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1.
诱导式卫星欺骗干扰可诱导航空器逐渐偏离预定航迹,难以被发现,因此及时有效地检测干扰是飞行安全的保障。在现有紧组合导航体制基础上,设计了一种基于误差估值累加开环校正的紧组合导航结构,并证明了其性能与传统闭环校正紧组合导航性能等效。在此结构中,将紧组合导航系统与自适应序贯概率比检测方法结合,提出了一种基于误差估值累加开环校正的诱导式欺骗检测方法,融合紧组合导航信息与其他不受欺骗影响的导航信息,构建欺骗检测统计量进行诱导式欺骗检测。仿真结果表明,开环校正结构可避免随时间累加的惯性导航系统误差所导致的组合导航滤波器发散问题,同时欺骗检测方法可进一步提高算法对“最坏”情形下微小诱导式欺骗的检测效果。  相似文献   
2.
针对高帧频、全局曝光和光谱平坦等成像应用需求,设计了一款高光谱成像用CMOS图像传感器。其光敏元采用PN型光电二极管,读出电路采用5T像素结构。采用列读出电路以及高速多通道模拟信号并行读出的设计方案来获得低像素固定图像噪声(FPN)和非均匀性抑制。芯片采用ASMC 0.35μm三层金属两层多晶硅标准CMOS工艺流片,为了抑制光电二极管的光谱干涉效应,后续进行了光谱平坦化VAE特殊工艺,并对器件的光电性能进行了测试评估。电路测试结果符合理论设计预期,成像效果良好,像素具备积分可调和全局快门功能,最终实现的像素规模为512×256,像元尺寸为30μm×30μm,最大满阱电子为400 ke^(-),FPN小于0.2%,动态范围为72 dB,帧频为450 f/s,相邻10 nm波段范围内量子效率相差小于10%,可满足高光谱成像系统对CMOS成像器件的要求。  相似文献   
3.
Many attempts have been made to improve mass transfer by reducing the size of reactors. However, such reduction will fairly quickly reach practical limitations and numerous difficulties still remain. Catalytic washcoat shape and properties may be critical design factors, but the mechanisms for their effects on mass transfer characteristics are still not fully understood. To effectively eliminate problems associated with mass transport phenomena in microstructured steam-methanol reformers, the effects of washcoat shape and properties were investigated in various situations by performing computational fluid dynamics simulations. The dependence of the solution on mass transfer characteristics was reduced to a small number of dimensionless parameters. A dimensionless mass transfer analysis was carried out in terms of the Sherwood, Schmidt, and pore Reynolds numbers. The results indicated that the rate of mass transfer is predominantly controlled by washcoat properties, and porosity and effective thermal conductivity are fundamentally important. The rate of the reforming reaction is typically controlled by kinetics at a temperature of 480 K and limited by mass transfer at a temperature of 580 K. The shape of washcoats affects the overall mass transfer characteristics, depending on the structural and thermal properties of washcoats. The shape effect is limited by heat transfer. A three-fold increase in effectiveness factor can be achieved by increasing the effective thermal conductivity of the washcoat. Design recommendations were finally made to improve transport characteristics for the systems.  相似文献   
4.
A consecutive competitive gas-liquid reaction is investigated using a Taylor bubble setup regarding the influence of fluid mixing in the bubble wake on yield and selectivity. The concentration fields behind a Taylor bubble are visualized and measured quantitatively with a novel time-resolved absorption imaging technique based on Beer Lamberts law and an integral selectivity is derived. In addition, the calculation of the local selectivity, often used in numerical approaches, is discussed and the existing experimental limits for its derivation are pointed out. Finally, an increase in selectivity of a competitive consecutive reaction for enhanced mixing is experimentally confirmed.  相似文献   
5.
Small interfering RNA (siRNA) can effectively silence target genes through Argonate 2 (Ago2)-induced RNA interference (RNAi). It is very important to control siRNA activity in both spatial and temporal modes. Among different masking strategies, photocaging can be used to regulate gene expression through light irradiation with spatiotemporal and dose-dependent resolution. Many different caging strategies and caging groups have been reported for light-activated siRNA gene silencing. Herein, we describe a novel caging strategy that increases the blocking effect of RISC complex formation/process through host/guest (including ligand/receptor) interactions, thereby enhancing the inhibition of caged siRNA activity until light activation. This strategy can be used as a general approach to design caged siRNAs for the photomodulation of gene silencing of exogenous and endogenous genes.  相似文献   
6.
Gene therapy research has advanced to clinical trials, but it is hampered by unstable nucleic acids packaged inside carriers and there is a lack of specificity towards targeted sites in the body. This study aims to address gene therapy limitations by encapsidating a plasmid synthesizing a short hairpin RNA (shRNA) that targets the anti-apoptotic Bcl-2 gene using truncated hepatitis B core antigen (tHBcAg) virus-like particle (VLP). A shRNA sequence targeting anti-apoptotic Bcl-2 was synthesized and cloned into the pSilencer 2.0-U6 vector. The recombinant plasmid, namely PshRNA, was encapsidated inside tHBcAg VLP and conjugated with folic acid (FA) to produce FA-tHBcAg-PshRNA VLP. Electron microscopy revealed that the FA-tHBcAg-PshRNA VLP has an icosahedral structure that is similar to the unmodified tHBcAg VLP. Delivery of FA-tHBcAg-PshRNA VLP into HeLa cells overexpressing the folate receptor significantly downregulated the expression of anti-apoptotic Bcl-2 at 48 and 72 h post-transfection. The 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay demonstrated that the cells’ viability was significantly reduced from 89.46% at 24 h to 64.52% and 60.63%, respectively, at 48 and 72 h post-transfection. As a conclusion, tHBcAg VLP can be used as a carrier for a receptor-mediated targeted delivery of a therapeutic plasmid encoding shRNA for gene silencing in cancer cells.  相似文献   
7.
This paper proposes a signal feedback interference topology to control the characteristics of a coupled line bandpass filter. Control is carried out by varying the ratio of the transmission line parameters of the forward and the feedback couplers. The topology produces a compact filter that does not require a complicated design or fabrication. The results of the insertion and return losses show that the feedback‐controlled design has desirable features in terms of the design frequency, fractional bandwidth, stopband rejection level, roll‐off rate and insertion loss. The test results of the fabricated prototype achieved good agreement with the simulation results of the ideal transmission line design model. Several microwave, modern wireless and mobile/satellite communication systems may benefit from such a filter design due to its compactness and flexibility.  相似文献   
8.
本文重点研究了自制深锥形干扰沉降分级机在不同影响因素下对细粒煤的分级效率,结果表明:底部和中部同时给水形式的设计有利于细粒煤分级,底部与中部给水量比值对分级效率有一定影响但不明显;给料速度及浓度值越低,细粒煤分级效率越高。该装置的适宜分级条件为流量配比2∶1、给料速度0.50m/s、矿浆浓度40%时,粒级级配(0.25~0.125mm和1.0~0.5mm)分级效率接近65%,较常规分级旋流器分级效率50%~60%提高约5%~15%,实验结果表明深锥形干扰沉降分级机可有效实现细粒煤的分级。  相似文献   
9.
针对日益严峻的食品安全问题,特别是食源性致病菌的快速检测,本文提出一种基于表面改性石墨烯粗锥型马赫-曾德尔干涉结构的光纤大肠杆菌传感器。首先,截取一根4 cm的实心光子晶体光纤,两端分别与两根单模光纤进行粗锥熔接,形成基于马赫-曾德尔干涉原理的传感结构;接着,制备一种表面改性石墨烯敏感材料,将它涂覆在实心光子晶体光纤的表面,使传感器对大肠杆菌溶液有较高的灵敏度;最后,将上述传感器置于水槽中,以此检测大肠杆菌溶液浓度。实验结果表明,在大肠杆菌溶液浓度为50~600 cfu/mL内,随着菌液的浓度增大,传感器的干涉光谱发生了明显的蓝移,灵敏度为3.43 pm/(cfu·mL^-1),菌液浓度与波长偏移的线性度为0.95649,检测限为67.18 cfu/mL,响应时间为15 s。该传感器成本低、体积小、响应时间快,适用于低浓度大肠杆菌浓度的快速检测。  相似文献   
10.
LTE室分高倒流直接影响室内4G用户的感知,同时较大程度拉低LTE网络驻留率指标。由于室内无线环境的封闭性,室分小区之间的覆盖独立性,仅仅通过参数调整的手段达到降低高倒流的效果非常不明显,因此本文针对目前影响室内用户感知的高倒流问题,从高倒流小区的标准出发,对室分高倒流小区的发现手段,产生原因及解决方案进行详尽地阐述,并针对各类型的高倒流情形提出解决方法,最终提供读者发现、分析及解决室分高倒流小区的有效方案,从而作为研究方法提供给LTE室内小区高倒流问题解决的指导意见  相似文献   
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