Ray Method Research Articles

Effect of additives on hydration and hardening of magnesia compositions

The article is devoted to the investigation of the influence of technological factors on the hydration and hardening of magnesia compositions. The objective – is investigation magnesia compositions with different additives. Factors which impact activity of magnesium oxide in compositions of different structure are investigated. Influence of liquid density on hardening of magnesium bindings is defined. Processes of hydration and hardening of magnesium bindings with participation of minerals – silicates are investigated. It is revealed that the addition of semi-aquatic calcium sulfate contributes to the hardening of magnesia binders. Defined effect of concentration calcium sulfate hemihydrate to the hardening of caustic magnesite. Here are proposed structures of sulphomagnesium compositions containing technogenic components. It revealed a beneficial effect on the hardening of ferrous component of the mixed magnesia binder. Composition of hydration products of magnesium binding with participation of ferriferous minerals is presented. Transformations of phases at hydration of magnesium binding are revealed. Influence of structure of bindings on transformations of hydrates is established. Results of research of magnesia bindings of long hardening are given. It is shown that the durability of stone of bindings is provided with dense structure of hydrates. In researches are used X – Ray and thermal methods, electronic microscopy.

About modeling the waves scattering on the complex shape objects

Background: Reducing the detection probability by radar stations for military or civil complex shape objects is very important problem of modern radar theory. The solution to this problem is impossible without numerous estimates of the effective scattering surface (RCS) of the investigated object. Objectives: The purpose of the work was to analyze and improve the efficiency of methods for modeling electromagnetic scattering on objects of complex shape. The process of constructing a facet model of an complex shape object for modeling electromagnetic scattering and an algorithm to simplify the geometric model of an object to reduce the time required for modeling is considered. Materials and methods: As the main method for calculating the RCS, we chose the method of rays that fall and reflect (in the English language literature “Shooting and Bouncing Rays” SBR). Wherein the modeling electromagnetic scattering on an complex shape object is based on the methods of physical and geometric optics. Object is represented in the form of a geometric model which takes into account the shape of the object and its electrodynamic properties (reflection coefficient, dielectric and magnetic permeability of the surface, conductivity, etc.). Results: The general steps of the SBR method are discussed, and the efficient of using the surface mesh method to launch the rays is shown. Effective approaches to simplify the calculation for complex shape objects are proposed, in particular, the use of Raytressing and k-d tree is considered. The using of large facets for modeling surface flat sections of complex shape object is proposed. To assess the effect of the facet size on the accuracy of RCS calculations, we simulated electromagnetic scattering for a triangular plate, the surface of which is represented using different numbers of facets. A comparison with the well-known expressions for a triangular plate RCS is made. Conclusions: The accelerating possibilities of the process of electromagnetic wave diffraction calculation on complex shape objects are offered. The efficiency of the created algorithms is tested numerically.

A Path Planning Algorithm for Plant Protection UAV for Avoiding Multiple Obstruction Areas

China’s farmland environment is complex. The planting area often contains some irregular obstacles. It is hard for plant protection UAV (Unmanned Aerial Vehicle) to get good planning results to avoid obstacles automatically in the autonomous mode or only through sensors. In order to improve the application scope for plant UAVs with autonomous operation mode and to obtain good operation results, this paper proposes Multi-Obstacle Area Avoidance (MOAA) algorithm which is a path planning algorithm for avoiding obstacle areas. This algorithm is proposed based on the method of cattle ploughing reciprocation. According to the information of heading, spouting, operating areas and obstacle areas, the internal route of the spraying area is obtained. The order of lines and waypoints are determined by choosing the shortest route. And this algorithm uses the Ray method to avoid the polygon obstacles and multi-obstacle areas. Operating results of different obstacle zones and heading angles are tested through simulation experiments. The best optimization radio is 14.2% when obstacle area is 800m2. Then aiming at the problem of over-dispatching of routes in some cases, MOAA algorithm is further optimized. Actual optimization length in field experiments is 75 meters (optimization radio is 7.7% ) when the heading angles is 315°. Field experimental results show that MOAA algorithm can select the best path scheme based on information such as obstacle height, area, etc.and it can improve the applicability of the plant protection UAV with autonomous operations.

The Fast Ray Tracing in Calculating the Geometrical Optics Reflected Field

We consider the problem of the computer-aided construction of geometrical optics electromagnetic wave propagation paths (ray tracing). We indicate the disadvantages of widely applied Shooting and Bouncing Rays method. We also provide the examples of its software implementation. As opposed to the employed approaches, the method and the algorithm synthesized on its basis are introduced for the reflected ray tracing where the search process is implemented faster and there are no disadvantages inherent in their common counterparts.

Effects of the symmetry axis orientation of a TI overburden on seismic images

In active tectonic regions, the primary formations are often tilted and subjected to the processes of folding and/or faulting. Dipping formations may be categorised as tilted transverse isotropy (TTI). While carrying out hydrocarbon exploration in areas of orogenic structures, mispositioning and defocusing effects in apparent reflections are often caused by the tilted transverse isotropy of the overburden. In this study, scaled physical modelling was carried out to demonstrate the behaviours of seismic wave propagation and imaging problems incurred by transverse isotropic (TI) overburdens that possess different orientations of the symmetry axis. To facilitate our objectives, zero-offset reflections were acquired from four stratum-fault models to image the same structures that were overlain by a TI (phenolite) slab. The symmetry axis of the TI slab was vertical, tilted or horizontal. In response to the symmetry axis orientations, spatial shifts and asymmetrical diffraction patterns in apparent reflections were observed in the acquired profiles. Given the different orientations of the symmetry axis, numerical manipulations showed that the imaged events could be well described by theoretical ray paths computed by the trial-and-error ray method and Fermat’s principle (TERF) method. In addition, outputs of image restoration show that the imaging problems, i.e. spatial shift in the apparent reflections, can be properly handled by the ray-based anisotropic 2D Kirchhoff time migration (RAKTM) method.

ARRC: A random ray neutron transport code for nuclear reactor simulation

A massively parallel implementation of a recently developed technique for numerically integrating the transport equation, The Random Ray Method (TRRM) (Tramm et al., 2017), is applied to several large reactor benchmark problems. The implementation, which is part of a new development called The Advanced Random Ray Code (ARRC), is one of the first parallel implementations of TRRM. Our goal is to better understand the accuracy and performance characteristics of TRRM on massive scale problems, and to provide community software that facilitates further algorithmic development and potentially its application to a broader class of problems. Key features of ARRC include extreme memory efficiency, domain decomposition, a task based parallel structure, and the ability to efficiently utilize Single Instruction Multiple Data (SIMD) vector units. These attributes lead to efficient performance on modern high performance computer (HPC) architectures, enabling the detailed simulation of reactor cores in three dimensions.

Moisture Measuring Device Based on Non-Destructive Method of Gamma Ray’s Attenuation

A moisture measuring device based on non-destructive method of gamma rays attenuation, allows measures to deepen concepts in building physics related to the moisture transfer; study the influence of the interface between layers in moisture transfer; analyse the influence of gravity on absorption and drying of different building materials; study the kinetics of absorption and drying of walls of one or more layers; analyse the importance of the temperature gradient in the movement of moisture; calculate the coefficient of water diffusivity of some building materials. In this work the proposed non-destructive method of gamma ray’s attenuation was used to analyse the transport of liquid water along a constructive element. For that propose gamma ray hydric profiles with red brick samples, 2 types: “A” and “B”, were obtained. Gamma ray hydric profiles are very interesting and original considering that the equipment exists in just a scarce laboratory. It is also intended to show how the equipment works and the way that those profiles can be taken. The water content profiles experimentally measure are very interesting, and the preliminary results obtained, for red brick samples with different densities and sectional area, will be shown and discussed.

IMPROVED METHOD OF INTERACTIVE DESIGN AND ADJUSTMENTS OF THE RATIONAL SCHEME OF PATTERING FLAT GEOMETRIC OBJECTS

This allowed to highlight the disadvantages of these methods and develop an improved method of interactive design and correction of rational schemes for the decomposition of flat geometric objects with different configurations of the external contour in a rectangular area of ​​the given size. In this method, it is possible to distinguish three main stages: the preliminary check of the intersection of rectangles, which are described around an active flat geometric object and a flat geometric object that has already been placed; If these rectangles intersect, check the intersection of these flat geometric objects by the ray tracing method; If these flat geometric objects do not intersect by the ray tracing method, then an additional check of their intersection by the ray method.
 The proposed method for designing dense layout schemes was implemented in a software product for interactive design and correction of rational schemes for the decomposition of dense combinations of flat geometric objects with different configurations of external contours in a rectangular area of ​​a given size. 
 An analysis of the existing methods of interactive design and correction of rational schemes for cutting flat geometric objects has been carried out.

Evidence for systemic age underestimation in shark and ray ageing studies

AbstractNumerous studies have now demonstrated that the most common method of ageing sharks and rays, counting growth zones on calcified structures, can underestimate true age. I reviewed bomb carbon dating (n = 15) and fluorochrome chemical marking (n = 44) age validation studies to investigate the frequency and magnitude of this phenomenon. Age was likely to have been underestimated in nine of 29 genera and 30% of the 53 populations studied, including 50% of those validated using bomb carbon dating. Length and age were strongly significant predictors of occurrence, with age typically underestimated in larger and older individuals. These characteristics suggest age underestimation is likely a systemic issue associated with the current methods and structures used for ageing. Where detected using bomb carbon dating, growth zones were reliable up to 88% of asymptotic length (L∞) and 41% of maximum age (AMax). The maximum magnitude of age underestimation, ΔMax, ranged from five to 34 years, averaging 18 years across species. Current perceptions of shark and ray life histories are informed to a large extent by growth studies that assume calcified ageing structures are valid throughout life. The widespread age underestimation documented here shows this assumption is frequently violated, with potentially important consequences for conservation and management. In addition to leading to an underestimation of longevity, the apparent loss of population age‐structure associated with it may unexpectedly bias growth and mortality parameters. Awareness of these biases is essential given shark and ray population assessments often rely exclusively on life history parameters derived from ageing studies.

Noise-Induced Chaos in a Piecewise Linear System

In the present paper, the phenomenon of noise-induced chaos in a piecewise linear system that is excited by Gaussian white noise is investigated. Firstly, the global dynamical behaviors of the deterministic piecewise linear system are investigated numerically in advance by using the generalized cell-mapping digraph (GCMD) method. Then, based on these global properties, the system that is excited by Gaussian white noise is introduced. Then, it is simplified by the stochastic averaging method, through which, a four-dimensional averaged Itô system is finally obtained. In order to reveal the phenomenon of noise-induced chaos quantitatively, MFPT (the mean first-passage time) is selected as the measure. The expression for MFPT is formulated by using the singular perturbation method and then a rather simple representation is obtained via the Laplace approximation, and within which, the concept of quasi-potential is introduced. Furthermore, with the rays method, the MFPT under a certain set of parameters is estimated. However, within the process of analysis, the authors had to face a difficult problem concerning the ill-conditioned matrix, which is the obstacle for the estimation of MFPT, which was then solved by applying one more approximation. Finally, the result is compared with the numerical one that is obtained by the Monte Carlo simulation.

The least square inversion method for the exterior ray transforms of 3D scalar and vector fields

Inversion of the scalar and vector ray transforms is performed in domain , ie, with the presence of an obstacle or singularity in the origin. Initially, the ray transforms of the basis functions for the scalar and vector fields are evaluated in an analytical form, and next, the inversion procedure is reduced to a linear system of equations by the use of the least squares method.

On the Calculation of the Morse Index and the Extension of Ray Formulas Beyond Caustics

Being the simplest and illustrative from the physical point of view, the ray method is extensively used for computations of short wave fields of a different physical nature: acoustic, electrodynamic, and elastodynamic. However it is not applicable in neighborhoods of caustics, where ray amplitudes get singular. Although caustics may appear in quantities in complex inhomogeneous media, they have zero measure, and therefore there are subdomains free of caustics in inhomogeneous media where ray formulas can be used for computations of wave fields. To this end it is necessary to calculate the phase jumps caused by the transition of rays through caustics. Mathematically, we must calculate the Morse index for a ray, i.e., the number of focal points (counting their multiplicity) on the ray between the source and the observation point. In the article, this problem is considered and a complete solution to it is given in the case of two space variables. Namely, a complex-valued function of the arc length along a ray is constructed and the increment of its argument between the source and the observation point, computed modulo 2π, gives the Morse index for that ray in the two cases where the field of rays is produced by a point source or is generated by an initially given wave front. Bibliography: 8 titles.

Broadband acoustic wave propagation in three-dimensional shallow waveguide with variable sound speed profile and boundary roughness

Propagation of broadband acoustic signals in shallow water environment is a complex four-dimensional problem that needs to be addressed with input from the spatial and temporal physical parameters of waveguides with rough boundaries. To construct a numerical model of this four-dimensional problem, methods such as the Parabolic Equation (PE), Horizontal Rays and Vertical Modes, 3D Ray Method, and Nx2D PE have been utilized in recent years. However, data/model comparison still remains a challenge and accurate comparison between measured and modeled acoustic fields in the waveguide is badly needed. Lack of environmental input to use for modeling is one reason, but with proper sampling of environment it may be overcome by novel experimental design based on the knowledge of waveguide physics. Acoustic frequency can also be utilized as one of the key parameters to simplify the problem and adopt strategies in conducting calibrated experiments. In this paper, we provide a broad view of recent advancements in three-dimensional acoustic wave propagation in shallow water waveguides in the presence of variable volumetric and boundary conditions. The effect of broadband acoustic wave center frequency and bandwidth with respect to the scale of environmental variability is also discussed. [Work supported by ONR 322 OA.]

The Random Ray Method for neutral particle transport

A new approach to solving partial differential equations (PDEs) based on the method of characteristics (MOC) is presented. The Random Ray Method (TRRM) uses a stochastic rather than deterministic discretization of characteristic tracks to integrate the phase space of a problem. TRRM is potentially applicable in a number of transport simulation fields where long characteristic methods are used, such as neutron transport and gamma ray transport in reactor physics as well as radiative transfer in astrophysics. In this study, TRRM is developed and then tested on a series of exemplar reactor physics benchmark problems. The results show extreme improvements in memory efficiency compared to deterministic MOC methods, while also reducing algorithmic complexity, allowing for a sparser computational grid to be used while maintaining accuracy.

Monostatic radar cross section of flying wing delta planforms

The design of the flying wing and its variants shapes continues to have a profound influence in the design of the current and future use of military aircraft. There is very little in the open literature available to the understanding and by way of comparison of the radar cross section of the different wing planforms, for obvious reasons of security and sensitivity. This paper aims to provide an insight about the radar cross section of the various flying wing planforms that would aid the need and amount of radar cross section suppression to escape detection from surveillance radars. Towards this, the shooting and bouncing ray method is used for analysis. In this, the geometric optics theory is first used for launching and tracing the electromagnetic rays to calculate the electromagnetic field values as the waves bounce around the target. The physical optics theory is next used to calculate the final scattered electric field using the far field integration along the observation direction. For the purpose of comparison, all the planform shapes are assumed to be having the same area, and only the aspect ratio and taper ratio are varied to feature representative airplanes.

Horizontal–Longitudinal Spatial Correlation of Acoustic Field with Deep Receiver in the Direct Zone in Deep Water**Supported by the National Natural Science Foundation of China under Grant No 11174235.

The horizontal–longitudinal correlation of acoustic field for the receiver near the bottom is analyzed by using numerical modeling. An approximate analytical solution of horizontal–longitudinal correlation coefficient is derived based on the ray method. Combining the characteristic of Lloyd’s mirror interference pattern, the variability of acoustic field and its effect on horizontal–longitudinal spatial correlation are discussed. The theoretical prediction agrees well with the numerical results. Experimental results confirm the validity of analytical solution. Finally, the applicability of the analytical solution is summarized. The conclusion is beneficial for the design of bottom-moored array and the estimation of integral time for moving source localization.

Rapid X-ray based determination of moisture-, ash content and heating value of three biofuel assortments

Here we demonstrate a new hyphenated X–ray method, qDXA–XRF, for the simultaneous determination of moisture–, ash content and heating value (as received) of biofuels. The method is based on the combination of X-ray transmission imaging and X–ray fluorescence spectroscopy.The method performance is demonstrated using three biofuel assortments; logging residues, roundwood chips and sawdust, on approximately 3 L samples (∼500–1500 g) with a total analysis time of one minute per sample.Mean absolute errors for the logging residues, roundwood chips and sawdust determinations respectively were; for moisture content MAE = 0.034, 0.026, 0.011 (wet basis mass fraction), for ash content MAE = 0.0015, 0.0015, 0.0049 (dry basis mass fraction), and for heating value (as received) MAE = 0.55, 0.44, 0.17 MJ kg−1.Furthermore, for the assortment logging residues, the qDXA–XRF determination of heating value decreases the measurement uncertainty from MAE = 1.53 to 0.55 MJ kg−1 (∼60% decrease) compared with traditional oven moisture/equation method.

用射线法定量分析三元相图

作者提出一种新的方法–射线法–定量地分析三元相图，简单介绍了射线法的原理和方法。作为例子，用射线法定量分析了W-Cr-C三元相图等温截面二相区中的合金以及Fe-C-P三元相图投影图中高磷灰铸铁的结晶过程，计算了组织组成物的相对量。与高磷灰铸铁组织的对比结果表明，射线法是可靠的。 In this paper, a new method-the ray method-was proposed for quantitative analysis of ternary phase diagram, and the brief principle and method of the ray method were introduced. As examples, the crystallization processes of an alloy in two-phase region of isothermal section of W-Cr-Ni ternary phase diagram as well as a high-phosphorus gray cast iron in projection of Fe-C-P ternary phase diagram were quantitatively analyzed by the ray method, and the relative amounts of structural compositions were calculated. The result of the comparison with the microstructure of a high phosphorus gray cast iron showed that the ray method is reliable.

Analysis on Human Blockage Path Loss and Shadow Fading in Millimeter-Wave Band

Millimeter-wave (Mm-w) is the trend of communication development in the future; users who carry mobile communication equipment could be blocked by others in a crowded population environment. Based on Shooting and Bouncing Ray (SBR) method and setting up different orientation receivers (RX), population density, and people fabric property at 28 GHz and 38 GHz, simulating experimental scene similar to station square by Wireless Insite software, we use least square method to do linear-regression analysis for path loss and build path loss model. The result shows that the path loss index has a certain change in the different frequency, orientation receivers, population density, and people fabric. The path loss index of RouteC1 and RouteA2 has an obvious change in the central transmitter (TX). Each route shadow fading obeys Gaussian distribution whose mean is 0. This paper’s result has a theoretical guiding for designing the communication system in a crowded population environment.

A New Shooting Bouncing Ray Method for Composite Scattering from a Target above the Electrically Large Scope Sea Surface

A new shooting and bouncing ray (SBR) simulator based on the hybrid scheme of GO/PO/SDFM/EEC method is developed for the accurate prediction of composite scattering from a low altitude target above the electrically very-large-scale sea surface. It can adequately deal with the complex local electromagnetic interactions between the target and the large scope sea surface. The method is compared with the exact computational electromagnetic solver FEKO-MLFMM to validate its accuracy and efficiency. Then, it is applied to simulate the bistatic and monostatic scattering characteristics of an airplane above the electrically large sea surface at X-band, for different sea states. The results reveal the contributions from the target, sea surface, and interactions, which are of significance for radar target detection and remote sensing in real maritime environments.