LDV assisted bubble dynamic parameter measurements from two enhanced tubes boiling in saturated R-134a

LDV measurements and heat transfer experiments for nucleate pool boiling from two horizontal enhanced tubes with porous copper on copper surfaces immersed in saturated R-134a were conducted. The influence of tube position (alignment) and tube pitch on bubble dynamics and boiling characteristics were studied. Photographs indicate that the average number of bubbles increases with heat fluxes, which is the same as those in previous studies of single tube. However, the bubble departure diameters of the upper tube show an opposite trend with an increase as compared to previous single-tube studies. LDV measurements show that the present tube arrangement has significant influence on local velocity in both magnitude and trend. The heat transfer mechanism and modeling for the upper tube were studied and developed.     

The formation of IQ type mutagens from Maillard reaction in ethanolic solution

The present study mimics cooking meats in alcohol or distilled spirit marinades by using a 0.1 M creatinine/0.05 M sugars/0.1 M threonine ethanolic model solution, in an attempt to investigate the formation of the heterocyclic amines IQ and IQx, via Maillard reaction. The results showed that ethanol accelerated the formation of IQ and IQx, in a dose-dependent manner. In an aqueous model solution of 0.1 M creatinine/0.05 M glucose/0.1 M threonine after 8 h heating at 150 °C, the contents of IQ and IQx are 16.5 ± 2.2 and 26.2 ± 4.2 mg/kg, respectively. However, at a similar Maillard browning level in the equivalent 50% ethanolic model solution after heating at the same temperature for only 4 h, the contents of IQ and IQx significantly increase to 46.0 ± 5.5 and 69.2 ± 3.4 mg/kg, respectively.     

Fast planar-oriented ripple search algorithm for hyperspace VQ codebook.

This paper presents a fast codebook search method for improving the quantization complexity of full-search vector quantization (VQ). The proposed method is built on the planar Voronoi diagram to label a ripple search domain. Then, the appropriate codeword can easily be found just by searching the local region instead of global exploration. In order to take a step further and obtain the close result full-search VQ would, we equip the proposed method with a duplication mechanism that helps to bring down the possible quantizing distortion to its lowest level. According to the experimental results, the proposed method is indeed capable of providing better outcome at a faster quantization speed than the existing partial-search methods. Moreover, the proposed method only requires a little extra storage for duplication.     

Completely biodegradable composites reinforced by the cellulose nanofibers of pineapple leaves modified by eco-friendly methods

In this study, cellulose nanofibers (CNF) derived from waste pineapple leaves (PALF) were incorporated into poly (lactic acid) (PLA) with the aim of developing completely biodegradable and sustainable composites. CNF was first prepared by the 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) method, and then, different surface modifications of the eco-friendly method were carried out for better dispersion in the PLA matrix. Then, a series of eco-friendly modified CNF/PLA composites were prepared by melt-blending. According to the contact angle experiment, the values of eco-friendly modified CNFs increased from 12.02° to 61.49 and 57.45°, respectively. DSC thermograms show that eco-friendly modified CNFs have a significant nucleating effect for the crystallization of PLA compared to the original CNF. Mechanical testing reveals that the tensile and impact strengths of eco-friendly modified CNF containing composites are improved by 5.4~22.7% and 17.5~56.1%, respectively, through the addition of only 1~3 wt% of modified CNF, and are all higher than that of the original CNF containing composite. Moreover, eco-friendly modified CNF containing composites can allow good light transmittance due to better dispersity of the modified CNF. Consequently, the addition of modified CNFs to the PLA matrix results in increased mechanical and thermal properties of the composites, as well as transparency. Moreover, the addition of CNFs extracted from pineapple leaves by eco-friendly methods can not only reduce the amount of agriculture waste but also avoid the usage of an organic solvent and meet the requirements of environmental protection.     

定量分析食品中的矿物油污染物

矿物油是碳数为10~50的直链、支链和烷基取代的环状饱和烷烃与芳香烃的混合物,其化学组成非常复杂。近年来,食品中的矿油油污染问题受到持续关注,主要原因是食品包装涉及使用回收纸和再生纸,其残留印刷油墨中的大量工业级矿物油造成与其接触食品的污染。调查显示:几乎所有食品中都或多或少含有矿物油。目前,国内对于食品中矿物油的分析方法还仅局限于定性鉴别。欧洲对矿物油的定量研究较多,陆续开发出在线联用的高效液相色谱-气相色谱-氢火焰离子化器检测法(HPLC-GC-FID)、离线固相萃取法(SPE-GC-FID)以及二维气相色谱法(GC×GC)等定量分析方法。本文综述了食品中矿物油污染物的最新分析技术、操作步骤以及定量结果的数据处理方法,目的是通过借鉴,研发出适用于我国食品中矿物油的定量分析方法,开展市售食品调查,保障食品安全。     

FPGA-realization of the kinematics IP for SCARA robot

Microsystem Technologies - In the implementation of robot motion control, it often requires complex forward and inverse kinematics calculation. However, this algorithm requires more CPU time in the...     

连续光源原子吸收光谱法顺序测定蛤蚧中 6种金属元素

目的采用连续光源原子吸收光谱法顺序测定蛤蚧头、躯干、尾、四肢等不同部位中铜、铁、锌、锰、镍、铬等6种金属元素的含量。方法采用微波消解样品,连续光源原子吸收光谱技术多元素顺序测定的方法。结果优化条件下,在0.05~2.00 mg/L浓度范围内,各元素的吸光度与浓度呈良好的线性关系(相关系数r≥0.9993),本方法检出限在0.3~13.2μg/g之间,加标回收率在76.7%~100.0%之间。将该法应用于实际蛤蚧样品中上述元素的测定,测定结果表明,蛤蚧不同身体部位中6种元素含量有所不同,Fe、Mn元素在四肢中的含量最高,Cu、Zn、Cr元素在头部中含量最高,Ni元素在躯干中的含量最高。结论本方法满足实际样品的分析要求,且较之常规锐线光源原子吸收光谱技术在保证分析准确度的同时,大大提升了分析效率。本方法可以对中药重金属污染风险监测提供借鉴。     

Joint coding and embedding techniques for multimedia images

Hiding data in digital images is a technique for secret data communication. It involves embedding important data into a cover image in digital form with minimal perceptible degradation. In this paper, we first propose an improved data hiding method for side-match vector quantization (SMVQ) compressed images, which utilizes the codeword-pairing procedure to modulate the index code of each image block. In order to take it a step further and obtain a larger embedding capacity, we remodel the first proposed method into a new one with the power of variable-rate data embedding through the use of a multiple-base notational system. According to the experimental results, the two proposed methods are indeed capable of providing a larger embedding capacity without causing noticeable distortions of stego-images in comparison with previous methods. Moreover, our methods also maintain a low compression bit-rate without auxiliary data.