基于LPC2132和DS18B20的单总线数字测温系统设计

本文介绍一种新型嵌入式数字测温系统,该系统采用美国DALLAS公司生产的单总线数字温度传感器DS18B20为核心测温元件,以ARM7(LPC2132)为微处理器,给出了该系统的电路硬件设计与软件实现方法,并针对它在智能家居控制系统应用中出现的与硬件和软件有关的问题给出了解决方法.该系统具有结构简单、测温准确等特点,可作为一种新型的数字测温系统.     

一种对用户公平的核心无状态队列管理算法

在对"流"公平的CSFQ(Core-Stateless Fair Queueing)算法基础上进行改进,将算法设计思想由对流速率的公平分配改为对表征用户需求的效用函数的公平分配,从而提出一种对用户公平的核心无状态队列管理算法(Core-Stateless User Fair Queueing,CSUFQ),该算法能近似实现边界及核心路由器上对用户需求的最大最小公平,仿真实验证明了其效果.     

Bandpass filter with an ultra-wide stopband designed on miniaturized coaxial resonators

Characteristics of a new miniaturized coaxial resonator are theoretically investigated. It is shown that the first resonant frequency of the resonator can be significantly lowered relative to the second one and the resonator dimensions can be considerably decreased as compared to those of a traditional dielectric-filled quarter-wavelength coaxial resonator. Based on the investigated resonator, a fourth-order bandpass filter has been designed and fabricated. The filter stopband at a level of no worse than ?90 dB extends to the frequency that exceeds the passband center frequency by a factor of 47. Calculated frequency responses are in good agreement with those measured on the fabricated filter prototypes.     

Model-Based Control of Active Tilting-Pad Bearings

A promising mechanical bearing candidate for an active operation is the tilting-pad bearing. The proposed active tilting-pad bearing has linear actuators that radially translate each pad/pivot pair. The use of feedback control in determining the actuator forces allows for the automatic, continuous adjustment of the pad position during the operation of the rotating machine. In this paper, we develop a nonlinear dynamic model of the active bearing system. The hydrodynamic force produced by the fluid film is modeled as a nonlinear, squeeze-film damper plus repellent spring. A model-based nonlinear controller is then designed to exponentially regulate the rotor position to the origin. A proof-of-concept experiment shows that the active strategy improves the bearing performance relative to its traditional passive operation. Further, the experiment demonstrates that the model-based nonlinear control regulates the rotor comparably to a linear proportional integral derivative (PID) control, but requires significantly less control energy.     

一款基于树莓派的便携式智能灭火器设计

设计了一款基于树莓派的便携式智能灭火器,该设计过程包括采用瓶体模块设计,存储模块设计,远程监测与报警模块设计.其中,瓶体外部采用ABS阻燃材质,内部采用一种用于气溶胶罐的铝合金铝合金;存储模块采用无压存储S型气溶胶的方式;远程监控系统中使用树莓派作为中央控制器,辅以各种传感器采集信息,然后通过外部方式远程传输数据,实现...     

SDCCH信道话务量评估及最佳配置

本比较详细地阐述了SDCCH信道话务量的计算方法及在GSM网络中的配置原则，以便使网络资源达到最佳配置，发挥最大的经济效益。在论述中提出了3种方法：(1)建立SDCCH信道话务模型的方法；(2)评估SDCCH信道话务量的计算方法；(3)选择SDCCH信道最佳配置的方法。这3种方法供大家参考。     

图像制导导弹落角约束的制导律设计

针对某些图像制导导弹限制终端攻击角的作战要求,提出一种落角约束最优导引律。该导引律形式简单,易于工程实现。仿真结果证明,能满足脱靶量小的要求,对于某些机动的目标,该制导律都能够以期望的终端攻击角度命中目标,对于目标的机动具有较好的鲁棒性。     

机场激光驱鸟器扫描系统设计及应用

介绍了机场激光驱鸟器扫描系统设计的基本内容,即系统原理、功能、特点、组成及各分系统设计;分析了系统的要求和使用条件,对直流电机选型进行计算及校核,验证了设计的正确性和可靠性。     

Understanding Boosted Selective CO2-to-CO Photoreduction with Pure Water Vapor over Hierarchical Biomass-Derived Carbon Matrix

Solar-driven CO₂ reduction reaction (CO₂RR) with water into carbon-neutral fuels is of great significance but remains challenging due to thermodynamic stability and kinetic inertness of CO₂. Biomass-derived nitrogen-doped carbon (N-C_b) have been considered as promising earth-abundant photocatalysts for CO₂RR, although their activities are not ideal and the reaction mechanism is still unclear. Herein, an efficient catalyst is developed for CO₂-to-CO conversion realized on diverse N-C_b materials with hierarchical pore structures. It is demonstrated that the CO₂-to-CO conversion preferentially takes place on positively charged carbon atoms next to pyridinic-N using two representatives treated pollens with the largest difference in pyridinic-N density and N content as model photocatalysts. Systematic experimental results indicate that surface local electric field originating from charge separation can be boosted by hierarchical pore structures, doped N, as well as pyridinic-N. Mechanistic studies reveal that positively charged carbon atoms next to pyridinic-N serve as active sites for CO₂RR, reduce the energy barrier on the formation of CO*, and facilitate the CO₂RR performance. All these benefits cooperatively contribute to treated chrysanthemum pollen catalyst exhibiting excellent CO formation rate of 203.2 µmol h⁻¹ g⁻¹ with 97.2% selectivity in pure water vapor. These results provide a new perspective into CO₂RR on N-C_b, which shall guide the design of nature-based photocatalysts for high-performance solar-fuel generation.     

Defect Engineering of MOF-Based Membrane for Gas Separation

Metal–organic frameworks (MOFs) are highly versatile materials that have been identified as promising candidates for membrane-based gas separation applications due to their uniformly narrow pore windows and virtually unlimited structural and chemical features. Defect engineering of MOFs has opened new opportunities for manipulating MOF structures, providing a simple yet efficient approach for enhancing membrane separation. However, the utilization of this strategy to tailor membrane microstructures and enhance separation performance is still in its infancy. Thus, this summary aims to provide a guideline for tailoring defective MOF-based membranes. Recent developments in defect engineering of MOF-based membranes will be discussed, including the synthesis strategies for defective MOFs, the effects of defects on the gas adsorption properties, gas transport mechanisms, and recently reported defective MOF-based membranes. Furthermore, the emerging challenges and future prospects will be outlined. Overall, defect engineering offers an exciting opportunity to improve the performance of MOF-based gas membranes. However, there is still a long way to go to fully understand the influence of defects on MOF properties and optimize the design of MOF-based membranes for specific gas separation applications. Nonetheless, continued research in this field holds great promise for the development of next-generation membrane-based gas separation technologies.