Math Formula Research Articles

An estimation method of wind energy curtailment considering wind generator tripping in frequency adjustment level

Summary Development of wind farms clustering exerts significant influence on secure operation of power grid and also puts forward new requirements for the capacity of peak regulation and frequency adjustment. When power grid frequency is higher than 50.2 Hz, active power output of wind farm should be reduced gradually according to the command from control center of power grid. To study urgent wind power curtailment in frequency adjustment level, math formula of frequency adjusted sensitivity index is deduced, which determines wind generator tripping strategy if the lopsided active power has occurred. Typical frequency adjustment time intervals are selected according to the relationship between frequency overshoot time and load variation as wind power gets curtailed. The annual wind energy curtailment in frequency adjustment level is estimated by selecting the most appropriate wind generator tripping and comparable with wind energy curtailment in peak-load regulation level on the basis of unit commitment model. Based on DIgSILENT/PowerFactory software, the effectiveness and feasibility of the proposed method are verified by taking China's a certain regional power network planning of 2020 as computational examples. Copyright © 2015 John Wiley & Sons, Ltd.

MATEMÁTICA FINANCEIRA E PLANILHAS ELETRÔNICAS: UMA ABORDAGEM COM A INCORPORAÇÃO DE RECURSOS COMPUTACIONAIS

http://dx.doi.org/10.5902/2179460X14623This paper has as its goal to propose a new alternative approach to the progressions and financial math teaching, with the incorporation of technological resources. One of the concepts that used is the study of geometric and arithmetic progressions. In order to study those, an approach based on recurrence relations is proposed. With the goal of stimulating the algebraic manipulation and understanding of the financial math formulas variables, it is proposed the incorporation of the technological resources, in particular, of electronic spreadsheets, in classes about the theme. Through the tool, it is proposed the viability of financial math simulators in the classroom, seeking the diversification of activities.

Modeling and Simulation of Human Reaction in a Multidimensional Social Network

The impacts of information on individuals within a social network are, mostly, statically modeled and the dynamic is not frequently tackled. In addition, the works about modeling and simulation of the populations reactions to the information do not use explicit specification languages to describe their models. These models are specified in the shape of graph or math formulas and then directly implemented and coded using classical programming languages. We propose to model, in the frame of SICOMORES project studying stabilization phase of a conflict, the actions of influence in a multidimensional social networks (MSN). Each graph dimension corresponds to a predetermined social network (Family, religion, neighborhood). The purpose of this work is to provide a simple but efficient and accurate framework to model the behavior of an individual, but also the simulation of the propagation of information among a group of individuals and its influence on their behavior. In more details, we define a set of models of individuals characterized by a set of state variables (e.g. Using Maslow to construct the behavior of an individual) and the mesh between the individuals within a social network. Then, we introduce the platform architecture, sharing resources, specifically designed to simulate MSN. In the end, a scenario is used to validate our models using the platform based on DEVS formalism.

Использование системы осевой сдвижки валков для корректировки межвалкового зазора на толстолистовых станах горячей прокатки

The factors are revealed affecting the thickness deviation of the sheet in the hot rolling process. CVC-roll description was shown, their distinct features and advantages for formation of the final shape of the plate. Known CVC-systems on the modern plate hot mills were considered. The main parameters of the work-roll crown were characterized by math formulas, the optimal shape of the rolls and they advantages to get a required flatness of the final plate was shown. The distribution of the roll gap along the length of the roll body was shown according to the horizontal displacement of the work rolls. The ways to eliminate of the most common thickness defects were shown. The most required directions of research were designated.

The Use of Simple-sample Explanations for Math Education

The Math lessons for students have always been difficult if we speak generally. The students think they memorize the math formulas and just take the exams but no applications at all. Is there any way to teach math in a more compact form. Yes there is, the name of it is simple-sample explanation. In this study we will see the properties and use of simple-sample explanations to some algebraic problems. The students can see many of the properties of a certain formula in one form. This makes the student to remember all the necessary properties without memorizing. This new technique also makes you gain time in the learning process. This helps the teacher to make much more applications. This is what we need as a teacher. This method also develops the learners analytic thinking capabilities.

Analysis of peer learning behaviors using multiple representations in virtual reality and their impacts on geometry problem solving

Learning geometry emphasizes the importance of exploring different representations such as virtual manipulatives, written math formulas, and verbal explanations, which help students build math conc...

Analytical Study on Inherent Properties of a Unidirectional Vibrating Steel Strip Partially Immersed in Fluid

The theory of singuarity functions is introduced to present an analytical approach for the natural properties of a unidirectional vibrating steel strip with two opposite edges simply supported and other two free, partially submerged in fluid and under tension. The velocity potential and Bernoulli's equation are used to describe the fluid pressure acting on the steel strip. The effect of fluid on vibrations of the strip may be equivalent to added mass of the strip. The math formula of added mass can be obtained from kinematic boundary conditions of the strip-fluid interfaces. Singularity functions are adopted to solve problems of the strip with discontinuous characteristics. By applying Laplace transforms, analytical solutions for inherent properties of the vibrating steel strip in contact with fluid are finally acquired. An example is given to illustrate that the proposed method matches the numerical solution using the finite element method (FEM) very closely. The results show that fluid has strong effect on natural frequencies and mode shapes of vibrating steel strips partially dipped into a liquid. The influences such as tension, the submergence depth, the position of strip in the container and the dimension of the container on the dynamic behavior of the strip are also investigated. Moreover, the presented method can also be used to study vertical or angled plates with discontinuous characteristics as well as different types of pressure fields around.

Direct Torque Control of a Bldc Motor Based on Computing Technique

This paper discusses about the speed control technique for brushless DC motors with non-sinusoidal back electromotive force. In order to solve the problems associated with conventional PI speed controller, a new speed control based on o fuzzy inference system is proposed to eliminate overshoot in the torque and speed responses, simplify designing and reduce complexity of math formulas. The effectiveness of proposed system has been validated by simulation results.

Analytical Study on Inherent Properties of a Unidirectional Vibrating Steel Strip Partially Immersed in Fluid

The theory of singuarity functions is introduced to present an analytical approach for the natural properties of a unidirectional vibrating steel strip with two opposite edges simply supported and other two free, partially submerged in fluid and under tension. The velocity potential and Bernoulli's equation are used to describe the fluid pressure acting on the steel strip. The effect of fluid on vibrations of the strip may be equivalent to added mass of the strip. The math formula of added mass can be obtained from kinematic boundary conditions of the strip-fluid interfaces. Singularity functions are adopted to solve problems of the strip with discontinuous characteristics. By applying Laplace transforms, analytical solutions for inherent properties of the vibrating steel strip in contact with fluid are finally acquired. An example is given to illustrate that the proposed method matches the numerical solution using the finite element method (FEM) very closely. The results show that fluid has strong effect on natural frequencies and mode shapes of vibrating steel strips partially dipped into a liquid. The influences such as tension, the submergence depth, the position of strip in the container and the dimension of the container on the dynamic behavior of the strip are also investigated. Moreover, the presented method can also be used to study vertical or angled plates with discontinuous characteristics as well as different types of pressure fields around.

Analysis of peer learning behaviors using multiple representations in virtual reality and their impacts on geometry problem solving

Learning geometry emphasizes the importance of exploring different representations such as virtual manipulatives, written math formulas, and verbal explanations, which help students build math concepts and develop critical thinking. Besides helping individuals construct math knowledge, peer interaction also plays a crucial role in promoting an understanding of mathematics and geometric problem solving. In this research, an Interactive Future Mathematics Classroom (IFMC) based on the Collaborative Virtual Reality Learning Environment (CVRLE) was proposed to facilitate three-dimensional (3-D) geometric problem solving. Two representational tools, the virtual manipulative and a white board, were integrated into the IFMC to help students with the following activities: to synchronously review peers' solving processes; to individually or collaboratively manipulate 3-D objects using the virtual manipulative; and to give comments on peers' white boards for future queries and discussions. One eight-week experiment was conducted and the results showed that the experimental group using the IFMC performed significantly better than the control group on geometric learning achievement. Further analysis showed that the peer learning behaviors of the experimental group in the two kinds of geometric problems, volume and surface area calculation, were different due to the problems' varying difficulty levels. Moreover, various peer learning behaviors with multiple representations lead to different types of strategies for geometric problem solving in the IFMC. Therefore, peer learning behaviors in the IFMC were found useful to facilitate geometric problem solving by sharing ideas and exploring multiple representations. Highlights? Interaction of peers learning behaviors in IFMC facilitates students' geometry problem solving. ? We refine students' strategies for geometry problem solving in the virtual reality. ? Students using IFMC perform better in the post-test of geometry problem solving. ? Students express exploring peers learning with multiple representations is enjoyable and useful for geometry problem solving.

Backtesting: Problems & Solutions

Tools, whether a chainsaw, a backhoe, or a math formula, can be incredibly useful, relevant and powerful if properly used, or destructive, dangerous or ineffective if misused and not respected.In this paper, we explore the many risks in backtesting financial strategies and approaches for managing these risks.

A new constitutive law for the nonlinear normal deformation of rock joints under normal load

In view of the deviation of the fitting results of the classical exponential model and the hyperbolic model (the BB model) from several experiment data during intermediate stress period, a new constitutive model for the nonlinear normal deformation of rock joints under normal monotonous load is established with flexibility-deformation method. First of all, basic laws of the deformation of joints under normal monotonous load are discussed, based on which three basic conditions which the complete constitutive equation for rock joints under normal load should meet are put forward. The analysis of the modified normal constitutive model on stress-deformation curve shows that the general exponential model and the improved hyperbolic model are not complete in math theory. Flexibility-deformation monotone decreasing curve lying between flexibility-deformation curve of the classical exponential model and the BB model is chosen, which meets basic conditions of normal deformation mentioned before, then a new normal deformation constitutive model of rock joints containing three parameters is established. Two main forms of flexibility-deformation curve are analyzed and specific math formulas of the two forms are deduced. Then the range of the parameters in the g-δ model and the g-λ model and the correlative influence factor in geology are preliminarily discussed. Referring to different experiment data, the validating analysis of the g-δ model and the g-λ model shows that the g-λ model can be applied to both the mated joints and unmated joints. Besides, experiment data can be better fit with the g-λ model with respect to the BB model, the classical exponential model and the logarithm model.

Feedback LETTERS TO OPFLOW

The letters in this Feedback department refer to the April 2011 letter that discusses math formulas for various calculations required in the water industry; and, to the April 2011 Question of the Month column, How Do We Deal with Invasive Mussels?

EVM simulation and analysis in digital transmitter

The error vector magnitude (EVM) is extensively applied as a metric for digital transmitter signal quality compliance in modern communication systems. This article is focused on the effects of local oscillator (LO) phase noise and nonlinear distortion of power amplifier on EVM. This article contributes to below aspects. First, the relationships between EVM and two effects, LO phase noise and nonlinear distortion of power amplifier, are derived and expressed. Second, to simplify the expression, the third-order intermodulation distortion (IMD3) is used to calculate the EVM. Then, an expression for the EVM is derived based on the digital transmitter model that considers local oscillator phase noise and nonlinear distortion of power amplifier. Finally, the math formula of bit error rate (BER) versus EVM is given which can be easier and more useful to predict BER, according to analysis of the relationship between EVM and signal to noise rate (SNR), inspired by the works of Rishad, Md. Shahriar and AHM, 2006. Simulations are carried out to display the performance of EVM based on these relationships.

Financial Derivatives Valuation

The article contains a thorough analysis of the world financial derivatives market with special reference to theoretical issues. It puts forward and traces Black-Scholes options valuation model. The author underlines particularities of advanced practical derivatives price calculation, using the math formula of the Nobel Prize winners. Some practical features of the concept and its implementation within notorious Long-Term Capital Management hedge fund are emphasized.

Real‐time recognition of handwritten math formulas

AbstractThis paper proposes a method of realizing a handwritten mathematical formula input system that works in real time. In the handwritten character input, the data is input generally for each stroke (segment). The proposed method is based on this property. The mathematical formula is recognized on the basis of the result of recognition of the individual input strokes and their positional relations. Then the LaTeX source code is generated. In this paper, mathematical symbols are considered as characters, and are integrated into character recognition. More precisely, each time a stroke is input, it is recognized as a single‐stroke character. The crossing with the already input characters is examined, and the character is extracted so that the likelihood of forming character is maximized. Based on the positional relations among the extracted characters, the structure of the mathematical formula, such as superscripts/subscripts and fractions, is recognized. The mathematical structures that can be recognized by the proposed method are the structures obtained by combining five different structures, namely, superscript/subscript, root, overline, underline, and fraction. The recognition is not affected by the order of input. The proposed method is applied to various mathematical formulas, and it is seen that the proposed system works adequately as an input environment for real‐time processing. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 87(8): 66–81, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20086

Math into LATEX: An Introduction to LATEX and AMS-LATEX.

From the Publisher: Gratzer's book provides the beginner with a simple, direct approach. Using numerous examples, a formula gallery, sample files, and templates, a short course, Part I, guides the reader through typing text, math formulas, equations, and an article template making it possible to start typing an article with only a few hours time. The rest of this book provides systematic discussion of all aspects of LaTeX and the AMS packages, customization, and introduces two major tools to help compile long bibliographies and indexes.

A mathematical expression language for imaging applications

The language of image processing is predominantly the language of discrete mathematics. Image processing texts are written using its notation, as are articles for conferences and journals. While math formulae are appropriate for communicating the traditional algorithmic relationships among parts of a process, they have not been used for a complete description of procedures implemented on a computer. This is largely because iteration, assignment and complete description of object shape has been traditionally deemed outside of mathematics and so has been supplied instead by “glue text” surrounding the formulae. We propose an Expression Language, a set of conventions for construction of compilable math expressions, for providing these complete descriptions by extending only slightly the traditional notation of mathematics. The impetus for the Expression Language arose from the need to describe precisely a large number of image processing functions in the context of national and international standards, but the language is also appropriate to graphics and to visualization.

A Discussion on photoelectron spectroscopy - Photoelectron spectra of some polyatomic molecules

The photoelectron spectra of ethylene, ethylene-d4, ammonia, and ammonia-d3 have been measured using a hemispherical high resolution electrostatic spectrometer and the 584 MATHS SYMBOL helium resonance line as the exciting radiation. Many ionization potentials have been determined for each compound and vibration structure associated with the transitions leading to the various ionization potentials has in many cases been well resolved. It has been possible to suggest reasonable assignments for the corresponding vibrational modes. The photoelectron spectra of MATHS FORMULA obtained using neon radiation (736 and 744 MATHS SYMBOL) shows a progression of twenty-one vibrational transitions, with maxima at v = 1 and v = 7. This is larger than the number of vibrational transitions observed with the 584 MATHS SYMBOL helium line and it is postulated that the extra structure observed arises from ionization processes from a long-lived excited state of oxygen.

A discussion on infared astronomy - Expected infrared spectra of gaseous nebulae

If we are asked why we want to use the infrared to observe gaseous nebulae, we might reply with George Mallory, who was asked why he wanted to climb Mount Everest, ‘Because its there’. More specifically, one reason is the very great space penetration possible in the infrared. Diffuse nebulae characteristically are close to the galactic plane, and interstellar extinction therefore prevents the observation of distant objects. At MATHS FORMULA the mean range to which diffuse nebulae can easily be observed is about 1500 parsecs (pc), while many of these nebulae are so reddened as to be nearly unobservable at Hβ. It is for this reason that at present the observation of diffuse nebulae is almost entirely limited to our own spiral arm and its immediate neighbours. However, because of the decrease of interstellar extinction to longer wavelengths, at 1 μm the range of observation would be about 3000 pc; at 2 μm about 10 000 pc, comparable with the distance to the centre of the Galaxy; and at 10μm, about 100 000 pc, far larger than the diameter of the Galaxy. (The form of the interstellar reddening curve is from Whitford 1958.)