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1.
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
2.
Magalie De Ville Philippe Coquet Philippe Brunet Rabah Boukherroub 《Microfluidics and nanofluidics》2012,12(6):953-961
Convenient for both biologists and MEMS designers, Polydimethylsiloxane (PDMS) polymer is intensively investigated for its
biocompatibility, transparency, high resistance under plasma treatment, flexibility and resistance to high temperature. However,
for microfluidic applications, the fabrication of PDMS circular channels is difficult to achieve except by wire moulding.
In this article, we present a simple, fast and low-cost fabrication method which can be applied out of clean-room environment.
It is based on the deposition of alginic acid sodium salt aqueous solution, enabling the formation of a liquid cylinder on
the most hydrophilic part of a hydrophilic/hydrophobic patterned surface. We experimentally studied the interaction between
liquid rivulets and surfaces presenting a contrast of wettability and/or a stepwise texture. Subsequent moulding of the half-cylinder
of liquid produces round PDMS microfluidic channels. The optimal parameters for hydrophilic/hydrophobic patterns have then
been applied to produce the roundest possible channels. The realisation of both straight channels 300–500 μm wide, 1 cm long
and 75° tangent chord angle at best, and Y-shaped channels with the same dimensions and 55° TCA is demonstrated. 相似文献
3.
Riitta Kettunen Sanna Saarnio Pertti J. Martikainen Jouko Silvola 《Nutrient Cycling in Agroecosystems》2006,74(2):175-189
The effects of elevated atmospheric CO2 concentration on soil moisture, N2O fluxes, and biomass production of Phleum pratense were studied in the laboratory. Farmed peat and sandy soil mesocosms sown with P. pratense were fertilized with a commercial fertilizer. In peat soil 10 g N m−2 of commercial fertilizer were added and in sandy soil 15 g N m−2. In both experiments, soil moisture was regulated with deionized water; 18 mesocosms were tended to keep equally moist, and
the other 18 were watered with equal amounts of water. Nine mesocosms from both watering treatments were grown under ambient
(360 μmol mol−1) CO2 concentration and the remaining nine under doubled (720 μmol mol−1) CO2. N2O efflux was monitored using a closed chamber technique and a gas chromatograph. The elevated supply of CO2 increased production of above- and belowground biomass, soil moisture and N2O fluxes, but decreased the total N content in the aboveground biomass, especially for the sandy soil. In similar water levels,
N2O efflux from the sandy soil was the same magnitude as that from the peat soil. In addition to moisture, N availability was
the main limiting factor for N2O production, but C availability also seemed to regulate the denitrification activity. In addition to an increase in C availability
the increase in the N2O efflux under the raised CO2 concentration also required a simultaneous increase in soil moisture. 相似文献
4.
Ville Alopaeus Jukka Koskinen Kari I. Keskinen 《Chemical Engineering Communications》2003,190(11):1468-1484
A simulation model has been developed to model drop populations in a mixed tank. A multiblock mixed tank model has been used with the drop population balance equations developed in the literature. The drop breakage and coalescence functions used in the population balance model take into account the local turbulent energy dissipation values. The drop breakage and coalescence function parameters are fitted against drop size measurements from dense liquid-liquid dispersions, which were assumed fully turbulent. Since the local turbulence and flow values of a mixed tank are used in the present model, the fundamental breakage and coalescence phenomena can be taken into closer examination. Furthermore, the present model is capable of predicting inhomogeneities occurring in a mixed tank. It is also considered as an improved tool for process scale-up, compared to the simple vessel-averaged population balance approach, or use of correlations of dimensionless numbers only. The present model can use two sources of data for fitting parameters in the drop rate functions. One is the transient data of the measured drop size distribution as the impeller speed is changed. The other is the time-averaged data measured at different locations of the mixed tank. Different flow regions can be chosen from direct measurements or from the CFD simulations in a straightforward manner. CFD flow simulation results can be used when no experimentally obtained flow conditions are available. This is especially useful for nonstandard vessels, such as reactors containing cooling coils. 相似文献
5.
2D profile analysis has often in the past been considered sufficient to control the geometrical features of a surface and to ensure that they are compatible with the required functionalities. Yet, experience shows that 3D surface texture analysis is now essential wherever a complete assessment of the surface is required to enable the selection of the most appropriate surface texture to achieve a required functionality.This paper introduces measurement strategies and features considered as essential by SOMICRONIC when designing or developing 3D surface texture measuring instruments, knowing that the pursued aim is to assess the measured surface in a way to reveal the real surface. This is achieved without losing sight of existing ISO standardized concepts concerning surface texture profile analysis.Indeed, essentially for economical reasons, we consider that 31) surface texture stylus instruments must be designed to achieve classical surface texture profiles measurements and characterisations and to fulfil conditions and characteristics listed and described in existing surface texture ISO standards.We propose to develop in the next paragraphs, the following points:
- • - Design of the data acquisition unit of a 3D surface texture instrument
- • - Strategy for the measurement of the surface
- • - Application of these concepts - Examples.
6.
Virpi Oksman Ville Ollikainen Elina Noppari Carlos Herrero Antti Tammela 《Multimedia Systems》2008,14(2):105-114
Recently, mobile TV has been launched in several countries. While mobile TV integrates television contents into mobile phones,
the most personal of communication devices, it becomes interesting to know how this feature will be used throughout the day
and in varying contexts of everyday life. This paper presents empirical results on the use of mobile TV with different delivery
mechanisms and both quantitative and qualitative results on how end-users prefer to use mobile TV contents in different situations.
The data is based on ongoing empirical research in Finland in 2006 and 2007. The mobile TV services under study included both
news and entertainment contents, and were tested in 3G, DVB-H and Wi-Fi networks using different delivery paradigms: broadcast,
on-demand and download. To explore the use of different delivery methods and content consumption, we have developed a mobile
TV service protoype, called Podracing. The analysis shows that users appreciated up-to-date information and information-rich
media forms and contents especially for mobile news delivery. There was high demand for only the latest news on mobiles. The
real-time property was considered important. Most of the users looked at the headlines or followed the news several times
a day – much more often than the traditional TV and news prime times would allow. 相似文献
7.
Preconditioning is crucial for the convergence of GMRES iteration in the Harmonic Balance analysis of RF and microwave circuits. In this article, mixed frequency/time‐domain preconditioners for harmonic balance Jacobians are presented. The efficiency of mixed preconditioners is demonstrated with realistic simulation examples. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009. 相似文献
8.
Ville T. Heikkilä Maria Paasivaara Casper Lasssenius Daniela Damian Christian Engblom 《Empirical Software Engineering》2017,22(6):2892-2936
In a large organization, informal communication and simple backlogs are not sufficient for the management of requirements and development work. Many large organizations are struggling to successfully adopt agile methods, but there is still little scientific knowledge on requirements management in large-scale agile development organizations. We present an in-depth study of an Ericsson telecommunications node development organization which employs a large scale agile method to develop telecommunications system software. We describe how the requirements flow from strategy to release, and related benefits and problems. Data was collected by 43 interviews, which were analyzed qualitatively. The requirements management was done in three different processes, each of which had a different process model, purpose and planning horizon. The release project management process was plan-driven, feature development process was continuous and implementation management process was agile. The perceived benefits included reduced development lead time, increased flexibility, increased planning efficiency, increased developer motivation and improved communication effectiveness. The recognized problems included difficulties in balancing planning effort, overcommitment, insufficient understanding of the development team autonomy, defining the product owner role, balancing team specialization, organizing system-level work and growing technical debt. The study indicates that agile development methods can be successfully employed in organizations where the higher level planning processes are not agile. Combining agile methods with a flexible feature development process can bring many benefits, but large-scale software development seems to require specialist roles and significant coordination effort. 相似文献
9.
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