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Folded reflectarray antenna features high gain, low profile, and low sidelobe level, but also faces several challenges in scannability, manufacturing, assembling, and integration with planar circuits, especially at millimeter-wave and terahertz frequencies. To alleviate these issues, this paper presents a slot antenna based on substrate integrated waveguide (SIW) to replace conventional horn. This SIW slot antenna is then inherently integrated with reflectarray elements in the same single-layered printed circuit board (PCB) for the first time. Moreover, this folded reflectarray is able to scan its narrow beams in 2-D, by controlling the polarizing grids. The whole reflectarray is fabricated by the commercial low-cost PCB process and can be highly integrated with planar active circuits. Measured results show that the proposed reflectarray achieves a 2-D scanning zone of 14° $\times$ 14°, a gain of 27.4 dBi, and a cross-polarization level less than −24 dB. The proposed folded reflectarray is promising for several application scenarios including millimeter-wave high-resolution imaging and fifth-generation communications. [ABSTRACT FROM AUTHOR]

The Cooray–Rubinstein formula is most widely used to evaluate the horizontal electric field generated by a lightning return stroke over a lossy ground. In this paper, a new method for fast evaluation of the Cooray–Rubinstein formula in time domain is proposed, by means of approximating the integral form of the modified Bessel function of the first kind using Gauss numerical integral. In the proposed method, the integral form of the modified Bessel function of the first kind is expressed by a summation of exponential functions, and a recursive convolution is achieved, which makes the calculation of the Cooray–Rubinstein formula in time domain much more efficient. Besides, the residues and poles due to the expression of the kernel function K( s) can be obtained directly for any ground conductivity and permittivity which makes the method proposed very simple and easy to program. The numerical examples demonstrate the validity and efficiency of the proposed method. [ABSTRACT FROM PUBLISHER]

Cooray–Rubinstein formula has been extensively used for the evaluation of the horizontal component of the electric field generated by a lightning return stroke over a lossy ground. Considering the good characteristics of the formulation in terms of “step response” kernel $K_{\varepsilon }(t)$ corresponding to the ground surface impedance, proposed by Andreotti et al. recently, a new method for evaluating the Cooray–Rubinstein formula in the time domain is proposed in this paper. In this method, $K_{\varepsilon }(t)$ is first expressed by an integral of exponential function based on the integral formula of the modified Bessel function of the first kind, and then approximated by a piecewise exponential function using the Gauss numerical integration. Finally, taking advantage of the piecewise recursive convolution, the time-domain Cooray–Rubinstein formula for evaluating the lightning horizontal electric field can be calculated accurately and efficiently. The validity and efficiency of the proposed method are demonstrated by the comparisons with the methods in other literature. [ABSTRACT FROM AUTHOR]

Hybrid hydrogen-electric vehicles (H2EVs) are developing rapidly in recent years. Evidently, the planning of H2EVs energy-supplying facilities (HVESFs) is important. It involves the coupled power flow of power network (PN), mass flow of hydrogen network (HN), and traffic flow of traffic network (TN), simultaneously. These coupled flows would indeed challenge economic and secure performances of HVESFs planning, especially when uncertain renewable energy is introduced. Therefore, a multinetwork framework considering coupled flow constraints is proposed for the planning issue of HVESFs, involving all the PN, HN, and TN. Therein, we first propose a modified maximum covering location method, in order to satisfy the energy demand of H2EVs. On this basis, a many-objective optimization-based bi-level HVESFs planning model is developed. Then, we use a hybrid differential evolution-interior point algorithm to solve this model, and obtain the planning solutions. Simulation results verify the feasibility and effectiveness of the proposed planning model, which has better performances compared to the existing approach. [ABSTRACT FROM AUTHOR]

Reducing energy consumption is very important in solving the problem of energy crisis and environmental problem. Usually, an elevator with a diode rectifier wastes regenerated power from its electric motor as heat on breaking resistors. This paper proposes an energy feedback digital system used in an elevator of 18.5 kW which is capable of recycling the regenerated power: obtaining near-unity power factor, sinusoid output current, and low total harmonic distortion in generator-operation state. It has reliable protection circuits and cute man–machine interface, and the feedback point of the dc voltage can be set arbitrarily in a certain extent, meeting the large-range variation of power system voltage. Field operation results showed good performance and energy-saving effect. [ABSTRACT FROM AUTHOR]

Hand motion tracking is useful in human-computer interface and many other applications requiring human-machine interactions. In this work, permanent magnets and contactless magnetic sensors are used to track finger motion. A magnet patch is affixed to each fingernail to mark the location and orientation of the fingertip. When fingers move, the combined magnetic fields produced by the magnets at fingertips are recorded by a set of magnetic sensors around a wristband. The recorded data from the sensors are utilized to calculate the magnets' locations and orientations, which can provide estimate of the hand posture based on a geometric hand model. [ABSTRACT FROM PUBLISHER]