Academic literature on the topic 'Third degree equations'

During the Renaissance, the theory of algebraic equations developed in Europe. It is about finding a solution to the equation of the formanxn + . . . + a1x + a0 = 0,represented by coefficients subject to algebraic operations and roots of any degree. In the 16th century, algorithms for the third and fourth-degree equations appeared. Only in the nineteenth century, a similar algorithm for thehigher degree was proved impossible. In (Cardano, 1545) described an algorithm for solving third-degree equations. In the current version of this algorithm, one has to take roots of complex numbers that even Cardano didnot know.This work proposes an algorithm for solving third-degree algebraic equations using only algebraic operations on real numbers and elementary functions taught at High School.

The general diophantine equations of the second and third degree are far from being totally solved. The equations considered in this paper are i) x2−my2=±1 ii) x3+my3+m2z3−3mxyz=1iii) Some fifth degree diopantine equationsInfinitely many solutions of each of these equations will be stated explicitly, using the results from the ACF discussed before.It is known that the solutions of Pell's equation are well exploited. We include it here because we shall use a common method to solve these three above mentioned equations and the method becomes very simple in Pell's equations case.Some new third and fifth degree combinatorial identities are derived from units in algebraic number fields.

Rather unexpectably all real equations of the fourth degree are solvable by real means. So we canclassify all real equations of the third and fourth degree. In this article we classify real cubics. Thereal quartics will be classified in another article.

We consider the difference equation of the form ?(rn?(pn?xn)) = anf (x?(n)) + bn. We present sufficient conditions under which, for a given solution y of the equation ?(rn?(pn?yn)) = 0, there exists a solution x of the nonlinear equation with the asymptotic behavior xn = yn + zn, where z is a sequence convergent to zero. Our approach allows us to control the degree of approximation, i.e., the rate of convergence of the sequence We examine two types of approximation: harmonic approximation when zn = o(ns), s ? 0, and geometric approximation when zn = o(?n), ? ? (0, 1).

The Treatise on Equations of Sharaf al-Dīn al-Ṭūsī (2nd half of the 12th century) is in the tradition of ‛Umar al-Khayyām (d. 1131). However, it has two special features. First, it contains a full discussion of the existence of a solution for third-degree equations, which al-Ṭūsī establishes by proving that the conic curves that represent this solution effectively intersect – a proof based on an intuitive notion of connexity. Secondly, al-Ṭūsī develops algorithms for the numerical resolution of these third-degree equations. The first stage of one of these algorithms follows a procedure which is akin to the so-called method of Newton's polygon.

We construct the linear differential equations of third order satisfied by the classical2-orthogonal polynomials. We show that these differential equations have the following form:R4,n(x)Pn+3(3)(x)+R3,n(x)P″n+3(x)+R2,n(x)P′n+3(x)+R1,n(x)Pn+3(x)=0, where the coefficients{Rk,n(x)}k=1,4are polynomials whose degrees are, respectively, less than or equal to4,3,2, and1. We also show that the coefficientR4,n(x)can be written asR4,n(x)=F1,n(x)S3(x), whereS3(x)is a polynomial of degree less than or equal to3with coefficients independent ofnanddeg⁡(F1,n(x))≤1. We derive these equations in some cases and we also quote some classical2-orthogonal polynomials, which were the subject of a deep study.

The article reveals the role of equations at the basic and profi le levels of teaching students mathematics at school. Various ways of solving rational equations of the third and fourth degree, based on the technique of the introduction of a new variable, are demonstrated. This technique is universal in mathematics. It fi nds its application both in algebra, in the solution of inequalities, in equations and their systems, and in geometry, where the additionally constructed geometric fi gure — a segment, an angle, a circle, a triangle — appears as a new variable. The methods of solving rational equations, shown by the author in this article, will be especially useful and interesting for students of profi le classes, as well as for applicants and students of higher educational institutions and mathematics teachers.

AbstractWe apply the averaging theory of first, second and third order to the class of generalized polynomial Liénard differential equations. Our main result shows that for any n, m ≥ 1 there are differential equations of the form ẍ + f(x)ẋ + g(x) = 0, with f and g polynomials of degree n and m respectively, having at least [(n + m − 1)/2] limit cycles, where [·] denotes the integer part function.

O objetivo desse trabalho à apresentar explanaÃÃes e estratÃgias de resoluÃÃo das equaÃÃes algÃbricas do primeiro, segundo e terceiro graus, uma vez que o ensino relativo à resoluÃÃes dessas equaÃÃes tem se restringido praticamente a apresentaÃÃo da fÃrmula resolutiva e as relaÃÃes entre seus coeficientes e suas raÃzes. Desta maneira procuramos demonstrar e atà mesmo justificar todas as formas apresentadas para se resolver equaÃÃes atà o terceiro grau atravÃs de mÃtodos puramente algÃbricos ou geomÃtricos, como tambÃm, exemplificar todos os mÃtodos que foram exibidos no intuito de satisfazer as expectativas dos leitores, por isso, o texto foi produzido em uma linguagem simples, acessÃvel à professores e alunos. Nesse contexto, espera-se que essa proposta de trabalho estimule os professores de MatemÃtica do Ensino BÃsico a realizarem essa abordagem diferenciada das equaÃÃes algÃbricas em questÃo, pois acredita-se que com essa abordagem ocorram reflexos positivos no processo de ensino e aprendizagem das equaÃÃes e da MatemÃtica.
The aim of this paper is to present explanations and solving strategies of algebraic equations of the first, second and third degrees, since the relative teaching on the resolutions of these equations has been restricted practically the presentation of solving formula and the relationships between its coefficients and its roots. In this way we try to demonstrate and even justify all forms presented to solve equations to the third degree by purely algebraic or geometric methods, but also exemplify all methods that were displayed in order to meet the expectations of readers, so the text was produced in simple language, accessible to teachers and students. In this context, it is expected that this work proposal stimulate the mathematics teachers of Basic Education to perform this differentiated approach to algebraic equations in question, since it is believed that with this approach occur positive reflexes in the teaching and learning of equations and of Mathematics.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Normally, the Basic Education comprises the study of the equations of first and second degree. Most of the textbooks do not address higher order equations. For this reason, we developed a didactic proposal addressing the third degree equation in Hight School. Thus, our main objective is to verify the feasibility of studying cubic equations in this stage of education. However, we began our study having as a motivator trouble finding the approximate number of molecules of air (real gas) contained in a car tire on road conditions, which allowed us to find the number of moles in the Van der Waals Equations and with that, we fall back on solving an equation of the third degree starting it is study.
Normalmente a Educação Básica contempla o estudo das equações do primeiro e segundo grau. Em sua maioria, os livros didáticos não abordam equações de ordem superior. Em razão disso, elaboramos uma proposta didática abordando as equações do terceiro grau no Ensino Médio. Dessa forma, nosso principal objetivo é verificar a viabilidade de se estudar equações cúbicas nesta etapa de ensino. Iniciamos o nosso estudo tendo como problema motivador encontrar o número aproximado de moléculas de ar atmosférico (gás real) contido em um pneu de carro em condições de rodagem, o qual nos possibilitou descobrir o número de mols na Equação de Van der Waals e com isso, recaímos na resolução de uma equação do terceiro grau dando início ao seu estudo.

Bones are multifunctional passive organs of movement that supports soft tissue and directly attached muscles. They also protect internal organs and are a reserve of calcium, phosphorus and magnesium. Each bone is covered with periosteum, and the adjacent bone surfaces are covered by articular cartilage. Histologically, the bone is an organ composed of many different tissues. The main component is bone tissue (cortical and spongy) composed of a set of bone cells and intercellular substance (mineral and organic), it also contains fat, hematopoietic (bone marrow) and cartilaginous tissue. Bones are a tissue that even in adult life retains the ability to change shape and structure depending on changes in their mechanical and hormonal environment, as well as self-renewal and repair capabilities. This process is called bone turnover. The basic processes of bone turnover are: • bone modeling (incessantly changes in bone shape during individual growth) following resorption and tissue formation at various locations (e.g. bone marrow formation) to increase mass and skeletal morphology. This process occurs in the bones of growing individuals and stops after reaching puberty • bone remodeling (processes involve in maintaining bone tissue by resorbing and replacing old bone tissue with new tissue in the same place, e.g. repairing micro fractures). It is a process involving the removal and internal remodeling of existing bone and is responsible for maintaining tissue mass and architecture of mature bones. Bone turnover is regulated by two types of transformation: • osteoclastogenesis, i.e. formation of cells responsible for bone resorption • osteoblastogenesis, i.e. formation of cells responsible for bone formation (bone matrix synthesis and mineralization) Bone maturity can be defined as the completion of basic structural development and mineralization leading to maximum mass and optimal mechanical strength. The highest rate of increase in pig bone mass is observed in the first twelve weeks after birth. This period of growth is considered crucial for optimizing the growth of the skeleton of pigs, because the degree of bone mineralization in later life stages (adulthood) depends largely on the amount of bone minerals accumulated in the early stages of their growth. The development of the technique allows to determine the condition of the skeletal system (or individual bones) in living animals by methods used in human medicine, or after their slaughter. For in vivo determination of bone properties, Abstract 10 double energy X-ray absorptiometry or computed tomography scanning techniques are used. Both methods allow the quantification of mineral content and bone mineral density. The most important property from a practical point of view is the bone’s bending strength, which is directly determined by the maximum bending force. The most important factors affecting bone strength are: • age (growth period), • gender and the associated hormonal balance, • genotype and modification of genes responsible for bone growth • chemical composition of the body (protein and fat content, and the proportion between these components), • physical activity and related bone load, • nutritional factors: – protein intake influencing synthesis of organic matrix of bone, – content of minerals in the feed (CA, P, Zn, Ca/P, Mg, Mn, Na, Cl, K, Cu ratio) influencing synthesis of the inorganic matrix of bone, – mineral/protein ratio in the diet (Ca/protein, P/protein, Zn/protein) – feed energy concentration, – energy source (content of saturated fatty acids - SFA, content of polyun saturated fatty acids - PUFA, in particular ALA, EPA, DPA, DHA), – feed additives, in particular: enzymes (e.g. phytase releasing of minerals bounded in phytin complexes), probiotics and prebiotics (e.g. inulin improving the function of the digestive tract by increasing absorption of nutrients), – vitamin content that regulate metabolism and biochemical changes occurring in bone tissue (e.g. vitamin D3, B6, C and K). This study was based on the results of research experiments from available literature, and studies on growing pigs carried out at the Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences. The tests were performed in total on 300 pigs of Duroc, Pietrain, Puławska breeds, line 990 and hybrids (Great White × Duroc, Great White × Landrace), PIC pigs, slaughtered at different body weight during the growth period from 15 to 130 kg. Bones for biomechanical tests were collected after slaughter from each pig. Their length, mass and volume were determined. Based on these measurements, the specific weight (density, g/cm3) was calculated. Then each bone was cut in the middle of the shaft and the outer and inner diameters were measured both horizontally and vertically. Based on these measurements, the following indicators were calculated: • cortical thickness, • cortical surface, • cortical index. Abstract 11 Bone strength was tested by a three-point bending test. The obtained data enabled the determination of: • bending force (the magnitude of the maximum force at which disintegration and disruption of bone structure occurs), • strength (the amount of maximum force needed to break/crack of bone), • stiffness (quotient of the force acting on the bone and the amount of displacement occurring under the influence of this force). Investigation of changes in physical and biomechanical features of bones during growth was performed on pigs of the synthetic 990 line growing from 15 to 130 kg body weight. The animals were slaughtered successively at a body weight of 15, 30, 40, 50, 70, 90, 110 and 130 kg. After slaughter, the following bones were separated from the right half-carcass: humerus, 3rd and 4th metatarsal bone, femur, tibia and fibula as well as 3rd and 4th metatarsal bone. The features of bones were determined using methods described in the methodology. Describing bone growth with the Gompertz equation, it was found that the earliest slowdown of bone growth curve was observed for metacarpal and metatarsal bones. This means that these bones matured the most quickly. The established data also indicate that the rib is the slowest maturing bone. The femur, humerus, tibia and fibula were between the values of these features for the metatarsal, metacarpal and rib bones. The rate of increase in bone mass and length differed significantly between the examined bones, but in all cases it was lower (coefficient b <1) than the growth rate of the whole body of the animal. The fastest growth rate was estimated for the rib mass (coefficient b = 0.93). Among the long bones, the humerus (coefficient b = 0.81) was characterized by the fastest rate of weight gain, however femur the smallest (coefficient b = 0.71). The lowest rate of bone mass increase was observed in the foot bones, with the metacarpal bones having a slightly higher value of coefficient b than the metatarsal bones (0.67 vs 0.62). The third bone had a lower growth rate than the fourth bone, regardless of whether they were metatarsal or metacarpal. The value of the bending force increased as the animals grew. Regardless of the growth point tested, the highest values were observed for the humerus, tibia and femur, smaller for the metatarsal and metacarpal bone, and the lowest for the fibula and rib. The rate of change in the value of this indicator increased at a similar rate as the body weight changes of the animals in the case of the fibula and the fourth metacarpal bone (b value = 0.98), and more slowly in the case of the metatarsal bone, the third metacarpal bone, and the tibia bone (values of the b ratio 0.81–0.85), and the slowest femur, humerus and rib (value of b = 0.60–0.66). Bone stiffness increased as animals grew. Regardless of the growth point tested, the highest values were observed for the humerus, tibia and femur, smaller for the metatarsal and metacarpal bone, and the lowest for the fibula and rib. Abstract 12 The rate of change in the value of this indicator changed at a faster rate than the increase in weight of pigs in the case of metacarpal and metatarsal bones (coefficient b = 1.01–1.22), slightly slower in the case of fibula (coefficient b = 0.92), definitely slower in the case of the tibia (b = 0.73), ribs (b = 0.66), femur (b = 0.59) and humerus (b = 0.50). Bone strength increased as animals grew. Regardless of the growth point tested, bone strength was as follows femur > tibia > humerus > 4 metacarpal> 3 metacarpal> 3 metatarsal > 4 metatarsal > rib> fibula. The rate of increase in strength of all examined bones was greater than the rate of weight gain of pigs (value of the coefficient b = 2.04–3.26). As the animals grew, the bone density increased. However, the growth rate of this indicator for the majority of bones was slower than the rate of weight gain (the value of the coefficient b ranged from 0.37 – humerus to 0.84 – fibula). The exception was the rib, whose density increased at a similar pace increasing the body weight of animals (value of the coefficient b = 0.97). The study on the influence of the breed and the feeding intensity on bone characteristics (physical and biomechanical) was performed on pigs of the breeds Duroc, Pietrain, and synthetic 990 during a growth period of 15 to 70 kg body weight. Animals were fed ad libitum or dosed system. After slaughter at a body weight of 70 kg, three bones were taken from the right half-carcass: femur, three metatarsal, and three metacarpal and subjected to the determinations described in the methodology. The weight of bones of animals fed aa libitum was significantly lower than in pigs fed restrictively All bones of Duroc breed were significantly heavier and longer than Pietrain and 990 pig bones. The average values of bending force for the examined bones took the following order: III metatarsal bone (63.5 kg) <III metacarpal bone (77.9 kg) <femur (271.5 kg). The feeding system and breed of pigs had no significant effect on the value of this indicator. The average values of the bones strength took the following order: III metatarsal bone (92.6 kg) <III metacarpal (107.2 kg) <femur (353.1 kg). Feeding intensity and breed of animals had no significant effect on the value of this feature of the bones tested. The average bone density took the following order: femur (1.23 g/cm3) <III metatarsal bone (1.26 g/cm3) <III metacarpal bone (1.34 g / cm3). The density of bones of animals fed aa libitum was higher (P<0.01) than in animals fed with a dosing system. The density of examined bones within the breeds took the following order: Pietrain race> line 990> Duroc race. The differences between the “extreme” breeds were: 7.2% (III metatarsal bone), 8.3% (III metacarpal bone), 8.4% (femur). Abstract 13 The average bone stiffness took the following order: III metatarsal bone (35.1 kg/mm) <III metacarpus (41.5 kg/mm) <femur (60.5 kg/mm). This indicator did not differ between the groups of pigs fed at different intensity, except for the metacarpal bone, which was more stiffer in pigs fed aa libitum (P<0.05). The femur of animals fed ad libitum showed a tendency (P<0.09) to be more stiffer and a force of 4.5 kg required for its displacement by 1 mm. Breed differences in stiffness were found for the femur (P <0.05) and III metacarpal bone (P <0.05). For femur, the highest value of this indicator was found in Pietrain pigs (64.5 kg/mm), lower in pigs of 990 line (61.6 kg/mm) and the lowest in Duroc pigs (55.3 kg/mm). In turn, the 3rd metacarpal bone of Duroc and Pietrain pigs had similar stiffness (39.0 and 40.0 kg/mm respectively) and was smaller than that of line 990 pigs (45.4 kg/mm). The thickness of the cortical bone layer took the following order: III metatarsal bone (2.25 mm) <III metacarpal bone (2.41 mm) <femur (5.12 mm). The feeding system did not affect this indicator. Breed differences (P <0.05) for this trait were found only for the femur bone: Duroc (5.42 mm)> line 990 (5.13 mm)> Pietrain (4.81 mm). The cross sectional area of the examined bones was arranged in the following order: III metatarsal bone (84 mm2) <III metacarpal bone (90 mm2) <femur (286 mm2). The feeding system had no effect on the value of this bone trait, with the exception of the femur, which in animals fed the dosing system was 4.7% higher (P<0.05) than in pigs fed ad libitum. Breed differences (P<0.01) in the coross sectional area were found only in femur and III metatarsal bone. The value of this indicator was the highest in Duroc pigs, lower in 990 animals and the lowest in Pietrain pigs. The cortical index of individual bones was in the following order: III metatarsal bone (31.86) <III metacarpal bone (33.86) <femur (44.75). However, its value did not significantly depend on the intensity of feeding or the breed of pigs.

The external surface of a material has an atomic or molecular structure that is different from the bulk material. So does any internal interface within a material. Because of this, the energy of a material or any grain or particle within it increases with the curvature of its bounding surface, as described by the Gibbs-Thomson equation. This chapter explains how surfaces control the nucleation of new phases during reactions such as solidification and precipitation, the coarsening and growth of particles during heat treatment, the equilibrium shape of crystals, and the surface adsorption and segregation of solutes and impurities. The Gibbs-Thomson was predated by a number of related equations; it is not clear whether it is named after J. J. Thomson or William Thomson (Lord Kelvin); and it was not put into its current usual form until after Gibbs’, Thomson’s and Kelvin’s time. J. J. Thomson was the third Cavendish Professor of Physics at Cambridge University. He discovered the electron, which had a profound impact on the world, notably via Thomas Edison’s invention of the light bulb, and subsequent building of the world’s first electricity distribution network. William Thomson was Professor of Natural Philosophy at Glasgow University. He made major scientific developments, notably in thermodynamics, and he helped build the first trans-Atlantic undersea telegraph. Because of his scientific pre-eminence, the absolute unit of temperature, the degree Kelvin, is named after him.

This chapter traces the growth of algebraic thought in Europe during the sixteenth century. Equations of the third and fourth degrees sparked quite a few algebraic fireworks in the first half of the century. Their solutions marked the first major European advances beyond the algebra contained in Fibonacci's thirteenth-century Liber abbaci. By the end of the century, algebraic thought—through work on the solutions of the cubics and quartics but, more especially, through work aimed at better contextualizing and at unifying those earlier sixteenth-century advances—had grown significantly beyond the body of knowledge codified in Luca Pacioli's fifteenth-century compendium, the Summa de arithmetica, geometria, proportioni, e proportionalita. Algebra during this period was evolving in interesting ways.

An analysis on the nonlinear oscillations and chaotic dynamics is presented for a simply-supported symmetric cross-ply composite laminated rectangular thin plate with parametric and forcing excitations. Based on the Reddy’s third-order shear deformation plate theory and the von Karman type equation, the nonlinear governing partial differential equations of motion for the composite laminated rectangular thin plate are derived by using the Hamilton’s principle. The Galerkin method is utilized to discretize the governing partial differential equations of motion to a three-degree-of-freedom nonlinear system including the cubic nonlinear terms. The case of 1:3:3 internal resonance and fundamental parametric resonance, 1/3 subharmonic resonance is considered. The method of multiple scales is employed to obtain the averaged equation. The stability analysis is given for the steady-state solutions of the averaged equation. The Numerical method is used to investigate the periodic and chaotic motions of the composite laminated rectangular thin plate. The results of numerical simulation demonstrate that there exist different kinds of periodic and chaotic motions of the composite laminated rectangular thin plate under certain conditions.

Abstract A two-degree-of-freedom (2-DOF), analytical model of a hydraulic valve lifter is derived. Special features of the model include the effects of bulk oil compressibility, multi-mode behavior due to plunger check valve modeling, and provision for the inclusion of third and fourth body displacements to aid In the use of the model in extended, multi-DOF systems. It is shown that motion of the lifter plunger and body must satisfy a coupled system of third-order, non-linear differential equations of motion. It is also shown that the special cases of zero oil compressibility and/or 1-DOF motion of lifter plunger can be obtained from the general third-order equations. For the case of zero oil compressibility, using Newtonian fluid assumptions, the equations of motion are shown to reduce to a system of second-order, linear differential equations. The differential equations are numerically integrated in five scenarios designed to test various aspects of the model. A modal analysis of the 2-DOF, compressible model with an external contact spring is performed and is shown to be in excellent agreement with simulation results.

Path tracking can be accomplished by separating the control of the desired trajectory geometry and the control of the path variable. Existing methods accomplish tracking of up to third-order geometric properties of planar paths and up to second-order properties of spatial paths using non-redundant manipulators, but only in special cases. This paper presents a novel methodology that enables the geometric tracking of a desired planar or spatial path to any order with any non-redundant regional manipulator. The governing first-order coordination equation for a spatial path-tracking problem is developed, the repeated differentiation of which generates the coordination equation of the desired order. In contrast to previous work, the equations are developed in a fixed global frame rather than a configuration-dependent canonical frame, providing a significant practical advantage. The equations are shown to be linear, and therefore, computationally efficient. As an example, the results are applied to a spatial 3-revolute mechanism that tracks a spatial path. Spatial, rigid-body guidance is achieved by applying the technique to three points on the end-effector of a six degree-of-freedom robot. A spatial 6-revolute robot is used as an illustration.

An analysis on nonlinear dynamic of a cantilevered functionally graded materials (FGM) plate which subjected to the transverse excitation in the uniform thermal environment is presented for the first time. Materials properties of the constituents are graded in the thickness direction according to a power-law distribution and assumed to be temperature dependent. In the framework of the Third-order shear deformation plate theory, the nonlinear governing equations of motion for the functionally graded materials plate are derived by using the Hamilton’s principle. For cantilever rectangular plate, the first two vibration mode shapes that satisfy the boundary conditions is given. The Galerkin’s method is utilized to discretize the governing equations of motion to a two-degree-of-freedom nonlinear system under combined thermal and external excitations. By using the numerical method, the two-degree-of-freedom nonlinear system is analyzed to find the nonlinear responses of the cantilever FGMs plate. The influences of the thermal environments on the nonlinear dynamic response of the cantilevered FGM plate are discussed in detail through a parametric study.

The Bouc/Wen model of mechanical hysteresis may be stated as a system of coupled parametric nonlinear differential equations of third order. This model is based on the equation of motion with damping for a single degree-of-freedom (DOF) system, which is able to reproduce the dynamics of a wide variety of hysteresis shapes, depending on the values of the seven parameters present in the equations. The characterization of the parameters that describe the specific shapes of hysteresis loops is not an easy task, due to the complexity of the model and the great amount of local minima in the search space. Accordingly, heuristic methods of search (optimization) must be carried out in order to curve-fit the model to the trial data sets, in order to extract damping information. Previous works on this topic deal with optimization using Genetic Algorithms (GA). This paper presents a new approach, using Particle Swarm Optimization (PSO). The performances of both methods are then compared when used for artificial and experimental hysteresis loops obtained for sandwich composite materials under test. Some damping measurement techniques often used by researchers are also explained.

The global bifurcation and multi-pulse chaotic dynamics of the four-edge simply supported composite laminated piezoelectric rectangular plate under in-plane and transversal excitations are studied. Based on the model of von Karman type equations for the geometric nonlinearity and the Reddy’s third-order shear deformation theory, the formulas of motion for composite laminated piezoelectric rectangular plate subjected to the in-plane and transversal excitations are derived. Then the Galerkin method is employed to discretize the partial differential equations and the non-autonomous ordinary differential equations with three-degree-of-freedom are derived. The extended Melnikov method is improved to investigate the six-dimensional non-autonomous nonlinear dynamical system in mixed coordinate and the global bifurcation and multi-pulse chaotic dynamics of the composite laminated piezoelectric rectangular plate are studied. The multi-pulse chaotic motions of the composite laminated piezoelectric rectangular plate are found from the numerical simulation which further verifies the result of theoretical analysis.

The bifurcations and chaotic motions of a simply supported symmetric cross-ply composite laminated piezoelectric rectangular plate are analyzed for the first time, which are forced by the transverse and in-plane excitations. It is assumed that different layers of symmetric cross-ply composite laminated piezoelectric rectangular plate are perfectly bonded to each other and with piezoelectric actuator layers embedded in the plate. Based on the Reddy’s third-order shear deformation plate theory, the nonlinear governing equations of motion for the composite laminated piezoelectric rectangular plate are derived by using the Hamilton’s principle. The excitation loaded by piezoelectric layers is considered. The Galerkin’s approach is employed to discretize partial differential governing equations to a two-degree-of-freedom nonlinear system under combined the parametric and external excitations. The method of multiple scales is utilized to obtain the four-dimensional averaged equation. Numerical method is used to find the periodic and chaotic motions of the composite laminated piezoelectric rectangular plate. The numerical results show the existence of the periodic and chaotic motions in the averaged equation. It is found that the chaotic responses are especially sensitive to the forcing and the parametric excitations. The influence of the transverse, in-plane and piezoelectric excitations on the bifurcations and chaotic behaviors of the composite laminated piezoelectric rectangular plate is investigated numerically.

This paper focuses on the analysis on a new kind of nonlinear resonant motion with the low-frequency large-amplitude, which can be induced by the high-frequency small-amplitude mode through the mechanism of modulation of amplitude and phase. The system investigated is a simply supported symmetric cross-ply composite laminated rectangular thin plate subjected to parametric excitations. Experimental research has been carried out for the first time. The test plate was excited near the first natural frequency with parametric forces and the above mentioned high-to-low frequency mode has been observed, whose frequency is extremely lower than the first natural frequency. Theoretical job goes to analysis the above phenomenon accordingly. Based on the Reddy’s third-order shear deformation plate theory and the von Karman type equation, the nonlinear governing equations of the simply supported symmetric cross-ply composite laminated rectangular thin plate subjected to parametric excitations are formulated. The Galerkin method is utilized to discretize the governing partial differential equations into a two-degree-of-freedom nonlinear system. Numerical simulation is conducted to investigate this non-autonomous system subsequently. The results of numerical simulation demonstrate that there is a qualitative agreement between the experimental observation and the theoretical result. Besides, the multi-pulse chaotic motions are also reported in numerical simulations.

Abstract In this study, an inverse kinematic solution approach applicable to six degree-of-freedom industrial robotic manipulators is introduced. The approach is based on a previously introduced kinematic classification of industrial robotic manipulators by Balkan et al. (1999), and depending on the kinematic structure, either an analytical or a semi-analytical inverse kinematic solution is obtained. The semi-analytical method is named as the parametrized joint variable (PJV) method. Compact forward kinematic equations obtained by utilizing the properties of exponential rotation matrices. In the inverse kinematic solutions of the industrial robots surveyed in the previous study, most of the simplified compact equations can be solved analytically and the remaining few of them can be solved semi-analytically through a numerical solution of a single univariate equation. In these solutions, the singularities and the multiple configurations of the manipulators can be determined easily. By the method employed in this study, the kinematic and inverse kinematic analysis of any manipulator or designed-to-be manipulator can be performed and using the solutions obtained, the inverse kinematics can also be computerized by means of short and fast algorithms. As an example for the demonstration of the applicability of the presented method to manipulators with closed-chains, ABB IRB2000 industrial robot is selected which has a four-bar mechanism for the actuation of the third link, and its compact forward kinematic equations are given as well as the inverse kinematic solution.

A two-dimensional theoretical procedure is proposed in this study to estimate sand particle erosion in 90-degree elbows for liquid flow. The two-dimensional model adequately describes the erosion occurring along the centerline of the elbow extrados and to an extent reflects the erosion level on the whole elbow. The sand erosion prediction procedure is divided into three steps: building a two-dimensional liquid flow model, tracking the particle trajectories and predicting the penetration depth. First, a motion expression of the fluid streamline in an elbow is deduced from the continuity equation and the Euler equations, supposing the incompressible flow in the elbow is steady and inviscid. The radial velocity is introduced into the present model to reflect the effect of secondary flow on the symmetry plane. Second, particle trajectories are computed using the Lagrange approach based on the obtained expression of flow field distributions. The effects of the fluid drag force and the virtual mass force are considered as the main factors, and the particle impact velocity and angle are predicted through this method. Third, the penetration depth can be calculated from erosion correlations and the erosion profile along the centerline of the 90-degree elbow can also be worked out. Several typical experiments are selected to verify the two-dimensional theoretical model by comparing the predicted erosion results with the measured data.