Intermolecular and intramolecular hydrogen bonding of poly(dimethylsiloxane)urethane‐graft–poly(methyl methacrylate) copolymers based on 2,4‐TDI and m‐XDI

In this study, poly(dimethylsiloxane)urethane–graft–poly(methyl methacrylate) (PDMS urethane–g–PMMA) copolymers with low crosslinking density were synthesized. Glass transition temperatures of the copolymers were investigated by dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC). Results confirm that PDMS urethane–g–PMMA is miscible in the 2,4‐TDI (2,4‐ toluene diisocyanate) system, whereas it is partially miscible in the m‐XDI (m‐xylene diisocyanate) system. Free, intra‐ (urethane–urethane), and inter‐ (urethane–ester) association hydrogen bonding exist in the urethane group of copolymers. The inter‐association hydrogen bonding can improve the compatibility of the copolymer components. The relationship between the frequency shift and enthalpy confirm the distribution of hydrogen bonding in the macromonomer and copolymer. Ninety percent of the hydrogen bonding is by interassociation in the 2,4‐TDI system. The intra‐association hydrogen bonding in the m‐XDI system is higher than that in the 2,4‐TDI system. Consequently, aggregation may occur easily in the siloxane‐grafted chain in the m‐XDI system. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 962–972, 2002     

Oviposition repellents of mosquitoes: Negative responses elicited by lower aliphatic carboxylic acids

Organic infusions have been shown to elicit discriminatory responses in ovipositing mosquitoes. Previously, we found that a Purina® Lab Chow infusion induces negative oviposition behavior inCulex pipiens quinquefasciatus Say andCulex tarsalis Coquillett. Six aliphatic carboxylic acids isolated from the active fraction of this infusion were acetic, propionic, isobutyric, butyric, isovaleric, and caproic. In the present studies, we have quantified the negative oviposition responses ofCulex mosquitoes to these carboxylic acids in a laboratory bioassay system and have also tested the main acid component, butyric acid, againstCuliseta, Aedes, andAnopheles mosquitoes.     

ROBOT SCHEDULING IN A CIRCUIT BOARD PRODUCTION LINE:A HYBRID OR/ANN APPROACH

A hybrid method that combines human intelligence, an optimization technique (semi-Markov decision model) and an artificial neural network to solve real-time scheduling problems is proposed. The proposed method consists of three phases: data collection, optimization, and generalization. The testbed of this approach is the robot scheduling problem in a circuit board production line where one overhead robot is used to transport jobs through a line of sequential chemical process tanks. Because chemical processes are involved in this production system, any mistiming or misplacing will result in defective jobs. The proposed hybrid system performs better than the human scheduler from whom the models were formulated, both in terms of productivity and quality.     

A comparative study of the coated filler method and the admixture method of powder metallurgy for making metal–matrix composites

Copper–matrix composites were made by powder metallurgy (PM). The reinforcements were molybdenum particles, silicon carbide whiskers and titanium diboride platelets. The coated filler method, which involves a reinforcement coated with the matrix metal, was used. In contrast, conventional PM uses the admixture method, which involves a mixture of matrix powder and reinforcement. For all the composite systems, the coated filler method was found to be superior to the admixture method in providing composites with lower porosity, greater hardness, higher compressive yield strength, lower coefficient of thermal expansion (CTE), higher thermal conductivity and lower electrical resistivity, though the degree of superiority was greater for high than low reinforcement contents. In the coated filler method, the coating on the reinforcement separated reinforcement units from one another and provided a cleaner interface and stronger bond between reinforcement and matrix than the admixture method could provide. The highest reinforcement content attained in dense composites (<5% porosity) made by the coated filler method was 70 vol% Mo, 60 vol% TiB2 and 54 vol% SiC. The critical reinforcement volume fraction above which the porosity of composites made by the admixture method increases abruptly is 60% Mo, 42% TiB2 and 33% SiC. This fraction increases with decreasing aspect ratio of the reinforcement. Among Cu/Mo, Cu/TiB2 and Cu/SiC at the same reinforcement volume fraction (50%), Cu/Mo gave the lowest CTE, highest thermal conductivity and lowest electrical resistivity, while Cu/SiC gave the greatest hardness and Cu/TiB2 and Cu/SiC gave the highest compressive yield strength. Compared to Cu/SiC, Cu/TiB2 exhibited much higher thermal conductivity and much lower electrical resistivity. This revised version was published online in November 2006 with corrections to the Cover Date.     

Human-centric product conceptualization using a design space framework

Designing products to fit human needs, preferences and capabilities is an essential key to competitiveness. In contested product markets, the management of user-related knowledge is therefore critical. Studies have shown that the identification and implementation of user requirements are significant issues for determining successful product development, especially during the conceptual design phase. User requirements represented in a single or limited level of abstraction is inadequate for effective incorporation into the conceptual design process. Such representation of user needs is argued here to be associated with issues such as the errors of problem framing, which is a cause of inadmissible, uncreative or sub-optimal designs. In this paper, a human-centric knowledge organization structure, Design Space Framework, is established to facilitate the consistent incorporation of user information into the length of the product conceptualization process. The role of this structure in human-centric design is illustrated in a case study.     

Angular-interrogation attenuated total reflection metrology system for plasmonic sensors

We develop an angular-interrogation attenuated total reflection (ATR) metrology system for three different plasmonic sensors, namely, a conventional surface plasmon resonance (SPR) device, a coupled-waveguide SPR device, and a nanoparticle-enhanced SPR device. The proposed metrology system is capable of measuring the reflectivity spectra of the transverse magnetic mode and the transverse electric mode simultaneously. Through the optimal control of the fabrication process and use of sophisticated system instrumentation, the experimental results confirm that the developed ATR system is capable of measuring the resonant angle with an angular accuracy of 10(-4) deg.     

Attractants for synanthropic flies

Fermented molasses or sucrose solutions are known to attract several species of filth-breeding flies. To identify the volatile attractants produced in fermenting sucrose solutions with yeast, these solutions were fractionated, and the chemical constituents identified and bioassayed against filth-breeding flies includingFannia canicularis (L.),Muscina stabulans (Fallén), andMusca domestica (L.). Distillation of a fermented sucrose solution gave an active distillate and an inactive residue. Gas Chromatographic analysis of the distillate showed the presence of acetaldehyde, ethyl acetate, ethanol, 1-pro-panol, 2-methyl-l-propanol, and 3-methyl-l-butanol. Ethanol constituted by far the greatest proportion of compounds present in the distillate. An aqueous solution of ethanol exhibited the same level of attractancy as the distillate, the fermented sucrose solution, and a reconstituted distillate containing all compounds identified. Ethanol was thus identified as the sole attractant emanated from fermented carbohydrate solutions that elicited positive responses in pest flies, especially inF. canicularis.Diptera: Muscidae.     

Novel copolyesters containing naphthalene structure III. Copolyesters prepared from 2,6‐dimethyl naphthalate,ethylene glycol,and 2,2‐dialkyl‐1,3‐propanediols

Poly(ethylene naphthalate) (PEN) copolymers were prepared by melt polycondensation of dimethyl naphthalate and excess ethylene glycol with 5–40 mol % (in feed) of 1,3‐propanediol or 2,2‐dialkyl‐1,3‐propanediols, where the dialkyl groups are dimethyl, diethyl, and butyl‐ethyl. No significant depression of reduced specific viscosity was observed. The comonomer contents in the copolymers are considerably higher than those in the feed. The effects of the copolymer composition on the structures of the films were investigated using thermal analyses, density measurements, X‐ray diffraction methods, and other physical tests. The crystallinities and densities of heat‐treated films decreased with increasing content of comonomer and length of alkyl side chain in the comonomer. The glass transition temperature (T_g) and melting temperature (T_m) were decreased by the copolymerization, while an increase in the length of the alkyl side chain hardly affected T_ms of the heat‐treated films. Alkali resistance, moisture resistance, dye ability, and thermal shrinkage were increased by the incorporation of comonomer having an alkyl side chain. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2754–2763, 2001     

Comprehensive evaluation of industrial CO2 emission (1989–2004) in Taiwan by input–output structural decomposition

Taiwan currently emits approximately 1% of the world's CO₂—ranking it 22nd among nations. Herein, we use the input–output (I–O) structural decomposition method to examine the changes in CO₂ emission over a 15-year period. By decomposing the CO₂ emission changes into nine factors for the periods of 1989–1994, 1994–1999, and 1999–2004, we have identified the key factors causing the emission changes, as well as the most important trends regarding the industrial development process in Taiwan. The 5-year increment with the largest increase of CO₂ emission was that of 1999–2004, due to the rapid increase of electricity consumption. From the decomposition, the industrial energy coefficient and the CO₂ emission factors were identified as the most important parameters for the determination of the highway, petrochemical materials, iron and steel, the commercial sector, and electric machinery as the major sources of increased CO₂ emission during the past 15 years. From 1989 to 2004, the level of exports and the level of domestic final demand were the largest contributors to the increase in the total increment of CO₂ change. During 1989–2004, the industrial energy coefficient and CO₂ emission factors, being minimally significant during 1989–1994, became extremely important, joining the domestic final demand and the level of exports factors as the major causes of the increase increment of CO₂. This indicates a heavy reliance upon high-energy (and CO₂) intensity for Taiwanese industries; therefore, continuous efforts to improve energy intensity and fuel mix toward lower carbon are important for CO₂ reduction, especially for the electricity and power generation sectors. Relevant strategies for reducing carbon dioxide emissions from major industries are also highlighted.     

Integrated software safety analysis method for digital I&C systems

The digitalized Instrumentation and Control (I&C) system of Nuclear power plants can provide more powerful overall operation capability, and user friendly man-machine interface. The operator can obtain more information through digital I&C system. However, while I&C system being digitalized, three issues are encountered: (1) software common-cause failure, (2) the interaction failure between operator and digital instrumentation and control system interface, and (3) the non-detectability of software failure. These failures might defeat defense echelons, and make the Diversity and Defense-in-Depth (D3) analysis be more difficult. This work developed an integrated methodology to evaluate nuclear power plant safety effect by interactions between operator and digital I&C system, and then propose improvement recommendations. This integrated methodology includes component-level software fault tree, system-level sequence-tree method and nuclear power plant computer simulation analysis. Software fault tree can clarify the software failure structure in digital I&C systems. Sequence-tree method can identify the interaction process and relationship among operator and I&C systems in each D3 echelon in a design basis event. Nuclear power plant computer simulation analysis method can further analyze the available backup facilities and allowable manual action duration for the operator when the digital I&C fail to function. Applying this methodology to evaluate the performance of digital nuclear power plant D3 design, could promote the nuclear power plant operation safety. The operator can then trust the nuclear power plant than before, when operating the highly automatic digital I&C facilities.