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71.
During the last 5 years, we have witnessed extraordinary development in the mobile market. Apple’s launch of the iOS platform and associated App Store marketplace turned the market around, and Apple became the leading company in the business. This development caused existing players, such as Nokia, to renew their business and attracted new players, such as Google and Microsoft, to enter the market and introduce their own mobile platforms. To understand this development, we suggest that a generic abstracted model of the ecosystem around mobile platforms should be developed describing how the actors, including users, individual app developers, companies, and digital services, are connected and interact. In this work, we propose that competition and collaboration in this kind of abstracted ecosystem can be modeled and analyzed using network analysis. In our research, we derived weighted competition and collaboration networks for each mobile platform from an expert survey, and by calculating companies’ degree centrality in their networks at different times we were able to illustrate how companies’ strategies to build and maintain an ecosystem differ and develop over time. We believe that this kind of analysis is useful both for companies that build ecosystems and also for companies that plan to do business in them. The former can use it to compare their strategy with existing competitors and also evaluate emerging new ecosystems and the latter to compare and choose between possible ecosystems with which to do business. 相似文献
72.
Louise Johnson Dorine L. Verraest Jacco van Haveren Kimmo Hakala Joop A. Peters Herman van Bekkum 《Tetrahedron: Asymmetry》1994,5(12)
Methyl α-
-fructofuranoside was synthesized by methylation of
-fructose and subsequent isolation of the α-furanoside from the anomeric mixture. This fructofuranoside was used as a starting material for the syntheses of several carboxylates, applying glycolic oxidation, selective oxidation of the primary alcohol function at the C-6 position and carboxymethylation. 相似文献
73.
We examine, by way of a detailed numerical calculation, the consequences for primordial nucleosynthesis of a weakly interacting neutrino which possesses both Dirac and Majorana mass terms. In the special limiting case of a pseudo-Dirac neutrino we place bounds on the pseudo-Dirac mass splitting δmp-D. This bound is relevant to a class of models constructed to incorporate the proposed 17 keV neutrino. We find that in the standard model |δmp-D|<10−10 eV. In the models with majorons the bound is less restrictive, but still several orders of magnitude more stringent than previous estimates. 相似文献
74.
Vasyl Palchykov János Kertész Robin Dunbar Kimmo Kaski 《Journal of statistical physics》2013,151(3-4):735-744
Mobile phone communication as digital service generates ever-increasing datasets of human communication actions, which in turn allow us to investigate the structure and evolution of social interactions and their networks. These datasets can be used to study the structuring of such egocentric networks with respect to the strength of the relationships by assuming direct dependence of the communication intensity on the strength of the social tie. Recently we have discovered that there are significant differences between the first and further “best friends” from the point of view of age and gender preferences. Here we introduce a control parameter p max based on the statistics of communication with the first and second “best friend” and use it to filter the data. We find that when p max is decreased the identification of the “best friend” becomes less ambiguous and the earlier observed effects get stronger, thus corroborating them. 相似文献
75.
76.
77.
Kokkonen R Sirén H Kauliomäki S Rovio S Luomanperä K 《Journal of chromatography. A》2004,1032(1-2):243-252
In this study, capillary electrophoresis (CE) was used for separation of inorganic and organic ions from waters of paper and paperboard machines at mills. The instrument was constructed for on-line measurements by building a batch-type sample feeding unit. Chloride, thiosulphate, sulphate, oxalate, sulphite, hydrogen sulphide, formate, carbonate, phosphate and acetate in the process water samples were separated using an ion-specific separation system in CE with dicarboxylic acid buffer (pH 8.2), with pyridinium-2,3-dicarboxylic acid modified with commercial NICE-Pak OFM-OH solution (pH 12.0) or with a cetyltrimethylammonium bromide solution modified with chromate (pH 10.6). In addition, Analis CEofix Anions 8 electrolyte solution was tested in on-line studies at mills. It allowed 5 min separation time for the anions. Aluminium was determined at pH 3.6 in 10 min by using a laboratory-made imidazole buffer modified with 18-crown 6-ether. The developed CE systems were used to monitor the concentrations of sulphur species in dithionite degradation, to estimate corrosion degree in the water tanks, to monitor formaldehyde as the biocide chemical in wire washing and, in general, to observe process disturbances resulting from chemical feedings and their sites. The CE combination was on-line coupled to eight different process machines for continuous monitoring of concentrations for periods between two weeks and one month at paper and pulp mills in Finland. 相似文献
78.
A CMOS Quadrature Baseband Frequency Synthesizer/Modulator 总被引:1,自引:0,他引:1
Marko Kosunen Jouko Vankka Mikko Waltari Lauri Sumanen Kimmo Koli Kari Halonen 《Analog Integrated Circuits and Signal Processing》1999,18(1):55-67
A quadrature baseband frequency synthesizer/modulator IC has been designed and fabricated in a 0.5 m CMOS. This quadrature baseband frequency synthesizer/modulator is intended for use in a wide variety of indoor/outdoor portable wireless applications in the 2.4–2.4835 GHz ISM frequency band. This frequency synthesizer/modulator is a capable of frequency and phase modulation. The major components are: a quadrature direct digital synthesizer, digital-to-analog converters and lowpass filters. By programming the quadrature direct digital synthesizer, adaptive channel bandwidths, modulation formats, frequency hopping and data rates are easily achieved. The quadrature baseband direct digital synthesizer produces an 80 MHz frequency band. The quadrature baseband spectrum could be upconverted with off-chip mixers into the 2.4 GHz ISM frequency band. The chip has a complexity of 17,803 transistors with a die area of 24 mm2 and a core area of 9 mm2. The power dissipation is 496 mW at 3.3 V. 相似文献
79.
Jarkko Routama Kimmo Koli Pasi Ruhanen Kari Halonen 《Analog Integrated Circuits and Signal Processing》1999,19(1):59-74
In this paper a single chip transmitter and receiver interface circuit for 160 Mbit/s CMI-coded data transmission is presented. The receiver circuit includes a 12 dB cable equalizer to compensate for nonconstant cable attenuations. There is also a PFLL for data regeneration and to extract a 320 MHz oscillator clock signal. The frequency characteristics of the equalizer are controlled with an automatic gain control loop (AGC). The PFLL is a combination of two separate control loops, the purpose of which is to keep the integrated oscillator on the narrow locking range of the data loop. The frequency loop has been designed with a frequency detector to avoid interferences between the two control loops. The transmitter includes a cable driver supplying a stable 1 Vpp signal amplitude to the transmission line and also a PLL to extract a 320 MHz clock signal. 相似文献
80.
Jarno Kansikas Kaija Sipil 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(11):1383-1385
In the synthesis of 1‐phenyl‐2‐phenylthio‐2‐(tetrahydropyran‐2‐ylthio)ethanol, C19H22O2S2, four diastereoisomers are formed. Two non‐centrosymmetric enantiomeric forms which crystallize in space groups P212121 and Pna21 are presented. The former has an intramolecular hydrogen bond between the hydroxyl group and the O atom of the tetrahydropyran ring. In the latter isomer, the hydroxyl group forms an intermolecular hydrogen bond to the O atom of the tetrahydropyranyl group of a neighbouring molecule, joining the molecules into chains in the c‐axis direction; the O?O distances are 2.962 (4) and 2.764 (3) Å, respectively. The tetrahydropyran rings are in chair conformations in both isomers and the S side chain has an equatorial orientation in the former, but an axial orientation in the latter molecule. 相似文献