A novel cascaded H-bridge photovoltaic inverter with flexible arc suppression function

This paper presents a novel approach that simultaneously enables photovoltaic(PV)inversion and flexible arc suppression during single-phase grounding faults.Inverters compensate for ground currents through an arc-elimination function,while outputting a PV direct current(DC)power supply.This method effectively reduces the residual grounding current.To reduce the dependence of the arc-suppression performance on accurate compensation current-injection models,an adaptive fuzzy neural network imitating a sliding mode controller was designed.An online adaptive adjustment law for network parameters was developed,based on the Lyapunov stability theorem,to improve the robustness of the inverter to fault and connection locations.Furthermore,a new arc-suppression control exit strategy is proposed to allow a zerosequence voltage amplitude to quickly and smoothly track a target value by controlling the nonlinear decrease in current and reducing the regulation time.Simulation results showed that the proposed method can effectively achieve fast arc suppression and reduce the fault impact current in single-phase grounding faults.Compared to other methods,the proposed method can generate a lower residual grounding current and maintain good arc-suppression performance under different transition resistances and fault locations.

Association of Lifestyle Factors and Sperm Motility in Adults from an Ethnic Minority Region of Southwest China

Objectives: To understand sperm motility in adults and its association with lifestyle in an ethnic minority area in Southwest China. Methods: A hospital-based cross-sectional study to assess sperm motility in male adults was conducted at the Reproductive Health Center from January 2018 to May 2019. The data was collected with a questionnaire and semen quality was analyzed with Computer-Aided Sperm Analysis system (CASA). Analysis of covariance (ANCOVA) was used to measure the relationship between lifestyle factors and sperm motility. Results: A total of 349 people were recruited. Dietary celery intake was significantly related to the increase of sperm progressive motility and total motility (β = 7.00, 95% CI: 1.59, 12.42 and β = 7.26, 95% CI: 1.45, 13.07, respectively). Cola consumption was associated with increased sperm progressive motility (β = 9.71, 95% CI: 1.46, 17.96). Frequent use of plastic bags for meat food storage (β = -5.56, 95% CI: -10.61, -0.51), industry work (β = -5.64, 95% CI: -11.21, -0.07), organic disease (β = -6.14, 95% CI: -11.00, -1.28) and sedentary lifestyle (β = -5.92, 95% CI: -10.66, -1.17 for 3-5 h/d and β = -6.04, 95% CI: -11.60, -0.47 for ≥5 h/d, respectively) were related with the decreased sperm progressive motility. Meanwhile, using plastic bags for meat food storage (β = -6.37, 95% CI: -11.79, -0.95), industry work (β = -7.96, 95% CI: -13.94, -1.98) and sedentary lifestyle (β = -5.51, 95% CI: -10.60, -0.42 for 3-5 h/d and β = -6.03, 95% CI: -12.01, -0.06 for ≥5 h/d, respectively) were also risk factors for total motility. Conclusions: Some modifiable lifestyle factors such as job title, cola consumption, dietary celery intake, plastic bags for meat food storage, and sedentary hours were linked to male sperm motility, indicating that changing these lifestyles may improve it.

Conductive Porous MXene for Bionic,Wearable,and Precise Gesture Motion Sensors

Reliable,wide range,and highly sensitive joint movement monitoring is essential for training activities,human behavior analysis,and human-machine interfaces.Yet,most current motion sensors work on the nano/microcracks induced by the tensile deformation on the convex surface of joints during joint movements,which cannot satisfy requirements of ultrawide detectable angle range,high angle sensitivity,conformability,and consistence under cyclic movements.In nature,scorpions sense small vibrations by allowing for compression strain conversion from external mechanical vibrations through crack-shaped slit sensilla.Here,we demonstrated that ultraconformal sensors based on controlled slit structures,inspired by the geometry of a scorpion’s slit sensilla,exhibit high sensitivity(0.45%deg^(-1)),ultralow angle detection threshold(~15°),fast response/relaxation times(115/72 ms),wide range(15°~120°),and durability(over 1000 cycles).Also,a user-friendly,hybrid sign language system has been developed to realize Chinese and American sign language recognition and feedback through video and speech broadcasts,making these conformal motion sensors promising candidates for joint movement monitoring in wearable electronics and robotics technology.