Stepping-motor-driven constant-shear-rate rotating viscometer

Despite the frequent use of stepping motors in robotics, automation, and a variety of precision instruments, they can hardly be found in rotational viscometers. This paper proposes the use of a stepping motor to drive a conventional constant-shear-rate laboratory rotational viscometer to avoid the use of velocity sensor and gearbox and, thus, simplify the instrument design. To investigate this driving technique, a commercial rotating viscometer has been adapted to be driven by a bipolar stepping motor, which is controlled via a personal computer. Special circuitry has been added to microstep the stepping motor at selectable step sizes and to condition the torque signal. Tests have been carried out using the prototype to produce flow curves for two standard Newtonian fluids (920 and 12 560 mPa (.) s, both at 25 degrees C). The flow curves have been obtained by employing several distinct microstep sizes within the shear rate range of 50-500 s(-1). The results indicate the feasibility of the proposed driving technique.

Desenvolvimento de um sistema de análise de imagem para quantificação do tamanho e distribuição de partículas de desgaste

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Projeto mecânico do sistema de transmissão de um veículo Baja

This study aims to determine the best configuration for the new gearbox of the new Baja´s vehicle from Piratas do Vale team, focusing on the gear train, in order to achieve high performance of it. To this end, first some information about the vehicle is gathered to determine the best pair of gears configuration, then calculations about maximum bending stress, fatigue and surface thereof are performed; ; thereafter static simulations are performed using an a appropriated software. Thus this paper shows a satisfactory design of the addressed, besides providing the Baja SAE team consultation material for future use in the project

Uma análise da eficiência de uma transmissão CVT

This undergraduate thesis evaluates the effects of temperature variation of the air inside the CVT gearbox on the performance of a Continuously Variable Transmission (CVT). The CVT used in the tests was manufactured by Gaged Engineering (GX9 model) and is currently used in a Baja prototype. It’s a mechanically operated CVT, which the movement of the pulley plates varies according to the drive shaft rotation, shifting the belt along the diameter, and varying the transmission ratio. The purpose of this work is to analyze the change in the slip factor, coefficient that compares the variation between the actual transmission ratio and the ratio of geometric transmission, and its correlation with the power variation. A test bench was built and some tests were performed, indicating that was possible to achieve output power ratios of 1.75 [ℎ

Projeto mecânico de um redutor de engrenagens sem-fim numa esteira transportadora inclinada

This work aims to present the design and development of a speed reducer worm gear that will be implemented on an inclined treadmill that aims to raise the load below the top floor. The project start was made with research on issues related to mechanisms and machine elements, and these theories of fundamental importance in the development of device components, along with the help of SolidWorks software that was used to model the main parts of the project and Microsoft Office Excel 2007 was used to alight formulas to perform calculations of the project. All data for calculations were taken from the conditions of the problem to be solved in the best possible way the proposed problem (lifting load from the belt). Following the entire sequence of design gearbox assembly, beginning in pre-sizing and endless selection of electric motor, which consists of an iterative project, then scaling the worm gear and crown, shafts, splines, calculation and bearing selection

Desenvolvimento de uma caixa de redução para veículo Baja SAE

A gear Box in a Baja SAE vehicle is required due to the objectives of the SAE competitions, which the vehicles are challenged to pass through different obstacles. A powertrain system has as the main objective the extension of the torque for the traction shaft of the vehicle, when compared to that one available in the engine. The Objective of this thesis is the description of a gear box project for a Baja SAE vehicle of the Piratas do Vale Team of Unesp Guaratinguetá. In the development of the thesis, a flowchart, developed by the team, was used, which includes a theory part and also the choice of shelf components. In this Project, the type of gearbox was chosen, besides the calculation of axles, gears, bearings and sealers, and software simulations were done for the critical parts. The transmission, developed in this thesis, is more complex than the current one used by the team, but the new one shows improvements, as a new reverse gear with high torque

Concepção de um dispositivo fisioterápico: parapodium mecanizado

This paper presents a proposal to redesign a physical therapy device for patients with quadriplegia, called parapodium. With the help of the Association of Parents and Exceptional Friends of Guaratinguetá, it was possible to know the currently used device and from this it was conceived changes, allowing the increase of freedom of its central portion, in the down and across positions with mechanical drive . This adaptation is to introduce improvements in the routine of physical therapy professionals and reduce ergonomic problems resulting from repetitive strain during the transfer of patients to the parapodium. In addition to providing greater security for patients who require the use of this equipment. The proposed device comprises: wheel, gearbox and brake systems used for actuation, allowing a degree of turning of the rear post, along an axis which is fixed to the gearbox and the rear structure that permits posterior movement. The mechanism allows the rear post rotate from 0 ° to 90 °. The estimated cost to make the proposal is lower than the marketed parapodiuns, reaching the device's functional expectations

Desenvolvimento de uma caixa de redução para veículo Baja SAE

A gear Box in a Baja SAE vehicle is required due to the objectives of the SAE competitions, which the vehicles are challenged to pass through different obstacles. A powertrain system has as the main objective the extension of the torque for the traction shaft of the vehicle, when compared to that one available in the engine. The Objective of this thesis is the description of a gear box project for a Baja SAE vehicle of the Piratas do Vale Team of Unesp Guaratinguetá. In the development of the thesis, a flowchart, developed by the team, was used, which includes a theory part and also the choice of shelf components. In this Project, the type of gearbox was chosen, besides the calculation of axles, gears, bearings and sealers, and software simulations were done for the critical parts. The transmission, developed in this thesis, is more complex than the current one used by the team, but the new one shows improvements, as a new reverse gear with high torque

Concepção de um dispositivo fisioterápico: parapodium mecanizado

This paper presents a proposal to redesign a physical therapy device for patients with quadriplegia, called parapodium. With the help of the Association of Parents and Exceptional Friends of Guaratinguetá, it was possible to know the currently used device and from this it was conceived changes, allowing the increase of freedom of its central portion, in the down and across positions with mechanical drive . This adaptation is to introduce improvements in the routine of physical therapy professionals and reduce ergonomic problems resulting from repetitive strain during the transfer of patients to the parapodium. In addition to providing greater security for patients who require the use of this equipment. The proposed device comprises: wheel, gearbox and brake systems used for actuation, allowing a degree of turning of the rear post, along an axis which is fixed to the gearbox and the rear structure that permits posterior movement. The mechanism allows the rear post rotate from 0 ° to 90 °. The estimated cost to make the proposal is lower than the marketed parapodiuns, reaching the device's functional expectations

Sulla energia dissipata in alcuni organi di macchina

Questa tesi riguarda l'analisi delle trasmissioni ad ingranaggi e delle ruote dentate in generale, nell'ottica della minimizzazione delle perdite di energia. È stato messo a punto un modello per il calcolo della energia e del calore dissipati in un riduttore, sia ad assi paralleli sia epicicloidale. Tale modello consente di stimare la temperatura di equilibrio dell'olio al variare delle condizioni di funzionamento. Il calcolo termico è ancora poco diffuso nel progetto di riduttori, ma si è visto essere importante soprattutto per riduttori compatti, come i riduttori epicicloidali, per i quali la massima potenza trasmissibile è solitamente determinata proprio da considerazioni termiche. Il modello è stato implementato in un sistema di calcolo automatizzato, che può essere adattato a varie tipologie di riduttore. Tale sistema di calcolo consente, inoltre, di stimare l'energia dissipata in varie condizioni di lubrificazione ed è stato utilizzato per valutare le differenze tra lubrificazione tradizionale in bagno d'olio e lubrificazione a “carter secco” o a “carter umido”. Il modello è stato applicato al caso particolare di un riduttore ad ingranaggi a due stadi: il primo ad assi paralleli ed il secondo epicicloidale. Nell'ambito di un contratto di ricerca tra il DIEM e la Brevini S.p.A. di Reggio Emilia, sono state condotte prove sperimentali su un prototipo di tale riduttore, prove che hanno consentito di tarare il modello proposto [1]. Un ulteriore campo di indagine è stato lo studio dell’energia dissipata per ingranamento tra due ruote dentate utilizzando modelli che prevedano il calcolo di un coefficiente d'attrito variabile lungo il segmento di contatto. I modelli più comuni, al contrario, si basano su un coefficiente di attrito medio, mentre si può constatare che esso varia sensibilmente durante l’ingranamento. In particolare, non trovando in letteratura come varia il rendimento nel caso di ruote corrette, ci si è concentrati sul valore dell'energia dissipata negli ingranaggi al variare dello spostamento del profilo. Questo studio è riportato in [2]. È stata condotta una ricerca sul funzionamento di attuatori lineari vite-madrevite. Si sono studiati i meccanismi che determinano le condizioni di usura dell'accoppiamento vite-madrevite in attuatori lineari, con particolare riferimento agli aspetti termici del fenomeno. Si è visto, infatti, che la temperatura di contatto tra vite e chiocciola è il parametro più critico nel funzionamento di questi attuatori. Mediante una prova sperimentale, è stata trovata una legge che, data pressione, velocità e fattore di servizio, stima la temperatura di esercizio. Di tale legge sperimentale è stata data un'interpretazione sulla base dei modelli teorici noti. Questo studio è stato condotto nell'ambito di un contratto di ricerca tra il DIEM e la Ognibene Meccanica S.r.l. di Bologna ed è pubblicato in [3].

Energy harvesting from body motion using rotational micro-generation

Autonomous system applications are typically limited by the power supply operational lifetime when battery replacement is difficult or costly. A trade-off between battery size and battery life is usually calculated to determine the device capability and lifespan. As a result, energy harvesting research has gained importance as society searches for alternative energy sources for power generation. For instance, energy harvesting has been a proven alternative for powering solar-based calculators and self-winding wristwatches. Thus, the use of energy harvesting technology can make it possible to assist or replace batteries for portable, wearable, or surgically-implantable autonomous systems. Applications such as cardiac pacemakers or electrical stimulation applications can benefit from this approach since the number of surgeries for battery replacement can be reduced or eliminated. Research on energy scavenging from body motion has been investigated to evaluate the feasibility of powering wearable or implantable systems. Energy from walking has been previously extracted using generators placed on shoes, backpacks, and knee braces while producing power levels ranging from milliwatts to watts. The research presented in this paper examines the available power from walking and running at several body locations. The ankle, knee, hip, chest, wrist, elbow, upper arm, side of the head, and back of the head were the chosen target localizations. Joints were preferred since they experience the most drastic acceleration changes. For this, a motor-driven treadmill test was performed on 11 healthy individuals at several walking (1-4 mph) and running (2-5 mph) speeds. The treadmill test provided the acceleration magnitudes from the listed body locations. Power can be estimated from the treadmill evaluation since it is proportional to the acceleration and frequency of occurrence. Available power output from walking was determined to be greater than 1mW/cm³ for most body locations while being over 10mW/cm³ at the foot and ankle locations. Available power from running was found to be almost 10 times higher than that from walking. Most energy harvester topologies use linear generator approaches that are well suited to fixed-frequency vibrations with sub-millimeter amplitude oscillations. In contrast, body motion is characterized with a wide frequency spectrum and larger amplitudes. A generator prototype based on self-winding wristwatches is deemed to be appropriate for harvesting body motion since it is not limited to operate at fixed-frequencies or restricted displacements. Electromagnetic generation is typically favored because of its slightly higher power output per unit volume. Then, a nonharmonic oscillating rotational energy scavenger prototype is proposed to harness body motion. The electromagnetic generator follows the approach from small wind turbine designs that overcome the lack of a gearbox by using a larger number of coil and magnets arrangements. The device presented here is composed of a rotor with multiple-pole permanent magnets having an eccentric weight and a stator composed of stacked planar coils. The rotor oscillations induce a voltage on the planar coil due to the eccentric mass unbalance produced by body motion. A meso-scale prototype device was then built and evaluated for energy generation. The meso-scale casing and rotor were constructed on PMMA with the help of a CNC mill machine. Commercially available discrete magnets were encased in a 25mm rotor. Commercial copper-coated polyimide film was employed to manufacture the planar coils using MEMS fabrication processes. Jewel bearings were used to finalize the arrangement. The prototypes were also tested at the listed body locations. A meso-scale generator with a 2-layer coil was capable to extract up to 234 µW of power at the ankle while walking at 3mph with a 2cm³ prototype for a power density of 117 µW/cm³. This dissertation presents the analysis of available power from walking and running at different speeds and the development of an unobtrusive miniature energy harvesting generator for body motion. Power generation indicates the possibility of powering devices by extracting energy from body motion.

Determinação analítica da correção de hélice em um par engrenado devido ao efeito da flexo-torção.

O foco do presente trabalho é estudar a intensificação da pressão de contato entre os dentes de duas engrenagens cilíndricas de dentes retos, que ocorre por causa do deslocamento dos componentes de um redutor de velocidades. Essa intensificação ocorre inclusive em um redutor fabricado sem quaisquer erros de usinagem ou de montagem. A correção de hélice é uma usinagem realizada na superfície do dente da engrenagem que compensa os deslocamentos dos eixos e engrenagens, devido à flexão e à torção, e os deslocamentos dos dentes das engrenagens, devido à flexão e à pressão de contato. Foram estudados efeitos importantes para essa correção de hélice em um redutor de velocidades. Com isso, foi desenvolvido um modelo analítico que calcula a correção necessária para diminuir esse intensificador de pressão de contato em função dos deslocamentos citados acima. Esse modelo analítico foi comparado com um modelo analítico da literatura e com o software comercial RIKOR®. Os resultados de correção de hélice propostos são similares aos da literatura e do RIKOR® com exceção das bordas das engrenagens, aonde existem algumas divergências. Posteriormente, foi desenvolvido um modelo sólido de engrenagem com o perfil evolvente e com as correções de hélice calculadas analiticamente. Este modelo tridimensional (3D) foi elaborado usando os softwares SolidWorks® e Inventor® e simulado por elementos finitos por meio do software ANSYS®. Verificou-se que as três correções de hélice - a proposta, a da literatura e a do RIKOR® - realmente diminuem a intensificação de pressão de contato no flanco do dente da engrenagem. Por fim, foi possível visualizar que a correção proposta nesta dissertação é 3% mais efetiva que a proposta pela literatura e pelo RIKOR® para o caso analisado.

EU enlargement to the Balkans: will the leopard change its spots? EPC Commentary, 29 September 2014

As the leadership of the European Union hands over the baton to a new management this autumn, will the winds of change blow also through the cobwebs of the EU’s enlargement agenda? Jean-Claude Juncker – the incoming President of the European Commission – has already promised to put the gearbox of further EU widening in neutral for the next five years of his mandate, and has designated the Austrian Johannes Hahn as Commissioner for the re-baptised portfolio of now European Neighbourhood Policy and Enlargement Negotiations, instructing him to focus on the Union’s political and economic ties with Southern and Eastern Europe, and in particular with the Balkans. Such an approach in the field of enlargement – once crowned the jewel of EU foreign policy – has all the appeal of a damp rag but does not necessarily depart from the festina lente strategy of the recent past. Inside the Union, political appetite and public support for expansion have been fizzling since Bulgaria and Romania joined in 2007, and were then severely curbed in the context of the on-going crisis by growing fears of importing organised crime and migrants from the Balkans. Juncker’s logic of consolidation sounds depressingly similar to what it supposedly replaces and incidentally, it also fits neatly with the unambitious and inward-looking mantra favoured at present in discussions at all levels on the future of European integration, more generally. With the 28-member block determined to catch its breath in the immediate time period, and given that even the forerunner countries in the Balkans – that is, Montenegro and Serbia – will realistically need more than five years to complete their accession talks, what priorities should guide Commissioner Hahn, soon to be Directorate-General for Neighbourhood and Enlargement Negotiations – when they get down to business on 1 November?

Control and Supervision of Wind Energy Conversion Systems

This paper is about a PhD thesis and includes the study and analysis of the performance of an onshore wind energy conversion system. First, mathematical models of a variable speed wind turbine with pitch control are studied, followed by the study of different controller types such as integer-order controllers, fractional-order controllers, fuzzy logic controllers, adaptive controllers and predictive controllers and the study of a supervisor based on finite state machines is also studied. The controllers are included in the lower level of a hierarchical structure composed by two levels whose objective is to control the electric output power around the rated power. The supervisor included at the higher level is based on finite state machines whose objective is to analyze the operational states according to the wind speed. The studied mathematical models are integrated into computer simulations for the wind energy conversion system and the obtained numerical results allow for the performance assessment of the system connected to the electric grid. The wind energy conversion system is composed by a variable speed wind turbine, a mechanical transmission system described by a two mass drive train, a gearbox, a doubly fed induction generator rotor and by a two level converter.