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排序方式: 共有196条查询结果,搜索用时 31 毫秒
1.
Kimmo Fredriksson 《Information Processing Letters》2003,87(4):201-204
Given a text T[1…n] and a pattern P[1…m] over some alphabet Σ of size σ, we want to find all the (exact) occurrences of P in T. The well-known shift-or algorithm solves this problem in time O(n⌈m/w⌉), where w is the number of bits in machine word, using bit-parallelism. We show how to extend the bit-parallelism in another direction, using super-alphabets. This gives a speed-up by a factor s, where s is the number of characters processed simultaneously. The algorithm is implemented, and we show that it works well in practice too. The result is the fastest known algorithm for exact string matching for short patterns and small alphabets. 相似文献
2.
In this paper we propose a soft-output RAKE receiver for CDMA mobile terminals using low spreading factor and/or high-order modulation constellations for high data rates. Based on the outputs of theRAKE correlator fingers, the receiver produces symbol or bit metrics for soft decision decoding. The formulation of these metrics is derived analytically taking into account the multipath propagation, interfering users and channel estimation errors. Simulations show thata performance gain is achieved when low spreading factors or high-order modulation constellations are used. 相似文献
3.
Kshama Motha Ulla Hippi Kimmo Hakala Maija Peltonen Vuokko Ojanper Barbro Lfgren Jukka Seppl 《应用聚合物科学杂志》2004,94(3):1094-1100
This article reports a study of some functionalized polyolefins evaluated as compatibilizers in polyethylene nanocomposites. The functionalized polymers were prepared by direct metallocene‐mediated copolymerizations of ethylene and a functional comonomer. The prepared nanocomposites were evaluated for mechanical and barrier property enhancement. A good combination of mechanical and barrier properties was obtained with the metallocene‐based functionalized polyethylene. The toughness–stiffness balance was better than or comparable to that achieved with conventional functionalized polymers such as maleic anhydride grafted polyethylene. The results also indicated that these metallocene‐based functionalized polyolefins, when used as compatibilizers, could have relatively higher molar masses and lower functionality than those of conventional post‐reactor‐modified compatibilizers, and so the drawbacks associated with the latter could be avoided. Their inherent properties could also further improve the final nanocomposite properties. This was attributed to the more homogeneous nature of metallocene‐catalyzed polymers in comparison with post‐reactor‐modified products. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1094–1100, 2004 相似文献
4.
The thermal curing reaction of two phenolic resole resins is monitored using the fluorescence technique. The intrinsic fluorescence can be used as an indicator for cure monitoring for the first resole. As the thermal curing proceeds, the intrinsic fluorescence intensity of the resole resin decreases and exhibits a few nanometers of redshift. The fluorescence intensity of the emission maxima is correlated with the conversion measured by differential scanning spectroscopy. A linear correlation is found at three different temperatures. The intrinsic fluorescence cannot always be used for monitoring the curing process of phenolic resole resins. Thus, three intramolecular charge transfer compounds and two organic donor–π‐acceptor salts are selected and applied for the cure monitoring of the second phenolic resole resin. As the curing reaction proceeds, the fluorescence emission spectra of the probes exhibit a blue spectral shift and the intensity changes because of environmental changes. An intensity ratio method is applied in which the ratios of the low‐ to high‐intensity changes in the emission bands are used to determine the degree of the curing process. There is a smooth correlation between the intensity ratio method and the degree of cure. The method enables one to follow the changes in the polymer structure at low and intermediate degrees of the curing process (below 70%) and obtain comparable results from different types of probes during the same curing process. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1773–1780, 2002 相似文献
5.
Ayse Tosun Oscar Dieste Davide Fucci Sira Vegas Burak Turhan Hakan Erdogmus Adrian Santos Markku Oivo Kimmo Toro Janne Jarvinen Natalia Juristo 《Empirical Software Engineering》2017,22(6):2763-2805
Existing empirical studies on test-driven development (TDD) report different conclusions about its effects on quality and productivity. Very few of those studies are experiments conducted with software professionals in industry. We aim to analyse the effects of TDD on the external quality of the work done and the productivity of developers in an industrial setting. We conducted an experiment with 24 professionals from three different sites of a software organization. We chose a repeated-measures design, and asked subjects to implement TDD and incremental test last development (ITLD) in two simple tasks and a realistic application close to real-life complexity. To analyse our findings, we applied a repeated-measures general linear model procedure and a linear mixed effects procedure. We did not observe a statistical difference between the quality of the work done by subjects in both treatments. We observed that the subjects are more productive when they implement TDD on a simple task compared to ITLD, but the productivity drops significantly when applying TDD to a complex brownfield task. So, the task complexity significantly obscured the effect of TDD. Further evidence is necessary to conclude whether TDD is better or worse than ITLD in terms of external quality and productivity in an industrial setting. We found that experimental factors such as selection of tasks could dominate the findings in TDD studies. 相似文献
6.
7.
It is proved that the system of word equations x
i
1=y
i
1
y
i
2…y
i
n
, i=1, 2,…, ⌈n/2⌉ +1, has only cyclic solutions. Some sharpenings concerning the cases n=5, 7 and n≥9 are derived as well as results concerning the general system of equations x
i
1
x
i
2…x
i
m
=y
i
1
y
i
2…y
i
n
, i=1, 2,… . Applications to test sets of certain bounded languages are considered.
Received: 18 May 1995/2 January 1996 相似文献
8.
9.
Tero Luukkonen Emma-Tuulia Tolonen Hanna Runtti Kimmo Kemppainen Paavo Perämäki Jaakko Rämö Ulla Lassi 《Journal of Materials Science》2017,52(16):9363-9376
Geopolymers are functional materials that can be used in various environmental applications such as adsorbents in pollutant removal from wastewaters. Metakaolin geopolymer (MK-GP) has been proven to be especially suitable for ammonium (NH4 +) removal. In this research, the optimal reagent and raw material ratios in the preparation of MK-GP in terms of NH4 + adsorption capacity were investigated. The response surface methodology based on the face-centered central composite design was used to optimize the levels of three factors: the amounts of hydroxide, silicate, and metakaolin. In addition, the effect of Na or K as the charge-balancing cation was studied. Empirical models were fitted to the experimental data using multiple linear regression. The significance of the models was confirmed by means of analysis of variance. Optimal NH4 + removal efficiency was achieved when the amounts of hydroxide and silicate were maximized, the amount of metakaolin was minimized, and Na-based reagents were used. These trends are most likely a result of optimized conversion of metakaolin into MK-GP. 相似文献
10.
Jestoi M Somma MC Kouva M Veijalainen P Rizzo A Ritieni A Peltonen K 《Molecular nutrition & food research》2004,48(4):299-307
The contamination levels of 16 different Fusarium- and Aspergillus-mycotoxins were chemically determined from randomly selected organic and conventional grain-based products purchased from Finnish and Italian markets. The cytotoxicity of the samples was analyzed with an in vitro test using feline fetal lung cells. Overall, the concentrations of the mycotoxins studied were low in all of the samples. Enniatins B and B1 as well as deoxynivalenol were the most predominant mycotoxins in the samples, being present in 97%, 97%, and 90% of the samples, respectively. The geographical origin or the agricultural practice had no influence on the mycotoxin concentrations of the samples. The babyfoods included in the samples had significantly lower concentrations of mycotoxins than the other products with a mean total mycotoxin content of 47 microg/kg compared with 99 microg/kg for the other kinds of food. All the samples evoked toxicity in the in vitro test, but no correlation between cytotoxicity and the mycotoxin concentrations was observed. 相似文献