GPS/SINS组合导航系统中卡尔曼滤波器的应用

在现代生活中,GPS/SINS组合导航系统得到了越来越多的应用.文中介绍了卡尔曼滤波器在处理多个导航系统传来的数据中的应用,并且能够自动校正系统,以达到更高精度的要求.     

活性碳纤维常温脱硫脱硝的实验研究

应用聚丙烯腈基活性碳纤维(PAN-ACF)与粘胶基活性碳纤维(Cellulose-ACF)进行脱除SO2实验研究,讨论ACF量、SO2浓度、O2浓度等因素的变化对脱硫效果的影响.结果表明,随着ACF量及O2浓度的增加,PAN-ACF脱除SO2的能力增强,而且PAN-ACF具有强于Cellulose-ACF的脱硫能力.对PAN-ACF进行脱硫脱硝相互影响的实验,探索了NO与SO2竞争吸附、相互影响的规律.     

A composite visible-light photocatalyst for hydrogen production

A composite photocatalyst, Pd–TiO_2−xN_x–WO₃, was synthesized by the template method and characterized by energy dispersive X-ray microanalysis (EDX), X-ray diffraction (XRD), UV–vis spectrometer, and scanning electron microscope (SEM). The results of EDX analysis reveals that the molecular formula of the composite photocatalyst can be expressed as Pd–TiO_1.72N_0.28–WO₃. The UV–vis absorption spectrum indicates that the absorption edge of the catalyst red-shifts to around 600 nm. Under the irradiation with ultraviolet and visible light, the catalyst showed good performance for photocatalytic hydrogen production with a Na₂S/Na₂SO₃ system as the sacrificial agent.     

One-step synthesis LiMn2O4 cathode by a hydrothermal method

Spinel LiMn₂O₄ powders have been successfully synthesized by a hydrothermal method directly, which is no any pretreatment and following treatment in the process. The structure and morphology of the powders were studied in detail by means of X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and thermogravimetric analysis (TGA). The data reveal that the products have well-defined stable spinel structure, and the particles show distinctive crystal faces with 50–300 nm in particle sizes. The electrochemical characteristics of the spinel materials are measured in the coin-type cells in a potential range of 3.2–4.35 V versus Li/Li⁺. The as-synthesized LiMn₂O₄ delivers reversible capacity of about 121 mAh g⁻¹ at a current density of 1/10 C. Cycled the cell to 40 cycles, the capacity remains at about 111 mAh g⁻¹ at 1/2 C.     

Shrinkage properties of a modified dental resin composites containing a novel spiro-orthocarbonate expanding monomer

ObjectivesThis study investigated the photopolymerization-induced shrinkage properties of conventional methacrylate-based composites modified by a novel spiro-orthocarbonate (SOC) expanding monomer.MethodsThe epoxy monomer and SOC expanding monomer were added to a methacrylate-based resin matrix at five different ratios ranging from 20 wt.% (SOC + Epoxy) (group 1) to 60 wt.% (SOC + Epoxy) (group 5). Volumetric shrinkage and contraction stress developing after polymerization were measured using X-ray micro-computed tomography and a universal testing machine, respectively.ResultsThe volumetric shrinkage of the resin composite samples ranged from 0.92% (group 5) to 3.85% (control group) 30 min after light curing. Group 5 had the lowest volumetric shrinkage (p < 0.05), followed by groups 4, 3, 2 and 1. The contraction stress of the materials ranged from 1.86 MPa (group 5) to 3.56 MPa (control group). The lowest contraction stress was also observed in group 5, 30 min after curing (p < 0.05).ConclusionIncluding SOC expanding monomer reduced volumetric shrinkage and contraction stress of composites in comparison with conventional methacrylate-based composites.     

Early warning for VHE gamma-ray flares with the ARGO-YBJ detector

Detecting and monitoring emissions from flaring gamma-ray sources in the very-high-energy (VHE, > 100 GeV) band is a very important topic in gamma-ray astronomy. The ARGO-YBJ detector is characterized by a high duty cycle and a wide field of view. Therefore, it is particularly capable of detecting flares from extragalactic objects. Based on fast reconstruction and analysis, real-time monitoring of 33 selected VHE extragalactic sources is implemented. Flares exceeding a specific threshold are reported timely, hence enabling the follow-up observation of these objects using more sensitive detectors, such as Cherenkov telescopes.     

Vibration analysis of orthotropic graphene sheets embedded in Pasternak elastic medium using nonlocal elasticity theory and differential quadrature method

In this paper, the small scale effect on the vibration analysis of orthotropic single layered graphene sheets embedded in elastic medium is studied. Elastic theory of the graphene sheets is reformulated using the nonlocal differential constitutive relations of Eringen. Both Winkler-type and Pasternak-type foundation models are employed to simulate the interaction between the graphene sheet and surrounding elastic medium. Using the principle of virtual work the governing differential equations are derived. Differential quadrature method is employed to solve the governing differential equations for various boundary conditions. Nonlocal theories are employed to bring out the small scale effect of the nonlocal parameter on the natural frequencies of the orthotropic graphene sheets embedded in elastic medium. Further, effects of (i) nonlocal parameter, (ii) size of the graphene sheets, (iii) stiffness of surrounding elastic medium and (iv) boundary conditions on non-dimensional vibration frequencies are investigated.     

Region based foreground segmentation combining color and depth sensors via logarithmic opinion pool decision

In this paper we present a novel foreground segmentation system that combines color and depth sensors information to perform a more complete Bayesian segmentation between foreground and background classes. The system shows a combination of spatial-color and spatial-depth region-based models for the foreground as well as color and depth pixel-wise models for the background in a Logarithmic Opinion Pool decision framework used to correctly combine the likelihoods of each model. A posterior enhancement step based on a trimap analysis is also proposed in order to correct the precision errors that the depth sensor introduces. The results presented in this paper show that our system is robust in front of color and depth camouflage problems between the foreground object and the background, and also improves the segmentation in the area of the objects’ contours by reducing the false positive detections that appear due to the lack of precision of the depth sensors.     

Effect of shock wave formation on propellant ignition in capillary discharge

In order to study the effect of shock wave formation on propellant ignition in capillary discharge, the shock wave formation process was analyzed using experimental and theoretical methods; the plasma jet temperature was measured, and closed bomb and 30 mm gun experiments were carried out. The results show that the first shock wave has a smaller value and larger range of influence, while the second shock wave has a larger value and smaller range of influence. A plasma jet can generate a shock wave at the nozzle according to the calculated plasma pressure and velocity, which is well confirmed by experiments and calculations. The plasma jet temperature is high during the formation of a shock wave and then decreases sharply. Plasma ignition can increase the burning rate of a propellant by about 30% by increasing the burning surface area of the propellant. Compared to conventional ignition, the average maximum chamber pressure and average muzzle velocity of plasma ignition are increased by 9.1 MPa and 29.3 m·s−1(∼3%), respectively, in a 30 mm gun. Plasma ignition has strong ignition ability and short ignition delay time due to the generation of a shock wave. By increasing the burning rate of the propellant, the muzzle velocity can be greatly improved when the maximum chamber pressure increases a little. The characteristics of the shock wave can be applied in the application of the capillary discharge plasma. For example, it can be applied in fusion, launching and combustion.     

Approximating feeder line reliability statistics with partial data collection in assembly systems

Due to the difficulty and high cost of data collection, many feeder lines in assembly systems lack full collection of data. However, reliability statistics of feeder lines are important in throughput analysis and continuous improvement of manufacturing systems. In this paper, a simple approximation approach is presented to estimate the reliability statistics of feeder lines from the associated assembly station's collected blocking and starving information. It is shown that the approach is helpful for accurate throughput estimation and sensitivity analysis. We also show how feeder line speed can be used to improve the approximation.