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11.
The multi-homogeneous Bezout number is a bound for the number of solutions of a system of multi-homogeneous polynomial equations,
in a suitable product of projective spaces. Given an arbitrary, not necessarily multi-homogeneous, system, one can ask for
the optimal multi-homogenization that would minimize the Bezout number. In this paper it is proved that the problem of computing,
or even estimating, the optimal multi-homogeneous Bezout number is actually NP-hard. In terms of approximation theory for
combinatorial optimization, the problem of computing the best multi-homogeneous structure does not belong to APX, unless P
= NP. Moreover, polynomial-time algorithms for estimating the minimal multi-homogeneous Bezout number up to a fixed factor
cannot exist even in a randomized setting, unless BPP ⫆ NP. 相似文献
12.
The price of SO2 permits and the volume of trading under the US Acid Rain Program have been lower than expected. This can be explained by the creation and distribution of more permits than were initially authorized, by the sale of permits by high cost abaters who are subject to more stringent local emission constraints or who have irreversibly invested in high cost abatement technologies and by the deregulation of the natural gas and railroad industries which, in combination with incentives for cost-cutting under the new market approach to SO2 control, has lowered marginal costs of abatement curves and made them more uniform across powerplants. The low price of permits and low trading volume are evidence that market approaches to pollution control can be more cost-effective than command and control regulations. The effect of public policies and technological changes on the allowance market are usefully examined in the context of an ideal market, in which the equilibrium price of allowances equals the marginal cost of abatement of individual powerplants. Using recent data from Coggins and Swinton (1996), we are able to explain the current price of permits with some accuracy. 相似文献
13.
Characterization of the epidermal growth factor receptor in pig oviduct and endometrium 总被引:1,自引:0,他引:1
K Wollenhaupt U Tiemann R Einspanier F Schneider W Kanitz KP Brüssow 《Canadian Metallurgical Quarterly》1997,111(2):173-181
Two different plaque variants of Japanese encephalitis virus were selected from a wild-type Taiwanese isolate using Vero cells. One variant was found to exhibit small plaque morphology with retarded virus replication kinetics in Vero cells, and was demonstrated to be resistant to monoclonal antibody (mAb) E3.3 neutralization. The other variant showed large plaque morphology, was sensitive to mAb E3.3 neutralization, and manifested reduced virulence in mice on both intracranial and intraperitoneal inoculations. These two variants propagated in Vero cells retained high levels of infectivity but had relatively low HA titers as compared with the parent strain. The envelope sequences of these two variants showed four amino acid differences at residues E-85 (Glu/Arg), E-306 (Glu/Gly), E-331 (Ser/Arg), and E-387 (Met/Arg). Our results indicated the neutralizing epitope of Japanese encephalitis virus did not overlap with virus virulence determinant. 相似文献
14.
Klaus Bauckhage 《化学,工程师,技术》1993,65(10):1200-1205
Utilisation of Different Components of Scattered Light for Particle Size Determination in Dispersed Systems . Light scattered by finely and coarsely dispersed particles can be used in variety of ways for characterization of sprays, emulsions, or suspensions. The characteristic of greatest interest is the particle size or the particle size distribution. While homogeneous, coarsely dispersed particles at sufficient dilutions and randomly distributed in a transparent continuous phase are generally amenable to particle size analysis, finely dispersed particles at higher concentrations or coarsely dispersed particles containing finely dispersed components are often difficult to measure. This article discusses ways of overcoming such difficulties on the basis of examples taken mainly from phase Doppler anemometry. 相似文献
15.
16.
A method for the determination of carbon black fillers in peroxide vulcanizates or sulfur vulcanizates of natural rubber (NR, cis-1,4-polyisoprene) by metathesis degradation with 1-octene was developed using the catalyst WCl6? (C2H5)3Al2Cl3. The carbon black was separated from the reaction mixture by centrifuging and determined by weighing. In this connection, investigations were also performed with the catalyst WCl6? C2H5Al2Cl3 which was less suitable for filler determination. The rate of degradation of crosslinked NR with (E)-4-octene was measured. Metathesis reactions of 2-methyl-2-pentene (low-molecular-weight model compound of NR) with 7-tetradecene showed the importance of double bond shift for the degradation of NR. 相似文献
17.
Walter Binder Ion Constantinescu Boi Faltings Klaus Haller Can Türker 《Autonomous Agents and Multi-Agent Systems》2006,12(2):219-237
This article presents an architecture to automatically create ad-hoc processes for complex value-added services and to execute
them in a reliable way. The uniqueness of ad-hoc processes is to support users not only in standardized situations like traditional
workflows do, but also in unique non-recurring situations. Based on user requirements, a service composition engine generates
such ad-hoc processes, which integrate individual services in order to provide the desired functionality. Our infrastructure
executes ad-hoc processes by transactional agents in a peer-to-peer style. The process execution is thereby performed under
transactional guarantees. Moreover, the service composition engine is used to re-plan in the case of execution failures.
The work presented in this article was supported by the Swiss National Science Foundation as part of the project MAGIC (FNRS-68155),
as well as by the Swiss National Funding Agency OFES as part of the European projects KnowledgeWeb (FP6-507482) and DIP (FP6-507483).
Authors in alphabetic order 相似文献
18.
Aus Betriebsergebnissen bei der Pfannenentschwefelung ist ein negativer Einfluß oxidierender Gasphasen bekannt. Daher war es das Ziel der eigenen Untersuchungen in einer geeigneten Apparatur die Wirkung oxidierender Bedingungen in der Gasphase sowohl auf den Verlauf des Schwefelabbaues in der Schlacke als auch des Schwefeltransportes aus dem Roheisen in die Schlacke zu untersuchen. Oxidierende Gasphasen erwirken bei der Pfannenentschwefelung an der Phasengrenze Schlacke/Gas eine Oxidation des Schwefels aus der Schlacke, ohne jedoch bei ruhender Schlackenschicht ein Oxidationspotential in der Schlacke aufzubauen, das bis zur Phasengrenze Roheisen/Schlacke durchgreift und dort die Entschwefelung des Roheisens durch die Siliciumgehalte stört. Sowohl die Entschwefelung des Roheisens als auch die Oxidation des Schwefels aus der Schlacke werden durch höhere Temperaturen und durch eine Rührwirkung gefördert. Der Schwefeltransport wird bei den ungerührten wie bei den gerührten Schmelzen durch Diffusionsvorgänge gesteuert und auch hier durch steigende Temperaturen und rührende Kräfte begünstigt. 相似文献
19.
Heinrich Heydt Philipp Eisenbarth Karin Feith Klaus Urgast Gerhard Maas Manfred Regitz 《Israel journal of chemistry》1986,27(1):96-104
Amino-substituted cyclopropenylium salts ( 11a,b ) react with diazomethyl compounds ( 12a-i ) in dichloromethane or acetonitrile in the presence of a base (ethyldiisopropylamine, 1,5-diazabicyclo[4.3.0] non-5-ene) to form 4-aminopyridazines ( 13a-i ) specifically. The reaction is interpreted in terms of an initial electrophilic diazoalkane substitution to give diazomethylcyclopropenes ( 11 + 12 → 14 ) which undergo a [1.5]-cyclisation to form the betaines 16 which, in turn, isomerise with opening of the bridging bond to give the aminopyridazines 13 . In a similar manner, the tris[amino] cyclopropenylium salts 8a,b and 10a-c are converted to the 3,4,5-tris[amino]-pyridazines ( 21a-k ) by treatment with diazomethyl compounds ( 12a, c-f ). 相似文献
20.