Numerical Coefficients Research Articles

AUTOMATED BRACHIAL-ANKLE VERSUS CAROTID-FEMORAL PULSE WAVE VELOCITY: SYSTEMATIC REVIEW AND META-ANALYSIS

Objective: Carotid femoral pulse wave velocity (cfPWV) is the gold standard for measuring large artery stiffness. Automated brachial ankle pulse wave velocity (baPWV) is an alternative observer-independent method for assessing arterial stiffness at the level of both large (elastic) and small (muscular) arteries. Design and method: A systematic review and meta-analysis of PubMed and EMBASE studies was performed aiming to compare cfPWV and baPWV in terms of (i) absolute numerical difference, (ii) correlation coefficient and (iii) correlations with target organ damage (TOD). Results: Among 486 retrieved studies 44 were analyzed (n = 32.064, weighted age 59.4 ± 11.6 years, 48% hypertensives). Meta-analysis of 41 studies (n = 23.145, weighted age [SD] 60.2 ± 13.6 years, pooled cfPWV 9.4 [95% CI 8.8, 10.1] m/s) showed pooled baPWV-cfPWV difference at 4.6 m/s (95% CI 3.1, 6.1). There was considerable heterogeneity among the studies (I2 = 100%). Meta-analysis of 21 studies (n = 16.429) showed pooled correlation coefficient between baPWV and cfPWV at 0.67 (0.60, 0.74). Sensitivity analyses based on the technology used for cfPWV assessment showed baPWV minus cfPWV difference at (i) 6.5 (5.6, 7.5) m/s with the SphygmoCor (10 studies), and (ii) 3.8 (1.9, 5.6) m/s with the Omron VP1000/2000 Vascular Profiler (26 studies). Analysis of 16 high quality studies (n = 5.877) showed baPWV-cfPWV difference at 3.8 (2.9, 4.7) m/s. Three studies (n = 2,003) compared the correlation of left ventricular mass index with cfPWV (pooled r = 0.16, 95% CI 0.09, 0.23) vs. baPWV (r = 0.21, 95% CI 0.07, 0.35) (p < 0.05 for comparison). Conclusions: The current evidence indicates that baPWV gives higher values than cfPWV, which is probably due to the fact that these two indices assess the stiffness at different parts of the arterial tree. The two methods appear to be closely correlated and are associated with left ventricular mass.

A beam–ring circular truss antenna restrained by means of the negative speed feedback procedure

The present article contemplates the nonlinear powerful exhibitions of affecting dynamic vibration controller over a beam–ring structure for demonstrating the circular truss antenna exposed to mixed excitations. The dynamic controller comprises the included negative speed input added to the framework’s idea. By using the statue, Hamilton, the nonlinear fractional differential administering conditions of movement and the limit conditions have inferred for the shaft ring structure. Through Galerkin’s method, the nonlinear partial differential equations referred to overseeing the movement of the shaft ring structure have diminished to a coupled normal differential equations extending the nonlinearities square terms. Multiple time scales have helped in acquiring (getting) the four-dimensional averaged equations for measuring the primary and 1:2 internal resonances. This article’s controlled assessment is useful for controlling the nonlinear vibrations of the considered framework. Likewise, the controller dispenses with the framework’s oscillations in a brief time frame. The demonstrations of the numerous coefficients and the framework directed at the examined resonance case have been determined. Using MATLAB 7.0 programs has aided in completing the simulation results. At last, the numerical outcomes displayed an admirable concurrence with the methodical ones. A comparison with recently available articles has also indicated good results through using the presented controller.

Numerical and experimental studies of the hypersonic flow around a cube at incidence

In order to improve predictions of the on-ground casualty risk associated with the uncontrolled atmospheric re-entry of satellites from Low Earth Orbit, there is significant research interest in the development of engineering models of hypersonic heating rates to faceted shapes. A key part of developing such models is generating accurate datasets of the heat fluxes experienced by faceted shapes at various orientations in hypersonic flows. In this work, we use wind tunnel experiments and CFD simulations to study the hypersonic flow around a cuboid geometry at 5° incidence in a Mach 5 flow at Reynolds numbers of 79.5×103, 109×103 and 148×103. The wind tunnel data are obtained in the University of Manchester's High SuperSonic Tunnel and consist of schlieren images and temperature histories collected using infrared thermography. These temperature histories are used to calculate experimental heat fluxes by solving a three-dimensional inverse heat conduction problem. CFD simulations around the same geometry at equivalent free-stream conditions are calculated with the DLR-TAU code. The experimental and CFD results show good agreement both in terms of heat fluxes as well as flow structure. Notable flow structures include wedge-shaped regions of high heat flux which emanate from the windward corners of the cube. Analysis of numerical Q-criterion contours show that these high heat flux regions are caused by vortex structures generated by the expansion at the cube corner. Analysis of the numerical skin friction coefficient shows that even at incidence there is no breakaway separation from the expansion edges of the cube and the flow remains attached throughout. We show that although there is little change in the average heat flux experienced by a cube at 5° incidence to the free-stream compared to one at 0° incidence, there are significant changes in the heat flux contours over the cubes at these two incidences. Finally, we calculate a number of heating shape factors which can easily be implemented in satellite re-entry and demise prediction analysis tools.

A reduced order model based on machine learning for numerical analysis: An application to geomechanics

Numerical methods are very important in geotechnical and geological engineering. This study presents a reduced-order numerical model to approximate the displacement and stress field in geotechnical and geological engineering contexts by combining numerical methods, proper orthogonal decomposition (POD), and multi-output support vector machine (MSVM). Snapshots were generated using Latin hypercube sampling. POD was used to compute POD-based vectors and their coefficients. Training samples were constructed from the numerical model and POD coefficients input. The MSVM algorithm was adopted to present the relationship based on these training samples. A reduced-order model was developed by predicting the POD coefficients using MSVM, and the displacement and stress field was then predicted based on the POD vectors and predicted POD coefficients. The proposed method was verified and demonstrated for a circular tunnel. The results show the displacement and stress fields are in excellent agreement with the analytical solution and with the numerical solution, and the predicted deformations are consistent with rock mechanics theory. The proposed method predicts the deformation and mechanical behavior of geomaterials well and may be used to replace numerical models for back analysis, for optimal design, and for uncertainty analysis in geotechnical and geological engineering, all of which involve repeated computation.

Third order positivity-preserving direct discontinuous Galerkin method with interface correction for chemotaxis Keller-Segel equations

In this article, we apply direct discontinuous Galerkin method with interface correction (DDGIC) to solve chemotaxis Keller-Segel equation and prove the quadratic polynomial solution satisfying positivity-preserving with third order of accuracy. We show DDGIC method can obtain optimal convergence order for the cell density variable without introducing extra auxiliary variables to approximate the gradient of the chemical concentration. This is due to the super convergent property of the DDGIC method. We prove that, with the proper choice of the numerical flux coefficients, the cell density approximation can be preserved none negative at all time. Uniform third order of accuracy is maintained with the positivity-preserving limiter applied. For the chemotaxis model with blow up or singular solutions, the DDGIC method can effectively remove negative values approximations and accurately capture the blow up time.

On the greatest distance between two partitions of the finite set

Consider the family Ξ of all possible partitions of a given finite set into disjoint parts. Suppose we have A ∈ Ξ, and there is reason to consider this partition basic from a certain point of view. The greatest value d *(A) of the special cluster metric d(A, B) is found, which is reached when its second argument runs through all B ∈ Ξ. The value of d *(A) turns out to depend on the structure of the basic partition A. Using the found value of d *(A), we propose a numerical coefficient whose value allows us to estimate the degree of difference between the basic partition and the newly built one. Such an assessment can help us to make a decision about the possibility of using the new partition instead of the basic one.

Color appearance model incorporating contrast adaptation - implications for individual differences in color vision.

Color appearance models use standard color matching functions to derive colorimetric information from spectral radiometric measurements of a visual environment, and they process that information to predict color perceptual attributes such as hue, chroma and lightness. That processing is usually done by equations with fixed numerical coefficients that were predetermined to yield optimal agreement for a given standard observer. Here we address the well-known fact that, among color-normal observers, there are significant differences of color matching functions. These cause disagreements between individuals as to whether certain colors match, an important effect that is often called observer metamerism. Yet how these individual sensitivity differences translate into differences in perceptual metrics is not fully addressed by many appearance models. It might seem that appearance could be predicted by substituting an individual's color matching functions into an otherwise-unchanged color appearance model, but this is problematic because the model's coefficients were not optimized for the new observer. Here we explore a solution guided by the idea that processes of adaptation in the visual system tend to compensate color perception for differences in cone responses and consequent color matching functions. For this purpose, we developed a simple color appearance model that uses only a few numerical coefficients, yet accurately predicts the perceptual attributes of Munsell samples under a selected standard lighting condition. We then added a feedback loop to automatically adjust the model coefficients, in response to switching between cone fundamentals simulating different observers and color matching functions. This adjustment is intended to model long term contrast adaptation in the vision system by maintaining average overall color contrast levels. Incorporating this adaptation principle into color appearance models could allow better assessments of displays and illumination systems, to help improve color appearances for most observers.

Effects of struts profiles and skewed angles on the aerodynamic performance of gas turbine exhaust diffuser

The strut structure directly affects the flow field characteristics and aerodynamic performance of the gas turbine exhaust diffuser. The effects of the strut profiles and strut skewed angles on the aerodynamic performance of the exhaust diffuser at different inlet pre-swirls were numerically investigated using three-dimensional Reynolds-Averaged Navier-Stokes(RANS) and Realizable k-ε turbulence model. The numerical static pressure recovery coefficient of the exhaust diffuser is in agreement with the experimental data well. The reliability of the numerical method for the exhaust diffuser performance analysis was demonstrated. Exhaust diffusers with four kinds of vertical strut profiles obtain the highest static pressure recovery coefficient at the inlet pre-swirl of 0.35. The similar static pressure recovery coefficient of exhaust diffusers with four kinds of vertical strut airfoils are observed when the inlet pre-swirl is less than 0.48. The static pressure recovery coefficient of exhaust diffusers with vertical b1 and b2 struts are higher than that with the a1 and a2 struts when the inlet pre-swirl is greater than 0.48. At the inlet pre-swirl of 0.35, The static pressure recovery coefficient of the exhaust diffuser with the a1 strut decreases with the increasing of the strut skewed angles. The static pressure recovery coefficient of the exhaust diffuser with the b1 strut increases with the increasing of the strut skewed angles, and the static pressure recovery coefficient increases by 3.6% compared with the vertical design when the skewed angle of b1 strut is 40[Formula: see text]. At the inlet pre-swirl of 0.64. The static pressure recovery coefficient of the exhaust diffuser with the a1 strut increases by 8.7% compared with the vertical design when the skewed angle of a1 strut is greater than 20°. In addition, the static pressure recovery coefficient of the exhaust diffuser with the b1 strut decreases by 3.8% compared with the vertical design when the skewed angle of b1 strut is 40°. The method to improve the aerodynamic performance of the exhaust diffuser by appropriate increase the strut maximum thickness and design the strut skewed angle is proposed in this work.

CFA BASED UNIVERSAL BIQUAD FILTER

This paper is a review of the organizational structure and challenges that a technological enterprise faces during scaling, from the perspective of the engineering management. After expanding operations internationally, the distributed engineering teams developing hardware and software for internet of things applications, face issues regarding culture, communication, leadership, project planning and management. Relevant literature addressing these issues is presented. We elaborate on already implemented measures for improving the overall efficiency and propose further processes introduced in recent literature that can be beneficial for further optimizing the new product development. Potential knock-on effects by such implementation are also discussed. A universal biquad filter using current feedback amplifiers (CFA) as active devices and a canonical number of capacitors is presented. It realizes the classical feedforward structure through the use of grounded capacitors and MOS transistors, which permit a full integrability. The proposed circuit has attractive characteristics, as the possibility to electronically control the transfer function coefficients and the possibility to be directly inserted within cascaded configurations. The theoretical analysis of the circuit is followed by some PSPICE simulation results in agreement with the theoretical findings. In this paper a universal fully integrable biquad using CFAs as active devices and a canonical number of capacitors is presented. It realizes the classical feedforward structure [3] through the use of grounded capacitors and MOS transistors. The presence of grounded capacitors makes the proposed circuit absorb shunt parasitic capacitances. All the possible kinds of responses can be realized, while in the biquad reported in [2] only the low-pass and band-pass responses can be obtained. The numerator and denominator coefficients of the voltage transfer function of the proposed biquad can be electronically controlled by acting on the gate voltages of the MOS transistors of the circuit. Moreover the presented structure has a low-impedance output and then it can be cascaded without additional buffers.

NATALITY IN THE GREEK COMMUNITY OF ODESSA IN THE LATE NINETEENTH CENTURY: PROSPECTS FOR HISTORICAL AND ANTHROPOLOGICAL RECONSTRUCTIONS

NATALITY IN THE GREEK COMMUNITY OF ODESSA IN THE LATE NINETEENTH CENTURY: PROSPECTS FOR HISTORICAL AND ANTHROPOLOGICAL RECONSTRUCTIONS

Air variability in maxillary sinus during radiotherapy for sinonasal carcinoma

IntroductionThe aim was to characterise patterns and predictability of aeration changes in the ipsilateral maxillary sinus during intensity-modulated radiotherapy (IMRT) for sinonasal cancer (SNC), and in a sample evaluate the dosimetric effects of aeration changes for both photon and proton therapy. Materials and methodsThe study included patients treated withIMRT for SNC in a single institution in 2009–2017. The volume of air in the ipsilateral maxillary sinus was recorded in1578 daily cone beam computer tomography (CBCT) from 53 patients.Patterns of changing air volumes were categorised as ‘stable’,increasing’, ‘decreasing’, or ‘erratic’. For the prediction analysis, categorisation was performed based both on the entire treatment course and the first five fractions (F1–5).Photon and proton therapy plans were generated for four patients, the one from each category with the largest aeration variation. Synthetic CT images were generated for each CBCT and all plans were recalculated on the daily synthetic CTs. ResultsThe absolute volume of air varied considerably during the treatment course, ranging from 0 to 25.9 cm3. Changes within a single participant varied in the range of 0–18.7 cm3. In the categorisation of patterns, most patients hadincreasingaeration of the sinus. Generally, patterns of aeration could not be predicted from F1–5. Patients categorised asincreasingin F1–5 had the best prediction, with 78% predicted correctly as increasing for the entire treatment course. The numeric correlation coefficients for target coverage and air volumewere low for 3/4scenarios(photons 0.03–0.23, protons 0.26–0.48). No straightforward correlation between the dosimetric effect and the volume changes could be detected in the sample test of four patients for neither photon nor proton therapy. ConclusionThe variation of aeration was large and unpredictable. No clear dosimetric consequences of the aerationvariation were evident for neither IMRT nor proton therapyfor the patients investigated.

RISK MEASUREMENT AND EVALUATION IN RFI AND RFP PROCESSES AT BULGARIAN MOBILE NETWORK OPERATORS

The present paper regards some possible approaches for measurement and evaluation of the risk in the “Request for Information” (RFI) and “Request for Proposal” (RFP) processes in the supply chain of Bulgarian mobile ntework operators. These approaches include measurement and calculations of the risk based on the use of risk calculation equation and questionnaire surveys and follow-up score cards. The risk calculation equation proposed in the paper assumes that each risk event or risk action “m” can be regarded as a function of the likelihood of occurrence, the consequences, and the imminence in regard to the time horizon for the occurrence of the very same risk event or risk action “m”. Apart from these components, the risk equation employed also considers the space in which the risk occurs and develops, as well as the extent of the actions taken to prevent and mitigate risk at a certain organizational level. The data collected from the questionnaire surveys and score cards are being processed and turned into a specific set of numeric coefficients that represent the contribution and value of the separate risk components. Methods for defining the thresholds for acceptance of the levels of the risks are also suggested. The paper also discusses several more specific problems in the application of risk measurement and evaluation of the RFI and RFP processes in the supply chain of Bulgarian mobile network operators, such as the use of risk evaluation for the point of time when the forecasts of the major indicators of the RFI and RFP processes suggest a major future decline.

A pursuit-evasion differential game with slow pursuers on the edge graph of simplexes. I

We consider the differential game between several pursuing points and one evading point moving along the graph of edges of a simplex when maximal quantities of velocities are given. The normalization of the game in the sense of J. von Neumann including the description of classes of admissible strategies is exposed. In the present part of the paper the qualitative problem for the full graph of three dimensional simplex is solved using the strategy of parallel pursuit for a slower pursuer and some numerical coefficient of a simplex characterizing its proximity to the regular one. Next part will be devoted to higher dimensional cases.

System analysis and processing of parameters of the test bench

The paper deals with the analysis of complex technical objects – test stands of control systems. A method is proposed for evaluating the effectiveness of the test bench based on the parameters obtained using the “standard” and “automated” test stand model. The objective function for calculating the efficiency of test benches based on their parameters and determining the numerical efficiency coefficient of the testing position relative to the typical one is given. The composition of the software for implementing the proposed method is shown.

Enhancing quantum entanglement of the two-mode squeezed vacuum state via multiphoton catalysis

Multiphoton catalysis is a non-Gaussian operation which has aroused interest recently in quantum information processing. There are two schemes of multiphoton catalysis in the current literature: one uses a beam splitter, while the other uses an optical parametric amplifier. We derive the catalysis operator in the Fock basis for each scheme and find a close relationship between them. We propose to enhance quantum entanglement of the two-mode squeezed vacuum state by performing two-mode multiphoton catalysis independently using two beam splitters. We calculate the optimal entanglement, which is maximized over two independent transmissivities, for the catalyzed states with various pairs of catalysis photon numbers, and find that in each case entanglement is enhanced only when the squeezing parameter is below a certain threshold. We also find that the optimal entanglement is nonzero in the limit of low squeezing, and deduce the analytical forms of the limiting catalyzed state and its entanglement in each case from numerical coefficients.

Numerical investigation of effective parameters of falling film evaporation in a vertical‐tube evaporator

AbstractWastewater treatment is one of the most effective solutions to manage the problem of water scarcity. Falling film evaporators are excellent technology in wastewater treatment plants. These wastewater evaporators provide high heat transfer, short residence time in the heating zone, and high‐purity distilled water. In the present study, the mechanism of turbulent falling film evaporation in a vertical tube has been investigated. A model has been developed for symmetrical two‐dimensional pure and saline water flow in a vertical tube under constant wall heat flux. The numerical simulation has been carried out by a commercial computational fluid dynamics code. The evaporation of saturated liquid film is simulated utilizing a two‐phase volume of fluid method and Tanasawa phase‐change model. The main objective of this study is to evaluate the effects of water salinity, liquid Reynolds number, wall heat flux, and liquid film thickness on the two‐phase heat transfer coefficient and vapor volume fraction. The numerical heat transfer coefficients are compared with the obtained results by Chen's empirical correlation. With a MAPE ≤ 11%, this study proves that the numerical method is highly effective at predicting the heat transfer coefficient. Moreover, the empirical coefficient of the Tanasawa model and the minimum thickness of the falling film are determined.

Разработка «Умной теплицы» на основе модели «растение–среда–ситуация–управление»

The greenhouse is a closed-type agroecological system in which energy processes are strictly determined by the technological process of growing plants, taking into account the influence of the environment. As you know, greenhouse models are divided into two types: white box models and black box models. The well-known model of the “Soil-Plant-Atmosphere” system belongs to the first type, built on the physical principles of thermo-, hydro- and gas dynamics. They consist of several complex differential equations that use numerous coefficients and parameters that are known in advance. Such models are cumbersome and require large computational resources and time-consuming. The proposed model of the system “Plant-Environment-Situation-Management” is a practical analogue of the well-known model “Soil-Plant-Atmosphere”. The main difference of this model is that it refers to a black box model, which is an approximation of the observed processes and allows you to describe processes based on experimental data. On the basis of the “Plant-Environment-Situation-Management” model, the software and hardware system “Smart Greenhouse” was developed, which is a human-machine system with a rational separation of the functions of preparation (computer) and decision-making (Man). It allows you to control and control the growth and development of the plant during the growing season, taking into account the influence of environmental conditions. The system is implemented and used in the greenhouse of the al-Farabi Kazakh National University.

STORM SURGE FORECAST MODEL USING GENETIC PROGRAMMING

Stormsurge is a typical genuine fiasco coming from the ocean. Therefore, an accurate forecast of surges is a vital assignment to dodge property misfortunes and decrease the chance of tropical storm surges. Genetic Programming (GP) is an evolution-based model learning technique that can simultaneously find the functional form and the numeric coefficients for the model. Moreover, GP has been widely applied to build models for predictive problems. However, GP has seldom been applied to the problem of storm surge forecasting. In this paper, a new method to use GP for evolving models for storm surge forecasting is proposed. Experimental results on data-sets collected from the Tottori coast of Japan show that GP can become more accurate storm surge forecasting models than other standard machine learning methods. Moreover, GP can automatically select relevant features when evolving storm surge forecasting models, and the models developed by GP are interpretable.

SCORE CARDS FOR EVALUATION OF RFI AND RFP PROCESSES WITHIN ONE OF THE BULGARIAN TELECOMMUNICATION OPERATORS

The present paper regards some the score cards as a possible tool for measurement and evaluation of the risk in the “Request for Information” (RFI) and “Request for Proposal” (RFP) processes in the supply chain at the Bulgarian mobile telecommunication operators. The presented hereby score cards use measurement and calculations of the risk based on the risk calculation equation in which the assumption is that each risk event or risk action “m” can be regarded as function of the likelihood of occurrence, the consequences and the imminence in regards to the time horizon for the occurrence of the very same risk event or risk action “m”. Further to these components, the risk equation in use also takes into account the space in which the risk occurs and itself, as well as the size of the actions for prevention and overcoming of the risks that can appear at a certain organizational level. The data collected for the score cards is being provided by an online survey through the staff dealing with the RFI and RFP processes within the regarded in particular Bulgarian telecommunication operator. The final information from both the survey and the score cards is being processed and turned into a specific set of numeric coefficients that represent the contribution and the value of the separate risk components. Methods for defining the thresholds for acceptance of the levels of the risks are also suggested.

Modified Newton identities

The sums of powers with identical exponents of natural, real, or complex numbers, considered as roots of algebraic equation, are expressed directly through the products of coefficients of that equation, starting from the well-known Newton identities. The final Eq. (6) includes the same power of sum of all numbers ± a sum over all partitions of the exponent. Each term of the last sum is the equation coefficients product with the net power keeping the “dimensionality” of the exponent and having a numerical factor, equal to a proper polynomial coefficient, built of exponents of equation coefficients entering the product. The revers Eq. (43) for equation coefficients is also a sum over all partitions of the same exponent with known numerical coefficients. The entering products are built of “commutators-anticommutators of power of sum and sum of powers” (C-A) of the initial sum addends. The numerous identities Eq. (44) for a C-A with an exponent, exceeding the number of C-A sum terms by 2, and similar C-A-s with lower exponents are established.