The problem of state space search is fundamental to many areas of computer science, such as, e.g., AI and formal methods. Often, the state space to be searched
is huge, so optimizing the search is an important issue. In this paper, we consider the problem of visiting all states in
the setting where transitions between states are generated by actions, and the (reachable) states are not known in advance.
Some of the actions may commute, i.e., they result in the same state for every order in which they are taken. We show how
to use commutativity to achieve full coverage of the states, while traversing a relatively small number of edges. 相似文献
Journal of Superconductivity and Novel Magnetism - NixZn1-xFe2O4 (x?=?0.0, 0.2, 0.4, 0.5, 0.6, 0.8 and 1.0) nanoferrites were synthesized using the citrate precursor method with... 相似文献
BACKGROUND: Previous works have suggested that the impairment of platelet aggregation by halothane was partly related to a stimulation of cyclic adenosine monophosphate (cAMP) production, to an inhibitory effect on Ca2+ signaling, or both. Intracellular Ca2+ measurements therefore were undertaken, first to determine the critical steps in the platelet CaZ+ signaling cascade most likely to be affected by halothane or by an increase in cAMP production, and second to establish if the effect of halothane involves aggregation-related biochemical pathways triggered by an increase in internal Ca2+. METHODS: Human washed platelets were treated with halothane or forskolin for 5 min before application of either platelet-activating factor, thrombin, U46619, or thapsigargin. The cytosolic Ca2+ concentration ([Ca2+]i) was measured with the fluorescent Ca2+ indicator fura-2. Nephelometric measurements were also performed to assay the aggregation process. RESULTS: Our results indicate that pretreating platelets with halothane leads to a partial impairment of the [Ca2+]i increase induced either by U46619, thrombin, or platelet-activating factor, but this had no significant effect on the [Ca2+]i response triggered by thapsigargin. In addition, our results show that halothane inhibits platelet aggregation triggered by U46619, but not by thapsigargin. Conversely, forskolin completely inhibited the [Ca2+]i response to U46619 and thapsigargin and prevented platelet aggregation induced by both agonists. CONCLUSIONS: These results suggest that halothane and cAMP exert their effects on platelet aggregation and Ca2+ signaling through different mechanisms, and that halothane cannot impair platelet aggregation independently of phospholipase C stimulation. 相似文献
When choosing a path for a linear infrastructure between two terminals, several types of constraints apply for installation and operational criteria. For offshore pipelines or cables, curvature constraints are typically important not only due to the flexural rigidity but also the maneuverability of the laying vessels. Roads are subject to similar curvature constraints to ensure the safety of users travelling at the design speed. Yet, such constraints are not taken into account in traditional least cost routing methods, often based on Dijkstra’s algorithm. Post-process smoothing is often necessary, resulting in non-optimal routes. We present a new method for least cost route optimization, allowing to incorporate the curvature constraints into the primary calculations as opposed to a post-determination consideration. With this technique, smoothing of the least cost route becomes unnecessary, preserving its optimal character. Optimization algorithms for the trajectories of forward-moving vehicles were adapted for the routing of linear infrastructures and modified to include an angular discretization of variable resolution, resulting in faster and more accurate results. In addition to the inclusion of curvature constraints, the proposed method offers a higher flexibility in terms of local route orientation compared to the traditional Dijkstra’s algorithm, producing routes of lower cost. The numerical solver was implemented on parallel architectures, to compute optimal routes on realistic domains in reasonable computational times. For personal computers with a few computing cores, the OpenMP implementation on Central Processing Units does not significantly increase the iteration count and provides significant speedups. For certain configurations, the use of Graphical Processing Units reduces further the computational time.
This paper presents a review of the latest developments on phase change materials (PCMs) for thermal energy storage (TES) applications in buildings. The paper provides information about material requirements for TES, classification of PCM, mathematical modelling and applications of PCMs. 相似文献
Two monoclonal antibodies (mAb) within cluster M4 of the myeloid section of the Second International Swine CD Workshop, C4 (No. 144) and PM18-7 (No. 192), showed reactivity with thymocytes and among cells of myelomonocytic origin with mature macrophages but not with monocytes and granulocytes. Both mAb recognize a protein showing two bands of 205 kDa and 130 kDa under both reducing and non-reducing conditions. Although epitope mapping with these mAb could not be performed, this cluster received the SWC9 designation. 相似文献
We study the problem of designing a feedback controller for a highly flexible Euler-Bernoulli beam using a distributed-parameter H∞-method. Employing skew Toeplitz theory, we derive the H∞-optimal controller for a weighted mixed sensitivity design for the beam. Based on the structure of the optimal controller we obtain suboptimal, finite-dimensional, linear, time-invariant controllers. With this approach we are able to include the added difficulties of a pure time delay and a noncollocated actuator/sensor pair directly into the design process. 相似文献
Seven species of the genus Argyranthemum were studied for antimicrobial and cytotoxic activities. Argyranthemum adauctum, A. foeniculaceum and A. frutescens showed antimicrobial activity against Gram-positive and Gram-negative and cytotoxic activity against HeLa and Hep-2 cell lines. Two new acetylenic compounds, frutescinol isovalerate and 3'-demethyl frutescinol isovalerate, were isolated from A. frutescens and their structures elucidated by spectroscopic studies. 相似文献