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Search Results: 1 - 10 of 3876 matches for " Tim Warnecke "
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A Study on Configuration and Integration of Sub-Systems to System-of-Systems with Rule Verification  [PDF]
Tim Warnecke
Engineering (ENG) , 2015, DOI: 10.4236/eng.2015.710056
Abstract: Increasing complexity of today’s software systems is one of the major challenges software engineers have to face. This is aggravated by the fact that formerly isolated systems have to be interconnected to more complex systems, called System-of-Systems (SoS). Those systems are in charge to provide more functionality to the user than all of their independent sub-systems could do. Reducing the complexity of such systems is one goal of the software engineering paradigm called component-based software engineering (CBSE). CBSE enables the developers to treat individual sub-systems as components which interact via interfaces with a simulated environment. Thus those components can be developed and implemented independently from other components. After the implementation a system integrator is able to interconnect the components to a SoS. Despite this much-used approach it is possible to show that constraints, which are valid in an isolated sub-system, are broken after this system is integrated into a SoS. To emphasize this issue we developed a technique based on interconnected timed automata for modelling sub-systems and System-of-Systems in the model checking tool UPPAAL. The presented modelling technique allows it to verify the correctness of single sub-systems as well as the resulting SoS. Additionally we developed a tool which abstracts the complicated timed automata to an easy to read component based language with the goal to help system integrators building and verifying complex SoS.
Building on basic metagenomics with complementary technologies
Falk Warnecke, Philip Hugenholtz
Genome Biology , 2007, DOI: 10.1186/gb-2007-8-12-231
Abstract: The majority of microorganisms defy axenic culture in the laboratory and so have eluded study by the classic microbiological approaches [1]. With the advent of cultivation-independent molecular tools, the true extent of microbial diversity has been, and continues to be, revealed [2-4]. Much of that work, however, is based on a single phylogenetic marker gene, small subunit ribosomal RNA (ssu rRNA) [5]. By contrast, metagenomics in principle makes accessible the entire genetic complement of a microbial community - we define metagenomics here as the large-scale application of random shotgun sequencing to DNA extracted directly from environmental samples and resulting in at least 50 megabase pairs (Mbp) of sequence data. It has been barely three years since the publication of the first large-scale metagenomic studies: of an acid mine drainage biofilm [6] and of ocean surface water [7]. Since then, numerous other habitats have been investigated using this 'basic' metagenomic approach (Figure 1, arrow 1), including farmland soil and whale falls (whale carcasses that have fallen to the sea floor) [8], symbionts in a gutless marine worm [9], phosphorus-removing activated sludge [10], the human [11] and termite [12] gut and marine microbial [13,14] and viral [15] samples. In all these cases, metagenomics provided insights into the microbial community under study that probably would have taken much longer to come to light using more directed (nonrandom) approaches. Shotgun sequencing of environmental samples has, however, a number of limitations [16], which can best be addressed by the use of complementary techniques.Three notable limitations of the basic metagenomic approach are low resolution, the inability to classify short metagenomic fragments, and the lack of functional verification. Perhaps surprisingly, the resolution of microbial communities by shotgun sequencing is rather low, with only dominant populations producing sufficient sequence coverage to result in a sequ
Fractal Company
Hans Jürgen Warnecke
Acta Mechanica Slovaca , 2009, DOI: 10.2478/v10147-010-0041-1
Abstract: More and more branches are confronted with fast changes of products, technologies and markets and it is hard to manage its position with the traditional methods of reorganization, re-engineering, computer integration or by new more flexible technology. The only chance is to create such adaptable organization which will react adequately to these changes by itself. Living organisms that are strongly adaptable to changed conditions because they are designed with self-organized elements; similarly to them the fractal organization uses suchlike principle. Individual organizational sections are autonomous, they organize and optimize themselves and so create the vital structure that is focused on processes and client.
Medical students’ perceptions of using e-learning to enhance the acquisition of consulting skills
Warnecke E,Pearson S
Australasian Medical Journal , 2011,
Abstract: BackgroundThis study aims to evaluate medical students’ perception ofthe usefulness and effectiveness of an e-learning packagedeveloped to enhance the acquisition of consulting skills.MethodA survey with mixed method data analysis was conducted.Participants were 67 medical students completing theirthird year primary care rotation as part of a five-year degreeat the University of Tasmania. Participants completed a 10question anonymous online survey after using the elearningpackageResultsOf the participants, 92% found it enjoyable and 95% foundthe e-learning package useful; 75% perceived it to beeffective in increasing their performance and 91% believedit increased their knowledge in consulting skills. Benefits forparticipants’ confidence, style and structure of consultingskills were found.ConclusionParticipants found the e-learning package to be enjoyableand effective. E-learning should be further utilised in ablended learning environment to support face-to-faceteaching in consulting skills.
Surface appearance of dynamo-generated large-scale fields
J. Warnecke,A. Brandenburg
Physics , 2010, DOI: 10.1051/0004-6361/201014287
Abstract: Twisted magnetic fields are frequently seen to emerge above the visible surface of the Sun. This emergence is usually associated with the rise of buoyant magnetic flux structures. Here we ask how magnetic fields from a turbulent large-scale dynamo appear above the surface if there is no magnetic buoyancy. The computational domain is split into two parts. In the lower part, which we refer to as the turbulence zone, the flow is driven by an assumed helical forcing function leading to dynamo action. Above this region, which we refer to as the exterior, a nearly force-free magnetic field is computed at each time step using the stress-and-relax method. Twisted arcade-like field structures are found to emerge in the exterior above the turbulence zone. Strong current sheets tend to form above the neutral line, where the vertical field component vanishes. Time series of the magnetic field structure show recurrent plasmoid ejections. The degree to which the exterior field is force free is estimated as the ratio of the dot product of current density and magnetic field strength to their respective rms values. This ratio reaches values of up to 95% in the exterior. A weak outward flow is driven by the residual Lorentz force.
Organic acid toxicity, tolerance, and production in Escherichia coli biorefining applications
Tanya Warnecke, Ryan T Gill
Microbial Cell Factories , 2005, DOI: 10.1186/1475-2859-4-25
Abstract: Biorefining promises the development of efficient processes for the conversion of renewable sources of carbon and energy into large volume commodity chemicals. It has been estimated that such bioprocesses already account for 5% of the 1.2 trillion dollar US chemical market [1], with some projecting future values of up to 50% of the total US chemical market generated through biological means. While the attractiveness of such bioprocesses has been recognized for some time [2,3], recent advances in biological engineering and associated sciences [4-15], several biorefining success stories [16-18], and instability in the price and future availability of oil [19], have collectively reinvigorated interest in the large scale production of chemicals through biological routes. Nevertheless, many challenges still remain for the economical bio-production of commodity chemicals. Such challenges encompass the need to not only inexpensively convert biomass into usable sources of carbon and energy but also to engineer microbes to produce relevant chemicals at high titers and productivities while minimizing the generation of byproducts that might foul downstream processes [1,20,21]. One model for addressing the latter of such challenges involves the generation of platform organisms that can be easily engineered and re-engineered to produce a variety of building block chemicals that are amenable to conversions to higher value products via traditional catalytic routes (see Figure 1). Although chemical pretreatment of raw materials impairs viability of platform organisms, this review will focus on product toxicity issues associated with the production of organic acids in E. coli (for further information on sugar extraction from raw materials see Zaldavar, et al. [22] and Knauf, et al. [23]).The US Department of Energy (USDOE) recently released a prioritized list of building block chemicals for future biorefining endeavors. Priority was assigned based on the projected value of the platf
Recurrent flux emergence from dynamo-generated fields
J?rn Warnecke,Axel Brandenburg
Physics , 2010, DOI: 10.1017/S1743921311018023
Abstract: We investigate the emergence of a large-scale magnetic field. This field is dynamo-generated by turbulence driven with a helical forcing function. Twisted arcade-like field structures are found to emerge in the exterior above the turbulence zone. Time series of the magnetic field structure show recurrent plasmoid ejections.
Coronal influence on dynamos
J?rn Warnecke,Axel Brandenburg
Physics , 2013, DOI: 10.1017/S1743921314001884
Abstract: We report on turbulent dynamo simulations in a spherical wedge with an outer coronal layer. We apply a two-layer model where the lower layer represents the convection zone and the upper layer the solar corona. This setup is used to study the coronal influence on the dynamo action beneath the surface. Increasing the radial coronal extent gradually to three times the solar radius and changing the magnetic Reynolds number, we find that dynamo action benefits from the additional coronal extent in terms of higher magnetic energy in the saturated stage. The flux of magnetic helicity can play an important role in this context.
Dynamo generated field emergence through recurrent plasmoid ejections
J?rn Warnecke,Axel Brandenburg
Physics , 2010, DOI: 10.1051/0004-6361/201117023
Abstract: Magnetic buoyancy is believed to drive the transport of magnetic flux tubes from the convection zone to the surface of the Sun. The magnetic fields form twisted loop-like structures in the solar atmosphere. In this paper we use helical forcing to produce a large-scale dynamo-generated magnetic field, which rises even without magnetic buoyancy. A two layer system is used as computational domain where the upper part represents the solar atmosphere. Here, the evolution of the magnetic field is solved with the stress--and--relax method. Below this region a magnetic field is produced by a helical forcing function in the momentum equation, which leads to dynamo action. We find twisted magnetic fields emerging frequently to the outer layer, forming arch-like structures. In addition, recurrent plasmoid ejections can be found by looking at space--time diagrams of the magnetic field. Recent simulations in spherical coordinates show similar results.
The singular kernel coagulation equation with multifragmentation
Carlos Cueto Camejo,Gerald Warnecke
Physics , 2012,
Abstract: In this article we prove the existence of solutions to the singular coagulation equation with multifragmentation. We use weighted $L^1$-spaces to deal with the singularities and to obtain regular solutions. The Smoluchowski kernel is covered by our proof. The weak $L^1$ compactness methods are applied to suitably chosen approximating equations as a base of our proof. A more restrictive uniqueness result is also given.
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