The effect of computer-assisted teaching on remedying misconceptions: The case of the subject “probability”

The aim of this study is to determine the effects of computer-assisted teaching (CAT) on remedying misconceptions students often have regarding some probability concepts in mathematics. Toward this aim, computer-assisted teaching materials were developed and used in the process of teaching. Within the true-experimental research method, a pre- and post-test control group study was carried out with 37 seventh-grade students-18 in the experimental group (CAT) and 19 in the control group (traditional teaching). A 12-item instrument, made up of 4 items related to each of the concepts “Probability Comparisons (PC),” “Equiprobability (E),” and “Representativeness (R),” was developed and implemented with the participants. After the teaching intervention, the same instrument was again administered to both groups as a post-test. In light of the findings, it can be concluded that computer-assisted teaching was significantly more effective than traditional methods in terms of remedying students’ misconceptions.     

模具钢Cr7Mo3V2Si渗扩氮等温淬火复合强韧化

研究了渗扩氮等温淬火对Ｃｒ７Ｍｏ３Ｖ２Ｓｉ钢硬度，组织，韧性和含氮硬化层扫描断和口形态的影响。结果表明，Ｃｒ７Ｍｏ３Ｖ２Ｓｉ钢制冷作模具复合强韧化处理后的使用寿命提高１倍，且破坏形式得改善。     

基于改进BP网络的装甲装备机动性能评估模型

收敛速度慢、易陷入局部极值是传统的BP神经网络难以避免的问题,最终可能导致网络训练失败．在量化装甲装备机动性能指标的基础上,采用遗传算法对BP神经网络权值进行优化,用自适应梯度下降法对传统BP神经网络进行训练,从而建立装甲装备机动性能评估模型,并通过二次训练得到评估值．仿真结果表明该改进网络收敛速度明显优于传统网络,能有效避免局部板值问题。     

含氮化合物在天然气运移中的示踪作用——以平落坝—邛西构造带须二段气藏为例

探讨了川西南部平落坝—邛西地区储层沥青中吡咯类化合物的分布特征和该区须二段储层中天然气的运移方向,指出：平落坝—邛西构造带储层沥青含氮化合物中吡咯类化合物的丰度、异构体参数的绝对大小与相对变化说明该构造平面上运移效应主要是对平落坝地区的吡咯类分布具有控制作用,总体表现出自西向东运移的趋势,而在整个平落坝—邛西构造带,这种控制并不明显;该构造须二段气藏具有原地或近源性,其天然气以大范围内的垂向运移为主。     

鄂尔多斯盆地东南部宜川—黄龙地区马五段白云岩次生灰化作用特征与成因分析

石灰岩的白云岩化作用因能形成较好的储层而备受关注,以往学者开展大量的分析和研究工作,但对白云岩的次生灰化作用的研究和认识程度均较低。次生灰化是发生在碳酸盐岩中重要的成岩作用类型之一,对储层的储集性能具有显著的影响作用。分析鄂尔多斯盆地东南部宜川—黄龙地区奥陶系马家沟组马五段次生灰岩岩石学特征及其形成的成岩阶段,并对次生灰岩的成因及主控因素进行探讨,指出古地貌低洼部位有利于白云岩次生灰化作用的发生,裂缝体系也是次生灰化作用的控制因素之一,泥晶含膏白云岩在低温条件下易于发生次生灰化作用。这些认识在碳酸盐岩风化壳储层预测方面具有理论指导意义,在油气勘探实践中具有重要的应用价值。     

VB(VBA)在AutoCAD2005二次开发中的应用

简要介绍了AutoCAD的二次开发平台,通过添加一个菜单项的实例讲述了将VB和VBA两者结合对AutoCAD2005进行二次开发的过程,以及如何在菜单宏中嵌入自己编制的可执行代码,并在AutoCAD2005启动时自动加载自定义菜单的技巧。     

有效烃源岩及其与天然气藏关系探讨

在天然气成因研究和勘探中,确定有效烃源岩和有效成藏组合是非常重要的。对于原型盆地来说 ,无论是碳酸盐岩还是泥岩 ,其有效烃源岩有机碳丰度下限值均为 0 .5 %。对于多旋回叠合残留盆地来说 ,该有机碳下限值对于二次生烃已不适用。有机质的成熟度不同 ,二次生烃有效烃源岩有机碳的下限值也不同 ,有机质成熟度 Ro 值在 1 .0 %～ 1 .2 %之间时 ,有机碳下限值为 1 .5 %～1 .8% ,Ro 值在 1 .2 %～ 2 .0 %之间时 ,有机碳下限值为 1 .8%～ 3 .2 % ,Ro 值在 2 .0 %～ 3 .0 %之间时 ,有机碳下限值为 3 .1 %～ 8.4% ,有机质成熟度 Ro 大于 4.0 %、H/C比值小于 0 .3的地区 ,无论有机碳丰度有多高 ,找气藏的希望则相当小。另一类有效烃源是古油气藏的储层沥青和局部残留的液态烃 ,由其裂解生成的烃类可以形成轻质油藏和天然气藏 ,这些次生油气藏有的再次被改造则形成晚期的天然气藏。因此 ,有效烃源岩或有效烃源生、排烃中心的叠加决定了次生油气藏的分布。     

Preferential petroleum migration pathways and prediction of petroleum occurrence in sedimentary basins： A review

The aim of this paper is to review the major points of contention concerning secondary petroleum migration, to discuss the nature and primary controls of the positions of petroleum migration pathways in sedimentary basins, and to illustrate the importance of preferential petroleum migration pathways for the formation of large oil/gas fields away from generative kitchens. There is competition between the driving force (buoyancy) and the restraining force (capillary pressure controlled largely by permeability contrast) in controlling the positions of petroleum migration pathways in heterogeneous carrier beds. At a large scale, there is a critical angle of dip of the carrier beds which determines the relative importance of structural morphology or permeability contrasts in controlling the positions of petroleum migration pathways in heterogeneous carrier beds. Maximum-driving-force–controlled migration pathways occur in carrier beds with an angle of dip greater than the critical dip and the positions of petroleum migration pathways are controlled mainly by the morphology of the sealing surfaces. Minimum-restraining-force–determined migration pathways occur in carrier beds with an angle of dip smaller than the critical angle where permeability contrasts would exert a more important influence on the positions of petroleum migration pathways. Preferential petroleum migration pathways (PPMP), defined as very restricted portions of carrier-beds that focus or concentrate petroleum from a large area of the generative kitchen, determine the distribution of oil and gas in sedimentary basins. The focusing of petroleum originating from a large area of the generative kitchens into restricted channels seems to be essential not only for long-range petroleum migration in hydrostatic conditions, but also for the formation of large oil or gas fields. Regions may miss out on petroleum migration because of its three-dimensional behavior, and two-dimensional migration modeling may be misleading in predicting petroleum occurrences in certain circumstances.     

一种估计管材硬化模型参数的方法

管材力学性能参数的准确性是影响管材塑性成形有限元数值模拟质量的关键因素之一。单向拉伸试验的试件取自滚弯和焊接等制管工序之前的平板坯料 ,所测应力—应变关系无法真实描述管材的塑性变形行为。单向拉伸试验也不能精确反映管材在实际塑性成形中所处的复杂应力状态。基于各向同性硬化假设 ,本文提出了一种轴压胀形、单向压缩试验和数据拟合技术相结合的估计管材硬化模型参数的方法。有限元数值模拟结果显示 ,由这种方法所估计出的管材硬化模型参数是相当准确的。     

一种改进的机载前斜视SAR二次距离压缩成像算法

该文基于斜视距离模型,直接推导了适用于大斜视合成孔径雷达(SAR)成像的二次距离压缩(SRC)算法,在此基础上提出了一种改进的机载前斜视SAR的SRC成像算法。通过补偿距离频率的三次相位项,有效改善了大斜视SAR成像距离压缩旁瓣非对称畸变的问题,通过补偿波束前视引入的平动相位项,解决了图像位置在方位向发生偏移的问题。给出了实现步骤和算法流程,对比了不同斜视角情况下算法改进前后的成像效果。仿真表明,该算法能有效改善大斜视SAR的成像质量,适合于大斜视机载SAR成像。