Bringing in the expert

Quality is king. Against a background of increasing post 1992 competition from our European partners and, perhaps even more important for the UK textile industry, the eventual abolition of the Multi-Fibre Arrangement, quality is one route to maintaining a competitive advantage. But, like all ruling monarchs, quality is expensive to maintain. It requires considerable financial investment, management resource and, once installed, continuous monitoring, re-evaluation, and updating.     

Influence of ZnCl2 on the structure and mechanical properties of polyacrylonitrile fibers

The structure and mechanical properties of polyacrylonitrile fibers containing small amounts of Zn²⁺ were investigated. It is possible to interpret the influence of ZnCl₂ on the fibers by diffusion. Fibers spun from spinning dope containing ZnCl₂ may have a denser and finer structure because ZnCl₂ in the spinning dope retards the coagulation rate. The tensile strength and modulus of the fibers are much improved because of the retardation of coagulation. It is probable that the complexation between Zn²⁺ and CN groups does not contribute to the improvement of the mechanical properties because the amount of ZnCl₂ added in a spinning dope is extremely small.     

Laparoscopically assisted vaginal hysterectomy

OBJECTIVE: To report our experience with laparoscopically assisted vaginal hysterectomy (LAVH) and evaluate the advantages of LAVH. STUDY DESIGN: From January 1991 to August 1992, 176 LAVHs were performed at the Department of Obstetrics and Gynecology, College of Medicine, Chung-Ang University, Seoul, Korea. The indications for LAVH, based on the preoperative diagnosis, were uterine myomas, dysmenorrhea, chronic pelvic inflammatory disease or pelvic pain, dysfunctional uterine bleeding and cervical intraepithelial neoplasia (in order of frequency). RESULTS: Patients had concomitant procedures, including incidental appendectomy, posterior wall repair, pelvic adhesiolysis and salpingo-oophorectomy. Bipolar forceps were used to compress and desiccate vessels. The Nd-YAG laser, scissors and/or unipolar electrode were used for tissue division, excision of adhesions and cutting. The intraoperative complications were bladder perforation, massive hemorrhage and inferior epigastric vessel injury (one case each). The postoperative complications were infection, voiding difficulty, febrile morbidity, pelvic abscess, incisional hernia, vaginal vault bleeding and peroneal nerve palsy (one case each). CONCLUSION: Hysterectomy can be safely performed vaginally assisted by operative laparoscopy by well-trained laparoscopists, resulting in reduced surgical morbidity, blood loss, postoperative discomfort, recovery time and hospitalization.     

Partial oxidation (POX) reforming of gasoline for fuel-cell powered vehicles applications

As a part of the development of a gasoline processor for integration with a proton-exchanged membrane (PEM) fuel cell, we carried out the POX reforming reaction ofiso-octane, toluene and gasoline over a commercial methane reforming catalyst, and investigated the reaction conditions required to prevent the formation of carbon and the effect of fuel constituents and sulfur impurities in gasoline. The H₂ and CO compositions increased with increasing reaction temperature, while those of CO₂ and CH₄ decreased. It is desirable to maintain an O/C molar ratio of more than 0.6 and an H₂O/C molar ratio of 1.5 to 2.0 for vehicle applications. It has been found that carbon formation in the POX reforming ofiso-octane occurs below 620 °C, whereas in the case of toluene it occurs below 640 °C. POX reforming of gasoline constituents led to the conclusion that hydrogen production is directly related to the constituents of fuels and the operating conditions. It was also found that the coke formation on the surface of catalysts is promoted by sulfur impurities in fuels. For the integration of a fuel processor with PEM fuel cell, studies are needed on the development of new high-performance transition metal-based catalysts with sulfur and coke-resistance and the desulfurization of fuels before applying the POX reformer based on gasoline feed.     

Artificial intelligence: A Far East perspective

Today the world's fastest economic growth area is in the Far East. Besides Japan, the four Small Dragons of Asia; Hong Kong, Singapore, South Korea and Taiwan are achieving very outstanding results in industry and trade. Their large foreign incomes will enable them to carry out substantial technology development programmes. An AI programme is certainly a possible candidate, considering Japan's Fifth Generation Project. This paper surveys the backgrounds of these Dragons from many perspectives: economical, cultural, political, historical ... and speculates on the future roles which AI may play in these nations. China, which has so many ties with these Dragons is also included in the discussion.     

A linear motor damper for vibration control of steel structures

A hybrid mass damper based on the linear motor principle is developed to suppress structural vibration. We will call it a linear motor damper in this paper. This paper deals with the design, analysis, and manufacture of the linear motor damper. It consists of the NdFeB permanent magnets, a coil-wrapped nonmagnetic hollow rectangular structure, an iron core, mechanical springs, and so on. It is designed to be able to move the auxiliary mass of 1500 kg, up to ±250 mm stroke. A series of performance tests for the linear mass damper with H_∞ robust controller are carried out on a steel frame structure. Through performance tests, it is confirmed that the developed hybrid mass damper has reliable feasibility as a control device for structural control. In addition, the linear motor damper is more economical than both hydraulic and electric motor driving mass damper with respect to simple structure and low maintenance cost.     

Quantum-well infrared phototransistor with pHEMT structure

A quantum-well infrared phototransistor with a pseudomorphic high-electron mobility transistor (pHEMT) structure is presented. The proposed phototransistor uses four periods of a GaAs/Al/sub 0.3/Ga/sub 0.7/As (50 /spl Aring//120 /spl Aring/) quantum-well absorption region, as well as an In/sub 0.15/Ga/sub 0.85/As quantum well conducting channel under the absorption layer. The phototransistor shows a large responsivity of 140 A/W around 6 /spl mu/m at 23 K (for a cutoff wavelength of 7.5 /spl mu/m). The relation between the photoconductive gain and the transconductance of the pHEMT structure is also investigated.     

The chemical and physical properties of electrochemically prepared polyaniline perchlorate (PAP)

Polyaniline perchlorate (PAP) was synthesized by electrochemical oxidation from 0.2 M aniline in acetonitrile solution containing 0.1 M tetraethylammonium perchlorate as supporting electrolyte. From polarographic and cyclic voltammetry results, the values of the half-wave potential (E_1/2), transfer coefficient (α), and number of electrons related to the electrode reaction (n) were calculated to be 825 mV, 0.894, and 1, respectively. The morphology of the PAP film was observed by using an SEM analyzer. From thermal analysis of the PAP sample, the reaction rate (R) for its thermal decomposition was obtained from the TGA result and a exothermic peak at 330°C was also observed in the DSC curve. The electrical conductivity of the PAP pellet was measured at temperatures from ?170 to 25°C. From a plot of conductivity vs. 1/T, the activation energy (E_a) was obtained to be 0.14 eV. The conduction mechanism in a pressed pellet of PAP is suggested to be electronic hopping conduction. The values of the ESR parameters were calculated from an ESR curve for PAP at room temperature.     

Comparison of compressive deformation of ultrafine-grained 5083 Al alloy at 77 and 298 K

The compression behaviors of well-annealed coarsegrained (CG) and ultrafine-grained (UFG) 5083 Al alloys at 77 and 298 K were compared. For the CG alloy, stage II and III strain hardening were dominant at 77 and 298 K, respectively, depending on the completeness of dislocation cell formation. The UFG alloy exhibited the elastic-near perfectly plastic behavior without distinctive dislocation cell formation at both temperatures. For both alloys, the flow stress at 77 K was much higher than that at 298 K. This work was supported by the Basic Research Program (Grant No. R01-2003-000-10202-0) of the Korea Science & Engineering Foundation.     

Correlative High‐Resolution Mapping of Strain and Charge Density in a Strained Piezoelectric Multilayer

A key to strain engineering of piezoelectric semiconductor devices is the quantitative assessment of the strain‐charge relationship. This is particularly demanding in current InGaN/GaN‐based light‐emitting diode (LED) designs as piezoelectric effects are known to degrade the device performance. Using the state‐of‐the‐art inline electron holography, we have obtained fully quantitative maps of the two‐dimensional strain tensor and total charge density in conventional blue LEDs and correlated these with sub‐nanometer spatial resolution. We show that the In_0.15Ga_0.85N quantum wells are compressively strained and elongated along the polar growth direction, exerting compressive stress/strain on the GaN quantum barriers. Interface sheet charges arising from a polarization gradient are obtained directly from the strain data and compared with the total charge density map, quantitatively verifying only 60% of the polarization charges are screened by electrons, leaving a substantial piezoelectric field in each In_0.15Ga_0.85N quantum well. The demonstrated capability of inline electron holography provides a technical breakthrough for future strain engineering of piezoelectric optoelectronic devices.