scholarly journals On embedding of graphs into euclidean spaces of small dimension

1992 ◽  
Vol 56 (1) ◽  
pp. 1-8 ◽  
Author(s):  
J Reiterman ◽  
V Rödl ◽  
E S̆in̆ajová
Keyword(s):  
Small Dimension ◽  
Euclidean Spaces

Current Highlights About the Safety of Inorganic Nanomaterials in Healthcare

2019 ◽  
Vol 26 (12) ◽  
pp. 2147-2165 ◽  
Author(s):  
Luana Perioli ◽  
Cinzia Pagano ◽  
Maria Rachele Ceccarini
Keyword(s):  
Zinc Oxide ◽  
Inorganic Material ◽  
Small Dimension ◽  
Inorganic Materials ◽  
Intracellular Space ◽  
Increased Risk ◽  
Inorganic Nanomaterials ◽  
Materials Used ◽  
Health Field ◽  
Fundamental Requirement

: In recent years inorganic materials are largely present in products intended for health care. Literature gives many examples of inorganic materials used in many healthcare products, mainly in pharmaceutical field. : Silver, zinc oxide, titanium oxide, iron oxide, gold, mesoporous silica, hydrotalcite-like compound and nanoclays are the most common inorganic materials used in nanosized form for different applications in the health field. Generally, these materials are employed to realize formulations for systemic use, often with the aim to perform a specific targeting to the pathological site. The nanometric dimensions are often preferred to obtain the cellular internalization when the target is localized in the intracellular space. : Some materials are frequently used in topical formulations as rheological agents, adsorbents, mattifying agents, physical sunscreen (e.g. zinc oxide, titanium dioxide), and others. : Recent studies highlighted that the use of nanosized inorganic materials can represent a risk for health. The very small dimension (nanometric) until a few years ago represented a fundamental requirement; however, it is currently held responsible for the inorganic material toxicity. This aspect is very important to be considered as actually numerous inorganic materials can be found in many products available in the market, often dedicated to infants and children. These materials are used without taking into account their dimensional properties with increased risk for the user/patient. : This review deals with a deep analysis of current researches documenting the toxicity of nanometric inorganic materials especially those largely used in products available in the market.

scholarly journals Decentralized Voltage Optimization Based on the Auxiliary Problem Principle in Distribution Networks with DERs

2021 ◽  
Vol 11 (10) ◽  
pp. 4509
Author(s):  
Anna Rita Di Fazio ◽  
Chiara Risi ◽  
Mario Russo ◽  
Michele De Santis
Keyword(s):  
Distribution Systems ◽  
Auxiliary Problem ◽  
Optimization Procedure ◽  
Distribution Networks ◽  
Small Dimension ◽  
Quadratic Program ◽  
Voltage Profile ◽  
Distributed Energy ◽  
Auxiliary Problem Principle ◽  
Coordination Process

This paper addresses the problem of optimizing the voltage profile of radially-operated distribution systems by acting on the active and reactive powers provided by distributed energy resources (DERs). A novel voltage optimization procedure is proposed by adopting a decentralized control strategy. To this aim, a centralized voltage optimization problem (VOP), minimizing the distance of all the nodal voltages from their reference values, is firstly formulated as a strictly-convex quadratic program. Then, the centralized VOP is rewritten by partitioning the network into voltage control zones (VCZs) with pilot nodes. To overcome the lack of strictly convexity determined by the reduction to the pilot nodes, the dual centralized VOP working on the augmented Lagrangian function is reformulated and iteratively solved by the method of multipliers. Finally, a fully-distributed VOP solution is obtained by applying a distributed algorithm based on the auxiliary problem principle, which allows for solving in each VCZ a quadratic programming problem of small dimension and to drive the VCZ solutions toward the overall optimum by an iterative coordination process that requires to exchange among the VCZs only scalar values. The effectiveness and feasibility of the proposed method have been demonstrated via numerical tests on the IEEE 123-bus system.

scholarly journals Realization of frequency hopping characteristics of an epsilon negative metamaterial with high effective medium ratio for multiband microwave applications

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mohammad Tariqul Islam ◽  
Md. Moniruzzaman ◽  
Touhidul Alam ◽  
Md Samsuzzaman ◽  
Qutaiba A. Razouqi ◽  
...  
Keyword(s):  
Refractive Index ◽  
Low Cost ◽  
Frequency Hopping ◽  
Small Dimension ◽  
Effective Medium ◽  
Unit Cell ◽  
Negative Permittivity ◽  
Design System ◽  
Microwave Applications ◽  
Meander Line

AbstractIn this paper, a meander-lines-based epsilon negative (ENG) metamaterial (MTM) with a high effective medium ratio (EMR) and near-zero refractive index (NZI) is designed and investigated for multiband microwave applications. The metamaterial unit cell is a modification of the conventional square split-ring resonator in which the meander line concept is utilized. The meander line helps to increase the electrical length of the rings and provides strong multiple resonances within a small dimension. The unit cell of proposed MTM is initiated on a low-cost FR4 substrate of 1.5 mm thick and electrical dimension of 0.06λ × 0.06λ, where wavelength, λ is calculated at the lowest resonance frequency (2.48 GHz). The MTM provides four major resonances of transmission coefficient (S21) at 2.48, 4.28, 9.36, and 13.7 GHz covering S, C, X, and Ku bands. It shows negative permittivity, near-zero permeability, and near-zero refractive index in the vicinity of these resonances. The equivalent circuit is designed and modeled in Advanced Design System (ADS) software. The simulated S21 of the MTM unit cell is compared with the measured one and both show close similarity. The array performance of the MTM is also evaluated by using 2 × 2, 4 × 4, and 8 × 8 arrays that show close resemblance with the unit cell. The MTM offers a high effective medium ratio (EMR) of 15.1, indicating the design's compactness. The frequency hopping characteristics of the proposed MTM is investigated by open and short-circuited the three outer rings split gaps by using three switches. Eight different combinations of the switching states provide eight different sets of multiband resonances within 2–18 GHz; those give the flexibility of using the proposed MTM operating in various frequency bands. For its small dimension, NZI, high EMR, and frequency hopping characteristics through switching, this metamaterial can be utilized for multiband microwave applications, especially to enhance the gain of multiband antennas.

scholarly journals Potential of Small Culverts as Wildlife Passages on Forest Roads

2021 ◽  
Vol 13 (13) ◽  
pp. 7224
Author(s):  
Hsiang-Ling Chen ◽  
Erin E. Posthumus ◽  
John L. Koprowski
Keyword(s):  
Animal Movement ◽  
Small Dimension ◽  
Lynx Rufus ◽  
Tamiasciurus Hudsonicus ◽  
Red Squirrels ◽  
Forest Roads ◽  
Alternative Pathways ◽  
Slow Moving ◽  
Trail Cameras ◽  
Spermophilus Variegatus

Roads and traffic can cause animal mortality. Specifically, roads serve as barriers by impeding animal movement, resulting in demographic and genetic consequences. Drainage structures, such as culverts, can provide linkages between habitat patches. However, the potential of small culverts with diameters of <60 cm (e.g., wildlife passages that facilitate movement on forest roads) are relatively unknown. In this study, we used trail cameras to monitor the use of 14 small culverts, by mammals, along forest roads on Mt. Graham, home of the critically endangered Mt. Graham red squirrels (Tamiasciurus hudsonicus grahamensis), in southeastern Arizona, USA. From 2011 to 2013, we only recorded 20 completed road crossings through culverts. More than half of culvert uses were by striped skunks (Mephitis mephitis), followed by the rock squirrel (Spermophilus variegatus) and the bobcat (Lynx rufus). The Mt. Graham red squirrel was the only species that was common along the roads, but never crossed the roads. Culverts with higher usages were characterized by shorter culvert lengths and absence of accumulated soil inside the culverts. Our study shows that small-dimension drainage systems may provide alternative pathways for wildlife crossing roads, especially for slow moving and ground dwelling species. However, the potential of small culverts assisting wildlife crossings can only be maximized when culverts are accessible year-round.

scholarly journals Ancient solutions for Andrews’ hypersurface flow

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Peng Lu ◽  
Jiuru Zhou
Keyword(s):  
Ricci Flow ◽  
Mean Curvature ◽  
Mean Curvature Flow ◽  
Curvature Flow ◽  
Euclidean Spaces ◽  
Round Cylinder ◽  
Ancient Solutions ◽  
Singular Time

AbstractWe construct the ancient solutions of the hypersurface flows in Euclidean spaces studied by B. Andrews in 1994.As time {t\rightarrow 0^{-}} the solutions collapse to a round point where 0 is the singular time. But as {t\rightarrow-\infty} the solutions become more and more oval. Near the center the appropriately-rescaled pointed Cheeger–Gromov limits are round cylinder solutions {S^{J}\times\mathbb{R}^{n-J}}, {1\leq J\leq n-1}. These results are the analog of the corresponding results in Ricci flow ({J=n-1}) and mean curvature flow.

scholarly journals Equiangular lines in Euclidean spaces

2016 ◽  
Vol 138 ◽  
pp. 208-235 ◽  
Author(s):  
Gary Greaves ◽  
Jacobus H. Koolen ◽  
Akihiro Munemasa ◽  
Ferenc Szöllősi
Keyword(s):  
Euclidean Spaces ◽  
Equiangular Lines
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