999 resultados para COOPERATIVE NUCLEATION


Relevância:

20.00% 20.00%

Publicador:

Resumo:

Wound research is a complex multidimensional activity most effectively conducted by inter-disciplinary teams that connect studies in basic wound biology, devices and biomaterials with clinical practice. These complexities have been recognised in a new initiative through the establishment of an inter-disciplinary wound research centre in Australia; the Wound Management Innovation Cooperative Research Centre (WMI CRC). The centre is funded by the Australian Government's Cooperative Research Centre Program and a consortium of 22 participants and has a resource of US$108 million over 8 years...

Relevância:

20.00% 20.00%

Publicador:

Resumo:

A simple experimental apparatus is described in which a wide variety of vapor phase nucleation studies of refractory materials could be performed aboard NASA's KC-135 Research Aircraft. The chief advantage of a microgravity environment for these studies is the expected absence of thermally driven convective motions in the gas. The absence of convection leads to much more accurate knowledge of both the temperature distribution in the system and the time evolution of the refractory vapor concentration as a function of distance from the crucible.The evolution of the apparatus will be described as more experience is gained with the microgravity environment. Such experiments will be used to prepare for similar ones carried out aboard either the shuttle or Space Station where considerably longer duration experiments are possible.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

We consider Cooperative Intrusion Detection System (CIDS) which is a distributed AIS-based (Artificial Immune System) IDS where nodes collaborate over a peer-to-peer overlay network. The AIS uses the negative selection algorithm for the selection of detectors (e.g., vectors of features such as CPU utilization, memory usage and network activity). For better detection performance, selection of all possible detectors for a node is desirable but it may not be feasible due to storage and computational overheads. Limiting the number of detectors on the other hand comes with the danger of missing attacks. We present a scheme for the controlled and decentralized division of detector sets where each IDS is assigned to a region of the feature space. We investigate the trade-off between scalability and robustness of detector sets. We address the problem of self-organization in CIDS so that each node generates a distinct set of the detectors to maximize the coverage of the feature space while pairs of nodes exchange their detector sets to provide a controlled level of redundancy. Our contribution is twofold. First, we use Symmetric Balanced Incomplete Block Design, Generalized Quadrangles and Ramanujan Expander Graph based deterministic techniques from combinatorial design theory and graph theory to decide how many and which detectors are exchanged between which pair of IDS nodes. Second, we use a classical epidemic model (SIR model) to show how properties from deterministic techniques can help us to reduce the attack spread rate.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Simulation has been widely used to estimate the benefits of Cooperative Systems (CS) based on Inter-Vehicular Communications (IVC). This paper presents a new architecture built with the SiVIC simulator and the RTMaps™ multisensors prototyping platform. We introduce several improvements from a previous similar architecture, regarding IVC modelisation and vehicles’ control. It has been tuned with on-road measurements to improve fidelity. We discuss the results of a freeway emergency braking scenario (EEBL) implemented to validate our architecture’s capabilities.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Cooperative Systems provide, through the multiplication of information sources over the road, a lot of potential to improve the safety of road users, especially drivers. However, developing cooperative ITS applications requires additional resources compared to non-cooperative applications which are both time consuming and expensive. In this paper, we present a simulation architecture aimed at prototyping cooperative ITS applications in an accurate and detailed, close-to-reality environment; the architecture is designed to be modular and generalist. It can be used to simulate any type of CS applications as well as augmented perception. Then, we discuss the results of two applications deployed with our architecture, using a common freeway emergency braking scenario. The first application is Emergency Electronic Brake Light (EEBL); we discuss improvements in safety in terms of the number of crashes and the severity of crashes. The second application compares the performance of a cooperative risk assessment using an augmented map against a non-cooperative approach based on local-perception only. Our results show a systematic improvement of forward warning time for most vehicles in the string when using the augmented-map-based risk assessment.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Cooperative Systems provide, through the multiplication of information sources over the road, a lot of potential to improve the assessment of the road risk describing a particular driving situation. In this paper, we compare the performance of a cooperative risk assessment approach against a non-cooperative approach; we used an advanced simulation framework, allowing for accurate and detailed, close-to-reality simulations. Risk is estimated, in both cases, with combinations of indicators based on the TTC. For the non-cooperative approach, vehicles are equipped only with an AAC-like forward-facing ranging sensor. On the other hand, for the cooperative approach, vehicles share information through 802.11p IVC and create an augmented map representing their environment; risk indicators are then extracted from this map. Our system shows that the cooperative risk assessment provides a systematic increase of forward warning to most of the vehicles involved in a freeway emergency braking scenario, compared to a non-cooperative system.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

In cooperative communication systems, several wireless communication terminals collaborate to form a virtual-multiple antenna array system and exploit the spatial diversity to achieve a better performance. This thesis proposes a practical slotted protocol for cooperative communication systems with half-duplex single antennas. The performance of the proposed slotted cooperative communication protocol is evaluated in terms of the pairwise error probability and the bit error rate. The proposed protocol achieves the multiple-input single-output performance bound with a novel relay ordering and scheduling strategy.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

In this paper we analyse the effects of highway traffic flow parameters like vehicle arrival rate and density on the performance of Amplify and Forward (AF) cooperative vehicular networks along a multi-lane highway under free flow state. We derive analytical expressions for connectivity performance and verify them with Monte-Carlo simulations. When AF cooperative relaying is employed together with Maximum Ratio Combining (MRC) at the receivers the average route error rate shows 10-20 fold improvement compared to direct communication. A 4-8 fold increase in maximum number of traversable hops can also be observed at different vehicle densities when AF cooperative communication is used to strengthen communication routes. However the theorical upper bound of maximum number of hops promises higher performance gains.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

In this paper we describe cooperative control algorithms for robots and sensor nodes in an underwater environment. Cooperative navigation is defined as the ability of a coupled system of autonomous robots to pool their resources to achieve long-distance navigation and a larger controllability space. Other types of useful cooperation in underwater environments include: exchange of information such as data download and retasking; cooperative localization and tracking; and physical connection (docking) for tasks such as deployment of underwater sensor networks, collection of nodes and rescue of damaged robots. We present experimental results obtained with an underwater system that consists of two very different robots and a number of sensor network modules. We present the hardware and software architecture of this underwater system. We then describe various interactions between the robots and sensor nodes and between the two robots, including cooperative navigation. Finally, we describe our experiments with this underwater system and present data.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Layers (about 60-100 μm thick) of almost pure BaCuO2 (BC1), as determined using X-ray diffractometry (XRD) and scanning electron microscopy (SEM), coat the surfaces of YBa2Cu3O7-x (Y123) samples partial melt processed using a single-zone vertical furnace. The actual Cu/Ba ratio of the BC1 phase is 1.2-1.3 as determined using energy dispersive X-ray spectrometry (EDS). The nominally BC1 phase displays an exsolution of BC1.5 or BC2 in the form of thin plates (about 50-100 nm thick) along {100}-type cleavage planes or facets. The exsolved phase also fills cracks within the BC1 layer that require it to be in a molten state at some stage of processing. The samples were influenced by Pt contamination from the supporting wire, which may have stabilised the BC1.5 phase. Many of the Y123 grains have the same morphology as the exsolution domains, and run nearly parallel to the thin plates of the exsolved phases, strongly indicating that Y123 nucleation took place at the interface between the BC1 and the BC1.5 or BC2 exsolved phases. The network of nearly parallel exsolved 'channels' provides a matrix and a mechanism through which a high degree of local texture can be initiated in the material.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

IEEE 802.11p is the new standard for Inter-Vehicular Communications (IVC) using the 5.9 GHz frequency band, as part of the DSRC framework; it will enable applications based on Cooperative Systems. Simulation is widely used to estimate or verify the potential benefits of such cooperative applications, notably in terms of safety for the drivers. We have developed a performance model for 802.11p that can be used by simulations of cooperative applications (e.g. collision avoidance) without requiring intricate models of the whole IVC stack. Instead, it provide a a straightforward yet realistic modelisation of IVC performance. Our model uses data from extensive field trials to infer the correlation between speed, distance and performance metrics such as maximum range, latency and frame loss. Then, we improve this model to limit the number of profiles that have to be generated when there are more than a few couples of emitter-receptor in a given location. Our model generates realistic performance for rural or suburban environments among small groups of IVC-equipped vehicles and road side units.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Using cooperative learning in classrooms promotes academic achievement, communication skills, problem-solving, social skills and student motivation. Yet it is reported that cooperative learning as a Western educational concept may be ineffective in Asian cultural contexts. The study aims to investigate the utilisation of scaffolding techniques for cooperative learning in Thailand primary mathematics classes. A teacher training program was designed to foster Thai primary school teachers’ cooperative learning implementation. Two teachers participated in this experimental program for one and a half weeks and then implemented cooperative learning strategies in their mathematics classes for six weeks. The data collected from teacher interviews and classroom observations indicates that the difficulty or failure of implementing cooperative learning in Thailand education may not be directly derived from cultural differences. Instead, it does indicate that Thai culture can be constructively merged with cooperative learning through a teacher training program and practices of scaffolding techniques.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The Thailand education reform adopted cooperative learning to improve the quality of education. However, it has been reported that the introduction and maintenance of cooperative learning has been difficult and uncertain because of the cultural differences. The study proposed a conceptual framework developed based on making a connection between Thai cultures and cooperative learning elements, and implemented a small-scale research project in a Thai primary mathematics class with a teacher and thirty-two Grade 4 students. The results uncovered that the three components including preparation of teachers, instructional strategies and preparation of students can be vehicles for the culture integration in cooperative learning.