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We demonstrate that generalized Weyl points can exist in a parameter space and we report the first observation of such nodal points in one-dimensional photonic crystals in the optical range. The reflection phase inside the band gap of a truncated photonic crystal exhibits vortexes in the parameter space where the Weyl points are defined and they share the same topological charges as the Weyl points.
With the rapid development of bulk power grid under extra-high voltage (EHV) AC/DC hybrid power system and extensive access of distributed energy resources (DER), operation characteristics of power grid have become increasingly complicated. To cope with new severe challenges faced by safe operation of interconnected bulk power grids, an in-depth analysis of bulk power grid security defense system...
We study the noise of a class-A dual-frequency vertical external cavity surface emitting laser at Cesium clock wavelength. Both the intensity noise and phase noise of the beatnote between the two orthogonal polarized modes are measured and modeled. The intensity noise of the two orthogonal laser modes and its correlation are well predicted by a theory based on modified rate equations. The phase noise...
Heart failure (HF) is one of the most common causes of hospitalization for people over 65 years old, and over half of patients who diagnosed with severe HF conditions at first time cannot survive over 5 years. It is also noticed that rehospitalization rate of heart failure patients may increase to 50% in three months and the mortality rate from 33% to 50% within five years if HF patients are not treated...
Various indices are used for assessing vegetation and soil properties in satellite remote sensing applications. Some indices, such as NDVI and NDWI, are defined based on the sensitivity and significance of specific bands. Nowadays, remote sensing capability with a good number of bands and high spatial resolution is available. Instead of classification based on indices, this paper explores direct classification...
A teaching example is built in Simulink, and then, based on the communication between Matlab and LabVIEW, a teaching virtual platform in LabVIEW is realized. This platform is about a wind power generation system and used mainly for the Renewable Energy Sources course of the undergraduate students of electrical engineering major. Compared with Simulink simulation teaching, the virtual platform adopts...
Industry applications in fields of electrical engineering have a high demandfor engineers with knowledge and experience in using digital signal processor(DSP). Many universities offer this type of training in DSP and motor control courses. However, in traditional teaching of motor control with DSP platform, it is difficult for the undergraduate students of electrical engineering to program the motor...
The heat generated by self-propagating exothermic reaction can be used to melt solder and then join the components. However, the microstructure of self-propagating interconnects is different from those obtained through traditional soldering process for its unique thermal conditions. In this paper, a finite element model was established to simulate the temperature field of self-propagating joints at...
Electromagnetic interference (EMI) is a critical problem for pulsed magnet system, especially for those sophisticated measuring sensors used in synchrotron accelerator. The purpose of this paper is to estimate and reduce the conductive and radiated EMI from a kicker magnet and its power supply. A line impedance stabilization network system was implemented to measure the EMI spectrum of the kicker...
Al/Ni self-propagating nanofoil can be used as a localized and rapid heat source to melt solder and achieve material connection. In this paper, air natural convection, thermal insulation and contacting heat transfer of the bonding process were considered separately to analyze the maximum fusion zone size of Sn solder by FEA model. The simulation works analyzed the temperature field and temperature...
A structure of Cu/IMCs/Ni micro-joint has been prepared from Cu/Sn (1.5µm)/Ni sandwich layers through the transient liquid phase soldering at 240 °C and 290 °C. On the result of microstructural observation, two layers can be distinguished as the thick (Cu, Ni)6Sn5 layer beneath the upper layer of thin (Cu, Ni)3Sn layer, to constitute the IMCs interlayer in micro-joint formed at 240 °C with dwell time...
Incorporating reinforcements into solder is an effective way to inhibit the growth of interfacial IMCs layer and also improve the mechanical properties of solder joints. In this study, some composite solders were prepared by adding of four types of reinforcements into SAC305 solder matrix respectively, including SiC nanowires, SiC, ZnO and Ni nanoparticles through the methods of mechanical ball milling...
Click Trough Rate (CTR) estimation is a crucial measure (or procedure) in online digital advertising (Ad). It defines the probability of a displayed Ad being clicked by viewers, and can serve as a performance metric to validate the effectiveness of Ad campaigns with respect to pages, sites, or media types etc. Due to real-time response nature of the online digital advertising eco-systems, it is vital...
Photodynamic therapy (PDT) is a light-based treatment modality that has shown promise for treatment of early stage oral lesions and potential to be adaptable for successful implementation in resource limited settings. To operate in such conditions a PDT light source must be engineered to be robust and portable, with flexible fiber optic light delivery that provides stable output in the desired spectral...
Based on the analysis of the negative sequence characteristics of the traction load and the influence of the negative sequence on the operation of the wind farm, this paper presents a method to quantitatively evaluate the effect of electrified railway on wind farms, and the critical electrical distance from the wind farm to the public connection point (PCC) is calculated from the angle of practical...
A 65 m diameter full-steerable radio telescope TMRT with the frequency coverage from 1.25 to 50.0 GHz is newly built at Shanghai. To satisfy the demands of the pulsar and spectral line observations, a Digital Backend System (DIBAS) was built for this telescope. The DIBAS can support both the pulsar search and online folding pulsar observation. Either the coherent or incoherent dedispersion pulsar...
Self-propagating exothermic reaction has been developed as a heat source to melt solder alloy during interconnection process for its high combustion heat and short duration. The solidification of solder alloy has occurred in a rapid cooling condition, which would be different from the situation of traditional reflow soldering. In this paper, the self-propagating exothermic reaction of Al/Ni multilayer...
A broadband differentially-fed circularly polarized (DFCP) antenna and a low-profile broadband DFCP antenna are proposed in this paper. Both antennas are made up of folded off-center-fed dipoles and are differentially-fed by two coaxial cables through a microstrip stub. It is shown that the DFCP antenna achieves a bandwidth of 44% (1.76–2.75 GHz) for differential reflection coefficient <−15 dB...
The problem of formation control of a group of quadrotors without linear velocity measurements is addressed in this paper. A distributed controller is developed directly on the orthogonal group SE(3) to avoid the singularities associated with Euler-angles and the ambiguity of quaternions. The control design procedure can be divided into two main steps. First, an intermediary control input is designed...
In view of the nonlinear, time-varying characters about the high precision photoelectric servo stabilized platform, a higher order sliding mode disturbance observer based on super-twisting algorithm (HSMDO) has been proposed, which could improve the system's precision through add the estimated disturbance to the input terminal of the controller. And to weak the chattering problem of sliding mode control,...
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