岩土工程勘察在商品房和物流园岩土工程勘察中的异同

岩土工程勘察作为根据建设工程的要求,查明、分析、评价建设场地的地质、环境特征和岩土工程条件,编制勘察文件的活动,在不同的建设项目中,会采用不同的技术方法和手段。本文以商品房和物流园岩土工程勘察为例,从项目概况、勘察手段、场地基础地质条件、勘察举措等方面,细致全面地比较分析了岩土工程勘察在两种建设项目中的异同。     

A passenger reduces sleepy driver's activation in the right prefrontal cortex: A laboratory study using near-infrared spectroscopy

The present study aimed to examine how a passenger affects the sleepiness effect (awake vs. sleepy) on an individual's prefrontal activation during a simulated driving-game task using a wireless portable near-infrared spectroscopy (NIRS) device. Participants drove from start to goal along default routes either solely (no-passenger group) or with a friend sitting beside him/her as a passenger (with-passenger group). Sleepiness level was assessed by a five-item scale questionnaire. In the no-passenger group, there were no performance and activation differences between the sleepy and awake participants. In the with-passenger group, by contrast, the sleepy participants showed more errors and lower activations in their right prefrontal cortex than the awake participants. These results suggest that a passenger has little effect on awake participants, but may weaken the sleepy participants’ vigilance and/or their cognitive abilities of action control. Practically, the present study demonstrates that NIRS may provide us a new possibility to monitor and examine the driver's mental states in the brain.     

地铁联络通道人工冻结法的数值模拟分析

以冻结管间距为0.3、0.4、0.5 m及其相应间距的单双排布置作为主要变量,考虑土的比热容、密度以及导热系数,建立热传递有限元模型对冻结法施工的积极冻结过程以及融化过程进行数值模拟。研究表明:当冻结管采用间距为0.3 m布置时,双排管会比单排管的制冷效果更加明显。同时发现冻结管间距越密集制冷效果会越高,从经济上考虑,冻结管的布置形式可以采用间距为0.4 m双排布置。在隧道中心竖向位置处,距离地表面越近,受到冻结后土体竖向产生的位移越大,在冻结帷幕内的冻土位移不随深度的变化而变化;在地表面距离隧道中心水平距离越大的位置,受冻土膨胀产生的竖向位移越小,在隧道中心处位移最大,同时发现地表水平方向的径向位移变化并不明显。     

某多层建筑物纠倾方法分析与实施

某4层建筑物地基土为深厚的饱和淤泥质软土,基础采用沉降控制复合桩基设计。建筑物施工完成后,建筑物发生向北倾斜的现象。纠倾过程中先后采用了堆载纠倾、降水纠倾以及冲水排土纠倾的方法,均未见明显效果,最终采用截桩纠倾,有效解决了问题。结论表明,在有桩建筑物的纠倾中,采用截桩纠倾安全有效。     

基于钻孔压水试验数据的岩体裂隙特征分析

以某隧道工程压水试验为例,利用钻孔压水试验P~Q曲线对岩体裂隙特性进行定性分析。选取该试验孔三段压水试验成果,对岩体裂隙的发育程度、张开度、填充情况及受压情况下裂隙变化状态,进行综合分析与研究,并将分析结果与钻探取芯、波速测试成果进行对比和相互验证。     

Multiple kernel-based multi-instance learning algorithm for image classification

In this paper, a novel multi-instance learning (MIL) algorithm based on multiple-kernels (MK) framework has been proposed for image classification. This newly developed algorithm defines each image as a bag, and the low-level visual features extracted from its segmented regions as instances. This algorithm is started from constructing a “word-space” from instances based on a collection of “visual-words” generated by affinity propagation (AP) clustering method. After calculating the distance between a “visual-word” and the bag (image), a nonlinear mapping mechanism is introduced for registering each bag as a coordinate point in the “word-space”. In this case, the MIL problem is transformed into a standard supervised learning problem, which allows multiple-kernels support vector machine (MKSVM) classifiers to be trained for the image categorization. Compared with many popular MIL algorithms, the proposed method, named as MKSVM-MIL, shows its satisfactorily experimental results on the COREL dataset, which highlights the robustness and effectiveness for image classification applications.     

A novel multifunctional phosphorous and nitrogenous reactive flame retardant toward epoxy resins by one-pot method

Epoxy resin (EP) has attracted considerable attention in packaging, electronic devices, aerospace, and coatings fields owing to its remarkable chemical and physical performance. However, the inherent flammable performance and unfavorable brittle nature seriously restricted its application in sophisticated industry. Herein, an efficient reactive 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO)-based flame retardant (DB-DAD) was prepared by a facile “one-pot” method. Due to their synergistic gas-phase and solid-phase flame-retardant effects, DB-DAD modified EP composites (EP/DB-DAD composite) easily achieved UL-94 V-0 ratings, and an EP/DB-DAD composite with a 0.32 wt% phosphorus content had an excellent (30.2%) limiting oxygen index. In addition, the amounts of heat and smoke decreased by 28.1% and 24.8%, respectively. Due to the introduction of long and flexible aliphatic chains, the EP/DB-DAD composites exhibited satisfactory mechanical properties, the flexural and tensile toughness of EP/6% DB-DAD were 82.5% and 62.2% higher than those of neat EP, respectively. Furthermore, EP/DB-DAD composite showed good transparency (>85%) and favorable UV shielding performance. The EP/DB-DAD composite with good comprehensive performance is extremely promising to accelerate EP application in high-tech industries.     

Synthesis and evaluation of dioctyl 2,5-thiophenedicarboxylate as a potentially bio-based plasticizer for poly(vinyl chloride)

In this work, dioctyl 2,5-thiophenedicarboxylate (DOT), a potentially bio-based plasticizer, was synthesized and evaluated as an alternative to traditional petroleum-based plasticizers. The chemical structure of DOT was confirmed by FTIR and ¹H NMR. Besides, its plasticization effect on poly(vinyl chloride) (PVC) was investigated in detail, and dioctyl 2,5-furandicarboxylate (DOF) as well as dioctyl isophthalate (DOIP) with similar chemical structures were used as references. The DMA results showed that the glass transition temperature (T_g) of PVC/DOT, PVC/DOF, and PVC/DOIP was 45.1°C, 33.6°C, and 51.3°C, respectively, indicating that the plasticizing efficiency of DOT was better than that of DOIP but lower than that of DOF. However, the tensile test results exhibited that the elongation at the break of PVC/DOT was higher than that of PVC/DOF, which was attributed to the easy phase separation between DOF and PVC. In addition, DOT displayed the best volatility resistance and exudation resistance among the three plasticizers, attributed to its highest molecular weight. Moreover, the migration loss of DOT in non-polar solvents was much smaller than that of DOIP because of its stronger molecular polarity. In conclusion, DOT has good potential to replace traditional petroleum-based plasticizers and be used as a primary plasticizer for PVC.     

人工湿地在农业面源污染治理中的应用

简要概述了农业面源污染,并介绍了人工湿地的定义、特点、机理、类型、构建方式和工艺流程等。通过分析国内外人工湿地技术治理农业面源污染实例进展,总结出人工湿地处理农业面源污染具有应用广泛、投资低廉、综合效益高的特点。在讨论现阶段人工湿地的研究状况和应用前景的基础上,提出了目前人工湿地应用的主要问题和发展方向。     

充水保压蜗壳与外围结构联合承载过程的力学仿真分析

水电站充水保压蜗壳兼备直埋式与垫层式蜗壳的优点,但受力分析复杂。为此,以一个HD值较高的蜗壳为例,应用三维有限元法研究了充水保压蜗壳与外围结构联合承载的过程,模型和计算过程精细,展示了联合承载过程中各结构的力学规律。结果表明:充水发电时,蜗壳与混凝土大部分区域闭合,脱开的面积约3%;外围混凝土大部分区域处在压应力状态,受拉部位少且拉应力较低,钢筋拉应力较小,此情况被现场观测所证实;采用常用公式或完全用有限法计算,蜗壳承载比的计算结果相差不超过3%;蜗壳充水保压值越低,充水运行期与混凝土的接触压力越大、蜗壳的承载比越小,因此蜗壳宜取较小的充水保压值,有利于减少振动;与常规打压顺序相比,非常规打压顺序不利于蜗壳与混凝土的贴合。此成果为该水电站的蜗壳设计提供了重要参考,电站已全面投产,蜗壳及外围结构工作表现良好。