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Maximum length binary sequences and spectral power distribution of periodic signals
Get PDFThe maximum length binary sequence (MLBS) is widely used as a broadband pseudo-random noise excitation signal, for example, for system identification. Although its properties have been known for decades, misleading or inaccurate statements can be found in many references. For example, it is sometimes stated that the spectrum of the MLBS is white, whereas in other references a sinc behavior is stated. In this paper, we therefore analyze the MLBS properties based on precise definitions for the given context (time-discrete vs. time-continuous, periodic vs. non-periodic, etc.), especially with respect to Fourier analysis. Another difficulty arises from the fact that in the literature the mathematical definitions are often simplified by means of normalizations which makes the physical interpretation difficult. Therefore, special emphasis is put on scaling factors which allow such a physical interpretation
Physiological data for affective computing in HRI with anthropomorphic service robots: the AFFECT-HRI data set
Get PDFIn human-human and human-robot interaction, the counterpart influences the human’s affective state. Contrary to humans, robots inherently cannot respond empathically, meaning non-beneficial affective reactions cannot be mitigated. Thus, to create a responsible and empathetic human-robot interaction (HRI), involving anthropomorphic service robots, the effect of robot behavior on human affect in HRI must be understood. To contribute to this understanding, we provide the new comprehensive data set AFFECT-HRI, including, for the first time, physiological data labeled with human affect (i.e., emotions and mood) gathered from a conducted HRI study. Within the study, 146 participants interacted with an anthropomorphic service robot in a realistic and complex retail scenario. The participants’ questionnaire ratings regarding affect, demographics, and socio-technical ratings are provided in the data set. Five different conditions (i.e., neutral, transparency, liability, moral, and immoral) were considered during the study, eliciting different affective reactions and allowing interdisciplinary investigations (e.g., computer science, law, and psychology). Each condition includes three scenes: a consultation regarding products, a request for sensitive personal information, and a handover
Revealing the quantum nature of the voltage-induced conductance changes in oxygen engineered yttrium oxide-based RRAM devices
Get PDFIn this work, the quasi-analog to discrete transition occurring in the current–voltage characteristic of oxygen engineered yttrium oxide-based resistive random-access memory (RRAM) devices is investigated in detail. In particular, the focus of our research is not on the absolute conductance values of this characteristic but on the magnitude of its conductance changes occurring during the reset process of the device. It is found that the detected changes correspond to conductance values predominantly of the order of the quantum unit of conductance G₀ = 2e²/h, where e is the electron charge and h the Planck constant. This feature is observed even at conductance levels far above G₀, i.e. where electron transport is seemingly diffusive. It is also observed that such behavior is reproducible across devices comprising yttrium oxide layers with different oxygen concentrations and measured under different voltage sweep rates. While the oxygen deficiency affects the total number of quantized conductance states, the magnitude of the changes in conductance, close to 1 G₀, is invariant to the oxygen content of the functional layer
Demonstration of active neutron interrogation of special nuclear materials using a high-intensity short-pulse-laser-driven neutron source
Get PDFDetecting shielded special nuclear material, such as nuclear explosives, is a difficult challenge pursued by non-proliferation, anti-terrorism, and nuclear security programs worldwide. Interrogation with intense fast-neutron pulses is a promising method to characterize concealed nuclear material rapidly but is limited by suitable source availability and proven instrumentation. In this study we have pioneered a demonstration of such an interrogation method using a high-intensity, short-pulse, laser-driven neutron source that offers potential benefits compared to conventional neutron sources. The measurement results reported here represent the first experimental demonstration of this interrogation approach on enriched uranium items and demonstrate the feasibility of a precise measurement using realistic nuclear materials, representative of field scenarios, even with just a single laser-driven neutron pulse. Bright pulsed sources can overcome the nuisance background of items with strong internal neutron sources, improving analytical power, while single-shot assay is attractive in high-throughput situations where time is at a premium. The science and technology of this type of neutron production is developing rapidly, and we anticipate that practical mobile interrogation systems will become available based on the detection concepts demonstrated here to meet the growing measurement needs
Deformation twins as a probe for tribologically induced stress states
Get PDFFriction and wear of metals are critically influenced by the microstructures of the bodies constituting the tribological contact. Understanding the microstructural evolution taking place over the lifetime of a tribological system therefore is crucial for strategically designing tribological systems with tailored friction and wear properties. Here, we focus on the single-crystalline High-Entropy Alloy CoCrFeMnNi that is prone to form twins at room temperature. Deformation twins feature a pronounced orientation dependence with a tension-compression anisotropy, a distinct strain release in an extended volume and robust onset stresses. This makes deformation twinning an ideal probe to experimentally investigate the complex stress fields occurring in a tribological contact. Our results unambiguously show a grain orientation dependence of twinning under tribological load. It is clearly shown, that twinning cannot be attributed to a single crystal direction parallel to a sample coordinate axes. With deformation twins in the microstructure, stress field models can be validated to make them useable for all different tribological systems
A wireless W-band 3D-printed temperature sensor based on a three-dimensional photonic crystal operating beyond 1000 °C
Get PDFIn addressing sensing in harsh and dynamic environments, there are no available millimeter-wave chipless and wireless sensors capable of continuous operation at extremely high temperatures. Here we present a fully dielectric wireless temperature sensor capable of operating beyond 1000 °C. The sensor uses high-Q cavities embedded within a three-dimensional photonic crystal resonating at 83.5 GHz and 85.5 GHz, and a flattened Luneburg lens enhances its readout range. The sensor is additively manufactured using Lithography-based Ceramic Manufacturing in Alumina (Al₂O₃). Despite the clutter, its frequency-coded response remains detectable from outside the furnace at 50 cm and at temperatures up to 1200 °C. It is observed that the resonance frequencies shift with temperature. This shift is linked to a change in the dielectric properties of Al₂O₃, which are estimated up to 1200 °C and show good agreement with literature values. The sensor is thus highly suitable for millimeter-wave applications in dynamic, cluttered, and high-temperature environments
Comprhensive Approach to the Analysis of the 3D Kinematics Deformation with appliction to the Kenai Peninsula
Get PDFThe problem of analyzing surface deformation of the Earth's crust in three-dimensions is discussed. The isoparametric and Lagrangian formulations of deformation are extended from 2D to 3D. Analytical and numerical investigation of problem conditioning proves that analyzing the 3D kinematics of deformation can be an ill-posed problem. The required mathematical elements for solving this problem, including sensitivity analysis of the deformation tensor and regularization, are proposed. Regularized deformation tensors were computed using the method of truncated singular value decomposition (TSVD). The optimal regularization parameter was attained by minimizing regularization errors. Regularization errors were assessed using the corresponding 2D results of deformation analysis. The proposed methods were applied to the GPS network in the Kenai Peninsula, south-central Alaska, in order to compute the 3D pattern of postseismic crustal deformation in this area. Computed deformation in the vertical direction is compared to the existing pattern of vertical deformation obtained from the combination of precise leveling, gravity and GPS measurements from other studies on this area
Crystal structure of ammonium triiodidomercurate(II) monohydrate, NH₄HgI₃ · H₂O
Get PDFH₆HgI₃NO, monoclinic, C1c1 (No. 9), a = 11.1235(9) Å, b = 9.8046(8) Å, c = 8.7430(8) Å, β = 90.185(7)°, V = 953.5 ų, Z = 4, Rgt(F) = 0.033, wRref(F²) = 0.072, T = 299 K
The Flying Laboratory FLab: development and application of a UAS to measure aerosol particles and trace gases in the lower troposphere
No full textUncrewed aircraft systems (UASs) are gradually being established in environmental research to study boundary layer conditions and phenomena in situ; however, due to payload limitations, UASs can typically measure only a limited number of atmospheric variables simultaneously. Here we present the Flying Laboratory (FLab), a hexacopter equipped with six instruments to measure aerosol particles (particle number concentration and size distribution; PM₁, PM₂.₅, and black carbon mass concentration), trace gases (CO₂, O₃), and meteorological variables (temperature, relative humidity, pressure, wind) in the lower troposphere in real time and with high temporal resolution. The instrumentation has been selected to provide an overview of relevant variables in urban and semi-urban environments and especially in the vicinity of aerosol sources. This paper describes the development of the technical setup of the Flying Laboratory, the characterization of the measurements with respect to horizontal and vertical motion of the UAS, and the optimization of measurement flight patterns. During two field experiments, FLab was applied to bridge the gap between ground-based and aircraft-based profiling measurements and to perform hourly vertical profiling flights up to 300 m above a ground-based reference station for 8 h. These applications demonstrate the capability of FLab to capture the evolution of the lower convective boundary layer during the day and the vertical particle transport in the afternoon up to 200 m above ground
Impact of Surface Functionalization on the Intrinsic Properties of the Resulting Fe–N–C Catalysts for Fuel Cell Applications
No full textHerein, Fe–N–C catalysts are prepared from surface functionalized carbon nanotubes (CNTs) in combination with iron acetate and phenanthroline. An improved performance and structural composition is obtained by surface functionalization of the CNTs with indazole or pyridine. Catalyst composition and morphology are characterized by transmission electron microscopy, N₂ sorption, photoelectron spectroscopy, and ⁵⁷Fe transmission Mössbauer spectroscopy. However, activity and selectivity toward oxygen reduction reaction are determined from rotating ring disc electrode (RRDE) experiments. The durability and stability are evaluated by accelerated stress tests (0.0–1.2 V) and differential electrochemical mass spectroscopy (DEMS), respectively. It is shown that surface functionalization with indazole enables the direct attachment of FeN4 centers to CNTs so that no impurity species are detected and a high activity is achieved, that can be attributed to an improved turnover frequency and higher mass-based site density. Even more striking is the excellent durability and stability of the realized catalyst. While these trends are well pronounced in RRDE and DEMS, challenges in the preparation of membrane electrode assemblies make the trend not as obvious in fuel cells (FCs)