Special Issue on Deep Learning for Robotic Vision

International Journal of Computer Vision -     

Imaging of two-dimensional unsaturated moisture flows in uncracked and cracked cement-based materials using electrical capacitance tomography

The development of visualizing tools to monitor unsaturated moisture flow in cement-based materials is of great importance, as most degradation processes in cement-based materials are connected to and take place in the presence moisture. This paper investigates the ability of electrical capacitance tomography (ECT) to image two-dimensional (2D) unsaturated moisture flow in cement-based materials. In ECT, the electrical permittivity distribution within an object is reconstructed based on measured capacitances between electrodes attached on the object’s surface. In a series of experiments, mortar specimens with and without discrete cracks were imaged with ECT during a 2D moisture ingress. The results show that ECT is able to monitor the evolution of the moisture flow, and to approximate the shape and position of the moisture front. These findings indicate that ECT is a viable method for monitoring and visualizing 2D unsaturated moisture flow in cement-based materials in the presence and absence of discrete cracks.     

Comparative emission analysis of low-energy and zero-emission buildings

Different designs and concepts of low-energy and zero-emission buildings (ZEBs) are being introduced into the Norwegian market. This study analyses and compares the life cycle emissions of CO₂ equivalents (CO₂e) from eight different single-family houses in the Oslo climate. Included are four ZEBs: one active house, two passive houses, and a reference house (Norwegian building code of 2010). Monthly differences in CO₂e emissions are calculated for the seasonally sensitive Norwegian context for electricity generation and consumption. This is used to supplant the previous applied symmetric weighting approach for CO₂e/kWh factors for import and export of electricity for the ZEB cases. All the ZEBs have lower use-stage emissions compared with the other buildings or the reference case. Embodied impacts are found to be 60–75% for the analysed ZEB cases, confirming the importance of embodied impacts in Norwegian ZEBs. The lowest total emissions were from the smallest ZEB, emphasizing area efficiency. The highest emissions were from the reference case. By abandoning the symmetric approach, a new perspective was developed for assessing the performance of ZEBs within the Norwegian context. One of four ZEB cases managed to balance out its annual energy-related emissions.     

Fatty and Volatile Oils of the Gypsywort Lycopus europaeus L. and the Gaussian-Like Distribution of its Wax Alkanes

The detailed analyses of the volatile essential oil and lipid profiles of the aerial parts from the blooming and fruit-forming stages of both ripe and unripe fruit of Lycopus europaeus (Lamiaceae) are presented. Both of these profiles are distinguished by components with a restricted occurrence in the Plant Kingdom. These rare compounds include (E)-hotrienol in the volatiles, numerous unusual fatty acids (such as very long chain, odd-numbered and branched-chain) in the bound lipids and a high amount of iso- and anteiso-alkanes in the epicuticular waxes. Furthermore, a Gaussian-like distribution of the relative amounts of the epicuticular wax alkanes was observed. These normal distributions could be interpreted as the end result of the work of elongase enzyme systems where the Gaussian parameter μ should match the length of the “ideal” fatty acid biosynthesised and σ would represent the error of this enzyme system. These curve parameters were shown to have a close relationship with ACL and CPI values usually utilised to describe the natural distribution of wax alkanes. The screening of L. europaeus essential oil for its in vitro antimicrobial activity showed that this oil possesses selectivity towards two gram-negative strains, E. coli and K. pneumoniae.     

The Liquidus in Cu–O–CaO System at Metallic Copper Saturation up to 1698 K

We present experimental results for the liquidus of the pseudo binary system Cu₂O–CaO at metallic copper saturation up to 1698 K in steps of 25 K. In this study, we quantified the liquidus (on the CaO side of the binary) by the equilibration, quench, and analysis technique, with Cu₂O, CaO, and Cu as the only primary crystalline phases. Experiments were conducted in an atmosphere of pure argon up to the critical temperature (1618 K) in the Cu–O system. Above this temperature, experiments were performed at a fixed oxygen pressure of (P_O2 = 1.01 kPa). Equilibrated specimens were quenched in ice‐cold water. We then quantified the liquid chemical compositions by means of energy‐dispersive X‐ray spectroscopy and electron probe micro‐analyzer. Results from this study reveal that below the critical point, some previous studies have overestimated CaO solubility amounts in the molten phase of the system, by up to 4.35 wt% CaO. Thermodynamic modeling of systems containing this binary should therefore also account for this variance.     

Ball screw drives with enhanced bandwidth by modification of the axial bearing

The bandwidth of the ball-screw drive is limited by the first natural frequency of the mechanical structure. As opposed to conventional drives where the axial bearing stiffness is kept high to obtain higher natural frequencies, this paper proposes to use lower axial bearing stiffness accompanied by a strong damper in parallel with the ball-screw structure. The proposed method, which is experimentally demonstrated, increases the bandwidth of the drive considerably provided that a cost effective and practical damper is available.     

An excursion into classical nonlinear acoustics

This paper is concerned with the derivation of the partial differential equations that govern the propagation of sonic disturbances in an ideal gas under isentropic conditions. The result is a quasilinear hyperbolic system of first order equations and an inequality constraint. The speed of propagation is pressure dependent. It is shown how to deal with the equations and the constraint and how to calculate characteristics and solutions. It is also shown that shock discontinuities can develop which distinguishes the equations from the traditional linear wave equation.     

Nanobodies and Nanocrystals: Highly Sensitive Quantum Dot‐Based Homogeneous FRET Immunoassay for Serum‐Based EGFR Detection

Semiconductor quantum dot nanocrystals (QDs) for optical biosensing applications often contain thick polyethylene glycol (PEG)‐based coatings in order to retain the advantageous QD properties in biological media such as blood, serum or plasma. On the other hand, the application of QDs in Förster resonance energy transfer (FRET) immunoassays, one of the most sensitive and most common fluorescence‐based techniques for non‐competitive homogeneous biomarker diagnostics, is limited by such thick coatings due to the increased donor‐acceptor distance. In particular, the combination with large IgG antibodies usually leads to distances well beyond the common FRET range of approximately 1 to 10 nm. Herein, time‐gated detection of Tb‐to‐QD FRET for background suppression and an increased FRET range is combined with single domain antibodies (or nanobodies) for a reduced distance in order to realize highly sensitive QD‐based FRET immunoassays. The “(nano)²” immunoassay (combination of nanocrystals and nanobodies) is performed on a commercial clinical fluorescence plate reader and provides sub‐nanomolar (few ng/mL) detection limits of soluble epidermal growth factor receptor (EGFR) in 50 μL buffer or serum samples. Apart from the first demonstration of using nanobodies for FRET‐based immunoassays, the extremely low and clinically relevant detection limits of EGFR demonstrate the direct applicability of the (nano)^2‐ assay to fast and sensitive biomarker detection in clinical diagnostics.     

Design of Engineered Elastomeric Substrate for Stretchable Active Devices and Sensors

In the field of flexible electronics, emerging applications require biocompatible and unobtrusive devices, which can withstand different modes of mechanical deformation and achieve low complexity in the fabrication process. Here, the fabrication of a mesa‐shaped elastomeric substrate, supporting thin‐film transistors (TFTs) and logic circuits (inverters), is reported. High‐relief structures are designed to minimize the strain experienced by the electronics, which are fabricated directly on the pillars' surface. In this design configuration, devices based on amorphous indium‐gallium‐zinc‐oxide can withstand different modes of deformation. Bending, stretching, and twisting experiments up to 6 mm radius, 20% uniaxial strain, and 180° global twisting, respectively, are performed to show stable electrical performance of the TFTs. Similarly, a fully integrated digital inverter is tested while stretched up to 20% elongation. As a proof of the versatility of mesa‐shaped geometry, a biocompatible and stretchable sensor for temperature mapping is also realized. Using pectin, which is a temperature‐sensitive material present in plant cells, the response of the sensor shows current modulation from 13 to 28 °C and functionality up to 15% strain. These results demonstrate the performance of highly flexible electronics for a broad variety of applications, including smart skin and health monitoring.