Double Cover Research Articles

Double Covering 모형을 활용한 인천광역시 소방시설 최적위치 선정에 관한 연구

The purpose of this study is to find the optimal locations of fire fighting facilities in Incheon to prevent the spread of accidental fires and efficiently extinguish them. In the event of a large fire difficult to cope with in one fire fighting facility, additional support from nearby facilities will be necessary. The model proposed in this study firstly ensures that all demand nodes in a network will be able to be reached from the minimum number of facilities in a given time. At the same time, we locate the given number of facilities so that they can cover as many demand nodes as possible multiple times. This problem can be considered as a facility location problem which aims at maximizing the number of demand nodes that are covered at least twice while minimizing the number of facilities needed. The proposed model is applied to conduct a case study using road network information and administrative district data in Incheon.

Low-cycle reciprocating loading test of Earthquake-resilient prefabricated steel frame with double FCPs

As an important component, the mechanical properties of the prefabricated beam-column steel joints have an effect on the mechanical mechanism of the whole frame structure system. According to the concept of replaceable post-earthquake and plastic damage control, the earthquake-resilient prefabricated beam-column steel joint with double flange cover plates (ERPBJ with double FCPs) has been proposed. To investigate the overall performance of the new steel frame with the new joint, four frame specimens are designed, and low-cycle reciprocating loading test and low cycle fatigue test had been carried out on them. The influence of the number of bolts, width of weakened dog-bone, post-earthquake repairability and different loading protocols have been studied. The failure mode, hysteretic curve, skeleton curve, the displacement ductility coefficient, the equivalent viscous damping coefficient have been obtained. The study results shows that the new earthquake-resilient prefabricated steel frame (ERPSF) with double FCPs have the advantage of controlling the damage positions. The plastic damage occurs on the replaceable FCPs, which ensures the structural performance, and the main structural components don not undergo plastic deformation. The decrease of the number of bolts will make the slip of FCPs more obvious, which will lead to the failure to fully utilize the bearing capacity of the FCP and reduce the ultimate load of the frame, but will improve the ductility and energy dissipation capacity of the frame. The behavior of ERPSF with double FCPs is stable under low cycle fatigue loading test and many repair tests, which indicates that the ERPBJ with double FCPs can be used as a damper in the frame structure system.

Numerical Study of a Basin Type Solar Still with a Double Glass Cover Under Winter Conditions

A numerical analysis of a basin-type solar still with a double glass cover is done under winter circumstances of solar radiation, ambient temperature, and wind speed. Equations defining thermal balances of different components of traditional and double glass cover solar stills are used to describe the physical issue, which is then solved using the Gauss-Seidel numerical technique. The effects of solar radiation, ambient temperature, and wind speed on the daily production, internal efficiency, and overall performance of solar stills are calculated and illustrated. The findings demonstrate that a solar still with a double-glass cover is more productive and efficient than a solar still with a single glass cover.

A splitting into the double cover of SL$$(3,\mathbb {R})$$

We provide a formula for the splitting of a congruence subgroup of SL\((3,\mathbb {R})\) into the double cover of SL\((3,\mathbb {R})\) in terms of Plücker coordinates. This new formula is then used to prove that the splitting satisfies a twisted multiplicativity. This formula has applications to the computation of Fourier coefficients of Eisenstein series on the double cover of SL(3) over \(\mathbb {Q}\).

Dirac quantum walks with conserved angular momentum

A quantum walk (QW) simulating the flat \((1 + 2)\)D Dirac equation on a spatial polar grid is constructed. Because fermions are represented by spinors, which do not constitute a representation of the rotation group \({\mathrm{SO}}(3)\), but rather of its double cover \({\mathrm{SU}}(2)\), the QW can only be defined globally on an extended spacetime where the polar angle extends from 0 to \(4 \pi \). The coupling of the QW with arbitrary electromagnetic fields is also presented. Finally, the cylindrical relativistic Landau levels of the Dirac equation are computed explicitly and simulated by the QW.

Voronoï Summation for Half-Integral Weight Automorphic Forms

Abstract A general Voronoï summation formula for the (metaplectic) double cover of $\operatorname{GL}_2$ is derived via the representation theoretic framework à la Ichino–Templier. The identity is also formulated classically and used to establish Voronoï summation formulae for half-integral weight modular forms and Maaß forms.

A special configuration of 12 conics and generalized Kummer surfaces

A generalized Kummer surface X obtained as the quotient of an abelian surface by a symplectic automorphism of order 3 contains a $$9\mathbf{A}_{2}$$ -configuration of $$(-2)$$ -curves. Such a configuration plays the role of the $$16\mathbf{A}_{1}$$ -configurations for usual Kummer surfaces. In this paper we construct 9 other such $$9\mathbf{A}_{2}$$ -configurations on the generalized Kummer surface associated to the double cover of the plane branched over the sextic dual curve of a cubic curve. The new $$9\mathbf{A}_{2}$$ -configurations are obtained by taking the pullback of a certain configuration of 12 conics which are in special position with respect to the branch curve, plus some singular quartic curves. We then construct some automorphisms of the K3 surface sending one configuration to another. We also give various models of X and of the generic fiber of its natural elliptic pencil.

D(n)-quintuples with square elements

For an integer n, a set of m distinct nonzero integers {a_1,a_2,...,a_m} such that a_i a_j+n is a perfect square for all 0<i<j<m+1, is called a D(n)-m-tuple. In this paper, we show that there are infinitely many essentially different D(n)-quintuples with square elements. We obtained this result by constructing genus one curves on a certain double cover of A^2 branched along four curves.

2 × 2 Matrices: Manifolds, Realizations, Applications

Both geometric and wave optical models, as well as classical and quantum mechanics, realize linear transformations with matrices; for plane optics, these are 2×2 and of unit determinant. Students and some researchers could assume that the structure of this matrix group is fairly evident and hardly interesting. However, the properties and applications even of this lowest 2×2 case are already unexpectedly rich. While in mechanics they cover classical angular momentum, quantum spin, and represent ‘2+1’ relativity, in optical models they lead from the geometrical description of light propagation in the paraxial regime to wave optics via linear canonical transforms requiring a more penetrating view of their manifold structure and multiple covers. The purpose of this review article is to highlight the topological space of 2×2 matrices as it applies to classical versus quantum and wave models, to underline how the latter requires the double cover of the former, thus using 2×2 matrices as an alternative viewpoint of the quantization process, beside the traditional characterization by commutation and non-commutations of position and momentum.

Achieving tree canopy cover targets: A case study of Bristol, UK

Many cities are increasing urban canopy cover to mitigate the impacts of urbanisation and climate change. Ambitious canopy cover targets are being implemented, with little consideration on how best to achieve them. The City of Bristol has recently published a One City Plan, which includes a target to double tree canopy cover by 2045. This study aims to investigate its feasibility, and explore different planting scenarios to achieve the target and maximise ecosystem service delivery. Using an existing i-Tree Eco assessment of the urban forest, i-Tree Forecast was used to project future urban forest growth under a number of different user-defined planting scenarios. Sixteen scenarios were forecasted over 27 years to test a variety of approaches. Tree stock size and number, timing of planting and annual mortality rates were varied to test the performance of each scenario. Planting 18,000 large tree stock, equivalent to ‘heavy standards’ every year for 27 years provided the most feasible scenario in balancing canopy cover, leaf area index and pollutant removal whilst providing a stable population. This increased to 44,000 trees per year assuming an annual mortality rate of 3 % more typical of urban areas, demonstrating the importance of good stewardship. The size of planted tree and timing of planting had a strong impact on the development of canopy cover. It was concluded that the One City Plan target is feasible if the planting rate is increased to at least 18,000 large tree stock from the current 10,000 trees per year.

Abelianisation of logarithmic mathfrak {sl}_2-connections

We prove a functorial correspondence between a category of logarithmic mathfrak {sl}_2-connections on a curve {mathsf {X}} with fixed generic residues and a category of abelian logarithmic connections on an appropriate spectral double cover . The proof is by constructing a pair of inverse functors pi ^text {ab}, pi _text {ab}, and the key is the construction of a certain canonical cocycle valued in the automorphisms of the direct image functor pi _*.

Effectiveness of Various Cast Covers in the Pediatric Population

Purpose: We explore the efficacy of different options as well as their cost across growing age cohorts encountered in a pediatric practice.&#x0D; Methods: Short arm casts were applied to mannequin models representing the arms of pediatric patients ages 3, 6, and 12 years old. The mass of each cast was then measured in grams. Casts were then completely submerged in water for 1 minute and the difference in mass was calculated. This was repeated six times per cast cover group across for all three age groups. There was a control group without a cast cover and eight additional groups of various cast cover types. Effectiveness of a cast was subjectively determined based on amount of absorption compared to the starting mass, and this was compared among the various groups using a non-parametric statistical test.&#x0D; Results: For the different cast cover types across all age groups, the Kruskall-Wallis test was used to analyze the entire dataset. A single plastic bag with duct tape was the most effective in reducing absorption (mean of 3.2 g absorption, 4.4 g SD). The results for the remaining cast covers were as follows. Many, but not all, of the eight groups had less absorption than the control with statistical significance at an alpha level of 0.05. These groups included the double plastic bag rubber band cover (p=0.0112), single plastic bag with duct tape cover (p&lt;0.0001), DryPro (p&lt;0.0001), Bloccs (p&lt;0.0001), Walgreens (p=0.0010), and Freedom covers (p&lt;0.0001). The plastic bag with duct tape cover additionally had significantly less absorption than the Press N Seal. (p=0.0045). The Curad group was found to not be statistically different from the control; in addition, the DryPro (p=0.0049), Bloccs (p&lt;0.0001), Freedom (p=0.0031), and plastic bag with duct tape (p&lt;0.0001) covers had significantly less absorption than this cover. Finally, a cost analysis was performed and demonstrated that a single plastic bag with duct tape was found to be the most cost efficient in theory, but the Walgreens cast cover was least expensive in actual cost.&#x0D; Conclusions: Our study indicated that a single plastic bag with duct tape was both one of the most effective cast covers at reducing absorption as well as one of the most cost effective across all age groups.&#x0D; Significance: The use of a single plastic bag with duct tape was both one of the most effective cast covers at reducing absorption as well as one of the most cost-effective across all age groups.

Spinoriality of orthogonal representations of GLn(𝔽q)

We determine which orthogonal representations V of GL(n,q) lift to the double cover Pin(V ) of the orthogonal group O(V ). We cover all n and prime powers q, except for (n; q) =(3,4).

Maximal families of nodal varieties with defect

In this paper we prove that a nodal hypersurface in mathbf {P}^4 with positive defect has at least (d-1)^2 nodes, and if it has at most 2(d-2)(d-1) nodes and dge 7 then it contains either a plane or a quadric surface. Furthermore, we prove that a nodal double cover of mathbf {P}^3 ramified along a surface of degree 2d with positive defect has at least d(2d-1) nodes. We construct the largest dimensional family of nodal degree d hypersurfaces in mathbf {P}^{2n+2} with positive defect for d sufficiently large.

Determining The Need for Fire Stations by Backup Double Covering Approach and Location Selection: The Case of Trabzon City

İtfaiye istasyonları kentsel alanda can ve mal güvenliğini sağlayan acil hizmet birimleridir. Bu hizmetin ihtiyaca hızlı yanıt verecek şekilde yüksek hizmet düzeyi ile sunulması kamu güvenliği açısından çok önemlidir. Ancak, imar mevzuatında itfaiye istasyonlarının planlanmasına yönelik herhangi bir hükme yer verilmediğinden, imar planlarında ve uygulamada itfaiye istasyonlarının sayısına, büyüklüklerine ve konumlarına ilişkin kararlar yetkili belediyenin takdirine bırakılmıştır. Oysa, itfaiye istasyonlarının planlanmasına ilişkin literatür incelendiğinde, tepki süresi, kapsama alanı, nüfus vb. ölçütler dikkate alınarak kent bütününde itfaiye istasyonlarının planlanması önerilmektedir. Bu çalışmanın amacı; Yedek Çift Kapsama yaklaşımıyla, tüm planlama alanına 5 dakika tepki süresi içinde hizmet verilebilecek ve mahallenin yangın risk sınıfına göre literatürdeki 5, 8, 10, 15 dakika erişim süreleri içinde ikinci bir itfaiye istasyonunun yedek kapsamında olacak şekilde en az itfaiye istasyon sayısını ve bu istasyonlara uygun kamusal alanları yürürlükteki nazım imar planında belirlemektir. Trabzon’un merkez ilçesi Ortahisar imar planı sınırları, çalışma alanı olarak seçilmiştir. Çalışma kent içinde itfaiye istasyonu ihtiyacının belirlenmesine ve yer seçimi sürecine katkı sağlayacaktır. Çalışma sonucunda, var olan itfaiye istasyonun mevcut yerinde kalması gerektiği, kentin doğusunda ve batısında iki itfaiye istasyonuna daha ihtiyaç olduğu ve itfaiye istasyonlarının planlanmasına yönelik olarak Mekânsal Planlar Yapım Yönetmeliğinde düzenlemeler yapılması gerektiği sonuçlarına varılmıştır.

Rank one sheaves over quaternion algebras on Enriques surfaces

Abstract Let X be an Enriques surface over the field of complex numbers. We prove that there exists a nontrivial quaternion algebra 𝓐 on X. Then we study the moduli scheme of torsion free 𝓐-modules of rank one. Finally we prove that this moduli scheme is an étale double cover of a Lagrangian subscheme in the corresponding moduli scheme on the associated covering K3 surface.

Higher Coverings of Racks and Quandles—Part II

This article is the second part of a series of three articles, in which we develop a higher covering theory of racks and quandles. This project is rooted in M. Eisermann’s work on quandle coverings, and the categorical perspective brought to the subject by V. Even, who characterizes coverings as those surjections which are categorically central, relatively to trivial quandles. We extend this work by applying the techniques from higher categorical Galois theory, in the sense of G. Janelidze, and in particular we identify meaningful higher-dimensional centrality conditions defining our higher coverings of racks and quandles. In this second article (Part II), we show that categorical Galois theory applies to the inclusion of the category of coverings into the category of surjective morphisms of racks or of quandles. We characterise the induced Galois-theoretic concepts of trivial covering, normal covering and covering in this two-dimensional context. The latter is described via our definition and study of double coverings, also called algebraically central double extensions of racks (and quandles). We define a suitable and well-behaved commutator which captures the zero-, one- and two-dimensional concepts of centralization in the category of quandles. We keep track of the links with the corresponding concepts in the category of groups.

Numerical evaluation of the thermal performance of different types of double glazing flat-plate solar air collectors

As the main source of heat loss of flat-plate solar air collectors (FPSACs), single glazing cover reduces the thermal performance of FPSAC. This situation becomes serious when the ambient temperature is low or the inlet temperature is high. A double glass cover with good thermal insulation is a good solution. This work aims to investigate the thermal performance of double glazing FPSAC at low ambient temperature and high inlet temperature. The thermal performance of four FPSACs with single glazing (Model 1), double glazing filled with air (Model 2), double glazing filled with argon (Model 3), and vacuum glazing (Model 4) as the glass cover at different ambient temperatures, different heat transfer air (HTA) inlet temperatures, and different HTA volume flow rates are studied and compared. Result demonstrates that Models 2, 3, and 4 have better thermal performance at low ambient temperature and high inlet temperature compared with Model 1. When the inlet temperature is 65 °C and ambient temperature is −10 °C, the thermal efficiencies of Models 2, 3, and 4 are 1.65, 1.72, and 2.29 times higher than that of Model 1, respectively. The efficiency factor and total heat loss coefficient of Model 4 are 0.62707 and 2.21745, respectively.

The fibers of the ramified Prym map

We study the ramified Prym map [Formula: see text] which assigns to a ramified double cover of a smooth irreducible curve of genus [Formula: see text] ramified in [Formula: see text] points the Prym variety of the covering. We focus on the six cases where the dimension of the source is strictly greater than the dimension of the target giving a geometric description of the generic fiber. We also give an explicit example of a totally geodesic curve which is an irreducible component of a fiber of the Prym map [Formula: see text].

Skeletons of Prym varieties and Brill–Noether theory

We show that the non-Archimedean skeleton of the Prym variety associated to an unramified double cover of an algebraic curve is naturally isomorphic (as a principally polarized tropical abelian variety) to the tropical Prym variety of the associated tropical double cover. This confirms a conjecture by Jensen and the first author. We prove a new upper bound on the dimension of the Prym-Brill-Noether locus for generic unramified double covers of curves with fixed even gonality on the base. Our methods also give a new proof of the classical Prym-Brill-Noether Theorem for generic unramified double covers that is originally due to Welters and Bertram.