Coating films prepared by photoreactions of the surface‐modified diamond powder and PET film with a binder agent

The surface‐modified diamond and PET film underwent photopolymerization rapidly with a binder agent to afford coating films of interpenetrating network (IPN) structure. The coating films thus formed exhibit higher tensile strength, thermal stability, and adhesion strength to the PET film. The inert surfaces of pristine diamond (PD) and PET film were modified by different chemicals and procedures to introduce epoxide and methacryloyl groups, respectively, on their surfaces. A coating agent consisting of an epoxide group containing modified diamond (called ED), a binder agent, and photoinitiators was prepared. After applying the coating agent to the substrate (a glass plate or a methacryloyl group containing PET film, MMA‐PET) and degassing under reduced pressure, the thin film of the coating agent was exposed to UV light (λ_max; 365 nm) at room temperature to yield a coating film of IPN‐structure. The tensile strength and thermal properties of the ED‐containing free coating film (called free film) increased with the amount of ED embedded, whereas the strength of the PD‐containing free film decreased with the amount of PD embedded. The adhesion strength of the coating film on the MMA‐PET improved significantly by the free radical polymerization of the methacryloyl groups on the MMA‐PET and the acrylate resin in the binder agent. The surface photoreactions of ED and MMA‐PET with the binder agent were confirmed by modeling. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Effect of electrical discharge machining on the characteristics of carbon fiber reinforced carbon composites

This work investigated electrical discharge machining (EDM) of carbon fiber reinforced carbon composite material. The characteristics of composites machined by EDM were studied in terms of machining parameters. An empirical model of the composites was also proposed based on the experimental data. The composite material was produced by an electrical discharge sinker using a graphite electrode. The workpiece surface and resolidified layers were examined by scanning electron microscopy (SEM). Moreover, surface roughness was determined with a surface profilometer. Experimental results indicate that the extent of delamination, thickness of the recast layer, and surface roughness are proportional to the power input. The EDM process effectively produces excellent surface characteristics and high quality holes in composites under low discharge energy conditions.     

The Feasibility Analysis of Electrical-Discharge Machining of Carbon-Carbon Composites

The objective of this research is to investigate the feasibility of using Electrical-Discharge Machining (EDM) for carbon-carbon composite materials as well as the effects of major machining parameters. The material was machined by electrical-discharge sinker using copper electrode. The mechanism of material removal has been revealed by the morphology of debris. The material removal rate, the surface topography and the recast layer that remains on the workpiece surface were studied in terms of EDM processing variables (e.g., pulse current and pulse duration time). The machined surface showing resolidification was examined by Scanning Electron Microscopy (SEM). A qualitative energy dispersive spectroscopic analyzer was used to measure the amount of migrated alloy in the workpiece and the chemical composition of recast layer. The machining damage, the recast layer, and the mass transfer was proportional to the power input. The EDM process is a feasible method for machining of carbon-carbon composites.     

An accelerated approach for solving fuzzy relation equations with a linear objective function

In literature, the optimization model with a linear objective function subject to fuzzy relation equations has been converted into a 0-1 integer programming problem by Fang and Li (1999). They proposed a jump-tracking branch-and-bound method to solve this 0-1 integer programming problem. In this paper, we propose an upper bound for the optimal objective value. Based on this upper bound and rearranging the structure of the problem, we present a backward jump-tracking branch-and-bound scheme for solving this optimization problem. A numerical example is provided to illustrate our scheme. Furthermore, testing examples show that the performance of our scheme is superior to the procedure in the paper by Fang and Li. Several testing examples show that our initial upper bound is sharp.     

Analysis of wear behaviour of titanium carbonitride coatings

The kinetics of chemical reactions occurring during the coating process and the wear behaviour of Ti(C,N) coatings, including variations in wear displacement with the temperature of the lower specimen, were investigated in this work. The variations in the wear displacement and the temperature of the lower specimen are regressed by an eight-order polynomial function. The lower specimens were coated by a titanium film as underlayer and three kinds of coating material including TiN, Ti(C,N) or TiC were deposited as the top layer. The Ti(C,N) coatings were prepared by varying the gas flow rates of nitrogen and acetylene to form eight kinds of specimen. The tribological behaviour demonstrated by these eight specimens is discussed. The experimental data for the atomic ratios of [C] and [N] can be well expressed using the theory of diffusion rate and the theory of reaction rate for the deposition of ceramic coatings. The variations in the wear displacement gradient with the temperature of the lower specimen can give information on the adhesive behaviour arising before and after three-body wear. The wear rates of the upper and lower specimens due to adhesive wear are dependent on the operating conditions. The specimen with a higher final wear displacement was likely to produce on the upper specimen a higher wear rate when operating at 0.705 m s⁻¹. The thicker the adhesive layer, the lower the wear rate of the lower specimen produced. When the sliding speed was elevated to 1.41 m s⁻¹, the specimen with a higher final wear displacement often produced a lower wear rate on the upper specimen, and also caused higher wear rates on the lower specimens.     

On the asymptotic stability of free fuzzy systems

It has been shown by Thathachar and Viswanath (ibid., vol.5, p.145-51, 1997) that the stability of Takagi and Sugeno's fuzzy system is equivalent to that of a corresponding switching system with finite number of characteristic matrices. In this correspondence, we shall correct a false proof of a result in Thathachar and Viswanath     

Study of the Effect of Machining Parameters on the Machining Characteristics in Electrical Discharge Machining of Fe-Mn-Al Alloy

In this work we investigated the electrical discharge machining (EDM) of a Fe-Mn-Al alloy. The surface phenomena caused by EDM were studied in terms of machining parameters. An empirical model of the Fe-Mn-Al alloy was also proposed based on the experimental data. Experimental results indicate that the higher the discharge energy, the faster the machining time. This treatment introduces machining damage in the resolidified surface layer and worsens the surface roughness. The optimum pulse-on duration on the basis of the electrode wear ratio for the copper electrode was about 200 μs. The increase of crater depth with the applied pulsed current and pulse-on duration appears minimal under a small input energy.     

Simple parameter estimation technique in manoeuvring target tracking system

The measurement noise in a manoeuvring target tracking system is significantly correlated for high measurement frequencies. If some correlation parameters are unknown, a complicated procedure is usually required further estimation. A simple estimation technique is presented when the manoeuvre detection method is used for tracking the target.<>     

Study of Piezoelectrically Actuated Micropumps with Multiple Parallel Chambers

This study investigated the performance of the piezoelectrically actuated parallel micropumps. The displacement of the piezoelectric (PZT) actuator and the flow rate of the micropump were studied in terms of operating parameters. Using a nonlinear regression technique, empirical models of the micropumps were established based on the experimental data. The experimental results indicated that the displacement of the piezoelectric actuator increased with actuating voltage but decreased with frequency. The flow rate of the micropump was proportional to the applied voltage and demonstrated that the maximum flow rate occurred at an adequate frequency. When operated at a voltage of 140 V and a frequency of 20 Hz, the single micropump delivered a maximum flow rate of 91 µ 1/min. At the same input signal, the maximum flow rate of the double parallel micropump was 1.5 times that of the single micropump, and approximately twice that of the single micropump for triple parallel operation. Furthermore, the obtained non-linear regression formulae can be utilized to predict the flow rate of the micropump with multiparallel chambers.     

The performance analysis of a concatenated ARQ scheme using parityretransmissions

The authors analyze an ARQ (automatic repeat request) scheme using parity retransmissions. By dividing each transmission block into subblocks, the combination of a transmission block and its retransmission block has the structure of a concatenated code. They derive formulae for calculating an upper bound on the probability of undetected errors and a lower bound on the throughput for such an ARQ scheme. Numerical results show that even with extremely simple code design, such an ARQ scheme has satisfactory performance