Electrification of residential areas is increasingly common. Major areas of development include rooftop solar panels, electric vehicles and heat pumps. However, existing grid components may have insufficient network capacity to accommodate the resulting electricity flows. Battery energy storage (BES) can be used to prevent transformer overloading resulting from electrification. Ideally, BES should be sized and placed such that it can prevent overloading with a minimum amount of storage capacity, but it is unclear how load characteristics affect BES capacity requirements. This study investigated how load simultaneity affects the minimum BES capacity required to prevent transformer overloading, comparing a central with a distributed BES layout. It was found that as simultaneity increases, distributed storage requires relatively less capacity than central storage. This is likely due to the reduced ability of central BES to share capacity between connections as simultaneity increases, and the ability of distributed BES to better reduce transportation losses.
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Market competition and global financial uncertainty have been the principal drivers that impel aviation companies to proceed to budget cuts, including decreases in salary and work force levels, in order to ensure viability and sustainability. Under the concepts of Maslow and Herzberg’s motivation theories, the current paper unfolds the influence of employment cost fluctuations on an aviation organization’s accidents attributed to human error. This study exploited financial and accident data over a period of 13 years, and explored if rates of accidents attributed to human errors of flight, maintenance and ramp crews, correlate with the average employment expenditures (N=13). In addition, the study took into account the relationship between average task load (ratio of flying hours per employee) and accident rates related to human error since task load, as part of total workload, is a constraint of modern complex systems. The results revealed strong correlations amongst accident rates linked to human error with the average employment costs and task load. The use of more specific data per aviation organizational department and professional group may further validate the results of this study. Organizations that seek to explore the 2 association between human error and employment budget and task load might appropriately adapt the approach proposed.
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Background: To avoid overexertion in critically ill patients, information on the physical demand, i.e., metabolic load, of daily care and active exercises is warranted. Objective: The objective of this study was toassess the metabolic load during morning care activities and active bed exercises in mechanically ventilated critically ill patients. Methods: This study incorporated an explorative observational study executed in a university hospital intensive care unit. Oxygen consumption (VO2) was measured in mechanically ventilated (≥48 h) critically ill patients during rest, routine morning care, and active bed exercises. We aimed to describe and compare VO2 in terms of absolute VO2 (mL) defined as the VO2 attributable to the activity and relative VO2 in mL per kilogram bodyweight, per minute (mL/kg/min). Additional outcomes achieved during the activity were perceived exertion, respiratory variables, and the highest VO2 values. Changes in VO2 and activity duration were tested using paired tests. Results: Twenty-one patients were included with a mean (standard deviation) age of 59 y (12). Median (interquartile range [IQR]) durations of morning care and active bed exercises were 26 min (21–29) and 7 min (5–12), respectively. Absolute VO2 of morning care was significantly higher than that of active bed exercises (p = 0,009). Median (IQR) relative VO2 was 2.9 (2.6–3.8) mL/kg/min during rest; 3.1 (2.8–3.7) mL/kg/min during morning care; and 3.2 (2.7–4) mL/kg/min during active bed exercises. The highest VO2 value was 4.9 (4.2–5.7) mL/kg/min during morning care and 3.7 (3.2–5.3) mL/kg/min during active bed exercises. Median (IQR) perceived exertion on the 6–20 Borg scale was 12 (10.3–14.5) during morning care (n = 8) and 13.5 (11–15) during active bed exercises (n = 6). Conclusion: Absolute VO2 in mechanically ventilated patients may be higher during morning care than during active bed exercises due to the longer duration of the activity. Intensive care unit clinicians should be aware that daily-care activities may cause intervals of high metabolic load and high ratings of perceived exertion.
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Quantifying measures of physical loading has been an essential part of performance monitoring within elite able-bodied sport, facilitated through advancing innovative technology. In wheelchair court sports (WCS) the inter-individual variability of physical impairments in the athletes increases the necessity for accurate load and performance measurements, while at the same time standard load monitoring methods (e.g. heart-rate) often fail in this group and dedicated WCS performance measurement methods are scarce. The objective of this review was to provide practitioners and researchers with an overview and recommendations to underpin the selection of suitable technologies for a variety of load and performance monitoring purposes specific to WCS. This review explored the different technologies that have been used for load and performance monitoring in WCS. During structured field testing, magnetic switch based devices, optical encoders and laser systems have all been used to monitor linear aspects of performance. However, movement in WCS is multidirectional, hence accelerations, decelerations and rotational performance and their impact on physiological responses and determination of skill level, is also of interest. Subsequently both for structured field testing as well as match-play and training, inertial measurement units mounted on wheels and frame have emerged as an accurate and practical option for quantifying linear and non-linear movements. In conclusion, each method has its place in load and performance measurement, yet inertial sensors seem most versatile and accurate. However, to add context to load and performance metrics, position-based acquisition devices such as automated image-based processing or local positioning systems are required.
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Accurate assessment of rolling resistance is important for wheelchair propulsion analyses. However, the commonly used drag and deceleration tests are reported to underestimate rolling resistance up to 6% due to the (neglected) influence of trunk motion. The first aim of this study was to investigate the accuracy of using trunk and wheelchair kinematics to predict the intra-cyclical load distribution, more particularly front wheel loading, during hand-rim wheelchair propulsion. Secondly, the study compared the accuracy of rolling resistance determined from the predicted load distribution with the accuracy of drag test-based rolling resistance. Twenty-five able-bodied participants performed hand-rim wheelchair propulsion on a large motor-driven treadmill. During the treadmill sessions, front wheel load was assessed with load pins to determine the load distribution between the front and rear wheels. Accordingly, a machine learning model was trained to predict front wheel load from kinematic data. Based on two inertial sensors (attached to the trunk and wheelchair) and the machine learning model, front wheel load was predicted with a mean absolute error (MAE) of 3.8% (or 1.8 kg). Rolling resistance determined from the predicted load distribution (MAE: 0.9%, mean error (ME): 0.1%) was more accurate than drag test-based rolling resistance (MAE: 2.5%, ME: −1.3%).
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This scoping review aimed to systematically explore the breadth and extent of the literature regarding the relationship between contextual factors (CFs) and training load (TL) in adolescent soccer players. Further aims included comprehending potential underlying mechanisms and identifying knowledge gaps. CFs were defined as factors not part of the main training process, such as the coach–athlete relationship and educational responsibilities. PubMed, EBSCO APA PsycINFO, Web of Science, ProQuest Dissertations & Theses A&I, and SportRxiv were searched. Studies involving adolescent soccer players that investigated the CF–TL relationship and measured TL indicators were deemed eligible. Seventeen studies were included, reflecting the limited number of articles published regarding the CF–TL relationship. CFs were mostly related to match-play (N = 13) and phase of the season (N = 7). Moreover, these factors appeared to affect TL. CF related to players’ personal environment (N = 3) were underrepresented in the reviewed studies. Overall, the CF–TL relationship appears to be rarely scrutinized. A likely cause for this lack of research is the segregation of the physiological and psychological research domains, where the CF–TL relationship is often speculated upon but not measured. Therefore, a holistic approach is warranted which also investigates the effect of personal environment, such as stressful life stress events, on TL.
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Background: Training load is typically described in terms of internal and external load. Investigating the coupling of internal and external training load is relevant to many sports. Here, continuous kernel-density estimation (KDE) may be a valuable tool to capture and visualize this coupling. Aim: Using training load data in speed skating, we evaluated how well bivariate KDE plots describe the coupling of internal and external load and differentiate between specific training sessions, compared to training impulse scores or intensity distribution into training zones. Methods: On-ice training sessions of 18 young (sub)elite speed skaters were monitored for velocity and heart rate during 2 consecutive seasons. Training session types were obtained from the coach’s training scheme, including endurance, interval, tempo, and sprint sessions. Differences in training load between session types were assessed using Kruskal–Wallis or Kolmogorov–Smirnov tests for training impulse and KDE scores, respectively. Results: Training impulse scores were not different between training session types, except for extensive endurance sessions. However, all training session types differed when comparing KDEs for heart rate and velocity (both P < .001). In addition, 2D KDE plots of heart rate and velocity provide detailed insights into the (subtle differences in) coupling of internal and external training load that could not be obtained by 2D plots using training zones. Conclusion: 2D KDE plots provide a valuable tool to visualize and inform coaches on the (subtle differences in) coupling of internal and external training load for training sessions. This will help coaches design better training schemes aiming at desired training adaptations.
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Het ondergaan van een eenzijdige beenamputatie is een drastische chirurgische ingreep. Mensen, die na een amputatie in staat zijn om te lopen met een prothese, zijn functioneel onafhankelijker, en hebben een hogere kwaliteit van leven dan mensen die in een rolstoel belanden. Het is daarom niet verrassend dat het herwinnen van de oopvaardigheid één van de voornaamste doelen is tijdens de revalidatie. Doel van het onderzoek was om inzicht te krijgen in de factoren die het herwinnen en onderhouden van de loopvaardigheid van mensen na een beenamputatie beïnvloeden. Gebaseerd op de resultaten van het onderzoek kan geconcludeerd worden dat de fysieke capaciteit hierbij een belangrijke rol speelt. Een relatief kleine verbetering in de capaciteit kan al resulteren in significante en klinisch relevante verbeteringen. Hoewel geavanceerde prothesen de mechanische belasting van het lopen met een beenprothese verminderen, kan een ineffectieve balanscontrole deze positieve resultaten weer tenietdoen. ABSTRACT Undergoing a lower limb amputation is a life-changing surgery. The ability to walk greatly influences the subject's functional independence and quality of life. Not surprisingly, regaining walking ability is one of the primary goals during prosthetic rehabilitation. The primary aim of the research performed was to enhance our understanding of some of the factors that influence the ability to regain and maintain walking after a unilateral lower limb amputation. Based on the results we can deduce that a person's physical capacity plays an important role in their walking ability. Relatively small improvements in capacity could lead to significant and clinically relevant improvements in people's walking ability. Furthermore, results show that sophisticated prosthetic feet can reduce the mechanical load experienced when walking with a prosthesis. Interestingly, inefficient balance control strategies can undo any positive effect of these prostheses.
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The prediction of the running injuries based on selfreported training data on load is difficult. At present, coaches and researchers have no validated system to predict if a runner has an increased risk of injuries. We aim to develop an algorithm to predict the increase of the risk of a runner to sustain an injury. As a first step Self-reported data on training parameters and injuries from high-level runners (duration=37 weeks, n=23, male=16, female=7) were used to identify the most predictive variables for injuries, and train a machine learning tree algorithm to predict an injury. The model was validated by splitting the data in training and a test set. The 10 most important variables were identified from 85 possible variables using the Random Forest algorithm. To predict at an earliest stage, so the runner or the coach is able to intervene, the variables were classified by time to build tree algorithms up to 7 weeks before the occurrence of an injury. By building machine learning algorithms using existing self-reported training data can enable prospective identification of high-level runners who are likely to develop an injury. Only the established prediction model needs to be verified as correct.
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The European Union is striving for a high penetration of renewable energy production in the future energy grid. Currently, the EU energy directive is aiming for 20% renewable energy production in the year 2020. In future plans the EU strives for approximately 80% renewable energy production by the year 2050. However, high penetration of wind and solar PV energy production, both centrally and de-centrally, can possibly destabilize the electricity grid. The gas grid and the flexibility of gas, which can be transformed in both electricity and heat at different levels of scale, can help integrate and balance intermittent renewable production. One possible method of assisting the electricity grid in achieving and maintaining balance is by pre-balancing local decentralized energy grids. Adopting flexible gas based decentralized energy production can help integrate intermittent renewable electricity production, short lived by-products (e.g. heat) and at the same time minimize transport of energy carriers and fuel sources. Hence, decentralized energy grids can possibly improve the overall efficiency and sustainability of the energy distribution system. The flexibility aforementioned, can potentially give gas a pivotal role in future decentralized energy grids as load balancer. However, there are a lot of potentially variables which effect a successful integration of renewable intermittent production and load balancing within decentralized energy systems. The flexibility of gas in general opens up multiple fuel sources e.g., natural gas, biogas, syngas etc. and multiple possibilities of energy transformation pathways e.g. combined heat and power, fuel cells, high efficiency boilers etc. Intermittent renewable production is already increasing exponentially on the decentralized level where load balancing is still lacking.
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