摘要：
A social network is a social structure made up of a set of social actors (such as individuals or organizations) and a set of the dyadic ties between these actors. By contrast, for the fixed time duration the size of digital video would be much bigger than that of digital sound. Consequently, providers of social network services can offer real-time chatting among users which could offer satisfactory experiences for users. As one of the most popular content-based social network services (SNS), chatting service plays an important role in current big data era. Also average data packets' transmission via networks is another significant traffic. So how to offer satisfactory Quality of Service (QoS) for users is the key problem which will be solved for SNS provider. For real time communication among users, end-to-end time delay seems to be critical in user's experience. Therefore modeling and evaluating social network systems is an important and urgent issue which offers quantitative basis of SNS with high quality for users. For social network system, the scalability and robust are important for both service provider and users under the circumstance of a large number of users. On the basis of performance evaluation of social network system of one user case, we construct the SPN model and conduct numerical analysis to discover and report the performance with the addition of users. By taking hybrid traffic containing voice and data into account, this paper constructed a Stochastic Petri Net (SPN) model for data and ON/OFF voice traffic for social network system. Then, average time delay of the system was analyzed and model-based simulation is conducted with Stochastic Petri Net Package (SPNP) 6.0. Furthermore, for different parameters of burst rate, idle rate, number of data packets, traffic load and buffer size, variation trends on average time delay are derived thereby. On the basis of the work in this paper, further research on heterogeneous objects of social network systems can be carried on. A social network is a social structure made up of a set of social actors (such as individuals or organizations) and a set of the dyadic ties between these actors. By contrast, for the fixed time duration the size of digital video would be much bigger than that of digital sound. Consequently, providers of social network services can offer real-time chatting among users which could offer satisfactory experiences for users. As one of the most popular content-based social network services (SNS), chatting service plays an important role in current big data era. Also average data packets' transmission via networks is another significant traffic. So how to offer satisfactory Quality of Service (QoS) for users is the key problem which will be solved for SNS provider. For real time communication among users, end-to-end time delay seems to be critical in user's experience. Therefore modeling and evaluating social network systems is an important and urgent issue which offers quantitative basis of SNS with high quality for users. For social network system, the scalability and robust are important for both service provider and users under the circumstance of a large number of users. On the basis of performance evaluation of social network system of one user case, we construct the SPN model and conduct numerical analysis to discover and report the performance with the addition of users. By taking hybrid traffic containing voice and data into account, this paper constructed a Stochastic Petri Net (SPN) model for data and ON/OFF voice traffic for social network system. Then, average time delay of the system was analyzed and model-based simulation is conducted with Stochastic Petri Net Package (SPNP) 6.0. Furthermore, for different parameters of burst rate, idle rate, number of data packets, traffic load and buffer size, variation trends on average time delay are derived thereby. On the basis of the work in this paper, further research on heterogeneous objects of social network systems can be carried on.
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：
By using a torsion pendulum and a rotating eightfold symmetric attractor with dual modulation of both the interested signal and the gravitational calibration signal, a new test of the gravitational inverse-square law at separations down to 295 μm is presented. A dual-compensation design by adding masses on both the pendulum and the attractor was adopted to realize a null experiment. The experimental result shows that, at a 95% confidence level, the gravitational inverse-square law holds ( |α|≤1) down to a length scale λ=59 μm. This work establishes the strongest bound on the magnitude α of Yukawa-type deviations from Newtonian gravity in the range of 70–300 μm, and improves the previous bounds by up to a factor of 2 at the length scale λ≈160 μm.
摘要：
A modified barium vacancy formation mechanism in donor-doped barium titanate (BaTiO3) ceramics is proposed. Assuming a uniform distribution of barium vacancies at sintering temperature and only oxygen partial pressure and sintering temperature related concentration of unionized barium vacancies, the electrical characteristics have been calculated by solving a differential equation about electron level. The room-temperature resistivity and positive temperature coefficient of resistivity (PTCR) behaviors of donor-doped BaTiO3 semiconducting ceramics have been quantitatively computed. The results pointed out that the room-temperature resistivity changes as a U-type curve with an increase of donor concentration. Moreover, the PTCR effect of BaTiO3 semiconductive ceramics was calculated quantitatively under different conditions. Theoretical and experimental results for BaTiO3 semiconductive ceramics are compared and discussed.
摘要：
We present a perturbation technique to study the linear and nonlinear output characteristics of coherent photon transport in a parity-time ( PT)-symmetric double-microcavity system where one passive cavity contains a single quantum emitter. It is found that (i) for the linear transmission of a low-power input probe field, the output spectra of the proposed PT-symmetric system exhibit a single transparent resonance dip and two symmetric, strongly amplifying sidebands, i.e., an inverted dipole-induced transparency; and (ii) for the nonlinear transmission of the input probe field, giant optical third-order nonlinearities with high linear transmission rate and vanishing nonlinear absorption can be achieved efficiently when the system parameters are tuned properly so that a PT-symmetry phase transition occurs. The obtained results can be useful for quantum information processing, quantum nondemolition measurements of photons, and optical signal processing.
关键词：
energy dissipation;frequency dependency;hysteresis loop;two-relaxation-time model;viscoelasticity
摘要：
Energy dissipation in polymeric materials was studied using a two-relaxation-time model. A differential form of a constitutive relation was constructed with the viscoelasticity theory. Through the simulation of a cyclic loading and unloading test, the dependence of the dissipated energy on the model parameters and external loading variables was determined and analyzed. In particular, the characteristics of the hysteresis phenomenon of a material with more than one relaxation time were studied in detail.
摘要：
Based on the Preisach model for hysteresis loop, the resistance hysteresis loop characteristic of thermosensitive VO2 thin film is theoretically analyzed. The resistance characteristics dependent on temperature in the resistance hysteresis loop can be obtained through theoretical numerical calculation, and the numerical calculated results are in good agreement with the experimentally measured results of some VO2 thin film samples in our laboratory. The resistance characteristics calculated results can be utilized to predict the infrared responsivity of high sensitive microbolometer of VO2 thin film and direct the operating temperature optimization for microbolometer.
摘要：
In this paper, we characterize the global multipartite nonlocality in one-dimensional infinite-size spin-1/2 chains. For this purpose, we calculate the multipartite nonlocality of n-site subchains, and take the large- n limit. As n increases from 2 to 100, we find that the average revenue and the marginal revenue of nonlocality converge gradually, thus they can be used to characterize the global multipartite nonlocality in infinite-size chains. Furthermore, in the vicinity of the quantum phase transition (QPT) points of the transverse-field Ising model and the XXZ model, in the large- n limit, multipartite nonlocality becomes extremely sensitive to external perturbation, that is, arbitrarily small perturbation away from the QPT points would lead to a drastic change in the global nonlocality. This signal of QPTs is easily distinguishable, and can be used to detect QPTs. We also draw a vivid physical picture of multipartite correlations and QPTs by analogy with magnetic domains in ferromagnets.
摘要：
A lot of experimental and theoretical studies of a system in cavity quantum electrodynamics (cavity QED), which consists of two spatially separated quantum emitters strongly coupled to a single optical cavity mode, have recently attracted much interest in the quantum optics community for various quantum information applications. Here, we propose a method for high-order harmonic generation in a photonic crystal microcavity coupled to single semiconductor quantum dots (QDs). The system is coherently driven by a bichromatic laser consisting of the control and signal fields at low input power (a few nanowatts) and the cavity output power via the cavity loss channel is monitored. Via numerical simulations, we thoroughly explore the difference of the generated high-order harmonic spectra between two QDs, one QD, and zero QDs in microcavity. The results clearly indicate that harmonic generation can be significantly enhanced via collective coherent coupling in the case of two spatially separated QDs coupled to the same photonic crystal microcavity mode. In addition, we present a study of the carrier-envelope phase (CEP) effect on high-order harmonic spectra, which may provide the insight of CEP effect in a new regime. Beyond this, our obtained results also apply to other classes of single-mode cavity-QED setup incorporating two-level atoms or comparable solid-state emitters.
摘要：
This paper investigates adaptive synchronization of stochastic time-varying delay dynamical networks with complex-variable systems. By using the complex inequality, stochastic analysis theory and two kinds of random disturbances, several sufficient conditions to ensure adaptive synchronization for stochastic time-varying delay networks with complex-variable systems. To illustrate the effectiveness of the synchronization conditions derived in this paper, numerical examples are provided finally.
摘要：
The formation of infrared solitons in graphene under Raman excitation is investigated using density-matrix approach. We find that the unique band structure and selection rules for the optical transitions near the Dirac point can result in extremely strong optical nonlinearity. Theoretical investigations with the aid of slowly varying envelope approximation and perturbation theory clearly indicate the existence of bright and dark solitons in Landau-quantized graphene. Actually, the formation of spatial soliton in such a material is the consequence of the balance between nonlinear effects and the dispersion properties. Also, the corresponding carrier frequency is tunable in the infrared range. These results can make us know better the crossover between optical solitons and graphene metamaterials. The predicted nonlinear optical effect in graphene may provide a new possibility for designing high-fidelity graphene-based information processing device.
摘要：
The microbolometric exact theoretical output responsivity expression for a focal plane array is obtained for the first time. Based on the physical thermal model for a microbolometer, the temperature change behavior of the microbolometer is analyzed and discussed to get its theoretical temperature change expression under pulse voltage bias. With the temperature change expression and infrared response analysis of the microbolometer, the theoretical output responsivity expression is successfully derived. The theoretical responsivity expression reveals some key factors that affect and determine the infrared sensibility of the microbolometric array, which can be utilized to guide the design optimization for a microbolometric focal plane array. (C) 2015 Society of Photo-Optical Instrumentation Engineers (SPIE)
关键词：
Silicon;Silicon carbide;Quantum Dots;Bonding Configuration;Crystallization Mechanism;Plasma-Enhanced Chemical Vapor Deposition;Transmission Electron Microscopy
摘要：
We have investigated the crystallization process of silicon quantum dots (QDs) imbedded in hydrogenated amorphous Si-rich silicon carbide (a-SiC:H) films. Analysis reveals that crystallization of silicon QDs upon thermal annealing of the samples can be explained in terms of bonding configuration and evolution of microstructure. The precursor gases were dissociated via electron impact reactions in the plasma-enhanced chemical vapor deposition, where the hydrogenated silicon radicals and reactive SiHn species lead to the formation of primary Si nuclei. With increasing annealing temperature, the breaking of SiHn bonds and decomposition of Si-rich SiC were progressively enhanced, allowing the formation of crystalline silicon QDs inside the a-SiC:H matrix. The results help clarify a probable mechanism for the growth of silicon QDs and provide the possibility to optimize the microstructure of silicon QDs in a-SiC:H films.
摘要：
This paper describes a non-uniformity compensating method for microbolometric focal plane array. Through the analysis of the basic principle of conventional non-uniformity compensating methods for microbolometric focal plane array, we have pointed out their common fatal limitation unable to compensate the nonlinear non-uniformity of microbolometer array. Based on our previous constant power optimized bias, a novel and simple nonlinear non-uniformity compensating method for microbolometric focal plane array is proposed in this paper. The proposed compensating method is simply configured and can easily and effectively be utilized to compensate the nonlinear non-uniformity of microbolometer array. (C) 2014 Elsevier GmbH. All rights reserved.
摘要：
A new CMOS readout integrated circuit (ROIC) for microbolometric focal plane array (FPA) is proposed in this paper. By applying multiple-module parallel working technique, the pixel readout speed of the CMOS ROIC can reach 10 MHz, which is very suitable for large-scale microbolometer array. The CMOS ROIC of each parallel working module consists of three major parts: direct injection (DI) input circuits, column-shared integrating circuits, and common noise-suppressing circuits. The readout structure of the ROIC is simple because of the DI input, shared and common circuits, and this makes the ROIC satisfy the requirements of small-pixel microbolometric FPA. Furthermore, the voltage signals from different working modules can be output according to a certain order through a high-speed output circuit. An experimental readout chip based on the proposed ROIC has been designed and fabricated to verify its readout function and performance. The measurement results of the experimental readout chip have successfully proved that the proposed CMOS ROIC can be applied to high-speed, low-noise, large-scale and high-resolution microbolometric FPA. (C) 2014 Elsevier GmbH. All rights reserved.
