scholarly journals Solar Power Concentrators for Space Applications

2016 ◽  
Vol 3 ◽  
pp. 2-26 ◽  
Author(s):  
Joshua Pritchard ◽  
Kiri Simon ◽  
Cameron Dowd ◽  
Eashwar Joshi
Keyword(s):  
Solar Power ◽  
Meta Analysis ◽  
Fresnel Lens ◽  
Optimal Choice ◽  
Spectral Irradiance ◽  
Specific Power ◽  
Space Applications ◽  
Current Matching ◽  
Efficiency Increase ◽  
Compact Design

Space based solar power is an attractive solution to growing energy needs, overcoming the operational downtime and atmospheric losses inherent to terrestrial solar technologies. Ideal solar satellites include concentrator systems in order to produce a high specific power output, keeping mass low for economic launch. A meta analysis of photovoltaic concentrator research is presented to determine viability in space applications, considering contributions to cell heating, subcell current matching and efficiency of the InGaP/GaAs/Ge multi-junction cell. We find that the CaF2 Fresnel lens is an optimal choice with an efficiency increase of 4.9% at 17 suns. The large range of concentration ratio, low mass, compact design and minimal effect on spectral irradiance allow a wide space for optimisation in temperature control, whilst the current matching conditions under concentration can be regulated by appropriate tunnel junction width and bandgap.

Fatigue As A Performance Shaping Factor In Human Reliability Analysis For Long-Duration Spaceflight

2020 ◽  
Vol 64 (1) ◽  
pp. 1681-1685
Author(s):  
Ronald Boring ◽  
Thomas Ulrich ◽  
Torrey Mortenson ◽  
David German
Keyword(s):  
Reliability Analysis ◽  
Meta Analysis ◽  
Extended Period ◽  
Human Reliability ◽  
Human Reliability Analysis ◽  
Space Applications ◽  
Performance Shaping Factors ◽  
Long Duration ◽  
Starting Point ◽  
Chronic Sleep

This paper provides background on the process to enhance human reliability analysis (HRA) for long-duration space applications. While short-duration missions largely mirror ground activities and fit well with existing HRA methods, new missions to the Moon or Mars entail a significantly longer duration of time in space for astronauts. This extended period in space presents opportunities to affect astronaut performance that require consideration of new performance shaping factors (PSFs). In the present paper, we conducted a meta-analysis on fatigue and developed a new PSF to account for chronic sleep deprivation associated with long-duration space missions. Fatigue provides a starting point for additional PSFs needed for space HRA.

scholarly journals Analysis of spectral irradiance blurring by Fresnel lens sunlight concentrators

2019 ◽  
Vol 1400 ◽  
pp. 066059
Author(s):  
E D Filimonov ◽  
S A Levina ◽  
M Z Shvarts
Keyword(s):  
Fresnel Lens ◽  
Spectral Irradiance

Optimal Choice of Ultrasound-Based Measurements for the Diagnosis of Ulnar Neuropathy at the Elbow: A Meta-Analysis of 1961 Examinations

2020 ◽  
Vol 215 (5) ◽  
pp. 1171-1183
Author(s):  
Arya Haj-Mirzaian ◽  
Nima Hafezi-Nejad ◽  
Filippo Del Grande ◽  
Yoshimi Endo ◽  
O. Kenechi Nwawka ◽  
...  
Keyword(s):  
Meta Analysis ◽  
Optimal Choice ◽  
Ulnar Neuropathy

Flexible, Lightweight, Amorphous Silicon Based Solar Cells on Polymer Substrate for Space and Near-Space Applications

2011 ◽  
Vol 1321 ◽  
Author(s):  
K. Beernink ◽  
A. Banerjee ◽  
J. Yang ◽  
K. Lord ◽  
F. Liu ◽  
...  
Keyword(s):  
Solar Cells ◽  
Amorphous Silicon ◽  
Polymer Substrate ◽  
Specific Power ◽  
Large Area ◽  
Space Applications ◽  
Area Efficiency ◽  
Near Space ◽  
Roll To Roll ◽  
High Flexibility

ABSTRACTUnited Solar Ovonic has leveraged its history of making amorphous silicon solar cells on stainless steel substrates to develop amorphous silicon alloy (a-Si:H)-based solar cells and modules on ∼25 μm thick polymer substrate using high-throughput roll-to-roll deposition technology for space and near-space applications. The solar cells have a triple-junction a-Si:H/a-SiGe:H/a-SiGe:H structure deposited by conventional plasma enhanced CVD (PECVD) using roll-to-roll processing. The cells have distinct advantages in terms of high specific power (W/kg), high flexibility, ruggedness, rollability for stowage, and irradiation resistance. The large area (23.9 cm x 32.1 cm) individual cells manufactured in large quantity can be readily connected into modules and have achieved initial, 25 °C, AM0 aperture-area efficiency of 9.8% and initial specific power of 1200 W/kg. We have conducted light-soak studies and measured the temperature coefficient of the current-voltage characteristics to determine the stable values at an expected operating temperature of 60 °C. The stable total-area efficiency and specific power at 60 °C are 7.2% and 950 W/kg, respectively. In this paper, we review the challenges and progress made in development of the cells, highlight some applications, and discuss current efforts aimed at improving performance.

scholarly journals Is there an optimal choice in refractory colorectal cancer? A network meta-analysis

2019 ◽  
Vol 30 ◽  
pp. iv14 ◽  
Author(s):  
A. Casadei Gardini ◽  
F. Gelsomino ◽  
A. Spallanzani ◽  
E. Tamburini ◽  
M. Scartozzi ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Meta Analysis ◽  
Optimal Choice

Cemented humeral stem versus press-fit humeral stem in total shoulder arthroplasty

2019 ◽  
Vol 101-B (9) ◽  
pp. 1107-1114 ◽  
Author(s):  
M. Uy ◽  
J. Wang ◽  
N. S. Horner ◽  
A. Bedi ◽  
T. Leroux ◽  
...  
Keyword(s):  
Shoulder Arthroplasty ◽  
Operative Time ◽  
Meta Analysis ◽  
Total Shoulder Arthroplasty ◽  
A Priori ◽  
Optimal Choice ◽  
Complication Rates ◽  
Press Fit ◽  
Fixation Type

Aims The aim of this study was to evaluate the differences in revision and complication rates, functional outcomes, and radiological outcomes between cemented and press-fit humeral stems in primary anatomical total shoulder arthroplasty (TSA). Materials and Methods A comprehensive systematic review and meta-analysis was conducted searching for studies that included patients who underwent primary anatomical TSA for primary osteoarthritis or rheumatoid arthritis. Results There was a total of 36 studies with 927 cemented humeral stems and 1555 press-fit stems. The revision rate was 5.4% (95% confidence interval (CI) 3.9 to 7.4) at a mean of 89 months for cemented stems, and 2.4% (95% CI 1.1 to 4.7) at a mean of 40 months for press-fit stems. A priori subgroup analysis to control for follow-up periods demonstrated similar revision rates: 2.3% (95% CI 1.1 to 4.7) for cemented stems versus 1.8% (95% CI 1.4 to 2.9) for press-fit stems. Exploratory meta-regression found that longer follow-up was a moderating variable for revision (p = 0.003). Conclusion Cement fixation had similar revision rates when compared to press-fit stems at short- to midterm follow-up. Rotator cuff pathology was a prevalent complication in both groups but is likely not related to fixation type. Overall, with comparable revision rates, possible easier revision, and decreased operative time, humeral press-fit fixation may be an optimal choice for primary anatomical TSA in patients with sufficient bone stock. Cite this article: Bone Joint J 2019;101-B:1107–1114.

scholarly journals Efficacy and safety of flexible versus rigid endoscopic third ventriculostomy in pediatric and adult populations: a systematic review and meta-analysis

2021 ◽  
Author(s):  
Alessandro Boaro ◽  
Bhargavi Mahadik ◽  
Anthony Petrillo ◽  
Francesca Siddi ◽  
Sharmila Devi ◽  
...  
Keyword(s):  
Endoscopic Third Ventriculostomy ◽  
Perioperative Complications ◽  
Meta Analysis ◽  
Case Series ◽  
Optimal Choice ◽  
Third Ventriculostomy ◽  
Efficacy And Safety ◽  
Bleeding Events ◽  
Random Effects Models ◽  
Hydrocephalus Treatment

AbstractEndoscopic third ventriculostomy (ETV) is a well-established surgical procedure for hydrocephalus treatment, but there is sparse evidence on the optimal choice between flexible and rigid approaches. A meta-analysis was conducted to compare efficacy and safety profiles of both techniques in pediatrics and adults. A comprehensive search was conducted on PubMED, EMBASE, and Cochrane until 11/10/2019. Efficacy was evaluated comparing incidence of ETV failure, while safety was defined by the incidence of perioperative complications, intraoperative bleedings, and deaths. Random-effects models were used to pool the incidence. Out of 1365 studies, 46 case series were meta-analyzed, yielding 821 patients who underwent flexible ETV and 2918 who underwent rigid ETV, with an age range of [5 days–87 years]. Although flexible ETV had a higher incidence of failure in adults (flexible: 54%, 95%CI: 22–82% vs rigid: 20%, 95%CI: 22–82%) possibly due to confounding due to etiology in adults treated with flexible, a smaller difference was seen in pediatrics (flexible: 36%, pediatric: 32%). Safety profiles were acceptable for both techniques, with a certain degree of variability for complications (flexible 2%, rigid 18%) and death (flexible 1%, rigid 3%) in pediatrics as well as complications (rigid 9%, flexible 13%), death (flexible 4%, rigid 6%) and intra-operative bleeding events (rigid 6%, flexible 8%) in adults. No clear superiority in efficacy could be depicted between flexible and rigid ETV for hydrocephalus treatment. Safety profiles varied by age but were acceptable for both techniques. Well-designed comparative studies are needed to assess the optimal endoscopic treatment option for hydrocephalus.

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