Analytical Calculation Method Research Articles

Multi-objective Optimization of Mapping Dataflow Applications to MPSoCs Using a Hybrid Evaluation Combining Analytic Models and Measurements

Dataflow modeling is well suited for a large variety of applications for modern multi-core architectures, e.g., from the signal processing and the control domain. Furthermore, Design Space Exploration (DSE) can be used to explore mappings of tasks to hardware resources (cores of an MPSoC) and their scheduling to obtain optimized trade-off solutions between throughput and resource costs. However, the throughput evaluation of an implementation candidate via compilation-in-the-loop or simulation-based approaches can be extremely time-consuming. Such a deficiency is very detrimental, because a typical DSE run needs to evaluate thousands of implementation candidates. As a remedy, we propose a hybrid-adaptive DSE where a max-plus algebra-based analytic throughput calculation method is used in the initial DSE phase to enable a fast progress of the search space exploration. However, as this analysis may be inaccurate as neglecting some real-world effects like cache and scheduling overhead, throughput measurements are taken later in the DSE. Moreover, we explore the trade-off between scheduling efficiency of implementation candidates—in favor of reducing concurrency—and exploiting concurrency to a large extent for parallel execution of the application. To find solutions of highest achievable throughput, it is shown that not only highly scheduling efficient implementation candidates but also highly parallel implementation candidates are essential when determining the initial population. In this realm, we contribute a method for diversity-based population initialization. For a representative set of benchmarks, it is shown that the combination of the two major contributions allows us to find much higher throughput multi-core solutions within a given exploration time compared to a state-of-the-art DSE approach.

Experimental and analytical study on continuous GFRP-concrete decks with steel bars

A hybrid bridge deck is proposed, which includes steel bars, concrete and glass-fiber-reinforced-polymer (GFRP) plates with channel sections. The steel bar in the negative moment region can increase the flexural stiffness, improve the ductility, and reduce the GFRP ratio. Three continuous decks with different steel bar ratios and a simply supported deck were fabricated and tested to study the mechanical performance. The failure mode, deflection, strain distribution, cracks and support reaction were tested and discussed. The steel bar improves the mechanical performance of continuous decks, and a theoretical method is proposed to predict the deformation and the shear capacity. The experimental results show that all specimens failed with shear failure in the positive moment region. The increase of steel bar ratio in the negative moment region can achieve an enhancement in the flexural stiffness and reduce the deflection without increasing GFRP. Moreover, the continuous deck can achieve a yield load, and the negative moment can be carried by GFRP plates after the steel bar yields. Finally, a nonlinear analytical method for the deflection calculation was proposed and verified, with considering the moment redistribution, non-cracked sections and nonlinearity of material. In addition, a simplified calculation method was proposed to predict the shear capacity of GFRP-concrete decks.

ВПЛИВ РІЗНИХ ПАРАМЕТРІВ СТАБІЛЬНОСТІ ВИРОБНИЧИХ ДІЛЬ-НИЦЬ НА ЕФЕКТИВНІСТЬ ФУНКЦІОНУВАННЯ ДЕРЕВООБРОБНОГО ВИРОБНИЦТВА

The article describes the study of the influence of the stability of production sites on the efficiency of automatic woodworking production lines. A new method of analytical calculation of equivalent stability parameters for multi-part production systems of sequential layout is proposed. With the help of analytical and simulation models of automated production systems of different productivity, the influence of equipment stability on system productivity is investigated. Improving the productivity of production systems is carried out through the optimal layout of equipment and structural and parametric optimization. The aim of the study is to determine the impact of the stability of technological equipment on the performance of automated production systems in terms of random effects on the technological process. It is too difficult for stochastic production systems to investigate the process. It is very difficult to establish analytical dependences of indicators of technological processes on operating conditions. Such problems can be solved using simulation methods. At the same time, the computer processes simulate the functioning of automated production systems. Investigating the operation of automated production systems in stochastic conditions on simulation models, it is possible to scientifically substantiate the optimal parameters of automated systems in terms of productivity, stability, reliability and cost-effectiveness. As a result, ways to increase the productivity of the production system are established. The layout of automated production systems with modern high-performance machines significantly improves productivity, but is not always economically feasible, because it does not eliminate the influence of stochastic factors on the efficiency of the technological process, but creates more complex stochastic processes. Modern methods for estimating the impact of different values of the stability parameter on the efficiency of automated production systems are incomplete. It is proposed to use analytical solutions and simulation modeling to study production systems.

NEW COMPOSITE BARKER CODES IN THE SYNCHRONIZATION SYSTEM OF BROADBAND SIGNALS

Background. At present, the demand for broadband signals (BВS) is determined by the qualities inherent in these signals, which make it possible to ensure high noise immunity of broadband communication systems (BСS) when transmitting confidential information in an open radio channel, especially in emergency situations. Although the foundations of the BВS theory are well known, the development of wireless communication networks requires constant refinements of theoretical provisions in accordance with new data on methods for constructing Barker code sequences used in wireless communicationsystems with direct sequence spread spectrum technology.Objective. The aim of the paper is to study new composite Barker codes as synchronization signals and compare them with known composite codes using simulation.Methods. Analytical methods of calculation are used, as well as simulation modeling in the MatLab software package.Results. Simulation modeling was carried out, which confirmed the possibility of using new composite Barker codes as synchronization signals in the BCS.Conclusions. Modeling in the MatLab software package showed a greater noise immunity of new composite codes to the influence of various modulating sequences of an information signal in comparison with known composite codes.

Transient Roebel Bar Force Calculation in Large Salient-Pole Synchronous Machines

The radial and tangential force components acting on each sub-conductor of a Roebel bar in a large generator lead to mechanical vibration of the stator bars in the slot. This double-frequency vibration results in additional mechanical stress on fixation materials in the slot and causes insulation deterioration and looseness of stator bars. Particularly during short circuits, the stator bars are subjected to immense radial forces. Understanding the origin of these vibrations and developing models to anticipate them is essential to increase the reliability and expected life time of large generators. This paper presents an analytical method for the estimation of Roebel bar forces during symmetrical and asymmetrical short circuits. For this purpose, an analytical calculation method is developed to estimate the transient three-phase currents during different short circuits. These currents induce tangential and radial flux density components along the slot width and length, respectively. An analytical approach is introduced to estimate these flux densities as a function of the slot length. Subsequently, an analytical method for calculating the Roebel bar forces considering three-dimensional transpositions is developed and verified with finite element calculations. Beyond the state of the art, the impact of the rotor field on the radial and tangential components of the stray fluxes are analytically estimated. The result is a comprehensive analytical tool for the estimation of Roebel bar forces during different short circuits in large generators.

Study of modern software capabilities for complex shell analysis

Relevance. In design and calculation of civil engineering structures, several standard commercial software packages, which are successfully applied to solve everyday engineering problems, are traditionally used. However, when it is necessary to design the models of complex shape shell structures with defining surfaces based on parametric equations, such programs often have certain drawbacks. The aim of the work - analysis of existing types of commercial computational software packages in order to check which allow to design finite element models for shell structures with median surfaces of complex geometry given by parametric equations. Methods. The analysis of commercial computational software packages is carried out by studying the software manuals, and by building and calculating a model in the shape of a right helicoid as a test example. To evaluate the results of the stress-strain state of a shell with a middle surface in the form of a right helicoid, an analytical calculation method based on the Reissner’s equations and Fourier series expansion is used. Results. A review of modern commercial computational software packages as applied to models defined by parametric equations is carried out. A model for a shell structure with a median surface in the form of right helicoid is built. The numerical results of stress-strain behavior of the right helicoid are obtained and analyzed in comparison with the analytical solutions obtained using the Reissner’s equations with Fourier series expansion. The pros and cons of several popular means of software are presented.

Multiple Linear Regression Method for Deeper Analyses of Abrasive Tribological Behaviour of Engineering Materials

Tribology (friction, wear, lubrication) studies the elements made of different materials in relative motion. While the individual materials can be well characterized e.g. by their physical and chemical properties the description and prediction of the friction and wear behaviour is not an easy task. There is no uniform, analytical calculation method, because the behaviour of the structural materials depends on the operating conditions and the effects occurring during operation, thus, the tribological behaviour is system dependent. In order to have information about wear, friction and heat generation during operation, it is advisable to use the modelling method. The result of either mechanical or numerical modelling can help machine designers. The use of simplified models performed under laboratory conditions (DIN50322, testing category VI.)

Calculation of displacements and internal forces of anchored retaining piles.

Pile-anchor retaining structures are widely used in excavation engineering. The evaluation of lateral displacements, the internal forces of piles are extremely important for the performance of the structure. Most of the existing methods are empirical, semiempirical or FEM methods, while analytic calculation methods for this evaluation are rare. This paper presents an analytic method to calculate the displacements and internal forces of anchored retaining piles based on the existing design code. In the calculation method, the singular function is applied to evaluate the effect of segmented loading on the deflection of a beam with a nonuniform cross section. The load concentration function, expressed by the singular function, can describe the segmented load and be integrated without a complicated procedure for determining the integral constants. The method is applied to a structure in Wenzhou, China, and the calculation results are compared to the field measurement results. This method is only valid for pre-failure predictions.

КООРДИНАТНИЙ МЕТОД ВИЗНАЧЕННЯ ШЛЯХОВОЇ ШВИДКОСТІ СУДНА ПО ВЕКТОРАМ ТА ПЕРЕМІЩЕННЯМ ВІДНОСНОЇ ТА ПЕРЕНОСНОЇ ШВИДКОСТЕЙ

During the movement of the vessel along the route there is a problem of observation of natural and man-made obstacles, which is solved by modernizing the management using enavigation. Intensification of the movement process is provided by increasing the number and frequency of observations according to static criteria. In this case, the methods of graphical and analytical calculation of the path are the basis of navigation, forcing a return to the local criterion, which reflects the full physical nature of the process. The calculation of the vessel's path on the route is carried out according to the rule of the polygon, the sides of which are the vectors of the speed of the path, the vessel and perturbations (wind, waves, current). The main problem is the accuracy of determining the magnitude of the perturbation vector. The inaccuracy of the definition leads to the extension of the vessel's path, which contributes to energy and financial losses for transport support and maintenance of the vessel. The aim of the study is to create a reliable, fast and accurate (innovative) way to determine the characteristics of rectilinear gradual uniform motion of the vessel, which features three speed vectors: perturbation, relative and absolute velocities. The object of study was the process of ship movement, and the subject - the elements (parameters) of movement. The article determines the forecast parameters with a minimum of a priori information at the beginning of the vessel: the sequence of determining the angles of the speed triangle is determined, the sides (modules) of the speed triangle are determined, the order of determining the coordinates of the vertices of the velocity triangle is established. This allows to solve more complex problems of graph-analytical and mechatronic calculus and observation of translational and rotational motion of the vessel along the route and to improve control to reduce risk on the course of disturbances in "big" real time, with variable intervals of observations, approaching invariant and robust control. The advantage of the coordinate method is to solve the problem of determining the parameters of vectors by methods of analytical geometry more accurate, proven and simple in comparison with empirical dependencies, as well as geometric constructions

Concept of LIF Neuron Circuit for Rate Coding in Spike Neural Networks

The study presents an oscillator circuit for a spike neural network with the possibility of firing rate coding and sigmoid-like activation function. The circuit contains a switching element with an S-shaped current-voltage characteristic and two capacitors; one of the capacitors is shunted by a control resistor. The circuit is characterised by a strong dependence of the frequency of relaxation oscillations on the magnitude of the control resistor. The dependence has a sigmoid-like form and we present an analytical method for dependence calculation. Finally, we describe the concept of the spike neural network architecture with firing rate coding based on the presented circuit for creating neuromorphic devices and artificial intelligence.

Study on analytical calculation method of water inflow in the tunnel of oblique crossing layered aquifer structure

Due to the complicated geological environment and karst hydrogeological conditions, water-inrush accidents often occur in the construction of tunnels in southwestern China. At present, there are many methods to predict tunnel water inflow, including analytic method and conventional hydrodynamic research method. There is a big discrepancy between calculated water inflow value and actual situation. Our research focused on the layered aquifer medium characteristics of water-bearing structure and movement characteristics. On the basis of existing tunnel gushing water inrush characteristics, the crossing relationships between tunnel and layered aquifer structure are divided into three categories, (I) tunnel longitudinal through layered aquifer structure, (II) tunnel through layered aquifer structure, and (III) tunnel obliquely crossing the layered aquifer structure. The revised formula of tunnel water inflow theory and experience in this study is inferred from steady-flow formula considering the boundary conditions. Inhomogeneous layered aquifer structure is considered as homogeneous structure, calculated by theory and experience formula. Next to the heterogeneity on one side of heterogeneity interface, the permeability coefficient of different strata can be fitted for a unified Kv; when crossing the layered water-bearing structure laterally, it is still calculated according to the original formula. When oblique crossing a layered water-bearing structure, the total flow rate is decomposed into two directions: transverse crossing and longitudinal crossing. The flow rates in the two directions are calculated respectively, and then superposed into the flow rates in oblique crossing.

Wave optical simulation of retinal images in laser safety evaluations.

Lasers with wavelengths in the visible and near infrared region, pose a potential hazard to vision as the radiation can be focused on the retina. The laser safety standard IEC 60825-1:2014 provides limits and evaluation methods to perform a classification for such systems. An important parameter is the retinal spot size which is described by the angular subtense of the apparent source. In laser safety evaluations, the radiation is often described as a Gaussian beam and the image on the retina is calculated using the wave optical propagation through a thin lens. For coherent radiation, this method can be insufficient as the diffraction effects of the pupil aperture influence the retinal image. In this publication, we analyze these effects and propose a general analytical calculation method for the angular subtense. The proposed formula is validated for collimated and divergent Gaussian beams.

Analytical Calculation of Active Magnetic Bearing Based on Distributed Magnetic Circuit Method

To solve the problem that coupled magnetic flux and saturation of active magnetic bearing (AMB) cannot be taken into account in the traditional magnetic circuit calculation method together, this paper proposes a novel analytical calculation method based on distributed magnetic circuit method (DMCM). First, a magnetic circuit model with multiple magnetic circuits is built, we can obtain the initial flux density of each section by magnetic circuit calculation. Next, the magnetomotive force (MMF) of each magnetic circuit is calculated by the B-H curve of the ferromagnetic material. Then, the air-gap flux density under each magnetic pole center is obtained by further iterative calculations according to the magnetic potential error. On the basis, the flux density distribution along the air-gap circumference is obtained by one-dimensional (1D) relative permeance function, and thus the bearing capacity is derived and a loss calculation method is introduced. Finally, the finite element method (FEM) and experimental results show that the proposed method is feasible and effective.

An Analytical Method for Estimating the Maximum Penetration of DFIG Considering Frequency Stability

With the increasing wind power in power systems and the wide application of frequency regulation technology, the accurate calculation of the limit wind power capacity in systems is critical to ensure the stability of the frequency and guide the planning of wind power sources. This paper proposes an analytical method for calculating the maximum wind generation penetration under the constraints of frequency regulation control and frequency stability taking doubly fed induction generator as an example. Firstly, the frequency-domain dynamic model of the doubly fed induction generator is established considering the supplementary frequency proportion-differentiation control under small disturbance. The equivalent inertia time constant of the doubly fed induction generator is calculated. On this basis, the frequency response model of the power system with the consideration of wind power integration in frequency regulation control is constructed. Then, the frequency-domain analytical solution of the system frequency is obtained. Finally, with the constraint by the steady-state deviation and dynamic change rate of the system frequency, the maximum wind generation penetration is analytically solved. The accuracy of the proposed analytical calculation method for the limit value of the percentage of wind power is verified by MATLAB/Simulink.

Mutual Inductance in Magnetic Resonance Two-Element Phased-Array Square Coils with Strip and Wire Conductors

Phased-array coils are extensively employed in Magnetic Resonance (MR) as transmitter and receiver radiofrequency (RF) coils due to their large field-of-view (FOV) and their high signal-to-noise ratio (SNR). Array elements have to be geometrically decoupled for mutual coupling minimization, to achieve coil performance maximization. This paper proposes an analytical method for the mutual inductance calculation between two square loops constituting a 2-element phased-array coil in dependence on the conductor cross-sectional geometry (flat strip and circular wire). Simulation accuracy was evaluated with workbench experimental measurements performed at 21 MHz frequency on two home-built array square coils.

Structural silicone joint behaviour study for cold bent glass

Cold-bent or warped glass units in facades has gained in popularity as architecture in commercial buildings is showing a trend to innovative, non-rectangular “organic” shapes. Structural silicone glazing has been used successfully as the sole method of retention of the bending membrane. Recent research by the authors investigated experimentally the durability of different cold bent glass designs by coupling the loading level to the rate of deformation over time and recommend for single corner warped glass tolerable peak strains to reach a good durability. The goal of the current paper is to propose adapted evaluation methods from the early design stage to the final concept. The first part of the paper is a thorough investigation of the difficulties observed when applying FEA to the evaluation of structurally glazed cold bent glass. Building further on the recently done investigation, the effect of the mesh size, the choice of constraints, the type of bending (single corner or other) and the design of the frame or interlayer are discussed. Additionally, an additional failure criteria was evaluated to the maximum principal strain to verify whether they can predict failure as observed experimentally. The second part of the paper derives an alternative simplified analytical calculation method to assess the potential of different concepts in the early design stages for twisted glass. The effect of the interlayer is addressed as well as the effect of the IGU compound. The accuracy of the analytical results are compared to FEA models.

Analytical and FE Determination of the Change of Single Stiffness for Cylindrical Gears with External Involute Teeth

The calculation of mesh stiffness with required accuracy is essential for determining the contact characteristics of gear pairs. The easiest approximation of the relative stiffness for the basic profile geometries is the so-called single stiffness. Standardized and analytical methods for the determination of the single and mesh stiffness of gears are used to achieve design goals considering the load capacity and the vibration excitation characteristics. Such methods involve the formulas of ISO 6336-1:2006 based on experimental relationships and the equations of Weber and Banaschek based on mechanical calculations. In this paper, guidelines are given to refine the analytical calculations. Our goal is to present the impact of the change of the applied pressure angle, module, load, rim thickness and tooth number on the maximal single stiffness. The profile geometry of the gears is generated with our program in MATLAB. The profile of gears is calculated by the tool geometry and the kinematics of production. The geometry is imported into Abaqus. The sensitivity of the models to different parameters is examined and compared to those obtained by analytical calculations. The benchmarks for the single stiffness are the two most widely used analytical calculation methods in Europe such as ISO 6336-1:2006 formulas and Weber and Banaschek equations.

Intelligent control system for minced meat production

This article presents the theoretical aspects of developing a control system for the processing of frozen raw meat by cutters in automatic mode. The method for analytical calculation of the productivity rate of meat cutting by a cutter with a screw tooth provides an accuracy for which relative error does not exceed 6%. The authors show automatic process control in minced meat production using a control system computer (CSC), with the aim of building an automatic control system (ACS) for chopping raw materials frozen in the form of blocks. The task of ACS synthesis was solved: the system structure and its elements were chosen, the topology of their cause-and-effect relationships and an algorithm of control devices were developed, and their parameters were determined. The ACS’s control loop scheme for raw material cutting speed was realized, where an assembly of devices was chosen as the object of management (OM): the squirrel cage induction motor (SCIM) of the cutting mechanism drive; the frequency converter (FC) of the supply voltage, which changes the rotation speed of the SCIM (the rotation speed of the milling cutter); and the milling cutter of the chopper. The shaping filter method was used, to predict the size of the meat chips produced, to modulate the perturbation acting on the system from the load side. Based on the single-stage chopping of raw meat, an automatic line is created for producing meat products, with a minced meat quality management system based on artificial intelligence on the principle of ‘unmanned technology’.

SYNCHRONOUS MOTOR WITH INCREASED ROTOR SPEED

Development of the design of a synchronous electric motor with six C-shaped stator teeth, the rotor axis of rotation of which is displaced relative to the axis of rotation of the output shaft. The rotational speed of the output shaft is equal to twice the rotational speed of the stator magnetic flux. Determination of the phase shifts of the supply voltages in time and the spatial position of the stator windings. Visualization of the principle of operation of the electric motor under consideration, namely, step-by-step observation of the position of the rotor in space, when the sinusoidal voltage wave changes by an angle equal to π, with a step of π/6. Mathematical description of the engine under consideration, with all the structural features of the stator-rotor magnetic circuit. In the course of the work, analytical calculation methods were applied. As a result of the study, the basic laws of operation were determined, as well as the design and principle of operation of the considered electric motor with a suspended rotation speed.

Calculation of groundwater head distribution with a close barrier during excavation dewatering in confined aquifer

When pumping is conducted in confined aquifer inside excavation pit (waterproof curtain), the direction of the groundwater seepage outside the excavation changes from horizontal to vertical owing to the existence of the curtain barrier. There is no analytical calculation method for the groundwater head distribution induced by dewatering inside excavation. This paper first analyses the mechanism of the blocking effects from a close barrier in confined aquifer. Then, a simple equation based on analytical solution is proposed to calculate groundwater heads inside and outside of the excavation pit with waterproof curtain (hereafter refer to close barrier) in a confined aquifer. The distribution of groundwater head is derived according to two conditions: (i) pumping with a constant water head, and (ii) pumping with a constant flow rate. The proposed calculation equation is verified by both numerical simulation and experimental results. The comparisons demonstrate that the proposed model can be applied in engineering practice of excavation.