Three-dimensional Scheme Research Articles

Energy-Efficient Solutions in Design, Construction and Operation of Thermal Power Plants and Heating Networks

The article deals with topical issues related to the introduction of energy-efficient measures in the energy sector of Russia. A comprehensive study and research of the current situation in the field of technological processes for generating electric and thermal energy of thermal power plants (hereinafter TPP), transportation and distribution of energy in thermal networks has been carried out. The analysis of the main equipment and the parameters of the working environment influence on the efficiency of the thermal power plant, taking into account the technological features and energy losses of the steam power cycle of heat and electric power generation, was carried out. The main existing problems and sources of energy losses in heat supply systems are considered. Recommendations are given for introduction and development of energy-efficient solutions and technologies in the design, construction and operation of thermal power plants and heating networks. Promising measures aimed at maximum effect of energy saving are proposed for consideration, including the design and construction of new or modernization of existing thermal power plant equipment, the introduction of combined-cycle power plants, the use of frequency drives of critical rotating mechanisms, the introduction of automatic or remote manual process control systems, the introduction of digital production, including digital counterparts of objects, digital heating points and electrical substations, installation of additional sensors and metering devices with the introduction of monitoring systems and predictive prognostics of equipment, the use of geo-information systems with visualization of three-dimensional schemes and the development of mathematical models of heating networks, carrying out a full-scale instrumental control of critical pipelines metal using robotic complexes. Practical examples of energy-efficient measures application at existing thermal power plants and heating networks are given.

Calculating the Possibility of Data Transmission in Trunking Communication Systems

In the present article, a calculation of a radio-relay communication line has been carried out in order to determine the operability of the selected location of the radio-relay communication on the designed route to ensure the required quality of communication. The classification of radio communication systems and, specifically, trunking communication systems (TCS) is given. The process of assessing the service area of TCS is considered. A comparative analysis of information transmission in analog and digital TCS has been carried out. The authors discuss advantages and disadvantages of communication channel access methods and describe a technology for creating three-dimensional schemes on plastics and flexible media, the advantage of which is the arrangement of elements at an angle, precise positioning of elements, freedom in choosing geometric shapes, and the possibility of its application in radio communication devices. The procedure for constructing a technological process using one of the most common technologies - LPKF-LDS®implemented in the laboratory of three-dimensional circuits on plastics and flexible media of the Institute of Radio Electronics and Informatics of MIREA-Russian Technological University, is considered. The classification of intervals of radio relay lines is given and the calculation of the Fresnel zone is carried out. The minimum suspension heights of base station antennas are calculated, at which the RRL interval would be open

Identifying key elements for user satisfaction of bike-sharing systems: a combination of direct and indirect evaluations

Bike-sharing systems (BSS) are gaining popularity in cities worldwide, as a part of a generalized strategy to mitigate the problems derived from motorized transportation (congestion, pollution, noise, etc.). These systems have proved to have positive effects on cities, moreover, many of them have reached a performance peak and require improvements to attract/retain users and compete against emerging soft mobility alternatives. Whilst there are broad studies evaluating BSS demand and design, less attention has been paid to user satisfaction and the complexities underlying the relationships between the system attributes importance. This study proposes a novel combination of two methodologies for satisfaction assessment that allows decision-makers to identify the most influential system attributes on user satisfaction. The combined methods are the direct, explicit, Importance Performance Analysis (IPA), and the nonlinear, implicit Three-Factor Theory (3FT), which combined generate a three-dimensional scheme that facilitates the comprehension of the results. The combination was applied to a dataset of Madrid´s BSS to identify the attributes that perform poorly, and then assess their implicit influence on satisfaction to establish improvement priorities. The results suggest that station occupancy and bicycle availability and totem functioning are key service attributes to enhance satisfaction. Also, the combination of the two methodologies makes it possible to differentiate that maintenance is a priority for subscribers and network extension for occasional users. The pedelec system is a key attribute that might help overcome Madrid´s unfavorable cycling environment. This user-centric evaluation is a valuable tool that guides precise measure implementation, service operation, future design, and planning oriented to increase ridership.

Analyzing the impact of three-dimensional visibility value on shopping center retail unit rental prices

This research examines the effect of a three-dimensional visibility value variable on shopping experience and estimates the contribution to retail units’ rental prices for shopping centers. The visibility value in a three-dimensional scheme is measured by adding storefront area volume to existing two-dimensional calculations. This study utilized an explanatory research design and a quantitative analysis method—a STATA regression test—for 150 store units in Jakarta. All units are permanent physical stores, excluding food courts, anchor, and exhibitions. The results showed that visibility value has the positive effect of increasing the average initial rental price by 6% (IDR15,403). The findings of this research can be useful for shopping center managers when estimating rental rates for retail units and architects when considering the visibility factor when designing shopping centers.

A positivity-preserving and free energy dissipative hybrid scheme for the Poisson-Nernst-Planck equations on polygonal and polyhedral meshes

This paper develops a positivity-preserving and free energy dissipative hybrid scheme for the multi-dimensional Poisson-Nernst-Planck equations with multiple ions on unstructured polygonal and polyhedral meshes. It is built on the linear virtual element method for the Poisson-type equation for the electrostatic potential and a cell-centered finite volume scheme for the Nernst-Planck equations for the ion concentrations, and preserves the positivity of the ion concentrations, the mass conservation, the free energy dissipation and steady-state properties. The existence of the numerical solutions is also discussed. Numerical results demonstrate the effectiveness of the proposed two- and three-dimensional schemes.

Towards Unified Literature Representations: Applications in Information Systems and Entrepreneurship Research

Abstract Research activity is becoming increasingly complex due to the nature of research topics and questions. Among the essential academic research activities are literature reviews (LR), as they support the advance of the knowledge frontier. To improve literature reviews and their understanding, it would need to have comprehensive literature representations. In this perspective, the paper aims to advance previous work by illustrating a new way of creating thorough literature representations. The proposed tool is innovative and versatile since authors can adopt it in different types of LRs. Its adoption implies the construction of a three-dimensional scheme for the classification of the literature to be analysed. Then, based on the latter and selecting suitable evaluation variables, the proposed approach produces informative multidimensional representations for literature mapping and bibliometric analysis. For exemplifying this, the paper provides two application cases concerning Enterprise Resource Planning (ERP) systems and entrepreneurship research.

The Major Role of Eccentricity in the Evolution of Colliding Pulsar-Stellar Winds

Binary systems that host a massive star and a non-accreting pulsar can be powerful non-thermal emitters. The relativistic pulsar wind and the non-relativistic stellar outflows interact along the orbit, producing ultrarelativistic particles that radiate from radio to gamma rays. To properly characterize the physics of these sources, and better understand their emission and impact on the environment, careful modeling of the outflow interactions, spanning a broad range of spatial and temporal scales, is needed. Full three-dimensional approaches are very computationally expensive, but simpler approximate approaches, while still realistic at the semi-quantitative level, are available. We present here the results of calculations done with a quasi three-dimensional scheme to compute the evolution of the interacting flows in a region spanning in size up to a thousand times the size of the binary. In particular, we analyze for the first time the role of different eccentricities in the large scale evolution of the shocked flows. We find that the higher the eccentricity, the closer the flows behave like a one-side outflow, which becomes rather collimated for eccentricity values ≳0.75. The simulations also unveil that the pulsar and the stellar winds become fully mixed within the grid for low eccentricity systems, presenting a more stochastic behavior at large scales than in the highly eccentric systems.

Crustal magma plumbing system beneath the Quaternary volcanic area (northern Hainan Island, China) revealed by magnetotelluric data

Magma plumbing system in active volcano can transport and store magmas, which is a key element for hazard assessment. The Quaternary volcano cluster of northern Hainan Island, an active volcano area in China, has been associated to a mantle plume. However, certain details such as the pathway of the ascent of magma and its storage in the crust remain unclear. In this work, a 68 km long magnetotelluric profile was deployed including 33 broadband sounding sites across the volcanoes to study the crustal magma plumbing system. Data were inverted using a three-dimensional scheme to image the resistivity structure beneath profile. The resistivity model shows a well-developed shallow low-resistivity zone in the west of Changliu-Xiangou Fault corresponding to the Fushan depression, two high conductors in the depths of ~5–12 km, and a relatively low resistivity layer in the lower crust and uppermost mantle. The conductors in the middle-upper crust were preferably attributed to the accumulation of fluids transported via conduits, while the deeper conductive layer could be ascribed to the presence of crystal mushes. The obtained resistivity structure supports that the crustal magma system of northern Hainan Island is in a state of stability at present, whereas the secular monitoring is still necessary.

Enhanced Pulsed-Source Localization with 3 Hydrophones: Uncertainty Estimates

The uncertainty behavior of an enhanced three-dimensional (3D) localization scheme for pulsed sources based on relative travel times at a large-aperture three-hydrophone array is studied. The localization scheme is an extension of a two-hydrophone localization approach based on time differences between direct and surface-reflected arrivals, an approach with significant advantages, but also drawbacks, such as left-right ambiguity, high range/depth uncertainties for broadside sources, and high bearing uncertainties for endfire sources. These drawbacks can be removed by adding a third hydrophone. The 3D localization problem is separated into two, a range/depth estimation problem, for which only the hydrophone depths are needed, and a bearing estimation problem, if the hydrophone geometry in the horizontal is known as well. The refraction of acoustic paths is taken into account using ray theory. The condition for existence of surface-reflected arrivals can be relaxed by considering arrivals with an upper turning point, allowing for localization at longer ranges. A Bayesian framework is adopted, allowing for the estimation of localization uncertainties. Uncertainty estimates are obtained through analytic predictions and simulations and they are compared against two-hydrophone localization uncertainties as well as against two-dimensional localization that is based on direct arrivals.

PARALLEL MANIPULATOR MECHANISM FOR USE IN ROBOTIC SURGERY

The article examines the mechanisms of parallel and parallel-sequential structure, including specific translational-guides, flat, spherical mechanisms of a parallel structure with three degrees of freedom, modifications of Delta robots from various manufacturers. The most famous studies of robots of parallel-serial structure are presented. Mazor Renaissance and Mazor X robotic systems for robotic assistance during spinal surgery are examined. The method of synthesis of mechanisms of parallel-serial structure with five degrees of freedom is briefly presented. Examples of synthesised schemes of mechanisms and three-dimensional schemes, synthesised using in the computer-aided design system Compass 3D, are given. A diagram of a mechanism of a parallel-sequential structure with five degrees of freedom for robotic assistance during minimally invasive operations, which can be used as an alternative to the da Vinci Surgical System Platform, is examined. An example of modelling the solution of the inverse problem of positions, direct and inverse problems of velocities and direct and inverse dynamic problems in the Mathcad system, the result of modelling the motion of the output link in various initial conditions is given. The results of experimental studies using a prototype mechanism are shown.

Short-term geomorphological evolution of the Poggio Baldi landslide upper scarp via 3D change detection

On 19 March 2010, a 4 million m3 landslide occurred at Poggio Baldi, a small village in the Santa Sofia municipality, central Apennines (Forlì-Cesena, Italy). The landslide caused severe damages to some homes and obstructed both the SS310 national road and the Bidente river. The Poggio Baldi landslide arose in the “Marnoso-Arenacea Romagnola” formation composed of a pelitic-arenaceous turbiditic sequence. The landslide was classified as a rotational landslide, evolving into a partially confined flow-like landslide and causing the reactivation of the deposit of a previous landslide that took place in 1914. This paper reports a study of the phenomena currently occurring on the 100-m high main scarp of this landslide complex. The aim of the study was to assess ground changes that occurred on the upper scarp from 2015 to 2018 and to infer a preliminary evolutionary model capable of supporting short-term landslide scenarios. For this purpose, multi-station terrestrial laser scanner surveys were performed in 2015, 2016, 2017, and 2018. Additionally, an unmanned aerial vehicle three-dimensional photogrammetric survey was carried out in 2016. Analyses of the three-dimensional digital models of the main scarp made it possible to carry out several exhaustive multi-temporal investigations and to derive a detailed three-dimensional change detection scheme for it. The results showed an active geomorphological evolution of the rock scarp area due to frequent rockfalls and topples (of the order of a few m3), with significant local volume changes (a few thousand m3/year) and with potential implications for the long-term evolution of the entire slope.

LPKF-LDS technology for the production of three-dimensional schemes on plastics

A promising technology for the production of three-dimensional circuits on plastics, the scope of its current application and prospects for its further development in the radio-electronic industry are considered. The analysis of current opportunities and limitations is carried out. It is shown that the key component of the technology is the correct choice of thermoplastics with suitable characteristics for the intended object, taking into account the resistance to external factors. An analysis of the international and domestic regulatory framework for thermoplastics was conducted. This allowed to determine the key characteristics for 3D-MID-technology and to make a comparison. A classification is proposed on the basis of the key characteristics of thermoplastics for making a decision when choosing materials on the market, taking into account the application in the radio-electronic industry using 3D-MID technology, which is currently either absent or not fully represented. Methods of testing materials for use in the production technology of three-dimensional circuits on plastics and ensuring the quality of manufacturing of radio engineering products, allowing to confirm the compliance of key parameters of materials are studied. The article considers the order of the build process with the application of the LPKF-LDS technology production of three-dimensional circuits on plastics, which allows building a sequence of processes with particular implementation as an example. The considered LPKF-LDS technology as part of the 3D-MID line is planned in the new laboratory “Threedimensional circuits on plastics and flexible media” at the Department of Design and Production of Radioelectronic Devices of the Institute of Radio Engineering and Telecommunications Systems of MIREA – Russian Technological University.

3D general-measure inversion of crosswell EM data using a direct solver

Abstract We present a three-dimensional (3D) general-measure inversion scheme of crosswell electromagnetic (EM) data in the frequency domain with a direct forward solver. In the forward problem, we discretised the EM Helmholtz equation by the staggered-grid finite difference (SGFD) scheme and solved it using the Intel MKL PARDISO direct solver. By applying a direct solver, we simultaneously solved the multisource forward problems at a given frequency. In the inversion, we integrated a general measure of data misfit and model constraints with linearised least-squares inversion. We reconstructed a model with blocky features by selecting the appropriate measure parameters and model constraints. We used the adjoint equation method to explicitly calculate the Jacobian matrix, which facilitated the determination of an appropriate initial value for the regularisation coefficient in the objective function. We illustrated the inversion scheme using synthetic crosswell EM data with a general measure, the L2 norm, and, specifically, two mixed norms.

Anthropology of a city: organization, communication, information

The article is concerned with the anthropology of a city. As an instrument of conceptualization, we used a three-dimensional scheme: organization — communication — information, which allows giving the urban interpre-tation for each of the coordinates, and then, using the two-dimensional projections (organization-information, or-ganization-communication, information-communication), to develop a concept of the three-dimensional image of city. It has been proposed to distinguish three types of organizational structures when considering the city as an organization: hierarchical, algorithmic, and relational. The necessity of curbing the growth of the city and solidat-ing it in the context of communication has produced a number of projections. One of them, "A compact city or city of short distances" has been considered. The concept of a compact city is based on the cost-effective public transport system, and it encourages pedestrian traffic and cycling. When considering the city as an organization, the main focus lies on its structure. From a topological point of view, it has been proposed to distinguish between three types of such structures: hierarchical, algorithmic, and relational. A hierarchical structure represents a tree of power hierarchy, but its content is not necessarily associated with consistent delegation of authority power (from top to bottom) or gradual accumulation of information (from the bottom up). Thus, a library catalogue, as well as other classification means, is arranged on the principle of hierarchy. An algorithmic structure is a scheme of production process which consists of a set of sequential operations. Its mathematical model appears as a net-work diagram. Typical examples of such structures include an algorithm of construction of a building, from founda-tion to roof, a conveyed assembly of complex technical devices, etc. In relation to a city, this structure can be filled with different content. Thus, carrying out of repair and maintenance in one of the city networks often requires not only formal coordination, but also a network schedule of joint work with other community services (water, electric-ity grid, heating, communication lines, etc.). A relational structure is a group of objects of arbitrary nature, usually of the same type, singled out from the total quantity of objects on the basis of any common feature. A complex of educational or medical institutions, trade companies, domestic services, etc. could be an example of such group within the organizational structure of a city.

Convergence and Accuracy of the Method of Iterative Approximate Factorization of Operators in Multidimensional High-Accuracy Bicompact Schemes

The convergence and accuracy of a method for solving high-order accurate bicompact schemes having the fourth order of approximation in spatial variables on a minimum stencil for a multidimensional inhomogeneous advection equation are investigated. The method is based on the approximate factorization of difference operators of multidimensional bicompact schemes. In addition, it uses iterations to preserve a high (higher than the second) order of accuracy of bicompact schemes in time. The convergence of these iterations for both two- and three-dimensional bicompact schemes as applied to the linear inhomogeneous advection equation with positive constant coefficients is proved using the spectral method. The efficiency of two parallel algorithms for solving equations of multidimensional bicompact schemes is compared. One of them is the spatial marching algorithm for calculating unfactorized schemes, and the other is based on iterative approximate factorization of difference operators of the schemes.

Theoretical and experimental investigations of vertical hole transport through unipolar AlGaN structures: Impacts of random alloy disorder

We report on the vertical hole transport through unipolar unintentionally doped (UID) and p-type doped AlGaN heterostructures to evaluate the effectiveness of the UID and doped AlGaN as barriers to the hole transport. Band diagram and current density–voltage (J–V) simulations are conducted in one-dimensional and three-dimensional schemes, with the latter including compositional fluctuations within the alloy AlGaN barrier layer. The simulation results using a self-consistent Poisson-drift diffusion scheme, incorporating the Localization Landscape theory, indicate a large asymmetric barrier to the hole transport by UID AlGaN. The asymmetric J–V characteristics are attributed to the asymmetric band diagrams calculated for the unipolar structure. The simulation results are verified by experiments using unipolar vertical hole transport structures enabled by n-to-p tunnel junctions (TJs) grown by ammonia molecular-beam epitaxy. The TJ structures are utilized to minimize the issues with the high spreading resistance of p-regions and to eliminate the need for its dry etching, which normally results in degraded p-contacts. The experimental results show that even a thin UID AlxGa1−xN (x = 14%, 13 nm) introduces an asymmetric barrier to the hole transport; a nearly 100% increase in the voltage drop induced by a thin UID AlGaN at 50 A/cm2 in the reverse direction is observed compared to an only 25% corresponding increase in the forward direction. Furthermore, p-type doping of the AlGaN layer results in a drastic drop in the potential barrier to hole transport in both directions. The results are beneficial for understanding the behavior of various structure designs within optoelectronics and power electronics.

High-order gas-kinetic scheme with three-dimensional WENO reconstruction for the Euler and Navier-Stokes solutions

In this paper, a simple and efficient third-order weighted essentially non-oscillatory (WENO) reconstruction is developed for three-dimensional flows, in which the idea of two-dimensional WENO-AO scheme on unstructured meshes [42] is adopted. In the classical finite volume type WENO schemes, the linear weights for candidate stencils are obtained by solving linear systems at Gaussian quadrature points of cell interface. For the three-dimensional scheme, such operations at twenty-four Gaussian quadrature points of a hexahedron would reduce the efficiency greatly, especially for the moving-mesh computation. Another drawback of the classical WENO schemes is the appearance of negative weights with irregular local topology, which affect the robustness of spatial reconstruction. For the three-dimensional WENO-AO scheme, a simple strategy of selecting big stencil and sub-stencils for reconstruction is proposed. With the reconstructed quadratic polynomial from big stencil and linear polynomials from sub-stencils, the linear weights are chosen as positive numbers with the requirement that their summation equals to one and be independent of local mesh topology. With such WENO reconstruction, a high-order gas-kinetic scheme (HGKS) is developed for both three-dimensional inviscid and viscous flows. Taken the grid velocity into account, the scheme is extended into the moving-mesh computation as well. Numerical results are provided to illustrate the good performance of such new finite volume WENO scheme. In the future, such WENO reconstruction will be extended to the unstructured meshes.

Attempting to Model a Fresh Three Dimensional Coverage Scheme for Wireless Sensor Networks

The coverage framework and the installation policies are straightforwardly linked to the feasible distribution of the restricted resources for the wireless sensor network like node energy, transmission bandwidth and energy for estimation along with the quality enhancement which is immensely resolved for the wireless sensor networks. A three-dimensional coverage model and installation scheme are designed which initially performs an assessment of the usual polyhedron frameworks in the three-dimensional prospects, a coverage model based on cuboids is proposed. The association among the coverage and sensor nodes is assumed along with the minimal number of sensor nodes to preserve the network regions comprehensive coverage is estimated. Lastly, the sensor nodes are installed based on the coverage model after the observation region which is subclassified into restricted three-dimensional grids. The results of analysis reveal that the evaluation against the conventional arbitrary schemes, the sensor number of sensor nodes are minimized efficiently based on the precise ratio of coverage employing the coverage framework and deterministic installation methods.

Unsteady Heat Transfer for Pressure Vessels in Atmospheric Flight at Orbital Velocities

Aeroassisted trajectories can be used to minimize spacecraft propellant requirements for near-Earth orbital operations. A review of spacecraft flight mechanics, aerothermodynamics, and energy balances relevant for near-term designs of reusable upper stages is presented. A reusable upper stage is modeled by a rigid tank containing liquid propellant with some propellant fraction undergoing phase change, while in an a planar aeroassist trajectory about an idealized Earth. Shortcomings of classical analyses are illustrated to motivate models with increased fidelity and complexity. A new method is proposed and models the material response of the spacecraft under aerothermal loading, that couples the simplicity of classical methods with a three-dimensional scheme that captures unsteady thermal gradients in the material. The new method is shown to provide similar solutions to a fully discrete case with a significant reduction in computational time.

Implementation of convolutional perfectly matched layer for three‐dimensional hybrid implicit‐explicit finite‐difference time‐domain method

The hybrid implicit-explicit (HIE) finite-difference time-domain (FDTD) method with the convolutional perfectly matched layer (CPML) is extended to a full three-dimensional scheme in this article. To demonstrate the application of the CPML better, the entire derivation process is presented, in which the fine scale structure is changed from y-direction to z-direction of the propagation innovatively. The numerical examples are adopted to verify the efficiency and accuracy of the proposed method. Numerical results show that the HIE-FDTD with CPML truncation has the similar relative reflection error with the FDTD with CPML method, but it is much better than the methods with Mur absorbing boundary. Although Courant-Friedrich-Levy number climbs to 8, the maximum relative error of the proposed HIE-CPML remains more below than −71 dB, and CPU time is nearly 72.1% less than the FDTD-CPML. As an example, a low-pass filter is simulated by using the FDTD-CPML and HIE-CPML methods. The curves obtained are highly fitted between two methods; the maximum errors are lower than −79 dB. Furthermore, the CPU time saved much more, accounting for only 26.8% of the FDTD-CPML method while the same example simulated.