Privacy, Trust and Interaction in the Internet of Things

Abstract. This workshop addresses topics of increasing importance in the emerging area of the Internet of Things (IoT): privacy, trust and related interaction concepts. The aim of the workshop is to bring together experts from different areas to cover the complexity of the questions involved and to provide a forum for developing new ideas on how to address the major challenges in the field considering both a scientific and an industrial viewpoint. The workshop targets to identify pressing questions and to develop a research agenda for trusted and privacy-respecting computing in the IoT. Special attention within the workshop is given on whether and how experiences with privacy and trust from related areas can be applied to the IoT, where existing conceptualizations need to be extended or modified and where radically new concepts are required. The Internet of Things (IoT) is an umbrella term covering a number of different base technologies aimed at linking physical objects and their virtual representation with the goal to utilize this link for improved service and interaction concepts [3]. The IoT approach combines concepts and paradigms informed by Ambient Intelligence, Ubiquitou

Оптичні властивості плівок оксиду ванадію

Як типовий корельований електронний матеріал, діоксид ванадію VO2 демонструє перехід метал-діелектрик при відносно низькій температурі. При нагріванні відбувається перехід від діелектричної моноклінної фази до металевої тетрагональної фази (структура рутилу) з перегрупуванням іонів ванадію вздовж осі моноклінної гратки. Зміна фази відповідає колосальному падінню питомого опору більш ніж на чотири порядки, а також іншим змінам властивостей, які можуть бути оборотними через природний процес охолодження. Таким чином, VO2 привернув велику увагу при його застосуванні у високочутливих розумних пристроях, які можуть різко реагувати на різноманітні зовнішні впливи. В останні роки швидкий прогрес у виробництві та модуляції властивостей VO2 значно полегшив його застосування в багатьох аспектах, таких як термічне зондування, термохроміка, електроніка та механіка з множинним відгуком. Методом модуляційної поляриметрії досліджено оптичні властивості тонких плівок діоксиду ванадію. Для осадження тонкої плівки VO2 використовувався двоетапний метод. Плівки VO2 вирощували на підкладках з кварцового скла шляхом магнетронного розпилення мішені VO2 з подальшим термічним відпалом. Плівки мали різні модифікації складу, структури, морфології та оптичних властивостей, зумовлені технологією виготовлення. У роботі було виміряно кутові залежності коефіцієнтів відбивання електромагнітного випромінювання s- і pполяризацій і їх різницю для різних довжин хвиль. Поляризаційні характеристики були змодельовані за допомогою матричного перетворення формул Френеля. Значення показників заломлення та поглинання плівок були отримані з умови найкращого узгодження між експериментом і математичним моделюванням. Як стандартні аналітичні методи використовували атомно-силовий мікроскоп і рентгенівський дифракційний аналіз.As a typical Correlated Electron Material, vanadium dioxide was discovered to demonstrate metalinsulator transition at a relatively low temperature. The transition occurs from an insulating monoclinic phase to a metallic tetragonal phase (rutile structure) upon heating with the rearrangement of vanadium ions along an axis of the monoclinic lattice. The phase change corresponds to a colossal resistivity drop by over four orders of magnitude as well as other dramatic property changes, which can be reversible via a natural cooling process. Therefore, vanadium dioxide has attracted extensive attention for its applications in highly sensitive smart devices that can abruptly respond to diverse external stimuli. In recent years, rapid advancement in the fabrication and property modulation of vanadium dioxide has greatly facilitated its applications in many aspects, such as thermal sensing, thermochromics, electronics, and multiple-response mechanics. The optical properties of thin vanadium dioxide films VO2 were researched using the modulation polarimetry technique. For VO2 thin film deposition the two-step method was used. VO2 films were grown on quartz glass substrates by magnetron sputtering of the VO2 target. The films had different modifications of composition, structure, morphology, and optical properties due to the manufacturing technology. The angular dependence of the reflection coefficients of electromagnetic radiation of s- and p- polarizations and their difference for different wavelengths was measured in the paper. The polarization characteristics were simulated by a matrix transformation of the Fresnel formulas. The values of the refractive and absorption indices of the films were obtained from the condition of the best agreement between the experiment and mathematical simulation. Atomic force microscope and X-ray diffraction analysis were used as standard analytical methods

The effect of TiO2 crystalline phase on microstructure and optical features of Zn2TiO4 doped with Mn

International audienc

Study of Mn ion charge state in Zn2TiO4 and its impact on the photoluminescence and optical absorption spectra

International audienc

The role of excess MgO in the intensity increase of red emission of Mn4+-activated Mg2TiO4 phosphors

International audienceThe influence of magnesium oxide (MgO) content on the intensity of red photoluminescence (PL) of Mn4+ ions in Mn-doped phosphors Mg2TiO4:Mn produced by solid-state reaction at 1200 °C has been investigated by PL, optical absorption, X-ray diffraction, and electron paramagnetic resonance methods. The phosphors synthesized with excess MgO show an increase of Mn4+ red emission compared with those of stoichiometric composition. The magnitude of this increase depends on both MgO and Mn content. The largest increase of PL intensity is found for the phosphors synthesized under 3:1 molar ratios of MgO to TiO2. For these phosphors, the PL intensity increases from time 1.1 to time 3 when Mn concentration decreases from 1.0 to 0.0001 mol%. The phosphors produced under 6:1 molar ratios demonstrate a decrease of PL intensity at any Mn concentration. It is shown that excess MgO promotes stabilization of Mg2TiO4 phase against decomposition, hinders formation of Mn2+ centers, and enhances Mn4+ ions incorporation in the Mg2TiO4 crystal lattice. The latter together with reduced concentration quenching are supposed to be the main reasons of PL enhancement, which leads to the conclusion that excess MgO is necessary to produce an efficient red phosphor

Effect of Li+ co-doping on structural and luminescence properties of Mn4+ activated magnesium titanate films

International audienceThe effect of Li+ co-doping on crystal phase formation and photoluminescence (PL) of Mn4+ activated magnesium titanate films produced by a solid state reaction method at different temperatures (800–1200 °C) has been investigated by using X-ray diffraction (XRD), diffuse reflectance and PL spectroscopy. The chemical composition of sintered films was estimated by energy dispersive X-ray spectroscopy. The concentration of Mn impurity estimated by Electron spin resonance was about 5 × 1016 cm−3. The XRD study of the annealed films revealed several magnesium titanate crystal phases, such as Mg2TiO4, MgTiO3 and MgTi2O5. The contribution of each phase depended strongly on the annealing temperature and the presence of Li+ additive. Furthermore, Li+ co-doping facilitated the formation of both MgTiO3 and Mg2TiO4 phases, especially at lower annealing temperatures. The PL spectra showed two bands centered at 660 and 710 nm and ascribed to the $^{2}E$ → ${^4}$A$_{2}$ spin-forbidden transition of the Mn4+ ion in the Mg2TiO4 and MgTiO3, respectively. In Li co-doped films, the integrated intensity of Mn4+ luminescence was found several times stronger compared to Li-undoped films that was ascribed mainly to flux effect of lithium

Optical and structural properties of Mn-doped magnesium titanates fabricated with excess MgO

International audienceOptical and structural properties of ceramics based on Mn-doped magnesium titanates synthesized by sintering in air at 1200 °C of MgO and TiO$_2$ powders of different molar ratio ranging from MgTiO$_3$ to Mg$_2$TiO$_4$ stoichiometric compositions were studied. The influence of excess MgO on Mn incorporation in crystal lattice of MgTiO$_3$ was also investigated. The Mn$^{4+}$ ions substituted Ti$^{4+}$ sites were controlled by the photoluminescence (PL) and diffuse reflectance spectroscopy, and the Mn$^{2+}$ ions on Mg$^{2+}$ sites were monitored by electron paramagnetic resonance (EPR). The ceramics produced using equimolar ratio of MgO and TiO$_2$ composed of a major MgTiO$_3$ and a minor MgTi$_2$O$_5$ crystal phases, and those made with excess MgO contained MgTiO$_3$ and Mg$_2$TiO$_4$ phases in different proportions. The EPR study showed that Mn incorporated in MgTiO$_3$ synthesized under 1:1 molar ratio as Mn$^{2+}$ ion mainly. This agreed with low intensity of Mn$^{4+}$ red PL ascribed to low concentration of Mn$^{4+}$ centers and partial absorption of the UV excitation light by the MgTi$_2$O$_5$ phase. The Mn-doped MgTiO$_3$ synthesized with excess MgO of 19 and 50 mol.% showed increased Mn$^{4+}$ red PL by a factor 30-50, enhanced Mn$^{4+}$ optical absorption and more than ten times decreased Mn$^{2+}$ EPR signal. The Mg$_2$TiO$_4$ phase was found to be under compressive strains attributed to the presence of Mg vacancies and demonstrated Mn$^{4+}$ red PL with modified spectrum shape and decay behavior. It is concluded that in MgTiO$_3$ the excess MgO facilitates the incorporation of Mn onto Ti$^{4+}$ site and can be used for the increasing of Mn$^{4+}$ PL intensity