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Your search keyword '"Chen, K.K."' showing total 47 results
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47 results on '"Chen, K.K."'

5. A linear programming method for the scheduling of pumped-storage units with oscillatory stability constraints

Author

Jeng, Lin-Her, Hsu, Yuan-Yih, Chang, B.S., and Chen, K.K.

Subjects
Pumped storage power plants -- Management, Linear programming -- Usage, Scheduling (Management) -- Case studies, Business, Electronics, Electronics and electrical industries
Abstract

Scheduling of pumped-storage units at Taiwan Power Company (TPC) is investigated in this work. In addition to economic considerations, oscillatory stability of the system as affected by the operation of pumped-storage units is of major concern. To achieve a secure as well as economical dispatching schedule for the pumped-storage units, differential dynamic programming is first employed to reach a preliminary schedule in which total fuel cost of the thermal units over the study period is minimized. Oscillatory stability analysis of the system under the preliminary schedule is then performed by computing the eigenvalues and eigenvectors for all electromechanical modes. Sensitivities of the eigenvalues for the poorly-damped inter-area mode with respect to individual generator outputs are evaluated. Then a systematic approach based on linear programming is presented to refine the preliminary schedule in order to improve the damping for the inter-area mode. The effectiveness of the proposed approach is demonstrated by short term operational planning of Taiwan power system. keyword: power system operational planning, hydro scheduling, pumped-storage unit, oscillatory stability, low frequency oscillations, linear programming

Published
1996

14. Efficient near-infrared supercontinuum generation in tellurite holey fiber pumped 320nm within the normal dispersion regime

Author

Shi, J.D., Feng, X., Chen, K.K., Teh, P.S., Horak, P., Lin, Dejiao, Alam, S.-U., Loh, W.H., Richardson, D.J., and Ibsen, M.

Abstract

We demonstrate the generation of a 1.1-1.7µm supercontinuum in a 1.3m long air suspended-core tellurite holey-fiber with a nominal zero-dispersion wavelength of ~1.38µm. The fiber is pumped at 1.06µm with a 20ps pulsed fiber laser. The high Raman gain-coefficient of tellurite glass is attributed a key role in the supercontinuum generation.

Published
2010

15. Picosecond fiber MOPA pumped supercontinuum source with 39W output power

Author

Chen, K.K., Alam, S.-U., Price, J.H.V., Hayes, J.R., Lin, Dejiao, Malinowski, A., Codemard, C., Ghosh, D., Pal, M., Bhadra, S.K., and Richardson, D.J.

Abstract

We report picosecond fiber MOPA pumped supercontinuum source with 39W output, spanning at least 0.4-1.75 µm with high and relatively uniform spectral power density of ~31.7mW/nm corresponding to peak power density of ~12.5W/nm in 20ps pulse.

Published
2010

17. Recent advances in microstructured fibers for laser delivery and generation

Author

Hayes, J.R., Petrovich, M.N., Poletti, F., Horak, P., Broderick, N.G.R., Feng, Xian, Dasgupta, S., Loh, Wei H., Ghosh, Debashri, Pal, Mrinmay, Bhadra, Shyamal K., Chen, K.K., Price, J.H.V., Alam, S.U., and Richardson, D.J.

Subjects
Physics::Optics, Astrophysics::Galaxy Astrophysics
Abstract

We report recent advances in the development of fibers for the delivery and generation of both single-mode and heavily multimode laser beams as well as recent progress in fibers for supercontinuum generation in spectral regimes spanning the visible to mid-IR.

Published
2010

18. High-power supercontinuum generation with picosecond pulses

Author

Horak, P., Chen, K.K., Alam, S.-U., Dasgupta, S., and Richardson, D.J.

Subjects
Physics::Optics
Abstract

We investigate both theoretically and experimentally the properties of supercontinuum generation in the nearinfrared and visible regimes using high-power picosecond pulses propagating in a photonic crystal optical fiber. We discuss the effect of the pump wavelength relative to the fiber zero-dispersion wavelength on the conversion efficiency of pump power to shorter wavelengths. Finally, we consider picosecond supercontinuum generation in the presence of a mode cutoff when the pump is launched into a higher order fiber mode.

Published
2010

21. Current research and future therapies

Author

Andersson, K.E., Burnett, A.L., Chen, K.K., Christ, G.J., Rampin, Olivier, Stief, C., Unité de recherches neurobiologie des fonctions végétatives, Institut National de la Recherche Agronomique (INRA), and ProdInra, Migration

Subjects
[SDV] Life Sciences [q-bio], [SDV]Life Sciences [q-bio], DYSFONCTIONNEMENT, ComputingMilieux_MISCELLANEOUS
Abstract

National audience

Published
1999

37. Involvement of L-arginine/nitric oxide pathway at the paraventricular nucleus of hypothalamus in central neural regulation of penile erection in the rat.

Author

Chen, K.K. and Chang, L.S.

Subjects
*ARGININE, *NITRIC oxide, *PENIS
Abstract

Investigates whether the L-arginine/nitric oxide pathway is involved in the neurotransmission of paraventricular nucleus of hypothalamus activation-induced penile erection in the rat. Cannulation of the femoral artery; Measurement of systemic and mean arterial pressure; Measurement of intracavernous pressure.

Published
2002
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38. Adjuvant Methotrexate, Vinblastine and Cisplatin Chemotherapy for Invasive Transitional Cell Carcinoma: Taiwan Experience

Author

Wei, C.H., Hsieh, R.K., Chiou, T.J., Chen, K.K., Chang, L.S., and Chen, P.M.

Abstract

Purpose: The feasibility of adjuvant cisplatin, methotrexate and vinblastine chemotherapy was evaluated in Taiwanese patients with invasive transitional cell carcinoma at high risk for recurrence. Materials and Methods: We assigned 56 patients with high risk transitional cell carcinoma (vascular or lymphatic invasion in the primary tumor, poorly differentiated stage P2, P3, P4 or N + and M0) to receive adjuvant chemotherapy after radical urological surgery. The chemotherapy consisted of 40 mg./m.^2 methotrexate and 4 mg./m.^2 vinblastine on days 1 and 8, and 100 mg./m.^2 cisplatin on day 2 given in 6 courses at 21-day intervals. Results: Median followup was 44 months. An average of 4.63 cycles of chemotherapy was administered. The median actual survival was 44 months, and the 1 and 3-year survival probabilities were 92 percent and 50 percent, respectively. The median disease-free survival was 15.5 months, and the 1 and 3-year disease-free survival probabilities were 66 percent and 28 percent, respectively. Only 5 (9 percent) and 1 (2 percent) patients had grades 3 and 4 leukopenia, respectively, and none died of sepsis. Conclusions: The use of adjuvant cisplatin, methotrexate and vinblastine chemotherapy in patients with invasive transitional cell carcinoma at high risk for recurrence is feasible with tolerable toxicity but randomized controlled trials will be required to assess the benefit.

Published
1996
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39. Recurrence rate and risk factors for urinary calculi after extracorporeal shock wave lithotripsy

Author

Sun, B.Y.C., Lee, Y.H., Jiaan, B.P., Chen, K.K., Chang, L.S., and Chen, K.T.

Abstract

Purpose: We determined the recurrence rate after extracorporeal shock wave lithotripsy (ESWL) and evaluated its associated risk factors, such as patient sex and age, volume of daily water intake, related diseases, family history of urinary calculi, number, burden and location of stones, residual stones after ESWL, serum uric acid level before ESWL and so forth. Materials and Methods: We conducted a retrospective study of 841 patients who underwent ESWL for primary treatment of urinary calculi between 1985 and 1987. Charts were reviewed for stone characteristics, outcomes and associated laboratory data. Followup 6 to 9 years later was done by mail and telephone interviews. Results: Followup data were available for 436 patients (52 percent). Overall, stones recurred in 51 percent of the 436 patients at a mean followup of 7.1 years. Late recurrences were common, and were noted in as many as 70 percent of the patients after 9 years. This rate is greater than what has been previously reported after other treatments. Cox regression analysis indicated that the major risk factors associated with recurrence were male gender (relative risk 1.406, p less than 0.05) and multiple stones (relative risk 1.777, p less than 0.05). Conclusions: The frequent late recurrences support the speculation that ESWL might lead to greater recurrence rates. Therefore, the cost-effectiveness of ESWL versus other modalities for stone removal warrants more long-term evaluation.

Published
1996
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