Implementation of innovative technologies for the improvement of concrete properties for freezing and thawing processes

For over a hundred years, concrete has been a well-known building material and is widely used in construction. Its properties have convinced construction engineers, architects, contractors and investors, which is why it is currently difficult to find a building completed without the use of this material. However, the influence of atmospheric conditions and other environmental influences means that over time they leave more and more visible signs of progressive destruction even on the best building material of the century. Taking into account the problems related to aeration and surface hydrophobization, the aim of the work was to demonstrate that by using an admixture in the form of an anionic bitumen emulsion and a superplasticizer based on polycarboxylate ethers, it is possible to obtain hard-to-wet concretes with a favorable porosity structure and increased resistance to environmental influences. For static calculations and dimensioning, an original calculation model of the pavement made of concrete with dispersed reinforcement in the form of fibers was used, which made it possible to eliminate the reinforcement in the form of bars. Laboratory tests with the use of concrete samples taken during concreting carried out after 28 days of maturation confirmed the high compressive strength.

Research on Body Type Correction of FINA Diving Difficulty Coefficient Based on Rigid Body System

In order to reduce the influence of athlete’s body shape on the difficulty coefficient of diving, a more reasonable calculation method of body shape correction coefficient is proposed based on the original calculation rules of diving difficulty coefficient. First, the composition of the original diving difficulty coefficient and influencing factors is analyzed and the relationship between the various structural parts is fully clarified. Second, a coupled nonrigid body dynamics model is established and a 2-body model is used to simulate complex diving actions, and it is concluded that diving time is positively correlated with body shape. Finally, the air movement part and the water entry part of diving are discussed separately, the calculation model of the difficulty coefficient of body shape correction is established, and the original difficulty coefficient is corrected. The results show that the difficulty coefficient of each movement is obviously increased. This effectively avoids the influence of body shape on the diving difficulty coefficient.

Аpplication of the mathematical model of human torso for modeling abbreval influence in wound ballistics

In the work, a review of scientific articles on the behavior of tissues and organs of the human body under local mechanical effects on it, as well as a description of the physico-mechanical properties of biological materials. The selection of mechanical behavior for each biological material as part of a mathematical model of the human torso was carried out, its finite element model was created, validation experiments were modeled using data presented in the literature. An original calculation model of a human torso with a tuned interaction of organs with each other was developed. Contact interaction parameters are determined. The developed computational model of a human torso was verified based on data from open sources for an experiment with mechanical action by a cylindrical impactor. An algorithm for processing pressure and acceleration graphs has been implemented in order to obtain tolerance curves. A specialized modular program has been created for the automated processing of calculation results and the output of the main results. 42 numerical tests were carried out simulating the entry of a steel ball into each of 21 zones for power engineers of 40 and 80 J. According to the results of the tests for each organ, pressure and acceleration tolerance curves were obtained, animations of the behavior of organs under shock were created, visualization of the pressure field propagation in organs was obtained torso.

Risk Estimate of Duodenoscope-Associated Infections in The Netherlands

Background: The likelihood of endoscopy-associated infections (EAIs) is often referenced from a paper published in 1993 by Kimmery et al1 in which a risk of 1 exogenous infection for every 1.8 million endoscopies (0.00006%) is proclaimed. Even though Ofstead et al2 pointed out in 2013 that this was at least an underestimation by 6-fold because of erroneous assumptions and mathematical errors, the original calculation is still often referred to. In the past decade, multiple outbreaks of multidrug-resistant microorganisms (MDROs) related to contaminated duodenoscopes have been reported worldwide. This leads to the assumption that the former risk calculation is indeed incorrect. Objective: We calculated the duodenoscope-associated infection (DAI) risk for the Dutch ERCP practice. Methods: We searched and consolidated all Dutch patients reported in the literature to have suffered from a clinical infection linked to a contaminated duodenoscope between 2008 and 2018. From a national database, the number of ERCPs performed per year in The Netherlands were retrieved. Actual numbers were available from 2012 to 2018. Numbers from 2008 to 2011 were estimated and assumed to be equal to 2012. Results: In 2008–2018, 3 MDRO outbreaks in Dutch hospitals were reported in the literature, with 21 patients suffering from a clinical infection based on a microorganism proven to be transmitted by a duodenoscope. In that period, ∼203,500 ERCP procedures were performed. Hence, for every 9,690 procedures, 1 patient developed a clinically relevant infection (DAI risk, 0.010%). Conclusions: The risk of developing a DAI is at least 30–180 times higher than the risks that were previously reported for all types of endoscopy-associated infections. Importantly, the current calculated risk of 0.010% constitutes a bare minimum risk of DAI because endoscope-related infections are underreported. Apart from DAI risk, a patient is also at risk of becoming colonized with a microorganism through contaminated endoscopes but without developing symptoms of clinical infection. These data call for consorted action of medical practitioners, industry, and government agencies to minimize and ultimately eliminate the risk of exogenous endoscope-associated infections and contamination. As a first step, the FDA recently recommended that healthcare facilities and manufacturers begin transitioning to duodenoscopes with disposable components.3Funding: NoneDisclosures: None

Estimation of global case fatality rate of coronavirus disease 2019 (COVID-19) using meta-analyses: Comparison between calendar date and days since the outbreak of the first confirmed case

Since the outbreak of the coronavirus disease 2019 (COVID-19) in December of 2019 in China, the estimation of the pandemic’s case fatality rate (CFR) has been the focus and interest of many stakeholders. In this manuscript, we prove that the method of using the cumulative CFR is static and does not reflect the trend according to the daily change per unit of time. A proportion meta-analysis was carried out on CFR in every country reporting COVID-19 cases. Based on the results, we performed a meta-analysis for global COVID-19 CFR. Each analysis was performed on two different calculations of CFR: according to calendar date and according to days since the outbreak of the first confirmed case. We thus explored an innovative and original calculation of CFR concurrently based on the date of the first confirmed case as well as on a daily basis. For the first time, we showed that using meta-analyses, according to calendar date and days since the outbreak of the first confirmed case were different. We propose that CFR according to days since the outbreak of the first confirmed case might be a better predictor of the current CFR of COVID-19 and its kinetics.

Hisab Waktu Shalat dalam Kitab al-Durus al-Falakiyyah

Determination of prayer times in al-Durus al-Falakiyyah uses a list of logarithms with 5 decimals. The existence of this logarithmic list is now very difficult to find, and what is circulating today is a list of logarithms with 4 decimal places and 3 decimal places. If the list of logarithms is used, it will certainly bring up the difference from the original calculation. This study attempts to answer the question whether the list of decimal 4 and 3 decimal places is appropriate for the reckoning of prayer in al-Durus al-Falakiyyah as a substitute for a list of 5 decimal logarithms. An assessment of its feasibility can be seen from whether or not the difference arising from the original calculation can be ignored or not. The results showed that the use of a list of 4 decimal logarithms raises a very small difference, which is an average of 1.12 seconds, so that the difference can be ignored when rounded. But to use a logarithmic decimal 3 list, the difference that is raised can reach 52 seconds. The difference cannot be ignored when rounded and can change the results of the original calculation.

COMPARATIVE ANALYSIS OF GAS VELOCITY INFLUENCE ON THE TEMPERATURE FIELD AND HYDRODYNAMIC LOSSES IN THE EXCHANGER SECTION OF THE COMPACT EXHAUST BOILER

The analysis of the numerical modeling results of gas dynamics in the ducts of the compact exhaust boiler is continued. Currently, there have been done three calculations for the same geometrical model; these calculations have different input speed values, as well as different methods of setting speed. It’s confirmed that in case of continuation of the original calculation with changed boundary condition (speed) in the inlet cross section the results coincide with results of calculation where originally set speed was the same. Thus, it becomes possible to perform several variants of calculations with the same geometry, but with different speed in one session (with minimum correction of initial data). So, the time of setting new temperature mode and the value of gas-dynamic resistance is reduced. Therefore, the time for preparing and carrying out the numerical experiment can be reduced. The influence of input speed on temperature field and hydrodynamic losses in exhaust boiler have been analyzed.

An Observationally Based Global Band-by-Band Surface Emissivity Dataset for Climate and Weather Simulations

While current atmospheric general circulation models (GCMs) still treat the surface as a blackbody in their longwave radiation scheme, recent studies suggest the need for taking realistic surface spectral emissivity into account. There have been few measurements available for the surface emissivity in the far IR (<650 cm−1). Based on first-principle calculation, the authors compute the spectral emissivity over the entire longwave spectrum for a variety of surface types. MODIS-retrieved mid-IR surface emissivity at 0.05° × 0.05° spatial resolution is then regressed against the calculated spectral emissivity to determine the surface type for each grid. The derived spectral emissivity data are then spatially averaged onto 0.5° × 0.5° grids and spectrally integrated onto the bandwidths used by the RRTMG_LW—a longwave radiation scheme widely used in current climate and numerical weather models. The band-by-band surface emissivity dataset is then compared with retrieved surface spectral emissivities from Infrared Atmospheric Sounding Interferometer (IASI) measurements. The comparison shows favorable agreement between two datasets in all the bands covered by the IASI measurements. The authors further use the dataset in conjunction with ERA-Interim to evaluate its impact on the top-of-atmosphere radiation budget. Depending on the blackbody surface assumptions used in the original calculation, the globally averaged difference caused by the inclusion of realistic surface emissivity ranges from −1.2 to −1.5 W m−2 for clear-sky OLR and from −0.67 to −0.94 W m−2 for all-sky OLR. Moreover, the difference is not spatially uniform and has a distinct spatial pattern.

The Calculation of Force Effects of a Conveyor Belt of the Pipe Conveyor to Forming Rollers by FEM

The paper interprets the calculation of the size of force effects created by the reason of the effect of balled conveyor belt of pipe conveyor to the guide rollers located in the ring idler stations. Knowing them is essential for the research of dynamic resistances by pipe conveyors operations. Examined force effects were determined by the help of finite element methods. The calculation was performed by the program Abaqus. Presented calculation is realized by original calculation model. The results of the calculation present information about action of the effect force of the balled conveyor belt to the guide rolls in the ring idler station. Results became a basis for determination of postulates for identification of dynamic resistances. Their knowledge is the key element for conveyor belts lifetime increase.

Ending the myth of the St Petersburg Paradox

Nicolas Bernoulli suggested the St Petersburg game, nearly 300 years ago, which is widely believed to produce a paradox in decision theory. This belief stems from a long standing mathematical error in the original calculation of the expected value of the game. This article argues that, in addition to the mathematical error, there are also methodological considerations which gave rise to the paradox. This article explains these considerations and why because of the modern computer, the same considerations, when correctly applied, also demonstrate that no paradox exists. Because of the longstanding belief that a paradox exists it is unlikely the mere mathematical correction will end the myth. The article explains why it is the methodological correction which will dispel the myth.