Thermally Actuated Hierarchical Lattices With Large Linear and Rotational Expansion

2019 ◽  
Vol 86 (11) ◽  
Author(s):  
Hang Xu ◽  
Amr Farag ◽  
Ruizhe Ma ◽  
Damiano Pasini
Keyword(s):  
Numerical Analysis ◽  
Solid Mechanics ◽  
Global Scale ◽  
Skew Angle ◽  
Temperature Changes ◽  
Initial Height ◽  
Working Principle ◽  
Hierarchical Lattices ◽  
Thermally Actuated ◽  
Definition Of

Abstract This paper presents thermally actuated hierarchical metamaterials with large linear and rotational motion made of passive solids. Their working principle relies on the definition of a triangular bi-material unit that uses temperature changes to locally generate in its internal members distinct rates of expansion that translate into anisotropic motions at the unit level and large deployment at the global scale. Obtained from solid mechanics theory, thermal experiments on fabricated proof-of-concepts and numerical analysis, the results show that introducing recursive patterns of just two orders of the hierarchy is highly effective in amplifying linear actuation at levels of nearly nine times the initial height, and rotational actuation of almost 18.5 times the initial skew angle.

Global assessment for reduction of solar photovoltaic potential due to meteorological and geomorphological limiting factors

2021 ◽  
Author(s):  
Mustajab Ali ◽  
Hyungjun Kim
Keyword(s):  
Northern Hemisphere ◽  
Clean Energy ◽  
Global Scale ◽  
Limiting Factors ◽  
Solar Photovoltaic ◽  
Solar Pv ◽  
Temperature Changes ◽  
Cell Efficiency ◽  
Maximum Reduction ◽  
Pv Cell

<p>Solar Photovoltaic (PV) has the potential to fulfill a considerable amount of growing electricity demands worldwide.  In addition, being neat and clean, it can help to keep the greenhouse gases emission within safe limits. This resource needs a substantial amount of area for its sitting to supply the required amount of electricity. Such an area mainly depends on the available solar resource which is mainly the function of the local environment where PV is installed. Although some previous studies exist at the global scale, however, they have not comprehensively considered environmental (e.g., temperature, dust deposition, and snow) limiting factors that affect the actual solar PV yield. This study addresses such shortcomings and deals with all limiting factors simultaneously to provide a reliable assessment of potential PV performance at a global scale. PV cell efficiency is reduced due to an increase in resistance between cells at a temperature above a certain limit. Meanwhile, the accumulation of soil (dust) and snow on PV modules are also proven to limit the solar PV resources as it tends to block the incoming solar radiation. Lastly, the geomorphological parameter, which is an arrangement of a PV module to face the sun, is also shown to change its power output.</p><p>PV cell efficiency corrections for temperature changes, soil, and snow covers are applied using the biased corrected data from Global Soil Wetness Project 3 (GWSP3), CanSISE Observation-Based Ensemble of Northern Hemisphere Terrestrial Snow Water Equivalent, Version 2 from National Snow and Ice Data Center (nsidc), and TERRA/MODIS Aerosol Optical Thickness data available from NASA Earth Observations (NEO). The daily mean solar climatological values near the Earth’s surface for the last 14 years (2001–2014) with global coverage of 0.5º x0.5º are used in the analysis. The results have demonstrated that PV performance is affected by temperature increase, soil, snow, and varying tilt-angles. An annual maximum reduction of 5.7% in the total solar PV resource is seen in the Middle East due to the temperature changes. Likewise, a maximum loss of 6.45% in the total solar PV resource is witnessed for soil deposition for Sub-Saharan Africa. A higher reduction (~20%) is shown by snow covers for Russia and Canada in the upper Northern Hemisphere. In addition, a decline of 5–7% is observed for variation in the solar PV tilt-angles in comparison to optimum ones. As a whole, a maximum reduction of 19.45% in the total solar PV resource is found, which leads to a higher coefficient of determination (R<sup>2</sup>= 0.78) than uncorrected estimation (R<sup>2</sup>=0.67). This study will be helpful for household as well as large scale solar schemes and may contribute particularly to achieving the UN SDG No. 07 — Affordable and Clean Energy — and No. 13 — Climate Action — quantitatively.</p>

Etude taxonomique d'entérobactéries appartenant ou apparentées à l'espèce Escherichia coli

1981 ◽  
Vol 27 (1) ◽  
pp. 98-106 ◽  
Author(s):  
F. Gavini ◽  
D. Izard ◽  
P. A. Trinel ◽  
B. Lefebvre ◽  
H. Leclerc
Keyword(s):  
Escherichia Coli ◽  
Numerical Analysis ◽  
Dna Hybridization ◽  
Dna Relatedness ◽  
E Coli ◽  
Definition Of

Phenetic (numerical analysis) and genetic (DNA–DNA hybridization) studies were carried out on strains belonging or related to the species Escherichia coli. They have shown the diversity of its phenotypes, by the presence of plasmidic characters (citrate+, urease+, H2S+, tetrathionate reductase+, raffinose+, and saccharose+). New strains related phenetically to E. coli are also individualized. They showed less than 30% DNA relatedness with E. coli. A new definition of E. coli is presented.

Designing for a green chemistry future

Science ◽  
2020 ◽  
Vol 367 (6476) ◽  
pp. 397-400 ◽  
Author(s):  
Julie B. Zimmerman ◽  
Paul T. Anastas ◽  
Hanno C. Erythropel ◽  
Walter Leitner
Keyword(s):  
Green Chemistry ◽  
Molecular Level ◽  
Positive Impact ◽  
Systems Design ◽  
Global Scale ◽  
Design Stage ◽  
Sustainable Society ◽  
Material Basis ◽  
Chemical Products ◽  
Definition Of

The material basis of a sustainable society will depend on chemical products and processes that are designed following principles that make them conducive to life. Important inherent properties of molecules need to be considered from the earliest stage—the design stage—to address whether compounds and processes are depleting versus renewable, toxic versus benign, and persistent versus readily degradable. Products, feedstocks, and manufacturing processes will need to integrate the principles of green chemistry and green engineering under an expanded definition of performance that includes sustainability considerations. This transformation will require the best of the traditions of science and innovation coupled with new emerging systems thinking and systems design that begins at the molecular level and results in a positive impact on the global scale.

scholarly journals Interactions between snow cover and evaporation lead to higher sensitivity of streamflow to temperature

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Antônio Alves Meira Neto ◽  
Guo-Yue Niu ◽  
Tirthankar Roy ◽  
Scott Tyler ◽  
Peter A. Troch
Keyword(s):  
Snow Cover ◽  
Water Availability ◽  
Water Demand ◽  
Water Surface ◽  
Free Water ◽  
Potential Evaporation ◽  
Temperature Changes ◽  
Conventional Methods ◽  
Definition Of ◽  
Higher Sensitivity

AbstractEstimates of potential evaporation often neglect the effects of snow cover on evaporation process. Here, we present a definition of potential evaporation that explicitly accounts for landscapes that are partially covered by snow. We show that, in the presence of snowpack, our evaporation estimates differ from conventional methods that assume evaporation from a free water surface. Specifically, we find that conventional methods overestimate potential evaporation as well as aridity, taken as the ratio of atmospheric water demand to supply, in landscapes where snowfall is significant. With dwindling snow-cover, actual aridity increases, which could explain the reduction in streamflow with decreasing snowfall. We suggest that streamflow, and hence water availability, is more sensitive to temperature changes in colder than in warmer regions.

scholarly journals Risks of collective investment undertakings in the context of global capital markets

2020 ◽  
Vol 74 ◽  
pp. 01025
Author(s):  
Daniela Pfeiferová ◽  
Ivana Kuchařová
Keyword(s):  
Significant Proportion ◽  
Global Scale ◽  
Interest Rate Risk ◽  
Financial Risks ◽  
Counterparty Risk ◽  
Investment Funds ◽  
Specific Investment ◽  
Equity Risk ◽  
Doing Business ◽  
Definition Of

In the context of globalization, international institutional investors have taken over a significant proportion of global investment assets. Among this group also belong to collective investment undertakings whose primary motive is regulated by collecting funds from indeterminate group of natural persons and legal persons for the purpose of doing business on a global scale. As part of their reporting obligations, these entities are required to report on the risks associated with the investment and how to eliminate them. Investment firms must use risk management methods that allow these risks to be identified at any time. The main risks associated with investments in collective investment funds include global financial risks: interest rate risk, currency risk, equity risk, credit risk, counterparty risk, liquidity risk, operational risk and political risk. This article deals with the definition of specific investment risks and the options for their elimination for collective investment entities. The main goal of the article is to recommend the elimination of these risks based on the identified risks associated with collective investment.

Numerical Analysis of Lining Temperature Field of Hydraulic Tunnel under the Highway

2010 ◽  
Vol 163-167 ◽  
pp. 1505-1509
Author(s):  
Xiao Yun Jia ◽  
Bao Long Lin
Keyword(s):  
Temperature Field ◽  
Numerical Analysis ◽  
Structural Characteristics ◽  
Crack Control ◽  
Temperature Changes ◽  
Finite Element Software ◽  
Concrete Crack ◽  
Geological Conditions ◽  
North Water ◽  
The Difference

Based on the geological conditions of culvert of the South to North Water Transfer Project, lining temperature field of hydraulic tunnel for crack control is simulated by finite element software—ANSYS. According to numerical analysis results of lining temperature field, considering terrain condition, structural characteristics and climate, some engineering measures are taken during construction. Internal temperature of concrete is controlled effectively, concrete crack caused by temperature changes is solved successfully, and construction quality is assured. The difference of measuring data in-situ and calculating data is very small, which illustrate that calculated model is correct and parameters are reasonable. The results can act as reference for the design and construction of similar projects later.

scholarly journals Notes on Early Land Plants Today. 58. Historical circumscription of Schistochilaceae (Marchantiophyta) and a new combination in Schistochila

Phytotaxa ◽  
2014 ◽  
Vol 173 (1) ◽  
pp. 91 ◽  
Author(s):  
Xiaolan He ◽  
David Glenny ◽  
Lars Söderström ◽  
Anders Hagborg ◽  
Matt Von Konrat
Keyword(s):  
Pacific Islands ◽  
Global Scale ◽  
New Combination ◽  
Generic Level ◽  
Tropical Mountain ◽  
Prominent Component ◽  
Extant Species ◽  
The Family ◽  
Definition Of ◽  
One New Species

The family Schistochilaceae Buch (1928: 9) consists of approximately 80 extant species. More than two-thirds of its diversity occurs in temperate to subantarctic South America and Australasia, and nearly one third in the tropical mountain forests of Southeast Asia and the western Pacific Islands. The plants of Schistochilaceae are usually robust and form a prominent component of the ground layer of cool temperate forests or upper montane tropical forests, commonly forests in which Nothofagus is a dominant genus.  The first species of the family, published as Jungermannia appendiculata Hooker (1818: tab. 15), Jungermannia glaucescens Hooker (1818: tab. 39), Jungermannia lamellata Hooker (1818: tab. 49), Jungermannia nobilis Hooker (1818: tab. 11), Jungermannia sphagnoides Schwägrichen (1814: 23) and Jungermannia thouarsii Hooker (1818: tab. 48), were described during 1814–1818. Dumortier established the genus Schistochila Dumortier (1835: 15) to accommodate the above mentioned species except Jungermannia glaucescens and Jungermannia sphagnoides, but he also added one new species, Schistochila pinnatifolia Dumortier (1835: 15) nom. inval. (ICN Art. 38.1(a); no description; McNeill et al. 2012). The definition of Schistochilaceae has remained largely unchanged since it was separated from Scapaniaceae Migula (1904: 479) by Buch (1928) and then later Balantiopsaceae Buch (1955: 23). The presence of magenta rhizoids, winged and complicate-bilobed leaves with smaller dorsal lobes, a shoot calyptra elaborated into a well-developed coelocaule, and a cylindrical sporophyte capsule with straight valves generally defines the family. These features, to a great extent, isolate Schistochilaceae from the rest of the leafy liverworts. Therefore, taxonomic rearrangements or revisions, based on morphological investigations, have mostly been at generic level or below (Grolle 1966, 1968, Hässel 1973, Schuster 1971a, Schuster & Engel 1977, 1985). So far, taxonomic revisions have only been done at regional scales, a study at global scale is under way (Glenny et al., unpublished).

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