基于555定时器的半波加热电热毯开关的设计

目前市场上的大多数电热毯的加热方式都是全波加热,虽然可以通过档位控制加热温度,但在加热中需要手动换挡,使用较长时间后,会出现温度过高,影响睡眠质量的缺点.为了克服这一缺点,设计了基于555定时器的半波加热电热毯开关,这一开关的核心元件是以555定时器构成的多谐振荡器和半波镇流器.测试结果表明,这款开关不但有助于减少人们因温度不适需要调节而带来的麻烦,更有利于节约能源.     

一种新型粮食水分数字传感器的设计

论述了一种新型粮食水分数字传感器的工作方法及原理,给出了传感器系统的检测电路及单片机的处理思想和流程图,并分析了减小测量误差的具体办法.     

555集成电路在皮带机综合保护器上的应用

以555时基电路的工作原理为理论基础，尝试设计一种应用于井下皮带机综合保护的装置，对煤位、速度、断带、跑偏进行检测和控制，具有起动报警、故障报警和起动速度自保及保护闭锁功能。     

匀变速直线运动实验的微机计时法

在匀变速直线运动的实验中，利用可编程定时／计数器8254来记录运动小车过测点的时刻值，可使计时精度达到万分之一秒。该实验系统可取代传统的计时方法。     

使用8253/8254定时计数器测量脉冲量的软、硬件实现方法

8253／8254是通用可编程定时器／计数器，内含3个彼此独立的16位计数器．由于芯片本身的特性，使之在实际应用时会产生一些问题．在简单介绍了几种脉冲量测量方法后，指出了使用8253／8254测量脉冲量可能存在的问题并提出了解决方法，最后给出了Borland C 的具体程序实现方法、     

高性能共轨柴油机电控单元的开发研究

采用高性能的MPC555微控制器,运用模块化设计方法,设计了共轨柴油机电控单元(ECU)的硬件和底层软件.其中硬件模块包括:微处理器(MCU)、电源、输入输出等模块;软件模块包括:初始化、采样处理和输出处理等模块.用该系统在油泵试验台上做了压力控制、油量匹配试验,并在发动机台架上进行了柴油机喷油提前角和燃油压力MAP的匹配研究.试验结果表明,该系统取得了令人满意的控制效果.     

Temperature dependent crystallographic transformations in chalcedony, SiO2, assessed in mid infrared spectroscopy

Chalcedony consists of hydroxylated 50-100 nanometre measuring α-quartz (SiO(2)) crystallites that lose their surface silanole groups (Si-OH) upon heating between 350°C and 600°C. The loss of the chalcedony's ≈1% of silanole groups allows for the healing of water related defects in the crystallites. We investigated these crystallographic transformations using Fourier Transform mid Infrared Spectroscopy in direct transmission, Attenuated Total Reflection (ATR) and the reflectivity. We found that an absorption band that is specific for chalcedony at 555 cm(-1) disappears gradually upon heating between 350°C and 600°C. The reduction of the band is correlated to the loss of surface silanoles. This result leads to the assignment of the band to free Si-O vibrations in non bridging Si-OH groups that have a lower natural frequency than Si-O vibrations in bridging Si-O-Si. The recognition of a silanole signal in the mid infrared allows for an easy, cheap and rapid recognition of hydroxyl in chalcedony.     

具有定时与随机时间闸门机制的两队列轮循模型

In this paper, we consider two-queue polling model with a Timer and a Randomly- Timed Gated （RTG） mechanism. At queue Q1, we employ a Timer T^（1）： whenever the server polls queue Q1 and finds it empty, it activates a Timer. If a customer arrives before the Timer expires, a busy period starts in accordance with exhaustive service discipline. However, if the Timer is shorter than the interarrival time to queue Q1, the server does not wait any more and switches back to queue Q2. At queue Q2, we operate a RTG mechanism T^（2）, that is, whenever the server reenters queue Q2, an exponential time T^（2） is activated. If the server empties the queue before T^（2）, it immediately leaves for queue Q1. Otherwise, the server completes all the work accumulated up to time T^（2） and leaves. Under the assumption of Poisson arrivals, general service and switchover time distributions, we obtain probability generating function （PGF） of the queue lengths at polling instant and mean cycle length and Laplace Stieltjes transform （LST） of the workload.     

SAR雷达定时模块的设计

文中设计了一款定时模块,用于为SAR雷达提供定时信号。设计选用了AD公司ADSP21060芯片作为控制芯片,实现数据交流、工作方式切换以及指令传输以等。设计中采用了标准VME接口来保证与主机的通信,配有CPLD模块来实现对VME接口控制和定时信号的产生。本文主要从硬件方面详细叙述了设计思路与过程。     

The electronic Raman spectrum of cobalt doped MgO

The energies of the ⁴T_1g states of Co²⁺ as a dilute substitutional impurity in MgO relative to the ground Λ_6g doublet have been found by low temperature Raman spectroscopy to be two Λ_8g states at 305 ± 3 cm^?1 and 930 ± 3 cm^?1; the remaining Λ_7g energy is predicted to be in the 980–1010 cm^?1 range the corresponding Λ_6g → Λ_7g Raman transition being weak and buried in the extensive two-phonon background. A second-order perturbation calculation which couples the spin-orbit states to both E_g and T_2g modes of vibration gives a weak but important Jahn-Teller stabilization energy for the Λ_8g states.