Search | Engineering

订阅投稿

首页工程期刊工程焦点工程成就工程前沿关于我们 English

资源类型

期刊论文 114

会议视频 1

年份

2023 10

2022 11

2021 4

2020 6

2019 5

2018 11

2017 8

2016 4

2015 1

2014 1

2013 5

2012 5

2011 8

2010 8

2009 9

2008 2

2007 2

2006 2

2005 2

2004 3

展开︾

关键词

三峡工程 2

气体辅助注射成型 2

12相整流 1

GDMS 1

μ-TAS 1

三元乙丙橡胶 1

三台阶七步开挖法 1

三峡水库 1

上下图模型 1

上部结构施工 1

中国 1

中子、伽马混合场 1

主缆架设 1

井身结构 1

交直流同时供电 1

代表帧 1

优化设计 1

优化调度决策 1

住宅建筑 1

展开︾

检索范围：

排序：展示方式：

Fabrication of scaffolds in tissue engineering: A review

Peng ZHAO, Haibing GU, Haoyang MI, Chengchen RAO, Jianzhong FU, Lih-sheng TURNG

《机械工程前沿（英文）》 2018年第13卷第1期页码 107-119 doi: 10.1007/s11465-018-0496-8

摘要：

Tissue engineering (TE) is an integrated discipline that involves engineering and natural science in the development of biological materials to replace, repair, and improve the function of diseased or missing tissues. Traditional medical and surgical treatments have been reported to have side effects on patients caused by organ necrosis and tissue loss. However, engineered tissues and organs provide a new way to cure specific diseases. Scaffold fabrication is an important step in the TE process. This paper summarizes and reviews the widely used scaffold fabrication methods, including conventional methods, electrospinning, three-dimensional printing, and a combination of molding techniques. Furthermore, the differences among the properties of tissues, such as pore size and distribution, porosity, structure, and mechanical properties, are elucidated and critically reviewed. Some studies that combine two or more methods are also reviewed. Finally, this paper provides some guidance and suggestions for the future of scaffold fabrication.

关键词： tissue engineering scaffolds electrospinning 3D printing molding techniques conventional methods

HTML PDF 收藏

density measurement for plastic injection molding via ultrasonic technology

《机械工程前沿（英文）》 2022年第17卷第4期 doi: 10.1007/s11465-022-0714-2

摘要： Density variation during the injection molding process directly reflects the state of plastic melt and contains valuable information for process monitoring and optimization. Therefore, in-situ density measurement is of great interest and has significant application value. The existing methods, such as pressure−volume−temperature (PVT) method, have the shortages of time-delay and high cost of sensors. This study is the first to propose an in-situ density measurement method using ultrasonic technology. The analyses of the time-domain and frequency-domain signals are combined in the proposed method. The ultrasonic velocity is obtained from the time-domain signals, and the acoustic impedance is computed through a full-spectral analysis of the frequency-domain signals. Experiments with different process conditions are conducted, including different melt temperature, injection speed, material, and mold structure. Results show that the proposed method has good agreement with the PVT method. The proposed method has the advantages of in-situ measurement, non-destructive, high accuracy, low cost, and is of great application value for the injection molding industry.

关键词： ultrasonic measurement melt density in-situ measurement injection molding

HTML PDF 收藏

Review of small aspheric glass lens molding technologies

Shaohui YIN,Hongpeng JIA,Guanhua ZHANG,Fengjun CHEN,Kejun ZHU

《机械工程前沿（英文）》 2017年第12卷第1期页码 66-76 doi: 10.1007/s11465-017-0417-2

摘要：

Aspheric lens can eliminate spherical aberrations, coma, astigmatism, field distortions, and other adverse factors. This type of lens can also reduce the loss of light energy and obtain high-quality images and optical characteristics. The demand for aspheric lens has increased in recent years because of its advantageous use in the electronics industry, particularly for compact, portable devices and high-performance products. As an advanced manufacturing technology, the glass lens molding process has been recognized as a low-cost and high-efficiency manufacturing technology for machining small-diameter aspheric lens for industrial production. However, the residual stress and profile deviation of the glass lens are greatly affected by various key technologies for glass lens molding, including glass and mold-die material forming, mold-die machining, and lens molding. These key technical factors, which affect the quality of the glass lens molding process, are systematically discussed and reviewed to solve the existing technical bottlenecks and problems, as well as to predict the potential applicability of glass lens molding in the future.

关键词： aspheric glass lens mold-die manufacturing lens molding molding process simulation

HTML PDF 收藏

Precision glass molding: Toward an optimal fabrication of optical lenses

Liangchi ZHANG,Weidong LIU

《机械工程前沿（英文）》 2017年第12卷第1期页码 3-17 doi: 10.1007/s11465-017-0408-3

摘要：

It is costly and time consuming to use machining processes, such as grinding, polishing and lapping, to produce optical glass lenses with complex features. Precision glass molding (PGM) has thus been developed to realize an efficient manufacture of such optical components in a single step. However, PGM faces various technical challenges. For example, a PGM process must be carried out within the super-cooled region of optical glass above its glass transition temperature, in which the material has an unstable non-equilibrium structure. Within a narrow window of allowable temperature variation, the glass viscosity can change from 10⁵ to 10¹² Pa·s due to the kinetic fragility of the super-cooled liquid. This makes a PGM process sensitive to its molding temperature. In addition, because of the structural relaxation in this temperature window, the atomic structure that governs the material properties is strongly dependent on time and thermal history. Such complexity often leads to residual stresses and shape distortion in a lens molded, causing unexpected changes in density and refractive index. This review will discuss some of the central issues in PGM processes and provide a method based on a manufacturing chain consideration from mold material selection, property and deformation characterization of optical glass to process optimization. The realization of such optimization is a necessary step for the Industry 4.0 of PGM.

关键词： precision glass molding optical lens constitutive modeling optimization manufacturing chain Industry 4.0

HTML PDF 收藏

Microcellular injection molding process for producing lightweight thermoplastic polyurethane with customizable

Thomas ELLINGHAM, Hrishikesh KHARBAS, Mihai MANITIU, Guenter SCHOLZ, Lih-Sheng TURNG

《机械工程前沿（英文）》 2018年第13卷第1期页码 96-106 doi: 10.1007/s11465-018-0498-6

摘要：

A three-stage molding process involving microcellular injection molding with core retraction and an “out-of-mold” expansion was developed to manufacture thermoplastic polyurethane into lightweight foams of varying local densities, microstructures, and mechanical properties in the same microcellular injection molded part. Two stages of cavity expansion through sequential core retractions and a third expansion in a separate mold at an elevated temperature were carried out. The densities varied from 0.25 to 0.42 g/cm³ (77% to 62% weight reduction). The mechanical properties varied as well. Cyclic compressive strengths and hysteresis loss ratios, together with the microstructures, were characterized and reported.

关键词： thermoplastic polyurethane microcellular injection molding cavity expansion compressive strength hysteresis loss ratio

HTML PDF 收藏

Recent advancements in optical microstructure fabrication through glass molding process

Tianfeng ZHOU,Xiaohua LIU,Zhiqiang LIANG,Yang LIU,Jiaqing XIE,Xibin WANG

《机械工程前沿（英文）》 2017年第12卷第1期页码 46-65 doi: 10.1007/s11465-017-0425-2

摘要：

Optical microstructures are increasingly applied in several fields, such as optical systems, precision measurement, and microfluid chips. Microstructures include microgrooves, microprisms, and microlenses. This paper presents an overview of optical microstructure fabrication through glass molding and highlights the applications of optical microstructures in mold fabrication and glass molding. The glass-mold interface friction and adhesion are also discussed. Moreover, the latest advancements in glass molding technologies are detailed, including new mold materials and their fabrication methods, viscoelastic constitutive modeling of glass, and microstructure molding process, as well as ultrasonic vibration-assisted molding technology.

关键词： optical microstructure microgroove microlens glass molding process single-point diamond cutting

HTML PDF 收藏

气辅注塑成型注气压力的模糊神经网络控制研究

欧长劲

《中国工程科学》 2007年第9卷第5期页码 27-32

摘要：

针对气辅注塑成形的注气压力精确控制要求，设计了具有５层结构的模糊神经网络控制器和控制算法，利用神经网络的学习能力实现对模糊逻辑规则的优化，改善了系统的适应性。对系统３段压力控制的仿真分析，验证了模糊神经网络控制模型的可行性，控制效果良好。

关键词：气体辅助注射成型模糊神经网络注气压力控制

HTML PDF 收藏

Three-dimensional numerical simulation for plastic injection-compression molding

Yun ZHANG, Wenjie YU, Junjie LIANG, Jianlin LANG, Dequn LI

《机械工程前沿（英文）》 2018年第13卷第1期页码 74-84 doi: 10.1007/s11465-018-0490-1

摘要：

Compared with conventional injection molding, injection-compression molding can mold optical parts with higher precision and lower flow residual stress. However, the melt flow process in a closed cavity becomes more complex because of the moving cavity boundary during compression and the nonlinear problems caused by non-Newtonian polymer melt. In this study, a 3D simulation method was developed for injection-compression molding. In this method, arbitrary Lagrangian-Eulerian was introduced to model the moving-boundary flow problem in the compression stage. The non-Newtonian characteristics and compressibility of the polymer melt were considered. The melt flow and pressure distribution in the cavity were investigated by using the proposed simulation method and compared with those of injection molding. Results reveal that the fountain flow effect becomes significant when the cavity thickness increases during compression. The back flow also plays an important role in the flow pattern and redistribution of cavity pressure. The discrepancy in pressures at different points along the flow path is complicated rather than monotonically decreased in injection molding.

关键词： injection-compression molding simulation injection molding melt flow cavity pressure

HTML PDF 收藏

Micro-optical fabrication by ultraprecision diamond machining and precision molding

Hui LI, Likai LI, Neil J. NAPLES, Jeffrey W. ROBLEE, Allen Y. YI

《机械工程前沿（英文）》 2017年第12卷第2期页码 181-192 doi: 10.1007/s11465-017-0444-z

摘要：

Ultraprecision diamond machining and high volume molding for affordable high precision high performance optical elements are becoming a viable process in optical industry for low cost high quality microoptical component manufacturing. In this process, first high precision microoptical molds are fabricated using ultraprecision single point diamond machining followed by high volume production methods such as compression or injection molding. In the last two decades, there have been steady improvements in ultraprecision machine design and performance, particularly with the introduction of both slow tool and fast tool servo. Today optical molds, including freeform surfaces and microlens arrays, are routinely diamond machined to final finish without post machining polishing. For consumers, compression molding or injection molding provide efficient and high quality optics at extremely low cost. In this paper, first ultraprecision machine design and machining processes such as slow tool and fast too servo are described then both compression molding and injection molding of polymer optics are discussed. To implement precision optical manufacturing by molding, numerical modeling can be included in the future as a critical part of the manufacturing process to ensure high product quality.

关键词： ultraprecision machining slow tool servo fast tool servo compression molding injection molding microlens arrays optical fabrication

HTML PDF 收藏

Surface modification techniques of membranes to improve their antifouling characteristics: recent advancements

《化学科学与工程前沿（英文）》 2023年第17卷第12期页码 1837-1865 doi: 10.1007/s11705-023-2347-3

摘要： Surface modification techniques of membranes to improve their antifouling characteristics: recent advancements and developments

关键词： Surface modification techniques

HTML PDF 收藏

Application of endoscopic techniques in orbital blowout fractures

null

《医学前沿（英文）》 2013年第7卷第3期页码 328-332 doi: 10.1007/s11684-013-0271-5

摘要：

Minimally invasive surgical techniques, particularly endoscopic techniques, have revolutionized otolaryngeal surgery. Endoscopic techniques have been gradually applied in orbital surgery through the sinus inferomedial to the orbit and the orbital subperiosteal space. Endoscopic techniques help surgeons observe fractures and soft tissue of the posterior orbit to precisely place implants and protect vital structures through accurate, safe, and minimally invasive approaches. We reviewed the development of endoscopic techniques, the composition of endoscopic systems for orbital surgery, and the problems and developmental prospects of endoscopic techniques for simple orbital wall fracture repair.

关键词： orbital fractures endoscope restoration surgery

HTML PDF 收藏

气辅成型工艺参数对制品成型质量的影响趋势研究

邱水金,姜少飞 ,柴国钟,鲁聪达

《中国工程科学》 2009年第11卷第4期页码 84-90

摘要：

对截面形状为s-3的加强筋进行工艺参数优化分析，讨论了气辅成型工艺参数对成型质量的影响程度，获得了一组较好的工艺参数组合。以此为参考标准，改变某一个工艺参数而保持其他工艺参数不变，对比研究4种不同截面形状加强筋在气辅成型条件下的成型情况，并考察了单个工艺参数对成型质量的影响趋势情况。

关键词：气体辅助注射成型加强筋正交试验设计

HTML PDF 收藏

Progress in studies of sex determination mechanisms and sex control techniques in

Qian ZHOU,Songlin CHEN

《农业科学与工程前沿（英文）》 2016年第3卷第2期页码 113-123 doi: 10.15302/J-FASE-2016093

摘要： The (half-smooth tongue sole) is a marine flatfish of great commercial value for fisheries and aquaculture in China. It has a female heterogametic sex determination system (ZW/ZZ) and environmental factors can induce sex-reversal of females to phenotypic males, suggesting that it is a promising model for the study of sex determination mechanisms. Additionally, females grow much faster than males and it is feasible to improve the aquaculture production through sex control techniques. This paper reviews the progress in research on sex determination mechanisms research in our laboratory. We have completed whole-genome sequencing and revealed the genome organization and sex chromosome evolution of . A putative male determining gene was identified and DNA methylation was verified as having a crucial role in the sex reversal process. Genetic maps and sex-specific biomarkers have been used in a marker-assisted selection breeding program and for differentiation of the fish sex. Development and improvement of sex control technologies, including artificial gynogenesis and production of breeding fry with high proportion of females, is also reviewed. These research advances have provided insight into the regulation of sex determination and enabled efficient sex management in artificial culturing of .

关键词： Cynoglossus semilaevis sex determination sex control technique

HTML PDF 收藏

Artificial lift equipment repairing techniques in Daqing Oilfield

He LIU, Guochen SHI, Cui WANG, Peijing SHI, Yi XU,

《机械工程前沿（英文）》 2010年第5卷第1期页码 111-117 doi: 10.1007/s11465-009-0081-2

摘要： To date, there are more than 60000 wells in Daqing Oilfield including injectors and producers. The annual investment is 1.07 billion RMB in the maintenance of artificial lift equipment, which is a heavy burden for the sustainable development of Daqing Oilfield. After years of study, a series of repairing techniques for artificial lift equipment have been created, which saved 0.5 billion RMB per year, leading to remarkable benefits and efficiency as well.This paper first presents the background of artificial lift equipment repairing technique in Daqing Oilfield. Then, a detailed introduction is given about the development history and current situation of key repairing technology, including the oil tube, rod string, and suck-rod pump. With reference to the study result in automobile and military territory remanufacturing technology, this paper analyzes the situation of artificial lift repairing techniques and evaluates the development direction and tendency of this field for a mature oilfield in the future.

关键词： artificial lift equipment repairing technique remanufacturing technique Daqing Oilfield