901 research outputs found
On the existence and exponential attractivity of a unique positive almost periodic solution to an impulsive hematopoiesis model with delays
In this paper, a generalized model of hematopoiesis with delays and impulses
is considered. By employing the contraction mapping principle and a novel type
of impulsive delay inequality, we prove the existence of a unique positive
almost periodic solution of the model. It is also proved that, under the
proposed conditions in this paper, the unique positive almost periodic solution
is globally exponentially attractive. A numerical example is given to
illustrate the effectiveness of the obtained results.Comment: Accepted for publication in AM
Extended state observer based load frequency controller for three area interconnected power system
In this paper, we develop a new extended state variable observer based LFC scheme for three-area interconnected power systems. The extended state observerbased load frequency controllers are developed which utilize disturbance estimation techniques. The propose control approach assures that the fluctuating things of the load frequencies reaches to a safer range and the load frequencies can also be made at a very minimal not to have an effect on power quality and power flow in multi-area interconnected power system. The results of the simulations using MATLAB/SIMULINK done did not only address that the proposed newly control method works effectively but also change powerfully the parameter variations of the interconnected areas of the power system. Especially, it works very well to limit disturbances impact on interconnected areas in the system. Therefore, the performance of interconnected power system under different multi-conditions is simulated with the new control method to demonstrate the feasibility of the system
Electromgnetic-gravitational cross-sections in external elctromagnetic fields
The classical processes: the conversion of photons into gravitons in the
static electromagnetic fields are considered by using Feynman perturbation
techniques. The differential cross sections are presented for the conversion in
the electric field of the flat condesor and the magnetic field of the selenoid.
A numerical evaluation shows that the cross sections may have the observable
value in the present technical scenario.Comment: 11 pages, LATEX, no figure
FMI Compliant Approach to Investigate the Impact of Communication to Islanded Microgrid Secondary Control
In multi-master islanded microgrids, the inverter controllers need to share
the signals and to coordinate, in either centralized or distributed way, in
order to operate properly and to assure a good functionality of the grid. The
central controller is used in centralized strategy. In distributed control,
Multi-agent system (MAS) is considered to be a suitable solution for
coordination of such system. However the latency and disturbance of the network
may disturb the communication from central controller to local controllers or
among agents or and negatively influence the grid operation. As a consequence,
communication aspects need to be properly addressed during the control design
and assessment. In this paper, we propose a holistic approach with
co-simulation using Functional Mockup Interface (FMI) standard to validate the
microgrid control system taking into account the communication network. A
use-case of islanded microgrid frequency secondary control with MAS under
consensus algorithm is implemented to demonstrate the impact of communication
and to illustrate the proposed holistic approach.Comment: Proceedings of the IEEE PES ISGT Asia 2017 conferenc
Heterologous phytase expression in the food filamentous fungus Aspergillus oryzae using the added rice husk cultivation model
Aspergillus oryzae, a safe filamentous fungus, is widely used in food and enzyme production. In this study, we examined a cultivation model using rice husks as carrier to assess the capacity of recombinant protein production in A. oryzae. The model was first tested with the A. oryzae strain expressing the DsRed reporter gene. Expression of DsRed was easily detected by the pink color of the fungal mycelium on culture media and under a fluorescence microscope. The model was then evaluated with the phyA gene encoding a phytase from the fungus Aspergillus fumigatus. The phyA expression cassette regulated by the amyB promoter was permanently integrated into the genome of A. oryzae via Agrobacterium tumefaciens-mediated transformation with the pyrG nutritional marker. Results showed that A. oryzae transgenic strains carrying 2−3 copies of the phyA gene in their genomes exhibited a significant increase in phytase activity on agar medium supplemented with phytate. With rice husks added, these transgenic strains could secrete the recombinant phytase into the culture and phytase activity of the crude enzyme solution increased by 4.3 times compared to the unstransgenic A. oryzae. The established cultivation model and the transgenic approach in this study represent a potential for being used in production of secreted recombinant enzymes for animal feeds.
Formalising Solutions to REST API Practices as Design (Anti)patterns
REST APIs are nowadays the de-facto standard for Web applications. However, as more systems and services adopt the REST architectural style, many problems arise regularly. To avoid these repetitive problems, developers should follow good practices and avoid bad ones. Thus, research on best and bad practices and how to design simple but effective REST APIs is important. Yet, to the best of our knowledge, only a few recurring REST API practices have been codified in the form of design (anti)patterns, which include a name, an intent, a context, and some solutions. There are works on defining or detecting some practices, but not on codifying these practices as patterns. In this thesis, we present the most up-to-date list of REST API practices and formalise them in the form of design (anti)patterns to ease their use by developers. During this formalisation, we also devise and formalise solutions to these practices. Finally, we validate our design (anti)patterns with a survey and interviews of 55 developers, which confirm that our solutions are acceptable by practitioners and reflect real problems and solutions
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