会议论文集名称：
Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2018
关键词：
Wireless sensor;Structural health monitoring;Capacitive strain sensor;AC Wheatstone bridge
摘要：
A capacitance based large-area electronics strain sensor, termed soft elastomeric capacitor (SEC) has shown various advantages in infrastructure sensing. The ability to cover large area enables to reflect mesoscale structural deformation, highly stretchable, easy to fabricate and low-cost feature allow full-scale field application for civil structure. As continuing efforts to realize full-scale civil infrastructure monitoring, in this study, new sensor board has been developed to implement the capacitive strain sensing capability into wireless sensor networks. The SEC has extremely low-level capacitance changes as responses to structural deformation; hence it requires high-gain and low-noise performance. For these requirements, AC (alternating current) based Wheatstone bridge circuit has been developed in combination a bridge balancer, two-step amplifiers, AM-demodulation, and series of filtering circuits to convert low-level capacitance changes to readable analog voltages. The new sensor board has been designed to work with the wireless platform that uses Illinois Structural Health Monitoring Project (ISHMP) wireless sensing software Toolsuite and allow 16bit low-noise data acquisition. The performances of new wireless capacitive strain sensor have been validated series of laboratory calibration tests. An example application for fatigue crack monitoring is also presented.
摘要：
In a previous study, we have proposed a procedure to study global quantum discord in 1D chains whose ground states are described by matrix product states [Z.-Y. Sun et al., Ann. Phys. 359, 115 (2015)]. In this paper, we show that with a very simple generalization, the procedure can be used to investigate quantum mixed states described by matrix product density operators, such as quantum chains at finite temperatures and 1D subchains in high-dimensional lattices. As an example, we study the global discord in the ground state of a 2D transverse-field Ising lattice, and pay our attention to the scaling behavior of global discord in 1D sub-chains of the lattice. We find that, for any strength of the magnetic field, global discord always shows a linear scaling behavior as the increase of the length of the sub-chains. In addition, global discord and the so-called “discord density” can be used to indicate the quantum phase transition in the model. Furthermore, based upon our numerical results, we make some reliable predictions about the scaling of global discord defined on the n × n sub-squares in the lattice.
摘要：
Due to its high sensitivity to weak forces, the classical torsion pendulum was widely employed in the fields of precision gravitational measurement, which can be evaluated by testing of Newtonian inverse square law (ISL). In order to get much higher precision for the tests of ISL at short ranges, such as at millimeter and/or sub-millimeter level, the torsion pendulum cannot work precisely in free oscillation motion due to the electrostatic disturbance. This paper presents a method using proportional-integral-differential (PID) technology to make pendulum to keep quasi-static. A closed-loop system with PID controller is realized and calibration results show the system has the potential to get the precision of test of the ISL violation at the order of 10
<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−16</sup>
N·m at millimeter range.
摘要：
Due to the constant temperature oven, the OCXO can have a higher frequency stability in both long-term and short-term comparing to other crystal oscillators. However, most of OCXOs are using passive temperature control components, such as heating resistors or power transistors, which makes OCXOs have long warm-up time and ease to be affected by the ambient temperature fluctuation. In this paper, demonstration of using the thermoelectric cooler as the temperature control for the OCXO has been studied. Simulation results show good consistence with the test results for using the TEC for the OCXO. Temperature control test results demonstrate the feasibility of using the TEC to control the temperature of the OCXO to improve the warm-up time and have better temperature stability.
摘要：
Warm-up time, which is for the OCXOs to get the nominal frequency stability, is a critical factor for the application of OCXOs. In most OCXOs, the temperature sensing and control method is passive involving heating resistors or power transistors. This kind of configuration makes the normal warm-up time around/above 3 minutes, which is not suitable for the applications requiring quick start and test scenarios. In order to improve the warm-up time, this paper presents a new active temperature sensing and control method by employing a thermoelectric cooler (TEC) to shorten the warm-up time. Test results show the warm-up time could be less than 1 minute and the temperature stability of the OCXO with the TEC is better than the one without the TEC.
作者机构：
[Xu, Jian] Wuhan Polytech Univ, Sch Elect & Elect Engn, Wuhan 430023, Peoples R China.;[Xu, Jian; Jo, Hongki] Univ Arizona, Dept Civil Engn & Engn Mech, Tucson, AZ 85721 USA.
通讯机构：
[Jo, Hongki] U;Univ Arizona, Dept Civil Engn & Engn Mech, Tucson, AZ 85721 USA.
关键词：
Electroluminance;high-sensitivity;strain;structural health monitoring (SHM);visualization
摘要：
Visualized strain/stress sensing is receiving interests in structural health monitoring area, but former approaches cannot be effectively applied to civil infrastructure monitoring, because of limited sensitivity to low-level response and/or limited response to civil structures for both static and dynamic strain/stress. This paper presents a high-sensitivity and low-cost method to visualize the strain by employing the precisely controllable Wheatstone bridge and monochrome electroluminance (EL) technology. A sensor prototype is developed to convert the structural strain responses into visible brightness change with brightness change mode (BCM) and to color change with color alternation mode (CAM). In the BCM, the brightness can be changed according to the strain change. In the CAM, two different-color EL panels are used to light on to indicate the necessity for the professional structural health evaluation. Brightness linearity evaluation results show that the BCM is suitable for both static and dynamic low-level strain visualization. Bill of materials shows the cost of the prototype is as low as U.S. $46 including the EL panels.
摘要：
Visualizing mechanical strain/stress changes is an emerging area in structural health monitoring. Several ways are available for strain change visualization through the color/brightness change of the materials subjected to the mechanical stresses, for example, using mechanoluminescence (ML) materials and mechanoresponsive polymers (MRP). However, these approaches were not effectively applicable for civil engineering system yet, due to insufficient sensitivity to low-level strain of typical civil structures and limitation in measuring both static and dynamic strain. In this study, design and validation for high-sensitivity strain visualization using electroluminescence technologies are presented. A high-sensitivity Wheatstone bridge, of which bridge balance is precisely controllable circuits, is used with a gain-adjustable amplifier. The monochrome electroluminescence (EL) technology is employed to convert both static and dynamic strain change into brightness/color change of the EL materials, through either brightness change mode (BCM) or color alternation mode (CAM). A prototype has been made and calibrated in lab, the linearity between strain and brightness change has been investigated.
摘要：
The ground state of interacting spin chains in external magnetic fields can undergo a quantum phase transition (QPT) characterized by dramatic changes at a critical value of the magnetic field. In this paper, we use Bell-type inequalities to study the multipartite correlations (including multipartite entanglement and multipartite nonlocality in an n-spin subsystem) in the QPT of an infinite XY chain. An efficient numerical optimization procedure is proposed to figure out the violation measure Mn of the inequalities. For n≤7, the magnetic-field ( λ) dependence of Mn is studied. We find the derivative of Mn is divergent exactly at the QPT point λc=1 for any n. In addition, with the increase of n, Mn converges quickly for λ<λc and converges very slowly for λ>λc, which can be regarded as another signal for the QPT. Furthermore, in the vicinity of λc, high-order Bell-type inequalities will be violated as long as n is large enough. This indicates that high-level multipartite correlation will be present when the system is in the vicinity of the QPT point. Nevertheless, genuine n-partite entanglement or genuine n-partite nonlocality is not observed in the QPT.
摘要：
In this paper, using the infinite time-evolving block decimation (iTEBD) algorithm and Bell-type inequalities, we investigate multipartite quantum nonlocality in an infinite one-dimensional quantum spin- 12 XXZ system. High hierarchy of multipartite nonlocality can be observed in the gapless phase of the model, while only the lowest hierarchy of multipartite nonlocality is observed in most regions of the gapped antiferromagnetic phase. Thereby, Bell-type inequalities disclose different correlation structures in the two phases of the system. Furthermore, at the infinite-order quantum phase transition (QPT, or Kosterlitz-Thouless QPT) point of the model, the correlation measures always show a local minimum value, regardless of the length of the subchains. It indicates that relatively low hierarchy of multipartite nonlocality would be observed at the infinite-order QPT point in a Bell-type experiment. The result is in contrast to the existing results of the second-order QPT in the one-dimensional XY model, where multipartite nonlocality with the highest hierarchy has been observed. Thus, multipartite nonlocality provides an alternative perspective to distinguish between these two kinds of QPTs. Reliable clues for the existence of tripartite quantum entanglement have also been found.
摘要：
Due to the development of the wireless communication technologies, wireless sensor networks (WSNs) are becoming more and more important in Internet of Things (IOT). In this paper, we proposed a design of a WSN for the enormous constructions structural healthy monitoring. Based on the analysis of the past project about the WSN for the highway healthy monitoring, we propose a novel design that can be used to guide the design of the future WSNs for the structural healthy monitoring. The focus of the design is the hardware design and the network layer design between the hardware and the users. In this paper we consider that 1) the WSN could detect the parameters related to the structural healthy, 2) the network layer design shall be able to utilize advanced wireless communication technologies, 3) the WSNs shall be able to provide the monitoring functionality and easily be reached by the users.
摘要：
Bell inequalities and nonlocality have been widely studied in one-dimensional quantum systems. As a kind of quantum correlation, it is expected that bipartite nonlocality should be present in quantum systems, just as bipartite entanglement does. Surprisingly, for various models, two-qubit states do not violate Bell inequalities, i.e., they are local. Recently, it is realized that the results are related to the monogamy trade-off obeyed by bipartite Bell correlations, thus it is believed that for general translation invariant systems, two-qubit states should not violate the Bell inequality [Oliveira, Europhys. Lett. 100, 60004 (2012)]. In this Brief Report, we demonstrate that in perfect translation-invariant systems with an even number of sites, the Bell inequality can be violated. A nontrivial model is constructed to confirm the conclusion.
会议名称：
2013 International Conference on Computer Sciences and Applications
会议时间：
December 2013
会议地点：
Wuhan, China
会议主办单位：
Hubei Univ Technol
会议论文集名称：
2013 International Conference on Computer Sciences and Applications
关键词：
Microwave Frequency;Direct Digital Synthesizer;3G Mobile Communication;Jamming
摘要：
This paper proposed a versatile signal generator which employed a phase lock loop (PLL) chip and a direct digital synthesizer (DDS) chip to produce microwave signal for 3G mobile communication jamming. Based on the self-developed software, it could be controlled to produce single frequency, amplitude modulation (AM), frequency shift keying (FSK) or binary phase shift keying (BPSK) signal for different effective jamming applications. For different configuration or small changes, it could be used for other applications. Spectrum and infield tests demonstrated the jamming signals.
关键词：
Atomic clock;Coherent population trapping;Direct digital synthesizer;Low noise;Oscillator;Phase-lock loop
摘要：
This paper presents an digital microwave oscillator which employs a phase lock loop (PLL) chip and a direct digital synthesizer (DDS) chips to realize a pure frequency at 3.4170Hz (half of the 87Rb atom ground-state hyperfine transition frequency) for the coherent population trapping (CPT) atomic clock application. And at this frequency, the oscillator demonstrates low noise (lower than -50dBc/Hz@100Hz and lower than -55dBc/Hz@1kHz) and purity. Moreover, based on the communication between a computer and the MCU, this oscillator could be completely controlled by self-developed user interface.
