. Additionally, the dominant species in sediment is significantly different from that in surface water during algal blooms. Our results suggest that the dominant species in surface water during algal blooms is more influenced by the environmental factors and hydrodynamic conditions in the water column than the seeds in the sediment. These findings are fundamental for further research on the influence of hydrodynamic conditions on algal blooms in artificially regulated river-reservoir systems.


Geology ◽  
2020 ◽  
Vol 48 (12) ◽  
pp. 1144-1148
Author(s):  
Chenliang Wu ◽  
Jeffrey A. Nittrouer ◽  
Travis Swanson ◽  
Hongbo Ma ◽  
Eric Barefoot ◽  
...  

Abstract Dune-scale cross-beds are a fundamental building block of fluvial-deltaic stratigraphy and have been recognized on Earth and other terrestrial planets. The architecture of these stratal elements reflects bed-form dynamics that are dependent on river hydrodynamic conditions, and previous work has documented a multitude of scaling relationships to describe the morphodynamic interactions between dunes and fluid flow. However, these relationships are predicated on normal flow conditions for river systems and thus may be unsuitable for application in fluvial-deltaic settings that are impacted by nonuniform flow. The ways in which dune dimensions vary systematically due to the influence of reach-averaged, nonuniform flow, and how such changes may be encoded in dune cross-strata, have not been investigated. Herein, we explored the influence of backwater flow on dune geometry in a large modern fluvial channel and its implications for interpretation of systematic variability in dune cross-strata in outcrop-scale stratigraphy. This was accomplished by analyzing high-resolution channel-bed topography data for the lowermost 410 km of the Mississippi River, which revealed that dune size increases to a maximum before decreasing toward the river outlet. This spatial variability coincides with enhanced channel-bed aggradation and decreasing dune celerity, which arise due to backwater hydrodynamics. An analytical model of bed-form stratification, identifying spatial variability of cross-set thickness, indicates a prominent downstream decrease over the backwater region. These findings can be used to inform studies of ancient fluvial-deltaic settings, by bolstering assessments of proximity to the marine terminus and associated spatially varying paleohydraulics.


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