On the performance of improved quadrature spatial modulation

Quadrature spatial modulation (QSM) utilizes the in‐phase and quadrature spatial dimensions to transmit the real and imaginary parts of a single signal symbol, respectively. The improved QSM (IQSM) transmits two signal symbols per channel use through a combination of two antennas for each of the real and imaginary parts. The main contributions of this study can be summarized as follows. First, we derive an upper bound for the error performance of the IQSM. We then design constellation sets that minimize the error performance of the IQSM for several system configurations. Second, we propose a double QSM (DQSM) that transmits the real and imaginary parts of two signal symbols through any available transmit antennas. Finally, we propose a parallel IQSM (PIQSM) that splits the antenna set into equal subsets and performs IQSM within each subset using the same two signal symbols. Simulation results demonstrate that the proposed constellations significantly outperform conventional constellations. Additionally, DQSM and PIQSM provide a performance similar to that of IQSM while requiring a smaller number of transmit antennas and outperform IQSM with the same number of transmit antennas.     

Purification,structural data and biological properties of polysaccharide from Prunus amygdalus gum

This work demonstrates the efficiency of almond gum polysaccharides (AGPs) as bioactive compounds. AGPs were first extracted using H₂O₂, in the presence of NaOH, at different times and temperatures. The optimal extraction conditions were 4% H₂O₂ and 2 N NaOH, for 7 h at 50 °C, leading to an extraction yield of 58.2% (w/w). After a purification step, the retained AGPs were characterised using high‐performance liquid chromatography showing a molecular weight of 99.3 kDa. The monosaccharide composition of AGPs were assessed using gas chromatography–mass spectrometry. AGPs were found to be a complex heteropolysaccharide with a repeating unit mainly composed of galactose, arabinose, xylose, mannose, rhamnose, and glucuronic acid with the respective ratios: 45:26:7:10:1:11. The acidic nature of the polysaccharide is due to the presence of glucuronic acid. Total antioxidant activity, free radical‐scavenging activity and reducing power assay of AGPs were investigated. The obtained results showed high antioxidant activities of AGPs. Furthermore, beyond 60 mg mL^?1, AGPs exhibited bacterial growth inhibition for five pathogenic strains: Escherichia coli, Staphylococcus aureus, Enterococcus feacalis, Pseudomonas aeruginosa and Salmonella typhimurium.     

Morphology development in polyethylene/polystyrene blends: the influence of processing conditions and interfacial modification

The influence of processing conditions and interfacial modification on the morphology evolution and the composition range within which fully co‐continuous high density polyethylene/polystyrene blend structures can exist during blending in a single screw extruder was studied. Blends ranging from pure A to pure B component, with and without compatibilizer, were prepared under two different shear rates. It was found that high shear rates displaced the breakdown–coalescence balance of the dispersed nodules to the side of coalescence, narrowing the percolation domain and the critical composition for full co‐continuity decreased with increasing shear rates. The addition of a tri‐block compatibilizer induced the percolation threshold of the polystyrene phase to begin at lower percentages of polyethylene but the phase inversion point did not change. The experimental results are discussed in the light of various theoretical models. Copyright © 2005 Society of Chemical Industry     

Iterative scheme for MS image pansharpening based on the combination of multi-resolution decompositions

Image pansharpening in the remote-sensing domain may be defined as the technique of extracting high-resolution details from the panchromatic (PAN) image and injecting them into the multispectral (MS) one in a way to preserve the spectral signature and improve the spatial resolution. In this article, the authors propose an image fusion framework that tries to derive sharpened MS image such that: (i) when decimated taking into account the imagery system Modulation Transfer Function (MTF), it equals the original MS image; (ii) when decomposed using discrete wavelet transform (DWT), its geometrical details are those of the PAN image weighted by the compatibility PAN/MS. Indeed, MS sharpening is carried out in two steps. First, pre-pansharpened MS image is obtained using inverse DWT taking as approximations those of the upsampled original MS image and as details those of PAN (to reduce spectral distortion, PAN detail injection is performed proportionally to the similarity PAN/MS). Second, to satisfy (i) and to remove the PAN-MS disagreement, an iteration algorithm (alternatively corrects approximations and details) has been proposed. The proposed approach is designed in two versions inspired by the Generalized Laplacian Pyramid (GLP) and the Gram–Schmidt (GS) transformation, respectively.

To validate our approach, Pléiades-1A, Geoeye-1, and Landsat Enhanced Thematic Mapper Plus (ETM+) images are tested. The results of qualitative and quantitative scores are presented and discussed. Compared to well-known techniques, our approach shows generally better results, particularly the one based on GLP formalism.     

Non-Intrusive Monitoring of Everyday Behavioral Activities in an Indoor Environment

A non-intrusive design for monitoring everyday activities of an elderly person is presented. The proposed system is intended to be used in the bedroom, allowing the elders to stay at home in a safe environment. The required hardware design is simple in structure and cost effective. The sensor design is implemented by using capacitive sensors and an Arduino microcontroller unit. And a real time graphical user interface is implemented to monitor the elderly person. The performance analysis shows that the sensor design is able to differentiate between a human body and a house pet.     

A comparison of predictive measures of problem difficulty inevolutionary algorithms

This paper studies a number of predictive measures of problem difficulty, among which epistasis variance and fitness distance correlation are the most widely known. Our approach is based on comparing the reference class of a measure to a number of known easy function classes. First, we generalize the reference classes of fitness distance correlation and epistasis variance, and construct a new predictive measure that is insensitive to nonlinear fitness scaling. We then investigate the relations between the reference classes of the measures and a number of intuitively easy classes. We also point out the need to further identify which functions are easy for a given class of evolutionary algorithms in order to design more efficient hardness indicators for them. We finally restrict attention to the genetic algorithm (GA), and consider both GA-easy and GA-hard fitness functions, and give experimental evidence that the values of the measures, based on random samples, can be completely unreliable and entirely uncorrelated to the convergence quality and convergence speed of GA instances using either proportional or ranking selection     

NARP-HPLC/MS and silver cationization fingerprinting of triacylglycerols in wild and cultivar Tunisian peanut kernels

A simple strategy to identify triacylglycerols (TAGs) in wild and cultivar peanuts was performed using on line coupling of non-aqueous reversed phase chromatography-electrospray ionization–mass spectrometry (NARP-LC-ESI–MS) with silver nitrate (AgNO₃) as a post-column additive. The combination of the structural information given by MS with chromatographic retention laws led to the determination of the structure of TAGs in wild and cultivar peanut oil. In addition, by using the MS⁵ method, the regio-specificity of the TAGs was determined. It was also demonstrated that in Tunisian peanut oil, the saturates have a preference for the sn-1/sn-3 position for the arachidonic and behenic acids. In the wild variety fatty acids with odd numbers of carbons were found and more TAGs were identified in comparison to the cultivar peanut oil.     

The nonstationary strain filter in elastography: Part II. Lateral and elevational decorrelation

The nonstationary evolution of the strain filter due to lateral and elevational motion of the tissue scatterers across the ultrasound beam is analyzed for the 1-D cross-correlation-based strain estimator. The effective correlation coefficient that includes the contributions due to lateral and elevational signal decorrelation is used to derate the upper bound of the signal-to-noise ratio in the elastogram (SNRe) predicted by the ideal strain filter. In the case of an elastically homogeneous target, if the transducer is on the axis of symmetry of such target in the elevational direction, the motion of the scatterers out the imaging plane is minimized. In addition, the ultrasound beam along the elevational direction is broader, allowing scatterers to stay longer within the beam during tissue compression. Under these conditions, lateral signal decorrelation becomes the primary contributor to the nonstationary behavior of the strain filter. Both the elastographic SNRe and the dynamic range are reduced, with an increase in lateral decorrelation. Finite element simulations and phantom experiments are presented in this paper to corroborate the theoretical strain filter. The nonstationary behavior of the strain filter is reduced by confining the tissue in the lateral direction (minimizing motion of tissue scatterers), thereby improving the quality of the elastogram.     

Analysis of a type II hybrid ARQ scheme with codecombining

An analysis is presented of the selective-repeat type II hybrid AR Q (automatic-repeat-request) scheme, using convolutional coding and exploiting code combining. With code combining, at successive decoding attempts for a data packet, the decoder for error correction operates on a combination of all received sequences for that packet rather than only on the two most recent received ones as in the conventional type II hybrid ARQ scheme. It is shown by means of analysis and computer simulations that with code combining, a significant throughput is achievable, even at very high channel error rates     

Efficient ARQ schemes with multiple copy decoding

Several modifications of an efficient automatic repeat request (ARQ) scheme proposed by Weldon (see IEEE Trans. Commun., vol.COM-30, p.480, 1982) are studied. Unlike Weldon's scheme, in which all erroneous data packets are discarded, the present schemes make use of copies of the data packet which may contain errors. A number of channel models are considered, namely, a binary symmetric channel, a nonfading, and a Rayleigh fading channel with additive white Gaussian noise. In most cases, it is found that the throughput can be substantially increased. Under poor channel conditions, the use of forward error correction can lead to further improvement. A type-II ARQ scheme which does not suffer the throughput degradation under good channel conditions due to overhead parity bits associated with conventional forward error correction is also analyzed