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61.
AbstractThis article analyses how firms use events and trade fairs for external knowledge sourcing, which barriers emerge and how event organisers strategically mediate and influence those processes. The research setting focuses on two major automotive events in Shanghai, highlighting that knowledge sourcing in these events do complement other types of knowledge accessed in permanent ‘sites’ and organisational configurations, such as in clusters and through joint-ventures. Firms use automotive events to access buzz, to monitor other firms and to explore options for new collaborations. Yet, it is also argued that a focus on existing relations, the defensive strategies deployed by lead firms and the intrinsic complexity of exhibited technologies hinder the process of knowledge sourcing that is influenced by event organisers’ content, matchmaking and access policies. 相似文献
62.
Franz Andert Florian-M. Adolf Lukas Goormann Jörg S. Dittrich 《Journal of Intelligent and Robotic Systems》2010,57(1-4):259-280
The challenge for unmanned aerial vehicles to sense and avoid obstacles becomes even harder if narrow passages have to be crossed. An approach to solve a mission scenario that tackles the problem of such narrow passages is presented here. The task is to fly an unmanned helicopter autonomously through a course with gates that are only slightly larger than the vehicle itself. A camera is installed on the vehicle to detect the gates. Using vehicle localization data from a navigation solution, camera alignment and global gate positions are estimated simultaneously. The presented algorithm calculates the desired target waypoints to fly through the gates. Furthermore, the paper presents a mission execution plan that instructs the vehicle to search for a gate, to fly through it after successful detection, and to search for a proceeding one. All algorithms are designed to run onboard the vehicle so that no interaction with the ground control station is necessary, making the vehicle completely autonomous. To develop and optimize algorithms, and to prove the correctness and accuracy of vision-based gate detection under real operational conditions, gate positions are searched in images taken from manual helicopter flights. Afterwards, the integration of visual sensing and mission control is proven. The paper presents results from full autonomous flight where the helicopter searches and flies through a gate without operator actions. 相似文献
63.
Abstract. Blockwise access to data is a central theme in the design of efficient external memory (EM) algorithms. A second important issue, when more than one disk is present, is fully parallel disk I/ O. In this paper we present a simple, deterministic simulation technique which transforms certain Bulk Synchronous Parallel (BSP) algorithms into efficient parallel EM algorithms.
It optimizes blockwise data access and parallel disk I/ O and, at the same time, utilizes multiple processors connected via a communication network or shared memory. We obtain new improved parallel EM algorithms for a large number
of problems including sorting, permutation, matrix transpose, several geometric and GIS problems including three-dimensional
convex hulls (two-dimensional Voronoi diagrams), and various graph problems. We show that certain parallel algorithms known
for the BSP model can be used to obtain EM algorithms that meet well known I /O complexity lower bounds for various problems, including sorting. 相似文献
64.
With the exponential growth of moving objects data to the Gigabyte range, it has become critical to develop effective techniques
for indexing, updating, and querying these massive data sets. To meet the high update rate as well as low query response time
requirements of moving object applications, this paper takes a novel approach in moving object indexing. In our approach,
we do not require a sophisticated index structure that needs to be adjusted for each incoming update. Rather, we construct conceptually
simple short-lived index images that we only keep for a very short period of time (sub-seconds) in main memory. As a consequence, the resulting technique
MOVIES supports at the same time high query rates and high update rates, trading this property for query result staleness. Moreover, MOVIES is the first main memory method supporting time-parameterized predictive queries. To support this feature, we present two
algorithms: non-predictive MOVIES and predictive MOVIES. We obtain the surprising result that a predictive indexing approach—considered state-of-the-art in an external-memory scenario—does
not scale well in a main memory environment. In fact, our results show that MOVIES outperforms state-of-the-art moving object indexes such as a main-memory adapted B
x
-tree by orders of magnitude w.r.t. update rates and query rates. In our experimental evaluation, we index the complete road
network of Germany consisting of 40,000,000 road segments and 38,000,000 nodes. We scale our workload up to 100,000,000 moving
objects, 58,000,000 updates per second and 10,000 queries per second, a scenario at a scale unmatched by any previous work. 相似文献
65.
66.
Constanze Hartmann Sébastien Doucet Yvan Niclass Ralf Dittrich Susanne Cupisti Benoist Schaal Andrea Buettner Christian Starkenmann 《Food chemistry》2012
Using ultra performance liquid chromatography–mass spectrometry we identified for the first time glutamine-N-α-conjugates of the fatty acids (E)/(Z)-3-methylhex-2-enoic acid and (R)/(S)-3-hydroxy-3-methylhexanoic acid as well as cysteinylglycine-S-conjugates of (R)/(S)-3-methyl-3-sulphanylhexan-1-ol and (R)/(S)-3-sulphanylhexan-1-ol as constituents of human milk and colostrum. The glutamine-N-α-conjugates were detected also in human amniotic fluids. The mean values of glutamine-N-α-conjugate of (R)/(S)-3-hydroxy-3-methylhexanoic acid were highest in colostrums with a range of <0.1–382 μg/kg, followed by the mature human milk with values from <0.1 to 39.6 μg/kg for defatted milk, and 0.8–7.0 μg/kg in amniotic fluids. The cysteinylglycine-S-conjugate of (R)/(S)-3-methyl-3-sulphanylhexan-1-ol were detected in the range of 2–24 ng/kg in human milk, and 7–101 ng/kg in colostrums. Our data demonstrate that concentrations in human milk vary between individuals, and with lactation period as the mean concentrations of the glutamine conjugates in colostrums were elevated in comparison to mature milk and the concentrations of acid precursors were close to 10 times higher. Further, these precursors were not detected in cow milk. 相似文献
67.
A mathematical model of dehydroisomerization of methylcyclopentane in presence of bifunctional catalysts under industrial operating conditions is presented. The model consists of six differential equations. The rate constants are expressed as polynomial functions of the catalyst blend, and coefficients of these polynomials were determined from numerous measurements, taken along the axis of a tubular reactor. The resulting polynomial coefficients led to reaction rate constants which yielded results close to the actual process. 相似文献
68.
Präsident: Prof. Klaus Dittrich 《Informatik-Spektrum》2003,26(6):467-474
Ohne Zusammenfassung 相似文献
69.
70.
We examine the qualitative dynamics of a catalytic self-organizing system of binary strings that is inspired by the chemical information processing metaphor. A string is interpreted in two different ways: either (a) as raw data or (b) as a machine that is able to process another string as data in order to produce a third one. This article focuses on the phenomena of evolution whose appearance is notable because no explicit mutation, recombination, or artificial selection operators are introduced. We call the system self-evolving because every variation is performed by the objects themselves in their machine form. 相似文献