Monitoring the strength gain of structural adhesives using the electromechanical impedance technique: An experimental investigation

Structural adhesives are employed to externally bond fibre-reinforced polymer (FRP) composites onto concrete structures for repair and strengthening purposes. The strength development of the bond layer is important to ensure the overall performance of the FRP-strengthened system. The non-destructive piezoelectric-based monitoring technique, namely the electromechanical impedance (EMI) technique, is introduced to monitor the strength gain of structural adhesives. In this study, the curing process of the commercially available structural adhesive, Sikadur 330, was monitored using the EMI technique. Throughout the experimental study, the 7-day strength gain of the adhesive was observed from the movement of acquired frequency peaks. The frequency peaks moved noticeably to the right for the first 24 hours. After that, the rate of movement decreased significantly. An empirical equation is established to correlate the tensile strength of the adhesive to the acquired resonance frequency for different curing durations. The current study shows the capability of the EMI technique to monitor the strength gain of structural adhesives, particularly at an early age of curing

A method for three-dimensional reconstruction of a train accident scene using photographs

Railway accidents that usually cause numerous property and life losses occurred in recent years all around the world. In general, resources such as financial supports and incident rescue programs are required to minimize the losses after an accident. Due to lack of comprehensive information collected from accident sites, most railway emergency management departments face a predicament in setting up rescue schemes. To tackle the issue, realistic three-dimensional virtual accident scene reconstruction technology is developed, which provides and visualises supplementary materials and information about a train accident and can offer assistance to emergency crews when making decisions. We propose a photo-based three-dimensional reconstruction framework of vehicles for measuring the positions and poses of carriages involved in an accident. We implement and examine two case studies to validate this reconstruction method, which performs well in the assigned tasks

3D reconstruction of train accident scene based on monocular image

To help with making an emergency rescue plan for train accidents, a rapid 3D reconstruction method of train accident scene based on a monocular image was proposed. Taking two camera projection models for different application scenarios into consideration, the SIFT algorithm was introduced to extract and match image feature with the CAD model of an accident train. Geometric constraints between carriages were provided to transform the 3D reconstruction to solving a nonlinear least square problem with constraints, by which the position and pose of accident subjects were reduced at last. To quantitatively and qualitatively verify the calculation performance of this method, the mimicked train accident scene and real train accident scene were respectively used to carry out 3D reconstruction. The precise finite camera projection model was applied in the mimicked train accident scene to carry out offline calibration, and the stable pin-hole model was adopted in the real train accident scene to carry out auto calibration. Analysis result shows that through quantitative analysis of mimicked scene the maximal and average relative error of 8 nodes for measurement in reconstructing two carriages are 4.54% and 1.85% respectively. Through qualitative analysis of the real scene, the 3D reduction of position and pose for carriages can also be realized with combining the topographic information correction. The whole accident environmental panorama can be reduced visually with the help of 3D visualization engine. This method can also be used in developing emergency rescue electronic sand table for train accident analysis and safety education

Image-based 3D Scene Reconstruction and Rescue Simulation Framework for Railway Accidents

Although the railway transport is regarded as a relatively safe transportation tool, many railway accidents have still happened worldwide. In this research, an image-based 3D scene reconstruction framework was proposed to help railway accident emergency rescues. Based on the improved constrained non-linear least square optimization, the framework can automatically model the accident scene with only one panorama in a short time. We embedded the self-developed global terrain module into the commercial visualization and physics engine, which makes the commercial engine can be used to render the static scene at anywhere and simulate the dynamic rescue process respectively. In addition, a Head Mounted Device (HMD) was integrated into this framework to allow users to verify their rescue plan and review previous railway accidents in an immersive environment

Robust DOA Estimation for Sources with Known Waveforms Against Doppler Shifts via Oblique Projection

As known, utilization of the information about signal waveform can improve the direction of arrival (DOA) estimation results. However, with a fast moving platform, Doppler effect occurs, which distorts the known waveforms and may result in large DOA estimation bias and even error for conventional DOA estimation methods for sources with known waveforms. To deal with this problem, a robust DOA estimation method for sources with known waveforms against Doppler shifts is developed. The proposed method first transforms the nonlinear mixing of Doppler shifts in the model to an approximately linear one using discrete-time Fourier transform (DTFT) and finite Taylor series expansion. Then, multiple oblique projectors are constructed to separate each component corresponding to different order of derivatives. Finally, estimations of DOAs, complex amplitudes and Doppler shifts are obtained simultaneously. Simulation results show that the proposed method has a much more robust DOA estimation performance than existing methods for sources with known waveforms

The Synthesis and Characterization of LiFeAs and NaFeAs

The newest homologous series of superconducting As-pnictides, LiFeAs (Li111) and NaFeAs (Na111) have been synthesized and investigated. Both crystallize with the layered tetragonal anti-PbFCl-type structure in P4/nmm space group. Polycrystalline samples and single-crystals of Li111 and Na111 display superconducting transitions at ~ 18 K and 12-25 K, respectively. No magnetic order has been found in either compound, although a weak magnetic background is clearly in evidence. The origin of the carriers and the stoichiometric compositions of Li111 and Na111 were explored.Comment: submitted for publication in Physica C special issue on Fe-pnictide

Pharmacogenetic aspects of the use of tacrolimus in renal transplantation: Recent developments and ethnic considerations

Introduction: Tacrolimus (Tac) is effective in preventing acute rejection but has considerable toxicity and inter-individual variability in pharmacokinetics and pharmacodynamics. Part of this is explained by polymorphisms in genes encoding Tac-metabolizing enzymes and transporters. A better understanding of Tac pharmacokinetics and pharmacodynamics may help to minimize different outcomes amongst transplant recipients by personalizing immunosuppression.Areas covered: The pharmacogenetic contribution of Tac metabolism will be examined, with a focus on recent discoveries, new developments and ethnic considerations.Expert opinion: The strongest and most consistent association in pharmacogenetics is between the CYP3A5 genotype and Tac dose requirement, with CYP3A5 expressers having a ∼ 40-50% higher dose requirement compared to non-expressers. Two recent randomized-controlled clinical trials using CYP3A5 genotype, however, did not show a decrease in acute rejections nor reduced toxicity. CYP3A4∗22, CYP3A4∗26, and POR∗28 are also associated with Tac dose requirements and may be included to provide the expected improvement of Tac therapy. Studies focusing on the intracellular drug concentrations and on calcineurin inhibitor-induced nephrotoxicity also seem promising. For all studies, however, the ethnic prevalence of genotypes should be taken into account, as this may significantly impact the effect of pre-emptive genotyping

A rapid and cheap protocol for preparation of PCR templates in peanut

This paper describes a simple, low cost and reliable DNA template preparation protocol for polymerase chain reaction (PCR) using immature leaves from peanut seeds or leaves from field-grown plants. The technique may find wide utility in studies involving PCR-based molecular markers, rapid screening for transformants and gene cloning

Quantifying atmospheric nitrogen deposition through a nationwide monitoring network across China

A Nationwide Nitrogen Deposition Monitoring Network (NNDMN) containing 43 monitoring sites was established in China to measure gaseous NH3, NO2, and HNO3 and particulate NH4+ and NO3− in air and/or precipitation from 2010 to 2014. Wet/bulk deposition fluxes of Nr species were collected by precipitation gauge method and measured by continuous-flow analyzer; dry deposition fluxes were estimated using airborne concentration measurements and inferential models. Our observations reveal large spatial variations of atmospheric Nr concentrations and dry and wet/bulk Nr deposition. On a national basis, the annual average concentrations (1.3–47.0 μg N m−3) and dry plus wet/bulk deposition fluxes (2.9–83.3 kg N ha−1 yr−1) of inorganic Nr species are ranked by land use as urban > rural > background sites and by regions as north China > southeast China > southwest China > northeast China > northwest China > Tibetan Plateau, reflecting the impact of anthropogenic Nr emission. Average dry and wet/bulk N deposition fluxes were 20.6 ± 11.2 (mean ± standard deviation) and 19.3 ± 9.2 kg N ha−1 yr−1 across China, with reduced N deposition dominating both dry and wet/bulk deposition. Our results suggest atmospheric dry N deposition is equally important to wet/bulk N deposition at the national scale. Therefore, both deposition forms should be included when considering the impacts of N deposition on environment and ecosystem health

Transformation of β-Ni(OH)2to NiO nano-sheets via surface nanocrystalline zirconia coating: Shape and size retention

Shape and size of the synthesized NiO nano-sheets were retained during transformation of sheet-like β-Ni(OH)2to NiO at elevated temperatures via nano-sized zirconia coating on the surface of β-Ni(OH)2. The average grain size was 6.42 nm after 600 °C treatment and slightly increased to 10 nm after 1000 °C treatment, showing effective sintering retardation between NiO nano-sheets. The excellent thermal stability revealed potential application at elevated temperatures, especially for high temperature catalysts and solid-state electrochemical devices