Soil water content and freezing temperature affect freeze–thaw related N2O production in organic soil

An organic agricultural soil was exposed to freeze–thaw cycles (FTC) using either intact soil cores or cores packed with homogenized soil. The cores were first exposed to two mild FTCs (–1.5°C/+4°C) with soil water content being 56–85% of the water-filled pore space (WFPS). Both intact and packed soil cores showed high N₂O emissions when the soil was thawing and had high WFPS. The second freeze–thaw cycle induced lower N₂O emission than the first. After the mild FTCs, a deep frost (–15°C) was applied. This greatly increased the N₂O emissions when the soil was thawing. Freezing–thawing had a smaller effect on CO₂ than on N₂O release. The results show that both soil moisture and the severity of frost modify the N₂O burst after thawing, and N₂O release (denitrification) was favoured more by FTC than heterotrophic microbial activity (CO₂ production) in general. The possible reason for this difference is discussed.     

Parallel Interference Cancellation in Multiuser CDMA Channel Estimation

Parallel interference cancellation (PIC) based channel parameter estimators for frequency selective fading channels are proposed for the uplink in code-division multiple-access (CDMA) mobile communication systems. The performance of PIC based algorithms depends heavily on the quality of the multiple-access interference estimates, which can be improved by using adaptive channel estimation filters. The performance of two adaptive complex channel coefficient estimation filters has been verified in a fading channel by computer simulations. According to the results, the PIC based adaptive channel estimators outperform clearly conventional, successive interference cancellation, and decorrelation based adaptive channel estimators. The PIC method is also used in delay tracking. By using the principles of sample-correlate-choose-largest (SCCL) delay trackers, a robust algorithm for multiuser delay tracking in fading channels is obtained.     

Efficient Resource Allocation and Paving the Way Towards Highly Efficient IMT-Advanced Systems

Recently, new network topologies including relays and meshed networks have emerged as a key technology receiving a lot of attention due to the increasing need for additional resources such as spectrum, and required high data-rates specified by the International Mobile Telecommunication-Advanced (IMT-Advanced) systems (Report ITU-R M.1645, Framework and overall objectives of the future development of IMT-2000 and systems beyond IMT-2000). These systems are designed to provide diverse services sustaining low to high mobility applications and yielding a significant improvement in terms of Quality-of-Service (QoS). In this paper, we identify and describe the novel network topologies that will be able to accommodate the high data rates demanded within the spectrum scarcity paradigm. By efficiently integrating mesh networks and flexible resource sharing, the overall network efficiency is shown to increase. In addition, direct terminal-to-terminal (T2T) communication both with and without the use of relays is presented, where terminals communicate without the use of base stations (BSs) as it is done in conventional systems. The results show significant gains in terms of throughput, average frame delays and power consumption compared to conventional networks. Finally, open issues and potential challenges are addressed.

Rational Nanotoolbox with Theranostic Potential for Medicated Pro‐Regenerative Corneal Implants

Cornea diseases are a leading cause of blindness and the disease burden is exacerbated by the increasing shortage around the world for cadaveric donor corneas. Despite the advances in the field of regenerative medicine, successful transplantation of laboratory‐made artificial corneas is not fully realized in clinical practice. The causes of failure of such artificial corneal implants are multifactorial and include latent infections from viruses and other microbes, enzyme overexpression, implant degradation, extrusion or delayed epithelial regeneration. Therefore, there is an urgent unmet need for developing customized corneal implants to suit the host environment and counter the effects of inflammation or infection, which are able to track early signs of implant failure in situ. This work reports a nanotoolbox comprising tools for protection from infection, promotion of regeneration, and noninvasive monitoring of the in situ corneal environment. These nanosystems can be incorporated within pro‐regenerative biosynthetic implants, transforming them into theranostic devices, which are able to respond to biological changes following implantation.     

Ion beam mixing of Au marker in Pt and Pt marker in Au by 7 MeV Ag ions

Mixing of a thin Au layer in Pt and in reversed conditions mixing of a thin Pt layer in Au due to bombardment with 7 MeV Ag ions has been measured. The Pt-Au multilayers deposited on a Si substrate were irradiated to doses of 1–6 × 10¹⁵ ions cm⁻² at room temperature. The mixed profiles were measured using a SIMS apparatus with O₂⁺ sputter ions at energy 2.5 keV. The width of the Pt marker increased from 90 to 260 Å with increasing dose. The width of the Au marker increased from 80 to 90 Å, respectively. The corresponding mixing efficiencies are 5 ± 3 (Au marker) and 90 ± 30 Å⁵/eV (Pt marker). The experimental results are compared with simulations based on a model which describes the atomic transport from the initial collisional phase to the late thermalized stage. The calculated values for mixing efficiencies agree reasonably well with experimental values.     

On metricity of two heterogeneous measures in the presence of missing values

Heterogeneous Euclidean-overlap metric and heterogeneous value difference metric given in machine learning literature are useful for the consideration of mixed-type data for machine learning, pattern recognition and data mining tasks. Mixed-type variables are quite common in practical problems, but this property has been taken into account only seldom in pattern recognition, data mining and decision making algorithms. We observed that these two distance measures are not actually metrics after having found a special situation when they are not metric, but pseudometric, a feature to be noted while using them. Nevertheless, by changing their definitions somewhat, it is possible to meet the metricity. Especially in medical applications, the redefinition of the two measures might be important, since otherwise it is possible in theory that, for example, two identical cases would be classified differently. Nearest neighbor searching tests with medical data were run to illustrate the behavior of these measures. Notwithstanding the violation of the metricity their original forms yielded slightly better classification results. The reason was that in real data sets tested there were very few almost similar cases according to these distance measures, and the original forms based on more separating distances than the redefinitions were slightly better in the classification.     

Power boiler fuel augmentation with a biomass fired atmospheric circulating fluid-bed gasifier

The successful experience in developing the advanced Foster Wheeler atmospheric circulating fluidized-bed (ACFB) combustion system subsequently led to the development of the ACFB gasification (ACFBG) Technology in the early 1980s. The driving force for the development work was the dramatic increase in oil price during this period. The primary advantage of the ACFBG technology is that it enables the substitution of expensive fuels (e.g. oil or gas) with cheaper solid fuels. Prior to this Lahti project, Foster Wheeler had supplied four waste wood fired commercial scale ACFBGs in the mid-1980s to the pulp and paper industry with capacities from 17 to 35 MW_th based on fuel input. These units are still in successful operation today. Lahden Lämpövoima Oy (LLOy) is a Finnish power company producing power and district heat for the City of Lahti. The company is jointly owned by the city of Lahti and by Fortum Oy, the largest utility power company in Finland. LLOy operates the Kymijärvi Power Plant located nearby the city of Lahti in Southern Finland. To keep the energy prices as low as possible, Plant personnel are continuously looking for the most economical fuel sources, and simultaneously, trying to improve the environmental aspects of the energy production. Currently, about 300 GW h/a of different types of biofuels and refuse fuels are available in the Lahti area. On an annual basis, the available amount of biofuels and refuse fuels is enough to substitute for about 15% of the fuels burned in the main boiler, equaling up to 30% of the coal typically used. The aim of the LLOy Kymijärvi Power Plant gasification project is a commercial scale demonstration of direct gasification of wet biofuel and the use of hot, raw and very low calorific gas directly in the existing coal fired boiler. The gasification of biofuels and co-combustion of gases in the existing coal-fired boiler offers many advantages such as: recycling of CO₂, decreased SO₂ and NO_x emissions, efficient way to utilize biofuels and recycled refuse fuels, low investment and operation costs, and utilization of the existing power plant capacity. Furthermore, only small modifications were required in the boiler and process upsets in the gasifier do not shut down the power plant. The first two years of operation (1998 and 1999) have been excellent with good availability for the gasifier and its related components. During 1998 several measurements and tests with different fuel combinations were performed. This paper presents the project in detail as well as the most important results of the first measurements. The EU Thermie program has supported this project.     

Solid-State Reactions between Cu(Ni) Alloys and Sn

Solid-state interfacial reactions between Sn and Cu(Ni) alloys have been investigated at the temperature of 125°C. The following results were obtained. Firstly, the addition of 0.1 at.% Ni to Cu decreased the total thickness of the intermetallic compound (IMC) layer to about half of that observed in the␣binary Cu/Sn diffusion couple; the Ni addition decreased especially the thickness of Cu₃Sn. Secondly, the addition of 1 to 2.5 at.% Ni to Cu further decreased the thickness of Cu₃Sn, increased that of Cu₆Sn₅ (compared to that in the binary Cu/Sn couple) and produced significant amount of voids at the Cu/Cu₃Sn interface. Thirdly, the addition of 5 at.% Ni to Cu increased the total thickness of the IMC layer to about two times that observed in the binary Cu/Sn diffusion couple and made the Cu₃Sn disappear. Fourthly, in contrast to the previous case, the addition of 10 at.% Ni to Cu decreased the total IMC (Cu₆Sn₅) thickness again close to that of the Cu/Sn couple. With this Ni content no voids were detected. The results are rationalized with the help of␣the thermodynamics of the Sn-Cu-Ni system as well as with kinetic considerations.     

Cold temperature PM emissions measurement: method evaluation and application to light duty vehicles

This work examines the methodology to sample and measure the number and size of motor vehicle particulate emissions (PM) at subambient temperatures. The study has two principal objectives. The first is to address the following question: which aspects of the particle sampling, dilution, and size measurement process must be made at the vehicle test temperature to obtain an accurate representation of the PM emissions? The second is to perform a preliminary overview of how subambient temperature operation affects PM emissions from the major classes of current model light duty vehicles. The principal findings are the following: (1) The temperature of the particle size instruments, test cell versus room temperature, has little effect on the measurements. (2) Once the engine has warmed, solid particle (soot) mode emissions in the cold test cell are similar to those at room temperature. The first finding simplifies cold temperature emissionstesting because it allows particle sizing instruments to be placed outside the cold test cell and operated at room temperature. The latter is consistent with the expectation that solid particles are formed in the engine and are therefore relatively unaffected by ambient conditions after engine warm-up. Use of cold dilution air in the room-temperature test cell increases the number and size of nuclei particles; however, the effect of dilution airtemperature was inconclusive in the cold test cell.