基于历史地图转译的兴城古城历史景观层积性研究

城市历史景观概念的提出,强调古城演进过程中的动态层积,为古城的保护提供了全新的思路。文章从城市历史景观视角出发,对各时代兴城古城历史地图进行转译,提取出自然生态、城市街巷、城墙体系和历史建筑四个类型的景观要素,将景观要素的层积和变化进行可视化,从而更直观地认知古城景观的历史层积过程。

民间文学的层积性研究

在民间文学中有一种类似于地层中的历史积压现象,我们把这种现象称之为民间文学的层积性。它是民间文学作品在发展的过程中,人们不断地依据不同历史时期的文化现象去改变其内容时,各个历史时期的文化现象作为一种历史印迹在民间文学作品中累积而成的。探讨民间文学作品中这种层积性,不仅有助于了解各民间文学作品产生和形成的时间,同时还有助于揭示各民间文学作品在产生和发展的过程中与历史的关系,是一种有效认识民间文学历史价值的方法。

基于GIS应用的乡村历史文化景观层积性研究——以徽州万安古埠码头为例

徽州村落空间内会积累多样的片段式印记,并在连续性的历史进程中不断叠加,形成村落中具有层积性的各类历史文化景观点。文章以徽州万安古镇最具特色的古埠码头文化景观点为例,通过其层积柱体现状与未来发展趋势,应用地理信息技术中的路径法、缓冲区分析将层积性空间数字化,旨在为徽州古镇的历史文化景观层积发展的数据化提供一些依据。

成都古城层积性历史景观调查与保护研究

城市的发展会留下独特的印迹,层积是发展的积淀,对于城市历史景观层积性的全面研究有助于保护城市特征,进而缓和城市历史文化遗产保护与城市发展之间的关系。在城市历史景观理论的思路拓展下,本文对成都古城的历史文脉展开调查,运用GIS叠置分析,从空间要素、街巷要素、用地要素三个方面进行层积价值研究,以期为成都市层积性历史景观保护提出若干建议。

历史性城市景观视角下的缅甸曼德勒空间层积性研究

历史性城市景观概念的提出,为城市遗产保护和发展提供了多维、动态的指引,对人类文化遗产的整体性保护有着积极的启示意义。从历史性城市景观保护的视角出发,"一带一路"沿线国家缅甸的第二大城市曼德勒发展历程可分为3个时期;依据时间动态发展的层积性原则对不同时期文化遗产的要素进行讨论,并探究其在空间的分布对空间结构的影响,最后根据不同特征对曼德勒历史性城市景观进行分类,并相应提出保护策略。在研究思路上纠正了传统只针对历史建筑物个体进行保护或修复的方式,将研究范围扩大到能够在空间上体现历史独特性和叠加性的文化遗产,强调了不同历史时期在城市空间的时空印记,以期对具有较为完整的文化特色及文化遗产的发展中国家的大城市空间文化遗产保护和发展模式的研究提供借鉴。

层积视角下武夷山国家公园文化景观特征识别

【目的】中国自然保护地具有自然与人文双重属性,系统、客观、可视化地识别文化景观特征,可为自然保护地空间规划和资源整体性管护提供参考。【方法】以武夷山国家公园为研究对象,从层积视角出发深入识别文化景观特征。在时间序列上,选取武夷山国家公园文化景观产生与发展的6个典型历史时期,在特征要素上,选取山水地貌、河流关系、景观结构、土地利用、感知意向5个指标,特征识别采用两步聚类法和图像分割技术。【结果】从静态的历史时期来看,武夷山国家公园在唐、宋、元、明、清和当代分别呈现出6类、17类、14类、21类、24类和36类文化景观特征类型。从长时序的演变视角出发,总结了武夷山国家公园文化景观在数量、空间及形式上的特征。识别出武夷山文化景观高层积区域位于九曲溪中、东部(一曲至七曲)以及南、北两岸部分区域,包含243个文化景观点、19处面状山体和9条线状河流。【结论】从层积性视角出发构建的文化景观特征识别路径,为明确区域文化价值提供了量化与空间化的科学手段,有助于国家公园文化资源的分级、分类管护工作。

浅析积云性层积云与淡积云的区别及观测技巧

"看云识天气",可见云的变化对天气的影响很重要,在高空风的影响下,云的外形特征发生变化,特别是被高空风吹后的淡积云容易与积云性层积云混淆。本文根据形态学和发生学的理论结合观测经验对Sc cug、Cu hum两者的色泽、高度、云量、成因、出现时间、演变情况、所伴见的天气现象等进行分析;在复杂天气条件下,Sc cug和Cu hum的观测技巧。

历史性城镇景观视角下遗产价值试论——以揭阳城隍庙为例

城市遗产具有重要价值,它与城市生活密切关联,构成了极具地域特色的城市文化景观。尝试突破以往对遗产价值认知的传统解读,在城市遗产价值识别中引入历史性城镇景观视角与方法,建构了以层积性与关联性为切入点,由“本体价值”“衍生价值”“工具价值”3个维度共同构成的价值识别框架;在历史层积演变中考察遗产的真实性,分析其与历史性城镇景观的动态关联,强调城市遗产作为历史性城镇景观要素的整体价值。以揭阳城隍庙为例,通过层积认知和关联分析,阐明了其在城市历史空间存续、地方群体文化认同和城市管理协同三方面的核心价值特征及具体呈现,对揭阳城隍庙承载的多元价值进行全面揭示,以期为遗产价值理论与可持续性保护提供新的理论探索方向。

Microstructure evolution of 7050 aluminum forgings during surface cumulative plastic deformation

To elucidate the mechanisms of regulating the microstructure uniformity in 7050 aluminum forgings through surface cumulative plastic deformation(SCPD),the microstructure under different solution treatments was investigated using metallographic observation(OM),electron backscatter diffraction(EBSD),transmission electron microscopy(TEM),and X-ray diffraction(XRD).The findings demonstrate that the most uniform microstructure in the forgings is achieved with a solution treatment at 470℃for 30 min.The SCPD process generates a significant number of needle-shaped precipitates,resulting in a higher dislocation density and stored energy.Solution treatments alleviate the pinning effect of second-phase particles and facilitate static recrystallization(SRX)in forgings,leading to a reduction in grain size.Additionally,mechanical testing results demonstrate 7%−13%increase in tensile strength and more uniform elongation of the forgings in different directions.

蔽光层积云能否降阵雨

众所周知,阵性降水主要产生在不稳定气团内部,也可形成在第二型冷锋云系,即主要降自积雨云(cb)、浓积云(Cucong)或积云性层积云(Sccug)。其天气条件为气层不稳定。

观测中的技术性错情

在技术性错情中,目测项目比例较大.在云量、云状的观测记录和互相配合上存在较多失当之处.如当积云性层积云、透光高积云等布满天空时,总云量不宜记10成而应记10^-;而当天空布满高层云、雨层云时,一般不宜记10^-而应记10.

高原地区非阵性霰

高原上由于热力和动力作用,对流扰动较强,积雨云全年可见。积雨云、浓积云降阵性的霰,在高原上是常见的现象。但非阵性霰在高原地区也并非不可能。现以理塘站观测到的一次非阵性霰实例作一浅析。

Automatic discrimination of sedimentary facies and lithologies in reef-bank reservoirs using borehole image logs

Reef-bank reservoirs are an important target for petroleum exploration in marine carbonates and also an essential supplemental area for oil and gas production in China. Due to the diversity of reservoirs and the extreme heterogeneity of reef-banks, it is very difficult to discriminate the sedimentary facies and lithologies in reef-bank reservoirs using conventional well logs. The borehole image log provides clear identification of sedimentary structures and textures and is an ideal tool for discriminating sedimentary facies and lithologies. After examining a large number of borehole images and cores, we propose nine typical patterns for borehole image interpretation and a method that uses these patterns to discriminate sedimentary facies and lithologies in reeI^bank reservoirs automatically. We also develop software with user-friendly interface. The results of applications in reef-bank reservoirs in the middle Tarim Basin and northeast Sichuan have proved that the proposed method and the corresponding software are quite effective.

Preparation and Characterization of Nanostructured Ni-TiN Composite Films

Ni-TiN nanocomposite films were produced from a Ni plating bath containing TiN nanoparticles by using dc electroplating method. The structure and surface morphology of Ni-TiN composite coatings were analyzed by atom force microscope, X-ray diffraction, and trans- mission electron microscopy. Meanwhile, the anti-corrosion properties, hardness and ther- mostability of Ni-TiN nanocomposite films were also investigated and compared with the traditional polycrystalline Ni coatings. The results show that, compared with the traditional polycrystalline Ni film, Ni-TiN nanocomposite coatings display much better corrosion resistance, higher film hardness, and thermal stability. In addition, the hardness of Ni-TiN nanocomposite coatings decreases slightly with the increase of electroplating current density, which may be due to the synergism of hydrogen evolution and faster nucleation/growth rate of nickel crystallites.

Electrodeposition and corrosion resistance of Ni-P-TiN composite coating on AZ91D magnesium alloy

In order to improve the corrosion resistance and microhardness of AZ91D magnesium alloy, TiN nanoparticles were addedto fabricate Ni-P-TiN composite coating by electrodeposition. The surface, cross-section morphology and composition wereexamined using SEM, EDS and XRD, and the corrosion resistance was checked by electrochemical technology. The results indicatethat TiN nanoparticles were doped successfully in the Ni-P matrix after a series of complex pretreatments including activation, zincimmersion and pre-electroplating, which enhances the stability of magnesium alloy in electrolyte and the adhesion betweenmagnesium alloy and composite coating. The microhardness of the Ni-P coating increases dramatically by adding TiN nanoparticlesand subsequent heat treatment. The corrosion experimental results indicate that the corrosion resistance of Ni-P-TiN compositecoating is much higher than that of uncoated AZ91D magnesium alloy and similar with Ni-P coating in short immersion time.However, TiN nanoparticles play a significant role in long-term corrosion resistance of composite coatings.

CeO_2/Zn NANOCOMPOSITE COATING BY ELECTRODEPOSITION

The nanocomposite coating is obtained by electrochemical deposition of the zinc plating solution with ceria nanoparticles (mean diameter 30 nm). The effect of ceria nanoparticles on the electrodeposited zinc coating is stu died by weight loss test, inductively copuled plasma quantometer (ICP), scanning electron microscopy (SEM) and X ray diffraction (XRD), respectively. It is found that under the same electrodeposition conditions, the corrosion resistance of the nanocomposite coating increases obviously while that of the micron composite coating only improves slightly; The ceria content of the nanocomposite coating is more than that of the micron composite coating. Ceria nanoparticles modify the surface morphology and crystal structure of the zinc matrix in correlation with the increase of corrosion resistance.

Formation mechanism and oxidation behavior of MoSi_2-SiC protective coating prepared by chemical vapor infiltration/reaction

In order to protect C/C composites from oxidation, SiC-MoSi2 composite coating was synthesized by chemical vapor infiltration /reaction （CVI/CVR） technology. A porous Mo layer was prefabricated on SiC coated C/C composites, and then MoSi2 and SiC were subsequently prepared in a CVI /CVR process using methyltrichlorosilane （MTS） as precursor. The deposition and reaction mechanism of the MoSi2-SiC composite coating was investigated by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The oxidation behavior of SiC-MoSi2 coated specimens was tested. The results show that the porous Mo layer can be densified with SiC phase decomposed from MTS, and transformed into SiC-MoSi2 by reacting with MTS as well. A dense composite coating was prepared with optimized deposition parameters. The coated specimen exhibits a good oxidation resistance with a little mass loss of 1.25% after oxidation at 1500 °C for 80 h.

Effect of La_2O_3/Ce O_2 particle size on high-temperature oxidation resistance of electrodeposited Ni-La_2O_3/Ce O_2 composites

Ni-La2O3/CeO2 composite films were prepared by electrodeposition from a nickel sulfate bath containing certain content of micrometer and nanometer La2O3/CeO2 particles. The effect of La2O3 or CeO2 particle size on the oxidation resistance of the electrodeposited Ni-La2O3/CeO2 composites in air at 1000 °C was studied. The results indicate that, compared with the electrodeposited Ni-film, Ni-La2O3/CeO2 composites exhibit a superior oxidation resistance due to the codeposited La2O3 or CeO2 particles blocking the outward diffusion of nickel. Moreover, compared with nanoparticles, La2O3 or CeO2 microparticles have stronger effect because La2O3 or CeO2 microparticles also act as a diffusion barrier layer at the onset of oxidation.

Microstructure and properties of nanocrystalline nickel coatings prepared by pulse jet electrodeposition

The fabrication of nanocrystalline nickel coatings was conducted by pulse jet electrodeposition on the substrate of 45# carbon steel.The effects of average current density on the surface morphology,microstructure,average grain size and microhardness of nickel coatings were investigated by scanning electron microscopy(SEM),X-ray diffractometry(XRD)and microhardness measurement.In addition,the corrosion resistances of coating and substrate were compared.It is revealed that the nickel coatings prepared by pulse jet electrodeposition exhibit a fine-grained structure with a smooth surface and a high density,although some pores and defects are still present in coatings.With the increase of average current density,the average grain size of nickel coatings is reduced at first and then increased.The coating with the optimum compactness,the smallest average grain size(13.7 nm)and the highest microhardness are obtained at current density of 39.8 A/dm2.The corrosion resistance is obviously increased for the coatings prepared by pulse jet electrodeposition;however,the corrosion rate is increased after a certain period due to the penetration of the corrosive media.

Microstructure homogeneity regulation of 7050 aluminum forgings by surface cumulative plastic deformation

To regulate the microstructure homogeneity of large aluminum structural forgings for aircraft,the surface cumulative plastic deformation was proposed.The microstructure of 7050 aluminum forgings after the surface cumulative plastic deformation was investigated by electron backscatter diffraction(EBSD),transmission electron microscopy(TEM),and X-ray diffraction(XRD).The results showed that the microstructure evolution of 7050 aluminum forgings was more sensitive to the deformation temperature than the strain rate.The dislocation density continued to increase with the decrease of the deformation temperature and the increase of the strain rate.Dislocation density and stored energy were accumulated by the surface cumulative plastic deformation.Besides,a static recrystallization(SRX)model of 7050 aluminum forgings was established.The SRX volume fraction calculated by this model was in good agreement with the experimental results,which indicated that the model could accurately describe the SRX behavior of 7050 aluminum forgings during the surface cumulative plastic deformation.