Fractal characteristics and damage evaluation of corroded beams under four-point bending tests based on acoustic emission techniques

This study investigated the relationship between the acoustic emission (AE) signals parameter sequence fractal characteristics and the damage evolution information of corroded reinforced concrete (RC) beams under four-point bending. Strength deterioration behavior and AE data can be obtained by coupling the four-point bending test and the AE monitoring. The results show that AE ringing counts of corroded and uncorroded beams had prominent fractal characteristics. The fractal dimension values of corroded RC beams all showed a fluctuating rise to a peak and then a sharp drop before the failure. The damage index corresponding to the peak point decreases with the increase of corrosion degree. Fractal dimension peak point could be used as an early warning point for corroded RC beams' failure. Moreover, the AE fractal dimension analysis can effectively reflect the pattern of crack development, which have an important value for evaluating the process of corroded RC beams rupture.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Concrete Structure

EdgeTuner: Fast Scheduling Algorithm Tuning for Dynamic Edge-Cloud Workloads and Resources

Edge-cloud jobs are rapidly prevailing in many application domains, posing the challenge of using both resource-strenuous edge devices and elastic cloud resources. Efficient resource allocation on such jobs via scheduling algorithms is essential to guarantee their performance, e.g. latency. Deep reinforcement learning (DRL) is increasingly adopted to make scheduling decisions but faces the conundrum of achieving high rewards at a low training overhead. It is unknown if such a DRL can be applied to timely tune the scheduling algorithms that are adopted in response to fast changing workloads and resources. In this paper, we propose EdgeTuner to effectively leverage DRL to select scheduling algorithms online for edge-cloud jobs. The enabling features of EdgeTuner are sophisticated DRL model that captures complex dynamics of Edge-Cloud jobs/tasks and an effective simulator to emulate the response times of short-running jobs in accordance to dynamically changing scheduling algorithms. EdgeTuner trains DRL agents offline by directly interacting with the simulator. We implement EdgeTuner on Kubernetes scheduler and extensively evaluate it on Kubernetes cluster testbed driven by the production traces. Our results show that EdgeTuner outperforms prevailing scheduling algorithms by achieving significant lower job response time while accelerating DRL training speed by more than 180x.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Distributed System

Visualization of flow separation inside cut kerf during laser cutting of thick sections

The behavior of oxygen gas not only determines the oxidation heat input but also affects the removal of molten metal during laser-oxygen cutting. Flow separation inside the cut kerf is the major problem for the deterioration of cut ability and cut quality, especially for cutting thick steel sections, because it significantly weakens the shear stress on molten slag and changes the pressure gradient along the cut front. There have been some researches on flow separation using numerical simulation and model kerf. However, many experimental details and results are unclear, and the numerical simulation is questionable due to lack of experimental verification. In this paper, a model kerf is set up based on the previous results of observation and cutting trials. High resolution and high speed Schlieren visualization is used to observe the formation of flow separation in the model kerf. Stand-off distance, inlet pressure, cut front slope, nozzle displacement, kerf width, and nozzle tilting angle are used as variables for Schlieren visualization of flow separation for both a conical subsonic and a minimum length nozzle supersonic nozzle. The effect of the above parameters on the position and the pattern of flow separation is discussed based on the gas dynamic theory. It is found that nozzle displacement, kerf width, and nozzle tilting angle are the key factors for flow separation. Possible strategies for controlling flow separation are also proposed for both subsonic and supersonic nozzles. (C) 2016 Laser Institute of America

An Efficient and Simple Method for Stereoselective Synthesis of N-Substituted Iminosugars from D-Xylose Derivative

A series of new N-substituted iminosugars were successfully synthesized through a general synthetic route from D-xylose derivative. This approach provided a convenient access to the synthesis of N-alkylated iminosugars as potential glucosidase inhibitors, which included a reaction of reductive amination. Various N-alkylated iminosugars were prepared in good yields with high stereoselectivity

Surface Tension and Its Temperature Coefficient of Molten Tin Determined with the Sessile Drop Method at Different Oxygen Partial Pressures

The surface tension of molten tin has been determined by the sessile drop method at The surface tension of molten tin has been determined by the sessile drop method at temperatures ranging from 523 to 1033 K and in the oxygen partial pressure (P-O2) range from 2.85 x 10(-19) to 8.56 x 10(-6) MPa, and its dependence on temperature and oxygen partial pressure has been analyzed. At P-O2 = 2.85 x 10(-19) and 1.06 x 10(-15) MPa, the surface tension decreases linearly with the increase of temperature and its temperature coefficients are -0.151 and -0.094 mNm(-1) K-1, respectively. However, at high P-O2 (3.17 x 10(-10), 8.56 x 10(-6) MPa), the surface tension increases with the temperature near the melting point (505 K) and decreases above 723 K. The surface tension decrease with increasing P-O2 is much larger near the melting point than at temperatures above 823 K. The contact angle between the molten tin and the alumina substrate is 158-173degrees, and the wettability is poor

Placebo analgesia affects the behavioral despair tests and hormonal secretions in mice

The placebo effect is a fascinating yet puzzling phenomenon, which has challenged investigators over the past 50 years. In previous studies, the investigators only focused on the placebo effect obtained within a single domain, and pain is the field in which most of the placebo research has been performed. However, recent research by our laboratory (Zhang and Luo in Psychophysiology 46:626-634, 2009; Zhang et al. 2011) showed that, in human subjects, the placebo effect can be transferred from one domain to the other, namely from pain to emotion

Spectral Characteristics of Biological Soil Crusts under the Different Types in the Water-Wind Erosion Crisscross Region on the Loess Plateau

The study on spectral characteristics of biological soil crust in the water-wind erosion crisscross region in the Loess Plateau has important scientific value for the identification of biological soil crust based on remote sensing technology at regional scale, also provides important technical support for estimating the effect of biological soil crust on regional soil erosion control. The spectra of higher vegetation as well as the biological soil crust of algae with different coverage and different types of mosses were measured and quantified by Surface Species Spectrometry. The results are as follows, the algal bio-soil crust has similar spectral characteristics with soil in the water-wind erosion crisscross region in the Loess Plateau, and there is no obvious "peak valley" characteristic in the spectral curve. The reflectivity was reduced by the increasing coverage of the biological soil crust. Compared with the bare area, the spectral reflectance normalized mean of algae biological soil crust deceased 8. 64%, 15. 80% and 23. 09% respectively in the coverage of 10% to 20%, 30% to 40% and 50% to 60% in the visible area. The absorption characteristic at 680 nm (Chlorophyll) became increasingly obvious and the absorption valley at 2 200 nm (secondary mineral) became smaller as the coverage of algae biological soil crust increased. The spectral curve of moss biological soil crust showed the reflection peak of the green band, the absorption valley of the red light band and the high reflection of the near infrared band, which is similar with the vegetation. In the range of 760 similar to 930 nm, the slope of moss biological soil crust was 2. 5 to 4. 5 timed higher than that of vegetation. The study can provide some theoretical basis and technical support for the identification of biological soil crust

Morphological and physiological responses of different wheat genotypes to chilling stress: a cue to explain yield loss

BACKGROUNDThe eco-physiological mechanism of wheat yield loss resulting from chilling stress is a fundamental scientific issue. However, previous studies have focused on hexaploid wheats, and few studies on the morphological and physiological plasticity of wheat plants. Six different wheat genotypes were tested under chilling stress to investigate the physio-morphological parameters as well as the loss of grain yield in growth chambers. RESULTSChilling stress resulted in significant loss in grain yield in all genotypes. Under chilling stress, diploid wheats generated zero harvest, and tetraploid genotypes also suffered from a pronounced loss in grain yield, compared with the control group. In contrast, hexaploid genotypes acquired relatively high maintenance rate of grain yield among three species. CONCLUSIONSDiploid and tetraploid wheat genotypes maintained relatively large leaf area and high photosynthetic rates, but they were subjected to significant declines in vascular bundle number and productive tillers as a consequence of the inhibition by sink growth under chilling stress. The hexaploid wheats were found to have relatively low leaf area and photosynthetic rates. These genotypes also stored more soluble carbohydrates and exhibited stronger sink enhancement, ensuring the translocation and redistribution of assimilates. Our findings provided a new theoretical understanding of yield stabilization in the domestication process of wheat genotypes under chilling stress. (c) 2017 Her Majesty the Queen in Right of Canada. Journal of The Science of Food and Agriculture (c) 2017 Society of Chemical Industr

The long rather than the short allele of 5-HTTLPR predisposes Han Chinese to anxiety and reduced connectivity between prefrontal cortex and amygdala

The short allele of the serotonin-transporter gene is associated with higher risk for anxiety and depression in Caucasians, but this association is still unclear in Asians. Here, we addressed this issue using behavioral and multi-modal MRI approaches in a large group of healthy Han Chinese participants (n = 233). In contrast to findings in Caucasians, we found that long-allele (L) carriers had higher anxiety scores. In another group (n = 64) experiencing significant levels of depression or anxiety, the L-allele frequency was also significantly higher. In healthy participants, L-carriers had reduced functional and anatomical connectivity between the amygdala and prefrontal cortex (PFC), which was correlated with anxiety or depression scores. Our findings demonstrated that in Chinese Han participants, in contrast to Caucasians, the L-allele confers vulnerability to anxiety or depression and weakens top-down emotional control between the PFC and amygdala. Therefore, ethnic background should be taken into account in generelated studies and their potential clinical applications