Preliminary discussion on the ignition mechanism of exploding foil initiators igniting boron potassium nitrate

Exploding foil initiator(EFI)is a kind of advanced device for initiating explosives,but its function is unstable when it comes to directly igniting pyrotechnics.To solve the problem,this research aims to reveal the ignition mechanism of EFIs directly igniting pyrotechnics.An oscilloscope,a photon Doppler velocimetry,and a plasma spectrum measurement system were employed to obtain information of electric characteristics,impact pressure,and plasma temperature.The results of the electric characteristics and the impact pressure were inconsistent with ignition results.The only thing that the ignition success tests had in common was that their plasma all had a relatively long period of high-temperature duration(HTD).It eventually concludes that the ignition mechanism in this research is the microconvection heat transfer rather than the shock initiation,which differs from that of exploding foil initiators detonating explosives.Furthermore,the methods for evaluating the ignition success of semiconductor bridge initiators are not entirely applicable to the tests mentioned in this paper.The HTD is the critical parameter for judging the ignition success,and it is influenced by two factors:the late time discharge and the energy of the electric explosion.The longer time of the late time discharge and the more energy of the electric explosion,the easier it is to expand the HTD,which improves the probability of the ignition success.

An Improved Distraction Behavior Detection Algorithm Based on YOLOv5

Distracted driving remains a primary factor in traffic accidents and poses a significant obstacle to advancing driver assistance technologies.Improving the accuracy of distracted driving can greatly reduce the occurrence of traffic accidents,thereby providing a guarantee for the safety of drivers.However,detecting distracted driving behaviors remains challenging in real-world scenarios with complex backgrounds,varying target scales,and different resolutions.Addressing the low detection accuracy of existing vehicle distraction detection algorithms and considering practical application scenarios,this paper proposes an improved vehicle distraction detection algorithm based on YOLOv5.The algorithm integrates Attention-based Intra-scale Feature Interaction(AIFI)into the backbone network,enabling it to focus on enhancing feature interactions within the same scale through the attention mechanism.By emphasizing important features,this approach improves detection accuracy,thereby enhancing performance in complex backgrounds.Additionally,a Triple Feature Encoding(TFE)module has been added to the neck network.This module utilizes multi-scale features,encoding and fusing them to create a more detailed and comprehensive feature representation,enhancing object detection and localization,and enabling the algorithm to fully understand the image.Finally,the shape-IoU(Intersection over Union)loss function is adopted to replace the original IoU for more precise bounding box regression.Comparative evaluation of the improved YOLOv5 distraction detection algorithm against the original YOLOv5 algorithm shows an average accuracy improvement of 1.8%,indicating significant advantages in solving distracted driving problems.

拉伸速率对β-iPP薄膜微观结构和力学性能的影响

通过熔体挤出-拉伸法制备了一系列稀土类β成核剂改性等规聚丙烯(iPP)薄膜。考察了拉伸速率对β-iPP薄膜微观结构和力学性能的影响。结果表明,所有β-iPP薄膜中α晶和β晶均发生支化现象,并且β晶支化随着拉伸速率的增加而受到抑制,而α晶支化没有发生明显变化;β-iPP薄膜的分子链和片晶的取向度随着拉伸速率增加而增大,而β晶含量及其结晶度呈现相反的趋势。另外,拉伸测试结果表明,当拉伸速率为30cm/min,β-iPP薄膜的拉伸强度和韧性达到最大值。

Highly stretchable kirigami-patterned nanofiber-based nanogenerators for harvesting human motion energy to power wearable electronics

Wearable electronics are advancing towards miniaturization and flexibility.However,traditional energy supply methods have largely hindered their development.An effective solution to this problem is to convert human mechanical energy into electricity to power wearable electronic devices.Therefore,it is greatly attractive to design flexible,foldable and even stretchable energy harvesting devices.Herein,we use the electrospinning and kirigami approach to develop a type of highly stretchable kirigami-patterned nanofiber-based triboelectric nanogenerator(K-TENG).Due to its innovative structural design,the K-TENG can achieve a tensile strain of 220%,independent of the tensile properties of the material itself.When a person swings their arms,the K-TENG fixed to the clothing can convert mechanical energy from human movement into electrical energy.The produced electricity can directly drive 50 LED lights and a digital watch,or be stored in a lithium battery to charge the smartwatch and smartphone,respectively.This study employs a new method to fabricate a stretchable triboelectric nanogenerator and demonstrates its promising applications in wearable power technology.

植物抗冻蛋白研究进展

温度是决定植物地理分布的主要环境因子之一,分布于高纬度、高海拔地区的寒地植物,在其生活史周期内通常会遭遇一段时期的零度以下低温。当环境温度降至冰点以下,植物体内水分子趋向于形成冰晶体,不断增大的冰晶对植物组织结构造成致命损伤。为适应冷冻环境,寒地植物病程相关蛋白(PR)及相关的WRKY转录因子进化成为能与冰面特异吸附结合、高效抑制冰晶形成和生长的抗冻蛋白(AFPs)。目前,已从冬黑麦(Secale cereale)等近百种植物中分离鉴定了AFPs。与昆虫AFPs相比,植物AFPs具有极高的重结晶抑制活性,可有效防止形成体内大冰晶。低温和病原菌均可诱导寒地植物合成AFP。有趣的是,仅冷诱导合成的AFPs有水解酶/抗冻活性双重分子功能。然而,越来越多的证据表明,PR-AFP仅具有水解酶/抗冻活性的其中一种,其转化由翻译后肽差异折叠控制/调节。AFP因具有独特的分子功能与广阔的应用前景而逐渐成为植物学领域的研究热点。该文对近年来相关领域取得的研究进展进行系统综述。

Scalable one-step wet-spinning of triboelectric fibers for large-area power and sensing textiles

Textile-based electronic devices have attracted increasing interest in recent years due to their wearability,breathability,comfort.Among them,textile-based triboelectric nanogenerators(T-TENGs)exhibit remarkable advantages in mechanical energy harvesting and self-powered sensing.However,there are still some key challenges to the development and application of triboelectric fibers(the basic unit of T-TENG).Scalable production and large-scale integration are still significant factors hindering its application.At the same time,there are some difficulties to overcome in the manufacturing process,such as achieving good stretchability and a quick production,overcoming incompatibility between conductive and triboelectric materials.In this study,triboelectric fibers are produced continuously by one-step coaxial wet spinning.They are only 0.18 mm in diameter and consist of liquid metal(LM)core and polyurethane(PU)sheath.Due to the good mechanical properties between them,there is no interface incompatibility of the triboelectric fibers.In addition,triboelectric fibers can be made into large areas of T-TENG by means of digital embroidery and plain weave.The T-TENGs can be used for energy harvesting and self-powered sensing.When they are fixed on the forearm can monitor various strokes in badminton.This work provides a promising strategy for the large-scale fabrication and large-area integration of triboelectric fibers,promotes the development of wearable T-TENGs.