scholarly journals BIAS ERRORS IN STUDIES ON SEDIMENT – LADEN FLOW IN SHORT EXPERIMENTAL CHANNELS / SISTEMINGOSIOS PAKLAIDOS, TYRINĖJANT NEŠMENIS PLUKDANČIAS TĖKMES PER TRUMPUOSE EKSPERIMENTINIUOSE LATAKUOSE / CИСТEМНЫE ПОГРЕШНОСТИ В ЭКСПЕРИМЕНТАЛЬНЫX ИCCЛEДOВAНИЯХ ВЗВECEНЕСУЩИХ ПОТОКOВ В КOPOТКИX ЛАБОРАТОРНЫХ ЛОТКАХ

2011 ◽  
Vol 19 (3) ◽  
pp. 198-207 ◽  
Author(s):  
Alfonsas Rimkus ◽  
Saulius Vaikasas ◽  
Boris Gjunsburgs
Keyword(s):  
Sediment Concentration ◽  
Channel Length ◽  
Suspension Flow ◽  
Scientific Development ◽  
Published Data ◽  
Sediment Distribution ◽  
Normal Character ◽  
Laboratory Investigations ◽  
Quality And Reliability ◽  
Further Development

For the further development of suspension flow theory extensive researches are performed in many hydraulic laboratories, as the up-to-date theory is not able to solve many practical problems yet. However, the recent methods of laboratory investigations and experimental equipment are not quite complete for successful scientific development yet. Analysis of published data of sediment-laden flow investigations revealed, that in many cases the experimental channel length was not sufficient for stabilization of sediment distribution along the water depth of flow, giving rise to bias errors. Unusual and unexplained deviations of experimental dependences from their normal character were detected in experimental dependences of sediment concentration, flow velocities and their fluctuations. These deviations were not similar to accidental measurement failures, as they were regular and the experimental points did not significantly disperse. It seemed as if they arose under the influence of certain unknown factors, which could reduce the quality, and reliability of experimental data and further conclusions. Therefore, it was necessary to establish the reasons for their occurrence. In the paper, these reasons and ways of eliminating these errors are considered. Santrauka Gausūs eksperimentiniai turbulentinių srautų struktūrų tyrimai atliekami daugelyje hidraulinių laboratorijų. Tiriant skendinčiujų nešmenų pasiskirstymą tėkmėse siekiama toliau plėtoti teoriją bei ją geriau pritaikyti praktiniams uždaviniams spręsti. Deja, turima eksperimentinė įranga ir tyrimų metodai vis dar nėra pakankamai tobuli, todėl dažnai būdavo gaunamos nemažos sistemingosios paklaidos. Įvairių tyrėjų moksliniuose straipsniuose pateiktų duomenų analizė tai patvirtino. Daugeliu atvejų tyrimams naudojamų eksperimentinių latakų ilgis buvo nepakankamas skendinčiųjų nešmenų pasiskirstymui stabilizuoti. Tai ir buvo tų paklaidų, o kartais ir neteisingų išvadų, priežastis. Analizuojant tyrimų duomenis pastebėta sunkiai paaiškinami nešmenų koncentracijos, tėkmės greičių bei turbulentinių pulsacijų nukrypimai nuo įprastinių. Šie nukrypimai nebuvo matavimų paklaidos ar netikslumai, nes jie reguliariai kartojosi, o eksperimentinių kreivių taškų sklaida buvo maža. Akivaizdu, kad jie atsirado dėl kažkokių dar nenustatytų veiksnių, kurie savaip formavo turbulentinės tėkmės sūkurių struktūrą atliekamų matavimų pjūvyje. Darbo tikslas – nustatyti tos struktūros formavimosi eksperimentiniuose latakuose eigą ir rasti būdų išvengti nešmenų matavimo sistemingujų paklaidų. Резюме Для дальнейшего развития теории взвесенесущего потока многочисленные экспериментальные исследованияпроводятся во многих гидравлических лабораториях мира, так как современная теория еще не в состоянии решитьмногие практические задачи. Однако ни современное лабораторное оборудование, ни методы исследования неявляются достаточно совершенными. Анализ результатов опубликованных исследований показал, что во многихслучаях длина экспериментальных лотков была недостаточной для стабилизации вертикального распределениявзвешенных наносов в потоке воды. Это приводило к существенным систематическим ошибкам, а иногда и к неправильным выводам. Наблюдались трудно объяснимые отклонения получаемых экспериментальных зависимостей от их обыкновенного характера. Они не могли быть объяснены погрешностями измерений, так как былирегулярны, а экспериментальные точки не были слишком разбросаны. Повидимому, они возникли под влияниемеще не установленных факторов. Было необходимо установить причины этих явлений и пути устранения появляющихся ошибок, что и стало целью работы, излагаемой в настоящей статье.

scholarly journals Biological Fingerprinting of Herbal Samples by Means of Liquid Chromatography

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Łukasz Cieśla
Keyword(s):  
Quality Control ◽  
Liquid Chromatography ◽  
Thin Layer ◽  
Published Data ◽  
Fingerprint Analysis ◽  
Chromatographic Techniques ◽  
Liquid Chromatographic ◽  
Further Development ◽  
Layer Chromatography ◽  
Chromatographic Fingerprinting

Biological chromatographic fingerprinting is a relatively new concept in the quality control of herbal samples. Originally it has been developed with the application of HPLC, and recently herbal samples' biological profiles have been obtained by means of thin-layer chromatography (TLC). This paper summarizes the application of liquid chromatographic techniques for the purpose of biological fingerprint analysis (BFA) of complex herbal samples. In case of biological TLC fingerprint, which is a relatively novel solution, perspectives of its further development are outlined in more detail. Apart from already published data, some novel results are also shown and briefly discussed. The paper aims at drawing scientists' attention to the unique solutions offered by biological fingerprint construction.

scholarly journals Tidal Variation in Cohesive Sediment Distribution and Sensitivity to Flocculation and Bed Consolidation in An Idealized, Partially Mixed Estuary

2019 ◽  
Vol 7 (10) ◽  
pp. 334 ◽  
Author(s):  
Tarpley ◽  
Harris ◽  
Friedrichs ◽  
Sherwood
Keyword(s):  
Settling Velocity ◽  
Transport Model ◽  
Tidal Flow ◽  
Sediment Concentration ◽  
Tidal Variation ◽  
Model Framework ◽  
Sediment Distribution ◽  
Floc Size ◽  
Size Classes ◽  
Suspended Floc

Particle settling velocity and erodibility are key factors that govern the transport of sediment through coastal environments including estuaries. These are difficult to parameterize in models that represent mud, whose properties can change in response to many factors, including tidally varying suspended sediment concentration (SSC) and shear stress. Using the COAWST (Coupled Ocean-Atmosphere-Wave-Sediment Transport) model framework, we implemented bed consolidation, sediment-induced stratification, and flocculation formulations within an idealized two-dimensional domain that represented the longitudinal dimension of a micro-tidal, muddy, partially mixed estuary. Within the Estuarine Turbidity Maximum (ETM), SSC and median floc diameter varied by a factor of four over the tidal cycle. Downstream of the ETM, the median floc size and SSC were several times smaller and showed less tidal variation (~20% or less). The suspended floc distributions only reached an equilibrium size as a function of SSC and shear in the ETM at peak tidal flow. In general, flocculation increased particle size, which reduced SSC by half in the ETM through increased settling velocity. Consolidation also limited SSC by reduced resuspension, which then limited floc growth through reduced SSC by half outside of the ETM. Sediment-induced stratification had negligible effects in the parameter space examined. Efforts to lessen the computation cost of the flocculation routine by reducing the number of size classes proved difficult; floc size distribution and SSC were sensitive to specification of size classes by factors of 60% and 300%, respectively.

scholarly journals Unexpected Small Urinary Bladder Pheochromocytoma: A Nonspecific Presentation

2013 ◽  
Vol 2013 ◽  
pp. 1-4
Author(s):  
Faouzi Mallat ◽  
Wissem Hmida ◽  
Adel Slama ◽  
Faouzi Mosbah
Keyword(s):  
Urinary Bladder ◽  
Transurethral Resection ◽  
Histopathological Examination ◽  
Hypertensive Crisis ◽  
Published Data ◽  
Radiologic Findings ◽  
Radiological Images ◽  
Laboratory Investigations ◽  
Physical Findings

Objectives. Pheochromocytoma of the urinary bladder is an extremely rare tumor that typically presents with a hypertensive crisis during micturition. Preoperatively, it may be misdiagnosed due to nonspecific symptomatology, physical, and radiologic findings.Method. We report a case of unsuspected small pheochromocytoma which was incidentally found by CT scan and confirmed by the histological aspects after transurethral resection in a 63-year-old woman. Here, we have described the clinical presentation, physical findings, laboratory investigations, and treatment provided in our case. We have also included radiological images and histopathology slides with input from both radiologists and pathologists. Surgical management and postoperative follow-up are discussed, as are details of previous published data.Results. After undergoing surgical treatment (transurethral resection), our patient is asymptomatic, with complete resolution of her pathology.Conclusion. Diagnosis is difficult before histopathological examination and should be considered in patients with no risk factors for usual bladder tumor. Our purpose is to raise clinician's awareness for this condition so that they will be more likely to diagnose it. This will facilitate prompt diagnosis and treatment and especially prevent complications due to pheochromocytoma which may be severe.

Analysis for the Characteristics of Sediment in Tarim River

2014 ◽  
Vol 641-642 ◽  
pp. 25-28
Author(s):  
Shao Yun Deng
Keyword(s):  
Sediment Transport ◽  
Sediment Load ◽  
Sediment Concentration ◽  
Annual Runoff ◽  
Tarim River ◽  
Main Stream ◽  
Water Network ◽  
Annual Average ◽  
Sediment Distribution ◽  
Annual Sediment

The author had given a brief introduction of Tarim River, and the analysis of its water network and the surrounding environmental features, and a few important representative of Tarim River tributaries and the main stream of the four major hydrological stations measured runoff for many years, the annual runoff, the average annual sediment load, the annual sediment load, the annual average sediment concentration, the annual sediment concentration, the average annual sediment transport modulus, the annual sediment transport modulus index data were analyzed. And on this basis, the author had given the further analysis of Tarim River stream sediment distribution characteristics, and had described the sediment source and characteristics of Tarim River.

scholarly journals A New Formula for Prediction of Crack Widths in Reinforced and Partially Prestressed Concrete Beams

2001 ◽  
Vol 4 (2) ◽  
pp. 101-110 ◽  
Author(s):  
S. H. Chowdhury ◽  
Y. C. Loo
Keyword(s):  
Prestressed Concrete ◽  
Concrete Beams ◽  
Published Data ◽  
Test Results ◽  
Average Crack ◽  
Laboratory Investigations ◽  
Width Measurements ◽  
The Comparative Study ◽  
New Formula ◽  
Crack Widths

A new formula for predicting the average crack widths in reinforced and partially prestressed concrete beams has been developed incorporating four governing parameters. The performance of the proposed formula is checked using the authors' test results which includes crack spacing and crack width measurements from 18 reinforced and 12 partially prestressed concrete beams. Also included in the comparison are published data on 76 beams from other laboratory investigations. The comparative study indicates that the predictions are accurate. The performance of the proposed formula is also compared with three major code formulas, viz those recommended in the ACI Building Code, the British Standard and the Eurocode. It is concluded that better correlation with test data is achieved by the proposed formula.

Turbulent Flow Heat Transfer and Friction in a Rectangular Channel With Varying Numbers of Ribbed Walls

1997 ◽  
Vol 119 (2) ◽  
pp. 374-380 ◽  
Author(s):  
P. R. Chandra ◽  
M. E. Niland ◽  
J. C. Han
Keyword(s):  
Heat Transfer ◽  
Turbulent Flows ◽  
Rectangular Channel ◽  
Reynolds Numbers ◽  
Channel Length ◽  
Diameter Ratio ◽  
Hydraulic Diameter ◽  
Published Data ◽  
Flow Heat ◽  
Turbulent Air Flow

An experimental study of wall heat transfer and friction characteristics of a fully developed turbulent air flow in a rectangular channel with transverse ribs on one, two, and four walls is reported. Tests were performed for Reynolds numbers ranging from 10,000 to 80,000. The pitch-to-rib height ratio, P/e, was kept at 8 and rib height-to-channel hydraulic diameter ratio, e/Dh, was kept at 0.0625. The channel length-to-hydraulic diameter ratio, L/Dh, was 15. The heat transfer coefficient and friction factor values were enhanced with the increase in the number of ribbed walls. The friction roughness function, R(e+), was almost constant over the entire range of tests performed and was within comparable limits of the previously published data. The heat transfer roughness function, G(e+), decreased with additional ribbed walls and compared well with previous work in this area. Friction data obtained experimentally for the case with four ribbed walls compared well with the values predicted by the assumed theoretical relationship used in the present study and past publications. Results of this investigation could be used in various applications of internal channel turbulent flows involving different numbers of roughened walls.

scholarly journals SEDIMENT TRANSPORT ON THE SOUTH-EAST AUSTRALIAN CONTINENTAL SHELF

1984 ◽  
Vol 1 (19) ◽  
pp. 131 ◽  
Author(s):  
Angus D. Gordon ◽  
John G. Hoffman
Keyword(s):  
Sediment Transport ◽  
Continental Shelf ◽  
Suspended Sediment ◽  
Transport System ◽  
Sediment Concentration ◽  
High Energy ◽  
Sediment Distribution ◽  
Sediment Movement ◽  
Shelf Sediment ◽  
Sea Bed

Engineering projects on the continental shelf off Sydney, Australia, have stimulated investigation into the sediment transport system of the shelf. Investigation activities associated with these projects have included: definition of sea bed morphology, sediment distribution and bedform characteristics; monitoring of steady and wave induced currents; wind data collection; suspended sediment sampling; bottom camera sediment movement investigations and analytical studies of sediment reaction to sea bed forcing functions. Sea bed velocity exceedence relationships for both wave oscillations and steady currents have been determined at depths of 24 m, 60 m and 80 m. Thresholds of sediment movement have been defined. Relative sediment transport computations have been undertaken and studies of suspended sediment concentration profiles are in progress so that absolute transport rates can be determined. The prevailing conditions, which include a mainly south bound current, are seldom sufficient to induce entrainment of shelf sediments. Transport events mainly result from major storms in the Tasman Sea which produce both high energy waves and north bound currents. Although these events are rare and short lived, the combined wave and current shear produced at the sea bed during the events gives rise to entrainment conditions which result in their dominance of the shelf sediment transport system.

scholarly journals Disturbances of intestinal microbiota in autism spectrum disorders: new horizons in search for pathogenetic approaches to therapy. Рart 3. Рotential strategies of influence on gut-brain axis for correction of symptoms of autism spectrum disorders

2021 ◽  
Vol 98 (3) ◽  
pp. 331-338
Author(s):  
A. S. Blagonravova ◽  
T. V. Zhilyaeva ◽  
D. V. Kvashnina
Keyword(s):  
Autism Spectrum Disorders ◽  
Intestinal Microbiota ◽  
Autism Spectrum ◽  
Published Data ◽  
New Horizons ◽  
Intestinal Dysbiosis ◽  
Spectrum Disorders ◽  
Based Medicine ◽  
Further Development

The third part of the literature review on the role of intestinal microbiota disturbances in the pathogenesis of autism spectrum disorders (ASD) is devoted to the analysis of published literature on possible interventional approaches for intestinal microbiota in ASD and the evaluation of the effectiveness of various types of interventions that have been studied in experiment and in clinical practice. Presented are available data on the possibility of correcting the intestinal microbiota in ASD with diet, taking pre- and probiotics, antibiotic therapy, as well as the effectiveness of transplantation of intestinal microbiota. An analysis of published data suggests that further development of approaches for correcting intestinal dysbiosis in ASD may provide safe and probably effective strategy for behavioral symptoms, but this requires further randomized controlled trials to confirm efficacy and safety from the perspective of evidence-based medicine, since available to date studies are small and scattered, and therefore they can only be considered preliminary.

scholarly journals PROSPECTS OF DISK PUMP FOR MECHANICAL CIRCULATORY SUPPORT IN CARDIAC SURGERY (REVIEW)

2016 ◽  
Vol 18 (3) ◽  
pp. 68-73 ◽  
Author(s):  
A. M. Chernyavskiy ◽  
A. V. Fomichev ◽  
T. M. Ruzmatov ◽  
A. E. Medvedev ◽  
Yu. M. Prikhodko ◽  
...  
Keyword(s):  
Support Systems ◽  
Experimental Studies ◽  
Viscous Friction ◽  
Left Ventricular ◽  
Circulatory Support ◽  
Published Data ◽  
Technical Requirements ◽  
New Directions ◽  
Further Development ◽  
Mechanical Heart Support

The need of circulatory support systems in the treatment of chronic heart failure is increasing constantly, as 20% of the patients on the waiting list die every year. Despite the great need for mechanical heart support systems, the use of available systems is limited by its expensiveness. In addition, there is no one system that is 100% responsible to all medical and technical requirements and that would be completely safe for patient. Therefore, further research in the field of circulatory support systems considering health and technical requirements is relevant. One of the new directions in the study are disc pumps of viscous friction for liquid transporting, based on the Tesla pump principle. The operation principle of such pumps is based on the phenomenon of the boundary layer which is formed on the disk rotating in a fluid. There are experimental studies of models with different variants of the rotor suspension, various forms and numbers of the disks, forms of the pump housing. However, none of the above samples was brought to clinical trials. Furthermore, despite the potential of that model there have been no pumps of similar type used so far in circulatory support systems. Published data provide a basis for further development and testing of the pump model and allow hoping for leveling a number of significant shortcomings of modern left ventricular bypass systems. 

scholarly journals HY-1C Observations of the Impacts of Islands on Suspended Sediment Distribution in Zhoushan Coastal Waters, China

2020 ◽  
Vol 12 (11) ◽  
pp. 1766
Author(s):  
Lina Cai ◽  
Minrui Zhou ◽  
Jianqiang Liu ◽  
Danling Tang ◽  
Juncheng Zuo
Keyword(s):  
Suspended Sediment ◽  
Coastal Waters ◽  
Near Infrared ◽  
Sediment Concentration ◽  
Vortex Street ◽  
Outer Side ◽  
Sediment Distribution ◽  
Vortex Streets ◽  
Karman Vortex

We analyzed the impacts of islands on suspended sediment concentration (SSC) in Zhoushan Coastal waters based on data from HY-1C, which was launched in September 2018 in China, carrying Coastal Zone Imager (CZI) and Chinese Ocean Color and Temperature Scanner (COCTS) on it for offshore observation. A new SSC retrieved model was established based on the relationship between in situ SSC and the reflectance in red and near infrared bands of CZI image. Fifteen CZI images obtained from October to December 2019 were applied to retrieve SSC in Zhoushan coastal waters. The results show that SSC in study area is 100–1600 mg·L−1. The SSC near islands changes obviously. Upstream of the islands, SSC is lower than downstream. During the flood and ebb, when the current passes through the islands, circumfluence will appear, under certain geophysical factors, generating Karman vortex streets downstream of the islands. The sediments were stirred by the fast speed current at the outer side of vortex street to the sea surface inducing higher SSC at the outer side of the vortex street, while the central sediments of the vortex street were lower. In the direction of ocean currents, the SSC of the vortex street downstream of islands is changing regularly, i.e., increasing, then decreasing and increasing again and then decreasing in a snaking vortex street whose length downstream is between 1000 and 8000 m long.

Sign in / Sign up

Export Citation Format

Share Document