Tool fabrication for composite forming of aircraft winglet using multi-point dieless forming

Journal of Mechanical Science and Technology - Flexible forming technology such as Multi-point dieless forming (MDF) has benefits for the sheet metal field because it can implement a variety of...     

Upper extremity hemodynamics and sensation with backpack loads

Heavy backpacks are often used in extreme environments, for example by military during combat, therefore completion of tasks quickly and efficiently is of operational relevance. The purpose of this study was to quantify hemodynamic parameters (brachial artery Doppler and microvascular flow by photoplethysmography; tissue oxygenation by near-infrared spectroscopy; arterial oxygen saturation by pulse oximeter) and sensation in upper extremities and hands (Semmes-Weinstein monofilament test and 2-point discrimination test) while wearing a loaded backpack (12 kg) in healthy adults for 10 min. All values were compared to baseline before wearing a backpack. Moderate weight loaded backpack loads significantly decreased upper extremity sensation as well as all macrovascular and microvascular hemodynamic values. Decreased macrovascular and microvascular hemodynamics may produce neurological dysfunction and consequently, probably affect fine motor control of the hands.     

大跨高墩连续刚构桥不对称悬臂段施工技术

随着我国交通事业的发展，其对桥梁的结构和性能也提出了更高的要求。本文主要分析了大跨高墩连续刚构桥不对称悬臂段施工现状和主要施工技术要点，并成功将其应用于实际，以期为同类桥型的施工提供借鉴。     

Isolation and identification of an antiproliferative substance from fructose–tyrosine Maillard reaction products

We isolated a substance from fructose–tyrosine Maillard reaction products (MRPs) and investigated its antiproliferative effect on six human cancer cell lines. The ethyl acetate fraction of fructose–tyrosine MRPs showed a strong antiproliferative effect; this fraction was isolated and purified using silica gel column chromatography, semipreparative RP-HPLC, and recycling HPLC. The structure of the purified compound was determined using spectroscopic methods. The isolated compound was identified as 2,4-bis(p-hydroxyphenyl)-2-butenal (C₁₆H₁₄O₃, HPB242). HPB242 inhibited cell growth in a dose-dependent manner (10–80 μg/ml) on the six human cancer cell lines. The IC₅₀ values of HPB242 on the six human cancer cell lines were 17.34 μg/ml (MCF-7), 29.21 μg/ml (HCT-116), 34.57 μg/ml (H-460), 34.87 μg/ml (HepG2), 48.77 μg/ml (PC-3), and 55.83 μg/ml (MKN-45).     

Statistical analysis for the manufacturing of multi-strip patterns by roll-to-roll single slot-die systems

Roll-to-roll (R2R) slot-die coating systems are mostly devoted to the mass manufacture of printed electronics. This study examined the correlation among the operating conditions, thickness, and width of the patterned strip fabricated by the R2R slot-die system. A full factorial experiment was conducted to screen for effective parameters. The velocity of a moving substrate was found to be the most dominant parameter affecting the thickness and width of the patterned strips. The flow ratio of the supply to the slot-die, and gap between substrate and slot-die did not affect the width of the strip, but affected the thickness; therefore, the flow ratio and gap can be employed for the independent patterning of thickness against width. In addition, it was proposed to determine the R2R process conditions, such as gap, velocity, and flow ratio for the desired thickness and width of the patterned strips.     

Part-by-part dimensional error compensation in compliant sheet metal assembly processes

Dimensional variation in assembly processes is one of the most important issues that affect quality. Although robust design and statistical process quality control help to reduce this problem, they cannot be used for instant variation reduction during assembly operations, especially during process ramp-up. This paper introduces a complete methodology for dimensional-related error compensation in compliant sheet metal assembly processes. The proposed methodology is divided into two steps: (1) an off-line error control-learning module using virtual assembly models to determine necessary adjustments; and (2) an in-line control implementation using a feed-forward control strategy based on the learned adjustments. The off-line learning step focuses on determining control actions or corrections to compensate for the negative effects incoming part errors have on Key Product Characteristics. Specifically, it utilizes a newly developed iterative sampling method based on Kriging fitting to efficiently determine optimal control actions. The in-line feed-forward control identifies appropriate part-by-part adjustments using these learned control actions and incoming assembly component measurements. In this paper, two case studies are presented. First, a mathematical case study presents an empirical proof for the feasibility of the Iterative Sampling and Fitting Algorithm. Second, a simulation-based case study illustrates the effectiveness of the proposed methodology to improve dimensional quality in assembly operations for compliant sheet metal parts.     

Termite tunneling feature extraction using genetic algorithm

Path design uses information about termite reproduction and the termite environment necessary for tunneling. Features are extracted by analyzing relevance of this information, and the fitness and relevance of these features are evaluated. The proposed method is demonstrated and is capable of finding various optimal termite tunneling paths.     

Investigation on formation and distribution of remaining oil and sensitivity analysis in fracture-vuggy media

Drilling and dewaxing are used to manufacture the quantitative model and stochastic model of fracture-vuggy media, respectively, which are used for the investigation on the oil displacement of full diameter cores. The formation and distribution of remaining oil and sensitivity analysis in fracture-vuggy media are studied. The research results show that the density difference between the displacing phase and the displaced phase and the connection position between fractures and vugs determine the fluid distribution law in the vugs. After water flooding, the remaining oil is composed of “attic oil,” “occlusion oil,” “corner oil,” “blind-vug oil,” “oil film,” and “dead oil region.” Then, the influences of oil viscosity, injection rate, density, and viscosity of driving fluid on oil recovery and remaining oil are studied.