scholarly journals ELBE TIDAL MODEL WITH MOVABLE BED

1972 ◽  
Vol 1 (13) ◽  
pp. 137 ◽  
Author(s):  
Hans Vollmers ◽  
Egon Giese
Keyword(s):  
Morphological Changes ◽  
Fixed Bed ◽  
Solid Material ◽  
Test Results ◽  
Tidal Model ◽  
Vertical Scale ◽  
Tidal Estuaries ◽  
The Elbe River ◽  
Sea Area ◽  
Movable Bed

The Bundesanstalt filr Wasserbau (BAW) was charged to investigate an estuary tidal model of the Elbe-river (North Sea). The model, fitted with a movable bed, serves for special research with regard to suitable actions for the enlargement and maintenance of the main navigable channel in the sea area. Because in tidal estuaries the interaction of fluid and solid material is extremely unknown, the investigation was undertaken to find out the arising morphological changes, only caused by tidal currents, considering structure or dredging works present or planned in prototype. The procedure seems advantageous and a better way as speculative interpretations of sediment movements, derived from flow velocities in a fixed bed model. The horizontal scale of the model is 1:800, the vertical scale 1:100. After basic considerations as similarity, hydrology, morphology, respectively, specifications of the modelling technique are given and finally some test results are discussed.

scholarly journals FIELD AND MODEL STUDIES FOR VISAKHAPATNAM HARBOR

1974 ◽  
Vol 1 (14) ◽  
pp. 88
Author(s):  
Simon Ince ◽  
W.W. Jamieson
Keyword(s):  
Monsoon Season ◽  
Fixed Bed ◽  
Northeast Monsoon ◽  
Shore Protection ◽  
Littoral Drift ◽  
Model Studies ◽  
Vertical Scale ◽  
Sand Trap ◽  
Trap Location ◽  
Movable Bed

Model studies and analysis of oceanographic and littoral drift data were undertaken to advise Howe India (Private) Ltd. on littoral drift, siltation and shore erosion problems to be encountered during and after the construction of Visakhapatnam Outer Harbor Project. Distorted fixed-bed and movable-bed models with a horizontal scale of 1:300 and a vertical scale of 1:80 were calibrated to reproduce the integrated net effect of an average southwest and northeast monsoon season. Experiments were conducted to assess and predict seasonal changes resulting from the construction of the system of breakwaters under normal and extreme conditions. Recommendations were made concerning breakwater and sand trap location, shore protection, dredging and disposal of dredged material.

scholarly journals HORIZONTAL DIFFUSION IN A TIDAL MODEL

1974 ◽  
Vol 1 (14) ◽  
pp. 139
Author(s):  
Haruo Higuchi ◽  
Tetsuo Yanagi
Keyword(s):  
Dimensional Analysis ◽  
Tidal Current ◽  
Hydraulic Model ◽  
Residual Flow ◽  
Tidal Model ◽  
Horizontal Diffusion ◽  
Vertical Scale ◽  
Tide And Tidal Current ◽  
Sea Area ◽  
Shallow Bay

The effect of the tidal residual flow on the horizontal diffusion in a shallow tidal bay is investigated through a hydraulic model experiment, for which Mikawa Bay in central Japan was used as a prototype. A hydraulic model of about 20 x 30 m including Mikawa Bay and neighboring sea area, with a horizontal and vertical scale of 1/2000 and 1/160 respectively, was used, and a semi-diurnal tide was provided for it. Experiments nave shown that tide and tidal current are well reproduced in the model. The tidal locus does not close, that means the existence of the residual flow. The distribution of the concentration of the dye, which is discharged from the bay bottom, corresponds to the pattern of the residual flow. The diffusion coefficient in the bay obtained through one dimensional analysis is the order of 10' cm2/sec and that through two dimensional analysis is less by one order and the dispersion coefficient becomes 105 cm2/sec. It is concluded that the dispersion due to the residual flow plays more important role on the distribution of the material in the shallow bay, as Mikawa Bay, than the diffusion due to the tidal current itself.

scholarly journals Laboratory Study of the Ultraviolet Radiation Effect on an HDPE Geomembrane

Membranes ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 390
Author(s):  
Fernando Luiz Lavoie ◽  
Marcelo Kobelnik ◽  
Clever Aparecido Valentin ◽  
Érica Fernanda da Silva Tirelli ◽  
Maria de Lurdes Lopes ◽  
...  
Keyword(s):  
Ultraviolet Radiation ◽  
Morphological Changes ◽  
Field Performance ◽  
Melt Flow Index ◽  
Flow Index ◽  
Test Results ◽  
Upward Trend ◽  
Scanning Calorimetry ◽  
Ultraviolet Exposure ◽  
Brittle Behavior

High-density polyethylene (HDPE) geomembranes are polymeric geosynthetic materials usually applied as a liner in environmental facilities due to their good mechanical properties, good welding conditions, and excellent chemical resistance. A geomembrane’s field performance is affected by different conditions and exposures, including ultraviolet radiation, thermal and oxidative exposure, and chemical contact. This article presents an experimental study with a 1.0 mm-thick HDPE virgin geomembrane exposed by the Xenon arc weatherometer for 2160 h and the ultraviolet fluorescent weatherometer for 8760 h to understand the geomembrane’s behavior under ultraviolet exposure. The evaluation was performed using the melt flow index (MFI) test, oxidative-induction time (OIT) tests, tensile test, differential scanning calorimetry (DSC) analysis, and Fourier transform infrared spectroscopy (FTIR) analysis. The sample exposed in the Xenon arc equipment showed a tendency to increase the MFI values during the exposure time. This upward trend may indicate morphological changes in the polymer. The tensile behavior analysis showed a tendency of the sample to lose ductility, without showing brittle behavior. The samples’ OIT test results under both device exposures showed faster antioxidant depletion for the standard OIT test than the high-pressure OIT test. The DSC and FTIR analyses did not demonstrate the polymer’s changes.

scholarly journals UNDERWATER MOUND FOR THE PROTECTION OF DURBAN'S BEACHES

1970 ◽  
Vol 1 (12) ◽  
pp. 62 ◽  
Author(s):  
J.A. Zwaborn ◽  
G.A.W. Fromme ◽  
J.B. FitzPatrick
Keyword(s):  
Settling Velocity ◽  
Scale Effects ◽  
Similarity Criterion ◽  
Test Results ◽  
Beach Profile ◽  
Reasonable Degree ◽  
Model Predictions ◽  
Profile Changes ◽  
High Degree ◽  
Movable Bed

The construction of an underwater mound of sand for the protection and improvement of Durban's beaches has been recommended on the basis of intensive investigations These investigations included prototype measurements of beach changes as related to recorded sea conditions, basic scaling tests in which these beach changes were reproduced to scale in movable bed models and tests of the proposed underwater mound in models, using different scales in order to eliminate possible scale effects The test results showed that, provided the shear-settling velocity similarity criterion is satisfied, beach changes can be reproduced in a movable bed model to a reasonable degree of accuracy Optimum dimensions for the cross section of the mound were determined on the basis of the criterion for erosive and non-erosive wave conditions which was derived from the prototype beach profile changes and confirmed by model tests The resulting dimensions are a mound of sand about 4 5 km long, about 1 200 m offshore, reaching to 7 3 m below LWOST, with side slopes of 1 in 25 and a crest width of 61 m 3 3 Of the total quantity required (8 000 000 m ) some 2 500 000 m of sand, available from harbour dredging works in Durban Bay, had been dumped by May, 1970 Model predictions on mound stability and beach improvements were confirmed to a high degree of accuracy by the full scale events.

scholarly journals The influence of large wood and rootwad on flow patterns and bed morphology in a moving bed channel

2018 ◽  
Vol 40 ◽  
pp. 02044
Author(s):  
Su-Chin Chen ◽  
Min-Chih Liang ◽  
Samkele Tfwala
Keyword(s):  
Field Experiments ◽  
Morphological Changes ◽  
Fixed Bed ◽  
Flow Patterns ◽  
Large Wood ◽  
River Channels ◽  
Moving Bed ◽  
Bed Topography ◽  
Bed Elevation ◽  
Elevation Changes

Studying large wood in river channels can help gain insight on their form and processes. Over the preceding decade, laboratory and field experiments have been used to explain wood dynamics, flow patterns and sediment transport. Moreover, field experiments are sparse, while laboratory experiments have focused mostly on fixed bed to capture their entrainment. To enhance our scientific understanding on logs of different morphology, this study designed an experimental flume to investigate the effects of log presence on flow and bed topography in a moving bed channel. Two log configurations were used, with and without rootwad. Wood pieces had a length of 0.2 m, diameter 0.05 m and a density of approximately 760 kg/m3. Rootwad were simulated by joining 0.06 m wood pieces, having a diameter of 0.02 m to the base of the log pieces at an angle of 30°. The experiments were carried out in a 4 m long flume, 0.6 m width and 0.6 m deep, and having a slope of 0.001. The experimental bed zone was paved with uniform sand, d50 = 0.750 mm, of 0.1 m thickness. Flow in the channel was set such that it was below the critical flow for wood entrainment, and it ranged between 0.0015 to 0.005 m3/s. Three different orientations of the log were considered, namely parallel, oblique and transverse to flow. Bed evolution was monitored using a camera and a laser mounted on a moving motor frame. This research shows that log orientation and the presence of rootwad dictate bed elevation changes and stability of single wood pieces. In addition, the contrast of morphological changes caused by the presence of abundant wood in a moving bed is crucial in determining large wood appropriate for river restoration. Our study provokes fascinating questions for future investigations.

Shear Strength of BC-Soil Admixed with Lime and Bio-Enzyme

2019 ◽  
Vol 969 ◽  
pp. 327-334
Author(s):  
C. Jairaj ◽  
M.T. Prathap Kumar ◽  
H. Muralidhara
Keyword(s):  
Shear Strength ◽  
Soil Stabilization ◽  
Morphological Changes ◽  
Ground Improvement ◽  
High Strength ◽  
Sem Analysis ◽  
Dry Density ◽  
Test Results ◽  
Maximum Dry Density ◽  
Lime Content

This BC Soil are expansive in nature and are problematic because of low shear strength and high compressibility. Review of literatures have proven that addition of lime imparts high strength with a corresponding reduction in swell of BC soils. In addition, Bio-enzymes have also been found to play a key role as activators in improving the characteristics of clayey soils such as BC soil. Development and use of non-traditional ground improvement techniques such as bio-enzymes in combination with lime for soil stabilization helps to reduce the cost and the detrimental effects on the soil environment. In the present study lime and bio-enzymes were used as soil stabilizing agents. Compaction test results on BC soil admixed with different percent of lime indicated that 3% addition lime gives higher maximum dry density of 17kN/m3 with OMC of 21% compare to other addition of lime percentages. Keeping 3% of lime as optimum lime content(OLC), BC Soil was admixed with different dosages of Bio-enzymes 25ml/m3, 50ml/m3, 100 ml/m3,150ml/m3, and 200ml/m3 along with OLC was tested for compaction and unconfined compressive strength(UCC). Further UCC test was carried out for different curing period of 0, 7, 15, 30, and 60 Days to analyse the long term effect of BC soil admixed with bio-enzymes with and without lime content. Morphological and chemical analysis was done by using XRD and SEM analysis, from all the test results it was found that 3%OLC + 75ml/m3 of bio-enzymes for 7 day of curing gives higher UCC of 450 kPa. From the SEM it was found that better bond between particles found to develop in bio-enzyme+ lime admixed BC soil in comparison with lime alone admixed BC soil. XRD studies indicated morphological changes in crystallinity and structure of stabilized BC soil in comparison to BC soil alone.

scholarly journals ANALYSIS OF OPEN-CHANNEL CONFLUENCE FLOW HAVING DIFFERENT STEEP SLOPES IN FIXED BED AND MOVABLE BED

2007 ◽  
Vol 51 ◽  
pp. 823-828
Author(s):  
Takashi DEGUCHI ◽  
Ichiro FUJITA ◽  
Ryota TSUBAKI ◽  
Masashi OZONO
Keyword(s):  
Open Channel ◽  
Fixed Bed ◽  
Steep Slopes ◽  
Movable Bed ◽  
Channel Confluence

scholarly journals EXPERIENCE WITH MOVABLE BED TIDAL MODELS

1974 ◽  
Vol 1 (14) ◽  
pp. 61
Author(s):  
E. Giese ◽  
H. Harten ◽  
H. Vollmers
Keyword(s):  
Sediment Transport ◽  
Morphological Changes ◽  
Transport Processes ◽  
Similarity Criteria ◽  
Research Institutes ◽  
Special Cases ◽  
Similarity Relationships ◽  
Movable Bed ◽  
Insufficient Knowledge ◽  
Sea Coast

A particular problem, of those arising in the economic development of estuary regions, concerns the maintenance and enlargement of navigation channels. The sediment transport plays an important role in connection with this problem. .Though the hydrodynamical processes are today, with the help of mathematical procedures, fairly exactly grasped, there is still insufficient knowledge about the related transport processes, the formation of ripples and dunes and of longterm periodical morphological changes. Nevertheless, the engineer wants information about sediment transport for his planning. A well-known aid is the movable bed hydraulic model, which has been technically developed to simulate the natural fluid-sediment interaction. Such models are not yet standard in hydraulic research institutes and. furthermore, they are not easy to handle. This is probably due to a lack of suitable similarity criteria for insuring valid experimental results. However, there exist recently developed somewhat compromised similarity relationships, which can be used for distorted movable bed tidal models. The experience gained with the movable bed. model Elbe I at the Bundesanstalt fur Wasserbau (BAW) in Hamburg provides an incentive for investigating special cases in other large tidal models of the German North-Sea coast. These models are presented in Fig. 1.

scholarly journals Reliable and Sophisticated Techniques to Evaluate LDPE Degraded Compounds by Streptomyces werraensis SDJM

2021 ◽  
Vol 20 (3) ◽  
Author(s):  
N. Deepika ◽  
R. Jaya Madhuri
Keyword(s):  
Weight Loss ◽  
Structural Changes ◽  
Morphological Changes ◽  
Field Trials ◽  
Sem Analysis ◽  
Modern World ◽  
Ftir Analysis ◽  
Test Results ◽  
Laboratory Test Results ◽  
The World

The modern world in the present era made life miserable due to extensive usage of plastic. Low-density polyethylene (LDPE) is widely consumed in every part of the world starting from baby products to garbage bags. Humans and animals are affected due to the usage and disposal of LDPE in the environment. To safeguard the environment from deleterious effects, biodegradation of LDPE was studied by isolating a potent Streptomyces werraensis SDJM strain from garbage soil. The degradation assessment was performed to identify the LDPE degraded compounds such as octane, decane, tetracosane, hexacosane, dotriacontene, tetratiacontene, tridecone, tetracontane, and pentacosane, using a sophisticated technique - liquid chromatography-mass spectroscopy (LCMS). The end product of LDPE biodegradation, carbon dioxide was measured by the GCMS-SPME technique. Field trials in garbage soil for a period of three months reveal 71.26% weight loss compared to laboratory test results where the weight loss was 60.05%. The morphological changes and structural changes of the polymer in fields were assessed by SEM analysis and FTIR analysis after one month of incubation. The test results in field trials were promising and convincing to overcome the LDPE pollution in presence of S.werraensis SDJM strain.

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