Alexandra Fodor

Thermal management of embedded devices

The presented work analyses the influences that different materials, component placements and other factors have on the efficiency of heat dissipation from the main processing unit of embedded devices. Passive cooling methods are investigated, since these not only require the least space, but also have no need to be powered. It has been shown, with the aid of simulations implemented in SolidWorks, that these devices can be efficiently cooled by an optimal selection of manufacturing materials and using the constructive elements of these devices, such as the EMC shield to draw away heat from components.

An integrated case-based reasoning and ontology-driven approach for designing recommendation systems

Considering the huge amount of available data, the necessity of high-quality recommendation systems is obvious. The complex and diverse definitions of quality make the problem even harder. Although there are several approaches to address the problem of relevant recommendation according to a given context, they still cannot cover all the involved aspects. In our work, we are proposing an integrated approach that enhances the traditional case-based reasoning approach with domain knowledge in order to improve the quality of our similarity metrics. In order to evaluate our model, we developed a proof-of-concept instance in the touristic domain.

Soldering profile optimization for through-hole and surface mounted ceramic capacitors

The paper examines the feasibility of using vapour phase or infrared reflow soldering technologies for multi-layer ceramic chip (MLCC) and disk ceramic capacitors by employing the pin-in-paste technology. During practical experiments recommendations are made for optimizing the thermal profiles used when soldering there types of components in order to minimize the drift in the capacitance and ESR values of these types of capacitors.

Advanced methods of generating signals to command switching converters

This paper presents the implementation of a signal generator using a 12-bit DAC. The applications were developed in LabView software and are used for transposing in a FPGA code sequences for communicating with the DAC and for analytical implementation of the generated signal. For practical implementation of the signal generator the following hardware components were used: Spartan 3E development board and the peripheral module PmodDA2. The waveform of the generated signal is set based on an analytical expression implemented in LabView (with the PC host) using MathScript function. Signal generation is possible by using PmodDA2 module. Infinite discrete sequences form the analog signal, controlled by the software application developed in Labview (the host is Spartan 3E development board).

Investigations of thermal influences on clock speed of embedded devices

This paper analyses the influence of temperature of the CPU of an embedded device, mainly on the application execution time. The study is performed on an AtMega8L microcontroller, placed in a thermal chamber, where different temperatures were set, to show how increasing the temperature can affect the microcontroller speed. Also, several speed configurations were built, using oscillators of 1MHz and 4MHz (internal oscillator) and 4MHz external crystal, in order to better observe the behavior of the studied device. Through experimental work, it has been shown that some configurations are more stable and can be used successfully in most extreme conditions.

Enhancing thermal capabilities of component packaging

Heat transfer from a component to the ambient can be optimized, primarily by reducing the thermal resistance from the main source of heat to the ambient. At package level, reducing thermal resistance can be achieved through adding embedded thermal pads into the package, increasing the number of vias in the packages substrate, and using materials with high thermal capabilities. The research presented in this paper aims to bring further optimizations to component packaging, by showing that making the proper electrical connection inside the IC package can bring improvements to the thermal blueprint of the electronic system.

Simulation and educational tool for fault modelling in logic circuits

Teaching electronic engineering and keeping students interested may sometimes be a challenge, especially for phenomena that rely heavily on a theoretical background. Classical SPICE simulators, although excellent at offering accurate results, rarely offer explanations as to how those results are obtained. This paper presents a novel simulator for modelling logic circuit faults implemented in MathWorks MATLAB which aims not only to provide correct waveforms for the simulated faults, but also let students understand how those results were obtained and what impact they would have in a real-life application of the circuit.

Task allocation for thermal optimization in multicore systems

Power dissipation for processors used in personal computers evolved along the evolution of processor capabilities. Datasheets normally contain the thermal design power (TDP), which is the maximum amount of heat generated by the CPU, which the cooling system in a computer is required to dissipate. The current research above aims to bring a decrease in the total power consumption of a processor, thus decreasing the temperature of the whole computing system, by proposing a task allocation method for multicore systems.

Guidelines on thermal management solutions for modern packaging technologies - a review

Thermal management for modern electronic systems can follow two fundamental paths: one concentrates design efforts towards low power/high efficiency electronic circuits/components, the other implies, where the previous one reaches its limits, optimizing thermal transfer in the entire system at chip level, package level, and PCB/assembly level. Thus, exploring all methods of improving heat transfer at chip/package/assembly levels can generate a guideline for common/specific approach that can be used at the earliest stage of a design. The current research gives an overview of latest packaging technology along with required thermal management measures and proposes a consistent methodology of Design for Thermal Management.

Mathematical model for a quasi-resonant converter

The paper presents a mathematical model for a quasi-resonant converter. This type of converter was analyzed for an induction heating system. The system can have a series or a parallel resonant circuit as a load. In this paper we discussed only series resonant circuit load case.