自由立体显示中的实景立体影像获取方法

获取适当位差的立体影像是自由立体显示系统的重要环节.针对该问题,提出了无导轨实景拍摄立体影像的过程和方法.分析并计算了立体包容范围与相机间距的关系,建立了立体场景包容范围模型.在测量自制各尺寸显示器的水平视差极限后,给出了最佳拍摄间距,为立体实景拍摄和制作提供了理论依据.     

Shannon限、时频不确定性和LDPC码

从信号分析和信息处理的观点论述了Shannon限所包含的实际物理意义,指出了时频不确定性对信号在信道传输中的限制,将信源和信宿、收端和发端、编码与解码接合起来,分析了LDPC码的主要性能。     

Chemistry of electron doped Ln2−xCexCuO4 superconductors

The electron doped Ln_2−xCe_xCuO₄ (Ln=lanthanide) oxides have intergrowth structures consisting of superconductively active CuO₂ sheets alternating with inactive (Ln, Ce)₂O₂ fluorite layers along the c-axis. Stabilization of such intergrowth structures requires bond length matching across the intergrowth interface. The bond length matching criterion causes a monotonic decrease in the Ce solubility limit from x=0.24 to x=0.15 as the size of Ln³⁺ decreased from Ln=La_0.5Nd_0.5 to Ln=Gd. Annealing in N₂ atm of Ln_2−xCe_xCuO₄ at temperatures above 900°C creates oxygen vacancies and the number of vacancies decreases with increasing Ce content. The value of x at which a semiconductor to superconductor transition occurs in Ln_2−xCe_xCuO₄ increases with decreasing size of Ln³⁺ due to an increasing Madelung energy caused by a decreasing Cu−O bond length.     

稠油油藏CO_2吞吐合理吞吐轮次

冀东油田高浅北区稠油油藏高含水油井自2010年底实施CO_2吞吐控水增油以来,取得良好效果。但首轮吞吐失效后,面临吞吐增油量逐轮减少、换油率下降、吨油成本不断上升的问题。为了有效提高吞吐措施效果,在明确CO_2吞吐控水增油机理和主要注采参数优化的基础上,以高浅北区某典型底水稠油油藏为例,考虑不同构造位置、水平井轨迹差异及不同采出程度,进行CO_2吞吐合理吞吐轮次数值模拟研究。研究表明:多轮吞吐效果主要受构造位置、井轨迹及含油饱和度的影响,高部位物性好的油井实施5轮次吞吐效果较好;腰部采出程度相对较低的油井可实施4轮吞吐;采出程度相对较高的油井、边部中部位油井可实施3轮次吞吐。矿场实践证实,该方法可减少无效措施工作量,实现多轮吞吐经济效益最优化。     

The effects of oxygenation aeration treatment on dissipation behaviors of tricaine mesylate in carp (Cyprinus carpio) muscle and water

Tricaine mesylate (MS-222) is one of the most used anesthetics in fish. It can be absorbed by the human body via food consumption, with related detriments to human health. In this study, a modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) method was developed for the determination of MS-222 in carp muscle and water samples using liquid chromatography-tandem mass spectrometry (LC-MS/MS). For cleanup procedure, multiplug filtration cleanup (m-PFC) method with n-Hexane delipidation was adopted. The extraction solvent, cleanup methods and sorbents were optimized. All method validation parameters were in the acceptable range. The dissipation behavior study was followed by the method development. Firstly, the anesthesia dose and time were optimized in application study. Secondly, carps were revived for different period of time with (experimental group) and without (control group) the oxygenation aeration treatment to compare the dissipation rate of MS-222. After being anesthetized for 6 h at 50 mg/L and 12 h of elimination, the concentrations of MS-222 in crap muscle and water of experimental group was lower than those of control group. After 36 h of elimination under oxygenation aeration, over 90% of MS-222 was dissipated in carp muscle. The results showed that the half-life of MS-222 in carp muscle was 6.2 h. The findings suggested that the commonly-used oxygenation aeration treatment in aquaculture production had potential effects in accelerating the dissipation of MS-222 in carp and water. In this study, three days of withdrawal period was recommended in carps after MS-222 administration under oxygenation aeration.     

Multi-walled carbon nanotubes-based magnetic solid-phase extraction for the determination of zearalenone and its derivatives in maize by ultra-high performance liquid chromatography-tandem mass spectrometry

A simple and rapid magnetic solid-phase extraction (M-SPE) procedure using multi-walled carbon nanotube-magnetic nanoparticles (MWCNT-MNPs) as sorbents was established for purification of zearalenone (ZEA), α-zearalenol (α-ZOL), β-zearalenol (β-ZOL), zearalanone (ZAN), α-zearalanol (α-ZAL) and β-zearalanol (β-ZAL) in maize. The main parameters affecting the clean-up efficiency were thoroughly investigated, and high purification efficiencies for all analytes were obtained. The resulting MWCNT-MNP-ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was validated for maize samples. The matrix effects were greatly minimized using the M-SPE approach, with signal suppression/enhancement values decreased from 69.9–127.6% to 92.1–103.8%. Consequently, complex matrix-matched calibration curves were not necessary and the calibrations constructed in acetonitrile could be applied for accurate quantification of the targeted mycotoxins in real samples. The average recoveries ranged from 75.8 to 104.1% and the inter- and intra-day precision values expressed as RSDs, were all lower than 14%. Limits of detection and quantification were in the range of 0.03–0.04 and 0.07–0.10 μg/kg, respectively. The analytical performance of the developed method was also successfully evaluated with maize samples, and this method was proved to be a powerful tool for monitoring ZEA and its derivatives in maize.     

Southern spanish windmills: Technological aspects

This paper shows the study carried out in a doctoral thesis about windmills in south-east Spain, in the area of Campo de Níjar in the province of Almeria. It intends to pay homage to Spanish windmills as a way of commemorating the fourth centenary of the masterwork of Spanish Literature, ‘Don Quixote’ in which the silhouette of the windmill is a pervading symbol.Wheat milling has been an important factor in the socio-economic development of rural Spain for centuries. The type of mill used depended on the energy resources available, wind or water. In the Campo de Níjar (Almeria, Andalusia, Spain), wind is the principal energy source, and therefore, windmills were widely used, as in other areas of Spain. In this paper, we study the technological conditions of these old windmills, we carry out a wind evaluation of the area, and we calculate the power and momentum of these windmills with a discussion of the results found.     

评定飞航导弹单发命中概率的方法研究

通过对抽样检验方法的研究,确立了区间估计的下限公式,用来在已知样本值的情况下确定导弹单发命中概率出现在该区间内的置信水平和精确度。     

边坡锚固工程分析中的水平条分法

对目前中国规范推荐用于边坡加固计算的垂直条分传递系数法进行研究,发现将该方法用于边坡锚固受力分析时,不仅存在垂直条块与加固结构体（锚杆和锚索）相互交叉,而且计算得出的锚固力与加固体的实际锚固力存在偏差等缺陷。在相关资料提出的、用于加筋土稳定性分析的水平条分法基础上,结合边坡锚固工程的特点,将该水平条分法做进一步拓展,使其能适用于锚杆和锚索等边坡锚固工程的稳定性计算,并通过工程实例对拓展后的水平条分法进行了验证。     

Equivalent linear limit states

The replacement of any limit state function by an equivalent linear function is discussed in detail and it is shown that there are several methods by which such an equivalence may be established. In the case of multiple failure mode problems the definition of fully equivalent linear functions requires the additional consideration of mode correlations. The manner in which this may be carried out is discussed and it is shown that, for most practical cases, a relatively simple analysis is likely to be sufficient to define the set of equivalent linear limit states, with the advantage that the established theory of such linear limit states may then be employed in the majority of reliability analyses.