Energetics of Floor Gymnastics: Aerobic and Anaerobic Share in Male and Female Sub-elite Gymnasts

Background Artistic gymnastics is a popular Olympic discipline where female athletes compete in four and male athletes in six events with floor exercise having the longest competition duration in Women’s and Men’s artistic gymnastics (WAG, MAG). To date no valid information on the energetics of floor gymnastics is available although this may be important for specific conditioning programming. This study evaluated the metabolic profile of a simulated floor competition in sub-elite gymnasts. Methods 17 (9 male, 8 female) sub-elite gymnasts aged 22.5 ± 2.6y took part in a floor-training-competition where oxygen uptake was measured during and until 15 min post-exercise. Additionally, resting and peak blood lactate concentration after exercise were obtained. The PCr-LA-O2 method was used to calculate the metabolic energy and the relative aerobic (WAER), anaerobic alactic (WPCr) and anaerobic lactic (WBLC) energy contribution. Further, the athletes completed a 30 s Bosco-jumping test, a countermovement jump and a drop jump. Results The competition scores were 9.2 (CI:8.9–9.3) in WAG and 10.6 (CI:10.4–10.9) in MAG. The metabolic profile of the floor routine was mainly aerobic (58.9%, CI: 56.0–61.8%) followed by the anaerobic alactic (24.2%, CI: 21.3–27.1%) and anaerobic lactic shares (16.9%, CI:14.9–18.8%). While sex had a significant (p = .010, d = 1.207) large effect on energy contribution, this was not the case for competition duration (p = .728, d = 0.061). Relative energy contribution of WAG and MAG differed in WAER (64.0 ± 4.7% vs. 54.4 ± 6.8%, p = .004, d = 1.739) but not in WPCr (21.3 ± 6.1% vs. 26.7 ± 8.0%, p = .144, d = 0.801) and WBLC (14.7 ± 5.4% vs. 18.9 ± 4.2%, p = .085, d = 0.954). Further no correlation between any energy share and performance was found but between WPCr and training experience (r = .680, p = .044) and WBLC and competition level (r = .668, p = .049). Conclusion The results show a predominant aerobic energy contribution and a considerable anaerobic contribution with no significant difference between anaerobic shares. Consequently, gymnastic specific aerobic training should not be neglected, while a different aerobic share in WAG and MAG strengthens sex-specific conditioning. All in all, the specific metabolic share must secure adequate energy provision, while relative proportions of the two anaerobic pathways seem to depend on training and competition history.

Investigation of the Performance and Emission Characteristics of Diesel Engine Fueled with Biogas-Diesel Dual Fuel

Due to the popularity of diesel engines, utilization of fossil fuel has increased. However, fossil fuel resources are depleting and their prices are increasing day by day. Additionally, the emissions from the burning of petroleum-derived fuel is harming the global environment. This work covers the performance and emission parameters of a biogas-diesel dual-fuel mode diesel engine and compared them to baseline diesel. The experiment was conducted on a single-cylinder and four-stroke DI diesel engine with a maximum power output of 2.2 kW by varying engine load at a constant speed of 1500 RPM. The diesel was injected as factory setup, whereas biogas mixes with air and then delivered to the combustion chamber through intake manifold at various flow rates of 2, 4, and 6 L/min. At 2 L/min flow rate of biogas, the results were found to have better performance and lower emission, than that of the other flow; with an average reduction in BTE, HC, and NOx by 11.19, 0.52, and 19.91%, respectively, and an average increment in BSFC, CO, and CO2 by 11.81, 1.05, and 12.8%, respectively, as compared to diesel. The diesel replacement ratio was varied from 19.56 to 7.61% at zero engine load and 80% engine load with biogas energy share of 39.6 and 16.59%, respectively.

Modelling the efficiency of power system with reserve capacity from variable renewable sources of energy

The paper considers modeling the efficiency of power system with integration large share of variable renewable sources of energy with the account of climate conditions of Ukraine. The proposed methodology with its position between system planning and dispatch simulation contributes to the field of hybrid energy system models. The idea behind the method allows high spatial and temporal resolution as well as the inclusion of the technical details of the power system and its dispatch. The novelty of this method is the usage of a parametric approach is chosen to analyze different variable renewable sources of energy scenarios, precisely every possible its share and mix. This provides insights on the systematic effects of different resource mixes and may serve as a new approach to the analysis of future power system development. The additional novelty aspect allows the optimization of the design of the technical details of the power system with large variable renewable sources shares to have continuous improvement of its energy efficiency. The energy balance model generator is well suited for the analysis of large share of variable renewable sources integration in the power system. The design of technical details of the power system with large variable renewable sources shares was optimized with the energy balance model. The results of numerical modelling demonstrated that at 80% variable renewable sources of energy share, the overproduction is reduced to 20%, down from over 100 % without grid extensions. With it, the necessary wind and solar capacity decreases. Consequently, the possible achievable variable renewable sources of energy share is increased, assuming the same technical potential. According to the results, a Ukrainian grid would allow to increase the possible variable renewable sources of energy share from 50% to 75%.

Ultra-processed food consumption in adults across Europe

Purpose The purpose of this study is to describe ultra-processed food and drinks (UPFDs) consumption, and associations with intake of total sugar and dietary fibre, and high BMI in adults across Europe. Methods Using food consumption data collected by food records or 24-h dietary recalls available from the European Food Safety Authority (EFSA) Comprehensive European Food Consumption Database, the foods consumed were classified by the level of processing using the NOVA classification. Diet quality was assessed by data linkage to the Dutch food composition tables (NEVO) and years lived with disability for high BMI from the Global Burden of Disease Study 2019. Bivariate groupings were carried out to explore associations of UPFDs consumption with population intake of sugar and dietary fibre, and BMI burden, visualised by scatterplots. Results The energy share from UPFDs varied markedly across the 22 European countries included, ranging from 14 to 44%, being the lowest in Italy and Romania, while the highest in the UK and Sweden. An overall modest decrease (2–15%) in UPFDs consumption is observed over time, except for Finland, Spain and the UK reporting increases (3–9%). Fine bakery wares and soft drinks were most frequently ranked as the main contributor. Countries with a higher sugar intake reported also a higher energy share from UPFDs, as most clearly observed for UPF (r = 0.57, p value = 0.032 for men; and r = 0.53, p value = 0.061 for women). No associations with fibre intake or high BMI were observed. Conclusion Population-level UPFDs consumption substantially varied across Europe, although main contributors are similar. UPFDs consumption was not observed to be associated with country-level burden of high BMI, despite being related to a higher total sugar intake.

A Study on Through-the-Thickness Heating in Continuous Ultrasonic Welding of Thermoplastic Composites

Continuous ultrasonic welding is a promising technique for joining thermoplastic composites structures together. The aim of this study was to gain further insight into what causes higher through-the-thickness heating in continuous ultrasonic welding of thermoplastic composites as compared to the static process. Thermocouples were used to measure temperature evolutions at the welding interface and within the adherends. To understand the mechanisms causing the observed temperature behaviours, the results were compared to temperature measurements from an equivalent static welding process and to the predictions from a simplified heat transfer model. Despite the significantly higher temperatures measured at the welding interface for the continuous process, viscoelastic bulk heat generation and not thermal conduction from the interface was identified as the main cause of higher through-the-thickness heating in the top adherend. Interestingly the top adherend seemed to absorb most of the vibrational energy in the continuous process as opposed to a more balanced energy share between the top and bottom adherend in the static process. Finally, the higher temperatures at the welding interface in continuous ultrasonic welding were attributed to pre-heating of the energy director due to the vibrations being transmitted downstream of the sonotrode, to reduced squeeze-flow of energy director due to the larger adherend size, and to heat flux originating downstream as the welding process continues.

Wind Energy Potential Assessment Based-on WRF Four-Dimensional Data Assimilation System and Cross-Calibrated Multi-Platform Dataset

Indonesia has a target of achieving 23% of renewable energy share in the total energy mix in 2025. However, Indonesia does not have accurate and comprehensive data on renewable energy potentials, especially wind energy. This article aims to assess the theoretical potential of wind speed and to visualize the wind speed by province for the entire Indonesia. Our assessment relied on the Weather Research and Forecasting (WRF) model using Four-Dimensional Data Assimilation technique, also known as Nudging Newtonian relaxation. The robustness of our analysis is confirmed by using high-resolution data from the National Centers for Environmental Prediction–Final (NCEP - FNL) and Cross-Calibrated Multi-Platform (CCMP) Reanalysis satellite data. This study shows the WRF method is a feasible option to estimate wind speed data.

Energy Evolution and Water Immersion-Induced Weakening Mechanism in the Sandstone Roof of Coal Mines

The instability of underground spaces in abandoned coal mines with water-immersed rocks is one of the main hazards hindering the geothermal energy utilization and ecological restoration of post-mining areas. This study conducted graded cyclic loading-unloading tests of five groups of sandstone samples with different water contents. The evolution laws of input, elastic, dissipated, damping, and plastic energies were explored in detail, taking into account the damping effect. The normalized plastic energy was used to characterize the damage evolution of sandstone samples, which failure modes were analyzed from both macroscopic and microscopic perspectives. The X-ray diffraction technique and scanning electron microscopy were used to reveal the softening mechanism of sandstone's strength and elastic energy storage limit. The results showed that the graded cyclic loading's input, elastic, and dissipated energies increased gradually. The elastic energy share first increased and then stabilized, while dissipated energy share variation had the opposite trend. In each cycle, the input energy was primarily stored in the form of elastic energy, while the dissipated energy was mainly used to overcome the damping of sandstone. When the normalized number of cycles approached unity, the plastic energy share sharply increased, while that of the dampening energy featured an abrupt drop. Such change indicated an inevitable instability failure of the water-bearing sandstone. As the water content increased, the pore water exhibited more substantial lubrication, water-wedging, and dissolution effects on mineral particles. As a result, the latter obtained a round form, and the elastic energy storage limit of the sandstone decreased. When the water content was increased, the damage factor of sandstone after the same number of cycles increased at a relatively higher rate, and there was a transition of failure mode from brittle to ductile.

Coupling of Power and Heating Sector – Opportunity for Heating Sector Development

European Union has set ambitious decarbonization goals under Green Deal, therefore, Latvia needs to search for solutions on how to move towards reaching the said goals. Although renewable energy share in Latvia is one of the highest among the European Union countries, it is mostly due to historic heritage, not as the result of implementing meaningful policies. Essential high renewable energy share in power sector comes from three large hydroelectric stations on Daugava, which is heritage from the Soviet Union times. Steady increase in renewable energy share can be observed in District Heating, however it is based on increased utilization of biomass, and that most likely is not a sustainable solution. Considering that bioeconomy will experience significant growth in the future, utilization of wood resource for production of products with low added value will steadily phase out. For energy sector it means the necessity to look for other alternatives to replace fossil fuels. If in other European countries (Denmark, Germany, the Netherlands, Lithuania, Estonia, et al.) solar and wind technology capacity have significantly increased over last decade, in Latvia this increase is negligible. Only in the last few years significant increase in installed solar capacities can be observed, but total capacity is still low. Latvia needs to seek solutions on how to increase the introduction rate of renewable energy technologies in order to move towards carbon neutrality in 2050. The aim of the Thesis is to develop a comprehensive system dynamics model which can be used to analyze energy sector at both national and local scale. It should include both heating and power sectors and be able to evaluate the possibility of sector coupling and its influence on the total system. Specific objectives are set to reach the aim: to develop a system dynamics model structure for heating system development; to analyze the heating system at local and national scale; to assess the importance of power sector flexibility on system development; to implement the elements of sector coupling in energy system; to analyze sector coupling as a flexibility increase measure for national scale and local systems.

EU-28’s progress toward the 2020 renewable energy share: a club convergence analysis

This paper assesses the convergence of the EU-28 countries toward their common goal of 20% in the renewable energy share indicator by year 2020. The potential presence of clubs of convergence toward different steady-state equilibria is also analyzed from both the standpoints of global convergence to the 20% goal and specific convergence to the various targets assigned to Member States. Two clubs of convergence are detected in the former case, each corresponding to different renewable energy source targets. A probit model is also fitted with the aim of better understanding the determinants of club membership, which seemingly include real GDP per capita, expenditure on environmental protection, energy dependence, and nuclear capacity, with all of them having statistically significant effects. Finally, convergence is also analyzed separately for the transport, heating and cooling, and electricity sectors.