Impact on spinning discs

The initial local response of a spinning disk subjected to impact is presented to highlight the effect of centrifugal stress. The impact generated deflection falls after reaching a peak unlike in the case of a stationary plate. The peak deflection at a given radius occurs around the time when the membrane wave reaches that location. This paper demonstrates the absorption of impact vibration transients in a spinning disk by the membrane wave action.

General classical theory of spinning particles in a meson field

An exact classical theory of the motion of a point dipole in a meson field is given which takes into account the effects of the reaction of the emitted meson field. The meson field is characterized by a constant $\chi =\mu /\hslash $ of the dimensions of a reciprocal length, $\mu $ being the meson mass, and as $\chi \rightarrow $ 0 the theory of this paper goes over continuously into the theory of the preceding paper for the motion of a spinning particle in a Maxwell field. The mass of the particle and the spin angular momentum are arbitrary mechanical constants. The field contributes a small finite addition to the mass, and a negative moment of inertia about an axis perpendicular to the spin axis. A cross-section (formula (88 a)) is given for the scattering of transversely polarized neutral mesons by the rotation of the spin of the neutron or proton which should be valid up to energies of 10$^{9}$ eV. For low energies E it agrees completely with the old quantum cross-section, having a dependence on energy proportional to p$^{4}$/E$^{2}$ (p being the meson momentum). At higher energies it deviates completely from the quantum cross-section, which it supersedes by taking into account the effects of radiation reaction on the rotation of the spin. The cross-section is a maximum at E $\sim $ 3$\cdot $5$\mu $, its value at this point being 3 $\times $ 10$^{-26}$ cm.$^{2}$, after which it decreases rapidly, becoming proportional to E$^{-2}$ at high energies. Thus the quantum theory of the interaction of neutrons with mesons goes wrong for E $\gtrsim $ 3$\mu $. The scattering of longitudinally polarized mesons is due to the translational but not the rotational motion of the dipole and is at least twenty thousand times smaller. With the assumption previously made by the present author that the heavy partilesc may exist in states of any integral charge, and in particular that protons of charge 2e and - e may occur in nature, the above results can be applied to charged mesons. Thus transversely polarised mesons should undergo a very big scattering and consequent absorption at energies near 3$\cdot $5$\mu $. Hence the energy spectrum of transversely polarized mesons should fall off rapidly for energies below about 3$\mu $. Scattering plays a relatively unimportant part in the absorption of longitudinally polarized mesons, and they are therefore much more penetrating. The theory does not lead to Heisenberg explosions and multiple processes.

Spinning strings and minimal surfaces in AdS(3) with mixed 3-form fluxes

Motivated by the recent proposal for the S-matrix in AdS(3) x S-3 with mixed three form fluxes, we study classical folded string spinning in AdS(3) with both Ramond and Neveu-Schwarz three form fluxes. We solve the equations of motion of these strings and obtain their dispersion relation to the leading order in the Neveu-Schwarz flux b. We show that dispersion relation for the spinning strings with large spin S acquires a term given by -root lambda/2 pi b(2) log(2) S in addition to the usual root lambda/pi log S term where root lambda is proportional to the square of the radius of AdS(3). Using SO(2, 2) transformations and re-parmetrizations we show that these spinning strings can be related to light like Wilson loops in AdS(3) with Neveu-Schwarz flux b. We observe that the logarithmic divergence in the area of the light like Wilson loop is also deformed by precisely the same coefficient of the b(2) log(2) S term in the dispersion relation of the spinning string. This result indicates that the coefficient of b(2) log(2) S has a property similar to the coefficient of the log S term, known as cusp-anomalous dimension, and can possibly be determined to all orders in the coupling lambda using the recent proposal for the S-matrix.

On the non-linear stability theory of spinning solid bodies with liquid-filled cavities and its application to the columbus problem

In this paper, we first present a system of differential-integral equations for the largedisturbance to the general case that any arbitrarily shaped solid body with a cavity contain-ing viscous liquid rotates uniformly around the principal axis of inertia, and then develop aweakly non-linear stability theory by the Lyapunov direct approach. Applying this theoryto the Columbus problem, we have proved the consistency between the theory and Kelvin'sexperiments.

Avaliação das concentrações de BTEX em ambiente indoor: estudo de caso da sala de spinning de uma academia de ginástica Rio de Janeiro / RJ.

Muitos dos locais onde as atividades são realizadas nas academias de ginásticas são salas pequenas e fechadas com sistema de climatização artificial, freqüentados por um grande número de alunos realizando seus exercícios e profissionais auxiliando as atividades. Com isso, há uma intensa transpiração desses indivíduos, uma freqüente rotina de limpeza do piso e de equipamentos com pequenos intervalos, possibilitando a alterações da qualidade do ar indoor. O presente trabalho busca mostrar as tendências de variações nos valores das concentrações dos poluentes atmosféricos BTEX em ambiente indoor, especificamente na sala de spinning de uma academia de ginástica do Rio de Janeiro. Para o monitoramento da qualidade do ar foram utilizados cartuchos de carvão ativado SKC, acoplado a uma bomba KNF com vazão de 1l min. Para a extração de cada amostra foi feita a análise cromatográfica com cromatógrafo a gás modelo 6890 acoplado a um espectrômetro de massa modelo 5973 da marca Agilent. Foram analisadas 34 amostras coletadas na salas de spinning durante as aulas com atividades aeróbicas, o que intensificava a respiração dos indivíduos, possibilitando uma maior inalação destes COVs. Em contrapartida, também foram coletadas 5 amostras outdoor, 4 delas pareadas indoor/ outdoor para uma análise comparativa das concentrações destes poluentes. Dentre os compostos orgânicos voláteis analisados, o tolueno é o BTEX mais abundante obtido neste trabalho, representando 81% destes COVs indoor. Todas as amostras medidas em pares indoor/ outdoor tiveram concentrações maiores no interior, exceto para o benzeno no dia 3/12/2010. Simples atividades usualmente realizadas pelo homem, como a inserção de piso emborrachado, manutenção do sistema de climatização artificial, e limpeza podem alterar o ar indoor. As conclusões alcançadas após as medições das concentrações de BTEX foram de que o ar indoor estava mais poluído do que o outdoor. Este monitoramento da qualidade do ar indoor ainda é escasso no Brasil. Alguns esforços tem sido feito em relação a ambientes confinados como a Portaria n˚3523 do Ministério da Saúde, regulamentando o controle dos ambientes climatizados e a Resolução n˚9 da Agência Nacional de Vigilância Sanitária, além da Resolução CONAMA n ˚3 estabelecendo padrões de qualidade do ar para alguns compostos químicos, porém muitos compostos químicos ainda não são legislados ou não possuem a devida atenção, não sendo suficientes para contemplar a complexidade do assunto

Wet-spinning of amyloid protein nanofibers into multifunctional high-performance biofibers.

Amyloid nanofibers derived from hen egg white lysozyme were processed into macroscopic fibers in a wet-spinning process based on interfacial polyion complexation using a polyanionic polysaccharide as cross-linker. As a result of their amyloid nanostructure, the hierarchically self-assembled protein fibers have a stiffness of up to 14 GPa and a tensile strength of up to 326 MPa. Fine-tuning of the polyelectrolytic interactions via pH allows to trigger the release of small molecules, as demonstrated with riboflavin-5'-phophate. The amyloid fibrils, highly oriented within the gellan gum matrix, were mineralized with calcium phosphate, mimicking the fibrolamellar structure of bone. The formed mineral crystals are highly oriented along the nanofibers, thus resulting in a 9-fold increase in fiber stiffness.

Flexible asymmetric spinning

Metal spinning is used to form shell components, but is constrained by two features: it can only produce axisymmetric shapes; it requires a dedicated mandrel for each product. Examination of pressures between product and mandrel revealed that contact is limited to three well defined areas. This suggested that the full mandrel could be replaced by three rollers. Furthermore, if these rollers could be controlled, they could represent any symmetric or asymmetric mandrel. A seven-axis machine has been designed, manufactured, and used to spin trial parts. The machine design is described, and preliminary results give an indicator of process capability. © 2011 CIRP.

Spinning off a semiconductor company from University premises -The story of Camsemi

The spinning off of Cambridge Semiconductor Ltd (Camsemi) from the High Voltage Microelectronics Lab at Cambridge University is discussed. The technology originated from Cambridge University and was subsequently developed and commercialized as PowerBrane by Camsemi. The paper also discusses the business model and the enabling financial factors that led to the formation of Camsemi as a fables IC company, including access to seed funding from University and the subsequent investments of venture capital in several rounds. © 2011 IEEE.

Azimuthal instabilities in annular combustors: Standing and spinning modes

This theoretical study investigates spinning and standing modes in azimuthally symmetric annular combustion chambers. Both modes are observed in experiments and simulations, and an existing model predicts that spinning modes are the only stable state of the system. We extend this model to take into account the effect that the acoustic azimuthal velocity, u, has on the flames, and propose a phenomenological model based on experiments performed on transversely forced flames. This model contains a parameter, ä, that quantifies the influence that the transversal excitation has on the fluctuating heat release. For small values of ä, spinning modes are the only stable state of the system. In an intermediate range of ä, both spinning and standing modes are stable states. For large values of ä, standing modes are the only stable state. This study shows that a flame's response to azimuthal velocity fluctuations plays an important role in determining the type of thermoacoustic oscillations found in annular combustors. © 2013 The Authors.

Tool-path design for metal spinning

Toolpath design in spinning is an open ended problem, with a large number of solutions, and remains an art acquired by practice. To be able to specify a toolpath without the need for experimental trials, further understanding of the process mechanics Is required. At the moment, the mechanics of the process Is not completely understood, due to the complex deformation and because long solution times required for accurate numerical modelling of the process Inhibit detailed study. This paper proposes and applies a new approach to modelling the process and aims to contribute to the understanding of process mechanics, In particular with respect to the mechanisms of failure and and to apply this understanding for toolpath design In spinning. A new approach to numerical modelling Is proposed and applied to Investigate the process. The findings suggest that there are two different causes and two different modes of wrinkling In spinning, depending on the stage In the process and direction of roller movement. A simple test Is performed to estimate the limits of wrinkling and provide a guideline for toolpath design In a typical spinning process. The results show that the required toolpath geometry in the early stages of the process is different from that In later stages. © 2011 Wiley-VCH Verlag GmbH & Co. KGaA. Weinheim.