基于多视图立体视觉的沙堆三维尺寸测量研究

利用从运动中恢复结构方法(SFM),提出了一种基于多视图立体视觉的沙堆三维重建及三维尺寸测量方法。首先根据SFM方法的求解不稳定特点,结合光束平差法对SFM求解过程进行分析及优化;其次针对SFM重建结果为稀疏点云的问题,利用基于面片的稠密重建算法重新生成稠密的三维点云,再利用泊松算法对密集点云进行三维曲面重建;最后获得模型的三维尺寸信息。对某建筑工地的沙堆进行了三维尺寸的测量实验,实验结果验证了该方法的有效及可行性,提高了重建能力及精度,同时考虑了目标实际测量误差与重建误差,能够满足实际智能测量的应用需求。     

Learning a Deep Predictive Coding Network for a Semi-Supervised 3D-Hand Pose Estimation

In this paper we present a CNN based approach for a real time 3D-hand pose estimation from the depth sequence. Prior discriminative approaches have achieved remarkable success but are facing two main challenges: Firstly, the methods are fully supervised hence require large numbers of annotated training data to extract the dynamic information from a hand representation. Secondly, unreliable hand detectors based on strong assumptions or a weak detector which often fail in several situations like complex environment and multiple hands. In contrast to these methods, this paper presents an approach that can be considered as semi-supervised by performing predictive coding of image sequences of hand poses in order to capture latent features underlying a given image without supervision. The hand is modelled using a novel latent tree dependency model (LDTM) which transforms internal joint location to an explicit representation. Then the modeled hand topology is integrated with the pose estimator using data dependent method to jointly learn latent variables of the posterior pose appearance and the pose configuration respectively. Finally, an unsupervised error term which is a part of the recurrent architecture ensures smooth estimations of the final pose. Experiments on three challenging public datasets, ICVL, MSRA, and NYU demonstrate the significant performance of the proposed method which is comparable or better than state-of-the-art approaches.      

于都县黄麟地区绿色富硒土壤分布选区评价

通过于都县黄麟地区1:5万土地质量地球化学调查,基本査明该地区农作物中硒元素及其他元素的地球化学特征,综合分析岀绿色富硒土壤分布,并优选出绿色富硒地块,为特色农产品基地建设的开发与利用提供理论依据。     

CFD modeling of thermal contact resistance between solid contacting surfaces

Heat transfer has considerable applications in different industries such as designing of heat exchanger, nuclear reactor cooling, control system for spacecraft, and designing of microelectronics cooling. As the surfaces of two metals contact each other, this issue becomes so crucial. Thermal contact resistance (TCR) is one of the key physical parameters in heat transfer of mentioned surfaces. Measuring the experimental value of TCR in laboratory is highly expensive and difficult. As an alternative, numerical modeling methods could be engaged. In this study, inverse problem method solution is utilized as a proper method for estimation of TCR value. In this order, three different configurations (flat-flat, flat-cylinder, and cylinder-cylinder) were utilized in two steady and unsteady state conditions to predict the value of TCR. A comparison between the measured values and obtained values from the simulation show the errors for flat-flat, flat-cylinder, and cylinder-cylinder configuration after 10 min from starting the experiment are 4.6074%, 0.1662%, and 0.5622%, respectively. And in steady-state condition, the corresponding errors are 6.06e-3%, 1.506%, and 0.846%, respectively. In conclusion, the final results establish the fact that the inverse problem method solution can predict TCR values between contacting surfaces.     

地埋管换热器分区运行对土壤热堆积特性影响的研究

为了缓解埋管区域土壤的热量堆积问题,提出了埋管换热器按内中外、块状、间隔三种分区运行的策略,利用CFD软件建立了10×10的井群换热模型,对地源热泵系统在三种分区与不分区运行策略下运行十年进行数值模拟,分析不同分区运行策略对土壤温度分布和土壤热堆积特性的影响。模拟结果可知:不分区、内中外分区、块状分区、间隔分区四种运行策略下埋管区域的平均温度分别为25.23、23.31、23.06、23.28℃,最高温度分别为40.62、32.77、40.65、38.93℃;分区运行较不分区运行可以有效缓解热堆积作用,埋管区域整体温度较不分区运行时降低了2.00℃左右,内中外分区策略可以显著缓解埋管区域热堆积。     

Selective hydrogenation of acetylene over Pd/CeO2

Five hundred ppm Pd/CeO₂ catalyst was prepared and evaluated in selective hydrogenation of acetylene in large excess of ethylene since ceria has been recently found to be a reasonable stand-alone catalyst for this reaction. Pd/CeO₂ catalyst could be activated in situ by the feed gas during reactions and the catalyst without reduction showed much better ethylene selectivity than the reduced one in the high temperature range due to the formation of oxygen vacancies by reduction. Excellent ethylene selectivity of ~100% was obtained in the whole reaction temperature range of 50°C–200°C for samples calcined at temperatures of 600°C and 800°C. This could be ascribed to the formation of Pd_xCe_1−xO_2−y or Pd-O-Ce surface species based on the X-ray diffraction and X-ray photoelectron spectroscopy results, indicating the strong interaction between palladium and ceria.     

Catalytic combustion of methane over a highly active and stable NiO/CeO2 catalyst

In the last decades, many reports dealing with technology for the catalytic combustion of methane (CH₄) have been published. Recently, attention has increasingly focused on the synthesis and catalytic activity of nickel oxides. In this paper, a NiO/CeO₂ catalyst with high catalytic performance in methane combustion was synthesized via a facile impregnation method, and its catalytic activity, stability, and water-resistance during CH₄ combustion were investigated. X-ray diffraction, low-temperature N₂ adsorption, thermogravimetric analysis, Fourier transform infrared spectroscopy, hydrogen temperature programmed reduction, methane temperature programmed surface reaction, Raman spectroscopy, electron paramagnetic resonance, and transmission electron microscope characterization of the catalyst were conducted to determine the origin of its high catalytic activity and stability in detail. The incorporation of NiO was found to enhance the concentration of oxygen vacancies, as well as the activity and amount of surface oxygen. As a result, the mobility of bulk oxygen in CeO₂ was increased. The presence of CeO₂ prevented the aggregation of NiO, enhanced reduction by NiO, and provided more oxygen species for the combustion of CH₄. The results of a kinetics study indicated that the reaction order was about 1.07 for CH₄ and about 0.10 for O₂ over the NiO/CeO₂ catalyst.     

于都黄麟-祁禄山地区土地质量地球化学评价

通过对于都县黄麟-祁禄山地区开展1:5万土地质量地球化学调查,在野外土壤样品采集和化验测试的基础上,系统地研究了影响土地质量的各项地球化学指标特征与控制因素,基本查明有益元素、重金属元素分布,划分出重点污染区和绿色土地发展区,并进行土地质量等级评价,为永久基本农田建设、土地资源开发与利用等方面提出建议。