Kinematic Model for Project Scheduling with Constrained Resources Under Uncertainties

Project management practitioners and researchers recognize that the project scheduling efforts are made based on information with many uncertainties and in an environment with constrained resources. This chapter presents the kinematic model named as Coupled Estimate Technique for project scheduling with constrained resources under uncertainties. The Coupled Estimate Technique provides tools of analytical analysis, given that the modelled duration depends on the planned duration and on the resource variability (aleatory uncertainty), as well as the modelled resource depends on the planned resource and on the duration variability (aleatory uncertainty), and also provides tools of graphical analysis, given that the durations and resources of activities, work packages or phases of the project are represented in the bidimensional graphics. In developing the mathematical formulation of the Coupled Estimate Technique, the project precedence diagram was considered as a kinematic chain of robotic manipulators, which may be in chain configuration open (serial), closed (parallel) and/or hybrid. This chapter describes the resource-constrained project scheduling problem (RCPSP) under uncertainties, identifies the limitations and opportunities in the previous work on planning under uncertainties and presents the fundamentals and method of the kinematic model for project scheduling with constrained resources under uncertainties along with a short example of implementation

ANALYSIS OF THREE-PHASE SVPWM MICROCONTROLLED INVERTER WITH FOCUS ON HARMONICS GENERATION

This work presents SVPWM modulation technique concepts in a simple and direct way, aiming at the level of harmonics generated measurement, in order to evaluate its performance and to compare with another method of modulation widely used and known as SPWM. It also presents the generation algorithm, implemented and simulated in an 8-bit microcontroller. PWM is a technique used by inverters to control induction motors, aiming to control rotation and torque. Several techniques have been developed, the most famous being SPWM, due to its simplicity and performance, and the most recent being SVPWM, which has gained the confidence and preference of designers, mainly due to its performance characteristics. A bibliographic study was necessary to implement the SVPWM with simulations in EXCEL, PSIM, MATHLAB and PROTEUS for a better understanding of the algorithm concepts and construction. Performances of SPWM and SVPWM modulations were evaluated under the same conditions in harmonics generation, by total harmonic distortion measurement, and the SVPWM method presented better results. On the other end, by increasing the number of vectors, this technique may be impracticable when acting with low cost conventional microprocessors. In both techniques, inverters dead times were realized in hardware, by dedicated integrated circuits, so that, besides avoiding crossed conductions, they didn´t influence distortions

Low-Cost PWM Speed Controller for an Electric Mini-Baja Type Vehicle

The main purpose for using electric vehicles (EVs), as opposed to internal-combustion cars, is that they are zero gas-emission vehicles. Besides not giving off carbon dioxide to the atmosphere, which is one of the main causes for air pollution in metropolitan areas, EV

Aplicação do GRAFCET na redução do retrabalho de uma linha de pintura automotiva

Na área de pintura, em geral, o maior problema encontrado no processo de aplicação é a quantidade de impurezas sobre a superfície de trabalho. As empresas fazem muitos investimentos para eliminar este problema que, em muitas vezes, é invisível ao olho humano. Inicialmente, procurou-se mapear e identificar as áreas com maior sujidade na planta estudada. Encontraram-se cabines com boas condições para aplicação, porém, a parte exterior da cabine possuía outras fontes contamináveis, como o próprio ar (devido ao sistema de filtragem) e as poeiras, ambas geradas pelo processo. Este trabalho apresenta um sistema de filtragem de ar na área de pintura, o sistema de limpeza das carrocerias e a proposta de implementação de uma cortina de ar automatizada para limpeza das carrocerias na área de pintura. Nesta cortina, desenvolveu-se um sistema de automação em que é possível gerar a trajetória para cada tipo de veículo, levando em consideração a sua silhueta. O programa para o funcionamento da cortina foi implementado em linguagem “Ladder”; o programa para o cálculo da trajetória foi implementado em linguagem “C” e a descrição do funcionamento foi realizado utilizando o diagrama de blocos GRAFCET, o que permitiu a verificação de cada etapa do funcionamento da cortina. Sensores ópticos são utilizados para garantir a segurança do sistema quando este estiver em funcionamento. Ensaios, realizados com simulação de limpeza em placas, comprovaram a eficiência do sistema

Modeling of a MIT for the application of a frequency inverter of the electric vehicle

Nowadays, drives that use a combination of induction motors and frequency inverters are very common, a fact due to the financial practicality and viability in purchasing and operating that system. This system modeling and simulation becomes important when it wants to evaluate the performance, to calculate and correct parameters, and it has a fundamental role in functionality and viability analysis for application of new configurations and technologies. This work is about to elaborate a simple induction motor model based in the torque versus speed characteristic, using the linearization method for application in a specific operation range to be controlled by a frequency inverter. © 2011 Springer-Verlag Berlin Heidelberg

An ultracapacitor-based no-break system for microcomputers

This work aims at presenting a no-break system for microcomputers using ultracapacitors in replacement of the conventional chemical batteries. We analyzed the most relevant data about average power consumption of microcomputers, electrical and mechanical characteristics of ultracapacitors and operation of no-break power circuits, to propose a configuration capable of working properly with a microcomputer switching mode power supply. Our solution was a sixteen-component ultracapacitor bank, with a total capacitance of 350 F and voltage of 10.8 V, adequate to integrate a low-capacity no-break system, capable of feeding a load of 180 Wh, during 75 s. Our proposed no-break increases the reliability of microcomputers by reducing the probability of user data losses, in case of a power grid failure, offering, so, a high benefit-cost ratio. The replacement of the battery by ultracapacitors allows a quick no-break recharge and low maintenance costs, since these modern components have a lifetime longer than the batteries. Moreover, this solution reduces the environmental impact and eliminates the constant recharge of the energy storage device

Notes on vibration control of a micro/macromanipulator mounted on a flexible structure

The objective of this study is to describe the design and the implementation of an experimental set-up used to study the dynamics, the experimental identification, and the active vibration control of a flexible structure mounted manipulator system. The system consists of a three-degree-of-freedom cylindrical manipulator system with a flexible link on its tip. A two-degree-of-freedom polar rigid manipulator is mounted on the flexible macromanipulator. The dynamic modelling and experimental modal analysis identification in the frequency domain are being applied to design active digital control strategies for the micro-manipulator system to damp the mechanical vibrations of the flexible structure on the tip of the macro-manipulator system

Numerical modelling and simulation of multi-phase flow through an industrial discharge chute

Made available in DSpace on 2019-09-12T16:53:32Z (GMT). No. of bitstreams: 0 Previous issue date: 2017Computational fluid dynamics simulations have been employed in many engineering applications to improve machines and processes. In this study, CFD is used to analyse the effect of geometrical modifications of a discharge chute in the performance of a drying process of silica (SiO2) and water (H2O) compound. Multi-phase flow simulations were carried on to study the gas-solid flow inside discharge chute to determine internal pressure, velocity and temperature of the flow. The results for the modified geometry show a reduction in the flow velocity and in the pressure that can increase the flow rate of the compound and reduce material's sedimentation. The simple geometric modification of the discharge chute proposed in this study might reduce maintenance and lead to production efficiency gains. (C) 2017 Elsevier Ltd. All rights reserved.[Lamas, Wendell de Queiroz; Bargos, Fabiano Fernandes] Univ Sao Paulo, Lorena Sch Engn, Dept Basic & Environm Sci, BR-12602810 Lorena, SP, Brazil[Oscare Giacaglia, Giorgio Eugenio; Grandinetti, Francisco José; de Moura, Leandro] Universidade de Taubaté (Unitau), Dept Mech Engn, Postgrad Programme Mech Engn, BR-12060440 Taubate, SP, Brazi