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Cajazeiras, LÃcio Laertti Rios. "O centro de massa e aplicaÃÃes à geometria." Universidade Federal do CearÃ, 2016. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=17269.
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Muitas sÃo as ferramentas desenvolvidas para a resoluÃÃo de problemas de Geometria Euclidiana. O presente estudo apresenta uma ferramenta baseada no conceito fÃsico de centro de massa, proporcionando o desenvolvimento de habilidades necessÃrias na resoluÃÃo de problemas geomÃtricos, principalmente em relaÃÃo Ãs questÃes apresentadas em OlimpÃadas de MatemÃticas, tanto no Ensino Fundamental como no Ensino MÃdio.There are many tools developed for solving Euclidean Geometry problems. This study presents a tool based on the physical concept of center of mass, allowing the development of the skills needed to solve geometric problems, especially the ones presented in Mathematics Olympiads, both in Elementary School and in High School.
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Xu, Tongyi. "Design and Analysis of a Shock Absorber with a Variable Moment of Inertia Flywheel for Passive Vehicle Suspension." Thèse, Université d'Ottawa / University of Ottawa, 2013. http://hdl.handle.net/10393/26293.
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Conventional vehicle suspensions consist of a spring and a damper, while mass is rarely used. A mass, if properly used, can also create a damping-like effect. However, a mass has only one terminal which makes it difficult to be incorporated into a suspension. In order to use a mass to achieve the damping-like effect, a two-terminal mass (TTM) has to be designed. However, most of the reported TTMs are of fixed moment of inertia (TTM-CMI), which limits the further improvement of the suspension performance and responsiveness to changes in environment and driving conditions.
In this study, a TTM-based vibration absorber with variable moment of inertia (TTM-VMI) is proposed. The main component of the proposed TTM absorber contains a hydraulic-driven flywheel with sliders. The moment of inertia changes with the positions of the sliders in response to the driving conditions. The performance of the proposed TTM-VMI absorber has been analyzed via dynamics modeling and simulation and further examined by experiments. The analysis results indicate that the TTM-VMI absorber outperforms the TTM-CMI design in terms of body displacement; and ride comfort, tire grip and suspension deflection for zero and impulse inputs with comparable performance for sinusoidal input.
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Blad, Marika, and Balog Alexander Tynnerstål. "Design of Eccentric Double Amplitude Vibration Drum Roller Shaft with Improved Mass Moment of Inertia : Product Development of Compaction Equipment." Thesis, Blekinge Tekniska Högskola, Institutionen för maskinteknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-19643.
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Road construction is important to make transports safe and sustainable. To compact asphalt an amount of energy needs to be conducted into the material either by static pressure or dynamic vibrations. An asphalt-roller compact the material and increases its load-bearing capacity. An eccentric shaft that generates vibrations is attached inside the roller drums. The shaft has two modes, varying between high eccentricity with slower pulses and low eccentricity with faster pulses. The study has been performed with the purpose to decrease the mass moment of inertia by redesigning the present eccentric shaft and verifying the new concepts with linear and non-linear FEM simulations. The new models were to have the same functional properties as the present eccentric shaft. The current cross-section of the shaft was changed to a cross-section of a circle in the periphery. This was done by adding all features in new geometry to a simple shaft base and creating an analysis chain. To create the new lengthwise design brainstorming was used to generate ideas. The ideas were then sorted by using a Pugh matrix. CAD was used to model the concepts with the desired eccentric properties. Simulation in FEM software was used to acquire information about the behaviors during operation. Academic validation and useful information have been gathered by doing a literature review. Two resulting concepts with properties fulfilling the prevailing restrictions. The circular cross-section in the periphery was adapted and the eccentric properties were kept. The simulation results from FEM software ended satisfactorily within limits for both execution in steel and ductile iron. For both concepts the mass moment of inertia was minimized, with 40.5 % in steel and in ductile iron with 42.0 % and 42.6 %. An analysis chain has been performed showing that a cross-section with a circular geometry is optimal when the intention is to minimize the mass moment of inertia. It is possible to minimize the mass moment of inertia without negatively affecting the eccentric properties. The lengthwise design of a shaft with eccentric properties has been studied and simulated. Two concepts with varied lengthwise designs have been created with conserved eccentric properties and significantly decreased mass moment of inertia. The concepts can compose a good basis to continue investigating the lengthwise design which hopefully ends in a manufacturable eccentric shaft that contributes to environmental asphalt construction with low energy usage.Tillverkning av vägar är viktigt för att transporter ska kunna utföras på ett säkert och hållbart sätt. För att packa asfalt behövs en mängd energi överföras till materialet genom statiskt tryck eller dynamiska vibrationer. En asfaltsvält packar materialet och ökar dess belastningsförmåga. En excentrisk axel som genererar vibrationer sitter inuti trummorna på välten. Denna axel har två lägen som varierar mellan att ha hög excentricitet med lägre puls samt låg excentricitet med högre puls. Studien har genomförts med syftet att minska den nuvarande excenteraxelns masströghetsmoment genom att designa om den samt verifiera nya koncept med linjära och icke-linjära FEM beräkningar. De nya modellerna skulle behålla samma funktionella egenskaper som den nuvarande excenteraxeln. Det nuvarande tvärsnittet i XY-planet ändrades till en cirkel i rotationsaxlens periferi, genom att lägga till alla funktioner med nya tvärsnitt på en enkel axelbas i en analyskedja. En ny design i längsled påbörjades med brainstorming för att generera nya idéer. Idéerna sorterades sedan med hjälp av en Pugh-matris. Koncepten modellerades sedan med önskade excentriska egenskaper i CAD. FEM-mjukvara användes för att simulera koncepten och samla information om beteenden under körning. Akademisk validering och användbar information samlades in i en litteraturstudie. Arbetet resulterade i två koncept med egenskaper som uppfyllde rådande krav. Det cirkulära tvärsnittet i periferin behölls och likaså de excentriska egenskaperna. FEM resultaten visade sig hamna tillfredsställande under gränserna med materialen stål och segjärn. För båda koncepten minskade masströghetsmomentet varav 40.5 % i stål och 42.0 % respektive 42.6 % i segjärn. En analyskedja har genomförts som visat att ett tvärsnitt av en cirkel i periferi är optimalt med intentionen att minska masströghetsmomentet. Det är möjligt att minska masströghetsmomentet utan att påverka de excentriska egenskaperna negativt. Designen längs med en axel med excentriska egenskaper har studerats och simulerat. Två koncept med varierad design har modellerats, koncepten har behållna excentriska egenskaper och betydligt minskat masströghetsmoment. Koncepten kan utgöra gott underlag för fortsatt undersökning av designen i längdled. Förhoppningsvis kan det i sin tur resultera i en tillverkningsbar excentrisk axel som bidrar till miljövänligare asfaltskonstruktion med låg energiåtgång.
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Shekar, Sadahalli Arjun. "ADAPTIVE CONTROL DESIGN FOR QUADROTORS." OpenSIUC, 2017. https://opensiuc.lib.siu.edu/dissertations/1472.
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Unmanned Aerial Vehicles (UAV) control has become a very important point of scientific study. The control design challenges of a UAV make it one of the most researched areas in modern control applications. This thesis specifically chooses the Quadrotor as the UAV platform. Considering the quadrotor has 4 rotors and 6 degrees of freedom, it is an underactuated system and is dynamically unstable that has to be stabilized by a suitable control algorithm in order to operate autonomously. This thesis focuses on the quaternion representation of the quadrotor system dynamics and develops an adaptive control for its trajectory tracking problem. The control design uses the certainty equivalence principle where adaptive tracking controls are designed separately for each of the translational and rotational subsystems. With this approach, the success of the outer loop translational control relies on the fast convergence of the inner loop rotational control in order to guarantee the system’s stability while achieving the tracking objective. For the translational subsystem in the outer loop, a modified geometric control technique is considered with an adaptive component for the estimation of the uncertain mass of the quadrotor. For the rotational subsystem in the inner loop a backstepping based control design is adopted due to its systematic design and intuitive approach. An adaptive component is further integrated with it to estimate the integrated components of the uncertain Moment of Inertia matrix and other constant parameters in the system dynamics to guarantee the stability of the inner loop system while achieving the tracking objective. Furthermore, a complete backstepping control design methodology is presented which overcomes the issues of certainty equivalence principle where the inner loop needs to execute significantly faster than the outer loop to stabilize the system.
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Eicholtz, Matthew R. "Design and analysis of an inertial properties measurement device for manual wheelchairs." Thesis, Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/34677.
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The dynamics of rigid body motion are dependent on the inertial properties of the body - that is, the mass and moment of inertia. For complex systems, it may be necessary to derive these results empirically. Such is the case for manual wheelchairs, which can be modeled as a rigid body frame connected to four wheels. While 3D modeling software is capable of estimating inertial parameters, modeling inaccuracies and ill-defined material properties may introduce significant errors in this estimation technique and necessitate experimental measurements. To that end, this thesis discusses the design of a device called the iMachine that empirically determines the mass, location of the center of mass, and moment of inertia about the vertical (yaw) axis passing through the center of mass of the wheelchair.
The iMachine is a spring-loaded rotating platform that freely oscillates about an axis passing through its center due to an initial angular velocity. The mass and location of the center of mass can be determined using a static analysis of a triangular configuration of load cells. An optical encoder records the dynamic angular displacement of the platform, and the natural frequency of free vibration is calculated using several techniques. Finally, the moment of inertia is determined from the natural frequency of the system.
In this thesis, test results are presented for the calibration of the load cells and spring rate. In addition, objects with known mass properties were tested and comparisons are made between the analytical and empirical inertia results. In general, the mass measurement of the test object had greater than 99% accuracy. The average relative error for the x and y-coordinates of the center of mass was 0.891% and 1.99%, respectively. For the moment of inertia, a relationship was established between relative error and the ratio of the test object inertia to the inertia of the system. The results suggest that 95% accuracy can be achieved if the test object accounts for at least 25% of the total inertia of the system. Finally, the moment of inertia of a manual wheelchair is determined using the device (I = 1.213 kg-m²), and conclusions are made regarding the reliability and validity of results. The results of this project will feed into energy calculations for the Anatomical Model Propulsion System (AMPS), a wheelchair-propelling robot used to measure the mechanical efficiency of manual wheelchairs.
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Schulze, Sören. "Bewegungsdesign unter Berücksichtigung des reduzierten Massenträgheitsmoments." Universitätsbibliothek Chemnitz, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-206894.
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Das Bewegungsdesign stellt einen wichtigen Aspekt beim Betrieb von ungleichmäßig übersetzenden Mechanismen dar. Durch Minimierung von Bewegungsparametern wie der Geschwindigkeit und Beschleunigung ist die Verringerung von Schwingungsamplituden sowie Bauteildeformationen infolge kinetostatischer Kräfte erzielbar. Weiterhin kann hierdurch der Verlauf des Antriebsmoments des Motors beeinflusst werden. Das reduzierte Massenträgheitsmoment J(φ) eines nichtlinear übersetzenden Mechanismus ist stellungsabhängig definiert durch die generalisierte Koordinate φ. Daher stellt die Minimierung von Beschleunigung und Geschwindigkeit mittels konstanter Grenzen über den gesamten Antriebsbereich eine Vereinfachung dar, welche die stellungsabhängige Trägheit außer Acht lässt. Der Beitrag stellt eine Möglichkeit zur Generierung der Grenzwerte für die Beschleunigung und Geschwindigkeit aus den Verläufen des reduzierten Massenträgheitsmoments J(φ) sowie dessen Ableitung nach der generalisierten Koordinate J‘(φ) vor. Die ermittelten Ober- und Untergrenzen dienen als Parameter für einen Optimierungsalgorithmus. Dieser nutzt den Ansatz der harmonischen Synthese um mit Hilfe der linearen Programmierung die Bewegungsfunktion zu generieren. Für einen Mechanismus mit einem Freiheitsgrad wird mittels eines herkömmlichen Ansatzes und mit dem neu vorgestellten Verfahren das optimale Bewegungsgesetz ermittelt. Mittels einer Mehrkörpersimulation werden neben Geschwindigkeit und Beschleunigung auch das resultierende Antriebsmoment und der Energiebedarf bilanziert.
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Koh, Meng hock. "Fission-barriers and energy spectra of odd-mass actinide nuclei in self-consistent mean-field calculations." Thesis, Bordeaux, 2015. http://www.theses.fr/2015BORD0208/document.
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Alors qu’il existe de nombreux calculs microscopiques de barrières de fission pour des noyaux composés pair-pairs, il n’y a cependant que relativement peu de tels calculs pour des noyaux de masse impaire. Ceci est dû aux complications induites par la brisure de la symétric de reversement du sens du temps au niveau du champ moyen qui est engendrée par la présence d’un nucleon non apparié. Pour éviter cette difficulté, des calculs existants pour des noyaux de masse impaire ont tout simplement négligé ces effets de brisure de la symétrie de reversement du sens du temps.Dans ce travail, on se donne pour but d’améliorer la description des barrières de fission, aussi bien que des propriétés spectroscopiques du niveau fondamental et de l’état isomérique de fission,pour quelques isotopes de masse impaire dans la région des actinides en prenant en compte de tels effets. Ceci a été réalisé dans le cadre du formalisme de Skyrme–Hartree–Fock plus BCS avec blocking en adaptant ce formalisme à la brisure de la symétrie considérée. L’interaction résiduelle d’appariement a été approchée par une force de séniorité dont les paramètres ont été ajustés pour reproduire les différences de masse pair-impair de quelques noyaux de la région des actinides.Les énergies des têtes de bande rotationnelle de basse énergie ont été calculées dans le cadre du modèle unifié de Bohr-Mottelson pour quatre noyaux bien déformés (235U, 239Pu, 237Np, 241Am)produisant un bon accord qualitatif avec les données pour les noyaux impairs en neutrons. L’accord significativement moins bon obtenu pour les noyaux impairs en protons pourrait résulter de l’usage de l’approximation de Slater pour l’interaction d’échange de Coulomb. Les énergies de déformation de deux noyaux impairs en neutrons (235U, 239Pu) ont été calculées pour quelques configurations de particule individuelle, jusqu’après la barrières de fission externe. La symétrie axiale a été imposée tandis que la brisure de la symétrie droite-gauche (ou de parité intrinsèque) a été permise dans la région de la seconde barrière. Les hauteurs des barrières de fission pour ces noyaux impairs dépendent significativement des configurations de particule individuelle. Un accord qualitatif avec les données disponibles pour les hauteurs de barrières des noyaux impairs considérés et leurs voisins pair-pairs a été généralement obtenuWhile there have been numerous microscopic calculations on fission barriers of even-even compoundnuclei, there are however, relatively few such work dedicated to odd-mass nuclei. This is dueto the complications posed by the breaking of the time-reversal symmetry at the mean-field leveldue to the presence of an unpaired nucleon. In order to circumvent this difficulty, previous fission barriercalculations of odd-mass nuclei have been performed by neglecting the effect of time-reversalsymmetry breaking. This work aims to improve on the description of fission barriers as well asthe spectroscopic properties of ground and fission-isomeric state, of some odd-mass actinide nucleiby taking the effect of time-reversal symmetry breaking into account. This has been perfomedwithin a Skyrme-Hartree-Fock-plus-BCS framework with blocking, where the BCS formalism hasbeen adapted to accomodate this symmetry breaking. The Skyrme nucleon-nucleon effective forcehas been used with various sets of parameters (SIII, SkM*, SLy5*). The residual pairing interactionhas been approximated by seniority forces whose neutron and proton parameters have beenfitted to reproduce the odd-even mass differences of some actinide nuclei. The low-lying rotationalband-head energies evaluated within the Bohr-Mottelson unified model have been determined forfour well-deformed odd-nuclei (235U, 239Pu, 237Np, 241Am) yielding a good qualitative agreementto the data for odd-neutron nuclei. The agreement was significantly less good for the odd-protonnuclei, possibly due to the use of the Slater approximation for the exchange Coulomb interaction.The deformation energies of two odd-neutron nuclei (235U and 239Pu) have been calculated forsome single-particle configurations up to a point beyond the outer fission-barrier. Axial symmetrynuclear shape has been assumed while a breaking of the left-right (or intrinsic parity) symmetryhas been allowed around the outer fission-barrier. The fission-barrier heights of such odd-neutronnuclei depend significantly on the particle configurations. A special attention has been paid tothe very important rotational correction to deformation energies. In particular, the correction ofthe moment of inertia calculated from the usual Belyaev expression was considered. Overall, aqualitative agreement with available data on fission-barrier heights for the considered odd-neutronnuclei and their even neighbours has been obtained
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Warmoth, Francis James. "Floor Vibrations: Girder Effective Moment of Inertia and Cost Study." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/41005.
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Studies on the effective moment of inertia of girders that support concrete slabs using joist seats as the horizontal shear connections, and a cost efficiency analysis comparing composite and non-composite floor systems that meet vibrations design standards, were conducted.
The first study was undertaken because over-prediction of girder effective moment of inertia was the suspected cause of several recent vibration problems in floors supported by widely spaced LH-series joists. Eight purpose-built floors of the type in question were subjected to experimental tests of girder effective moment of inertia and girder frequency. Frequencies were tested for two live loading cases. Three separate test configurations were made with each floor by changing the seat-to-girder connections between bolted, welded, and reinforced. In the study, 1) the accuracy of the current design practice is assessed, 2) a new relationship was proposed, and 3) suggestions for finite element modeling are made.
In recent years, composite construction has been used to improve cost efficiency by reducing structural weight and in some cases by reducing story height. However, vibration problems are a design consideration in composite floors because lighter floors tend to be more lively. It is not clear if cost savings can be made with composite construction if vibrations are considered in the design. To compare the cost of composite and non-composite floors that satisfy AISC/CISC Design Guide criterion for walking excitation, four typical size bays were analyzed using commercial design software that finds the least expensive member configuration for a given bay size. All acceptable bay configurations of member sizes and spacing were evaluated for least non-composite and composite costs, then these results were compared. The findings show that composite construction can be more economical when initial dead load deflections do not control the design.Master of Science
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Schorah, David J. "The effect of moment of inertia on the speed of swung implements." Thesis, Sheffield Hallam University, 2015. http://shura.shu.ac.uk/20803/.
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The maximum swing speed of an implement is an important performance parameter in many sports. It is understood that moment of inertia (MOI) has an effect upon the swing speed of an implement and numerous studies have found a similar rate of swing speed decay (n). These studies considered different movements which suggested that skill was less important than physique to the relationship between swing speed and MOI. The aim of this project was to quantify this relationship and to determine whether the physical characteristics of a participant can be used to predict their swing speed performance. A series of eight visually identical rods with varied MOI were swung in a heavily restricted, maximal motion and trials were recorded with a motion capture system. The results found that swing speed decreased as MOI increased. It was also found that if n was assumed to be constant, the maximum work done by a participant was strongly and significantly related to their swing speed. The relationship between work done and swing speed was used to create a model to predict swing speed for an implement with a specific MOI. This model was validated for a new set of participants performing the same restricted motion and all measured data fell within the confidence intervals of the predictions. The ecological validity of the model was tested in an analysis of the swing speed of tennis groundstrokes. An impact model was used to analyse the effect of changing MOI on ball speed. It was discovered that there is an optimum MOI that produces a maximum ball speed and that this optimum MOI is dependent upon n. This makes the customisation of equipment a realistic possibility. A simple method for measuring n in a non-laboratory environment is proposed that will enable the customisation process to take place.
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Pearce, Steven James. "Core-mantle interactions resulting from sudden changes in the Earth's moment of inertia." Diss., The University of Arizona, 1995. http://hdl.handle.net/10150/187267.
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The effect of sudden changes in the Earth's moment of inertia on the hydromagnetic state of the core is studied. Rapid changes in georotation, due to ice age transgression and regression, are described as varying boundary conditions in an axisymmetric Earth model containing both viscous and electromagnetic coupling. The deterministic equations describing the limit of rapid rotation are employed in conjunction with restricted 2-D predictive magneto-fluid equations. A kinematic description is devised for both buoyancy driven mass motions and the regeneration of the poloidal magnetic field. A pseudo-spectral method is used to solve the incompressible magneto-fluid equations. The variables are collocated in radius using Chebyshev polynomials and the pseudospectral evaluations in colatitude are done using associated Legendre polynomials. Time dependence and magnetic diffusion are controlled by a modified second order semi-implicit Runge Kutta scheme. Deterministic steady state solutions were found in full agreement with Hollerbach and Jones (1993a,b; 1995). Steady state boundary layers, arising from differential motion of the outer core boundaries, were found to induce significant departures for both α²- and αω-dynamo steady state configurations. The hydromagnetic communication time of the core, determined the predictive magneto-fluid equations, is found to be consistent with the deterministic calculations. 'Within the context of this model, it is concluded that a causal connection is plausible between geomagnetic transients and significant changes in the Earth's moment of inertia.
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Petkov, Vesselin P. "Fundamental issues in general relativity, inertia, gravitation and electromagnetic mass." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0004/NQ40303.pdf.
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Kutluay, Emir. "Identification Of Inertia Tensor Of Vehicles." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/3/12608796/index.pdf.
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The aim of this thesis is to develop a methodology for obtaining mass properties of a vehicle using specific test rig. Investigated mass properties are the mass, location of center of gravity and the inertia tensor. Accurate measurement of mass properties of vehicles is crucial for vehicle dynamics research. The test rig consists of a frame on which the vehicle is fixed and which is suspended from the ceiling of the laboratory using steel cables. Mass and location of center of gravity are measured using the data from the test rig in equilibrium position and basic static equations. Inertia tensor is measured using the data from
dynamical response of the system. For this purpose an identification routine which employs prediction error method is developed using the built&ndashin functions from the System Identification Toolbox of MATLAB®
. The experiment was also simulated using Simmechanics Toolbox of MATLAB®
. Identification code is verified using the results of the experiment simulations for various cases.
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Rücker, Jan. "Měření hmotnostních parametrů vozidel." Master's thesis, Vysoké učení technické v Brně. Ústav soudního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-232657.
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This thesis is the first part deals with methods of determining weight parameters of vehicles. By measuring the position of center of gravity and inertia measurements. In the second part focuses on the measurement of gravity position in a selected group of vehicles Škoda and their comparison between vehicles and comparison with simulation programs PCcrach and Virtual crach.
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Wickline, Joseph Edward. "A Study Of Effective Moment of Inertia Models for Full-Scale Reinforced Concrete T-Beams Subjected to a Tandem-Axle Load Configuration." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/35754.
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This thesis is a product of the U.S. Army Corp of Engineer's desire to develop a more accurate procedure for estimating the load capacity of an in-service T-beam bridge.
A bridge type that is a stumbling block for U.S. Army field engineers due to the unknown amount and placement of the flexural reinforcement in the T-beam girder cross-sections.
Personnel from the U.S. Army Corp of Engineer's Waterways Experiment Station in cooperation with personnel from Virginia Tech conceived a procedure that is potentially more accurate, can be quickly executed in the field, and is relatively easy to use by field engineers. In general, the procedure provides a method for transition between the quantity of flexural reinforcement in a reinforced concrete T-beam and the member's actual moment of inertia.
Specifically, the goal of this thesis is to evaluate the accuracy of selected, effective moment of inertia models as a component in the proposed analysis procedure. The accuracy of the selected models is evaluated with test data generated from a testing program detailed herein, which load tested full-scale reinforced concrete T-beams. The test specimens were subjected to a closely-spaced, tandem-axle load configuration, a load configuration typical of military equipment.Master of Science
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Dvořák, Karel. "Měření setrvačných charakteristik těles pro účely matematického modelování dynamiky vozidel." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2008. http://www.nusl.cz/ntk/nusl-227970.
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The aim of the diploma thesis is to create a concept of methods that can be used for measurement of important mechanical inertia properties of bodies -- the coordinates of center of gravity and the the moment of inertia tensor, in case we don't have 3D model of these bodies. The thesis divides this problem into several sub-problems and suggests the solutions for each of them. Required equipment was created and measurement was carried out. At the end the measured values are compared with the teoretical ones and accuracy of this method is determined.
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Bataineh, Anas. "Analysis and design of tall concrete buildings : an investigation regarding the use of cracked versus un-cracked moment of inertia." FIU Digital Commons, 2004. http://digitalcommons.fiu.edu/etd/1431.
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A debate is currently prevalent among the structural engineers regarding the use of cracked versus un-cracked moment of inertia of the structural elements in analyzing and designing tall concrete buildings. (The basic definition of a tall building, according to the Journal of Structural Design of Tall Buildings Vol. 13. No. 5, 2004 is a structure that is equal to or greater than 160 feet in height, or 6 stories or greater.) The controversy is the result of differing interpretations of certain ACI (American Concrete Institute) code provisions. The issue is whether designers should use cracked moment of inertia in order to estimate lateral deflection and whether the computed lateral deflection should be used to carry out subsequent second-order analysis (analysis considering the effect of first order lateral deflections on bending moment and shear stresses). On one hand, bending moments and shear forces estimated based on un-cracked moment of inertia of the sections may result in conservative designs by overestimating moments and shears. On the other hand, lateral deflections may be underestimated due to the same analyses resulting in unsafe designs.
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Bennett, Robert. "Quantum electrodynamic shifts of mass and magnetic moment near dielectric or conducting surfaces." Thesis, University of Sussex, 2013. http://sro.sussex.ac.uk/id/eprint/46447/.
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Quantum electrodynamics is the spectacularly successful theory of the interaction of light and matter. Its consequences are well-understood, and have been experimentally verified to extreme precision. What is not generally known is how these predictions change when the theory is considered in anything other than free space - near a surface, for example. A material boundary causes vacuum fluctuations of the electromagnetic field to be different from their counterparts in free space, causing the electromagnetic environment of a microscopic system sitting near the boundary to differ from that if the surface were not present. This causes a variety of surface-dependent shifts in the properties of the microscopic system - this work investigates these shifts for a free electron. First using explicit normal mode expansion and analytic continuation of the wave-vector in the complex plane, and then using a semi-phenomenological `noise current' approach, the work presents derivations of formulae for the shifts in the mass and magnetic moment of an electron near a dispersive and absorbing surface. The formalism is also extended to the case where the electron is subject to a harmonic potential. It is noted that results for different models of the surface do not agree in the expected limiting cases due to their differing behaviour at low frequency, which leads to the conclusion that one must be very careful to use an appropriate model of a particular surface when considering quantum electrodynamic surface effects. Analysis of the results shows that use of a realistic model of the surface can make these shifts orders of magnitude larger than previous calculations had suggested, since they all relied on the somewhat unrealistic assumption that the surface is perfectly reflecting. This is shown to be particularly relevant to experiments which aim to measure the anomalous magnetic moment of an electron.
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Banibayat, Pouya. "Experimental Investigation of the Mechanical and Creep Rupture Properties of Basalt Fiber Reinforced Polymer (BFRP) Bars." University of Akron / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=akron1323229543.
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Brown, Nicholas Albert Thomas. "Construction of a dynamic-contact task by children : the role of segmental mass and inertia in cycling /." Full text (PDF) from UMI/Dissertation Abstracts International, 2000. http://wwwlib.umi.com/cr/utexas/fullcit?p3004225.
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Hou, Xian. "Detections of seven faint g-ray pulsars and constraints on neutron star moments of inertia with the Fermi-LAT." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2013. http://tel.archives-ouvertes.fr/tel-01058049.
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Le Large Area Telescope (LAT) à bord du satellite Fermi, lancé le 11 Juin 2008, est sensible au rayonnement gamma de20 MeV à plus de 300 GeV. 148 pulsars gamma à ce jour ont été détectés avec le Fermi-LAT, dont 117 sont détaillés dansle Deuxième Catalogue de Pulsars gamma de Fermi (2PC). Les pulsars forment la plus grande classe de sources au GeVdans la Voie Lactée. Les études de pulsars gamma apportent des contraintes importantes sur les modèles d'émission gamma etpermettent des percées dans notre compréhension des pulsars.Cette thèse présente des détections de sept pulsars gamma faibles déjà connus en radio, dont quatre jeunes ou d'âgesmoyens et trois millisecondes (MSP). L'analyse spectrale et la caractérisation des courbes de lumiére sont décriteset comparées à la population de 2PC. Ces détections ont l'intérêt particulier de sonder et d'étendre l'espace desparamètres de la population actuelle. Elles illustrent la distorsion inhérente dans 2PC et marquent la transition de lapremière phase (pulsars brillants) à la seconde phase (pulsars faibles) d'opération de Fermi. Le développement desmodèles théoriques et un recensement complet de la population galactique des étoiles à neutrons bénéficieront de plusde détections de pulsars faibles dans les années à venir.Certains pulsars gamma dans 2PC manifestant de grande efficacité gamma sont étudiés dans cette thèse. L'examen desdifférents paramètres qui influencent l'efficacité conduit à quelques candidats pour lesquels un plus grand momentd'inertie est nécessaire afin de résoudre le paradoxe de grande efficacité. Les observations de Fermi en rayons gamma ontl'air à apporter des contraintes indépendantes sur le moment d'inertie et les équations d'état des étoiles à neutrons.
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Walsh, Maria. "Indentity-in-motion : the narrative duration of the dis/continuous film moment." Thesis, University of Plymouth, 2003. http://hdl.handle.net/10026.1/361.
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The trajectorv of this thesis is set out like a journey upon which encounters are staged between two films. film theor), and philosophers. such as Slavoj Zizek. Gilles Deletize, and Maurice Merleau-Ponty. An encounter with a moment of image suspension. a cut to the blank screen- in Tacita Dean's film, Disappearance atSea (1996). motivates the beginning of this journey's narrative. My reading of this moment counters the way that suspended film moments have been discussed in terms of non-narrative in 1970s film theory and in the contemporary psychoanalýlic filin theory of Slavoj Zizek. Using Gilles Deleuze's notion of narrativization as a process of serialization. I argue that the supposedly non-narrative moment is coextensive with the spectator's dis/continuity in time as opposed to Slavoj Zizek's static suspension or film theory's distanciation. A performative text based on Disappearance at Sea, which I refer to as a 'montage text' and for which precedence is found in Roland Barthes' writing, acts as an interlude that runs in tandem to the main theoretical trajectory. The generativity of absence that emerges from these encounters, both theoretical and poetic. is heightened in the second half of the thesis by the appearance of another 'montage text' based on Chantal Akerrnan's News From Home (1976). In this text. I reconfigure the negativity of historical readings of absence in Neus From Home where it was related to the impossible question of a woman's desire. In my reconfiguration, absence. rather than suspending time. generates a temporalized space and a spatialized time in which the spectator performs the dis/continuity of narrative duration. In the theoretical trajectory of this movement, Gilles Deleuze is hybridized with aspects of Merleau-Ponty's phenomenology, my argument being that the sublime infinity of Deleuzian serialization requires a relation to embodiment in order for it to be useftil in considering the spectator's relation to the two film encounters with absence. I read this hybridization in terms of a feminine mode of the sublime, which suggests the possibility of the real rather than its negation in representation and contributes to current thinking in feminist philosophy, particularly the work of Elizabeth Grosz.
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Snell, Lloyd Dale. "Force and moment analysis of stacked counter rotating eccentric mass tree shaker energy-wheel system." [Ames, Iowa : Iowa State University], 2008.
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Cunha, Wanderley Pires. "Sistema para medições de propriedades de massa." Instituto Tecnológico de Aeronáutica, 1993. http://www.bd.bibl.ita.br/tde_busca/arquivo.php?codArquivo=1743.
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No capitulo 2 deste trabalho sao descritos os metodos maisutilizados de medicao de propriedades de massa como momento de inercia, produto de inercia e Balanceamento Estatico e Dinamico. No paragrafo 2.4 e chamada a atencao para a importancia de seutilizar a maquina de Balancear apropriada para cada forma detrabalho de um corpo-de-prova, na descricao dos tipos existentes de maquinas de Balanceamento. As Maquinas de Balancear especificas para a area espacial sao apresentadas no paragrafo 2.5. No capitulo 3 eexplicada a configuracao adotada pelo SMPM, as equacoes empregadas e as tecnicas de medicao dos seus modos de operacao. O projeto SMPM e finalmente descrito no capitulo 4, com as sequencias dos calculos dos mancais aerostaticos, que equipam a Unidade de Medicao, nos paragrafos 4.1.1 e 4.1.2. Os procedimentos para medicao de propriedades de massa a serem empregados nos modos de operacao da maquina, e na calibracao dos mesmos, sao descritos no capitulo 5, bem como todo o processo de calibracao. Finalmente, os problemas encontrados para emplementar a configuracao adotada neste projeto,as solucoes e as modificacoes recomendadas estao expostos nocapitulo 6.
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Liao, Ruofan. "The anomalous magnetic moment of the muon and the QED coupling at the Z boson mass." Thesis, University of Liverpool, 2011. http://livrepository.liverpool.ac.uk/4913/.
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In this thesis, we present our updated determinations for the leading order and higher order hadronic vacuum polarisation contributions to the anomalous magnetic moment of the muon (a_{\mu} {had,LOVP}, a_{\mu} {had,HOVP}), and for the hadronic contributions to the running of the QED coupling at the Z-boson mass (\Delta\alpha_{had} {(5)}(M_Z 2)). At present the Standard Model (SM) predictions of the anomalous magnetic moment of the muon a_{\mu} {SM} is lower than the experimental measurement a_{\mu} {exp}$ by about 3 standard deviations. The precision of a_{\mu} {SM} is limited by hadronic contributions, of which a_{\mu} {had,LOVP} has the largest uncertainty. Therefore improving the accuracy and precision of a_{\mu} {had,LOVP} will help to clarify the origin of the discrepancy between theory and experiment. The running of the QED coupling at the Z-boson mass \alpha(M_Z 2) is the least precise of the three parameters that is usually taken to define the electroweak sector of the SM. Its precision is limited by \Delta\alpha_{had} {(5)}(M_Z 2), and is a significant limiting factor for precision electroweak physics, e.g. the indirect determination of Higgs boson mass. We describe in detail our refined data-driven approach, which processes and combines a large number of e +e - hadronic annihilation data for use in our determinations. Error treatment is of course, also discussed in depth. We present a detailed breakdown of all the contributions to a_{\mu} {had,LOVP}, including the many new, more precise data used along with discussions on their impacts. We also perform an improved sum rule analysis for a specific energy region, which assists us in discriminating between two different choices of using data. Comparisons with previous analyses as well as with another group's recent determination are also made. For \Delta\alpha_{had} {(5)}(M_Z 2), we summarise the main results, discussing their effects as well as the comparison with other groups. More focus is given to a separate procedure used for preparing a set of new data that will improve the description of \alpha(q 2). We conclude the thesis by summing our a_{\mu} {had,LOVP}, a_{\mu} {had,HOVP} results with the latest predictions of contributions from the other sectors of the SM, leading to our own value for a_{\mu} {SM}. This is then discussed and compared to other recent determinations. Results for \Delta\alpha_{had} {(5)}(M_Z 2) and \alpha(M_Z 2) are also briefly reviewed. Finally, a summary of the whole thesis and future prospects in this area of study are given.
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Grác, David. "Měření momentů setrvačnosti vozidla." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2014. http://www.nusl.cz/ntk/nusl-231201.
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This diploma thesis is concerned with selecting the appropriate method for determining the moment of inertia to the vertical, lateral and longitudinal axis through the centre of gravity of the vehicle. Using the special mechanical device, constructed on IAE was carried out repeated measurements of known mass properties in each axis. With the aid of obtained data was calculated measurement error. To compare the resulting values was created MBS model.
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Toman, Josef. "Zařízení pro měření výškové polohy těžiště vozidla." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2014. http://www.nusl.cz/ntk/nusl-231246.
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This diploma thesis deals with measurement of vehicle centre of gravity height position. In the first part is created summary of methods used for measuring centre of gravity position and moment of inertia of the vehicle. In the other parts are designed and analyzed two dynamics method of measuring centre of gravity height position. This thesis presents analysis of the errors of the proposed methods, results of measurements and design of the construct adjustments device for measuring of the moments of inertia enabling its used for measuring centre of gravity height position. Some components are through analyse of tension.
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Nyangau, Wilson Ombati [Verfasser]. "Microcantilever-based measurement of mass and magnetic moment of liquidborne magnetic micro and nanoparticles / Wilson Ombati Nyangau." München : Verlag Dr. Hut, 2021. http://nbn-resolving.de/urn:nbn:de:101:1-2021100123344253194208.
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Lanči, Jaroslav. "Návrh zařízení pro měření tenzoru setrvačnosti vozidla." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-230309.
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The aim of this thesis was to design a device allowing to measure the moments of inertia of a motor vehicle around several intersecting axes. Next, a three dimensional model of the proposed device was created in programme Pro/ENGINEER. Stress analysis of individual components was performed using the finite element method (FEM) in programme ANSYS.
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Petschlies, Marcus. "Non-perturbative investigation of current correlators in twisted mass lattice QCD." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2013. http://dx.doi.org/10.18452/16770.
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Wir stellen die Resultate einer Untersuchung von Strom-Strom-Korrelatoren beruhend auf den Grundprinzipien der Quantenchromodynamik vor. Wir benutzen die nicht-perturbativen Methoden der sogenannten twisted mass Gitter-QCD mit dynamischem up- und down-Quark unter Ausnutzung der automatischen O(a)-Verbesserung. Als Anwendung diskutieren wir die Berechnung des hadronischen Beitrags zur Korrektur in führender Ordnung in der elektromagnetischen Kopplung zum anomalen magnetischen Moment des Myons. Dieses gilt als eine sehr geeignete Größe für die aktuelle Suche nach neuer Physik jenseits des Standardmodells, besonders im Hinblick auf die Diskrepanz zwischen der Vorhersage aus dem Standardmodell und dem experimentell gemessenen Wert. Innerhalb der theoretischen Bestimmung ist der hadronische Anteil führender Ordnung mit der größten Unsicherheit behaftet und genießt derzeit somit naturgemäß Priorität. Wir beschreiben unsere Studie aller systematischen Unsicherheiten der Gitterrechnung auf Grundlage von drei Gittervolumina, zwei Gitterabständen, Pionmassen im Bereich von 650 MeV bis 290 MeV und den Quark-unverbundenen Beiträgen. Für die Extrapolation zum physikalischen Punkt stellen wir eine neue Methode vor, welche die Abhängigkeit von der Pionmasse hinreichend abschwächt und eine lineare Extrapolation ermöglicht. Im Ergebnis bestimmen wir den Beitrag von up- und down-Quark zu a_mu^hlo(N_f=2) = 5.69 (15) 10^(-8). Die dargelegten Methoden werden auf das Elektron- und das Tau-Lepton erweitert mit dem Resultat a_el^hlo(N_f=2) = 1.512 (43) 10^(-12) bzw. a_tau^hlo(N_f=2) = 2.635 (54) 10^(-6). Wir schätzen den Beitrag des charm-Quarks zu a_mu^hlo in der Partially Quenched tmLQCD mit dem Resultat a_mu^hlo(charm) = 1.447 (24) (30) 10^(-9) in Übereinstimmung mit der Vorhersage über die Dispersionsrelation unter Hinzunahme experimenteller Daten für das hadronische R-Verhältnis.We present an investigation of hadronic current-current correlators based on the first principles of Quantum Chromodynamics. Specifically we apply the non-perturbative methods of twisted mass lattice QCD with dynamical up and down quark taking advantage of its automatic O(a) improvement. As a special application we discuss the calculation of the hadronic leading order contribution to the muon anomalous magnetic moment. The latter is regarded as a promising quantity for the search for physics beyond the standard model. The origin of the strong interest in the muon anomaly lies in the persistent discrepancy between the standard model estimate and its experimental measurement. In the theoretical determination the hadronic leading order part is currently afflicted with the largest uncertainty and a dedicated lattice investigation of the former can be of strong impact on future estimates. We discuss our study of all systematic uncertainties in the lattice calculation, including three lattice volumes, two lattice spacings, pion masses from 650 MeV to 290 MeV and the quark-disconnected contribution. We present a new method for the extrapolation to the physical point that softens the pion mass dependence of a_mu^hlo and allows for a linear extrapolation with small statistical uncertainty at the physical point. We determine the contribution of up and down quark as a_mu^hlo(N_f=2) = 5.69 (15) 10^(-8). The methods used for the muon are extended to the electron and tau lepton and we find a_el^hlo(N_f=2) = 1.512 (43) 10^(-12) and a_tau^hlo(N_f=2) = 2.635 (54) 10^(-6). We estimate the charm contribution to a_mu^hlo in partially quenched tmLQCD with the result a_mu^hlo(charm) = 1.447 (24) (30) 10^(-9) in very good agreement with a dispersion-relation based result using experimental data for the hadronic R-ratio.
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Neužil, Ondřej. "Řízení orientace družice - laboratorní úloha." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2018. http://www.nusl.cz/ntk/nusl-377016.
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This diploma thesis is about the basics of satellite systems, about their sorting, usage and technologies. An important part is the description of the principles controlling and stabilization of the small experimental CubeSat type satellites. The main point is the proposition and construction of the laboratory model of the CubeSat type satellite that should simulate the chosen methods of controlling and stabilization in laboratory conditions. The thesis describes the construction of the electronic parts of the model, the controlling software of the satellite’s processor and user software for easy controlling by PC.
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Votava, Ondřej. "Návrh oběžného kola radiální turbíny se sníženým momentem setrvačnosti." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-432805.
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This master’s thesis deals with topological optimization of the impeller of a radial turbocharger turbine. It focuses on reducing the moment of inertia with unchanged aerodynamic properties. The optimization was carried out using CFD, thermal and structural analysis. The computational modeling was performed using the finite element analysis in ANSYS. The work proposes models of the impeller with the topological modification of the internal structure. Based on the values of moment of inertia, the stress and the strain the most suitable model was selected.
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Nilsson, Albin, and Johan Fallström. "Framtagning av konceptsmodell för mekanisk avskiljning av feltryckta wellpappark." Thesis, Örebro universitet, Institutionen för naturvetenskap och teknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-92814.
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This thesis was made for EMBA Machinery AB and includes a product development process with the result of a concept model. EMBA is a company that develops and manufactures machines for the global corrugated board industry and wants to extend their solutions with a system that automatically removes the misprinted corrugated boards. The idea is to incorporate the system with the already existing processing flow and should be combined with the existing video system that validate the print quality. The concept model is a concept of the mechanical parts needed for the solution and can be used as a foundation for further work towards a product for the market. To produce this concept model methods for divergent problem solving were used. Several concept solutions were created and evaluated with the purpose of finding the best one. This concept was then developed further into a 3D-model of all the interlocking machine- and construction elements, whom in detail demonstrates the removal of misprinted boards. Calculations, which included determining moment of inertia and an acceleration curve, were also done based on data from this model with the intent of testing the plausibility of the solution and to offer a theoretical foundation on which to base further work with this concept.Det här examensarbetet utfördes åt EMBA Machinery AB och innefattar en produktutvecklingsprocess med slutresultat i en konceptmodell. Företaget utvecklar och tillverkar i dag maskiner för den globala wellpapp-industrin och önskar nu komplettera sitt utbud med ett system som automatiskt sorterar bort wellpappark som erhållit felaktigt grafiskt tryck. Detta är tänkt att kunna inkorporeras i deras befintliga processeringsflöde och skall kombineras med befintlig videoteknik för validering av det grafiska trycket. Konceptmodellen som tas fram är således en potentiell lösning av de mekaniska delar som samverkar i sållningen av feltryckta ark och är tänkt som en grund för vidare arbete att ta fram en marknadsfärdig produkt. I processen att ta fram denna konceptmodell tillämpades metoder för divergent problemlösning där flera lösningskoncept genererades och värderades i syfte att hitta det bästa. Detta koncept utvecklades sedan till en mer detaljerad representation av lösningen i form av en 3D-modell av de samverkande maskin- och konstruktionselementen, vilken i detalj demonstrerar hur det valda konceptet löser sållningen av feltryckta ark. Beräkningar, vilka innefattade framtagning av tröghetsmoment och accelerationskurva, utfördes även med data från denna modell i syfte att testa lösningens rimlighet och att erbjuda en teoretisk grund att jobba vidare med i fortsatt arbete av konceptet.
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Jadrný, Jan. "Výpočtový model vyvažovací jednotky řadového pětiválcového motoru v multi-body systému." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2008. http://www.nusl.cz/ntk/nusl-228008.
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The diploma thesis deals with a calculation and a construction concept of a balancing unit of a strait five cylinder combustion engine. The thesis contains the calculation and the construction concept of the balancing shafts. Also the concept of the calculation model of a driving mechanism with the balancing unit in MSC Adams – Engine is included.
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Říha, Stanislav. "Viskózní tlumič torzních kmitů plynového vidlicového šestnáctiválce." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2010. http://www.nusl.cz/ntk/nusl-229308.
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Master’s thesis with title Viscous torsional vibration damper of a gas v-sixteen engine deals with torsion vibrafon of the crankshaft and chance how to eliminated it. First part of diploma thesis containes calculation of torsion vibrafon without damper. In second part is added damper. In the end of this thesis is equaiont made of both parts.
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Gallet, Florian. "Modélisation de l'évolution du moment cinétique des étoiles de faible masse." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENY055/document.
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En 1972, Skumanich découvre une relation empirique unique entre la période de rotation de surface des étoiles G et leur âge sur la séquence principale. Cette découverte ouvrit alors une nouvelle voie pour la datation stellaire : la gyrochronologie. Dès lors, bon nombre d'auteurs, entre la fin des années 80 et 90, se sont intéressés à l'évolution de la vitesse de rotation de surface des étoiles de faible masse ($M_*$ = 0.4 $M_{odot}$- 1.1 $M_{odot}$). Les premiers modèles phénoménologies sur le sujet été nés.L'évolution de la vitesse de rotation de ces étoiles commence à être raisonnablement bien reproduite par la classe de modèle paramétrique que je présente dans cette thèse. Par manque de descriptions théoriques satisfaisantes, seuls les effets globaux des mécanismes physiques impliqués sont ici décris. Le principal enjeu est d'étudier le cadre et la façon dont le moment cinétique stellaire est impacté par ces processus tout en contraignant leurs principales caractéristiques.Au cours de ma thèse, j'ai modélisé les trajets rotationnels des enveloppes externes et médianes des distributions de période de rotation de 18 amas stellaire entre 1 Myr et 1 Gyr. Ceci m'a permis d'analyser la dépendance temporelle des mécanismes physiques impliqués dans l'évolution du moment cinétique des étoiles de type solaire. Les résultats que j'ai obtenus montrent que l'évolution de la rotation différentielle interne impact fortement la convergence rotationnelle (relation empirique de Skumanich), l'évolution de l'abondance de surface en lithium, et les intensités du champ magnétique généré par effet dynamo. En plus de reproduire ces enveloppes externes, le modèle que j'ai développé fournit des contraintes sur les mécanismes de redistribution interne du moment cinétique et sur les durées de vie des disques circumstellaires, supposés responsables de la régulation rotationnelle observée durant les quelques premiers millions d'années de la pré-séquence principale. L'extension du modèle aux étoiles moins massives (0.5 et 0.8 $M_{odot}$) que j'ai réalisé, a également fournis la dépendance en masse de ces différents processus physiques.Cette étape à notamment ajoutée de fortes contraintes sur les temps caractéristiques associés au transport de moment cinétique entre le coeur et l'enveloppe, sur l'efficacité du freinage magnétique vraisemblablement reliée à un changement de topologie des étoiles de type solaire vers celles de 0.5 $M_{odot}$, et sur l'histoire rotationnelle, interne comme de surface, des étoiles entre 1 Myr à 1 GyrIn 1972, Skumanich discovers a unique empirical relationship between the rotation period of the surface of G star and their age on the main sequence. This discovery then opened a new path for stellar dating: the gyrochronology. Therefore, many authors in the late 80's and the begenning 90's, were interested in the evolution of the surface angular velocity of low-mass stars ($M_*$ = 0.4 $M_{odot}$- 1.1 $M_{odot}$). The first phenomenological models on the subject were born.The angular velocity evolution of these stars begins to be reasonably well reproduced by the class of parametrical model that I present in this thesis. Because of the lack of adequate theoretical descriptions, only the overall effects of the physical mechanisms involved are described here. The main issue is to study the framework and how the stellar angular momentum is affected by these processes and to constrain their main characteristics.Over the course of my thesis, I modelled the rotational tracks of external and median envelopes and median of rotation period distributions of 18 stellar clusters between 1 Myr and 1 Gyr. This allowed me to analyse the time dependence of the physical mechanisms involved in the angular momentum evolution of solar-type stars. The results I obtained show that the evolution of the internal differential rotation significantly impact the rotational convergence (empirical Skumanich's relationship), the evolution of the surface lithium abundance, and the intensity of the magnetic field generated by dynamo effect. In addition to the reproduction of these external envelopes, the model I developed provides constraints on the mechanisms of internal redistribution of angular momentum and the lifetimes of circumstellar disks, that are held responsible for the rotational regulation observed during the first few million years of pre-main sequence. The extension of the model to less massive stars (0.5 et 0.8 $M_{odot}$) that I performed also provided the mass dependence of these physical processes. Most specifically, this step added strong constraints on the characteristic time associated to the transport of angular momentum between the core and the envelope, on the efficiency of magnetic braking likely related to a change of topology from solar-type stars to those of 0.5 $M_{odot}$, and on the internal and external rotational history of stars from 1 Myr to 1 Gyr
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Parchański, Martin. "Pětiválcový řadový vznětový motor." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2010. http://www.nusl.cz/ntk/nusl-229101.
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The purpose of this thesis is design of in-line a five-cylinder diesel engine arrangement with given main parameters, power train design, balancing centrifugal and inertia moments and calculation of torsion vibrations. The proposed engine must be based on four-cylinder diesel Zetor engine.
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Srzic, Veljko. "Significance of transport dynamics on concentration statistics and expected mass fraction based risk assessment in the subsurface." Doctoral thesis, KTH, Mark- och vattenteknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-133455.
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This thesis relies on a Langrangian framework used for conservative tracer transport simulations through 2-D heterogeneous porous media. Conducted numerical simulations enable large sets of concentration values in both spatial and temporal domains. In addition to the advection, which acts on all scales, an additional mechanism considered is local scale dispersion (LSD), accounting for both mechanical dispersion and molecular diffusion. The ratio between these two mechanisms is quantified by the Peclet (Pe) number. In its base, the thesis gives answers to contaminant concentration features when influenced by: i) different log-conductivity variance; ii) log-conductivity structures defined by the same global variogram but with different log conductivity patterns cor-related; and iii) for a wide range of Peclet values. Results conducted by Monte Carlo (MC) analysis show a complex interplay between the aforementioned pa-rameters, indicating the influence of aquifer properties to temporal LSD evolu-tion. A stochastic characterization of the concentration scalar is done through moment analysis: mean, coefficient of variation (CVC), skewness and kurtosis as well as through the concentration probability density function (PDF). A re-markable collapse of higher order to second-order concentration moments leads to the conclusion that only two concentration moments are required for an accurate description of concentration fluctuations. This explicitly holds for the pure advection case, while in the case of LSD presence the Moment Deriv-ing Function (MDF) is involved to ensure the moment collapse validity. Fur-thermore, the expected mass fraction (EMF) concept is applied in groundwater transport. In its origin, EMF is function of the concentration but with lower number of realizations needed for its determination, compared to the one point PDF. From practical point of view, EMF excludes meandering effect and incorporates information about exposure time for each non-zero concentration value present. Also, it is shown that EMF is able to clearly reflect the effects of aquifer heterogeneity and structure as well as the Pe value. To demonstrate the uniqueness of the moment collapse feature and ability of the Beta distribution to account for the concentration frequencies even in real cases, Macrodisper-sion Experiment (MADE1) data sets are used.QC 20131104
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Grzeszczak, Jan, and Michał Płygawko. "Frequency Analysis of Rottne Comfort Line." Thesis, Linnéuniversitetet, Institutionen för maskinteknik (MT), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-35924.
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The European Parliment stipulated regulations concerning the forestry vehicles operators' health and working conditions. The allowed whole body vibrations were limited, which influenced the design of the vehicles' cabin. Surveys show a strong correlation between operator's comport and their productivity. The object of the research was Rottne AB Comfort Line Cabin, which was designed to increase the comfort for the forwarder operators. The main objective was to determine the cab's inertia properties, position of the centre of gravity and the resonance frequencies of the cab as well as a system consisting of the cab and its suspension. The methods used were an impact test with Mass-Line Analysis for the cab's properties and Operational Modal Analysis for the system. For both tests a Leuven Measurement System was used, but a part of the calculations were made in parallel by use of a MATLAB code written for this thesis. In addition a suspension test was made to estimate the centre of gravity and it was here treated as the reference value. The authors used reference values and the quality of the obtained results to compare the methods used. Further proposals for future research were made together with hints how to use vibration tests more effectively.
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Hanych, Jaroslav. "Konstrukční návrh zařízení pro měření výškové polohy těžiště vozidla." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-378015.
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This master's thesis deals with problems connected with measuring vehicle centre of gravity height. The research part summarizes generally known methods of measuring vehicle centre of gravity and moments of inertia. Essential part of this thesis is the design of a device for measuring the centre of gravity height of a road vehicle on a principle of measuring a period of oscillation. The height position of the platform of the device is adjustable through hydraulic cylinders. A stress-strain analysis of the design was executed through a combination of analytical methods and a finite element method. The process of measurement was described and an equation for determination of centre of gravity height was deduced. Error of measurement was estimated based on the knowledge of partial errors of measured values.
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Jelbert, K. "The comparative demography of invasive plants." Thesis, University of Exeter, 2018. http://hdl.handle.net/10871/34994.
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Biodiversity, ecosystems, industry and human health are threatened by invasive plant species. The costs of mitigating damages run into billions of pounds per annum. Fundamental to the control of invasive plant species is an ability to predict which species will become invasive. Yet identification of predictive differences between invasive and non-invasive species has proven difficult to pinpoint. In this thesis I identify several weaknesses within published literature, and using field experiments and meta-analyses we address these to find consistent predictors of invasiveness amongst plants. Specifically, I recognize that predictors of invasiveness can be identified by studying plant species in the native range because species may undergo phenotypic and demographic changes following naturalization (Chapters 2 – 5). I also recognize the importance of comparing globally invasive and non-invasive species, and the importance of accounting for phylogenetic relationships so as not to inflate or conceal differences (Chapters 2 – 4). Finally, I investigate whether particular analyses are more appropriate for investigating life history and demographic differences (Chapter 5). This thesis comprises an introductory chapter (Chapter 1), four data chapters (Chapters 2 - 5) and a general discussion (Chapter 6). Chapters 2 and 3 compare life history traits of plant species known to be invasive elsewhere, with their exported but non-invasive sympatric relatives in the native range. Chapter 4 utilizes Population Projection Matrices held within the COMPADRE Plant Matrix Database, to compare demographic projections of stable and transient dynamics of invasive and non-invasive plants; and Chapter 5 compares ten metrics, derived from Population Projection Matrices, of seven invasive species between the native and invaded range to determine if there are demographic or life history differences that facilitate invasion, and to identify those analyses that are most likely to reveal such differences. I find reproductive capacity to be a predictor of invasiveness, and that analyses of transient dynamics are more likely than analyses of projected stable dynamics to reveal demographic or life history differences between invasive and non-invasive species or populations of plants. I discuss these findings in the context of invasive risk assessment protocols and highlight future research opportunities.
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Fracarolli, Juliana Aparecida 1984. "Utilização do biospeckle laser na avaliação do potencial germinativo de sementes de ipê-roxo (Tabebuia heptaphylla) (Vellozo) Toledo." [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/256884.
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Orientadores: Inacio Maria Dal Fabbro, Leila MartinsDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agrícola
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Resumo: O ipê-roxo (Tabebuia heptaphylla (Vellozo) Toledo) é uma espécie de alto valor econômico, ornamental e medicinal, pertencente à família Bignoniaceae, cuja multiplicação ocorre prioritariamente por sementes. Há considerável necessidade de estudos sobre o desempenho fisiológico das unidades de dispersão dessa e de outras espécies florestais. O objetivo desse trabalho foi avaliar a potencialidade do biospeckle, técnica baseada no fenômeno óptico de interferência, como ferramenta de caracterização do potencial germinativo das sementes de ipê-roxo. A quantificação do biospeckle foi expressa através do cálculo do Momento de Inércia (MI). Foram utilizados laser vermelho (632 nm de comprimento de onda) e 10 mW de potência, câmera filmadora digital e computador. Foram realizados cinco experimentos, a saber: (1) Avaliação de danos térmicos em sementes através do biospeckle; (2) Avaliação da interferência do tegumento na sensibilidade do biospeckle; (3) Diferenciação entre sementes germinadas e não germinadas através do biospeckle; (4) Determinação da faixa de umidade das sementes para a melhor interação entre o laser e a semente para o biospeckle; (5) Avaliação de sementes de ipê-roxo submetidas ao envelhecimento acelerado através do biospeckle. Para os experimentos 1, 2, 3 e 4 as sementes foram hidratadas até atingirem grau de umidade de 69%, divididas em quatro sub-amostras sendo que duas delas foram submetidas ao congelamento. Em seguida as sub-amostras foram separadas em 5 níveis de umidade (28, 35, 54, 63, 69%) e iluminadas com laser. Nesses ensaios foram planejados quatro tratamentos: (1) sementes sem tegumento; (2) sementes com tegumento; (3) sementes sem tegumento submetidas a congelamento a 0°C e (4) sementes com tegumento submetidas ao congelamento a 0°C. Os resultados permitem afirmar que é possível diferenciar as sementes que sofreram dano térmico daquelas que não sofreram através do biospeckle. A presença do tegumento interfere na sensibilidade do biospeckle. É possível diferenciar as sementes viáveis das inviáveis através do biospeckle. Do experimento 4 obteve-se uma correlação positiva entre os valores de MI e de umidade das sementes. Verificou-se também que a faixa de teor de água para a melhor interação entre o laser e a semente de ipê-roxo está entre 28 e 54%. Esta faixa de umidade das sementes foi utilizada como referência para o experimento 5. No experimento 5 as sementes foram submetidas ao envelhecimento acelerado (42°C e umidade relativa do ar de 100 % durante 24, 48, 72, 96 e 120 horas) e avaliadas através da técnica do biospeckle e teste de germinação. Obteve-se que é possível detectar a redução de viabilidade e vigor das sementes de T. heptaphylla ocasionada pelo envelhecimento acelerado. Dessa forma, o biospeckle é uma técnica que vem sendo desenvolvida e apresenta-se como uma ferramenta possível para avaliar o potencial germinativo das sementes de ipê-roxo
Abstract: Ipê-roxo (Tabebuia heptaphylla (Vellozo) Toledo) is considered of very important economical, ornamental, as well as medicinal value which is included in the Bignoniaceae botanical family which multiplication is quite solely carried by seeds. Forest dispersion elements, i.e., the seeds, deserve a deep understanding of their physiological performance. The objective of this research work was to evaluate a biospeckle method potential in testing seed viability, which is based on the laser interferometry. The biospeckle phenomenon quantification was carried by means of the Moment of Inertia (MI) which formula resembles its mechanical counterpart. The equipment employed in the experimental setup included a 632 nm red diode laser of 10mW, a digital movie camera as well as a PC. The five tests carried were (1) thermal damage evaluation on seeds, (2) biospeckle sensitivity to the tegument interference, (3) differentiation between non germinated and germinated seeds evaluation by the biospeckle, (4) determination of the best seed moisture content to laser interaction and (5) evaluation of accelerated aging ipê-roxo seeds through the biospeckle. In tests 1, 2, 3 and 4 seeds were hydrated to the value of 69% and divided into four sub samples from which two of them were forwarded to freezing. Following the four sub samples were separated into five moisture level groups (28, 35, 54, 63, 69%) and exposed to the laser. Four treatments have been imposed to the experimental tests, named (1) seeds without teguments, (2) seeds with tegument, (3) frozen at 0° C seeds without teguments and (4) frozen at 0° C seeds with teguments. Results from biospeckle tests confirm the possibility of differentiating seeds with thermal damage from those without thermal damage. When the tegument is covering the seed, the sensitivity of biospeckle is affected.?It's possible to differentiate viable seeds from non viable seeds using biospeckle technique. From test (4) it is obtained a positive correlation between MI and seeds moisture content. It was also verified that seed moisture content between 28% and 54% showed better interaction with laser. That moisture content range was adopted for the test (5). Seeds were submitted to accelerated aging process in the test (5) (42°C and 100% of relative humidity for 24, 48, 72, 96 and 120 hours) following by biospeckle evaluation and germination tests. It was concluded that viability reduction of T. heptaphylla as generated by accelerated aging can be detected by the biospeckle test. Thus, the biospeckle is a technique that has been developed and is presented as a possible tool to assess the germination potential of ipê-roxo seeds
Mestrado
Maquinas Agricolas
Mestre em Engenharia Agrícola
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Drozdek, Lukáš. "Silikonový tlumič torzních kmitů řadového šestiválcového vznětového motoru." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2008. http://www.nusl.cz/ntk/nusl-228281.
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This thesis "Silicone damper of a six-cylinder in-line diesel engine " is focused on the proposal of alternative using of silicone damper for the a six-cylinder in-line diesel engine, which is made for tractors and other industrial aplications. The aim of this thesis is to count the oscilation of crankshaft by the help of appropriate dynamic model, then to propose such a basic parameters of silicone damper, which absorbes torsion blip crankshaft to acceptable value. The next part of my thesis is proposal of the constructive implementation of fixation the silicone damper on the free part of crankshaft. The last part of my thesis is comparing and evaluating the oscilation of crankshaft without a dumper and with a new propsal of the silicone damper.
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Allain, Stéphanie. "L'évolution du moment cinétique des étoiles pré-séquence principale de faible masse." Grenoble 1, 1997. http://www.theses.fr/1997GRE10167.
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Cette thèse présente l'étude de la rotation des étoiles de faible masse (entre 0,5 et 1,2 m#+) pendant leurs phases pré-séquence principale, depuis les T Tauri âgées de quelques millions d'années, et séquence principale, à quelques milliards d'années. Deux approches complémentaires ont été utilisées : les observations apportent de nouvelles mesures de rotation de ces objets et la modélisation permet de comprendre les processus physiques mis en jeu. Les observations ont porté essentiellement sur les amas jeunes, IC4665, Alpha Persée et les Pléiades. Dans ces amas, les étoiles de type solaire sont à un âge charnière entre la phase pré-séquence principale et la séquence principale. Alors qu'un grand pourcentage d’étoiles tournent à des vitesses inferieures à 10 km. S#-#1, leurs vitesses de rotation exactes n'étaient pas connues à cause des limites de résolution instrumentales. Grace aux instruments CORAVEL et ELODIE de l'OHP, toutes les vitesses de rotation sont maintenant résolues dans Persée et les Pléiades pour les étoiles de masse comprise entre 0,6 et 1,1 m#+. Les distributions de vitesse équatoriales en fonction de la masse ont été construites dans les deux amas et sont comparées aux modèles. Un modèle d'évolution du moment cinétique a été développé, qui permet de prendre en compte l'évolution pré-séquence principale : les changements de structure interne, l'effet d'un disque d'accrétion, la perte de moment cinétique à la surface et le transfert de moment cinétique entre le cœur et l'enveloppe. Les nouvelles données apportent des contraintes fortes quant au transport de moment cinétique dans les intérieurs stellaires. Dans les étoiles en rotation rapide, un transfert très efficace du moment cinétique permet à l’étoile de garder une rotation quasi-solide pendant toute son évolution, de la phase T Tauri jusqu'à l’âge du soleil, en accord avec les observations de l'intérieur solaire. Par contre, l'existence même d'un grand nombre de rotateurs lents nécessite un découplage entre le cœur et l'enveloppe, avec un temps caractéristique de couplage de 100 millions d'années. L'évolution de la vitesse de ces rotateurs très lents au début de la séquence principale, pendant laquelle leur vitesse varie très peu, est également en accord avec un temps de couplage très long.
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Štěpánek, Tomáš. "Měření polohy těžiště vozidla." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2008. http://www.nusl.cz/ntk/nusl-228353.
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This diploma thesis is devoted to problems of measurement centre of gravity position. At the beginning diploma thesis is created summary of methods to measuring moment of inertia and position measuring of centre of gravity of vehicle. Proposal is in-process on the basis method weighing on oblique position. And measurement is possible in Institute of automotive engineering in Brno. Is proposed measuring platform and preparative for obstruct changes of centre of gravity position at measuring. Measuring procedure is described and is derived formula toward calculation position of gravity centre of vehicle. To troubleshooting parts of platform are elaborate solidity calculations. In final parts diploma thesis are mentioned results from these measurements. Drawing documentation of platform and programme for calculation of centre of gravity of vehicle is enclosed in diploma thesis.
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Yu, Zitian. "Integrated Estimation and Motion Control for Electric Vehicles." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1531778655719369.
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Kubica, Petr. "Zařízení pro měření výškové polohy těžiště vozidla." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-232123.
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This diploma thesis deals the with measurment of the centre of gravity height position of a road vehicle and its issues. The introduction of this thesis focuses on the determining of the position of the center of gravity and the moment of inertia of a road vehicle. The next part is about creationing of a construction plan and its verification. The thesis contains a sensitivity analysis of this device including its results. The end of the thesis informs about the executed measurment in a laboratory and about recommendations for next measurments.
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Iacobucci, Marco. "Dynamic parameter identification of a collaborative robot." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021.
Find full textAbstract:
I robot collaborativi stanno guadagnando un interesse crescente nel campo della robotica. Dal momento che l'industria 4.0 richiede nuovi livelli di flessibilità e soluzioni innovative di prodotto, robot e umani recentemente hanno iniziato ad interagire e lavorare in un 'ambiente comune senza protezioni perimetrali. Questa tecnologia emergente può provvedere all'operatore supporto fisico o assistenza nello svolgere compiti pericolosi o faticosi. In questo scenario, un controllo in tempo reale dovrebbe essere il più affidabile possibile e minimizzare ogni rischio legato alla collaborazione tra uomo e robot.
L'obiettivo di questa tesi è l'identificazione dei coefficienti dinamici che linearizzano il modello del robot e dei parametri dinamici (massa, posizione del centro di massa ed elementi dei tensori d'inerzia di ciascun membro), utili per simulare il comportamento del robot in ambiente CAD, per ottenere simulazioni dinamiche più realistiche e algoritmi di controllo in tempo reale più affidabili.
Un approccio di identificazione dinamica è presentato per il Franka Emika Panda, un robot collaborativo a 7 gradi di libertà. Questo consiste nel suddividere l'identificazione in due fasi: una prima fase in cui si analizzano le sole configurazioni statiche del robot per ottenere un set di possibili masse e centri di massa, ed una seconda fase in cui si considera il robot in movimento ed è possibile ottenere alcuni valori degli elementi dei tensori d'inerzia. Seguendo questo approccio, è possibile ottenere una stima più precisa dei parametri di massa e di posizione dei centri di massa rispetto ad un approccio in cui l'identificazione viene compiuta in una singola fase, cosa che è stata successivamente dimostrata da alcuni test eseguiti sul robot stesso, i cui risultati sono stati confrontati con quelli ottenuti seguendo un altro approccio e quelli restituiti direttamente dalla libreria del robot.
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Horký, Karel. "Návrh setrvačníku jednovzpěrného čelisťového drtiče." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-400467.
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Diploma thesis deals with design of a flywheel and a belt pulley of single toggle jaw crusher DCJ 900x600. The first part is dedicated to overview of the methods for calculation of a size of flywheels for working machines. The second part is focused on calculation of a size of the flywheel. The third part treats the constructional design of the flywheel. In the last two parts there is elaborated analysis of a changing size of the flywheel depended on increasing the working rotation speed and change of coefficient .
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Bassler, Christopher Colby. "Analysis and Modeling of Hydrodynamic Components for Ship Roll Motion in Heavy Weather." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/23258.
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Ship roll motion has been the subject of many studies, because of the complexities associated with this mode of ship motion, and its impact on operability, safety, and survivability. Estimation and prediction of the energy transfer and dissipation of the hydrodynamic components, added inertia and damping, is essential to accurately describe the roll motions of a ship. This is especially true for ship operations in moderate to extreme sea conditions. In these conditions, a complex process of energy transfer occurs, which alters the physical behavior of the hydrodynamic components, and ultimately affects the amplitude of ship roll motion. Bilge keels have been used on ships for nearly two centuries, to increase damping and reduce the severity of roll motions experienced by a ship in waves. Because ship motions are more severe in extreme sea conditions, large roll angles may occur. With the possibility of crew injury, cargo damage, or even capsize, it is important to understand the behavior of the roll added inertia and damping for these conditions. Dead ship conditions, where ships may experience excitation from beam, or near beam, seas present a worst case scenario in heavy weather. The behavior of a ship in this condition should be considered in both the design and assessment of seakeeping performance.
In this study, hydrodynamic component models of roll added inertia and roll damping were examined and assessed to be unsuitable for accurate prediction of ship motions in heavy weather. A series of model experiments and numerical studies were carried out and analyzed to provide improved understanding of the essential physical phenomena which affect the hydrodynamic components and occur during large amplitude roll motion. These observations served to confirm the hypothesis that the existing models for roll added inertia and damping in large amplitude motions are not sufficient. The change in added inertia and damping behavior for large roll motion is largely due to the effects of hull form geometry, including the bilge keels and topside geometry, and their interactions with the free surface. Therefore, the changes in added inertia and damping must be considered in models to describe and predict roll motions in severe wave environments.
Based on the observations and analysis from both experimental and numerical methods, several time-domain model formulations were proposed and examined to model hydrodynamic components of large amplitude roll motions. These time-domain formulations included an analytical model with memory effects, a piecewise formulation, and several possibilities for a bilge keel force model. Although a piecewise model for roll damping was proposed, which can improve the applicability of traditional formulations for roll damping to heavy weather conditions, a further attempt was undertaken to develop a more detailed model specifically for the bilge keel force. This model was based on the consideration of large amplitude effects on the hydrodynamic components of the bilge keel force. Both the piecewise and bilge keel force models have the possibility to enable improved accuracy of potential flow-based numerical prediction of ship roll motion in heavy weather. However, additional development remains to address issues for further practical implementation.
Ph. D.
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Galásek, Martin. "Pryžový tlumič torzních kmitů čtyřválcového vznětového motoru." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-377464.
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The diploma thesis ‚Rubber Torsional Vibration Damper Of a Four-Cylinder Diesel Engine‘ covers all the development phases related to a design of a rubber damper for a specified engine. The individual phases of it are discussed in details throughout the thesis. At first, the construction plan of a crankshaft is given. The computational checks for torsional vibrations and forced torsional vibration are performed then. With regards to it there might be derived the basic parameters and dimensions of a rubber torsional vibration damper. The knowledge of them enables to prepare the constructional plan of a rubber torsional vibration damper. By using this damper construction plan the torsional displacements (deviations) and forced vibrations are calculated. Finally, a mechanical and thermal stress test of this damper is performed and a crankshaft production drawing is produced.