Inversion of river-bottom sediment parameters using mechanically sampled specimens and subbottom profiling data

The study of river dynamics requires knowledge of physical parameters, such as porosity, permeability, and wave propagation velocity, of river-bottom sediments. To do so, sediment properties are determined on mechanically sampled specimens and from subbottom profiling. However, mechanical sampling introduces disturbances that affect test results, with the exception of grain-size distribution. In this study, we perform inversion of acoustic data using the grain-size distribution of mechanically sampled specimens and the relation between porosity and permeability from the Kozeny-Carman equation as prior information. The wave reflection coefficient of the water-silt interface is extracted from the raw subbottom profile. Based on the effective density fluid model, we combine the Kozeny-Carman equation and the wave reflection coefficient. We use experimental data from two Yellow River reservoirs to obtain the wave velocity and density of multiple sections and their spatial variations, and find that the inversion and testing results are in good agreement.

Production characteristics and displacement mechanisms of infilling polymer-surfactant-preformed particle gel flooding in post-polymer flooding reservoirs:A review of practice in Ng3 block of Gudao Oilfield

The pilot test of infilling polymer-surfactant-preformed particle gel(PPG)flooding has been successfully implemented after polymer flooding in Ng3 block of Gudao Oilfield in China.However,the production characteristics and displacement mechanisms are still unclear,which restricts its further popularization and application.Aiming at this problem,this paper firstly analyzes the production performance of the pilot test and proposed four response types according to the change of water cut curves,including W-type,U-type,V-type response,and no response.Furthermore,the underlying reasons of these four types are analyzed from the aspects of seepage resistance and sweep efficiency.The overall sweep efficiency of gradual-rising W-type,gradual-decreasing W-type,and early V-type response increases from 0.81 to 0.93,0.55 to 0.89,and 0.94 to 1,respectively.And the sum of seepage resistance along the connection line between production well and injection well for U-type and delayed V-type response increases from 0.0994 to 0.2425,and 0.0677 to 0.1654,respectively.Then,the remaining oil distribution after polymer flooding is summarized into four types on the basis of production and geological characteristics,namely disconnected remaining oil,streamline unswept remaining oil,rhythm remaining oil,and interlayer-controlled remaining oil.Furthermore,the main displacement mechanisms for each type are clarified based on the dimensionless seepage resistance and water absorption profile.Generally,improving connectivity by well pattern infilling is the most important for producing disconnected remaining oil.The synergistic effect of well pattern infilling and polymer-surfactant-PPG flooding increases the dimensionless seepage resistance of water channeling regions and forces the subsequent injected water to turn to regions with streamline unswept remaining oil.The improvement of the water absorption profile by polymer-surfactant-PPG flooding and separated layer water injection contributes to displacing rhythm remaining oil and interlayer-controlled remaining oil.Finally,the paper analyzes the relationships between the remaining oil distribution after polymer flooding and production characteristics of infilling polymer-surfactant-PPG flooding.The study helps to deepen the understanding of infilling polymer-surfactant-PPG flooding and has reference significance for more commercial implementations in the future.

Comparative Analysis of the Erosion Mechanism of Different Profiles in the Arcuate Foreshore under Typhoon Action

The comparison results of three beach profile data repeatedly measured before and after the typhoon in Shuidong Bay,west Guangdong province which show that there are significant differences in beach profile erosion and response process.And the changes of beach profile can be divided into:strong downward overall low shoreline regressive type and overall slight erosion shoreline regressive type.Application of the modified mildslope equation along three beach profile are simulated wave high reflection to the sea side,to the section vertical shore pressure gradient and including water roll force and radiation stress,the vertical shore forces one dimensional profile along the momentum conservation equation(radiation stress and water roll force)bottom friction and lateral mixing reaction between numerical solution,the momentum conservation equations of the wave increases the water flow velocity and section along the profile distribution of wave height and related forces.The analysis shows that the extent and difference of coastal erosion depend on the shoreline erosion mode stimulated by the maximum surge water of the coastal current and the maximum velocity of the coastal current and the dynamic state of the profile topography under the action of the profile location,morphology and incident wave elements.

Effect of pin profile and process parameters on microstructure and mechanical properties of friction stir welded Al-Cu joints

In friction stir welding(FSW), pin profile has more influence on material flow especially in welding of dissimilar materials with different yield strengths. In the dissimilar welding of aluminium and copper, the material flow behaviour is complex to understand and thus a study is needed to reveal the mechanism of flow behaviour and the resultant mechanical properties. Three pin profiles, whorl pin profile(WPP), plain taper pin profile(PTP) and taper treaded pin profile(TTP) were chosen. The effects of pin profile on the microstructure, microhardness and tensile properties were studied. Optical microscope, scanning electron microscope, X-ray diffraction and EDS analysis were used to characterize the microstructural features. Among the three pin profiles, PTP profile results in defect-free stir zone and maximum joint properties of yield strength of 101 MPa, tensile strength of 116 MPa and joint efficiency of 68% compared with the other pin profiles. However, the microhardness plots are more or less identical for all the pin profiles but follows fluctuating trend. This is attributed to the heterogeneous distribution of hard Cu particle. The superior joint properties are mainly attributed to the defect-free stir zone formation and dispersion strengthening.

Effect of small tool pin profiles on microstructures and mechanical properties of 6061 aluminum alloy by friction stir welding

The effect of small tool pin profiles on the microstructures and mechanical properties of 6061 aluminum alloy joints using friction stir welding （FSW） technique was investigated. Three different tool pin profiles： threaded tapered cylindrical （T1）, triangular （T2） and square （T3） were used to produce the joints. The results indicate that the weld joints are notably affected by joining with different tool pin profiles. The triangular tool pin profile produces thebest metallurgicaland mechanical weld properties compared with other tool pin profiles. Besides, the lowest tensile strength and microhardness are obtained for the joint friction stir welded with square tool pin profile. It is observed that the smaller tool pin profile and shoulder diameter lead to narrow region of heat affected zone （HAZ） and a desired level of softening. The fracture surface examination shows that the joints are also affected when welding with different types of tool pin profiles. The fracture surface shows that the triangular specimen fails with a ductile fracture mode during the tensile test, while the brittle fracture modes are observed in the joints fabricated with other tool pin profiles （T1 and T3）.

Microstructure and mechanical properties of Al−Mg−Si alloy U-shaped profile

To get a full understanding of hot extrusion,solid solution treatment and aging process on the Al−0.56Mg−0.63Si alloy,the microstructure and mechanical properties of a U-shaped profile were studied through optical microscopy,scanning electrical microscopy,transmission electrical microscopy,hardness,and tensile tests.The coarse equiaxed grains existed near the profile edge as a result of the dynamic recrystallization nucleation and exceeding growth during hot extrusion.The fibrous deformed and sub-structured grains located between the two coarse grain layers,due to the occurrence of work-hardening and dynamic recovery.Perpendicular needle β′′precipitates were distributed inside the grain,and obvious precipitates-free zone appeared after aging treatment.The tensile strength,yield strength and elongation of the aged Al−Mg−Si alloy U-shaped profile were no less than 279.4 MPa,258.6 MPa,and 21.6%,respectively.The fracture morphology showed dimple rupture characteristics.The precipitates and grain boundaries played key role in the strengthening contribution.

Study on Relationship Between Differential Proteins of Bacillus cereus LBR-4 and Its Salt Tolerance Mechanism

In order to explore the salt tolerance mechanism of Bacillus cereus LBR-4 with salinity of 14%NaCl,differential proteomic analysis of the whole protein of LBR-4 strain expressed under 14%NaCl high salinity condition and normalculture condition(1%NaCl)was studied by two-dimensional electrophoresis and mass spectrometry.The isoelectric point of most detected proteins was between pH 4-7 and the molecular weight distribution was 10-70 ku.Compared with the normal culture condition,the expression level of 118 protein spots in the whole protein expression map changed significantly(accounting for 25.2%of the total protein spots).The expression level of 78 protein spots increased significantly,including 22 new protein spots that appeared under high salt stress.The expression levels of 40 protein spots decreased significantly,including 18 protein spots that disappeared under high salt stress.By mass spectrometry,six distinct differentially expressed protein spotswere dihydroxy acid dehydratase,cell division protein FtsZ,iron sulfur cluster synthesis protein SufD,unknown carboxylase YngE,hypothetical acetaldehyde dehydrogenase DhaS and phenylalanine acid tRNA ligase alpha subunit.It was speculated that under high salt stress,the cells had protective measures and the secretion of intracellular compatible solutes increased.The iron and sulfur clusters involved in various physiological reactions also activated the stressful suf synthesis pathway,and therate of cell division and reproduction was also slowed down and ensured the normal progress of physiological reactions inthe cells.

Detailed Kinetic Mechanism of CNG Combustion in an IC Engine

In this study, the four kinetic reaction mechanisms were developed to simulate the formation of pollutant species in CNG fired IC engine. The reactions were generated using EXGAS and coupled with Leed’s NOx reactions to develop four kinetic mechanisms. These reaction mechanisms described the combustion of natural gas at low (below 800 K) to high (above 1000 K) temperature in combustion chamber. The simulation studies predicted that the maximum cylinder pressure was achieved up to 18.0 atm & 40.0 atm under fuel leaner conditions (φ ≈0.6) and fuel rich conditions (φ=1.13 to 1.3) respectively. The simulation based data was compared with the experimental data (when engine was operated at 3000 rpm, φ=1.0, Pinlet=0.67 atm). For fuel rich conditions, high concentrations of CO were observed while NOx levels were lowered while the fuel leaner mixture produced the lower CO emissions and moderate levels of NOx emissions. The NOx and CO profiles depicted that Mechanism-I, Mechanism-II and Mechanism III seemed to be inappropriate for predicting the emissions in due to CNG combustion IC engine. The molded data for Mechanism-IV exhibited closer agreement with experimental measurements. The rate of production analysis identified the important reactions in each mechanism which were contributing in the formation of emission concentrations of pollutant species. Although each proposed mechanism illustrated some discrepancies among the profiles, Mechanism-IV (consisting of 208 reactions and 78 species) showed good agreement with experimental data for pressure, temperature and pollutant species profiles.

A New Thread Guide Mechanism of Rubbed Roving Frame

A new thread guide mechanism of a rubbed roving frame is developed, which consists mainly of a plate cam, a linkage and an air bag spring. Characteristics and design parameters of the air spring are explored in this study. Based on analyses of winding technology for this kind of package, the kinetic laws of the thread guide is put forward. General design equations of the cam profile are derived, and common kinetic laws of II linkage group which is used for such mechanism design is proposed. It proves theoretically that it is practicable. The experimental results indicate that it can meet the needs of technological demands, and the new thread guide mechanism has been used successfully on textile machines.

Study on the Mechanism of Shimian Granules (SMG) against Depression via Regulating Circadian Rhythms

Background:According to the World Health Organization,about 350 million people worldwide are suffering from depression.It's reported that depression has been linked to several circadian rhythm perturbations,suggesting a disruption of the circadian clock system in affective disorders.The present study investigates the possible molecular mechanism of Shimian granules(SMG)in treating depression via restoring disrupted circadian rhythms.Method:Firstly,network pharmacology approach was used to identify the compounds and potential targets of SMG in TCMIP and BATMAN-TCM database.Secondly,the differential expression genes were obtained by gene expression profiling in GEO database(GSE56931,GSE98793).Further,protein-protein interactions(PPI)network was used to screen out core targets by STRING v11.Moreover,functional enrichment was carried out in DAVID database.Conclusively,the"herbs-compounds-targets-pathways"network was established to explore the mechanism of SMG in the treatment of depression.Result:It was found out that 65 compounds,18 targets and three pathways contributed to SMG in treating depression by regulating disrupted circadian rhythms,which might relate to core targets TNF,IL10,VDR in cAMP and calcium signaling pathway.Conclusion:Network pharmacology combined with gene expression profiling exhibited a powerful means to investigate the possible mechanism of formula,which contributes to theoretical basis for further study of SMG in the treatment of depression.

A Development of Rom-Exercise Machine Using Linkages(Design of Leg Mechanism by Walking Simulation)

In this study, the design of an automatic ROM-Exercise machine that is constructed witha planar multililnk mechamsm consisting of only revolute pairs is investigated. Namely, equations thatdetermine the minimum moving spaces and relative positions of link required to construct the legmechanism are formulated with consideration of transform functions. For the leg mechanism that isconstructed with a planar eleven-link mechanism, arrangements of each link and optimum linkprofiles avoided mutual interferences among moving links are determined wb consideration of therelative locations of each link in the same plane during a cycle of motion of the mechanism. Based onthe above analytical results, an automatic ROM-Exercise machine that performs within a minimum moving spaces is proposed as a prachcal example. ms study is carried out as part of the students'computcr education to the graduation thesis, in order to improve their creativity and machine designtechnology skills in coniunction with educational advantages. Significam educational results areobtained by using the design techniques mentioned above.

俯仰式播种单体仿形性能检测试验台设计与试验

为解决播种单体仿形机构性能难以检测的问题,设计了俯仰式播种单体仿形性能检测试验台。阐述了试验台组成结构与工作原理,对其高速传动系统、液压升降系统、监控系统以及关键部件参数进行设计。应用ANSYS软件对台架整体和关键部件进行静力学分析和模态分析,验证结构设计的合理性。为检验俯仰式播种单体仿形性能检测试验台的实际检测效果,以德邦大为1205型牵引式免耕精量播种机播种单体为研究对象,先以液压杆伸出量与传送带速度为试验因素,以监控系统误差为评价指标进行试验。试验得出,在液压杆伸出量为0~200 mm范围内,监控系统角度传感器最大误差为0.69 mm;在传送带速度8~19 km/范围内,光电编码器最大误差为0.18 km/h。确认监控系统准确性后,再以单体速度为试验因素,采集速度8、10、12 km/h下地块的起伏数据为目标曲线,以地形起伏模拟曲线的绝对误差平均值为指标进行单因素试验,试验得出,所设计的试验台可有效模拟田间地面的起伏频率与起伏量,绝对误差平均值为1.86 mm,满足播种单体仿形性能检测需求。

内置工字型CFRP型材高强圆钢管高强混凝土轴压短柱组合效应分析

目的 研究内置工字型CFRP型材的高强圆钢管高强混凝土短柱在轴心压力作用下三种材料的组合效应。方法 采用有限元分析软件ABAQUS对其进行数值模拟,通过相关试验验证模型的准确性,并对典型构件的破坏形态、受力全过程曲线进行分析,揭示构件各组成部分之间的相互作用和工作机理,评估CFRP配置率、钢材屈服强度、混凝土抗压强度、约束效应系数对组合效应的影响。结果 在高强圆钢管高强混凝土柱中内置CFRP型材,对构件的延性及安全裕度有显著提高,并改善了高强圆钢管对高强混凝土的约束,提高了构件的组合效应。结论 CFRP配置率控制在5.9%~8.4%,约束效应系数在1.2~1.4,钢材屈服强度不大于770 MPa时,构件中三种材料组合效应最佳。

多杆仿形式茶枝柑剥皮取肉装置设计与试验

广东新会一带的茶枝柑是“南药”广陈皮唯一来源,其初加工过程中剥皮取肉环节自动化程度低、并容易产生“汁溅”导致腐蚀广陈皮(俗称“烧皮”),为了实现茶枝柑初加工全程自动化,该研究研发一种新型茶枝柑自动剥皮取肉装置以解决上述问题。首先采用3D扫描与重构技术,获得人手剥皮时果皮真实轨迹和姿态数据,建立人手剥皮位姿数学模型;然后以人手剥皮位姿信息为目标,设计多杆仿形机构并使其轨迹和姿态逼近人手剥皮位姿;最后对设计好的多杆仿形机构进行仿真验证和分析,并加工装配出样机进行实际剥皮试验。试验结果表明,该装置可较好模拟人手剥皮时的位姿曲线,配合真空吸盘吸附,可实现茶枝柑机械式自动剥皮,然后配合包络式柔顺机械爪,实现了茶枝柑无损剥皮取肉,试验结果显示剥皮无损率为80%。该研究结果可为柑橘类水果剥皮初加工提供了理论和试验参考。

β-内酰胺酶抑制剂的稳定性与降解反应特性

β-内酰胺酶抑制剂与广谱β-内酰胺抗生素的联合使用是一种有效解决细菌耐药的策略之一。目前上市的β-内酰胺酶抑制剂按其化学结构主要包括氧青霉烯类(克拉维酸)、青霉烷砜类(舒巴坦和他唑巴坦)和二氮杂二环辛烷类化合物(阿维巴坦),本文对临床常见的β-内酰胺酶抑制剂的稳定性与降解反应特性进行综述,并结合当前药典标准中的有关物质检查项,探讨上述β-内酰胺酶抑制剂的杂质谱控制策略。

聚乳酸异形纤维熔融纺丝及性能研究

以聚乳酸(PLA)切片为原料,采用异形喷丝板,通过熔融纺丝、拉伸两步法制得PLA异形截面纤维。通过对PLA切片的DSC热分析确定纤维纺丝成形温度,并用显微镜分析了纤维的截面形态,研究了不同拉伸倍数下PLA纤维性能。结果表明,PLA纤维为类十字形异形截面纤维,相对径向异形度为37%,纤维表面平滑,且有明显的棱状凸起。拉伸倍数越大,断裂强度和取向因子都增大,而断裂伸长率下降。

基于改进YOLOv5的铝型材表面缺陷检测算法

针对工业生产中铝合金型材表面缺陷在实际检测中出现漏检和误检的情况,提出一种YOLOv5-Ghost-CBAM-BiFPN模型对铝型材缺陷进行更加精确的检测。首先在YOLOv5 Backbone网中引入了一个轻量级Ghost模块,在保证准确性的前提下显著提高了检测速度。其次,将卷积块注意机制(CBAM)模块添加到Backbone网络的卷积层,以增强特征提取,进一步提高检测精度。此外,考虑到铝型材缺陷尺寸差异,在Neck模块中使用了用于多尺度特征融合的双向特征金字塔网络(Bi-FPN)来聚合不同缺陷类型的特征。实验表明:优化后的模型mAP、精确率P、召回率R都有明显提高。

端面铣削工件表面粗糙度数学模型与实验验证

目的针对多种表面粗糙度影响因素的耦合作用使轮廓形成机理不清,导致表面粗糙度数学模型存在表面质量智能管控工业应用预测精度不足的技术难题,建立端面铣削工件表面粗糙度数学模型。方法首先,基于加工运动学机理和刀具几何学分析端面铣削工件表面轮廓形成机理,建立考虑刀具跳动的工件表面轮廓模型以及轮廓高度偏差关于铣削力的补偿函数,并通过卷积神经网络(Convolution Neural Network,CNN)进行解析。其次,建立端面铣削表面粗糙度数学模型。最后,进行可转位面铣刀端面铣削ZG32MnMo的实验验证,分别采集轮廓数据与铣削力信号,建立以铣削力为输入、轮廓高度偏差数据为输出的铣削数据集,训练卷积神经网络解析轮廓高度补偿值并验证理论模型的准确性,对比分析考虑刀具跳动的表面粗糙度数学模型与CNN优化考虑刀具跳动的表面粗糙度数学模型的精度。结果CNN优化考虑刀具跳动的表面粗糙度数学模型对加工重叠区与非重叠区内沿刀具进给方向的轮廓算术平均偏差Ra的预测误差分别为18.71%和14.14%,与考虑刀具跳动的表面粗糙度数学模型相比,精度分别提高了10.61%和32.83%,CNN优化考虑刀具跳动的表面粗糙度数学模型对轮廓单元的平均宽度R_(sm)和支承长度率R_(mr(c))的预测结果与实验值吻合。结论考虑刀具跳动以及动态铣削力耦合作用边界条件的表面粗糙度数学模型能够有效预测端面铣削表面粗糙度,可为在质量管控工程中的应用提供理论指导与技术支撑。

PARAMETERIZED-PROTOTYPE-BASED DYNAMIC OPTIMIZATION DESIGN FOR CAM PROFILE

Aiming at the problems in current cam profile optimization processes, such as simple dynamics models, limited geometric accuracy and low design automatization level, a new dynamic optimization mode is put forward. Based on the parameterization modeling technique of MSC. ADAMS platform, the different steps in current mode are reorganized, thus obtaining an upgraded mode called the ＂parameterized-prototype-based cam profile dynamic optimization mode＂. A parameterized prototype（PP） of valve mechanism is constructed in the course of dynamic optimization for cam profiles. Practically, by utilizing PP and considering the flexibility of the parts in valve mechanism, geometric accuracy and design automatization are improved.

基于纳米划痕的熔石英玻璃去除机制与亚表面裂纹研究

目的研究熔石英玻璃在不同动态载荷作用下的材料去除机制和亚表面裂纹形成与扩展机理。方法对熔石英玻璃试样进行纳米划痕试验,分别从划痕轮廓、划痕力2个方面分析不同载荷下熔石英玻璃的力学行为,通过扫描电镜和光学显微镜观察划痕形貌,分析材料去除机制;采用逐层截面显微法对划痕截面的亚表面裂纹形貌进行观测,研究动态载荷下工件亚表面裂纹的形成与扩展机理。结果当动态载荷小于118mN时,材料发生塑性变形,亚表面未产生裂纹;当动态载荷大于118mN且小于245mN时,材料处于塑脆转变阶段,亚表面裂纹以动态载荷加载点为起点,向试样内部扩展形成赫兹锥形裂纹并伴有横向裂纹的存在;当动态载荷超过245mN时,材料进入完全脆性断裂阶段,亚表面裂纹不断扩展至表面导致材料破碎。结论随着动态载荷的不断增大,熔石英玻璃的材料去除经历了弹塑性变形、塑脆转变、脆性断裂3个阶段;亚表面裂纹受到动态载荷的影响,裂纹从载荷加载点形成,并沿着应力最大方向不断扩展,导致材料表面发生脆性断裂;熔石英玻璃的临界切深与其动态弹性模量成正比,与其流动应力成反比,动态冲击载荷使熔石英玻璃的临界切削深度下降,亚表面裂纹更易扩展,材料去除更快进入塑脆转变阶段。