bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Pilot Study to Detect Balance Impairment in Older Adults Using an Instrumented One-Leg Stance Test
Authors: Bassement Jennifer N. C. , Shukla Brajesh K. , Yadav Sandeep K. , Vijay Vivek , Mathur Arvind , Hewson David J. 
Published: March 2020

Abstract
The aim of this study was to investigate whether parameters from an instrumented one-leg stance (OLS) on a force plate could provide relevant information related to fall risk in older people. Forty-two community dwelling older people including 17 fallers and 25 nonfallers, and 25 young subjects performed a OLS while standing on a force plate, with parameters related to transferring weight onto one leg and postural sway in singe-leg stance evaluated. No differences were observed between older fallers and nonfallers and the younger participants for any of the weight transfer parameters. The younger participants were able to reduce their postural sway during the OLS test after the first 0–2 s period, unlike older participants who swayed the same amount throughout the test. The older fallers swayed significantly more than both nonfallers and younger participants throughout the 10-s of OLS evaluated. When the tests were used to classify older participants as fallers, the instrumented OLS achieved 100% accuracy, compared to 69.0% classification accuracy for the five times sit-to-stand test, 61.9% for the standard OLS, and 47.6% for the timed-up-and-go test. These findings suggest that the standard OLS test might not be suitable to detect fall risk. In contrast, an instrumented version of the OLS could provide valuable additional information that could identify older fallers. Future work will include a prospective study of the instrumented OLS in a larger population of older people.
A New Approach to Transient Vibration Analysis of Two-Dimensional Beam Structures at Medium and High Frequencies
Authors: Yang Bingen , Zhang Yichi 
Published: March 2020

Abstract
Transient analysis of medium-frequency (mid-frequency) and high-frequency vibrations plays an important role in the research and development of complex structures in aerospace, automobile, civil, mechanical, and ship engineering. Low-frequency analysis tools, like the finite element methods, do not work well for mid- and high-frequency problems because they require a huge number of degrees-of-freedom and consequently costly computation, and are sensitive to material properties and boundary conditions. High-frequency analysis tools, such as the statistical energy analysis (SEA) and its variations, are unsuitable for midfrequency problems because they describe the vibrational behaviors of multibody structures in a global manner and cannot provide detailed local information about displacements and internal forces. In this paper, a new method, which is called the augmented distributed transfer function method (DTFM), is proposed for transient vibration analysis of two-dimensional beam structures at medium and high frequencies. Without the need for discretization and numerical integration, the augmented DTFM consistently delivers analytical transient solutions from low to high-frequency regions. A unique feature of the proposed method is that it can provide local information about system response, such as the displacements and internal forces of a structure, at any point and in any frequency region. Additionally, the proposed method provides a platform for model reduction, by which, a balance of efficiency and accuracy in mid- and high-frequency analyses can be achieved. The proposed method is demonstrated in numerical examples.
Comparative Measurements of Different Solar Flux Gauge Types
Authors: Kaluza Jens , Neumann Andreas 
Published: March 2020

Abstract
At the DLR Solar Furnace calorimeters or circular foil radiometers are used for calibrating the video camera based flux mapping systems. Since many years we are investigating the accuracy of these devices and we have undertaken several efforts to check their performance. Furthermore, we developed new instruments and compared these devices to the existent ones. The most recent measurements were collected within the frame of an international intercomparison campaign, called Intercomp 2000, and located at the DLR Solar Furnace in Cologne. This was the opportunity to test our own flux gauges, the 10000 suns Kendall radiometer, the 5000 suns Suncatch calorimeter, 2 HyCal circular foil radiometers for 3000 suns and 2 more HyCal radiometers for 11000 suns. About 100 measurements were taken in the range from 0,5 MW/m2 up to 5 MW/m2. The Kendall radiometer and the Suncatch calorimeter agreed well within the 2 % margin. The circular foil HyCal radiometers showed much higher deviations. This leads to the conclusion that we will change the manufacturer-given calibration constants of the HyCal radiometers by using the data collected with either the SunCatch or the Kendall flux gauges.
Energy Performance Analysis of Coupled Control Units With Both Thermostat and Humidistat
Authors: Liu Mingsheng , Wang Jinrong 
Published: March 2020

Abstract
The coupled control unit is widely used in hotels, dormitory buildings, hospitals, and office buildings. Computer simulation models are developed to analyze the thermal energy performance of the coupled control units. Simulation results indicate that excessive airflow significantly increases thermal and fan power consumption. The variable air volume technique or the return air by-pass can be used to improve the energy performance of the coupled control units. The humidistat should be properly set and located to avoid excessive thermal energy consumption.
SES/Boeing Dish Stirling System Operation
Authors: Stone Kenneth W. , Leingang Eric , Liden Bob , Ellis Erik , Sattar Tariq , Mancini Dr. Thomas , Nelving Hans 
Published: March 2020

Abstract
The data presented in this paper document the operation and service requirements for the 25 kW Stirling Energy Systems (SES)/Boeing Dish Stirling system. Among the information presented are the hydrogen used by the system, oil and water service requirements, and reliability data in the form of a component outage tree. Also presented are discussions of the problems that have occurred during the thousands of hours of on-sun operation of two dish/Stirling systems, which comprise two solar concentrators and three power conversion units (PCUs). We have identified a number changes to the design of the 15-year-old dish/Stirling system. However, based on the performance of the systems and the data presented in this paper, there appear to be no serious obstacles to the commercialization of this technology.
Preliminary Results on Luminaire Designs for Hybrid Solar Lighting Systems
Authors: Earl D. D. , Muhs J. D. 
Published: March 2020

Abstract
We report on the design of two hybrid lighting liminaires that blend light from a fiber optic end-emitted solar source with electric T8 fluorescent lamps. Both designs involve the retrofit of a commercially-available recessed fluorescent luminaire with minimal reductions in the original luminaire’s optical efficiency. Two methods for high-angle dispersion of fiber optic end-emitted solar light are described and the resulting spatial intensity distributions, simulated using ZEMAX, are compared with standard cylindrical fluorescent tubes. Differences in spatial intensity distribution are qualitatively characterized and potential design improvements discussed.
The Importance of Site Surveys in Florida’s PV Buildings Program
Authors: Lynn Kevin 
Published: March 2020

Abstract
One of the goals of the Florida PV Buildings Program is to ensure that only quality utility-interactive PV systems are installed in the state. One important component of the Program is the site survey. The purpose of the site survey is to inspect the potential location for PV system before beginning construction, ensuring it is a sensible place to install it. The purpose of this paper is to introduce the method used by this Program and to present some examples that will demonstrate why it is important.
Optimization Studies for Integrated Solar Combined Cycle Systems
Authors: Kelly Bruce , Herrmann Ulf , Hale Mary Jane 
Published: March 2020

Abstract
The integrated solar plant concept was initially proposed by Luz Solar International [1] as a means of integrating a parabolic trough solar plant with modern combined cycle power plants. An integrated plant consists of a conventional combined cycle plant, a solar collector field, and a solar steam generator. During sunny periods, feedwater is withdrawn from the combined cycle plant heat recovery steam generator, and converted to saturated steam in the solar steam generator. The saturated steam is returned to the heat recovery steam generator, and the combined fossil and solar steam flows are superheated in the heat recovery steam generator. The increased steam flow rate provides an increase in the output of the Rankine cycle. During cloudy periods and at night, the integrated plant operates as a conventional combined cycle facility.
Two studies on integrated plant designs using a General Electric Frame 7(FA) gas turbine and a three pressure heat recovery steam generator are currently being conducted by the authors. Preliminary results include the following items: 1) the most efficient use of solar thermal energy is the production of high pressure saturated steam for addition to the heat recovery steam generator; 2) the quantity of high pressure steam generation duty which can be transferred from the heat recovery steam generator to the solar steam generator is limited; thus, the maximum practical solar contribution is also reasonably well defined; 3) small annual solar thermal contributions to an integrated plant can be converted to electric energy at a higher efficiency than a solar-only parabolic trough plant, and can also raise the overall thermal-to-electric conversion efficiency in the Rankine cycle; and 4) annual solar contributions up to 12 percent in an integrated plant should offer economic advantages over a conventional solar-only parabolic trough power plant.
Parabolic Trough Power for the California Competitive Market
Authors: Price Henry , Cable Robert 
Published: March 2020

Abstract
California is about to complete its third year of a deregulated competitive wholesale power market. During the first two years of the competitive market, power prices averaged between 2 and 3¢/kWh. During 2000, electric supply to California was constrained a number of times causing maximum the price of power to peak over 100¢/kWh, and the average price of power to quadruple.
The power output from solar plants tends to coincide with the high power demand periods in California. This fact had been demonstrated by the solar electric generating stations (SEGS) located in the California Mojave Desert, which operate under specific contracts signed in the 1980’s and early 1990’s with the local utility. This paper, on the other hand, examines how new parabolic trough solar plants would have faired on the wholesale competitive power market during 1999 and 2000.
Experimental Investigation of a Vortex-Flow Solar Chemical Reactor for the Combined ZnO-Reduction and CH4-Reforming
Authors: Kräupl Stefan , Steinfeld Aldo 
Published: March 2020

Abstract
The co-production of Zn and synthesis gas by the combined reduction of ZnO and reforming of CH4 has been performed using a vortex-flow chemical reactor in a high-flux solar furnace. The reactor operating temperature ranged between 1032 and 1481 K for an input solar power of 2.3 to 4.6 kW and mean solar flux intensities of 810 to 1609 kW/m2. The performance of the reactor was determined by conducting a complete mass and energy balance for the chemical process. The chemical conversion ranged between 83–100%. The thermal efficiency, defined as the portion of input solar power absorbed as sensible and process heat, was in the range 11–28%. The exergy efficiency for the closed cycle, defined as the ratio of the maximum amount of work that the products leaving the reactor could produce if were re-combined to the input solar power, was in the range 0.3–3.1%. Major sources of energy loss are re-radiation heat transfer through the reactor aperture, conduction heat transfer through the reactor walls, and the quenching of the reaction products.
Towards the Large Scale Production of Fullerenes and Nanotubes by Solar Energy
Authors: Guillard Tony , Flamant Gilles , Laplaze Daniel , Robert Jean-François , Rivoire Bruno , Giral Joseph 
Published: March 2020

Abstract
Conventional methods for the synthesis of fullerenes and carbon nanotubes such as laser or electric arc ablation have failed when the process is scaled up. Our ultimate goal is to scale a solar process up from 2 to 500 kW; this paper shows that our method for achieving this scale up is valid because we were able to predict process performance variables at the 50 kW level from preliminary experimental results from 2 kW experiments. The key parameters that characterize this process are the carbon soot mass flow rate and the desired product yield. The carbon soot production rate is a function of the target temperature and this can be predicted in a straightforward way from a heat transfer model of the larger system. The yield is a more complicated function of specific reactor variables such as patterns of fluid flow, residence times at various temperatures and the reaction chemistry, but we have found that for fullerenes it depends primarily on the concentration of carbon vapor in the carrier gas, the target temperature and the temperature distribution in the cooling zone. Using these parameters, we scaled our process up to 50 kW and compared the predicted results to the measured performance. A graphite target 6 cm in diameter was vaporized in an argon atmosphere and a reduced pressure of 120–240 hPa with a solar flux density in the range 600–900 W/cm2. Vaporization rates of 20 g/h were measured with a fullerene production rate equal to or greater than 1 g/h, i.e. the expected results.
Infant sleep and child mental health: a longitudinal investigation
Authors: Cook Fallon , Conway Laura J , Giallo Rebecca , Gartland Deirdre , Sciberras Emma , Brown Stephanie 
Published: March 2020

ObjectiveTo determine whether infants with severe persistent sleep problems are at increased risk of (1) meeting diagnostic criteria for a psychiatric disorder (age 10 years), and (2) having elevated symptoms of mental health difficulties (ages 4 and 10 years), in comparison with infants with settled sleep.Design and settingProspective longitudinal community cohort study—the Maternal Health Study. Mothers completed questionnaires/interviews at 15 weeks' gestation; 3, 6, 9 and 12 months post partum; and when their child turned 4 and 10 years old. Measures included parental report of infant night waking and sleep problems and child mental health (Strengths and Difficulties Questionnaire; Spence Children’s Anxiety Scale; Development and Well-being Assessment).Participants1460 mother-infant dyads.Results283 (19.4%) infants had persistent severe sleep problems, 817 (56.0%) had moderate/fluctuating sleep problems and 360 (24.7%) infants were settled. Infants with persistent severe sleep problems were more likely to report emotional symptoms at age 4 (adjusted odds ratio (AOR)=2.70, 95% CI 1.21 to 6.05, p=0.02), and meet diagnostic criteria for an emotional disorder at age 10 (AOR=2.37, 95% CI 1.05 to 5.36, p=0.04). Infants with persistent severe sleep problems also had elevated symptoms of separation anxiety (AOR=2.44, 95% CI 1.35 to 4.41, p<0.01), fear of physical injury (AOR=2.14, 95% CI 1.09 to 4.18, p=0.03) and overall elevated anxiety (AOR=2.20, 95% CI 1.13 to 4.29, p=0.02) at age 10.ConclusionsInfants with persistent severe sleep problems during the first postnatal year have an increased risk of anxiety problems and emotional disorders at age 10.
Challenging the view that lack of fibre causes childhood constipation
Authors: Tappin David , Grzeda Mariusz , Joinson Carol , Heron Jon 
Published: March 2020

ObjectivesTo assess evidence supporting the view that ‘low fibre causes childhood constipation’.DesignTriangulation integrated three approaches: a systematic review NICE guideline CG99 examining effectiveness of increasing fibre; a cohort study, Avon Longitudinal Study of Parents and Children (ALSPAC), to assess if constipation (or hard stools) can precede fibre intake at weaning; and a literature search for twin studies to calculate heredity.SettingCG99 examined the literature regarding the effectiveness of increasing fibre. ALSPAC asked parents about: hard stools at 4 weeks, 6 months and 2.5 years and constipation at age 4–10 years, as well as fibre intake at 2 years. Twin studies and data from ALSPAC were pooled to calculate concordance of constipation comparing monozygotic and dizygous twin pairs.ParticipantsCG99 reported six randomised controlled trials (RCTs). ALSPAC hard stool data from 6796 children at 4 weeks, 9828 at 6 months and 9452 at 2.5 years plus constipation data on 8401 at 4–10 years were compared with fibre intake at 2 years. Twin studies had 338 and 93 twin pairs and ALSPAC added a further 45.ResultsIncreasing fibre did not effectively treat constipation. Hard stools at 4 weeks predated fibre and at 6 months predicted lower fibre intake at 2 years (p=0.003). Heredity explained 59% of constipation.ConclusionsRCTs indicate that increasing fibre is not an effective treatment for constipation in children. Hard stools can precede and predict later fibre intake. Genetic inheritance explains most childhood constipation. Extended treatment with stool softeners may improve fibre intake and limit long-term damaging sequelae of constipation.
Change in drink purchases in 16 Australian recreation centres following a sugar-sweetened beverage reduction initiative: an observational study
Authors: Boelsen-Robinson Tara , Orellana Liliana , Backholer Kathryn , Kurzeme Ariana , Jerebine Alethea , Gilham Beth , Chung Alexandra , Peeters Anna 
Published: March 2020

ObjectiveTo assess the impact of a sugar-sweetened beverage (SSB) reduction initiative on customer purchasing patterns, including volume sales of healthy and unhealthy packaged drinks and sales value of all packaged drinks, in a major Australian aquatic and recreation provider, YMCA Victoria.DesignProspectiveSetting16 aquatic and recreation centres in Victoria, Australia.InterventionsThe SSB-reduction initiative aimed to remove all SSBs (excluding sports drinks) and increase healthier drink availability over a 1-year period.Primary and secondary outcome measuresItemised monthly drink sales data were collected for 16 centres, over 4 years (2 years preimplementation, 1 year implementation and 1 year postimplementation). Drinks were classified as ‘green’ (best choice), ‘amber’ (choose carefully) or ‘red’ (limit). Interrupted time series analysis was conducted for each centre to determine the impact on volume sales of ‘red’ and ‘green’ drinks, and overall sales value. A novel meta-analysis approach was conducted to estimate the mean changes across centres.ResultsFollowing implementation, volume sales of ‘red’ drinks reduced by 46.2% across centres (95% CI: −53.2% to −39.2%), ‘green’ drink volume did not change (0.0%, 95% CI: −13.3% to 13.2%) and total drink sales value decreased by 24.3% (95% CI: −32.0% to −16.6%).ConclusionsThe reduction of SSBs in health-promoting settings such as recreation centres is a feasible, effective public health policy that is likely to be transferable to other high-income countries with similarly unhealthy beverage offerings. However, complementary strategies should be considered to encourage customers to switch to healthier alternatives, particularly when translating policies to organisations with less flexible income streams.
Anaesthesia care providers employed in humanitarian settings by Médecins Sans Frontières: a retrospective observational study of 173 084 surgical cases over 10 years
Authors: Kudsk-Iversen Søren , Trelles Miguel , Ngowa Bakebaanitsa Elie , Hagabimana Longin , Momen Abdul , Helmand Rahmatullah , Saint Victor Carline , Shah Khalid , Masu Adolphe , Kendell Judith , Edgcombe Hilary , English Mike 
Published: March 2020

ObjectiveTo describe the extent to which different categories of anaesthesia provider are used in humanitarian surgical projects and to explore the volume and nature of their surgical workload.DesignDescriptive analysis using 10 years (2008–2017) of routine case-level data linked with routine programme-level data from surgical projects run exclusively by Médecins Sans Frontières-Operational Centre Brussels (MSF-OCB).SettingProjects were in contexts of natural disaster (ND, entire expatriate team deployed by MSF-OCB), active conflict (AC) and stable healthcare gaps (HG). In AC and HG settings, MSF-OCB support pre-existing local facilities. Hospital facilities ranged from basic health centres with surgical capabilities to tertiary referral centres.ParticipantsThe full dataset included 178 814 surgical cases. These were categorised by most senior anaesthetic provider for the project, according to qualification: specialist physician anaesthesiologists, qualified nurse anaesthetists and uncertified anaesthesia providers.Primary outcome measureVolume and nature of surgical workload of different anaesthesia providers.ResultsFull routine data were available for 173 084 cases (96.8%): 2518 in ND, 42 225 in AC, 126 936 in HG. Anaesthesia was predominantly led by physician anaesthesiologists (100% in ND, 66% in AC and HG), then nurse anaesthetists (19% in AC and HG) or uncertified anaesthesia providers (15% in AC and HG). Across all settings and provider groups, patients were mostly healthy young adults (median age range 24–27 years), with predominantly females in HG contexts, and males in AC contexts. Overall intra-operative mortality was 0.2%.ConclusionOur findings contribute to existing knowledge of the nature of anaesthetic provision in humanitarian settings, while demonstrating the value of high-quality, routine data collection at scale in this sector. Further evaluation of perioperative outcomes associated with different models of humanitarian anaesthetic provision is required.