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2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Qiong Chen ◽  
Deshan Cui ◽  
Yu Chen ◽  
Xianyu Tao ◽  
Wei Xiang

Earthquakes or cyclic loadings cause significant changes in the strength characteristics of soil. These changes, especially for sliding zone soil, can lead to catastrophic landslides. Taking into account this characteristic, this paper investigates the effects of prior cyclic loading on the consolidated undrained triaxial compression strength of sliding zone soil with the KTL triaxial automated system. Our experimental results indicate that the prior cyclic loading has a significant effect on the strength behaviour of saturated sliding zone soil. Under different confining pressures, cycle periods, and number of cycles, the samples exhibit the characteristics of strain-hardening. Deviatoric stress under cyclic loading condition is smaller than that with monotonic loading condition under different confining pressures, cycle periods, and number of cycles. As the confining pressure and cycle period increase, the failure stress ratio decreases. The axial strain exhibits a steep rise first and then stays stable under a cycle period of 90 s, while the axial strain shows a linear increase with an increase in the number of cycles under a cycle period of 10 s under confining pressures of 100 kPa and 400 kPa, respectively. The logarithmic relation correlates well with the failure stress ratio in the cyclic loading tests, which preliminary validates the applicability of logarithmic relation for sliding zone soil influenced by prior cyclic loading, providing a theoretical basis and guidance for the further understanding of strength characteristics of sliding zone soil.


Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5904
Author(s):  
Dunwen Liu ◽  
Haofei Chen ◽  
Yu Tang Tang ◽  
Chun Gong ◽  
Yinghua Jian ◽  
...  

Sulfate erosion is a major cause of concrete durability deteriorations, especially for the service tunnels that suffer sulfate erosion for a long time. Accurately predicting the concrete damage failure under sulfate erosion has been a challenging problem in the evaluation and maintenance of concrete structures. Here we design the dry–wet cycle test of service tunnel concrete under sulfate erosion and analyze the Elastic relative dynamic modulus (Erd) and mass under 35 times cycle periods. Then we develop an autoregressive integrated moving average (ARIMA) prediction model linking damage failure to Erd and mass. The results show that the deterioration of concrete first increased and then decreased with an extension of the dry–wet cycle period. Moreover, based on a finite set of training data, the proposed prediction approach shows high accuracy for the changes of concrete damage failure parameters in or out of the training dataset. The ARIMA method is proven to be feasible and efficient for predicting the concrete damage failure of service tunnels under sulfate erosion for a long time.


2021 ◽  
pp. 179-194
Author(s):  
I.O. Dumanskaya ◽  

The warming of the Arctic, especially intensified at the beginning of the XXI century, is accompanied by a significant decrease in the area of ice cover in the Arctic seas. The article shows the quantitative changes in the ice parameters of the Barents Sea, as well as factors affecting the formation of ice cover in recent years. In the twenty-first century the frequency of occurrence of mild winters has increased by 17%, the frequency of severe winters has decreased by 19%. Significantly increased the temperature at the meteorological station Malye Karmakuly, water temperature at transect "Kola Meridian", atmospheric and oceanic heat fluxes, and speed of sea currents on the Western border of the Barents sea. The duration of the ice period decreased by an average of 2–3 weeks, and the rate of reduction of ice cover was 7.2% for 10 years. This is the highest speed compared to other Arctic seas. The article shows that the variability of the ice cover of the Barents Sea and other parameters of the natural environment in the region has the cyclic character. Presumably, the cycle period is close to 84 years, which corresponds to the orbital period of Uranium. The minimum sea ice extent after 1935–1945 is expected in the period 2019–2029.


2021 ◽  
Vol 3 (2) ◽  
pp. 29-32
Author(s):  
Özgür Turan ◽  
Ersen Ertekin ◽  
Oghuz Abdullayev ◽  
Behram Kuh

Objective: In most of the gynecological studies conducted using the Shear Wave Elastography (SWE) method in the literature, the menstrual cycle period was not taken into account. Current study, we aimed to describe the sonoelastographic features of normal myometrium and ovaries in healthy women and to define their variability during the different phases of the menstrual cycle using the SWE method. Material and methods: All cases were selected from individuals between the ages of 24-31, with regular menstrual cycles and no systemic disease. Each case was called in, 1-5th, 12-16th, 21-24th day of their menstrual cycles and was evaluated by B-mode imaging and SWE in pelvic ultrasonography. The relationship of menstrual phases with uterine and ovarian elasticity was investigated by comparing all measurements made in different menstrual phases. Results: No statistically significant difference was observed between the volume of right and left ovaries in terms (p> 0.05). There was no statistically significant difference in terms of elastography measurements obtained from the uterus, right and left ovaries for each menstrual phase according to Bonferroni Correction (p> 0.0163). Conclusion: Although there was a slight decrease in myometrial SWE measurements in the follicular phase, there was no significant difference regarding the SWE measurements of uterus and ovaries in early follicular, peri-ovulatory, and luteal menstrual stages. Further studies with a large number of participants are needed to suggest whether gynecological studies planned to be carried out with the shear wave elastography method should be planned in a specific menstrual phase.


2021 ◽  
Author(s):  
Prajkta Shashikant Kallurkar ◽  
Maria Cristina Picardo ◽  
Yae Sugimura ◽  
Margaret A Saha ◽  
Gregory Douglas Conradi Smith ◽  
...  

Breathing depends on interneurons in the preBötzinger complex (preBötC) derived from Dbx1-expressing precursors. Here we investigate whether rhythm- and pattern-generating functions reside in discrete classes of Dbx1 preBötC neurons. In a slice model of breathing with ~5 s cycle period, putatively rhythmogenic Type-1 Dbx1 preBötC neurons activate 100-300 ms prior to Type-2 neurons, putatively specialized for output pattern, and 300-500 ms prior to the inspiratory motor output. We sequenced Type-1 and Type-2 transcriptomes and identified differential expression of 123 genes including ionotropic receptors (Gria3 and Gabra1) that may explain their preinspiratory activation profiles and Ca2+ signaling (Cracr2a, Sgk1) involved in inspiratory and sigh bursts. Surprisingly, neuropeptide receptors that influence breathing (e.g., μ-opioid and bombesin-like peptide receptors) were only sparsely expressed, which suggests that cognate peptides and opioid drugs exert their profound effects on a small fraction of the preBötC core. These data in the public domain help explain the neural origins of breathing.


2021 ◽  
Author(s):  
Dunwen Liu ◽  
Haofei Chen ◽  
Yu Tang ◽  
Gong Chun ◽  
Yinghua Jian ◽  
...  

Abstract Sulfate erosion is a major cause of concrete durability deteriorations, especially for the service tunnels which are in sulfate erosion for a long time. Accurately predicting the concrete damage failure under sulfate erosion has been a challenging problem in the evaluation and maintenance of concrete structures. Here we design the dry-wet cycle test of service tunnel concrete under sulfate erosion, and analyze the Elastic relative dynamic modulus(Erd) and mass under 35 times cycle periods. Then we develop an autoregressive integrated moving average (ARIMA) prediction model linking damage failure to Erd and mass. The results show that the deterioration of concrete first increased and then decreased with an extension of the dry–wet cycle period. Moreover, based on a finite set of training data, the proposed prediction approach shows high accuracy for the changes of concrete damage failure parameters in or out of the training dataset. The ARIMA method is proven to be feasible and efficient for predicting the concrete damage failure of service tunnel under sulfate erosion for a long time.


2021 ◽  
Vol 25 (5) ◽  
pp. 413-431
Author(s):  
Jolanta Tamošaitienė ◽  
Hadi Sarvari ◽  
Matteo Cristofaro ◽  
Daniel W. M. Chan

All buildings require Repair and Maintenance (R&M) in their life cycle period. However, if R&M activities are not carried out properly, deterioration will occur, service life of buildings will be reduced, and maintenance costs will increase. Hence, selecting the appropriate R&M methods is pivotal, especially for developing countries, such as Iran, which are featured by highly constrained resources. The present study aims to identify and prioritize the main criteria for selecting the suitable R&M methods for Commercial Buildings (CBs), which is considered as a profound challenge for the Architecture, Engineering and Construction/Facility Management (AEC/FM) industry. A total of 20 senior experts in the AEC/FM industry and CBs in Iran were invited to participate in a Delphi survey to solicit their perceptions and opinions on the selection criteria. The total number of individual criteria identified is 16, which are further divided into five categories: human resources, flexibility and technical capability, risks, cost of maintenance, together with facilities and technology. Then, the Fuzzy Analytic Hierarchy Process (FAHP) technique was applied to prioritize the identified criteria. Among the 5 main selection criteria, the cost of maintenance is the most important criterion for selecting appropriate R&M methods for CBs whereas the criterion of human resources (HR) was recognized as the least important.


2021 ◽  
pp. 27-50
Author(s):  
Alexandra Smolecová ◽  
Daniel Šárovec

This article aims to analyse changes of the Slovak party system from 1992 to the last parliamentary elections of 2020. These elections were the eighth elections in the history of independent Slovakia. There are discussions about stability or instability of individual development stages of the party system. In the article, Attention is paid to changes in the distribution of forces within the development of the party system. In political science, various methods are used to measure the party system’s dynamics to determine the intensity of changes and the trends arising from them. This analysis is based on election results in each electoral cycle (period), which are being compared. Next part of the analysis is focused on the selected comparative indicators: Index of the Effective Number of Parties and Aggregation Index. These indices are chosen based on the criteria of classification of party systems. The results presented in the final part of the paper prove that several significant milestones in development of party system could be identified, as confirmed by the 2020 general elections – a major breakthrough in development trends.


Author(s):  
Ying Zhang ◽  
Ziqiang Ma ◽  
Mengjun Yao ◽  
Hui Gao ◽  
Xun Xu

This paper mainly studied the thermocapillary migration of deformable droplets induced by periodic temperature boundary under microgravity conditions. The Finite-Difference/Front-Tracking (FD/FT) Method was used to solve the Navier-Stokes equation coupled with the energy equation, and the Continuum Surface Force (CSF) model was used to simplify the surface tension of the phase interface. The results showed that the maximum droplet migration velocity increased with the increase of temperature amplitude. And the droplet cycle period became shorter with the increase of temperature angular frequency. In the 1/4 cycle, the initial movement time of droplet decreased with the increase of temperature phase. If the phase was reversed, the initial movement direction of the droplet changed. With the increase of Reynolds number (Re), the droplet tended to maintain its motion inertia.


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