Повышение устойчивости газонефтепроводов при прокладке их в неблагоприятных районах Крайнего Севера

Актуальность темы работы связана с тем, что главную опасность для трубопроводов, проложенных в многолетнемерзлых грунтах, представляет оттаивание грунта вокруг трубопровода.The relevance of the topic of the work is related to the fact that the main danger for pipelines laid in permafrost soils is thawing of the soil around the pipeline

Two-layer LMDS system architecture: DAVIC-based approach and analysis

Despite the growing interest for LMDS systems there have been only a few commercial implementations until now especially outside of the U.S.A. The use of hierarchical structure through two-layer networking has been even rarer. In many cases LMDS systems have strong advantages against their competitors to cover the last mile. In this article, we review and analyze the standards currently available and describe the European two-layer trial system developed in 1996-2000. We show why further development towards IP based LMDS is useful in the future. Most of our recommendations are based on results derived from the European Union supported research project CABSINET. It had the aim of demonstrating the viability of a 40 GHz cellular digital television system with a return channel to offer interactive services. Two systems were tested: a line of sight link using QPSK, and a non-line of sight with COFDM modulation scheme. In the RF-subsystems, the greatest difficulty of any viable LMDS system is to obtain a moderately low price for the user receiver, while fulfilling the hard OFDM requirements in terms of phase noise, stability and spectrum restrictions. Several options have been studied in order to design the subsystems with the smallest cost. This paper will present the architectures of the transmitters, nomadic terminals, and the design of the IF/RF subsystems for both types of modulations. The discussion is focused on system engineering and selections required in order to build a full two-layer LMDS system.This work has been supported in part by European Commission through the ACTS programme (CABSINET project). PM is in part supported by the Academy of Finland (grant 50624). Authors wish to thank the CABSINET research consortium for enjoyable collaboration and useful suggestions

The Rebound Effect in the Aviation Sector

The rebound effect, i.e., the (partial) offset of the energy efficiency improvement potential due to a reduction in marginal usage costs and the associated increase in consumer demand, has been extensively studied for residential energy demand and automobile travel. This study presents a quantitative estimate of the rebound effect for an air traffic network including the 22 busiest airports, which serve 14 of the highest O-D cities within the domestic U.S. aviation sector. To satisfy this objective, passenger flows, aircraft operations, flight delays and the resulting energy use are simulated. Our model results indicate that the average rebound effect in this network is about 19%, for the range of aircraft fuel burn reductions considered. This is the net impact of an increase in air transportation supply to satisfy the rising passenger demand, airline operational effects that further increase supply, and the mitigating effects of an increase in flight delays. Although the magnitude of the rebound effect is small, it can be significant for a sector that has comparatively few options for reducing greenhouse gas emissions

Design and performance of a flexible wavelet based multicarrier modulation for wireless communications

In the last decade, progress in digital signal processing has led to major changes in the wireless communication world. In particular, the transition from single carrier to multicarrier has resulted in a significant improvement in performance. To this day, however, virtually no commercial application uses a multicarrier modulation based on anything else than Orthogonal Frequency Division Multiplex (OFDM). This thesis analyses the design and performance of the Wavelet Packet Modulation (WPM), an alternative multicarrier modulation based on the wavelet packet transform. While swapping sine waves for wavelets as subcarrier waveforms is conceptually a simple change, it does allow the new modulation scheme to benefit from the properties of the versatile transform that the WPT is. This study begins with the mathematical basis of the WPT, the core element of a WPM transceiver. Its design and implementation architecture are derived and compared. In particular, we show that the WPT has more degrees of freedom than the DFT, and we explain how this extra freedom can be exploited in a wireless communication system. The performance of this new scheme over various wireless channels are reported and the differences with OFDM are highlighted whenever relevant. The issue of equalisation for WPM signal is extensively discussed and quantitative comparison with the extremely efficient cyclic based OFDM equalisation method is made. As it is equally important for the successful deployment of commercial systems, characterisation of WPM performance under common system distortion such as sampling frequency offset and power amplifier non-linearity has almost been made. A synchronisation method capable of tolerating large sampling frequency offset is also proposed. Overall, the performance of WPM in wireless propagation channel is shown to be comparable to the OFDM scheme. Equalisation of the latter is however easier thanks to the use of a cyclic prefix. As the implementation complexity of both schemes is of the same order, the advantage of WPM resides undeniably in its degree of freedom. The possibility of choosing both a particular wavelet and an arbitrary decomposition in the time-frequency domain gives the opportunity to optimise the modulated signal according to the application at hand. Nevertheless, further work remains to be carried out on equalisation in order for WPM to have a role in next generation communication systems

Design and performance of a flexible wavelet based multicarrier modulation for wireless communications

In the last decade, progress in digital signal processing has led to major changes in the wireless communication world. In particular, the transition from single carrier to multicarrier has resulted in a significant improvement in performance. To this day, however, virtually no commercial application uses a multicarrier modulation based on anything else than Orthogonal Frequency Division Multiplex (OFDM). This thesis analyses the design and performance of the Wavelet Packet Modulation (WPM), an alternative multicarrier modulation based on the wavelet packet transform. While swapping sine waves for wavelets as subcarrier waveforms is conceptually a simple change, it does allow the new modulation scheme to benefit from the properties of the versatile transform that the WPT is. This study begins with the mathematical basis of the WPT, the core element of a WPM transceiver. Its design and implementation architecture are derived and compared. In particular, we show that the WPT has more degrees of freedom than the DFT, and we explain how this extra freedom can be exploited in a wireless communication system. The performance of this new scheme over various wireless channels are reported and the differences with OFDM are highlighted whenever relevant. The issue of equalisation for WPM signal is extensively discussed and quantitative comparison with the extremely efficient cyclic based OFDM equalisation method is made. As it is equally important for the successful deployment of commercial systems, characterisation of WPM performance under common system distortion such as sampling frequency offset and power amplifier non-linearity has almost been made. A synchronisation method capable of tolerating large sampling frequency offset is also proposed. Overall, the performance of WPM in wireless propagation channel is shown to be comparable to the OFDM scheme. Equalisation of the latter is however easier thanks to the use of a cyclic prefix. As the implementation complexity of both schemes is of the same order, the advantage of WPM resides undeniably in its degree of freedom. The possibility of choosing both a particular wavelet and an arbitrary decomposition in the time-frequency domain gives the opportunity to optimise the modulated signal according to the application at hand. Nevertheless, further work remains to be carried out on equalisation in order for WPM to have a role in next generation communication systems

Wavelet Packet Modulation for Wireless Communications

Abstract — As proven by the success of OFDM, multicarrier modulation has been recognized as an efficient solution for wireless communications. Waveform bases other than sine functions could similarly be used for multicarrier systems in order to provide an alternative to OFDM. In this article, we study the performance of wavelet packet transform modulation (WPM) for transmission over wireless channels. This scheme is shown to be overall quite similar to OFDM, but with some interesting additional features and improved characteristics. A detailed analysis of the system’s implementation complexity as well as an evaluation of the influence of implementation-related impairments are also reported. Index Terms — Wavelet packet modulation, multicarrier modulation, orthogonal waveform base

Ocean forced variability of the main East Antarctic Glacier

A large volume of the East Antarctic Ice Sheet drains through the Totten Glacier (TG) and is thought to be a potential source of substantial global sea level rise over the coming centuries. We show the flow and surface height of floating part of TG, which buttresses the grounded component, have varied substantially over two decades (1989–2011), with variations in surface height and basal melt rates highly anti-correlated (r=0.70, p <0.05). Coupled glacier/ice-shelf simulations confirm ice flow and thickness respond to both basal melting of the ice shelf and grounding on bed obstacles. We conclude the observed variability of TG is primarily ocean-driven and enhanced ice-sheet dynamism, leading to upstream grounded ice loss, will occur from the region with ocean warming

Artemisinin Blocks Prostate Cancer Growth and Cell Cycle Progression by Disrupting Sp1 Interactions with the Cyclin-dependent Kinase-4 (CDK4) Promoter and Inhibiting CDK4 Gene Expression*

Artemisinin, a naturally occurring component of Artemisia annua, or sweet wormwood, is a potent anti-malaria compound that has recently been shown to have anti-proliferative effects on a number of human cancer cell types, although little is know about the molecular mechanisms of this response. We have observed that artemisinin treatment triggers a stringent G1 cell cycle arrest of LNCaP (lymph node carcinoma of the prostate) human prostate cancer cells that is accompanied by a rapid down-regulation of CDK2 and CDK4 protein and transcript levels. Transient transfection with promoter-linked luciferase reporter plasmids revealed that artemisinin strongly inhibits CDK2 and CDK4 promoter activity. Deletion analysis of the CDK4 promoter revealed a 231-bp artemisinin-responsive region between -1737 and -1506. Site-specific mutations revealed that the Sp1 site at -1531 was necessary for artemisinin responsiveness in the context of the CDK4 promoter. DNA binding assays as well as chromatin immunoprecipitation assays demonstrated that this Sp1-binding site in the CDK4 promoter forms a specific artemisinin-responsive DNA-protein complex that contains the Sp1 transcription factor. Artemisinin reduced phosphorylation of Sp1, and when dephosphorylation of Sp1 was inhibited by treatment of cells with the phosphatase inhibitor okadaic acid, the ability of artemisinin to down-regulate Sp1 interactions with the CDK4 promoter was ablated, rendering the CDK4 promoter unresponsive to artemisinin. Finally, overexpression of Sp1 mostly reversed the artemisinin down-regulation of CDK4 promoter activity and partially reversed the cell cycle arrest. Taken together, our results demonstrate that a key event in the artemisinin anti-proliferative effects in prostate cancer cells is the transcriptional down-regulation of CDK4 expression by disruption of Sp1 interactions with the CDK4 promoter