应用网格走时的射线路径计算方法

子射线法（Raylet method）基于走时场的互易性,可用于多路径射线的计算。针对子射线法在拾取总走时（源点到给定点走时与接收点到给定点走时之和）场极值中存在的困难与稳定性问题,提出利用反插值求取总走时场中走时横向或纵向一阶导数为零的点来构成射线路径。此外,结合多级次计算策略,利用上述算法得到了全部的续至射线。在均匀介质和垂向梯度介质中,通过与解析结果的数值对比,发现计算网格尺度与导数算子长度对上述算法的精度有一定影响;在横向变速介质中,数值试验表明该算法相对于常规运动学射线追踪只有很小的计算偏差,其对横向变速具有很强的适应能力。低速体模型和Marmousi模型试算结果表明,本文算法对复杂模型具有令人满意的计算精度和计算效率。     

Performance and emission characteristics of diesel engine operated on plastic pyrolysis oil with exhaust gas recirculation

The objective of this research was to study the performance and emission characteristics of using waste plastic pyrolysis oil in diesel engine without any engine modification. The engine used in this study is a four-stroke single-cylinder naturally aspirated diesel engine (compression ignition). In the present work, the engine fuelled with blends of diesel fuel (DF) with plastic oil in the ratio of 90:10 (blend10%), 80:20 (blend20%), 70:30 (blend30%), and 50:50 (blend50%) are experimentally measured the efficiencies and emissions, analysed the performance, and compared results with that of DF.     

Investigation of Bubble Behavior in Subcooled Flow Boiling of Water in a Horizontal Annulus Using High-Speed Flow Visualization

Experiments have been carried out to study bubble behavior in subcooled flow boiling of water in a horizontal annulus at mass fluxes from 400 to 1200 kg/m²-s, heat fluxes from 0.1 to 1 MW/m², and pressures varying from 1 to 4 bar using high-speed visualization methods. National Instruments Labview IMAQ Vision Builder automated image-processing software was used to analyze the images obtained by high-speed visualization to obtain bubble size and bubble density. The parametric effects of pressure, mass flux, and heat flux on bubble behavior have also been brought out. Experimental results were validated by comparing with the predicted bubble sizes by using the Zeitoun and Shoukri (1996) correlation and were found to be in good agreement. It was found that bubble behavior is significantly affected by mass flux of working fluid and applied heat flux, whereas pressure of working fluid influences the bubble formation process indirectly.     

Characterization of friction surfaced martensitic stainless steel (AISI 410) coatings

Friction surfacing is a candidate process for depositing corrosion and wear resistant coatings. Being a solid-state process, it offers several advantages over conventional fusion welding based surfacing process. In the current work, martensitic stainless steel AISI 410 was friction surfaced over mild steel substrates. Coating microstructures were characterized using light microscopy, scanning electron microscopy and Xray diffraction. Coatings in as-deposited condition exhibited a fully martensitic microstructure and were found to be quite hard (with an average hardness of 460 HV). Bend and shear tests indicated excellent coating/substrate bonding. Overall, the current work shows that martensitic stainless steel AISI 410 can be satisfactorily friction surfaced on mild steel.     

Effect of methanol gasoline blended fuels on the performance and emissions of SI engine

This article presents experimental results of the effect of methanol gasoline blends as alternate fuels for the spark ignition (SI) engine. As the cost of the gasoline is periodically increasing the quest for the alternative fuels are evolved with which the emissions are reduced along with improved engine performance. A set of experiments have been conducted to investigate the effect of gasoline methanol blends in methanol percentages of M5, M10 and M15 on the engine performance and emissions. A significant reduction in emissions is observed with methanol blends compared to the standard gasoline with improved engine performance and emission characteristics. The fuels blends ranging from M10 to M15 have been found suitable for reduced emissions and improved engine performance.     

Structure, dielectric, ferroelectric, and energy density properties of (1 − x)BZT–xBCT ceramic capacitors for energy storage applications

We investigate the dielectric, ferroelectric, and energy density properties of Pb-free (1 ? x)BZT–xBCT ceramic capacitors at higher sintering temperature (1600 °C). A significant increase in the dielectric constant, with relatively low loss was observed for the investigated {Ba(Zr_0.2Ti_0.8)O₃}_(1?x ){(Ba_0.7Ca_0.3)TiO₃} _x (x = 0.10, 0.15, 0.20) ceramics; however, electric breakdown was low (~140, 170, 134 kV/cm), and of which room temperature (300 K) charging curve energy density values are largest ~0.88, 0.94, and 0.87 J/cm³ with maximum high dielectric constant values ~7800, 8400, and 5200, respectively. Bulk ceramic BZT–BCT materials have shown interesting energy densities with good energy storage efficiency (~72 %) at high sintering temperature; they might be one of the strong candidates for high energy density capacitor applications in an environmentally protective atmosphere.     

A quaternary lead based perovskite structured materials with diffuse phase transition behavior

A lead based quaternary compound composed of 0.25(PbZr_0.52Ti_0.48O₃) + 0.25(PbFe_0.5Ta_0.5O₃) + 0.25 (PbF_0.67W_0.33O₃) + 0.25(PbFe_0.5Nb_0.5O₃) - (PZT-PFT-PFW-PFN) was synthesized by conventional solid-state reaction techniques. It showed moderate high dielectric constant, low dielectric loss, and two diffuse phase transitions, one below the room temperature ∼261 K and other above ∼410 K. X-ray diffraction (XRD) patterns revealed a tetragonal crystal structure at room temperature where as scanning electron micrograph (SEM) indicates inhomogeneous surface with an average grain size of 500 nm-3 μm. Well saturated ferroelectric hysteresis loops with good saturation polarization (spontaneous polarization, P_s ∼ 30.68 μC/cm²) were observed. Temperature-dependent ac conductivity displayed low conductivity with kink in spectra near the phase transition. In continuing search for developing new ferroelectric materials, in the present study we report stoichiometric compositions of complex perovskite ceramic materials: (PZT-PFT-PFW-PFN) with diffuse phase transition behavior. The crystal structure, dielectric properties, and ferroelectric properties were characterized by XRD, SEM, dielectric spectroscopy, and polarization. 1/? versus (T) plots revealed diffuse relaxor phase transition (DPT) behavior. The compositional variation on the phase transition temperature, dielectric constant, and ferroelectric to paraelectric phase transitions are discussed.     

空气自动监测站的运行维护与远程故障诊断

通过对空气自动监测中SO2、NOx和PM10分析仪日常运行中的维护、保养及远程故障诊断方法的深入剖析,以期使用者能更好地掌握和使用各监测仪器,使监测仪器能在最佳性能状态下运行,保证监测数据的可靠性、准确性和及时性。     

蓝牙服务搜索协议的实现

为简洁高效地实现蓝牙服务搜索协议,给出了它的实现方法,包括数据元报头的位模实现,服务记录表的构建以及搜索过程的方法。实验结果表明,这些方法不但可以与商用手机实现互相搜索的功能,而且简单,可靠性强,具有较高的应用价值。