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91.
L. G. Chalmet R. L. Francis J. F. Lawrence 《Journal of Optimization Theory and Applications》1980,32(2):135-149
An example of design might be a warehouse floor (represented by a setS) of areaA, with unspecified shape. Givenm warehouse users, we suppose that useri has a known disutility functionf
isuch thatH
i(S), the integral off
iover the setS (for example, total travel distance), defines the disutility of the designS to useri. For the vectorH(S) with entriesH
i(S), we study the vector minimization problem over the set {H(S) :S a design} and call a design efficient if and only if it solves this problem. Assuming a mild regularity condition, we give necessary and sufficient conditions for a design to be efficient, as well as verifiable conditions for the regularity condition to hold. For the case wheref
iis thel
p-distance from warehouse docki, with 1<p<, a design is efficient if and only if it is essentially the same as a contour set of some Steiner-Weber functionf
=1
f
1++
m
f
m
,when the
i
are nonnegative constants, not all zero.This research was supported in part by the Interuniversity College for PhD Studies in Management Sciences (CIM), Brussels, Belgium; by the Army Research Office, Triangle Park, North Carolina; by a National Academy of Sciences-National Research Council Postdoctorate Associateship; and by the Operations Research Division, National Bureau of Standards, Washington, D.C. The authors would like to thank R. E. Wendell for calling Ref. 16 to their attention. 相似文献
92.
93.
An investigation of heparinase immobilization 总被引:1,自引:0,他引:1
Bernstein Howard Yang Victor C. Langer Robert 《Applied biochemistry and biotechnology》1987,16(1):129-143
A systematic investigation of the parameters that affect the efficiency of immobilizing heparinase onto cyanogen bromide activated
crosslinked 8% agarose beads was conducted. Two experimental measures, the “fraction bound” and the “fraction retained,” were
used to monitor the coupling efficiency. The fraction bound is the portion of the total initial enzyme that is bound to the
agarose gel. The fraction retained is the fraction of bound enzyme that is active. The product of the two measures indicates
the coupling efficiency. The activity of the immobilized heparinase was measured under conditions free of both internal and
external mass transfer limitations, and thus, the fraction retained represents the true immobilized enzyme activity.
Increasing the degree of activation of the beads results in an increase in the fraction bound, the fraction retained, and
consequently, the coupling efficiency. As the ratio of enzyme solution to gel volume increases from 1.5 to 2.2, the fraction
bound remains constant but the fraction retained decreases (heparinase concentration; 0.15 mg/mL and degree of activation;
9.5 μmol of cyanate esters/g of gel). At volume ratios greater than 2.2, both the fraction bound and the fraction retained
decline continuously. Changing the heparinase concentration in the coupling solution changes the coupling efficiency in a
manner similar to that of the volume ratio change.
When heparin is added during the coupling process, the fraction bound declines as the heparin concentration increases, whereas
the fraction retained increases up to a heparin concentration of 12 mg/mL and decreases thereafter. When arginine, lysine,
and glycine are used to block the unreacted cyanate ester groups after the coupling process, the immobilized heparinase shows
different pH optima of 6.5, 6.9, and 7.2, respectively. Based upon these findings, a protocol to optimize heparinase immobilization
is developed. 相似文献
94.
95.
程序涂渍柱“柱效能程序效应”的研究 总被引:1,自引:0,他引:1
本文从理论上给出程序柱“柱效能程序效应”的概念并导出了函数关系式,通过计算机可计算柱效能程序效应与柱内各变量之间的关系,实践证明实验数据的变化趋势与理论数据相符。 相似文献
96.
Mohammad M. Fares Adeeb S. El-Faqeeh 《Journal of Thermal Analysis and Calorimetry》2005,82(1):161-166
Summary Thermal degradation under N2atmosphere and thermoxidative degradation under air atmosphere of increasingly grafting efficiency values (i.e. GE%=0.0 to 35.5) for starch and starch grafted with N-tert-butylacrylamide thermosensitive copolymers (starch-g-BAM) by Ozawa and Kissinger methods using thermogravimetric analysis
(TG) and differential scanning calorimetry techniques (DSC) at 10, 30 and 50% mass losses respectively have been studied.
Influence of physical inter and intra molecular interactions on grafting and consequently on activation energy of degradation
(Ea,d) was investigated using Ozawa's method, whereas linear dependence of Ea,don GE% by scaling relations using Kissinger's method was determined. Furthermore, the thermoxidative degradation induces the possibility
of molecular rearrangement, cyclization and partial crosslinking that is deduced from the activation energy of degradation
(Ea,d) and residual mass of TG profile. Thermal stability of starch does not alter as a result of different grafting efficiency
percentages. 相似文献
97.
近年来,钙钛矿太阳电池的光电转换效率取得了爆发式增长,这与电池中钙钛矿薄膜的制备工艺和材料组分密切相关.关于钙钛矿薄膜的制备方法,相关的研究报道及综述较多,然而钙钛矿材料组分调控方面的研究梳理工作相对缺乏.本综述总结了近年来不同组分体系钙钛矿材料的研究进展,包括有机无机铅卤钙钛矿、全无机铅卤钙钛矿、少铅钙钛矿以及无铅钙钛矿.重点介绍了不同体系中具有代表性的材料组分及其对器件性能的影响,旨在梳理通过组分调控提高钙钛矿电池的效率及稳定性的研究思路,最终实现商业化应用. 相似文献
98.
99.
We present a microstructural model of aerogels that includes the effect of particle necks, tortuosity and dangling ends on the scaling of elastic moduli with density. Relative neck radii can be determined for sintering series of silica aerogels and for Resorcinol Formaldehyde (RF) aerogels produced with different catalyst concentrations. The density of elastically ineffective dangling ends and the tortuosity can be estimated using information from thermal conductivity and elastic modulus measurements in silica aerogels. Typical values for the load bearing mass range from >50% for high density and heat treated aerogels to <10% of the total mass for low density wet-gels. 相似文献
100.
G. Schomburg 《Journal of separation science》1979,2(7):461-474
Glass capillary gas chromatography is a high resolution separation method which allows the qualitative and quantitative analysis of even complex mixtures, which may contain many components–also isomeric–in a wide range of volatilities, polarities and concentrations. The principal limitation of gas chromatographic application is given by an insufficient volatility of the species to be separated. Elevated temperatures have to be applied if the application range is to be extended and to achieve steep peak profiles, i.e. low detection limits at high resolution. The use of elevated temperatures is limited, of course, by the temperature stability of both the solvent (stationary liquid and support) and the solutes. The problems of trace analysis for low volatility compounds at high resolution and its limitational parameters regarding sampling, separation and detection are discussed. The applicability of glass capillary columns in this field is influenced by the following parameters: tailing behaviour; irreversible adsorption of polar and decomposition of unstable solutes; thermal stability of stationary liquid (including the support deactivation); separation efficiency and sample capacity (film thickness). Multidimensional gas chromatography using capillary columns coupled either with a packed or another capilllary column for preseparations may be applied with advantage in the analysis of complex mixtures. 相似文献