Biblio

A Unique Object (UNO) is a physical object with unique characteristics that can be measured externally. The usually analogue measurement can be converted into a digital representation - a fingerprint - which uniquely identifies the object. For practical applications it is necessary that measurements can be performed without the need of specialist equipment or complex measurement setup. Furthermore, a UNO should be able to defeat simulation attacks; an attacker may replace the UNO with a device or system that produces the expected measurement. Recently a novel type of UNOs based on Quantum Dots (QDs) and exhibiting unique photo-luminescence properties has been proposed. The uniqueness of these UNOs is based on quantum effects that can be interrogated using a light source and a camera. The so called Quantum Confinement UNO (QCUNO) responds uniquely to different light excitation levels which is exploited for simulation attack protection, as opposed to focusing on features too small to reproduce and therefore difficult to measure. In this paper we describe methods for extraction of fingerprints from the QCUNO. We evaluate our proposed methods using 46 UNOs in a controlled setup. Focus of the evaluation are entropy, error resilience and the ability to detect simulation attacks.

A semi-analytical model for internal optical losses at high power in a 1.5 μm laser diode with strong n-doping in the n-side of the optical confinement layer is created. The model includes intervalence band absorption by holes supplied by both current flow and two-photon absorption. The resulting losses are shown to be substantially lower than those in a similar, but weakly doped structure. Thus a significant improvement in the output power and efficiency by strong n-doping is predicted.

Drinking water availability is a crucial problem that must be addressed in order to improve the quality of life of individuals living developing nations. Improving water supply availability is important for public health, as it is the third highest risk factor for poor health in developing nations with high mortality rates. This project researched drinking water filtration for areas of Sub-Saharan Africa near existing bodies of water, where the populations are completely reliant on collecting from surface water sources: the most contaminated water source type. Water filtration methods that can be completely created by the consumer would alleviate aid organization dependence in developing nations, put the consumers in control, and improve public health. Filtration processes pass water through a medium that will catch contaminants through physical entrapment or absorption and thus yield a cleaner effluent. When exploring different materials for filtration, removal of contaminants and hydraulic conductivity are the two most important components. Not only does the method have to treat the water, but also it has to do so in a timeframe that is quick enough to produce potable water at a rate that keeps up with everyday needs. Cement is easily accessible in Sub- Saharan regions. Most concrete mixtures are not meant to be pervious, as it is a construction material used for its compressive strength, however, reduced water content in a cement mixture gives it higher permeability. Several different concrete samples of varying thicknesses and water concentrations were created. Bacterial count tests were performed on both pre-filtered and filtered water samples. Concrete filtration does remove bacteria from drinking water, however, the method can still be improved upon.