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Assembly process modeling mechanism, which contains all the process elements, is crucial for assembly process planning. This study proposes an assembly process modeling mechanism based on the product hierarchy, and the assembly-by-disassembly approach is used for constructing the assembly process model. Firstly, three stage for process models called disassembly process model (DPM), rough assembly process model (RAPM), and finish assembly process model (FAPM) are presented, and the process information, such as the motion information, process marks is given. Secondly, the operation semantics for assembly process model is proposed to describe the physical constraints between parts and components. Thirdly, the establishing procedure of assembly process model is given, which includes establishing process of disassembly task tree, design process of disassembly process node, mapping process from DPM to RAPM, and mapping process from RAPM to FAPM four subprocesses. At last, a prototype assembly process planning system, called AMTProcesser, is developed based on the proposed modeling mechanism.

A good assembly process plan can increase the efficiency and quality, and decrease the cost and time of the whole product manufacturing process, which is important as product and production demand changes rapidly in today’s market. Several approaches using different techniques and methodologies have been developed and reported in the literature for assembly process planning. Automated assembly process planning (AAPP) has been the main focus of the research efforts over the years, with most work concentrated on attempting to automate or to semi-automate the key sequencing process. However, some of these efforts have not been successful in general, and many assembly process plans are still based on traditional methods. The purpose of this paper is to review and outline the methodologies and tools in assembly process planning developed during the past ten years, such as the application of meta-heuristics methods to find the optimal/near optimal assembly plans and assembly line balancing, the evaluation methods for design for assembly (DFA), and collaborative assembly process planning systems. Based on this review the future trends in this area are also identified and discussed.

There are various forms of assembly data sources for wind turbines, which contributes to the lack of a unified and standardized expression. Moreover, the reusability of historical assembly data is low, which leads to the poor reasoning ability of a new product assembly sequence. In this paper, we propose a knowledge graph-based approach for assembly sequence recommendations for wind turbines. First, for the multimodal data (text in process manual, image of tooling, and three-dimensional (3D) model) of assembly, a multi-process assembly information representation model is established to express assembly elements in a unified way. In addition, knowledge extraction methods for different modal data are designed to construct a multimodal knowledge graph for wind turbine assembly. Further, the retrieval of similar assembly process items based on the bidirectional encoder representation from transformers joint graph-matching network (BERT-GMN) is proposed to predict the assembly sequence subgraphs. Also, a Semantic Web Rule Language (SWRL)-based assembly process items inference method is proposed to automatically generate subassembly sequences by combining component assembly relationships. Then, a multi-objective sequence optimization algorithm for the final assembly is designed to output the optimal assembly sequences. Finally, taking the VEU-15 wind turbine as the object, the effectiveness of the assembly process information modeling and part multi-source information representation is verified. Sequence recommendation results are better quality compared to traditional assembly sequence planning algorithms. It provides a feasible solution for wind turbine assembly to be optimized from multiple objectives simultaneously.

An electrohydraulic servo actuator is used as an example to show how numerical data on the parameters of the components and assembly units supplied to the assembly section allow control of the assembly process, its qualitative transformation, and refinement of the characteristics of finished products. The described approach to the arrangement of the assembly process may be applied to any product both to ensure that nondefective items are assembled in manufacturing components with apparently extended parameter tolerance ranges and to enhance the characteristics and reduce labor input in the adjustment of products.

The paper deals with the analysis of the assembly process of the selected component. The purpose of the analysis is to identify bottlenecks in the assembly process and to suggest possible improvements to the assembly process. The carburettor of a passenger car was chosen as the object of assembly. By analysing the assembly process, we measure the duration of individual assembly operations. Subsequently, we propose measures to improve and shorten the assembly time for problematic operations. We design and describe the assembly tool that has been tested and evaluated.

Purpose: This paper proposes model-based standard times estimates, using multiple linear regression, nonlinear optimization, and fuzzy systems in four real cases assembly lines. The work includes a description of the models and a comparison of their performance with values obtained using the conventional chronometer method. These models allow estimating standard times without reconducting field studies. Design/methodology/approach: For the development of the time study, the methodology applied by the International Labour Organization (ILO) was used as a baseline. This methodology is structured in three phases: selection of the case study, registration of the process by direct observation, and calculation/estimation of the standard time. The selected case studies belong to real assembly lines of motorcycles, television sets, printed circuit boards, and bicycles. Findings: In the motorcycle's assembly case, the study allowed constructing seven linear regression models to estimate standard times for assembling the front parts, and seven linear regression models to predict standard times for the rear parts of the different motorcycle types. Compared to the classical chronometer method, the results obtained never exceeded 10%. Regarding the case studies of assembling TV sets and PCBs, the study considered the construction of nonlinear optimization models that allow making appropriate predictions of the standard times in their assembly lines. Finally, for the bicycle assembly line, a fuzzy logic model to represent the standard time was constructed and validated. Research limitations/implications: For reasons of confidentiality of information, this work omitted the names of companies, services, and models of manufactured products. Originality/value: The literature consulted does not refer to the representation of standard time on assembly lines using mathematical models. The construction of these models with empirical data from actual assembly lines was a valuable aid to the companies involved in supporting activity planning.

Process-oriented tolerance design and maintenance policy of the fixture system are major ways to ensure the dimension quality of autobodies. Traditional maintenance policy mostly uses a fixed threshold considering the static nominal process variables, which always lead to excessive or inadequate maintenance of fixtures. Based on the analysis of dynamic information in multistation assembly process, a maintenance policy optimization methodology is proposed to integrate the updated process states and monitored incoming parts’ deviations in the assembly process. In this method, the product quality constraint function considering dynamic fixture component degradation, dimension fluctuations of parts, etc. is constructed firstly, and then, a nonlinear optimization algorithm is used to obtain the optimal maintenance schedule with a minimum maintenance cost. An engine compartment assembly case was used to illustrate the procedure and advantages of the proposed method. At last, the effect of dynamic process variables and incoming parts’ qualities on the maintenance results were examined and discussed.

In the past two decades, augmented reality (AR) has received a growing amount of attention by researchers in the manufacturing technology community, because AR can be applied to address a wide range of problems throughout the assembly phase in the lifecycle of a product, e.g., planning, design, ergonomics assessment, operation guidance and training. However, to the best of authors’ knowledge, there has not been any comprehensive review of AR-based assembly systems. This paper aims to provide a concise overview of the technical features, characteristics and broad range of applications of AR-based assembly systems published between 1990 and 2015. Among these selected articles, two thirds of them were published between 2005 and 2015, and they are considered as recent pertinent works which will be discussed in detail. In addition, the current limitation factors and future trends in the development will also be discussed.

Polymersomes are artificial nanoparticles formed by the self-assembly process of amphiphilic block copolymers composed of hydrophobic and hydrophilic blocks. They can encapsulate hydrophilic molecules in the aqueous core and hydrophobic molecules within the membrane. The composition of block copolymers can be tuned, enabling control of characteristics and properties of formed polymersomes and, thus, their application in areas such as drug delivery, diagnostics, or bioimaging. The preparation methods of polymersomes can also impact their characteristics and the preservation of the encapsulated drugs. Many methods have been described, including direct hydration, thin film hydration, electroporation, the pH-switch method, solvent shift method, single and double emulsion method, flash nanoprecipitation, and microfluidic synthesis. Considering polymersome structure and composition, there are several types of polymersomes including theranostic polymersomes, polymersomes decorated with targeting ligands for selective delivery, stimuli-responsive polymersomes, or porous polymersomes with multiple promising applications. Due to the shortcomings related to the stability, efficacy, and safety of some therapeutics in the human body, polymersomes as drug delivery systems have been good candidates to improve the quality of therapies against a wide range of diseases, including cancer. Chemotherapy and immunotherapy can be improved by using polymersomes to deliver the drugs, protecting and directing them to the exact site of action. Moreover, this approach is also promising for targeted delivery of biologics since they represent a class of drugs with poor stability and high susceptibility to in vivo clearance. However, the lack of a well-defined regulatory plan for polymersome formulations has hampered their follow-up to clinical trials and subsequent market entry.

Fixtures, tools, and other assembly resources have an important role in the assembly of complex products, so it is very necessary to consider the interactive relationship between the resources model and the product model for assembly order planning in 3D environment. Firstly, the features of assembly process planning involved resources are analyzed. Secondly, the concept of the assembly process intention（AsmPI） is introduced，and an assembly process can be divided into an AsmPI sequence. Thirdly, based on the graph theory, a resource-involved assembly process model is built up. At last, setting a typical structure as an example, the validity of this modeling method is verified.