Doru Ursutiu

Distributed virtual and remote labs in engineering

Laboratories are important elements in science, engineering and technical education. They allow the application and testing of theoretical knowledge in practical learning situations. Experimentation and experience-based learning is also performed in many other subject areas, for example in economics where students lead virtual companies and compete on a simulated market. Active learning by means of online laboratories is especially valuable for distance education students and learners in the workplace. They can access the labs without traveling. This flexibility is important for life long learning, because it allows learners in the workplace to fit learning phases into a full work agenda. Using online laboratories has the potential of removing the obstacles of cost, time-inefficient use of facilities, inadequate technical support and limited access to laboratories.

Current-voltage characteristic raising techniques for solar cells. comparisons and applications

Interpreting the current- voltage I–V characteristic of the solar cells gives important information about functional parameters. The paper presents a comparison between the most important techniques of raising the I–V characteristic for solar cells. The improvement realized for raising the characteristic using a capacitor as a load resistance is also presented. A new method to determine the series resistance is developed using the I–V characteristic, and the comparison with the previously methods is also made.

Functionalized Antimicrobial Composite Thin Films Printing for Stainless Steel Implant Coatings

In this work we try to address the large interest existing nowadays in the better understanding of the interaction between microbial biofilms and metallic implants. Our aimed was to identify a new preventive strategy to control drug release, biofilm formation and contamination of medical devices with microbes. The transfer and printing of novel bioactive glass-polymer-antibiotic composites by Matrix-Assisted Pulsed Laser Evaporation into uniform thin films onto 316 L stainless steel substrates of the type used in implants are reported. The targets were prepared by freezing in liquid nitrogen mixtures containing polymer and antibiotic reinforced with bioglass powder. The cryogenic targets were submitted to multipulse evaporation by irradiation with an UV KrF* (λ = 248 nm, τFWHM ≤ 25 ns) excimer laser source. The prepared structures were analyzed by infrared spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy and profilometry, before and after immersion in physiological fluids. The bioactivity and the release of the antibiotic have been evaluated. We showed that the incorporated antibiotic underwent a gradually dissolution in physiological fluids thus supporting a high local treatment efficiency. Electrochemical measurements including linear sweep voltammetry and impedance spectroscopy studies were carried out to investigate the corrosion resistance of the coatings in physiological environments. The in vitro biocompatibility assay using the MG63 mammalian cell line revealed that the obtained nanostructured composite films are non-cytotoxic. The antimicrobial effect of the coatings was tested against Staphylococcus aureus and Escherichia coli strains, usually present in implant-associated infections. An anti-biofilm activity was evidenced, stronger against E. coli than the S. aureus strain. The results proved that the applied method allows for the fabrication of implantable biomaterials which shield metal ion release and possess increased biocompatibility and resistance to microbial colonization and biofilm growth.

The methods to determine the series resistance and the ideality factor of diode for solar cells-review

The most important and accessible methods to determine the series resistance Rs and the ideality factor of the diode, m, for the solar cell are presented in this paper. The values of the two parameters obtained for a monocrystalline silicon solar cell with an area of 9cm2 are also presented comparatively. The measurements were realized using the NI ELVIS platform and the Solar Lab board, developed by the authors.

Multifunction iLab implemented laboratory

This paper introduces a new and flexible Multifunction System. By using LabVIEW 2010 Graphical Programming and or VEE-Pro with the new class of Agilent USB Devices in this application, at the University Transylvania of Brasov was developed a Flexible Laboratory Instrumentation System (FLIS) for new nanostructurated materials. This development offers great benefits to university research laboratories which need flexible systems that can be configured easily, to match the testing needs. At the same time, this FLIS Measurement System can be remotely controlled using MITs iLab Shared Architecture and is providing a uniquely modern, Web-controlled collaborative platform in research and education.

Behavioral models for microwave circuit optimization

Contemporary microwave circuit design is based on EM simulations and complex simulation models. Simulation model design is a must for growing number of devices and systems for which theoretical (e.g., analytical) models are either not available or not sufficiently accurate to yield the design satisfying given performance requirements. As prototype manufacture is very costly, the use of computer simulations has become commonplace as a feasible alternative for manufactures and also for education. Accurate numerical evaluations are computationally expensive; particularly for complex microwave/microstrip structures and computationally efficient EM-driven design optimization can be realized using physically based behavioral models.

Battery lifetime testing using LabVIEW

The use of portable electric devices in a wide range of applications leads to the need for thorough battery testing and selection. This paper presents a system for battery lifetime evaluation using a CompactRIO™ programmable automation controller and a Touch Panel Computer. The LabVIEW™ environment is used for creating different scenarios which simulate the functioning of a battery powered Wi-Fi data acquisition device. The main contribution of this paper is the development of an independent system that measures battery lifetime by simulating the operation of an electronic device powered up by the battery under test. The application was built specially for the case of the Tag4M Wi-Fi device, but it can be used in selecting the appropriate supply for other battery powered portable systems.

FPGA LabVIEW Programming, Monitoring and Remote Control

NI ELVIS is an educational design and prototyping platform from National Instruments Corp. based on NI LabVIEW graphical system design software. The platform is used for teaching concepts in areas such as instrumentation, circuits, control, communication, and embedded design in a hands-on, interactive manner. NI ELVIS contains an integrated suite of the 12 most commonly used instruments â?? DMM, oscilloscope, function generator, MIO, Counter etc - in a compact, rugged, laboratory-friendly form factor. A new instrument, the Digital Electronics FPGA Board has been added to the NI-ELVIS platform in order to help educators teach concepts of FPGA programming. This paper presents an example of graphical FPGA programming and monitoring using the Digital Electronics FPGA Board and LabVIEW FPGA graphical programming..

Using Noise and Fluctuations for In Situ Measurements of Nitrogen Diffusion Depth

In manufacturing processes involving diffusion (of C, N, S, etc.), the evolution of the layer depth is of the utmost importance: the success of the entire process depends on this parameter. Currently, nitriding is typically either calibrated using a “post process” method or controlled via indirect measurements (H2, O2, H2O + CO2). In the absence of “in situ” monitoring, any variation in the process parameters (gas concentration, temperature, steel composition, distance between sensors and furnace chamber) can cause expensive process inefficiency or failure. Indirect measurements can prevent process failure, but uncertainties and complications may arise in the relationship between the measured parameters and the actual diffusion process. In this paper, a method based on noise and fluctuation measurements is proposed that offers direct control of the layer depth evolution because the parameters of interest are measured in direct contact with the nitrided steel (represented by the active electrode). The paper addresses two related sets of experiments. The first set of experiments consisted of laboratory tests on nitrided samples using Barkhausen noise and yielded a linear relationship between the frequency exponent in the Hooge equation and the nitriding time. For the second set, a specific sensor based on conductivity noise (at the nitriding temperature) was built for shop-floor experiments. Although two different types of noise were measured in these two sets of experiments, the use of the frequency exponent to monitor the process evolution remained valid.

RELab - virtual laboratory of the renewable energy

The paper presents a very useful, innovative, compact laboratory, which is simple and complex at the same time. This virtual laboratory covers an important part of the renewable energy: photovoltaic energy, wind energy and solar thermal energy. The SolarLab board and the educational platform NI ELVIS II are the “heart” of the RELab laboratory. The complex software developed in LabVIEW is also presented. ReLAB allows the realization of over thirty lab experiments.