Search

Three-dimensional printing technology (3D printing) is becoming a more and more popular technology for aerospace, biology, medicine, mechanics, civil and other engineering fields. In civil engineering, researchers and engineers attempt to print construction materials such as concrete using 3D-printing technology. This study aims to investigate the reinforcement of concrete beams with 3D printing. To achieve this, fused deposition modeling (FDM) technology as a printing method and polylactic acid (PLA) as a material were selected. Two types of geometries were chosen to find the optimal mechanical behavior of concrete: high-performance concrete (HPC) reinforced with four types of trusses (Pratt, Howe, Warren, and Warren with vertical) and ultra-high-performance concrete (UHPC) reinforced with a hyperboloid shell structure. The compressive and tensile strengths of reinforced UHPC were examined by a three-point bending test, and reinforced HPC was examined by a four-point bending test. The results of the experiments show that hyperboloid shell structures can absorb energy, although the strength of reinforced UHPC is reduced. For example, there was a decrease of over 20% in the compressive strength and 41% in the flexural strength, but the ductility was raised. Adding the hyperboloid shell structure improved the deformability of the UHPC. When Warren and Howe trusses were added to the HPC as reinforcements, the flexural strength improved by over 26% and 4.3%, respectively. The overall results of this study show that the concrete reinforced with 3D-printed trusses was better than that with a hyperboloid shell structure. [ABSTRACT FROM AUTHOR]

The vast majority of studies on discounting have focused on simple delayed outcomes, but most everyday decisions are more complicated. The present experiment focused on one such scenario, an iconic self‐control situation in which immediate gains are followed by delayed losses. The same participants were studied in all conditions to permit examination of individual differences in choice behavior using intercorrelations and factor analysis. Consistent with previous research, the hyperboloid model accurately described the form of the discounting function and discounting was not affected by the amount of the delayed loss when it was presented alone. However, replicating other studies, smaller delayed losses were discounted more steeply than larger ones when presented in combination with immediate gains. Exploratory factor analysis revealed two factors, one loading primarily on loss‐only conditions and the other loading primarily on conditions involving outcomes that combined gains and losses. These results imply that there are individual differences in how one combines gains and losses and that this characteristic of individual decision making might be an important predictor of decisions in the many everyday choice situations that involve complex outcomes. [ABSTRACT FROM AUTHOR]

Three-dimensional printing technology (3D printing) is becoming a more and more popular technology for aerospace, biology, medicine, mechanics, civil and other engineering fields. In civil engineering, researchers and engineers attempt to print construction materials such as concrete using 3D-printing technology. This study aims to investigate the reinforcement of concrete beams with 3D printing. To achieve this, fused deposition modeling (FDM) technology as a printing method and polylactic acid (PLA) as a material were selected. Two types of geometries were chosen to find the optimal mechanical behavior of concrete: high-performance concrete (HPC) reinforced with four types of trusses (Pratt, Howe, Warren, and Warren with vertical) and ultra-high-performance concrete (UHPC) reinforced with a hyperboloid shell structure. The compressive and tensile strengths of reinforced UHPC were examined by a three-point bending test, and reinforced HPC was examined by a four-point bending test. The results of the experiments show that hyperboloid shell structures can absorb energy, although the strength of reinforced UHPC is reduced. For example, there was a decrease of over 20% in the compressive strength and 41% in the flexural strength, but the ductility was raised. Adding the hyperboloid shell structure improved the deformability of the UHPC. When Warren and Howe trusses were added to the HPC as reinforcements, the flexural strength improved by over 26% and 4.3%, respectively. The overall results of this study show that the concrete reinforced with 3D-printed trusses was better than that with a hyperboloid shell structure.

We review from a different perspective the approach and solution to the torque-free Euler equations, also called the free asymmetric top equations. We aim to simplify and broaden the study of the asymmetric free rigid body. This is an old but important integrable problem that has two first integrals: the energy and the angular momentum. We reduce this problem by eliminating the time as the independent variable in the three autonomous Euler equations written in cylindrical dimensionless variables, which allows a geometric study of the solution as a function of the cylindrical angle variable ψ , by means of continuous deformations dependent on the two independent parameters κ and e 0 . The parameter space is divided into six disjoint regions, whose boundaries are the separatices and degenerated cases. The solutions are given in terms of trigonometric functions of the independent cylindric angle ψ. [ABSTRACT FROM AUTHOR]

In this article, we aim at obtaining the analytical expression (not previously found and recorded in the literature) for the exact curved surface area of a hyperboloid of two sheets in terms of Appell's double hypergeometric function of second kind and triple hypergeometric function of Srivastava. The derivation is based on Mellin-Barnes type contour integral representations of generalized hypergeometric function pFq(z), Meijer's G-function and series manipulation technique. Further, we also obtain the formula for the volume of hyperboloid of two sheets. The closed forms for the exact curved surface area and volume of the hyperboloid of two sheets are also verified numerically by using Mathematica Program. [ABSTRACT FROM AUTHOR]

Different hypotheses of carcinogenesis have been proposed based on local genetic factors and physiologic mechanisms. It is assumed that changes in the metric invariants of a biologic system (BS) determine the general mechanisms of cancer development. Numerous pieces of data demonstrate the existence of three invariant feedback patterns of BS: negative feedback (NFB), positive feedback (PFB) and reciprocal links (RL). These base patterns represent basis elements of a Lie algebra s l (2 , R) and an imaginary part of coquaternion. Considering coquaternion as a model of a functional core of a BS, in this work a new geometric approach has been introduced. Based on this approach, conditions of the system are identified with the points of three families of hypersurfaces in R42: hyperboloids of one sheet, hyperboloids of two sheets and double cones. The obtained results also demonstrated the correspondence of an indefinite metric of coquaternion quadratic form with negative and positive entropy contributions of the base elements to the energy level of the system. From that, it can be further concluded that the anabolic states of the system will correspond to the points of a hyperboloid of one sheet, whereas catabolic conditions correspond to the points of a hyperboloid of two sheets. Equilibrium states will lie in a double cone. Physiologically anabolic and catabolic states dominate intermittently oscillating around the equilibrium. Deterioration of base elements increases positive entropy and causes domination of catabolic states, which is the main metabolic determinant of cancer. Based on these observations and the geometric representation of a BS's behavior, it was shown that conditions related to cancer metabolic malfunction will have a tendency to remain inside the double cone. [ABSTRACT FROM AUTHOR]

Previous discounting research has focused on relatively simple situations (e.g., choosing between immediate and delayed gains, or between immediate and delayed losses) and the relations among amount, delay, and subjective value in such situations are now well established. Many everyday choice situations, however, are more complex, involving alternatives that combine gains and losses. In two experiments, participants discounted a monetary outcome that combined an immediate gain with a delayed loss. Consistent with the discounting framework, the value of the combination was approximately equal to the difference between the (undiscounted) value of the immediate gain and the (discounted) value of the delayed loss. More precise predictions of the relative subjective value of the delayed loss component of a combination were given by the same hyperboloid function that describes discounting in simple choice situations where outcomes only involve gains or losses, not both. As in previous studies, when the outcome was a simple one consisting of only a delayed loss, discounting was not affected by the amount of that loss. Surprisingly, however, when the loss was preceded by a gain, the degree to which the combination was discounted was affected by the amount of the loss. Notably, discounting of the delayed loss component of the combination decreased with the amount of the loss in a fashion similar to that observed with simple delayed gains, where smaller amounts are discounted more steeply than larger amounts. Choice situations involving immediate gains followed by delayed losses pose iconic self‐control problems, and the present findings support the application of the discounting framework to these important everyday problems. [ABSTRACT FROM AUTHOR]

The processes of ray energy transfer using hyperbolic formations and the accompanying ef)fects are considered. A new concept of the optical system of a solar energy concentrator and varieties within its framework are proposed, aberrations that occur in such systems and the possibility of transmitting ray energy using a hyperboloid system consisting of surfaces of the second and higher order are considered. The possibility of creating the effect of self-focusing in mirror optical systems is considered. [ABSTRACT FROM AUTHOR]

Objective. The aim of the study is to develop methods for determining the coordinates of the hypocenter of an earthquake with a known structure of the earth's crust. Method. To solve the problem, the brute force method, the confidence interval, the comparative method and the enumeration of possible options on the grid are used. Result. A method has been developed for determining the coordinates of an earthquake source with a known structure of the earth's crust using points of various figures of the n-th order as geometric locations in calculations. Conclusion. The proposed method, with the known structure of the earth's crust, makes it possible to use all known methods that require information on the travel time differences of seismic waves to spaced seismic sensors and the difference in travel times of longitudinal and transverse seismic waves to the seismic sensor for calculating the coordinates of the earthquake hypocenter. The accuracy of determining the coordinates of the earthquake hypocenter depends on the quality of determining the structure of the earth's crust on which the seismic event was observed.

Objective. The aim of the study is to develop a method for determining the coordinates of the earthquake hypocenter using various combinations of second and fourth order figures as a geo-locus of the hypocenter position points.Method. It is known that the line of intersection of figures of the second and fourth orders, in the case of coincidence of focuses, is a circle. To determine the coordinates of the earthquake source, data from seismographs are used, which are used to construct figures of the second and fourth order, the intersection point of which is the hypocenter. When using data from two seismic sensors, there are two figures, the intersection line of which is a circle. A sphere with a radius equal to the radius of the circle is constructed through the center of this circle. For the other two pairs of seismic sensors, two more spheres are also formed, The intersection point of the three spheres obtained is the sought-for hypocenter of the earthquake.Result. A method has been developed for determining the coordinates of an earthquake source using different shapes of the second and fourth orders for different pairs of seismic sensors.Conclusion. The method allows one to select one of the second or fourth order figures for different pairs of seismic sensors, which makes it possible to reduce the error in determining the source coordinates.

We establish Fourier extension estimates for compact subsets of the hyperbolic hyperboloid in three dimensions via polynomial partitioning. [ABSTRACT FROM AUTHOR]

The paper proposes a computational method to study and test the relationship between shape and performance for the built environment, sustaining the use of smart geometry to support design operation. A comprehensive study of the geometry and working principles of a hyperboloidical cooling tower is presented. A case study in Marghera (Venice), built in 1938 is explored. Thanks to knowledge in descriptive geometry and mathematics, scripting procedures, digital survey, Building Information Modeling (BIM) and Computational Fluid Dynamics (CFD) analysis, the paper demonstrates how hyperboloidical cooling towers represent a reference in shape optimization. Varying the fundamental parameter of the shape, reducing the throat diameter, the simulation shows the enhanced efficiency of the tower in terms of velocity and temperature. Consequently, the proposed method may be applied to other surfaces and structures. [ABSTRACT FROM AUTHOR]

• Radiometric theory of ellipsoidal cavities. • View factor of a triaxial ellipsoid. • Design, test, and construct an ellipsoid to analyze the breast. • Description of an ellipsoid with spectral stability capable of distinguishing between tissues of different sizes and types. • SVM classification algorithm to retrieve a diffuse reflectance spectrum of biological ex vivo tissue from a set of them. Integrating ellipsoids in diffuse reflectance spectroscopy is unusual; few are constructed in just one piece. In diffuse reflectance spectroscopy, integrating spheres are used to determine the optical properties of biological tissues in diagnosis or disease detection. The disadvantages of using integrating spheres in the biological field lie in the dimensions of their apertures, which, being small, prevent the analysis of a complete biological tissue or organ. In this work, we propose the construction, calibration, and use of diffuse reflecting integrating ellipsoid (DRIE) for spectral analysis, elaborated as a body without couplings, not implemented so far for clinical diagnosis. A hyperboloid calibrator was designed and coupled to the ellipsoid to measure the volumetric spectra of samples instead of thin samples with small surfaces to measure whole organs or samples with larger sizes than habitual. We developed a radiometric theory for the ellipsoid using the shape factor to calculate its flux or radiant energy. With spectra acquired by the device from different chicken tissues (brain, bone, muscle, digestive tract, and skin) and with support vector machines (SVM), spectra of the tissues were classified for dimensions from 19.14 mm2 to 4600 mm2, resulting in a correlation (0.98), demonstrating the high sensitivity and low noise of our device to classify. [ABSTRACT FROM AUTHOR]

Under discussion is the matter of processing hyperboloid surfaces using wire electrode discharge machining (WEDM). Let us consider a random hyperboloid surface which will help define the kinetics engaged in generating it. There will be illustrated the mathematical relations that make possible the engendering of hyperboloid surfaces, ensued by an exemplification of the way the processing works, highlighting its industrial role. [ABSTRACT FROM AUTHOR]

Objectives. To study the dependencies obtained when determining the coordinates of an earthquake hypocentre using the figures of fourth and second orders.Method. A comparative analysis of determining the coordinates of the earthquake focus using the Cassini oval method, both taking errors in the readings of seismic sensors into account the and ignoring them, is presented.Result. A new method is proposed for determining the coordinates of the earthquake hypocentre, which uses the fourth-order figure, the Cassini oval, in the calculations. A graph is obtained for the distribution of errors in determining the coordinates of the earthquake focus (using the Cassini oval) depending on the relative position of two seismic sensors with different values of their errors in determining the difference in travel times of seismic waves.Conclusion. Since the calculation results are independent of the error sign in determining the difference in the arrival times of seismic waves, the method is suitable for the initial determination of the coordinates of the earthquake hypocentre as well as for comparison with the results of other methods for identifying the error sign.

Copyright of Mechanics & Advanced Technologies is the property of National Technical University of Ukraine KPI and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this article we establish new inequalities, both conditional and unconditional, for the restriction problem associated to the hyperbolic, or one-sheeted, hyperboloid in three dimensions, endowed with a Lorentz-invariant measure. These inequalities are unconditional (and optimal) in the bilinear range q > 10 3. [ABSTRACT FROM AUTHOR]

We consider orthogonal polynomials on the surface of a double cone or a hyperboloid of revolution, either finite or infinite in axis direction, and on the solid domain bounded by such a surface and, when the surface is finite, by hyperplanes at the two ends. On each domain a family of orthogonal polynomials, related to the Gegebauer polynomials, is studied and shown to share two characteristic properties of spherical harmonics: they are eigenfunctions of a second order linear differential operator with eigenvalues depending only on the polynomial degree, and they satisfy an addition formula that provides a closed form formula for the reproducing kernel of the orthogonal projection operator. The addition formula leads to a convolution structure, which provides a powerful tool for studying the Fourier orthogonal series on these domains. Furthermore, another family of orthogonal polynomials, related to the Hermite polynomials, is defined and shown to be the limit of the first family, and their properties are derived accordingly. [ABSTRACT FROM AUTHOR]

Objectives The purpose of the study is to obtain an expression for determining the coordinates of the earthquake focus using the ellipsoid method, as well as testing the possibility of using the method using the figures of the second order of the ellipsoid during the initial determination of the coordinates of the earthquake hypocenter.Method A comparative analysis of the probability density of errors in the hypocentral zone of the earth's surface, in combination with various spheres, ellipsoid and hyperboloid and ellipsoids, is carried out.Result Obtained an expression for determining the coordinates of the earthquake focus by the method of ellipsoids, as well as the density of the distribution of error probabilities in the determination of the earthquake hypocenter the in calculations by the method of spheres, by the combined method of spheres, hyperboloid and ellipsoid, and also by the method of ellipsoids.Conclusion Methods used to determine the coordinates of the hypocenter ellipsoid, have large errors in comparison with the method of areas. This can explained by the fact that in determining the coordinates of the hypocenter in the sphere method, three errors are used in determining the difference in the travel times of seismic waves, while in the ellipsoid method and the combined method of the sphere of the ellipsoid and hyperboloid have four errors, which introduces final errors in the distribution. All the obtained dependences of the error distribution have the form close to the Cauchy distribution.

What shapes do you get when you spin a cube on one of its vertices? This article explores the algebraic aspects of a spinning cube and establishes equations for the two cones and the hyperboloid using secondary school mathematics. Both the analysis and the verification take advantage of dynamic mathematics learning technologies. [ABSTRACT FROM AUTHOR]

The use of parametric and multi-objective optimization (MOO) as a new way of approaching architectural design has been growing in line with current breakthroughs in computational architecture. Wood, on the other hand, is a living and unique building material that provides durability, manufacturing flexibility, and local availability. One of the structure types that provides high structural stability is the hyperboloid. However, the exploration of hyperboloid structures in building design, together with the building daylight objective, is still limitedly reported. This paper presents the application of the parametric approach and multi-objective optimization in optimizing the structure and daylight objectives of a hyperboloid two-story wooden house in Japan, made of 105 mm × 105 mm × 4000 mm Japanese timber. The method involves iterating dynamic parameters such as radius bottom, offset distance, timber members, twisting level, building height, radius-top, and roof slope to optimize the structural objective of minimizing normal force average, displacement, and cost while simultaneously maximizing building volume. Regarding daylight objectives, unit movement and glazing ratio that control the glazing strategies were explored to optimize useful daylight illumination (UDI) in summer and winter. The optimization and exploration yielded 10,098 solutions in structural analysis and 406 solutions in daylight exploration. Based on the data analysis, the proposed methodology has successfully produced the best design solution, discovering the balance between the objective trade-offs. In addition, the most influential parameter that shapes the value of design objectives has been identified. The findings of this research were expected to contribute to and enhance the performance-based design optimization, and support design decision-making process in the early design stage of a wooden house with a hyperboloid structure.

For a sharp tip emitter, due to the non-uniform emission feature and the electron beam expansion in the vacuum, it is difficult to precisely determine the average field enhancement factor βc as well as the effective emission area Seff for a single field emitter. In this paper, we conduct a numerical experiment to simulate the electron field emission from a sharp tip emitter (Lorentzian or hyperboloid shape). By collecting the emission current Itot at the finite anode area Stot, we establish the criteria in using Fowler-Nordheim plot to estimate both βc and Seff, which agree well with our initial emission condition. It is found that the values of βc and Seff depend on the emitter's properties as well as the size of the anode area Stot. In order to determine the precise value of βc, Stot must be large enough to collect all the emitted electrons from the sharp tip (e.g., Itot reaches maximum). As an example, a Lorentzian type emitter with an aspect ratio of 10 (height over width), the effective enhancement factor is about βc=33 as compared to the maximal enhancement of 35 at the apex. At similar maximal enhancement factor at the apex (=360), both types of emitters will give different average field enhancement dependent on the collecting area. The extension of this simple model to a statistical more complicated model to simulate field emission from a cathode consisting of many field emitters is also briefly discussed. This paper should be useful to analyze and characterize field emission data together with experimental measurement. [ABSTRACT FROM AUTHOR]

Abstract. Objectives This work is a continuation of a series of articles devoted to an analysis of the effect of the utilised second-order surface types on the accuracy of determining earthquake epicentre and hypocentre coordinates. Methods In order to find the density of error probability distribution during the determination of earthquake hypocentres, approaches using spheres, hyperboloids, as well as combined spheres and hyperboloids, are used.The hyperboloid-based methods used for determining hypocentre coordinates have fewer errors as compared to the sphere-based method. This is explained by the fact that when determining the travel times of seismic waves, it is assumed that the error increase is the same for the difference in the seismic wave arrival times to two seismic sensors (for methods using hyperboloid), and for the difference in the arrival times of the two seismic waves to the one seismic sensor (for methods using spheres). Results The expression for determining the earthquake focus coordinates by the hyperboloid method, as well as the density of error probability distribution during the earthquake hypocentre determination, is obtained for calculations using the sphere method, the hyperboloid method, as well as the combined sphere and hyperboloid method. A graph for the error distribution when determining the earthquake hypocentre is obtained for different locations of seismic sensors and for various error values concerning differences in the travel times of seismic waves. Conclusion The obtained dependencies have the form of an error distribution close to the Cauchy distribution. A wavelet in the zero regions for all distributions was obtained as a result of calculations of the earthquake focus coordinates in the absence of errors in the determination of the time difference. The combined method of the hyperboloid and the sphere has a distribution form close to the hyperboloid method, while the distribution curve in the region close to zero is similar to the sphere method.

We present a proof of concept for a spectrally selective thermal mid-IR source based on nanopatterned graphene (NPG) with a typical mobility of CVD-grown graphene (up to 3000 cm 2 V - 1 s - 1 ), ensuring scalability to large areas. For that, we solve the electrostatic problem of a conducting hyperboloid with an elliptical wormhole in the presence of an in-plane electric field. The localized surface plasmons (LSPs) on the NPG sheet, partially hybridized with graphene phonons and surface phonons of the neighboring materials, allow for the control and tuning of the thermal emission spectrum in the wavelength regime from λ = 3 to 12 μ m by adjusting the size of and distance between the circular holes in a hexagonal or square lattice structure. Most importantly, the LSPs along with an optical cavity increase the emittance of graphene from about 2.3% for pristine graphene to 80% for NPG, thereby outperforming state-of-the-art pristine graphene light sources operating in the near-infrared by at least a factor of 100. According to our COMSOL calculations, a maximum emission power per area of 11 × 10 3 W/ m 2 at T = 2000 K for a bias voltage of V = 23 V is achieved by controlling the temperature of the hot electrons through the Joule heating. By generalizing Planck's theory to any grey body and deriving the completely general nonlocal fluctuation-dissipation theorem with nonlocal response of surface plasmons in the random phase approximation, we show that the coherence length of the graphene plasmons and the thermally emitted photons can be as large as 13 μ m and 150 μ m, respectively, providing the opportunity to create phased arrays made of nanoantennas represented by the holes in NPG. The spatial phase variation of the coherence allows for beamsteering of the thermal emission in the range between 12 ∘ and 80 ∘ by tuning the Fermi energy between E F = 1.0 eV and E F = 0.25 eV through the gate voltage. Our analysis of the nonlocal hydrodynamic response leads to the conjecture that the diffusion length and viscosity in graphene are frequency-dependent. Using finite-difference time domain calculations, coupled mode theory, and RPA, we develop the model of a mid-IR light source based on NPG, which will pave the way to graphene-based optical mid-IR communication, mid-IR color displays, mid-IR spectroscopy, and virus detection. [ABSTRACT FROM AUTHOR]

Hyperbolic towers are towers in the shape of a single-sheet hyperboloid, and they are interesting in architecture. In this paper, we deal with the infinitesimal bending of a curve on a hyperboloid of one sheet; that is, we study the flexibility of the net-like structures used to make a hyperbolic tower. Visualization of infinitesimal bending has been carried out using Mathematica, and some examples are presented and discussed. [ABSTRACT FROM AUTHOR]

Solar chimney power plant (SCPP) is an interesting project to produce clean and sustainable energy. An efficient SCPP system requires a very high chimney, and thus the optimization of the chimney shape presents an important way to enhance the SCPP performance. The aim of this paper is to analyze the effect of the divergent chimney shape on the airflow behavior inside SCPP. A comparison between four chimney shapes is carried out using CFD method: two cylindrical chimneys with different diameters and two divergent chimneys with different shapes. Indeed, both parameters were studied: the ratio of the inlet and outlet diameter of the chimney and the shape of the chimney which both hyperboloid and conical. The SCPP prototype was tested numerically and experimentally to validate the present computational outcomes. The obtained results confirm that the divergence shape affects directly the efficiency of the SCPP system. Moreover, the hyperboloid chimney presents the efficient solution which produces an important power output with keeping the chimney height constant. [ABSTRACT FROM AUTHOR]

Copyright of Electronics & Control Systems is the property of National Aviation University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The relationship between the eyeball size and convexity of its anterior part and the efficacy of local vacuum compression of the eye performed using a new design suction cup for impedance ophthalmopneumoplethysmography was studied. Based on the mathematical modeling of the geometric shape of the anterior segment of 75 eyes obtained by ultrasound biomicroscopy examination, it was found that the horizontal meridian curve of the anterior eye segment with a base diameter of 16.00 mm could be best approximated by a hyperbola. The surface area under the new suction cup with an inside diameter of about 16.5 mm was calculated using the formula for the segment surface area of a hyperboloid of revolution. It was determined by the convexity of the anterior part of the eye and varied from 247.3 to 271.4 mm2. The conversion coefficient of the level of applied vacuum to the level of IOP rise, calculated on the basis of individual combinations of the surface area of local vacuum compression and the eyeball size, was on average 0.83 ranging from 0.44 to 1.33. Using an individual conversion coefficient according to eyeball anatomical parameters will make it possible to measure diastolic ocular perfusion pressure during impedance OPPG with high sensitivity and accuracy. [ABSTRACT FROM AUTHOR]

A general calculation for the distribution of non-uniform demagnetization fields in paramagnetic bulk solids is described and the fields for various sample geometries are calculated. Cones, ellipsoids, paraboloids, and hyperboloids with similar sample aspect ratios are considered. Significant differences in their demagnetization fields are observed. The calculation shows that the demagnetization field magnitudes decrease along the axis of symmetry (along z) where an externally applied magnetic field is aligned, and increase in the vicinity of the lateral surfaces with the largest field values found in the cone and the narrowest field distributions found in the hyperboloid. An application is made to the theoretical modeling of the 1H-NMR spectra of a single crystal of field-induced superconductor λ-(BETS)2 FeCl4 with a rectangular sample geometry, providing a good fit to the measured NMR spectra. [ABSTRACT FROM AUTHOR]

The geometric challenges in the architectural design of warped surface come mainly from the physical materialization. This paper presents structural forms based on warped surface and shows the types of structures made during the 20th and 21st century, the geometric scheme, the structural behaviour and a projection of their potential trends. The analysis creates the possibility of comparisons between original and current design. Also, this work analyses the ways in which descriptive geometry, by warped surface allows the students architects the realization of volumes and architectural spaces, especially the role it plays in the development of spatial thinking.

The geometric challenges in the architectural design of warped surface come mainly from the physical materialization. This paper presents structural forms based on warped surface and shows the types of structures made during the 20th and 21st century, the geometric scheme, the structural behaviour and a projection of their potential trends. The analysis creates the possibility of comparisons between original and current design. Also, this work analyses the ways in which descriptive geometry, by warped surface allows the students architects the realization of volumes and architectural spaces, especially the role it plays in the development of spatial thinking. [ABSTRACT FROM AUTHOR]

Abstract The L 2 → L p adjoint Fourier restriction inequality on the d -dimensional hyperboloid H d ⊂ R d + 1 holds provided 6 ≤ p < ∞ , if d = 1 , and 2 (d + 2) / d ≤ p ≤ 2 (d + 1) / (d − 1) , if d ≥ 2. Quilodrán [35] recently found the values of the optimal constants in the endpoint cases (d , p) ∈ { (2 , 4) , (2 , 6) , (3 , 4) } and showed that the inequality does not have extremizers in these cases. In this paper we answer two questions posed in [35] , namely: (i) we find the explicit value of the optimal constant in the endpoint case (d , p) = (1 , 6) (the remaining endpoint for which p is an even integer) and show that there are no extremizers in this case; and (ii) we establish the existence of extremizers in all non-endpoint cases in dimensions d ∈ { 1 , 2 }. This completes the qualitative description of this problem in low dimensions. [ABSTRACT FROM AUTHOR]

Highlights • A sensitivity-based region selection for the GCC-based SRP algorithm is presented. • The method exploits the nonuniform TDOA information accumulation on the search grid. • The search space is classified into high and low sensitivity regions. • A peak-to-peak ratio identifies the region in which the source is positioned. • The noise component of a GCC function is modeled as a Gaussian distribution. Abstract The steered response power (SRP) algorithm is a well-studied method for acoustic source localization using a microphone array. Recently, different improvements based on the accumulation of all time difference of arrival (TDOA) information have been proposed in order to achieve spatial resolution scalability of the grid search map and reduce the computational cost. However, the TDOA information distribution is not uniform with respect to the search grid, as it depends on the geometry of the array, the sampling frequency, and the spatial resolution. In this paper, we propose a sensitivity-based region selection SRP (R-SRP) algorithm that exploits the nonuniform TDOA information accumulation on the search grid. First, high and low sensitivity regions of the search space are identified using an array sensitivity estimation procedure; then, through the formulation of a peak-to-peak ratio (PPR) measuring the peak energy distribution in the two regions, the source is classified to belong to a high or to a low sensitivity region, and this information is used to design an ad hoc weighting function of the acoustic power map on which the grid search is performed. Simulated and real experiments show that the proposed method improves the localization performance in comparison to the state-of-the-art. [ABSTRACT FROM AUTHOR]

We propose a non-null subaperture stitching method to measure the convex aspheric surfaces. In the method, the non-null configuration avoids the introduction of auxiliary optical elements which must be specially designed and customized, and their compensating effects cannot be independently measured. In order to obtain the full aperture result, a non-null stitching algorithm based on ray tracing method and least square method is developed to stitch all phase data together. Both simulation and experimental results justify the proposed method. [ABSTRACT FROM AUTHOR]

Electrostatic precipitators based on corona discharge are a research hotspot in recent years. It is of great significance to investigate the characteristics of corona discharge under different system parameters for improving the dust removal efficiency. In this manuscript, the continuity equations coupled with Poisson's equation are solved by the finite element method (FEM) to explore the different mechanisms of the generation of Trichel pulses when hyperboloid and hemispherical electrodes are used in negative corona discharges for a needle-plate configuration under atmospheric pressure. The fitting curve of the Trichel pulse frequency versus systematic macro parameters, including the applied voltage, the needle tip radius and the needle-plate distance, are given and their mechanisms are analyzed. Subsequently, the features of the Trichel pulses of the hyperboloid electrode and the hemispherical electrode at similar power are compared. From precipitation point of view, the hemispherical electrode is obviously better than hyperboloid electrode. [ABSTRACT FROM AUTHOR]

The paper presents practical aspects of an original method that can be used for cutting hyperboloid surfaces using wire electrical discharge machining (WEDM). The processing method, which has only been partly revealed by the author in certain relatively low-impact Romanian publications, is now fully delineated in the form of two papers that focus on both the theoretical and practical aspects of the processing of hyperboloid surfaces using wire electrical discharge machining. This paper presents the practical aspects of the method of generating hyperboloid surfaces. The numerical and geometric simulation of the generation of hyperboloid surfaces using wire electrical discharge machining is shown, together with the way of programming the processing, certain technological limitations regarding the processing of hyperboloid surfaces, and real-world conclusions concerning the generation of surfaces being processed via wire electrical discharge machining. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • An optimized T-trap with uniform electric field was obtained based on electric field analysis and SIMION simulation. • A high correlation was found between the in-trap electric field gradient distribution and the ion emission characteristics. • Directional ion excitation ability can be achieved with appropriate structure modification. • The finding can be used to implement structure optimization of asymmetric ion trap analyzers. Abstract The toroidal-cylindrical ion trap (TCIT) is a small multi-function tandem ion trap analyzer with a simple structure and a compact design. The asymmetric structure of the out toroidal ion trap (T-trap) confers the in-trap region with a non-uniform electric field distribution, particularly when a plate ring electrode is used. To optimize the electric field distribution in the trap, the shapes of the toroidal electrodes were modified to compensate for the electric field. For this purpose, we developed a simple simulation-based method for evaluating the optimized asymmetric structure of the ion trap electrode. Specifically, static electric field distribution in the trap was acquired using COMSOL software and then simply analyzed, while the SIMION simulation platform was adopted to characterize both the ion motion and the performance of the T-trap with an modified structure. The results revealed that electrode optimization can not only improve the non-uniformity of the in-trap electric field distribution but also implement unidirectional emission of the ions upon resonance excitation, thereby significantly increasing the utilization efficiency of the ions in TCIT. In addition, a high correlation was found between the electric field gradient distribution in the trap and the ion emission characteristics, which can provide an simple but useful guiding significance for the performance and structural optimization of T-trap. [ABSTRACT FROM AUTHOR]

Presents a study which determined the electron density in a laser tube that is formed by a hyperboloid of revolution and spherical-end surfaces. Computational procedure and assumptions; Results; Discussion.