Inconel 690传热管GTAW对接焊接头组织及力学性能研究

对Inconel 690传热管材进行钨极气体保护焊(GTAW)对接焊,采用拉伸试验机、压扁试验机和光学显微镜测试和分析传热管焊接接头,同时利用ANSYS软件开展焊接接头在设计工况失压时的一次应力强度校核。研究结果表明:焊缝中心为树枝胞状晶,熔合线附近为粗大柱状晶。室温时接头的平均抗拉强度为619 MPa,平均屈服强度为292 MPa,350℃时接头平均抗拉强度为475 MPa,平均屈服强度为206 MPa,拉伸接头断裂从熔合区开始贯穿整个焊缝组织,呈塑性断裂。压扁试验和反向压扁试验结果表明管接头完好。通过ANSYS分析可知,设计工况下传热管接头350℃许用应力强度150 MPa限值可满足其一次应力强度要求,且裕量较大。     

某微细粒嵌布磁铁矿选矿工艺研究

针对某微细粒磁铁矿进行了全磁选流程和磁选-反浮选流程对比试验研究。结果表明,在最终磨矿细度相当的情况下,2种工艺流程都获得了产率48%左右、TFe品位66%左右、回收率80%左右的铁精矿指标,而采用磁选-反浮选流程的第三段磨矿量比全磁选流程减少了2/3。磁选-反浮选流程具有显著的节能降耗优势。     

变压吸附制氮(PSA)设备在炼油生产中的应用

针对某炼油装置氮气供需矛盾突出的问题,提出采用变压吸附(PSA)制氮设备,利用空压站净化风生产氮气方案,(1)降低空压站多余风量放空,减少浪费;(2)正常生产情况下,利用PSA设备生产氮气,对供氮管网压力调节。针对上述方案,结合空压站供风现状进行分析,得出结论:利用PSA制氮设备满足炼油装置高峰用氮是可行的,并提出了具体措施和运行过程中应注意的问题。     

Improved photoluminescence and multi-mode optical thermometry of Er3+/Yb3+ co-doped (Ba,Sr)3Lu4O9 phosphors

Contactless optical thermometers have attracted extensive attentions for applications in scientific research and technological fields due to their apparent advantages. Herein, a novel sequence of Ba_3-xSr_xLu₄O₉ (B_3-xS_xLO):Er³⁺/Yb³⁺ phosphors were successfully prepared to investigate the temperature sensing property. By establishing energy transfer from Yb³⁺ to Er³⁺ and regulating the local lattice environment, up-conversion luminescence of Er³⁺ is dramatically improved when excited by 980 nm laser. This can effectively promote signal-noise ratio and reduce the errors in temperature detection. Furthermore, a multi-mode optical thermometry, which includes the fluorescence intensity ratio (FIR) from two thermally coupled levels of ²H_11/2/⁴S_3/2, FIR based on non-thermally coupled system of ²H_11/2/⁴F_9/2 and fluorescence lifetime of ⁴S_3/2 state of Er³⁺, was explored systematically. The fabricated samples exhibit the superior temperature measurement performances containing wide temperature-sensing range, superior signal discriminability, high sensitivity and favorable repeatability, indicative of the enormous utilization prospects of B_3-xS_xLO:Er³⁺/Yb³⁺ for thermometry.     

Locating wind farm for power and hydrogen production based on Geographic information system and multi-criteria decision making method: An application

Hydrogen generation from renewable energy resources is considered as a suitable solution to solve the problems related to the energy sector and the reduction of greenhouse gases. The aim of this study is to provide an integrated framework for identifying suitable areas for the construction of wind farms to produce hydrogen. For this purpose, a combined method of Geographic Information System (GIS) and multi-criteria decision making (MCDM) has been used to locate the power plant in Yazd province. The GIS method in the present study consisted of two parts: constraints and criteria. The constraint section included areas that were unsuitable for the construction of wind farms to produce power and hydrogen. In the present study, various aspects such as physical, economic and environmental had been considered as constraints. In the criteria section, eight different criteria from technical aspects (including average wind speed, hydrogen production potential, land slope) and economic aspects (including distance to electricity grid, distance to urban areas, distance to road, distance to railway and distance to centers of High hydrogen consumption) had been investigated. The MCDM tool had been used to weigh the criteria and identify suitable areas. Analytic Hierarchy Process (AHP) technique was used for weighting the criteria. The results of AHP weighting method showed that economic criteria had the highest importance with a value of 0.681. The most significant sub-criterion was the distance to urban areas and the least significant sub-criterion was the distance to power transmission lines. The results of GIS-MCDM analysis had shown that the most proper areas were in the southern and central sectors of Yazd province. In addition, the feasibility of hydrogen production from wind energy had shown that this province had the capacity to generate hydrogen at the rate of 53.6–128.6 tons per year.     

基于卷积神经网络的5G蜂窝网络无线定位方法

5G蜂窝网络发展迅猛，其覆盖面积将逐渐增大，因此使用5G蜂窝网络进行定位是有研究潜力的研究方向。本文提出一种新的深度学习技术来实现高效、高精度和低占用的定位，以代替传统指纹定位过程中繁重的指纹库生成以及距离计算。该方法建立了一个特殊的卷积神经网络，并根据5G天线信号的接收信号强度指示、相位和到达角等特征量，选择合适的输入数据格式构造样本组建训练集，对该卷积神经网络进行训练。训练得到的卷积神经网络可以替代指纹定位中的庞大指纹库，非常有利于直接在5G移动设备端实现定位。虽然卷积神经网络在训练过程中需要大量时间，但在训练完毕后直接进行分类定位的速度非常快，可以保障定位实现的实时性。本文所实现的卷积神经网络权重与偏置所占内存不到0.5 MB，且能够在实际应用环境中以95%的定位准确率以及0.1 m的平均定位精度实现高精度定位。     

水-油连续螺旋折流板换热器热力性能研究

利用计算流体力学(Computational Fluid Dynamic, CFD)方法，针对连续螺旋折流板换热器建立物理模型和数学模型，在管侧介质为水和壳侧介质为原油条件下，研究不同原油流量及螺旋角对螺旋折流板换热器内部流场、换热性能及阻力性能的影响，并拟合了水油换热时螺旋折流板换热器的Nu、f与Re的关联式。结果表明：22°螺旋角的螺旋折流板换热器与其它较小螺旋角换热器对比，壳侧压降和换热系数逐渐减小，综合换热性能最佳。通过对壳侧原油为层流状态下的阻力系数和对流换热系数关系式进行拟合，更好地指导水-油连续螺旋折流板换热器的热力设计。     

Prediction of mode I fracture toughness of rock using linear multiple regression and gene expression programming

Prediction of mode I fracture toughness (K_IC) of rock is of significant importance in rock engineering analyses. In this study, linear multiple regression (LMR) and gene expression programming (GEP) methods were used to provide a reliable relationship to determine mode I fracture toughness of rock. The presented model was developed based on 60 datasets taken from the previous literature. To predict fracture parameters, three mechanical parameters of rock mass including uniaxial compressive strength (UCS), Brazilian tensile strength (BTS), and elastic modulus (E) have been selected as the input parameters. A cluster of data was collected and divided into two random groups of training and testing datasets. Then, different statistical linear and artificial intelligence based nonlinear analyses were conducted on the training data to provide a reliable prediction model of K_IC. These two predictive methods were then evaluated based on the testing data. To evaluate the efficiency of the proposed models for predicting the mode I fracture toughness of rock, various statistical indices including coefficient of determination (R²), root mean square error (RMSE), and mean absolute error (MAE) were utilized herein. In the case of testing datasets, the values of R², RMSE, and MAE for the GEP model were 0.87, 0.188, and 0.156, respectively, while they were 0.74, 0.473, and 0.223, respectively, for the LMR model. The results indicated that the selected GEP model delivered superior performance with a higher R² value and lower errors.     

某型柴油机水泵、机油泵间隙调整工装的应用

为了方便某柴油机前端水泵和机油泵齿轮间隙的调整,改变以前传统的调整方法,通过长期在装配现场的观察和了解,设计出某柴油机前端水泵和机油泵齿轮间调整工作,经现场使用验证;该工装安全、小巧轻便精度高,改善了装配的劳动强度和装配质量。     

A novel and sensitive colorimetric detection of PABA by asymmetrically functionalized TA-AuNPs-PEG-FITC based on oriented aggregation

A colorimetric assay based on the oriented TA-AuNPs-PEG-FITC for rapid and sensitive PABA detection was proposed. Initially, the negatively charged TA modified on the surface of AuNPs enabled rapid binding to PABA due to the electrostatic interaction and hydrogen bond, resulting in a visible color change. However, particles were aggregated in a non-oriented way, leading to an unstable testing system which failed to realize the accurate quantification. Thus, the asymmetrically functionalized TA-AuNPs-PEG-FITC were prepared, in which the stabilizer agent of HS-PEG-FITC was attached to the specific sites on the surface of TA-AuNPs. Such a way of modification resulted in an oriented aggregation manner, the addition of PABA induced the formation of oligomers. Moreover, the introduction of FITC group acted as fluorescent marker, providing a simple, fast and quantitative method for characterization of PEG chain. The molar ratio between TA-AuNPs and modified PEG-FITC was further determined. A linear regression was established in a wide range from 10 μM to 1 mM with the LOD of 6.9 μM. Finally, the sensor was successfully applied in the health food. This was the first example in which TA-AuNPs-PEG-FITC were fabricated for colorimetric detection of PABA, and an indirect method based on fluorescence marker was well used to quantify the content of PEG chain.