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A survey on assembly lines and its types

Ullah SAIF,Zailin GUAN,Baoxi WANG,Jahanzeb MIRZA,Shiyang HUANG

《机械工程前沿（英文）》 2014年第9卷第2期页码 95-105 doi: 10.1007/s11465-014-0302-1

摘要：

Assembly lines are useful for mass production of standard as well as customized products. Line balancing is an important issue, in this regard an optimal or near optimal balance can provide a fruitful savings in the initial cost and also in the running cost of such production systems. A survey of different problems in different types of assembly lines and some of the critical and on going research areas are highlighted here. The provided research information is momentous for the research community in assembly line area to proceed further in the presented issues of assembly lines.

关键词： assembly lines line balancing survey

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基于Bézier曲线的柔性曲面装配变动分析 None

Zhen-yu LIU, Shi-en ZHOU, Jin CHENG, Chan QIU, Jian-rong TAN

《信息与电子工程前沿（英文）》 2018年第19卷第6期页码 796-808 doi: 10.1631/FITEE.1601619

摘要：在装配过程中，柔性零件表面特征会发生形状变化，相比刚性体，其变动分析复杂许多。现有柔性装配变动分析方法大多未考虑零件表面邻近点的相互关系，或者将零件表面上所有特征点的概率分布情况视为统一。本文将柔性曲面零件装配简化为边侧线匹配问题，提出基于Bézier曲线来表征曲面零件边侧线的方法，解决了柔性零件装配中考虑表面连续性的曲面零件装配变动分析问题。该方法利用控制点变动来获取零件边侧线上特征点的偏差，并将它们作为输入参数进行有限元分析，从而计算出最终产品变形量。通过天线表面装配的两个实例，对所提方法进行了验证。

关键词：装配变动分析；特征点；边侧线；柔性曲面；Bézier曲线

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Natural killer cell lines in tumor immunotherapy

null

《医学前沿（英文）》 2012年第6卷第1期页码 56-66 doi: 10.1007/s11684-012-0177-7

摘要：

Natural killer (NK) cells are considered to be critical players in anticancer immunity. However, cancers are able to develop mechanisms to escape NK cell attack or to induce defective NK cells. Current NK cell-based cancer immunotherapy is aimed at overcoming NK cell paralysis through several potential approaches, including activating autologous NK cells, expanding allogeneic NK cells, usage of stable allogeneic NK cell lines and genetically modifying fresh NK cells or NK cell lines. The stable allogeneic NK cell line approach is more practical for quality-control and large-scale production. Additionally, genetically modifying NK cell lines by increasing their expression of cytokines and engineering chimeric tumor antigen receptors could improve their specificity and cytotoxicity. In this review, NK cells in tumor immunotherapy are discussed, and a list of therapeutic NK cell lines currently undergoing preclinical and clinical trials of several kinds of tumors are reviewed.

关键词： natural killer cell natural killer cell line tumor immunotherapy genetic modification

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Assembly of biosynthetic pathways in

Lidan Ye,Xiaomei Lv,Hongwei Yu

《化学科学与工程前沿（英文）》 2017年第11卷第1期页码 126-132 doi: 10.1007/s11705-016-1597-8

摘要： A robust and versatile tool for multigene pathway assembly is a key to the biosynthesis of high-value chemicals. Here we report the rapid construction of biosynthetic pathways in using a marker recyclable integrative toolbox (pUMRI) developed in our research group, which has features of ready-to-use, convenient marker recycling, arbitrary element replacement, shuttle plasmid, auxotrophic marker independence, GAL regulation, and decentralized assembly. Functional isoprenoid biosynthesis pathways containing 4–11 genes with lengths ranging from ~10 to ~22 kb were assembled using this toolbox within 1–5 rounds of reiterative recombination. In combination with GAL-regulated metabolic engineering, high production of isoprenoids (e.g., 16.3 mg?g dcw carotenoids) was achieved. These results demonstrate the wide range of application and the efficiency of the pUMRI toolbox in multigene pathway construction of .

关键词： pathway assembly toolbox reiterative recombination S. cerevisiae biosynthesis

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A novel task-oriented framework for dual-arm robotic assembly task

《机械工程前沿（英文）》 2021年第16卷第3期页码 528-545 doi: 10.1007/s11465-021-0638-2

摘要： In industrial manufacturing, the deployment of dual-arm robots in assembly tasks has become a trend. However, making the dual-arm robots more intelligent in such applications is still an open, challenging issue. This paper proposes a novel framework that combines task-oriented motion planning with visual perception to facilitate robot deployment from perception to execution and finish assembly problems by using dual-arm robots. In this framework, visual perception is first employed to track the effects of the robot behaviors and observe states of the workpieces, where the performance of tasks can be abstracted as a high-level state for intelligent reasoning. The assembly task and manipulation sequences can be obtained by analyzing and reasoning the state transition trajectory of the environment as well as the workpieces. Next, the corresponding assembly manipulation can be generated and parameterized according to the differences between adjacent states by combining with the prebuilt knowledge of the scenarios. Experiments are set up with a dual-arm robotic system (ABB YuMi and an RGB-D camera) to validate the proposed framework. Experimental results demonstrate the effectiveness of the proposed framework and the promising value of its practical application.

关键词： dual-arm assembly AI reasoning intelligent system task-oriented motion planning visual perception

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Pareto lexicographic α-robust approach and its application in robust multi objective assembly line balancing

null

《机械工程前沿（英文）》 2014年第9卷第3期页码 257-264 doi: 10.1007/s11465-014-0294-x

摘要：

Robustness in most of the literature is associated with min-max or min-max regret criteria. However, these criteria of robustness are conservative and therefore recently new criteria called, lexicographic α-robust method has been introduced in literature which defines the robust solution as a set of solutions whose quality or jth largest cost is not worse than the best possible jth largest cost in all scenarios. These criteria might be significant for robust optimization of single objective optimization problems. However, in real optimization problems, two or more than two conflicting objectives are desired to optimize concurrently and solution of multi objective optimization problems exists in the form of a set of solutions called Pareto solutions and from these solutions it might be difficult to decide which Pareto solution can satisfy min-max, min-max regret or lexicographic α-robust criteria by considering multiple objectives simultaneously. Therefore, lexicographic α-robust method which is a recently introduced method in literature is extended in the current research for Pareto solutions. The proposed method called Pareto lexicographic α-robust approach can define Pareto lexicographic α-robust solutions from different scenarios by considering multiple objectives simultaneously. A simple example and an application of the proposed method on a simple problem of multi objective optimization of simple assembly line balancing problem with task time uncertainty is presented to get their robust solutions. The presented method can be significant to implement on different multi objective robust optimization problems containing uncertainty.

关键词： Pareto lexicographic α-robust assembly line balancing

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Achieving desired nodal lines in freely vibrating structures via material-field series-expansion topology

《机械工程前沿（英文）》 2023年第18卷第3期 doi: 10.1007/s11465-023-0758-y

摘要： Accurately controlling the nodal lines of vibrating structures with topology optimization is a highly challenging task. The major difficulties in this type of problem include a large number of design variables, the highly nonlinear and multi-peak characteristics of iteration, and the changeable orders of eigenmodes. In this study, an effective material-field series-expansion (MFSE)-based topology optimization design strategy for precisely controlling nodal lines is proposed. Here, two typical optimization targets are established: (1) minimizing the difference between structural nodal lines and their desired positions, and (2) keeping the position of nodal lines within the specified range while optimizing certain dynamic performance. To solve this complex optimization problem, the structural topology of structures is first represented by a few design variables on the basis of the MFSE model. Then, the problems are effectively solved using a sequence Kriging-based optimization algorithm without requiring design sensitivity analysis. The proposed design strategy inherently circumvents various numerical difficulties and can effectively obtain the desired vibration modes and nodal lines. Numerical examples are provided to validate the proposed topology optimization models and the corresponding solution strategy.

关键词： nodal line topology optimization structural dynamics design material-field series-expansion

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Assembly design system based on engineering connection

Wensheng YIN

《机械工程前沿（英文）》 2016年第11卷第4期页码 423-432 doi: 10.1007/s11465-016-0382-1

摘要：

An assembly design system is an important part of computer-aided design systems, which are important tools for realizing product concept design. The traditional assembly design system does not record the connection information of production on the engineering layer; consequently, the upstream design idea cannot be fully used in the downstream design. An assembly design model based on the relationship of engineering connection is presented. In this model, all nodes are divided into two categories: The component and the connection. Moreover, the product is constructed on the basis of the connection relationship of the components. The model is an And/Or graph and has the ability to record all assembly schemes. This model records only the connection information that has engineering application value in the product design. In addition, this model can significantly reduce the number of combinations, and is very favorable for the assembly sequence planning in the downstream. The system contains a connection knowledge system that can be mapped to the connection node, and the connection knowledge obtained in practice can be returned to the knowledge system. Finally, VC++6.0 is used to develop a prototype system called Connect-based Assembly Planning (CAP). The relationship between the CAP system and the commercial assembly design system is also established.

关键词： product design assembly design engineering connection assembly sequence planning

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Effect on proliferation and apoptosis of T24 cell lines via silencing DNMT1 with RNA interference

ZHANG Shilong, ZENG Fuqing, PENG Shibo, WANG Liang

《医学前沿（英文）》 2008年第2卷第4期页码 374-379 doi: 10.1007/s11684-008-0072-4

摘要： Expression of DNA methyltransferase 1 (DNMT1), which plays an important role on aberrantly methylated CpG in the promoter regions of tumor suppressor genes (TSGs), is higher in bladder cancer cells than in normal bladder cells. Therefore, its overexpression is closely related to tumor formation. In this study, the eukaryotic vector pshRNA-DNMT1 was constructed and transfected into T24 cells. Levels of DNMT1 mRNA and protein were detected by reverse transcription-polymerase chain reaction (RT-PCR) and western blot. Relative to the blank control at the 24th, 48th and 72nd hour after transfection of pshRNA-DNMT1, the inhibitory rates of DNMT1 mRNA levels in T24 cells were 28.44%, 52.48%, 70.91%, respectively. Those of DNMT1 proteins were 24.27%, 57.79%, and 77.74%, respectively. Proliferation and apoptosis were assayed by MTT and flow cytometry with Annexin-V-FITC/PI staining. The growth inhibition rates of pshRNA-DNMT1 at the 24th, 48th and 72nd hour after transfection of pshRNA-DNMT1 were (4.34 ± 0.76)%, (9.87 ± 1.54)% and (13.78 ± 1.93)%, respectively. There were statistically significant differences between pshRNA-DNMT1 and the control blank at each time points ( < 0.01); 24, 48 and 72 hours after T24 cells were transfected by pshRNA-DNMT1, the apoptosis rates of pshRNA-DNMT1 were (3.87 ± 0.81)%, (8.69 ± 1.23)% and (11.46 ± 1.24)%, respectively ( < 0.01 blank control). Based on this case, our conclusion is that the recombinant plasmid pshRNA-DNMT1 can silence the expression of gene DNMT1 mRNA and protein effectively, and to some extent, it also can inhibit the proliferation of bladder cancer cell and promote the cellular apoptosis.

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Enzyme-instructed self-assembly of peptides containing phosphoserine to form supramolecular hydrogels

Jie Zhou, Xuewen Du, Jiaqing Wang, Natsuko Yamagata, Bing Xu

《化学科学与工程前沿（英文）》 2017年第11卷第4期页码 509-515 doi: 10.1007/s11705-017-1613-7

摘要： Enzyme-instructed self-assembly (EISA) offers a facile approach to explore the supramolecular assemblies of small molecules in cellular milieu for a variety of biomedical applications. One of the commonly used enzymes is phosphatase, but the study of the substrates of phosphatases mainly focuses on the phosphotyrosine containing peptides. In this work, we examine the EISA of phosphoserine containing small peptides for the first time by designing and synthesizing a series of precursors containing only phosphoserine or both phosphoserine and phosphotyrosine. Conjugating a phosphoserine to the -terminal of a well-established self-assembling peptide backbone, (naphthalene-2-ly)-acetyl-diphenylalanine (NapFF), affords a novel hydrogelation precursor for EISA. The incorporation of phosphotyrosine, another substrate of phosphatase, into the resulting precursor, provides one more enzymatic trigger on a single molecule, and meanwhile increases the precursors’ propensity to aggregate after being fully dephosphorylated. Exchanging the positions of phosphorylated serine and tyrosine in the peptide backbone provides insights on how the specific molecular structures influence self-assembling behaviors of small peptides and the subsequent cellular responses. Moreover, the utilization of D-amino acids largely enhances the biostability of the peptides, thus providing a unique soft material for potential biomedical applications.

关键词： enzyme-instructed self-assembly phosphoserine phosphatase supramolecular hydrogel

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Relationship between the number of tapping-induced secondary laticifer lines and rubber yield among

Yueyi CHEN,Xinsheng GAO,Xiaofei ZHANG,Weimin TIAN

《农业科学与工程前沿（英文）》 2016年第3卷第4期页码 363-367 doi: 10.15302/J-FASE-2016122

摘要： The lack of suitable early selection parameters means that traditional rubber breeding for yield is time-consuming and inefficient. Laticifer is a tissue specific for natural rubber biosynthesis and storage in rubber tree. The number of the secondary laticifers in the trunk bark tissues is positively correlated with rubber yield in the matured rubber trees that are regularly tapped. In the present study, the rubber yield from 280 of 4–5 year-old virgin trees from 7 cross combinations was compared with the number of newly differentiated secondary laticifers caused by tapping. Results showed that the number of tapping-induced lines of secondary laticifers varied in different germplasm and was positively related to the rubber yield, indicating this could be used as a suitable parameter for early evaluation of yield potential of rubber trees.

关键词： Hevea brasiliensis rubber yield breeding early evaluation tapping secondary laticifer differentiation

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filtering-based bridge weigh-in-motion system on a continuous multi-girder bridge considering the influence lines

Hanli WU, Hua ZHAO, Jenny LIU, Zhentao HU

《结构与土木工程前沿（英文）》 2020年第14卷第5期页码 1232-1246 doi: 10.1007/s11709-020-0653-0

摘要： A real-time vehicle monitoring is crucial for effective bridge maintenance and traffic management because overloaded vehicles can cause damage to bridges, and in some extreme cases, it will directly lead to a bridge failure. Bridge weigh-in-motion (BWIM) system as a high performance and cost-effective technology has been extensively used to monitor vehicle speed and weight on highways. However, the dynamic effect and data noise may have an adverse impact on the bridge responses during and immediately following the vehicles pass the bridge. The fast Fourier transform (FFT) method, which can significantly purify the collected structural responses (dynamic strains) received from sensors or transducers, was used in axle counting, detection, and axle weighing technology in this study. To further improve the accuracy of the BWIM system, the field-calibrated influence lines (ILs) of a continuous multi-girder bridge were regarded as a reference to identify the vehicle weight based on the modified Moses algorithm and the least squares method. experimental results indicated that the signals treated with FFT filter were far better than the original ones, the efficiency and the accuracy of axle detection were significantly improved by introducing the FFT method to the BWIM system. Moreover, the lateral load distribution effect on bridges should be considered by using the calculated average ILs of the specific lane individually for vehicle weight calculation of this lane.

关键词： bridge weigh-in-motion continuous bridge fast Fourier transform influence line axle weight calculation

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Distinct community assembly processes underlie significant spatiotemporal dynamics of abundant and rare

《环境科学与工程前沿（英文）》 2022年第16卷第6期 doi: 10.1007/s11783-021-1513-4

摘要：

• Season and landform influenced spatiotemporal patterns of abundant and rare taxa.

关键词： Rare taxa Biogeography Community assembly Bacterioplankton The Yangtze River

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Research on constraint-based virtual assembly technologies

YANG Rundang, WU Dianliang, FAN Xiumin, YAN Juanqi

《机械工程前沿（英文）》 2007年第2卷第2期页码 243-249 doi: 10.1007/s11465-007-0043-5

摘要： To realize a constraint-based virtual assembly operation, the unified representations of the assembly constraint, the equivalent relation between the constraint and the degree of freedom (DOF), and the movement DOF reduction in a virtual environment are proposed. Several algorithms about the constraint treatment are submitted. First, the automatic recognition algorithm based on the assembly relation is used to determine the position and orientation relation between two geometry elements of constraint whether they meet the given errors. Second, to satisfy the new constraint, according to the positing solving algorithm, the position and orientation of an active part are modified with minimal adjustment after the part has satisfied the affirmed constraints. Finally, the algorithm of movement navigation based on the generalized coordinate system is put forward, and the part movement is guided. These algorithms have been applied to the integrated virtual assembly environment (IVAE) system. Experiments have indicated that these algorithms have well supported constraint treatments in the IVAE and realized the closer combination of the virtual and the real assembly processes.

关键词： movement DOF recognition algorithm assembly orientation combination

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The construction of pseudo-Janus silica/surfactant assembly and their application to stabilize Pickering

《化学科学与工程前沿（英文）》 2022年第16卷第7期页码 1101-1113 doi: 10.1007/s11705-021-2095-1

摘要： Nanoparticles with high surface energy and chemical activity have drawn substantial attention in petroleum industry. Recently, Janus nanoparticles exhibited tremendous potential in enhanced oil recovery (EOR) due to their asymmetric structures and properties. In this study, a series of amphiphilic pseudo-Janus@OTAB (PJ@C18) nanoparticles with different concentrations of stearyltrimethylammoium bromide (OTAB) were successfully fabricated. The structures and properties of PJ@C18 were characterized by Fourier transform infrared spectroscopy and ζ-potential measurements. Based on the emulsification experimental results, the interaction models and the self-assembly behavior between hydrophilic nanoparticles (SiO₂@NH₂) and OTAB molecules at the oil/water interface were proposed, which was further confirmed via the measurements of the contact angle and dynamic interfacial tension. Interestingly, it was found that the change of pH value from 7.5 to 4.0 caused the type reversal of the PJ@C18-1000 stabilized Pickering emulsions. Furthermore, the PJ@C18-1000 stabilized Pickering emulsion system with excellent salt and temperature tolerances (10000 mg∙L^–1, 90 °C) significantly improved the oil recovery in the single-tube (more than 17%) and double-tube (more than 25%) sand pack model flooding tests. The findings of this study could help to better understand the construction mechanism of pseudo-Janus silica/surfactant assembly and the potential application of PJ@C18-1000 stabilized Pickering emulsions for EOR.

关键词： Janus nanoparticles surfactant double phase inversion self-assembly enhanced oil recovery