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.     

Wooden sticks as the source of a pseudoepidemic of infection with Rhizopus microsporus var. rhizopodiformis among immunocompromised patients

Wooden sticks used to suspend feces obtained for surveillance cultures were found to be the source of Rhizopus microsporus var. rhizopodiformis causing a pseudo-outbreak among 17 immunocompromised patients cared for in three different wards. Nonsterile wooden products should therefore not be used for collecting, handling, and processing specimens for microbiological examination.     

The effect of floor slope on sub-maximal lifting capacity and technique

Inclined surfaces, where both the lifter and load are on the slope, may be encountered in a jobsite situation. The purpose of this study was to determine if facing up or down a sloped surface (10 degrees and 20 degrees ) would affect maximal acceptable weights of lift (MAWL) using a 10 min psychophysical approach with symmetric freestyle technique at 4 lifts/min. Seventeen healthy men and 18 women determined floor to knuckle height MAWL while facing uphill, downhill, and on a level surface. Motion capture was also performed to examine sagittal plane joint angles and foot placement relative to a milk crate. Slope did not alter MAWL (p>0.05) with the men lifting more than the women in every condition (p<0.001) (25 kg vs. 15 kg, respectively). Foot placement relative to the box was altered by slope such that both horizontal position behind and vertical position below the box increased as slope changed from the downhill to uphill conditions (both p<0.001). Forward torso lean as well as hip, knee, and ankle (plantar) flexion generally decreased as slope changed from the downhill to uphill conditions (all p<0.001). Torso and knee motion appeared to be protected compared to the other joints, changing the least. Though trends were the same in both sexes, interactions did exist in vertical foot position and hip angle (both p0.001). In conclusion, the body is highly adaptive to floor slope, maintaining MAWL at least in the short term. However, while slight technique differences exist between men and women, care should be taken by all when facing uphill due to the tendency to stand further from the load horizontally and when facing downhill due to increased torso lean.     

3D Semantic Scene Completion: A Survey

International Journal of Computer Vision - Semantic scene completion (SSC) aims to jointly estimate the complete geometry and semantics of a scene, assuming partial sparse input. In the last years...     

A critical discussion on rebar electrical continuity and usual interpretation thresholds in the field of half-cell potential measurements in steel reinforced concrete

Corrosion of steel in reinforced concrete structures is a recurrent problem affecting civil engineering structures and costing the world billions of dollars per year. This physical phenomenon mainly results from chloride ingress or concrete carbonation. Corrosion can be diagnosed through a nondestructive method such as half-cell potential measurements. The present paper studies this method on a reinforced concrete wall containing eighteen unconnected steel bars and subjected to chloride-induced macrocell corrosion. Three corrosion systems with different configurations of connections between the steel bars are generated, involving three different anode-to-cathode surface ratios. Then, half-cell potential variations are observed versus macrocell corrosion current. The results lead to a critical discussion regarding the physical relevance of the usual potential threshold method to detect corroding rebars in reinforced concrete structures. In addition, the experiments demonstrate that electrical continuity between reinforcing steel bars is not necessary to get meaningful information about the macrocell corrosion system. At last, the paper show that the electric field (potential gradient) relative to a macrocell corrosion system may be measured by connecting the measurement system (reference electrode?+?voltmeter) to any electrochemical system in electrolytic contact with the concrete.     

Next generation session management for 3D teleimmersive interactive environments

In the recent past we have seen a boom of distributed interactive multimedia environments which use multiple correlated media sensors, multi-view displays, and advanced haptic-audio-visual user interfaces for teleimmersive gaming, business meetings and other collaborative activities. However, when we investigate the emerging teleimmersive environments closer, we realize that their overall session management, including end-to-end session setup, establishment and run-time management are not appropriate for the new demands that these environments present. These environments are cyber-physical rooms that demand (a) large scale of multi-sensory devices across geographically-distributed locations and (b) interaction with each other in synchronous and real-time manner. To deal with the new teleimmersive demands, we present a new session management design with (a) session initiation protocol(s) that understand media correlations, (b) view-based multi-stream topology establishment among multiple parties, (c) efficient, light-weight and distributed session monitoring with querying and debugging capabilities, (d) flexible view-based session adaptation with efficient topology adjustments, and (e) light-weighted and consistent session tear-down protocols. The presented design of the next generation session management protocols, services, algorithms and data structures is based on our extensive experiences with building 3D teleimmersive interactive systems, experimenting with high impact teleimmersive applications and deploying such environments at various venues.     

The Covering Law Model Applied to Dynamical Cognitive Science: A Comment on Joel Walmsley

In a 2008 paper, Walmsley argued that the explanations employed in the dynamical approach to cognitive science, as exemplified by the Haken, Kelso and Bunz model of rhythmic finger movement, and the model of infant preservative reaching developed by Esther Thelen and her colleagues, conform to Carl Hempel and Paul Oppenheim’s deductive-nomological model of explanation (also known as the covering law model). Although we think Walmsley’s approach is methodologically sound in that it starts with an analysis of scientific practice rather than a general philosophical framework, we nevertheless feel that there are two problems with his paper. First, he focuses only on the deductivenomological model and so neglects the important fact that explanations are causal. Second, the explanations offered by the dynamical approach do not take the deductive-nomological format, because they do not deduce the explananda from exceptionless laws. Because of these two points, Walmsley makes the dynamical explanations in cognitive science appear problematic, while in fact they are not.     

Estimating the altitude of aerosol plumes over the ocean from reflectance ratio measurements in the O2 A-band

A methodology is proposed to infer the altitude of aerosol plumes over the ocean from reflectance ratio measurements in the O₂ absorption A-band (759 to 770 nm). The reflectance ratio is defined as the ratio of the reflectance in a first spectral band, strongly attenuated by O₂ absorption, and the reflectance in a second spectral band, minimally attenuated. For a given surface reflectance, simple relations are established between the reflectance ratio and the altitude of an aerosol layer, as a function of atmospheric conditions and the geometry of observation. The expected accuracy for various aerosol loadings and models is first quantified using an accurate, high spectral resolution, radiative transfer model that fully accounts for interactions between scattering and absorption. The method is developed for POLDER and MERIS, satellite sensors with adequate spectral characteristics. The simulations show that the method is only accurate over dark surfaces when aerosol optical thickness at 765 nm is relatively large (> 0.3). In this case, the expected accuracy is on the order of ± 0.5 km or ± 0.2 km for POLDER or MERIS respectively. More accurate estimates are obtained with MERIS, since in this case the spectral reflectance ratio is more sensitive to aerosol altitude. However, a precise spectral calibration is needed for MERIS. The methodology is applied to MERIS and POLDER imagery acquired over marine surfaces. The estimated aerosol altitude is compared with in situ lidar profiles of backscattering coefficient measured during the AOPEX-2004 experiment for MERIS, or obtained with the space-borne lidar CALIOP for POLDER. The retrieved altitudes agree with lidar measurements in a manner consistent with theory. These comparisons demonstrate the potential of the differential absorption methodology for obtaining information on aerosol altitude over dark surfaces.