泡沫陶瓷过滤片后添加下置包对提高砂型铸造中铝液充型能力的研究

以铝液的流动性试样为研究对象,研究砂型铸造泡沫陶瓷过滤片后安放一定尺寸的下置包对铝液流动性的影响.同时,将下置包运用于生产热裂圆环薄壁铸件,表明:在泡沫陶瓷过滤片后安放一定尺寸的下置包对金属液的充型能力有较大提高,并且下置包的设置和安放工艺简单.     

有色合金用呋喃树脂砂溃散性的研究

呋喃树脂砂用于有色合金铸造时，由于浇注温度低，型芯的演散性较差。对于薄壁铝合金铸件和厚大型芯该问题尤其明显。为解决这个问题，作者以ＫＪＮ－Ⅲ型呋喃树脂自硬砂为对象，就其在不同加热温度下的温度场、残留强度及热强度进行了系统的研究。通过对树脂添加剂与残留强度之间关系的研究，得到几种较好的树脂添加剂。在合适的加入量下，可使呋喃树脂砂的残留强度下降４０％～８０％，取得了令人满意的结果。     

覆砂金属型工艺设计及其数值模拟

论述了覆砂金属型铸造工艺及其传热机理,对其数值模拟技术进行了分析,并利用ANSYS软件模拟了球铁曲轴的覆砂金属型铸造温度场,确定了其工艺参数.     

基于Visual C＋＋的沙波测量成像系统

介绍了利用激光器、CCD相机、图像采集卡和计算机组成的沙波测量成像系统。阐述了系统的工作原理和计算机图像处理的方法。     

SODA: A new method of in-scene atmospheric water vapor estimation and post-flight spectral recalibration for hyperspectral sensors: Application to the HyMap sensor at two locations

A new method of estimating per-pixel atmospheric column water vapor (ACWV) and potential differences in the reported band center wavelengths of the HyMap sensor has been developed. The new method uses variations of a second order derivative algorithm (SODA) to assess the impact of atmospheric residual features on calculated surface reflectance spectra after atmospheric compensation. The SODA method provides an alternative to the current band ratio techniques of ACWV estimation and also allows the same form of algorithm to be used for the estimation of possible band shifts. A comparison of in-situ measured surface reflectance at two field sites in Western Australia demonstrates improvement in the resulting spectra when post-flight updates are made to the reported HyMap band center wavelengths and applied during the atmospheric compensation process. The same SODA methodology was varied to estimate the ACWV on a per-pixel basis and found to significantly reduce the appearance of the underlying surface structure on the resulting ACWV images as well as improve the overall accuracy of the estimation. The ACWV estimated from the HyMap imagery at the two field sites was found to agree with in-situ atmospheric ACWV measurements to within 2% and represented a two fold increase in accuracy over a 3 band ratio Continuum Interpolated Band Ratio (CIBR) technique of ACWV estimation.     

微伏古隆起对滩坝砂体分布的控制作用——以东营凹陷八面河地区面120区沙四段为例

东营凹陷八面河地区面120区沙四段各砂组沉积时期的精细古地貌,为一北东走向、北西倾的宽缓古隆,隆上发育多个微伏古隆起,相应单砂体分布基本与微伏隆起发育耦合,砂体分布存在滩连滩、滩外滩、滩叠滩三种模式。     

复合相控砂体预测技术在潜江凹陷潜江组的应用

沉积相与物探技术相结合,是对盐湖盆地潜江凹陷特殊地质条件以及实际精细勘探的需要。可用成熟的复合相控砂体预测技术在潜江组储层预测中区分多种复杂岩性、识别不同厚度砂体。     

Interface Characteristics and Laboratory Constructability Tests of Novel Fiber-Reinforced Polymer/Concrete Piles

Conventional pile materials such as steel, concrete, and timber are prone to deterioration for many reasons. Fiber-reinforced polymer (FRP) concrete composites represent an alternative construction material for deep foundations that can eliminate many of the performance disadvantages of traditional piling materials. However, FRP composites present several difficulties related to constructability, and the lack of design tools for their implementation as a foundation element. This paper describes the results of an experimental study on frictional FRP/dense sand interface characteristics and the constructability of FRP–concrete composite piles. An innovative toe driving technique is developed to install the empty FRP shells in the soil and self-consolidating concrete is subsequently cast in them. The experimental program involves interface shear tests on small FRP samples and uplift load tests on large-scale model piles. Two different FRP pile materials with different roughness and a reference steel pile are examined. Static uplift load tests are conducted on different piles installed in soil samples subjected to different confining pressures in the pressure chamber. The results showed that the interface friction for FRP materials compared favorably with conventional steel material. It was shown that toe driving is suitable for installation of FRP piles in dense soils.     

Stress Dilatancy and Fabric Dependencies on Sand Behavior

A stress dilatancy model with embedded microstructural information, originally developed by the writers, is used to illustrate the pivotal importance of dilatancy and fabric on the behavior of sand. Fabric, as a second-order tensor, enters into the stress dilatancy equation obtained from a microscopic analysis of an ensemble of rigid particles. Model simulations of sand behavior are carried out in triaxial stress conditions along strain paths with varying degrees of controlled dilation (or compaction) including isochoric deformations as a particular case. Under particular strain paths and fabric conditions, it is shown that a relatively dense sand can succumb to instability or liquefaction under other than isochoric (undrained) conditions. This phenomenon is in accord with laboratory experiments in which dilation or compaction is controlled by modulating the amount of water flowing in or out of a sand specimen during shearing. Mixed drained–undrained loading paths are also simulated with particular reference to fabric dependence at a fixed void ratio. Model simulations capture most of the observed characteristics of sand response, such as instability and asymptotic behavior under various conditions.     

Experimental Study on the Aging of Sands

Aging effects in sand, such as increases in cone penetration resistance with time after deposition and/or densification, are known to occur in the field, but the causes of these effects are not fully understood. A laboratory testing program was designed to study mechanisms responsible for aging effects under controlled conditions. The testing program included measurements of the small strain shear modulus, electrical conductivity, pore fluid chemistry, and minicone penetration resistance after different periods of aging. Two different sands were tested, and aging effects were evaluated for different combinations of relative density, temperature, and pore fluid composition. Increases in the small strain shear modulus were observed throughout most of the tests, and chemical analyses suggest that precipitation of carbonate and silica occurred in two tests. Despite these changes, there was no corresponding increase in the minicone penetration resistance with time in any of the tests. It is unlikely that precipitation of carbonate or silica is responsible for aging effects in sands; other possible mechanisms include arching due to dissipation of blast gases and redistribution of stresses through the soil skeleton. An additional possibility is that the boundary conditions imposed by the laboratory tests obscure changes in penetration resistance that would be measured had the volume of sand tested been much larger. The implications of these findings in terms of other published field and laboratory studies are discussed.