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Inspired by increasing demand of advanced pulsed power capacitors, the development of lead-free dielectric ceramic capacitors with high energy storage density and temperature-insensitive performance are extremely crucial. Herein, the lead-free relaxor ferroelectric ceramics based on (1-x) (Na0.5Bi0.5)0.6Sr0.4TiO3- xSr0.7La0.2ZrO3 [abbreviated as (1-x)NBST-xSLZ] are prepared by the solid-state reaction route. The large recoverable energy density (Wrec) of 3.45 J/cm3 and efficiency (η) of 90.1% are simultaneously realized in 0.86NBST-0.14SLZ ceramic due to increased breakdown strength. Furthermore, both the Wrec and η of 0.86NBST-0.14SLZ ceramic display superior of thermal stability (20–180 °C), frequency stability (1–1000 Hz), and cycle stability (104) within a satisfactory range of variation. In addition, the 0.86NBST-0.14SLZ ceramic can also achieve a large current density (CD) of 625 A/cm2, an ultrahigh power density (PD) of 50 MW/cm3 and a fast discharge rate (τ0.90) of 160.8 ns at 160 kV/cm. These results demonstrate that the 0.86NBST-0.14SLZ ceramic could be a highly competitive and eco-friendly relaxor ferroelectric material for next-generation pulsed power capacitors.

Background: Shufeng Jiedu (SFJD) capsules can be used as adjunctive treatment for patients with community-acquired pneumonia, but the effectiveness and safety of SFJD are not clear. This review aims to evaluate the effectiveness and safety of SFJD based on randomized controlled trials (RCTs). Methods: A systematic review was conducted by searching PubMed, Embase, Scopus, Web of Science, CENTRAL, CNKI, VIP, CBM, Wanfang and trial registry platforms from their inception to March 2022. Two reviewers screened studies, extracted the data and assessed risk of bias independently. The data were pooled for meta-analysis or presented narratively. Results: Seventeen RCTs involving 1840 participants were included. All trials compared SFJD plus antibiotics to antibiotics, or combined with symptomatic treatment in both groups. The overall certainty of evidence was assessed as moderate to very low certainty. Compared with routine treatment (antibiotics alone or antibiotics plus symptomatic treatment), SFJD plus routine treatment showed beneficial effects in resolution of fever (MD −1.20 days, 95%CI −1.73 to −0.67; 10 RCTs; very low certainty), cough (MD −1.02 days, 95%CI −1.23 to −0.81; 9 RCTs; moderate certainty), phlegm (MD −1.46 days, 95%CI −2.84 to −0.08; 6 RCTs; very low certainty), pulmonary crepitations (MD −1.61 days, 95%CI −2.64 to −0.59; 8 RCTs; low certainty), shortness of breath (MD −2.80 days, 95%CI −2.88 to −2.72; 2 RCTs; low certainty) and chest pain (MD −2.85 days, 95%CI −3.01 to −2.69; 1 RCT; low certainty). There was no significant difference in pathogen clearance (1 RCT). No serious adverse events were reported, but 2.60% (5/192) patients reported nausea in the SFJD groups, 1.04% (2/192) participants in routine group, and no significant difference was identified. Conclusions: Current evidence suggests that adding SFJD may shorten the duration of symptom relief in community-acquired pneumonia for 1–2 days. The adverse events were minor and controllable, and no serious adverse events were reported. Well-reported trials and potential of reducing antibiotics were expected in the future studies.

In order to solve the problem that the equivalent relationship between space vector pulse width modulation (SVPWM) and carrier-based pulse width modulation (CBPWM) in the field of single phase multi-level inverters is still unclear, this paper drew on the equivalent realization method of three-phase multi-level inverters. And the equivalent relationship between the two modulation strategies of SVPWM and CBPWM was studied in depth according to the characteristics of the multilevel single phase diode clamped inverter. By injecting the deduced DC component into the CBPWM modulated wave, the same modulation output sequence as SVPWM was obtained, and by further strictly derived, the DC component formula realizing the equivalent of any number segment SVPWM sequences and CBPWM was obtained under single phase NPC n-level inverters. Finally, the experiment verifies correctness of the equivalent relationship.

While wireless sensors, data transmission devices and medical implant devices tend to miniaturization and low consumption, energy supply modes such as batteries, solar energy and wind energy are limited due to their defects. Instead, vibration energy harvesting can open up new possibilities for self-supplying the low-consumption devices. The narrow-band random vibration with center frequency is a typical vibration in the environment, and its characteristics are closely related to the environment.This paper takes the energy harvesting system with bi-stable piezoelectric cantilever beam as a research object, and the characteristics of system's equivalent linear natural frequency, linear and nonlinear stiffness under different intervals between magnets are analyzed. By using the narrow-band random excitation with a certain bandwidth output of the bandpass filter to simulate environment vibration and using Runge-Kutta method to solve the system equation numerically, the response of system and the characteristics of energy harvesting are studied.It is observed that the variation of the magnet spacings at peak output voltage, which possesses a central frequency, is related to the variation of the equivalent linear natural frequency of the system with the interval between magnets. When the variation of magnet spacing is triggered by the narrow-band random excitation with a certain bandwidth, there is always a constant interval between magnets, making the system produce a peak output, which is like a bi-stable system that produces the peak output at optimal spacing under broad-band excitation. On the other hand, there are also more than one or two different magnet spacings making the system produce peak outputs while excitation's center frequency changes in a certain range, and the peak outputs are formed by bi-stable or single-stable “resonance” of the system, induced at the equivalent linear natural frequency. And the demarcation point spacing of the single-stable and bi-stable vibration of the system are the magnet spacing when linear stiffness is zero.Therefore, for the narrow-band random excitation in the actual environment, the magnet spacing of the energy harvesting system can be reasonably arranged according to the specific working conditions to achieve better electromechanical energy conversion. The findings in this paper can provide some theoretical and technical support for the study of harvesting the vibration energy with characteristics of narrow-band random excitation.