Search

In this paper, a particle swarm optimization (PSO) method is proposed to design Quantitative Feedback Theory (QFT) control. This method minimizes a proposed cost function subject to appropriate robust stability and performance QFT constraints. The PSO algorithm is simple and easy to implement, and can be used to automate the loop shaping procedures of the standard QFT. The proposed method is applied to the high uncertainty pneumatic servo actuator system as an example to illustrate the design procedure of the proposed algorithm. The proposed method is compared with the standard QFT control. The results show that the superiority of the proposed method in that it can achieve the same robustness requirements of standard QFT control with simple structure and low order controller. [ABSTRACT FROM AUTHOR]

Quantitative Feedback Theory (QFT) technique is a robust control design based on frequency domain methodology. It is useful for practical design of feedback system in ensuring plant's stability by reducing the sensitivity to parameter variation and attenuate the effect of disturbances. Parameter variation or physical changes to the plant is taken into account in the QFT controller's design. This paper will discuss on QFT control design methodology and will work on a case study; laboratory scale plant of a bench-top helicopter. The bench-top helicopter is very difficult to control due to its non-linear behavior and subject to parameter variation. By using QFT controller, a full operational envelop design is achieved according to pre-defined specifications. The proposed method is compared with the conventional PI controller. The obtained simulation results show QFT controller is more efficient and robust than the PI controller. [ABSTRACT FROM AUTHOR]

Abstract: Nanostructured lipid carriers (NLCs), made from mixtures of solid and liquid lipids, were postulated to have superior properties over solid lipid nanoparticles (SLNs). Nonetheless, the architecture of their inner cores remains elusive. The objective of this study was to elucidate the mode by which tocotrienol-rich fraction (TRF) is entrapped within NLCs and the impact of TRF interaction with solid lipids on the long-term stability of the nanoparticles. The mode of TRF localization was postulated from TEM image analysis and 1H NMR signals’ amplitude. The size, polydispersity, and fusion enthalpy were found to decrease with an increase in TRF loading, which implied a distortion in the crystallinity of the nanoparticles and the preferential entrapment of TRF within the cores of the NLCs. Nonetheless, 1H NMR spectra of TRF-NLCs broadened as TRF load decreased from 100 to 10%, which was attributed to partial TRF mobility on the surface of the nanoparticles. This was confirmed by TEM images of NLCs at 50% TRF loads. These data led to the conclusion that NLCs have limited capacity to accommodate TRF with the excess being expelled to the surface of the nanoparticles. Such arrangement may have implication on future utility of the NLCs as drug delivery vehicles. [Copyright &y& Elsevier]

The effect of certain agriculture practices such as susceptibility of six broad bean varieties, space of planting, nitrogen fertilization levels, first irrigation and farmyard manure on the infestation of broad bean crop with the Aphis craccivora Koch was studied at El-Kawsar region, Sohag Governorate (about 495 km south of Cairo, Egypt) throughout the 2003/2004 and 2004/2005 seasons. The results obtained revealed that A. craccivora appeared from November until the second week of April. Also, the faba bean varieties were different in their susceptibility to the infestation with A. craccivora, dividing into three groups: the first one which was susceptible included Giza 674 and Giza Blanka; the second had low resistance and included Giza 843, Giza 2 and Giza 40; and the third group was moderate including Giza 429. The numbers of A. craccivora was significantly increased at 70 kg chemical nitrogen plus farmyard manure than at 40 or 55 units/feddan of chemical nitrogen during the two seasons. The population density of A. craccivora was significantly higher when decreasing the planting space. The population density of A. craccivora increased significantly with an increase of nitrogen fertilization levels during both seasons. The broad bean plants sown on 10 cm and which received N at a rate of 90 kg/fed. harboured the highest numbers of A. craccivora as compared with the other treatment (20 and 30 cm). The results show also that the broad bean plants which were irrigated at 56 and 63 days as a first irrigation harboured highly significant numbers of A. craccivora compared with the plants irrigated at 14, 21 and 28 days. These results also show significant negative correlation between the infestation of A. craccivora and the yield of broad bean plants. [ABSTRACT FROM AUTHOR]

Thermoelectric power generators are promising for clean energy production through converting the waste heat to electricity in environmentally friendly ways without any noise or pollutants. This work reports a facile method to synthesize Bi2Te3 nanoflakes with an investigation of their structural, optical, and thermoelectric properties. Various techniques such as X‐ray diffraction, field emission scanning electron microscope, transmission electron microscope, and energy dispersive spectroscopy are used to characterize the synthesized compound. The results confirmed that the nanoflakes crystallize in a rhombohedral structure with an average diameter and thickness ≈31.2 and 27 nm, respectively. A narrow optical band gap of 0.43 eV is determined for the prepared nanoflakes confirming the potential of employing the nanoflakes in optoelectronic applications. The results of the thermoelectric measurements imply that the synthesized nanoflakes have high power factor values at high temperatures compared to those previously reported for the same compound by other research groups. The power factor values make the synthesized nanoflakes promising candidate for thermoelectric applications. Bi2Te3 nanoflakes (average diameter 31.2 nm and thickness 27 nm) are synthesized via a bottom up facile hydrothermal method. An enhanced power factor (PF) ≈13.2 μW cm−1 K−2 at 500 K is achieved. The enhanced PF value candidates the Bi2Te3 nanoflkes for promising thermopower applications. [ABSTRACT FROM AUTHOR]

Objective: To assess serum interleukin-6 (IL-6)level in patients with systemic sclerosis (SSc) and its correlations with European Scleroderma Study Group activity score (EUSTAR), Scleroderma Assessment Questionnaire (SAQ), disability index and cardiopulmonary involvement., Methods: Twenty SSc patients and 10 matched healthy controls were included. Serum IL-6 was measured in patients and controls. Disease activity, status,and disability were assessed.Cardiopulmonary involvement was evaluated by pulmonary function tests (PFTs), six minute walk test, echocardiography, and high resolution computed tomography (HRCT) of chest., Results: Serum level of IL-6 was significantly higher in patients with SSc (6.3± 1.4pg/ml) versus healthy controls (3.2± 0.4pg/ml) (P=0.002). IL-6 level showed positive correlations with disease duration (r=0.49, P=0.03), EUSTAR score (r=0.64, P=0.002), Index of Respiratory Status "IRS" (r=0.46, P=0.001), Index of Musculoskeletal Status "IMSS" (r=0.45, P=0.049), Index of Vascular Status "IVS" (r=0.39, P=0.04), mean and peak of pulmonary artery pressure (r=0.44 & 0.55, P=0.02 & 0.002 respectively). Negative correlations of IL-6 level with DLCO% (r=-0.49, P=0.006),six minute walk distance (6MWD) (r=-0.52, P= 0.003) and right ventricle fraction area change (r=-0.48, P=0.03) were found, while there were strong positive correlations with HRCT-ground glass score (r=0.77, P=0.0001) and HRCT-fibrosis score (r=0.62, P=0.003)., Conclusion: IL-6 level is increased in patients with SSc and significantly correlates with EUSTAR score, IRS, DLCO, 6MWD, HRCT scores, and echocardiographic abnormalities of the right side of the heart. These results support the role of IL-6 in the disease activity and in the development of cardiopulmonary manifestations in SSc patients.

In vitro characterization of alpha-tocopherol SEDDS formulations was performed by (1) lipolysis in bio-relevant media, and (2) physical assessment by dissolution, particle size, and turbidity analyses. Both methods were statistically correlated using a 25-run, five-factor multiple-level d-optimal mixture design. Independent variables were SEDDS composition [vitamin E (12.5-25%), Tween 80 (10-40%), labrasol (0-10%), alcohol (0-10%), and captex 355 (20-50%)]. Measured responses were percent lipolysis, percent vitamin E retained in the aqueous layer of the digestion medium, and percent vitamin E dissolved in the dissolution medium. Percent lipolysis ranged from 0% to 66.3%. Percent vitamin E retrieved in the aqueous layer of the digestion and dissolution media ranged from 3% to 29.3% and from 25.9% to 101.7%, respectively. Turbidity ranged from 28 to 403JTU and the average droplet size was >1.0 microm. All formulation ingredients had significant (p<0.05) effect on percent lipolysis. Only two factors, Tween and vitamin E had significant effect on vitamin retention in the aqueous layer post-lipolysis. Tween, labrasol, and captex 355 had significant effect on vitamin E dissolution. Poor correlation was observed between the responses. Formulation ingredients influenced each response differently; and therefore, each method can only reveal distinctive characteristics of the SEDDS formulation and may not be used interchangeably.