International Journal of Precision Engineering and Manufacturing最新文献

Cell migration is an essential process in a number of physiological and pathological events, and known to be modulated by external microenvironment because cells may sense physical and chemical signals from the microenvironment and collectively respond to these signals. Over the past two decades, a lot of efforts have been made to study how external microenvironment can affect cell migration behaviors. Cells often migrate through confined environments in vivo, such as extracellular matrices in tissues and capillary vessels. Understanding how cells move in these constrained spaces is crucial to clarify various biological processes. For instance, during embryonic development, cells migrate through specific pathways to form tissues and organs. In wound healing, cells migrate to repair damaged tissues. In cancer, tumour cells migrate to invade surrounding tissues and metastasize to distant sites. Recent advances of bio-MEMS technologies have enabled to characterize cell mechanics and to control local cellular environment at micro-scale. In order to study cell migration under confinement, microchannels have been widely fabricated and used due to their directionality and compatibility. Thus, this study reviews recent work on fabrication of microchannels and their applications to investigate cell migration behaviors, ranging from straight channels to tortuous structures. Challenges and limitations associated with studying cell migration in microchannels are also discussed. Reviewing cell migration in confined environments may provide valuable insights into the underlying mechanisms of cell migration and aid in developing strategies for therapeutic interventions.

Driver monitoring system (DMS) was mainly developed to prevent accident risks by analyzing facial movements related to drowsiness and carelessness in real time such as driver’s gaze, blink, and head angle through cameras and warning the driver. Recently, the scope has been expanded to monitor passengers, and it has been linked to safety functions such as neglecting children, empty seats, or controlling airbags on seats with people under safety weight. However, evaluation research for algorithm advancement and performance optimization is relatively insufficient. In addition, the verification system is facing limitations such as personal information protection problems caused by the subject’s face data, errors in reproducing the subject’s drowsy and careless behavior, and differences in behavior according to individual differences. Therefore, as the importance of traffic safety is emphasized, an evaluation tool that can more efficiently and systematically evaluate the performance of DMS is needed. In this study, a driver behavior simulation dummy was developed that can quantitatively control the movement of the driver’s face and upper body. The driver behavior simulation dummy was developed in three stages in the order of function and specification definition, design and manufacture according to specifications, and verification through error tests for each function.

As electronic waste poses environmental challenges, exploring eco-friendly alternatives becomes imperative. In this review, the introduction reveals the disposal problem of existing printed circuit boards (PCBs) and the potential impacts of implementing biodegradable PCBs towards the United Nations Sustainable Development Goals. Various biodegradable materials, including polylactic acid, cellulose/cellulose acetate, silk proteins, gelatin, polyvinyl alcohol, mycelium, and wood, were evaluated for their properties and suitability in PCB manufacturing. Each material is scrutinised for its suitability in creating environmentally friendly circuit boards. The study meticulously analyses these biodegradable PCBs' electrical, mechanical, thermal and decomposition properties, providing insights into their performance under various conditions. The article also explores different fabrication methods and their advantages and limitations for manufacturing biodegradable PCBs. Solvent and non-solvent based decomposition of the biodegradable PCBs were revealed. The research outcome on a balance between hygroscopic property and degradability of biodegradable PCBs is revealed. The narrative extends to encompass the challenges and issues associated with the Design-for-Manufacturing processes and life cycle assessment of biodegradable PCBs, shedding light on potential hurdles and areas for improvement. The article concludes with a forward-looking perspective on the future of biodegradable printed circuit boards, environmentally friendly fire-retardants, a proposal for alternative standards for biodegradable PCBs, and their increasing role in sustainable electronics.

Finishing is an essential process after manufacturing of miniature products. The conventional finishing processes can be used to produce good surface in micro domain but effectiveness of these processes is very poor for polishing of ductile, hard and brittle materials. Considering aforementioned, rotary abrasive float polishing set-up has been developed and utilized for polishing of aluminium matrix composite specimens. The effect of abrasive particle size, abrasive concentration, lap rotation and polishing time on surface finish were analysed. Taguchi L₁₈ mixed orthogonal array was engaged for the experimental design and optimization. The surface roughness height (R_a, µm) of the polished specimens were enhanced from 0.437 to 0.049 µm i.e. 88.79%, when experiments were performed at optimal parametric setting. Abrasive particle size, lap rotation and polishing time was found significant factors in deciding surface roughness. Scanning electrode microscopic and optical images confirm the absence of any scratch and roughness peaks on polished surface specimens.

The precision of scroll machining plays a crucial role in scroll compressor efficiency. However, the improvement in scroll surface quality usually comes at the cost of an increase in energy consumption, so a trade-off between surface quality and energy consumption is required. Here in, we concentrate on optimizing several scroll end milling parameters including depth of cut, feed rate, cutting speed, and radial depth of cut to enhance the efficiency of scroll compressors, which greatly influence manufacturing responses like cutting force, surface roughness, and machining time. First, a set of scroll milling experiments are conducted and analyzed by the Taguchi L25 orthogonal array. Then, a single response optimization is done by the Taguchi method to show the impact of the milling parameters on each single response. Furthermore, the Taguchi method associated with the desirability function is applied to optimize the multi-response outputs. According to the analysis of variance (ANOVA) for the single-response, feed rate is found the most significant factor, while the results of the multi-response analysis prove that depth of cut with 37.53% is the most significant factor for the entire system. Finally, a quadratic regression analysis is performed to verify the validation of optimized results. The results revealed a 44.04% improvement in machining time, accompanied by a 2.46% enhancement in composite desirability. This demonstrated a perfect fit between the measured and expected values, achieving a balance between surface quality and energy consumption. The optimization results provide a guidance for the high-surface quality machining of scrolls and could be directly applied in the manufacturing processes of scroll compressors.

There has been a growing interest in using Fiber Bragg Grating (FBG) sensors for the detection of humidity and water content due to their high sensitivity, ease of installation, multiplexing capability, reliability, and resistance to electromagnetic interference. Although, several studies and papers have been published on FBG sensors and their applications in various fields such as construction, geophysical, there is a lack of a consolidated review that specifically focuses on recent developments in agriculture with particular reference soil humidity and water content. Therefore, a comprehensive and up-to-date analysis of the advances, detection mechanisms, challenges, and potential future directions in this field is needed. This paper provides an in-depth analysis and summarizes the fundamental principles, advancements, methodologies, and recent research findings, highlighting the potential application in agriculture, development, challenges, and prospects for FBG-based humidity and water content detection. By utilizing the changes in FBG wavelength or amplitude caused by the presence of humidity, they provide an effective means for real-time monitoring and control of water content. However, challenges remain to be addressed, such as the need for accurate calibration and the potential for drift over time. In this review, we further discuss the strategies and techniques proposed to overcome the highlighted challenges, such as sensor packaging, signal processing algorithms, and calibration procedures, and suggest that further studies could be done to investigates the novel materials with enhanced sensitivity and selectivity, development of miniaturized and wireless FBG sensor system, as well as investigating multiplexing techniques for simultaneous measurement of multiple parameters.

Microfluidics is a promising research area that is widely used in biochemical applications. Recently, the commercialization of microfluidic devices composed of economical plastics has been highlighted. Plastic microfluidic devices must contain conformal contacts to construct a completely closed channel that prevents leakage during liquid transport. However, the conventional fabrication (i.e., injection molding and bonding) of plastic microfluidic devices requires empirical expertise, high cost, time-consuming, and complex procedures. This limits its extensive use in the research and development (R&D) phase to take the next steps toward final commercialization. In particular, iterative changes in the channel design typically lead to increased time and cost. This study proposes an easy-to-change and cost-effective fabrication method for 3D-printed microfluidic devices that offer bonding- and leakage-free spontaneous capillary flow (SCF). Locking pillar arrays on upper and lower substrates are simply and reliably assembled using friction forces. Incorporating inherent fabrication errors in 3D printing allows the intended and reproducible assembly gaps between the substrates to be used as microchannels. In addition, a novel side-opened (side-railed) channel geometry is applied to provide both SCF and virtual sidewalls (i.e., capillary barriers) along the microchannel. Finally, the proposed device demonstrates a potential fabrication method that can be utilized as a bridge between the R&D and commercialization phases.

Ball screws are surface heat-treated/hardened to improve their fatigue strength. However, the screws inevitably deform during heating. Thus, an additional straightening process is essential. Pressurization through three-point bending is typically adopted; however, determining the appropriate stroke for certain plastic deformations is challenging, mainly due to the complex mechanical properties of surface heat-treated ball screws. In this study, ball screws composed of S55C with various geometric shapes and heat-treated depths were tested with the aim of constructing a stroke model for precise straightening. Three-point bending experiments showed that the plastic deformation of the ball screws after bending was affected by the ratio of the heat-treated area to the total cross-sectional area, as well as the absolute value of the heat-treated area. Response surfaces were constructed according to the given plastic deformation and geometric shape of the ball screws to predict the desired stroke for straightening. Based on the experimental results, a computational model was built by modeling the screws with two materials. By adjusting the mechanical properties of non-heat-treated and heat-treated areas, the computational model showed similar characteristics to the experimental results. It is expected that our approach will contribute to more precise and effective straightening of partially heat-treated ball screws with complex mechanical properties.