应用分形理论和光线投射算法的卫星云图模拟技术

卫星云图模拟是气象卫星成像仿真所研究的核心问题,针对快速生成效果逼真的卫星云图的要求,以分形理论为基础,设计了一种基于随机中点位移算法的云体数据生成模型,并采用光线投射算法将产生的三维云体数据绘制于二维平面图像上,实现了卫星云图的模拟,得到了比较满意的结果.     

Water-soluble ABC triblock copolymers based on vinyl ethers: Synthesis by living cationic polymerization and solution characterization

Water-soluble ABC triblock copolymers of methyl vinyl ether (MVE), ethyl vinyl ether (EVE), and methyl tri(ethylene glycol) vinyl ether (MTEGVE) of various block sequences and carrying 20 monomer units in each block were synthesized by living cationic polymerization. In addition to the triblocks, one AB diblock, one BA diblock, and one statistical copolymer of MVE and MTEGVE carrying 20 units of each type of monomer were synthesized as controls. Moreover, three homopolymers each carrying 20 units of MVE and end groups of varying hydrophobicity were synthesized using three different initiators. The molecular weights and molecular weight distributions of all the polymers were determined by gel permeation chromatography (GPC) in tetrahydrofuran (THF). The number average degrees of polymerization (DP_ns) and composition of all the polymers were calculated by proton nuclear magnetic resonance (¹H-NMR) spectroscopy. The molecular weights and degrees of polymerization corresponded to the values expected from the monomer/initiator ratios. The calculated polydispersities were reasonably narrow at 1.3. Aqueous GPC studies at room temperature on the triblock copolymers showed that the polymers exist as isolated chains (unimers) in solution but they tend to assemble and form micelles in the presence of a sufficiently high salt concentration apparently due to the insolubility of the EVE units under the latter conditions. Triblocks with a different block sequence exhibited a different susceptibility to salt-induced micellization, as indicated by the retention volume of the micelles and the relative micelle/unimer peak areas. Similarly, the cloud points of the triblock copolymers covered a relatively wide temperature range from 56 to 72°C. These differences in micellization and cloud points suggest a profound effect of the location of the hydrophilic MTEGVE block on copolymer association. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1181–1195, 1997     

三维成像载荷地面快速融合处理方法研究

三维成像载荷是一种能够同时采集激光雷达数据以及CCD影像,并快速融合生成三维立体影像的新型载荷。在分析载荷工作原理的基础上,面向载荷的地面检校及成像试验,提出了一种针对该新型三维成像载荷的地面快速数据融合处理方法;并利用地面实测数据对方法进行了验证。结果表明,该方法能快速生成实验区的三维影像,同时也验证了该类型载荷对激光雷达数据与影像数据快速融合的能力。     

镁粉尘云最低着火温度及抑制技术的实验研究

为评价镁粉着火燃烧危险性及惰性粉体对镁粉着火燃烧的抑制作用,采用Godbert-Greenwald恒温炉装置研究了喷粉压力、浓度、粒径及惰性粉体Ca CO3、Si O2对镁粉尘云最低着火温度的影响。结果表明:喷粉压力为0.03 MPa时,最有利于镁粉着火燃烧;镁粉尘云的最低着火温度随浓度的增加而降低,存在最小危险浓度,5.45 kg/m3;高于此浓度,镁粉尘云的最低着火温度几乎不变;镁粉粒径减小,其最低着火温度降低;镁粉尘云最低着火温度随Ca CO3、Si O2含量的增加而先升高后趋于稳定;惰性粉体浓度低于52%时,Ca CO3的抑制效果强于Si O2;高于52%时,Si O2的抑制效果强于Ca CO3;当炉体温度高于630℃时,Ca CO3与Si O2对镁粉的抑制效果较弱。     

基于改进云物元的山东省城市生态安全评价及贡献度分析

基于压力(Pressure)-状态(State)-响应(Response)模型建立城市生态安全评价体系,提出一种改进的云物元模型,利用云模型的双重不确定性和物元可拓理论相结合定性定量分析,对山东省2009-2019年城市生态安全进行综合评价,并重点研究济南市生态安全及指标贡献度。结果表明：该模型所给出的生态安全指数既能描述生态安全状况,亦可对不同城市进行比较。济南市虽一直处于临界安全状态,但生态安全指数稳步上升,受生态系统压力和状态影响较大。山东省16个地级市生态安全状况存在明显差异,整体呈上升趋势,但总体处于临界安全级别,威海、青岛、济南处于排名前列,德州、枣庄、菏泽处于较不安全。建议山东省政府注意区域发展的不平衡性,制定相关政策方案来缩小各城市间的差距。     

自适应法向量约束的工件分割方法

针对目前对工件点云分割中出现的过分割、欠分割等问题,提出一种结合欧式聚类和自适应法向量约束的工件分割方法.首先对采集到的点云进行体素滤波,使用随机采样一致性(random sample consensus,RNASAC)算法滤除背景并通过统计滤波器去除噪点,接着利用欧式聚类算法将目标点云划分成点云簇,最后针对点云簇中含...     

基于用户价值和风险的云服务定价方法研究

用户价值和风险是影响云服务纵深化应用的重要因素,为解决这一障碍,最有效的措施是在云服务定价中考虑这些因素。在传统固定定价和按用量定价机制基础上构建混合定价模型,在以往文献探讨单一影响因素的基础上,研究用户价值与风险双重因素影响下的云服务定价策略。研究表明：云服务提供商应在用户价值较低的市场中提供固定定价机制,在用户价值较高的市场提供混合定价机制,混合定价机制比单一定价机制在市场占有率方面更有优势;伴随风险增大,用户更偏好按用量定价机制购买云服务;交易成本高低是按用量定价机制能否创造价值的关键,随着交易成本不断降低,混合定价机制下的云服务提供商利润和社会福利最优。     

The surface tension of aqueous poly(N-isopropylacrylamide-co-acrylamide)

A series of poly(N-isopropylacrylamide-co-acrylamide) copolymers with N-isopropylacrylamide (NIPAM) to acrylamide (AM) ratios varying from 95/05 to 10/90 was synthesized and surface tensions, cloud point temperatures, and enthalpies of phase separation were measured. At 25°C, 1 wt % poly(N-isopropylacrylamide) homopolymer has a surface tension of 41.8 mJ/m². Incorporation of AM moieties in the copolymer increased surface tension approaching the limiting value of 65.3 mJ/m² which was obtained for polyacrylamide solutions. The surface tension values of copolymer solutions were predicted from the surface tensions of the homopolymers applied to a one-parameter model analogous to the Margules model for the excess free energy of mixing. Heats of phase separation for the copolymer were less than expected compared with PNIPAM homopolymer. It was proposed that NIPAM moieties directly bonded to acrylamide did not contribute to the enthalpy of phase separation. Finally, surface tension lowering kinetics were slower above the cloud point temperatures because at high temperatures the copolymers were present as colloidally dispersed particles which had to diffuse to the air/water interface, unwrap, and spread to give an adsorbed monolayer. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2137–2143, 1999     

Preparation of micron-size polystyrene particles in supercritical carbon dioxide

The dispersion polymerization of styrene in supercritical CO₂ utilizing poly(1,1-dihydroperfluorooctyl acrylate) (p-FOA) as a polymeric stabilizer was investigated as well as poly(1,1-dihydroperfluorooctyl methacrylate) (p-FOMA). The resulting high yield (>85%) of spherical and relatively uniform polystyrene (PS) particles with micron-size range (2.9–9.6 µm) was formed for 40 h at 370 bar using various amounts of p-FOA and p-FOMA as a stabilizer with good stability until the end of the reaction. The particle diameter was shown to be dependent on the weight percent of added stabilizer. Previously, we reported that p-FOA was not effective for the dispersion polymerization of styrene as a stabilizer. Here, we find that p-FOA can indeed be an effective stabilizer for the dispersion polymerization of styrene in supercritical CO₂, but the pressure necessary to achieve good stability is higher than pressure used by us previously. This study suggests the possibility that fluorinated acrylic homopolymers are effective for the dispersion polymerization of various kinds of monomers as a stabilizer. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2429–2437, 1999     

制造云服务组合柔性的四维属性测度方法

云制造环境下服务资源进行动态组合时不可避免地遇到内、外部环境的不确定性,这些不确定性因素直接影响到制造云服务组合的执行成本、效率和质量。为了有效提升制造云服务组合的柔性,需要对其柔性能力进行测度。在假定某待选云服务集中的各服务资源能够以不同的效率替代完成任务的基础上,建立了考虑制造云服务组合柔性的效率柔性、冗余柔性、路径柔性和任务柔性的四维属性测度方法。最后,结合具体算例对该方法的应用过程进行了分析。