Study on the double-logarithmic profile of tidal flow velocity in the near-bed layers

Tidal current velocity profile in the near-bed layers has been widely studied. The results showed that velocity profile in the near-bed layer obviously departure from the traditional logarithmic profile, due to the acceleration or deceleration. Although the logarithmic linear profile can reduce the rate of deviation from this, only it is a lower-order approximate solution. In this paper, considering the unsteady and non-linear features of tidal motion, the double logarithmic profile near-bed layers in estuarine and coastal waters is established on the assumption that the turbulent shear stress along the water depth was parabolic distribution, and on the basis of Prandtl＇s mixing length theory and yon Karman＇s self-similar theory. Having been verified the data observed at the West Solent in the south of England, and comparison of the logarithmic linear profile, it found that the double logarithmic profile is more precious than the latter. At last, the discussed results showed that： （1） The parabolic distribution of the tidal shear stresses verified good by the field data and experimental data, can be better reflected the basic features of the tidal shear stress deviating from linear distribution that is downward when to accelerate, upward when to decelerate. （2） The traditional logarithmic velocity profile is the zero-order approximation solution of the double logarithmic profile, the logarithmic linear profile is the first order, and the logarithmic parabolic profile is the second order. （3） Ignoring the conditions of diffusion and convection in the tida movement, the double logarithmic profile can reflect the tidal properties of acceleration or deceleration, so that the calculation of the friction velocity and roughness length are more reasonable. When the acceleration or the deceleration is about zero, the double logarithmic profile becomes the logarithmic profile.

Hydrogen Purification Performance of Pressure Swing Adsorption Based on Cu-BTC/zeolite 5A Layered Bed

A pressure swing adsorption (PSA) hydrogen purification model for the four-component gas (H_(2)/CO_(2)/CH_(4)/CO=73/16/8/3 mol%) in a layered bed packed with Cu-BTC and zeolite 5A was established to achieve better hydrogen purification performance.By comparing its simulation results with the experimental data,the adsorption isotherm model was validated and could be used to accurately describe the adsorption process of the gas mixture on the two adsorbents.The breakthrough curves of the mixed gas on the layered bed were studied to verify the correctness of the established simulation models.Based on the validated model,the performance of the PSA system based on the layered bed was carried out,including the hydrogen purity and recovery.The simulation results show that the hydrogen purification system based on the layered bed model can achieve hydrogen purity of 95.469% and hydrogen recovery of 83.219%.Moreover,a parametric study was carried out and its results show that reductions in feed flow rate and adsorption time result in an increase in hydrogen purity and a decrease in hydrogen recovery.A longer equalization time between the two adsorption beds can simultaneously increase the hydrogen purity and recovery.

Penetration Depth of Torpedo Anchor in Two-Layered Cohesive Soil Bed by Free Fall

The penetration depth of torpedo anchor in two-layered soil bed was experimentally investigated. A total of 177 experimental data were obtained in laboratory by varying the undrained shear strength of the two-layered soil and the thickness of the top soil layer. The geometric parameters of the anchor and the soil properties(the liquid limit, plastic limit, specific gravity, undrained shear strength, density, and water content) were measured. Based on the energy analysis and present test data, an empirical formula to predict the penetration depth of torpedo anchor in two-layered soil bed was proposed. The proposed formula was extensively validated by laboratory and field data of previous researchers. The results were in good agreement with those obtained for two-layered and single-layered soil bed.Finally, a sensitivity analysis on the parameters in the formula was performed.

Research on reservoir bed heterogeneity,interlayers and seal layers and controlling factors of 2+3 sands of upper second member,Shahejie Formation,in the west of the Pucheng Oilfield

Terminal fans have formed the sedimentary system of the 2＋3 sands of the upper second member, Shahejie formation in the west of the Pucheng Oilfield, Bohai Bay Basin, East China. Based on well logging data and physical properties of the reservoir beds, the 2＋3 sands were divided into 16 sublayers. The heterogeneity of reservoir beds and distribution of interlayers and seal layers in the 2＋3 sands were investigated. The intra-layer heterogeneity and inter-layer heterogeneity primarily belong to the severely heterogeneous classification. The spatial differentiation of sedimentary microfacies resulted in a change of reservoir bed heterogeneity, strong in the middle and southern parts, weak in the northern part. Spatial distribution of interlayers and seal layers is dominated by sedimentary microfacies, and they are thick in north-eastern and middle parts, thin in the south-western part.

Concept of Bed Roughness Boundary Layer and Its Application to Bed Load Transport in Flow with Non-Submerged Vegetation

Ecosystem conservation has become one of the purposes in river management as well as flood mitigation and water resources management, and understanding of river flow and morphology in a stream with vegetation becomes important. Recently 2D depth averaged analysis is familiar even in a stream with vegetation by taking account of form drag due to vegetation. However, the shear stress in vegetated area is not properly described because the resistance law due to bed roughness is not reasonably modified in vegetated area. In this study, we discussed the bed roughness boundary layer in flow with non-submerged vegetation to deduce a reasonable relation between U and u* in vegetated area toward improving the analysis of sediment transport. The results show that the modification of resistance law using by thickness, velocity distribution in that layer was found to bring significant improvement of accurate estimation of shear velocity and subsequently the sediment transport. The proposed modification is improved by 2D depth averaged analysis based on this concept, and its application is certificated through flume experiment.

Mechanics Principle and Engineering Application of Split Layer and Bed Separation of Mining Overburden

To control land surface subsidence caused the underground mineral exploitation and the catastrophic phenomena such as serious damage of buildings, waterbodies, cultivated lands, railways, bridges caused by land subsidence, bed separation grouting technology of overburden is put forward. To provide theoretical support for the technology, the characteristics and the mechanics mechanism of mining overburden from layer-split to formation of bed separation are studied. On the basis of elastic sheet board theory, calculation formula of rock sheet deflection is presented, and the mechanics criteria of the separation formation and the calculation formula of bed separation volume are set up. Finally, the applications and technics of bed separation grout technology of mining overburden to control land subsidence in china are introduced.

超高料层双层烧结富氧强化及烟气排放行为研究

针对超高料层双层烧结矿强度低的问题,采用富氧方法强化双层烧结。研究富氧浓度和燃料用量对烧结矿产质量的影响,分析普通双层烧结和富氧强化双层烧结的烧结矿主要矿物组成和微观结构,研究两者烧结烟气中O_(2)、CO_(2)和CO的排放行为。研究结果表明:富氧方法能明显强化超高料层双层烧结,大幅度提高烧结矿成品率和转鼓强度;二次点火后对料层进行富氧,氧气体积分数为25%,烧结矿成品率、转鼓强度、利用系数和固体燃耗分别为69.06%、66.40%、2.09t/(m^(2)∙h)和53.79kg/t,与普通双层烧结指标相比,成品率、转鼓强度和利用系数分别提高4.11%、7.73%、0.18t/(m^(2)∙h),固体燃耗降低3.23kg/t;富氧使烧结矿中磁铁矿氧化充分,铁酸钙大量生成,烧结矿结构均质、紧密;富氧增大烧结烟气O_(2)质量分数,可有效解决下部料层缺氧问题,提高燃料燃烧效率,减少CO排放量。

基于多层残差网络的地震提频处理在薄储集层识别中的应用

基于多层残差网络的地震提频处理方法,通过智能化网络将测井高频信息与地震数据相结合,能有效提升纵向分辨率,保持横向连续可追踪,利于薄储集层识别。针对AMH地区常规处理的地震数据仅能识别厚度大于30 m的碳酸盐岩层,无法有效识别厚度较小的薄储集层的问题,提出基于多层残差网络的地震提频处理方法,以井旁地震振幅作为训练数据,测井相对波阻抗作为训练标签,利用深度学习网络多层残差网络开展训练,获取相对波阻抗曲线的预测模型;通过将地震数据作为输入,利用深度网络训练模型计算得到相对波阻抗数据体,进而得到提频后的地震数据体相对应的反射系数体。通过对靶区地质情况的分析认识,对宽频子波进行标定后提取合适的宽频子波,与反射系数体进行褶积,得到提频后的地震数据体;利用提频后的地震数据体开展储集层反演,反演结果纵向具有较高分辨率,与主要目的层能够较好匹配,横向可以进行识别和追踪,利用高分辨地震数据反演结果实现AMH地区的薄储集层识别。结果表明,通过基于多层残差网络的地震提频处理及相应的高分辨模型反演,在AMH地区能够识别厚度大于10 m的薄储集层,较好地解决由于地震分辨率低无法识别薄储集层的问题,有效提高了薄储集层预测的精度,对同类型薄储集层识别具有借鉴意义。

层状岩石不排气三轴压缩力学特性试验研究

为研究地下隧洞开挖过程中围压和孔隙气压对层状千枚岩力学特性及变形参数的影响,以氩气作为渗透介质,开展层状千枚岩不排气三轴压缩试验,分析层状千枚岩在不同围压和孔压下应力-应变关系、峰值强度、变形特性及破坏形式随层理倾角的演化特征。引入基于层理倾角的各向异性度公式,探讨围压和孔压对层状千枚岩各向异性的影响。结果表明:不排气条件下,当孔压减小或围压增大时,层状千枚岩峰值强度逐渐增大;岩石峰值强度σc、弹性模量及变形模量随层理倾角的增大呈“U”型变化;层理倾角在30°~60°之间,层状千枚岩存在层理弱面,破坏形式主要为沿层理面剪切滑移破坏;层状千枚岩在平行层理方向受围压、孔压影响较大,呈现明显各向异性特征。

运营地铁盾构隧道基底沉降的影响因素分析

隧道基底沉降不仅影响地铁列车的正常运行和乘客的舒适性,严重时会造成隧道结构病害,目前的研究主要集中在长期沉降预测和单因素影响分析,非常有必要开展隧道基底沉降的多影响因素分析。以郑州地铁1号线某盾构隧道区间为工程实例,构建三维有限元数值模型,采用人工激振力模拟地铁列车竖向荷载,提取数值模拟结果的动应力和静偏应力数据,引入循环荷载作用下累积塑性应变计算公式,采用分层总和法计算得到隧道基底沉降,研究了隧道周围土层性质、道床脱空深度和地铁列车运行速度等因素对隧道基底沉降的影响,研究结果表明:数值模拟的隧道基底沉降和发展规律与现场实测结果具有较高的吻合度,验证了有限元模拟的准确性;隧道基底沉降随着周围土层砂粒含量的提高而减小;道床脱空尺寸会加剧隧道和道床板中应力集中和振动放大现象,增大隧道下卧土层的动偏应力和基底沉降;提高车速会增大基底沉降的横向影响范围;采用正交试验法、极差分析法和方差分析法得到了隧道沉降对各因素的敏感性,从大到小依次为:土层性质、车速和道床脱空,其中,土层性质为高度显著水平、车速为显著水平。研究成果对运营地铁盾构隧道的变形监测、安全评估和加固处理具有一定的参考价值。

公立医院床位利用效率及配置合理性评估研究

目的分析上海市某三级甲等公立医院各科室床位利用效率,为评估床位资源配置合理性提供方法学依据。方法以上海市某三级甲等医院2023年的医疗运营数据为基础,利用床位利用模型进行可视化呈现,评价床位资源的利用效率。运用床位评价指标测算各科室床位的合理区间,得出床位调整方案。采用多层感知器神经网络模型评估床位调整方案的准确性、合理性、可行性。结果床位利用模型显示,11个(25.00%)科室属于床位效率型,11个(25.00%)科室属于床位周转型,16个(36.36%)科室属于床位闲置型,6个(13.64%)科室属于压床型。床位评价指标显示,8个科室床位数不需改变,16个科室床位数需要适当减少,20个科室床位数需要结合实际情况增加。利用多层感知器神经网络搭建床位不变、床位减少、床位增加模型。床位不变模型的受试者工作特征曲线下面积(area under curve,AUC)=0.719,灵敏度为100.00%,特异度为40.63%。床位减少模型的AUC=0.875,灵敏度为83.33%,特异度为85.00%。床位增加模型的AUC=0.913,灵敏度为100.00%,特异度为72.22%。结论医院整体床位利用效率较低且不同科室间床位的利用效率存在差异,通过多层感知器神经网络建立的床位增加模型评估结果与床位利用模型和床位评价指标的结果具有较好的一致性,能够为医院床位资源配置管理提供方法学依据,进而实现医院床位精细化管理。

铁路基床底层风积沙填料长期动力稳定性研究

为了研究铁路基床底层风积沙填料的长期动力稳定性,以和若铁路某试验段路基为研究对象,开展现场动力响应试验,试验车速分别为5,20和30 km/h,轴重分别为14.5 t和23.5 t,分析动应力随列车速度、轴重及沿深度的变化规律,基于现场测试和以往动三轴试验成果,将临界动应力和累积塑性变形作为评价参数,分别从动强度和动变形2个方面评价和若铁路基床底层风积沙填料的长期动力稳定性。研究结果表明:1)当列车以不大于30 km/h的速度运行时,车速对基床动应力值的影响很小,但轴重的影响十分显著,不同轴重作用下动应力衰减系数沿深度的变化曲线基本重合,动应力经过基床表层衰减约39.7%,传递至基床底层底面衰减约84.6%。2)在和若铁路基床底层范围内,列车荷载产生的动应力为12.86~53.05 kPa,小于风积沙临界动应力66.02~100.21 kPa,从动强度角度来说,风积沙用作铁路基床底层填料满足长期动力稳定性要求。3)基于基床填料的累积塑性应变模型,采用分层总和法计算了和若铁路基床层的累积塑性变形,结果发现列车荷载作用下基床变形主要集中在第1个月,累积变形量为13.59 mm,小于规范允许的月沉降量25 mm,从动变形角度来说,风积沙用作铁路基床底层填料满足长期动力稳定性要求。研究成果可为沙漠地区路基填料选择及基床结构设计提供参考。

干气制乙苯装置烷基化催化剂快速失活原因分析

介绍了中国石油化工股份有限公司安庆分公司干气制乙苯烷基化催化剂快速失活情况,讨论了快速失活的原因,分析了原料干气或苯中碱性物质的来源以及对催化剂的影响,提出了碱性物质以外的杂质也会影响催化剂活性的观点。实验分析表明,催化装置干气除含有氨气外,还存在未知氮化物。工业试验结果表明:来自于催化装置以外的尾气,可显著影响烷基化催化剂的活性;将成分复杂的尾气和部分干气改出系统后,催化剂活性可以保持长时间稳定。生产中进行了水洗系统改造、改出成分复杂的尾气、加强上下游装置沟通,烷基化催化剂实际使用寿命大幅超出正常使用寿命。

激光粉末床熔融纯钼组织及性能研究

钼作为一种难熔金属,由于其具有良好的高温力学性能和低膨胀系数而被广泛应用于核工业及航空航天。使用激光粉末床熔融(LPBF)制备的纯钼有着显著的设计优势和工业生产效率。为了提高LPBF生产效率,通过工艺优化,获得了30μm层厚选区激光熔化技术的最优工艺参数,制备出致密度为99.2%的无裂纹纯钼样品。经过XRD和EBSD表征发现,不同参数下纯钼样品均存在择优取向以及不同程度的晶格畸变,样品侧面织构强度大于底面。最优样品硬度为206HV,单向压缩强度和伸长率分别为566MPa和20.7%。该研究为LPBF制备30μm层厚的无裂纹且性能优异的纯钼构件奠定了基础。

对硫酸装置二氧化硫转化系统设计的初探

当进转化器气体中φ(SO_(2))<5.5%时,不建议采用二转二吸工艺。模拟了进转化器气体中不同的二氧化硫浓度下需采用“3+2”转化工艺的临界氧含量。对转化换热流程的选取进行了分析,指出当进转化器气体中φ(SO_(2))≤6.5%时,建议采用ⅣⅠ-ⅢⅡ换热流程,并指出了该流程的缺点。建议对含一氧化碳的二氧化硫气体进行转化计算时,考虑65%左右的一氧化碳在一段床层发生转化。提出了转化器催化剂床层进气温度选择的原则及方法,针对转化设备、管道的设计选材和转化系统散热量的选取等问题进行了探讨。

某项目顺层边坡的稳定性计算分析与失稳预防处置

顺层边坡是山区公路建设中常见的一种不良地质,而且由于软弱结构层的存在,其具有比普通边坡更复杂的地质破坏模式,施工过程中在外力的扰动下极易发生失稳。因此,为了减少顺层边坡施工过程中的失稳破坏,提前对边坡采取了有效的预防措施,即:通过对已滑移段顺层边坡进行反演,计算得到了滑体结构面的相关参数;再根据计算所得结构面参数,模拟分析未滑移段顺层边坡的稳定性,确定了边坡支护所需的剩余下滑力;最后提出了针对性预防措施并加以实施,最终提高了边坡的稳定性。该方法能够在边坡发生较小范围破坏时,模拟获得稳定性参数,并对顺层边坡进行处理;同时可为相同地质条件的边坡防护提供参考,以避免更大范围的边坡失稳破坏,达到防患于未然的目的。

市政道路水泥稳定碎石基层双层连铺施工技术分析

本文以市政道路水泥稳定碎石基层施工为对象进行研究,结合某市政道路施工案例,对水泥稳定碎石基层双层连铺施工技术要点进行分析,包括施工材料选择和检测、材料配置和运输以及路面混合料的摊铺碾压等,并且顺利完成本次市政道路施工任务,达到了预期施工目标,可供相关人员参考。

环氧沥青钢桥面铺装施工技术分析

该文以清云高速公路肇云大桥的钢桥面铺装工程为例,探究环氧沥青混凝土的铺装工艺及技术要点。正式铺装前需要做好钢桥面的喷砂除锈和清洁处理,营造良好的铺装环境。然后,洒布黏结层和喷涂环氧富锌防锈漆。拌和环氧沥青混凝土,由运输车将混合料从拌和站运送到施工现场完成摊铺后,分别进行初压、复压、终压,保证摊铺料的密实度达标。最后,根据天气情况确定养护时间,养护完毕后开放通车。

提高辊压机做功能力的影响因素分析

水泥工业广泛采用辊压机作为粉磨系统的预粉碎设备,辊压机的高效做功成为业内关注的重点,通过分析辊压机喂料阀及辊面、侧挡板间隙、辊缝、辊压机工作压力、中间仓和喂料溜子、V型选粉机、熟料粒径等对辊压机做功的影响,提出了优化改进措施,以保证辊压机料床挤压稳定运行,维持做功电流在额定电流的90%±5%,提高辊压机做功效率。

Estimation of Bed Shear Stresses in the Pearl River Estuary

Mean and fluctuating velocities were measured by use of a pulse coherent acoustic Doppler profiler （PC-ADP） and an acoustic Doppler velocimeter in the tidal bottom boundary layer of the Pearl River Estuary. The bed shear stresses were estimated by four different methods： log profile （LP）, eddy correlation （EC）, turbulent kinetic energy （TKE）, and inertial dissipation （ID）. The results show that （a） all four methods for estimating bed stresses have advantages and disadvantages, and they should be applied simultaneously to obtain reliable frictional velocity and to identify potential sources of errors; （b） the LP method was found to be the most suitable to estimate the bed stresses in non-stratified, quasi-steady, and homogeneous flows; and （c） in the estuary where the semi-diurnal tidal current is dominant, bed shear stresses exhibit a strong quarter-diurnal variation.