Computational representations for multi state design tasks and enumeration of mechanical device behaviour

The role of a computer emerged from modeling and analyzing concepts (ideas) to generate concepts. Research into methods for supporting conceptual design using automated synthesis had attracted much attention in the past decades. To find out how designers synthesize solution concepts for multi-state mechanical devices, ten experimental studies were conducted. Observations from these empirical studies would be used as the basis to develop knowledge involved in the multi-state design synthesis process. In this paper, we propose a computational representation for expressing the multi-state design task and for enumerating multi-state behaviors of kinematic pairs and mechanisms. This computational representation would be used to formulate computational methods for the synthesis process to develop a system for supporting design synthesis of multiple state mechanical devices by generating a comprehensive variety of solution alternatives.

A mechanical device for eradication of submerged aquatic weeds

This paper embodies details and method of operation of a mechanical device developed for eradication of submerged aquatic weeds. The economics of operation is also discussed.

Voltage programmable dual-band bandpass/bandstop filter response in a single micro-electro-mechanical device

This paper reports on a switchable multi-band filter response achieved within a single micro-electro-mechanical device. A prototype device fabricated in a SOI process demonstrates a voltage programmable and tunable, dual-band, band-pass/band-stop response. Both analytical and finite element models are introduced in this paper to elucidate the operating principle of the filter and to guide filter design. Voltage programmability of the filter characteristic is demonstrated with the ability to independently tune the centre frequency and bandwidth for each band. A representative measurement shows that the minimum 3 dB-bandwidth (BW) is 155 Hz, 140Hz, and 20 dB-BW is 216 Hz, 203Hz for the upper-band and lower-band center frequencies located at 131.5 kHz and 130.7 kHz, respectively. © 2011 IEEE.

Investigation of the Design of a Bistable Micro-Chemical-Mechanical Device Utilizing Lateral Buckling

The Gracias Laboratory at Johns Hopkins University has developed microgrippers which utilize chemically-actuated joints to be used in micro-surgery. These grippers, however, take up to thirty minutes to close fully when activated biochemicals in the human body. This is very problematic and could limit the use of the devices in surgery. It is the goal of this research to develop a gripper that uses theGracias Laboratory's existing joints in conjunction with mechanical components to decrease the closing time. The purpose of including the mechanical components is to induce a state of instability at which time a small perturbation would cause the joint to close fully.The main concept of the research was to use the lateral buckling of a triangular gripper geometry and use a toggle mechanism to decrease the closure time of the device. This would create a snap-action device mimicking the quick closure of a Venus flytrap. All developed geometries were tested using finite element analysis to determine ifloading conditions produced the desired buckled shape. This research examines lateral buckling on the micro-scale and the possibility ofusing this phenomenon in a micro-gripper. Although a final geometry with the required deformed shaped was not found, this document contains suggestions for future geometries that may produce the correct deformed shape. It was determined through this work that in order to obtain the desired deformed shape, polymeric sections need to be added to the geometry. This simplifies the analysis and allows the triangular structure to buckle in the appropriate way due to the added joints. Future work for this project will be completed by undergraduate students at Bucknell University. Fabrication and testing of devices will be done at Johns Hopkins University in the Gracias Laboratory.

3D thermo-electro-mechanical simulations of gas sensors based on SOI membranes

3D thermo-electro-mechanical device simulations are presented of a novel fully CMOS-compatible MOSFET gas sensor operating in a SOI membrane. A comprehensive stress analysis of a Si-SiO2-based multilayer membrane has been performed to ensure a high degree of mechanical reliability at a high operating temperature (e.g. up to 400°C). Moreover, optimisation of the layout dimensions of the SOI membrane, in particular the aspect ratio between the membrane length and membrane thickness, has been carried out to find the best trade-off between minimal device power consumption and acceptable mechanical stress.

A novel device to measure acetabular inclination with patients in lateral decubitus

The ability to measure acetabular cup orientation accurately during total hip arthroplasty represents a significant challenge. The aim of this research was to develop and evaluate a novel low cost mechanical device for measuring operative acetabular inclination. Cup implantation was simulated in two trials using the novel device: firstly involving surgeons and engineers orientating acetabular cups with sawbone pelves at a range of inclination angles (20°-55° in 5° increments); secondly in a simulated intra-operative scenario with surgeons. Target angles were compared with achieved angles and deviations from desired angles were recorded. In addition, all participants orientated cups under the same conditions using two other techniques: freehand and with a propriatory Mechanical Alignment Guide. In the first trial, the mean errors (deviations) using freehand technique, the mechanical alignment guide and the new device were 5.2° +/- 4.3° (range 0.1-22.0), 3.6° +/- 3.9° (range 0.1°-33.6°) and 0.5° +/- 0.4° (range 0.0-1.9) respectively. In the second trial, the mean error for freehand technique, mechanical alignment guide and the new device were 6.2° +/- 4.2° (range 0.2-18.2), 3.8° +/- 3.3° (range 0.0-19.1) and 0.6° +/- 0.5° (range 0.0-1.8) respectively. The new device has the potential to allow the surgeon to choose and record operative inclination accurately during total hip arthroplasty in the lateral decubitus position.

A mechanical analogous model for the power system with Automatic Voltage Regulator

This paper deals with the subject-matter of teaching immaterial issues like power system dynamics where the phenomena and events are not sense-perceptible. The dynamics of the power system are recognized as analogous to the dynamics of a simple mechanical pendulum taken into account the well-known classical model for the synchronous machine. It is shown that even for more sophisticated models including flux decay and Automatic Voltage Regulator the mechanical device can be taken as an analogous, since provided some considerations about variation and control of the pendulum length using certain control laws. The resulting mathematical model represents a mechanical system that can be built for use in laboratory teaching of power system dynamics. © 2010 Praise Worthy Prize S.r.l. - All rights reserved.

An Empirical Study of Synthesis of Multiple State Devices by Engineering Designers

Automated synthesis of mechanical designs is an important step towards the development of an intelligent CAD system. Research into methods for supporting conceptual design using automated synthesis has attracted much attention in the past decades. The research work presented here is based on an empirical study of the process of synthesis of multiple state mechanical devices. As a background to the work, the paper explores concepts of what mechanical device, state, single state and multiple state are, and in the context of the above observational studies, attempts to identify the outstanding issues for supporting multiple state synthesis of mechanical devices.

Diseño y evaluación de métodos de supresión del artefacto causado en el ECG por las compresiones torácicas proporcionadas por el dispositivo mecánico LUCAS.

[Es]En este proyecto se analizan el diseño y la evaluación de dos métodos para la supresión de la interferencia generada por las compresiones torácicas proporcionadas por el dispositivo mecánico LUCAS, en el electrocardiograma (ECG) durante el masaje de resucitación cardiopulmonar. El objetivo es encontrar un método que elimine el artefacto generado en el ECG de una manera efectiva, que permita el diagnóstico fiable del ritmo cardiaco. Encontrar un método eficaz sería de gran ayuda para no tener que interrumpir el masaje de resucitación para el análisis correcto del ritmo cardiaco, lo que supondría un aumento en las probabilidades de resucitación. Para llevar a cabo el proyecto se ha generado una base de datos propia partiendo de registros de paradas cardiorrespiratorias extra-hospitalarias. Esta nueva base de datos contiene 410 cortes correspondientes a 86 pacientes, siendo todos los episodios de 30 segundos de duración y durante los cuales el paciente, recibe masaje cardiaco. Por otro lado, se ha desarrollado una interfaz gráfica para caracterizar los métodos de supresión del artefacto. Esta, muestra las señales del ECG, de impedancia torácica y del ECG tras eliminar el artefacto en tiempo. Mediante esta herramienta se han procesado los registros aplicando un filtro adaptativo y un filtro de coeficientes constantes. La evaluación de los métodos se ha realizado en base a la sensibilidad y especificidad del algoritmo de clasificación de ritmos con las señales ECG filtradas. La mayor aportación del proyecto, por tanto, es el desarrollo de una potente herramienta eficaz para evaluar métodos de supresión del artefacto causado en el ECG por las compresiones torácicas al realizar el masaje de resucitación cardiopulmonar, y su posterior diagnóstico. Un instrumento que puede ser implementado para analizar episodios de resucitación de cualquier tipo de procedencia y capaz de integrar nuevos métodos de supresión del artefacto.

Passive suspensions incorporating inerters for railway vehicles

This paper investigates the possibility of improving the performance of railway vehicle suspensions by incorporating a newly developed mechanical device known as the inerter. A comparative study of several low-complexity passive suspension layouts is made. Improved performance for the lateral and vertical ride comfort, as well as lateral body movement when curving are demonstrated in comparison with the conventional suspension layout. The constraints imposed are to maintain the same level of other performance metrics. The calculations and optimisations are based on linearised plan-view and side-view high-speed train mathematical models. © 2012 Copyright Taylor and Francis Group, LLC.

Stability control of a railway vehicle using absolute stiffness and inerters

Work presented in this paper studies the potential of employing inerters -a novel mechanical device used successfully in racing cars- in active suspension configurations with the aim to enhance railway vehicle system performance. The particular element of research in this paper concerns railway wheelset lateral stability control. Controlled torques are applied to the wheelsets using the concept of absolute stiffness. The effects of a reduced set of arbitrary passive structures using springs, dampers and inerters integrated to the active solution are discussed. A multi-objective optimisation problem is defined for tuning the parameters of the proposed configurations. Finally, time domain simulations are assessed for the railway vehicle while negotiating a curved track. A simplification of the design problem for stability is attained with the integration of inerters to the active solutions. © 2012 IEEE.

Granular Attrition due to Rotary Valve in a Pneumatic Conveying System

The rotary valve is a widely used mechanical device in many solids-handling industrial processes. However, it may also be responsible for most of the attrition effects occurring in a typical process. In this study, the attrition effects occurring in a rotary valve operating as a stand-alone device and as part of a pneumatic conveying system were investigated. In the former case granular attrition was carried out at three different rotary valve speeds and the experimental results obtained were found to be in good agreement with the Gwyn correlation. In the latter case three typical air flow rates were used in the pneumatic conveying system. The size distribution of the attrition product obtained at the lowest air flow rate used was not adequately described by the Gwyn correlation. The attrition process and mechanisms involved were analysed and the minimum size of the attrition product obtained from both modes of operations was found to be similar.

A modular head/eye platform for real-time reactive vision

This paper describes the design, implementation and testing of a high speed controlled stereo “head/eye” platform which facilitates the rapid redirection of gaze in response to visual input. It details the mechanical device, which is based around geared DC motors, and describes hardware aspects of the controller and vision system, which are implemented on a reconfigurable network of general purpose parallel processors. The servo-controller is described in detail and higher level gaze and vision constructs outlined. The paper gives performance figures gained both from mechanical tests on the platform alone, and from closed loop tests on the entire system using visual feedback from a feature detector.

A interatividade na aprendizagem: uma perspectiva cognitiva utilizando conteúdo multimídia

A migração de materiais educacionais para dispositivos portáteis, tais como computadores do tipo tablet, torna possível oferecer altos níveis de interatividade na apresentação de animações e, dessa forma, pesquisas são necessárias para avaliar o valor pedagógico de incorporar recursos sofisticados de interatividade em lições para dispositivos portáteis. Estudantes de Engenharia (no Experimento 1) e estudantes de nível superior de outras áreas (no Experimento 2) estudaram por 5 minutos uma animação mostrando, em um computador do tipo tablet, os seis passos de um procedimento de manutenção para um dispositivo mecânico chamado Tomada de Força. A animação envolveu um baixo nível de interatividade, no qual os estudantes eram capazes de reproduzir, pausar, avançar e voltar a animação por meio de botões acionados em tela sensível ao toque (touch screen); um alto nível de interatividade, no qual os estudantes podiam também tocar e deslizar um dedo na tela para rotacionar a animação ou ainda tocar a tela com dois dedos abrindo-os ou fechando-os para ampliar ou reduzir a animação; ou nenhuma interatividade (apenas no Experimento 2). De forma geral, em ambos os experimentos, os estudantes que utilizaram alto nível de interatividade reportaram maior interesse, mas não mostraram melhor aprendizagem, comparados aos grupos de baixa ou nenhuma interatividade. Entretanto, no Experimento 2, estudantes que se classificaram como alunos verbais demonstraram maior interesse e obtiveram pontuações mais altas de aprendizagem com alta interatividade, em vez de baixa ou nenhuma interatividade. Esse padrão, contudo, não foi encontrado entre os alunos visuais. Também no Experimento 2, os alunos verbais e os alunos com baixo nível de autorregulação de aprendizagem, que manifestaram alto nível de interesse, obtiveram pontuações mais altas de aprendizagem do que os alunos visuais e os alunos com alto nível de autorregulação de aprendizagem, que manifestaram baixo nível de interesse, respectivamente.