Martin Ouwerkerk | Philips Electronics (original) (raw)

Papers by Martin Ouwerkerk

A study was made of the dynamical behaviour of bound interstitial fluoride ions in disordered Bal... more A study was made of the dynamical behaviour of bound interstitial fluoride ions in disordered BalmxLaxF2+x and Bal_xUxF2+2x solid solutions with Thermally Stimulated Depolarisation Current measurements and neutron scattering measurements, and a combination of both techniques. From 10 K to 400 K the TSDC spectra showed four reorientation peaks to be present in Bal_xLaxF,+,, and six in Bal-xUxF2+2x, along with the relaxation of the macroscopic space charge. The position of a space charge peak shifted to lower temperatures with increasing solute content. The dipolar realaxations were concentration invariant. In Bal_xLaxF2+x neutral associates, L-shaped-and (222)clusters occur. The present study reveals (212)-clusters to be present in Bal_xUxF,+,,. The relations between ion dynamics and defect structures are discussed.

Recent developments in the field of facial expression recognition advocate the use of feature vec... more Recent developments in the field of facial expression recognition advocate the use of feature vectors based on local binary patterns (LBP). Research on the algorithmic side addresses robustness issues when dealing with non-ideal illumination conditions. In this paper, we address the challenges related to mapping these algorithms on smart camera platforms. Algorithmic partitioning taking into account the camera architecture is investigated with a primary focus of keeping the power consumption low. Experimental results show that compute-intensive feature extraction tasks can be mapped on a massively-parallel processor with reasonable processor utilization. Although the final feature classification phase could also benefit from parallel processing, mapping on a general purpose sequential processor would suffice.

Acta Crystallographica Section C-crystal Structure Communications, 1985

... For SmH3 and LuH3 the absorption edge lies at a longer wavelength and more Mg is required. Fi... more ... For SmH3 and LuH3 the absorption edge lies at a longer wavelength and more Mg is required. Figure 1 shows one more interesting feature: The trans-mission of aMg alloy hydride is higher than that of the pure metal hydride. ...

A modular application development platform for miniature wireless sensor/actuator devices called ... more A modular application development platform for miniature wireless sensor/actuator devices called Small Autonomous Network Devices (SANDs) is described. As an application example a system power breakdown of a real-time ECG analysis is presented. The application development SANDs have a volume of about one cubic centimeter. Based upon testing and optimization the schematics and specifications are obtained for the mass-production SANDs. Utilizing System in Package (SiP) technology the volume can be reduced up to five times. These devices can be used in a truly unnoticeable and unobtrusive way to serve as the smallest components of a personal health care monitoring system or an ambient intelligence system.

The quantification of the human perception of experiences can be achieved by the sensing of speci... more The quantification of the human perception of experiences can be achieved by the sensing of specific psychophysiological parameters. A growing interest develops for the daily life use of these quantification techniques by unobtrusive and unnoticeable data collection. Remote and non invasive sensing technologies are discussed for the sensing of the following psychophysiological parameters: heart rate variability, and muscle stress. A generic miniature platform for miniature wireless sensing applications is described as an important enabler for unobtrusive and unnoticeable sensing. The technology no longer seems to be a limiting factor for unobtrusive and unnoticeable sensing. Initially the sensors will be worn on the body, but ultimately implantable sensors will become widely accepted, allowing access to new parameters, such as hormone levels and body core temperature.

Microelectronics Journal, 2006

Networks of autonomous microsensors promise to revolutionize the way people interact with electro... more Networks of autonomous microsensors promise to revolutionize the way people interact with electronics, enabling ambient intelligence. In this paper we investigate different energy scavenging options in real applications to find out which devices are more suitable to power a microsensor having a volume of only 100 mm 3 . Photovoltaic cells are the most promising power generators when a power level of 100 mW is required. If the power consumption can be reduced to about 10 mW, MEMS-based vibration-driven scavengers and thermoelectric generators can also be used.

The measurement of human emotions in a daily life setting is reviewed in this chapter. In detail ... more The measurement of human emotions in a daily life setting is reviewed in this chapter. In detail the hardware aspects of the Philips Research emotion measurement platform are described. The platform contains a wireless skin conductance wristband, a wireless chest strap ECG sensor and a wireless ear clip blood volume pulse sensor, which together with an internet tablet as hub form a personal wireless network. Two examples of applications, which have been evaluated in the form of concepts are presented.

Advanced Materials, 1991

... By Martin Ouwerkerk* ... the frequency doubling of a GaAs-laser in the ma-terial potassium li... more ... By Martin Ouwerkerk* ... the frequency doubling of a GaAs-laser in the ma-terial potassium lithium niobate (KLN, chemical formula: K,Lil,85Nb5,15015,3 ... materials and some success-ful approaches have been reported.Lg - ' 31 For example, 2-dicyanovinylanisole 1 (DIVA) has a ...

Journal of The Chemical Society, Faraday Transactions 2, 1982

Materials Research Bulletin, 1992

The low-temperature luminescence properties of potassium lithium niobates K3Li2_xNbs+xO15+2 x (0 ... more The low-temperature luminescence properties of potassium lithium niobates K3Li2_xNbs+xO15+2 x (0 < x < 0.5) are reported and discussed in terms of corner-sharing NbO 6 octahedra. The quenching temperature of the luminescence is low and depends on the composition of the potassium lithium niobates. These compositions are important nonlinear optical materials in contrast with niobates with a high luminescence quenching temperature.

To improve human-computer interaction (HCI), computers need to recognize and respond properly to ... more To improve human-computer interaction (HCI), computers need to recognize and respond properly to their user’s emotional state. This is a fundamental application of affective computing, which relates to, arises from, or deliberately influences emotion. As a first step to a system that recognizes emotions of individual users, this research focuses on how emotional experiences are expressed in six parameters (i.e., mean, absolute deviation, standard deviation, variance, skewness, and kurtosis) of not baseline-corrected physiological measurements of the galvanic skin response (GSR) and of three electromyography signals: frontalis (EMG1), corrugator supercilii (EMG2), and zygomaticus major (EMG3). The 24 participants were asked to watch film scenes of 120 seconds, which they rated afterward. These ratings enabled us to distinguish four categories of emotions: negative, positive, mixed, and neutral. The skewness and kurtosis of the GSR, the skewness of the EMG2, and four parameters of EMG3, discriminate between the four emotion categories. This, despite the coarse time windows that were used. Moreover, rapid processing of the signals proved to be possible. This enables tailored HCI facilitated by an emotional awareness of systems.

The growing interest in affective computing is expected to have its beneficial impact on consumer... more The growing interest in affective computing is expected to have its beneficial impact on consumer lifestyle products. Especially emphatic applications - applications that make you feel they really understand you - will serve the current consumer interest in enhanced and meaningful experiences. To do so, the applications will have to measure the user's emotional experience. Well-established psychophysiological techniques bear promise, but so far have mainly been validated in laboratory situations. To also apply them in real-life situations, we built an emotion measurement platform. This platform shows that emotional experiences can be measured in a relatively unobtrusive way, while at the same time it enables us to gather knowledge on emotional experiences in everyday-life and it offers the opportunity to prototype emphatic application concepts and test them in relevant situations.

A post-traumatic stress disorder (PTSD) is a severe stress disorder and, as such, a severe handic... more A post-traumatic stress disorder (PTSD) is a severe stress disorder and, as such, a severe handicap in daily life. To this date, its treatment is still a big endeavor for therapists. This chapter discusses an exploration towards automatic assistance in treating patients suffering from PTSD. Such assistance should enable objective and unobtrusive stress measurement, provide decision support on whether or not the level of stress is excessive, and, consequently, be able to aid in its treatment. Speech was chosen as an objective, unobtrusive stress indicator, considering that most therapy sessions are already recorded anyway. Two studies were conducted: a (controlled) stress-provoking story telling (SPS) and a(n ecologically valid) re-living (RL) study, each consisting of a “happy” and an “anxiety triggering” session. In both studies the same 25 PTSD patients participated. The Subjective Unit of Distress (SUD) was determined as a subjective measure, which enabled the validation of derived speech features. For both studies, a Linear Regression Model (LRM) was developed, founded on patients’ average acoustic profile. It used five speech features: amplitude, zero crossings, power, high-frequency power, and pitch. From each feature, 13 parameters were derived; hence, in total 65 parameters were calculated. Using LRMs, respectively 83 and 69% of the variance was explained for the SPS and RL study. Moreover, a set of generic speech signal parameters was presented. Together, the models created and parameters identified can serve as the foundation for future artificial therapy assistants.

Journal of Power Sources, 2004

Two different strategies are outlined to develop both high energy density and space-efficient bat... more Two different strategies are outlined to develop both high energy density and space-efficient batteries, including the most widely applied rechargeable nickel-metal hydride (NiMH) and Li-ion batteries. The hydrogen storage capacity of fluorite-structured Mg-containing compounds are shown to have a reversible electrochemical storage capacity of more than four times that of the commonly used MischMetal-based AB 5 compounds in NiMH, i.e. 1500 mAh/g (5.6 wt.%). The formation of octahedral sites within the crystal lattice is argued to be very crucial for the improved kinetics of hydrogen absorption and desorption. It is shown that the fluorite-structure can be conserved with both precious Sc and the less expensive Ti up to a Mg content of 80 at.%. Both thermodynamic and kinetic data are presented in relation to the materials composition. In addition, the development of preshaped batteries, as the first step to battery integration, has contributed to a much higher level of design freedom for portable electronic equipment. The manufacturing process of preshaped batteries will be described together with their electrochemical characteristics. Advantageously, the mechanical stability is provided locally by polymer rivets, allowing to get rid of heavy metallic casings and to make use of a much wider range of battery shapes.

Journal of Alloys and Compounds, 2003

A model is proposed which includes the charge transfer reaction and the formation of adsorbed hyd... more A model is proposed which includes the charge transfer reaction and the formation of adsorbed hydrogen at the electrode / electrolyte interface, absorption of hydrogen into the solid-state MH electrode, recombination of adsorbed hydrogen atoms into molecular hydrogen dissolved in the electrolyte and hydrogen in the gas phase. It was found that the rate of the charge transfer reaction, as represented by the exchange current, is dependent on the partial hydrogen pressure (P ) in a rather complex way: a positive linear dependence between H 2 log I and log P is found at relatively low partial pressures, which subsequently passes through a maximum, turning into a negative 0 H 2 dependence at higher partial pressures. Both the slopes of the lines and the turning points are found to be strongly dependent on the rate constants of the various reactions. The theoretical model has been verified with both switchable mirror MH thin film electrodes and multicomponent MH electrode materials, nowadays widely applied in commercial NiMH batteries. The as-deduced theoretical relationship will form the basis for the modelling of complete NiMH batteries. 

Materials Research Bulletin, 1985

Crystals of the solid solutions MF2:UF 4 (M = Ca, St, Ba, and Pb) have been grown successfully by... more Crystals of the solid solutions MF2:UF 4 (M = Ca, St, Ba, and Pb) have been grown successfully by a modified Bridgeman-Stockbarger technique using a radlo-frequency induction furnace. All Ml_xUxF2+2x (x ~ 0.211) crystals appeared to be slngle-phase with the cubic fluorite (caP2) structure. Experimental circumstances necessary to avoid the reduction of U &+ to U 3+ during growth are discussed. Crystals containing tetravalent uranium have a blue-green colour. The presence of trlvalent uranium is marked by an orange-brown colouration of the crystal. Evidence of the valence-state of the uranium dopant is presented. X-ray diffraction and X-ray fluorescence methods have been utilised to determine the UF 4 content of the solid solutions. The effect of the incorporation of UF 4 on the stability of the ~-PbF 2 structure at room temperature is discussed.