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991.
B Tan 《The Journal of the Operational Research Society》2002,53(2):232-242
In this study, we investigate the strategy of increasing production capacity temporarily through contingent contractual agreements with short-cycle manufacturers to manage the risks associated with demand volatility. We view all these agreements as capacity options. More specifically, we consider a manufacturing company that produces a replenishment product that is sold at a retailer. The demand for the product switches randomly between a high level and a low level. The production system has enough capacity to meet the demand in the long run. However, when the demand is high, it does not have enough capacity to meet the instantaneous demand and thus has to produce to stock in advance. Alternatively, a contractual agreement with a short-cycle manufacturer can be made. This option gives the right to receive additional production capacity when needed. There is a fixed cost to purchase this option for a period of time and, if the option is exercised, there is an additional per unit exercise price which corresponds to the cost of the goods produced at the short-cycle manufacturer. We formulate the problem as a stochastic optimal control problem and analyse it analytically. By comparing the costs between two cases where the contract with the short-cycle manufacturer is used or not, the value of this option is evaluated. Furthermore, the effect of demand variability on this contract is investigated. 相似文献
992.
Daciberg L. Gonç alves Jan Jaworowski Pedro L. Q. Pergher 《Proceedings of the American Mathematical Society》2002,130(10):3111-3115
Let be a finite group acting freely in a CW-complex which is a homotopy -dimensional sphere and let be a map of to a finite -dimensional CW-complex . We show that if , then has an -coincidence for some nontrivial subgroup of .
993.
994.
A short and versatile synthesis of substituted quinolines is provided. Alkylation of sodium tolylsulfinate with bromomethyl- or chloromethyl ketones generates beta-keto sulfones. Knoevenagel condensation of the beta-keto sulfones with an aldehyde provides alpha-tolylsulfonyl-alpha,beta-unsaturated ketones. Michael addition of the dianion of N-Boc-anilines in the presence of CuCN and LiCl with the unsaturated ketone generates a 1,4-adduct, which after deprotection of the Boc group and thermal elimination of the tolyl sulfone provides the quinoline. 相似文献
995.
After heat erases the order in 1,3-O,O'-bis(dodecyl)calix[4]arene, it self-organizes the phenyl units into a rigid calix bowl first at T2 = 111 degrees C, followed by the formation of all-trans alkyl chains at T1 = 62 degrees C, which eventually yields a stable cone-shaped structure at room temperature. 相似文献
996.
Kanungo M Srivastava DN Kumar A Contractor AQ 《Chemical communications (Cambridge, England)》2002,(7):680-681
A conductimetric reagentless immunosensor using the biospecific binding pair of goat antirabbit IgG and rabbit IgG has been designed and fabricated using poly (3,4-ethylenedioxythiophene) as the immobilization matrix-cumtransducer. 相似文献
997.
[reaction: see text] The first example of enantioselective linear homoallylic alcohol transfer reaction was revealed. In all cases, the whole rearrangement is thermodynamically favorable and a steric effect is the driving force of this reaction. The preservation of the stereocenter and olefin geometry together with the isolation of gamma-adduct homoallylic alcohols in one isomeric form have warranted the proposed mechanism. 相似文献
998.
Li N Tan WG Tsang RY Tyrrell DL Dovichi NJ 《Analytical and bioanalytical chemistry》2002,374(2):269-273
We report an accurate and reproducible DNA quantitation method using the polymerase chain reaction (PCR). The amount of PCR product is monitored after each PCR cycle by capillary electrophoresis. To ensure accurate quantitation, a non-amplified internal standard is added to each PCR-amplified electrophoresis sample to correct for variations in injection volume. Quantitation of the sample is based on the number of cycles necessary to generate a predetermined amount of PCR product. Duck hepatitis B virus genome was used as a model in this study. The genome was quantified with a linear relationship between cycle number and logarithm of sample DNA for amounts of sample DNA between 30 and 3.1 x 10(8) copies ( r(2)>0.999). The relative standard deviation for the corrected capillary electrophoresis signal was 2.7%, while the relative standard deviation for the overall assay was 3.0%. Results from a single-blind study generated a relative error of 1.3%. 相似文献
999.
Gabrielse G Bowden NS Oxley P Speck A Storry CH Tan JN Wessels M Grzonka D Oelert W Schepers G Sefzick T Walz J Pittner H Hänsch TW Hessels EA;ATRAP Collaboration 《Physical review letters》2002,89(23):233401
Cold antihydrogen is produced when antiprotons are repeatedly driven into collisions with cold positrons within a nested Penning trap. Efficient antihydrogen production takes place during many cycles of positron cooling of antiprotons. A first measurement of a distribution of antihydrogen states is made using a preionizing electric field between separated production and detection regions. Surviving antihydrogen is stripped in an ionization well that captures and stores the freed antiproton for background-free detection. 相似文献
1000.
A subexcitable medium of Belousov-Zhabotinsky (BZ) reaction subjected to external Gaussian white noise is studied in experiments and numerical simulations. We observe that at an optimal level of noise the wave sources of excited traveling waves become synchronous, as though there exists a long distance spatial correlation. The synchronous behavior fades if the noise level becomes larger or smaller. Numerical simulations confirm the experimental findings, and point out that the best synchronous behavior takes place when the signal-to-noise ratio of waves becomes largest. 相似文献