Radu Munteanu

Polymer Electrolyte Fuel Cell System (PEFC) Performance Analysis

This paper presents a study of the fuel cell system performance operating at different pressure and temperature levels. A polymer electrolyte fuel cell (PEFC) is analyzed according with the possibility of using in transport applications. Therefore, it begin with the description of a parametric model of the fuel cell which has been developed using a combination between empirical and mathematics modeling techniques. This model enables to simulate fuel cells V-J curves in dependences with the stack temperature and the oxygen partial pressure. In addition, it can be used to study the influence of the gases management (pressure) on the fuel cell stack performances

Quasi-stationary and Transient Regime of Induction Machine Supplied by Two Stator Frequencies

The paper analyzes the behavior of an induction machine having the stator winding fed with two voltages of different frequencies. Usually, this particular operation is exploited in prac ...

IoT system for monitoring vital signs of elderly population

The leading cause of death of elderly Europeans (over 65 years) is heart diseases [1]. Adding up to that, there is also the fact that 30% of elderly people encounter unintentional falls each year, and most of them are fatal [2]. Our paper describes the concept and architecture of a system which is able to monitor the bodys vital signs, pre-process the data, generate emergency alerts and use the power of cloud machine learning to predict medical states.

Embedded platform for Web-based monitoring and control of a smart home

This paper presents the architecture of a low cost embedded platform for Web-based monitoring and control of a smart home. The platform consists of a distributed sensing and control network, devices for access control and a residential gateway with touch-screen display offering an easy to use interface to the user as well as providing remote, Web based access. The key issues related to the design of the proposed platform were addressed: the problem of security, the robustness of the distributed control network to faults and a low cost hardware implementation.

Reliability Indicators and a Failure Mode and Effect Analysis Calculation for a Holter Recorder

Product reliability is very important nowadays, and everyone seeks products that will last very long without failing. It is hard to make a product good and reliable without investing in reliability research from the early stages of the design. This paper presents a reliability analysis for a Holter Recorder for home use, and also a Failure Mode and Effect Analysis using Relex software. This approach can be used for any similar device and helps the manufacturer design a better product.

Study of neural networks to improve performance for character recognition

Three methods are proposed to improve the performance of a system based on feedforward neural networks, that is used for character recognition which are perturbed with noise up to 50%. Have been studied neural networks using backpropagation algorithm. The first element introduced in this study is to train the network in stages, using input data with noise, from 0 to 25% (steps 10,15,20,25) and then from 30% to 40% (steps 30,35,40). This approach has allowed fewer errors up to 1,2% for noise plateau 40%-50%. The second proposed method consists in introducing a vector of stability for the primary information, in stages of network training and then character recognition, with role to reduce the influence of noise on the input data. Stability vector proposed is a linear array with 5 constant parameters. The network used has 35 inputs, 16,20,25,30 or 50 nodes in the hidden layer and 26 outputs (one for each letter). The simulation and experimental results demonstrate that the proposed “vector of stability” can improve performance by decreasing the number of errors up to 1,7% for a neural network with 30 or 50 nodes in hidden layer. The third element proposed is to use reverse information (reverse the bits 0 with 1 and 1 with 0). Have been used two networks that process information. Then their outputs are analyzed and processed by a logic block. With this technique performances have been improved by decreasing the number of errors with 1%, 1.5% and 2.3% for 40%, 45% and 50% noise data.

Model based approach in fault detection and diagnosis for DC motor

Recent advances in microelectronic circuit have enabled the application of process diagnostics to a variety of systems to improve performances and the reliability. Failure detection and isolation strategies monitor a system for degradations and if detected, classify the failure source. One of the most important methods for failure detection and diagnosis is the analysis of the variations of the estimated parameter of DC Motor. In this paper is presented a structure of a method for failure detection and diagnosis based on continuous time parameter estimation of a mathematical model of the DC Motor. Continuous time parameters can be related easily to the physical characterizations of DC Motor. The parameter is directly estimated by well-known prediction error method of identification for dynamic systems. The failure detection it is based on changing the process coefficient and statistical decision methods. Unlike usual papers, the failure can be detected whether others process parameters are not constant.

Agile approach with Kanban in information security risk management

In an ever changing business environment, in order to bring value, security risk management must keep engaged at pace with the company, by following the enterprise goals and using the same methodologies as core business units. This paper analyses how information security risk management can be automated and interlinked with the processes in a software development company, using an Agile approach with Kanban. The methodology used has been tested (Proof of Concept) applying relevant information security risks for an e-commerce business, the results showing an increase in efficiency of the risk management team, better business response and improvements of the defined risk management SLAs (Service Level Agreement).

Reliability indicators analysis for the cam box module of industrial knitting machines

This paper studies the reliability of an industrial knitting machine, emphasizing the reliability value and the reliability indicators: failure rate and MTBF (Mean Time Between Failures). This study has been conducted on an industrial knitting machine and has duration of 4500 hours (approximately 6 months), after which preventive maintenance operations are planned. This study analyses the behavior of the reliability, failure rate and of the MTBF depending on the functioning environment and of the temperature to which the knitting machine was subjected. The last part presents an analysis of the top ten components that are most likely to malfunction.

Modeling and simulation of AC machines behaviour in dynamic operation - critical analysis

In this paper, mathematical models of saturated AC machines are obtained by taking into account the dynamic variation of magnetic saturation. It is shown that various sets of state variables have a common theoretical background that simplifies the derivation of saturated models. Significant data are presented for comparative analysis of different ways to consider saturation in the dynamic operation of AC machines.