Pilot-based carrier frequency offset estimation in OFDM systems

The ability of OFDM to mitigate channel frequency selectivity is impaired by its vulnerability to carrier frequency offset (CFO). In this paper, a new pilot-based carrier frequency offset estimation scheme for frequency selective slowly-varying channels is proposed. This scheme exploits the inherent redundancy introduced by the OFDM signaling and no additional training symbol is needed. The synchronization process is to minimize a LMS-like cost function, which essentially quantifies the variance of the pilot tones across several OFDM symbols. Moreover, a reduced-complexity estimator is also developed to reduce the implementation complexity. The CFO estimation range can span the whole OFDM signal bandwidth by nonuniformly distributing the embedded pilot tones in the frequency domain. Computer simulation results show that the performance of the proposed estimator can meet the requirement of typical OFDM communication systems.published_or_final_versio

High compression ratio image processing techniques using combinations of WT and IFS

Many works of compressing image based on wavelet transformation have been presented in recent years. Also, the method of fractals is used in this field. The first method uses the pyramid subband decomposition, and the second takes advantage of the self-similarity between the basic image and subimages. We combine these two methods as a hybrid algorithm to complete the image compression. The experiments show that this method has a better performance than many others, especially, in a high compression ratio situation. A comparison with the famous embedded zero tree wavelet (EZW) algorithm shows that its performance is close to the EZW algorithm.published_or_final_versio

Recording of natural head position using stereophotogrammetry: A new technique and reliability study

The purpose of this study was to develop a technique to record physical references and orient digital mesh models to natural head position (NHP) using stereo-photogrammetry (SP). The first step was to record the digital mesh model of a hanging reference board placed at the capturing position of the SP machine. The board was aligned to the true vertical using a plumb bob. It was also aligned with laser plane parallel to the hanging mirror which was located at the center of the machine. Parameter derived from the digital mesh model of the board was then used to adjust the roll, pitch and yaw of the subsequent captures of subjects. This information was valid until the next machine calibration. The board placement was repeatable with standard deviation of less than 0.1 degrees for both pitch and yaw; 0.15 degrees for roll angles.postprin

Optimal designs for an additive quadratic mixture model involving the amount of mixture

This paper is concerned with D- and A-optimal designs for a quadratic additive model for experiments with mixtures, in which the response depends not only on the relative proportions but also on the actual amounts of the mixture components. It is found that the origin and vertices of the simplex are support points of these optimal designs, and when the number of mixture components increases, other support points shift gradually from barycentres of depth 1 to barycentres of higher depths. It is shown that the D-optimal designs have high efficiency in terms of A-optimality, and vice versa.published_or_final_versio

The Efficacy of Triamcinolone Acetonide in Keloid Treatment: A Systematic Review and Meta-analysis

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BEX3 contributes to cisplatin chemoresistance in nasopharyngeal carcinoma

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Influence of transport and ocean ice extent on biogenic aerosol sulfur in the Arctic atmosphere

The recent decline in sea ice cover in the Arctic Ocean could affect the regional radiative forcing via changes in sea ice-atmosphere exchange of dimethyl sulfide (DMS) and biogenic aerosols formed from its atmospheric oxidation, such as methanesulfonic acid (MSA). This study examines relationships between changes in total sea ice extent north of 70 degrees N and atmospheric MSA measurement at Alert, Nunavut, during 1980-2009; at Barrow, Alaska, during 1997-2008; and at Ny-Alesund, Svalbard, for 1991-2004. During the 1980-1989 and 1990-1997 periods, summer (July-August) and June MSA concentrations at Alert decreased. In general, MSA concentrations increased at all locations since 2000 with respect to 1990 values, specifically during June and summer at Alert and in summer at Barrow and Ny-Alesund. Our results show variability in MSA at all sites is related to changes in the source strengths of DMS, possibly linked to changes in sea ice extent as well as to changes in atmospheric transport patterns. Since 2000, a late spring increase in atmospheric MSA at the three sites coincides with the northward migration of the marginal ice edge zone where high DMS emissions from ocean to atmosphere have previously been reported. Significant negative correlations are found between sea ice extent and MSA concentrations at the three sites during the spring and June. These results suggest that a decrease in seasonal ice cover influencing other mechanisms of DMS production could lead to higher atmospheric MSA concentrations

Active routing service for the next-generation network/ISDN3

In recent years, a new routing method, known as active routing, has been emerging. This involves using active packets to configure customized network paths. Based on a Markov decision model, this paper presents an active routing service for active networks in general and the next generation network, called ISDN3, in particular. Our aim is to determine the active routing policy so as to minimize the network cost. Theoretical analysis is presented to show the advantages of our proposal as compared with three other approaches.published_or_final_versio

ISDN3: The next generation networks

Two generations of Integrated Services Digital Network (ISDN), namely ISDN1 and ISDN2, have been developed in the last century. In our view, the convergence of ATM, Internet and active networks will form the basis for the next generation networks called ISDN3. In this paper, we first review ISDN1 and ISDN2 as well as the Internet and active networks. We then discuss some fundamental questions related to the design of ISDN3. Finally, we compare ISDN3 with ISDN1 and ISDN2, and outline what ISDN3 might look like.published_or_final_versio