ON A VERY HIGH RATE SENSITIVITY OF CONCRETE FAILURE AT HIGH LOADING RATES AND IMPACT

2003 ◽  
pp. 1-27 ◽  
Author(s):  
Janusz R. KLEPACZKO
Keyword(s):  
Rate Sensitivity ◽  
High Rate ◽  
High Loading ◽  
Loading Rates ◽  
Concrete Failure ◽  
Very High

Inertial Effects on Void Growth in Porous Viscoplastic Materials

1995 ◽  
Vol 62 (3) ◽  
pp. 633-639 ◽  
Author(s):  
W. Tong ◽  
G. Ravichandran
Keyword(s):  
Void Growth ◽  
Constitutive Models ◽  
Rate Sensitivity ◽  
High Rate ◽  
Dynamic Crack ◽  
Inertial Effects ◽  
Loading Conditions ◽  
Viscoplastic Material ◽  
Dynamic Loading Conditions ◽  
Very High

The present work examines the inertial effects on void growth in viscoplastic materials which have been largely neglected in analyses of dynamic crack growth and spallation phenomena using existing continuum porous material models. The dynamic void growth in porous materials is investigated by analyzing the finite deformation of an elastic/viscoplastic spherical shell under intense hydrostatic tensile loading. Under typical dynamic loading conditions, inertia is found to have a strong stabilizing effect on void growth process and consequently to delay coalescence even when the high rate-sensitivity of materials at very high strain rates is taken into account. Effects of strain hardening and thermal softening are found to be relatively small. Approximate relations are suggested to incorporate inertial effects and rate sensitivity of matrix materials into the porous viscoplastic material constitutive models for dynamic ductile fracture analyses for certain loading conditions.

Long-term operation of high rate algal ponds for the bioremediation of piggery wastewaters at high loading rates

2009 ◽  
Vol 100 (19) ◽  
pp. 4332-4339 ◽  
Author(s):  
Ignacio de Godos ◽  
Saúl Blanco ◽  
Pedro A. García-Encina ◽  
Eloy Becares ◽  
Raúl Muñoz
Keyword(s):  
High Rate ◽  
High Loading ◽  
Term Operation ◽  
High Rate Algal Ponds ◽  
Loading Rates

Relations between carbon removal rates, biofilm size and density of a novel anaerobic reactor: the inverse turbulent bed

2000 ◽  
Vol 41 (4-5) ◽  
pp. 253-260 ◽  
Author(s):  
P. Buffière ◽  
R. Moletta
Keyword(s):  
Removal Rate ◽  
Removal Rates ◽  
Carbon Removal ◽  
Biofilm Growth ◽  
Loading Rates ◽  
Biomass Activity ◽  
High Turbulence ◽  
The One ◽  
High Level ◽  
Very High

An anaerobic inverse turbulent bed, in which the biogas only ensures fluidisation of floating carrier particles, was investigated for carbon removal kinetics and for biofilm growth and detachment. The range of operation of the reactor was kept within 5 and 30 kgCOD· m−3· d−1, with Hydraulic Retention Times between 0.28 and 1 day. The carbon removal efficiency remained between 70 and 85%. Biofilm size were rather low (between 5 and 30 μm) while biofilm density reached very high values (over 80 kgVS· m−3). The biofilm size and density varied with increasing carbon removal rates with opposite trends; as biofilm size increases, its density decreases. On the one hand, biomass activity within the reactor was kept at a high level, (between 0.23 and 0.75 kgTOC· kgVS· d−1, i.e. between 0.6 and 1.85 kgCOD·kgVS · d−1).This result indicates that high turbulence and shear may favour growth of thin, dense and active biofilms. It is thus an interesting tool for biomass control. On the other hand, volatile solid detachment increases quasi linearly with carbon removal rate and the total amount of solid in the reactor levels off at high OLR. This means that detachment could be a limit of the process at higher organic loading rates.

Promoting sludge quantity and activity results in high loading rates in Anammox UBF

2010 ◽  
Vol 101 (8) ◽  
pp. 2700-2705 ◽  
Author(s):  
Jianwei Chen ◽  
Ping Zheng ◽  
Yi Yu ◽  
Chongjian Tang ◽  
Qaisar Mahmood
Keyword(s):  
High Loading ◽  
Loading Rates

Very high loading oxidized copper supported on ceria to catalyze the water-gas shift reaction

2021 ◽  
Author(s):  
Wen-Zhu Yu ◽  
Wei-Wei Wang ◽  
Chao Ma ◽  
Shan-Qing Li ◽  
Ke Wu ◽  
...  
Keyword(s):  
Water Gas Shift ◽  
High Loading ◽  
Water Gas Shift Reaction ◽  
Shift Reaction ◽  
Water Gas ◽  
Very High

Tilapia rearing with high rate algal pond effluent: ammonia surface loading rates and stocking densities effects

2018 ◽  
Vol 78 (1) ◽  
pp. 49-56
Author(s):  
I. A. Sánchez ◽  
R. K. X. Bastos ◽  
E. A. T. Lana
Keyword(s):  
Weight Gain ◽  
Oxygen Demand ◽  
Pilot Scale ◽  
Ammonia Nitrogen ◽  
High Rate ◽  
Surface Loading ◽  
Loading Rates ◽  
Total Weight Gain ◽  
Low Weight ◽  
Total Ammonia

Abstract In two pilot-scale experiments, fingerlings and juvenile of tilapia were reared in high rate algal pond (HRAP) effluent. The combination of three different total ammonia nitrogen (TAN) surface loading rates (SLR1 = 0.6, SLR2 = 1.2; SLR3 = 2.4 kg TAN·ha−1·d−1) and two fish stocking densities (D1 = 4 and D2 = 8 fish per tank) was evaluated during two 12-week experiments. Fingerlings total weight gain varied from 4.9 to 18.9 g, with the highest value (equivalent to 0.225 g·d−1) being recorded in SLR2-D1 treatment; however, high mortality (up to 67%) was recorded, probably due to sensitivity to ammonia and wide daily temperature variations. At lower water temperatures, juvenile tilapia showed no mortality, but very low weight gain. The fish rearing tanks worked as wastewater polishing units, adding the following approximate average removal figures on top of those achieved at the HRAP: 63% of total Kjeldahl nitrogen; 54% of ammonia nitrogen; 42% of total phosphorus; 37% of chemical oxygen demand; 1.1 log units of Escherichia coli.

Determination of Nitrogen and Phosphorus Partitioning within Components of the Biomass in a High Rate Algal Pond: Significance for the Coastal Environment of the Treated Effluent Discharge

1992 ◽  
Vol 25 (12) ◽  
pp. 207-214 ◽  
Author(s):  
N. J. Cromar ◽  
N. J. Martin ◽  
N. Christofi ◽  
P. A. Read ◽  
H. J. Fallowfield
Keyword(s):  
Dry Matter ◽  
Coastal Environment ◽  
High Rate ◽  
Nutrient Input ◽  
Nitrogen And Phosphorus ◽  
Loading Rates ◽  
Effective Strategies ◽  
Treated Effluent ◽  
Algae And Bacteria

Two High-Rate Algal Ponds were operated over residence times of 4 and 6 days respectively, at three COD loading rates equivalent to 600, 350 and 100 kg ha−1d−1 from early September to late October 1991. Samples of pond N and P feed were analysed to obtain nutrient input values to the system. Pond filtrates were also analysed for soluble nutrients. The pond biomass was separated into constituent components of algae and bacteria. Following separation, the discrete fractions were analysed for dry matter, chlorophyll content, and paniculate carbon, hydrogen, nitrogen and phosphorus. Nitrogen and phosphorus balances were then calculated which were used to partition the nutrients into soluble and paniculate phases, and to further separate the paniculate phase into algal and bacterial components. The partitioning of these nutrients, responsible for eutrophication, enables the calculation of removal rates of N and P from the pond systems and makes possible more effective strategies for the removal of the nutrient-rich biomass from receiving water bodies.

Pond walls: inclined planes to improve pathogen removal in pond systems for wastewater treatment?

2018 ◽  
Vol 78 (1) ◽  
pp. 31-36 ◽  
Author(s):  
A. L. Hawley ◽  
H. J. Fallowfield
Keyword(s):  
Wastewater Treatment ◽  
Prolonged Exposure ◽  
Tap Water ◽  
Bulk Water ◽  
High Rate ◽  
Pathogen Removal ◽  
Slope Length ◽  
Loading Rates ◽  
Surface Areas ◽  
Inclined Planes

Abstract Attenuation of sunlight in wastewater treatment ponds reduces the depth of the water exposed to disinfecting irradiances. Shallow pond depth with paddlewheel rotation increases exposure of pathogens to sunlight in high rate algal ponds. Generation of thin films, using pond walls as inclined planes, may increase inactivation of pathogens by increasing sunlight exposure. The performance of a laboratory based model system incorporating an inclined plane (IP) was evaluated. F-RNA bacteriophage, in tap water or wastewater, was exposed to sunlight only on the IP with the bulk water incubated in the dark. MS2 inactivation was significantly higher when the IP was present (P < 0.05) with a 63% increase observed. Prolonged exposure increased MS2 die-off irrespective of IP presence. Versatility of the IP was also demonstrated with faster inactivation observed in both optically clear tap water and wastewaters. IPs of different surface areas produced similar inactivation rates when operated at similar hydraulic loading rates regardless of slope length.

Sign in / Sign up

Export Citation Format

Share Document