Construction of gridshells composed of elastically bent elements and covered by a stretched three-dimensional membrane

This document deals with the gridshells built by the Navier laboratory in the last ten years. The numerical conception is developed, from the draft made by architects up to the final structure. To design a gridshell several numerical tasks have to be performed. The geometry of the gridshell is first considered. Then, an iterative step mixing geometry and mechanical considerations is important. In particular, it is explained how the naturally straight beams are bent to form the final shape. This active bending provides many interests like high stiffness for a light weight structure. After the numerical design of the grid, the geometry of the membrane is drawn from the numerical final geometry of the gridshell. The improvements of gridshells, including safety considerations as well as practical considerations are then developed, trough the four gridshells recently built

Developing a voltage-stability-constrained security assessment system part I: Determination of power system voltage security operation limits

The method for determining the voltage security operation limits in a practical voltage security analysis (VSA) system based on VSAT software for large power systems is introduced in this paper. These operation limits include bus voltage limits, branch/corridor transfer power limits and P-load limit of the whole system. The voltage security operation limits are determined by the most critical contingency among the studied contingency set. The most critical contingency determines the P-load limit of the whole system, and all kinds of operation parameter limits are operation parameter values corresponding to this P-load limit under pre-contingency. An operation parameter limit is upper limit if the function relationship between this operation parameter and load power is an increasing curve, or lower limit if the function relationship between this operation parameter and load power is an decreasing curve. These operation parameter limits are helpful for operators to monitor the system operation state. © 2005 IEEE.published_or_final_versio

Narrowband Biphotons: Generation, Manipulation, and Applications

In this chapter, we review recent advances in generating narrowband biphotons with long coherence time using spontaneous parametric interaction in monolithic cavity with cluster effect as well as in cold atoms with electromagnetically induced transparency. Engineering and manipulating the temporal waveforms of these long biphotons provide efficient means for controlling light-matter quantum interaction at the single-photon level. We also review recent experiments using temporally long biphotons and single photons.Comment: to appear as a book chapter in a compilation "Engineering the Atom-Photon Interaction" published by Springer in 2015, edited by A. Predojevic and M. W. Mitchel

Insights from Modeling the 3D Structure of New Delhi Metallo-β-Lactamse and Its Binding Interactions with Antibiotic Drugs

New Delhi metallo-beta-lactamase (NDM-1) is an enzyme that makes bacteria resistant to a broad range of beta-lactam antibiotic drugs. This is because it can inactivate most beta-lactam antibiotic drugs by hydrolyzing them. For in-depth understanding of the hydrolysis mechanism, the three-dimensional structure of NDM-1 was developed. With such a structural frame, two enzyme-ligand complexes were derived by respectively docking Imipenem and Meropenem (two typical beta-lactam antibiotic drugs) to the NDM-1 receptor. It was revealed from the NDM-1/Imipenem complex that the antibiotic drug was hydrolyzed while sitting in a binding pocket of NDM-1 formed by nine residues. And for the case of NDM-1/Meropenem complex, the antibiotic drug was hydrolyzed in a binding pocket formed by twelve residues. All these constituent residues of the two binding pockets were explicitly defined and graphically labeled. It is anticipated that the findings reported here may provide useful insights for developing new antibiotic drugs to overcome the resistance problem

Environmental change and atmospheric contamination across China as indicated by lake sediments (Joint Project Q741)

In China, anthropogenic impact from changes in water quality, land-use and atmospheric deposition vary both spatially and temporally. There is a gradient across the country from the populous lowlands in the east, where considerable long-term impact on water bodies has resulted from centuries of agricultural and aquacultural practices superimposed by more recent, rapid industrial growth; to the mountainous west where many areas remain minimally impacted and any anthropogenic impact is restricted to long-range transport of atmospheric pollutants and change in climate. Currently, however, there is little information on temporal trends in atmospheric deposition. The importance of water resources in China cannot be overestimated and therefore determining the extent, rate and direction of change in water quality is a national priority. In the absence of long-term monitoring programmes, lake sediments remain the only way whereby this information can be retrospectively determined at the necessary temporal scale to ascertain whether the causes of any detriment in quality are as a result of natural changes, or due to agricultural or industrial impacts. Therefore, the aim of this research programme is to use lake sediments from three regions of China to detennine the extent to which impacts to lakes have changed through time and the causes of these changes. The project focuses on an east - west transect along the Yangtse River. The Middle and Lower Reaches of the Yangtse are undergoing exceptionally rapid economic and industrial development and this region is receiving a great deal of attention as the Three Gorges Dam undergoes construction. The three areas in which lakes are to be studied in this proposal are: l. Jiangsu Province in east China north of Shanghai. Lowland sites. Lakes in this area are likely to have been impacted by long-term agriculture and may therefore may have become eutrophic. Atmospheric deposition may also be significant from local and regional industrial sources. 2. The upper reaches of the Yangtse River, in Sichuan and Yunnan Provinces. Lakes at l-2000m. Lakes in this area may have been impacted by agriculture, but where possible sites will be selected where direct impact is minimal. Lakes may therefore be mesotrophic but sources of atmospherically derived industrial pollutants are likely to be remote. 3. The Tibetan Plateau. Lakes at 4 - 5000m. 'Control' sites in a pristine area with minimal human influence. Sediment cores from these sites will be used to detem1ine background levels of atmospherically deposited contaminants. Oligotrophic (low nutrient) sites on sensitive geology (low acid neutralising capacity e.g. granites) will be selected where possible. By including earlier collaborative work between the participating institutes (funded by the Royal Society and the Chinese Academy of Sciences) on the lake sediment records on the Jianghan Plain and research currently being undertaken on lakes in the Shennonggjia region in western Hubei (NNFSC funded), this study will produce a transect of lakes from five regions providing a unique database on the historical impact of human activity on the freshwater environment

Developing a voltage-stability-constrained security assessment system part II : Structure and function design and technology used

This is the second part in a two-part paper on the development of a voltage stability constrained security assessment system (VSC-SAS). In this part, overall VSC-SAS structure and function design and technology used will be presented. The system is expected to be used in both on-line and off-line modes. In on-line mode, on-line SCADA/EMS data will be used for VSC-SAS use; while in off-line mode (usually day-ahead calculation), historical data can be used for VSC-SAS. Both results (i.e. system operation limits) can be selected to compare with real time operation conditions and supervision power system operation security margin. © 2005 IEEE.published_or_final_versio

Exploring the impact of random telegraph noise-induced accuracy loss in Resistive RAM-based deep neural network

For Resistive RAM (RRAM)-based deep neural network, Random telegraph noise (RTN) causes accuracy loss during inference. In this work, we systematically investigated the impact of RTN on the complex deep neural networks (DNNs) with different datasets. By using 8 mainstream DNNs and 4 datasets, we explored the origin that caused the RTN-induced accuracy loss. Based on the understanding, for the first time, we proposed a new method to estimate the accuracy loss without going through time-consuming RTN simulation. The method was verified with other 10 DNN/dataset combinations that were not used for establishing the method. Finally, we discussed its potential adoption for the co-optimization of the DNN architecture and the RRAM technology, paving ways to RTN-induced accuracy loss mitigation for future neuromorphic hardware systems

Constraint Generation Algorithm for the Minimum Connectivity Inference Problem

Given a hypergraph $H$, the Minimum Connectivity Inference problem asks for a graph on the same vertex set as $H$ with the minimum number of edges such that the subgraph induced by every hyperedge of $H$ is connected. This problem has received a lot of attention these recent years, both from a theoretical and practical perspective, leading to several implemented approximation, greedy and heuristic algorithms. Concerning exact algorithms, only Mixed Integer Linear Programming (MILP) formulations have been experimented, all representing connectivity constraints by the means of graph flows. In this work, we investigate the efficiency of a constraint generation algorithm, where we iteratively add cut constraints to a simple ILP until a feasible (and optimal) solution is found. It turns out that our method is faster than the previous best flow-based MILP algorithm on random generated instances, which suggests that a constraint generation approach might be also useful for other optimization problems dealing with connectivity constraints. At last, we present the results of an enumeration algorithm for the problem.Comment: 16 pages, 4 tables, 1 figur

Channel selection for multispectral color imaging using binary differential evolution

2013-2014 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe