Definition Formula Research Articles

An effective simulation scheme for the prediction of aerodynamic environment under hypersonic conditions characterized by NACA0012

Currently, aerodynamic environment prediction research into scramjet-propelled vehicles characterized by NACA0012 under hypersonic conditions is relatively sparse. Two-dimensional external flow field models are established, and then through validation tests, we perform a systematic investigation between simulation parameters and prediction accuracy, and an effective aerodynamic environment prediction simulation scheme under hypersonic conditions is proposed. Unlike under incompressible conditions, the maximum accuracy decline could be attributed to the inappropriate choice of the sharp trailing edge modeling method, but the definition formula is still preferred. In particular, for the two modeling data point sources, Airfoil tools and NACA4, the numerical performance of the latter is better than the former, and the calculation accuracy negatively correlates with the number of data points offered by both of them. Moreover, for the mesh cells near the shock, the cell Reynolds number and aspect ratio values should be no smaller than 16 and not exceed 380, respectively, and the recommended values for the far field distance, the turbulence model and flux type are 16L, Spalart-Allmaras, and ROE flux type. Under hypersonic conditions, the aerodynamic environment characterized by NACA0012 predicts a maximum temperature of approximately 1856.85 °C, with an average temperature change rate of 77 °C/s. Meanwhile, the top sound pressure level and the vibration acceleration could reach up to 145 dB and 182 g, respectively.

Localized density-based K-means UAV communication coverage algorithm for UV collaboration

In response to the problem of UAV-assisted communication, utilizing the characteristics of wireless ultraviolet with strong anti-jamming performance and good confidentiality, providing emergency communication services by covering ground users with UAVs as aerial base stations is crucial. A K-means clustering coverage algorithm based on the local density is proposed, which increases the connectivity term of UAVs on the basis of minimizing the squared error; secondly, the definition formula of the local density is proposed, and a heuristic decision function is used to determine the selection of the initial cluster center. The simulation results show that the initial coverage of the initial cluster center selected by the heuristic function is increased by 31.6%. Compared to the standard K-means algorithm and FSFDP algorithm, the coverage rate of the proposed algorithm in this paper is improved by 7.2% and 4.3%, respectively.

A probabilistic proof of some integral formulas involving incomplete gamma functions

The theory of normal variance mixture distributions is used to provide elementary derivations of closed-form expressions for the definite integrals ∫ 0 ∞ x − 2 ν cos ⁡ ( b x ) γ ( ν , α x 2 ) d x (for ν > 1 / 2 , b > 0, α > 0) and ∫ 0 ∞ x 2 ν − 1 cos ⁡ ( b x ) Γ ( − ν , α x 2 ) d x (for ν > 0, b > 0, α > 0), where γ(a, x) and Γ(a, x) are the lower and upper incomplete gamma functions, respectively. The method of proof is of independent interest and could be used to derive further new definite integral formulas.

Non-contact air-coupled transducers Lamb wave signal multipath effect and blind separation for different modes using PZT as receiver

Due to the complexity and faintness of the detection wave patterns obtained by air-coupled transducers, if it is possible to effectively separate the various modes and obtain non-dispersive signals for more accurate detection and positioning, it will help to improve the accuracy and reliability of air-coupled ultrasonic Lamb wave detection, providing better technical support for the application and development of related fields. Because of the increased complexity of air-coupled signals, there is no definite theoretical formula to describe the mode changes of air-coupled signals, so the method based on blind separation has unique value. To address these challenges, the paper proposes a single-channel blind source separation (SCBSS) method. The effectiveness of this method is evaluated through simulations and experiments, demonstrating favorable separation results and efficient computational speed. This work first conducts an in-depth analysis of the signal characteristics of air-coupled ultrasonic non-destructive testing, and simulates the ultrasonic excitation conditions of air-coupled sensors through finite element software. The study of modal changes and multipath effects caused by the variation of the incidence angle of the ACT signal is carried out, and the situation of the Lamb wave signal excited by ACT at the receiving end is analyzed. By combining ACT with PZT signals, the ultrasonic signals of air-coupled Lamb waves are compared and studied, and their modal purification is carried out.

Exploring Explicit Definite Integral Formulae with Trigonometric and Hyperbolic Functions

Making use of integration by parts and variable replacement methods, we derive some interesting explicit definite integral formulae involving trigonometric or hyperbolic functions, whose results are expressed in terms of Catalan’s constant, Dirichlet’s beta function, and Riemann’s zeta function, as well as π in the denominator.

E-comic as a media to build an understanding of newtons concepts

This research aims to create effective physics e-comic learning media to help students understand Newton’s concepts. The Research and Development method was used in conjunction with a 4-D development model that consists of four stages: definition, design, development, and dissemination. At the definition stage, a series of needs analysis was carried out, collecting and analyzing information. After a series of definitions had been formulated, the next step was to design. This stage involved designing the product that would be created in accordance with the previously completed definition formula. After the design stage was completed, the designing stage consisted of two steps, namely expert appraisal (expert assessment), accompanied by revisions and developmental testing (development trials) up to the deployment stage. A limited trial on 27 students of class VIII from SMP Negeri 15 Semarang resulted in an increase of 80% in student learning outcomes in final physics learning with the criteria “very feasible.” Based on limited trials, the e-comic media developed was effective and could be used as a physics learning medium to build understanding of Newtonian material physics concepts. This research could serve as a foundation for several other studies that employed diverse and innovative learning media, such as e-comics, which could have ramifications for readers’ understanding of several concepts related to their cognitive abilities.

Design thinking with constructivist learning increases the learning motivation and wicked problem-solving capability—An empirical research in Taiwan

In the 21st century, one of the cruxes in education is to enhance students’ competencies to solve wicked problems that prepare students to confront misrepresentation, information confusion, value conflicts, no definite formula, and intertwined issues. Design thinking is a student-centered approach to interacting with students and teachers in a constructivist learning environment. That transforms students’ learning process to link up real-world experiences, problem-solving foundations, and multiple reflections and reconstructions. Design thinking allows students to face ambiguous and unsuccessful situations comfortably by implementing the five steps progressively to test solutions or prototypes for solving wicked problems. Previous research has focused on how learning motivation can be enhanced with constructivist learning, and critical thinking and problem-solving skills can be improved via the design thinking approach. However, there needs to be an in-depth theoretical discussion of the rationale for enhancing learning motivation or wicked problem-solving capabilities. Therefore, self-determination theory and wicked problem-solving theory are applied to explain profoundly that design thinking can increase students’ learning motivation and wicked problem-solving capabilities. The empirical results support the hypotheses. This study contributes to the theoretical extension and empirical verification of the literature on constructivist learning, design thinking, and problem-solving capability.

Definite Formulae, Negation-as-Failure, and the Base-Extension Semantics of Intuitionistic Propositional Logic

Proof-theoretic semantics (P-tS) is the paradigm of semantics in which meaning in logic is based on proof (as opposed to truth). A particular instance of P-tS for intuitionistic propositional logic (IPL) is its base-extension semantics (B-eS). This semantics is given by a relation called support, explaining the meaning of the logical constants, which is parameterized by systems of rules called bases that provide the semantics of atomic propositions. In this paper, we interpret bases as collections of definite formulae and use the operational view of them as provided by uniform proof-search—the proof-theoretic foundation of logic programming (LP)—to establish the completeness of IPL for the B-eS. This perspective allows negation, a subtle issue in P-tS, to be understood in terms of the negation-as-failure protocol in LP. Specifically, while the denial of a proposition is traditionally understood as the assertion of its negation, in B-eS we may understand the denial of a proposition as the failure to find a proof of it. In this way, assertion and denial are both prime concepts in P-tS.

The Importance of Digitization in Estimating Housing Fair Value with the Artificial Neural Networks Method: The Case of Yenimahalle/Ankara/Turkey

With the rapid development in the construction sector in recent years, housing sales, which is one of the economic investments, have accelerated, making an objective valuation difficult and making it impossible to predict the real price due to the fact that there are too many parameters in the valuation stage and there is no definite formula. In addition, in real estate appraisal processes, the use of artificial neural networks (ANN), which is one of the artificial intelligence methods, has made it attractive to perform and adapt machine learning using examples, to provide information about unprecedented examples, to work fast and easy to identify, to provides solutions to complex problems, to work with little information. In this study, ANN models were created by rearranging the quantification values in an existing study by creating ANN models with 14 parameters that are effective in determining the fair value of a total of 220 houses for sale advertised on an e-commerce site in different neighborhoods of Yenimahalle district of Ankara/Turkey, and it was observed that with the use of rearranged quantification values, the ANN architecture selected with mean square error (MSE) 0.000016, regression (R) 95.99% and accuracy rate 91.73% gave more successful results in predicting the house price.

The Horizon Problem in the Big Bag Theory and the Completeness Error Rate as a Solution From the Definitive Formula

The Horizon Problem in the Big Bag Theory and the Completeness Error Rate as a Solution From the Definitive Formula

The Definitive Formula Regarding the Principle of Light and Sound, String Theory and the Multiverse

The Definitive Formula Regarding the Principle of Light and Sound, String Theory and the Multiverse

The Definitive Formula: Wave-Particle Duality and the Principle of Light and Sound in Relation to Proportional Dynamic Equilibrium

The Definitive Formula: Wave-Particle Duality and the Principle of Light and Sound in Relation to Proportional Dynamic Equilibrium

The Definitive Formula the Principle of Light and Sound and the Nature of Light in Relation to Its Behaviour as a Wave and as a Particle

The Definitive Formula the Principle of Light and Sound and the Nature of Light in Relation to Its Behaviour as a Wave and as a Particle

A Total Transmitted Light Intensity Method for Detecting Concentration of Glucose Aqueous Solution Directly Irradiated by Near Infrared LED

Glucose plays an important role in biological fermentation and biosensing. Therefore, it is very important to detect the concentration of glucose aqueous solution quickly and accurately. A novel method for detecting the concentration of glucose solution is introduced in this article. Based on the spectral characteristics of the near-infrared light-emitting diode (NIR LED), the total transmitted light intensity (TTLI)-concentration model of glucose solution directly irradiated by NIR LED was established to detect the concentration of glucose solution. In this model, firstly, the TTLI of glucose solution and TTLI of deionized water were defined. Secondly, the definition formula of the change ratio of TTLI was provided. Finally, the linear relationship between the change ratio of TTLI and the concentration of glucose solution was derived. In order to verify the effectiveness of the TTLI method, NIR LED Glucose Solution Concentration Detection System (NIR LED-GSCDS) was designed. In this system, an alternating measurement method is designed to reduce the influence of the radiation fluctuation of the NIR LED light source on the accuracy of detection results, and the thermostatic circulation subsystem is designed to reduce the influence of the change of solution temperature on the infrared light absorption rate of glucose solution. The experimental results show that the linear correlation coefficient between the change rate of TTLI and glucose solution concentration is 0.998 and the relative uncertainty is 8.2% in the concentration range of 1000–5000 mg/dL. Therefore, the TTLI method can determine the concentration of glucose solution under the direct irradiation of the NIR LED light source without a complex spectroscopic system.

Reconstructing a single-head formula to facilitate logical forgetting

Abstract Logical forgetting is removing some variables from a formula while maintaining its consequences on the remaining variables. This removal may require exponential time on arbitrary propositional Horn formulae, but it only takes polynomial time on single-head propositional definite Horn formulae. Single-head means that no variable is the head of multiple clauses. An algorithm to make a formula single-head if possible is shown. It enlarges the set of formulae admitting polynomial-time forgetting by making them single-head if possible and then running the usual algorithm for forgetting.

THE FORMULA OF AGATHA CHRISTIE’S DETECTIVE STORY THE THIRD-FLOOR FLAT

Abstract
 This research aims to explain the detective formula as portrayed in Agatha Christie’s The Third-Floor Flat short story and the techniques that are employed to maintain the suspense by using Cawelti’s formula theory. Cawelti explains there are four aspects of the classic detective’s formula: situation, the pattern of action, character and their relation, and setting. This research is descriptive qualitative research. The formulas of detective stories exist in The Third-Floor Flat. The plot goes straight on the definite formula: the preliminaries, birth of the plot, intentional misleading, the crime, grouping for the murderer by the police, friends, relatives, and amateur detective, failure of everybody, detective’s announcement of facts and proof. The author used some techniques such as the whodunit, metaphor, foreshadowing, and fake devices to maintain the suspense.

DETERMINATION OF OPTIMAL DESIGN AND WORKING PARAMETERS OF A VIBRO-PRESS FOR DEHYDRATION OF DAMP DISPERSIVE WASTES OF FOOD INDUSTRY

Vibro-pressing equipment its one from most effective kinds of machines for dehydration of damp dispersive wastes of food industry (alcoholic bard, beer pellets, beet press, coffee and barley slime) for their further using as valuable additives to agricultural fodders or as fuel. In comparison with other equipment for mechanical dehydration (hydraulic, belt and screw presses, centrifuges) vibro-presses with hydraulic pulse, unbalanced or electromagnetic drive provide the same or higher productivity (20 ÷ 25 t / h) and energy efficiency (2,7 ÷ 3,2 kW / t) under lower final humidity of processed wastes (20 ÷ 25% against 70 – 76% - in case of realization of other mechanical methods). The last advantage allows do not conduct an additional drying of the wastes and that provides significant decrease of general power consuming of the working process. For provision of high efficiency parameters of the vibro-blowing dehydration there is need to provide optimal values of working and design parameters of the equipment for their realization. There are several approaches for research of the vibro-press equipment. The approaches that realized with help of differential equations of movement of the machine’s executive elements or differential equations of balances their energy provide high accuracy of calculations but because of complexity of these equations they are unsuitable for creation of a method of engineering design calculation of the machines. In the article are proposed algebraic equations and formulas for definition of optimal parameters of the vibro-pressing equipment for dehydration of damp dispersive wastes of food industry for realization of given parameters of efficiency and with consideration of initial and final physical-mechanical characteristics of the processed waste. There are conducted calculated diagrams of these parameters.

ALGORITHM AND SOFTWARE TOOLS FOR IMPROVING INTERPOLATION ACCURACY BASED ON CUBIC SPLINE

In this work, the construction of the cubic spline for the continuous function defined in the segment, as well as the approximation algorithm of the interpolation process and the software for determining the interpolation error were developed. We used cubic splines of the third degree in this work. In the spline definition formula, the value of the coefficient is expressed by the distance between the nodes of the function and the distance between the nodes. The spline-functions method was improved based on the result of analytical analysis to study the methods of approximating functions and functional connections obtained from experience

Influence Analysis of Simulation Parameters on Numerical Prediction of Compressible External Flow Field Based on NACA0012 Airfoil under Hypersonic Speed

Currently, the influence of numerical parameters on the prediction accuracy of the compressible external flow field characterized by a NACA0012 airfoil under hypersonic speed, especially the influence analyses of the trailing edge shape, the modeling methods, and the adopted data points on it are relatively sparse. In this paper, using three modeling approaches and two data point sources, six NACA0012 airfoils are designed including two types of trailing edge shapes. Unlike under the incompressible external flow field, the comparative analysis shows that though the optimal accuracy is obtained by the sharp trailing edge, the improper sharp trailing edge design could result in a greater error ratio than that of the blunt trailing edge. Similarly, the definition formula could provide the best performance, while in other cases, NACA4 is preferred and the selection between them depends on the adopted data point source. Furthermore, the increase in the number of the adopted two types of data points would lead to a decrease in prediction accuracy. According to the comparison among all the optimal total error ratios, the suggested configuration is the sharp trailing edge based on the definition formula adopting 200 points sourced from NACA4 + 16 m far-field distance + SA turbulence model + ROE flux type and the best result is 2.05%.

Extraction of phytochemicals with health benefit from Peperomia pellucida (L.) Kunth through liquid-liquid partitioning

Peperomia pellucida (L.) Kunth has been traditionally used as food and medicine in both Eastern and Western countries. Owing to the vast variety of bioactive compounds, there is no definite extraction system or formula to efficiently extract the bioactive compounds with commercial value. This study aimed to evaluate the bioactive compounds in P. pellucida with liquid-liquid partitioning method and compare their anti-glycaemic, anti-inflammatory, antioxidant, and anti-glycation potential in different solvent fractions. The dried plant powder was macerated with methanol and successively partitioned with five solvents of different polarity. Five classes of bioactive compounds, four categories of biological activities and in vivo toxicity were evaluated with quantitative bioassays. This study found that the plant extraction yield varied with solvent polarity. The chloroform, ethyl acetate and n-butanol plant fractions were rich in phenolics, tannin, saponin and alkaloid despite their low extraction yields. Plant phenolics and saponin were positively correlated (p < 0.01) with antioxidant, anti-inflammatory and anti-glycation activities. The non-polar hexane fraction displayed high anti-inflammatory potential while ethyl acetate, aqueous and hexane fractions showed relatively strong anti-glycation effect. The anti-α-glucosidase and anti-α-amylase activities in all plant fractions except the non-toxic aqueous fraction were stronger than standard acarbose drug. Four main bioactive compounds, including the dillapiole, 2,4,5-trimethoxystyrene, 9-octadecenoic acid methyl ester and pheophorbide-a methyl ester have been characterized through nuclear magnetic resonance and electrospray ionization mass spectrometry. Principal component analysis confirmed that both solvent polarity and plant extraction yield contributed to 63% of biological activity variation in P. pellucida. This study has demonstrated that the liquid-liquid partitioning method could be optimized to extract bioactive compounds from P. pellucida with potent antioxidant, anti-diabetic, anti-inflammatory and anti-glycation activities.