Matrix Coded Modulation: A New Non-coherent MIMO Scheme

This paper describes a new space-time coding scheme for non-coherent multi-antenna multi-input multi-output (MIMO) systems. This new MIMO scheme merges error-correcting and space-time coding functions by transmitting invertible matrices, so this scheme has been called “Matrix Coded Modulation” or “MCM”. Coherent systems require channel state information (CSI) at the transmitters and/or at the receivers, and their performances strongly depend on the channel estimation. For example, in systems using Orthogonal frequency division multiplexing, the channel estimation requires the insertion of pilot-symbols in the transmitted frame which implies a spectral efficiency loss of the global system that increase with the number of transmit antennas. The existing non-coherent schemes such as the differential space-time modulation leads to performance degradation compared to coherent systems in which perfect CSI is assumed. Decoding in the MCM scheme is performed iteratively, based on a specified detection criteria. In the proposed MCM scheme, decoding can be achieved with or without CSI at the receiving antennas. As the space-time coding function is merged with the error-correcting code, the euclidean distances distribution between modulated signals based on the detection criteria is strongly linked to the Hamming weights distribution of the channel error-correcting code used in the MCM scheme. Moreover, a low-complexity decoding algorithm is described and compared to the existing differential schemes.     

Matrix Coded Modulation: A New Non-coherent MIMO Scheme

This paper describes a new space-time coding scheme for non-coherent multi-antenna Multi-Input Multi-Output (MIMO) systems. This new MIMO scheme merges error-correcting and space-time coding functions by transmitting invertible matrices, so this scheme has been called “Matrix Coded Modulation” or “MCM”. Coherent systems require Channel State Information (CSI) at the transmitters and/or at the receivers, and their performances strongly depend on the channel estimation. For example, in systems using Orthogonal Frequency Division Multiplexing, the channel estimation requires the insertion of pilot-symbols in the transmitted frame which implies a spectral efficiency loss of the global system that increase with the number of transmit antennas. The existing non-coherent schemes such as the Differential Space-Time Modulation leads to performance degradation compared to coherent systems in which perfect CSI is assumed. Decoding in the MCM scheme is performed iteratively, based on a specified detection criteria. In the proposed MCM scheme, decoding can be achieved with or without CSI at the receiving antennas. As the space-time coding function is merged with the error-correcting code, the euclidean distances distribution between modulated signals based on the detection criteria is strongly linked to the Hamming weights distribution of the channel error-correcting code used in the MCM scheme. Moreover, a low-complexity decoding algorithm is described and compared to the existing differential schemes.     

Remote Field Eddy Current Control Using Rotating Magnetic Field Transducer: Application to Pressure Tubes Examination

The remote field eddy current (RFEC) technique is used to investigate the possibility of detecting the discontinuities practiced on pressure tubes samples from nuclear reactors, pressurized heavy water reactors (PHWR) type. In this article, we propose to develop the RFEC using the technique of rotating magnetic field (RMF). A method for calculating the field generated by the eddy current transducer with RMF using propagator matrix was developed. The experimental measurements are realized for artificial discontinuities practiced in pressure tubes samples.     

Electromagnetic metamaterials

This paper proposes a review of electromagnetic metamaterials based on the idea that these are composite materials, their properties depending of the type and dimensions of the structural elements as well as the dimensions of unit cell. From the multitude of structural elements, only few that could present negative permittivity and negative or very high permeability in the range of radio and microwave frequency were chosen. The method of determination for the constitutive parameters (μ_eff and ?_eff) of metamaterials based on the S parameters or transmission and reflection coefficients is presented. Moreover, some applications of metamaterials are described, the attention being focused on perfect lenses and novel structures, namely conical Swiss rolls, electromagnetic cloaks and sensors for nondestructive evaluation of materials. Given that the spatial resolution of these sensors can be substantially improved in comparison to classical sensors, the metamaterial lenses are used for the manipulation of evanescent waves.     

Properties and drug release profile of poly(N-isopropylacrylamide) microgels functionalized with maleic anhydride and alginate

This study highlights the advantages of functionalized poly(N-isopropylacrylamide) (PNIPAAm) microgels over pure PNIPAAm microgels in terms of polymer network properties and drug release profiles. PNIPAAm network was modified by addition of maleic anhydride (MA) as a comonomer and by formation of interpenetrating polymer network in the presence of alginate. The functionalized thermosensitive microgels in the size range from 20 to 80 μm and with better performance in comparison with pure PNIPAAm microgels were prepared by inverse suspension polymerization. The impact of MA and alginate on the PNIPAAm microgel structure was evaluated through analysis of microgel size, size distribution, volume phase transition temperature (VPTT), equilibrium swelling ratio as well as morphology of the system. It was shown that the controlled modification of PNIPAAm network could result in microgels of considerably improved swelling capacity with unchanged thermosensitivity and maintained open pore morphology. In addition, drug release behavior of microgels could be markedly altered. Release of procaine hydrochloride from the selected microgels was studied using Franz diffusion cell at temperatures below and above VPTT of the microgels. Temperature-controlled drug release pattern was dependent on the type of functionalization of PNIPAAm network. According to drug loading properties and drug release mechanism, PNIPAAm/MA copolymer microgels demonstrated the optimal performances.     

KTa0.6Nb0.4O3 ferroelectric thin film behavior at microwave frequencies for tunable applications.

In this study about the relationships between structural and microwave electrical properties of KTa(1-x)NbxO3 (KTN) ferroelectric materials, a KTN thin film was deposited on different substrates to investigate how KTN growth affects the microwave behavior. Interdigital capacitors and stubs were made on these films through a simple engraving process. Microwave measurements under a static electric field showed the importance of the substrate on the circuit behavior and, notably, on the tuning factor.     

Inter-domain security for mobile IPv6

Mobile IPv6 is only adapted to the mobile’s movements within its own administrative domain. As Mobile IPv6 is expected to be the basis for beyond 3G networks, a solution for inter-domain security is required allowing the visited domain to authenticate any mobile to grant it access. As such, new concepts known as AAA for Authentication, Authorization, Accounting were defined by the IETF. The IETF is currently defining the Diametr protocol to support those three functions in a Mobile IPv4 environment. Today’s difficulty is to adapt the Diameter protocol to Mobile IPv6. After introducing the Mobile IPv6, IPsec and Diameter protocols, this paper presents our solution (IETF draft of December 2001), and an IETF alternative for adapting Diameter to Mobile IPv6. It gives a comparison and describes our prototype.     

Clairvoyance and online scheduling in real-time energy harvesting systems

Real-time energy harvesting systems are designed using a microprocessor, a rechargeable energy storage unit and an energy harvester. The theoretical analysis shows that an optimal solution to the underlying online scheduling problem requires time lookahead which can be incompatible with the common stochastic nature of ambient energy.     

Fully depleted double-gate MSDRAM cell with additional nonvolatile functionality

We demonstrate a new fully depleted (FD) double-gate (DG) MSDRAM cell, which features SONOS type storage node at the back-gate (control-gate). This single-transistor cell, based on the meta-stable dip (MSD) hysteresis effect, can also be operated in non-volatile memory (NVM) mode. The NVM functionality is achieved by Fowler–Nordheim tunneling hole injection into the nitride storage node; the injected holes induce a permanent inversion layer in silicon body. The proposed device shows a large current ratio between ‘1’ and ‘0’ states (～10³) and a wide memory window (～3 V). The effect of the NVM functionality on the MSD hysteresis was investigated and combined with the effect of the control-gate bias. The SONOS charging can be used for replacing the second gate (i.e. enabling single-gate MSDRAM) or for achieving ‘unified’ memory operation.     

Multifilament fibres of poly(?-caprolactone)/poly(lactic acid) blends with multiwalled carbon nanotubes as sensor materials for ethyl acetate and acetone

Conductive poly(?-caprolactone) (PCL) + 4% multiwalled carbon nanotubes (MWCNTs)/poly(lactic acid) (PLA) = 50/50 wt% blend multifilament fibres were melt-spun and a woven textile was made by a handloom with the conductive fibres in weft direction. The fibres were tested for cyclic liquid sensing in ethyl acetate and acetone as two moderate solvents and in ethanol as a poor solvent. The liquid sensing responses, namely the relative resistance changes R_rel relating the resistance change to the initial resistance of the samples on contact with ethyl acetate and acetone, were fast (R_rel higher than 16 after 100 s), with high amplitudes (R_rel higher than 23 after 500 s), and well reproducible. At the same time, the fibres were resistant against these solvents. The response to ethanol was also reproducible, however, very slow and with low amplitude.PLA was found to crystallize during the immersion process, whereas in PCL the crystalline domains transformed into amorphous ones as studied by Wide Angle X-ray Diffraction. The crystallization of PLA does not influence negatively the liquid sensing properties which can be assigned to the finding that the MWCNT are predominantly localized in the PCL phase as confirmed by Scanning Electron Microscopy.In the final step, a textile based on those fibres was prepared and its sensing behaviour was investigated on ethyl acetate and acetone clearly showing that such textiles are suitable to detect these solvents.