Simultaneous measurement of velocity profile and liquid film thickness in horizontal gas–liquid slug flow by using ultrasonic Doppler method

Horizontal gas-liquid two-phase flows widely exist in chemical engineering,oil/gas production and other important industrial processes.Slug flow pattern is the main form of horizontal gas-liquid flows and characterized by intermittent motion of film region and slug region.This work aims to develop the ultrasonic Doppler method to realize the simultaneous measurement of the velocity profile and liquid film thickness of slug flow.A single-frequency single-channel transducer is adopted in the design of the field-programmable gate array based ultrasonic Doppler system.A multiple echo repetition technology is used to improve the temporal-spatial resolution for the velocity profile.An experiment of horizontal gas-liquid two-phase flow is implemented in an acrylic pipe with an inner diameter of 20 mm.Considering the aerated characteristics of the liquid slug,slug flow is divided into low-aerated slug flow,high-aerated slug flow and pseudo slug flow.The temporal-spatial velocity distributions of the three kinds of slug flows are reconstructed by using the ultrasonic velocity profile measurement.The evolution characteristics of the average velocity profile in slug flows are investigated.A novel method is proposed to derive the liquid film thickness based on the instantaneous velocity profile.The liquid film thickness can be effectively measured by detecting the position and the size of the bubbles nearly below the elongated gas bubble.Compared with the time of flight method,the film thickness measured by the Doppler system shows a higher accuracy as a bubble layer occurs in the film region.The effect of the gas distribution on the film thickness is uncovered in three kinds of slug flows.

Forming process chain for manufacturing complex conical-section profiled rings:On a co-design method

The final quality of complex conical-section rings depends on co-design of multiple processes in forming process chain.In this study,for a complex aeroengine casing ring with a large slope and a flange on its end,a co-design method of the forming process chain is put forward towards the objective of precision forming,which not only proposes a standard process route composed of multiple processes of upsetting,punching,rectangular ring rolling,loose tooling forging and profiled ring rolling,but also presents co-design methods of dies and blanks for all the processes.For profiled ring rolling,a design method of preformed blank that makes the blank and the target conical-section ring have the same axial volume distribution is proposed.By the method,the axial metal redistribution during the process can be alleviated greatly thus improving the forming stability and precision of the ring.Based on the geometric features of designed preformed blank,design methods of blanks and dies for loose tolling forging,rectangular ring rolling,punching and upsetting are proposed sequentially.In view of the key roles of loose tooling forging(manufacturing the preformed blank)and profiled ring rolling on the final quality of the conical ring parts,inherited FE simulations for these two processes are performed to verify the proposed design methods and determine appropriate design parameter.It is demonstrated that the proposed design method has significant advantages in improving forming precision.Besides,a suggestive value 1.5 of the rolling ratio for profiled ring rolling(a key design parameter)is given based on comprehensive consideration of multiple indicators such as ring roundness,deformation uniformity and forming load.The corresponding industrial experiments performed illustrate that a high forming precision of the conical-section aeroengine casing ring is achieved.

Investigation of the Aroma Profile of Green Tea Leaves Using Organic Synthesis and Conventional Analytical Techniques

Although many aroma components have been identified in green tea leaves, the aroma compounds contributing to green tea＇s characteristic odor have not yet been reported. The authors recently reported that aroma components with a matcha-like odor are present in both green tea and black tea prepared from the Sayamakaori tea cuttivar. This matcha-like odor is similar to the odor of commercial available matcha （high-quality powdered green tea）, and is a specific odor feature of green tea leaves. At present, the green-tea odor is thought to arise from the combination of a large number of constituents. Recent reports indicate that a complex interaction between olfactory receptors and odorants is important for the evaluation of the odors. Taking into consideration these findings, the authors investigated the aroma profile of green tea, focusing on the characteristic molecular structures of the constituents that give matcha-like odor. Using a combination of organic synthesis and gas chromatography-mass spectrometry plus gas chromatography-olfactometry, the authors identified aroma components with matcha-like odors in five other tea cultivars. This investigation also revealed that several compounds with a formyl group were important constituents of the aroma of green tea leaves, although the odor of each constituent was not individually similar to the tea＇s overall aroma. The authors found for the first time a group of key components that have the matcha-like odor.

Dim Moving Small Target Detection by Local and Global Variance Filtering on Temporal Profiles in Infrared Sequences

In this paper, the temporal different characteristics between the target and background pixels are used to detect dim moving targets in the slow-evolving complex background. A local and global variance filter on temporal profiles is presented that addresses the temporal characteristics of the target and background pixels to eliminate the large variation of background temporal profiles. Firstly, the temporal behaviors of different types of image pixels of practical infrared scenes are analyzed.Then, the new local and global variance filter is proposed. The baseline of the fluctuation level of background temporal profiles is obtained by using the local and global variance filter. The height of the target pulse signal is extracted by subtracting the baseline from the original temporal profiles. Finally, a new target detection criterion is designed. The proposed method is applied to detect dim and small targets in practical infrared sequence images. The experimental results show that the proposed algorithm has good detection performance for dim moving small targets in the complex background.

Zircon age depth-profiling sheds light on the early Caledonian evolution of the Seve Nappe Complex in west-central J?mtland

The Scandinavian Caledonides comprise nappe stacks of far-travelled allochthons that record closure of the Iapetus Ocean and subsequent continental collision of Baltica and Laurentia.The Seve Nappe Complex(SNC)of the Scandinavian Caledonides includes relics of the outermost Baltoscandian passive margin that were subducted to mantle depths.The earliest of the deep subduction events has been dated to ca.500-480 Ma.Evidence of this event has been reported from the northern exposures of the SNC.Farther south in the central and southern segments of the SNC,(ultra)high-pressure rocks have yielded younger ages in the range of ca.470-440 Ma.This study provides the first record of the early Caledonian event in the southern SNC.The evidence has been obtained by depth profiling of zircon grains that were extracted from the Tv?r?klumparna microdiamond-bearing gneiss.These zircon grains preserve eclogite facies overgrowths that crystallized at 482.6±3.8 Ma.A second,chemically-distinct zircon overgrowth records granulite facies metamorphism at 439.3±3.6 Ma,which corroborates previous geochronological evidence for granulite facies metamorphism at this time.Based on these results,we propose that the entire outer margin of Baltica was subducted in the late Cambrian to early Ordovician,but the record of this event may be almost entirely eradicated in the vast majority of lithologies by pervasive late Ordovician to early Silurian metamorphism.

复杂地形对风速廓线的影响

随着风电利用的发展,越来越多的风电场建立在复杂地形的山区,为了更好地进行风能评估和风电预报,就需要了解复杂地形对风速廓线的影响。本文基于薄翼理论和湍流边界层扰动的线性化理论,采用两层模型对坡度较小的山地在其二维横截面上的风廓线进行了预测,该模型能够较为准确地预报地形、压力、稳定度对风速增速的影响,但对于三维地形或其他因素产生的风速的复杂变化,需要进一步将其扩展至三维,并结合数值模拟进行研究。

基于混合模型的复杂舰载信息系统可靠性测试技术

复杂舰载信息系统在未来海战场战争中扮演着至关重要的角色,必须在未来更加复杂多变的战场环境下保持稳定可靠的性能。面对未来更加复杂多变的战场环境,软件可靠性测试面临众多挑战。现有的软件可靠性测试理论难以满足复杂舰载信息系统任务繁多、状态多样、交互复杂的特点,并且缺乏有效的测试数据生成手段。为了解决这个问题,结合Musa方法和Markov链模型思想来构建操作剖面,并生成可靠性测试用例。将操作剖面模型定义的使用用例集和Markov链表示的状态迁移模型相结合,生成测试用例。通过实例分析和对比实验,采用混合模型生成的测试用例集具备良好的稳定性,并且能够满足复杂舰载信息系统可靠性测试的需求。

考虑大气稳定度的典型复杂地形风场CFD模式

为评估中国典型复杂山地风资源,实现风资源的高效利用,结合雷诺时均的k-ε两方程模型、大气粗糙度壁面函数和热浮力作用,提出能模拟不稳定、中性和稳定状态复杂地形风场特性的大气CFD模式,并针对湍流参数、大气粗糙度对风速廓线的影响进行参数化研究。采用两种方式驱动CFD模式:一种是通过来流上游的实测风速廓线驱动CFD模式,一种是通过WRF模式输出风速廓线和温度廓线驱动CFD模式。利用山西神池南桦山丘陵山地测风数据进行大气CFD模式验证,通过WRF-CFD耦合仿真研究山地公里级范围热浮力作用对风场的影响,详细对比不同热浮力作用下的大气CFD模式仿真精度。结果表明大气CFD模式能准确地模拟不同稳定度状态下的山区大气风环境,但对于不稳定状态下山后风场的模拟能力稍差。

复杂型面结构超声成像检测研究进展

工程结构普遍具有复杂型面,而且此类区域是制造和服役阶段损伤甚至失效的高发区。超声无损检测是评估结构制造质量和服役安全性的重要手段,但复杂型面给超声检测带来了声耦合困难、随形扫描控制难、超声入射/接收难、超声传播行为复杂等挑战。本文分别从超声耦合策略、超声换能器、随形扫描控制、复杂型面轮廓重建、成像算法、复杂型面与材料复杂耦合的影响几大方面,概述了现有研究已取得的重要进展。最后探讨了复杂型面超声成像检测研究仍面临的挑战以及未来发展趋势,包括超复杂型面三维异形结构检测、高柔性二维阵列超声换能器、以及同时考虑宏/微观结构和材料自身声学特性的影响改进超声成像算法。

棉铃虫BR‑C Z1基因的克隆及表达谱分析

广泛锌指复合物(BR‐C)在棉铃虫Helicoverpa armigera的生长发育过程中有重要作用。基于转录组数据通过PCR克隆获得棉铃虫BR‑C Z1(HaBR‑C Z1)基因序列,利用生物信息学分析其氨基酸序列,利用qRT-PCR分析基因的表达规律,以及2-十三烷酮(2‐TD)处理后基因的表达情况。结果显示,HaBR‑C Z1基因的开放阅读框长1284 bp,编码427个氨基酸,预测编码蛋白的分子量和等电点分别为47.41 kD和7.72。系统进化树显示,HaBR‐C Z1与帝王斑蝶Danaus plexippus plexippus的亲缘关系最近。HaBR‑C Z1基因在预蛹期和6龄幼虫肠组织中的相对表达量最高。20 mg·g^(−1)浓度2-TD处理后的相对表达量在6 h达到峰值,为对照组的24.7倍。本研究明确了HaBR‑C Z1基因的表达规律及其对2-TD的响应,为深入了解棉铃虫生长发育机制奠定了基础,并为害虫防治提供依据。

高锰钢辙叉自动打磨生产线控制系统研发

高锰钢辙叉工件因目标型面结构复杂,所以打磨技术难度大、人工作业强度高,最终导致打磨质量低、覆盖率低等痛点问题。针对自动打磨生产线的多兼容、柔性化特点,开发的控制系统可实现对高锰钢辙叉工件的自动输送、自动识别及定位、浮动打磨、多工具头切换、打磨质量检测、打磨区域可视化等功能,进一步实现对高锰钢辙叉工件复杂型面的自适应打磨。这个系统在生产实例中得到了验证和应用,有效提高了辙叉复杂型面自动打磨的覆盖率、质量和综合生产效率,降低了人工劳动强度和工作量。

融合SOM神经网络与K-means聚类算法的用户信用画像研究

为提高现阶段基于K-Means聚类算法的用户信用画像模型的准确性和实时性,提出一种融合自组织映射(SOM,Self-Organizing Map)神经网络与K-Means聚类算法的改进方法。通过SOM对用户数据进行降维和特征提取,直接获得最优聚类数目后再用K-Means算法进行聚类分析。通过真实在线借贷平台数据对所提方法进行验证,结果表明,该方法可提升用户信用画像分析的质量,更好地满足金融数据分析中对实时管理和风险控制的要求,为金融机构提供精准的决策支持。

大型压裂技术在苏里格气田开发中的优化应用

为实现苏里格区块难采储量的有效动用,对以往大型压裂技术进行优化升级,压裂液体系由胍胶交联冻胶压裂液升级为“滑溜水+线性胶+胍胶压裂液冻胶”变黏度复合压裂液,支撑剂选用中密度高强度40/70目+20/40目陶粒组合,通过裂缝支撑剖面模拟和优化压裂施工参数,在保障施工安全的前提下,设计施工排量可满足8.0~9.0 m 3/min,形成了适合苏里格气田大型压裂技术。现场应用表明,大型压裂技术采用大排量、大液量、大砂量造复杂裂缝,加大了储层的渗透率,增加了气体可动区域,用液强度平均增大99%,加砂强度平均增大97%,日产气平均增加101.3%,取得了较好的增产效果,为后续该类区块的开发起到较好的借鉴和指导作用。

Alginate-based complex fibers with the Janus morphology for controlled release of co-delivered drugs

Hydrogels are soft materials consisting of a three-dimensional network of polymer chains.Over the years,hydrogels with different compositions have been developed as drug carriers for diverse biomedical applications,ranging from cancer therapy and wound care to the treatment of neurodegenerative and inflammatory diseases.Most of these carriers,however,are designed only to deliver single agents.Carriers based on hydrogels for co-delivery of multiple agents,with the release rate of each of the co-delivered agents tunable,are lacking.This study reports a one-pot method of fabricating alginate-based complex fibers with the Janus morphology,with carboxymethyl cellulose sodium functioning as a polymeric modifier of the properties of each of the fiber compartments.By using malachite green and minocycline hydrochloride as model drugs,the generated fibers demonstrate the capacity of enabling the release profile of each of the co-delivered drugs to be precisely controlled.Along with their negligible toxicity and the retention of the activity of the loaded drugs,the complex fibers reported in this study warrant further development and optimization for applications that involve co-delivery of multiple agents.

顺北5号断裂带南部压力剖面建立及井身结构优化

顺北5号断裂带南部受断裂构造运动影响,钻井过程中普遍存在恶性漏失、钻井效率低等问题。为此,基于邻井成像测井资料和钻井资料,建立了漏失压力计算模型,得到了顺北5号断裂带南部地层的四压力(孔隙压力、破裂压力、坍塌压力和漏失压力)剖面;根据四压力剖面和钻井技术难点优化井身结构,将侵入体未发育区域原有的五开井身结构优化为四开井身结构,并减小井眼尺寸,缩短了钻井周期;针对侵入体发育区域,设计了地层承压能力强的非常规四开井身结构和缩小井眼尺寸的常规五开专封井身结构,提高了井壁稳定性。现场试验表明:所建漏失压力计算模型的预测准确性较高;应用常规五开专封井身结构后,复杂情况处理时效平均缩短27.8 d,钻井周期平均缩短14.6%。研究和现场试验表明,顺北5号断裂带南部采用优化后的井身结构能够解决钻井过程井漏和钻井效率低的问题,可为复杂地层超深井井身结构设计提供技术借鉴。

Profiling the Change of Key Chemical Ingredients in Combination of Aconitum carmichaeli Debx. and Bletilla striata (Thunb.) Reichb.f. by UPLC-QTOF/MS with Multivariate Statistical Analysis

In the present study, an ultra performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry(UPLC-QTOF/MS) based chemical profiling approach to rapidly evaluate chemical diversity after codecocting of the combination of Aconitum carmichaeli Debx.(wu-tou in Chinese, WT) and Bletilla striata(Thunb.) Reichb.f.(bai-ji in Chinese, BJ) incompatible pair. Two different kinds of decoctions, namely WT-BJ mixed decoction: mixed water extract of each individual herbs, and WT-BJ co-decoction: water extract of mixed two constituent herbs, were prepared. Batches of these two kinds of decoction samples were subjected to UPLC-QTOF/MS analysis, the datasets of tR-m/z pairs, ion intensities and sample codes were processed with supervised orthogonal partial least squared discriminant analysis(OPLS-DA) to holistically compare the difference between these two kinds of decoction samples. Once a clear classification trend was found in score plot, extended statistical analysis was performed to generate S-plot, in which the variables(tR-m/z pair) contributing most to the difference were clearly depicted as points at the two ends of "S", and the components that correlate to these ions were regarded as the most changed components during co-decocting of the incompatible pair. The identities of the changed components can be identified by comparing the retention times and mass spectra with those of reference compounds and/or tentatively assigned by matching empirical molecular formulae with those of the known compounds published in the literatures. Using the proposed approach, global chemical difference was found between mixed decoction and co-decoction, and hypaconitine, mesaconitine, deoxyaconitine, aconitine, 10-OH-mesaconitine, 10-OH-aconitine and deoxyhypaconitine were identified as the most changed toxic components of the combination of WT-BJ incompatible pair during co-decocting. It is suggested that this newly established approach could be used to practically reveal the possible toxic components changed/increased of the herbal combination taboos, e.g. the Eighteen Incompatible Medications(Shi Ba Fan), in traditional Chinese medicines.

面向复杂轨形的钢轨断面轮廓实时识别方法

钢轨断面轮廓检测装备能够测量钢轨的磨耗情况,为铁路维修保养提供重要参考。能否及时准确地从普通轨道、道岔、接头等复杂路况条件下识别出有效钢轨廓形制约了检测装备的实际应用性能。通过对二维线激光采样数据的统计分析,实现对有效廓形和异常廓形的分类识别。首先,对比线路中不同区域的钢轨轮廓形态,选择轨头与轨腰的间断性和轨头与轨腰的形态相关性作为有效轮廓的识别依据。其次,利用不同路况条件下的钢轨轮廓点云数据分布情况,实现对原始数据中难以评估磨耗程度的异常轮廓数据进行识别分类。现场实验测试结果表明,该方法识别出的有效轮廓分布和实际路况基本一致,在行车测试速度8.3 km/h的条件下,单个轮廓平均识别时间为9.78 ms,识别准确率达到97%以上。

不同类型复合添加剂对全株玉米青贮发酵品质、有氧稳定性和细菌区系的影响

本研究旨在评价不同类型的复合添加剂对全株玉米青贮发酵品质、有氧稳定性和细菌区系结构的影响,以探究复合添加剂改善青贮饲料品质的机制。在干物质含量为30.8%时将整株玉米收获并切碎,在鲜样基础上分别进行以下四种处理:(1)对照组(CON组):不进行任何处理;(2)复合乳酸菌剂接种组(CLB组):调制青贮时添加0.002 g/kg由布氏乳酸菌、植物乳杆菌和粪肠球菌组合而成的复合乳酸菌剂;(3)复合有机酸盐处理组(MS组):添加0.1 g/kg以苯甲酸钠和山梨酸钾为主要活性成分的复合有机酸盐;(4)菌酸复配组(CLBMS组):同时进行(2)和(3)处理。每个处理3个生物学重复,抽真空并密封后室温贮藏42 d,开窖后分析玉米青贮的常规养分、发酵参数、有氧稳定性和细菌区系结构。结果表明:CON组玉米青贮的pH显著高于3个处理组(P<0.05),同时CON组和CLB组的乳酸浓度和乳酸/乙酸比显著高于MS和CLBMS处理组(P<0.05),表明CLB和MS处理均能增加玉米青贮pH的下降速度和程度,且MS能够使青贮发酵模式向乙酸型发酵转变;CLBMS处理组玉米青贮的有氧稳定为66.2 h,较CLB组的50.2 h提高了31.9%(P<0.05),而二者与CON组(60.2 h)和MS处理组(65.3 h)之间均无统计学差异(P>0.05)。细菌区系结构分析显示,与CON组相比,CLB组乳酸片球菌的相对丰度显著升高(P<0.05,LDA score>2),而MS组的魏斯氏菌属和鞘氨醇单胞菌属的相对丰度显著增加(P<0.05,LDA score>2),这些变化可能与玉米青贮发酵品质和有氧稳定性的改变密切相关。综上表明,与复合乳酸菌剂相比,复合有机酸盐对全株玉米青贮发酵品质和有氧稳定性的改善效果更佳,且二者具有一定的协同增效作用,但作用机制需要进一步研究。

大型复杂薄壁铝合金空心型材挤压成形工艺

目的解决大型复杂薄壁铝合金空心型材挤压过程中材料流速均匀性控制难,以及模具局部应力集中导致模具寿命低、挤压型材尺寸稳定性差的问题。方法采用有限元模拟方法对此类典型型材挤压过程进行仿真分析,根据仿真结果中型材出口材料流速分布情况,通过调控不同部位材料流入量及材料流动阻力,并以型材出口流速差和流速均方差(SDV)作为衡量挤压过程中材料流速均匀性的指标,逐步迭代优化模具结构以提高材料流动均匀性;根据仿真结果中挤压模具应力分布情况,以模具最高应力作为衡量模具强度的指标,逐步迭代优化模具结构以减小模具应力。结果通过迭代仿真依次优化模具工作带长度、分流孔尺寸、阻流块高度等参数,最终型材出口流速差由25.07 mm/s降至2.72 mm/s,流速均方差由9.84 mm/s降至0.72 mm/s;通过迭代仿真优化焊合角度,最终模具最高应力由945 MPa降至863 MPa。采用基于有限元仿真优化结构的挤压模具成功制备了合格的铝合金型材样件,挤压试验结果与数值模拟结果吻合。结论通过优化模具工作带长度、分流孔尺寸及阻流块高度,调控不同部位材料流入量及材料流动阻力,能够有效解决大型复杂薄壁铝合金空心型材挤压流速均匀性差的问题;通过优化模具焊合角度,能够显著降低模具局部应力集中。

四川雷达波束遮挡区反射因子垂直廓线填补方法的应用研究

以四川成都、宜宾雷达为例,利用近两年观测数据建立不同降水类型、不同回波强度的反射率因子垂直廓线库,基于反射率因子垂直廓线的高度-回波强度变化特性,以高仰角回波强度填补波束遮挡区回波强度,通过对比波束遮挡区实际观测值与填补值之间的差异,检验填补效果。结果表明:(1)不同类型降水空间分布特征差异明显,对VPR进行分层分类处理,能够为后续不同类型降水填补提供较好的支撑;(2)在针对不同降水类型填补时,填补值与观测值保持了较好的一致性,离散程度较小,相关系数介于0.9~0.95,均方根误差介于4.13~8.4 dBZ。(3)雷达波束遮挡所在仰角与上层无雷达波束遮挡仰角越接近,填补效果越好。