Modeling and analysis of nonlinear rotordynamics due to higher order deformations in bending

A mathematical model incorporating the higher order deformations in bending is devel- oped and analyzed to investigate the nonlinear dynamics of rotors. The rotor system con- sidered for the present work consists of a flexible shaft and a rigid disk. The shaft is modeled as a beam with a circular cross section and the Euler Bernoulli beam theory is applied with added effects such as rotary inertia, gyroscopic effect, higher order large deformations, rotor mass unbalance and dynamic axial force. The kinetic and strain (defor- mation) energies of the rotor system are derived and the Rayleigh–Ritz method is used to discretize these energy expressions. Hamilton’s principle is then applied to obtain the mathematical model consisting of second order coupled nonlinear differential equations of motion. In order to solve these equations and hence obtain the nonlinear dynamic response of the rotor system, the method of multiple scales is applied. Furthermore, this response is examined for different possible resonant conditions and resonant curves are plotted and discussed. It is concluded that nonlinearity due to higher order deformations significantly affects the dynamic behavior of the rotor system leading to resonant hard spring type curves. It is also observed that variations in the values of different parameters like mass unbalance and shaft diameter greatly influence dynamic response. These influences are also presented graphically and discussed

Couplings in parametrically excited inclined cables systems

Cables in stayed bridges are subjected to important dynamic solicitations for which dynamic model are now well established. Due to their design, such structures highlight resonance phenomena and instabilities frequently observed. Nevertheless, some structures exhibit important vibration amplitudes that can not be explained simply. Measurement recently performed on a bridge point a coupling of the cable with the deck or the pillar. The present paper suggests to consider the deck flexibility coupled to the nonlinear dynamic of the inclined cable. Results of previous study are used. The retained nonlinear model of the cable include two degrees of freedom for the in-plane motion. Considering the bridge mass and deck rigidity adds one DOF, assumed linear in a first approach. The excitation is created on the deck, which produce an external force(such as the wind or the car traffic for example). An experimental set-up uses a specific device in order to highlight expected coupling phenomena on the parametric instabilities. It is composed of a flexible blade which represents the deck, and an inclined cable. Both elements are linked to a mass forced to move vertically, and which represent the anchor point and the equivalent mass of a section of the deck. Therefore, the cable has a given initial static tension. An electrodynamic shaker applies a force close to blade clumping. The transmitted force from the shaker to the structure is measured thanks to a piezo-electric sensor. The instantaneous cable tension is measured via a Shape force sensor. And a high resolution laser sensor captures without contact the in-plane motion of the cable. Analytically, the multiple scales method is applied to solve the nonlinear equations of motion. In-plane vibration of the cable and stability in the vicinity of the primary resonance w1 and sub-harmonic resonance 2w1 are computed. The competition between the behaviour at 2w1 and w2 are of particular interest, as it is observed experimentally

Instability zones for isotropic and anisotropic multibladed rotor configurations.

Helicopter ground resonance is an unstable dynamic phenomenon which can lead to the total destruction of the aircraft during take-off or landing phases. The earliest research in this domain was carried out by Coleman and Feingold during the decade of 60s. The instability was predicted by using classical procedures once the rotor was considered as isotropic, consequently, the periodic equations of motion could be simplified to a system with constant coefficients by introducing a change of variables, known as the Coleman Variable Transformation. The goal of the present work is to further comprehend the phenomenon and the influence of the anisotropic properties of rotors by analyzing the periodic set of equations of motion. For this, Floquet's Theory (Floquet's Method — FM) is used. The analysis for predicting the ground resonance phenomenon in isotropic and anisotropic rotor configurations is explored. The conclusions lead to verify the appearance of bifurcation points depending on the anisotropic characteristic present in the rotor. The temporal response analysis in the motion of helicopter with one asymmetric blade at unstable regions highlighted the presence of non symmetric rotor deformation shapes

Enseignement, protestantisme et modernité. Les écoles du pays de Montbéliard (1724-1833)

International audienceIn the 16th century, the Principality of Montbéliard, following the Dukes of Wurtemberg, became Lutheran, which led to the creation of a stable network of primary and secondary schools during that same century. In the 18th century, this network at the meeting point of French and German influences underwent major development as well as a modernization of teaching promoted by ministers and administrators alike. The incorporation of the county of Montbéliard into France during the French Revolution could have modified this situation. This study demonstrates that the dignitaries, and especially the ministers, fought to maintain the Protestant characteristics of their schools while never rejecting the contribution of ideas outlined nationally. They did not refuse the innovations that were necessary in a France modified by the destabilizing influences of the Industrial Revolution, for they perceived them as being essential to saving their inheritance.La principauté de Montbéliard adopta au XVIe siècle le luthéranisme, dans le sillage des ducs de Wurtemberg, ce qui entraîna dès la fin du XVIe siècle le développement d'un réseau d'écoles primaires et secondaires stable. Ce réseau connut, au XVIIIe siècle, un développement important accompagné d'une modernisation des enseignements que promouvaient pasteurs et administrateurs, à la confluence des influences française et allemande. Le rattachement du pays de Montbéliard à la France durant la Révolution aurait pu modifier cet état de fait. Il montre en réalité que les notables, et notamment les pasteurs, luttèrent pour garder les caractéristiques protestantes de leurs écoles mais qu'ils ne rejetèrent jamais l'apport des réflexions qui s'ébauchaient nationalement. Ils ne refusèrent pas les innovations, nécessaires dans ce pays modifié par une industrialisation déstabilisante, car ils les percevaient comme nécessaires pour conserver leur héritage

National Educational Association Convention at Boston, 1903: La Damnation de Faust

Booklet describing La Damnation de Faust by Hector Berlioz

SFGP 2007 - Investigation of a Novel Principle of Chemical Grafting for Modification of Cellulose Fibers

Natural cellulose fibres have been employed for packaging applications for a long time. Their use, however, has been hampered by their high hydrophilicity and their moisture sensitivity. It has, thus, been proposed to circumvent this problem through the hydrophobic modification of their surface thanks to the use of molecular grafting approaches. In this work, we describe the use of a novel solvent-free chemical pathway for molecular grafting that we have coined chromatogenic chemistry. It involves a reaction between a solid substrate and a reagent which is in a vapour-liquid equilibrium and diffuses within the solid substrate through a mechanism of adsorption/desorption akin to gas chromatography. Chromatogenic chemistry phenomenon has been studied and modelled through the extensive use of a new specific test, the Droplet Surface Migration Test. It involves the deposition upon a porous substrate of a small amount of reagent and in studying its subsequent migration and grafting. Whatman paper and various long chain acid chlorides were used for this modelling. The acid chloride carboxylic ends react with the external hydroxyl groups of cellulose fibres to give rise to the formation of long chain hydrophobic ester bonds. Upon immersion of the paper sheet in distilled water, a hydrophobic spot, extending well over the initial depot zone, could then be clearly visualized, allowing to follow conveniently the reagent migration and reaction. Grafting densities were performed by using the HPLC technique. The results obtained through the use of this test allowed a better understanding of chromatogenic chemistry phenomenon and an identification of the main parameters which affect the process: the nature of the reagent, the temperature, the reaction time, the nature of the substrate, etc. We have more particularly shown that the diffusion and grafting yields were maximal for a specific temperature which increases with the boiling point and therefore with the chain length of the reagents. We have proposed that this temperature should correspond to a compromise between the diffusion and reactivity properties of the reagent, its evaporation and its degradation by hydrolysis

Cool carbon stars in the halo and in dwarf galaxies: Halpha, colours, and variabiity

The population of cool carbon (C) stars located far from the galactic plane is probably made of debris of small galaxies such as the Sagittarius dwarf spheroidal galaxy (Sgr), which are disrupted by the gravitational field of the Galaxy. We aim to know this population better through spectroscopy, 2MASS photometric colours, and variability data. When possible, we compared the halo results to C star populations in the Fornax dwarf spheroidal galaxy, Sgr, and the solar neighbourhood. We first present a few new discoveries of C stars in the halo and in Fornax. The number of spectra of halo C stars is now 125. Forty percent show Halpha in emission. The narrow location in the JHK diagram of the halo C stars is found to differ from that of similar C stars in the above galaxies. The light curves of the Catalina and LINEAR variability databases were exploited to derive the pulsation periods of 66 halo C stars. A few supplementary periods were obtained with the TAROT telescopes. We confirm that the period distribution of the halo strongly resembles that of Fornax, and we found that is it very different from the C stars in the solar neighbourhood. There is a larger proportion of short period Mira/SRa variables in the halo than in Sgr, but the survey for C stars in this dwarf galaxy is not complete, and the study of their variability needs to be continued to investigate the link between Sgr and the cool halo C stars.Comment: 11 pages, 10 figures + one appendix of 26 pages; accepted for publication in Astronomy and Astrophysic

Community and Government Engagement Intern at Catholic Charities

Loyola University of Chicago offers a grant program where undergraduate students are paired with a non-profit organization to develop transferable skills throughout the year. The program allows you to obtain 3 credits for Engaged Learning and contributes students with a $2,000 grant per semester. I had the opportunity of being an intern at Catholic Charities of the Archdiocese of Chicago in the position of Community and Government Engagement. Catholic Charities as an organization, assists with housing, food, case management, and other services to transform the lives of immigrants, and homeless people of all ages. My job has been to retrieve monthly statistics from major projects imparted for immigrants sponsored by 150 parishes across Lake and Cook Counties. I am also a content creator for ongoing events and have assisted in translating documents for the public. I have also cited partnership projects on new development strategies for people who need assistance with their daily living

Completeness of Digital Accessible Knowledge of Plants of Benin and Priorities for Future Inventory and Data Discovery

Discovery of and access to primary biodiversity data are critical components in informed decision-making regarding sustainable use of biological resources and conservation of biodiversity. Primary biodiversity data are increasingly available from Benin, but information about completeness of this information across the country is still lacking for most groups. This study analyzed the Digital Accessible Knowledge regarding the plants of Benin to identify gaps in both geographic and environmental dimensions. Many gaps exist in plant data for Benin, particularly in the northern most departments; central and southern Benin are better known, but some gaps remain even there. The resulting view of Beninese Digital Accessible Knowledge can guide future inventory and data discovery efforts

Título: Marcha húngara

Orgánico: 3[1.2.pic] 2 2 4[2 partes] -- 4 4[2tp, 2crt] 3 1 -- tmp + 4 -- strperc: bd, cym, sd, triDuración: 5Copia digital. España : Ministerio de Cultura y Deporte. Subdirección General de Coordinación Bibliotecaria, s2021Tít. de la carp.: `1. Marcha militar op. 51 ...`Partes: Fl 1, 2, Pic, Ob 1, 2, Cl 1, 2, Bn 1 + 3, 2 + 4, Hn 1, 2, 3, 4, Tp 1, 2, Crt 1, 2, Tbn 1, 2, 3, Tuba, Tmp, Bd + Cym, Sd + TriFaltan las partes de la cuerda