基于平行因子分解的大规模MIMO盲信道估计

针对单小区大规模多输入多输出（Multiple-Input Multiple-Output,MIMO）系统上行链路,提出了一种基于平行因子（Parallel Factor,PARAFAC）模型的信道估计方法。在基站端,将接收信号构造成PARAFAC模型,利用大规模MIMO系统中信道的渐近正交的性质,提出了一种基于约束二线性迭代最小二乘算法(Constrained Blinear Alternating Least Squares,CBALS),从而实现了盲信道估计。理论分析及仿真结果表明,所提方法与传统最小二乘方法相比,不仅提高了频带利用率而且具有更高的估计精度;与已有的二线性交替最小二乘方法(BALS)相比,所提算法有更快的收敛速度。     

Constructing Flexible Film Electrode with Porous Layered Structure by MXene/SWCNTs/PANI Ternary Composite for Efficient Low-Grade Thermal Energy Harvest

Thermal energy, constituting the majority of the energy lost through various inefficiencies, is abundant and ubiquitous. With thermogalvanic effect, thermocells (TECs) can directly convert thermal energy into electricity without producing vibration, noise or other waste emissions. This work presents a rational design of flexible film electrodes constructed on a ternary composite of Ti₃C₂T_x MXene (T_x represents surface terminations), polyaniline (PANI) and single-wall carbon nanotubes for TECs, which exhibit notably enhanced thermoelectrochemical performance compared to the widely adopted noble platinum electrodes. The ternary composite electrodes form a porous layered structure with a large electrochemical-active surface area. Experiment and simulation results reveal that synergistic effects of Ti₃C₂T_x and PANI are induced for promoting both mass and charge transport at the electrolyte-electrode interface, resulting in a TEC with an output power of 13.15 µW cm⁻² at the ΔT of 40 K. The TEC also shows a rapid response to the small temperature difference between the human body and the ambient, demonstrating high potential in harvesting low-grade heat to power small electronics.     

6.7 kW全国产化窄线宽三包层光纤激光器

为了实现高功率光纤激光的窄线宽输出,研究了基于大模场三包层掺镱光纤（LMA-YTF）高功率窄线宽光纤激光的热效应和四波混频(FWM)效应。基于FWM效应模型,仿真分析了大模场三包层光纤(LMA-TCF)放大器光谱展宽的影响因素。建立了LMA-YTF的热分布模型,分析了大模场三包层光纤(LMA-YTF)中第二包层功率占比对光纤温度以及泵浦功率上限的影响,讨论了聚合物涂层导热系数和外部温度对光纤温度的影响,实验对比了不同反向合束器的泵浦功率上限,结果表明第二包层功率占比低的(6+1)×1合束器比(9+1)×1合束器拥有更高的泵浦功率上限。基于全国产化器件搭建了一台三包层光纤激光器,实现了输出功率6.7 kW、3 dB线宽为0.32 nm的激光输出。     

A review: crystalline silicon membranes over sealed cavities for pressure sensors by using silicon migration technology

A silicon pressure sensor is one of the very first MEMS components appearing in the microsystem area.The market for the MEMS pressure sensor is rapidly growing due to consumer electronic applications in recent years.Requirements of the pressure sensors with low cost,low power consumption and high accuracy drive one to develop a novel technology.This paper first overviews the historical development of the absolute pressure sensor briefly.It then reviews the state of the art technology for fabricating crystalline silicon membranes over sealed cavities by using the silicon migration technology in detail.By using only one lithographic step,the membranes defined in lateral and vertical dimensions can be realized by the technology.Finally,applications of MEMS through using the silicon migration technology are summarized.     

基于人体热感觉的新型辐射板节能空调设计

本文提出了一种新型辐射板节能空调的设计方案.以AT89C52单片机为核心控制器,通过温度传感器和液晶显示屏对室内温度信息进行采集与显示,该空调设置4个能够描述当前感觉的调温档位("热"、"较热"、"冷""较冷"),可将信息反馈给单片机,进行温度调节,并在手机APP上进行显示.     

DNA‐Templated Biomimetic Enzyme Sheets on Carbon Nanotubes to Sensitively In Situ Detect Superoxide Anions Released from Cells

Superoxide anion (O₂^?) is implicated in a wide variety of biological phenomena and oxidative stress‐related diseases. The electrochemical detection of O₂^? is very attractive but relies on superoxide dismutase enzymes, thus suffering from high cost and low durability. The advances of nanoscience allows architecting while functionalizing a biomimetic sensing platform in nanoscales for high sensitivity and specificity. In this work, manganous phosphate (Mn₃(PO₄)₂) nanosheets, a biomimetic enzyme, are template‐synthesized with DNA and further assembled on carbon nanotubes (CNTs) to form unique DNA‐Mn₃(PO₄)₂‐CNT nanocomposite sheets, of which the Mn₃(PO₄)₂ sheets efficiently catalyze the dismutation of O₂^? while CNTs enable fast electron transfer, thus achieving highly sensitive and specific detection of O₂^? with long‐term stability. The biomimetic O₂^? sensor is further used to monitor O₂^?in situ released from mouse cancer cell and normal skin cell under drug stimulation, showing excellent real time quantitative detection capability. This work demonstrates a nanoscale approach to not only synthesize but also design a biomimetic enzyme for comparable performance with the natural enzyme‐based biosensor while rendering much higher durability than the natural one and thus holding a great promise for broad applications in fundamental research, clinic diagnostics and screening for drug therapy effects.     

基于结构一体化的压电尺蠖直线电机设计

为使装配与调节过程易于实现,基于结构一体化思想设计了压电尺蠖直线电机。首先,采用三角放大结构对箝位机构进行了设计,并采用柔性薄板和柔性折叠梁对驱动机构进行了设计,所设计电机的箝位机构与驱动机构被集成为一体,可降低对机体加工与装配的精度要求;其次,采用有限元法对电机的位移放大倍数、应力与模态进行了分析;最后对电机的静、动态特性分别进行了测试。结果表明,电机位移具有良好的线性,最大单步位移为8.24μm,电机的分辨率为10 nm,最大运动速度为0.17 mm/s。     

芜菁籽油的超临界CO2萃取及脂肪酸成分分析

采用超临界CO2萃取技术对芜菁籽油进行萃取,运用响应面法优化了工艺条件.结果表明超临界CO2萃取芜菁籽油的最佳工艺条件为:萃取压力31.65 MPa,萃取温度46.10℃,萃取时间80.40 min,在此条件下芜菁籽油得率为32.55%.芜菁籽油经气相色谱-质谱分析,饱和脂肪酸含量为7.70%,以棕榈酸(2.63%)为主;不饱和脂肪酸含量为88.35%,主要以芥酸(47.18%)、油酸(17.53%)和亚油酸(8.43%)为主.     

小蓬草乙醇提取物对葡聚糖硫酸钠诱导的溃疡性结肠炎小鼠的抗炎作用

探讨小蓬草乙醇提取物(CME)对葡聚糖硫酸钠(dextran sodium sulfate,DSS)诱导的溃疡性结肠炎小鼠的抗炎能力的影响.将小鼠随机分成正常组、模型组、低剂量和高剂量CME组.除正常组外,其余各组小鼠采用DSS诱导结肠炎小鼠模型,并对低剂量和高剂量CME组分别灌胃50和200 mg·kg-1 CME,...     

分散固相萃取—超高效液相色谱—四极杆/飞行时间质谱法测定禽肉中松香酸类物质

目的：建立超高效液相色谱—四极杆/飞行时间质谱法（UPLC-Q-TOF/MS）测定禽肉中松香酸类物质。方法：样品使用乙腈提取,盐析分层后,上清液由C₁₈固相萃取剂净化,UPLC-Q-TOF/MS电喷雾负离子模式测定。结果：3种松香酸类物质在10~500 μg/L质量浓度范围内线性关系良好,相关系数R²＞0.998,平均回收率为87.8%~98.5%,相对标准偏差（RSDs）为1.99%~6.71%（n=6）;方法检出限（LODs）为10 μg/kg,方法定量限（LOQs）为20 μg/kg。结论：试验方法操作简便,快捷,回收率和灵敏度高,精密度好,能够满足禽肉中3种松香酸类物质的检测需求。