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The text in this paper is for visual purpose only. No rights can be taken from this. The hollow slab with reinforced or pre-stressed concrete has been broadly used in the construction of the bridge under 20 meters because it has the advantages of light weight, good performance of structure, convenient transportation, standardized production and construction. However, because the mechanism among the force transfers of the hinge joint is so complex that the traditional theory and algorithms are impossible to analyze them in good precision quantitatively. The early diagnosis system for the hinge joint disease of hollow slab bridge can execute the state-above task successfully. The system in the Figure 1, an Internet of things, is composed of modern technologies such as sensing, network, artificial intelligence, and fuzzy comprehensive analysis. The system mainly solve the hree aspects: Figure 1 The architecture of the early diagnosis system. https://s3.rawdatalibrary.net/s3-euw1-ap-pe-df-pch-content-public-p/9781315207681/cd556cd4-4dcf-4efe-8e29-56fc67b8bfbd/content/fig223_1.tif"/> – Index of the damage: to monitor the current status of the hinge joint, specific technology can be applied to pick up the dybanuc information of the joint structure. The number of various sensors are deployed on the middle of beams, piers, and two ends of bridge in order to collect the real-time data of immunity, vibration frequency and amplitude, crack, displacement and so forth. The parameters can describe the dynamic characteristics of the hinge joint structure fully and accurately. – The time and spatial location of the damage: All of the sensors are able to collect the information of the hinge joint with time and date stamps in 24 hour/day and 365 day/year. As soon as any of their values is over thresholds, the system can determine the warning sensor and its location. – Severity of the damage: based upon the technical standards from nations, the five risk grades are defined to represent the severity of the damage for the hinge joint. The early diagnosis system makes use of modern sensing technology to collect the dynamic information near the hinge joints, the data are pre-processed and changed to unique TCP/IP communication prototype, then, by GPRS are transmitted to a remote data center where the information are stored, modeled in fuzzy theory, analyzed in a fuzzy comprehensive algorithm. Because of the application of sensing technology, the installation of sensors and data transfer by wire or wireless is very simple without the closing traffic. The sensors with very high sensitivity and precision can find out the early tiny changes of the hinge joint structure so that the damage can be controlled in time. It will dramatically reduce the maintenance costs and extend the service life of the hollow slab bridge effectively.
The rapid development of semiconductor materials and devices has brought tremendous development opportunities to optoelectronics, intelligent manufacturing, Internet of Things, power electronics, and even innovative energy technologies. Among them, the third and fourth generation semiconductors represented by ZnO, GaN, SiC, and Ga2O3 are two kinds of emerging strategic material systems. Due to their large energy bandgaps, they exhibit excellent performance in application scenarios of high voltage, high frequency, and high temperature resistance, making them great candidates in high-power, radio frequency, and optoelectronic devices. The third and fourth generation semiconductors usually possess non-centrosymmetric crystal structures, which makes the piezoelectric polarization effect a fundamental characteristic for the third and fourth generation semiconductors in contrast to the first and second generation semiconductors as represented by Si, Ge, and GaAs. Research studies on the coupling of piezoelectricity, semiconductor, and light excitation properties were coined as piezotronics and piezo-phototronics in 2007 and 2010, respectively, by Zhong Lin Wang. The piezotronic and piezo-phototronic effects open another avenue for further improvement of the performance of electronic and optoelectronic devices. This Perspective will first introduce the basic concepts and principles of piezotronics and piezo-phototronics and the basic characteristics of the third and fourth generation semiconductors. Then, progress, challenges, and opportunities of ideal materials, comprehensive physical models, and outstanding applications based on piezotronics and piezo-phototronics are presented with emphasis. Finally, conclusions and outlooks are drawn for the piezotronics and piezo-phototronics based on the third and fourth generation semiconductors.
The shapes and sizes of platinum nanoparticles were controlled by changes in the ratio of the concentration of the capping polymer material to the concentration of the platinum cations used in the reductive synthesis of colloidal particles in solution at room temperature. Tetrahedral, cubic, irregular-prismatic, icosahedral, and cubo-octahedral particle shapes were observed, whose distribution was dependent on the concentration ratio of the capping polymer material to the platinum cation. Controlling the shape of platinum nanoparticles is potentially important in the field of catalysis.
