Simulating NACA Equations Used in Optimizing Wind Turbine Blade Design: محاكاة معادلات NACA واستخدامها لتحسين تصميم شفرة العنفة الريحية

Aerodynamic scientists are interested in geometry definition and possible geometric shapes that would be useful in design. This paper illustrates a simulation of a NACA four digits airfoil blade profile using MATLAB. As airfoil design became more sophisticated, this basic approach has been modified to include additional variables, and suggestions for the chord line length at the root and at the end of the blade. as well as changes in the twisting angle of the blade and its thickness, this helps to reduce the weight of the blade significantly Simulating NACA equations is very useful in obtaining coordinates of airfoil curvature for the whole series of NACA four digits, which is very effective in optimizing blade design. In order to get an optimal operating performance and high efficiency for the airfoil, the blade surface must be smooth and does not suffer any discontinuities or undefined cases, which cause separation of the boundary layer during the airflow, and get as a result great energy losses. Therefore, the conditions for the continuity of the blade was extracted using mathematical analysis, so the air flow does not suffer any interruptions which reduce the efficiency. This enable us to determine the locations of the maximum thickness of the blade sections on the chord along the blade, in addition to specifying conditions for the chord line length at the root and at the end of the blade which keep the blade curvature continuous and doesn’t have any irregular points, which also facilities writing the necessary programs.

Numerical methods for the detection of phase defect structures in excitable media

Electrical waves that rotate in the heart organize dangerous cardiac arrhythmias. Finding the region around which such rotation occurs is one of the most important practical questions for arrhythmia management. For many years, the main method for finding such regions was so-called phase mapping, in which a continuous phase was assigned to points in the heart based on their excitation status and defining the rotation region as a point of phase singularity. Recent analysis, however, showed that in many rotation regimes there exist phase discontinuities and the region of rotation must be defined not as a point of phase singularity, but as a phase defect line. In this paper we use this novel methodology and perform comparative study of three different phase definitions applied to in-silico data and to experimental data obtained from optical voltage mapping experiments on monolayers of human atrial myocytes. We introduce new phase defect detection algorithms and compare them with those that appeared in literature already. We find that the phase definition is more important than the algorithm to identify sudden spatial phase variations. Sharp phase defect lines can be obtained from a phase derived from local activation times observed during one cycle of arrhythmia. Alternatively, similar quality can be obtained from a reparameterization of the classical phase obtained from observation of a single timeframe of transmembrane potential. We found that the phase defect line length was 35.9(62)mm in the Fenton-Karma model and 4.01(55)mm in cardiac human atrial myocyte monolayers. As local activation times are obtained during standard clinical cardiac mapping, the methods are also suitable to be applied to clinical datasets. All studied methods are publicly available and can be downloaded from an institutional web-server.

Proposal of a Novel Mooring System Using Three-Bifurcated Mooring Lines for Spar-Type Off-Shore Wind Turbines

Floating wind turbine vibration controlling becomes more and more important with the increase in wind turbine size. Thus, a novel three-bifurcated mooring system is proposed for Spar-type floating wind turbines. Compared with the original mooring system using three mooring lines, three-bifurcated sub-mooring-lines are added into the novel mooring system. Specifically, each three-bifurcated sub-mooring-line is first connected to a Spar-type platform using three fairleads, then it is connected to the anchor using the main mooring line. Six fairleads are involved in the proposed mooring system, theoretically resulting in larger overturning and torsional stiffness. For further improvement, a clump mass is attached onto the main mooring lines of the proposed mooring system. The wind turbine surge, pitch, and yaw movements under regular and irregular waves are calculated to quantitatively examine the mooring system performances. A recommended configuration for the proposed mooring system is presented: the three-bifurcated sub-mooring-line and main mooring line lengths should be (0.0166, 0.0111, 0.0166) and 0.9723 times the total mooring line length in the traditional mooring system. The proposed mooring system can at most reduce the wind turbine surge movement 37.15% and 54.5% when under regular and irregular waves, respectively, and can at most reduce the yaw movement 30.1% and 40% when under regular and irregular waves, respectively.

Development of aqueous two-phase systems-based approaches for the selective recovery of metalloproteases and phospholipases A2 toxins from Crotalus molossus nigrescens venom

Snake venoms are rich sources of proteins with potential biotechnological and pharmaceutical applications. Among them, metalloproteases (MPs) and phospholipases A2 (PLA2) are the most abundant. Their isolation involves a multistep chromatographic approach, which has proven to be effective, however implies high operating costs and long processing times. In this study, a cost-effective and simple method based on aqueous two-phase systems (ATPS) was developed to recover MPs and PLA2 from Crotalus molossus nigrescens venom. A system with PEG 400 g mol−1, volume ratio (VR) 1, tie line length (TLL) 25% w/w and pH 7 showed the best performance for PLA2 recovery. In systems with PEG 400 g mol−1, VR 1, TLL 15% w/w, pH 7 and 1 and 3% w/w of NaCl, selective recovery of MP subtype P-III was achieved; whereas, in a system with PEG 400 g mol−1, VR 1, TLL 25% w/w and pH 8.5, MP subtypes P-I and P-III were recovered. Due to their low costs, ethanol–salt systems were also evaluated, however, failed to differentially partition PLA2 and MPs. The use of ATPS could contribute to the simplification and cost reduction of protein isolation processes from snake venoms and other toxin fluids, as well as potentially aid their biochemical, proteomic and biological analyses. Graphic Abstract

Design foundations: Towards a model of style grammar in creative drawing

<p>A style grammar is a principled rule set that governs the organization of very complex ideas. It allows for the examination of underlying structures which are often times obscured. Style grammars have been developed for many fields such as writing, fashion and architecture but to date there is no style grammar for creative drawing. The research identifies the necessary visual features and core traits associated with each feature towards developing such a model for creative drawings. Then operational measures are defined using the computer to extract and measure the core traits of those features towards developing a model of style grammar in drawing. These visual features include line, tone, and depth. Core traits include line length, line width, line expressiveness, local tone, global tone, texture, pattern, outline, shape, and position. A multidimensional scaling (MDS) using input from 27 subjects, 10 art experts and 17 novices, supported the overall list of visual features and added the dimension of smudge to the list. A second MDS sort discusses issues with images and large art categorical sorts from the standpoint of both human perception and machine measures that were obtained using feature extraction. It was concluded from the results of the second MDS that large art categories were too broad to be useful in evaluating measures to develop the model. Further analysis was run using only drawings from three artists, two impressionists to compare similarity and one expressionist for dissimilarity to determine if the machine measures of the core traits of the visual features were able to differentiate smaller groupings of consistent drawing styles. Using the computer allowed for systematic and objective procedures to be used to obtain measures. The multinomial logistic regression showed high significance for all the traits except marginal significance for line length and no significance for depth. Binomial logistic regressions run on each pair of artists showed high significance for all the traits except depth. The combined positive results of the first MDS card sort and the binomial and multinomial regression analysis provide proof of concept and offer strong support towards the development of a model of style grammar for creative drawings. Implications for teaching drawing using the identified visual features and core traits are offered. The outcomes and analysis provided in this research currently support a general practice rule in design reuse and intelligent borrowing that suggests first smudge, then depth, then tone, and then line quality are the most significant elements to use for style comparison. Discussions for future research including improved measures and other types of perception testing are provided towards further development of the model.</p>

Design foundations: Towards a model of style grammar in creative drawing

<p>A style grammar is a principled rule set that governs the organization of very complex ideas. It allows for the examination of underlying structures which are often times obscured. Style grammars have been developed for many fields such as writing, fashion and architecture but to date there is no style grammar for creative drawing. The research identifies the necessary visual features and core traits associated with each feature towards developing such a model for creative drawings. Then operational measures are defined using the computer to extract and measure the core traits of those features towards developing a model of style grammar in drawing. These visual features include line, tone, and depth. Core traits include line length, line width, line expressiveness, local tone, global tone, texture, pattern, outline, shape, and position. A multidimensional scaling (MDS) using input from 27 subjects, 10 art experts and 17 novices, supported the overall list of visual features and added the dimension of smudge to the list. A second MDS sort discusses issues with images and large art categorical sorts from the standpoint of both human perception and machine measures that were obtained using feature extraction. It was concluded from the results of the second MDS that large art categories were too broad to be useful in evaluating measures to develop the model. Further analysis was run using only drawings from three artists, two impressionists to compare similarity and one expressionist for dissimilarity to determine if the machine measures of the core traits of the visual features were able to differentiate smaller groupings of consistent drawing styles. Using the computer allowed for systematic and objective procedures to be used to obtain measures. The multinomial logistic regression showed high significance for all the traits except marginal significance for line length and no significance for depth. Binomial logistic regressions run on each pair of artists showed high significance for all the traits except depth. The combined positive results of the first MDS card sort and the binomial and multinomial regression analysis provide proof of concept and offer strong support towards the development of a model of style grammar for creative drawings. Implications for teaching drawing using the identified visual features and core traits are offered. The outcomes and analysis provided in this research currently support a general practice rule in design reuse and intelligent borrowing that suggests first smudge, then depth, then tone, and then line quality are the most significant elements to use for style comparison. Discussions for future research including improved measures and other types of perception testing are provided towards further development of the model.</p>

Towards high-precision parton distributions from lattice QCD via distillation

We apply the Distillation spatial smearing program to the extraction of the unpolarized isovector valence PDF of the nucleon. The improved volume sampling and control of excited-states afforded by distillation leads to a dramatically improved determination of the requisite Ioffe-time Pseudo-distribution (pITD). The impact of higher-twist effects is subsequently explored by extending the Wilson line length present in our non-local operators to one half the spatial extent of the lattice ensemble considered. The valence PDF is extracted by analyzing both the matched Ioffe-time Distribution (ITD), as well as a direct matching of the pITD to the PDF. Through development of a novel prescription to obtain the PDF from the pITD, we establish a concerning deviation of the pITD from the expected DGLAP evolution of the pseudo-PDF. The presence of DGLAP evolution is observed once more following introduction of a discretization term into the PDF extractions. Observance and correction of this discrepancy further highlights the utility of distillation in such structure studies.

Life of a single bubble growing within an electric field in microgravity: some preliminary results of the Reference mUltiscale Boiling Investigation

The experimental outcomes of single bubbles nucleated and growth from a heated surface immersed in an electric field in high-quality microgravity level are presented. Data were obtained between September 2019 and January 2021 from the European experiment known as Reference mUltiscale Boiling Investigation (also multiscale boiling project), in which single bubbles of FC-72 were nucleated on a heated surface, on-board the International Space Station. In the experiments reported here, an electrostatic field is imposed in the boiling region by a washer-shaped electrode, centred above the nucleation site. The bubbles are heavily distorted by the electric stresses; in particular, contact angles and contact line length increase with electric field intensity. In the appropriate conditions, bubbles are continuously and regularly sucked towards the electrode, because they are attracted to regions of weaker electric field. The significant contribution of electro-convection is highlighted by the bubbles growth rate. These preliminary results contribute to the insight of the basics of boiling and show promising opportunities for practical application of electric fields in space.

EXPRESS: Cross-National Differences in Market Response: Line-Length, Price, and Distribution Elasticities in Fourteen Indo-Pacific Rim Economies

Our field’s knowledge of marketing-mix elasticities is largely restricted to developed countries in the North-Atlantic region, even though other parts of the world—especially the Indo-Pacific Rim region—have become economic powerhouses. To better allocate marketing budgets, firms need to have information about marketing-mix elasticities for countries outside the North-Atlantic region. We use data covering over 1,600 brands from 14 product categories collected in 7 developed and 7 emerging Indo-Pacific Rim countries across more than 10 years to estimate marketing elasticities for line length, price, and distribution, and examine which brand, category, and country factors influence these elasticities. Averaged across brands, categories, and countries, line-length elasticity is .459, price elasticity is -.422, and distribution elasticity is .368, but with substantial variation across brands, categories, and countries. Contrary to what has been suggested, we find no systematic differences in marketing responsiveness between emerging and developed economies. Instead, the key country-level factor driving elasticities is societal stratification, with Hofstede’s measure of power inequality (power distance) as its cultural manifestation and income inequality as its economic manifestation. As the effects of virtually all brand, category, and country factors differ across the three marketing-mix instruments, the field needs new theorizing that is contingent on the marketing-mix instrument studied.