Adaptive fuzzy sliding mode power system stabilizer using Nussbaum gain

Power system stability is enhanced through a novel stabilizer developed around an adaptive fuzzy sliding mode approach which applies the Nussbaum gain to a nonlinear model of a single-machine infinite-bus （SMIB） and multi-machine power system stabilizer subjected to a three phase fault. The Nussbaum gain is used to avoid the positive sign constraint and the problem of controllability of the system. A comparative simulation study is presented to evaluate the achieved performance.     

Representativeness of Apple Aroma Extract Obtained by Vacuum Hydrodistillation: Comparison of Two Concentration Techniques

ABSTRACT: Vacuum hydrodistillation, which is a very gentle work-up procedure, has never been used for the extraction of apple aroma. During the concentration of aroma that follows vacuum hydrodistillation, some very volatile components can be lost. The aim of this study was to compare 2 different concentration techniques, liquid-liquid extraction and solid phase extraction, to obtain an apple aroma extract as close as possible to fresh apple. After the elimination of solvent from the extract by gas chromatography, the study of the odor characteristics of solvent-free extracts was made possible. Vacuum hydrodistillation was convenient for fresh apples.     

A process-tolerant out-of-band blocker rejection technique for SAW-less receivers

In this paper, an active filtering technique is presented which is capable of filtering the out-of-band blockers in wireless receivers. The concept is based on the feedforward cancellation technique where a blocker replica is subtracted at the output of the low-noise amplifier (LNA). In contrast to the previously reported feedforward cancellation methods, exact gain and phase matching are easily obtained in the proposed architecture to produce a highly selective narrowband frequency response at the output of the LNA with wide rejection bandwidth. For the proof of concept, the system is implemented in a 65 nm CMOS technology. It occupies a total area of 0.8 mm² and the current consumption is 24 mA from a 1.2 V supply. The system post-layout simulations showed a blocker rejection of more than 33 dB for blocker signals 100 MHz away from the desired signal when the feedforward path is activated. The noise figure (NF) of the entire system is 3.8 dB that degrades to 5.8 dB when the feedforward path is activated.     

Phenolic composition and antioxidant capacities of ten Algerian date (Phoenix dactylifera L.) cultivars: A comparative study

Phenolic compounds and antioxidant capacities of ten Algerian date (Phoenix dactylifera L.) cultivars were investigated. The total phenolic, flavonoid, flavonol and condensed tannin contents of the different cultivars were measured using colorimetric methods. Free phenolic acid and flavonoid profiles of the date cultivars were analyzed by high performance liquid chromatography with diode array detection (HPLC-DAD), while antioxidant capacities were evaluated in vitro using scavenging assays of 1,1-diphenyl-2-picrylhydrazyl radical and hydrogen peroxide, ferric reducing power, and ferrous ion chelating ability. The results showed that the cultivars exerted different antioxidant capacities, and had different phenolic acid and flavonoid patterns. Among the tested cultivars, Ghazi, Arechti and Sebt Mira possessed the strongest antioxidant capacities and the highest phenolic contents. Four phenolic acids (gallic, ferulic, coumaric and caffeic acids) and five flavonoids (isoquercetrin, quercetrin, rutin, quercetin and luteolin) were identified and quantified.     

Influence of Nano,Micro, and Macro Topography of Dental Implant Surfaces on Human Gingival Fibroblasts

Current research on dental implants has mainly focused on the influence of surface roughness on the rate of osseointegration, while studies on the development of surfaces to also improve the interaction of peri-implant soft tissues are lacking. To this end, the first purpose of this study was to evaluate the response of human gingival fibroblasts (hGDFs) to titanium implant discs (Implacil De Bortoli, Brazil) having different micro and nano-topography: machined (Ti-M) versus sandblasted/double-etched (Ti-S). The secondary aim was to investigate the effect of the macrogeometry of the discs on cells: linear-like (Ti-L) versus wave-like (Ti-W) surfaces. The atomic force microscopy (AFM) and scanning electron microscopy (SEM) analysis showed that the Ti-S surfaces were characterized by a significantly higher micro and nano roughness and showed the 3D macrotopography of Ti-L and Ti-W surfaces. For in vitro analyses, the hGDFs were seeded into titanium discs and analyzed at 1, 3, and 5 days for adhesion and morphology (SEM) viability and proliferation (Cck-8 and MTT assays). The results showed that all tested surfaces were not cytotoxic for the hGDFs, rather the nano-micro and macro topography favored their proliferation in a time-dependent manner. Especially, at 3 and 5 days, the number of cells on Ti-L was higher than on other surfaces, including Ti-W surfaces. In conclusion, although further studies are needed, our in vitro data proved that the use of implant discs with Ti-S surfaces promotes the adhesion and proliferation of gingival fibroblasts, suggesting their use for in vivo applications.     

Textural properties of fruit affected by experimental conditions in TPA tests: an RSM approach

Texture profile analysis (TPA) is widely used to assess the textural properties of fruit. However, test parameters may potentially affect TPA results. This work studies the influence of the degree of deformation and crosshead speed on the mechanical parameters of apple measured by TPA. In this study, the degree of deformation ranged from 5% to 17.8% and the crosshead speed from 10 to 90 mm min^?1. Eight parameters were extracted from the analysis of force–displacement and force–time curves. For each parameter, the mean value and the coefficient of variation (CV) were examined. A central composite design that simultaneously takes into account both input variables, the degree of deformation and crosshead speed, was implemented. It appears that the linear and the quadratic effects of the degree of deformation make it the major variable. However, neglecting the effects (linear and quadratic) of the crosshead speed might be disastrous since they significantly affect parameters such as cohesiveness, gumminess and work 2. Moreover, the CV of hardness 1 depends mainly on the interaction between the degree of deformation and crosshead speed.     

A 100-MHz 8-mW ROM-less quadrature direct digital frequency synthesizer

A low-power quadrature direct digital frequency synthesizer (DDFS) is presented. Piecewise linear approximation is used to avoid using a ROM look-up table to store the sine values as in a conventional DDFS. Significant saving in power consumption, due to the elimination of the ROM, renders the design more suitable for portable wireless communication applications. To demonstrate the proposed technique, a quadrature DDFS has been implemented using 0.5-/spl mu/m CMOS process and occupies an active area of 1.4 mm/sup 2/. It consumes 8 mW at 100 MHz and operates from a single 2.7-V supply. The spurious-free dynamic range is better than 59 dBc at low synthesized frequencies and the frequency resolution is 1.5 kHz.     

Instrumental and sensory characterisation of industrially processed applesauces

BACKGROUND: In the context of fruit consumption promotion, applesauce is an interesting ready‐to‐eat product. However, little information has been gathered on its sensory properties. Yet, the processing involved easily triggers rheological and structural changes, possibly modifying these sensory properties. The aim of this study was thus to provide a global approach for applesauce characterisation by studying instrumental and sensory properties, with knowledge of the processing conditions applied. Four applesauce samples processed under controlled parameters were therefore compared with seven purchased applesauces. RESULTS: The four studied samples were characterised by their high creaminess and low graininess. These products were homogeneous and presented a small average particle size (332–354 µm). Their flow properties were best described with the Hershel–Bulkey model. The products were shear‐thinning with low yield stress. Interestingly, significant differences in textural and flow properties were also found among these four manufactured samples. CONCLUSION: Sensory characterisation revealed aromatic and textural diversity even though applesauce is considered as a common product. Differences found among the samples of interest might be related to postharvest maturity of fruits and consequent pectic degradation from cell walls. Finally, the candied odour and flavour that distinguished these products could be related to the extensive heating applied during processing. Copyright © 2009 Society of Chemical Industry     

Stability of Individual Phenolic Compounds and Antioxidant Activity During Storage of a Red Wine Powder

The addition of maltodextrin DE 10 to red wine (Cabernet Sauvignon) followed by freeze-drying allowed to obtain a free-flowing (dealcoholized) wine powder (WP) having a phenolic concentration about 3.6 times higher than the original liquid red wine. The powder, having a water activity (a _w) of 0.053 and 0.330 was stored at 28 °C and 38 °C and the content of ten different phenolic compounds was determined by HPLC. Caftaric acid, quercetin 3-glucoside, caffeic acid, gallic acid and resveratrol contents in the WP stored at 28 °C and 38 °C, remained almost constant during 70 days of storage, while epicatechin gallate, catechin, malvidin 3-G and epicatechin showed slight losses (about 15–25 %) during storage. On the contrary, epigallocatechin experienced a strong loss of concentration (around 61 % loss) during storage at the same conditions. A moderate decrease of antioxidant activity, determined by free radical scavenging capacity of the 2,2-diphenyl-1-picrylhydrazyl free radical (DPPH*) and ferric reducing antioxidant power (FRAP) was observed along storage. This decrease was more important at higher temperature (38 °C) and higher a _w (0.33). These results would allow the feasibility of using this WP as a healthy ingredient in alcohol-free powder drinks.