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91.
Miriam Zia Sadaf Mustafiz Hans Vangheluwe Jörg Kienzle 《Software and Systems Modeling》2007,6(4):437-451
Complex real-time system design needs to address dependability requirements, such as safety, reliability, and security. We
introduce a modelling and simulation based approach which allows for the analysis and prediction of dependability constraints.
Dependability can be improved by making use of fault tolerance techniques. The de-facto example, in the real-time system literature,
of a pump control system in a mining environment is used to demonstrate our model-based approach. In particular, the system
is modelled using the Discrete EVent system Specification (DEVS) formalism, and then extended to incorporate fault tolerance
mechanisms. The modularity of the DEVS formalism facilitates this extension. The simulation demonstrates that the employed
fault tolerance techniques are effective. That is, the system performs satisfactorily despite the presence of faults. This
approach also makes it possible to make an informed choice between different fault tolerance techniques. Performance metrics
are used to measure the reliability and safety of the system, and to evaluate the dependability achieved by the design. In
our model-based development process, modelling, simulation and eventual deployment of the system are seamlessly integrated. 相似文献
92.
Sadaf Jamal Gilani Syed Sarim Imam Adil Ahmed Sanjay Chauhan Mohd. Aamir Mirza 《Drug development and industrial pharmacy》2013,39(11):1799-1806
AbstractA rapid, accurate, and sensitive reverse phase high-performance liquid chromatographic (RP-HPLC) method was developed and validated for the estimation of Thymoquinone (TMQ) in API as well as in noisome. The chromatograms were developed with the mobile phase – water: 2-propanol: methanol (50:45:5 v/v/v) as a solvent system at 254?nm. The method was validated as per ICH guidelines for different parameters and the recovery of TMQ was calculated in developed niosomes. Further, TMQ loaded niosomes (TMQNIOS) were prepared and evaluated for different parameters. The optimized TMQNIOS (F3) was further evaluated for surface morphology, in vitro drug release, permeation study, and confocal laser scanning microscopic (CLSM) study. The method showed linearity range between 6.25 and 100?µg/ml with low detection limit and quantitation limit with a value of 2.08 and 6.25?µg/ml. The developed formulations showed the vesicle size and encapsulation efficiency in the range of 157.32?±?3.15 to 211.44?±?5.23?nm and 59.32?±?4.87 to 83.21?±?3.55%, respectively. The drug release result showed the significant higher release from TMQNIOS in compared to TMQDIS, and the release kinetics data showed Higuchi's equation with highest regression coefficient values. The permeation study and the confocal laser microscopy study further confirmed the enhancement in permeation of TMQ in the intestinal mucosa. 相似文献
93.
The combination of a threshold switching device and a resistive switching (RS) device was proposed to suppress the undesired sneak current for the integration of bipolar RS cells in a cross-point array type memory. A simulation for this hybrid-type device shows that the matching of key parameters between switch element and memory element is an important issue. Based on the threshold switching oxides, a conceptual structure with a simple metal-oxide?1-oxide?2-metal stack was provided to accommodate the evolution trend. We show that electroformed W-NbO(x)-Pt devices can simultaneously exhibit both threshold switching and memory switching. A qualitative model was suggested to elucidate the unique properties in a W-NbO(x)-Pt stack, where threshold switching is associated with a localized metal-insulator transition in the NbO(x) bulk, and the bipolar RS derives from a redox at the tip of the localized filament at the WO(x)-NbO(x) interface. Such a simple metal-oxide-metal structure, with functionally separated bulk and interface effects, provides a fabrication advantage for future high-density cross-point memory devices. 相似文献
94.
Zahid Ullah Fatima Kainat Sadaf Manzoor Hamza Liaquat Arslan Waheed Sultan Akhtar Imran Rafiq S. Hassan M. Jafri Hu Li Aamir Razaq 《应用聚合物科学杂志》2023,140(1):e53275
For modern high-tech flexible energy storage devices, it becomes important to synthesize micro-/nanostructures as per the required shape and morphology with superior physical and electro-active characteristics. This work shares the fabrication and characterization of ZnSn(OH)6 (Zinc hydroxystannate [ZHS]) prepared by facile microwave-assisted technique and furthermore converted into flexible sheets by employing lignocelluloses (LC) known as natural fibers, collected from Carica papaya leaf petiole as a substrate to provide the flexible matrix. X-ray diffraction measurements confirm the successful crystalline structure of ZHS. Scanning electron microscopy and transmission electron microscopy showed the solid spherical structure of ZHS microspheres. Fourier transform infrared spectrometry and Raman spectroscopy confirmed the composite formation of ZHS and LC-based composite sheets (ZHS/LC sheets). Electrochemical measurements that is, cyclic voltammetry (CV), Galvanostatic charge/discharge, and electrochemical impedance (EIS) spectroscopy revealed the electroactive behavior of ZHS/LC paper sheets as working electrode for energy storage applications. CV measurements revealed the specific capacitance of 100 F/g and EIS measurements confirmed the decrease in the resistance of LC fiber after the growth of ZHS microspheres. Presented flexible ZHS based paper sheets will be highly feasible for the modern bendable/flexible/disposable energy storage applications. 相似文献
95.
Nika Sokolova Lili Zhang Sadaf Deravi Rick Oerlemans Prof. Dr. Matthew R. Groves Prof. Dr. Kristina Haslinger 《Chembiochem : a European journal of chemical biology》2023,24(9):e202300076
Oxygen-directed methylation is a ubiquitous tailoring reaction in natural product pathways catalysed by O-methyltransferases (OMTs). Promiscuous OMT biocatalysts are thus a valuable asset in the toolkit for sustainable synthesis and optimization of known bioactive scaffolds for drug development. Here, we characterized the enzymatic properties and substrate scope of two bacterial OMTs from Desulforomonas acetoxidans and Streptomyces avermitilis and determined their crystal structures. Both OMTs methylated a wide range of catechol-like substrates, including flavonoids, coumarins, hydroxybenzoic acids, and their respective aldehydes, an anthraquinone and an indole. One enzyme also accepted a steroid. The product range included pharmaceutically relevant compounds such as (iso)fraxidin, iso(scopoletin), chrysoeriol, alizarin 1-methyl ether, and 2-methoxyestradiol. Interestingly, certain non-catechol flavonoids and hydroxybenzoic acids were also methylated. This study expands the knowledge on substrate preference and structural diversity of bacterial catechol OMTs and paves the way for their use in (combinatorial) pathway engineering. 相似文献
96.
Hamza Muhammad Nie Zhihong Aziz Mubashir Ijaz Nauman Fang Chuanfeng Ghani Muhammad Usman Ijaz Zain Noshin Sadaf Salman Muhammad 《Clean Technologies and Environmental Policy》2023,25(5):1699-1719
Clean Technologies and Environmental Policy - This article presents a comprehensive study on the geotechnical behavior of problematic expansive subgrade stabilized by guar gum (GG) biopolymer. In... 相似文献