ALBERT

Beschreibung: Over 10 μm-thick ( K , N a) N b O 3 KNN -based films doped with complex-perovskite-materials (CPs) were deposited on platinized sapphire substrates by aerosol deposition (AD). Three CPs were selected: B a( C u 1/3 N b 2/3 ) O 3 ( BCN ), C u( C u 1/3 N b 2/3 ) O 3 ( CCN ), and S r( C u 1/3 N b 2/3 ) O 3 ( SCN ). The films of 0.985( N a 0.5 K 0.5 ) N b O 3 -0.015CPs ( KNN -CPs) were post annealed at 1050°C for 1 h in air without any serious phase decomposition. The microstructure showed abnormal grain growth due to C u-rich liquid phase. The KNN – BCN film had the largest abnormal grain size of over 10 μm, whereas the KNN – SCN film had the smallest grain size and also the smallest frequency of abnormal grains. All the films exhibited typical characteristics of ferroelectric hysteresis similar to those of the bulk materials without any leakage. The KNN – BCN films possessing the biggest abnormal grains also exhibited the highest density, piezoelectric constant, and piezoelectric voltage constant of 110 pC/N and 15.45 × 10 −3  Vm/N, respectively, which are the highest values reported so far for KNN -based films. This indicated that KNN -CPs lead-free films are suitable candidates for sensor applications.

Beschreibung: Improving fingerprint matching algorithms is an active and important research area in fingerprint recognition. Algorithms based on minutia triplets, an important matcher family, present some drawbacks that impact their accuracy, such as dependency to the order of minutiae in the feature, insensitivity to the reflection of minutiae triplets, and insensitivity to the directions of the minutiae relative to the sides of the triangle. To alleviate these drawbacks, we introduce in this paper a novel fingerprint matching algorithm, named M3gl. This algorithm contains three components: a new feature representation containing clockwise-arranged minutiae without a central minutia, a new similarity measure that shifts the triplets to find the best minutiae correspondence, and a global matching procedure that selects the alignment by maximizing the amount of global matching minutiae. To make M3gl faster, it includes some optimizations to discard non-matching minutia triplets without comparing the whole representation. In comparison with six verification algorithms, M3gl achieves the highest accuracy in the lowest matching time, using FVC2002 and FVC2004 databases.

Beschreibung: Pollution of drinking water sources represents a continuously emerging problem in global environmental protection. Novel techniques for real-time monitoring of water quality, capable of the detection of unanticipated toxic and bioactive substances, are urgently needed. In this study, the applicability of a cell-based sensor system using selected eukaryotic cell lines for the detection of aquatic pollutants is shown. Readout parameters of the cells were the acidification (metabolism), oxygen consumption (respiration) and impedance (morphology) of the cells. A variety of potential cytotoxic classes of substances (heavy metals, pharmaceuticals, neurotoxins, waste water) was tested with monolayers of L6 cells (rat myoblasts). The cytotoxicity or cellular effects induced by inorganic ions (Ni2+ and Cu2+) can be detected with the metabolic parameters acidification and respiration down to 0.5 mg/L, whereas the detection limit for other substances like nicotine and acetaminophen are rather high, in the range of 0.1 mg/L and 100 mg/L. In a close to application model a real waste water sample shows detectable signals, indicating the existence of cytotoxic substances. The results support the paradigm change from single substance detection to the monitoring of overall toxicity.

Beschreibung: Small noncoding microRNAs (miRNAs) are important regulators of post-transcriptional gene regulation and have altered the prevailing view of a linear relationship between gene and protein expression. Aberrant miRNA expression is an emerging theme for a wide variety of diseases, highlighting the fundamental role played by miRNAs in both physiological and pathological states. The identification of stable miRNAs in bodily fluids paved the way for their use as novel biomarkers amenable to clinical diagnosis in translational medicine. Identification of miRNAs in exosomes that are functional upon delivery to the recipient cells has highlighted a novel method of intercellular communication. Delivery of miRNAs to recipient cells via blood, with functional gene regulatory consequences, opens up novel avenues for target intervention. Exosomes thus offer a novel strategy for delivering drugs or RNA therapeutic agents. Though much work lies ahead, circulating miRNAs are unequivocally ushering in a new era of novel biomarker discovery, intercellular communication mechanisms, and therapeutic intervention strategies.

Beschreibung: In this paper, a novel principle of contactless gauge block calibration is presented. The principle of contactless gauge block calibration combines low-coherence interferometry and laser interferometry. An experimental setup combines Dowell interferometer and Michelson interferometer to ensure a gauge block length determination with direct traceability to the primary length standard. By monitoring both gauge block sides with a digital camera gauge block 3D surface measurements are possible too. The principle presented is protected by the Czech national patent No. 302948.

Beschreibung: Quorum sensing (QS) is a population density-dependent regulatory mechanism in which gene expression is coupled to the accumulation of a chemical signaling molecule. QS systems are widespread among the plant soft-rotting bacteria. In Pectobacterium carotovorum, at least two QS systems exist being specified by the nature of chemical signals involved. QS in Pectobacterium carotovorum uses N-acylhomoserine lactone (AHL) based, as well as autoinducer-2 (AI-2) dependent signaling systems. This review will address the importance of the QS in production of virulence factors and interaction of QS with other regulatory systems in Pectobacterium carotovorum.

Beschreibung: Optical fibers possess many advantages such as small size, light weight and immunity to electro-magnetic interference that meet the sensing requirements to a large extent. In this investigation, a Mach-Zehnder interferometric optical fiber sensor is used to measure the dynamic strain of a vibrating cantilever beam. A 3 × 3 coupler is employed to demodulate the phase shift of the Mach-Zehnder interferometer. The dynamic strain of a cantilever beam subjected to base excitation is determined by the optical fiber sensor. The experimental results are validated with the strain gauge.

Beschreibung: Joint estimation of direction-of-arrival (DOA) and polarization with electromagnetic vector-sensors (EMVS) is considered in the framework of complex-valued non-orthogonal joint diagonalization (CNJD). Two new CNJD algorithms are presented, which propose to tackle the high dimensional optimization problem in CNJD via a sequence of simple sub-optimization problems, by using LU or LQ decompositions of the target matrices as well as the Jacobi-type scheme. Furthermore, based on the above CNJD algorithms we present a novel strategy to exploit the multi-dimensional structure present in the second-order statistics of EMVS outputs for simultaneous DOA and polarization estimation. Simulations are provided to compare the proposed strategy with existing tensorial or joint diagonalization based methods.

Beschreibung: In this study, multi-phase borosilicate-based glass-ceramics were investigated as an alternative waste form for immobilizing non-fissionable products from used nuclear fuel. Currently, borosilicate glass is the waste form selected for immobilization of this waste stream, however, the low thermal stability and solubility of MoO 3 in borosilicate glass translates into a maximum waste loading in the range 15–20 mass%. Glass-ceramics provide the opportunity to target chemically durable crystalline phases, e.g., powellite, oxyapatite, celsian, and pollucite that will incorporate MoO 3 as well as other waste components such as lanthanides, alkalis, and alkaline earths at levels twice the solubility limits of a single-phase glass. In addition a glass-ceramic could provide higher thermal stability, depending upon the properties of the crystalline and amorphous phases. Here, glass-ceramics were synthesized at waste loadings of 42, 45, and 50 mass% with the following glass additives: B 2 O 3 , Al 2 O 3 , CaO , and SiO 2 by slow-cooling from a glass melt. Glass-ceramics were characterized in terms of phase assemblage, morphology, and thermal stability. Only two of the targeted phases, powellite and oxyapatite, were observed, along with lanthanide-borosilicate and cerianite. Results of this initial investigation show promise of glass-ceramics as a potential waste form to replace single-phase borosilicate glass.

Beschreibung: The dielectric properties of a new, cubic, pyrochlore-type solid solution B i (1.6−1.08 x ) N d x T i 2 O (6.4−0.11 x ) have been studied across the compositional range 0.35 〈  x  〈 0.86. The dielectric constant (ε) of the ceramics based on the pyrochlore-type solid solution within the experimental compositional range varied from 104 to 76 at 1 MHz, whereas the dielectric losses were well below tan δ = 8 × 10 −3 . The temperature coefficient of the dielectric constant τ k for single-phase pyrochlore samples was found to be in the range between −20 and −40 ppm/K. Below room temperature dielectric relaxation phenomena were observed for all the compositions.

Beschreibung: The mechanism of core/shell formation during sintering in B a T i O 3 -based systems was studied in ( M g, Y )-doped B a T i O 3 . The effect of ball milling time on core size and shell thickness was first observed. The core size was similar irrespective of ball milling time whereas the shell thickness increased with increasing ball milling time. The measured powder size after ball milling suggested that the cores were from the larger B a T i O 3 particles and the shells formed via dissolution of smaller particles and precipitation of dissolved material, in contrast with the interpretation of the results of a previous investigation. To identify the core/shell formation mechanism, bi-layer samples with different chemical compositions, 94 B a T i O 3 –2 Y 2 O 3 –2 M g O –2 S i O 2 (mol%) ( BT – YMS ) and 98 B a T i O 3 –2 S i O 2 (mol%) ( BT – S ), and different grain sizes were prepared. The morphology of the newly formed shell layer and the shape of an {111} twin across the interface between a core and a shell confirmed that the formation mechanism of the core/shell structure during sintering is the dissolution and precipitation of material rather than solid-state diffusion of solutes into B a T i O 3 .

Beschreibung: B i 2 (( Z n 1/3 N b 2/3 ) 1− x T i x ) 2 O 7 ceramics with 0 ≤  x  ≤ 0.4 were synthesized using solid-state reaction method. The crystal structure is pure zirconolite type for the compositions with 0 ≤  x  ≤ 0.15, single weberite type for the compositions with 0.3 ≤  x  ≤ 0.4, and mixture of zirconolite and weberite for the compositions with 0.15 〈  x  〈 0.3. The weberite ceramics with only B i as the A-site cation are first reported. A possible correlation between the crystal structure transformation and T i content in system of B i 2 (( Z n 1/3 N b 2/3 ) 1− x T i x ) 2 O 7 with 0 ≤  x  ≤ 0.4 was suggested. Dielectric constant (ε), dielectric loss (tan δ) and temperature coefficient of capacitance (TCC) are ~85, ~0.001, and ~200 ppm/°C for the zirconolite solid solutions, ~140, 0.004, and between −120 and −200 ppm/°C for the weberite solid solutions, respectively, at 1 MHz. Ceramics with a near zero TCC consisting of the zirconolite and weberite phases were obtained. High ε, low tanδ, and low sintering temperatures (~950°C) make the novel ceramic system of B i 2 (( Z n 1/3 N b 2/3 ) 1− x T i x ) 2 O 7 potential dielectrics for applications in low-temperature co-fired ceramic and multiplayer ceramic capacitors.

Beschreibung: LaNbO 4 / La 3 NbO 7 and LaNbO 4 / LaNb 3 O 9 cer-cer composites were prepared by impregnating Ca -doped LaNbO 4 powder, synthesized by spray pyrolysis, with La - or Nb -precursor solutions. The sintering of the calcined powders was investigated by dilatometry, and dense composites were prepared by conventional sintering, hot pressing, and spark plasma sintering. The particle size of the starting powders was about 50 nm, and the average grain size of the dense materials ranged from 100 nm and upwards, depending on the sintering temperature, sintering procedure, and the phase composition. The unit cell parameters of LaNbO 4 showed a finite size effect and approached the cell parameters of tetragonal LaNbO 4 with decreasing crystallite size, both for the single-phase material and the composites. The minority phase ( La 3 NbO 7 or LaNb 3 O 9 ) were observed as isolated grains and accumulated at triple points and not along the grain boundaries, pointing to a large dihedral angle between the phases. The calcium-solubility in the minority phases was larger than in LaNbO 4 , which corresponds well with previous reports. The electrical conductivity of the hetero-doped materials was similar to, or lower than, that for Ca -doped LaNbO 4 .

Beschreibung: We studied the nucleation and growth of nano-sized crystals on two glass-ceramic systems: a conventional lithium-aluminosilicate (LAS) and a ( M g, Z n) spinel. We combined several techniques: in situ Small Angle Neutron Scattering (SANS), Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM), and laboratory X-ray diffraction (XRD). We observed by SANS, and confirmed by DSC, that during a temperature ramp, transient phenomena occur between the regions of nucleation and growth in the LAS, which do not follow classic kinetic theories. In contrast, the spinel material shows a smooth transition during the temperature ramp between the nucleation and the growth stages, and follows a more conventional growth pattern. In the spinel system the initial phase separation plays a very important role in determining the crystalline phase distribution in the glassy matrix, as crystallites are confined only in one phase.

Beschreibung: A key requirement for the use of bio scaffold is that its degradation rate matches the growth rate of target tissue. Therefore, the degradation of recently developed tailored amorphous multiporous (TAMP) scaffold of 70 SiO 2 ·30 CaO (mol%) in simulated body fluid (SBF) was studied under both static and quasi-dynamic conditions. The degradation was assessed through the dissolution of silica from the glass into SBF, while the in-vitro bioactivity was characterized by precipitation of calcium phosphate ( CaP ) on and inside the scaffold. Under static conditions, the degradation stopped due to the saturation of solution with silica in 3 days, whereas the precipitation of CaP continued. Rapid degradation and better in-vitro bioactivity was found under quasi-dynamic conditions, where the concentration gradient across the sample was maintained. The degradation followed exponential dependence on time with a half-life of 15.4 days and initial degradation rate 4.5% day −1 . The remaining samples maintained their integrity and pore structure during degradation. The degradation occurred in three distinct stages: (a) wetting stage, (b) initial degradation stage when CaP precipitation dominates, and (c) intensive degradation stage when the nanopores rupture and network dissolves. By varying the sintering parameters the nanopore structure, and hence the degradation rate, can be tailored to suit the anticipated tissue regeneration rate. With demonstrated rapid and controllable degradation and good in-vitro bioactivity, the TAMP scaffold shows promise as candidate for bone regeneration application under various conditions in the body.

Beschreibung: The development of a rapid, sensitive, specific method for the foodborne pathogenic bacteria detection is of great importance to ensure food safety and security. In recent years impedimetric biosensors which integrate biological recognition technology and impedance have gained widespread application in the field of bacteria detection. This paper presents an overview on the progress and application of impedimetric biosensors for detection of foodborne pathogenic bacteria, particularly the new trends in the past few years, including the new specific bio-recognition elements such as bacteriophage and lectin, the use of nanomaterials and microfluidics techniques. The applications of these new materials or techniques have provided unprecedented opportunities for the development of high-performance impedance bacteria biosensors. The significant developments of impedimetric biosensors for bacteria detection in the last five years have been reviewed according to the classification of with or without specific bio-recognition element. In addition, some microfluidics systems, which were used in the construction of impedimetric biosensors to improve analytical performance, are introduced in this review.

Beschreibung: Traditionally, the nuclear and aerospace industries have been the main drivers behind the development of high-temperature materials. These applications demand a high degree of reliability and extensive characterization of every new material. There is a lack of experimental thermodynamic data above 1500°C even for HfO 2 , ZrO 2 , La 2 O 3 , Y 2 O 3 , and other constituents of widely used ceramic systems. Such data, as are available, were often obtained half a century ago using custom-built instruments. We review classic experimental approaches for the measurement of formation enthalpies, high-temperature enthalpy increments by the drop method, and also discuss more recent developments which include mass spectrometric measurements of vapor pressures, pulsed laser relaxation methods for heat capacity, and melting temperature determination and high-temperature oxide melt solution calorimetry in application to refractory compounds. Approaches to the experimental determination of phase diagrams at high temperature are introduced using studies of liquid immiscibility in the Zr(O) –UO 2 system as an example. Thermal analysis above 2000°C is now possible with commercially available instruments, as shown by the first experimental measurements of the phase transition and fusion enthalpies of La 2 O 3 . New results on a premelting phase transition in Y 2 O 3 in oxygen are reported from in situ synchrotron X-ray diffraction study on levitated samples.

Beschreibung: Nano-hafnium diboride powder was synthesized by boro/carborthermal reduction process of HfO 2 using a spark plasma sintering (SPS) apparatus. The agglomerated product was found to be 1–2 μm in size, which was composed with small primary particles of 100–200 nm in size. The particle size of HfO 2 played an important role to produce the nano-boride powder. In addition, the grain growth of HfB 2 could be effectively suppressed by using SPS due to the fast heating rate. The synthesized powder had a low oxygen content (~0.66 wt%). Excessive B 4 C and C were necessary during the boro/carborthermal reduction in HfO 2 process because of the volatilization of boron as a form of B 2 O 3 and the reduction in residual HfO 2 .

Beschreibung: 0.65 Pb ( Mg 1/3 Nb 2/3 ) O 3 –0.35 PbTiO 3 powder was prepared by a single-step, solid-state synthesis at 850°C. This was enabled by the controlled agglomeration of precursor particles by the change of pH in water suspensions. With the design of the contacts between the particles in the agglomerates, a phase-pure perovskite powder was synthesized from a suspension with a pH = 12.5. At the inherent pH = 11.4, the agglomerates that promote the pyrochlore formation were formed, resulting in a mixture of perovskite and pyrochlore phases after the calcination. The ceramics prepared from the suspension with pH = 12.5 were sintered to 96% of theoretical density at only 950°C, and exhibited electrical properties comparable to ceramics prepared by the columbite method, sintered at much higher temperatures. In contrast, the properties of the ceramics from the pH = 11.4 suspension were heavily deteriorated due to the presence of the pyrochlore phase and the high degree of porosity.

Beschreibung: The properties that determine the thermal shock resistance in materials are reported for porous cordierite, a leading candidate material for the fabrication of diesel particulate filters. Fracture toughness and slow crack growth tests were performed on test specimens obtained from the walls of diesel particulate filter monolithic substrates using the double-torsion test method at temperatures between 20°C and 900°C. The thermal expansion and elastic properties were characterized between 20°C and 1000°C. The role of the microstructure of porous cordierite in determining its unusual thermal expansion and elevated temperature Young's modulus and fracture toughness are discussed.

Beschreibung: Chitosan/Boron nitride ( BN ) composites were prepared by solution method using CuSO 4 /glycine chelate complex as the catalysis with variable percentage of boron nitride loading. The dispersion of BN with the chitosan polymer was achieved with sonication at power of 120 W and frequency of 80 kHz. The chemical interactions of chitosan and BN were studied by Fourier transform infrared spectroscopy. The structure of chitosan and BN composites were investigated by XRD and TEM. It was observed that the BN were dispersed with chitosan matrix through intercalation. The quantitative identification of composites was investigated by Energy Dispersive X-ray Spectroscopy and Selected Area Electron Diffraction. Thermal stabilities of chitosan/ BN composites were studied by thermogravimetric analysis. It was found that, the thermal stability of the chitosan/ BN composites was increased compare with virgin chitosan. The oxygen barrier properties of chitosan/ BN composites were measured using gas permeameter. A substantial reduction in oxygen permeability was observed increasing boron nitride concentrations by which the synthesized composite materials may applicable in packaging industry.

Beschreibung: Landcover is subject to continuous changes on a wide variety of temporal and spatial scales. Those changes produce significant effects in human and natural activities. Maintaining an updated spatial database with the occurred changes allows a better monitoring of the Earth’s resources and management of the environment. Change detection (CD) techniques using images from different sensors, such as satellite imagery, aerial photographs, etc., have proven to be suitable and secure data sources from which updated information can be extracted efficiently, so that changes can also be inventoried and monitored. In this paper, a multisource CD methodology for multiresolution datasets is applied. First, different change indices are processed, then different thresholding algorithms for change/no_change are applied to these indices in order to better estimate the statistical parameters of these categories, finally the indices are integrated into a change detection multisource fusion process, which allows generating a single CD result from several combination of indices. This methodology has been applied to datasets with different spectral and spatial resolution properties. Then, the obtained results are evaluated by means of a quality control analysis, as well as with complementary graphical representations. The suggested methodology has also been proved efficiently for identifying the change detection index with the higher contribution.

Beschreibung: A memristor bridge neural circuit which is able to perform signed synaptic weighting was proposed in our previous study, where the synaptic operation was verified via software simulation of the mathematical model of the HP memristor. This study is an extension of the previous work advancing toward the circuit implementation where the architecture of the memristor bridge synapse is built with memristor emulator circuits. In addition, a simple neural network which performs both synaptic weighting and summation is built by combining memristor emulators-based synapses and differential amplifier circuits. The feasibility of the memristor bridge neural circuit is verified via SPICE simulations.

Beschreibung: This work presents an experimental study of gold-DNA-gold structures in the presence and absence of external magnetic fields with strengths less than 1,200.00 mT. The DNA strands, extracted by standard method were used to fabricate a Metal-DNA-Metal (MDM) structure. Its electric behavior when subjected to a magnetic field was studied through its current-voltage (I-V) curve. Acquisition of the I-V curve demonstrated that DNA as a semiconductor exhibits diode behavior in the MDM structure. The current versus magnetic field strength followed a decreasing trend because of a diminished mobility in the presence of a low magnetic field. This made clear that an externally imposed magnetic field would boost resistance of the MDM structure up to 1,000.00 mT and for higher magnetic field strengths we can observe an increase in potential barrier in MDM junction. The magnetic sensitivity indicates the promise of using MDM structures as potential magnetic sensors.

Beschreibung: A flow-electrolytical cell containing a strand of micro Au modified carbon fiber electrodes (CFE) has been designedand characterized for use in a voltammatric detector for detecting cysteine using high-performance liquid chromatography. Cysteine is more efficiently electrochemical oxidized on a Au /CFE than a bare gold and carbon fiber electrode. The possible reaction mechanism of the oxidation process is described from the relations to scan rate, peak potentials and currents. For the pulse mode, and measurements with suitable experimental parameters, a linear concentration from 0.5 to 5.0 mg·L−1 was found. The limit of quantification for cysteine was below 60 ng·mL−1.

Beschreibung: Using three different sintering methods: spark plasma sintering, two-step sintering, and normal sintering ( Ba 0.85 Ca 0.15 )( Zr 0.1 Ti 0.9 ) O 3 ( BCZT ) lead-free piezoelectric ceramics with grain sizes in the range of 0.4–32.2 μm were prepared. The effects of grain size on the electrical properties and temperature stability of BCZT ceramics were systematically investigated. Results showed that reducing grain size shifted both the T c and T T-R to higher temperatures, and tended to enhance the relaxor behavior. A strong dependence of piezoelectric properties on the grain size was observed, and ~10 μm was a critical point for fabricating high-performance BCZT ceramics. For samples with grain sizes 〉10 μm, excellent piezoelectric properties of k p  〉 0.48, k t  〉 0.46, d 33  〉 470 pC/N and d 33 * 〉 950 pm/V were obtained. Moreover, no evident relationship between the grain size and temperature stability existed in this material, and all samples exhibited thermal instability below the Curie temperature. However, increasing grain size was helpful for improving the resistance to thermal depoling. The depolarization was assisted by internal mechanical stresses and the movement of 180° and 90° domain walls, which explained the increased resistance to thermal depoling in coarse-grained samples.

Beschreibung: ( Ca , Dy ) co-stabilized α-Sialon with elongated grains was prepared from SiO 2 – AlN – CaF 2 – Dy 2 O 3 powders by carbothermal reduction-nitridation (CRN) at 1700°C. Detailed investigations on the formation process of ( Ca , Dy )-α-Sialon elongated grains performed under various firing conditions revealed that the big quartz particles were initially reduced and decomposed gradually by carbon, and a large number of ball-shaped particles consisting of amorphous ( Si , Al , Ca , Dy ) x ( O , N ) y were formed. With increasing temperature, nitrogen continuously diffused into the liquid to form nitrogen-rich solid balls. Further increasing the temperature to 1700°C and held for 2 h, hollow α-Sialon spheres with nanometric particles were obtained from nitrogen-rich solid balls. Subsequently, the framework structure of hollow spheres was destroyed at 1700°C for 3 h, and ( Ca , Dy )-α-Sialon grains grew up continuously by consuming nanometric particles in the rough interface via Ostwald ripening and growth stages moving on the smooth interface. Finally, ( Ca , Dy )-α-Sialon developed well-defined crystalline elongated grains because the growth rate of rough surfaces is more rapid than that of smooth surfaces.

Beschreibung: A new temperature stable, low-loss, low sintering temperature microwave dielectric material Mg 0.5 Zn 0.5 TiNb 2 O 8 was investigated for the first time. Single phase Mg 0.5 Zn 0.5 TiNb 2 O 8 was obtained, and it showed Columbite structure which was tri-ixiolite structure. The variation trend of dielectric constant was in accordance with variation trend of relative density. When the sintering temperature was lower than 1120°C, the Qf value increased with the increasing of relative density. When the sintering temperature was higher than 1120°C, the Qf value decreased with the increasing of the unit cell volume. With the decrease of bond strength, the τ f increased. The typical values of ε = 30.74, Qf  = 66 900 GHz, τ f  = −4.01 × 10 −6 /°C were obtained for Mg 0.5 Zn 0.5 TiNb 2 O 8 sintered at 1120°C for 6 h.

Beschreibung: Oxide ion transport in Pb ( Zr x Ti 1– x ) O 3 ( PZT ) was investigated using 18 O tracer diffusion and time-of-flight secondary ion mass spectrometry analysis. Particularly diffusion in the near-surface regions (a few 100 nm in depth) is discussed and strong evidence for a space charge layer near the surface is provided. In this layer, an enrichment of oxygen vacancies is found at temperatures up to 600°C, resulting in box-shaped tracer diffusion profiles. At 650°C, however, the profile shape is modified and reveals a depletion of oxygen vacancies close to the surface. Accordingly, a change in the polarity of the surface charge takes place between 600°C and 650°C. The tracer diffusion profiles are very sensitive to surface modification, caused by etching or annealing at higher temperature, and also depend on the sintering procedure. Moreover, application of an external field during the tracer experiments affected the tracer diffusion at the cathode, while leaving the profile at the anode unperturbed. Quantitative analysis of the profiles was performed by means of numerical calculations based on Gouy-Chapman or Mott-Schottky space charge models. Estimates of the oxygen vacancy concentration and ionic transference number of donor-doped PZT are provided.

Beschreibung: Nanocrystalline tetragonal ZrO 2 polycrystals ( TZP ) have been fabricated by the pressureless sintering of recently developed tetragonal ZrO 2 powder containing 5.69 mol% YO 1.5 and 0.60 mol% AlO 1.5 . The average grain sizes were 160 nm in the TZP sintered at 1150°C for 10 h and 150 nm in the 0.25 mol% GeO 2 -doped TZP sintered at 1100°C for 100 h. The TZP and Ge 4+ -doped TZP-sintered bodies were essentially single-phase materials, and neither the amorphous layer nor the second-phase particle was observed along the grain boundary faces. High-resolution transmission electron microscopy (HRTEM), scanning transmission electron microscopy (STEM), and nanoprobe energy-dispersive X-ray spectrometer (EDS) measurements revealed that the Y 3+ , Al 3+ and Ge 4+ cations tend to segregate in the vicinity of the grain boundaries in the TZP -sintered bodies. The TZP and Ge 4+ -doped TZP exhibited an elongation to failure of more than 100% in the temperature range of 1150°C–1300°C and initial strain rate range of 1.4 × 10 −5  s −1 to 1.0 × 10 −2  s −1 . For instance, an elongation to failure in the Ge -doped TZP reached about 200% at 1150°C and 1.4 × 10 −5  s −1 . The nanocrystallization reduced the lower limit of the superplastic temperature of conventional, submicron-grain TZP materials by 150°C. The improved ductility of the TZP at low temperatures was essentially attributed to the reduced grain size.

Beschreibung: This paper introduces a flexible hardware and software architecture for a smart video sensor. This sensor has been applied in a video surveillance application where some of these video sensors are deployed, constituting the sensory nodes of a distributed surveillance system. In this system, a video sensor node processes images locally in order to extract objects of interest, and classify them. The sensor node reports the processing results to other nodes in the cloud (a user or higher level software) in the form of an XML description. The hardware architecture of each sensor node has been developed using two DSP processors and an FPGA that controls, in a flexible way, the interconnection among processors and the image data flow. The developed node software is based on pluggable components and runs on a provided execution run-time. Some basic and application-specific software components have been developed, in particular: acquisition, segmentation, labeling, tracking, classification and feature extraction. Preliminary results demonstrate that the system can achieve up to 7.5 frames per second in the worst case, and the true positive rates in the classification of objects are better than 80%.

Beschreibung: A facile synthetic strategy was implemented to obtain nanosized barium titanate ( BaTiO 3 ) powders with tetragonal structure. The nanoparticles were synthesized using solvothermal process employing diethanolamine and triethanolamine to suppress the particle growth and the as-prepared nanopowders were characterized using X-ray diffraction, scanning electron microscopy, and high-resolution dispersive Raman spectroscopy. It was found that the particle size can be easily tuned by adjusting the experimental parameters while retaining the tetragonality. The average diameters of the particles prepared with and without the organic amines were found to be 80 and 100 nm, respectively. All the synthesized BaTiO 3 nanopowders exhibit a narrow size distribution with a uniform morphology. Rietveld refinement of the XRD patterns and Raman spectra revealed that the synthesized BaTiO 3 nanopowders have tetragonal asymmetry dominant structures. A slight decrease in the tetragonality of the prepared powders with decrease in particle size is attributed to the presence of cubic shell layer and inner defects. The tetragonal-dominant structure was also confirmed by normalizing the peak area of the Raman spectra.

Beschreibung: To improve the microwave dielectric properties, CuO was doped into composite ceramics BaTi 4 O 9 – BaZn 2 Ti 4 O 11 by the solid-state reaction. CuO worked as flux former and caused the liquid-phase sintering mechanism, which effectively improved the densification process and lowered the sintering temperature by nearly 100°C. Moreover, Cu 2+ substituted for Zn 2+ sites in BaZn 2 Ti 4 O 11 phase, which led to the increase of BaZn 2 Ti 4 O 11 phase and the reduction of lattice parameters of BaZn 2 Ti 4 O 11 phase, and both these two results had the positive effect on the dielectric properties, especially the Q  ×  f value. As increasing CuO content from 0.0 to 3.0 wt%, the dielectric constant ( ε r ) increased from 35.5 to 36.5, the Q  ×  f value increased first from 49 100 GHz to the peak value 62 600 GHz (1.0 wt% CuO ) and thereafter decreased to 31 900 GHz, and the temperature coefficient of resonant frequency ( τ f ) kept in a low value as 〈2.0 wt% CuO was added. At last, 0.85 BaTi 4 O 9 –0.15 BaZn 2 Ti 4 O 11 ceramics with 1.0 wt% CuO sintered at 1150°C for 3 h showed excellent microwave dielectric properties: the high ε r  = 36.4, the high Q  ×  f = 62 600 GHz and the near-zero τ f  = +0.2 ppm/°C.

Beschreibung: A piezoelectric system of (1− x ) Bi ( Ni 1/2 Ti 1/2 ) O 3 – x ( Pb (1− y ) Sr y TiO 3 ) ( BNT–PST ) is developed to have good high temperature piezoelectric properties with much improved resistivity. The crystal structure shows that the phase transformation from tetragonal phase to rhombohedral one is gradually shifted to the composition with high content of PT by the substitution of strontium. The problem of leakage current for the Bi ( Ni , Ti ) O 3 – PbTiO 3 can be well resolved by introducing the dopant of strontium. Both dielectric loss and DC resistivity can be much reduced not only at room temperature but also high temperature. An optimum composition of 0.53 Bi ( Ni 1/2 Ti 1/2 ) O 3 –0.47( Pb 0.95 Sr 0.05 ) TiO 3 is obtained to have a good potential application of high temperature piezoelectric ( d 33  = 205 pC/N, E C  = 3.32 kV/mm, P r  = 41.2 μC/cm 2 ). Strontium could be a useful dopant for the studies on the high temperature piezoelectric ceramics in future.

Beschreibung: This paper presents a signal processing technique to improve angular rate accuracy of the gyroscope by combining the outputs of an array of MEMS gyroscope. A mathematical model for the accuracy improvement was described and a Kalman filter (KF) was designed to obtain optimal rate estimates. Especially, the rate signal was modeled by a first-order Markov process instead of a random walk to improve overall performance. The accuracy of the combined rate signal and affecting factors were analyzed using a steady-state covariance. A system comprising a six-gyroscope array was developed to test the presented KF. Experimental tests proved that the presented model was effective at improving the gyroscope accuracy. The experimental results indicated that six identical gyroscopes with an ARW noise of 6.2 °/Öh and a bias drift of 54.14 °/h could be combined into a rate signal with an ARW noise of 1.8 °/Öh and a bias drift of 16.3 °/h, while the estimated rate signal by the random walk model has an ARW noise of 2.4 °/Öh and a bias drift of 20.6 °/h. It revealed that both models could improve the angular rate accuracy and have a similar performance in static condition. In dynamic condition, the test results showed that the first-order Markov process model could reduce the dynamic errors 20% more than the random walk model.

Beschreibung: Because of their small size, passive nature, immunity to electromagnetic interference, and capability to directly measure physical parameters such as temperature and strain, fiber Bragg grating sensors have developed beyond a laboratory curiosity and are becoming a mainstream sensing technology. Recently, high temperature stable gratings based on regeneration techniques and femtosecond infrared laser processing have shown promise for use in extreme environments such as high temperature, pressure or ionizing radiation. Such gratings are ideally suited for energy production applications where there is a requirement for advanced energy system instrumentation and controls that are operable in harsh environments. This paper will present a review of some of the more recent developments.

Beschreibung: Methodologies and algorithms are presented for the secure cooperation of a team of autonomous mobile underwater sensors, connected through an acoustic communication network, within surveillance and patrolling applications. In particular, the work proposes a cooperative algorithm in which the mobile underwater sensors (installed on Autonomous Underwater Vehicles—AUVs) respond to simple local rules based on the available information to perform the mission and maintain the communication link with the network (behavioral approach). The algorithm is intrinsically robust: with loss of communication among the vehicles the coverage performance (i.e., the mission goal) is degraded but not lost. The ensuing form of graceful degradation provides also a reactive measure against Denial of Service. The cooperative algorithm relies on the fact that the available information from the other sensors, though not necessarily complete, is trustworthy. To ensure trustworthiness, a security suite has been designed, specifically oriented to the underwater scenario, and in particular with the goal of reducing the communication overhead introduced by security in terms of number and size of messages. The paper gives implementation details on the integration between the security suite and the cooperative algorithm and provides statistics on the performance of the system as collected during the UAN project sea trial held in Trondheim, Norway, in May 2011.

Beschreibung: The mean shift algorithm has achieved considerable success in target tracking due to its simplicity and robustness. However, the lack of spatial information may result in its failure to get high tracking precision. This might be even worse when the target is scale variant and the sequences are gray-levels. This paper presents a novel multiple subtemplates based tracking algorithm for the terminal guidance application. By applying a separate tracker to each subtemplate, it can handle more complicated situations such as rotation, scaling, and partial coverage of the target. The innovations include: (1) an optimal subtemplates selection algorithm is designed, which ensures that the selected subtemplates maximally represent the information of the entire template while having the least mutual redundancy; (2) based on the serial tracking results and the spatial constraint prior to those subtemplates, a Gaussian weighted voting method is proposed to locate the target center; (3) the optimal scale factor is determined by maximizing the voting results among the scale searching layers, which avoids the complicated threshold setting problem. Experiments on some videos with static scenes show that the proposed method greatly improves the tracking accuracy compared to the original mean shift algorithm.

Beschreibung: Hand-held near-infrared (NIR) optical imagers are developed by various researchers towards non-invasive clinical breast imaging. Unlike these existing imagers that can perform only reflectance imaging, a generation-2 (Gen-2) hand-held optical imager has been recently developed to perform both reflectance and transillumination imaging. The unique forked design of the hand-held probe head(s) allows for reflectance imaging (as in ultrasound) and transillumination or compressed imaging (as in X-ray mammography). Phantom studies were performed to demonstrate two-dimensional (2D) target detection via reflectance and transillumination imaging at various target depths (1–5 cm deep) and using simultaneous multiple point illumination approach. It was observed that 0.45 cc targets were detected up to 5 cm deep during transillumination, but limited to 2.5 cm deep during reflectance imaging. Additionally, implementing appropriate data post-processing techniques along with a polynomial fitting approach, to plot 2D surface contours of the detected signal, yields distinct target detectability and localization. The ability of the gen-2 imager to perform both reflectance and transillumination imaging allows its direct comparison to ultrasound and X-ray mammography results, respectively, in future clinical breast imaging studies.

Beschreibung: Studies on fault detection and diagnosis of planetary gearboxes are quite limited compared with those of fixed-axis gearboxes. Different from fixed-axis gearboxes, planetary gearboxes exhibit unique behaviors, which invalidate fault diagnosis methods that work well for fixed-axis gearboxes. It is a fact that for systems as complex as planetary gearboxes, multiple sensors mounted on different locations provide complementary information on the health condition of the systems. On this basis, a fault detection method based on multi-sensor data fusion is introduced in this paper. In this method, two features developed for planetary gearboxes are used to characterize the gear health conditions, and an adaptive neuro-fuzzy inference system (ANFIS) is utilized to fuse all features from different sensors. In order to demonstrate the effectiveness of the proposed method, experiments are carried out on a planetary gearbox test rig, on which multiple accelerometers are mounted for data collection. The comparisons between the proposed method and the methods based on individual sensors show that the former achieves much higher accuracies in detecting planetary gearbox faults.

Beschreibung: There have been only few studies to substantiate the kinematic characteristics of cursor movement. In this study, a quantitative experimental research method was used to explore the effect of moving direction on the kinematics of cursor movement in 24 typical young persons using our previously developed computerized measuring program. The results of multiple one way repeated measures ANOVAs and post hoc LSD tests demonstrated that the moving direction had effects on average velocity, movement time, movement unit and peak velocity. Moving leftward showed better efficiency than moving rightward, upward and downward from the kinematic evidences such as velocity, movement unit and time. Moreover, the unique pattern of the power spectral density (PSD) of velocity (strategy for power application) explained why the smoothness was still maintained while moving leftward even under an unstable situation with larger momentum. Moreover, the information from this cursor moving study can guide us to relocate the toolbars and icons in the window interface, especially for individuals with physical disabilities whose performances are easily interrupted while controlling the cursor in specific directions.

Beschreibung: We present a study of an electrical model of electromechanically active carbon-polymer composite (CPC) with carbide-derived carbon (CDC) electrodes. The major focus is on investigation of surface electrode behavior upon external bending of the material. We show that electrical impedance measured from the surface of the CDC-based CPC can be used to determine the curvature of the material and, hence, the tip displacement of a CPC laminate in a cantilever configuration. It is also shown that by measuring surface signals in the process of an actuator’s work-cycle, we obtain a self-sensing collision-detecting CPC actuator that can be considered as a counterpart of biomimetic vibrissae.

Beschreibung: The detection of bridging tetrahedra, or Q 2 (L), in the silica chains constituting C – S – H gels is controversial. While some authors maintain that 29 Si MAS - NMR can be used to distinguish between Q 1 and Q 2 units but not between the silicon environments associated with Q 2 (intermediate position) and Q 2 (L) (intermediate and bridging position) units, others claim the contrary. The present article addresses this issue with a report on 29 Si MAS - NMR studies of a number of calcium silicate hydrate gels. The findings showed that nuclear magnetic resonance can differentiate between Q 2 and Q 2 (L) units in highly polymerized C – S – H gels with mean chain lengths (MCL) of over 12 and Ca / Si ratios of 〈1. At higher Ca / Si ratios, however, the MCL declined, with the concomitant rise in Q 1 units. Under these conditions, in which it was practically impossible to distinguish between Q 2 and Q 2 (L), the presence of a single signal for all Q 2 units was assumed.

Beschreibung: In Underwater Wireless Sensor Networks (UWSNs), localization is one of most important technologies since it plays a critical role in many applications. Motivated by widespread adoption of localization, in this paper, we present a comprehensive survey of localization algorithms. First, we classify localization algorithms into three categories based on sensor nodes’ mobility: stationary localization algorithms, mobile localization algorithms and hybrid localization algorithms. Moreover, we compare the localization algorithms in detail and analyze future research directions of localization algorithms in UWSNs.

Beschreibung: The non-isothermal crystallization kinetics of the strontium zinc silicate (SZS) glasses, having composition 51 SrO -9 ZnO -40 SiO 2 (wt%), was studied using the differential thermal analysis (DTA). Glasses prepared by quenching the melt in air, were subjected to different heat treatments for studying the crystallization behavior. Formation of crystalline phases and microstructure were studied by using powder X-ray diffraction and scanning electron microscopy. The activation energy and mechanism of crystallization were determined according to Kissinger, Ozawa and Matusita-Sakka equations. The DTA exotherm observed at around 920°C consists of two overlapping crystallization peaks corresponding to two different crystalline phases. Strontium silicate ( Sr 3 Si 3 O 9 ) and SZS ( Sr 2 ZnSi 2 O 7 ) phases crystallize almost simultaneously as major phases. The activation energies for the these crystallization peaks are 700 kJ/mol and 704 kJ/mol. Higher activation energies indicate that the kinetics are more thermally activated making the control of crystallization more difficult. The values of growth morphology parameters n (Avarami parameter) and m (dimensionality of crystal growth) suggest a diffusion controlled bulk crystallization with three- and two-dimensional growth. This is also confirmed by an interconnected growth of stubby granular/prismatic shaped crystals in the glass-ceramic. The microstructural evolution of the glass upon heating suggests the occurrence of phase separation with an apparently spinodal decomposition mechanism prior to the crystallization.

Beschreibung: A facile starch-assisted sol–gel method combined with freeze-drying technique has been developed to synthesize K -doped Li 2 ZrO 3 sorbents. SEM, TEM, and XRD techniques have been applied to characterize the morphology and structure of the synthesized K -doped Li 2 ZrO 3 samples. The CO 2 capture-regeneration properties of the prepared K -doped Li 2 ZrO 3 sample were investigated using thermogravimetric analysis at different CO 2 partial pressures. The K -doped Li 2 ZrO 3 synthesized using the starch-assisted sol–gel method combined with the freeze-drying technique shows excellent CO 2 capture properties. At 823 K and a CO 2 partial pressure of 0.25 bar, the uptake of CO 2 reaches 22 wt% within 20 min, which is approximately 87% of the stoichiometric sorption capacity (25.3 wt%) of CO 2 in the K -doped Li 2 ZrO 3 with a K : Li : Zr composition of 0.2:1.6:1 in molar ratio. Furthermore, the sorbent shows a good stability, confirmed using capture-regeneration cycles.

Beschreibung: This paper describes the characteristics of optical fiber sensors with surface plasmon resonance (SPR) at 1,310 nm in which the scattering loss of silica optical fiber is low. SPR operation in the infrared wavelength range is achieved by coating a thin tantalum pentaoxide (Ta2O5) film. The novelty of this paper lies in the verification of how the hetero-core scheme could be operated as a commercial base candidate in the sense of easy fabrication, sufficient mechanical strength, and significant sensitivity as a liquid detector under the basis of a low loss transmission network in the near infrared wavelength region. The effect of Ta2O5 layer thickness has been experimentally revealed in the wavelength region extending to 1,800 nm by using the hetero-core structured optical fiber. SPR characterizations have been made in the wavelength region 1,000–1,300 nm, showing the feasible operation at the near infrared wavelength and the possible practical applications. In addition, the technique developed in this work has been interestingly applied to a multi-point water-detection and a water-level gauge in which tandem-connected SPR sensors system using hetero-core structured fibers were incorporated. The detailed performance characteristics are also shown on these applications.

Beschreibung: Wireless Sensor Networks (WSNs) are gaining tremendous importance thanks to their broad range of commercial applications such as in smart home automation, health-care and industrial automation. In these applications multi-vendor and heterogeneous sensor nodes are deployed. Due to strict administrative control over the specific WSN domains, communication barriers, conflicting goals and the economic interests of different WSN sensor node vendors, it is difficult to introduce a large scale federated WSN. By allowing heterogeneous sensor nodes in WSNs to coexist on a shared physical sensor substrate, virtualization in sensor network may provide flexibility, cost effective solutions, promote diversity, ensure security and increase manageability. This paper surveys the novel approach of using the large scale federated WSN resources in a sensor virtualization environment. Our focus in this paper is to introduce a few design goals, the challenges and opportunities of research in the field of sensor network virtualization as well as to illustrate a current status of research in this field. This paper also presents a wide array of state-of-the art projects related to sensor network virtualization.

Beschreibung: Gait analysis using wearable sensors is an inexpensive, convenient, and efficient manner of providing useful information for multiple health-related applications. As a clinical tool applied in the rehabilitation and diagnosis of medical conditions and sport activities, gait analysis using wearable sensors shows great prospects. The current paper reviews available wearable sensors and ambulatory gait analysis methods based on the various wearable sensors. After an introduction of the gait phases, the principles and features of wearable sensors used in gait analysis are provided. The gait analysis methods based on wearable sensors is divided into gait kinematics, gait kinetics, and electromyography. Studies on the current methods are reviewed, and applications in sports, rehabilitation, and clinical diagnosis are summarized separately. With the development of sensor technology and the analysis method, gait analysis using wearable sensors is expected to play an increasingly important role in clinical applications.

Beschreibung: During the last years, proteomics has facilitated biomarker discovery by coupling high-throughput techniques with novel nanosensors. In the present review, we focus on the study of label-based and label-free detection systems, as well as nanotechnology approaches, indicating their advantages and applications in biomarker discovery. In addition, several disease biomarkers are shown in order to display the clinical importance of the improvement of sensitivity and selectivity by using nanoproteomics approaches as novel sensors.

Beschreibung: The photoplethysmographic waveform sits at the core of the most used, and arguably the most important, clinical monitor, the pulse oximeter.  Interestingly, the pulse oximeter was discovered while examining an artifact during the development of a noninvasive cardiac output monitor.  This article will explore the response of the pulse oximeter waveform to various modes of ventilation.  Modern digital signal processing is allowing for a re-examination of this ubiquitous signal. The effect of ventilation on the photoplethysmographic waveform has long been thought of as a source of artifact. The primary goal of this article is to improve the understanding of the underlying physiology responsible for the observed phenomena, thereby encouraging the utilization of this understanding to develop new methods of patient monitoring. The reader will be presented with a review of respiratory physiology followed by numerous examples of the impact of ventilation on the photoplethysmographic waveform.

Beschreibung: Fully dense nanocrystalline MgO -based ceramics were consolidated by field and pressure assisted sintering (also known as Spark Plasma Sintering) using anhydrous nanosized powders (~5 nm) prepared by laser ablation and handled in a controlled, water-free environment prior to sintering. The high reactivity of the powders promoted excellent sinterability at relatively low temperatures. Highly transparent specimens were produced by sintering at 0.23–0.28 T m (650°C–800°C) for 15–30 min with good control over the final nanometric grain size. To preserve the nanocrystalline nature of the samples, the high temperature exposure time during sintering was reduced by the application of 300 MPa uniaxial pressure; higher pressure or two-step procedures did not provide extra benefits to densification or microstructural control.

Beschreibung: Two innovative glass compositions based on the commonly used 45S5 Bioglass ® were developed by increasing the calcium quantity and replacing the sodium oxide with a specific content of potassium oxide. The new glasses, named BG_ Ca / K and BG _ Ca /Mix, can be prepared using a conventional melting process and show a very low tendency to crystallize. Thanks to this peculiarity, BG_ Ca / K and BG_ Ca /Mix powders can be sintered at a relatively low temperature (800°C) to obtain samples of high compactness and bioactivity, since their amorphous nature is preserved. Consequently, the proposed glasses are perfect for making specific products such as scaffolds or hydroxyapatite-based composites. Furthermore, the relatively low alkali amount in the new compositions gives rise to a slow ion leaching in simulated body fluid, thus avoiding abrupt changes in pH that can damage osteoblasts or negatively affect their behavior.

Beschreibung: For decades, underwater acoustic communication has been restricted to the point-to-point long distance applications such as deep sea probes and offshore oil fields. For this reason, previous acoustic modems were typically characterized by high data rates and long working ranges at the expense of large size and high power consumption. Recently, as the need for underwater wireless sensor networks (UWSNs) has increased, the research and development of compact and low-power consuming communication devices has become the focus. From the consideration that the requisites of acoustic modems for UWSNs are low power consumption, omni-directional beam pattern, low cost and so on, in this paper, we design and implement an omni-directional underwater acoustic micro-modem satisfying these requirements. In order to execute fast digital domain signal processing and support flexible interfaces with other peripherals, an ARM Cortex-M3 is embedded in the micro-modem. Also, for the realization of small and omni-directional properties, a spherical transducer having a resonant frequency of 70 kHz and a diameter of 34 mm is utilized for the implementation. Physical layer frame format and symbol structure for efficient packet-based underwater communication systems are also investigated. The developed acoustic micro-modem is verified analytically and experimentally in indoor and outdoor environments in terms of functionality and performance. Since the modem satisfies the requirements for use in UWSNs, it could be deployed in a wide range of applications requiring underwater acoustic communication.

Beschreibung: Solid solution effects on thermal conductivity within the MgO – Al 2 O 3 – Ga 2 O 3 system were studied. Samples with systematically varied additions of MgGa 2 O 4 – MgAl 2 O 4 were prepared and the laser flash technique was used to determine thermal diffusivity at temperatures between 200°C and 1300°C. Heat capacity as a function of temperature from room temperature to 800°C was also determined using differential scanning calorimetry (DSC). Solid solution in the MgAl 2 O 4 – MgGa 2 O 4 system decreases the thermal conductivity up to 1000°C. At 200°C thermal conductivity decreased 24% with a 5 mol% addition of MgGa 2 O 4 to the system. At 1000°C, the thermal conductivity decreased 13% with a 5 mol% addition. Steady-state calculations showed a 12.5% decrease in heat flux with 5 mol% MgGa 2 O 4 considered across a 12 inch thickness.

Beschreibung: The presence of leachable alkali ions, or their hydrated sites in the glass, is believed to be a determining factor for the interfacial water structure at the glass surface, influencing the surface properties of glass. The interfacial water structure on soda-lime silicate glass in humid ambience at room temperature was analyzed with sum-frequency-generation (SFG) vibration spectroscopy, which can probe the interfacial water layer without spectral interferences from the gas phase water. The soda-lime glass surface exposed to water vapor shows three sharp SFG peaks at 3200, 3430, and 3670 cm −1 in SFG, which is drastically different from the SFG spectra of the water layers on the fused quartz glass surface and the liquid water/air interface. The sharp peak at 3200 cm −1 is believed to be associated with the hydronium ions in the Na + -leached silicate glass surface. The 3200 cm −1 peak intensity varies with the relative humidity, indicating its equilibrium with the gas phase water. It is proposed that the hydronium ions in the Na + -leached sites produce compressive stress in the silicate glass surface; thus the growth of hydronium ions with increasing humidity might be responsible for the increased wear resistance of soda-lime glass surfaces in near-saturation humidity conditions.

Beschreibung: We introduce a novel method to produce macroporous ceramics by capillary suspensions. Adding a small amount (~1 vol%) of an immiscible secondary phase to a low concentration (~20 vol%) suspension can increase the yield stress by several orders of magnitude. This drastic change in flow behavior is induced by the creation of a sample-spanning particle network in the suspension controlled by capillary forces. This strong network may persist even if the primary bulk phase is removed. Accordingly, capillary suspensions can be used as a precursor for manufacturing porous materials. Here, we focus on the specific features of this universal, low-cost processing route for porous ceramics. An Al 2 O 3 model system is used to demonstrate how to adjust porosity and pore size. With this system, we were able to achieve open porosities higher than 60% with an average pore size below 10 μm.

Beschreibung: Binary metal oxides occur in different polymorphic states under applied pressure and temperature. Structural changes occur due to polymorphic transitions in binary metal oxides. It is essential to theoretically predict the conditions of polymorphic transitions so that materials can be effectively used in engineering applications. Temperature and pressure are the two main factors affecting the bulk state phase transformation of materials. For nanomaterials, it has been observed that particle size and temperature are the main factors affecting the phase transformation, e.g., γ- Fe 2 O 3 to α- Fe 2 O 3 , monoclinic to orthorhombic transformation in MoO 3 , anatase to rutile transformation in Titania, γ to α Alumina transformation. We compile from literature the main factors which affect the phase stability of a nanocrystalline binary metal oxide. A heuristic approach to formulate particle size is put forth. Factors like surface energy, surface tension, and particle shape are considered, and a value for critical particle size is formulated. The model fits well with the experimental results for nanocrystalline alumina, titania, zirconia, and Fe 2 O 3 . Such an approach can be applied to predict the particle size-dependent stability of a phase at known temperature range.

Beschreibung: This work revealed that the solid solution compounds of Sr 2 − x Ba x Nb 2 O 7 are promising lead-free materials for high-temperature piezoelectric sensor application. These compounds were confirmed as ferroelectric materials with high Curie points ( 〉 900°C) by their piezoelectric activity after poling, ferroelectric domain switching in their P – E hysteresis loops and thermal depoling behavior. The effect of Ba substitution on the structure and properties of Sr 2 − x Ba x Nb 2 O 7 ( x  〈  1.0) was investigated. The solid solution limit of Sr 2 − x Ba x Nb 2 O 7 was determined by XRD as x  〈 0.6. The a -, b -, c - axes, and cell volume increase with Ba addition. The textured ceramics of Sr 2 − x Ba x Nb 2 O 7 were prepared for the first time. The highest d 33 was measured as 3.6  ±  0.1 pC/N for Sr 1.8 Ba 0.2 Nb 2 O 7 .

Beschreibung: Containerless levitation technique, where the undercooling can be treated as one of the major thermodynamic parameters, was used to study the influence of oxygen partial pressure ( ) on the microstructure and physical properties of rare-earth orthoferrites RFeO 3 (where R = Rare-earth element) in the ranges from 10 5 to 10 −1  Pa. The microstructure of the as-solidified samples changed into orthorhombic RFeO 3 ( o - RFeO 3 ), metastable hexagonal RFeO 3 ( h - RFeO 3 ), and Fe 2+ -containing RFe 2 O 4 and a new metastable R 3 Fe 2 O 7 phases with decreasing . The effect of on the magnetic properties was indicated as that the saturation magnetization gradually increased for R = La to Yb and decreased for R = Lu with decreasing due to the formation of metastable and magnetic phases such as Fe 3 O 4 and Fe .

Beschreibung: The rapid densification behavior of 8 mol% Y 2 O 3 -stabilized ZrO 2 polycrystalline (8 Y -SZP) powder compacts at the initial stage of pressure sintering (relative density ( ) below 0.92) has been investigated using an electric current-activated/assisted sintering (ECAS) system. Data points corresponding to a fixed heating rate were extracted from the densification rate ( ) versus ρ and versus temperature ( T ) curves. These curves were obtained experimentally by consolidation at a fixed current. Under fixed current ECAS, the heating rate ( ) decreases continuously over sintering time. Using a quasi- constant heating rate (CHR) method, data points were extracted to plot vs. ρ, vs. T , and ρ vs. T curves at a fixed . The stress exponent ( n ), estimated from a log-log plot of grain size ( d )-corrected /ρ and effective stress (σ eff ) at 1300–1400 K, shows an almost constant value of 1. In addition, the activation energy ( Q ) for rapid densification, estimated from an Arrhenius plot of d -corrected /ρ also shows an almost constant value of 350 kJ/mol, which is considerably lower than the previously reported value of the activation energy for Zr 4+ lattice diffusion of about 440 kJ/mol. These results suggest that rapid densification of 8 Y -SZP by ECAS seems to proceed by diffusional creep controlled by grain-boundary diffusion of Zr 4+ ions.

Beschreibung: This study examines an analog circuit comprising a multilayer perceptron neural network (MLPNN). This study proposes a low-power and small-area analog MLP circuit to implement in an E-nose as a classifier, such that the E-nose would be relatively small, power-efficient, and portable. The analog MLP circuit had only four input neurons, four hidden neurons, and one output neuron. The circuit was designed and fabricated using a 0.18 μm standard CMOS process with a 1.8 V supply. The power consumption was 0.553 mW, and the area was approximately 1.36 × 1.36 mm2. The chip measurements showed that this MLPNN successfully identified the fruit odors of bananas, lemons, and lychees with 91.7% accuracy.

Beschreibung: We present a novel system for detection, localization and tracking of multiple people, which fuses a multi-view computer vision approach with a radio-based localization system. The proposed fusion combines the best of both worlds, excellent computer-vision-based localization, and strong identity information provided by the radio system, and is therefore able to perform tracking by identification, which makes it impervious to propagated identity switches. We present comprehensive methodology for evaluation of systems that perform person localization in world coordinate system and use it to evaluate the proposed system as well as its components. Experimental results on a challenging indoor dataset, which involves multiple people walking around a realistically cluttered room, confirm that proposed fusion of both systems significantly outperforms its individual components. Compared to the radio-based system, it achieves better localization results, while at the same time it successfully prevents propagation of identity switches that occur in pure computer-vision-based tracking.

Beschreibung: Measuring bone turnover markers could detect early stages of osteoporosis and early responses to anti-osteoporotic treatments. Currently, commonly used bone turnover markers, N-telopeptides (NTx) and C-telopeptides (CTx), are measured using ELISA tests, which demands time and increases cost. Bone turnover markers need to be measured more easily for general use. Lateral flow-based immunoassay would be an appropriate method for this context. This study was performed to investigate the precision of a newly developed lateral flow-based immunoassay for measuring the urinary NTx and serum CTx, and their correlations with ELISA measurements. Urine NTx and serum CTx concentrations were determined by photoscan of newly developed strips, using a lateral flow-based immunoassay for 36 subjects (mean age 66.2 years, SD 7.5 years; four males and 32 females). Repeated measurement of urinary NTx and serum CTx were performed three times, using this technology for a precision test. The correlation of the lateral flow-based immunoassay with the ELISA measurements was analyzed. Precision of the newly developed lateral flow based immunoassay was 0.974 (ICC, 95% confidence interval, 0.955 to 0.986) and 0.995 (ICC, 95% confidence interval, 0.991 to 0.997) for urinary NTx and serum CTx, respectively. The correlation of lateral flow based immunoassay with ELISA was 0.913 for urinary NTx and 0.872 for serum CTx. These results suggest that measuring the urinary NTx and serum CTx, using a lateral flow-based immunoassay, is a relevant method for point-of-care testing and screening of bone resorption markers.

Beschreibung: To enhance the control performance of permanent magnet synchronous motors (PMSMs), a generalized predictive control (GPC)-based proportional integral feedforward (PIF) controller is proposed for the speed control system. In this new approach, firstly, based on the online identification of controlled model parameters, a simplified GPC law supplies the PIF controller with suitable control parameters according to the uncertainties in the operating conditions. Secondly, the speed reference curve for PMSMs is usually required to be continuous and continuously differentiable according to the general servo system design requirements, so the adaptation of the speed reference is discussed in details in this paper. Hence, the performance of the speed control system using a GPC-based PIF controller is improved for tracking some specified signals. The main motivation of this paper is the extension of GPC law to replace the traditional PI or PIF controllers in industrial applications. The efficacy and usefulness of the proposed controller are verified through experimental results.

Beschreibung: Wine quality is related to its intrinsic visual, taste, or aroma characteristics and is reflected in the price paid for that wine. One of the most important wine faults is the excessive concentration of acetic acid which can cause a wine to take on vinegar aromas and reduce its varietal character. Thereby it is very important for the wine industry to have methods, like electronic noses, for real-time monitoring the excessive concentration of acetic acid in wines. However, aroma characterization of alcoholic beverages with sensor array electronic noses is a difficult challenge due to the masking effect of ethanol. In this work, in order to detect the presence of acetic acid in synthetic wine samples (aqueous ethanol solution at 10% v/v) we use a detection unit which consists of a commercial electronic nose and a HSS32 auto sampler, in combination with a neural network classifier (MLP). To find the characteristic vector representative of the sample that we want to classify, first we select the sensors, and the section of the sensors response curves, where the probability of detecting the presence of acetic acid will be higher, and then we apply Principal Component Analysis (PCA) such that each sensor response curve is represented by the coefficients of its first principal components. Results show that the PEN3 electronic nose is able to detect and discriminate wine samples doped with acetic acid in concentrations equal or greater than 2 g/L.

Beschreibung: The various applications of transparent conducting oxides (TCO), e.g., as electrodes in flat panel displays and solar cells or as low-emissivity coatings have stimulated extensive research on their fabrication and properties. Recent experimental and theoretical studies of defect properties have considerably improved the understanding of the limitations of the electrical conductivity of both n - and p -type transparent conductors and of the structural and electronic surface properties of the most important TCO materials. Development of emerging and future applications in the area of transparent thin film electronics with oxide semiconductors as well as the improvement of existing applications require a detailed control of the Fermi level position in the bulk and at surfaces and interfaces of polycrystalline and amorphous TCO materials. This feature article describes how the important parameters for such control can be identified using photoelectron spectroscopy with in situ sample preparation. The parameters influencing doping, work functions, ionization potentials, and surface band bending as well as energy band alignment at interfaces are described and discussed providing a fundamental understanding of important material properties for tailoring TCOs in electronic devices.

Beschreibung: Highly orientated Co -doped Zn ( Mg , Cd ) O thin films have been prepared on Si (001) substrate using pulsed laser deposition (PLD). Our results indicate that Mg and Cd -doping can tune the bandgap of ZnO thin film. Apparent room-temperature ferromagnetism is observed in these films, which can be modified by the bandgap of ZnO . A narrow bandgap enhances the ferromagnetism of the films through the Cd -doping, and wide bandgap does the opposite through the Mg-doping, which may be ascribed to the ferromagnetic (FM) exchange interaction between the 3 d states of magnetic Co ions and the impurity band. These experimental results provide some new evidence that the ferromagnetism in Co : ZnO is closely related to crystal defects and improve our knowledge about ferromagnetism in dilute magnetic oxides.

Beschreibung: Nanocrystalline TiO 2 and Ti 1− x V x O 2 ( x  = 0.01) powders have been prepared by thermal decomposition, in air, of amorphous precursors resulting from the freeze-drying of appropriate solutions. In addition, TiO 2− x N y (anatase and rutile) and Ti O x N y (rock-salt) have been prepared by thermal treatment in ammonia of a crystalline precursor ( TiO 2 obtained at 673 K). TEM and SEM images, as well as the analysis of the X-ray diffraction (XRD) patterns, show the nanoparticulated character of those solids obtained at low temperatures, with typical particle sizes in the 10–20 nm range when prepared at 673 K. The UV–Vis results indicate both the insertion of V in the anatase lattice and the feasibility of nitridation at low temperatures. The photocatalytic properties of these materials (as prepared and after their incorporation to mortar samples) in the degradation of nitrogen oxides have been preliminary evaluated. Although N-doping enhances the photocatalytic activity of the TiO 2 matrix, V-doping worsens it.

Beschreibung: Two processing methods were successfully combined to obtain Ag-modified calcium phosphate scaffolds with antibacterial properties: (i) hydrothermal conversion of macroporous biogenic carbonates and (ii) vapor transport sintering. Hydrothermal conversion of two precursor materials, i.e., coral skeletons and sea urchin spines, resulted in the pseudomorphic replacement of highly porous calcium carbonates by calcium phosphate scaffolds. Vapor transport sintering of these scaffolds within a reactive AgCl atmosphere facilitated near net-shape processing accompanied by the condensation of finely dispersed Ag -bearing particles over the scaffold's surface. Chemical and phase compositions were analyzed using WDXRF, XRD, and DRIFTS (FTIR), and the microstructure development was characterized by SEM and TEM imaging. The dissolution kinetics of Ag + ions in aqueous solution was determined and growth inhibition experiments with Gram-positive and Gram-negative bacteria were performed to assess the antibacterial properties of Ag -modified ceramics.

Beschreibung: Electric field-induced magnetization characteristics are demonstrated in (100− x ) NaNbO 3 – x NiFe 2 O 4 ( x  = 15, 25, 35, 45), synthesized by the solid-state sintering method. The composites show well-defined ferroelectric behaviors and magnetic characteristics. The CME effect characteristics with driving frequency in a range 10 k – 15 kHz were investigated at room temperature. The CME couplings increase initially with increasing the driving frequencies and then decrease with the further increase in the frequency. Large CME coefficients are obtained at electromechanical resonance frequency of 12.8 kHz. These lead-free multiferroic composites exhibiting electrostatically induced ME resonance provide great opportunities for electric field-tunable microwave devices.

Beschreibung: A sucrose-mediated aqueous sol–gel procedure was developed to synthesize MgO – Y 2 O 3 nanocomposite ceramics for potential optical applications. The synthesis involves the generation of a precursor foam containing Mg 2+ and Y 3+ cations via the chemical and thermal degradation of sucrose molecules in aqueous solution. Subsequent calcination and crushing of the foam gave MgO – Y 2 O 3 nanocomposites in the form of thin mesoporous flake-like powder particles with uniform composition and surface areas of 27–85 m 2  g − 1 , depending on calcination conditions. The flakes exhibited a homogeneous microstructure comprising intimately mixed nanoscale grains of the cubic MgO and Y 2 O 3 phases. This microstructure was resistant to grain coarsening with average grain sizes of less than 100 nm for calcination temperatures of up to 1200°C. The results indicate that the sucrose-mediated sol–gel process is a simple effective method for making nanoscale mixed oxides.

Beschreibung: Perfumes are manufactured by mixing odorous materials with different volatilities. The parameter that measures the lasting property of a material when applied on the skin is called substantivity or tenacity. It is well known by perfumers that citrus and green notes are perceived as fresh and they tend to evaporate quickly, while odors most dissimilar to ‘fresh’ (e.g., oriental, powdery, erogenic and animalic scents) are tenacious. However, studies aimed at quantifying the relationship between fresh odor quality and substantivity have not received much attention. In this work, perceptual olfactory ratings on a fresh scale, estimated in a previous study, were compared with substantivity parameters and antierogenic ratings from the literature. It was found that the correlation between fresh odor character and odorant substantivity is quite strong (r = −0.85). ‘Fresh’ is sometimes interpreted in perfumery as ‘cool’ and the opposite of ‘warm’. This association suggests that odor freshness might be somehow related to temperature. Assuming that odor perception space was shaped throughout evolution in temperate climates, results reported here are consistent with the hypothesis that ‘fresh’ evokes scents typically encountered in the cool season, while ‘warm’ would be evoked by odors found in nature during summer. This hypothesis is rather simplistic but it may provide a new insight to better understand the perceptual space of scents.

Beschreibung: A new electronic tongue to monitor the presence of glyphosate (a non-selective systemic herbicide) has been developed. It is based on pulse voltammetry and consists in an array of three working electrodes (Pt, Co and Cu) encapsulated on a methacrylate cylinder. The electrochemical response of the sensing array was characteristic of the presence of glyphosate in buffered water (phosphate buffer 0.1 mol·dm−3, pH 6.7). Rotating disc electrode (RDE) studies were carried out with Pt, Co and Cu electrodes in water at room temperature and at pH 6.7 using 0.1 mol·dm−3 of phosphate as a buffer. In the presence of glyphosate, the corrosion current of the Cu and Co electrodes increased significantly, probably due to the formation of Cu2+ or Co2+ complexes. The pulse array waveform for the voltammetric tongue was designed by taking into account some of the redox processes observed in the electrochemical studies. The PCA statistical analysis required four dimensions to explain 95% of variance. Moreover, a two-dimensional representation of the two principal components differentiated the water mixtures containing glyphosate. Furthermore, the PLS statistical analyses allowed the creation of a model to correlate the electrochemical response of the electrodes with glyphosate concentrations, even in the presence of potential interferents such as humic acids and Ca2+. The system offers a PLS prediction model for glyphosate detection with values of 098, −2.3 × 10−5 and 0.94 for the slope, the intercept and the regression coefficient, respectively, which is in agreement with the good fit between the predicted and measured concentrations. The results suggest the feasibility of this system to help develop electronic tongues for glyphosate detection.

Beschreibung: Monitoring tropical deforestation and forest degradation is one of the central elements for the Reduced Emissions from Deforestation and Forest Degradation in developing countries (REDD+) scheme. Current arrangements for monitoring are based on remote sensing and field measurements. Since monitoring is the periodic process of assessing forest stands properties with respect to reference data, adopting the current REDD+ requirements for implementing monitoring at national levels is a challenging task. Recently, the advancement in Information and Communications Technologies (ICT) and mobile devices has enabled local communities to monitor their forest in a basic resource setting such as no or slow internet connection link, limited power supply, etc. Despite the potential, the use of mobile device system for community based monitoring (CBM) is still exceptional and faces implementation challenges. This paper presents an integrated data collection system based on mobile devices that streamlines the community-based forest monitoring data collection, transmission and visualization process. This paper also assesses the accuracy and reliability of CBM data and proposes a way to fit them into national REDD+ Monitoring, Reporting and Verification (MRV) scheme. The system performance is evaluated at Tra Bui commune, Quang Nam province, Central Vietnam, where forest carbon and change activities were tracked. The results show that the local community is able to provide data with accuracy comparable to expert measurements (index of agreement greater than 0.88), but against lower costs. Furthermore, the results confirm that communities are more effective to monitor small scale forest degradation due to subsistence fuel wood collection and selective logging, than high resolution remote sensing SPOT imagery.

Beschreibung: As research continues, the control on the polymorph and morphology of calcium carbonate ( CaCO 3 ) becomes a hot topic because its application is limited by these parameters. The polymorph and morphology control of CaCO 3 was successfully achieved via temperature and PEG ( M w  = 6000) during the decomposition of Ca ( HCO 3 ) 2 , which has rarely been employed to prepare precipitated CaCO 3 . As-prepared CaCO 3 was characterized using XRD and SEM. In the case of no PEG, rhombohedra calcite, lamellar vaterite, rod- and needlelike aragonite are observed, and calcite is the major phase at all samples and it increases with temperature, whereas vaterite and aragonite decrease with temperature. The addition of PEG restrains the formation of vaterite and promotes the emergence of needlelike aragonite particles at 70°C, and prevents the generation of calcite and encourages the production of rodlike aragonite particles at 80°C and 90°C. This work not only provides a new way on the preparation of CaCO 3 powder but also presents the feasible control method in this route.

Beschreibung: We have synthesized a partially nitridated Ca 13.7 Eu 0.3 Mg 2 Si 8 O 32 (CMSN: Eu 2+ ) using Si 3 N 4 with a conventional solid-state reaction and successfully determined the structural parameters by a combined Rietveld refinement method. The partial nitridation of Ca 13.7 Eu 0.3 Mg 2 Si 8 O 32 (CMS: Eu 2+ ) led to a large enhancement in the luminescence intensity, as much as 148%. From the Rietveld refinement results, the anisotropic changes of the lattice parameters were observed for the partially nitridated samples. By incorporating this phosphor + red phosphor with an encapsulant on an InGaN light-emitting diode (LED) (λ max  = 395 nm), white light with a color rendering index of 92 and a color temperature of 5320 K under 20 mA was obtained.

Beschreibung: In March 2012, a group of researchers met to discuss emerging topics in ceramic science and to identify grand challenges in the field. By the end of the workshop, the group reached a consensus on eight challenges for the future:—understanding rare events in ceramic microstructures, understanding the phase-like behavior of interfaces, predicting and controlling heterogeneous microstructures with unprecedented functionalities, controlling the properties of oxide electronics, understanding defects in the vicinity of interfaces, controlling ceramics far from equilibrium, accelerating the development of new ceramic materials, and harnessing order within disorder in glasses. This paper reports the outcomes of the workshop and provides descriptions of these challenges.

Beschreibung: The BiOCl / Ag 3 PO 4 composites have been prepared via a facile and reproducible route. In the composite, Ag 3 PO 4 particles are deposited on the surface of plates of BiOCl . Among the as-prepared samples, the ultraviolet (UV) and visible light photocatalytic reaction rates of BiOCl / Ag 3 PO 4 composite with the ratio of 1:0.1 are about 4.4 times and 4.5 times than that of pure BiOCl , respectively. Overall, the BiOCl / Ag 3 PO 4 composites not only show highly enhanced visible light photocatalytic activity but also exhibit highly improved UV photocatalytic activity, which could find enormous potential application in addressing environmental protection issues utilizing solar energy effectively.

Beschreibung: Porous yttria-stabilized zirconia (YSZ) ceramics were fabricated using tert-butyl alcohol (TBA)-based gelcasting with monodisperse polymethylmethacrylate (PMMA) microspheres as both pore-forming agent and lubricant agent. The TBA-based slurry of 50 vol% solid loading with excellent rheological properties appropriate for casting was successfully prepared by using a commercial polymer dispersant DISPERBYK-163 as both dispersant and stabilizer. The distribution of the spherical pores made from PMMA microspheres was very homogeneous. Their average diameter decreased from 16.9 to 15.7 μm when the sintering temperature was increased from 1350°C to 1550°C. The compressive strength increased from 14.57 to 142.29 MPa and the thermal conductivity changed from 0.17 to 0.65 W/m·K when the porosity decreased from 71.6% to 45.1%. The results show that this preparation technology can make all the main factors controllable, such as the porosity, the size and shape of pores, the distribution of pores, and the thickness and density of pore walls. This is significant for fabricating porous ceramics with both high compressive strength and low thermal conductivity.

Beschreibung: Improving the high-temperature strength and stiffness of Ti 3 SiC 2 is the task of many investigations. However, methods for high-temperature strengthening have not been established although various ways are applicable to enhance the room-temperature mechanical properties of Ti 3 SiC 2 . In this work, we report that significant strengthening was realized at both room and high temperatures by incorporating a small amount of W into Ti 3 ( Si , Al ) C 2 . The onsite temperature for the rapid degradation of stiffness and strength moved more than 150°C upward to over 1200°C. The flexural strength of 5 at.% W -doped Ti 3 ( Si , Al ) C 2 is 632.9 MPa at RT and 285 MPa at 1200°C, being 176% and 170% of those for baseline material, respectively.

Beschreibung: Lanthanum zirconate has been prepared via a new chemical synthesis method by combining sol–gel processing and complex precipitation. The synthesis was carried out in aqueous solution under ambient conditions. The synthesized powder possessed the pyrochlore superstructure upon calcination above 1200°C. A suite of characterization techniques, including FTIR, Raman, X-ray and electron diffraction, TEM, SEM, and nitrogen sorption were employed to investigate the microstructural evolution and bulk properties. Dense ceramics (〉90% relative density) were obtained after sintering at 1400°C, without need for additional processing (i.e., hot or cold isostatic pressing) or any milling steps. A mechanism has been proposed that elucidates molecular assembly of this chemical synthesis method.

Beschreibung: Nowadays, optical sensors are used to digitize sculptural artworks by exploiting various contactless technologies. Cultural Heritage applications may concern 3D reconstructions of sculptural shapes distinguished by small details distributed over large surfaces. These applications require robust multi-view procedures based on aligning several high resolution 3D measurements. In this paper, the integration of a 3D structured light scanner and a stereo photogrammetric sensor is proposed with the aim of reliably reconstructing large free form artworks. The structured light scanner provides high resolution range maps captured from different views. The stereo photogrammetric sensor measures the spatial location of each view by tracking a marker frame integral to the optical scanner. This procedure allows the computation of the rotation-translation matrix to transpose the range maps from local view coordinate systems to a unique global reference system defined by the stereo photogrammetric sensor. The artwork reconstructions can be further augmented by referring metadata related to restoration processes. In this paper, a methodology has been developed to map metadata to 3D models by capturing spatial references using a passive stereo-photogrammetric sensor. The multi-sensor framework has been experienced through the 3D reconstruction of a Statue of Hope located at the English Cemetery in Florence. This sculptural artwork has been a severe test due to the non-cooperative environment and the complex shape features distributed over a large surface.

Beschreibung: Appliance Load Monitoring (ALM) is essential for energy management solutions, allowing them to obtain appliance-specific energy consumption statistics that can further be used to devise load scheduling strategies for optimal energy utilization. Fine-grained energy monitoring can be achieved by deploying smart power outlets on every device of interest; however it incurs extra hardware cost and installation complexity. Non-Intrusive Load Monitoring (NILM) is an attractive method for energy disaggregation, as it can discern devices from the aggregated data acquired from a single point of measurement. This paper provides a comprehensive overview of NILM system and its associated methods and techniques used for disaggregated energy sensing. We review the state-of-the art load signatures and disaggregation algorithms used for appliance recognition and highlight challenges and future research directions.

Beschreibung:  A variety of microrobots have commonly been used in the fields of biomedical engineering and underwater operations during the last few years. Thanks to their compact structure, low driving power, and simple control systems, microrobots can complete a variety of underwater tasks, even in limited spaces. To accomplish our objectives, we previously designed several bio-inspired underwater microrobots with compact structure, flexibility, and multi-functionality, using ionic polymer metal composite (IPMC) actuators. To implement high-position precision for IPMC legs, in the present research, we proposed an electromechanical model of an IPMC actuator and analysed the deformation and actuating force of an equivalent IPMC cantilever beam, which could be used to design biomimetic legs, fingers, or fins for an underwater microrobot. We then evaluated the tip displacement of an IPMC actuator experimentally. The experimental deflections fit the theoretical values very well when the driving frequency was larger than 1 Hz. To realise the necessary multi-functionality for adapting to complex underwater environments, we introduced a walking biomimetic microrobot with two kinds of motion attitudes: a lying state and a standing state. The microrobot uses eleven IPMC actuators to move and two shape memory alloy (SMA) actuators to change its motion attitude. In the lying state, the microrobot implements stick-insect-inspired walking/rotating motion, fish-like swimming motion, horizontal grasping motion, and floating motion. In the standing state, it implements inchworm-inspired crawling motion in two horizontal directions and grasping motion in the vertical direction. We constructed a prototype of this biomimetic microrobot and evaluated its walking, rotating, and floating speeds experimentally. The experimental results indicated that the robot could attain a maximum walking speed of 3.6 mm/s, a maximum rotational speed of 9°/s, and a maximum floating speed of 7.14 mm/s. Obstacle-avoidance and swimming experiments were also carried out to demonstrate its multi-functionality.

Beschreibung: Direct synthesis of silicon carbide ( SiC ) nanopowders (size 50–200 nm, BET ~20 m 2 /g) in Si – C system is conducted in an inert atmosphere (argon) using a self-propagating high-temperature synthesis (SHS) approach. A preliminary short-term (e.g., minutes) high-energy ball milling (HEBM) of the initial mixture, which involves pure Si and C powders, is used to enhance system reactivity. Two conditions of HEBM with different force fields (17G and 90G) are applied and the results are compared. The influence of HEBM's conditions on the microstructure of mechanically treated mixtures and combustion products is also investigated and discussed. Obtained results suggest that by changing the intensity of mechanical treatment one may prepare a completely amorphous reactive mixture containing carbon and silicon, or gradually change the ratio of ( Si / C )– SiC phases and finally produce pure silicon carbide powder during the milling process. The influence of HEBM on the combustibility of the Si / C mixture possesses a critical character: the self-sustained reaction becomes feasible only after a critical time of ball milling (i.e., 10 min for 90G; 30 min for 17G). Comparison of the microstructures for as-milled and as-synthesized powders reveals that for all investigated conditions the morphologies of the as-milled reactive Si / C media are essentially the same as that for SiC combustion products. The mechanism for direct synthesis of SiC by combustion reaction is also proposed.

Beschreibung: One of the most serious causes of degradation of concrete is the alkali–silica reaction. Amorphous silicates present in certain aggregates react with the alkaline pore solution of the concrete to form a gel, which absorbs water and swells, leading to the expansion of the concrete. It is known that the deleterious effects of ASR can be suppressed by the incorporation of supplementary cementitious materials in the concrete, but the mechanisms operating are not clear. In this article, we study a model system of amorphous silica plates in simulated pore solutions by X-ray photoelectron spectroscopy (XPS), to demonstrate that aluminum in solution can directly suppress the dissolution of amorphous silica under the highly alkaline conditions found in concrete. XPS shows that aluminum species are incorporated into the framework of the silica structure. Scanning electron microscope (SEM) and atomic force microscope (AFM) images confirmed the reduction in dissolution of silica in solutions containing aluminum.

Beschreibung: An infrared ceiling sensor network system is reported in this study to realize behavior analysis and fall detection of a single person in the home environment. The sensors output multiple binary sequences from which we know the existence/non-existence of persons under the sensors. The short duration averages of the binary responses are shown to be able to be regarded as pixel values of a top-view camera, but more advantageous in the sense of preserving privacy. Using the “pixel values” as features, support vector machine classifiers succeeded in recognizing eight activities (walking, reading, etc.) performed by five subjects at an average recognition rate of 80.65%. In addition, we proposed a martingale framework for detecting falls in this system. The experimental results showed that we attained the best performance of 95.14% (F1 value), the FAR of 7.5% and the FRR of 2.0%. This accuracy is not sufficient in general but surprisingly high with such low-level information. In summary, it is shown that this system has the potential to be used in the home environment to provide personalized services and to detect abnormalities of elders who live alone.

Beschreibung: The overall aim of our research is to develop a monitoring system for neonatal intensive care units. Long-term EEG monitoring in newborns require that the electrodes don’t harm the sensitive skin of the baby, an especially relevant feature for premature babies. Our approach to EEG monitoring is based on several electrodes distributed over the head of the baby, and since the weight of the head always will be on some of them, any type of hard electrode will inevitably cause a pressure-point that can irritate the skin. Therefore, we propose the use of soft conductive textiles as EEG electrodes, primarily for neonates, but also for other kinds of unobtrusive long-term monitoring. In this paper we have tested two types of textile electrodes on five healthy adults and compared them to standard high quality electrodes. The acquired signals were compared with respect to morphology, frequency distribution, spectral coherence, correlation and power line interference sensitivity, and the signals were found to be similar in most respects. The good measurement performance exhibited by the textile electrodes indicates that they are feasible candidates for EEG recording, opening the door for long-term EEG monitoring applications.

Beschreibung: Single crystal titanium nitride powder was used to fabricate titanium nitride films using a vacuum kinetic spray (VKS) process. Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (FETEM) were used to investigate the microstructure of the as-fabricated films under different process conditions. Plastic deformation features (i.e., amorphization, rotated grain, slip bands, and distorted lattices in the transition structure) revealed an elastic-to-inelastic transition of titanium nitride particles at high strain rate and high pressure induced by hypervelocity impact, which was considered vital for grain refinement and film growth during the process.

Beschreibung: We report the diffusion and stress coupling effect during oxidation. An analytical model is developed for the stress and diffusion coupling effect based on equilibrium relationship and diffusion equation considering for the stress effect. Compressive stress will generate during the oxidation due to the growth strain. This growth stress can modify the diffusion coefficient; therefore, the oxidation kinetics is also affected. The coupling effect reduces both the oxidation rate and the stress. The proposed model is applied to predict the oxidation evolution for SiC and its consistence with the experimental data demonstrates the theoretical analysis.

Beschreibung: Composites of ZrC – SiC with relative densities in excess of 98% were prepared by reactive hot pressing of ZrC and Si at temperature as low as 1600°C. The reaction between ZrC and Si resulted in the formation of ZrC 1− x , SiC , and ZrSi . Low-temperature densification of ZrC − SiC ceramics is attributed to the formed nonstoichiometric ZrC 1− x and Zr – Si liquid phase. Adding 5 wt% Si to ZrC , the three-point bending strength of formed ZrC 0.8 –13.4 vol% SiC ceramics reached 819 ± 102 MPa with hardness and toughness being 20.5 GPa and 3.3 MPa·m 1/2 , respectively.

Beschreibung: Oxidation of SiC can occur in a passive mode, where a protective film is generated, or in an active mode, where a volatile suboxide is generated. The transitions from active-to-passive and passive-to-active are particularly important to understand as they occur via different mechanisms. In Part II of this article, the passive-to-active transition is explored. Three different types of SiC are examined— Si -rich SiC , stoichiometric SiC , and C-rich SiC . In addition to an in situ transition from passive-to-active, the effect of a preformed film on all three types of SiC is explored. It appears that the passive-to-active transition occurs when the SiO 2 scale begins to react with the SiC substrate. This reaction generates SiO (g) and CO (g), which build pressure beneath the SiO 2 scale, eventually causing the oxide to rupture. In addition, the SiO (g) can oxidize a distance away from the surface leading to the formation of SiO 2 needles and further promoting this SiO 2 / SiC reaction. Thermodynamic and kinetic data are used to predict transition pressures of oxygen, which show reasonable agreement with those measured.

Beschreibung: Camber evolution and stress development during co-firing of asymmetric bilayer laminates, consisting of porous Ce 0.9 Gd 0.1 O 1.95 gadolinium-doped cerium oxide (CGO) and La 0.85 Sr 0.15 MnO 3 lanthanum strontium manganate (LSM)-CGO were investigated. Individual layer shrinkage was measured by optical dilatometer, and the uniaxial viscosities were determined as a function of layer density using a vertical sintering approach. The camber evolution in the bilayer laminates was recorded in situ during co-firing and it was found to correspond well with the one predicted by the theoretical model. The estimated sintering mismatch stress in co-fired CGO-LSM/CGO bilayer laminates was significantly lower than general sintering stresses expected for free sintering conditions. As a result, no co-firing defects were observed in the bilayer laminates, illustrating an acceptable sintering compatibility of the ceramic layers.

Beschreibung: Erbium Er 3+ and ytterbium Yb 3+ codoped fluoro-phosphate glasses belonging to the system NaPO 3 –YF 3 – BaF 2 – CaF 2 have been prepared by the classical melt-quenching technique. Glasses containing up to 10 wt% of erbium and ytterbium fluorides have been obtained and characterized using differential scanning calorimetry (DSC) and UV–visible and near-infrared spectroscopy. Transparent and homogeneous glass–ceramics have been then reproducibly synthetized by appropriate heat treatment above glass transition temperature of a selected parent glass. Structural investigations of the crystallization performed through X-ray diffractometry (XRD) and scanning electron microscopy (SEM) have evidenced the formation of fluorite-type cubic crystals based during the devitrification process. Finally, infrared to visible up-conversion emission upon excitation at 975 nm has been studied on the Er 3+ and Yb 3+ codoped glass–ceramics as a function of thermal treatment time. A large enhancement of intensity of the up-conversion emissions–about 150 times- has been observed in the glass–ceramics if compared to the parent glass one, suggesting an incorporation of the rare-earth ions (REI) into the crystalline phase.

Beschreibung: In this work, we present a systematic study on the effect of monovalent and divalent cation inclusion on the magnetic properties of the manganites series La 0.80 ( Ag 1− x Sr x ) 0.20 MnO 3 ( x  = 0.0–1.0) synthesized by the solid-state reaction method. The decreasing Sr : Ag proportion across the compositional series was verified by X-ray photoelectron spectroscopy. Concerning magnetic properties, the hysteresis curves manifested an initial paramagnetic response at x  = 0.0, followed by a progressive ferromagnetic behavior with an optimum Ag : Sr ratio at x  = 0.75, for which an enhanced saturation magnetization of 51 Am 2 /kg and a Curie temperature of 336 K were recorded. Results are explained on the basis of the effect of the increasing unit cell volume on the double exchange interaction between magnetic Mn 3+ – Mn 4+ atoms.

Beschreibung: A simple solvothermal low-temperature synthesis process of TiO 2 nanoparticles was investigated in different solvents [Octanol ( Oc ), Ethanolamine ( Am ) and Terathane ( Tr )] with titanium (IV) chloride ( TiCl 4 ) as precursor. The samples were characterized by X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). XRD showed the crystallite size ranging from 4 to 12 nm, which were calculated using Debye–Scherrer's equation. The existence of poor or high crystalline anatase phases and high crystalline anatase/rutile mixture was also shown. TEM images displayed variations in the morphological behavior depending on the synthesis condition. Particles of irregular morphology with high irregular agglomeration up to well-defined particles can be observed, which are self-assembled by oriented attachment (OA). This self-assembly led to TiO 2 microparticles with 3-D Wulff shape for anatase and 1-D shape for rutile. The results showed that the TiO 2 nanopowder could be easily engineered and adapted by the solvent type, the TiCl 4 concentration and the synthesis time.

Beschreibung: x Nd ( Zn 1/2 Ti 1/2 ) O 3 –(1− x ) Ba 0.6 Sr 0.4 TiO 3 ( x NZT–BST) thin films were fabricated on Pt / Ti / SiO 2 / Si substrates by sol–gel method with x  =   0, 3%, 6%, and 10%. The structures, surface morphology, dielectric and ferroelectric properties, and thermal stability of x NZT–BST thin films were investigated as a function of NZT content. It was observed that the introduction of NZT into BST decreased grain size, dielectric constant, ferroelectricity, tunability, and significantly improved dielectric loss and dielectric thermal stability. The corresponding reasons were discussed. The 10%NZT–BST thin film exhibited the least dielectric loss of 0.005 and the lowest temperature coefficient of permittivity (TCP) of 3.2 × 10 −3 /°C. In addition, the figure of merit (FOM) of x NZT–BST ( x  = 3%, 6%, and 10%) films was higher than that of pure BST film. Our results showed that the introduction of appropriate NZT into BST could modify the dielectric quality of BST thin films with good thermal stability. Especially for the 3%NZT–BST thin film, it showed the highest FOM of 33.58 for its appropriate tunability of 32.87% and low dielectric loss of 0.0098.

Beschreibung: The influence of the addition of 1 mol% Tm 2 O 3 on the nanocrystallization of LaF 3 in a glass of composition 55 SiO 2 –20 Al 2 O 3 –15 Na 2 O –10 LaF 3 (mol%) has been studied. Tm 2 O 3 affects the phase separation in the glass and delays the onset of crystallization with respect to the undoped glass. Additionally, the maximum LaF 3 crystal size is slightly greater than that in the undoped glass–ceramics. The microstructural and compositional changes in the glass matrix have been studied using several techniques, including viscosity, dilatometry, X-ray and neutron diffraction (XRD, ND), quantitative Rietveld refinement, transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and Raman spectroscopy. Photoluminescence measurements indicate that the Tm 3+ ions are distributed between the glassy matrix and LaF 3 crystals. Eu 2 O 3 has been used as structure probe and part of the Eu 3+ ions are reduced to Eu 2+ when incorporated in the LaF 3 nano-crystals. Up-conversion spectra under IR-excitation show a higher intensity of the blue emission in the Tm -doped glass–ceramic compared with that in the glass.

Beschreibung: In this paper, a laboratory goniometer system for performing multi-angular measurements under controlled illumination conditions is described. A commercially available robotic arm enables the acquisition of a large number of measurements over the full hemisphere within a short time span making it much faster than other goniometers. In addition, the presented set-up enables assessment of anisotropic reflectance and emittance behaviour of soils, leaves and small canopies. Mounting a spectrometer enables acquisition of either hemispherical measurements or measurements in the horizontal plane. Mounting a thermal camera allows directional observations of the thermal emittance. This paper also presents three showcases of these different measurement set-ups in order to illustrate its possibilities. Finally, suggestions for applying this instrument and for future research directions are given, including linking the measured reflectance anisotropy with physically-based anisotropy models on the one hand and combining them with field goniometry measurements for joint analysis with remote sensing data on the other hand. The speed and flexibility of the system offer a large added value to the existing pool of laboratory goniometers.