A Versatile Universal Capacitor‐Grounded Voltage‐Mode Filter Using DVCCs

In this paper, a versatile three‐input five‐output universal capacitor‐grounded voltage‐mode filter is proposed. The circuit employs two differential voltage current conveyors as active elements together with two grounded capacitors and four resistors as passive elements. The proposed configuration can be used as either a single‐input five‐output or three‐input two‐output. Unlike the previously reported works, it can simultaneously realize five different generic filtering signals: lowpass, bandpass, highpass, bandreject, and allpass. It still maintains the following advantages: (i) the employment of all grounded capacitors, (ii) no need to employ inverting‐type input signals, (iii) no need to impose component choice, (iv) orthogonal control of the resonance angular frequency ω_o and the quality factor Q, and (v) low active and passive sensitivity performances.     

Specific interactions in miscible polymer blends of poly(2‐hydroxypropyl methacrylate) with polyvinylpyrrolidone

The miscibility behaviour and hydrogen‐bonding interaction in blends of poly(2‐hydroxypropyl methacrylate) (PHPMA) with polyvinylpyrrolidone (PVP) were characterized using differential scanning calorimetry and Fourier‐transform infrared spectra. This polymer blend was miscible over the whole composition range and an unusually large positive deviation of T_g from the linearity rule was observed, indicating strong hydrogen bonding between the hydroxyl group of PHPMA and the carbonyl group of PVP. Infrared spectroscopic analysis provided positive evidence for the intra‐molecular hydrogen bonding of PHPMA and inter‐molecular hydrogen bonding between PHPMA and PVP at various compositions and temperatures. Furthermore, equilibrium constants and enthalpies of self‐association and inter‐association between functional groups in the blend of PHPMA and PVP were calculated to explain the results. Copyright © 2004 Society of Chemical Industry     

A vision-aided automation system for destructive web thickness measurement of microdrills

Microdrills are fundamental cutting tools used in mechanical microdrilling. The web thickness of a microdrill is an important design parameter in balancing drill rigidity and chip removal ability. Conventional destructive method for measuring the web thickness is currently adopted by some microdrill manufactures. The conventional method must be carried out manually by experienced inspectors and thus lacks sufficient efficiency and accuracy. To improve the drawbacks of the conventional method, a vision-aided automation system for performing the destructive web thickness measurement is introduced in this paper. Based on the integration of motion and logic control, machine vision, and image processing techniques, an automated measuring process is then established. Experiments to measure the web thickness of microdrill samples were conducted to test the feasibility and effectiveness of the presented automation system and automated measuring process. The experimental results showed that the presented vision-aided automation system, in combination with the automated measuring process, could be an efficient and precise manner for replacing the conventional manual procedure in performing the destructive web thickness measurement of certain microdrills.     

Intermittent Process Measurement of a Freeform Surface Profile with a Circular Triangulation Laser Probe on a Machining Centre

This paper describes the development of a non-contact type system for measuring a freeform surface on a machine tool. A laser probe, model OTM-3A20 made by Wolf & Back Co., was integrated into a CNC machining centre as a non-contact sensor. An adjustment device for the laser probe was designed to minimise the cosine error caused by assembly inaccuracy. An alignment test of the measuring laser beam was carried out using a calibrated specimen. The systematic accuracy of the circular triangulation laser probe and a standard triangulation laser probe, with respect to the surface roughness, surface slope, and coating colour of the workpiece, was investigated by using an HP5529A laser interferometer system. The measuring system, which consists of a personal computer, a CNC controller of a machining centre, a Renishaw MP10 touch-trigger probe system, and the controller of the laser probe system, was integrated information-technically. Automatic measuring software was developed for the purpose of measuring path simulation, generation of NC codes, and error analysis of the measured data. The profile error of the tested object, measured by the laser probe and the coordinate measuring machine respectively was found to be within 45 μm. In this case, the tolerance of the designed part is about 50 μm, so the developed system can be applied to the inspection of mould production in bakelite according to the experimental results. ID="A1"Correspondance and offprint requests to: Dr Fang-Jung Shiou, Department of Mechanical Engineering, National Taiwan University of Science and Technology, No. 43, Section 4, Keelung Rd. 106 Taipei, Taiwan. E-mail: shiou@mail.ntust.edu.tw     

Modulating the ERK1/2–MMP1 Axis through Corosolic Acid Inhibits Metastasis of Human Oral Squamous Cell Carcinoma Cells

Corosolic acid (CA; 2α-hydroxyursolic acid) is a natural pentacyclic triterpenoid with antioxidant, antitumour and antimetastatic activities against various tumour cells during tumourigenesis. However, CA’s antitumour effect and functional roles on human oral squamous cell carcinoma (OSCC) cells are utterly unknown. In this study, our results demonstrated that CA significantly exerted an inhibitory effect on matrix metalloproteinase (MMP)1 expression, cell migration and invasion without influencing cell growth or the cell cycle of human OSCC cells. The critical role of MMP1 was confirmed using the GEPIA database and showed that patients have a high expression of MMP1 and have a shorter overall survival rate, confirmed on the Kaplan–Meier curve assay. In the synergistic inhibitory analysis, CA and siMMP1 co-treatment showed a synergically inhibitory influence on MMP1 expression and invasion of human OSCC cells. The ERK1/2 pathway plays an essential role in mediating tumour progression. We found that CA significantly inhibits the phosphorylation of ERK1/2 dose-dependently. The ERK1/2 pathway played an essential role in the CA-mediated downregulation of MMP1 expression and in invasive motility in human OSCC cells. These findings first demonstrated the inhibitory effects of CA on OSCC cells’ progression through inhibition of the ERK1/2–MMP1 axis. Therefore, CA might represent a novel strategy for treating OSCC.     

Anonymous authentication protocol based on elliptic curve Diffie–Hellman for wireless access networks

Anonymous channel tickets have been proposed as a way to provide user anonymity and to reduce the overhead of re‐authentication for authentication in wireless environments. Chen et al. proposed a secure and efficient protocol, based on a protocol proposed by Yang et al., which is resistant to guessing attacks on networks from which users’ secret keys are easy to obtain. However, their scheme is time‐consuming in the phases of ticket issuing and authentication. Furthermore, a malicious attacker can utilize the expired time, T_exp, to launch a denial of authentication (DoA) attack, which is a type of denial of service attack. Because T_exp is exposed to any user, it would be easy to launch a DoA attack that could make the scheme impractical. To resist against DoAs that the scheme of Chen et al. might suffer, we propose an improved scheme based on elliptic curve cryptography in this paper. Our scheme not only reduces time cost but also enhances security. The basis of the proposed scheme is the elliptic curve discrete logarithm problem. The operations of points of an elliptic curve are faster and use fewer bits to achieve the same level of security. Therefore, our scheme is more suitable for mobile devices, which have limited computing power and storage. Copyright © 2012 John Wiley & Sons, Ltd.     

Determination of Optimal Ball-Burnishing Parameters for Plastic Injection Moulding Steel

The objective of this study is to determine the optimal plane ball-burnishing parameters for plastic injection moulding steel PDS5 on a machining centre by utilising the Taguchi’s orthogonal array method. The design and manufacture of a burnishing tool are described. Four burnishing parameters, namely the ball material, burnishing speed, burnishing force and feed, were selected as the experimental factors in Taguchi’s design of experiments to determine the optimal burnishing parameters which have the dominant influence on surface roughness. The optimal burnishing parameters were found after carrying out the experiments specified by Taguchi’s L18 orthogonal table, by the analysis of variation, and by a full factorial experiment. The optimal plane burnishing parameters for the plastic injection moulding steel PDS5 were a combination of a tungsten carbide ball, a burnishing speed of 200 mm/min, a burnishing force of 300 N and a feed of 40 μm. The surface roughness Ra of the specimen can be improved from about 1 μm to 0.07 μm by using the optimal burnishing parameters for plane burnishing.     

Object recognition based on foreground detection using X-ray imaging

Development of effective terrorism-prevention techniques has assumed international importance since the 9/11 attacks. X-ray examination technology is a nondestructive screening method that enables the contents and internal structures of objects to be viewed without destroying the packaging or the external structures. Owing to its speed and efficiency compared to manual inspection, this technology is especially useful for the inspection of checked luggage and cargo, especially for inspecting items that cannot be disassembled. This paper presents developed training software for automated X-ray image recognition for checked luggage. To obtain the optimum classification result, an algorithm is designed using the C++ language. In Taiwan, the intensity of X-ray equipment is 10 times that of a typical X-ray baggage inspection machine. The use of reflected thermal neutrons in this equipment can reveal the presence of drugs, weapons, or explosives that are hidden in luggage. Using the Harris corner detection method and the speeded-up robust features (SURF) algorithm, the corner and feature points are obtained. In an evaluation, the proposed system uses a pattern-matching method and SURF to detect a 9-mm pistol. Compared to the results of a gun template image, the similarity obtained by the proposed method is increased by 0.85 to 1.81%.     

A simulation for the bulk polymerization of acrylonitrile

Abstract

In this paper, referring to the experimental observation of Thomas and Pellon, the authors consider the possible features of the development of the inter‐ and intra‐molecular forces of polymer and monomer molecules in the reaction mixture. Then, a critical chain length is proposed to be a criterion for the loci of polymerization for the polymer molecules. The polymer molecules formed initially exist and react in the solution phase. As soon as they attain a chain length longer than the critical chain length, they will separate from the solution phase, and continue their reaction in the precipitation phase by the diffusion‐controlled process. The chain transfer to monomer reaction is suggested as the deactivation reaction for the precipitated polymer radicals. In the kinetic treatment, the unsteady‐state condition is applied for the precipitation phase, while the steady‐state assumption is used for the solution phase.

Using the kinetic model proposed above, the authors provide the kinetic parameters for this acrylonitrile polymerization. The simulations of conversion‐time, rate‐conversion, and molecular weight‐conversion obtained fit excellently with the data of Hamielec et al. The critical chain length for this acrylonitrile system is found to be a function of the reaction temperature and the conversion.     

Development of a new meso-scale machine tool for fabricating micro V-grooves

This work presents the development of a meso-scale machine tool with a nanometer resolution. The newly developed meso-scale machine tool consists of a pagoda structure for Z-axis, four HR8 ultrasonic motors, three linear encoders with a resolution of 2 nm, a coaxial counter-balance system, a XY coplanar positioning stage, a rotary stage, a Galil 4-axis motion control card, an industrial PC and a CCD camera system. The optimal geometrical dimensions of the pagoda structure have been determined by ANSYS software. The designed meso-scale machine tool is equipped with an X–Y coplanar positioning stage with nanometer resolution. The coplanar stage developed by National Taiwan University was integrated with two linear encoders, so that a two-axis closed-loop control was possible. A circular positioning test with the radius of 1 mm using the developed stage was tested, and the overall circular positioning error was about 83 nm based on the test results. The micro V-grooves and the micro pyramid cutting tests of the polished oxygen free copper using a single crystal diamond tool on the developed meso-scale machine tool have been performed. The cutting tests under various combination of the depth of cut and cutting speed have been carried out. It revealed that the cutting speed had no great influence on the cutting force. The measured cutting forces for the depth of cut of 5, 10, 15 μm were 1.2, 1.6 and 2.4 N, respectively. The results showed the meso-scale machining tool can be used in micro pyramid structures manufacturing.