LED 一般是恒流操作的，如何改变 LED 的亮度呢？答案就是 PWM 控制。在一定的
频率的方波中，调整高电平和低电平的占空比，即可实现。比如我们用低电平点亮一个 LED
灯，我们假设把一个频率周期分为 10 个时间等份，如果方波中的高低电平占空比是 9：1，
这是就是一个比较暗的亮度，如果方波中高低电平占空比是 10：0，这时 ...
Lithium–sulfur (Li–S) batteries with high energy density and long cycle life are considered to be one of the most promising next-generation energy-storage systems beyond routine lithium-ion batteries. Various approaches have been proposed to break down technical barriers in Li–S battery systems. ...
Abstract—In the future communication applications, users
may obtain their messages that have different importance levels
distributively from several available sources, such as distributed
storage or even devices belonging to other users. This
scenario is the best modeled by the multilevel diversity ...
In recent years, cellular voice networks have transformed into powerful packet-switched
access networks for both voice communication and Internet access. Evolving Universal
Mobile Telecommunication System (UMTS) networks and first Long Term Evolution
(LTE) installations now deliver bandwidths of sev ...
Today’s wireless services have come a long way since the roll out of the
conventional voice-centric cellular systems. The demand for wireless access
in voice and high rate data multi-media applications has been increasing.
New generation wireless communication systems are aimed at accommodating
thi ...
Cooperation is not a natural characteristic attributed to humans. The typical human horizon is focused
on short-term gains, which might be due to our instinct-driven subconscious occupying a grander
importance than we dare to admit [1]. Cooperating with other individuals or entities, however, usuall ...
It is commonly accepted today that optical fiber communications have revolutionized
telecommunications. Indeed, dramatic changes have been induced in the way we interact
with our relatives, friends, and colleagues: we retrieve information, we entertain and
educate ourselves, we buy and sell, we orga ...
Cellular communications is one of the fastest growing and most challenging telecom-
munication applications ever. Today, it represents a large and continuously increasing
percentage of all new telephone subscribers around the world. In the long term,
cellular digital technology may become the univer ...
The motivation to write about the History of Wireless comes from Auguste
Comte (1798-1857), a French philosopher who is termed the father of positivism
and modem sociology [Les Maximes d'Auguste Comte (Auguste Comte's
Mottos), http://www.membres.lycos. ...
