Response of the ultra high performance concrete under dynamic compressive loading

Ultra high performance concrete is a modern cementitious material which exhibits excellent mechanical properties such as damage tolerance, fracture toughness and durability. These features make this materials suitable for wide range of applications where is the material subjected to different modes of loading and different loading rates.This paper deals with measurement of the Ultra high performance concrete reinforced with steel fibres in quasi-static compression mode of deformation and two elevated strain rates using split Hopkinson pressure bar. The results of the measurement show high increase of the mechanical properties with elevated strain rate

Prognostic impact of neck responders on conception rate of Czech Fleckvieh Simmental cows

Article Details: Received: 2020-10-25 | Accepted: 2020-11-27 | Available online: 2021-01-31https://doi.org/10.15414/afz.2021.24.mi-prap.58-61The climate in the Czech Republic is mild, transient between oceanic and continental, with a typical alternation of 4-year periods. The continental climate is characterized by high temperatures in summer and low temperatures in winter. During the extreme fluctuation of microclimatic conditions in the stable, there is also a change in individual reproductive indicators due to disruption of hormonal secretion, which further affects individual physiological processes, thus worsening conception or milder manifestations of heat, which we currently try to detect by neck responders and other modern systems.The experiment analyzed the effect of the average monthly temperature and humidity in the stable on the percentage of pregnant cows, in 2017 without the use of neck responders and in 2019, when all cows already had a neck responder. Monitoring was performed in 2017 and 2019 on the private farm GenAgro Říčany, a.s. (GPS 49 ° 12'32.319 "N, 16 ° 23'42.666" V). The values of average temperatures and relative humidity were calculated from 15-minute interval recordings of HOBO brand data loggers (Onset), which were placed in the stable, at the height at the withers of the cows without the possibility of influencing the measurements by the cows themselves. The object of monitoring was a herd of approximately 700 cows of Czech Fleckvieh Simmental various lactations. Data on the conception of cows were obtained both from the monthly reports of the breeding organization and from the data of the breeder.Thermal stress can have a long-lasting effect observable for weeks or months after the summer. This is also evidenced by the results of the work, which shows the worsening conception of cows, especially in late summer and autumn. At the same time, the results show a positive effect of the used neck responders, which help with the detection of heat and thus improve the reproduction of the whole herd.Keywords: Czech Fleckvieh Simmental, smart farming, neck responders, reproduction, heat stressReferencesBadinga, L., et al. (1985). Effects of climatic and management factors on conception rate of dairy cattle in subtropical environment. J Dairy Sci, 68, 78–85.Bertipaglia, E. C. A., et al. (2005). Fertility and hair coat characteristics of Holstein cows in a tropical environment. Anim Reprod, 2(3), 187–194.Bridges, P. J. et al. (2005). Elevated temperature (heat stress) in vitro reduces androstenedione and estradiol and increases progesterone secretion by follicular cells from bovine dominant follicles. Domestic Animal Endocrinology, 29, 508–522, https://doi.org/10.1016/j.domaniend.2005.02.017.Funnell, A. (2015). Robots and the future of agriculture.[cited 2020-10-15].  Available from:http://www.abc.net.au/radionational/programs/futuretense/a-swarmof-agbots/6968940Jelínek, P., Koudela, K. et al. (2003). Fyziologie hospodářských zvířat. Brno: Mendelova zemědělská a lesnická univerzita.Rensis, F. D., Scaramuzzi, R. . (2003). Heat stress and seasonal effects on reproduction in the dairy cow – a review. Theriogenology, 60,1139–1151, https://doi.org/10.1016/S0093-691X(03)00126-2.Schmitt, E. J. et al. (1996). Differential response of the luteal phase and fertility in cattle following ovulation of the first-wave follicle with human chorionic gonadotropin or an agonist of the gonadotropin-releasing hormone. J Anim Sci, 74, 1074–1083, DOI: 10.2527/1996.7451074xSchwab, K. (2016). The fourth industrial revolution. New York: Crown Business.Ustundag, A., Cevikcan, E. (2017). Industry 4.0: managing the digital transformation. New York: Springer Berlin Heidelberg.Velechovská, J. (2016). Monitoring přežvykování pro efektivnější chov. Chov [online]., 8. číslo 18–20 str. [cited 2020-10-15]. Available from:https://www.eurofarm.cz/sites/www.eurofarm.cz/files/u2018/08-2016-chov-priloha_str18-20-eurofarm.pdfWolfenson, D., Roth, Z., Meidan, R. (2000). Impaired reproduction in heat stressed: basic and applied aspects. Anim Reprod Sci, 60, 535–547, https://doi.org/10.1016/S0378-4320(00)00102-0

Gravitational Wave Emission from the Single-Degenerate Channel of Type Ia Supernovae

The thermonuclear explosion of a C/O white dwarf as a Type Ia supernova (SN Ia) generates a kinetic energy comparable to that released by a massive star during a SN II event. Current observations and theoretical models have established that SNe Ia are asymmetric, and therefore--like SNe II--potential sources of gravitational wave (GW) radiation. We perform the first detailed calculations of the GW emission for a SN Ia of any type within the single-degenerate channel. The gravitationally-confined detonation (GCD) mechanism predicts a strongly-polarized GW burst in the frequency band around 1 Hz. Third-generation spaceborne GW observatories currently in planning may be able to detect this predicted signal from SNe Ia at distances up to 1 Mpc. If observable, GWs may offer a direct probe into the first few seconds of the SNe Ia detonation.Comment: 8 pages, 4 figures, Accepted by Physical Review Letter

Manufactured caverns in carbonate rock

Disclosed is a process for manufacturing underground caverns suitable in one embodiment for storage of large volumes of gaseous or liquid materials. The method is an acid dissolution process that can be utilized to form caverns in carbonate rock formations. The caverns can be used to store large quantities of materials near transportation facilities or destination markets. The caverns can be used for storage of materials including fossil fuels, such as natural gas, refined products formed from fossil fuels, or waste materials, such as hazardous waste materials. The caverns can also be utilized for applications involving human access such as recreation or research. The method can also be utilized to form calcium chloride as a by-product of the cavern formation process

Response of the ultra high performance concrete under dynamic compressive loading

Ultra high performance concrete is a modern cementitious material which exhibits excellent mechanical properties such as damage tolerance, fracture toughness and durability. These features make this materials suitable for wide range of applications where is the material subjected to different modes of loading and different loading rates. This paper deals with measurement of the Ultra high performance concrete reinforced with steel fibres in quasi-static compression mode of deformation and two elevated strain rates using split Hopkinson pressure bar. The results of the measurement show high increase of the mechanical properties with elevated strain rate

Fracture Dissolution of Carbonate Rock: An Innovative Process for Gas Storage

The goal of the project is to develop and assess the feasibility and economic viability of an innovative concept that may lead to commercialization of new gas-storage capacity near major markets. The investigation involves a new approach to developing underground gas storage in carbonate rock, which is present near major markets in many areas of the United States. Because of the lack of conventional gas storage and the projected growth in demand for storage capacity, many of these areas are likely to experience shortfalls in gas deliverability. Since depleted gas reservoirs and salt formations are nearly non-existent in many areas, alternatives to conventional methods of gas storage are required. The need for improved methods of gas storage, particularly for ways to meet peak demand, is increasing. Gas-market conditions are driving the need for higher deliverability and more flexibility in injection/withdrawal cycling. In order to meet these needs, the project involves an innovative approach to developing underground storage capacity by creating caverns in carbonate rock formations by acid dissolution. The basic concept of the acid-dissolution method is to drill to depth, fracture the carbonate rock layer as needed, and then create a cavern using an aqueous acid to dissolve the carbonate rock. Assessing feasibility of the acid-dissolution method included a regional geologic investigation. Data were compiled and analyzed from carbonate formations in six states: Indiana, Ohio, Kentucky, West Virginia, Pennsylvania, and New York. To analyze the requirements for creating storage volume, the following aspects of the dissolution process were examined: weight and volume of rock to be dissolved; gas storage pressure, temperature, and volume at depth; rock solubility; and acid costs. Hydrochloric acid was determined to be the best acid to use because of low cost, high acid solubility, fast reaction rates with carbonate rock, and highly soluble products (calcium chloride) that allow for the easy removal of calcium waste from the well. Physical and chemical analysis of core samples taken from prospective geologic formations for the acid dissolution process confirmed that many of the limestone samples readily dissolved in concentrated hydrochloric acid. Further, some samples contained oily residues that may help to seal the walls of the final cavern structure. These results suggest that there exist carbonate rock formations well suited for the dissolution technology and that the presence of inert impurities had no noticeable effect on the dissolution rate for the carbonate rock. A sensitivity analysis was performed for characteristics of hydraulic fractures induced in carbonate formations to enhance the dissolution process. Multiple fracture simulations were conducted using modeling software that has a fully 3-D fracture geometry package. The simulations, which predict the distribution of fracture geometry and fracture conductivity, show that the stress difference between adjacent beds is the physical property of the formations that has the greatest influence on fracture characteristics by restricting vertical growth. The results indicate that by modifying the fracturing fluid, proppant type, or pumping rate, a fracture can be created with characteristics within a predictable range, which contributes to predicting the geometry of storage caverns created by acid dissolution of carbonate formations. A series of three-dimensional simulations of cavern formation were used to investigate three different configurations of the acid-dissolution process: (a) injection into an open borehole with production from that same borehole and no fracture; (b) injection into an open borehole with production from that same borehole, with an open fracture; and (c) injection into an open borehole connected by a fracture to an adjacent borehole from which the fluids are produced. The two-well configuration maximizes the overall mass transfer from the rock to the fluid, but it results in a complex cavern shape. Numerical simulations were performed to evaluate the ability of storage caverns produced by the acid-dissolution method to store natural gas. In addition, analyses were conducted to evaluate cavern stability during gas injection and withdrawal from storage caverns created in carbonate formations by the acid-dissolution method. The stability analyses were conducted using FLAC2D, a commercially available geotechnical analysis and design software. The analyses indicate that a tall cylindrical cavern with a domed roof and floor will be stable under the expected range of in situ and operational conditions. This result suggests that it should be feasible to avoid mechanical instabilities that could potentially diminish the effectiveness of the storage facility. The feasibility of using pressure transients measured at the ground surface was investigated as a means to evaluate (Abstract truncated

The right to statutory judge

Katedra občanského právaDepartment of Civil LawFaculty of LawPrávnická fakult