870 resultados para IEEE 802.11 distributed coordination function (DCF)
Resumo:
Energy resource scheduling is becoming increasingly important, such as the use of more distributed generators and electric vehicles connected to the distribution network. This paper proposes a methodology to be used by Virtual Power Players (VPPs), regarding the energy resource scheduling in smart grids and considering day-ahead, hour-ahead and realtime time horizons. This method considers that energy resources are managed by a VPP which establishes contracts with their owners. The full AC power flow calculation included in the model takes into account network constraints. In this paper, distribution function errors are used to simulate variations between time horizons, and to measure the performance of the proposed methodology. A 33-bus distribution network with large number of distributed resources is used.
Resumo:
IEEE International Conference on Cyber Physical Systems, Networks and Applications (CPSNA'15), Hong Kong, China.
Resumo:
11th IEEE World Conference on Factory Communication Systems (WFCS 2015). 27 to 29, May, 2015, TII-SS-2: Scheduling and Performance Analysis. Palma de Mallorca, Spain.
Resumo:
The paper presents a RFDSCA automated synthesis procedure. This algorithm determines several RFDSCA circuits from the top-level system specifications all with the same maximum performance. The genetic synthesis tool optimizes a fitness function proportional to the RFDSCA quality factor and uses the epsiv-concept and maximin sorting scheme to achieve a set of solutions well distributed along a non-dominated front. To confirm the results of the algorithm, three RFDSCAs were simulated in SpectreRF and one of them was implemented and tested. The design used a 0.25 mum BiCMOS process. All the results (synthesized, simulated and measured) are very close, which indicate that the genetic synthesis method is a very useful tool to design optimum performance RFDSCAs.
Resumo:
In a distributed key distribution scheme, a set of servers helps a set of users in a group to securely obtain a common key. Security means that an adversary who corrupts some servers and some users has no information about the key of a noncorrupted group. In this work, we formalize the security analysis of one such scheme which was not considered in the original proposal. We prove the scheme is secure in the random oracle model, assuming that the Decisional Diffie-Hellman (DDH) problem is hard to solve. We also detail a possible modification of that scheme and the one in which allows us to prove the security of the schemes without assuming that a specific hash function behaves as a random oracle. As usual, this improvement in the security of the schemes is at the cost of an efficiency loss.
Resumo:
Until the 1990's, Switzerland could be classified as either a corporatist, cooperative or coordinated market economy where non-market mechanisms of coordination among economic and political actors were very important. In this respect, Business Interest Associations (BIAs) played a key role. The aim of this paper is to look at the historical evolution of the five main peak Swiss BIAs through network analysis for five assorted dates during the 20th century (1910, 1937, 1957, 1980 and 2000) while relying on a database that includes more than 12,000 people. First, we examine the logic of membership in these associations, which allows us to analyze their position and function within the network of the Swiss economic elite. Until the 1980's, BIAs took part in the emergence and consolidation of a closely meshed national network, which declined during the two last decades of the 20th century. Second, we investigate the logic of influence of these associations by looking at the links they maintained with the political and administrative worlds through their links to the political parties and Parliament, and to the administration via the extra-parliamentary commissions (corporatist bodies). In both cases, the recent dynamic of globalization called into question the traditional role of BIAs.
Resumo:
The Engineering Research Institute at Iowa State University studied the organization and procedures for highway planning by all levels of government and the coordination among various state agencies and local governments in Iowa. Study information was derived from interviews, questionnaires, and a review of the literature. Representatives from state transportation or highway organizations in all states responded to questionnaires. Additionally, selected upper and intermediate level personnel from highway organizations in seven other states were interviewed and a visit was made to one state transportation department. Within Iowa, employees were interviewed in the Highway Commission, Office for Planning and Programming, Development Commission, Commerce Commission, Conservation Commission, and Highway Patrol. Nearly 600 officials of local governments in Iowa contributed factual data and opinions through questionnaires and interviews. Private citizens and consultants also provided input to the investigation through their responses to questionnaires. Twelve recommendations to improve highway planning in Iowa were formulated as a result of this study.
Resumo:
RPE65 is a retinoid isomerase required for the production of 11-cis-retinal, the chromophore of both cone and rod visual pigments. We recently established an R91W knock-in mouse strain as homologous animal model for patients afflicted by this mutation in RPE65. These mice have impaired vision and can only synthesize minute amounts of 11-cis-retinal. Here, we investigated the consequences of this chromophore insufficiency on cone function and pathophysiology. We found that the R91W mutation caused cone opsin mislocalization and progressive geographic cone atrophy. Remnant visual function was mostly mediated by rods. Ablation of rod opsin corrected the localization of cone opsin and improved cone retinal function. Thus, our analyses indicate that under conditions of limited chromophore supply rods and cones compete for 11-cis-retinal that derives from regeneration pathway(s) which are reliant on RPE65. Due to their higher number and the instability of cone opsin, rods are privileged under this condition while cones suffer chromophore deficiency and degenerate. These findings reinforce the notion that in patients any effective gene therapy with RPE65 needs to target the cone-rich macula directly to locally restore the cones' chromophore supply outside the reach of rods.
Resumo:
A number of metal complexes containing the ligand 5,5,7,12,12,14-hexamethyl-l,4,8,11-tetra-azatetradecane were synthesized and analyzed using electron impact (EI) and fast atom bombardment (FAB). The FAB mass spectra were obtained in positive and negative ion mode. FAB in the positive ion mode proved to be the most successful technique for the identification of these compounds. In the majority of cases the spectra obtained using positive ion FAB were structurally informative, although not all showed molecular (M+) or quasimolecular ([M+H]+) ions. The fragmentations observed were characteristic of the ligands, and were interpreted based on the chemistry of these compounds.
Resumo:
The onset of spontaneous seizures triggers a cascade of molecular and cellular events that eventually leads to neuronal injury and cognitive decline. The present study investigated the effect of Withania somnifera (WS) root extract and Withanolide A (WA) in restoring behavioural deficit by inhibiting oxidative stress induced alteration in glutamergic neurotransmission. The subdued performance in behavioural tests shows impaired motor coordination and memory. Histopathological investigations revealed significant neuronal loss in hippocampus of epileptic rats indicating glutamate mediated excitotoxicity. The treatment with WS and WA restored behavioural deficit and ameliorated neuronal loss. An altered redox homeostasis leading to oxidative stress is a hallmark of TLE. The antioxidant potential was afflicted in epileptic rats, evident from altered activity of SOD and CAT, down regulation of SOD and GPX expression and enhanced lipid peroxidation. The antioxidant property of WS and WA restored altered antioxidant capacity. Alteration in GDH activity and down regulation of GLAST expression resulted in enhanced glutamate content in the brain regions. The metabolism of glutamate was altered in the form of down regulated GAD expression. The alteration in synthesis, transport and metabolism resulted in further increase of the glutamate concentration at the synapse leading to glutamate mediated excitotoxicity. The decreased NMDA and AMPA receptor binding and down regulated NMDA R1, NMDA 2B and AMPA (GluR2) mRNA expression indicated altered glutamergic receptor function. The treatment with WS and WA reversed altered glutamergic receptor function, synthesis, transport and metabolism. The enhanced levels of second messenger IP3 responsible for Ca2+ mediated toxicity was reversed after treatment with WS and WA. Neurotoxics concentration of glutamate resulted in up regulation of pro apoptotic factors Bax and Caspase 8 and down regulation of anti apoptotic factor Akt resulting in neuronal death. The treatment with WS and WA resulted in activation of Akt and down regulation of Bax and caspase 8 leading to blocking of apoptotic pathway. The treatment with WS and WA resulted in reduced seizure frequency and amelioration of associated alterations suggesting the therapeutic role of Withania somnifera in temporal lobe epilepsy
Resumo:
English: The present thesis describes the synthesis of 1,1’-ferrocendiyl-based pyridylphosphine ligands, the exploration of their fundamental coordination chemistry and preliminary experiments with selected complexes aimed at potential applications. One main aspect is the synthesis of the bidentate ferrocene-based pyridylphosphine ligands 1-(Pyrid-2-yl)-1’-diphenylphosphinoferrocene, 1-(Pyrid-3-yl)-1’-diphenylphosphinoferrocene and 1-[(Pyrid-2-yl)methyl]-1’-diphenylphosphinoferrocene. A specific feature of these ligands is the ball-bearing like flexibility of the ferrocenebased backbone. An additional flexibility element is the rotation around the C–C single bonds. Consequently, the donor atoms can realise a wide range of positions with respect to each other and are therefore able to adapt to the coordination requirements of different metal centres. The flexibility of the ligand also plays a role in another key aspect of this work, which concerns the coordination mode, i. e. bridging vs. chelating. In addition to the flexibility, also the position of the donor atoms to each other is important. This is largely affected by the position of the pyridyl nitrogen (pyrid-2-yl vs. pyrid-3-yl) and the methylen group in 1-[(Pyrid-2-yl)methyl]-1’-diphenylphosphinoferrocene. Another interesting point is the combination of a soft phosphorus donor atom with a harder nitrogen donor atom, according to the HSAB principle. This combination generates a unique binding profile, since the pi-acceptor character of the P site is able to stabilise a metal centre in a low oxidation state, while the nitrogen sigma-donor ability can make the metal more susceptible to oxidative addition reactions. A P,N-donor combination can afford hemilabile binding profiles, which would be ideal for catalysis. Beyond 1,2-substituted ferrocene derivatives, which are quite successful in catalytic applications, 1,1’-derivatives are rather underrepresented. While a low-yield synthetic pathway to 1-(Pyrid-2-yl)-1’-diphenylphosphinoferrocene was already described in the literature [I. R. Butler, Organometallics 1992, 11, 74.], it was possible to find a new, improved and simplified synthetic pathway. Both other ligands were unknown prior to this work. Satisfactory results in the synthesis of 1-(Pyrid-3-yl)-1’-diphenylphosphinoferrocene could be achieved by working in analogy to the new synthetic procedure for 1-(Pyrid-2-yl)-1’-diphenylphosphinoferrocene. The synthesis of 1-[(Pyrid-2-yl)methyl]-1’-diphenylphosphinoferrocene has been handled by the group of Prof. Petr Stepnicka from Charles University, Prague, Czech Republic. The synthesis of tridentate ligands with an analogous heterodentate arrangement, was investigated briefly as a sideline of this study. The major part of this thesis deals with the fundamental coordination chemistry towards transition metals of the groups 10, 11 and 12. Due to the well-established catalytic properties of analogous palladium complexes, the coordination chemistry towards palladium (group 10) is of particular interest. The metals zinc and cadmium (group 12) are also of substantial importance because they are redox-inert in their divalent state. This is relevant in view of electrochemical investigations concerning the utilisation of the ligands as molecular redox sensors. Also mercury and the monovalent metals silver and gold (group 11) are included because of their rich coordination chemistry. It is essential to answer questions concerning aspects of the ligands’ coordination mode bearing in mind the HSAB principle.
Resumo:
In real world applications sequential algorithms of data mining and data exploration are often unsuitable for datasets with enormous size, high-dimensionality and complex data structure. Grid computing promises unprecedented opportunities for unlimited computing and storage resources. In this context there is the necessity to develop high performance distributed data mining algorithms. However, the computational complexity of the problem and the large amount of data to be explored often make the design of large scale applications particularly challenging. In this paper we present the first distributed formulation of a frequent subgraph mining algorithm for discriminative fragments of molecular compounds. Two distributed approaches have been developed and compared on the well known National Cancer Institute’s HIV-screening dataset. We present experimental results on a small-scale computing environment.
Resumo:
Evidence has been mounting for peripheral functions for tachykinins, a family of neuropeptides including substance P (SP), neurokinin A, and neurokinin B, which are recognized for their roles in the central and peripheral nervous system. The recent discovery of 4 new members of this family, the endokinins (EKA, B, C, and 13), which are distributed peripherally, adds support to the notion that tachykinins have physiologic/endocrine roles in the periphery. In the present study we report a fundamental new function for tachykinins in the regulation of platelet function. We show that SP stimulates platelet aggregation, and underlying this is the intracellular mobilization of calcium and degranulation. We demonstrate the presence of the tachykinin receptors NK1 and NK3 in platelets and present evidence for the involvement of NK1 in SP-mediated platelet aggregation. Platelets were found to contain SP-like immunoreactivity that is secreted upon activation implicating SP-like substances in the autocrine/paracrine regulation of these cells. Indeed, NK1-blocking antibodies inhibited aggregation in response to other agonists. Of particular note is the observation that EKA/B cross-react in the SP immunoassay and are also able to stimulate platelet activation. Together our data implicate tachykinins, specifically SP and EKA/B, in the regulation of platelet function. (C) 2004 by The American Society of Hematology.