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This paper presents a novel geometrical design of inserts to realize high-efficiency smooth-surface high-chatter-stability turning. Inserts with a nose radius are used in turning to realize a smooth surface since the theoretical surface roughness R t h = f 2 / (8 r) where f is the feed rate and r is the radius of the nose part. Since the size of the nose radius is limited because of the chatter stability, i.e. a large nose radius tends to cause chatter, the feed rate has to be kept small so that the acquired roughness is acceptable. Hence, the efficiency is limited. In this study, a novel turning insert geometry is proposed to realize high chatter stability along with a high efficiency and a smooth surface. The proposed insert geometry is verified by analyses and experiments. • Insert geometry to realize high efficiency, smooth surface, and high chatter stability. • Large nose radius and small effective regenerative cutting width are combined. • Higher gain margin and same surface roughness is realized compared to conventional inserts. [ABSTRACT FROM AUTHOR]

Abstract Let λ (D) be the A α spectral radius of digraph D , and let G n r be the set of digraphs with order n and dichromatic number r. In this paper, we characterize the digraph which has the maximal A α spectral radius in G n r. Moreover, we also determine the unique digraph which attains the maximum (resp. minimum) A α spectral radius among all strongly connected bicyclic digraphs. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we study the performance of Saitou and Nei''s neighbor-joining method for phylogenetic reconstruction. We show that the edge radius of the method is . This improves an result by Atteson [The performance of neighbor-joining methods of phylogenetic reconstruction, Algorithmica 25 (1999) 251–278] and Xu et al. [A lower bound on the edge radius of Saitou and Nei''s method for phylogenetic reconstruction, Inform. Process. Lett. 94(5) (2005) 225–230]. Previously, only an upper bound and a lower bound were known. [Copyright &y& Elsevier]

Abstract: Let T (n, d) be the set of trees on n vertices with diameter d. In this paper, the first spectral radii of trees in the set T (n, d) (3⩽ d ⩽ n −4) are characterized. [Copyright &y& Elsevier]

Abstract: In this paper we consider the following problem: Of all trees of order n with k pendant vertices (n, k fixed), which achieves the maximal spectral radius? We show that the maximal spectral radius is obtained uniquely at Tn,k, where Tn,k is a tree obtained from a star K1,k and k paths of almost equal lengths by joining each pendant vertex of K1,k to an end vertex of one path. We also discuss the spectral radius of Tn,k and get some results. [Copyright &y& Elsevier]

We study the spectral radius of graphs with n vertices and k cut edges. In this paper, we show that of all the connected graphs with n vertices and k cut edges, the maximal spectral radius is obtained uniquely at Knk, where Knk is a graph obtained by joining k independent vertices to one vertex of Kn-k. We also discuss the limit point of the maximal spectral radius. [Copyright &y& Elsevier]

By making use of detached eclipsing binaries with B-type components discovered by the OGLE and MACHO teams in the SMC and in the LMC, we give the value of the fractional radius above which circularization occurs. This critical radius is around 0.24–0.26, regardless of the mass, surface gravity or metallicity, and is consistent with that found by Giuricin et al. [A&A 134 (1984) 365] for galactic binaries. These empirical facts are shown to be consistent with Zahn''s [A&A 41 (1975) 329] theory of tidal dissipation. As a by-product of this study, we provide approximate stellar parameters of the average component of 148 binaries in the SMC and of up to 353 binaries (some of which might be non-detached) in the LMC, under the assumption of equal components. [Copyright &y& Elsevier]

• Most accurate geometry of attached mortar geometry for recycled aggregate concrete (RAC) modelling; • Comparative analysis with several attached mortar geometries; • Comparison of the mechanical behaviour of RAC with natural aggregate concrete (NAC). The geometry of the attached mortar present in recycled concrete aggregates influences the behaviour of recycled aggregate concrete, since this mortar is porous, rough and tends to increase the elongation of aggregate particles. These factors influence shape, volume, and complexity of the mesoscopic phases of concrete (including the interfacial transition zone), but studies on this topic so far have not realistically represented the geometry and mesoscopic phases of recycled aggregate concrete. This hinders a proper analysis of the effect of the attached mortar's geometry. This paper develops a mesoscopic model for recycled aggregate concrete, considering four types of attached mortar's geometry based on experimental observation. Concrete mixes numerically modelled with either: i) the four attached mortar's geometries combined on a mixed model (representative of real cases); or ii) a single type of attached mortar's geometry was analysed regarding the effect of the attached mortar's geometry on the compressive and tensile behaviour and on fracture development. The main findings of the paper are: (1) the geometry of the attached mortar is relevant to the behaviour of recycled aggregate concrete; (2) modelling the attached mortar as present in both ends of the larger radius of the recycled aggregate leads to more realistic results; (3) modelling the attached mortar as fully enclosing the recycled aggregate overestimates the mechanical properties. [ABSTRACT FROM AUTHOR]

• Kinematics of the vane-cam ring mechanism is defined analytically. • The admissibility of the vane geometry is defined. • Influence of vane tip radius and tip eccentricity is evaluated. • Effect of the cam ring profile is taken into account with a parametric study. This paper analyzes the kinematics of the vane-cam ring mechanism in balanced vane pumps, by considering both vanes with centered and not-centered circular tip. The motion of the vane, the position of the contact point and the evolution of the pressure angle are analytically determined in reference to a generic cam ring profile. The results of the kinematic analysis are used to obtain the constraints defining the admissibility of the vane geometry, which is described in terms of tip radius, vane thickness and tip center eccentricity. A parametric study is performed to show the capabilities of the proposed formulation and the influence of the vane design parameters on its kinematics. The analysis demonstrates that the vane kinematic motion in balanced vane pumps is mainly controlled by the tip radius and the tip center eccentricity, as long as the cam ring profile is defined. The tip radius is mainly responsible for the shape of the vane motion, while the tip center eccentricity has a major influence on its timing. Furthermore the effect of the cam ring profile is evaluated by demonstrating that shape and extension of the rise and fall phases influence on the vane geometry admissibility. [ABSTRACT FROM AUTHOR]

Abstract: Let R, S and T be finite sets with , and . A code with covering radius 1 and minimum distance 2 is closely connected to a certain generalized partial Latin rectangle. We present various constructions of such codes and some lower bounds on their minimal cardinality . These bounds turn out to be best possible in many instances. Focussing on the special case we determine when r divides s, when , when s is large, relative to r, when r is large, relative to s, as well as . Finally, a table with bounds on is given. [Copyright &y& Elsevier]

We present the multi-GPU realization of the StePS(Stereographically Projected Cosmological Simulations) algorithm with MPI–OpenMP–CUDA hybrid parallelization and nearly ideal scale-out to multiple compute nodes. Our new zoom-in cosmological direct N-body simulation method simulates the infinite universe with unprecedented dynamic range for a given amount of memory and, in contrast to traditional periodic simulations, its fundamental geometry and topology match observations. By using a spherical geometry instead of periodic boundary conditions, and gradually decreasing the mass resolution with radius, our code is capable of running simulations with a few gigaparsecs in diameter and with a mass resolution of ∼ 1 0 9 M ⊙ in the center in four days on three compute nodes with four GTX 1080 Ti GPUs in each. The code can also be used to run extremely fast simulations with reasonable resolution for fitting cosmological parameters. These simulations are useful for prediction needs of large surveys. The StePScode is publicly available for the research community. [ABSTRACT FROM AUTHOR]

The connection between the shadow radius and the Ruppeiner geometry of a charged static spherically symmetric black hole is investigated. The normalized curvature scalar is adopted, and its close relation to the Van der Waals-like and Hawking-Page phase transition of the Reissner-Nordström AdS black hole is studied. The results show that the shadow radius is a useful tool to reveal the correct information of the phase structure and the underlying microstructure of the black hole, which opens a new window to investigate the strong gravity system from the observational point of view. [ABSTRACT FROM AUTHOR]

Abstract: We consider the problem of locating a circle with respect to existing facilities in the plane such that the sum of weighted distances between the circle and the facilities is minimized, i.e., we approximate a set of given points by a circle regarding the sum of weighted distances. If the radius of the circle is a variable we show that there always exists an optimal circle passing through two of the existing facilities. For the case of a fixed radius we provide characterizations of optimal circles in special cases. Solution procedures are suggested. [Copyright &y& Elsevier]

Abstract Let G be a graph of order n and let d i be the degree of the vertex v i in G for i = 1 , 2 , … , n. The weighted adjacency matrix A db of G is defined so that its (i, j)-entry is equal to d i + d j d i d j if the vertices v i and v j are adjacent, and 0 otherwise. The spectral radius ϱ 1 and the energy E d b of the A db -matrix are examined. Lower and upper bounds on ϱ 1 and E d b are obtained, and the respective extremal graphs are characterized. [ABSTRACT FROM AUTHOR]

The present study proposes an analytical approach to describe contact pressure and wear evolution in line and point contacts. Starting from the unworn condition, described by Hertz theory, modifications of geometry and pressure distribution due to wear are included. Under the basic assumption of parabolic wear and pressure profiles, derived from Finite Element simulations, simple equations governing the phenomenon are derived, where the maximum wear depth evolution is described by a first order differential equation which can be easily solved. Interestingly, the maximum pressure remains dependent on the radius of curvature at the nominal contact point according to Hertz theory, but pressure is not null at the extremes of the contact region. The contact width can be derived from equilibrium conditions and wear law. The reliability of the procedure is proved by the perfect agreement with Finite Element simulations. • The geometry of the surfaces in contact as well as contact pressure change with wear. • Geometry and pressure profiles during wear are often determined by FE simulation. • A simple procedure for determining geometry and pressure evolution is proposed. • Wear and pressure profiles are assumed to be parabolic at every instant. • The proposed approach is validated against FE analyses. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents a new and effective method to construct manifold T-splines of complicated topology/geometry. The fundamental idea of our novel approach is the geometry-aware object segmentation, by which an arbitrarily complicated surface model can be decomposed into a group of disjoint components that comprise branches, handles, and base patches. Such a domain decomposition simplifies objects of arbitrary topological type into a family of genus-zero/one open surfaces, each of which can be conformally parameterized into a set of rectangles. In contrast to the conventional decomposition approaches, our method can guarantee that the cutting locus are consistent on the parametric domain. As a result, the resultant T-splines of decomposed components are automatically glued and have high-order continuity everywhere except at the extraordinary points. We show that the number of extraordinary points of the domain manifold is bounded by the number of segmented components. Furthermore, the entire mesh-to-spline data conversion pipeline can be implemented with full automation, and thus, has potential in shape modeling and reverse engineering applications of complicated real-world objects. [Copyright &y& Elsevier]

A model investigating the role of geometry on the alpha dose rate of spent nuclear fuel has been developed. This novel approach utilises a new piecewise function to describe the probability of alpha escape as a function of particulate radius, decay range within the material, and position from the surface. The alpha dose rates were produced for particulates of radii 1 μ m to 10 mm, showing considerable changes in the 1 μ m–50 μ m range. Results indicate that for decreasing particulate sizes, approaching radii equal to or less than the range of the α -particle within the fuel, there is a significant increase in the rate of energy emitted per unit mass of fuel material. The influence of geometry is more significant for smaller radii, showing clear differences in dose rate curves below 50 μ m. These considerations are essential for any future accurate prediction of the dissolution rates and hydrogen gas release, driven by the radiolytic yields of particulate spent nuclear fuel. • An approach to simulate α-dosimetry from spherical particulates is presented. • Probability of α-particle escape for curved surfaces has been derived. • The role of geometry has a considerable influence for particulate radii <50 μm. • Results comparable with previous MCNPX model to within 0.7% of total dose rate. [ABSTRACT FROM AUTHOR]

• Theoretical flow rate ripple in balanced vane pump is defined analytically. • The method relates the flow rate waveform to the vane design parameters. • A parametric study details the influence of vane tip radius and thickness. Advancements related to the correlation between pump design parameters and the kinematic flow ripple in balanced vane pumps are addressed in the present work. In particular, the study focuses the attention on the influence of the vane geometry on the oscillations of the flow rate produced by the volume variation of both under-vane pockets and displaced chambers, that is known as one of the most relevant sources of noise in hydraulic systems. The working principle of the machine is detailed and used as starting point to deduce analytical correlations describing both vane kinematics and delivery flow rate ripple. The set of results that can be achieved with the obtained formulation is evaluated by means of a nondimensional parametric study including the two main design parameters defining the vane geometry, i.e. thickness and tip radius. The resulting trends demonstrate that the theoretical delivery flow ripple is closely related to the vane design and the cam ring shape profile. [ABSTRACT FROM AUTHOR]

This paper presents a new technology to realize high-efficiency, smooth-surface, and high-chatter-stability machining of flexible thin plates with the proposed face-milling cutter geometry. Radius end mills are widely utilized for high-efficiency and smooth-surface machining, but they generally have low machining stability, i.e. chatter vibrations often occur. It is well known that the chatter stability depends on the structural flexibility and the cutting conditions, whereas it is less known that it strongly depends on the cutter geometry. In this study, a novel face-milling cutter geometry is proposed to improve chatter stability, especially for regenerative chatter, without sacrificing the high efficiency and the surface smoothness in radius end milling. The validity of the milling technology utilizing the proposed cutter geometry is verified analytically and experimentally. • Milling cutter geometry which realizes smooth surface and high chatter stability is proposed. • High efficiency, i.e. high feed rate, can be achieved since a large nose radius is adopted. • High stability is achieved because the effective regenerative cutting width is kept minimum. • Ability of cutter is verified, e.g. 7.8 times higher stability than conventional cutters. [ABSTRACT FROM AUTHOR]

We show that a method that makes clever use of the axial symmetry of the model considerably simplifies the calculation of the electrostatic Coulomb self-energy of an annulus with uniform surface charge density. Differently from a disk, the case of an annulus represents a rather challenging geometry with no obvious solution for the calculation. The final result obtained for the electrostatic Coulomb self-energy of a uniformly charged annulus is expressed in compact form as a function of the ratio of the inner radius relative to the outer radius and involves special standard functions such as the complete elliptic integrals of the first and second kind. • Stored electrostatic energy of a uniformly charged annulus. • Exact analytic result for the value of the electrostatic self-energy. • Method can be generalized to similar systems with axial symmetry. [ABSTRACT FROM AUTHOR]

Detailed geometric information of a high-purity Ge (HPGe) detector is a very important issue for Monte Carlo simulation of the detector. Commonly, users have no geometric information about the detector and information given by the manufacturer is not completely valid for simulation. An equivalent geometry of detector, the parameters of which can be used for Monte Carlo simulation, is optimised using a genetic algorithm for a large-volume HPGe detector in this study. A mixed-point gamma calibration standard, emitting 12 useful gamma-radiation energies within 59.5–1836.1 keV, is placed at 74 different locations around the detector for this purpose. A high-quality solution is generated starting from an initial population of randomly-generated detector geometries using a genetic algorithm. Fitness of each geometry is obtained by comparing full energy peak efficiencies computed by Monte Carlo simulation with experimental values for each energy and position. Efficiencies with relative errors less than 5% for high energies and less than 7% for lower energies, except 59.5 keV, are obtained using optimised equivalent geometry parameters for the Monte Carlo simulation. Also, the necessity of using crystal dimensions smaller than real dimensions for Monte Carlo simulations of high-volume HPGe detectors is discussed. In addition, for Monte Carlo simulation of high-volume HPGe detectors, it is demonstrated that the use of smaller crystal dimensions than the real dimensions is necessary to obtain experimentally measured efficiencies of the detector. • Problems in Monte Carlo simulations of high-volume Germanium detectors are discussed. • Defining new equivalent geometry parameters for these simulations are proposed. • New geometry parameters are described by a genetic algorithm. • Necessity of simulating high-volume Ge detectors with smaller dimensions are stated. • Energy cumulative distribution function is used to simulate true coincidence effects. [ABSTRACT FROM AUTHOR]

Abstract: The spreading of a drop of non-Newtonian (power-law) liquid over a horizontal solid substrate is analyzed theoretically through energy approach method in the case of complete wetting. In this approach we have used the physical and geometrical reasoning and finally obtained a relation between the rate of spreading and bottom radius of the drop. It is shown that spreading rate of shear thickening liquid is more than that of a Newtonian liquid while shear thinning liquid is having slower rate than the latter one. [Copyright &y& Elsevier]

The present work is undertaken to optimize the geometry of the curved trapezoidal winglet mounted over each cooling tube to enhance the overall performance of the heat exchanger. Before conducting the optimization study, the most critical geometric entities have been identified, and this has helped in significantly reducing the computational overheads. It has been found that the three most critical design parameters are the arc radius (R), the angle subtended (θ) and the winglet's leading-edge height (h 1), and the same are chosen for optimization. To plan the experiment, we make use of the Latin hypercube sampling (LHS) scheme. The system responses viz. the Colburn factor (j) and the friction factor (f) ‒ for different combinations of the independent variables ‒ are computed using the numerical simulations together with the conjugate heat transfer approach. To get the best outcome from computations, both fluid and solid domains have been discretized using hexahedra. We make use of the Reynolds-averaged Navier-Stokes (RANS) approach ‒ with SST k –ω (a 2-equation) turbulence model as a closure to RANS ‒ for evaluating the dependent variables. The artificial neural network (ANN) is trained using the data from the DoE table to build the metamodel necessary for conducting the multiobjective optimization. The genetic algorithm (GA) is employed to generate the optimized data sets. The study reveals that the optimized HE variants outperform the baseline model not only at the on-design condition but also at the off-design conditions. The resulting Pareto front points reveal very interesting results, and these data would facilitate the designers to make choices over a wide range of the VG geometry of the heat exchanger. [Display omitted] • Fin-and-tube type heat exchanger with curved trapezoidal winglets is optimized. • Latin hypercube sampling plan is used to design the experiment. • The artificial neural network is used to build the surrogate models for optimization. • Pareto front points are generated using the genetic algorithm. • The optimized data sets elucidate significant improvement over the baseline models. [ABSTRACT FROM AUTHOR]