People tracking in an environment with multiple depth cameras: A skeleton-based pairwise trajectory matching scheme

This paper proposes a pairwise trajectory matching scheme from multiple cameras for people tracking, handling the mistracking situations caused by occlusion events occurred in one of the cameras. In a multiple cameras environment, a geometric calibration process is necessary for the co-plane of the overlapping field of views from different cameras as the initial step. Once the geometry is calibrated, according to the 2D positions of the analyzed foot joints from the depth cameras. Homography transformation is applied to project the detected foot points from different views into a synergistic virtual bird’s eye view for people tracking. At the virtual bird’s eye view, the people tracking results from each of the cameras based on Kalman filter are fused according to the proposed pairwise trajectory matching scheme. The contribution of this paper is trifold: (1) The proposed hand-gesture-triggered calibration process with temporally synchronization capability can effectively build and calibrate the geometry in a region of interest. (2) The proposed interleaving-based skeleton obtaining and moving average based valid skeleton determination can extend the skeleton tracking capability to track more people. (3) The proposed pairwise trajectory matching scheme effectively manages occlusion situations happened in one of the depth cameras. In addition, in the extensive experimental results, the proposed method can track up to six simultaneously freely moving persons in the field of view, with affordable complexity for real-time applications. Furthermore, the infrared-based depth cameras track people satisfactorily from bright to extremely dark environments.     

Critical parameters for the compressive strength of high-strength concrete

This study investigates the influence of several material properties underlying the failure mechanism of high-strength concrete (HSC) under uniaxial compression. An experimental-numerical characterization of a single inclusion block (SIB) – an idealized composite comprising of a granite cylindrical core embedded within a high-strength mortar (HSM) matrix – is first carried out. Parametric studies are next conducted with the calibrated SIB model, to identify the critical parameters governing the failure of the idealized composite. The qualitative understanding obtained from the SIB is then utilized to design a series of experiments, exploring the extent of influence of the identified critical parameters on the compressive strength of HSC. Complementary experimental data in literature are also examined. For the range of specimens considered, it is found that the lateral strain capacity of mortar matrix has the most influence on the compressive strength of HSC.     

A potential gas sensor device based on Pd/RGO/TiO2 nanotube ternary hybrid junction

In the present work, fabrication, characterizations and gas sensing performance of a novel ternary hybrid junction device consisting of Pd nanoparticles, Reduced Graphene Oxide (RGO) and TiO₂ nanotubes (NTs) is reported. Electrochemically derived TiO₂ nanotubes were covered partially by RGO matrix in the form of distributed islands, on top of which Pd nanoparticles were dispersed uniformly. After detailed structural and morphological characterizations, gas sensing potentiality of the developed ternary hybrid device was tested for detection of methanol vapor and the sensing performance was compared with that of the RGO-TiO₂ binary structure to ensure the improvement caused by incorporation of the ternary element (Pd). Underlying mechanistic framework for gas sensing, by such ternary junction, was explained with the help of corresponding energy band diagram.     

细骨料携带氯离子的砂浆强度和粘结力长期暴露试验研究

首先研究了细骨料携带不同质量分数氯离子的砂浆试件在3，5，7，14，28，90d的抗折、抗压强度的变化规律，发现与拌制用水中携带氯离子具有早强作用不同，细骨料携带氯离子不但不会引起早强，反而会降低强度。基于4年的长期暴露试验，系统研究细骨料携带不同质量分数氯离子的砂浆试件在270，360，450，630，810，105...     

Efficient nonparametric identification for high-precision motion systems: A practical comparison based on a medical X-ray system

The need for accurate knowledge of complex dynamical behavior for high-performance mechatronic systems led to the development of a vast amount of nonparametric system identification approaches over the recent years. The aim of this paper is to compare several proposed methods based on experiments on a physical complex mechanical system to bridge the gap between identification theory and practical applications in industry where basic identification approaches are often the norm. Typical practical implications such as operation under closed-loop control, multivariable coupled behavior and nonlinear effects are included in the analysis. Finally, a possible approach for fast and reliable identification is illustrated based on measurement results of an interventional medical X-ray system.     

A new a priori SNR estimator based on multiple linear regression technique for speech enhancement

We propose a new approach to estimate the a priori signal-to-noise ratio (SNR) based on a multiple linear regression (MLR) technique. In contrast to estimation of the a priori SNR employing the decision-directed (DD) method, which uses the estimated speech spectrum in previous frame, we propose to find the a priori SNR based on the MLR technique by incorporating regression parameters such as the ratio between the local energy of the noisy speech and its derived minimum along with the a posteriori SNR. In the experimental step, regression coefficients obtained using the MLR are assigned according to various noise types, for which we employ a real-time noise classification scheme based on a Gaussian mixture model (GMM). Evaluations using both objective speech quality measures and subjective listening tests under various ambient noise environments show that the performance of the proposed algorithm is better than that of the conventional methods.     

Toward sustainable energy usage in the power generation and construction sectors—a case study of Australia

To be sustainable in energy usage in the future, there are two aspects that need to be considered: the energy supply or generation and the consumption side, including the closely linked construction and building industries which consume a large amount of energy. Essential requirements for energy efficiency are to produce less greenhouse gas emissions and to rely more on renewable energy sources for future sustainability. Policies for mitigation of the environment impact are having effects on both the supply and demand. While the former requires more alternate sources in smart grids and improved technologies for carbon capture and storage, the latter involves the reduction of energy wastes and greenhouse gas (GHG) emissions as prerequisites to green certification within the construction and building sector. Thus, access to sustainable, affordable, and secure energy is one of the major global strategic priorities to maintain and improve public health, sustain economic growth, and mitigate the effects of climate change. Toward this goal, many countries, including Australia, are investing in clean, efficient, reliable energy systems for a prosperous and environmentally sustainable future. Hence, exploring various options to ensure energy security by diversification of energy sources is an important step in meeting the future requirements and delivering clean energy to different industry sectors. This paper discusses options to manage the use of energy sources in the power generation and construction industries. Options for mitigation of environmental impact and for achievement of sustainable energy usage, such as building design with BIM, are discussed.     

Research on the interaction mechanism between quantum dots and radionuclides for the improvement of Cerenkov luminescence imaging

Cerenkov luminescence imaging(CLI) is a relatively new optical molecular imaging technique. The nature of Stokes shift in quantum dots(QD) can be used to improve the quality of CLI. However, the interaction mechanism of QD with Cerenkov light remains unclear. In this work, the interaction mechanism between QD and radionuclides emitting β rays, γ rays, and Cerenkov light was investigated. The 96-well plates were used to test the different levels of radioactivity of radionuclides with different QD concentrations. Transparent vials were used to determine the relationship between QD fluorescence intensity and the distance from QD to the radionuclide. In addition, black paper was used to block the transmission of Cerenkov light through the QD vials. A linear relationship was found between the number of photons and the radioactivity of radionuclides when the QD concentration was kept constant. Similarly, the number of photons was linearly related to the QD concentration when the radioactivity of radionuclides was kept constant. Furthermore, with the increases in the distance between radionuclides and quantum dots, the number of photons was exponentially decreased. Meanwhile, the number of photons emitted from QD excited by Cerenkov light accounted for 20% the total number of photons excited by 131 I radionuclide. The result proved that QD was not only excited by Cerenkov light but also by other rays.     

Numerical simulation of the shear behaviour of reinforced concrete rectangular beam specimens with or without FRP-strip shear reinforcement

The successful validation of a numerical model is presented that can realistically approximate the shear behaviour of reinforced concrete (R/C) rectangular beams strengthened against shear with externally applied open hoop fibre reinforcing polymer (FRP) strips. For this purpose, the measured load-deformation response of ten (10) full-scale R/C beam specimens is utilised. These specimens were loaded monotonically in a four-point bending arrangement up to failure. Open hoop FRP strip shear reinforcement was applied externally to upgrade the shear capacity of eight (8) R/C beam specimens. Four of these specimens had these FRP strips without anchorage, whereas for the other four the FRP strips were attached together with novel anchoring devices. This successful numerical simulation predicts with a very good degree of approximation the observed load-deformation behaviour and the ultimate shear capacity of all these specimens as well as the observed modes of failure including diagonal concrete cracking, debonding of the FRP strips in the case of no anchoring, or the plastification of parts of the anchoring devices plus the adjacent crushing of the concrete.