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Solar tracking

Donald G Bruns, Ronald D Bruns
The sky brightness was measured during the partial phases and during totality of the 21 August 2017 total solar eclipse. A tracking CCD camera with color filters and a wide-angle lens allowed measurements across a wide field of view, recording images every 10 s. The partially and totally eclipsed Sun was kept behind an occulting disk attached to the camera, allowing direct brightness measurements from 1.5° to 38° from the Sun. During the partial phases, the sky brightness as a function of time closely followed the integrated intensity of the unobscured fraction of the solar disk...
June 1, 2018: Applied Optics
Lele Peng, Shubin Zheng, Wei Xu, Li Xin
This article presents the data on photovoltaic (PV) system used different perturb and observe (P&O) methods under fast multi-changing solar irradiances. The mathematical modeling of the PV system and tangent error P&O method was discussed in our previous study entitled "A novel tangent error maximum power point tracking algorithm for photovoltaic system under fast multi-changing solar irradiances" by Peng et al. (2018) [1]. The data provided in this paper can be used directly without having to spend weeks to simulate the output performance...
April 2018: Data in Brief
Liliana Ruiz Diaz, Byron Cocilovo, Alexander Miles, Wei Pan, Pierre-Alexandre Blanche, Robert A Norwood
Hybrid thermal-PV solar trough collectors combine concentrated photovoltaics and concentrated solar power technology to harvest and store solar energy. In this work, the optical and mechanical requirements for optimal efficiency are analyzed using non-sequential ray tracing techniques. The results are used to generate opto-mechanical tolerances that can be compared to those of traditional solar collectors. We also explore ideas on how to relieve tracking tolerances for single-axis solar collectors. The objective is to establish a basis for tolerances required for the fabrication and manufacturing of hybrid solar trough collectors...
May 14, 2018: Optics Express
Clifford M Will
We point out the existence of a new general relativistic contribution to the perihelion advance of Mercury that, while smaller than the contributions arising from the solar quadrupole moment and angular momentum, is 100 times larger than the second-post-Newtonian contribution. It arises in part from relativistic "crossterms" in the post-Newtonian equations of motion between Mercury's interaction with the Sun and with the other planets, and in part from an interaction between Mercury's motion and the gravitomagnetic field of the moving planets...
May 11, 2018: Physical Review Letters
James H Diaz
Background: Coccidioidomycosis is a regionally endemic systemic mycosis with unique risk factors. Since people travel for business or pleasure, and often in conjunction with their avocations or hobbies, the objectives of this review were to describe these and other risk factors for coccidioidomycosis; to alert travel medicine clinicians to the different presenting manifestations of coccidioidomycosis; and to recommend effective treatment, disease control and prevention strategies. Methods: To meet the objectives of this review, Internet search engines were queried with the keywords as medical subject headings over the study period, 1970-2017...
January 1, 2018: Journal of Travel Medicine
Seongrok Seo, Seonghwa Jeong, Changdeuck Bae, Nam-Gyu Park, Hyunjung Shin
Despite the high power conversion efficiency (PCE) of perovskite solar cells (PSCs), poor long-term stability is one of the main obstacles preventing their commercialization. Several approaches to enhance the stability of PSCs have been proposed. However, an accelerating stability test of PSCs at high temperature under the operating conditions in ambient air remains still to be demonstrated. Herein, interface-engineered stable PSCs with inorganic charge-transport layers are shown. The highly conductive Al-doped ZnO films act as efficient electron-transporting layers as well as dense passivation layers...
May 22, 2018: Advanced Materials
Isla Rose Mary Barnard, Patrick Tierney, Catherine Louise Campbell, Lewis McMillan, Harry Moseley, Ewan Eadie, Christian Tom Alcuin Brown, Kenneth Wood
Non-melanoma and melanoma skin cancers are attributable to DNA damage caused by ultraviolet (UV) radiation exposure. One DNA photoproduct, the Cyclobutane Pyrimidine Dimer (CPD), is believed to lead to DNA mutations caused by UV radiation. Using radiative transfer simulations, we compare the number of CPDs directly induced by UV irradiation from artificial and natural UV sources (a standard sunbed and the midday summer Mediterranean sun) for skin types I and II on the Fitzpatrick scale. We use Monte Carlo Radiative Transfer (MCRT) modelling to track the progression of UV photons through a multi-layered three dimensional (3D) grid that simulates the upper layers of the skin...
May 12, 2018: Photochemistry and Photobiology
Rita Fontanella, Domenico Accardo, Rosario Schiano Lo Moriello, Leopoldo Angrisani, Domenico De Simone
This paper presents an innovative model for integrating thermal compensation of gyro bias error into an augmented state Kalman filter. The developed model is applied in the Zero Velocity Update filter for inertial units manufactured by exploiting Micro Electro-Mechanical System (MEMS) gyros. It is used to remove residual bias at startup. It is a more effective alternative to traditional approach that is realized by cascading bias thermal correction by calibration and traditional Kalman filtering for bias tracking...
May 7, 2018: Sensors
Abdel-Hamid K Osman, Thomas Caceci, Mitchiko Shintani
Programmed cell death is a fundamental event that takes place during organ development and plays an important role in cellular homeostasis. Since various body organs of the camel are under high ecological and physiological stress during food and water deprivation, desiccation, and the long exposure to solar radiation in these desert nomads, we aimed to examine the immunohistochemical expression of apoptosis-related biomarkers in some of its normal body organs to illustrate a basic track for further pathological investigation...
May 2018: Acta Histochemica
Denis Leshchev, Tobias C B Harlang, Lisa A Fredin, Dmitry Khakhulin, Yizhu Liu, Elisa Biasin, Mads G Laursen, Gemma E Newby, Kristoffer Haldrup, Martin M Nielsen, Kenneth Wärnmark, Villy Sundström, Petter Persson, Kasper S Kjær, Michael Wulff
Recent years have seen the development of new iron-centered N-heterocyclic carbene (NHC) complexes for solar energy applications. Compared to typical ligand systems, the NHC ligands provide Fe complexes with longer-lived metal-to-ligand charge transfer (MLCT) states. This increased lifetime is ascribed to strong ligand field splitting provided by the NHC ligands that raises the energy levels of the metal centered (MC) states and therefore reduces the deactivation efficiency of MLCT states. Among currently known NHC systems, [Fe(btbip)2 ]2+ (btbip = 2,6-bis(3- tert -butyl-imidazol-1-ylidene)pyridine) is a unique complex as it exhibits a short-lived MC state with a lifetime on the scale of a few hundreds of picoseconds...
January 14, 2018: Chemical Science
Lijian Zuo, Xueliang Shi, Sae Byeok Jo, Yun Liu, Fracis Lin, Alex K-Y Jen
Limited by the various inherent energy losses from multiple channels, organic solar cells show inferior device performance compared to traditional inorganic photovoltaic techniques, such as silicon and CuInGaSe. To alleviate these fundamental limitations, an integrated multiple strategy is implemented including molecular design, interfacial engineering, optical manipulation, and tandem device construction into one cell. Considering the close correlation among these loss channels, a sophisticated quantification of energy-loss reduction is tracked along with each strategy in a perspective to reach rational overall optimum...
April 2018: Advanced Materials
Ali Jasim Ramadhan
In this paper, we present a wearable smart system to help visually impaired persons (VIPs) walk by themselves through the streets, navigate in public places, and seek assistance. The main components of the system are a microcontroller board, various sensors, cellular communication and GPS modules, and a solar panel. The system employs a set of sensors to track the path and alert the user of obstacles in front of them. The user is alerted by a sound emitted through a buzzer and by vibrations on the wrist, which is helpful when the user has hearing loss or is in a noisy environment...
March 13, 2018: Sensors
Grant Matthews
A need to gain more confidence in computer model predictions of coming climate change has resulted in greater analysis of the quality of orbital Earth radiation budget (ERB) measurements being used today to constrain, validate, and hence improve such simulations. These studies conclude from time series analysis that for around a quarter of a century, no existing satellite ERB climate data record is of a sufficient standard to partition changes to the Earth from those of un-tracked and changing artificial instrumentation effects...
March 1, 2018: Applied Optics
Rui Fang, Shaohang Wu, Weitao Chen, Zonghao Liu, Shasha Zhang, Rui Chen, Youfeng Yue, Linlong Deng, Yi-Bing Cheng, Liyuan Han, Wei Chen
Stability issues and high material cost constitute the biggest obstacles of a perovskite solar cell (PVSC), hampering its sustainable development. Herein, we demonstrate that, after suitable surface modification, the low-cost cerium oxide (CeO x ) nanocrystals can be well dispersed in both polar and nonpolar solvents and easily processed into high-quality electron transport layers (ETLs). The inverted PVSC with the configuration of "NiMgLiO/MAPbI3 /[6,6]-phenyl-C61 -butyric acid methyl ester (PCBM)/CeO x " has achieved a high efficiency up to 18...
March 27, 2018: ACS Nano
Bilge Baytekin, S Doruk Cezan, H Tarık Baytekin, Bartosz A Grzybowski
Although plants are typically not considered an inspiration for designing motile robots, they do perform a variety of intricate motion patterns, including diurnal cycles of sun tracking (heliotropism) and leaf opening (nyctinasty). In real plants, these motions are controlled by complex, feedback-based biological mechanisms that, to date, have been mimicked only in computer-controlled artificial systems. This work demonstrates both heliotropism and nyctinasty in a system in which few simple, but strategically positioned thermo-responsive springs and lenses form a feedback loop controlling these motions and substantiating a behavioral analogy to "plants...
February 2018: Soft Robotics
Christopher H Trisos, Giuseppe Amatulli, Jessica Gurevitch, Alan Robock, Lili Xia, Brian Zambri
Solar geoengineering is receiving increased policy attention as a potential tool to offset climate warming. While climate responses to geoengineering have been studied in detail, the potential biodiversity consequences are largely unknown. To avoid extinction, species must either adapt or move to track shifting climates. Here, we assess the effects of the rapid implementation, continuation and sudden termination of geoengineering on climate velocities-the speeds and directions that species would need to move to track changes in climate...
March 2018: Nature Ecology & Evolution
S Matthew Menke, Alexandre Cheminal, Patrick Conaghan, Niva A Ran, Neil C Greehnam, Guillermo C Bazan, Thuc-Quyen Nguyen, Akshay Rao, Richard H Friend
Donor-acceptor organic solar cells often show low open-circuit voltages (V OC ) relative to their optical energy gap (E g ) that limit power conversion efficiencies to ~12%. This energy loss is partly attributed to the offset between E g and that of intermolecular charge transfer (CT) states at the donor-acceptor interface. Here we study charge generation occurring in PIPCP:PC61 BM, a system with a very low driving energy for initial charge separation (E g -E CT  ~ 50 meV) and a high internal quantum efficiency (η IQE  ~ 80%)...
January 18, 2018: Nature Communications
Curtis D Mobley, Brian L Diffey
Atmospheric and oceanic radiative transfer models were used to compute spectral radiances between 285 and 400 nm onto horizontal and vertical plane surfaces over water. The calculations kept track of the contributions by the sun's direct beam, by diffuse-sky radiance, by radiance reflected from the sea surface and by water-leaving radiance. Clear, hazy and cloudy sky conditions were simulated for a range of solar zenith angles, wind speeds and atmospheric ozone concentrations. The radiances were used to estimate erythemal exposures due to the sun and sky, as well as from radiation reflected by the sea surface and backscattered from the water column...
January 8, 2018: Photochemistry and Photobiology
Daniel Monsivais, Asim Ghosh, Kunal Bhattacharya, Robin I M Dunbar, Kimmo Kaski
Timings of human activities are marked by circadian clocks which in turn are entrained to different environmental signals. In an urban environment the presence of artificial lighting and various social cues tend to disrupt the natural entrainment with the sunlight. However, it is not completely understood to what extent this is the case. Here we exploit the large-scale data analysis techniques to study the mobile phone calling activity of people in large cities to infer the dynamics of urban daily rhythms. From the calling patterns of about 1,000,000 users spread over different cities but lying inside the same time-zone, we show that the onset and termination of the calling activity synchronizes with the east-west progression of the sun...
November 2017: PLoS Computational Biology
Yasunari Tamai, Yeli Fan, Vincent O Kim, Kostiantyn Ziabrev, Akshay Rao, Stephen Barlow, Seth R Marder, Richard H Friend, S Matthew Menke
Rapid, long-range charge separation in polymer-fullerene organic solar cells (OSCs) enables electrons and holes to move beyond their Coulomb capture radius and overcome geminate recombination. Understanding the nature of charge generation and recombination mechanisms in efficient, nonfullerene-acceptor-based OSCs are critical to further improve device performance. Here we report charge dynamics in an OSC using a perylene diimide (PDI) dimer acceptor. We use transient absorption spectroscopy to track the time evolution of electroabsorption caused by the dipolar electric field generated between electron-hole pairs as they separate after ionization at the donor-acceptor interface...
December 26, 2017: ACS Nano
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