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Magnetic Resonance Materials in Physics, Biology and Medicine - Quantitative analysis in MRI is challenging due to variabilities in intensity distributions across patients, acquisitions and...  相似文献   
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The aim of this study was to discuss the influence of different filter surface chemistries on the properties of foam filters. For reliable results, it is essential to ensure comparable structural properties (cell size and strut thickness) for all different surface chemistries (Al2O3, MgAl2O4, 3Al2O3·2SiO2, SiO2, and TiO2) possess the same structural properties (cell size and strut thickness). Filters made of 100% of the investigated materials and alumina skeletons coated with the investigated materials were prepared. The coated alumina samples were sintered in one and two steps. The processing route with two sintering steps resulted in improved mechanical properties and comparable shrinkage and strut thickness. The 100% bulk foams possessed different pore sizes due to the differences of the material shrinkage. In this study, a comparison of the experimental investigated properties of the ceramic foam filters and the theoretically calculated values for foam materials derived from the bulk material properties is established.  相似文献   
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The paper defines the identification problem for Discrete Event Systems (DES) as the problem of inferring a Petri Net () model using the observation of the events and the available output vectors, that correspond to the markings of the measurable places. Two cases are studied considering different levels of the system knowledge. In the first case the place and transition sets are assumed known. Hence, an integer linear programming problem is defined in order to determine a modelling the DES. In the second case the transition and place sets are assumed unknown and only an upper bound of the number of places is given. Hence, the identification problem is solved by an identification algorithm that observes in real time the occurred events and the corresponding output vectors. The integer linear programming problem is defined at each observation so that the can be recursively identified. Some results and examples characterize the identified systems and show the flexibility and simplicity of the proposed technique. Moreover, an application to the synthesis of supervisory control of systems via monitor places is proposed.  相似文献   
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Siemens is a global enterprise that sells its products in more than 190 countries throughout the world. This internationalization of products means more than just translating the operating instructions and making changes to formats. True adaptation goes much deeper and takes into account different requirements in terms of functionality. This article starts by defining the term culture and then considers the requirements that have to be met in the context of intercultural usability engineering. Taking the establishment of usability laboratories in Beijing, China and Princeton, New Jersey as examples, the article then presents the challenges facing international cooperation and possible solutions, taking a detailed look at differences in the infrastructure, at key qualifications in international cooperation, and at the development of appropriate test methods.  相似文献   
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The paper deals with the consensus problem in a leaderless network of agents that have to reach a common velocity while forming a uniformly spaced string.Moreover,the final common velocity(reference velocity)is determined by the agents in a distributed and leaderless way.Then,the consensus protocol parameters are optimized for networks characterized by a communication topology described by a class of directed graphs having a directed spanning tree,in order to maximize the convergence rate and avoid oscillations.The advantages of the optimized consensus protocol are enlightened by some simulation results and comparison with a protocol proposed in the related literature.The presented protocol can be applied to coordinate agents such as mobile robots,automated guided vehicles(AGVs)and autonomous vehicles that have to move with the same velocity and a common inter-space gap.  相似文献   
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An experimental modified-atmosphere packaging system was used to compare the atmospheric compositions that developed within sealed packs made from a range of films of different permeability properties. The effects of these conditions were then related to the primary quality attributes, i.e. background skin colour and flesh firmness, and the sensory quality of Discovery apples. Concentrations of CO2 and O2 within packs were dependent on the permeability of the film and the holding temperature. In packs sealed with low density polyethylene films and held at 20°C, equilibrated atmospheres containing 3-5% CO2 and 5-6% O2 developed within 1-2 days. Softening and yellowing of fruit was markedly retarded. In packs sealed with some less permeable films, atmospheres containing 12-20% CO2 and 0.9-4% O2 developed within 1-2 days, resulting in retarded softening and yellowing of the fruit but also a high incidence of tainting. Possible commercial applications, benefits and limitations of modified-atmosphere packaging are discussed.  相似文献   
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