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991.
CST可控驱动装置可对胶带输送机进行优化控制 ,且有较强的组网能力。还可与胶带机控制系统配套使用 ,改善胶带机的技术性能 ,延长了胶带机的使用寿命。 相似文献
992.
993.
994.
龙年春节前后,全国各地乃至世界各地的酷冷空前,人们不禁感到困惑,不是说地球一直在变暖吗?此前,中国科学家崔伟宏、美国科学家S.弗雷德·辛格等人也强烈反对"全球变暖"的观点,认为自然是气候变化的主要驱动因素。2007年,联合国气候变化政府间专门委员会(IPCC)提出:"人类将会经历全球 相似文献
995.
为了保证管理软件在整个生命周期内都具有可信性,在ICEMDA架构基础上融入可信性理论与方
法,提出了一种可信管理软件的模型驱动构造参考方法.通过分析国内外的研究现状,明确界定了管理软件
可信性概念,给出可信性判定问题描述.结果表明该方法以ICEMDA各层次上的构造体为中心,逐层进行可
信模型描述、可信指标度量、可信性判定与优化,借助ICEMDA的模型语义保持技术实现各层间可信性的保
持与传递,并以业务构件PSM模型的可信性判定为例简要介绍了该体系的具体实施机制 相似文献
996.
为拓宽开关电源产品的电压范围,提出了1种基于恒流驱动模式的能在10~80V宽电压范围工作的串联型开关稳压电源.该开关电源采用恒流方式驱动开关管,开关管在宽电压范围内始终能够得到理想的驱动电流.实验表明,该开关电源效率高、工作稳定、成本低,因此,可使用于工业用各种报警器产品和爆闪式信号灯中. 相似文献
997.
The quality of the micro-mechanical machining outcome depends significantly on the tracking performance of the miniaturized
linear motor drive precision stage. The tracking behavior of a direct drive design is prone to uncertainties such as model
parameter variations and disturbances. Robust optimal tracking controller design for this kind of precision stages with mass
and damping ratio uncertainties was researched. The mass and damping ratio uncertainties were modeled as the structured parametric
uncertainty model. An identification method for obtaining the parametric uncertainties was developed by using unbiased least
square technique. The instantaneous frequency bandwidth of the external disturbance signals was analyzed by using short time
Fourier transform technique. A two loop tracking control strategy that combines the μ-synthesis and the disturbance observer
(DOB) techniques was proposed. The μ-synthesis technique was used to design robust optimal controllers based on structured
uncertainty models. By complementing the μ controller, the DOB was applied to further improving the disturbance rejection
performance. To evaluate the positioning performance of the proposed control strategy, the comparative experiments were conducted
on a prototype micro milling machine among four control schemes: the proposed two-loop tracking control, the single loop μ
control, the PID control and the PID with DOB control. The disturbance rejection performances, the root mean square (RMS)
tracking errors and the performance robustness of different control schemes were studied. The results reveal that the proposed
control scheme has the best positioning performance. It reduces the maximal errors caused by disturbance forces such as friction
force by 60% and the RMS errors by 63.4% compared with the PID control. Compared to PID with DOB control, it reduces the RMS
errors by 29.6%. 相似文献
998.
A new dimmer using a mental-oxide-semiconductor field-effect transistor (MOSFET) for alternating-current (AC) directly driven
light-emitting-diode (LED) lamp was presented. The control method of proposed dimmer is pulse width control (PWM) method.
Compared with the conventional phase-controlled dimmer, the proposed PWM dimmer can produce sine wave and did not cause harmonics
problem. Furthermore, the proposed control method did not amplify the light flicker due to the independence of input voltage.
Therefore, the PWM dimmer can be used as the dimmer of the AC LED lamp instead of the conventional phase-controlled dimmer.
The experimental result shows that the proposed PWM dimmer has good performances. 相似文献
999.
Traffic flow prediction is an important component for real-time traffic-adaptive signal control in urban arterial networks.
By exploring available detector and signal controller information from neighboring intersections, a dynamic data-driven flow
prediction model was developed. The model consists of two prediction components based on the signal states (red or green)
for each movement at an upstream intersection. The characteristics of each signal state were carefully examined and the corresponding
travel time from the upstream intersection to the approach in question at the downstream intersection was predicted. With
an online turning proportion estimation method, along with the predicted travel times, the anticipated vehicle arrivals can
be forecasted at the downstream intersection. The model performance was tested at a set of two signalized intersections located
in the city of Gainesville, Florida, USA, using the CORSIM microscopic simulation package. Analysis results show that the
model agrees well with empirical arrival data measured at 10 s intervals within an acceptable range of 10%–20%, and show a
normal distribution. It is reasonably believed that the model has potential applicability for use in truly proactive real-time
traffic adaptive signal control systems. 相似文献
1000.
The direct current-direct current (DC-DC) converter is designed for 1 T static random access memory (SRAM) used in display
driver integrated circuits (ICs), which consists of positive word-line voltage (V
PWL), negative word-line voltage (V
NWL) and half-V
DD voltage (V
HDD) generator. To generate a process voltage temperature (PVT)-insensitive V
PWL and V
NWL, a set of circuits were proposed to generate reference voltages using bandgap reference current generators for respective
voltage level detectors. Also, a V
PWL regulator and a V
NWL charge pump were proposed for a small-area and low-power design. The proposed V
PWL regulator can provide a large driving current with a small area since it regulates an input voltage (VCI) from 2.5 to 3.3
V. The V
NWL charge pump can be implemented as a high-efficiency circuit with a small area and low power since it can transfer pumped
charges to V
NWL node entirely. The DC-DC converter for 1 T SRAM were designed with 0.11 μm mixed signal process and operated well with satisfactory
measurement results. 相似文献