如果你经常用U盘、移动硬盘拷贝数据，就会发现在传输大文件或给平板手机充电时，除了设备之外，线材本身也 容易发热，但同样是传输数据的网线通常摸起来却是凉凉的，这是为什么呢？ 兼具供电功能，是 USB 发热的关键 最关键的一点，就是 USB 接口和线材的核心设计是同时为设备提供电力和数据传输，这意味着同一个接口和线缆 既要传输数据信号，又要输送较大的电流，尤其是给设备充电时，考虑到现在的快充、闪充横行，按照 USB PD 3.1 规范，充电电流可达 5A，而根据焦耳定律，当较大的电流流 经导线电阻时，会产生显著的热量。 即便是PoE 供电的网线，电流也最多不过 1.73A 转自：电脑报 而且差分信号有着低电压摆幅的优势，不需要很高的绝对电压就能工作，差分信号之间的电压差只有 ±1V 左右， 也正因为电压摆幅低且差分接收灵敏度高，驱动这些信号所需的电流非常小，通常只有几毫安到十几毫安，这种 极小的电流也意味着产生的热量极低。 USB 快充的 5A大流就是导致高发热量 当然，也不是所有的网络数据传输方式都没有发热，比如PoE（PowerOverEthernet），翻译过来就是以太网供电， 像是IP电话、IP摄像头等互 ...

Core Viewpoint - The story of a Shenzhen Huaqiangbei merchant, A Teng, reflects the challenges faced by millions of merchants in the area, highlighting a battle for survival and rebirth in a competitive market [3]. Group 1: Profit Decline and Market Changes - A Teng's profit margin has plummeted from 20% to around 5%, with a significant reduction in shipment volume [5][4]. - The increasing transparency of prices has led to rapid product obsolescence, requiring constant updates to offerings [5]. - Customers have become more knowledgeable, often dictating product specifications based on their own research [5]. Group 2: Strategies for Recovery - A Teng aims to regain control by actively seeking customers through trade shows, which provide direct access to end clients and better conversion rates [8]. - The shift from being perceived as a trader to a manufacturer is crucial, allowing for price and brand optimization [9]. - A Teng emphasizes the importance of service quality, ensuring timely delivery and product guarantees to retain large-volume clients [9]. Group 3: Upcoming Events and Opportunities - The first "Good Life Expo" will be held from June 27 to 29 in Beijing, aimed at stimulating consumer activity and supporting quality brand growth [11]. - The expo will feature a unique online-offline integration model, connecting quality product/service companies with domestic distribution channels [11].