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The transition to low-carbon technologies lies in the support of modern energy sources, which are also represented by fusion power plants. One of the first fusion power plants will be the European Union DEMOnstration fusion power plant. Among the key attributes that influence the entire design of this power plant, belongs the power conversion system. In addition to the classic Rankine steam cycle, it is possible to use different cooling media, such as supercritical CO2in the Brayton cycle. The advantages of supercritical CO2are mainly in the compactness of the power conversion system, that is, lower investment costs for the entire power plant while maintaining the high efficiency of the entire power plant. The key question that can influence the choice of the power conversion system is the levelized cost of electricity. The direct cost of the supercritical CO2cycles is lower compared to the Rankine steam cycles, in general. On the other hand, supercritical CO2cycles for the DEMOnstration fusion power plant offer slightly lower efficiency (by approximately 1.5 percentage points), which negatively influences supercritical CO2cycles levelized cost of electricity by 10%–20% against Rankine steam cycles.

Exposure to high altitude results in hypobaric hypoxia, leading to physiological changes in the cardiovascular system that may result in limiting symptoms, including dyspnea, fatigue, and exercise intolerance. However, it is still unclear why some patients are more susceptible to high-altitude symptoms than others. Hypoxic simulation testing (HST) simulates changes in physiology that occur at a specific altitude by asking the patients to breathe a mixture of gases with decreased oxygen content. This study aimed to determine whether the use of transthoracic echocardiography (TTE) during HST can detect the rise in right-sided pressures and the impact of hypoxia on right ventricle (RV) hemodynamics and right to left shunts, thus revealing the underlying causes of high-altitude signs and symptoms. A retrospective study was performed including consecutive patients with unexplained dyspnea at high altitude. HSTs were performed by administrating reduced FiO2 to simulate altitude levels specific to patients’ history. Echocardiography images were obtained at baseline and during hypoxia. The study included 27 patients, with a mean age of 65 years, 14 patients (51.9%) were female. RV systolic pressure increased at peak hypoxia, while RV systolic function declined as shown by a significant decrease in the tricuspid annular plane systolic excursion (TAPSE), the maximum velocity achieved by the lateral tricuspid annulus during systole (S’ wave), and the RV free wall longitudinal strain. Additionally, right-to-left shunt was present in 19 (70.4%) patients as identified by bubble contrast injections. Among these, the severity of the shunt increased at peak hypoxia in eight cases (42.1%), and the shunt was only evident during hypoxia in seven patients (36.8%). In conclusion, the use of TTE during HST provides valuable information by revealing the presence of symptomatic, sustained shunts and confirming the decline in RV hemodynamics, thus potentially explaining dyspnea at high altitude. Further studies are needed to establish the optimal clinical role of this physiologic method.

Abstract Oxygen is viewed in medicine as the sole determinant of tissue oxygenation, though carbon dioxide homeostasis is equally important and clinically often ignored. The aims of this study were as follows: (a) to examine the effects of different acute hypoxic conditions on partial pressure of arterial oxygen (PaO2), arterial oxygen saturation of hemoglobin (SaO2), and regional cerebral saturation of hemoglobin (rSO2); and (b) to evaluate supplemental CO2 as a tool to improve oxygenation in acutely hypoxic individuals. We hypothesized that exposure to gas mixtures with added CO2 would improve oxygenation in hypoxic human subjects. Twenty healthy subjects were exposed to 5‐min intervals of two gas mixtures: hypoxic gas mixture containing 8% oxygen, and a CO2‐enriched mixture containing 8% oxygen plus either 3% or 5% CO2. Ten subjects received the 3% CO2‐enriched mixture, and the remaining 10 subjects received the 5% CO2‐enriched mixture. The order of exposure was randomized. Blood gases, pulse oximetry, end‐tidal CO2, and cerebral oximetry were measured. Compared to the purely hypoxic gas group, PaO2 was increased in the 3% and 5% CO2‐enriched groups by 14.9 and 9.5 mmHg, respectively. Compared to pure hypoxia, SaO2 was increased in the 3% and 5% CO2‐enriched groups by 16.8% and 12.9%, respectively. Both CO2‐enriched gas groups had significantly higher end‐exposure rSO2 and recovered to baseline rSO2 within 1 min, compared to the pure hypoxic gas group, which returned to baseline in 5 min. These results suggest that in acutely hypoxic subjects, CO2 supplementation improves blood oxygen saturation and oxygen tension as well as cerebral oxygenation measures.

Understanding the quench front propagation during bottom core reflooding is crucial for the effective cooling during the LOCA accident. The results presented in this paper were obtained on an experimental loop with an annular test section. The test section consists of a vertical electrically heated stainless steel tube with outer diameter 9 mm and length of 1.7 m. The heated tube is placed inside a glass tube with the inner diameter 14.5 mm. Water mass flux during the reflooding is in the range from 100 kg.m−2.s−1 up to 140 kg.m−2.s−1 and the initial wall temperature of the stainless steel tube is in the range from 250 °C up to 800 °C. The presented results show the influence of the initial conditions on the quench front propagation and the complexity of the phenomenon.

A tuned mass damper is a device, which can be highly helpful while dealing with dynamic behaviour of structures. Its proper design is conditioned by knowledge of both loading and the structure properties. In many cases, the structure can be represented by single degree of freedom model, which simplifies the design and optimization of tuned mass dampers. Most of studies focus only on minimization of displacement of the main structure under harmonic force load, however, in many cases, different frequency response function would be more appropriate. This paper presents an extension of design formulas for the H∞ optimization of tuned mass dampers for damped structures and various frequency response functions.

Tuned mass damper is a device, which can be highly useful when dealing with excessive vibration and is widely used in many engineering fields. However, its proper design and optimization is a complicated task. This study uses mode superposition method to speed up the evaluation of dynamic response. The speed of response calculation allows for a quick calculation of frequency response function and numerical optimization of tuned mass dampers. This optimization method is demonstrated on a numerical example of a cable stayed footbridge. The example compares a simplified and widely used design method of tuned mass damper with numerical optimization.

Working with digitized cultural heritage is an important aspect of education. This article offers research on the interaction of pupils and teachers with digitized cultural heritage processed in the Twine2 environment, focusing on exploring the potential use of digital nonlinear stories in the teaching of humanities in high schools. The aim of this study is to describe the design process that led to the creation of 16 innovative educational resources, and to present the results of their pilot testing and evaluation, which subsequently took place among participating teachers and pupils. For the evaluation, we used a mix of design methods, combining a quantitative and qualitative approach. Both the teachers and the pupils were asked about their experience and takeaways from the interaction with the resources offered. The findings show that presenting educational content in the form of a nonlinear interactive story is a suitable alternative to the traditional frontal educational approach, as both teachers and pupils perceived the resources as intuitive, appealing, and effective in helping to achieve the set educational goals. The study also highlights some key recommendations for future designers of nonlinear interactive stories, which emerged from the respondents’ feedback.

The dynamic analysis of footbridges became common in recent years, but the approach to modelling pedestrian induced load is still inconsistent. This paper compares two different ways of modelling single pedestrian load. The response of the structure to stationary pulsating force is compared to the results given by the same force moving along simply supported beam. 300 randomly generated beams were used in this parametric study to describe the relation among these two approaches and parameters of the structure. The proposed formula was successfully applied to get more realistic estimation of response of the structure to a single walking pedestrian using stationary pulsating force.

Economic efficiency of the furniture production is closely associated with high input costs. Despite the fact that the material makes up 80% of total costs, there were 7,908 active furniture manufacturing companies in 2011 in the Czech Republic and they generated sales of nearly 30,812,199 thousand with an added value of CZK 9,592,032 thousands CZK and employed nearly 22,000 people. The aim of this paper is to assess the development of economic efficiency ratio indicator using return on equity (ROE hereinafter). The evaluation method was developed using statistical methods. The sample included 107 enterprises with more than 50 employees. For each company of the sample the ROE ratio was calculated and descriptive statistics and correlation analysis followed. Average ROE was 3.54% and the median was 3.3% in 2011. ROE of the sample in 2011 decreased compared to the base year 2007, which was the peak of the economic boom, the arithmetic average decreased by 74.68% and a median decrease was 63.7%. The linear trend of the sample and of the entire manufacturing industry had almost identical falling course of ROE development unlike the furniture industry in the Czech Republic. When using correlation analysis the tightness was in the arithmetic average of 30.42% and the tightness of the median was 39.00%.