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排序方式: 共有96条查询结果,搜索用时 15 毫秒
1.
Godwin J. Udo 《The Journal of the Operational Research Society》1994,45(12):1425-1435
This paper is a report of a simulation study that investigates a dynamic approach to scheduling jobs in a multi-machine job shop. The workload information of a job is used in different forms to evaluate the shop performance based on three measures: mean job lateness, percentage of tardy jobs and lateness variance. Different combinations of due-date assignment methods and sequencing rules are compared based on specific performance criteria. The results indicate that using the cumulative distribution function of workload information can yield a better performance than using a proportional function of workload information or ignoring shop congestion information. A few situations are identified in which workload information is not critical. 相似文献
2.
Godwin O. Mbagwu R. Gerald Bass Richard A. Glennon 《Journal of heterocyclic chemistry》1985,22(2):465-474
The ring-opening reactions of seven mesoionic thiazolo[3,2-a]pyrimidine-5,7-diones by a series of primary and secondary amines have been investigated. The rates of the ring fission of five N(8)-substituted mesoionic xanthines with benzylamine were measured and found to follow second order kinetics. The Hammett relationship is followed with ? value of + 0.48 in p-dioxane as solvent. The dependence of rates on temperatures has been studied for the N(8)-ethyl derivative; the energy of activation (Δ E* ) is 25.3 kcals mol?1, the enthalpy of activation (Δ H* ) is 24.7 kcals mol?1 and the entropy of activation (Δ S* ) is — 4.9 e.u. A slight increase in rate of reaction was observed when the solvent was changed from p-dioxane to dimethyl sulfoxide. In p-dioxane at constant mesoionic xanthine concentration, the rate constant for ring opening decreased with increasing benzylamine concentration. These results are consistent with a bimolecular nucleophilic mechanism proceeding by the rate-determining formation of a charged tetrahedral transition state. 相似文献
3.
Ayoko Godwin Adefikayo Iyun Johnson Femi El-Idris Ibrahim Faskari 《Transition Metal Chemistry》1992,17(1):46-49
Transition Metal Chemistry - The kinetics of the silver(I) ion catalysed reduction of peroxodisulphate by 12-tungstocobaltate(II) anion in aqueous HC1O4 has been studied. Although the reaction in... 相似文献
4.
Dr. B. P. Feuerbacher Dr. R. P. Godwin Dr. M. Skibowski 《Zeitschrift für Physik A Hadrons and Nuclei》1969,224(1-3):172-178
A plasma resonance in the photoelectric yield has been observed on thin aluminum films evaporated in ultrahigh vacuum when irradiated with parallel-polarized light at the bulk plasma energy of Al, 14.8 eV (λp=835 Å). A relative yield has been measured for wavelengths between 500 and 1100 Å with polarized synchrotron light at various angles of incidence for both directions of polarization. The results agree reasonably well with theoretical predictions based on a simple model for excitation and escape of photoelectrons into the vacuum. 相似文献
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Godwin Chukwu Ebi A. Singh 《Journal of polymer science. Part A, Polymer chemistry》1990,28(13):3533-3540
3,5-Di-tert-butyl-4-hydroxybenzyl thioglycollate (DBHBT) has been reacted with Nigerian Natural rubber latex at 65 ± 1°C using 4,4-azobiscyanovaleric (AZBN) acid-ferrous sulfate redox system to obtain a binding efficiency of 13%. The bound DBHBT was investigated as a UV stabilizer in unprocessed and unvulcanized rubber using spectroscopic method. With respect to the C? O index, the masterbatch diluted to 56% gave the optimum activity and higher concentrations showed significant pro-oxidant activity. The C? C bonds in particular, showed greater stability which is a function of DBHBT concentration. The methylenic and the allylic hydrogen atoms, the most susceptible, and probably the sites of the primary attack, were not protected by DBHBT. 相似文献
8.
Leah A. Godwin Kennon S. DealLauren D. Hoepfner Louis A. JacksonChristopher J. Easley 《Analytica chimica acta》2013
A simplified method for measuring the fluidic resistance (Rfluidic) of microfluidic channels is presented, in which the electrical resistance (Relec) of a channel filled with a conductivity standard solution can be measured and directly correlated to Rfluidic using a simple equation. Although a slight correction factor could be applied in this system to improve accuracy, results showed that a standard voltage meter could be used without calibration to determine Rfluidic to within 12% error. Results accurate to within 2% were obtained when a geometric correction factor was applied using these particular channels. When compared to standard flow rate measurements, such as meniscus tracking in outlet tubing, this approach provided a more straightforward alternative and resulted in lower measurement error. The method was validated using 9 different fluidic resistance values (from ∼40 to 600 kPa s mm−3) and over 30 separately fabricated microfluidic devices. Furthermore, since the method is analogous to resistance measurements with a voltage meter in electrical circuits, dynamic Rfluidic measurements were possible in more complex microfluidic designs. Microchannel Relec was shown to dynamically mimic pressure waveforms applied to a membrane in a variable microfluidic resistor. The variable resistor was then used to dynamically control aqueous-in-oil droplet sizes and spacing, providing a unique and convenient control system for droplet-generating devices. This conductivity-based method for fluidic resistance measurement is thus a useful tool for static or real-time characterization of microfluidic systems. 相似文献
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Application of organoclays for the adsorption of recalcitrant organic molecules from aqueous media 总被引:2,自引:0,他引:2
Water purification is imperative for the welfare of a healthy population. Water is widely contaminated by recalcitrant organic chemicals such a pesticides, herbicides and hormones. One inexpensive method for purifying water from these types of molecules is through adsorption. One suite of materials for this adsorption is based upon organoclays. This paper reviews the adsorption of organics on organoclays. 相似文献