Performance of ultra wide band system using nonlinear receiver in the presence of interference

The performance of a time hopping combined with pulse position modulation ultra wide band system with a nonlinear receiver using an adaptive filter and a soft-limiter in the presence of narrowband interference has been considered. This system brings a significant performance improvement compared with the system that uses an adaptive filter and a linear receiver, particularly in the case of high-interference power where its absence leads to the reception loss. Also, the proposed receiver has much better interference rejection performance compared with minimal mean-square error interference rejection, in case of high-interference power (interference to signal ratios from 30 to 65 dB).     

Multi-domain collaborative exploration mechanisms for query expansion in an agent-based filtering framework

Novice users often do not have enough domain knowledge to create good queries for searching information on-line. To help alleviate the situation, exploration techniques have been used to increase the diversity of the search results so that not only those explicitly asked will be returned, but also those potentially relevant ones will be returned too. Most existing approaches, such as collaborative filtering, do not allow the level of exploration to be controlled. Consequently, the search results can be very different from what is expected. We propose an exploration strategy that performs intelligent query processing by first searching usable old queries, and then utilising them to adapt the current query, with the hope that the adapted query will be more relevant to the user’s areas of interest. We applied the proposed strategy to the implementation of a personal information assistant (PIA) set up for user evaluation for 3 months. The experimental results showed that the proposed exploration method outperformed collaborative filtering, and mutation and crossover methods by around 25% in terms of the elimination of off-topic results.     

Structural,morphological and up-converting luminescence characteristics of nanocrystalline Y2O3:Yb/Er powders obtained via spray pyrolysis

Sub-micronic, spherical Y₂O₃:Yb/Er particles comprising clustered nano-units (70 nm) were prepared via ultrasonic spray pyrolysis from pure nitrate precursor solutions with different Yb/Er dopant ratios. The particles were additionally thermally treated at 1100 °C for 12, 24 and 48 h. The structural and morphological characteristics of particles were studied by X-ray powder diffraction, Fourier transform infrared spectroscopy, field-emission scanning electron microscopy, energy dispersive X-ray analysis and specific surface area (BET) and were further correlated with their advanced optical properties. For the recorded up-conversion emissions, originating from the following Er³⁺ transitions: [²H_9/2→⁴I_15/2] in blue (407–420 nm); [²H_11/2, ⁴S_3/2→⁴I_15/2] green: 510–590 nm; and [⁴F_9/2→⁴I_15/2] in red (640–720 nm) spectral region, the corresponding lifetimes were acquired in the wide temperature range (10–300 K). The most intense green up-conversion emission with the long decay of 550 ms is recorded for Y_1.97Yb_0.02Er_0.01O₃ particles thermally treated at 1100 °C for 24 h.     

Nanostructured alumina particles synthesized by the Spray Pyrolysis method: microstructural and morphological analyses

Ultrafine particles or nanoparticles (ranging from a few nanometers to 100 nm) are of considerable interest for a wide variety of applications, ranking from catalyst to luminescence ceramics, due to their unique and improved properties primarily determined by size, composition and structure. This study presents the preparation and characterization of nanostructured spherical alumina particles by the Spray Pyrolysis method for the application in reinforcements of metal-matrix composites (MMCs). Synthesis procedure includes aerosol formation ultrasonically from alumina nitrate water solution and its decomposition into a tubular flow reactor at 700 °C. The obtained particles are spherical, smooth, amorphous and in non-agglomerated state. Microstructural and morphological analyses were carried out using X-ray diffraction (XRD), scanning electron microscopy (SEM/EDS) and analytical and high resolution transmission electron microscopy (TEM/HRTEM).     

An investigation of shelf-life of strontium doped LaMnO3 materials

The shelf-life of Sr doped LaMnO₃ (LSM) materials of varying stoichiometric compositions prepared by wet chemical synthesis was investigated under storage conditions of low and high humidity at ambient temperature for 350 days. It has been found that the adhesion, chemical stability and stability of the electrode performance of LSM materials are critically dependent on the A-site stoichiometry (i.e., (La+Sr)/Mn ratio) of the LSM materials and much less dependent on storage conditions (humidity level and storage time) over the period investigated. In this respect, LSM materials with stoichiometric and sub-stoichiometric compositions where (La+Sr)/Mn1 are stable and LSM with A-site sub-stoichiometry ((La+Sr)/Mn0.9) is effective in achieving good adherence, high chemical stability and high stability of electrode performance.     

Lipids present in olive skin

Olive oil is a major constituent of many food preparations and is used in margarine and as a cooking oil. Olive oil consists of lipidic components, mainly fatty acids, in differing proportions depending on the source of the olive and the method of preparation. Although several studies have been made on the lipid composition of the extracted oil, no detailed analysis has been made on olive skin as a discrete entity. Analysis by gas chromatography (GC) of an olive skin extract showed oleic acid (61.45%), palmitic acid (15.28%) and linoleic acid (11.69%) to predominate. Smaller amounts of other fatty acids, not previously detected in olive fruit, were also found to be present in olive skin.     

Nondominated sorting genetic algorithm for optimal phasor measurement placement

This paper considers a phasor measurement unit (PMU) placement problem requiring simultaneous optimization of two conflicting objectives, such as minimization of the number of PMUs and maximization of the measurement redundancy. The objectives are in conflict since the improvement of one of them leads to the deterioration of another. Instead of a unique optimal solution, it exists a set of best tradeoffs between competing objectives, the so-called Pareto-optimal solutions. A specially tailored nondominated sorting genetic algorithm (NSGA) for a PMU placement problem is proposed as a methodology to find these Pareto-optimal solutions. The algorithm is combined with the graph-theoretical procedure and a simple GA to reduce the initial number of the PMU's candidate locations. The NSGA parameters are carefully set by performing a number of trial runs and evaluating the NSGA performances based on the number of distinct Pareto-optimal solutions found in the particular run and distance of the obtained Pareto front from the optimal one. Illustrative results on the 39- and 118-bus IEEE systems are presented.     

Intervertebral Disc Regeneration Injection of a Cell-Loaded Collagen Hydrogel in a Sheep Model

Degenerated intervertebral discs (IVDs) were treated with autologous adipose-derived stem cells (ASC) loaded into an injectable collagen scaffold in a sheep model to investigate the implant’s therapeutic potential regarding the progression of degeneration of previously damaged discs. In this study, 18 merino sheep were subjected to a 3-step minimally invasive injury and treatment model, which consisted of surgically induced disc degeneration, treatment of IVDs with an ASC-loaded collagen hydrogel 6 weeks post-operatively, and assessment of the implant’s influence on degenerative tissue changes after 6 and 12 months of grazing. Autologous ASCs were extracted from subcutaneous adipose tissue and cultivated in vitro. At the end of the experiment, disc heights were determined by µ-CT measurements and morphological tissue changes were histologically examined.Histological investigations show that, after treatment with the ASC-loaded collagen hydrogel implant, degeneration-specific features were observed less frequently. Quantitative studies of the degree of degeneration did not demonstrate a significant influence on potential tissue regeneration with treatment. Regarding disc height analysis, at both 6 and 12 months after treatment with the ASC-loaded collagen hydrogel implant a stabilization of the disc height can be seen. A complete restoration of the intervertebral disc heights however could not be achieved.The reported injection procedure describes in a preclinical model a translational therapeutic approach for degenerative disc diseases based on adipose-derived stem cells in a collagen hydrogel scaffold. Further investigations are planned with the use of a different injectable scaffold material using the same test model.