Long-term budget requirements for the replacement of bridges and hydraulic structures

2015 ◽  
pp. 969-974
Author(s):  
R Nicolai ◽  
H Klatter
Keyword(s):  
Hydraulic Structures

scholarly journals Mechanical Modification of Nanomaterials on Fully Saturated Concrete in Groundwater Reservoir Under Long-Term Water Immersion

2021 ◽  
Vol 8 ◽  
Author(s):  
XianJie Hao ◽  
Yingnan Wei ◽  
Zeyu Chen ◽  
Honglan Zhang ◽  
Yifan Niu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Water Immersion ◽  
Deformation Modulus ◽  
Concrete Sample ◽  
Hydraulic Structures ◽  
Safe Operation ◽  
Modifying Effect ◽  
Series Of Experiments ◽  
Saturated Concrete

With the increasing number of hydraulic structures in service, many scholars have investigated the performance of saturated concrete, however, there are few studies on the influences of different contents and types of nanomaterials on the performance of fully saturated concrete. In this paper, a series of experiments on concrete with different contents of nano SiO2, nano Al2O3 and nano TiO2 are performed, such as electron mirror scanning, uniaxial compression, acoustic emission, etc., and the microstructure, mechanical properties of samples are compared and analyzed. The results show that: 1) By the addition of various kinds of nanomaterials to saturated concrete, the microstructure of saturated concrete is significantly improved, and the compactness and integrity of the slurry are improved 2) The mechanical properties of saturated concrete are significantly improved by the addition of 3 wt% nanomaterials. And the compressive strength of the saturated concrete sample containing 3 wt% nano-Al2O3 is the largest and the deformation modulus of the saturated concrete sample containing 6 wt% nano-Al2O3 is the largest. 3) Compared with dry concrete, when the concrete is saturated, the modifying effect of nanomaterials on the mechanical properties of concrete is weakened. The results of this study have important guiding significance for the study of the nano-modification and the safe operation of hydraulic structures.

scholarly journals Long Term Historic Changes in the Flow of Lesser Zab River, Iraq

Hydrology ◽  
2019 ◽  
Vol 6 (1) ◽  
pp. 22 ◽  
Author(s):  
Rawshan Ali ◽  
Arez Ismael ◽  
Arien Heryansyah ◽  
Nadeem Nawaz
Keyword(s):  
Climate Change ◽  
Scientific Community ◽  
River Flow ◽  
Kendall Test ◽  
Hydraulic Structures ◽  
Trend Test ◽  
Adaptation Measures ◽  
Sen’S Slope ◽  
Water Scarce

The assessment of trends in river flows has become of interest to the scientific community in order to understand the changing characteristics of flow due to climate change. In this study, the trends in river flow of Dukan Dam located in the northern part of Iraq were assessed. The assessment was carried out for the period 1964 to 2013 using Sen’s slope and the Mann–Kendall test. Sen’s slope was used to assess the magnitude of change while the Mann–Kendall trend test was used to confirm the significance of trends. The results of the study showed that there was a decreasing trend in river flow both annually and for all individual months. The highest decreasing trend of −5.08846 m3/month was noticed in April, while the lowest change of −1.06022 m3/month was noticed in November. The annual flow also showed a significant decrease at a rate of −1.912 m3/year at a 95% level of confidence. Additionally, the findings of the study also confirmed that a decrease in precipitation and the construction of hydraulic structures reduced the flow in the river. The findings of the study suggest that decreasing trends may cause a water-scarce situation in the future if proper adaptation measures are not taken.

Effectiveness of Polypropylene Fiber Reinforced Concrete in Enhancement of Long-Term Durability of Hydraulic Structures

2018 ◽  
Vol 923 ◽  
pp. 125-129
Author(s):  
Asad Zia ◽  
Majid Ali
Keyword(s):  
Reinforced Concrete ◽  
Water Absorption ◽  
Polypropylene Fiber ◽  
Linear Shrinkage ◽  
Fiber Reinforced Concrete ◽  
Hydraulic Structures ◽  
Polypropylene Fibers ◽  
Fiber Reinforced ◽  
Polypropylene Fiber Reinforced Concrete

The long-term durability of concrete hydraulic structures can be improved by controlling their rate of water absorption and linear shrinkage. Incorporation of fibers in concrete composites has the potential to improve these properties of concrete. Artificial fibers are commonly used in concrete due to its durable nature for long serviceable life. So, the overall aim of this research program is to study the effectiveness of artificial fibers for improvement of long-term durability of concrete hydraulic structures. To start with, polypropylene fibers are considered. The polypropylene fibers (PPF) have the unique properties of chemically inertness and low cost raw materials. The pilot study presents the experimental evaluation of water absorption and linear shrinkage of polypropylene fiber reinforced concrete (PPFRC) in comparison to that of plain concrete (PC). The mix design proportion of 1:3:1.5:0.7 (cement:sand:aggregates:water) is used in preparation of PC and PPFRC. For PPFRC, the fiber length of 50 mm and content of 5% by mass of cement are added. All tests are performed as per ASTM standard. Discussions on the considered properties of PC and PPFRC are made. As per expected outcomes PPFRC showed less water absorption and less linear shrinkage as compared to that of PC. Because of this possible attribute, the PPFRC can be used in hydraulic structures.

scholarly journals Mechanical Parameter Identification of Hydraulic Engineering with the Improved Deep Q-Network Algorithm

2020 ◽  
Vol 2020 ◽  
pp. 1-20
Author(s):  
Wei Ji ◽  
Xiaoqing Liu ◽  
Huijun Qi ◽  
Xunnan Liu ◽  
Chaoning Lin ◽  
...  
Keyword(s):  
Neural Network ◽  
Environmental Factors ◽  
Surrogate Model ◽  
Deep Neural Network ◽  
Hydraulic Structures ◽  
Mechanical Parameters ◽  
Operating Period ◽  
Accurate Analysis ◽  
Inversion Analysis

During the long-term operating period, the mechanical parameters of hydraulic structures and foundation deteriorated gradually because of the environmental factors. In order to evaluate the overall safety and durability, these parameters should be calculated by some accurate analysis methods, which are hindered by slow computational efficiency and optimization performance. The improved deep Q-network (DQN) algorithm combined with the deep neural network (DNN) surrogate model was proposed in this paper to ameliorate the above problems. Through the study cases of different zoning in the dam body and the actual engineering foundation, it is shown that the improved DQN algorithm has a good application effect on inversion analysis of material mechanical parameters in this paper.

scholarly journals Subsidence deformations of the foundations of hydraulic structures

2021 ◽  
Vol 264 ◽  
pp. 03069
Author(s):  
Rustam Хujakulov ◽  
M Zaripov ◽  
U Normurodov
Keyword(s):  
Stressed State ◽  
Strain State ◽  
Stress Redistribution ◽  
Hydraulic Structures ◽  
Physical Processes ◽  
Irrigation Systems ◽  
Stress Strain ◽  
Regulatory Documents ◽  
Stress Strain State

One of the most important tasks in designing and constructing reclamation network structures on loess subsidence soils is to ensure their long-term trouble-free operation. The improvement of methods for the design of hydraulic structures on subsidence foundations requires further study of very complex physical processes occurring in the foundations of structures during their construction and operation. This is confirmed by the fact that even if all the requirements and recommendations of regulatory documents for the design of irrigation systems on subsiding soils are observed, the deformations of the foundations of structures often significantly exceed the calculated ones, which can cause a loss of serviceability of irrigation structures. This determines the need for further study peculiarities of interaction of irrigation structures with their subsidence bases. This article is devoted to this problem, in particular, to the study of the influence of stress redistribution in wetted subsidence foundations of hydraulic structures on the stressed state of their elements and the stress-strain state of loess subsidence foundations on the models of float bets of hydraulic structures in the Karshi steppe.

Evaluating the Long-Term Durability of Lime Treatment in Hydraulic Structures: Case Study on the Friant-Kern Canal

2020 ◽  
Vol 2674 (6) ◽  
pp. 431-443 ◽  
Author(s):  
Pavan Akula ◽  
Narain Hariharan ◽  
Dallas N. Little ◽  
Didier Lesueur ◽  
Gontran Herrier
Keyword(s):  
Slope Failure ◽  
Fluorescence Analysis ◽  
Engineering Properties ◽  
Hydraulic Structures ◽  
Lime Treatment ◽  
Geochemical Model ◽  
Bureau Of Reclamation ◽  
Tenfold Increase ◽  
Geochemical Reactions

The slopes along the Friant-Kern Canal were last treated in the 1970s with 4% quick lime to mitigate issues related to slope failure caused by expansive Porterville soils. The immediate benefits of lime treatment were well documented by the Bureau of Reclamation. However, questions remain over the long-term durability of lime-treated materials. In this study, we compare the engineering properties and changes in the soil mineralogy of treated and untreated sections to establish the effectiveness of lime after more than 40 years of performance. A geochemical model was developed using the GEM-Selektor program to simulate the geochemical reactions in the soil-lime system and predict stable pozzolanic products. The experimental results show a reduction in the plasticity index from 23 to 6 after lime treatment together with a tenfold increase in strength. Lime addition lowers the risk of volumetric expansion and erosion in soils from moderately high to very low. Further, a pH increase from 6.30 to 8.90 in lime-treated sections indicates that lime treatment continues to be effective. X-ray fluorescence analysis shows the presence of Ca2+ ions in quantities similar to the initial treatment dosage indicating negligible leaching of lime. The geochemical model provides evidence of the formation of pozzolanic products in the soil-lime system which was validated using thermogravimetry analysis. The performance history of the Friant-Kern Canal together with the findings of this study affirm the long-term durability of lime treatment on this project and strengthens the case for using lime in the repair of hydraulic structures.

Therapy and prevention for mental health: What if mental diseases are mostly not brain disorders?

2019 ◽  
Vol 42 ◽  
Author(s):  
John P. A. Ioannidis
Keyword(s):  
Mental Health ◽  
Mental Disease ◽  
Brain Disorders ◽  
Social Stressors ◽  
Labor Education ◽  
Mental Diseases ◽  
Long Term Follow Up ◽  
Political Decisions

AbstractNeurobiology-based interventions for mental diseases and searches for useful biomarkers of treatment response have largely failed. Clinical trials should assess interventions related to environmental and social stressors, with long-term follow-up; social rather than biological endpoints; personalized outcomes; and suitable cluster, adaptive, and n-of-1 designs. Labor, education, financial, and other social/political decisions should be evaluated for their impacts on mental disease.

Conceptual short-term memory (CSTM) supports core claims of Christiansen and Chater

2016 ◽  
Vol 39 ◽  
Author(s):  
Mary C. Potter
Keyword(s):  
Working Memory ◽  
Rapid Serial Visual Presentation ◽  
Language Comprehension ◽  
Short Term Memory ◽  
Visual Presentation ◽  
Long Term Memory ◽  
Short Term ◽  
Term Memory ◽  
Use Of Knowledge

AbstractRapid serial visual presentation (RSVP) of words or pictured scenes provides evidence for a large-capacity conceptual short-term memory (CSTM) that momentarily provides rich associated material from long-term memory, permitting rapid chunking (Potter 1993; 2009; 2012). In perception of scenes as well as language comprehension, we make use of knowledge that briefly exceeds the supposed limits of working memory.

Brief summary of Kleť photographic search programme for minor planets

1999 ◽  
Vol 173 ◽  
pp. 189-192
Author(s):  
J. Tichá ◽  
M. Tichý ◽  
Z. Moravec
Keyword(s):  
Ccd Camera ◽  
Minor Planet ◽  
Minor Planets ◽  
Main Belt

AbstractA long-term photographic search programme for minor planets was begun at the Kleť Observatory at the end of seventies using a 0.63-m Maksutov telescope, but with insufficient respect for long-arc follow-up astrometry. More than two thousand provisional designations were given to new Kleť discoveries. Since 1993 targeted follow-up astrometry of Kleť candidates has been performed with a 0.57-m reflector equipped with a CCD camera, and reliable orbits for many previous Kleť discoveries have been determined. The photographic programme results in more than 350 numbered minor planets credited to Kleť, one of the world's most prolific discovery sites. Nearly 50 per cent of them were numbered as a consequence of CCD follow-up observations since 1994.This brief summary describes the results of this Kleť photographic minor planet survey between 1977 and 1996. The majority of the Kleť photographic discoveries are main belt asteroids, but two Amor type asteroids and one Trojan have been found.

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