A Robust Consensus Algorithm for Current Sharing and Voltage Regulation in DC Microgrids

In this paper a novel distributed control algorithm for current sharing and voltage regulation in Direct Current (DC) microgrids is proposed. The DC microgrid is composed of several Distributed Generation units (DGUs), including Buck converters and current loads. The considered model permits an arbitrary network topology and is affected by unknown load demand and modelling uncertainties. The proposed control strategy exploits a communication network to achieve proportional current sharing using a consensus-like algorithm. Voltage regulation is achieved by constraining the system to a suitable manifold. Two robust control strategies of Sliding Mode (SM) type are developed to reach the desired manifold in a finite time. The proposed control scheme is formally analyzed, proving the achievement of proportional current sharing, while guaranteeing that the weighted average voltage of the microgrid is identical to the weighted average of the voltage references.Comment: 12 page

Morphological asymmetry and interspecific hybridization: A case study using hylid frogs

The limited studies addressing developmental stability of interspecific hybrids suggest a positive association between the level of fluctuating asymmetry and 1) the degree of divergence between parental species, and 2) the recency of the contact zone. To evaluate these associations, we examined asymmetry in a recentlyestablished hybrid population of treefrogs (Hyla cinerea and H. gratiosa) that show marked structural gene divergence. Fluctuating asymmetry (FA), directional asymmetry, and antisymmetry were assessed for eight paired osteometric traits in allozymically-defined parental and hybrid categories. FA levels varied considerably among traits. Nonetheless, for any given trait, the hybrid categories did not demonstrate elevated levels of FA compared to the parental categories, or compared to frogs from a non-hybridizing parental population. The only trait that differed statistically among categories (pterygoid length) involved a significantly lower FA value for the Fl hybrids. Thus, observed FA values do not support expectations that the hybrid categories should experience decreased developmental stability

Morphological asymmetry and interspecific hybridization: A case study using hylid frogs

The limited studies addressing developmental stability of interspecific hybrids suggest a positive association between the level of fluctuating asymmetry and 1) the degree of divergence between parental species, and 2) the recency of the contact zone. To evaluate these associations, we examined asymmetry in a recentlyestablished hybrid population of treefrogs (Hyla cinerea and H. gratiosa) that show marked structural gene divergence. Fluctuating asymmetry (FA), directional asymmetry, and antisymmetry were assessed for eight paired osteometric traits in allozymically-defined parental and hybrid categories. FA levels varied considerably among traits. Nonetheless, for any given trait, the hybrid categories did not demonstrate elevated levels of FA compared to the parental categories, or compared to frogs from a non-hybridizing parental population. The only trait that differed statistically among categories (pterygoid length) involved a significantly lower FA value for the Fl hybrids. Thus, observed FA values do not support expectations that the hybrid categories should experience decreased developmental stability

Robust Load Frequency Control of Nonlinear Power Networks

This paper proposes a decentralised second-order sliding mode (SOSM) control strategy for load frequency control (LFC) in power networks, regulating the frequency and maintaining the net inter-area power flows at their scheduled values. The considered power network is partitioned into control areas, where each area is modelled by an equivalent generator including second-order turbine-governor dynamics, and where the areas are nonlinearly coupled through the power flows. Asymptotic convergence to the desired state is established by constraining the state of the power network on a suitably designed sliding manifold. This manifold is designed relying on stability considerations made on the basis of an incremental energy (storage) function. Simulation results confirm the effectiveness of the proposed control approach

Evidence of Two Functionally Distinct Ornithine Decarboxylation Systems in Lactic Acid Bacteria

Biogenic amines are low-molecular-weight organic bases whose presence in food can result in health problems. The biosynthesis of biogenic amines in fermented foods mostly proceeds through amino acid decarboxylation carried out by lactic acid bacteria (LAB), but not all systems leading to biogenic amine production by LAB have been thoroughly characterized. Here, putative ornithine decarboxylation pathways consisting of a putative ornithine decarboxylase and an amino acid transporter were identified in LAB by strain collection screening and database searches. The decarboxylases were produced in heterologous hosts and purified and characterized in vitro, whereas transporters were heterologously expressed in Lactococcus lactis and functionally characterized in vivo. Amino acid decarboxylation by whole cells of the original hosts was determined as well. We concluded that two distinct types of ornithine decarboxylation systems exist in LAB. One is composed of an ornithine decarboxylase coupled to an ornithine/putrescine transmembrane exchanger. Their combined activities results in the extracellular release of putrescine. This typical amino acid decarboxylation system is present in only a few LAB strains and may contribute to metabolic energy production and/or pH homeostasis. The second system is widespread among LAB. It is composed of a decarboxylase active on ornithine and L-2,4-diaminobutyric acid (DABA) and a transporter that mediates unidirectional transport of ornithine into the cytoplasm. Diamines that result from this second system are retained within the cytosol.

Morphological asymmetry and interspecific hybridization: A case study using hylid frogs

Abstract The limited studies addressing developmental stability of interspecific hybrids suggest a positive association between the level of fluctuating asymmetry and 1) the degree of divergence between parental species, and 2) the recency of the contact zone. To evaluate these associations, we examined asymmetry in a recentlyestablished hybrid population of treefrogs (Hyla cinerea and H. gratiosa) that show marked structural gene divergence. Fluctuating asymmetry (FA), directional asymmetry, and antisymmetry were assessed for eight paired osteometric traits in allozymically-defined parental and hybrid categories. FA levels varied considerably among traits. Nonetheless, for any given trait, the hybrid categories did not demonstrate elevated levels of FA compared to the parental categories, or compared to frogs from a non-hybridizing parental population. The only trait that differed statistically among categories (pterygoid length) involved a significantly lower FA value for the Fl hybrids. Thus, observed FA values do not support expectations that the hybrid categories should experience decreased developmental stability

Male-Specific Association between a γ-Secretase Polymorphism and Premature Coronary Atherosclerosis

Contains fulltext : 69125.pdf (publisher's version ) (Open Access)6 p

Scenariographer: a tool for reverse engineering class usage scenarios from method invocation sequences

Proceedings of the 2005 International Conference on Software Maintenance (ICSM'05), Budapest, Hungary, September, 2005. Retrieved 3/16/2006 from http://www.cs.drexel.edu/~spiros/research/papers/ICSM05a.pdfTypical documentation for object-oriented programs includes descriptions of the parameters and return types of each method in a class, but little or no information on valid method invocation sequences. Knowing the sequence with which methods of a class can be invoked is useful information especially for software engineers (e.g., developers, testers) who are actively involved in the maintenance of large software systems. This paper describes a new approach and a tool for generating class usage scenarios (i.e., how a class is used by other classes) from method invocations, which are collected during the execution of the software. Our approach is algorithmic and employs the notion of canonical sets to categorize method sequences into groups of similar sequences, where each group represents a usage scenario for a given class

Association Between Increased Platelet P-Selectin Expression and Obesity in Patients With Type 2 Diabetes: A BARI 2D (Bypass Angioplasty Revascularization Investigation 2 Diabetes) substudy

OBJECTIVE- To determine whether obesity increases platelet reactivity and thrombin activity in patients with type 2 diabetes plus stable coronary artery disease. RESEARCH DESIGN AND METHODS- We assessed platelet reactivity and markers of thrombin generation and activity in 193 patients from nine clinical sites of the Bypass Angioplasty Revascularization Investigation 2 Diabetes (BARI 2D). Blood taken at the time of enrollment was used for assay of the concentration of prothrombin fragment 1.2 (PT1.2, released when prothrombin is activated) and fibrinopeptide A (FPA, released when fibrinogen is cleaved). Platelet activation was identified with the use of flow cytometry in response to 0, 0.2, and 1 mu mol/l adenosine diphosphate (ADP). RESULTS- Concentrations of FPA, PT1.2, and platelet activation in the absence of agonist were low. Greater BMI was associated with higher platelet reactivity in response to 1 mu m ADP as assessed by surface expression of P-selectin (r = 0.29, P < 0.0001) but not reflected by the binding of fibrinogen to activated glycoprotein IIb-IIIa. BMI was not associated with concentrations of FPA or PT1.2. Platelet reactivity correlated negatively with A1C (P < 0.04), was not related to the concentration Of triglycerides in blood, and did not correlate with the concentration of C-reactive peptide. CONCLUSIONS- Among patients enrolled in this substudy of BARI 2D, a greater BMI was associated with higher platelet reactivity at the time of enrollment. Our results suggest that obesity and insulin resistance that accompanies obesity may influence platelet reactivity in patients with type 2 diabetes.National Heart, Lung, and Blood Institute (NHLBI/NIH)[R01 HL69146]National Heart, Lung, and Blood Institute (NHLBI/NIH)[R01 HL71306]NHLBI[U01 HL061746]NHLBI[U01 HL06171748]NHLBI[U01 HL06384]National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK/NIH)[HL061744