We present a fiber-optic extrinsic Fabry-Perot interferometer pressure sensor based on a nanothick silver diaphragm. The sensing diaphragm, with a thickness measured in a few hundreds of nanometers, is fabricated by the electroless plating method, which provides a simple fabrication process involving a high-quality diaphragm at a low cost. The sensor exhibits a relatively linear response within the pressure variation range of 0-50 kPa, with a high pressure sensitivity of 70.5 nm/kPa. This sensor is expected to have potential applications in the field of highly sensitive pressure sensors.

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A rigid fused π-conjugated segment has a bilaterally symmetric structure for most reported dyes synthesized with the strategy of rigidification in a solar cell. In this work, a series of dyes with an asymmetric or symmetric rigid π spacer were theoretically investigated through density functional theory and time-dependent density functional theory, to study how asymmetry in a conjugated spacer affects the photophysical properties. The asymmetry is achieved by benzene substitution at different positions in dithienothienodipyrrole. To make a more complete comparison, two more symmetric spacers were also designed by grafting a second benzene. The influence of benzene substitution on the short-circuit current (J sc ) and open-circuit voltage (V oc ) was expounded through analyzing the geometry, electronic structure, absorption spectra, and other microscopic parameters. Results demonstrated that substituting benzene lowers the light harvest efficiency and maximum photoinduced current. However, the asymmetric configuration of the spacer produced by benzene substitution could result in a narrow energy gap, efficient charge separation, faster interfacial electron injection, energetically promoting dye regeneration, and suppressing recombination. The shift of the conduct band, a key factor affecting V oc , is increased when substitution occurs from the donor end to the other end of the π spacer. The differences between symmetric and asymmetric rigid spacers originate from not only the nature of the component moiety, but also the substitution position. Taken all together, the asymmetric configuration with a more aromatic benzene on the donor side is more desirable compared to that on the other side and the symmetric spacers. Our work is expected to reveal the structure−property relationship and provide guidelines for further dye design.

This paper proposes a novel extended-single-phase shift (ESPS) control strategy of isolated bidirectional full-bridge DC-DC converters (IBDCs) which are a promising alternative as a power electronic interface in microgrids with an additional function of galvanic isolation. Based on the mathematical models of ESPS control under steady-state conditions, detailed theoretical and experimental analyses of IBDC under ESPS control are presented. Compared with conventional single-phase-shift (CSPS) control, ESPS control can greatly improve the efficiency of IBDCs in microgrids through decreasing current stress and backflow power considerably over a wide input and output voltage range under light and medium loads. In addition, ESPS control only needs to adjust one single phase-shift angel to control transmission power, thus it retains implementation simplicity in comparison with dual-phase-shift (DPS) control for microgrid applications. Furthermore, an efficiency-optimized modulation scheme based on ESPS and CSPS control is developed in the whole power range of IBDC for power distribution in microgrids. A 10 kW IBDC prototype is constructed and the experimental results validate the effectiveness of the proposed control strategy, showing that the proposed strategy can enhance the overall efficiency up to 30%.

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The conventional model-predictive-based direct power control (MPDPC) of the three-phase full-bridge AC/DC converters chooses the best single voltage vector for the following control period, which results in variable switching frequency and power distortion, and thus a relatively higher sampling frequency is needed to achieve acceptable results. This paper proposes a simplified dual-vector-based predictive direct duty-cycle-control (SPDDC) with an additional zero vector implemented in contrast to the MPDPC. With the same best vector selection method, the proposed strategy has retained the control simplicity with just one more step added and much better control performance as well as a fixed switching frequency in comparison to the MPDPC. On the other hand, the duty-cycle optimization procedure is eliminated while the negative duration issue is essentially resolved compared with the conventional dual-vector-based model predictive duty-cycle-control (MPDCC). Comprehensive comparisons of various control methods by numerical simulation and experimental testing show that the SPDDC can achieve better steady state and dynamic performance than the MPDPC and simpler algorithms than the MPDCC.INDEX TERMS AC/DC conversion, cost function, duty-cycle-control, duty-cycle optimization, model predictive control.

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