Design of Self-Tuning PID Power System Stabilizers for Synchronous Generators

A new technique for the excitation control of a synchronous generator is presented in this paper. The proposed technique employs a self-tuning proportional-integral-derivative (PID) power system stabilizer in order to improve the dynamic performance of a synchronous machine under a wide range of operating condition. Digital simulation of a synchronous machine subject to a major disturbance of a three phase fault under different operating conditions is performed to demonstrate the effectiveness of the proposed controller. It is found that the self-tuning PID stabilizer can enhance both the transient stability and the dynamic performance of the synchronous machine.     

Heat transfer in a smooth-walled reciprocating anti-gravity open thermosyphon

This paper describes an experimental investigation of heat transfer in a smooth-walled reciprocating anti-gravity open thermosyphon with relevance to the ‘shaker’ cooling system for the pistons of marine propulsive diesel engines. A selection of experimental results illustrates the interactive effects of inertial, reciprocating and buoyancy forces on heat transfer. It is demonstrated that the gravitational and reciprocating buoyancy effects, respectively, improve heat transfer in the static and reciprocating anti-gravity open thermosyphon. The individual pulsating force effect impairs heat transfer in the axial region with 5 hydraulic diameter length measured from the entrance of thermosyphon (region I). In the vicinity of sealed end of reciprocating thermosyphon with one hydraulic diameter from the sealed surface (region II), the individual pulsating force effect improves heat transfer at low pulsating number range, over which range a subsequent heat transfer reduction in this axial region is followed. The synergistic effects of inertial force, reciprocating force and buoyancy interaction in the reciprocating anti-gravity open thermosyphon could, respectively, impede or improve the regional heat transfers in the axial regions I and II from the static references of zero-buoyancy. A set of empirical correlations, which is physically consistent, was developed that permits the individual and interactive effects of inertial, reciprocating and buoyancy forces on heat transfer to be evaluated.     

The chaperonin containing TCP-1 (CCT) displays a single-ring mediated disassembly and reassembly cycle

A prospective study of 40 shoulder arthroplasties in patients with rheumatoid arthritis was performed to evaluate the results of rotator cuff repair at the time of arthroplasty. A large cuff tear was present in 21 shoulders, and good repair of the cuff was performed in 9. In the other shoulders the repair was considered insufficient. All patients were clinically evaluated using the Hospital for Special Surgery 100-point scoring system. The minimum follow-up period for inclusion in this study was 2 years. The quality of the repair of the ruptured cuff at the time of surgery had a significant influence on the postoperative clinical score (linear regression model, P = .002). The clinical score of the shoulders with good repair of the rotator cuff improved considerably and continued to improve even after the first-year follow-up examination. Meticulous repair of the ruptured cuff at the time of arthroplasty is recommended.     

Occupational disease profile in Taiwan, Republic of China

Lack of knowledge of the exact contents of the materials and improper handling of the toxic chemicals lead to the occurrence of occupational illnesses in the developing countries. However, the incidence of occupational diseases was usually underestimated. This article presents the profile of occupational diseases in Taiwan from two sources, i.e. occupational disease benefit payments of labor insurance and the review of relevant literature. The primarily documented occupational diseases in Taiwan were pneumoconioses. The second most common occupational disease was carbon monoxide intoxication, followed by lead poisoning and noise-induced hearing loss. Less than five percent of occupational diseases were due to the other causes, including decompression syndrome, heat stroke, toxic hepatitis, neurological disorders and hematologic disorders. The number of occupational diseases recognized in Taiwan was considered to be seriously underestimated due to the shortage of occupational medical specialists. Priority in the development of occupational medicine in Taiwan is to educate industrial hygienists and physicians to recognize health hazards in the work environment and to diagnose occupational diseases. Recognition of occupational diseases could subsequently highlight the health hazards in the workplace and prevent workers from overexposure.     

Differential regulation of discrete apoptotic pathways by Ras

The products of the ras genes are known to regulate cell proliferation and differentiation; recently, they have been found to play a role in apoptosis. The expression of oncogenic p21(ras) in a number of cell types, including Jurkat (a human T lymphoblastoid cell line) and murine fibroblasts, makes the cells susceptible to apoptosis following suppression of protein kinase C (PKC) activity (PKC/Ras-mediated apoptosis). Engagement of Fas antigen, a potent effector of apoptosis, activates cellular p21(ras), which may be required for completion of the cell death program. To further investigate the role of p21(ras) in the regulation of apoptosis, the cellular mechanisms employed in these two apoptotic processes in which Ras activity is involved (PKC/Ras-related and Fas-triggered apoptosis), was explored. Increasing p21(ras) activity by expressing v-ras or by treatment with an antisense oligonucleotide to the GTPase-activating protein was found to accelerate the Fas-mediated apoptotic process in Jurkat and mouse LF cells. PKC/Ras-related apoptosis was associated with, and required, cell cycle progression, accompanied by the expression of the G1/S cyclins. In contrast, Fas engagement, although inducing a vigorous and PKC-independent activation of endogenous p21(ras), did not alter cell cycle progression, nor did it require such progression for apoptosis. Both the protein synthesis inhibitor cycloheximide and cyclin E antisense oligonucleotides partially abolished PKC/Ras-mediated apoptosis but had only a moderate effect on Fas-induced apoptosis. In contrast, the CED-3/interleukin-1beta-converting enzyme (ICE) protease inhibitor Z-VADfmk efficiently suppressed Fas-induced apoptosis and only marginally inhibited PKC/Ras-mediated apoptosis. Induction of both pathways resulted in activation of the Jun NH2-terminal kinase/JUN signaling system. These results suggest that different cell death programs, such as PKC/Ras-mediated and Fas-mediated apoptosis, may be interconnected via p21(ras) and perhaps Jun NH2-terminal kinase/JUN. In response to various death stimuli, p21(ras) may act as a common intermediate regulator in the transduction of apoptotic signals.     

复合材料综合信息查询系统的研究

信息、生物技术和新材料已成为2l世纪最重要、最有发展潜力的领域。复合材料的发展同样也面临着巨大的机遇和挑战。随着市场环境的不断变化，其信息量也在日趋复杂。在信息处理方面，不仅要求其准确性、完整性．更要求其时效性，传统的手工处理方式难以胜任这一要求，本文正是基于这一前提，将我国玻璃钢事业四十年来所取得的丰硕成果与计算机技术相结合，研制开发了功能较齐全的复合材料综合信息查询系统。     

Amniotic fluid alpha-fetoprotein levels during midtrimester of trisomy pregnancies

To investigate the association between low amniotic fluid alpha-fetoprotein (AFP) and trisomy pregnancies, we retrospectively reviewed 26 trisomy pregnancies including 18 fetuses with Down's syndrome and eight with trisomy 18. The amniotic fluid AFP median values of Down's syndrome, trisomy 18, and the study groups were 0.73 MoM, 1.15 MoM, and 0.85 MoM, respectively. There was a significant difference between the mean values of the Down's syndrome-affected fetuses (0.78 +/- 0.29 MoM) and that of the control group (p < 0.001), whereas no such difference was found for that of trisomy 18-affected fetuses (1.16 +/- 0.38 MoM). Only three patients in the study group (3/26, 11.5%) had an amniotic fluid AFP value below 0.5 MoM, including the two cases of Down's syndrome (2/18, 11.1%) and one case of trisomy 18 (1/8, 12.5%). Most of the values for the trisomy pregnancies were within the normal range, thereby precluding the possibility of using this measurement as an alternative to fetal karyotyping as a screening test for Down's syndrome or other trisomy pregnancies.     

The correlation between skin electrical conductance and the score of qi vacuity

In traditional Chinese medicine, the syndrome of qi vacuity means that the patient's body has a low level of energy to react to stress. Recently, we used a score, the QV score, by scaling the severity of symptoms and signs of qi vacuity in patients with tiredness. The aim of this study was to investigate the relationship between QV score and skin electrical conductance in patients with tiredness. One hundred and forty-three healthy controls and 103 patients with tiredness were involved. Each subject received a weak electrical stimulation with constant voltage (1.75 volt), and conductance was measured between two different limbs. The mean value of skin conductance among four limbs was calculated and expressed by a special unit, namely Chin. The correlation between the skin conductance and QV score was analyzed by a linear regression analysis. The results showed that skin electrical conductance of healthy controls was negatively correlated with age (r-coefficient = -0.51, P = 0.000). The skin conductance of patients with tiredness was significantly lower than that of healthy controls with matching age (P = 0.000 by Student's t-test). Moreover, there was a positive correlation between the decrease of skin conductance and the QV score in patients with tiredness (r-coefficient = +0.68, P = 0.000). These results suggest that a decrease in skin electrical conductance may be closely related to the severity of qi vacuity. The skin conductance test is a simple, reliable, and quantitative method for detection of syndrome of qi vacuity.     

X-ray synthesis of nickel–gold composite nanoparticles

We developed a novel approach to prepare Ni–Au composite nanoparticles using synchrotron radiation X-rays. Ni–Au particles dispersed in aqueous solutions were synthesized with two different irradiation strategies. The first is by exposing to X-rays a mixed electroless solution of Ni and Au at two different temperatures, trying to nucleate Ni nanoparticles homogeneously at room temperature and to deposit Au subsequently on them at the high temperature of 70 °C. The second strategy is to change the pH value of the mixed solution, directly leading to the formation of Ni–Au nanoparticles. In both cases, the Ni–Au composite nanoparticles were successfully formed, as confirmed by the observed ferromagnetic behavior and by the evolution of the Au surface plasmon resonance band.