DEFF Research Database (Denmark)
Brodal, Gerth Stølting; Moruz, Gabriel
2006-01-01
It is well-known that to minimize the number of comparisons a binary search tree should be perfectly balanced. Previous work has shown that a dominating factor over the running time for a search is the number of cache faults performed, and that an appropriate memory layout of a binary search tree...... can reduce the number of cache faults by several hundred percent. Motivated by the fact that during a search branching to the left or right at a node does not necessarily have the same cost, e.g. because of branch prediction schemes, we in this paper study the class of skewed binary search trees....... For all nodes in a skewed binary search tree the ratio between the size of the left subtree and the size of the tree is a fixed constant (a ratio of 1/2 gives perfect balanced trees). In this paper we present an experimental study of various memory layouts of static skewed binary search trees, where each...
A. de Bruin (Arie); W.H.L.M. Pijls (Wim)
2003-01-01
textabstractThis paper deals with algorithms searching trees generated by two-person, zero-sum games with perfect information. The standard algorithm in this field is alpha-beta. We will discuss this algorithm as well as extensions, like transposition tables, iterative deepening and NegaScout. Speci
A. de Bruin (Arie); W.H.L.M. Pijls (Wim)
2003-01-01
textabstractThis paper deals with algorithms searching trees generated by two-person, zero-sum games with perfect information. The standard algorithm in this field is alpha-beta. We will discuss this algorithm as well as extensions, like transposition tables, iterative deepening and NegaScout.
A two-level cache for distributed information retrieval in search engines.
Zhang, Weizhe; He, Hui; Ye, Jianwei
2013-01-01
To improve the performance of distributed information retrieval in search engines, we propose a two-level cache structure based on the queries of the users' logs. We extract the highest rank queries of users from the static cache, in which the queries are the most popular. We adopt the dynamic cache as an auxiliary to optimize the distribution of the cache data. We propose a distribution strategy of the cache data. The experiments prove that the hit rate, the efficiency, and the time consumption of the two-level cache have advantages compared with other structures of cache.
A Two-Level Cache for Distributed Information Retrieval in Search Engines
Directory of Open Access Journals (Sweden)
Weizhe Zhang
2013-01-01
Full Text Available To improve the performance of distributed information retrieval in search engines, we propose a two-level cache structure based on the queries of the users’ logs. We extract the highest rank queries of users from the static cache, in which the queries are the most popular. We adopt the dynamic cache as an auxiliary to optimize the distribution of the cache data. We propose a distribution strategy of the cache data. The experiments prove that the hit rate, the efficiency, and the time consumption of the two-level cache have advantages compared with other structures of cache.
Tree Searching and Student Problem Solving
Alderman, Donald L.
1978-01-01
Tree searching was applied as a computer model of simple addition sentences. Results indicated that the number of problem reductions performed in tree searching accounted for most of the variance across problems in student error rate and solution time. The technique constitutes a computer test for the adequacy of a problem solving prescription.…
Fringe trees, Crump-Mode-Jagers branching processes and $m$-ary search trees
Holmgren, Cecilia; Janson, Svante
2016-01-01
This survey studies asymptotics of random fringe trees and extended fringe trees in random trees that can be constructed as family trees of a Crump-Mode-Jagers branching process, stopped at a suitable time. This includes random recursive trees, preferential attachment trees, fragmentation trees, binary search trees and (more generally) $m$-ary search trees, as well as some other classes of random trees. We begin with general results, mainly due to Aldous (1991) and Jagers and Nerman (1984). T...
An analysis of Monte Carlo tree search
CSIR Research Space (South Africa)
James, S
2017-02-01
Full Text Available Monte Carlo Tree Search (MCTS) is a family of directed search algorithms that has gained widespread attention in recent years. Despite the vast amount of research into MCTS, the effect of modifications on the algorithm, as well as the manner...
Understanding search trees via statistical physics
Indian Academy of Sciences (India)
N Majumdar Sathya; S Dean David; P L Krapivsky
2005-06-01
We study the random -ary search tree model (where stands for the number of branches of the search tree), an important problem for data storage in computer science, using a variety of statistical physics techniques that allow us to obtain exact asymptotic results. In particular, we show that the probability distributions of extreme observables associated with a random search tree such as the height and the balanced height of a tree have a travelling front structure. In addition, the variance of the number of nodes needed to store a data string of a given size is shown to undergo a striking phase transition at a critical value of the branching ratio c = 26. We identified the mechanism of this phase transition and showed that it is generic and occurs in various other problems as well. New results are obtained when each element of the data string is a -dimensional vector. We show that this problem also has a phase transition at a critical dimension, c = /sin−1 (1/$\\sqrt{8}$) = 8.69363 . . ..
A two-level parallel direct search implementation for arbitrarily sized objective functions
Energy Technology Data Exchange (ETDEWEB)
Hutchinson, S.A.; Shadid, N.; Moffat, H.K. [Sandia National Labs., Albuquerque, NM (United States)] [and others
1994-12-31
In the past, many optimization schemes for massively parallel computers have attempted to achieve parallel efficiency using one of two methods. In the case of large and expensive objective function calculations, the optimization itself may be run in serial and the objective function calculations parallelized. In contrast, if the objective function calculations are relatively inexpensive and can be performed on a single processor, then the actual optimization routine itself may be parallelized. In this paper, a scheme based upon the Parallel Direct Search (PDS) technique is presented which allows the objective function calculations to be done on an arbitrarily large number (p{sub 2}) of processors. If, p, the number of processors available, is greater than or equal to 2p{sub 2} then the optimization may be parallelized as well. This allows for efficient use of computational resources since the objective function calculations can be performed on the number of processors that allow for peak parallel efficiency and then further speedup may be achieved by parallelizing the optimization. Results are presented for an optimization problem which involves the solution of a PDE using a finite-element algorithm as part of the objective function calculation. The optimum number of processors for the finite-element calculations is less than p/2. Thus, the PDS method is also parallelized. Performance comparisons are given for a nCUBE 2 implementation.
Development of a Concurrent Tree Search Program.
1982-10-01
rtfiia intelience Evefonith good0 heriti funcions Ohe tieiPAESo 4 sarch.I~ AtErC AM discussing (i concuret p o roramn issue asI bEUIYCAkgroundhi...tree search, is fundamental to the field of artificial intelligence. Even with good heuristic functions, the time it takes on a single processor to...fundamental to the field of artificial intelligence. Even with good heuristic functions, the time it takes on a single processor to solve progressively
Nearest neighbor search algorithm for GBD tree spatial data structure
Institute of Scientific and Technical Information of China (English)
Yutaka Ohsawa; Takanobu Kurihara; Ayaka Ohki
2007-01-01
This paper describes the nearest neighbor (NN) search algorithm on the GBD(generalized BD) tree. The GBD tree is a spatial data structure suitable for two- or three-dimensional data and has good performance characteristics with respect to the dynamic data environment. On GIS and CAD systems, the R-tree and its successors have been used. In addition, the NN search algorithm is also proposed in an attempt to obtain good performance from the R-tree. On the other hand, the GBD tree is superior to the R-tree with respect to exact match retrieval, because the GBD tree has auxiliary data that uniquely determines the position of the object in the structure. The proposed NN search algorithm depends on the property of the GBD tree described above. The NN search algorithm on the GBD tree was studied and the performance thereof was evaluated through experiments.
Creating, Searching, and Deleting KD Trees Using C++
2014-09-01
Creating, Searching, and Deleting KD Trees Using C++ by Robert J Yager ARL-TN-0629 September 2014...Deleting KD Trees Using C++ by Robert J Yager Weapons and Materials Research Directorate, ARL...Searching, and Deleting KD Trees Using C++ 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Robert J Yager
Cache-Oblivious Search Trees via Binary Trees of Small Height
DEFF Research Database (Denmark)
Brodal, G.S.; Fagerberg, R.; Jacob, R.
2002-01-01
We propose a version of cache oblivious search trees which is simpler than the previous proposal of Bender, Demaine and Farach-Colton and has the same complexity bounds. In particular, our data structure avoids the use of weight balanced B-trees, and can be implemented as just a single array......, and range queries in worst case O(logB n + k/B) memory transfers, where k is the size of the output.The basic idea of our data structure is to maintain a dynamic binary tree of height log n+O(1) using existing methods, embed this tree in a static binary tree, which in turn is embedded in an array in a cache...... oblivious fashion, using the van Emde Boas layout of Prokop.We also investigate the practicality of cache obliviousness in the area of search trees, by providing an empirical comparison of different methods for laying out a search tree in memory....
Concurrent Manipulation of Binary Search Trees. Revision.
1979-09-01
trees (or often B*-trees; see Wedekind [23]) as the main data structure (e.g., Astrachan, et.aL[1]). These structures have the advantage that they are...Conference Proceedings 46 (1977), 637-644. 23. Wedekind . On the Selection of Access Paths in a Data Base System. In Data Base Management, North-Holland
Performance Characterization of Parallel Game-tree Search Application Crafty
Institute of Scientific and Technical Information of China (English)
TAN Ying; LUO Ke-lu; CHEN Yu-rong; ZHANG Yi-min
2006-01-01
Game-tree search plays an important role in the field of Artificial Intelligence (AI). In this paper, we characterize one parallel game-tree search workload in chess: the latest version of Crafty, a state of art program, on two Intel Xeon(r) shared-memory multiprocessor systems. Our analysis shows that Crafty is latency-sensitive and the hash-table and dynamic tree splitting used in Crafty cause large scalability penalties. They consume 35%-50% of the running time on the 4-way system. Furthermore, Crafty is not bandwidth-limited.
Depth-first search in split-by-edges trees
Brændeland, Asbjørn
2015-01-01
A layerwise search in a split-by-edges tree (as defined by Br{\\ae}ndeland, 2015) of agiven graph produces a maximum independent set in exponential time. A depth-first search produces an independent set, which may or may not be a maximum, in linear time, but the worst case success rate is maybe not high enough to make it really interesting. What may make depth-first searching in split-by-edges trees interesting, though, is the pronounced oscillation of its success rate along the graph size axis.
Computing a Clique Tree with the Algorithm Maximal Label Search
Directory of Open Access Journals (Sweden)
Anne Berry
2017-01-01
Full Text Available The algorithm MLS (Maximal Label Search is a graph search algorithm that generalizes the algorithms Maximum Cardinality Search (MCS, Lexicographic Breadth-First Search (LexBFS, Lexicographic Depth-First Search (LexDFS and Maximal Neighborhood Search (MNS. On a chordal graph, MLS computes a PEO (perfect elimination ordering of the graph. We show how the algorithm MLS can be modified to compute a PMO (perfect moplex ordering, as well as a clique tree and the minimal separators of a chordal graph. We give a necessary and sufficient condition on the labeling structure of MLS for the beginning of a new clique in the clique tree to be detected by a condition on labels. MLS is also used to compute a clique tree of the complement graph, and new cliques in the complement graph can be detected by a condition on labels for any labeling structure. We provide a linear time algorithm computing a PMO and the corresponding generators of the maximal cliques and minimal separators of the complement graph. On a non-chordal graph, the algorithm MLSM, a graph search algorithm computing an MEO and a minimal triangulation of the graph, is used to compute an atom tree of the clique minimal separator decomposition of any graph.
Search Trees with Relaxed Balance and Near-Optimal Height
DEFF Research Database (Denmark)
Fagerberg, Rolf; Larsen, Kim Skak; Jensen, Rune E.
2001-01-01
We introduce a relaxed k-tree, a search tree with relaxed balance and a height bound, when in balance, of (1+epsilon)log_2 n + 1, for any epsilon > 0. The number of nodes involved in rebalancing is O(1/epsilon) per update in the amortized sense, and O(log n/epsilon) in the worst case sense. This ...... constant rebalancing, which is an improvement over the current definition. World Wide Web search engines are possible applications for this line of work.......We introduce a relaxed k-tree, a search tree with relaxed balance and a height bound, when in balance, of (1+epsilon)log_2 n + 1, for any epsilon > 0. The number of nodes involved in rebalancing is O(1/epsilon) per update in the amortized sense, and O(log n/epsilon) in the worst case sense....... This is the first binary search tree with relaxed balance having a height bound better than c log_2 n for a fixed constant c. In all previous proposals, the constant is at least 1/log_2 phi>1.44, where phi is the golden ratio. As a consequence, we can also define a standard (non-relaxed) k-tree with amortized...
Upper Bounds for Maximally Greedy Binary Search Trees
Fox, Kyle
2011-01-01
At SODA 2009, Demaine et al. presented a novel connection between binary search trees (BSTs) and subsets of points on the plane. This connection was independently discovered by Derryberry et al. As part of their results, Demaine et al. considered GreedyFuture, an offline BST algorithm that greedily rearranges the search path to minimize the cost of future searches. They showed that GreedyFuture is actually an online algorithm in their geometric view, and that there is a way to turn GreedyFuture into an online BST algorithm with only a constant factor increase in total search cost. Demaine et al. conjectured this algorithm was dynamically optimal, but no upper bounds were given in their paper. We prove the first non-trivial upper bounds for the cost of search operations using GreedyFuture including giving an access lemma similar to that found in Sleator and Tarjan's classic paper on splay trees.
Monte-Carlo Tree Search for Simulated Car Racing
DEFF Research Database (Denmark)
Fischer, Jacob; Falsted, Nikolaj; Vielwerth, Mathias
2015-01-01
Monte Carlo Tree Search (MCTS) has recently seen considerable success in playing certain types of games, most of which are discrete, fully observable zero-sum games. Consequently there is currently considerable interest within the research community in investigating what other games this algorithm...... of the action space. This combination allows the controller to effectively search the tree of potential future states. Results show that it is indeed possible to implement a competent MCTS-based racing controller. The controller generalizes to most road tracks as long as a warm-up period is provided....
Monte-Carlo Tree Search for Simulated Car Racing
DEFF Research Database (Denmark)
Fischer, Jacob; Falsted, Nikolaj; Vielwerth, Mathias
2015-01-01
Monte Carlo Tree Search (MCTS) has recently seen considerable success in playing certain types of games, most of which are discrete, fully observable zero-sum games. Consequently there is currently considerable interest within the research community in investigating what other games this algorithm...... of the action space. This combination allows the controller to effectively search the tree of potential future states. Results show that it is indeed possible to implement a competent MCTS-based racing controller. The controller generalizes to most road tracks as long as a warm-up period is provided....
Searching Fragment Spaces with feature trees.
Lessel, Uta; Wellenzohn, Bernd; Lilienthal, Markus; Claussen, Holger
2009-02-01
Virtual combinatorial chemistry easily produces billions of compounds, for which conventional virtual screening cannot be performed even with the fastest methods available. An efficient solution for such a scenario is the generation of Fragment Spaces, which encode huge numbers of virtual compounds by their fragments/reagents and rules of how to combine them. Similarity-based searches can be performed in such spaces without ever fully enumerating all virtual products. Here we describe the generation of a huge Fragment Space encoding about 5 * 10(11) compounds based on established in-house synthesis protocols for combinatorial libraries, i.e., we encode practically evaluated combinatorial chemistry protocols in a machine readable form, rendering them accessible to in silico search methods. We show how such searches in this Fragment Space can be integrated as a first step in an overall workflow. It reduces the extremely huge number of virtual products by several orders of magnitude so that the resulting list of molecules becomes more manageable for further more elaborated and time-consuming analysis steps. Results of a case study are presented and discussed, which lead to some general conclusions for an efficient expansion of the chemical space to be screened in pharmaceutical companies.
Time management for Monte-Carlo tree search in Go
Baier, Hendrik; Winands, Mark H M
2012-01-01
The dominant approach for programs playing the game of Go is nowadays Monte-Carlo Tree Search (MCTS). While MCTS allows for fine-grained time control, little has been published on time management for MCTS programs under tournament conditions. This paper investigates the effects that various time-man
Optimal Finger Search Trees in the Pointer Machine
DEFF Research Database (Denmark)
Brodal, Gerth Stølting; Lagogiannis, George; Makris, Christos
2003-01-01
We develop a new finger search tree with worst-case constant update time in the Pointer Machine (PM) model of computation. This was a major problem in the field of Data Structures and was tantalizingly open for over twenty years while many attempts by researchers were made to solve it. The result...
USING PRECEDENTS FOR REDUCTION OF DECISION TREE BY GRAPH SEARCH
Directory of Open Access Journals (Sweden)
I. A. Bessmertny
2015-01-01
Full Text Available The paper considers the problem of mutual payment organization between business entities by means of clearing that is solved by search of graph paths. To reduce the decision tree complexity a method of precedents is proposed that consists in saving the intermediate solution during the moving along decision tree. An algorithm and example are presented demonstrating solution complexity coming close to a linear one. The tests carried out in civil aviation settlement system demonstrate approximately 30 percent shortage of real money transfer. The proposed algorithm is planned to be implemented also in other clearing organizations of the Russian Federation.
Bayesian Inference in Monte-Carlo Tree Search
Tesauro, Gerald; Segal, Richard
2012-01-01
Monte-Carlo Tree Search (MCTS) methods are drawing great interest after yielding breakthrough results in computer Go. This paper proposes a Bayesian approach to MCTS that is inspired by distributionfree approaches such as UCT [13], yet significantly differs in important respects. The Bayesian framework allows potentially much more accurate (Bayes-optimal) estimation of node values and node uncertainties from a limited number of simulation trials. We further propose propagating inference in the tree via fast analytic Gaussian approximation methods: this can make the overhead of Bayesian inference manageable in domains such as Go, while preserving high accuracy of expected-value estimates. We find substantial empirical outperformance of UCT in an idealized bandit-tree test environment, where we can obtain valuable insights by comparing with known ground truth. Additionally we rigorously prove on-policy and off-policy convergence of the proposed methods.
Limiting theorems for the nodes in binary search trees
Institute of Scientific and Technical Information of China (English)
2008-01-01
We consider three random variables X_n, Y_n and Z_n, which represent the numbers of the nodes with 0, 1, and 2 children, in the binary search trees of size n. The expectation and variance of the three above random variables are got, and it is also shown that X_n, Y_n and Z_n are all asymptotically normal as n→∞by applying the contraction method.
A new classification algorithm based on RGH-tree search
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
In this paper, we put forward a new classification algorithm based on RGH-Tree search and perform the classification analysis and comparison study. This algorithm can save computing resource and increase the classification efficiency. The experiment shows that this algorithm can get better effect in dealing with three dimensional multi-kind data. We find that the algorithm has better generalization ability for small training set and big testing result.
Optimum Binary Search Trees on the Hierarchical Memory Model
Thite, Shripad
2008-01-01
The Hierarchical Memory Model (HMM) of computation is similar to the standard Random Access Machine (RAM) model except that the HMM has a non-uniform memory organized in a hierarchy of levels numbered 1 through h. The cost of accessing a memory location increases with the level number, and accesses to memory locations belonging to the same level cost the same. Formally, the cost of a single access to the memory location at address a is given by m(a), where m: N -> N is the memory cost function, and the h distinct values of m model the different levels of the memory hierarchy. We study the problem of constructing and storing a binary search tree (BST) of minimum cost, over a set of keys, with probabilities for successful and unsuccessful searches, on the HMM with an arbitrary number of memory levels, and for the special case h=2. While the problem of constructing optimum binary search trees has been well studied for the standard RAM model, the additional parameter m for the HMM increases the combinatorial comp...
Implementation of Binary Search Trees Via Smart Pointers
Directory of Open Access Journals (Sweden)
Ivaylo Donchev
2015-03-01
Full Text Available Study of binary trees has prominent place in the training course of DSA (Data Structures and Algorithms. Their implementation in C++ however is traditionally difficult for students. To a large extent these difficulties are due not so much to the complexity of algorithms as to language complexity in terms of memory management by raw pointers – the programmer must consider too many details to ensure a reliable, efficient and secure implementation. Evolution of C++ regarded to automated resource management, as well as experience in implementation of linear lists by means of C++ 11/14 lead to an attempt to implement binary search trees (BST via smart pointers as well. In the present paper, the authors share experience in this direction. Some conclusions about pedagogical aspects and effectiveness of the new classes, compared to traditional library containers and implementation with built-in pointers, are made.
Alexander Safatli; Christian Blouin
2015-01-01
Summary. Pylogeny is a cross-platform library for the Python programming language that provides an object-oriented application programming interface for phylogenetic heuristic searches. Its primary function is to permit both heuristic search and analysis of the phylogenetic tree search space, as well as to enable the design of novel algorithms to search this space. To this end, the framework supports the structural manipulation of phylogenetic trees, in particular using rearrangement operator...
Monte-Carlo Tree Search in Settlers of Catan
Szita, István; Chaslot, Guillaume; Spronck, Pieter
Games are considered important benchmark opportunities for artificial intelligence research. Modern strategic board games can typically be played by three or more people, which makes them suitable test beds for investigating multi-player strategic decision making. Monte-Carlo Tree Search (MCTS) is a recently published family of algorithms that achieved successful results with classical, two-player, perfect-information games such as Go. In this paper we apply MCTS to the multi-player, non-deterministic board game Settlers of Catan. We implemented an agent that is able to play against computer-controlled and human players. We show that MCTS can be adapted successfully to multi-agent environments, and present two approaches of providing the agent with a limited amount of domain knowledge. Our results show that the agent has a considerable playing strength when compared to game implementation with existing heuristics. So, we may conclude that MCTS is a suitable tool for achieving a strong Settlers of Catan player.
Keyword Searches in Data-Centric XML Documents Using Tree Partitioning
Institute of Scientific and Technical Information of China (English)
LI Guoliang; FENG Jianhua; ZHOU Lizhu
2009-01-01
This paper presents an effective keyword search method for data-centric extensive markup language (XML) documents.The method divides an XML document into compact connected integral subtrees,called self-integral trees (Si-Trees),to capture the structural information in the XML document.The Si-Trees are generated based on a schema guide.Meaningful self-integral trees (MSI-Trees) are identified,which contain all or some of the input keywords for the keyword search in the XML documents.Indexing is used to accelerate the retrieval of MSI-Trees related to the input keywords.The MSI-Trees are ranked to identify the top-k results with the highest ranks.Extensive tests demonstrate that this method costs 10-100 ms to answer a keyword query,and outperforms existing approaches by 1-2 orders of magnitude.
Monte Carlo tree search in the board game of Scotland Yard
ILENIČ, NEJC
2015-01-01
Because of its success in the computer game of Go, Monte Carlo Tree Search is becoming a progressively popular decision making algorithm in various domains. It has proven its strengths in singleplayer and multiplayer games with perfect information, however domain specific improvements must be introduced in games with imperfect information. In thesis existing approaches to the problem of applying the tree search to the Scotland Yard board game are described and empiricaly tested. It has tu...
PhyloFinder: An intelligent search engine for phylogenetic tree databases
Directory of Open Access Journals (Sweden)
Bansal Mukul S
2008-03-01
Full Text Available Abstract Background Bioinformatic tools are needed to store and access the rapidly growing phylogenetic data. These tools should enable users to identify existing phylogenetic trees containing a specified taxon or set of taxa and to compare a specified phylogenetic hypothesis to existing phylogenetic trees. Results PhyloFinder is an intelligent search engine for phylogenetic databases that we have implemented using trees from TreeBASE. It enables taxonomic queries, in which it identifies trees in the database containing the exact name of the query taxon and/or any synonymous taxon names, and it provides spelling suggestions for the query when there is no match. Additionally, PhyloFinder can identify trees containing descendants or direct ancestors of the query taxon. PhyloFinder also performs phylogenetic queries, in which it identifies trees that contain the query tree or topologies that are similar to the query tree. Conclusion PhyloFinder can enhance the utility of any tree database by providing tools for both taxonomic and phylogenetic queries as well as visualization tools that highlight the query results and provide links to NCBI and TBMap. An implementation of PhyloFinder using trees from TreeBASE is available from the web client application found in the availability and requirements section.
Monte carlo tree search with heuristic evaluations using implicit minimax backups
Lanctot, Marc; Winands, Mark H M; Pepels, Tom; Sturtevant, Nathan R.
2014-01-01
Monte Carlo Tree Search (MCTS) has improved the performance of game engines in domains such as Go, Hex, and general game playing. MCTS has been shown to outperform classic αβ search in games where good heuristic evaluations are difficult to obtain. In recent years, combining ideas from traditional m
An O(loglog n)-Competitive Binary Search Tree with Optimal Worst-Case Access Times
Bose, Prosenjit; Dujmovic, Vida; Fagerberg, Rolf
2010-01-01
We present the zipper tree, an $O(\\log \\log n)$-competitive online binary search tree that performs each access in $O(\\log n)$ worst-case time. This shows that for binary search trees, optimal worst-case access time and near-optimal amortized access time can be guaranteed simultaneously.
Two-level Tiled Quad-tree Index for Real-time Terrain Rendering%实时地形绘制的两级瓦片四叉树索引
Institute of Scientific and Technical Information of China (English)
陆筱霞; 李思昆
2012-01-01
To satisfy the massive data management and real-time requirement in terrain scene rendering, a two-level Tiled Quad-Tree index was proposed. Firstly, terrain data were subdivided as many primary square grid, and then Tiled Quad-Trees were built on each primary patches. Index was made on these divided blocks. Based on the index, a bottom-up viewpoint diffused algorithm for rendering data retrieval was designed. Experiments and analysis show that the index can decrease storage of auxiliary information, and the retrieval efficiency for rendering is improved.%针对地形场景绘制的海量数据管理和实时性要求，提出一种两级瓦片四又树索引方法：首先将地形数据在水平面上进行初级方格副分，然后在每介初级方格面片上构建瓦片四叉树，分块数据被两级索引唯一标识。以此为基础，设计了自底向上的视点扩散绘制数据检索算法。实验结果表明，该索引能够大幅度减少辅助信息存储，并提高绘制检索的速度。
Dropout Rates and Response Times of an Occupation Search Tree in a Web Survey
Directory of Open Access Journals (Sweden)
Tijdens Kea
2014-03-01
Full Text Available Occupation is key in socioeconomic research. As in other survey modes, most web surveys use an open-ended question for occupation, though the absence of interviewers elicits unidentifiable or aggregated responses. Unlike other modes, web surveys can use a search tree with an occupation database. They are hardly ever used, but this may change due to technical advancements. This article evaluates a three-step search tree with 1,700 occupational titles, used in the 2010 multilingual WageIndicator web survey for UK, Belgium and Netherlands (22,990 observations. Dropout rates are high; in Step 1 due to unemployed respondents judging the question not to be adequate, and in Step 3 due to search tree item length. Median response times are substantial due to search tree item length, dropout in the next step and invalid occupations ticked. Overall the validity of the occupation data is rather good, 1.7-7.5% of the respondents completing the search tree have ticked an invalid occupation.
Research on the adaptive hybrid search tree anti-collision algorithm in RFID system
Institute of Scientific and Technical Information of China (English)
靳晓芳
2016-01-01
Due to more tag-collisions result in failed transmissions, tag anti-collision is a very vital issue in the radio frequency identification ( RFID) system.However, so far decreases in communication time and increases in throughput are very limited.In order to solve these problems, this paper presents a novel tag anti-collision scheme, namely adaptive hybrid search tree ( AHST) , by combining two al-gorithms of the adaptive binary-tree disassembly ( ABD) and the combination query tree ( CQT) , in which ABD has superior tag identification velocity and CQT has optimum performance in system throughput and search timeslots.From the theoretical analysis and numerical simulations, the pro-posed algorithm can colligate the advantages of above algorithms, improve the system throughput and reduce the searching timeslots dramatically.
Goloboff, Pablo A
2014-10-01
Three different types of data sets, for which the uniquely most parsimonious tree can be known exactly but is hard to find with heuristic tree search methods, are studied. Tree searches are complicated more by the shape of the tree landscape (i.e. the distribution of homoplasy on different trees) than by the sheer abundance of homoplasy or character conflict. Data sets of Type 1 are those constructed by Radel et al. (2013). Data sets of Type 2 present a very rugged landscape, with narrow peaks and valleys, but relatively low amounts of homoplasy. For such a tree landscape, subjecting the trees to TBR and saving suboptimal trees produces much better results when the sequence of clipping for the tree branches is randomized instead of fixed. An unexpected finding for data sets of Types 1 and 2 is that starting a search from a random tree instead of a random addition sequence Wagner tree may increase the probability that the search finds the most parsimonious tree; a small artificial example where these probabilities can be calculated exactly is presented. Data sets of Type 3, the most difficult data sets studied here, comprise only congruent characters, and a single island with only one most parsimonious tree. Even if there is a single island, missing entries create a very flat landscape which is difficult to traverse with tree search algorithms because the number of equally parsimonious trees that need to be saved and swapped to effectively move around the plateaus is too large. Minor modifications of the parameters of tree drifting, ratchet, and sectorial searches allow travelling around these plateaus much more efficiently than saving and swapping large numbers of equally parsimonious trees with TBR. For these data sets, two new related criteria for selecting taxon addition sequences in Wagner trees (the "selected" and "informative" addition sequences) produce much better results than the standard random or closest addition sequences. These new methods for Wagner
Dimitrakakis, Christos
2009-01-01
There has been a lot of recent work on Bayesian methods for reinforcement learning exhibiting near-optimal online performance. The main obstacle facing such methods is that in most problems of interest, the optimal solution involves planning in an infinitely large tree. However, it is possible to obtain stochastic lower and upper bounds on the value of each tree node. This enables us to use stochastic branch and bound algorithms to search the tree efficiently. This paper proposes two such algorithms and examines their complexity in this setting.
Directory of Open Access Journals (Sweden)
Alexander Safatli
2015-06-01
Full Text Available Summary. Pylogeny is a cross-platform library for the Python programming language that provides an object-oriented application programming interface for phylogenetic heuristic searches. Its primary function is to permit both heuristic search and analysis of the phylogenetic tree search space, as well as to enable the design of novel algorithms to search this space. To this end, the framework supports the structural manipulation of phylogenetic trees, in particular using rearrangement operators such as NNI, SPR, and TBR, the scoring of trees using parsimony and likelihood methods, the construction of a tree search space graph, and the programmatic execution of a few existing heuristic programs. The library supports a range of common phylogenetic file formats and can be used for both nucleotide and protein data. Furthermore, it is also capable of supporting GPU likelihood calculation on nucleotide character data through the BEAGLE library.Availability. Existing development and source code is available for contribution and for download by the public from GitHub (http://github.com/AlexSafatli/Pylogeny. A stable release of this framework is available for download through PyPi (Python Package Index at http://pypi.python.org/pypi/pylogeny.
Directory of Open Access Journals (Sweden)
Jian Yang
2016-09-01
Full Text Available In this article, a tree search algorithm is proposed to find the near optimal conflict avoidance solutions for unmanned aerial vehicles. In the dynamic environment, the unmodeled elements, such as wind, would make UAVs deviate from nominal traces. It brings about difficulties for conflict detection and resolution. The back propagation neural networks are utilized to approximate the unmodeled dynamics of the environment. To satisfy the online planning requirement, the search length of the tree search algorithm would be limited. Therefore, the algorithm may not be able to reach the goal states in search process. The midterm reward function for assessing each node is devised, with consideration given to two factors, namely, the safe separation requirement and the mission of each unmanned aerial vehicle. The simulation examples and the comparisons with previous approaches are provided to illustrate the smooth and convincing behaviours of the proposed algorithm.
B-tree search reinforcement learning for model based intelligent agent
Bhuvaneswari, S.; Vignashwaran, R.
2013-03-01
Agents trained by learning techniques provide a powerful approximation of active solutions for naive approaches. In this study using B - Trees implying reinforced learning the data search for information retrieval is moderated to achieve accuracy with minimum search time. The impact of variables and tactics applied in training are determined using reinforcement learning. Agents based on these techniques perform satisfactory baseline and act as finite agents based on the predetermined model against competitors from the course.
A gamma dose distribution evaluation technique using the k-d tree for nearest neighbor searching.
Yuan, Jiankui; Chen, Weimin
2010-09-01
The authors propose an algorithm based on the k-d tree for nearest neighbor searching to improve the gamma calculation time for 2D and 3D dose distributions. The gamma calculation method has been widely used for comparisons of dose distributions in clinical treatment plans and quality assurances. By specifying the acceptable dose and distance-to-agreement criteria, the method provides quantitative measurement of the agreement between the reference and evaluation dose distributions. The gamma value indicates the acceptability. In regions where gamma nearest neighbor can be an O (log N) operation with a k-d tree, where N is the total number of the dose points, the authors propose an algorithm based on the k-d tree for the gamma evaluation in this work. In the experiment, the authors found that the average k-d tree construction time per reference point is O (log N), while the nearest neighbor searching time per evaluation point is proportional to O (N(1/k), where k is between 2 and 3 for two-dimensional and three-dimensional dose distributions, respectively. Comparing with other algorithms such as exhaustive search and sorted list O (N), the k-d tree algorithm for gamma evaluation is much more efficient.
Enhancements for Monte-Carlo Tree Search in Ms Pac-Man
Pepels, Tom; Winands, Mark H M
2012-01-01
In this paper enhancements for the Monte-Carlo Tree Search (MCTS) framework are investigated to play Ms Pac-Man. MCTS is used to find an optimal path for an agent at each turn, determining the move to make based on randomised simulations. Ms Pac-Man is a real-time arcade game, in which the protagoni
A γ dose distribution evaluation technique using the k-d tree for nearest neighbor searching.
Yuan, Jiankui; Chen, Weimin
2010-09-01
The authors propose an algorithm based on the k-d tree for nearest neighbor searching to improve theγ calculation time for 2D and 3D dose distributions. Theγ calculation method has been widely used for comparisons of dose distributions in clinical treatment plans and quality assurances. By specifying the acceptable dose and distance-to-agreement criteria, the method provides quantitative measurement of the agreement between the reference and evaluation dose distributions. The γ value indicates the acceptability. In regions where γ≤1, the predefined criterion is satisfied and thus the agreement is acceptable; otherwise, the agreement fails. Although the concept of the method is not complicated and a quick naïve implementation is straightforward, an efficient and robust implementation is not trivial. Recent algorithms based on exhaustive searching within a maximum radius, the geometric Euclidean distance, and the table lookup method have been proposed to improve the computational time for multidimensional dose distributions. Motivated by the fact that the least searching time for finding a nearest neighbor can be an O(logN) operation with a k-d tree, where N is the total number of the dose points, the authors propose an algorithm based on the k-d tree for the γ evaluation in this work. In the experiment, the authors found that the average k-d tree construction time per reference point isO(logN), while the nearest neighbor searching time per evaluation point is proportional to O(N1/k), where k is between 2 and 3 for two-dimensional and three-dimensional dose distributions, respectively. Comparing with other algorithms such as exhaustive search and sorted listO(N), the k-d tree algorithm for γ evaluation is much more efficient. © 2010 American Association of Physicists in Medicine.
A best-first tree-searching approach for ML decoding in MIMO system
Shen, Chung-An
2012-07-28
In MIMO communication systems maximum-likelihood (ML) decoding can be formulated as a tree-searching problem. This paper presents a tree-searching approach that combines the features of classical depth-first and breadth-first approaches to achieve close to ML performance while minimizing the number of visited nodes. A detailed outline of the algorithm is given, including the required storage. The effects of storage size on BER performance and complexity in terms of search space are also studied. Our result demonstrates that with a proper choice of storage size the proposed method visits 40% fewer nodes than a sphere decoding algorithm at signal to noise ratio (SNR) = 20dB and by an order of magnitude at 0 dB SNR.
D Nearest Neighbour Search Using a Clustered Hierarchical Tree Structure
Suhaibah, A.; Uznir, U.; Anton, F.; Mioc, D.; Rahman, A. A.
2016-06-01
Locating and analysing the location of new stores or outlets is one of the common issues facing retailers and franchisers. This is due to assure that new opening stores are at their strategic location to attract the highest possible number of customers. Spatial information is used to manage, maintain and analyse these store locations. However, since the business of franchising and chain stores in urban areas runs within high rise multi-level buildings, a three-dimensional (3D) method is prominently required in order to locate and identify the surrounding information such as at which level of the franchise unit will be located or is the franchise unit located is at the best level for visibility purposes. One of the common used analyses used for retrieving the surrounding information is Nearest Neighbour (NN) analysis. It uses a point location and identifies the surrounding neighbours. However, with the immense number of urban datasets, the retrieval and analysis of nearest neighbour information and their efficiency will become more complex and crucial. In this paper, we present a technique to retrieve nearest neighbour information in 3D space using a clustered hierarchical tree structure. Based on our findings, the proposed approach substantially showed an improvement of response time analysis compared to existing approaches of spatial access methods in databases. The query performance was tested using a dataset consisting of 500,000 point locations building and franchising unit. The results are presented in this paper. Another advantage of this structure is that it also offers a minimal overlap and coverage among nodes which can reduce repetitive data entry.
Monte-Carlo Tree Search for the “Mr Jack” Board Game
Mazyad, Ahmad; Teytaud, Fabien; Fonlupt, Cyril
2015-01-01
International audience; Recently the use of the Monte-Carlo Tree Search algorithm, and inparticular its most famous implementation, the Upper Confidence Tree can beseen has a key moment for artificial intelligence in games. This family of algorithmsprovides huge improvements in numerous games, such as Go, Havannah,Hex or Amazon. In this paper we study the use of this algorithm on the game ofMr Jack and in particular how to deal with a specific decision-making process.Mr Jack is a 2-player gam...
How tree shrews (Tupaia belangeri) perform in a searching task: evidence for strategy use.
Bartolomucci, A; de Biurrun, G; Fuchs, E
2001-12-01
This study investigated how male tree shrews (Tupaia belangen) performed in a searching task while in their home cages and assessed whether different food distributions affected their performance. The animals were faced with a holeboard containing 9 food sources arranged in a 3 x 3 matrix or in 3 clusters, each containing 3 sources. Animals tended to start and end the trials from preferred locations, thereafter solving the task by strategically organizing the reward collection according to a minimum-distance principle. In the cluster configuration, they visited the sources hierarchically. Food distribution did not affect the performance. Comparison with data from mice and capuchin monkeys revealed that tree shrews and capuchins solved the task in a similar strategic way, whereas mice did not. These findings attract particular attention because of the phylogenetic position of tree shrews, which are regarded as closely related to primates.
Energy Technology Data Exchange (ETDEWEB)
Karpinski, M. [Univ. of Bonn (Germany); Larmore, L.L. [Univ. of Nevada, Las Vegas, NV (United States); Rytter, W. [Warsaw Univ. (Poland)
1996-12-31
A sublinear time subquadratic work parallel algorithm for construction of an optimal binary search tree, in a special case of practical interest, namely where the frequencies of items to be stored are not too small, is given. A sublinear time subquadratic work parallel algorithm for construction of an approximately optimal binary search tree in the general case is also given. Sub-quadratic work and sublinear time are achieved using a fast parallel algorithm for the column minima problem for Monge matrices developed by Atallah and Kosaraju. The algorithms given in this paper take O(n{sup 0.6}) time with n processors in the CREW PRAM model. Our 29orithms work well if every subtree of the optimal binary search tree of depth {Omega}(log n) has o(n) leaves. We prove that there is a sequential algorithm with subquadratic average-case complexity, by demonstrating that the {open_quotes}small subtree{close_quotes} condition holds with very high probability for a randomly permuted weight sequence. This solves the conjecture posed in liand breaks the quadratic time {open_quotes}barrier{close_quotes} of Knuth`s algorithm. This algorithm can also be parallelized to run in average sublinear time with n processors.
Angle Tree: Nearest Neighbor Search in High Dimensions with Low Intrinsic Dimensionality
Zvedeniouk, Ilia
2010-01-01
We propose an extension of tree-based space-partitioning indexing structures for data with low intrinsic dimensionality embedded in a high dimensional space. We call this extension an Angle Tree. Our extension can be applied to both classical kd-trees as well as the more recent rp-trees. The key idea of our approach is to store the angle (the "dihedral angle") between the data region (which is a low dimensional manifold) and the random hyperplane that splits the region (the "splitter"). We show that the dihedral angle can be used to obtain a tight lower bound on the distance between the query point and any point on the opposite side of the splitter. This in turn can be used to efficiently prune the search space. We introduce a novel randomized strategy to efficiently calculate the dihedral angle with a high degree of accuracy. Experiments and analysis on real and synthetic data sets shows that the Angle Tree is the most efficient known indexing structure for nearest neighbor queries in terms of preprocessing ...
National Research Council Canada - National Science Library
Liu, XiangShao; Zhou, Shangbo; Li, Hua; Li, Kun
2016-01-01
In this article, a bidirectional feature matching algorithm and two extended algorithms based on the priority k-d tree search are presented for the image registration using scale-invariant feature transform features...
A fast recursive coordinate bisection tree for neighbour search and gravity
Gafton, Emanuel
2011-01-01
We introduce our new binary tree code for neighbour search and gravitational force calculations in an N-particle system. The tree is built in a "top-down" fashion by "recursive coordinate bisection" where on each tree level we split the longest side of a cell through its centre of mass. This procedure continues until the average number of particles in the lowest tree level has dropped below a prescribed value. To calculate the forces on the particles in each lowest-level cell we split the gravitational interaction into a near- and a far-field. Since our main intended applications are SPH simulations, we calculate the near-field by a direct, kernel-smoothed summation, while the far field is evaluated via a Cartesian Taylor expansion up to quadrupole order. Instead of applying the far-field approach for each particle separately, we use another Taylor expansion around the centre of mass of each lowest-level cell to determine the forces at the particle positions. Due to this "cell-cell interaction" the code perfo...
TOPOLOGY EXTRACTION USING DEPTH FIRST SEARCH ON VOXEL REPRESENTATIONS OF TREE POINT CLOUDS
Directory of Open Access Journals (Sweden)
A. Schilling
2012-09-01
Full Text Available The three-dimensional reconstruction of the vegetation structure is a requirement for the analysis of interaction between biosphere and atmosphere. Information about the 3D structure of plants enables the modeling of crucial processes, like water interception or absorption of light. Terrestrial laser scanners have proven to be a valuable tool to rapidly and accurately capture the geometry of plants as point clouds, which provide the foundation for analyzing their structure. Based on a very dense but unstructured, noisy point cloud, we have presented a method to extract the topology of a tree in form of a tree graph, demonstrated on a test set of single birches. In a first step we have applied a variation of the Circular Hough Transform to detect a set of 3D points, which represent the tree trunk. Subsequently, the point cloud is transformed onto a voxel space and filtered to a connected component representation of only the main object. In the second step, the residual voxels are interpreted as a connected graph and the Depth First Search algorithm is employed to retrieve the topology of the scanned tree.
Fast Tree Search for A Triangular Lattice Model of Protein Folding
Institute of Scientific and Technical Information of China (English)
Xiaomei Li; Nengchao Wang
2004-01-01
Using a triangular lattice model to study the designability of protein folding, we overcame the parity problem of previous cubic lattice model and enumerated all the sequences and compact structures on a simple two-dimensional triangular lattice model of size 4+5+6+5+4. We used two types of amino acids, hydrophobic and polar, to make up the sequences, and achieved 223+212 different sequences excluding the reverse symmetry sequences. The total string number of distinct compact structures was 219,093, excluding reflection symmetry in the self-avoiding path of length 24 triangular lattice model. Based on this model, we applied a fast search algorithm by constructing a cluster tree. The algorithm decreased the computation by computing the objective energy of non-leaf nodes. The parallel experiments proved that the fast tree search algorithm yielded an exponential speed-up in the model of size 4+5+6+5+4. Designability analysis was performed to understand the search result.
Monte-Carlo tree search method for the board game Scotland Yard
BELEJ, NEŽA
2015-01-01
In the thesis we learn about the field of artificial intelligence that investigates board games and their program-based solutions. We examine Monte-Carlo tree search algorithm and transfer it to well-known board game Scotland Yard, considering advices from Nijssen and Winands. We focus mainly on the third phase of the algorithm, playout, and decide to implement it in three different ways (from less to more advanced techniques). We compare these three aproaches. We compare the win rates and co...
A method of characterizing network topology based on the breadth-first search tree
Zhou, Bin; He, Zhe; Wang, Nianxin; Wang, Bing-Hong
2016-05-01
A method based on the breadth-first search tree is proposed in this paper to characterize the hierarchical structure of network. In this method, a similarity coefficient is defined to quantitatively distinguish networks, and quantitatively measure the topology stability of the network generated by a model. The applications of the method are discussed in ER random network, WS small-world network and BA scale-free network. The method will be helpful for deeply describing network topology and provide a starting point for researching the topology similarity and isomorphism of networks.
Learning is planning: near Bayes-optimal reinforcement learning via Monte-Carlo tree search
Asmuth, John
2012-01-01
Bayes-optimal behavior, while well-defined, is often difficult to achieve. Recent advances in the use of Monte-Carlo tree search (MCTS) have shown that it is possible to act near-optimally in Markov Decision Processes (MDPs) with very large or infinite state spaces. Bayes-optimal behavior in an unknown MDP is equivalent to optimal behavior in the known belief-space MDP, although the size of this belief-space MDP grows exponentially with the amount of history retained, and is potentially infinite. We show how an agent can use one particular MCTS algorithm, Forward Search Sparse Sampling (FSSS), in an efficient way to act nearly Bayes-optimally for all but a polynomial number of steps, assuming that FSSS can be used to act efficiently in any possible underlying MDP.
Taillandier, Patrick; Drogoul, Alexis
2012-01-01
Many real world problems can be expressed as optimisation problems. Solving this kind of problems means to find, among all possible solutions, the one that maximises an evaluation function. One approach to solve this kind of problem is to use an informed search strategy. The principle of this kind of strategy is to use problem-specific knowledge beyond the definition of the problem itself to find solutions more efficiently than with an uninformed strategy. This kind of strategy demands to define problem-specific knowledge (heuristics). The efficiency and the effectiveness of systems based on it directly depend on the used knowledge quality. Unfortunately, acquiring and maintaining such knowledge can be fastidious. The objective of the work presented in this paper is to propose an automatic knowledge revision approach for systems based on an informed tree search strategy. Our approach consists in analysing the system execution logs and revising knowledge based on these logs by modelling the revision problem as...
Tree and Hashing Data Structures to Speed up Chemical Searches: Analysis and Experiments.
Nasr, Ramzi; Kristensen, Thomas; Baldi, Pierre
2011-09-01
In many large chemoinformatics database systems, molecules are represented by long binary fingerprint vectors whose components record the presence or absence of particular functional groups or combinatorial features. For a given query molecule, one is interested in retrieving all the molecules in the database with a similarity to the query above a certain threshold. Here we describe a method for speeding up chemical searches in these large databases of small molecules by combining previously developed tree and hashing data structures to prune the search space without any false negatives. More importantly, we provide a mathematical analysis that allows one to predict the level of pruning, and validate the quality of the predictions of the method through simulation experiments.
Zip：An Algorithm Based on Loser Tree for Common Contacts Searching in Large Graphs
Institute of Scientific and Technical Information of China (English)
唐宏; 牟帅; 黄晋; 朱佳; 陈健; 丁蕊
2015-01-01
The problem of k-hop reachability between two vertices in a graph has received considerable attention in recent years. A substantial number of algorithms have been proposed with the goal of improving the searching eﬃciency of the k-hop reachability between two vertices in a graph. However, searching and traversing are challenging tasks, especially in large-scale graphs. Furthermore, the existing algorithms propounded by different scholars are not satisfactory in terms of feasibility and scalability when applied to different kinds of graphs. In this work, we propose a new algorithm, called Zip, in an attempt to eﬃciently determine the common contacts between any two random vertices in a large-scale graph. First, we describe a novel algorithm for constructing the graph index via binary searching which maintains the adjacent list of each vertex in order. Second, we present the ways to achieve a sequential k-hop contact set by using the loser tree, a merge sorting algorithm. Finally, we develop an eﬃcient algorithm for querying common contacts and an optimized strategy for k-hop contact set serialization. Experimental results on synthetic and real datasets show that the proposed Zip algorithm outperforms existing state-of-the-art algorithms (e.g., breadth-first searching, GRAIL, the graph stratification algorithm).
Incremental road discovery from aerial imagery using curvilinear spanning tree (CST) search
Wang, Guozhi; Huang, Yuchun; Xie, Rongchang; Zhang, Hongchang
2016-10-01
Robust detection of road network in aerial imagery is a challenging task since roads have different pavement texture, road-side surroundings, as well as grades. Roads of different grade have different curvilinear saliency in the aerial imagery. This paper is motivated to incrementally extract roads and construct the topology of the road network of aerial imagery from the higher-grade-first perspective. Inspired by the spanning tree technique, the proposed method starts from the robust extraction of the most salient road segment(s) of the road network, and incrementally connects segments of less saliency of curvilinear structure until all road segments in the network are extracted. The proposed algorithm includes: curvilinear path-based road morphological enhancement, extraction of road segments, and spanning tree search for the incremental road discovery. It is tested on a diverse set of aerial imagery acquired in the city and inter-city areas. Experimental results show that the proposed curvilinear spanning tree (CST) can detect roads efficiently and construct the topology of the road network effectively. It is promising for the change detection of the road network.
Al-Khaja, Nawal
2007-01-01
This is a thematic lesson plan for young learners about palm trees and the importance of taking care of them. The two part lesson teaches listening, reading and speaking skills. The lesson includes parts of a tree; the modal auxiliary, can; dialogues and a role play activity.
Loss Reduction in Heavy Loaded Distribution Networks Using Cyclic Sub Tree Search
Energy Technology Data Exchange (ETDEWEB)
Choi, Sang-Yule; Shin, Myong-Chul [Sungkyunkwan University, Seoul (Korea)
2001-05-01
Network reconfiguration in distribution systems is realized by changing the status of sectionalizing switches, and is usually done for loss reduction or load balancing in the system. This paper presents an effective heuristic based switching scheme to solve the distribution feeder loss reduction problem. The proposed algorithm consists of two parts. One is to set up a decision tree to represent the various switching operations available. Another is to apply a proposed technique called cyclic best first search, the proposed algorithm identify the most effective the set of switch status configuration of distribution system for loss reduction. To demonstrate the validity of the proposed algorithm, numerical calculations are carried out the 32, 69 bus system models (author). 17 refs., 10 figs., 2 tabs.
Institute of Scientific and Technical Information of China (English)
加力; 陆鑫达; 张健
2002-01-01
The real problem in cluster of workstations is the changes in workstation power or number of workstations or dynmaic changes in the run-time behavior of the application hamper the efficient use of resources. Dynamic load balancing is a technique for the parallel implementation of problems, which generate unpredictable workloads by migration work units from heavily loaded processor to lightly loaded processors at run-time. This paper proposed an efficient load balancing method in which parallel tree computations depth-first-search (DFS) generates unpredictable, highly imbalance workloads and moves through different phases detectable at run-time, where dynamic load balancing strategy is applicable in each phase running under the MPI(message passing interface) and Unix operating system on cluster of workstations parallel platform computing.
Optimal processing for gel electrophoresis images: Applying Monte Carlo Tree Search in GelApp.
Nguyen, Phi-Vu; Ghezal, Ali; Hsueh, Ya-Chih; Boudier, Thomas; Gan, Samuel Ken-En; Lee, Hwee Kuan
2016-08-01
In biomedical research, gel band size estimation in electrophoresis analysis is a routine process. To facilitate and automate this process, numerous software have been released, notably the GelApp mobile app. However, the band detection accuracy is limited due to a band detection algorithm that cannot adapt to the variations in input images. To address this, we used the Monte Carlo Tree Search with Upper Confidence Bound (MCTS-UCB) method to efficiently search for optimal image processing pipelines for the band detection task, thereby improving the segmentation algorithm. Incorporating this into GelApp, we report a significant enhancement of gel band detection accuracy by 55.9 ± 2.0% for protein polyacrylamide gels, and 35.9 ± 2.5% for DNA SYBR green agarose gels. This implementation is a proof-of-concept in demonstrating MCTS-UCB as a strategy to optimize general image segmentation. The improved version of GelApp-GelApp 2.0-is freely available on both Google Play Store (for Android platform), and Apple App Store (for iOS platform). © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Tree breeding for pest resistance for the next 50 years: the search for cross resistance?
Alvin D. Yanchuk
2012-01-01
Research activities aimed at developing resistance to pests (insect, pathogens, mammals) in forest trees can be documented back over 5 decades. While a substantial body of research has been published on resistances in forest trees, not much of this work has made its way into applied tree improvement programs. There are several reasons for this, e.g.: (i) a new...
Henri Epstein
2016-01-01
An algebraic formalism, developed with V. Glaser and R. Stora for the study of the generalized retarded functions of quantum field theory, is used to prove a factorization theorem which provides a complete description of the generalized retarded functions associated with any tree graph. Integrating over the variables associated to internal vertices to obtain the perturbative generalized retarded functions for interacting fields arising from such graphs is shown to be possible for a large cate...
Epstein, Henri
2016-01-01
An algebraic formalism, developped with V. Glaser and R. Stora for the study of the generalized retarded functions of quantum field theory, is used to prove a factorization theorem which provides a complete description of the generalized retarded functions associated with any tree graph. Integrating over the variables associated to internal vertices to obtain the perturbative generalized retarded functions for interacting fields arising from such graphs is shown to be possible for a large cat...
Epstein, Henri
2016-01-01
An algebraic formalism, developped with V.~Glaser and R.~Stora for the study of the generalized retarded functions of quantum field theory, is used to prove a factorization theorem which provides a complete description of the generalized retarded functions associated with any tree graph. Integrating over the variables associated to internal vertices to obtain the perturbative generalized retarded functions for interacting fields arising from such graphs is shown to be possible for a large category of space-times.
Huang, Wei Tao; Luo, Hong Qun; Li, Nian Bing
2014-05-06
The most serious, and yet unsolved, problem of constructing molecular computing devices consists in connecting all of these molecular events into a usable device. This report demonstrates the use of Boolean logic tree for analyzing the chemical event network based on graphene, organic dye, thrombin aptamer, and Fenton reaction, organizing and connecting these basic chemical events. And this chemical event network can be utilized to implement fluorescent combinatorial logic (including basic logic gates and complex integrated logic circuits) and fuzzy logic computing. On the basis of the Boolean logic tree analysis and logic computing, these basic chemical events can be considered as programmable "words" and chemical interactions as "syntax" logic rules to construct molecular search engine for performing intelligent molecular search query. Our approach is helpful in developing the advanced logic program based on molecules for application in biosensing, nanotechnology, and drug delivery.
Smoly, Ilan; Carmel, Amir; Shemer-Avni, Yonat; Yeger-Lotem, Esti; Ziv-Ukelson, Michal
2016-03-01
Network querying is a powerful approach to mine molecular interaction networks. Most state-of-the-art network querying tools either confine the search to a prespecified topology in the form of some template subnetwork, or do not specify any topological constraints at all. Another approach is grammar-based queries, which are more flexible and expressive as they allow for expressing the topology of the sought pattern according to some grammar-based logic. Previous grammar-based network querying tools were confined to the identification of paths. In this article, we extend the patterns identified by grammar-based query approaches from paths to trees. For this, we adopt a higher order query descriptor in the form of a regular tree grammar (RTG). We introduce a novel problem and propose an algorithm to search a given graph for the k highest scoring subgraphs matching a tree accepted by an RTG. Our algorithm is based on the combination of dynamic programming with color coding, and includes an extension of previous k-best parsing optimization approaches to avoid isomorphic trees in the output. We implement the new algorithm and exemplify its application to mining viral infection patterns within molecular interaction networks. Our code is available online.
Ruczyński, Ireneusz; Bartoń, Kamil A
2012-01-01
Sensory limitation plays an important role in the evolution of animal behaviour. Animals have to find objects of interest (e.g. food, shelters, predators). When sensory abilities are strongly limited, animals adjust their behaviour to maximize chances for success. Bats are nocturnal, live in complex environments, are capable of flight and must confront numerous perceptual challenges (e.g. limited sensory range, interfering clutter echoes). This makes them an excellent model for studying the role of compensating behaviours to decrease costs of finding resources. Cavity roosting bats are especially interesting because the availability of tree cavities is often limited, and their quality is vital for bats during the breeding season. From a bat's sensory point of view, cavities are difficult to detect and finding them requires time and energy. However, tree cavities are also long lasting, allowing information transfer among conspecifics. Here, we use a simple simulation model to explore the benefits of tree selection, memory and eavesdropping (compensation behaviours) to searches for tree cavities by bats with short and long perception range. Our model suggests that memory and correct discrimination of tree suitability are the basic strategies decreasing the cost of roost finding, whereas perceptual range plays a minor role in this process. Additionally, eavesdropping constitutes a buffer that reduces the costs of finding new resources (such as roosts), especially when they occur in low density. We conclude that natural selection may promote different strategies of roost finding in relation to habitat conditions and cognitive skills of animals.
Directory of Open Access Journals (Sweden)
Ireneusz Ruczyński
Full Text Available Sensory limitation plays an important role in the evolution of animal behaviour. Animals have to find objects of interest (e.g. food, shelters, predators. When sensory abilities are strongly limited, animals adjust their behaviour to maximize chances for success. Bats are nocturnal, live in complex environments, are capable of flight and must confront numerous perceptual challenges (e.g. limited sensory range, interfering clutter echoes. This makes them an excellent model for studying the role of compensating behaviours to decrease costs of finding resources. Cavity roosting bats are especially interesting because the availability of tree cavities is often limited, and their quality is vital for bats during the breeding season. From a bat's sensory point of view, cavities are difficult to detect and finding them requires time and energy. However, tree cavities are also long lasting, allowing information transfer among conspecifics. Here, we use a simple simulation model to explore the benefits of tree selection, memory and eavesdropping (compensation behaviours to searches for tree cavities by bats with short and long perception range. Our model suggests that memory and correct discrimination of tree suitability are the basic strategies decreasing the cost of roost finding, whereas perceptual range plays a minor role in this process. Additionally, eavesdropping constitutes a buffer that reduces the costs of finding new resources (such as roosts, especially when they occur in low density. We conclude that natural selection may promote different strategies of roost finding in relation to habitat conditions and cognitive skills of animals.
Resource Search in Unstructured Peer-to-Peer System Based on Multiple-Tree Overlay Structure
Institute of Scientific and Technical Information of China (English)
YU Jianqiao; LIAO Jianwei
2007-01-01
We propose a multiple-tree overlay structure for resource discovery in unstructured P2P systems. Peers that have similar interests or hold similar type of resources will be grouped into a tree-like cluster. We exploit the heterogeneity of peers in each cluster by connecting peers with more capacities closer to the root of the tree. The capacity of a peer can be defined in different ways (e.g. higher network bandwidth, larger disk space, more data items of a certain type etc.) according to different needs of users or applications.
Two-level cervical disc replacement: perspectives and patient selection
Directory of Open Access Journals (Sweden)
Narain AS
2017-02-01
Full Text Available Ankur S Narain, Fady Y Hijji, Daniel D Bohl, Kelly H Yom, Krishna T Kudaravalli, Kern Singh Department of Orthopedic Surgery, Rush University Medical Center, Chicago, IL, USA Introduction: Cervical disc replacement (CDR is an emerging treatment option for cervical degenerative disease. Postulated benefits of cervical disc replacement compared to anterior cervical discectomy and fusion include preserved motion at the operative segments and decreased motion at adjacent levels. Multiple studies have been performed investigating the outcomes of CDR in single-level pathology. The investigation of the use of CDR in two-level pathology is an emerging topic within the literature.Purpose: To critically evaluate the literature regarding two-level CDR in order to determine its utility compared to two-level cervical arthrodesis. Patient selection factors including indications and contraindications will also be explored.Methods: The PubMed database was searched for all articles published on the subject of two-level CDR up until October 2016. Studies were classified by publication year, study design, sample size, follow-up interval, and conflict of interest. Outcomes were recorded from each study, and included data on patient-reported outcomes, radiographic measurements, range of motion, peri- and postoperative complications, heterotopic ossification, adjacent segment disease, reoperation rate, and total intervention cost. Results: Fourteen studies were included in this review. All studies demonstrated at least noninferiority of two-level CDR compared to both two-level arthrodesis and single-level CDR. Patient selection in two-level CDR is driven by the inclusion and exclusion criteria presented in prospective, randomized controlled trials. The most common indication is subaxial degenerative disc disease over two contiguous levels presenting with radiculopathy or myelopathy. Furthermore, costs analyses trended toward at least noninferiority of two-level
Dimitrakakis, C.; Filipe, J.; Fred, A.; Sharp, B.
2010-01-01
There has been a lot of recent work on Bayesian methods for reinforcement learning exhibiting near-optimal online performance. The main obstacle facing such methods is that in most problems of interest, the optimal solution involves planning in an infinitely large tree. However, it is possible to ob
Complexity of stochastic branch and bound for belief tree search in Bayesian reinforcement learning
Dimitrakakis, C.
2009-01-01
There has been a lot of recent work on Bayesian methods for reinforcement learning exhibiting near-optimal online performance. The main obstacle facing such methods is that in most problems of interest, the optimal solution involves planning in an infinitely large tree. However, it is possible to ob
A Distributed Election and Spanning Tree Algorithm Based on Depth First Search Traversals
DEFF Research Database (Denmark)
Skyum, Sven
The existence of an effective distributed traversal algorithm for a class of graphs has proven useful in connection with election problems for those classes. In this paper we show how a general traversal algorithm, such as depth first search, can be turned into an effective election algorithm using...
Patrut, Adrian; von Reden, Karl F; Danthu, Pascal; Pock-Tsy, Jean-Michel Leong; Patrut, Roxana T; Lowy, Daniel A
2015-01-01
We extended our research on the architecture, growth and age of trees belonging to the genus Adansonia, by starting to investigate large individuals of the most widespread Malagasy species. Our research also intends to identify the oldest baobabs of Madagascar. Here we present results of the radiocarbon investigation of the two most representative Adansonia rubrostipa (fony baobab) specimens, which are located in south-western Madagascar, in the Tsimanampetsotse National Park. We found that the fony baobab called "Grandmother" consists of 3 perfectly fused stems of different ages. The radiocarbon date of the oldest sample was found to be 1136 ± 16 BP. We estimated that the oldest part of this tree, which is mainly hollow, has an age close to 1,600 yr. This value is comparable to the age of the oldest Adansonia digitata (African baobab) specimens. By its age, the Grandmother is a major candidate for the oldest baobab of Madagascar. The second investigated specimen, called the "polygamous baobab", consists of 6 partially fused stems of different ages. According to dating results, this fony baobab is 1,000 yr old. This research is the first investigation of the structure and age of Malagasy baobabs.
Directory of Open Access Journals (Sweden)
Adrian Patrut
Full Text Available We extended our research on the architecture, growth and age of trees belonging to the genus Adansonia, by starting to investigate large individuals of the most widespread Malagasy species. Our research also intends to identify the oldest baobabs of Madagascar. Here we present results of the radiocarbon investigation of the two most representative Adansonia rubrostipa (fony baobab specimens, which are located in south-western Madagascar, in the Tsimanampetsotse National Park. We found that the fony baobab called "Grandmother" consists of 3 perfectly fused stems of different ages. The radiocarbon date of the oldest sample was found to be 1136 ± 16 BP. We estimated that the oldest part of this tree, which is mainly hollow, has an age close to 1,600 yr. This value is comparable to the age of the oldest Adansonia digitata (African baobab specimens. By its age, the Grandmother is a major candidate for the oldest baobab of Madagascar. The second investigated specimen, called the "polygamous baobab", consists of 6 partially fused stems of different ages. According to dating results, this fony baobab is 1,000 yr old. This research is the first investigation of the structure and age of Malagasy baobabs.
3D Nearest Neighbour Search Using a Clustered Hierarchical Tree Structure
DEFF Research Database (Denmark)
Suhaibah, A.; Uznir, U.; Antón Castro, Francesc/François
2016-01-01
, with the immense number of urban datasets, the retrieval and analysis of nearest neighbour information and their efficiency will become more complex and crucial. In this paper, we present a technique to retrieve nearest neighbour information in 3D space using a clustered hierarchical tree structure. Based on our...... findings, the proposed approach substantially showed an improvement of response time analysis compared to existing approaches of spatial access methods in databases. The query performance was tested using a dataset consisting of 500,000 point locations building and franchising unit. The results...... of the franchise unit will be located or is the franchise unit located is at the best level for visibility purposes. One of the common used analyses used for retrieving the surrounding information is Nearest Neighbour (NN) analysis. It uses a point location and identifies the surrounding neighbours. However...
An Adaptive Indexed Binary Search Tree for Efficient Homomorphic Coercion Resistant Voting Scheme
Directory of Open Access Journals (Sweden)
Vinodu George
2010-02-01
Full Text Available This paper presents a voting scheme that coalesces many of the advantageous features of an efficient e-votingscheme like receipt-freeness, uncoercibility and write-in ballot, without requiring untappable channels. Someof the previous schemes in the literature provide most of these features with a penalty of increased runningtime. The proposed scheme utilizes the advantages of a novel data structure known as “ Indexed binarysearch tree (IBST” for reducing the running time to linear order The self organizing nature of the datastructure ensures an efficient voting process. It also satisfies the desirable features of the existing write-in andcoercion resistant voting schemes, such as fair degree of efficiency and protection against any kind ofadversarial behavior with lowest running time.
Two-Level Semantics and Abstract Interpretation
DEFF Research Database (Denmark)
Nielson, Flemming
1989-01-01
Two-level semantics is a variant of Scott/Strachey denotational semantics in which the concept of binding time is treated explicitly. This is done by formally distinguishing between those computations that take place at run-time and those that take place at compile-time. Abstract interpretation...... unique flavour is the insistence on formal proofs of correctness and the methods used to establish these. This paper develops a theory of abstract interpretation for two-level denotational definitions. There are three ingredients in this. First a framework for proving the correctness of analyses...
Expectations of two-level telegraph noise
Fern, J
2006-01-01
We find expectation values of functions of time integrated two-level telegraph noise. Expectation values of this noise are evaluated under simple control pulses. Both the Gaussian limit and $1/f$ noise are considered. We apply the results to a specific superconducting quantum computing example, which illustrates the use of this technique for calculating error probabilities.
Directory of Open Access Journals (Sweden)
Atif Shahzad
2016-02-01
Full Text Available A promising approach for an effective shop scheduling that synergizes the benefits of the combinatorial optimization, supervised learning and discrete-event simulation is presented. Though dispatching rules are in widely used by shop scheduling practitioners, only ordinary performance rules are known; hence, dynamic generation of dispatching rules is desired to make them more effective in changing shop conditions. Meta-heuristics are able to perform quite well and carry more knowledge of the problem domain, however at the cost of prohibitive computational effort in real-time. The primary purpose of this research lies in an offline extraction of this domain knowledge using decision trees to generate simple if-then rules that subsequently act as dispatching rules for scheduling in an online manner. We used similarity index to identify parametric and structural similarity in problem instances in order to implicitly support the learning algorithm for effective rule generation and quality index for relative ranking of the dispatching decisions. Maximum lateness is used as the scheduling objective in a job shop scheduling environment.
3D NEAREST NEIGHBOUR SEARCH USING A CLUSTERED HIERARCHICAL TREE STRUCTURE
Directory of Open Access Journals (Sweden)
A. Suhaibah
2016-06-01
Full Text Available Locating and analysing the location of new stores or outlets is one of the common issues facing retailers and franchisers. This is due to assure that new opening stores are at their strategic location to attract the highest possible number of customers. Spatial information is used to manage, maintain and analyse these store locations. However, since the business of franchising and chain stores in urban areas runs within high rise multi-level buildings, a three-dimensional (3D method is prominently required in order to locate and identify the surrounding information such as at which level of the franchise unit will be located or is the franchise unit located is at the best level for visibility purposes. One of the common used analyses used for retrieving the surrounding information is Nearest Neighbour (NN analysis. It uses a point location and identifies the surrounding neighbours. However, with the immense number of urban datasets, the retrieval and analysis of nearest neighbour information and their efficiency will become more complex and crucial. In this paper, we present a technique to retrieve nearest neighbour information in 3D space using a clustered hierarchical tree structure. Based on our findings, the proposed approach substantially showed an improvement of response time analysis compared to existing approaches of spatial access methods in databases. The query performance was tested using a dataset consisting of 500,000 point locations building and franchising unit. The results are presented in this paper. Another advantage of this structure is that it also offers a minimal overlap and coverage among nodes which can reduce repetitive data entry.
Two-Level Semantics and Abstract Interpretation
DEFF Research Database (Denmark)
Nielson, Flemming
1989-01-01
Two-level semantics is a variant of Scott/Strachey denotational semantics in which the concept of binding time is treated explicitly. This is done by formally distinguishing between those computations that take place at run-time and those that take place at compile-time. Abstract interpretation...... is concerned with the (preferably automatic) analysis of programs. The main purpose of these analyses is to find information that may assist in the efficient implementation of the programs. Abstract interpretation is thus related to data flow analysis, partial evaluation and other program analysis methods. Its...... unique flavour is the insistence on formal proofs of correctness and the methods used to establish these. This paper develops a theory of abstract interpretation for two-level denotational definitions. There are three ingredients in this. First a framework for proving the correctness of analyses...
Clustering DTDs: An Interactive Two-Level Approach
Institute of Scientific and Technical Information of China (English)
周傲英; 钱卫宁; 钱海蕾; 张龙; 梁宇奇; 金文
2002-01-01
XML (eXtensible Markup Language) is a standard which is widely appliedin data representation and data exchange. However, as an important concept of XML, DTD(Document Type Definition) is not taken full advantage in current applications. In this paper, anew method for clustering DTDs is presented, and it can be used in XML document clustering.The two-level method clusters the elements in DTDs and clusters DTDs separately. Elementclustering forms the first level and provides element clusters, which are the generalization ofrelevant elements. DTD clustering utilizes the generalized information and forms the secondlevel in the whole clustering process. The two-level method has the following advantages: 1) Ittakes into consideration both the content and the structure within DTDs; 2) The generalizedinformation about elements is more useful than the separated words in the vector model; 3) Thetwo-level method facilitates the searching of outliers. The experiments show that this methodis able to categorize the relevant DTDs effectively.
Directory of Open Access Journals (Sweden)
Robin Roj
2014-07-01
Full Text Available This paper presents three different search engines for the detection of CAD-parts in large databases. The analysis of the contained information is performed by the export of the data that is stored in the structure trees of the CAD-models. A preparation program generates one XML-file for every model, which in addition to including the data of the structure tree, also owns certain physical properties of each part. The first search engine is specializes in the discovery of standard parts, like screws or washers. The second program uses certain user input as search parameters, and therefore has the ability to perform personalized queries. The third one compares one given reference part with all parts in the database, and locates files that are identical, or similar to, the reference part. All approaches run automatically, and have the analysis of the structure tree in common. Files constructed with CATIA V5, and search engines written with Python have been used for the implementation. The paper also includes a short comparison of the advantages and disadvantages of each program, as well as a performance test.
A best-first soft/hard decision tree searching MIMO decoder for a 4 × 4 64-QAM system
Shen, Chungan
2012-08-01
This paper presents the algorithm and VLSI architecture of a configurable tree-searching approach that combines the features of classical depth-first and breadth-first methods. Based on this approach, techniques to reduce complexity while providing both hard and soft outputs decoding are presented. Furthermore, a single programmable parameter allows the user to tradeoff throughput versus BER performance. The proposed multiple-input-multiple-output decoder supports a 4 × 4 64-QAM system and was synthesized with 65-nm CMOS technology at 333 MHz clock frequency. For the hard output scheme the design can achieve an average throughput of 257.8 Mbps at 24 dB signal-to-noise ratio (SNR) with area equivalent to 54.2 Kgates and a power consumption of 7.26 mW. For the soft output scheme it achieves an average throughput of 83.3 Mbps across the SNR range of interest with an area equivalent to 64 Kgates and a power consumption of 11.5 mW. © 2011 IEEE.
Directory of Open Access Journals (Sweden)
J. I. Park
2013-03-01
Full Text Available In this paper, we propose a hybrid maximum likelihood (ML decoding scheme for multiple-input multiple-output(MIMO systems. After partitioning the searching tree into several stages, the proposed scheme adopts thecombination of depth- and breadth-first search methods in an organized way. Taking the number of stages, the size ofsignal constellation, and the number of antennas as the parameter of the scheme, we provide extensive simulationresults for various MIMO communication conditions. Numerical results indicate that, when the depth- and breadth-firstsearch methods are employed appropriately, the proposed scheme exhibits substantially lower computationalcomplexity than conventional ML decoders while maintaining the ML bit error performance.
Structured Learning of Two-Level Dynamic Rankings
Raman, Karthik; Shivaswamy, Pannaga
2011-01-01
For ambiguous queries, conventional retrieval systems are bound by two conflicting goals. On the one hand, they should diversify and strive to present results for as many query intents as possible. On the other hand, they should provide depth for each intent by displaying more than a single result. Since both diversity and depth cannot be achieved simultaneously in the conventional static retrieval model, we propose a new dynamic ranking approach. Dynamic ranking models allow users to adapt the ranking through interaction, thus overcoming the constraints of presenting a one-size-fits-all static ranking. In particular, we propose a new two-level dynamic ranking model for presenting search results to the user. In this model, a user's interactions with the first-level ranking are used to infer this user's intent, so that second-level rankings can be inserted to provide more results relevant for this intent. Unlike for previous dynamic ranking models, we provide an algorithm to efficiently compute dynamic ranking...
Wawer, Mathias; Bajorath, Jürgen
2010-08-23
An intuitive and generally applicable analysis method, termed similarity-potency tree (SPT), is introduced to mine structure-activity relationship (SAR) information in compound data sets of any source. Only compound potency values and nearest-neighbor similarity relationships are considered. Rather than analyzing a data set as a whole, in part overlapping compound neighborhoods are systematically generated and represented as SPTs. This local analysis scheme simplifies the evaluation of SAR information and SPTs of high SAR information content are easily identified. By inspecting only a limited number of compound neighborhoods, it is also straightforward to determine whether data sets contain only little or no interpretable SAR information. Interactive analysis of SPTs is facilitated by reading the trees in two directions, which makes it possible to extract SAR rules, if available, in a consistent manner. The simplicity and interpretability of the data structure and the ease of calculation are characteristic features of this approach. We apply the methodology to high-throughput screening and lead optimization data sets, compare the approach to standard clustering techniques, illustrate how SAR rules are derived, and provide some practical guidance how to best utilize the methodology. The SPT program is made freely available to the scientific community.
DEFF Research Database (Denmark)
Sitchinava, Nodar; Zeh, Norbert
2012-01-01
We present the parallel buffer tree, a parallel external memory (PEM) data structure for batched search problems. This data structure is a non-trivial extension of Arge's sequential buffer tree to a private-cache multiprocessor environment and reduces the number of I/O operations by the number...... of available processor cores compared to its sequential counterpart, thereby taking full advantage of multicore parallelism. The parallel buffer tree is a search tree data structure that supports the batched parallel processing of a sequence of N insertions, deletions, membership queries, and range queries...
Partial index replicated and distributed scheme for full-text search on wireless broadcast
Indian Academy of Sciences (India)
Vikas Goel; Anil Kumar Ahlawat; M N Gupta
2015-10-01
Information indexing is an extremely useful solution for wireless broadcast channels, because of its energy efficiency. Full text search on the wireless broadcast stream is another popular type of information dissemination access. This research paper discusses indexing schemes for full text search information, using two levels of structure B+ tree and inverted list. The partial replication in the B+ tree indexing scheme is proposed to extend the existing full text search indexing scheme. In the proposed work, the index information of B+ tree has been cut to reduce access time and tuning time: metrics for evaluating indexing schemes. The replication in B+ tree may be done up to a certain level of the indexed informat+ion (Data). Evaluation and analysis of the proposed indexing scheme show an excellent improvement over existing indexing schemes.
Two-Level Fingerprinting Codes: Non-Trivial Constructions
Rochanakul, Penying
2011-01-01
We extend the concept of two-level fingerprinting codes, introduced by Anthapadmanabhan and Barg (2009) in context of traceability (TA) codes, to other types of fingerprinting codes, namely identifiable parent property (IPP) codes, secure-frameproof (SFP) codes, and frameproof (FP) codes. We define and propose the first explicit non-trivial construction for two-level IPP, SFP and FP codes.
Oflazer, K
1996-01-01
This paper presents an efficient algorithm for retrieving from a database of trees, all trees that match a given query tree approximately, that is, within a certain error tolerance. It has natural language processing applications in searching for matches in example-based translation systems, and retrieval from lexical databases containing entries of complex feature structures. The algorithm has been implemented on SparcStations, and for large randomly generated synthetic tree databases (some having tens of thousands of trees) it can associatively search for trees with a small error, in a matter of tenths of a second to few seconds.
The Two-level Management System of University and School
Institute of Scientific and Technical Information of China (English)
Yang Xu
2013-01-01
With the development of our country's higher e-ducation, the school also presents the great-leap-forward devel-opment trend. The previous denotative development has changed into the way of connotative development. The two-level management system of university and school is the most common management mode in many colleges. This paper intro-duces the advantage of this mode in the objective view, analyzes the problems existing in the practice operation, put forward countermeasures to improve the two-level management and proposes a method to build the two-level management system.
Field correlations and effective two level atom-cavity systems
Rebic, S; Tan, S M
2004-01-01
We analyse the properties of the second order correlation functions of the electromagnetic field in atom-cavity systems that approximate two-level systems. It is shown that a recently-developed polariton formalism can be used to account for all the properties of the correlations, if the analysis is extended to include two manifolds - corresponding to the ground state and the states excited by a single photon - rather than just two levels.
Compressed Data Structures for Range Searching
DEFF Research Database (Denmark)
Bille, Philip; Gørtz, Inge Li; Vind, Søren Juhl
2015-01-01
matrices and web graphs. Our contribution is twofold. First, we show how to compress geometric repetitions that may appear in standard range searching data structures (such as K-D trees, Quad trees, Range trees, R-trees, Priority R-trees, and K-D-B trees), and how to implement subsequent range queries...
Uniformity pattern and related criteria for two-level factorials
Institute of Scientific and Technical Information of China (English)
FANG; Kaitai; QIN; Hong
2005-01-01
In this paper,the study of projection properties of two-level factorials in view of geometry is reported.The concept of uniformity pattern is defined.Based on this new concept,criteria of uniformity resolution and minimum projection uniformity are proposed for comparing two-level factorials.Relationship between minimum projection uniformity and other criteria such as minimum aberration,generalized minimum aberration and orthogonality is made explict.This close relationship raises the hope of improving the connection between uniform design theory and factorial design theory.Our results provide a justification of orthogonality,minimum aberration,and generalized minimum aberration from a natural geometrical interpretation.
Rectilinear Full Steiner Tree Generation
DEFF Research Database (Denmark)
Zachariasen, Martin
1999-01-01
The fastest exact algorithm (in practice) for the rectilinear Steiner tree problem in the plane uses a two-phase scheme: First, a small but sufficient set of full Steiner trees (FSTs) is generated and then a Steiner minimum tree is constructed from this set by using simple backtrack search, dynamic...
A Comprehensive Guide to Factorial Two-Level Experimentation
Mee, Robert
2009-01-01
Statistical design of experiments is useful in virtually every quantitative field. This book focuses on two-level factorial designs that provide efficient plans for exploring the effects of many factors at once. It is suitable for engineers, physical scientists, and those who conduct experiments.
Modulated two-level system: exact work statistics.
Verley, Gatien; Van den Broeck, Christian; Esposito, Massimiliano
2013-09-01
We consider an open two-level system driven by a piecewise constant periodic field and described by a rate equation with Fermi, Bose, and Arrhenius rates, respectively. We derive an analytical expression for the generating function and large deviation function of the work performed by the field and show that a work fluctuation theorem holds.
Two-level convolution formula for nuclear structure function
Ma, Boqiang
1990-05-01
A two-level convolution formula for the nuclear structure function is derived in considering the nucleus as a composite system of baryon-mesons which are also composite systems of quark-gluons again. The results show that the European Muon Colaboration effect can not be explained by the nuclear effects as nucleon Fermi motion and nuclear binding contributions.
Experiments of Two-level Training in Hungarian Higher Education
Korcsog, Andras; And Others
1977-01-01
An experiment designed to train engineering students to two levels of achievement in three-year and five-year programs within a single institution is reported. Organizational and curricular problems created by such integrated schemes are examined. (Author/LBH)
THE TWO-LEVEL MODEL AT FINITE-TEMPERATURE
Energy Technology Data Exchange (ETDEWEB)
Goodman, A.L.
1980-07-01
The finite-temperature HFB cranking equations are solved for the two-level model. The pair gap, moment of inertia and internal energy are determined as functions of spin and temperature. Thermal excitations and rotations collaborate to destroy the pair correlations. Raising the temperature eliminates the backbending effect and improves the HFB approximation.
用于控制器保护的防火墙规则的三叉树算法%Ternary search tree algorithm of firewall rules for controller protection
Institute of Scientific and Technical Information of China (English)
傅一帆; 刘小树; 刘跃; 黄玲
2012-01-01
A ternary search tree algorithm in time 0(「log32N」,which is IP address range set oriented,is presented for speedups of searching firewall rules, where N is the number of rules. This paper also proposes the analysis of a multi-dimensional Euclidean space model on which rules are specified to solve the problem of rule conflict. The generating algorithm of firewall rule tree ia described in details. The ternary search tree algorithm facilitates system reliability analysis and verification of safety integrity level, and is particularly applicable to control applications.%为提高防火墙安全规则的查找速度,提出了一种面向IP地址集合处理的时间复杂度为O(「log32N」)的三叉树查找算法,N为安全规则数.用空间分析法解决规则冲突,并给出规则树的生成算法,该方法适用于控制应用的可靠性分析和安全完整性等级验证的要求.
Possible Minkowskian Language in Two-level Systems
Kim, Y S
2008-01-01
One hundred years ago, in 1908, Hermann Minkowski completed his proof that Maxwell's equations are covariant under Lorentz transformations. During this process, he introduced a four-dimensional space called the Minkowskian space. In 1949, P. A. M. Dirac showed the Minkowskian space can be handled with the light-cone coordinate system with squeeze transformations. While the squeeze is one of the fundamental mathematical operations in optical sciences, it could serve useful purposes in two-level systems. Some possibilities are considered in this report. It is shown possible to cross the light-cone boundary in optical and two-level systems while it is not possible in Einstein's theory of relativity.
Model discrimination for dephasing two-level systems
Energy Technology Data Exchange (ETDEWEB)
Gong, Er-ling [Department of Automatic Control, College of Mechatronic Engineering and Automation, National University of Defense Technology, Changsha, Hunan 410073 (China); College of Science (Physics), Swansea University, Singleton Park, Swansea, SA2 8PP (United Kingdom); Zhou, Weiwei [Department of Automatic Control, College of Mechatronic Engineering and Automation, National University of Defense Technology, Changsha, Hunan 410073 (China); Schirmer, Sophie, E-mail: sgs29@swan.ac.uk [College of Science (Physics), Swansea University, Singleton Park, Swansea, SA2 8PP (United Kingdom)
2015-02-06
The problem of model discriminability and parameter identifiability for dephasing two-level systems subject to Hamiltonian control is studied. Analytic solutions of the Bloch equations are used to derive explicit expressions for observables as functions of time for different models. This information is used to give criteria for model discrimination and parameter estimation based on simple experimental paradigms. - Highlights: • Analytic expressions for observables of driven, dephasing two-level systems. • Distinguishability of dephasing models via Rabi-oscillation experiments. • General identifiability of model parameters and cases of failure. • Application to empirically determine of effect of driving on dephasing basis. • Importance for optimal design of coherent controls for qubits subject to dephasing.
Berry phase in a generalized nonlinear two-level system
Institute of Scientific and Technical Information of China (English)
Liu Ji-Bing; Li Jia-Hua; Song Pei-Jun; Li Wei-Bin
2008-01-01
In this paper,we investigate the behaviour of the geometric phase of a more generalized nonlinear system composed of an effective two-level system interacting with a single-mode quantized cavity field.Both the field nonlinearity and the atom-field coupling nonlinearity are considered.We find that the geometric phase depends on whether the index k is an odd number or an even number in the resonant case.In addition,we also find that the geometric phase may be easily observed when the field nonlinearity is not considered.The fractional statistical phenomenon appears in this system if the strong nonlinear atom-field coupling is considered.We have also investigated the geometric phase of an effective two-level system interacting with a two-mode quantized cavity field.
Two-level method with coarse space size independent convergence
Energy Technology Data Exchange (ETDEWEB)
Vanek, P.; Brezina, M. [Univ. of Colorado, Denver, CO (United States); Tezaur, R.; Krizkova, J. [UWB, Plzen (Czech Republic)
1996-12-31
The basic disadvantage of the standard two-level method is the strong dependence of its convergence rate on the size of the coarse-level problem. In order to obtain the optimal convergence result, one is limited to using a coarse space which is only a few times smaller than the size of the fine-level one. Consequently, the asymptotic cost of the resulting method is the same as in the case of using a coarse-level solver for the original problem. Today`s two-level domain decomposition methods typically offer an improvement by yielding a rate of convergence which depends on the ratio of fine and coarse level only polylogarithmically. However, these methods require the use of local subdomain solvers for which straightforward application of iterative methods is problematic, while the usual application of direct solvers is expensive. We suggest a method diminishing significantly these difficulties.
A two level DEA in project based organizations
Directory of Open Access Journals (Sweden)
Mehrdad Hamidi Hedayat
2012-01-01
Full Text Available This paper presents a systematic approach for evaluating the performance of a project based organization using a two level fuzzy data envelopment analysis (DEA technique in project based organizations. In order to determine the required inputs and outputs, important indicators are selected using both expert judgments and statistical analysis and a two-level DEA model is adapted. In this model, by considering different inputs and outputs through a hierarchical process, a large number of sub indicators are provided and rolled up to a higher level. Since inputs and outputs are combinations of qualitative and quantitative indicators, fuzzy logic is also included through the modeling procedure. In addition, since the exact amount cannot be attributed to the indicators, the proposed model uses interval values for the project life cycle. Finally, some of the projects are evaluated throughout the approach proposed in this paper.
Micro- and macrostresses in two level model of coating growth
N. N. Nazarenko; Knyazeva, Anna Georgievna
2014-01-01
In the work, a two level model of coating growing with the diffusion and chemical compounds formation is proposed. The process of coating formation includes different physico-chemical steps and transformations of the structure. From the experiments it was established that the coating consists of the following substances: 4+ titanium oxide, titanium pyrophosphate, calcium pyrophosphate, calcium titanophosphate. Coating growth rate is determined by the deposition rate and the dispersion of the ...
Franson Interference Generated by a Two-Level System
Peiris, M.; Konthasinghe, K.; Muller, A.
2017-01-01
We report a Franson interferometry experiment based on correlated photon pairs generated via frequency-filtered scattered light from a near-resonantly driven two-level semiconductor quantum dot. In contrast to spontaneous parametric down-conversion and four-wave mixing, this approach can produce single pairs of correlated photons. We have measured a Franson visibility as high as 66%, which goes beyond the classical limit of 50% and approaches the limit of violation of Bell's inequalities (70.7%).
Quantum modeling of two-level photovoltaic systems
Aram, Tahereh Nemati; Asgari, Asghar; Ernzerhof, Matthias; Quémerais, Pascal; Mayou, Didier
2017-06-01
We present a quantum formalism that provides a quantitative picture of the fundamental processes of charge separation that follow an absorption event. We apply the formalism to two-level photovoltaic cells and our purpose is to pedagogically explain the main aspects of the model. The formalism is developed in the energy domain and provides detailed knowledge about existence or absence of localized states and their effects on electronic structure and photovoltaic yield.
Two-level systems driven by large-amplitude fields
Nori, F.; Ashhab, S.; Johansson, J. R.; Zagoskin, A. M.
2009-03-01
We analyze the dynamics of a two-level system subject to driving by large-amplitude external fields, focusing on the resonance properties in the case of driving around the region of avoided level crossing. In particular, we consider three main questions that characterize resonance dynamics: (1) the resonance condition, (2) the frequency of the resulting oscillations on resonance, and (3) the width of the resonance. We identify the regions of validity of different approximations. In a large region of the parameter space, we use a geometric picture in order to obtain both a simple understanding of the dynamics and quantitative results. The geometric approach is obtained by dividing the evolution into discrete time steps, with each time step described by either a phase shift on the basis states or a coherent mixing process corresponding to a Landau-Zener crossing. We compare the results of the geometric picture with those of a rotating wave approximation. We also comment briefly on the prospects of employing strong driving as a useful tool to manipulate two-level systems. S. Ashhab, J.R. Johansson, A.M. Zagoskin, F. Nori, Two-level systems driven by large-amplitude fields, Phys. Rev. A 75, 063414 (2007). S. Ashhab et al, unpublished.
Two-level leader-follower organization in pigeon flocks
Chen, Zhiyong; Zhang, Hai-Tao; Chen, Xi; Chen, Duxin; Zhou, Tao
2015-10-01
The most attractive trait of collective animal behavior is the emergence of highly ordered structures (Cavagna A., Giardina I. and Ginelli F., Phys. Rev. Lett., 110 (2013) 168107). It has been conjectured that the interaction mechanism in pigeon flock dynamics follows a hierarchical leader-follower influential network (Nagy M., Ákos Z., Biro D. and Vicsek T., Nature, 464 (2010) 890). In this paper, a new observation is reported that shows that pigeon flocks actually adopt a much simpler two-level interactive network composed of one leader and some followers. By statistically analyzing the same experimental dataset, we show that for a certain period of time a sole leader determines the motion of the flock while the remaining birds are all followers directly copying the leader's direction with specific time delays. This simple two-level despotic organization is expected to save both motional energy and communication cost, while retaining agility and robustness of the whole group. From an evolutionary perspective, our results suggest that a two-level organization of group flight may be more efficient than a multilevel topology for small pigeon flocks.
A Two-Level Method for Nonsymmetric Eigenvalue Problems
Institute of Scientific and Technical Information of China (English)
Karel Kolman
2005-01-01
A two-level discretization method for eigenvalue problems is studied. Compared to the standard Galerkin finite element discretization technique performed on a fine grid this method discretizes the eigenvalue problem on a coarse grid and obtains an improved eigenvector (eigenvalue) approximation by solving only a linear problem on the fine grid (or two linear problems for the case of eigenvalue approximation of nonsymmetric problems). The improved solution has the asymptotic accuracy of the Galerkin discretization solution. The link between the method and the iterated Galerkin method is established. Error estimates for the general nonsymmetric case are derived.
Ultra-short strong excitation of two-level systems
Jha, Pankaj K.; Eleuch, Hichem; Grazioso, Fabio
2014-11-01
We present a model describing the use of ultra-short strong pulses to control the population of the excited level of a two-level quantum system. In particular, we study an off-resonance excitation with a few cycles pulse which presents a smooth phase jump i.e. a change of the pulse's phase which is not step-like, but happens over a finite time interval. A numerical solution is given for the time-dependent probability amplitude of the excited level. The control of the excited level's population is obtained acting on the shape of the phase transient, and other parameters of the excitation pulse.
Ultra-short strong excitation of two-level systems
2013-01-01
We present a model describing the use of ultra-short strong pulses to control the population of the excited level of a two-level quantum system. In particular, we study an off-resonance excitation with a few cycles pulse which presents a smooth phase jump i.e. a change of the pulse's phase which is not step-like, but happens over a finite time interval. A numerical solution is given for the time-dependent probability amplitude of the excited level. The control of the excited level's populatio...
Levitated nanoparticle as a classical two-level atom [Invited
Frimmer, Martin; Gieseler, Jan; Ihn, Thomas; Novotny, Lukas
2017-06-01
The center-of-mass motion of a single optically levitated nanoparticle resembles three uncoupled harmonic oscillators. We show how a suitable modulation of the optical trapping potential can give rise to a coupling between two of these oscillators, such that their dynamics are governed by a classical equation of motion that resembles the Schr\\"odinger equation for a two-level system. Based on experimental data, we illustrate the dynamics of this parametrically coupled system both in the frequency and in the time domain. We discuss the limitations and differences of the mechanical analogue in comparison to a true quantum mechanical system.
Negative spontaneous emission by a moving two-level atom
Lannebère, Sylvain; Silveirinha, Mário G.
2017-01-01
In this paper we investigate how the dynamics of a two-level atom is affected by its interaction with the quantized near field of a plasmonic slab in relative motion. We demonstrate that for small separation distances and a relative velocity greater than a certain threshold, this interaction can lead to a population inversion, such that the probability of the excited state exceeds the probability of the ground state, corresponding to a negative spontaneous emission rate. It is shown that the developed theory is intimately related to a classical problem. The problem of quantum friction is analyzed and the differences with respect to the corresponding classical effect are highlighted.
Noise from Two-Level Systems in Superconducting Resonators
Neill, C.; Barends, R.; Chen, Y.; Chiaro, B.; Jeffrey, E.; Kelly, J.; Mariantoni, M.; Megrant, A.; Mutus, J.; Ohya, S.; Sank, D.; Vainsencher, A.; Wenner, J.; White, T.; Cleland, A. N.; Martinis, J. M.
2013-03-01
Two-level systems (TLSs) present in amorphous dielectrics and surface interfaces are a significant source of decoherence in superconducting qubits. Linear microwave resonators offer a valuable instrument for characterizing the strongly power-dependent response of these TLSs. Using quarter-wavelength coplanar waveguide resonators, we monitored the microwave response of the resonator at a single near-resonant frequency versus time at varying microwave drive powers. We observe a time dependent variation of the resonator's internal dissipation and resonance frequency. The amplitude of these variations saturates with power in a manner similar to loss from TLSs. These results provide a means for quantifying the number and distribution of TLSs.
Comparison of time optimal control for two level quantum systems
Institute of Scientific and Technical Information of China (English)
Shuang Cong; Jie Wen; Xubo Zou
2014-01-01
The time optimal problem for a two level quantum sys-tem is studied. We compare two different control strategies of bang-bang control and the geometric control, respectively, es-pecial y in the case of minimizing the time of steering the state from North Pole to South Pole on the Bloch sphere with bounded control. The time performances are compared for different param-eters by the individual numerical simulation experiments, and the experimental results are analyzed. The results show that the ge-ometric control spends less time than the bang-bang control does.
Variational Study on a Dissipative Two-Level System
Institute of Scientific and Technical Information of China (English)
ZHU Wei-Wing; REN Qing-Bao; CHEN Qing-Hu
2008-01-01
A new variational approach is proposed to study the ground-state of a two-level system coupled to a dispersionless phonon bath. By the extended coherent state, where the more phonon correlations are easily incorporated, we can obtain very accurate ground state energy and the tunnelling reduction factor in all regime of tunnelling matrix element δo and coupling parameter s. The relative difference between the present ones and those by exact numerical diagonalization is less then 0.001%. In addition, some simple analytical results are given in the limits of δo/s → 0 and ∞.
Energy Technology Data Exchange (ETDEWEB)
Pangilinan, Monica [Brown Univ., Providence, RI (United States)
2010-05-01
The top quark produced through the electroweak channel provides a direct measurement of the V_{tb} element in the CKM matrix which can be viewed as a transition rate of a top quark to a bottom quark. This production channel of top quark is also sensitive to different theories beyond the Standard Model such as heavy charged gauged bosons termed W'. This thesis measures the cross section of the electroweak produced top quark using a technique based on using the matrix elements of the processes under consideration. The technique is applied to 2.3 fb^{-1} of data from the D0 detector. From a comparison of the matrix element discriminants between data and the signal and background model using Bayesian statistics, we measure the cross section of the top quark produced through the electroweak mechanism σ(p$\\bar{p}$ → tb + X, tqb + X) = 4.30_{-1.20}^{+0.98} pb. The measured result corresponds to a 4.9σ Gaussian-equivalent significance. By combining this analysis with other analyses based on the Bayesian Neural Network (BNN) and Boosted Decision Tree (BDT) method, the measured cross section is 3.94 ± 0.88 pb with a significance of 5.0σ, resulting in the discovery of electroweak produced top quarks. Using this measured cross section and constraining |V_{tb}| < 1, the 95% confidence level (C.L.) lower limit is |V_{tb}| > 0.78. Additionally, a search is made for the production of W' using the same samples from the electroweak produced top quark. An analysis based on the BDT method is used to separate the signal from expected backgrounds. No significant excess is found and 95% C.L. upper limits on the production cross section are set for W' with masses within 600-950 GeV. For four general models of W{prime} boson production using decay channel W' → t$\\bar{p}$, the lower mass limits are the following: M(W'_{L} with SM couplings) > 840 GeV; M(W'_{R}) > 880 GeV or 890 GeV if the
Two-level hierarchical feature learning for image classification
Institute of Scientific and Technical Information of China (English)
Guang-hui SONG; Xiao-gang JIN; Gen-lang CHEN; Yan NIE
2016-01-01
In some image classifi cation tasks, similarities among different categories are different and the samples are usually misclassifi ed as highly similar categories. To distinguish highly similar categories, more specifi c features are required so that the classifi er can improve the classifi cation performance. In this paper, we propose a novel two-level hierarchical feature learning framework based on the deep convolutional neural network (CNN), which is simple and effective. First, the deep feature extractors of different levels are trained using the transfer learning method that fi ne-tunes the pre-trained deep CNN model toward the new target dataset. Second, the general feature extracted from all the categories and the specifi c feature extracted from highly similar categories are fused into a feature vector. Then the fi nal feature representation is fed into a linear classifi er. Finally, experiments using the Caltech-256, Oxford Flower-102, and Tasmania Coral Point Count (CPC) datasets demonstrate that the expression ability of the deep features resulting from two-level hierarchical feature learning is powerful. Our proposed method effectively increases the classifi cation accuracy in comparison with fl at multiple classifi cation methods.
Two-level evaluation on sensor interoperability of features in fingerprint image segmentation.
Yang, Gongping; Li, Ying; Yin, Yilong; Li, Ya-Shuo
2012-01-01
Features used in fingerprint segmentation significantly affect the segmentation performance. Various features exhibit different discriminating abilities on fingerprint images derived from different sensors. One feature which has better discriminating ability on images derived from a certain sensor may not adapt to segment images derived from other sensors. This degrades the segmentation performance. This paper empirically analyzes the sensor interoperability problem of segmentation feature, which refers to the feature's ability to adapt to the raw fingerprints captured by different sensors. To address this issue, this paper presents a two-level feature evaluation method, including the first level feature evaluation based on segmentation error rate and the second level feature evaluation based on decision tree. The proposed method is performed on a number of fingerprint databases which are obtained from various sensors. Experimental results show that the proposed method can effectively evaluate the sensor interoperability of features, and the features with good evaluation results acquire better segmentation accuracies of images originating from different sensors.
The Computational Complexity of Two-Level Morphology.
1985-11-01
phonological changes and ortho- graphic conventions. In this paper, theee two asepects of spelling changes will riot he distinguished. The plionology and...repremctations (e.g. froto autosegiremtal theory) that allow a more ilhm: uinating dese ription of various linguistic processes. Oe possible argmnent for thein...recognizer is entertaining along each path, during the analysis of spiel with a merged dictionary. Figure 4 displays the search graphically with an
Optimizing ETL by a Two-level Data Staging Method
DEFF Research Database (Denmark)
Iftikhar, Nadeem
2016-01-01
In data warehousing, the data from source systems are populated into a central data warehouse (DW) through extraction, transformation and loading (ETL). The standard ETL approach usually uses sequential jobs to process the data with dependencies, such as dimension and fact data. It is a non......-/late-arriving data, and fast-/slowly-changing data. The introduced additional staging area decouples loading process from data extraction and transformation, which improves ETL flexibility and minimizes intervention to the data warehouse. This paper evaluates the proposed method empirically, which shows......-trivial task to process the so-called early-/late-arriving data, which arrive out of order. This paper proposes a two-level data staging area method to optimize ETL. The proposed method is an all-in-one solution that supports processing different types of data from operational systems, including early...
Rabi noise spectroscopy of individual two-level tunneling defects
Matityahu, Shlomi; Lisenfeld, Jürgen; Bilmes, Alexander; Shnirman, Alexander; Weiss, Georg; Ustinov, Alexey V.; Schechter, Moshe
2017-06-01
Understanding the nature of two-level tunneling defects is important for minimizing their disruptive effects in various nanodevices. By exploiting the resonant coupling of these defects to a superconducting qubit, one can probe and coherently manipulate them individually. In this work, we utilize a phase qubit to induce Rabi oscillations of single tunneling defects and measure their dephasing rates as a function of the defect's asymmetry energy, which is tuned by an applied strain. The dephasing rates scale quadratically with the external strain and are inversely proportional to the Rabi frequency. These results are analyzed and explained within a model of interacting defects, in which pure dephasing of coherent high-frequency (gigahertz) defects is caused by interaction with incoherent low-frequency thermally excited defects. Our analysis sets an upper bound for the relaxation rates of thermally excited defects interacting strongly with strain fields.
Human action analysis with randomized trees
Yu, Gang; Liu, Zicheng
2014-01-01
This book will provide a comprehensive overview on human action analysis with randomized trees. It will cover both the supervised random trees and the unsupervised random trees. When there are sufficient amount of labeled data available, supervised random trees provides a fast method for space-time interest point matching. When labeled data is minimal as in the case of example-based action search, unsupervised random trees is used to leverage the unlabelled data. We describe how the randomized trees can be used for action classification, action detection, action search, and action prediction.
STLIS: A Scalable Two-Level Index Scheme for Big Data in IoT
Directory of Open Access Journals (Sweden)
Yonglin Leng
2016-01-01
Full Text Available The rapid development of the Internet of Things causes the dramatic growth of data, which poses an important challenge on the storage and quick retrieval of big data. As an effective representation model, RDF receives the most attention. More and more storage and index schemes have been developed for RDF model. For the large-scale RDF data, most of them suffer from a large number of self-joins, high storage cost, and many intermediate results. In this paper, we propose a scalable two-level index scheme (STLIS for RDF data. In the first level, we devise a compressed path template tree (CPTT index based on S-tree to retrieve the candidate sets of full path. In the second level, we create a hierarchical edge index (HEI and a node-predicate (NP index to accelerate the match. Extensive experiments are executed on two representative RDF benchmarks and one real RDF dataset in IoT by comparison with three representative index schemes, that is, RDF-3X, Bitmat, and TripleBit. Results demonstrate that our proposed scheme can respond to the complex query in real time and save much storage space compared with RDF-3X and Bitmat.
Two-level tunneling systems in amorphous alumina
Lebedeva, Irina V.; Paz, Alejandro P.; Tokatly, Ilya V.; Rubio, Angel
2014-03-01
The decades of research on thermal properties of amorphous solids at temperatures below 1 K suggest that their anomalous behaviour can be related to quantum mechanical tunneling of atoms between two nearly equivalent states that can be described as a two-level system (TLS). This theory is also supported by recent studies on microwave spectroscopy of superconducting qubits. However, the microscopic nature of the TLS remains unknown. To identify structural motifs for TLSs in amorphous alumina we have performed extensive classical molecular dynamics simulations. Several bistable motifs with only one or two atoms jumping by considerable distance ~ 0.5 Å were found at T=25 K. Accounting for the surrounding environment relaxation was shown to be important up to distances ~ 7 Å. The energy asymmetry and barrier for the detected motifs lied in the ranges 0.5 - 2 meV and 4 - 15 meV, respectively, while their density was about 1 motif per 10 000 atoms. Tuning of motif asymmetry by strain was demonstrated with the coupling coefficient below 1 eV. The tunnel splitting for the symmetrized motifs was estimated on the order of 0.1 meV. The discovered motifs are in good agreement with the available experimental data. The financial support from the Marie Curie Fellowship PIIF-GA-2012-326435 (RespSpatDisp) is gratefully acknowledged.
CONSENSUS FORMATION OF TWO-LEVEL OPINION DYNAMICS
Institute of Scientific and Technical Information of China (English)
Yilun SHANG
2014-01-01
Opinion dynamics have received significant attention in recent years. This pa-per proposes a bounded confidence opinion model for a group of agents with two different confidence levels. Each agent in the population is endowed with a confidence interval around her opinion with radius αd or (1-α)d, where α ∈ (0, 1/2] represents the differentiation of confidence levels. We analytically derived the critical confidence bound dc =1/(4α) for the two-level opinion dynamics on Z. A single opinion cluster is formed with probability 1 above this critical value regardless of the ratio p of agents with high/low confidence. Extensive numerical simulations are performed to illustrate our theoretical results. Noticed is a clear impact of p on the collective behavior: more agents with high confidence lead to harder agreement. It is also experimentally revealed that the sharpness of the threshold dc increases with αbut does not depend on p.
分组自适应多叉树 RFID防碰撞算法研究%A Grouping Adaptive Anti-Collision Algorithm Based on Multi-tree Search
Institute of Scientific and Technical Information of China (English)
刘培学; 高颖; 陈玉杰
2014-01-01
The paper proposed a grouping adaptive multi-tree RFID anti-collision algorithm which divide the tags into many group based on the comprehensive analysis of variety tree-based algorithm ,the tags is handled as group ,the number of responding tags is reduced in the one time ,thereby the probability of collision is reduced ,in the same group ,dynamic or dynamic quad-tree search is selected automatically according to the collision factor with using back strategy ,simulation results show that the algorithm has improved greatly on the average number of queries and the amount of data transmission compared to other algorithms .%提出了一种基于分组自适应多叉树的RFID防碰撞算法，该算法将标签分为多组并按分组处理标签，减少同一时刻同时响应的标签的数目，从而减少碰撞发生的概率，对同一分组的标签，按照碰撞因子自动选择动态二叉树或动态四叉树搜索，同时采用后退策略。仿真结果表明，该算法在平均查询次数及传输数据量上较其他算法都有较大提高。
PoInTree: A Polar and Interactive Phylogenetic Tree
Institute of Scientific and Technical Information of China (English)
Carreras Marco; Gianti Eleonora; Sartori Luca; Plyte Simon Edward; Isacchi Antonella; Bosotti Roberta
2005-01-01
PoInTree (Polar and Innteractive Tree) is an application that allows to build, visualize, and customize phylogenetic trees in a polar, interactive, and highly flexible view. It takes as input a FASTA file or multiple alignment formats. Phylogenetic tree calculation is based on a sequence distance method and utilizes the Neighbor Joining (NJ) algorithm. It also allows displaying precalculated trees of the major protein families based on Pfam classification. In PoInTree, nodes can be dynamically opened and closed and distances between genes are graphically represented.Tree root can be centered on a selected leaf. Text search mechanism, color-coding and labeling display are integrated. The visualizer can be connected to an Oracle database containing information on sequences and other biological data, helping to guide their interpretation within a given protein family across multiple species.The application is written in Borland Delphi and based on VCL Teechart Pro 6 graphical component (Steema software).
DEFF Research Database (Denmark)
Assent, Ira; Krieger, Ralph; Afschari, Farzad;
2008-01-01
Continuous growth in sensor data and other temporal data increases the importance of retrieval and similarity search in time series data. Efficient time series query processing is crucial for interactive applications. Existing multidimensional indexes like the R-tree provide efficient querying fo...
DEFF Research Database (Denmark)
Assent, Ira; Krieger, Ralph; Afschari, Farzad
2008-01-01
Continuous growth in sensor data and other temporal data increases the importance of retrieval and similarity search in time series data. Efficient time series query processing is crucial for interactive applications. Existing multidimensional indexes like the R-tree provide efficient querying fo...
Institute of Scientific and Technical Information of China (English)
孙文胜; 胡玲敏
2011-01-01
Concerning the common problem of tag collision in Radio Frequency Identification (RFID) system, an improved anti-collision algorithm for multi-branch tree was proposed based on the regressive-style search algorithm.According to the characteristics of the tags collision, the presented algorithm adopted the dormancy count, and took quad tree structure when continuous collision appeared, which had the ability to choose the number of forks dynamically during the searching process, reduced the search range and improved the identification efficiency.The performance analysis results show that the system efficiency of the proposed algorithm is about 76.5％; moreover, with the number of tags increased, the superiority of the performance is more obvious.%针对无线射频识别(RFID)系统中常见的标签防碰撞问题,在后退式搜索算法的基础上提出了一种改进的多叉树防碰撞算法.根据标签碰撞的特点,采用休眠计数的方法,以及遇到连续碰撞位时进行四叉树分裂的策略,使得在搜索过程中能够动态选择分叉数量,缩短了标签识别时间,有效地提高了算法的搜索效率.性能分析表明,该算法的系统识别效率达76.5%,且随着标签数目的增多,优越性更加明显.
Böcker, Sebastian; Dührkop, Kai
2016-01-01
Untargeted metabolomics commonly uses liquid chromatography mass spectrometry to measure abundances of metabolites; subsequent tandem mass spectrometry is used to derive information about individual compounds. One of the bottlenecks in this experimental setup is the interpretation of fragmentation spectra to accurately and efficiently identify compounds. Fragmentation trees have become a powerful tool for the interpretation of tandem mass spectrometry data of small molecules. These trees are determined from the data using combinatorial optimization, and aim at explaining the experimental data via fragmentation cascades. Fragmentation tree computation does not require spectral or structural databases. To obtain biochemically meaningful trees, one needs an elaborate optimization function (scoring). We present a new scoring for computing fragmentation trees, transforming the combinatorial optimization into a Maximum A Posteriori estimator. We demonstrate the superiority of the new scoring for two tasks: both for the de novo identification of molecular formulas of unknown compounds, and for searching a database for structurally similar compounds, our method SIRIUS 3, performs significantly better than the previous version of our method, as well as other methods for this task. SIRIUS 3 can be a part of an untargeted metabolomics workflow, allowing researchers to investigate unknowns using automated computational methods.Graphical abstractWe present a new scoring for computing fragmentation trees from tandem mass spectrometry data based on Bayesian statistics. The best scoring fragmentation tree most likely explains the molecular formula of the measured parent ion.
Aspects of insertion in random trees
Bagchi, Arunabha; Reingold, E.M.
1982-01-01
A method formulated by Yao and used by Brown has yielded bounds on the fraction of nodes with specified properties in trees bult by a sequence of random internal nodes in a random tree built by binary search and insertion, and show that in such a tree about bounds better than those now known. We the
Aspects of insertion in random trees
Bagchi, Arunabha; Reingold, E.M.
1982-01-01
A method formulated by Yao and used by Brown has yielded bounds on the fraction of nodes with specified properties in trees bult by a sequence of random internal nodes in a random tree built by binary search and insertion, and show that in such a tree about bounds better than those now known. We
Bose, Prosenjit; Dujmović, Vida; Howat, John
2009-01-01
The working-set bound [Sleator and Tarjan, J. ACM, 1985] roughly states that searching for an element is fast if the element was accessed recently. Binary search trees, such as splay trees, can achieve this property in the amortized sense, while data structures that are not binary search trees are known to have this property in the worst case. We close this gap and present a binary search tree called a layered working-set tree that guarantees the working-set property in the worst case. The unified bound [Badoiu et al., TCS, 2007] roughly states that searching for an element is fast if it is near (in terms of rank distance) to a recently accessed element. We show how layered working-set trees can be used to achieve the unified bound to within a small additive term in the amortized sense while maintaining in the worst case an access time that is both logarithmic and within a small multiplicative factor of the working-set bound.
Kucharczyk, Robert A
2012-01-01
In this note we discuss trees similar to the Calkin-Wilf tree, a binary tree that enumerates all positive rational numbers in a simple way. The original construction of Calkin and Wilf is reformulated in a more algebraic language, and an elementary application of methods from analytic number theory gives restrictions on possible analogues.
Two-Level Evaluation on Sensor Interoperability of Features in Fingerprint Image Segmentation
Directory of Open Access Journals (Sweden)
Ya-Shuo Li
2012-03-01
Full Text Available Features used in fingerprint segmentation significantly affect the segmentation performance. Various features exhibit different discriminating abilities on fingerprint images derived from different sensors. One feature which has better discriminating ability on images derived from a certain sensor may not adapt to segment images derived from other sensors. This degrades the segmentation performance. This paper empirically analyzes the sensor interoperability problem of segmentation feature, which refers to the feature’s ability to adapt to the raw fingerprints captured by different sensors. To address this issue, this paper presents a two-level feature evaluation method, including the first level feature evaluation based on segmentation error rate and the second level feature evaluation based on decision tree. The proposed method is performed on a number of fingerprint databases which are obtained from various sensors. Experimental results show that the proposed method can effectively evaluate the sensor interoperability of features, and the features with good evaluation results acquire better segmentation accuracies of images originating from different sensors.
Tree compression with top trees
DEFF Research Database (Denmark)
Bille, Philip; Gørtz, Inge Li; Landau, Gad M.;
2015-01-01
We introduce a new compression scheme for labeled trees based on top trees. Our compression scheme is the first to simultaneously take advantage of internal repeats in the tree (as opposed to the classical DAG compression that only exploits rooted subtree repeats) while also supporting fast...
Tree compression with top trees
DEFF Research Database (Denmark)
Bille, Philip; Gørtz, Inge Li; Landau, Gad M.
2013-01-01
We introduce a new compression scheme for labeled trees based on top trees [3]. Our compression scheme is the first to simultaneously take advantage of internal repeats in the tree (as opposed to the classical DAG compression that only exploits rooted subtree repeats) while also supporting fast...
Tree compression with top trees
DEFF Research Database (Denmark)
Bille, Philip; Gørtz, Inge Li; Landau, Gad M.
2015-01-01
We introduce a new compression scheme for labeled trees based on top trees. Our compression scheme is the first to simultaneously take advantage of internal repeats in the tree (as opposed to the classical DAG compression that only exploits rooted subtree repeats) while also supporting fast...
Rojas Huamani, Jairo Martin
2017-01-01
The main goal is to have a direct measurement of the Yukawa coupling of the Higgs boson to the top quark which is only possible in the production process → ttH + . In this analysis, final states with 2 same sign leptons (neutrinos not counted) have been used in order to estimate the expected significance of the ttH process. A study using Boosted Decision Trees was done using Monte Carlo simulation equivalent to a luminosity of 36.5 fb-1 at √s=13 TeV, characteristics of the years 2015 and 2016 of Run-2 at LHC. The focus of my summer student program was to investigate the performance of the BDT, mainly: To avoid building of a rigid and possible overtrained BTD (Boosted Decision Tree) in charge of identifying pp→ttH+X process by removing systematically the number of variables used in the analysis. Look the expected sensitivity’s dependence on different parameters that takes in account the BDT.
Yu, Jeffrey Xu; Chang, Lijun
2009-01-01
It has become highly desirable to provide users with flexible ways to query/search information over databases as simple as keyword search like Google search. This book surveys the recent developments on keyword search over databases, and focuses on finding structural information among objects in a database using a set of keywords. Such structural information to be returned can be either trees or subgraphs representing how the objects, that contain the required keywords, are interconnected in a relational database or in an XML database. The structural keyword search is completely different from
Ganzinger, Harald; Nieuwenhuis, Robert; Nivela, Pilar
2001-01-01
Indexing data structures are well-known to be crucial for the efficiency of the current state-of-the-art theorem provers. Examples are \\emph{discrimination trees}, which are like tries where terms are seen as strings and common prefixes are shared, and \\emph{substitution trees}, where terms keep their tree structure and all common \\emph{contexts} can be shared. Here we describe a new indexing data structure, \\emph{context trees}, where, by means of a limited kind of conte...
Cochrane, John. H.; Longstaff, Francis A.; Santa-Clara, Pedro
2004-01-01
We solve a model with two â€œLucas trees.â€ Each tree has i.i.d. dividend growth. The investor has log utility and consumes the sum of the two treesâ€™ dividends. This model produces interesting asset-pricing dynamics, despite its simple ingredients. Investors want to rebalance their portfolios after any change in value. Since the size of the trees is fixed, however, prices must adjust to oï¬€set this desire. As a result, expected returns, excess returns, and return volatility all vary throug...
Concurrent Manipulation of Expanded AVL Trees
Institute of Scientific and Technical Information of China (English)
章寅; 许卓群
1998-01-01
The concurrent manipulation of an expanded AVL tree(EAVL tree)s considered in this paper.The presented system can support any number of concurrent processes which perform searching,insertion and deletion on the tree.Simulation results indicate the high performance of the system.Elaborate techniques are used to achieve such a system unavailable based on any known algorithms.Methods developed in this paper may provide new insights into other problems in the area of concurrent search structure manipulation.
Non-redundant patent sequence databases with value-added annotations at two levels.
Li, Weizhong; McWilliam, Hamish; de la Torre, Ana Richart; Grodowski, Adam; Benediktovich, Irina; Goujon, Mickael; Nauche, Stephane; Lopez, Rodrigo
2010-01-01
The European Bioinformatics Institute (EMBL-EBI) provides public access to patent data, including abstracts, chemical compounds and sequences. Sequences can appear multiple times due to the filing of the same invention with multiple patent offices, or the use of the same sequence by different inventors in different contexts. Information relating to the source invention may be incomplete, and biological information available in patent documents elsewhere may not be reflected in the annotation of the sequence. Search and analysis of these data have become increasingly challenging for both the scientific and intellectual-property communities. Here, we report a collection of non-redundant patent sequence databases, which cover the EMBL-Bank nucleotides patent class and the patent protein databases and contain value-added annotations from patent documents. The databases were created at two levels by the use of sequence MD5 checksums. Sequences within a level-1 cluster are 100% identical over their whole length. Level-2 clusters were defined by sub-grouping level-1 clusters based on patent family information. Value-added annotations, such as publication number corrections, earliest publication dates and feature collations, significantly enhance the quality of the data, allowing for better tracking and cross-referencing. The databases are available format: http://www.ebi.ac.uk/patentdata/nr/.
Non-redundant patent sequence databases with value-added annotations at two levels
Li, Weizhong; McWilliam, Hamish; de la Torre, Ana Richart; Grodowski, Adam; Benediktovich, Irina; Goujon, Mickael; Nauche, Stephane; Lopez, Rodrigo
2010-01-01
The European Bioinformatics Institute (EMBL-EBI) provides public access to patent data, including abstracts, chemical compounds and sequences. Sequences can appear multiple times due to the filing of the same invention with multiple patent offices, or the use of the same sequence by different inventors in different contexts. Information relating to the source invention may be incomplete, and biological information available in patent documents elsewhere may not be reflected in the annotation of the sequence. Search and analysis of these data have become increasingly challenging for both the scientific and intellectual-property communities. Here, we report a collection of non-redundant patent sequence databases, which cover the EMBL-Bank nucleotides patent class and the patent protein databases and contain value-added annotations from patent documents. The databases were created at two levels by the use of sequence MD5 checksums. Sequences within a level-1 cluster are 100% identical over their whole length. Level-2 clusters were defined by sub-grouping level-1 clusters based on patent family information. Value-added annotations, such as publication number corrections, earliest publication dates and feature collations, significantly enhance the quality of the data, allowing for better tracking and cross-referencing. The databases are available format: http://www.ebi.ac.uk/patentdata/nr/. PMID:19884134
Tolman, Marvin
2005-01-01
Students love outdoor activities and will love them even more when they build confidence in their tree identification and measurement skills. Through these activities, students will learn to identify the major characteristics of trees and discover how the pace--a nonstandard measuring unit--can be used to estimate not only distances but also the…
Bose, Prosenjit; Douieb, Karim; Dujmovic, Vida; King, James; Morin, Pat
2010-01-01
Let R^d -> A be a query problem over R^d for which there exists a data structure S that can compute P(q) in O(log n) time for any query point q in R^d. Let D be a probability measure over R^d representing a distribution of queries. We describe a data structure called the odds-on tree, of size O(n^\\epsilon) that can be used as a filter that quickly computes P(q) for some query values q in R^d and relies on S for the remaining queries. With an odds-on tree, the expected query time for a point drawn according to D is O(H*+1), where H* is a lower-bound on the expected cost of any linear decision tree that solves P. Odds-on trees have a number of applications, including distribution-sensitive data structures for point location in 2-d, point-in-polytope testing in d dimensions, ray shooting in simple polygons, ray shooting in polytopes, nearest-neighbour queries in R^d, point-location in arrangements of hyperplanes in R^d, and many other geometric searching problems that can be solved in the linear-decision tree mo...
Zhu, Ruoqing; Zeng, Donglin; Kosorok, Michael R
In this paper, we introduce a new type of tree-based method, reinforcement learning trees (RLT), which exhibits significantly improved performance over traditional methods such as random forests (Breiman, 2001) under high-dimensional settings. The innovations are three-fold. First, the new method implements reinforcement learning at each selection of a splitting variable during the tree construction processes. By splitting on the variable that brings the greatest future improvement in later splits, rather than choosing the one with largest marginal effect from the immediate split, the constructed tree utilizes the available samples in a more efficient way. Moreover, such an approach enables linear combination cuts at little extra computational cost. Second, we propose a variable muting procedure that progressively eliminates noise variables during the construction of each individual tree. The muting procedure also takes advantage of reinforcement learning and prevents noise variables from being considered in the search for splitting rules, so that towards terminal nodes, where the sample size is small, the splitting rules are still constructed from only strong variables. Last, we investigate asymptotic properties of the proposed method under basic assumptions and discuss rationale in general settings.
Baños, Hector; Bushek, Nathaniel; Davidson, Ruth; Gross, Elizabeth; Harris, Pamela E.; Krone, Robert; Long, Colby; Stewart, Allen; WALKER, Robert
2016-01-01
We introduce the package PhylogeneticTrees for Macaulay2 which allows users to compute phylogenetic invariants for group-based tree models. We provide some background information on phylogenetic algebraic geometry and show how the package PhylogeneticTrees can be used to calculate a generating set for a phylogenetic ideal as well as a lower bound for its dimension. Finally, we show how methods within the package can be used to compute a generating set for the join of any two ideals.
Game tree algorithms and solution trees
W.H.L.M. Pijls (Wim); A. de Bruin (Arie)
1998-01-01
textabstractIn this paper, a theory of game tree algorithms is presented, entirely based upon the concept of solution tree. Two types of solution trees are distinguished: max and min trees. Every game tree algorithm tries to prune nodes as many as possible from the game tree. A cut-off criterion in
DEFF Research Database (Denmark)
Appelt, Ane L; Rønde, Heidi S
2013-01-01
The photo shows a close-up of a Lichtenberg figure – popularly called an “electron tree” – produced in a cylinder of polymethyl methacrylate (PMMA). Electron trees are created by irradiating a suitable insulating material, in this case PMMA, with an intense high energy electron beam. Upon discharge......, during dielectric breakdown in the material, the electrons generate branching chains of fractures on leaving the PMMA, producing the tree pattern seen. To be able to create electron trees with a clinical linear accelerator, one needs to access the primary electron beam used for photon treatments. We...... appropriated a linac that was being decommissioned in our department and dismantled the head to circumvent the target and ion chambers. This is one of 24 electron trees produced before we had to stop the fun and allow the rest of the accelerator to be disassembled....
DEFF Research Database (Denmark)
Appelt, Ane L; Rønde, Heidi S
2013-01-01
The photo shows a close-up of a Lichtenberg figure – popularly called an “electron tree” – produced in a cylinder of polymethyl methacrylate (PMMA). Electron trees are created by irradiating a suitable insulating material, in this case PMMA, with an intense high energy electron beam. Upon discharge......, during dielectric breakdown in the material, the electrons generate branching chains of fractures on leaving the PMMA, producing the tree pattern seen. To be able to create electron trees with a clinical linear accelerator, one needs to access the primary electron beam used for photon treatments. We...... appropriated a linac that was being decommissioned in our department and dismantled the head to circumvent the target and ion chambers. This is one of 24 electron trees produced before we had to stop the fun and allow the rest of the accelerator to be disassembled....
Efficiency analysis on a two-level three-phase quasi-soft-switching inverter
DEFF Research Database (Denmark)
Geng, Pan; Wu, Weimin; Huang, Min;
2013-01-01
for non-conventional inverters with special shoot-through state is introduced and illustrated through the analysis on a special two-level three-phase quasi-soft-switching inverter. Efficiency comparison between the classical two-stage two-level three-phase inverter and the two-level three-phase quasi......-soft-switching inverter is carried out. A 10 kW/380 V prototype is constructed to verify the analysis. The experimental results show that the efficiency of the new inverter is higher than that of the traditional two-stage two- level three-phase inverter....
A Two-Level Spreading-despreading CDMA System and Its Performance Evaluation
Institute of Scientific and Technical Information of China (English)
无
2003-01-01
A new two-level spreading-despreading scheme is presented in this paper. By adopting the two-level scheme, the Generalized Orthogonal (GO) zone of GO codes can be utilized. In this paper, the forward link of a multi-cell CDMA system employing the two-level scheme is presented and analyzed. The BER performance obtained by Gaussian Approximation is compared with that of the conventional single-level spreading-despreading system. The results reveal that the two*$-level CDMA system introduced in this paper exhibits larger performance gain when time delay can be restricted within a given zone.
A new paradigm for minimax search
A. Plaat (Aske); J. Schaeffer; W.H.L.M. Pijls (Wim); A. de Bruin (Arie)
1995-01-01
textabstractThis paper introduces a new paradigm for minimax game-tree search algorithms. MT is a memory-enhanced version of Pearl's Test procedure. By changing the way MT is called, a number of best-first game-tree search algorithms can be simply and elegantly constructed (including SSS*). Most of
A new paradigm for minimax search
A. Plaat (Aske); J. Schaeffer; W.H.L.M. Pijls (Wim); A. de Bruin (Arie)
1995-01-01
textabstractThis paper introduces a new paradigm for minimax game-tree search algorithms. MT is a memory-enhanced version of Pearl's Test procedure. By changing the way MT is called, a number of best-first game-tree search algorithms can be simply and elegantly constructed (including SSS*). Most of
Two levels decision system for efficient planning and implementation of bioenergy production
Energy Technology Data Exchange (ETDEWEB)
Ayoub, Nasser [Chemical Resources Laboratory, Process Systems Engineering Division, Tokyo Institute of Technology, R1-19, 4259 Nagatsuta, Midori-ku Yokohama 226-8503 (Japan)]. E-mail: nasser@pse.res.titech.ac.jp; Martins, Ricardo [Chemical Resources Laboratory, Process Systems Engineering Division, Tokyo Institute of Technology, R1-19, 4259 Nagatsuta, Midori-ku Yokohama 226-8503 (Japan); Wang, Kefeng [Chemical Resources Laboratory, Process Systems Engineering Division, Tokyo Institute of Technology, R1-19, 4259 Nagatsuta, Midori-ku Yokohama 226-8503 (Japan); Seki, Hiroya [Chemical Resources Laboratory, Process Systems Engineering Division, Tokyo Institute of Technology, R1-19, 4259 Nagatsuta, Midori-ku Yokohama 226-8503 (Japan); Naka, Yuji [Chemical Resources Laboratory, Process Systems Engineering Division, Tokyo Institute of Technology, R1-19, 4259 Nagatsuta, Midori-ku Yokohama 226-8503 (Japan)
2007-03-15
When planning bioenergy production from biomass, planners should take into account each and every stakeholder along the biomass supply chains, e.g. biomass resources suppliers, transportation, conversion and electricity suppliers. Also, the planners have to consider social concerns, environmental and economical impacts related with establishing the biomass systems and the specific difficulties of each country. To overcome these problems in a sustainable manner, a robust decision support system is required. For that purpose, a two levels general Bioenergy Decision System (gBEDS) for bioenergy production planning and implementation was developed. The core part of the gBEDS is the information base, which includes the basic bioenergy information and the detailed decision information. Basic bioenergy information include, for instance, the geographical information system (GIS) database, the biomass materials' database, the biomass logistic database and the biomass conversion database. The detailed decision information considers the parameters' values database with their default values and the variables database, values obtained by simulation and optimization. It also includes a scenario database, which is used for demonstration to new users and also for case based reasoning by planners and executers. Based on the information base, the following modules are included to support decision making: the simulation module with graph interface based on the unit process (UP) definition and the genetic algorithms (GAs) methods for optimal decisions and the Matlab module for applying data mining methods (fuzzy C-means clustering and decision trees) to the biomass collection points, to define the location of storage and bioenergy conversion plants based on the simulation and optimization model developed of the whole life cycle of bioenergy generation. Furthermore, Matlab is used to set up a calculation model with crucial biomass planning parameters (e.g. costs, CO{sub 2
Interpreting Tree Ensembles with inTrees
Deng, Houtao
2014-01-01
Tree ensembles such as random forests and boosted trees are accurate but difficult to understand, debug and deploy. In this work, we provide the inTrees (interpretable trees) framework that extracts, measures, prunes and selects rules from a tree ensemble, and calculates frequent variable interactions. An rule-based learner, referred to as the simplified tree ensemble learner (STEL), can also be formed and used for future prediction. The inTrees framework can applied to both classification an...
Squeezing in the interaction of radiation with two-level atoms
Bandyopadhyay, Abir; Rai, Jagdish
1995-01-01
We propose a simple experimental procedure to produce squeezing and other non-classical properties like photon antibunching of radiation, and amplification without population inversion. The method also decreases the uncertainties of the angular-momentum quadratures representing the two-level atomic system in the interaction of the two-level atoms with quantized radiation.
Maximum Likelihood Analysis of a Two-Level Nonlinear Structural Equation Model with Fixed Covariates
Lee, Sik-Yum; Song, Xin-Yuan
2005-01-01
In this article, a maximum likelihood (ML) approach for analyzing a rather general two-level structural equation model is developed for hierarchically structured data that are very common in educational and/or behavioral research. The proposed two-level model can accommodate nonlinear causal relations among latent variables as well as effects…
Analysis of Bullwhip Effect for Two-level Supply Chain with Multi-distributed Centers
Institute of Scientific and Technical Information of China (English)
LirongCui
2004-01-01
The bullwhip effect is studied for two-level supply chain with multi-distributed centers. First the model for two-level supply chain with multi-distributed centers is established under some assumptions, then the mathematical description is given for it. Finally a simple example is showed to illustrate the results obtained in the paper.
Springer, Mark S; Gatesy, John
2016-01-01
grossly misaligned, and numerous loci with >50% missing data for taxa that are misplaced in their gene trees. These problems were compounded by inadequate tree searches with nearest neighbor interchange branch swapping and inadvertent application of substitution models that did not account for among-site rate heterogeneity. Sixty-six gene trees imply unrealistic deep coalescences that exceed 100 million years (MY). Gene trees that were obtained with better justified models and search parameters show large increases in both likelihood scores and congruence. Coalescence analyses based on a curated set of 413 improved gene trees and a superior coalescence method (ASTRAL) support a Scandentia (treeshrews)+Glires (rabbits, rodents) clade, contradicting one of the three primary systematic conclusions of Song et al. (2012). Robust support for a Perissodactyla+Carnivora clade within Laurasiatheria is also lost, contradicting a second major conclusion of this study. Song et al.'s (2012) MP-EST species tree provided the basis for circular simulations that led these authors to conclude that the multispecies coalescent accounts for 77% of the gene tree conflicts in their dataset, but many internal branches of their MP-EST tree are stunted by an order of magnitude or more due to wholesale gene tree reconstruction errors. An independent assessment of branch lengths suggests the multispecies coalescent accounts for ⩽ 15% of the conflicts among Song et al.'s (2012) 447 gene trees. Unfortunately, Song et al.'s (2012) flawed phylogenomic dataset has been used as a model for additional simulation work that suggests the superiority of shortcut coalescence methods relative to concatenation. Investigator error was passed on to the subsequent simulation studies, which also incorporated further logical errors that should be avoided in future simulation studies. Illegitimate branch length switches in the simulation routines unfairly protected coalescence methods from their Achilles' heel, high
National Audubon Society, New York, NY.
Included are an illustrated student reader, "The Story of Trees," a leaders' guide, and a large tree chart with 37 colored pictures. The student reader reviews several aspects of trees: a definition of a tree; where and how trees grow; flowers, pollination and seed production; how trees make their food; how to recognize trees; seasonal changes;…
Directory of Open Access Journals (Sweden)
Burak Omer Saracoglu
2016-03-01
Full Text Available Purpose: The electricity demand in Turkey has been increasing for a while. Hydropower is one of the major electricity generation types to compensate this electricity demand in Turkey. Private investors (domestic and foreign in the hydropower electricity generation sector have been looking for the most appropriate and satisfactory new private hydropower investment (PHPI options and opportunities in Turkey. This study aims to present a qualitative multi-attribute decision making (MADM model, that is easy, straightforward, and fast for the selection of the most satisfactory reasonable PHPI options during the very early investment stages (data and information poorness on projects. Design/methodology/approach: The data and information of the PHPI options was gathered from the official records on the official websites. A wide and deep literature review was conducted for the MADM models and for the hydropower industry. The attributes of the model were identified, selected, clustered and evaluated by the expert decision maker (EDM opinion and by help of an open source search results clustering engine (Carrot2 (helpful for also comprehension. The PHPI options were clustered according to their installed capacities main property to analyze the options in the most appropriate, decidable, informative, understandable and meaningful way. A simple clustering algorithm for the PHPI options was executed in the current study. A template model for the selection of the most satisfactory PHPI options was built in the DEXi (Decision EXpert for Education and the DEXiTree software. Findings: The basic attributes for the selection of the PHPI options were presented and afterwards the aggregate attributes were defined by the bottom-up structuring for the early investment stages. The attributes were also analyzed by help of Carrot2. The most satisfactory PHPI options in Turkey in the big options data set were selected for each PHPI options cluster by the EDM evaluations in
Privacy for Key-Trees with Adaptive Adversaries
Beye, M.; Veugen, P.J.M.
2011-01-01
Hash-lock authentication protocols for Radio Frequency IDentification (RFID) tags incur heavy search on the server. Key-trees have been proposed as a way to reduce search times, but because partial keys in such trees are shared, key compromise affects several tags. Butty´an [3] and Beye and Veugen [
Anonymity for key-trees with adaptive adversaries
Beye, M.; Veugen, P.J.M.
2012-01-01
Hash-lock authentication protocols for Radio Frequency IDentification (RFID) tags incur heavy search on the server. Key-trees have been proposed as a way to reduce search times, but because partial keys in such trees are shared, key compromise affects several tags. Buttyán [4] and Beye and Veugen [3
Directory of Open Access Journals (Sweden)
Eman M Dokla
Full Text Available This study provides a comprehensive computational procedure for the discovery of novel urea-based antineoplastic kinase inhibitors while focusing on diversification of both chemotype and selectivity pattern. It presents a systematic structural analysis of the different binding motifs of urea-based kinase inhibitors and the corresponding configurations of the kinase enzymes. The computational model depends on simultaneous application of two protocols. The first protocol applies multiple consecutive validated virtual screening filters including SMARTS, support vector-machine model (ROC = 0.98, Bayesian model (ROC = 0.86 and structure-based pharmacophore filters based on urea-based kinase inhibitors complexes retrieved from literature. This is followed by hits profiling against different extended electron distribution (XED based field templates representing different kinase targets. The second protocol enables cancericidal activity verification by using the algorithm of feature trees (Ftrees similarity searching against NCI database. Being a proof-of-concept study, this combined procedure was experimentally validated by its utilization in developing a novel series of urea-based derivatives of strong anticancer activity. This new series is based on 3-benzylbenzo[d]thiazol-2(3H-one scaffold which has interesting chemical feasibility and wide diversification capability. Antineoplastic activity of this series was assayed in vitro against NCI 60 tumor-cell lines showing very strong inhibition of GI(50 as low as 0.9 uM. Additionally, its mechanism was unleashed using KINEX™ protein kinase microarray-based small molecule inhibitor profiling platform and cell cycle analysis showing a peculiar selectivity pattern against Zap70, c-src, Mink1, csk and MeKK2 kinases. Interestingly, it showed activity on syk kinase confirming the recent studies finding of the high activity of diphenyl urea containing compounds against this kinase. Allover, the new series
Energy Technology Data Exchange (ETDEWEB)
Saracoglu, B.O.
2016-07-01
The electricity demand in Turkey has been increasing for a while. Hydropower is one of the major electricity generation types to compensate this electricity demand in Turkey. Private investors (domestic and foreign) in the hydropower electricity generation sector have been looking for the most appropriate and satisfactory new private hydropower investment (PHPI) options and opportunities in Turkey. This study aims to present a qualitative multi-attribute decision making (MADM) model, that is easy, straightforward, and fast for the selection of the most satisfactory reasonable PHPI options during the very early investment stages (data and information poorness on projects). The data and information of the PHPI options was gathered from the official records on the official websites. A wide and deep literature review was conducted for the MADM models and for the hydropower industry. The attributes of the model were identified, selected, clustered and evaluated by the expert decision maker (EDM) opinion and by help of an open source search results clustering engine (Carrot2) (helpful for also comprehension). The PHPI options were clustered according to their installed capacities main property to analyze the options in the most appropriate, decidable, informative, understandable and meaningful way. A simple clustering algorithm for the PHPI options was executed in the current study. A template model for the selection of the most satisfactory PHPI options was built in the DEXi (Decision EXpert for Education) and the DEXiTree software. The basic attributes for the selection of the PHPI options were presented and afterwards the aggregate attributes were defined by the bottom-up structuring for the early investment stages. The attributes were also analyzed by help of Carrot2. The most satisfactory PHPI options in Turkey in the big options data set were selected for each PHPI options cluster by the EDM evaluations in the DEXi. (Author)
Institute of Scientific and Technical Information of China (English)
许宪成; 张凌
2011-01-01
提出将基于HASH表的二叉排序树结构应用于高速网络数据包流的动态存储和检测,提高查找效率.以所研制原型网路处理器系统的IP分片重组、流缓存和TCP会话重组等经典模块为实例,分别给出了方案选择、理论分析和测试结果,并对具体实现进行了深入讨论.指出该结构对入侵检测、状态防火墙和流量监测等网络安全系统的构建更具借鉴价值.%With the wide application of network processor (NP) technology, the key algorithms and data structures arc of important significance for packet detection or flow storage and qucry. This paper proposes a general approach that uses HASH table-based binary search tree structure to implement classic components of NP-based security schemes : IP fragmentation reassembly, Flow cache and TCP session reassembly, etc. Both theoretical analysis and tests results confirrned that our adopted structure not only improves the lookup efficiency but also takes the advantage of insertion and deletion dynamically. Consequently, it can facilitate the design process of highperformance network processing systems, especially in case of building intrusion detection systems, stateful firewalls and traffic monitor systems.
Dokla, Eman M; Mahmoud, Amr H; Elsayed, Mohamed S A; El-Khatib, Ahmed H; Linscheid, Michael W; Abouzid, Khaled A
2012-01-01
This study provides a comprehensive computational procedure for the discovery of novel urea-based antineoplastic kinase inhibitors while focusing on diversification of both chemotype and selectivity pattern. It presents a systematic structural analysis of the different binding motifs of urea-based kinase inhibitors and the corresponding configurations of the kinase enzymes. The computational model depends on simultaneous application of two protocols. The first protocol applies multiple consecutive validated virtual screening filters including SMARTS, support vector-machine model (ROC = 0.98), Bayesian model (ROC = 0.86) and structure-based pharmacophore filters based on urea-based kinase inhibitors complexes retrieved from literature. This is followed by hits profiling against different extended electron distribution (XED) based field templates representing different kinase targets. The second protocol enables cancericidal activity verification by using the algorithm of feature trees (Ftrees) similarity searching against NCI database. Being a proof-of-concept study, this combined procedure was experimentally validated by its utilization in developing a novel series of urea-based derivatives of strong anticancer activity. This new series is based on 3-benzylbenzo[d]thiazol-2(3H)-one scaffold which has interesting chemical feasibility and wide diversification capability. Antineoplastic activity of this series was assayed in vitro against NCI 60 tumor-cell lines showing very strong inhibition of GI(50) as low as 0.9 uM. Additionally, its mechanism was unleashed using KINEX™ protein kinase microarray-based small molecule inhibitor profiling platform and cell cycle analysis showing a peculiar selectivity pattern against Zap70, c-src, Mink1, csk and MeKK2 kinases. Interestingly, it showed activity on syk kinase confirming the recent studies finding of the high activity of diphenyl urea containing compounds against this kinase. Allover, the new series, which is based on
Canfield, Elaine
2002-01-01
Describes a fifth-grade art activity that offers a new approach to creating pictures of Aspen trees. Explains that the students learned about art concepts, such as line and balance, in this lesson. Discusses the process in detail for creating the pictures. (CMK)
Ternary Tree and Memory-Efficient Huffman Decoding Algorithm
Directory of Open Access Journals (Sweden)
Pushpa R. Suri
2011-01-01
Full Text Available In this study, the focus was on the use of ternary tree over binary tree. Here, a new one pass Algorithm for Decoding adaptive Huffman ternary tree codes was implemented. To reduce the memory size and fasten the process of searching for a symbol in a Huffman tree, we exploited the property of the encoded symbols and proposed a memory efficient data structure to represent the codeword length of Huffman ternary tree. In this algorithm we tried to find out the staring and ending address of the code to know the length of the code. And then in second algorithm we tried to decode the ternary tree code using binary search method. In this algorithm we tried to find out the staring and ending address of the code to know the length of the code. And then in second algorithm we tried to decode the ternary tree code using binary search method.
Cluster Tree Based Hybrid Document Similarity Measure
Directory of Open Access Journals (Sweden)
M. Varshana Devi
2015-10-01
Full Text Available
FastTree 2--approximately maximum-likelihood trees for large alignments.
Directory of Open Access Journals (Sweden)
Morgan N Price
Full Text Available BACKGROUND: We recently described FastTree, a tool for inferring phylogenies for alignments with up to hundreds of thousands of sequences. Here, we describe improvements to FastTree that improve its accuracy without sacrificing scalability. METHODOLOGY/PRINCIPAL FINDINGS: Where FastTree 1 used nearest-neighbor interchanges (NNIs and the minimum-evolution criterion to improve the tree, FastTree 2 adds minimum-evolution subtree-pruning-regrafting (SPRs and maximum-likelihood NNIs. FastTree 2 uses heuristics to restrict the search for better trees and estimates a rate of evolution for each site (the "CAT" approximation. Nevertheless, for both simulated and genuine alignments, FastTree 2 is slightly more accurate than a standard implementation of maximum-likelihood NNIs (PhyML 3 with default settings. Although FastTree 2 is not quite as accurate as methods that use maximum-likelihood SPRs, most of the splits that disagree are poorly supported, and for large alignments, FastTree 2 is 100-1,000 times faster. FastTree 2 inferred a topology and likelihood-based local support values for 237,882 distinct 16S ribosomal RNAs on a desktop computer in 22 hours and 5.8 gigabytes of memory. CONCLUSIONS/SIGNIFICANCE: FastTree 2 allows the inference of maximum-likelihood phylogenies for huge alignments. FastTree 2 is freely available at http://www.microbesonline.org/fasttree.
Information Entropy. and Squeezing of Quantum Fluctuations in a Two-Level Atom
Institute of Scientific and Technical Information of China (English)
FANG Mao-Fa; ZHOU Peng; S. Swain
2000-01-01
We study the atomic squeezing in the language of the quantum information theory. A rigorous entropy uncertainty relation which suits for characterizing the squeezing of a two-level atoms is obtained, and a general definition of information entropy squeezing in the two-level atoms is given. The information entropy squeezing of two-level atoms interacting with a single-mode quantum field is examined. Our results show that the information entropy is a superior measure of the quantum uncertainty of atomic observable, also is a remarkable good precision measure of atomic squeezing. When the population difference of two-level atom is zero, the definition of atomic squeezing based on the Heisenberg uncertainty relation is trivial, while the definition of information entropy squeezing of the atom based on the entropy uncertainty relation is valid and can provide full information on the atomic squeezing in any cases.
Dispersion management for two-level optically labeled signals in IP-over-WDM networks 4
DEFF Research Database (Denmark)
Chi, Nan; Carlsson, Birger; Holm-Nielsen, Pablo Villanueva;
2002-01-01
The transmission characteristics of a two-level optically labeled signal with ASK/DPSK modulation are investigated under varying dispersion management. A limitation of extinction ratio and the resilience of fiber span, compensation ratio, and power level are obtained...
Unimodular trees versus Einstein trees
Energy Technology Data Exchange (ETDEWEB)
Alvarez, Enrique; Gonzalez-Martin, Sergio [Universidad Autonoma, Instituto de Fisica Teorica, IFT-UAM/CSIC, Madrid (Spain); Universidad Autonoma de Madrid, Departamento de Fisica Teorica, Madrid (Spain); Martin, Carmelo P. [Universidad Complutense de Madrid (UCM), Departamento de Fisica Teorica I Facultad de Ciencias Fisicas, Madrid (Spain)
2016-10-15
The maximally helicity violating tree-level scattering amplitudes involving three, four or five gravitons are worked out in Unimodular Gravity. They are found to coincide with the corresponding amplitudes in General Relativity. This a remarkable result, insofar as both the propagators and the vertices are quite different in the two theories. (orig.)
Unimodular Trees versus Einstein Trees
Alvarez, Enrique; Martin, Carmelo P
2016-01-01
The maximally helicity violating (MHV) tree level scattering amplitudes involving three, four or five gravitons are worked out in Unimodular Gravity. They are found to coincide with the corresponding amplitudes in General Relativity. This a remarkable result, insofar as both the propagators and the vertices are quite different in both theories.
Unimodular trees versus Einstein trees
Álvarez, Enrique; González-Martín, Sergio; Martín, Carmelo P.
2016-10-01
The maximally helicity violating tree-level scattering amplitudes involving three, four or five gravitons are worked out in Unimodular Gravity. They are found to coincide with the corresponding amplitudes in General Relativity. This a remarkable result, insofar as both the propagators and the vertices are quite different in the two theories.
Can Hare's two-level utilitarianism overcome the problems facing act-utilitarianism?
Roberts, Emma
2012-01-01
In order to provide a positive defence of utilitarianism, R.M Hare presented his own theory of 'two-level' utilitarianism, claiming that it overcame the main objections directed towards traditional act utilitarianism. This essay firstly outlines the main problems associated with utilitarianism and examines whether Hare's theory is indeed able to successfully overcome them. It then goes on to examine the coherence of two-level utilitarianism itself, and thus determine whether it can provide a ...
Two-Level Incremental Checkpoint Recovery Scheme for Reducing System Total Overheads
Li, Huixian; Pang, Liaojun; Wang, Zhangquan
2014-01-01
Long-running applications are often subject to failures. Once failures occur, it will lead to unacceptable system overheads. The checkpoint technology is used to reduce the losses in the event of a failure. For the two-level checkpoint recovery scheme used in the long-running tasks, it is unavoidable for the system to periodically transfer huge memory context to a remote stable storage. Therefore, the overheads of setting checkpoints and the re-computing time become a critical issue which directly impacts the system total overheads. Motivated by these concerns, this paper presents a new model by introducing i-checkpoints into the existing two-level checkpoint recovery scheme to deal with the more probable failures with the smaller cost and the faster speed. The proposed scheme is independent of the specific failure distribution type and can be applied to different failure distribution types. We respectively make analyses between the two-level incremental and two-level checkpoint recovery schemes with the Weibull distribution and exponential distribution, both of which fit with the actual failure distribution best. The comparison results show that the total overheads of setting checkpoints, the total re-computing time and the system total overheads in the two-level incremental checkpoint recovery scheme are all significantly smaller than those in the two-level checkpoint recovery scheme. At last, limitations of our study are discussed, and at the same time, open questions and possible future work are given. PMID:25111048
Which Spatial Partition Trees are Adaptive to Intrinsic Dimension?
Verma, Nakul; Dasgupta, Sanjoy
2012-01-01
Recent theory work has found that a special type of spatial partition tree - called a random projection tree - is adaptive to the intrinsic dimension of the data from which it is built. Here we examine this same question, with a combination of theory and experiments, for a broader class of trees that includes k-d trees, dyadic trees, and PCA trees. Our motivation is to get a feel for (i) the kind of intrinsic low dimensional structure that can be empirically verified, (ii) the extent to which a spatial partition can exploit such structure, and (iii) the implications for standard statistical tasks such as regression, vector quantization, and nearest neighbor search.
Performance of a Two-Level Call Admission Control Scheme for DS-CDMA Wireless Networks
Directory of Open Access Journals (Sweden)
Abraham O. Fapojuwo
2007-11-01
Full Text Available We propose a two-level call admission control (CAC scheme for direct sequence code division multiple access (DS-CDMA wireless networks supporting multimedia traffic and evaluate its performance. The first-level admission control assigns higher priority to real-time calls (also referred to as class 0 calls in gaining access to the system resources. The second level admits nonreal-time calls (or class 1 calls based on the resources remaining after meeting the resource needs for real-time calls. However, to ensure some minimum level of performance for nonreal-time calls, the scheme reserves some resources for such calls. The proposed two-level CAC scheme utilizes the delay-tolerant characteristic of non-real-time calls by incorporating a queue to temporarily store those that cannot be assigned resources at the time of initial access. We analyze and evaluate the call blocking, outage probability, throughput, and average queuing delay performance of the proposed two-level CAC scheme using Markov chain theory. The analytic results are validated by simulation results. The numerical results show that the proposed two-level CAC scheme provides better performance than the single-level CAC scheme. Based on these results, it is concluded that the proposed two-level CAC scheme serves as a good solution for supporting multimedia applications in DS-CDMA wireless communication systems.
Performance of a Two-Level Call Admission Control Scheme for DS-CDMA Wireless Networks
Directory of Open Access Journals (Sweden)
Fapojuwo Abraham O
2007-01-01
Full Text Available We propose a two-level call admission control (CAC scheme for direct sequence code division multiple access (DS-CDMA wireless networks supporting multimedia traffic and evaluate its performance. The first-level admission control assigns higher priority to real-time calls (also referred to as class 0 calls in gaining access to the system resources. The second level admits nonreal-time calls (or class 1 calls based on the resources remaining after meeting the resource needs for real-time calls. However, to ensure some minimum level of performance for nonreal-time calls, the scheme reserves some resources for such calls. The proposed two-level CAC scheme utilizes the delay-tolerant characteristic of non-real-time calls by incorporating a queue to temporarily store those that cannot be assigned resources at the time of initial access. We analyze and evaluate the call blocking, outage probability, throughput, and average queuing delay performance of the proposed two-level CAC scheme using Markov chain theory. The analytic results are validated by simulation results. The numerical results show that the proposed two-level CAC scheme provides better performance than the single-level CAC scheme. Based on these results, it is concluded that the proposed two-level CAC scheme serves as a good solution for supporting multimedia applications in DS-CDMA wireless communication systems.
Finite Sholander Trees, Trees, and their Betweenness
Chvátal, Vašek; Schäfer, Philipp Matthias
2011-01-01
We provide a proof of Sholander's claim (Trees, lattices, order, and betweenness, Proc. Amer. Math. Soc. 3, 369-381 (1952)) concerning the representability of collections of so-called segments by trees, which yields a characterization of the interval function of a tree. Furthermore, we streamline Burigana's characterization (Tree representations of betweenness relations defined by intersection and inclusion, Mathematics and Social Sciences 185, 5-36 (2009)) of tree betweenness and provide a relatively short proof.
Two-Level Stabilized Finite Volume Methods for Stationary Navier-Stokes Equations
Directory of Open Access Journals (Sweden)
Anas Rachid
2012-01-01
Full Text Available We propose two algorithms of two-level methods for resolving the nonlinearity in the stabilized finite volume approximation of the Navier-Stokes equations describing the equilibrium flow of a viscous, incompressible fluid. A macroelement condition is introduced for constructing the local stabilized finite volume element formulation. Moreover the two-level methods consist of solving a small nonlinear system on the coarse mesh and then solving a linear system on the fine mesh. The error analysis shows that the two-level stabilized finite volume element method provides an approximate solution with the convergence rate of the same order as the usual stabilized finite volume element solution solving the Navier-Stokes equations on a fine mesh for a related choice of mesh widths.
Quantum Otto engine of a two-level atom with single-mode fields.
Wang, Jianhui; Wu, Zhaoqi; He, Jizhou
2012-04-01
We establish a quantum Otto engine (QOE) of a two-level atom, which is confined in a one-dimensional (1D) harmonic trap and is coupled to single-mode radiation fields. Besides two adiabatic processes, the QOE cycle consists of two isochoric processes, along one of which the two-level atom as the working substance interacts with a single-mode radiation field. Based on the semigroup approach, we derive the time for completing any adiabatic process and then present a performance analysis of the heat engine model. Furthermore, we generalize the results to the performance optimization for a QOE of a single two-level atom trapped in a 1D power-law potential. Our result shows that the efficiency at maximum power output is dependent on the trap exponent θ but is independent of the energy spectrum index σ.
Open-Loop Control in Quantum Optics: Two-Level Atom in Modulated Optical Field
Saifullah, Sergei
2008-01-01
The methods of mathematical control theory are widely used in the modern physics, but still they are less popular in quantum science. We will discuss the aspects of control theory, which are the most useful in applications to the real problems of quantum optics. We apply this technique to control the behavior of the two-level quantum particles (atoms) in the modulated external optical field in the frame of the so called "semi classical model", where quantum two-level atomic system (all other levels are neglected) interacts with classical electromagnetic field. In this paper we propose a simple model of feedforward (open-loop) control for the quantum particle system, which is a basement for further investigation of two-level quantum particle in the external one-dimensional optical field.
Two-Level Solutions to Exponentially Complex Problems in Glass Science
DEFF Research Database (Denmark)
Mauro, John C.; Smedskjær, Morten Mattrup
Glass poses an especially challenging problem for physicists. The key to making progress in theoretical glass science is to extract the key physics governing properties of practical interest. In this spirit, we discuss several two-level solutions to exponentially complex problems in glass science....... Topological constraint theory, originally developed by J.C. Phillips, is based on a two-level description of rigid and floppy modes in a glass network and can be used to derive quantitatively accurate and analytically solvable models for a variety of macroscopic properties. The temperature dependence...... of the floppy mode density is used to derive the new MYEGA model of supercooled liquid viscosity, which offers improved descriptions for the temperature and composition dependence of relaxation time. The relaxation behavior of the glassy state can be further elucidated using a two-level energy landscape...
Quantum Otto engine of a two-level atom with single-mode fields
Wang, Jianhui; Wu, Zhaoqi; He, Jizhou
2012-04-01
We establish a quantum Otto engine (QOE) of a two-level atom, which is confined in a one-dimensional (1D) harmonic trap and is coupled to single-mode radiation fields. Besides two adiabatic processes, the QOE cycle consists of two isochoric processes, along one of which the two-level atom as the working substance interacts with a single-mode radiation field. Based on the semigroup approach, we derive the time for completing any adiabatic process and then present a performance analysis of the heat engine model. Furthermore, we generalize the results to the performance optimization for a QOE of a single two-level atom trapped in a 1D power-law potential. Our result shows that the efficiency at maximum power output is dependent on the trap exponent θ but is independent of the energy spectrum index σ.
Two-level hierarchical fragmentation in the northern filament of the Orion Molecular Cloud 1
Teixeira, P. S.; Takahashi, S.; Zapata, L. A.; Ho, P. T. P.
2016-03-01
-equidistant length of ≈30' (0.06 pc). This separation is dominated by the Jeans length and therefore indicates that the main physical process in the filament evolution was thermal fragmentation. Within the protostellar groups, the typical separation is ≈6'' (~2500 au), which is a factor 2-3 smaller than the Jeans length of the parental clumps within which the protostars are embedded. These results point to a hierarchical (two-level) thermal fragmentation process of the OMC 1n filament. The reduced continuun map (FITS file) is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/587/A47
A modified two-level three-phase quasi-soft-switching inverter
DEFF Research Database (Denmark)
Liu, Yusheng; Wu, Weimin; Blaabjerg, Frede;
2014-01-01
to reduce the extra conduction power loss and the voltage stress across the DC-link capacitor, a modified two-level three-phase quasi-soft-switching inverter is proposed by using a SiC MOSFET instead of an IGBT. The principle of the modified two-level three-phase quasi-soft-switching inverter is analyzed...... in detail. And the performance is verified through simulations and experiments on a 5 kW/380 V three-phase prototype....
Fundamentals of PV Efficiency Interpreted by a Two-Level Model
Alam, Muhammad A
2012-01-01
Elementary physics of photovoltaic energy conversion in a two-level atomic PV is considered. We explain the conditions for which the Carnot efficiency is reached and how it can be exceeded! The loss mechanisms - thermalization, angle entropy, and below-bandgap transmission - explain the gap between Carnot efficiency and the Shockley-Queisser limit. Wide varieties of techniques developed to reduce these losses (e.g., solar concentrators, solar-thermal, tandem cells, etc.) are reinterpreted by using a two level model. Remarkably, the simple model appears to capture the essence of PV operation and reproduce the key results and important insights that are known to the experts through complex derivations.
Design and Implementation of Two-Level Metadata Server in Small-Scale Cluster File System
Institute of Scientific and Technical Information of China (English)
LIU Yuling; YU Hongfen; SONG Weiwei
2006-01-01
The reliability and high performance of metadata service is crucial to the store architecture. A novel design of a two-level metadata server file system (TTMFS) is presented, which behaves high reliability and performance. The merits both centralized management and distributed management are considered simultaneously in our design. In this file system, the advanced-metadata server is responsible for manage directory metadata and the whole namespace. The double-metadata server is responsible for maintaining file metadata. And this paper uses the Markov return model to analyze the reliability of the two-level metadata server. The experiment data indicates that the design can provide high throughput.
Implementation of a Parallel Tree Method on a GPU
Nakasato, Naohito
2011-01-01
The kd-tree is a fundamental tool in computer science. Among other applications, the application of kd-tree search (by the tree method) to the fast evaluation of particle interactions and neighbor search is highly important, since the computational complexity of these problems is reduced from O(N^2) for a brute force method to O(N log N) for the tree method, where N is the number of particles. In this paper, we present a parallel implementation of the tree method running on a graphics processing unit (GPU). We present a detailed description of how we have implemented the tree method on a Cypress GPU. An optimization that we found important is localized particle ordering to effectively utilize cache memory. We present a number of test results and performance measurements. Our results show that the execution of the tree traversal in a force calculation on a GPU is practical and efficient.
Two-level Schwartz methods for nonconforming finite elements and discontinuous coefficients
Sarkis, Marcus
1993-01-01
Two-level domain decomposition methods are developed for a simple nonconforming approximation of second order elliptic problems. A bound is established for the condition number of these iterative methods, which grows only logarithmically with the number of degrees of freedom in each subregion. This bound holds for two and three dimensions and is independent of jumps in the value of the coefficients.
Two-Level Solutions to Exponentially Complex Problems in Glass Science
DEFF Research Database (Denmark)
Mauro, John C.; Smedskjær, Morten Mattrup
Glass poses an especially challenging problem for physicists. The key to making progress in theoretical glass science is to extract the key physics governing properties of practical interest. In this spirit, we discuss several two-level solutions to exponentially complex problems in glass science...
M Sakawa; Kato, K.
2009-01-01
This paper considers stochastic two-level linear programming problems. Using the concept of chance constraints and probability maximization, original problems are transformed into deterministic ones. An interactive fuzzy programming method is presented for deriving a satisfactory solution efficiently with considerations of overall satisfactory balance.
Eigenmode expansion of the polarization for a spherical sample of two-level atoms
Energy Technology Data Exchange (ETDEWEB)
Friedberg, Richard [Physics Department, Columbia University, New York, NY 10027 (United States); Manassah, Jamal T., E-mail: jmanassah@gmail.co [HMS Consultants, Inc., PO Box 592, New York, NY 10028 (United States)
2009-12-07
We derive pseudo-orthogonality relations for both the magnetic and electric eigenmodes of a system of two-level atoms in a sphere configuration. We verify numerically that an arbitrary vector field can be reconstructed to a great accuracy from these eigenmode expansions. We apply this eigenmode analysis to explore superradiance from a sphere with initially uniform polarization.
How to Calculate the Exact Angle for Two-level Osteotomy in Ankylosing Spondylitis?
Zheng, Guoquan; Song, Kai; Yao, Ziming; Zhang, Yonggang; Tang, Xiangyu; Wang, Zheng; Zhang, Xuesong; Mao, Keya; Cui, Geng; Wang, Yan
2016-09-01
A prospective case series study. To describe and assess a two-level osteotomy method for the management of severe thoracolumbar kyphosis (TLK) in patients with ankylosing spondylitis (AS). To achieve better postoperative outcomes in these patients, a sophisticated preoperative surgical plan is required. Most deformities are managed using a one-level osteotomy and a two-level osteotomy is seldomly reported. Till date, no study has described a two-level osteotomy for these cases. From January 2011 to December 2012, 10 consecutive patients with ankylosing spondylitis who underwent two-level spinal osteotomy were studied. Pre- and postoperative full-length free-standing radiographs, including the whole spine and pelvis, were available for all patients. Pre- and postoperative radiological parameters, including T5-S1 Cobb angles, TLK, lumbar lordosis, pelvic incidence, pelvic tilt, sacral slope, and sagittal vertical axis were measured. Health related quality of life , including Oswestry Disability Index and Scoliosis Research Society-22 surveys were administered before surgery and at 1-year follow up. The preoperative and postoperative T5-S1 Cobb angles was 51.3° and -7.1°, respectively (P osteotomy provides an accurate and reproducible method for ankylosing spondylitis correction. By which, we can obtain satisfactory radiological parameters and clinical outcomes. 4.
On the dependence of the two-level source function on its radiation field.
Steinitz, R.; Shine, R. A.
1973-01-01
The consequences of the universally made assumption that the stimulated emission profile is identical to the absorption profile are quantitatively investigated for a two-level atom with Doppler redistribution. The nonlinear terms arising in the source function are evaluated iteratively. We find that the magnitude of the effects is probably completely negligible for visible and UV solar lines.
Collective polaritonic modes in an array of two-level quantum emitters coupled to optical nanofiber
Kornovan, D F; Petrov, M I
2016-01-01
In this paper we develop a microscopic analysis of the light scattering on a periodic two-level atomic array coupled to an optical nanofiber. We extend the scattering matrix approach for two-level system interaction with nanofiber fundamental waveguiding mode HE_{11}, that allows us modeling the scattering spectra. We support these results considering the dispersion of the polaritonic states formed by the superposition of the fundamental mode of light HE_{11} and the atomic chain states. To illustrate our approach we start with considering a simple model of light scattering over atomic array in the free space. We discuss the Bragg diffraction at the atomic array and show that the scattering spectrum is defined by the non-symmetric coupling of two-level system with nanofiber and vacuum modes. The proposed method allows considering two-level systems interaction with full account for dipole-dipole interaction both via near fields and long-range interaction owing to nanofiber mode coupling.
The Two-Level System of Higher Education: Western Traditions and Russian Reality
Druzhilov, S. A.
2011-01-01
The law on the two-level system of higher education has now gone into effect in Russia: the bachelor's degree will correspond to the first level of higher education, while the master's degree will correspond to the second level. These levels entail separate state educational standards and separate final certification. In the process of adopting…
Experimental Research into the Two-Level Cylindrical Cyclone with a Different Number of Channels
Directory of Open Access Journals (Sweden)
Egidijus Baliukas
2014-10-01
Full Text Available The multichannel two-level cyclone has been designed for separating solid particles from airflow and built at the Laboratory of Environmental Protection Technologies of Vilnius Gediminas Technical University. The conducted research is aimed at determining air flow distribution at two levels and channels of the multichannel cyclone. The multifunctional meter Testo-400 and the dynamic Pitot tube have been used form easuring air flow rates in the channels. The obtained results show that the equal volume of air gets into two levels installed inside the cyclone, and rates are distributed equally in the channels of these levels. The maximum air flow rate is recorded in the first channel and occurs when half-rings are set in such positions so that 75% of air flow returns to the previous channel. The biggest aerodynamic resistance is 1660 Pa and has been recorded in the cyclone having eight channels under air flow distribution ratio 75/25. The highest air purification efficiency has been observed in the two-level six-channel cyclone under air flow distribution ratio 75/25. The effectiveness of separating granite particles is 92.1% and that of wood particles – 91.1 when the particles are up to 20 μm in diameter.
Psychological Corp., New York, NY.
Under the guidance of an advisory committee from the American Association for Respiratory Therapy (AART), The Psychological Corporation developed three forms of two criterion-referenced proficiency examinations to measure the skills, understandings, and knowledge required in entry level jobs for two levels of respiratory therapy personnel. The…
Reactive Power Impact on Lifetime Prediction of Two-level Wind Power Converter
DEFF Research Database (Denmark)
Zhou, Dao; Blaabjerg, Frede; Lau, M.
2013-01-01
The influence of reactive power injection on the dominating two-level wind power converter is investigated and compared in terms of power loss and thermal behavior. Then the lifetime of both the partial-scale and full-scale power converter is estimated based on the widely used Coffin-Manson model...
Exact Solution of the Two-Level System and the Einstein Solid in the Microcanonical Formalism
Bertoldi, Dalia S.; Bringa, Eduardo M.; Miranda, E. N.
2011-01-01
The two-level system and the Einstein model of a crystalline solid are taught in every course of statistical mechanics and they are solved in the microcanonical formalism because the number of accessible microstates can be easily evaluated. However, their solutions are usually presented using the Stirling approximation to deal with factorials. In…
A two-level stochastic collocation method for semilinear elliptic equations with random coefficients
Energy Technology Data Exchange (ETDEWEB)
Chen, Luoping; Zheng, Bin; Lin, Guang; Voulgarakis, Nikolaos
2017-05-01
In this work, we propose a novel two-level discretization for solving semilinear elliptic equations with random coefficients. Motivated by the two-grid method for deterministic partial differential equations (PDEs) introduced by Xu, our two-level stochastic collocation method utilizes a two-grid finite element discretization in the physical space and a two-level collocation method in the random domain. In particular, we solve semilinear equations on a coarse mesh $\\mathcal{T}_H$ with a low level stochastic collocation (corresponding to the polynomial space $\\mathcal{P}_{P}$) and solve linearized equations on a fine mesh $\\mathcal{T}_h$ using high level stochastic collocation (corresponding to the polynomial space $\\mathcal{P}_p$). We prove that the approximated solution obtained from this method achieves the same order of accuracy as that from solving the original semilinear problem directly by stochastic collocation method with $\\mathcal{T}_h$ and $\\mathcal{P}_p$. The two-level method is computationally more efficient, especially for nonlinear problems with high random dimensions. Numerical experiments are also provided to verify the theoretical results.
Broadband EM radiation amplification by means of a monochromatically driven two-level system
Soldatov, Andrey V.
2017-02-01
It is shown that a two-level quantum system possessing dipole moment operator with permanent non-equal diagonal matrix elements and driven by external semiclassical monochromatic high-frequency electromagnetic (EM) (laser) field can amplify EM radiation waves of much lower frequency.
DEFF Research Database (Denmark)
Bianchi, Federica; Hjortkjær, Jens; Santurette, Sébastien
2017-01-01
in pitch discrimination across all participants, but not within the musicians group alone. Only neural activity in the right auditory cortex scaled with the fine pitch-discrimination thresholds within the musicians. These findings suggest two levels of neuroplasticity in musicians, whereby training...
Time-Minimal Control of Dissipative Two-level Quantum Systems: the Generic Case
Bonnard, B; Sugny, D
2008-01-01
The objective of this article is to complete preliminary results concerning the time-minimal control of dissipative two-level quantum systems whose dynamics is governed by Lindblad equations. The extremal system is described by a 3D-Hamiltonian depending upon three parameters. We combine geometric techniques with numerical simulations to deduce the optimal solutions.
Constrained Maximum Likelihood Estimation for Two-Level Mean and Covariance Structure Models
Bentler, Peter M.; Liang, Jiajuan; Tang, Man-Lai; Yuan, Ke-Hai
2011-01-01
Maximum likelihood is commonly used for the estimation of model parameters in the analysis of two-level structural equation models. Constraints on model parameters could be encountered in some situations such as equal factor loadings for different factors. Linear constraints are the most common ones and they are relatively easy to handle in…
Time-minimal control of dissipative two-level quantum systems: The Integrable case
Bonnard, B
2008-01-01
The objective of this article is to apply recent developments in geometric optimal control to analyze the time minimum control problem of dissipative two-level quantum systems whose dynamics is governed by the Lindblad equation. We focus our analysis on the case where the extremal Hamiltonian is integrable.
DEFF Research Database (Denmark)
Bahr, Patrick
2012-01-01
Tree automata are traditionally used to study properties of tree languages and tree transformations. In this paper, we consider tree automata as the basis for modular and extensible recursion schemes. We show, using well-known techniques, how to derive from standard tree automata highly modular r...
David J. Nowak; Jeffrey T. Walton; James Baldwin; Jerry. Bond
2015-01-01
Information on street trees is critical for management of this important resource. Sampling of street tree populations provides an efficient means to obtain street tree population information. Long-term repeat measures of street tree samples supply additional information on street tree changes and can be used to report damages from catastrophic events. Analyses of...
DEFF Research Database (Denmark)
Bahr, Patrick
2012-01-01
Tree automata are traditionally used to study properties of tree languages and tree transformations. In this paper, we consider tree automata as the basis for modular and extensible recursion schemes. We show, using well-known techniques, how to derive from standard tree automata highly modular...
A two-level generative model for cloth representation and shape from shading.
Han, Feng; Zhu, Song-Chun
2007-07-01
In this paper, we present a two-level generative model for representing the images and surface depth maps of drapery and clothes. The upper level consists of a number of folds which will generate the high contrast (ridge) areas with a dictionary of shading primitives (for 2D images) and fold primitives (for 3D depth maps). These primitives are represented in parametric forms and are learned in a supervised learning phase using 3D surfaces of clothes acquired through photometric stereo. The lower level consists of the remaining flat areas which fill between the folds with a smoothness prior (Markov random field). We show that the classical ill-posed problem-shape from shading (SFS) can be much improved by this two-level model for its reduced dimensionality and incorporation of middle-level visual knowledge, i.e., the dictionary of primitives. Given an input image, we first infer the folds and compute a sketch graph using a sketch pursuit algorithm as in the primal sketch [10], [11]. The 3D folds are estimated by parameter fitting using the fold dictionary and they form the "skeleton" of the drapery/cloth surfaces. Then, the lower level is computed by conventional SFS method using the fold areas as boundary conditions. The two levels interact at the final stage by optimizing a joint Bayesian posterior probability on the depth map. We show a number of experiments which demonstrate more robust results in comparison with state-of-the-art work. In a broader scope, our representation can be viewed as a two-level inhomogeneous MRF model which is applicable to general shape-from-X problems. Our study is an attempt to revisit Marr's idea [23] of computing the 2(1/2)D sketch from primal sketch. In a companion paper [2], we study shape from stereo based on a similar two-level generative sketch representation.
Professional Microsoft search fast search, Sharepoint search, and search server
Bennett, Mark; Kehoe, Miles; Voskresenskaya, Natalya
2010-01-01
Use Microsoft's latest search-based technology-FAST search-to plan, customize, and deploy your search solutionFAST is Microsoft's latest intelligent search-based technology that boasts robustness and an ability to integrate business intelligence with Search. This in-depth guide provides you with advanced coverage on FAST search and shows you how to use it to plan, customize, and deploy your search solution, with an emphasis on SharePoint 2010 and Internet-based search solutions.With a particular appeal for anyone responsible for implementing and managing enterprise search, this book presents t
Airway Tree Extraction with Locally Optimal Paths
DEFF Research Database (Denmark)
Lo, Pechin Chien Pau; Sporring, Jon; Pedersen, Jesper Johannes Holst
2009-01-01
This paper proposes a method to extract the airway tree from CT images by continually extending the tree with locally optimal paths. This is in contrast to commonly used region growing based approaches that only search the space of the immediate neighbors. The result is a much more robust method...... for tree extraction that can overcome local occlusions. The cost function for obtaining the optimal paths takes into account of an airway probability map as well as measures of airway shape and orientation derived from multi-scale Hessian eigen analysis on the airway probability. Significant improvements...
Algorithms for optimal dyadic decision trees
Energy Technology Data Exchange (ETDEWEB)
Hush, Don [Los Alamos National Laboratory; Porter, Reid [Los Alamos National Laboratory
2009-01-01
A new algorithm for constructing optimal dyadic decision trees was recently introduced, analyzed, and shown to be very effective for low dimensional data sets. This paper enhances and extends this algorithm by: introducing an adaptive grid search for the regularization parameter that guarantees optimal solutions for all relevant trees sizes, revising the core tree-building algorithm so that its run time is substantially smaller for most regularization parameter values on the grid, and incorporating new data structures and data pre-processing steps that provide significant run time enhancement in practice.
... of this page: https://medlineplus.gov/cloud.html Search Cloud To use the sharing features on this ... of Top 110 zoster vaccine Share the MedlinePlus search cloud with your users by embedding our search ...
A Two-Level Undercut-Profile Substrate for Chemical-Solution-Based Filamentary Coated Conductors
DEFF Research Database (Denmark)
Wulff, Anders Christian; Lundeman, Jesper H.; Hansen, Jørn B.
2016-01-01
. In the present study, the 2LUPS concept is applied to a commercial cube-textured Ni-5at.% W tape, and the surface of the 2LUPS coated with two Gd2Zr2O7 buffer layers using chemical solution deposition is examined. Except for narrow regions near the edge of upper plateaus, the plateaus are found to be covered......A recently developed two-level undercut-profile substrate (2LUPS), containing two levels of plateaus connected by a curved wall with an undercut profile, enables self-forming filaments in a coated conductor during physical line-of-sight deposition of buffer and superconducting layers...... by strongly textured Gd2Zr2O7 buffer layers after dip coating and sintering....
Dynamical decoherence in a cavity with a large number of two-level atoms
Frasca, M
2004-01-01
We consider a large number of two-level atoms interacting with the mode of a cavity in the rotating-wave approximation (Tavis-Cummings model). We apply the Holstein-Primakoff transformation to study the model in the limit of the number of two-level atoms, all in their ground state, becoming very large. The unitary evolution that we obtain in this approximation is applied to a macroscopic superposition state showing that, when the coherent states forming the superposition are enough distant, then the state collapses on a single coherent state describing a classical radiation mode. This appear as a true dynamical effect that could be observed in experiments with cavities.
Two-Level Bregman Method for MRI Reconstruction with Graph Regularized Sparse Coding
Institute of Scientific and Technical Information of China (English)
刘且根; 卢红阳; 张明辉
2016-01-01
In this paper, a two-level Bregman method is presented with graph regularized sparse coding for highly undersampled magnetic resonance image reconstruction. The graph regularized sparse coding is incorporated with the two-level Bregman iterative procedure which enforces the sampled data constraints in the outer level and up-dates dictionary and sparse representation in the inner level. Graph regularized sparse coding and simple dictionary updating applied in the inner minimization make the proposed algorithm converge with a relatively small number of iterations. Experimental results demonstrate that the proposed algorithm can consistently reconstruct both simulated MR images and real MR data efficiently, and outperforms the current state-of-the-art approaches in terms of visual comparisons and quantitative measures.
Photon-statistics excitation spectroscopy of a single two-level system
Strauß, Max; Placke, Marlon; Kreinberg, Sören; Schneider, Christian; Kamp, Martin; Höfling, Sven; Wolters, Janik; Reitzenstein, Stephan
2016-06-01
We investigate the influence of the photon statistics on the excitation dynamics of a single two-level system. A single semiconductor quantum dot represents the two-level system and is resonantly excited either with coherent laser light, or excited with chaotic light, with photon statistics corresponding to that of thermal radiation. Experimentally, we observe a reduced absorption cross section under chaotic excitation in the steady state. In the transient regime, the Rabi oscillations observable under coherent excitation disappear under chaotic excitation. Likewise, in the emission spectrum, the well-known Mollow triplet, which we observe under coherent drive, disappears under chaotic excitation. Our observations are fully consistent with theoretical predictions based on the semiclassical Bloch equation approach.
A novel two-level dielectric barrier discharge reactor for methyl orange degradation.
Tao, Xumei; Wang, Guowei; Huang, Liang; Ye, Qingguo; Xu, Dongyan
2016-12-15
A novel pilot two-level dielectric barrier discharge (DBD) reactor has been proposed and applied for degradation of continuous model wastewater. The two-level DBD reactor was skillfully realized with high space utilization efficiency and large contact area between plasma and wastewater. Various conditions such as applied voltage, initial concentration and initial pH value on methyl orange (MO) model wastewater degradation were investigated. The results showed that the appropriate applied voltage was 13.4 kV; low initial concentration and low initial pH value were conducive for MO degradation. The percentage removal of 4 L MO with concentration of 80 mg/L reached 94.1% after plasma treatment for 80min. Based on ultraviolet spectrum (UV), Infrared spectrum (IR), liquid chromatography-mass spectrometry (LC-MS) analysis of degradation intermediates and products, insights in the degradation pathway of MO were proposed.
Semiclassical electrodynamics of alien atoms in interacting media II. Two-level systems
Elçi, Ahmet
1985-03-01
The previously developed self-consistent mean field theory of atoms entering an interacting medium is specialized to two-level alien atoms. It is shown that the medium may invert or split the original two levels, and that there is an intimate connection between the dressed atom spectrum and the statistical nature of the ensemble of alien atoms in the self-consistent mean field approximation. The optical susceptibility of alien atoms while inside the medium is calculated, and the lineshape and position of the optical resonance are shown to depend on the intensity of the optical field applied. There may be more than one phase possible for the atomic ensemble as a result of optical excitation.
Photon-Statistics Excitation Spectroscopy of a Single Two Level System
Strauß, M; Kreinberg, S; Schneider, C; Kamp, M; Höfling, S; Wolters, J; Reitzenstein, S
2016-01-01
We investigate the influence of the photon statistics on the excitation dynamics of a single two level system. A single semiconductor quantum dot represents the two level system and is resonantly excited either with coherent laser light, or excited with chaotic light, with photon statistics corresponding to that of thermal radiation. Experimentally, we observe a reduced absorption cross-section under chaotic excitation in the steady-state. In the transient regime, the Rabi oscillations observable under coherent excitation disappear under chaotic excitation. Likewise, in the emission spectrum the well-known Mollow triplet, which we observe under coherent drive, disappears under chaotic excitation. Our observations are fully consistent with theoretical predictions based on the semi-classical Bloch equation approach.
Quantum transport in a two-level quantum dot driven by coherent and stochastic fields
Ke, Sha-Sha; Miao, Ling-E.; Guo, Zhen; Guo, Yong; Zhang, Huai-Wu; Lü, Hai-Feng
2016-12-01
We study theoretically the current and shot noise properties flowing through a two-level quantum dot driven by a strong coherent field and a weak stochastic field. The interaction x(t) between the quantum dot and the stochastic field is assumed to be a Gaussian-Markovian random process with zero mean value and correlation function = Dκe - κ | t - t ‧ | , where D and κ are the strength and bandwidth of the stochastic field, respectively. It is found that the stochastic field could enhance the resonant effect between the quantum dot and the coherent field, and generate new resonant points. At the resonant points, the state population difference between two levels is suppressed and the current is considerably enhanced. The zero-frequency shot noise of the current varies dramatically between sub- and super-Poissonian characteristics by tuning the stochastic field appropriately.
A DISCRETE TIME TWO-LEVEL MIXED SERVICE PARALLEL POLLING MODEL
Institute of Scientific and Technical Information of China (English)
Guan Zheng; Zhao Dongfeng; Zhao Yifan
2012-01-01
We present a discrete time single-server two-level mixed service polling systems with two queue types,one center queue and N normal queues.Two-level means the center queue will be successive served after each normal queue.In the first level,server visits between the center queue and the normal queue.In the second level,normal queues are polled by a cyclic order.Mixed service means the service discipline are exhaustive for center queue,and parallel i-limited for normal queues.We propose an imbedded Markov chain framework to drive the closed-form expressions for the mean cycle time,mean queue length,and mean waiting time.Numerical examples demonstrate that theoretical and simulation results are identical the new system efficiently differentiates priorities.
Theoretical treatment of the interaction between two-level atoms and periodic waveguides
Zang, Xiaorun
2015-01-01
Light transport in periodic waveguides coupled to a two-level atom is investigated. By using optical Bloch equations and a photonic modal formalism, we derive semi-analytical expressions for the scattering matrix of one atom trapped in a periodic waveguide. The derivation is general, as the expressions hold for any periodic photonic or plasmonic waveguides. It provides a basic building block to study collective effects arising from photon-mediated multi-atom interactions in periodic waveguides.
Weak-Coupling Theory for Low-Frequency Periodically Driven Two-Level Systems
Institute of Scientific and Technical Information of China (English)
CHEN Ai-Xi; HUANG Ke-Lin; WANG Zhi-Ping
2008-01-01
We generalize the Wu-Yang strong-coupling theory to solve analytically periodically driven two-level systems in the weak-coupling and low-frequency regimes for single- and multi-period periodic driving of continuous-wave-type and pulse-type including ultrashort pulses of a few cycles. We also derive a general formula of the AC Stark shift suitable for such diverse situations.
Transmission Dynamics of a Driven Two-Level System Dissipated by Leads
Institute of Scientific and Technical Information of China (English)
ZHANG Ping; FAN Wen-Bin; ZHAO Xian-Geng
2001-01-01
We study the transmission dynamics of a driven two-level system dissipated by the two leads. Using the nonequilibrium Green function, we derive an analytical transmission formula for an electron incident from the left lead,through the double quantum dots, to the right lead. The Landauer-type conductance and current are also given.A discussion of the internal tunnelling dynamics reveals crucial effects of the localization and delocalization on the transport of the system.
Spontaneously induced atom-radiation entanglement in an ensemble of two-level atoms
Tesfa, Sintayehu
2007-01-01
Analysis of the spontaneously induced correlation on atom-radiation entanglement in an ensemble of two-level atoms initially prepared in the upper level and placed in a cavity containing a squeezed radiation employing the method of evaluating the coherent-state propagator is presented. It is found that the cavity radiation exhibits squeezing which is directly attributed to the squeezed radiation in the cavity. The intensity of the cavity radiation increases with the squeeze parameter and inte...
Some studies of the interaction between N-two level atoms and three level atom
Directory of Open Access Journals (Sweden)
D.A.M. Abo-Kahla
2016-07-01
Full Text Available In this paper, we present the analytical solution for the model that describes the interaction between a three level atom and two systems of N-two level atoms. The effect of the quantum numbers on the atomic inversion and the purity, for some special cases of the initial states, are investigated. We observe that the atomic inversion and the purity change remarkably by the change of the quantum numbers.
Total Quantum Zeno effect and Intelligent States for a two level system in a squeezed bath
Mundarain, D; Stephany, J
2006-01-01
In this work we show that by frequent measurements of adequately chosen observables, a complete suppression of the decay in an exponentially decaying two level system interacting with a squeezed bath is obtained. The observables for which the effect is observed depend on the the squeezing parameters of the bath. The initial states which display Total Zeno Effect are intelligent states of two conjugate observables associated to the electromagnetic fluctuations of the bath.
Directory of Open Access Journals (Sweden)
Dolean Victorita
2014-07-01
Full Text Available Multiphase, compositional porous media flow models lead to the solution of highly heterogeneous systems of Partial Differential Equations (PDE. We focus on overlapping Schwarz type methods on parallel computers and on multiscale methods. We present a coarse space [Nataf F., Xiang H., Dolean V., Spillane N. (2011 SIAM J. Sci. Comput. 33, 4, 1623-1642] that is robust even when there are such heterogeneities. The two-level domain decomposition approach is compared to multiscale methods.
The Cost of Cache-Oblivious Searching
DEFF Research Database (Denmark)
Bender, Michael A.; Brodal, Gert Stølting; Fagerberg, Rolf
2003-01-01
Tight bounds on the cost of cache-oblivious searching are proved. It is shown that no cache-oblivious search structure can guarantee that a search performs fewer than lg e log B N block transfers between any two levels of the memory hierarchy. This lower bound holds even if all of the block sizes......, multilevel memory hierarchies can be modelled. It is shown that as k grows, the search costs of the optimal k-level DAM search structure and of the optimal cache-oblivious search structure rapidly converge. This demonstrates that for a multilevel memory hierarchy, a simple cache-oblivious structure almost...
Directory of Open Access Journals (Sweden)
Gisela C V Ramadas
Full Text Available This paper addresses the challenging task of computing multiple roots of a system of nonlinear equations. A repulsion algorithm that invokes the Nelder-Mead (N-M local search method and uses a penalty-type merit function based on the error function, known as 'erf', is presented. In the N-M algorithm context, different strategies are proposed to enhance the quality of the solutions and improve the overall efficiency. The main goal of this paper is to use a two-level factorial design of experiments to analyze the statistical significance of the observed differences in selected performance criteria produced when testing different strategies in the N-M based repulsion algorithm. The main goal of this paper is to use a two-level factorial design of experiments to analyze the statistical significance of the observed differences in selected performance criteria produced when testing different strategies in the N-M based repulsion algorithm.
Ramadas, Gisela C V; Rocha, Ana Maria A C; Fernandes, Edite M G P
2015-01-01
This paper addresses the challenging task of computing multiple roots of a system of nonlinear equations. A repulsion algorithm that invokes the Nelder-Mead (N-M) local search method and uses a penalty-type merit function based on the error function, known as 'erf', is presented. In the N-M algorithm context, different strategies are proposed to enhance the quality of the solutions and improve the overall efficiency. The main goal of this paper is to use a two-level factorial design of experiments to analyze the statistical significance of the observed differences in selected performance criteria produced when testing different strategies in the N-M based repulsion algorithm. The main goal of this paper is to use a two-level factorial design of experiments to analyze the statistical significance of the observed differences in selected performance criteria produced when testing different strategies in the N-M based repulsion algorithm.
Automatic Detection of Cervical Cancer Cells by a Two-Level Cascade Classification System
Directory of Open Access Journals (Sweden)
Jie Su
2016-01-01
Full Text Available We proposed a method for automatic detection of cervical cancer cells in images captured from thin liquid based cytology slides. We selected 20,000 cells in images derived from 120 different thin liquid based cytology slides, which include 5000 epithelial cells (normal 2500, abnormal 2500, lymphoid cells, neutrophils, and junk cells. We first proposed 28 features, including 20 morphologic features and 8 texture features, based on the characteristics of each cell type. We then used a two-level cascade integration system of two classifiers to classify the cervical cells into normal and abnormal epithelial cells. The results showed that the recognition rates for abnormal cervical epithelial cells were 92.7% and 93.2%, respectively, when C4.5 classifier or LR (LR: logical regression classifier was used individually; while the recognition rate was significantly higher (95.642% when our two-level cascade integrated classifier system was used. The false negative rate and false positive rate (both 1.44% of the proposed automatic two-level cascade classification system are also much lower than those of traditional Pap smear review.
Two-level, two-objective evolutionary algorithms for solving unit commitment problems
Energy Technology Data Exchange (ETDEWEB)
Georgopoulou, Chariklia A.; Giannakoglou, Kyriakos C. [National Technical University of Athens, School of Mechanical Engineering, Laboratory of Thermal Turbomachines, Parallel CFD and Optimization Unit, P.O. Box 64069, Athens 157 10 (Greece)
2009-07-15
A two-level, two-objective optimization scheme based on evolutionary algorithms (EAs) is proposed for solving power generating Unit Commitment (UC) problems by considering stochastic power demand variations. Apart from the total operating cost to cover a known power demand distribution over the scheduling horizon, which is the first objective, the risk of not fulfilling possible demand variations forms the second objective to be minimized. For this kind of problems with a high number of decision variables, conventional EAs become inefficient optimization tools, since they require a high number of evaluations before reaching the optimal solution(s). To considerably reduce the computational burden, a two-level algorithm is proposed. At the low level, a coarsened UC problem is defined and solved using EAs to locate promising solutions at low cost: a strategy for coarsening the UC problem is proposed. Promising solutions migrate upwards to be injected into the high level EA population for further refinement. In addition, at the high level, the scheduling horizon is partitioned in a small number of subperiods of time which are optimized iteratively using EAs, based on objective function(s) penalized to ensure smooth transition from/to the adjacent subperiods. Handling shorter chromosomes due to partitioning increases method's efficiency despite the need for iterating. The proposed two-level method and conventional EAs are compared on representative test problems. (author)
Coupling of effective one-dimensional two-level atoms to squeezed light
Clark, S; Clark, Stephen; Parkins, Scott
2002-01-01
A cavity QED system is analyzed which duplicates the dynamics of a two-level atom in free space interacting exclusively with broadband squeezed light. We consider atoms in a three or four-level Lambda-configuration coupled to a high-finesse optical cavity which is driven by a squeezed light field. Raman transitions are induced between a pair of stable atomic ground states via the squeezed cavity mode and coherent driving fields. An analysis of the reduced master equation for the atomic ground states shows that a three-level atomic system has insufficient parameter flexibility to act as an effective two-level atom interacting exclusively with a squeezed reservoir. However, the inclusion of a fourth atomic level, coupled dispersively to one of the two ground states by an auxiliary laser field, introduces an extra degree of freedom and enables the desired interaction to be realised. As a means of detecting the reduced quadrature decay rate of the effective two-level system, we examine the transmission spectrum o...
Two-level total disc replacement with Mobi-C(r over 3-years
Directory of Open Access Journals (Sweden)
Reginald Davis
2014-01-01
Full Text Available Objective: To evaluate the safety and effectiveness of two-level total disc replacement (TDR using a Mobi-C(r Cervical Artificial Disc at the 36 month follow-up. Methods: a Prospective, randomized, controlled, multicenter clinical trial of an artificial cervical disc (Mobi-C(r Cervical Artificial Disc was conducted under the Investigational Device Exemptions (IDE and the U.S. Food & Drug Administration (FDA regulations. A total of 339 patients with degenerative disc disease were enrolled to receive either two-level treatment with TDR, or a two-level anterior cervical discectomy and fusion (ACDF as control. The 234 TDR patients and 105 ACDF patients were followed up at regular time points for three years after surgery. Results: At 36 months, both groups demonstrated an improvement in clinical outcome measures and a comparable safety profile. NDI scores, SF-12 PCS scores, patient satisfaction, and overall success indicated greater statistically significant improvement from baseline for the TDR group, in comparison to the ACDF group. The TDR patients experienced lower subsequent surgery rates and a lower rate of adjacent segment degeneration. On average, the TDR patients maintained segmental range of motion through 36 months with no device failure. Conclusion: Results at three-years support TDR as a safe, effective and statistically superior alternative to ACDF for the treatment of degenerative disc disease at two contiguous cervical levels.
Energy Technology Data Exchange (ETDEWEB)
Tan, Xinsheng [National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093 (China); Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas 66045 (United States); Yu, Haifeng, E-mail: hfyu@nju.edu.cn; Yu, Yang, E-mail: yuyang@nju.edu.cn [National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093 (China); Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Han, Siyuan [Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas 66045 (United States)
2015-09-07
We demonstrate a fast method to detect microscopic two-level systems in a superconducting phase qubit. By monitoring the population leak after sweeping the qubit bias flux, we are able to measure the two-level systems that are coupled with the qubit. Compared with the traditional method that detects two-level systems by energy spectroscopy, our method is faster and more sensitive. This method supplies a useful tool to investigate two-level systems in solid-state qubits.
Fast Structural Search in Phylogenetic Databases
Directory of Open Access Journals (Sweden)
William H. Piel
2005-01-01
Full Text Available As the size of phylogenetic databases grows, the need for efficiently searching these databases arises. Thanks to previous and ongoing research, searching by attribute value and by text has become commonplace in these databases. However, searching by topological or physical structure, especially for large databases and especially for approximate matches, is still an art. We propose structural search techniques that, given a query or pattern tree P and a database of phylogenies D, find trees in D that are sufficiently close to P . The “closeness” is a measure of the topological relationships in P that are found to be the same or similar in a tree D in D. We develop a filtering technique that accelerates searches and present algorithms for rooted and unrooted trees where the trees can be weighted or unweighted. Experimental results on comparing the similarity measure with existing tree metrics and on evaluating the efficiency of the search techniques demonstrate that the proposed approach is promising
Barking up the wrong tree: injuries due to falls from trees in Solomon Islands.
Negin, Joel; Vizintin, Pavle; Houasia, Patrick; Martiniuk, Alexandra L C
2014-12-11
To investigate tree-related injuries in Solomon Islands by the types of trees involved, who is affected and the types of injuries caused. Descriptive case series of all cases of injuries related to trees presenting to the National Referral Hospital in Honiara from 1994 to 2011. Data were collected by the attending clinician using a Trauma Epidemiology form, which provides information on age, sex, cause of injury and type of fracture. Number of injuries by tree type, sex and age. Of the 7651 injuries in the database, 1107 (14%) were caused by falls from trees. Falls from coconut trees led to the highest number of injuries, followed by falls from mango, guava, apple and nut trees. Overall, 85% of injuries occurred in individuals aged injuries involving guava trees, 77% of patients were aged injuries occurred among males. Of all injuries, 92% were fractures, 3% were dislocations and 5% were non-fracture, non-dislocation injuries. The arm (including wrist, elbow and hand) was the most common location of injury across all tree types. Distal radius fractures in the forearm were particularly common, as were ulna fractures. While mangos and guavas are undeniably delicious, the quest for their flesh can be hazardous. Children will always climb trees, but the search for food among children in lower-income settings may lead to higher rates of injury.
Efficient suffix trees on secondary storage
Energy Technology Data Exchange (ETDEWEB)
Clark, D.R.; Munro, J.I. [Univ. of Waterloo, Ontario (Canada)
1996-12-31
We present a new representation for suffix trees, a data structure used in full text searching, that uses little more storage than the log n bits per index point required to store the list of index points. We also show algorithms for maintaining the structure on secondary storage in such a way that we minimize the number of disk accesses while searching and we can efficiently handle changes to the text. Using this new representation, suffix trees are competitive in terms of space with, and actually offer significantly better performance than, existing methods for full text searching. While we present new algorithms and data structures in this paper, the emphasis is on practical searching methods that have been empirically verified against real data.
Luo, Chaomin; Krishnan, Mohan; Paulik, Mark; Cui, Bo; Zhang, Xingzhong
2013-12-01
In this paper, a two-level LIDAR-driven hybrid approach is proposed for real-time unmanned ground vehicle navigation and map building. Top level is newly designed enhanced Voronoi Diagram (EVD) method to plan a global trajectory for an unmanned vehicle. Bottom level employs Vector Field Histogram (VFH) algorithm based on the LIDAR sensor information to locally guide the vehicle under complicated workspace, in which it autonomously traverses from one node to another within the planned EDV with obstacle avoidance. To find the least-cost path within the EDV, novel distance and angle based search heuristic algorithms are developed, in which the cost of an edge is the risk of traversing the edge. An EVD is first constructed based on the environment, which is utilized to generate the initial global trajectory with obstacle avoidance. The VFH algorithm is employed to guide the vehicle to follow the path locally. Its effectiveness and efficiency of real-time navigation and map building for unmanned vehicles have been successfully validated by simulation studies and experiments. The proposed approach is successfully experimented on an actual unmanned vehicle to demonstrate the real-time navigation and map building performance of the proposed method. The vehicle appears to follow a very stable path while navigating through various obstacles.
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Morville, Peter
2010-01-01
What people are saying about Search Patterns "Search Patterns is a delight to read -- very thoughtful and thought provoking. It's the most comprehensive survey of designing effective search experiences I've seen." --Irene Au, Director of User Experience, Google "I love this book! Thanks to Peter and Jeffery, I now know that search (yes, boring old yucky who cares search) is one of the coolest ways around of looking at the world." --Dan Roam, author, The Back of the Napkin (Portfolio Hardcover) "Search Patterns is a playful guide to the practical concerns of search interface design. It cont
Learning Type Extension Trees for Metal Bonding State Prediction
DEFF Research Database (Denmark)
Frasconi, Paolo; Jaeger, Manfred; Passerini, Andrea
2008-01-01
Type Extension Trees (TET) have been recently introduced as an expressive representation language allowing to encode complex combinatorial features of relational entities. They can be efficiently learned with a greedy search strategy driven by a generalized relational information gain...
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
Healthy trees are important to us all. Trees provide shade, beauty, and homes for wildlife. Trees give us products like paper and wood. Trees can give us all this only if they are healthy.They must be well cared for to remain healthy.
Species tree inference by minimizing deep coalescences.
Directory of Open Access Journals (Sweden)
Cuong Than
2009-09-01
Full Text Available In a 1997 seminal paper, W. Maddison proposed minimizing deep coalescences, or MDC, as an optimization criterion for inferring the species tree from a set of incongruent gene trees, assuming the incongruence is exclusively due to lineage sorting. In a subsequent paper, Maddison and Knowles provided and implemented a search heuristic for optimizing the MDC criterion, given a set of gene trees. However, the heuristic is not guaranteed to compute optimal solutions, and its hill-climbing search makes it slow in practice. In this paper, we provide two exact solutions to the problem of inferring the species tree from a set of gene trees under the MDC criterion. In other words, our solutions are guaranteed to find the tree that minimizes the total number of deep coalescences from a set of gene trees. One solution is based on a novel integer linear programming (ILP formulation, and another is based on a simple dynamic programming (DP approach. Powerful ILP solvers, such as CPLEX, make the first solution appealing, particularly for very large-scale instances of the problem, whereas the DP-based solution eliminates dependence on proprietary tools, and its simplicity makes it easy to integrate with other genomic events that may cause gene tree incongruence. Using the exact solutions, we analyze a data set of 106 loci from eight yeast species, a data set of 268 loci from eight Apicomplexan species, and several simulated data sets. We show that the MDC criterion provides very accurate estimates of the species tree topologies, and that our solutions are very fast, thus allowing for the accurate analysis of genome-scale data sets. Further, the efficiency of the solutions allow for quick exploration of sub-optimal solutions, which is important for a parsimony-based criterion such as MDC, as we show. We show that searching for the species tree in the compatibility graph of the clusters induced by the gene trees may be sufficient in practice, a finding that helps
Sato, Shinji
2015-01-01
Characteristics of the 2011 Tohoku Tsunami have been revealed by collaborative tsunami surveys extensively performed under the coordination of the Joint Tsunami Survey Group. The complex behaviors of the mega-tsunami were characterized by the unprecedented scale and the low occurrence frequency. The limitation and the performance of tsunami countermeasures were described on the basis of tsunami surveys, laboratory experiments and numerical analyses. These findings contributed to the introduction of two-level tsunami hazards to establish a new strategy for tsunami disaster mitigation, combining structure-based flood protection designed by the Level-1 tsunami and non-structure-based damage reduction planned by the Level-2 tsunami.
Thermal analysis of multi-MW two-level wind power converter
Zhou, Dao; Blaabjerg, Frede; Mogens, Lau; Tonnes, Michael
2012-01-01
In this paper, the multi-MW wind turbine of partial-scale and full-scale two-level power converter with DFIG and direct-drive PMSG are designed and compared in terms of their thermal performance. Simulations of different configurations regarding loss distribution and junction temperature in the power device in the whole range of wind speed are presented and analyzed. It is concluded that in both partial-scale and full-scale power converter the most thermal stressed power device in the generat...
Ultra-short, off-resonant, strong excitation of two-level systems
Jha, Pankaj K; Grazioso, Fabio
2013-01-01
We present a model describing the use of ultra-short strong pulses to populate the excited level of a two-level quantum system. In particular, we study an off-resonance excitation with a few cycles pulse which presents a smooth phase jump i.e. a change of the pulse's phase which is not step-like, but happens over a finite time interval. A numerical solution is given for the time-dependent probability amplitude of the excited level. The enhancement of the excited level's population is optimized with respect to the shape of the phase transient, and to other parameters of the excitation pulse.
Enhancing student learning of two-level quantum systems with interactive simulations
Kohnle, Antje; Campbell, Anna; Korolkova, Natalia; Paetkau, Mark J
2015-01-01
The QuVis Quantum Mechanics Visualization project aims to address challenges of quantum mechanics instruction through the development of interactive simulations for the learning and teaching of quantum mechanics. In this article, we describe evaluation of simulations focusing on two-level systems developed as part of the Institute of Physics Quantum Physics resources. Simulations are research-based and have been iteratively refined using student feedback in individual observation sessions and in-class trials. We give evidence that these simulations are helping students learn quantum mechanics concepts at both the introductory and advanced undergraduate level, and that students perceive simulations to be beneficial to their learning.
Miao, Qiang; Zheng, Yujun
2016-06-29
In this paper, the nature of the multi-order resonance and coherent destruction of tunneling (CDT) for two-level system driven cross avoided crossing is investigated by employing the emitted photons 〈N〉 and the Mandel's Q parameter based on the photon counting statistics. An asymmetric feature of CDT is shown in the spectrum of Mandel's Q parameter. Also, the CDT can be employed to suppress the spontaneous decay and prolong waiting time noticeably. The photon emission pattern is of monotonicity in strong relaxation, and homogeneity in pure dephasing regime, respectively.
Intrinsic decoherence in the interaction of two fields with a two-level atom
Energy Technology Data Exchange (ETDEWEB)
Juarez-Amaro, R. [Universidad Tecnologica de la Mixteca, Mexico (Mexico); INAOE, Puebla (Mexico); Escudero-Jimenez, J.L. [INAOE, Puebla (Mexico); Moya-Cessa, H.
2009-06-15
We study the interaction of a two-level atom and two fields, one of them classical. We obtain an effective Hamiltonian for this system by using a method recently introduced that produces a small rotation to the Hamiltonian that allows to neglect some terms in the rotated Hamiltonian. Then we solve a variation of the Schroedinger equation that models decoherence as the system evolves through intrinsic mechanisms beyond conventional quantum mechanics rather than dissipative interaction with an environment. (Abstract Copyright [2009], Wiley Periodicals, Inc.)
Miao, Qiang; Zheng, Yujun
2016-06-01
In this paper, the nature of the multi-order resonance and coherent destruction of tunneling (CDT) for two-level system driven cross avoided crossing is investigated by employing the emitted photons and the Mandel’s Q parameter based on the photon counting statistics. An asymmetric feature of CDT is shown in the spectrum of Mandel’s Q parameter. Also, the CDT can be employed to suppress the spontaneous decay and prolong waiting time noticeably. The photon emission pattern is of monotonicity in strong relaxation, and homogeneity in pure dephasing regime, respectively.
Interaction of Lamb modes with two-level systems in amorphous nanoscopic membranes.
Energy Technology Data Exchange (ETDEWEB)
Kuhn, T.; Anghel, D. V.; Galperin, Y. M.; Manninen, M.; Materials Science Division; Univ. Jyvaskyla; National Inst. for Physics and Nuclear Engineering; Bogolivbov Lab. Theoretical Physics; Univ. Oslo; Russian Academy of Sciences
2007-01-01
Using a generalized model of interaction between a two-level system (TLS) and an arbitrary deformation of the material, we calculate the interaction of Lamb modes with TLSs in amorphous nanoscopic membranes. We compare the mean free paths of the Lamb modes of different symmetries and calculate the heat conductivity {kappa}. In the limit of an infinitely wide membrane, the heat conductivity is divergent. Nevertheless, the finite size of the membrane imposes a lower cutoff for the phonon frequencies, which leads to the temperature dependence {kappa}{alpha}T(a+b ln T). This temperature dependence is a hallmark of the TLS-limited heat conductance at low temperature.
Two-level correlation function of critical random-matrix ensembles
E. Cuevas
2004-01-01
The two-level correlation function $R_{d,\\beta}(s)$ of $d$-dimensional disordered models ($d=1$, 2, and 3) with long-range random-hopping amplitudes is investigated numerically at criticality. We focus on models with orthogonal ($\\beta=1$) or unitary ($\\beta=2$) symmetry in the strong ($b^d \\ll 1$) coupling regime, where the parameter $b^{-d}$ plays the role of the coupling constant of the model. It is found that $R_{d,\\beta}(s)$ is of the form $R_{d,\\beta}(s)=1+\\delta(s)-F_{\\beta}(s^{\\beta}/...
Solving the scattering of N photons on a two-level atom without computation
Roulet, Alexandre; Scarani, Valerio
2016-09-01
We propose a novel approach for solving the scattering of light onto a two-level atom coupled to a one-dimensional waveguide. First we express the physical quantity of interest in terms of Feynman diagrams and treat the atom as a non-saturable linear beamsplitter. By using the atomic response to our advantage, a relevant substitution is then made that captures the nonlinearity of the atom, and the final result is obtained in terms of simple integrals over the initial incoming wavepackets. The procedure is not limited to post-scattering quantities and allows for instance to derive the atomic excitation during the scattering event.
Ultrasonic distance sensor improvement using a two-level neural network
Parvis, Marco; Carullo, Alessio; Ferraris, Franco
1996-01-01
This paper discusses the performance improvement that a neural network can provide to a contactless distance sensor based on the measurement of the time of flight (TOF) of an ultrasonic (US) pulse. The sensor, which embeds a correction system for the temperature effect, achieves a distance uncertainty (rms) of less than 0.5 mm over 0.5 m by using a two-level neural network to process the US echo and determine the TOF in the presence of environmental acoustic noise. The network embeds a "guard...
Experimental investigation of slow light propagation in degenerate two-level system
Institute of Scientific and Technical Information of China (English)
Wang Li-Rong; Zhao Yan-Ting; Ma Jie; Zhao Jian-Ming; Xiao Lian-Tuan; Jia Suo-Tang
2006-01-01
Slowing a light pulse in a degenerate two-level system is observed with a double-frequency sweeping technique. The effects of coupling beam intensity, cell temperature and frequency detunings of the coupling and probe beams in resonance, on the slowing of light propagation in such a system are investigated. It is found that group velocities depend strongly on polarization combinations. A group velocity υg=6760m/s of light pulses in caesium vapour is obtained under the optimal parameters.
Canyon of current suppression in an interacting two-level quantum dot
DEFF Research Database (Denmark)
Karlström, O; Pedersen, Jonas Nyvold; Samuelsson, P
2011-01-01
Motivated by the recent discovery of a canyon of conductance suppression in a two-level equal-spin quantum dot system [Phys. Rev. Lett. 104, 186804 (2010)], the transport through this system is studied in detail. At low bias and low temperature a strong current suppression is found around...... quantum rate equations. The simulations allow for the prediction of how the suppression is affected by the couplings, the charging energy, the position of the energy levels, the applied bias, and the temperature. We find that, away from electron-hole symmetry, the parity of the couplings is essential...
Phase Dependence of Few-Cycle Pulsed Laser Propagation in a Two-Level Atom Medium
Institute of Scientific and Technical Information of China (English)
肖健; 王中阳; 徐至展
2002-01-01
The phase-dependent feature of few-cycle pulsed laser propagation in a resonant two-level atom medium is demonstrated by solving the full Maxwell-Bloch equations. Even in the perturbative region, the propagating carrier field and the corresponding spectra of the few-cycle pulsed laser are sensitive to the initial phase due to self-phase modulation. For the larger pulse area, the fact that the carrier-wave reshaping comes from the carrier wave Rabi flopping is also responsible for this sensitivity, and the phase-dependent feature is more evident.
SPECTRUM OF A FEW-CYCLE LASER PULSE PROPAGATING IN A TWO-LEVEL ATOM MEDIUM
Institute of Scientific and Technical Information of China (English)
肖健; 王中阳; 徐至展
2001-01-01
The spectrum evolution of a few-cycle optical pulse in a resonant two-level atom medium is studied theoretically by using the full Maxwell-Bloch equations. On the propagating pulse, significantly much faster oscillation components separated with the main pulse appear due to strong self-phase modulation and pulse reshaping. In this case, ideal selfinduced transparency cannot occur for a 2r pulse. The spectrum of the 4r pulse shows an evident oscillatory feature because of the continuum interference of the separate pulses. For larger pulse areas, continuum generation from near ultraviolet to infrared occurs.
Zeno and Anti Zeno effect for a two level system in a squeezed bath
Mundarain, D F
2005-01-01
We discuss the appearance of Zeno (QZE) or anti-Zeno (QAE) effect in an exponentially decaying system. We consider the quantum dynamics of a continuously monitored two level system interacting with a squeezed bath. We find that the behavior of the system depends critically on the way in which the squeezed bath is prepared. For specific choices of the squeezing phase the system shows Zeno or anti-Zeno effect in conditions for which it would decay exponentially if no measurements were done. This result allows for a clear interpretation in terms of the equivalent spin system interacting with a fictitious magnetic field.
Reactive Power Impact on Lifetime Prediction of Two-level Wind Power Converter
DEFF Research Database (Denmark)
Zhou, Dao; Blaabjerg, Frede; Lau, M.;
2013-01-01
The influence of reactive power injection on the dominating two-level wind power converter is investigated and compared in terms of power loss and thermal behavior. Then the lifetime of both the partial-scale and full-scale power converter is estimated based on the widely used Coffin-Manson model....... It is concluded that the injection of the reactive power could have serious impact on the power loss and thermal profile, especially at lower wind speed. Furthermore, the introduction of the reactive power could also shorten the lifetime of the wind power converter significantly....
Dynamics of Two-Level Trapped Ion in a Standing Wave Laser in Noncommutative Space
Institute of Scientific and Technical Information of China (English)
YANG Xiao-Xue; WU Ying
2007-01-01
We study the dynamics of a two-level trapped ion in a standing wave electromagnetic field in two-dimensional (2D) noncommutative spaces in the Lamb-Dicke regime under the rotating wave approximation. We obtain the explicit analytical expressions for the energy spectra, energy eigenstates, unitary time evolution operator, atomic inversion, and phonon number operators. The Rabi oscillations, the collapse, and revivals in the average atomic inversion and the average phonon number are explicitly shown to contain the information of the parameter of the space noncommutativity,which sheds light on proposing new schemes based on the dynamics of trappedion to test the noncommutativity.
Radiation Rate of a Two-Level Atom in a Spacetime with a Reflecting Boundary
Institute of Scientific and Technical Information of China (English)
LU Shi-Zhuan; YU Hong-Wei
2005-01-01
@@ We study a two-level atom in interaction with a real massless scalar quantum field in a spacetime with a reflecting boundary. We calculate the rate of change of the atomic energy for the atom. The presence of the boundary modifies the quantum fluctuations of the scalar field, which in turn modifies the rate of change of the atomic energy.It is found that the modifications induced by the presence of a boundary make the spontaneous radiation rate of an excited atom to oscillate near the boundary and this oscillatory behaviour may offer a possible opportunity for experimental tests for geometrical (boundary) effects in flat spacetime.
Propagation of Few-Cycle Pulse Laser in Two-Level Atom Medium
Institute of Scientific and Technical Information of China (English)
肖健; 王中阳; 徐至展
2001-01-01
By comparing the numerical solutions of Maxwell-Bloch equations beyond and within the slowly-varying envelope approximation and the rotating-wave approximation for the propagation of a few-cycle pulse laser in a resonant two-level atom medium, we found that both the Rabi flopping and the refractive index, and subsequently the carrier and the propagation velocity of the few-cycle pulse, are closely connected with the time-derivative behaviour of the electric field. This is because the Rabi flopping is such that the soliton pulse splits during propagation and that a shorter pulse propagates faster than a broader one.
Analysis of Two-Level Support Systems with Time-Dependent Overflow - A Banking Application
DEFF Research Database (Denmark)
Barth, Wolfgang; Manitz, Michael; Stolletz, Raik
2010-01-01
is available. The analysis of such a system with time-dependent overflow is reduced to the analysis of a continuous-time Markov chain with state-dependent overflow probabilities. To approximate the system with time-dependent overflow, some waiting-based performance measures are modified. Numerical results......In this paper, we analyze the performance of call centers of financial service providers with two levels of support and a time-dependent overflow mechanism. Waiting calls from the front-office queue flow over to the back office if a waiting-time limit is reached and at least one back-office agent...
Fractal Two-Level Finite Element Method For Free Vibration of Cracked Beams
Directory of Open Access Journals (Sweden)
A.Y.T. Leung
1998-01-01
Full Text Available The fractal two-level finite element method is extended to the free vibration behavior of cracked beams for various end boundary conditions. A cracked beam is separated into its singular and regular regions. Within the singular region, infinite number of finite elements are virturally generated by fractal geometry to model the singular behavior of the crack tip. The corresponding numerous degrees of freedom are reduced to a small set of generalized displacements by fractal transformation technique. The solution time and computer storage can be remarkably reduced without sacrifying accuracy. The resonant frequencies and mode shapes computed compared well with the results from a commercial program.
Phase Dependence of Fluorescence Spectrum of a Two-Level Atom in a Trichromatic Field
Institute of Scientific and Technical Information of China (English)
LI Jing-Yan; HU Xiang-Ming; LI Xiao-Xia; SHI Wen-Xing; XU Qing; GUO Hong-Ju
2005-01-01
@@ We examine the phase-dependent effects in resonance fluorescence of a two-level atom driven by a trichromatic modulated field. It is shown that the fluorescence spectrum depends crucially on the sum of relative phases of the sideband components compared to the central component, not simply on the respective phases. The appearance or disappearance of the central peak and the selective elimination of the sideband peaks are achieved simply by varying the sum phase. Once the sum phase is fixed, the spectrum keeps its features unchanged regardless of the respective relative phases.
The dynamic properties of the two-level entangled atom in an optical field
Institute of Scientific and Technical Information of China (English)
无
2003-01-01
The interaction of an optical field and one of the entangled atoms is analyzed in detail in this paper. Furthermore, the dynamic properties of the two-level entangled atom are manifested. The properties of the action are dependent on the initial state of the atom. After detecting the atom out of the field, we can obtain the state of the other atom moving in the field. It is shown that the state of the atom out of the field influences the dynamic properties of the atom in the field.
Quantum averaging and resonances: two-level atom in a one-mode classical laser field
Directory of Open Access Journals (Sweden)
M. Amniat-Talab
2007-06-01
Full Text Available We use a nonperturbative method based on quantum averaging and an adapted from of resonant transformations to treat the resonances of the Hamiltonian of a two-level atom interacting with a one-mode classical field in Floquet formalism. We illustrate this method by extraction of effective Hamiltonians of the system in two regimes of weak and strong coupling. The results obtained in the strong-coupling regime, are valid in the whole range of the coupling constant for the one-photon zero-field resonance.
Spectral density of Cooper pairs in two level quantum dot-superconductors Josephson junction
Dhyani, A.; Rawat, P. S.; Tewari, B. S.
2016-09-01
In the present paper, we report the role of quantum dot energy levels on the electronic spectral density for a two level quantum dot coupled to s-wave superconducting leads. The theoretical arguments in this work are based on the Anderson model so that it necessarily includes dot energies, single particle tunneling and superconducting order parameter for BCS superconductors. The expression for single particle spectral function is obtained by using the Green's function equation of motion technique. On the basis of numerical computation of spectral function of superconducting leads, it has been found that the charge transfer across such junctions can be controlled by the positions and availability of the dot levels.
Quantum dynamics of a microwave driven superconducting phase qubit coupled to a two-level system
Sun, Guozhu; Wen, Xueda; Mao, Bo; Zhou, Zhongyuan; Yu, Yang; Wu, Peiheng; Han, Siyuan
2010-10-01
We present an analytical and comprehensive description of the quantum dynamics of a microwave resonantly driven superconducting phase qubit coupled to a microscopic two-level system (TLS), covering a wide range of the external microwave field strength. Our model predicts several interesting phenomena in such an ac driven four-level bipartite system including anomalous Rabi oscillations, high-contrast beatings of Rabi oscillations, and extraordinary two-photon transitions. Our experimental results in a coupled qubit-TLS system agree quantitatively very well with the predictions of the theoretical model.
Haffoudhi, Houda
2005-01-01
URL des Cahiers :http://mse.univ-paris1.fr/MSEFramCahier2005.htm; Cahiers de la Maison des Sciences Economiques 2005.54 - ISSN : 1624-0340; International environmental agreements (IEAs) are increasingly important in a globalized economy. The aim of our paper is study the effect of political pressure groups-lobbies on the size and stability of IEAs. To this purpose we use the framework of two-level games to explain how national political situation influences the decisions of governments at the...
Load-Balance Policy in Two Level-Cluster File System
Institute of Scientific and Technical Information of China (English)
LIU Yuling; SONG Weiwei; MA Xiaoxue
2006-01-01
In this paper, we explored a load-balancing algorithm in a cluster file system contains two levels of metadata-server,primary-level server quickly distributestasks to second-level servers depending on the closest load-balancing information. At the same time, we explored a method which accurately reflect I/O traffic and storage of storage-node: computing the heat-value of file, according to which we realized a more logical storage allocation. According to the experiment result, we conclude that this new algorithm shortens the executing time of tasks and improves the system performance compared with other load algorithm.
Two Improved Access Methods on Compact Binary (CB) Trees.
Shishibori, Masami; Koyama, Masafumi; Okada, Makoto; Aoe, Jun-ichi
2000-01-01
Discusses information retrieval and the use of binary trees as a fast access method for search strategies such as hashing. Proposes new methods based on compact binary trees that provide faster access and more compact storage, explains the theoretical basis, and confirms the validity of the methods through empirical observations. (LRW)
Efficient enumeration of non-isomorphic processing trees
Waas, F.
1998-01-01
Enumeration of search spaces belonging to join queries, so far comprises large sets of isomorphic processing trees, i.e. trees that can be equalized by only commutative exchange of the input relations to the operators. Since these differences can be handled effectively by the costing method it is su
Classification and regression trees
Breiman, Leo; Olshen, Richard A; Stone, Charles J
1984-01-01
The methodology used to construct tree structured rules is the focus of this monograph. Unlike many other statistical procedures, which moved from pencil and paper to calculators, this text's use of trees was unthinkable before computers. Both the practical and theoretical sides have been developed in the authors' study of tree methods. Classification and Regression Trees reflects these two sides, covering the use of trees as a data analysis method, and in a more mathematical framework, proving some of their fundamental properties.
SCREENING OF MEDIUM COMPOUNDS USING A TWO-LEVEL FACTORIAL DESIGN FOR SACCHAROMYCES BOULARDII
Directory of Open Access Journals (Sweden)
GUOWEI SHU
2016-04-01
Full Text Available Even if the probiotic effect of Saccharomyces boulardii is has been reported, this yeast is rarely used in medium composition. Based on single factor experiment, two-level factorial design was employed to evaluate the effect of carbon sources (sucrose, glucose, nitrogen sources (soy peptone, beef extract, yeast extract, calf serum, malt extract and salts (K2HPO4, KH2PO4, MgSO4, Na2HPO4, NaH2PO4, CaCl2, sodium citrate, sodium glutamate on the growth of S. boulardii. At the same time, the optical density (OD in the medium was measured at 560 nm after 36 h of incubation. The result of two-level factorial design experiment showed that calf serum (p = 0.0214 and sodium citrate (p = 0.0045 are the significant growth factors of S. boulardii, sucrose (p = 0.0861 and malt extract (p = 0.0763 are important factors. In addition, sucrose and sodium citrate showed positive effect on the growth of S. boulardii. However, calf serum and malt extract showed negative effect on the growth. And we determined that the optimum medium composition for S. boulardii was as follow: 37.5 g·L-1 sucrose, 6 g·L-1 calf serum, 6 g·L-1 malt extract, 5 g·L-1 sodium citrate.
The Master Equation for Two-Level Accelerated Systems at Finite Temperature
Tomazelli, J. L.; Cunha, R. O.
2016-10-01
In this work, we study the behaviour of two weakly coupled quantum systems, described by a separable density operator; one of them is a single oscillator, representing a microscopic system, while the other is a set of oscillators which perform the role of a reservoir in thermal equilibrium. From the Liouville-Von Neumann equation for the reduced density operator, we devise the master equation that governs the evolution of the microscopic system, incorporating the effects of temperature via Thermofield Dynamics formalism by suitably redefining the vacuum of the macroscopic system. As applications, we initially investigate the behaviour of a Fermi oscillator in the presence of a heat bath consisting of a set of Fermi oscillators and that of an atomic two-level system interacting with a scalar radiation field, considered as a reservoir, by constructing the corresponding master equation which governs the time evolution of both sub-systems at finite temperature. Finally, we calculate the energy variation rates for the atom and the field, as well as the atomic population levels, both in the inertial case and at constant proper acceleration, considering the two-level system as a prototype of an Unruh detector, for admissible couplings of the radiation field.
Directory of Open Access Journals (Sweden)
Shen-yan Chen
2015-01-01
Full Text Available This paper presents an Improved Genetic Algorithm with Two-Level Approximation (IGATA to minimize truss weight by simultaneously optimizing size, shape, and topology variables. On the basis of a previously presented truss sizing/topology optimization method based on two-level approximation and genetic algorithm (GA, a new method for adding shape variables is presented, in which the nodal positions are corresponding to a set of coordinate lists. A uniform optimization model including size/shape/topology variables is established. First, a first-level approximate problem is constructed to transform the original implicit problem to an explicit problem. To solve this explicit problem which involves size/shape/topology variables, GA is used to optimize individuals which include discrete topology variables and shape variables. When calculating the fitness value of each member in the current generation, a second-level approximation method is used to optimize the continuous size variables. With the introduction of shape variables, the original optimization algorithm was improved in individual coding strategy as well as GA execution techniques. Meanwhile, the update strategy of the first-level approximation problem was also improved. The results of numerical examples show that the proposed method is effective in dealing with the three kinds of design variables simultaneously, and the required computational cost for structural analysis is quite small.
Thermal analysis of multi-MW two-level wind power converter
DEFF Research Database (Denmark)
Zhou, Dao; Blaabjerg, Frede; Mogens, Lau;
2012-01-01
In this paper, the multi-MW wind turbine of partial-scale and full-scale two-level power converter with DFIG and direct-drive PMSG are designed and compared in terms of their thermal performance. Simulations of different configurations regarding loss distribution and junction temperature in the p......In this paper, the multi-MW wind turbine of partial-scale and full-scale two-level power converter with DFIG and direct-drive PMSG are designed and compared in terms of their thermal performance. Simulations of different configurations regarding loss distribution and junction temperature...... in the power device in the whole range of wind speed are presented and analyzed. It is concluded that in both partial-scale and full-scale power converter the most thermal stressed power device in the generator-side converter will have higher mean junction temperature and larger junction temperature...... fluctuation compared to grid-side converter at the rated wind speed. Moreover, the thermal performance of the generator-side converter in the partial-scale power converter becomes crucial around the synchronous operating point and should be considered carefully....
Two-level Robust Measurement Fusion Kalman Filter for Clustering Sensor Networks
Institute of Scientific and Technical Information of China (English)
ZHANG Peng; QI Wen-Juan; DENG Zi-Li
2014-01-01
This paper investigates the distributed fusion Kalman filtering over clustering sensor networks. The sensor network is partitioned as clusters by the nearest neighbor rule and each cluster consists of sensing nodes and cluster-head. Using the minimax robust estimation principle, based on the worst-case conservative system with the conservative upper bounds of noise variances, two-level robust measurement fusion Kalman filter is presented for the clustering sensor network systems with uncertain noise variances. It can significantly reduce the communication load and save energy when the number of sensors is very large. A Lyapunov equation approach for the robustness analysis is presented, by which the robustness of the local and fused Kalman filters is proved. The concept of the robust accuracy is presented, and the robust accuracy relations among the local and fused robust Kalman filters are proved. It is proved that the robust accuracy of the two-level weighted measurement fuser is equal to that of the global centralized robust fuser and is higher than those of each local robust filter and each local weighted measurement fuser. A simulation example shows the correctness and effectiveness of the proposed results.
Assessment of two-level heat pump installations’ power efficiency for heat supply systems
Directory of Open Access Journals (Sweden)
Аlla Е. Denysova
2015-06-01
Full Text Available The problem of energy saving becomes one of the most important in power engineering. It is caused by exhaustion of world reserves in hydrocarbon fuel, such as gas, oil and coal representing sources of traditional heat supply. Conventional sources has essential shortcomings: low power, ecological and economic efficiencies, that can be eliminated by using alternative methods of power supply, like the considered one: low-temperature natural heat of ground waters of on the basis of heat pump installations application. The heat supply system considered provides an effective use of two-level heat pump installation operating as heat source the Odessa city ground waters during the lowest ambient temperature period. Proposed is a calculation method of heat pump installations on the basis of geothermal heat supply. Calculated are the values of electric energy consumption N by the compressors’ drive, and the heat supply system transformation coefficient µ for a source of geothermal heat from ground waters of Odessa city allowing to estimate efficiency of two-level heat pump installations.
Speeding Up Neighbour-Joining Tree Construction
DEFF Research Database (Denmark)
Brodal, Gerth Stølting; Fagerberg, Rolf; Mailund, Thomas
A widely used method for constructing phylogenetic trees is the neighbour-joining method of Saitou and Nei. We develope heuristics for speeding up the neighbour-joining method which generate the same phylogenetic trees as the original method. All heuristics are based on using a quad-tree to guide...... the search for the next pair of nodes to join, but di#er in the information stored in quad-tree nodes, the way the search is performed, and in the way the quad-tree is updated after a join. We empirically evaluate the performance of the heuristics on distance matrices obtained from the Pfam collection...... of alignments, and compare the running time with that of the QuickTree tool, a well-known and widely used implementation of the standard neighbour-joining method. The results show that the presented heuristics can give a significant speed-up over the standard neighbour-joining method, already for medium sized...
Speeding Up Neighbour-Joining Tree Construction
DEFF Research Database (Denmark)
Brodal, Gerth Stølting; Fagerberg, Rolf; Mailund, Thomas
A widely used method for constructing phylogenetic trees is the neighbour-joining method of Saitou and Nei. We develope heuristics for speeding up the neighbour-joining method which generate the same phylogenetic trees as the original method. All heuristics are based on using a quad-tree to guide...... the search for the next pair of nodes to join, but di#er in the information stored in quad-tree nodes, the way the search is performed, and in the way the quad-tree is updated after a join. We empirically evaluate the performance of the heuristics on distance matrices obtained from the Pfam collection...... of alignments, and compare the running time with that of the QuickTree tool, a well-known and widely used implementation of the standard neighbour-joining method. The results show that the presented heuristics can give a significant speed-up over the standard neighbour-joining method, already for medium sized...
An Efficient Trajectory Data Index Integrating R-tree, Hash and B*-tree
Directory of Open Access Journals (Sweden)
GONG Jun
2015-05-01
Full Text Available To take into account all of efficiency and query capability, this paper presents a new trajectory data index named HBSTR-tree. In HBSTR-tree, trajectory sample points are collectively stored into trajectory nodes sequentially. Hash table is adopted to index the most recent trajectory nodes of mobile targets, and trajectory nodes will not be inserted into spatio-temporal R-tree until full, which can enhance generation performance in this way. Meantime, one-dimensional index of trajectory nodes in the form of B*-tree is built. Therefore, HBSTR-tree can satisfy both spatio-temporal query and target trajectory query. In order to improve search efficiency, a new criterion for spatio-temporal R-tree and one new node-selection sub-algorithm are put forward, which further optimize insertion algorithm of spatio-temporal R-tree. Furthermore, a database storage scheme for spatio-temporal R-tree is also brought up. Experimental results prove that HBSTR-tree outperforms current methods in several aspects such as generation efficiency, query performance and supported query types, and then supports real-time updates and efficient accesses of huge trajectory database.
EVALUATION OF TWO-LEVEL GLOBAL LOAD BALANCING FRAMEWORK IN CLOUD ENVIRONMENT
Directory of Open Access Journals (Sweden)
Po-Huei Liang
2015-05-01
Full Text Available With technological advancements and constant changes of Internet, cloud computing has been today's trend. With the lower cost and convenience of cloud computing services, users have increasingly put their Web resources and information in the cloud environment. The availability and reliability of the client systems will become increasingly important. Today cloud applications slightest interruption, the impact will be significant for users. It is an important issue that how to ensure reliability and stability of the cloud sites. Load balancing would be one good solution. This paper presents a framework for global server load balancing of the Web sites in a cloud with two-level load balancing model. The proposed framework is intended for adapting an open-source load-balancing system and the framework allows the network service provider to deploy a load balancer in different data centers dynamically while the customers need more load balancers for increasing the availability.
Chao, Li; Wu, Zhen; Wang, Jianing; Liu, Yi; Chen, Yi
2010-07-01
This article is focused on the two-level control system of ODL, which are divided into bottom layer control of linear motor and upper layer control of Piezoelectric Transducer(PZT).This ODL are designed to compensate geometrical optical path difference, which results from the earth rotation, and other disturbances, with high-accuracy and real time. Based on the PLC of PMAC controller, the linear motor tracks the trajectory of the simulated optical path difference to compensate roughly. PZT then compensates the rest error measured by ZLM almost real time. A detailed fulfillment of this method is shown in the article, and the first result data is produced. The result implies that this method is efficient. This article offers the reference for the ODL development with the practical high accuracy of compensation.
A two-level approach towards semantic colon segmentation: removing extra-colonic findings.
Lu, Le; Wolf, Matthias; Liang, Jianming; Dundar, Murat; Bi, Jinbo; Salganicoff, Marcos
2009-01-01
Computer aided detection (CAD) of colonic polyps in computed tomographic colonography has tremendously impacted colorectal cancer diagnosis using 3D medical imaging. It is a prerequisite for all CAD systems to extract the air-distended colon segments from 3D abdomen computed tomography scans. In this paper, we present a two-level statistical approach of first separating colon segments from small intestine, stomach and other extra-colonic parts by classification on a new geometric feature set; then evaluating the overall performance confidence using distance and geometry statistics over patients. The proposed method is fully automatic and validated using both the classification results in the first level and its numerical impacts on false positive reduction of extra-colonic findings in a CAD system. It shows superior performance than the state-of-art knowledge or anatomy based colon segmentation algorithms.
Spectroscopic properties of a two-level atom interacting with a complex spherical nanoshell
Moroz, A
2004-01-01
Frequency shifts, radiative decay rates, the Ohmic loss contribution to the nonradiative decay rates, fluorescence yields, and photobleaching of a two-level atom radiating anywhere inside or outside a complex spherical nanoshell, i.e. a stratified sphere consisting of alternating silica and gold concentric spherical shells, are studied. The changes in the spectroscopic properties of an atom interacting with complex nanoshells are significantly enhanced, often more than two orders of magnitude, compared to the same atom interacting with a homogeneous dielectric sphere. The changes strongly depend on the nanoshell parameters and the atom position. When an atom approaches a metal shell,the radiative decay rates are strongly enhanced and they increase faster than the Ohmic loss contribution to the nonradiative decay rates. However, the majority of the emitted radiation does not escape to spatial infinity but instead is absorbed. The enhancement of the radiative decay rates in a close proximity of metal boundaries...
Solvent effects on the optical properties of two-level systems with permanent dipole moments
Mastrodomenico, A.; Izquierdo, M. A.; Paz, J. L.; Colmenares, P.
2013-11-01
The inclusion of the permanent dipole moments and the solvent on the optical conventional Bloch equations (OCBE) allowed us to obtain analytical expressions for the optical properties of a two-level molecular system. We employed the methodology developed by Colmenares et al.1, in which they model the collisional effect of the solvent through a stochastical function, ξ(t) = ω0 + σ(t), so the OCBE become a set of coupled integro-differential stochastical equations that we solved, up to third order in the incident field, employing the perturbation theory. Once obtained the analytical expressions for the density matrix elements, macroscopic polarization and effective susceptibility of the system, we studied the optical properties derived in the frequency space, inside and outside the rotating wave approximation.
Equivalence of the measures of non-Markovianty for open two-level systems
Zeng, Hao-Sheng; Zheng, Yan-Ping; Wang, Guo-You
2011-01-01
In order to depict the deviation of quantum time evolution in open systems from Markovian processes, different measures have been presented. We demonstrate that the measure proposed by Breuer, Laine and Piilo [Phys. Rev. Lett. 103, 210401 (2009)] and the two measures proposed by Rivas, Huelga and Plenio [Phys. Rev. Lett. 105, 050403 (2010)] have exactly the same non-Markovian time-evolution intervals and thus are really equivalent each other when they apply to open two-level systems coupled to environments via Jaynes-Cummings or dephasing models. This equivalence implies that the three measures in different ways capture the intrinsical characters of non-Markovianty of quantum evolutional processes. We also show that the maximization in the definition of the first measure can be actually removed for the considered models without influencing the sensibility of the measure to detect non-Markovianty.
Equivalence of the measures of non-Markovianity for open two-level systems
Energy Technology Data Exchange (ETDEWEB)
Zeng Haosheng; Tang Ning; Zheng Yanping; Wang Guoyou [Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education, and Department of Physics, Hunan Normal University, Changsha 410081 (China)
2011-09-15
Different measures have been presented to depict the deviation of quantum time evolution in open systems from Markovian processes. We demonstrate that the measure proposed by Breuer, Laine, and Piilo [Phys. Rev. Lett. 103, 210401 (2009)] and the two measures proposed by Rivas, Huelga, and Plenio [Phys. Rev. Lett. 105, 050403 (2010)] have exactly the same non-Markovian time-evolution intervals and thus are really equivalent to each other when they are applied to open two-level systems coupled to environments via the Jaynes-Cummings or dephasing models. This equivalence implies that the three measures, in different ways, capture the intrinsic character of the non-Markovianity of quantum evolutional processes. We also show that the maximization in the definition of the first measure can be actually removed for the considered models without influencing the sensibility of the measure to detect non-Markovianity.
Photon absorption and emission statistics of a two-level atom in a cavity
Energy Technology Data Exchange (ETDEWEB)
Lee, Chang J. [Sun Moon University, Asan (Korea, Republic of)
2012-03-15
The absorption and the emission of photons by an atom involves quantum jumps between states. We investigate the quantum jump statistics for the system of a two-level atom and a single-mode cavity field. We use the Jaynes-Cummings model for this problem, perform Monte Carlo numerical simulations, and give a detailed exact analysis on these simulations. These studies reveal that the waiting-time distribution (WTD) for photon absorptions (emissions) has a unique novel statistic, and that the photon absorption (emission) rate is not uniform, but counter-intuitively depends on the position in the Rabi cycle. The effects of the nonclassical nature of the field on the WTD is discussed.
DEFF Research Database (Denmark)
Nysteen, Anders; McCutcheon, Dara; Mørk, Jesper
2015-01-01
We analytically treat the scattering of two counterpropagating photons on a two-level emitter embedded in an optical waveguide. We find that the nonlinearity of the emitter can give rise to significant pulse-dependent directional correlations in the scattered photonic state, which could...... be quantified via a reduction in coincidence clicks in a Hong–Ou–Mandel measurement setup, analogous to a linear beam splitter. Changes to the spectra and phase of the scattered photons, however, would lead to reduced interference with other photons when implemented in a larger optical circuit. We introduce...... suitable fidelity measures which account for these changes and find that high values can still be achieved even when accounting for all properties of the scattered photonic state....
Giant Cooperative Lamb Shift in a density-modulated slab of two-level atoms
Energy Technology Data Exchange (ETDEWEB)
Manassah, Jamal T., E-mail: jmanassah@gmail.co [Department of Electrical Engineering, City College of New York, NY 10031 (United States)
2010-04-19
A 'slab' of two-level atoms prepared in a superradiant Dicke state exhibits interesting enhancement of the Cooperative Decay Rate (CDR) when its density is modulated at the Bragg condition. In this Letter, complete analytical formulas are given, not only for CDR but also for the Cooperative Lamb Shift (CLS), both at and near the Bragg condition, as a function of the depth of modulation, the thickness of the slab, and the detuning from the Bragg condition. A major new result is that for detuning O(1/m) (where m=thickness/wavelength) the CLS takes on 'giant' values, proportional to m. The reason for this giant CLS is explored.
Controlling spontaneous emission of a two-level atom by hyperbolic metamaterials
Liu, Zheng; Jiang, Xunya
2012-01-01
Within the frame of quantum optics we analyze the properties of spontaneous emission of two-level atom in media with indefinite permittivity tensor where the geometry of the dispersion relation is characterized by an ellipsoid or a hyperboloid(hyperbolic medium). The decay rate is explicitly given with the orientation of the dipole transition matrix element taken into account. It indicates that for the ellipsoid case the intensity of the photons coupled into different modes can be tuned by changing the direction of the matrix element and for the hyperboloid case it is found that spontaneous emission in hyperbolic medium can be dramatically enhanced compared to the dielectric background. Moreover, spontaneous emission exhibit the strong directivity and get the maximum in the asymptote direction.
Two-Level Automatic Adaptation of a Distributed User Profile for Personalized News Content Delivery
Directory of Open Access Journals (Sweden)
Maria Papadogiorgaki
2008-01-01
Full Text Available This paper presents a distributed client-server architecture for the personalized delivery of textual news content to mobile users. The user profile consists of two separate models, that is, the long-term interests are stored in a skeleton profile on the server and the short-term interests in a detailed profile in the handset. The user profile enables a high-level filtering of available news content on the server, followed by matching of detailed user preferences in the handset. The highest rated items are recommended to the user, by employing an efficient ranking process. The paper focuses on a two-level learning process, which is employed on the client side in order to automatically update both user profile models. It involves the use of machine learning algorithms applied to the implicit and explicit user feedback. The system's learning performance has been systematically evaluated based on data collected from regular system users.
TWO-LEVEL HIERARCHICAL COORDINATION QUEUING METHOD FOR TELECOMMUNICATION NETWORK NODES
Directory of Open Access Journals (Sweden)
M. V. Semenyaka
2014-07-01
Full Text Available The paper presents hierarchical coordination queuing method. Within the proposed method a queuing problem has been reduced to optimization problem solving that was presented as two-level hierarchical structure. The required distribution of flows and bandwidth allocation was calculated at the first level independently for each macro-queue; at the second level solutions obtained on lower level for each queue were coordinated in order to prevent probable network link overload. The method of goal coordination has been determined for multilevel structure managing, which makes it possible to define the order for consideration of queue cooperation restrictions and calculation tasks distribution between levels of hierarchy. Decisions coordination was performed by the method of Lagrange multipliers. The study of method convergence has been carried out by analytical modeling.
Two-level system noise reduction for Microwave Kinetic Inductance Detectors
Noroozian, Omid; Zmuidzinas, Jonas; LeDuc, Henry G; Mazin, Benjamin A
2009-01-01
Noise performance is one of the most crucial aspects of any detector. Superconducting Microwave Kinetic Inductance Detectors (MKIDs) have an "excess" frequency noise that shows up as a small time dependent jitter of the resonance frequency characterized by the frequency noise power spectrum measured in units of Hz^2/Hz. Recent studies have shown that this noise almost certainly originates from a surface layer of two-level system (TLS) defects on the metallization or substrate. Fluctuation of these TLSs introduces noise in the resonator due to coupling of the TLS electric dipole moments to the resonator's electric field. Motivated by a semi-empirical quantitative theory of this noise mechanism, we have designed and tested new resonator geometries in which the high-field "capacitive" portion of the CPW resonator is replaced by an interdigitated capacitor (IDC) structure with 10 - 20 micron electrode spacing, as compared to the 2 micron spacing used for our more conventional CPW resonators. Measurements show tha...
Zhao, Tao; Hwang, Feng-Nan; Cai, Xiao-Chuan
2016-07-01
We consider a quintic polynomial eigenvalue problem arising from the finite volume discretization of a quantum dot simulation problem. The problem is solved by the Jacobi-Davidson (JD) algorithm. Our focus is on how to achieve the quadratic convergence of JD in a way that is not only efficient but also scalable when the number of processor cores is large. For this purpose, we develop a projected two-level Schwarz preconditioned JD algorithm that exploits multilevel domain decomposition techniques. The pyramidal quantum dot calculation is carefully studied to illustrate the efficiency of the proposed method. Numerical experiments confirm that the proposed method has a good scalability for problems with hundreds of millions of unknowns on a parallel computer with more than 10,000 processor cores.
Quantum mechanical treatment of traveling light in an absorptive medium of two-level systems
Inoue, K.
2016-12-01
Quantum mechanical treatment of a light wave that propagates through an absorptive medium is presented. Unlike a phenomenological beam-splitter model conventionally employed to describe a traveling light in a lossy medium, the time evolution of the field operator is derived using the Heisenberg equation with the Hamiltonian for a physical system, where the light wave interacts with an ensemble of two-level systems in a medium. Using the obtained time-evolved field operators, the mean values and variances of the light amplitude and the photon number are evaluated. The results are in agreement with those obtained in the beam-splitter model, giving a logical theoretical basis for the phenomenological beam-splitter model.
Optimal state transfer of a single dissipative two-level system
Jirari, Hamza; Wu, Ning
2016-04-01
Optimal state transfer of a single two-level system (TLS) coupled to an Ohmic boson bath via off-diagonal TLS-bath coupling is studied by using optimal control theory. In the weak system-bath coupling regime where the time-dependent Bloch-Redfield formalism is applicable, we obtain the Bloch equation to probe the evolution of the dissipative TLS in the presence of a time-dependent external control field. By using the automatic differentiation technique to compute the gradient for the cost functional, we calculate the optimal transfer integral profile that can achieve an ideal transfer within a dimer system in the Fenna-Matthews-Olson (FMO) model. The robustness of the control profile against temperature variation is also analyzed.
Interaction between two SU(1 , 1) quantum systems and a two-level atom
Abdalla, M. Sebawe; Khalil, E. M.; Obada, A. S.-F.
2016-07-01
We consider a two-level atom interacting with two coupled quantum systems that can be represented in terms of su(1 , 1) Lie algebra. The wave function that is obtained using the evolution operator for the atom is initially in a superposition state and the coupled su(1 , 1) systems in a pair coherent Barut-Girardello coherent state. We then discuss atomic inversion, where more periods of revivals are observed and compared with a single su(1 , 1) quantum system. For entanglement and squeezing phenomena, the atomic angles coherence and phase as well as the detuning are effective parameters. The second-order correlation function displays Bunching and anti-Bunching behavior.
Phonon induced optical gain in a current carrying two-level quantum dot
Energy Technology Data Exchange (ETDEWEB)
Eskandari-asl, Amir, E-mail: amir.eskandari.asl@gmail.com [Department of Physics, Shahid Beheshti University, G.C. Evin, Tehran 1983963113 (Iran, Islamic Republic of); School of Nano Science, Institute for Research in Fundamental Sciences (IPM), P.O. Box: 19395-5531, Tehran, Iran (Iran, Islamic Republic of)
2017-05-15
In this work we consider a current carrying two level quantum dot (QD) that is coupled to a single mode phonon bath. Using self-consistent Hartree-Fock approximation, we obtain the I-V curve of QD. By considering the linear response of our system to an incoming classical light, we see that depending on the parametric regime, the system could have weak or strong light absorption or may even show lasing. This lasing occurs at high enough bias voltages and is explained by a population inversion considering side bands, while the total electron population in the higher level is less than the lower one. The frequency at which we have the most significant lasing depends on the level spacing and phonon frequency and not on the electron-phonon coupling strength.
On Two-Level State-Dependent Routing Polling Systems with Mixed Service
Directory of Open Access Journals (Sweden)
Guan Zheng
2015-01-01
Full Text Available Based on priority differentiation and efficiency of the system, we consider an N+1 queues’ single-server two-level polling system which consists of one key queue and N normal queues. The novel contribution of the present paper is that we consider that the server just polls active queues with customers waiting in the queue. Furthermore, key queue is served with exhaustive service and normal queues are served with 1-limited service in a parallel scheduling. For this model, we derive an expression for the probability generating function of the joint queue length distribution at polling epochs. Based on these results, we derive the explicit closed-form expressions for the mean waiting time. Numerical examples demonstrate that theoretical and simulation results are identical and the new system is efficient both at key queue and normal queues.
Stimuli-Responsive Reversible Two-Level Adhesion from a Structurally Dynamic Shape-Memory Polymer.
Michal, Brian T; Spencer, Emily J; Rowan, Stuart J
2016-05-01
A shape-memory adhesive has been prepared that exhibits two levels of reversible adhesion. The adhesive is a semicrystalline cross-linked polymer that contains dynamic disulfide bonds. Melting of the crystalline regions via heat causes a drop in the modulus of the material facilitating wetting of the substrate as well as enhancing the surface contact area with the substrate, which result in the formation of an adhesive bond. Exposure to higher heat or UV light results in dynamic exchange of the disulfide bonds, which yields a further drop in the modulus/viscosity that improves surface wetting/contact and strengthens the adhesive bond. This improvement in adhesion is shown to apply over different substrates, contact forces, and deformation modes. Furthermore, the adhesive acts as a thermal shape-memory material and can be used to create joints that can reposition themselves upon application of heat.
Information Entropy Squeezing of a Two-Level Atom Interacting with Two-Mode Coherent Fields
Institute of Scientific and Technical Information of China (English)
LIU Xiao-Juan; FANG Mao-Fa
2004-01-01
From a quantum information point of view we investigate the entropy squeezing properties for a two-level atom interacting with the two-mode coherent fields via the two-photon transition. We discuss the influences of the initial state of the system on the atomic information entropy squeezing. Our results show that the squeezed component number,squeezed direction, and time of the information entropy squeezing can be controlled by choosing atomic distribution angle,the relative phase between the atom and the two-mode field, and the difference of the average photon number of the two field modes, respectively. Quantum information entropy is a remarkable precision measure for the atomic squeezing.
Two Level Versus Matrix Converters Performance in Wind Energy Conversion Systems Employing DFIG
Reddy, Gongati Pandu Ranga; Kumar, M. Vijaya
2017-05-01
Wind power capacity has received enormous growth during past decades. With substantial development of wind power, it is expected to provide a fifth of world's electricity by the end of 2030. In wind energy conversion system, the power electronic converters play an important role. This paper presents the two level and matrix converters performance in wind energy conversion system employing Doubly Fed Induction Generator (DFIG). The DFIG is a wound rotor induction generator. Because of the advantages of the DFIG over other generators it is being used for most of the wind applications. This paper also discusses control of converters using the space vector pulse width modulation technique. The MATLAB/SIMULINK ® software is used to study the performance of the converters.
Temperature dependent quantum correlations in three dipolar coupled two-level atoms
Ahmed, Shaik
2016-01-01
We investigate the thermal entanglement characteristics of three dipole-coupled two-level atoms arranged in two different configurations - in a line with nearest neighbour coupling and in a closed loop with each atom interacting with both its neighbours. It is observed that in loop configuration, any one of the three atoms is indeed entangled with the other two atoms in the system, which are not mutually entangled, and further that this feature is specific to only the loop configuration, which is markedly absent in the line configuration. A detailed study of the quantum correlations demonstrated how these can be tuned by varying the temperature and the dipole dipole coupling strength, in both the configurations.
Intrinsic decoherence of entanglement of a single quantized field interacting with a two-level atom
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
How the mean photon number, the probability of excited state and intrinsic decoherence coefficient influence the time evolution of entanglement is unknown, when a single-mode quantized optic field and a two-level atom coupling system is governed by Milburn equation. The Jaynes-Cummings model is considered. A lower bound of concurrence is proposed to calculate the entanglement. Simulation results indicate that the entanglement of system increases following the increasing of intrinsic decoherence coefficient or the decreasing of the mean photon number. Besides that, the entanglement of system decreases, while the probability of exited state increases from 0 to 0.1, and increases, while the probability of exited state increases from 0.1 to 1.
Nonvolatile optical memory via recoil-induced resonance in a pure two-level system
de Almeida, A. J. F.; Maynard, M.-A.; Banerjee, C.; Felinto, D.; Goldfarb, F.; Tabosa, J. W. R.
2016-12-01
We report on the storage of light via the phenomenon of recoil-induced resonance in a pure two-level system of cold cesium atoms. We use a strong coupling beam and a weak probe beam to couple different external momentum states of the cesium atom via two-photon Raman interaction which leads to the storage of the optical information of the probe beam. We have also measured the probe transmission spectrum, as well as the light storage spectrum which reveals very narrow subnatural resonance features showing absorption and gain. We have demonstrated that this memory presents the unique property of being insensitive to the reading process, which does not destroy the stored information leading to a memory lifetime limited only by the atomic thermal motion.
Effect of Phase Shifted Frequency Modulation on Two Level Atom-Field Interaction
Institute of Scientific and Technical Information of China (English)
K.V. Priyesh; Ramesh Babu Thayyullathil
2012-01-01
We have studied the effect of phase shifted frequency modulation on two level atom with field interaction using Jaynes-Cummings model. Here the frequency of the interacting field is sinusoidally varying with time with a constant phase. Due to the presence of phase in the frequency modulation, the variation of population inversion with time is different from the standard case. There are no exact collapses and revivals in the variation of population inversion but it oscillates sinusoidally with time. In coherent field atom interaction the population inversion behaves as in the case of Fock state atom interaction, when frequency modulation with a non zero phase is applied. The study done with squeezed field has shown the same behavior of the population inversion.
Quantum logic gates with two-level trapped ions beyond Lamb-Dicke limit
Institute of Scientific and Technical Information of China (English)
Zheng Xiao-Juan; Luo Yi-Min; Cai Jian-Wu
2009-01-01
In the system with two two-level ions confined in a linear trap,this paper presents a simple scheme to realize the quantum phase gate(QPG)and the swap gate beyond the Lamb-Dicke(LD)limit.These two-qubit quantum logic gates only involve the internal states of two trapped ions.The scheme does not use the vibrational mode as the data bus and only requires a single resonant interaction of the ions with the lasers.Neither the LD approximation nor the auxiliary atomic level is needed in the proposed scheme.Thus the scheme is simple and the interaction time is very short,which is important in view of decoherence.The experimental feasibility for achieving this scheme is also discussed.
Three-body entanglement induced by spontaneous emission in a three two-level atoms system
Institute of Scientific and Technical Information of China (English)
Liao Xiang-Ping; Fang Mao-Fa; Zheng Xiao-Juan; Cai Jian-Wu
2006-01-01
We study three-body entanglement induced by spontaneous emission in a three two-level atoms system by using the entanglement tensor approach. The results show that the amount of entanglement is strongly dependent on the initial state of the system and the species of atoms. The three-body entanglement is the result of the coherent superposition of the two-body entanglements. The larger the two-body entanglement is, the stronger the three-body entanglement is. On the other hand, if there exists a great difference in three two-body entanglement measures, the three-body entanglement is very weak. We also find that the maximum of the two-body entanglement obtained with nonidentical atoms is greater than that obtained with identical atoms via adjusting the difference in atomic frequency.
The Level-split of the Two-level Entangled Atom in an Optical Field
Institute of Scientific and Technical Information of China (English)
CAO Zhuoliang; HUANG Ting; GUO Guangcan; YI Youming
2002-01-01
The behavior of a two-level entangled atom in an optical field with circular polarization is studied in this paper. The interaction of an optical field and one of the entangled atoms is analyzed in detail. A general solution of the SchrAo¨Gdinger equation about the motion of the entangled atom is obtained. The properties of the action are dependent on the initial state of the atom. By detecting the entangled atom out of the field, we can obtain the state of the other atom moving in the field. It is shown that the state of the atom out of the field will influence the energies of the split-levels of the atom in the field.
A two-level formal specification of a defense communications system
Energy Technology Data Exchange (ETDEWEB)
Chisholm, G.H. [Argonne National Lab., IL (United States). Decision and Information Sciences Div.; Kemmerer, R.A. [Univ. of California, Santa Barbara, CA (United States). Reliable Software Group
1994-04-01
Computer systems are being used in critical situations with sensitive data, which makes it very important to ensure that these systems perform as desired. The defense communications system contains particularly sensitive data. A two-level ASLAN formal specification of a defense communications system is presented. The ASLAN model is designed to enhance the understanding of critical requirements and demands of the defense communications system. For the top-level (high-level) specifications, the structural details of the actual network are actual network are abstracted to allow more time for examining the interactions between the sites and the network. At this level, DataGrams move through the network, although the actual routing decisions are not specified. More details are added in the second-level specification. At this level, structure is added to the network.
Two-Level Verification of Data Integrity for Data Storage in Cloud Computing
Xu, Guangwei; Chen, Chunlin; Wang, Hongya; Zang, Zhuping; Pang, Mugen; Jiang, Ping
Data storage in cloud computing can save capital expenditure and relive burden of storage management for users. As the lose or corruption of files stored may happen, many researchers focus on the verification of data integrity. However, massive users often bring large numbers of verifying tasks for the auditor. Moreover, users also need to pay extra fee for these verifying tasks beyond storage fee. Therefore, we propose a two-level verification of data integrity to alleviate these problems. The key idea is to routinely verify the data integrity by users and arbitrate the challenge between the user and cloud provider by the auditor according to the MACs and ϕ values. The extensive performance simulations show that the proposed scheme obviously decreases auditor's verifying tasks and the ratio of wrong arbitration.
Reversible Data Hiding Based on Two-level HDWT Coefficient Histograms
Directory of Open Access Journals (Sweden)
Xu-Ren Luo
2011-05-01
Full Text Available In recent years, reversible data hiding has attracted much more attention than before. Reversibilitysignifies that the original media can be recovered without any loss from the marked media afterextracting the embedded message. This paper presents a new method that adopts two-level wavelettransform and exploits the feature of large wavelet coefficient variance to achieve the goal of highcapacity with imperceptibility. Our method differs from those of previous ones in which the waveletcoefficients histogram not gray-level histogram is manipulated. Besides, clever shifting rules areintroduced into histogram to avoid the decimal problem in pixel values after recovery to achievereversibility. With small alteration of the wavelet coefficients in the embedding process, and therefore lowvisual distortion is obtained in the marked image. In addition, an important feature of our design is thatthe use of threshold is much different from previous studies. The results indicate that our design issuperior to many other state-of-the-art reversible data hiding schemes.
A two-level on-line learning algorithm of Artificial Neural Network with forward connections
Directory of Open Access Journals (Sweden)
Stanislaw Placzek
2014-12-01
Full Text Available An Artificial Neural Network with cross-connection is one of the most popular network structures. The structure contains: an input layer, at least one hidden layer and an output layer. Analysing and describing an ANN structure, one usually finds that the first parameter is the number of ANN’s layers. A hierarchical structure is a default and accepted way of describing the network. Using this assumption, the network structure can be described from a different point of view. A set of concepts and models can be used to describe the complexity of ANN’s structure in addition to using a two-level learning algorithm. Implementing the hierarchical structure to the learning algorithm, an ANN structure is divided into sub-networks. Every sub-network is responsible for finding the optimal value of its weight coefficients using a local target function to minimise the learning error. The second coordination level of the learning algorithm is responsible for coordinating the local solutions and finding the minimum of the global target function. In the article a special emphasis is placed on the coordinator’s role in the learning algorithm and its target function. In each iteration the coordinator has to send coordination parameters into the first level of subnetworks. Using the input X and the teaching Z vectors, the local procedures are working and finding their weight coefficients. At the same step the feedback information is calculated and sent to the coordinator. The process is being repeated until the minimum of local target functions is achieved. As an example, a two-level learning algorithm is used to implement an ANN in the underwriting process for classifying the category of health in a life insurance company.
Melgar, Miguel A; Tobler, William D; Ernst, Robert J; Raley, Thomas J; Anand, Neel; Miller, Larry E; Nasca, Richard J
2014-01-01
Background Loss of lumbar lordosis has been reported after lumbar interbody fusion surgery and may portend poor clinical and radiographic outcome. The objective of this research was to measure changes in segmental and global lumbar lordosis in patients treated with presacral axial L4-S1 interbody fusion and posterior instrumentation and to determine if these changes influenced patient outcomes. Methods We performed a retrospective, multi-center review of prospectively collected data in 58 consecutive patients with disabling lumbar pain and radiculopathy unresponsive to nonsurgical treatment who underwent L4-S1 interbody fusion with the AxiaLIF two-level system (Baxano Surgical, Raleigh NC). Main outcomes included back pain severity, Oswestry Disability Index (ODI), Odom's outcome criteria, and fusion status using flexion and extension radiographs and computed tomography scans. Segmental (L4-S1) and global (L1-S1) lumbar lordosis measurements were made using standing lateral radiographs. All patients were followed for at least 24 months (mean: 29 months, range 24-56 months). Results There was no bowel injury, vascular injury, deep infection, neurologic complication or implant failure. Mean back pain severity improved from 7.8±1.7 at baseline to 3.3±2.6 at 2 years (p lordosis, defined as a change in Cobb angle ≤ 5°, was identified in 84% of patients at L4-S1 and 81% of patients at L1-S1. Patients with loss or gain in segmental or global lordosis experienced similar 2-year outcomes versus those with less than a 5° change. Conclusions/Clinical Relevance Two-level axial interbody fusion supplemented with posterior fixation does not alter segmental or global lordosis in most patients. Patients with postoperative change in lordosis greater than 5° have similarly favorable long-term clinical outcomes and fusion rates compared to patients with less than 5° lordosis change. PMID:25694920
AUTHOR|(SzGeCERN)749939
2015-01-01
As the volume of electronically available information grows, relevant items become harder to find. This work presents an approach to personalizing search results in scientific publication databases. This work focuses on re-ranking search results from existing search engines like Solr or ElasticSearch. This work also includes the development of Obelix, a new recommendation system used to re-rank search results. The project was proposed and performed at CERN, using the scientific publications available on the CERN Document Server (CDS). This work experiments with re-ranking using offline and online evaluation of users and documents in CDS. The experiments conclude that the personalized search result outperform both latest first and word similarity in terms of click position in the search result for global search in CDS.
Schrijvers, Tom; Wuille, Pieter; Samulowitz, Horst; Stuckey, Peter J
2012-01-01
The ability to model search in a constraint solver can be an essential asset for solving combinatorial problems. However, existing infrastructure for defining search heuristics is often inadequate. Either modeling capabilities are extremely limited or users are faced with a general-purpose programming language whose features are not tailored towards writing search heuristics. As a result, major improvements in performance may remain unexplored. This article introduces search combinators, a lightweight and solver-independent method that bridges the gap between a conceptually simple modeling language for search (high-level, functional and naturally compositional) and an efficient implementation (low-level, imperative and highly non-modular). By allowing the user to define application-tailored search strategies from a small set of primitives, search combinators effectively provide a rich domain-specific language (DSL) for modeling search to the user. Remarkably, this DSL comes at a low implementation cost to the...
Butler, Ricky W.; Boerschlein, David P.
1993-01-01
Fault-Tree Compiler (FTC) program, is software tool used to calculate probability of top event in fault tree. Gates of five different types allowed in fault tree: AND, OR, EXCLUSIVE OR, INVERT, and M OF N. High-level input language easy to understand and use. In addition, program supports hierarchical fault-tree definition feature, which simplifies tree-description process and reduces execution time. Set of programs created forming basis for reliability-analysis workstation: SURE, ASSIST, PAWS/STEM, and FTC fault-tree tool (LAR-14586). Written in PASCAL, ANSI-compliant C language, and FORTRAN 77. Other versions available upon request.
Categorizing Ideas about Trees: A Tree of Trees
Fisler, Marie; Lecointre, Guillaume
2013-01-01
The aim of this study is to explore whether matrices and MP trees used to produce systematic categories of organisms could be useful to produce categories of ideas in history of science. We study the history of the use of trees in systematics to represent the diversity of life from 1766 to 1991. We apply to those ideas a method inspired from coding homologous parts of organisms. We discretize conceptual parts of ideas, writings and drawings about trees contained in 41 main writings; we detect shared parts among authors and code them into a 91-characters matrix and use a tree representation to show who shares what with whom. In other words, we propose a hierarchical representation of the shared ideas about trees among authors: this produces a “tree of trees.” Then, we categorize schools of tree-representations. Classical schools like “cladists” and “pheneticists” are recovered but others are not: “gradists” are separated into two blocks, one of them being called here “grade theoreticians.” We propose new interesting categories like the “buffonian school,” the “metaphoricians,” and those using “strictly genealogical classifications.” We consider that networks are not useful to represent shared ideas at the present step of the study. A cladogram is made for showing who is sharing what with whom, but also heterobathmy and homoplasy of characters. The present cladogram is not modelling processes of transmission of ideas about trees, and here it is mostly used to test for proximity of ideas of the same age and for categorization. PMID:23950877
Directory of Open Access Journals (Sweden)
Ayse KOCALMIS BILHAN
2013-01-01
Full Text Available A space vector PWM method for a two level inverter is proposed in this paper. A two level inverter using space vector modulation strategy has been modeled and simulated with a passive R-L load. Photovoltaic cells are used as DC source for input of two-level inverter. Simulation results are presented for various operation conditions to verify the system model. In this paper, MATLAB/Simulink package program has been used for modeling and simulation of PV cells and two-level space vector pulse width modulation (SVPWM inverter.
Toet, A.; Bijl, P.
2003-01-01
Visual search, with or without the aid of optical or electro-optical instruments, plays a significant role in various types of military and civilian operations (e.g., reconnaissance, surveillance, and search and rescue). Advance knowledge of human visual search and target acquisition performance is
AUTHOR|(INSPIRE)INSPIRE-00359999; The ATLAS collaboration
2016-01-01
Flavour Changing Neutral Current (FCNC) processes are forbidden at tree level in the Standard Model (SM) and highly suppressed at NLO. This makes FCNC one of the key processes to look for new physics since any confirmation of them will be a signature of new physics. Both ATLAS and CMS collaborations have designed a comprehensive strategy to look FCNC in top quark physics both in the production and decay. In this talk an overview of the latest results on searches of FCNC is presented.
Directory of Open Access Journals (Sweden)
Yen Hung Chen
2012-01-01
minimum cost spanning tree T in G such that the total weight in T is at most a given bound B. In this paper, we present two polynomial time approximation schemes (PTASs for the constrained minimum spanning tree problem.
Low frequency critical current noise and two level system defects in Josephson junctions
Nugroho, Christopher Daniel
The critical current in a Josephson junction is known to exhibit a 1/falpha low frequency noise. Implemented as a superconducting qubit, this low frequency noise can lead to decoherence. While the 1/f noise has been known to arise from an ensemble of two level systems connected to the tunnel barrier, the precise microscopic nature of these TLSs remain a mystery. In this thesis we will present measurements of the 1/f alpha low frequency noise in the critical current and tunneling resistance of Al-AlOx-Al Josephson junctions. Measurements in a wide range of resistively shunted and unshunted junctions confirm the equality of critical current and tunneling resistance noise. That is the critical current fluctuation corresponds to fluctuations of the tunneling resistance. In not too small Al-AlOx-Al junctions we have found that the fractional power spectral density scales linearly with temperature. We confirmed that the 1/falpha power spectrum is the result of a large number of two level systems modulating the tunneling resistance. At small junction areas and low temperatures, the number of thermally active TLSs is insufficient to integrate out a featureless 1/ f spectral shape. By analyzing the spectral variance in small junction areas, we have been able to deduce the TLS defect density, n ≈ 2.53 per micrometer squared per Kelvin spread in the TLS energy per factor e in the TLS lifetimes. This density is consistent with the density of tunneling TLSs found in glassy insulators, as well as the density deduced from coherent TLSs interacting at qubit frequencies. The deduced TLS density combined with the magnitude of the 1/f power spectral density in large area junctions, gives an average TLS effective area, A ˜ 0.3 nanometer squared. In ultra small tunnel junctions, we have studied the time-domain dynamics of isolated TLSs. We have found a TLS whose dynamics is described by the quantum tunneling between the two localized wells, and a one-phonon absorption
Making Tree Ensembles Interpretable
Hara, Satoshi; Hayashi, Kohei
2016-01-01
Tree ensembles, such as random forest and boosted trees, are renowned for their high prediction performance, whereas their interpretability is critically limited. In this paper, we propose a post processing method that improves the model interpretability of tree ensembles. After learning a complex tree ensembles in a standard way, we approximate it by a simpler model that is interpretable for human. To obtain the simpler model, we derive the EM algorithm minimizing the KL divergence from the ...
Mitchell, William
1992-01-01
This paper, dating from May 1991, contains preliminary (and unpublishable) notes on investigations about iteration trees. They will be of interest only to the specialist. In the first two sections I define notions of support and embeddings for tree iterations, proving for example that every tree iteration is a direct limit of finite tree iterations. This is a generalization to models with extenders of basic ideas of iterated ultrapowers using only ultrapowers. In the final section (which is m...
DEFF Research Database (Denmark)
Baumbach, Jan; Guo, Jian-Ying; Ibragimov, Rashid
2013-01-01
We study the tree edit distance problem with edge deletions and edge insertions as edit operations. We reformulate a special case of this problem as Covering Tree with Stars (CTS): given a tree T and a set of stars, can we connect the stars in by adding edges between them such that the resulting ...
DEFF Research Database (Denmark)
Baumbach, Jan; Guo, Jiong; Ibragimov, Rashid
2015-01-01
We study the tree edit distance problem with edge deletions and edge insertions as edit operations. We reformulate a special case of this problem as Covering Tree with Stars (CTS): given a tree T and a set of stars, can we connect the stars in by adding edges between them such that the resulting ...
Engelfriet, Joost; Vogler, Heiko
1985-01-01
Macro tree transducers are a combination of top-down tree transducers and macro grammars. They serve as a model for syntax-directed semantics in which context information can be handled. In this paper the formal model of macro tree transducers is studied by investigating typical automata theoretical
Sweeney, Debra; Rounds, Judy
2011-01-01
Trees are great inspiration for artists. Many art teachers find themselves inspired and maybe somewhat obsessed with the natural beauty and elegance of the lofty tree, and how it changes through the seasons. One such tree that grows in several regions and always looks magnificent, regardless of the time of year, is the birch. In this article, the…
DEFF Research Database (Denmark)
Finbow, Arthur; Frendrup, Allan; Vestergaard, Preben D.
cardinality then G is a total well dominated graph. In this paper we study composition and decomposition of total well dominated trees. By a reversible process we prove that any total well dominated tree can both be reduced to and constructed from a family of three small trees....
Brooks, Sarah DeWitt
2010-01-01
This article describes the author's experience in implementing a Wish Tree project in her school in an effort to bring the school community together with a positive art-making experience during a potentially stressful time. The concept of a wish tree is simple: plant a tree; provide tags and pencils for writing wishes; and encourage everyone to…
Brooks, Sarah DeWitt
2010-01-01
This article describes the author's experience in implementing a Wish Tree project in her school in an effort to bring the school community together with a positive art-making experience during a potentially stressful time. The concept of a wish tree is simple: plant a tree; provide tags and pencils for writing wishes; and encourage everyone to…
Engelfriet, Joost; Vogler, Heiko
1985-01-01
Macro tree transducers are a combination of top-down tree transducers and macro grammars. They serve as a model for syntax-directed semantics in which context information can be handled. In this paper the formal model of macro tree transducers is studied by investigating typical automata theoretical
SILVA tree viewer: interactive web browsing of the SILVA phylogenetic guide trees.
Beccati, Alan; Gerken, Jan; Quast, Christian; Yilmaz, Pelin; Glöckner, Frank Oliver
2017-09-30
Phylogenetic trees are an important tool to study the evolutionary relationships among organisms. The huge amount of available taxa poses difficulties in their interactive visualization. This hampers the interaction with the users to provide feedback for the further improvement of the taxonomic framework. The SILVA Tree Viewer is a web application designed for visualizing large phylogenetic trees without requiring the download of any software tool or data files. The SILVA Tree Viewer is based on Web Geographic Information Systems (Web-GIS) technology with a PostgreSQL backend. It enables zoom and pan functionalities similar to Google Maps. The SILVA Tree Viewer enables access to two phylogenetic (guide) trees provided by the SILVA database: the SSU Ref NR99 inferred from high-quality, full-length small subunit sequences, clustered at 99% sequence identity and the LSU Ref inferred from high-quality, full-length large subunit sequences. The Tree Viewer provides tree navigation, search and browse tools as well as an interactive feedback system to collect any kinds of requests ranging from taxonomy to data curation and improving the tool itself.
Institute of Scientific and Technical Information of China (English)
Zeng Ke; Fang Mao-Fa
2005-01-01
The entanglement properties of the system of two two-level atoms interacting with a single-mode vacuum field are explored. The quantum entanglement between two two-level atoms and a single-mode vacuum field is investigated by using the quantum reduced entropy; the quantum entanglement between two two-level atoms, and that between a single two-level atom and a single-mode vacuum field are studied in terms of the quantum relative entropy. The influences of the atomic dipole-dipole interaction on the quantum entanglement of the system are also discussed. Our results show that three entangled states of two atoms-field, atom-atom, and atom-field can be prepared via two two-level atoms interacting with a single-mode vacuum field.
A Two-Level Task Scheduler on Multiple DSP System for OpenCL
Directory of Open Access Journals (Sweden)
Li Tian
2014-04-01
Full Text Available This paper addresses the problem that multiple DSP system does not support OpenCL programming. With the compiler, runtime, and the kernel scheduler proposed, an OpenCL application becomes portable not only between multiple CPU and GPU, but also between embedded multiple DSP systems. Firstly, the LLVM compiler was imported for source-to-source translation in which the translated source was supported by CCS. Secondly, two-level schedulers were proposed to support efficient OpenCL kernel execution. The DSP/BIOS is used to schedule system level tasks such as interrupts and drivers; however, the synchronization mechanism resulted in heavy overhead during task switching. So we designed an efficient second level scheduler especially for OpenCL kernel work-item scheduling. The context switch process utilizes the 8 functional units and cross path links which was superior to DSP/BIOS in the aspect of task switching. Finally, dynamic loading and software managed CACHE were redesigned for OpenCL running on multiple DSP system. We evaluated the performance using some common OpenCL kernels from NVIDIA, AMD, NAS, and Parboil benchmarks. Experimental results show that the DSP OpenCL can efficiently exploit the computing resource of multiple cores.
Yan, Yiying; Lü, Zhiguo; Zheng, Hang
2016-08-01
We present a theoretical formalism for resonance fluorescence radiating from a two-level system (TLS) driven by any periodic driving and coupled to multiple reservoirs. The formalism is derived analytically based on the combination of Floquet theory and Born-Markov master equation. The formalism allows us to calculate the spectrum when the Floquet states and quasienergies are analytically or numerically solved for simple or complicated driving fields. We can systematically explore the spectral features by implementing the present formalism. To exemplify this theory, we apply the unified formalism to comprehensively study a generic model that a harmonically driven TLS is simultaneously coupled to a radiative reservoir and a dephasing reservoir. We demonstrate that the significant features of the fluorescence spectra, the driving-induced asymmetry and the dephasing-induced asymmetry, can be attributed to the violation of detailed balance condition, and explained in terms of the driving-related transition quantities between Floquet-states and their steady populations. In addition, we find the distinguished features of the fluorescence spectra under the biharmonic and multiharmonic driving fields in contrast with that of the harmonic driving case. In the case of the biharmonic driving, we find that the spectra are significantly different from the result of the RWA under the multiple resonance conditions. By the three concrete applications, we illustrate that the present formalism provides a routine tool for comprehensively exploring the fluorescence spectrum of periodically strongly driven TLSs.
Energy Technology Data Exchange (ETDEWEB)
Yan, Yiying, E-mail: yiyingyan@sjtu.edu.cn; Lü, Zhiguo, E-mail: zglv@sjtu.edu.cn; Zheng, Hang, E-mail: hzheng@sjtu.edu.cn
2016-08-15
We present a theoretical formalism for resonance fluorescence radiating from a two-level system (TLS) driven by any periodic driving and coupled to multiple reservoirs. The formalism is derived analytically based on the combination of Floquet theory and Born–Markov master equation. The formalism allows us to calculate the spectrum when the Floquet states and quasienergies are analytically or numerically solved for simple or complicated driving fields. We can systematically explore the spectral features by implementing the present formalism. To exemplify this theory, we apply the unified formalism to comprehensively study a generic model that a harmonically driven TLS is simultaneously coupled to a radiative reservoir and a dephasing reservoir. We demonstrate that the significant features of the fluorescence spectra, the driving-induced asymmetry and the dephasing-induced asymmetry, can be attributed to the violation of detailed balance condition, and explained in terms of the driving-related transition quantities between Floquet-states and their steady populations. In addition, we find the distinguished features of the fluorescence spectra under the biharmonic and multiharmonic driving fields in contrast with that of the harmonic driving case. In the case of the biharmonic driving, we find that the spectra are significantly different from the result of the RWA under the multiple resonance conditions. By the three concrete applications, we illustrate that the present formalism provides a routine tool for comprehensively exploring the fluorescence spectrum of periodically strongly driven TLSs.
Equivalence of the measures of non-Markovianity for open two-level systems
Zeng, Hao-Sheng; Tang, Ning; Zheng, Yan-Ping; Wang, Guo-You
2011-09-01
Different measures have been presented to depict the deviation of quantum time evolution in open systems from Markovian processes. We demonstrate that the measure proposed by Breuer, Laine, and Piilo [Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.103.210401 103, 210401 (2009)] and the two measures proposed by Rivas, Huelga, and Plenio [Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.105.050403 105, 050403 (2010)] have exactly the same non-Markovian time-evolution intervals and thus are really equivalent to each other when they are applied to open two-level systems coupled to environments via the Jaynes-Cummings or dephasing models. This equivalence implies that the three measures, in different ways, capture the intrinsic character of the non-Markovianity of quantum evolutional processes. We also show that the maximization in the definition of the first measure can be actually removed for the considered models without influencing the sensibility of the measure to detect non-Markovianity.
Grid trust based on pre-measure and two-level reputation
Institute of Scientific and Technical Information of China (English)
ZHANG Lin; WANG Ru-chuan; WANG Hai-yan
2007-01-01
Security has been the focus of grid systems recently. As a kind of tool, grid security infrastructure (GSI) provides the authentication and authorization services and so on. These mechanisms mostly belong to the objective factors, which have not met the needs of security. As the subjective factor, trust model plays an important role in security field. A new two-level reputation trust architecture for grid is given to reduce the costs of system management largely, in which trust relationships amongst virtual organizations (VOs) are built on domain trust managers (DTMs) rather than resource nodes (RNs). Taking inter-domain trust propagation for example, trust model is improved by integrating global reputation and the subjective trust concept of each recommender into synthesizing final trust value. Moreover, before the grid starts to interact with the trustworthy entities, the pre-measure scheme is presented to filter distrustful entities further, which is based on accuracy and honesty. Experimental results indicate that the model can prevent from the malicious attacks better.
Proposing a two-level stochastic model for epileptic seizure genesis.
Shayegh, F; Sadri, S; Amirfattahi, R; Ansari-Asl, K
2014-02-01
By assuming the brain as a multi-stable system, different scenarios have been introduced for transition from normal to epileptic state. But, the path through which this transition occurs is under debate. In this paper a stochastic model for seizure genesis is presented that is consistent with all scenarios: a two-level spontaneous seizure generation model is proposed in which, in its first level the behavior of physiological parameters is modeled with a stochastic process. The focus is on some physiological parameters that are essential in simulating different activities of ElectroEncephaloGram (EEG), i.e., excitatory and inhibitory synaptic gains of neuronal populations. There are many depth-EEG models in which excitatory and inhibitory synaptic gains are the adjustable parameters. Using one of these models at the second level, our proposed seizure generator is complete. The suggested stochastic model of first level is a hidden Markov process whose transition matrices are obtained through analyzing the real parameter sequences of a seizure onset area. These real parameter sequences are estimated from real depth-EEG signals via applying a parameter identification algorithm. In this paper both short-term and long-term validations of the proposed model are done. The long-term synthetic depth-EEG signals simulated by this model can be taken as a suitable tool for comparing different seizure prediction algorithms.
The excitation of a two-level atom by a propagating light pulse
Wang, Yimin; Scarani, Valerio
2010-01-01
State mapping between atoms and photons, and photon-photon interactions play an important role in scalable quantum information processing. We consider the interaction of a two-level atom with a quantized \\textit{propagating} pulse in free space and study the probability $P_e(t)$ of finding the atom in the excited state at any time $t$. This probability is expected to depend on (i) the quantum state of the pulse field and (ii) the overlap between the pulse and the dipole pattern of the atomic spontaneous emission. In the full three-dimensional vector model for the field, we show that the second effect is captured by a single parameter $\\Lambda\\in[0,8\\pi/3]$, obtained by weighing the numerical aperture with the dipole pattern. Then $P_e(t)$ can be obtained by solving time-dependent Heisenberg-Langevin equations. We provide detailed solutions for both single-photon states and coherent states and for various shapes of the pulse.
Absorption spectrum of a two-level system subjected to a periodic pulse sequence
Fotso, H. F.; Dobrovitski, V. V.
2017-06-01
We investigate how the quantum control of a two-level system (TLS) coupled to photons can modify and tune the TLS's photon absorption spectrum. Tuning and controlling the emission and the absorption are of great interest, e.g., for the development of efficient interfaces between stationary and flying qubits in modern architectures for quantum computation and quantum communication. We consider periodic pulse control, where the TLS is subjected to a periodic sequence of the near-resonant Rabi driving pulses, each pulse implementing a 180∘ rotation. For small interpulse delays, the absorption spectrum features a pronounced peak of stimulated emission at the pulse frequency, similar satellite peaks with smaller spectral weights, and the net absorption peaks on the sides. As long as the detuning between the carrier frequency of the driving and the TLS transition frequency remains moderate, this spectral shape shows little change. Therefore, the pulse control allows shifting the absorption peak to a desired position and locks the overall absorption spectrum to the carrier frequency of the driving pulses. A detailed description of the spectrum and its evolution as a function time, the interpulse spacing, and the detuning is presented.
Non-Markovian dynamics of quantum coherence of two-level system driven by classical field
Huang, Zhiming; Situ, Haozhen
2017-09-01
In this paper, we study the quantum coherence dynamics of two-level atom system embedded in non-Markovian reservoir in the presence of classical driving field. We analyze the influence of memory effects, classical driving, and detuning on the quantum coherence. It is found that the quantum coherence has different behaviors in resonant case and non-resonant case. In the resonant case, in stark contrast with previous results, the strength of classical driving plays a negative effect on quantum coherence, while detuning parameter has the opposite effect. However, in non-resonant case through a long time, classical driving and detuning parameter have a different influence on quantum coherence compared with resonant case. Due to the memory effect of environment, in comparison with Markovian regime, quantum coherence presents vibrational variations in non-Markovian regime. In the resonant case, all quantum coherence converges to a fixed maximum value; in the non-resonant case, quantum coherence evolves to different stable values. For zero-coherence initial states, quantum coherence can be generated with evolution time. Our discussions and results should be helpful in manipulating and preserving the quantum coherence in dissipative environment with classical driving field.
Yang, Xingwang; Qian, Jing; Jiang, Ling; Yan, Yuting; Wang, Kan; Liu, Qian; Wang, Kun
2014-04-01
Ochratoxin A (OTA) has a number of toxic effects to both humans and animals, so developing sensitive detection method is of great importance. Herein, we describe an ultrasensitive electrochemical aptasensor for OTA based on the two-level cascaded signal amplification strategy with methylene blue (MB) as a redox indicator. In this method, capture DNA, aptamers, and reporter DNA functionalized-gold nanoparticles (GNPs) were immobilized on the electrode accordingly, where GNPs were used as the first-level signal enhancer. To receive the more sensitive response, a larger number of guanine (G)-rich DNA was bound to the GNPs' surface to provide abundant anchoring sites for MB to achieve the second-level signal amplification. By employing this novel strategy, an ~8.5 (±0.3) fold amplification in signal intensity was obtained. Afterward, OTA was added to force partial GNPs/G-rich DNA to release from the sensing interface and thus decreased the electrochemical response. An effective sensing range from 2.5pM to 2.5nM was received with an extremely low detection limit of 0.75 (±0.12) pM. This amplification strategy has the potential to be the main technology for aptamer-based electrochemical biosensor in a variety of fields.
Formulation and Solution ofTwo-Level Capacitated Lot-Sizing Problem
Directory of Open Access Journals (Sweden)
Mohsen Basti
2016-06-01
Full Text Available The integration of sequencing decisions in lot-sizing and scheduling problems has received an increased attention from the research community due to its inherent applicability to the real-world problems. In this paper, we develop and solve a synchronized and integrated two-level lot-sizing and scheduling problem motivated by a real-world problem arisen in the soft drink production. The soft drink production process has two main stages: flavor preparation (Stage1 and bottling (Stage2. In Stage 1, the liquid flavor (concentrated syrup plus some water is prepared in tanks with various capacities. In Stage 2 in which the liquid flavors are bottled at the filling lines. we considered stock capacityconstraint, and shortages of the combination(shortages backlog and lost sales added to the model. The aim is to determine the lot-sizing and scheduling raw materials and products so that the soft drink flavors and bottle types are assigned to the tanks and bottling lines, respectively, in order to meet a known weekly product demand. Finally, we implement LINGO solver to solve this model.
Regular and Chaotic Quantum Dynamics of Two-Level Atoms in a Selfconsistent Radiation Field
Konkov, L. E.; Prants, S. V.
1996-01-01
Dynamics of two-level atoms interacting with their own radiation field in a single-mode high-quality resonator is considered. The dynamical system consists of two second-order differential equations, one for the atomic SU(2) dynamical-group parameter and another for the field strength. With the help of the maximal Lyapunov exponent for this set, we numerically investigate transitions from regularity to deterministic quantum chaos in such a simple model. Increasing the collective coupling constant b is identical with 8(pi)N(sub 0)(d(exp 2))/hw, we observed for initially unexcited atoms a usual sharp transition to chaos at b(sub c) approx. equal to 1. If we take the dimensionless individual Rabi frequency a = Omega/2w as a control parameter, then a sequence of order-to-chaos transitions has been observed starting with the critical value a(sub c) approx. equal to 0.25 at the same initial conditions.
Spectral density of Cooper pairs in two level quantum dot–superconductors Josephson junction
Energy Technology Data Exchange (ETDEWEB)
Dhyani, A., E-mail: archana.d2003@gmail.com [Department of Physics, University of Petroleum and Energy Studies, Dehradun 248007, Uttarakhand (India); Rawat, P.S. [Department of Nuclear Science and Technology, University of Petroleum and Energy Studies, Dehradun 248007, Uttarakhand (India); Tewari, B.S., E-mail: bstewari@ddn.upes.ac.in [Department of Physics, University of Petroleum and Energy Studies, Dehradun 248007, Uttarakhand (India)
2016-09-15
Highlights: • The present work deals with the study of the electronic spectral density of electron pairs and its effect in charge transport in superconductor-quantum dot-superconductor junctions. • The charge transfer across such junctions can be controlled by changing the positions of the dot level. • The Josephson supercurrent can also be tuned by controlling the position of quantum dot energy levels. - Abstract: In the present paper, we report the role of quantum dot energy levels on the electronic spectral density for a two level quantum dot coupled to s-wave superconducting leads. The theoretical arguments in this work are based on the Anderson model so that it necessarily includes dot energies, single particle tunneling and superconducting order parameter for BCS superconductors. The expression for single particle spectral function is obtained by using the Green's function equation of motion technique. On the basis of numerical computation of spectral function of superconducting leads, it has been found that the charge transfer across such junctions can be controlled by the positions and availability of the dot levels.
An Energy-Efficient Instruction Scheduler Design with Two-Level Shelving and Adaptive Banking
Institute of Scientific and Technical Information of China (English)
Yu-Lai Zhao; Xian-Feng Li; Dong Tong; Xu Cheng
2007-01-01
Mainstream processors implement the instruction scheduler using a monolithic CAM-based issue queue (IQ),which consumes increasingly high energy as its size scales.In particular, its instruction wakeup logic accounts for a major portion of the consumed energy.Our study shows that instructions with 2 non-ready operands (called 2OP instructions) are in small percentage, but tend to spend long latencies in the IQ.They can be effectively shelved in a small RAM-based waiting instruction buffer (WIB) and steered into the IQ at appropriate time.With this two-level shelving ability, half of the CAM tag comparators are eliminated in the IQ, which significantly reduces the energy of wakeup operation.In addition,we propose an adaptive banking scheme to downsize the IQ and reduce the bit-width of tag comparators.Experiments indicate that for an 8-wide issue superscalar or SMT processor, the energy consumption of the instruction scheduler can be reduced by 67%.Furthermore, the new design has potentially faster scheduler clock speed while maintaining close IPC to the monolithic scheduler design.Compared with the previous work on eliminating tags through prediction, our design is superior in terms of both energy reduction and SMT support.
Sarabi, B; Ramanayaka, A N; Burin, A L; Wellstood, F C; Osborn, K D
2016-04-22
Material-based two-level systems (TLSs), appearing as defects in low-temperature devices including superconducting qubits and photon detectors, are difficult to characterize. In this study we apply a uniform dc electric field across a film to tune the energies of TLSs within. The film is embedded in a superconducting resonator such that it forms a circuit quantum electrodynamical system. The energy of individual TLSs is observed as a function of the known tuning field. By studying TLSs for which we can determine the tunneling energy, the actual p_{z}, dipole moments projected along the uniform field direction, are individually obtained. A distribution is created with 60 p_{z}. We describe the distribution using a model with two dipole moment magnitudes, and a fit yields the corresponding values p=p_{1}=2.8±0.2 D and p=p_{2}=8.3±0.4 D. For a strong-coupled TLS the vacuum-Rabi splitting can be obtained with p_{z} and tunneling energy. This allows a measurement of the circuit's zero-point electric-field fluctuations, in a method that does not need the electric-field volume.
Wen, Zaidao; Hou, Biao; Jiao, Licheng
2016-06-30
Discriminative dictionary learning (DDL) framework has been widely used in image classification which aims to learn some class-specific feature vectors as well as a representative dictionary according to a set of labeled training samples. However, interclass similarities and intraclass variances among input samples and learned features will generally weaken the representability of dictionary and the discrimination of feature vectors so as to degrade the classification performance. Therefore, how to explicitly represent them becomes an important issue. In this paper, we present a novel DDL framework with two-level low rank and group sparse decomposition model. In the first level, we learn a class-shared and several class-specific dictionaries, where a low rank and a group sparse regularization are, respectively, imposed on the corresponding feature matrices. In the second level, the class-specific feature matrix will be further decomposed into a low rank and a sparse matrix so that intraclass variances can be separated to concentrate the corresponding feature vectors. Extensive experimental results demonstrate the effectiveness of our model. Compared with the other state-of-the-arts on several popular image databases, our model can achieve a competitive or better performance in terms of the classification accuracy.
Quantum dynamics of a driven two-level molecule with variable dephasing
Grandi, Samuele; Major, Kyle D.; Polisseni, Claudio; Boissier, Sebastien; Clark, Alex S.; Hinds, E. A.
2016-12-01
The longitudinal (Γ1) and transverse (Γ2) decay rates of a two-level quantum system have a profound influence on its evolution. Atomic systems with Γ2=1/2 Γ1 have been studied extensively, but with the rise of solid-state quantum devices it is also important to consider the effect of stronger transverse relaxation due to interactions with the solid environment. Here we study the quantum dynamics of a single organic dye molecule driven by a laser. We measure the variation of Γ2 with temperature and determine the activation energy for thermal dephasing of the optical dipole. Then we measure the second-order correlation function g(2 )(τ ) of the light emitted by the molecule for various ratios Γ2/Γ1 and saturation parameters S . We show that the general solution to the optical Bloch equations accurately describes the observed quantum dynamics over a wide range of these parameters, and we discuss the limitations of the various approximate expressions for g(2 )(τ ) that appear in the literature.
Trophic groups and modules: two levels of group detection in food webs.
Gauzens, Benoit; Thébault, Elisa; Lacroix, Gérard; Legendre, Stéphane
2015-05-06
Within food webs, species can be partitioned into groups according to various criteria. Two notions have received particular attention: trophic groups (TGs), which have been used for decades in the ecological literature, and more recently, modules. The relationship between these two group concepts remains unknown in empirical food webs. While recent developments in network theory have led to efficient methods for detecting modules in food webs, the determination of TGs (groups of species that are functionally similar) is largely based on subjective expert knowledge. We develop a novel algorithm for TG detection. We apply this method to empirical food webs and show that aggregation into TGs allows for the simplification of food webs while preserving their information content. Furthermore, we reveal a two-level hierarchical structure where modules partition food webs into large bottom-top trophic pathways, whereas TGs further partition these pathways into groups of species with similar trophic connections. This provides new perspectives for the study of dynamical and functional consequences of food-web structure, bridging topological and dynamical analysis. TGs have a clear ecological meaning and are found to provide a trade-off between network complexity and information loss.
Amplification without inversion, fast light and optical bistability in a duplicated two-level system
Energy Technology Data Exchange (ETDEWEB)
Ebrahimi Zohravi, Lida; Vafafard, Azar; Mahmoudi, Mohammad, E-mail: mahmoudi@znu.ac.ir
2014-07-01
The optical properties of a weak probe field in a duplicated two-level system are investigated in multi-photon resonance (MPR) condition and beyond it. It is shown that by changing the relative phase of applied fields, the absorption switches to the amplification without inversion in MPR condition. By applying the Floquet decomposition to the equations of motion beyond MPR condition, it is shown that the phase-dependent behavior is valid only in MPR condition. Moreover, it is demonstrated that the group velocity of light pulse can be controlled by the intensity of the applied fields and the gain-assisted superluminal light propagation (fast light) is obtained in this system. In addition, the optical bistability (OB) behavior of the system is studied beyond MPR condition. We apply an indirect incoherent pumping field to the system and it is found that the group velocity and OB behavior of the system can be controlled by the incoherent pumping rate. - Highlights: • We studied the optical properties of DTL system under MPR condition and beyond it. • By changing the relative phase, the absorption switches to the amplification without inversion in MPR condition. • The gain-assisted superluminal light propagation (fast light) is obtained in this system. • The optical bistability (OB) behavior of the system is studied beyond MPR condition. • The incoherent pumping rate has a major role in controlling the group velocity and OB behavior of the system.
Preventing IP Source Address Spoofing: A Two-Level,State Machine-Based Method
Institute of Scientific and Technical Information of China (English)
BI Jun; LIU Bingyang; WU Jianping; SHEN Yan
2009-01-01
A signature-and-verification-based method, automatic peer-to-peer anti-spoofing (APPA), is pro-posed to prevent IP source address spoofing. In this method, signatures are tagged into the packets at the source peer, and verified and removed at the verification peer where packets with incorrect signatures are filtered. A unique state machine, which is used to generate signatures, is associated with each ordered pair of APPA peers. As the state machine automatically transits, the signature changes accordingly. KISS ran-dom number generator is used as the signature generating algorithm, which makes the state machine very small and fast and requires very low management costs. APPA has an intre-AS (autonomous system) level and an inter-AS level. In the intra-AS level, signatures are tagged into each departing packet at the host and verified at the gateway to achieve finer-grained anti-spoofing than ingress filtering. In the inter-AS level, signatures are tagged at the source AS border router and verified at the destination AS border muter to achieve prefix-level anti-spoofing, and the automatic state machine enables the peers to change signatures without negotiation which makes APPA attack-resilient compared with the spoofing prevention method. The results show that the two levels are both incentive for deployment, and they make APPA an integrated anti-spoofing solution.
Decoherence of a quantum two-level system by spectral diffusion
Matityahu, Shlomi; Shnirman, Alexander; Schön, Gerd; Schechter, Moshe
2016-04-01
We study the dephasing of an individual high-frequency tunneling two-level system (TLS) due to its interaction with an ensemble of low-frequency thermal TLSs which are described by the standard tunneling model (STM). We show that the dephasing by the bath of TLSs explains both the dependence of the Ramsey dephasing rate on an externally applied strain as well as its order of magnitude, as observed in a recent experiment [J. Lisenfeld et al., Sci. Rep. 6, 23786 (2016)], 10.1038/srep23786. However, the theory based on the STM predicts the Hahn-echo protocol to be much more efficient, yielding too low echo dephasing rates, as compared to the experiment. Also the strain dependence of the echo dephasing rate predicted by the STM does not agree with the measured quadratic dependence, which would fit to a high-frequency white noise environment. We suggest that few fast TLSs which are coupled much more strongly to the strain fields than the usual TLSs of the STM give rise to such a white noise. This explains the magnitude and strong fluctuations of the echo dephasing rate observed in the experiment.
Testing a Quantum Heat Pump with a Two-Level Spin
Correa, Luis; Mehboudi, Mohammad
2016-04-01
Once in its non-equilibrium steady state, a nanoscale system coupled to several heat baths may be thought-of as a quantum heat pump. Depending on the direction of its stationary heat flows it may function as e.g. a refrigerator or a heat transformer. These continuous heat devices can be arbitrarily complex multipartite systems, and yet their working principle is always the same: They are made up of several elementary three-level stages operating in parallel. As a result, it is possible to devise external black-box testing strategies to learn about their functionality and performance regardless of any internal details. In particular, one such heat pump can be tested by coupling a two-level spin to one of its contact transitions. The steady state of this external probe contains information about the presence of heat leaks and internal dissipation in the device, and also, about the direction of its steady-state heat currents. Provided that the irreversibility of the heat pump is low, one can further estimate its coefficient of performance. These techniques may find applications in the emerging field of quantum thermal engineering, as they facilitate the diagnosis and design optimization of complex thermodynamic cycles.
Testing a Quantum Heat Pump with a Two-Level Spin
Directory of Open Access Journals (Sweden)
Luis A. Correa
2016-04-01
Full Text Available Once in its non-equilibrium steady state, a nanoscale system coupled to several heat baths may be thought of as a “quantum heat pump”. Depending on the direction of its stationary heat flows, it may function as, e.g., a refrigerator or a heat transformer. These continuous heat devices can be arbitrarily complex multipartite systems, and yet, their working principle is always the same: they are made up of several elementary three-level stages operating in parallel. As a result, it is possible to devise external “black-box” testing strategies to learn about their functionality and performance regardless of any internal details. In particular, one such heat pump can be tested by coupling a two-level spin to one of its “contact transitions”. The steady state of this external probe contains information about the presence of heat leaks and internal dissipation in the device and, also, about the direction of its steady-state heat currents. Provided that the irreversibility of the heat pump is low, one can further estimate its coefficient of performance. These techniques may find applications in the emerging field of quantum thermal engineering, as they facilitate the diagnosis and design optimization of complex thermodynamic cycles.
SPONGY (SPam ONtoloGY): email classification using two-level dynamic ontology.
Youn, Seongwook
2014-01-01
Email is one of common communication methods between people on the Internet. However, the increase of email misuse/abuse has resulted in an increasing volume of spam emails over recent years. An experimental system has been designed and implemented with the hypothesis that this method would outperform existing techniques, and the experimental results showed that indeed the proposed ontology-based approach improves spam filtering accuracy significantly. In this paper, two levels of ontology spam filters were implemented: a first level global ontology filter and a second level user-customized ontology filter. The use of the global ontology filter showed about 91% of spam filtered, which is comparable with other methods. The user-customized ontology filter was created based on the specific user's background as well as the filtering mechanism used in the global ontology filter creation. The main contributions of the paper are (1) to introduce an ontology-based multilevel filtering technique that uses both a global ontology and an individual filter for each user to increase spam filtering accuracy and (2) to create a spam filter in the form of ontology, which is user-customized, scalable, and modularized, so that it can be embedded to many other systems for better performance.
Nonadiabatic transitions for a decaying two-level system: geometrical and dynamical contributions
Energy Technology Data Exchange (ETDEWEB)
Schilling, R [Institute of Physics, Johannes Gutenberg-Universitaet Mainz, Staudinger Weg 7, D-55099 Mainz (Germany); Vogelsberger, Mark [Institute of Physics, Johannes Gutenberg-Universitaet Mainz, Staudinger Weg 7, D-55099 Mainz (Germany); Garanin, D A [Physics Department, Lehman College, City University of New York, 250 Bedford Park Boulevard West, Bronx, NY 10468-1589 (United States)
2006-11-03
We study the Landau-Zener problem for a decaying two-level system described by a non-Hermitian Hamiltonian, depending analytically on time. Use of a super-adiabatic basis allows us to calculate the survival probability P in the slow-sweep limit, without specifying the Hamiltonian explicitly. It is found that P consists of a 'dynamical' and a 'geometrical' factor. The former is determined by the complex adiabatic eigenvalues E{sub {+-}}(t), only, whereas the latter solely requires the knowledge of {alpha}{sub {+-}}(t), the ratio of the components of each of the adiabatic eigenstates. Both factors can be split into a universal one, depending only on the complex level crossing points, and a nonuniversal one, involving the full time dependence of E{sub {+-}}(t) and {alpha}{sub {+-}}(t). This general result is applied to the Akulin-Schleich model where the initial upper level is damped with damping constant {gamma}. For analytic power-law sweeps we find that Stueckelberg oscillations of P exist for {gamma} smaller than a critical value {gamma}{sub c} and disappear for {gamma} > {gamma}{sub c}. A physical interpretation of this behaviour will be presented by use of a damped harmonic oscillator.
Nakasato, N
2009-01-01
The kd-tree is a fundamental tool in computer science. Among others, an application of the kd-tree search (oct-tree method) to fast evaluation of particle interactions and neighbor search is highly important since computational complexity of these problems are reduced from O(N^2) with a brute force method to O(N log N) with the tree method where N is a number of particles. In this paper, we present a parallel implementation of the tree method running on a graphic processor unit (GPU). We successfully run a simulation of structure formation in the universe very efficiently. On our system, which costs roughly $900, the run with N ~ 2.87x10^6 particles took 5.79 hours and executed 1.2x10^13 force evaluations in total. We obtained the sustained computing speed of 21.8 Gflops and the cost per Gflops of 41.6/Gflops that is two and half times better than the previous record in 2006.
Prefetching J+-Tree: A Cache-Optimized Main Memory Database Index Structure
Institute of Scientific and Technical Information of China (English)
Hua Luan; Xiao-Yong Du; Sha Wang
2009-01-01
As the speed gap between main memory and modern processors continues to widen, the cache behavior becomes more important for main memory database systems (MMDBs). Indexing technique is a key component of MMDBs. Unfortunately, the predominant indexes -- B+-trees and T-trees -- have been shown to utilize cache poorly, which triggers the development of many cache-conscious indexes, such as CSB+-trees and pB+-trees. Most of these cache-conscious indexes are variants of conventional B+-trees, and have better cache performance than B+-trees. In this paper, we develop a novel J+-tree index, inspired by the Judy structure which is an associative array data structure, and propose a more cacheoptimized index -- Prefetching J+-tree (pJ+-tree), which applies prefetching to J+-tree to accelerate range scan operations. The J+-tree stores all the keys in its leaf nodes and keeps the reference values of leaf nodes in a Judy structure, which makes J+-tree not only hold the advantages of Judy (such as fast single value search) but also outperform it in other aspects. For example, J+-trees can achieve better performance on range queries than Judy. The pJ+-tree index exploits prefetching techniques to further improve the cache behavior of J+-trees and yields a speedup of 2.0 on range scans. Compared with B+-trees, CSB+-trees, pB+-trees and T-trees, our extensive experimental study shows that pJ+-trees can provide better performance on both time (search, scan, update) and space aspects.
New algorithms for radio pulsar search
Smith, Kendrick M
2016-01-01
The computational cost of searching for new pulsars is a limiting factor for upcoming radio telescopes such as SKA. We introduce four new algorithms: an optimal constant-period search, a coherent tree search which permits optimal searching with O(1) cost per model, a semicoherent search which combines information from coherent subsearches while preserving as much phase information as possible, and a hierarchical search which interpolates between the coherent and semicoherent limits. Taken together, these algorithms improve the computational cost of pulsar search by several orders of magnitude. In this paper, we consider the simple case of a constant-acceleration phase model, but our methods should generalize to more complex search spaces.
Institute of Scientific and Technical Information of China (English)
Degyi
2008-01-01
Trees are flourishing in Lhasa wherever the history exists. There is such a man. He has already been through cus-toms after his annual trek to Lhasa, which he has been doing for over twenty years in succession to visit his tree.Although he has been making this journey for so long,it is neither to visit friends or family,nor is it his hometown.It is a tree that is tied so profoundly to his heart.When the wind blows fiercely on the bare tree and winter snow falls,he stands be-fore the tree with tears of jo...
Energy Technology Data Exchange (ETDEWEB)
Morozov, Dmitriy; Weber, Gunther H.
2014-03-31
Topological techniques provide robust tools for data analysis. They are used, for example, for feature extraction, for data de-noising, and for comparison of data sets. This chapter concerns contour trees, a topological descriptor that records the connectivity of the isosurfaces of scalar functions. These trees are fundamental to analysis and visualization of physical phenomena modeled by real-valued measurements. We study the parallel analysis of contour trees. After describing a particular representation of a contour tree, called local{global representation, we illustrate how di erent problems that rely on contour trees can be solved in parallel with minimal communication.
Chinese Term Extraction Based on PAT Tree
Institute of Scientific and Technical Information of China (English)
ZHANG Feng; FAN Xiao-zhong; XU Yun
2006-01-01
A new method of automatic Chinese term extraction is proposed based on Patricia (PAT) tree. Mutual information is calculated based on prefix searching in PAT tree of domain corpus to estimate the internal associative strength between Chinese characters in a string. It can improve the speed of term candidate extraction largely compared with methods based on domain corpus directly. Common collocation suffix, prefix bank are constructed and term part of speech (POS) composing rules are summarized to improve the precision of term extraction. Experiment results show that the F-measure is 74.97 %.
A survey of decision tree classifier methodology
Safavian, S. R.; Landgrebe, David
1991-01-01
Decision tree classifiers (DTCs) are used successfully in many diverse areas such as radar signal classification, character recognition, remote sensing, medical diagnosis, expert systems, and speech recognition. Perhaps the most important feature of DTCs is their capability to break down a complex decision-making process into a collection of simpler decisions, thus providing a solution which is often easier to interpret. A survey of current methods is presented for DTC designs and the various existing issues. After considering potential advantages of DTCs over single-state classifiers, subjects of tree structure design, feature selection at each internal node, and decision and search strategies are discussed.
Rollinson, Susan Wells
2012-01-01
The growth of a pine tree is examined by preparing "tree cookies" (cross-sectional disks) between whorls of branches. The use of Christmas trees allows the tree cookies to be obtained with inexpensive, commonly available tools. Students use the tree cookies to investigate the annual growth of the tree and how it corresponds to the number of whorls…
Rollinson, Susan Wells
2012-01-01
The growth of a pine tree is examined by preparing "tree cookies" (cross-sectional disks) between whorls of branches. The use of Christmas trees allows the tree cookies to be obtained with inexpensive, commonly available tools. Students use the tree cookies to investigate the annual growth of the tree and how it corresponds to the number of whorls…
A two level mutation-selection model of cultural evolution and diversity.
Salazar-Ciudad, Isaac
2010-11-21
Cultural evolution is a complex process that can happen at several levels. At the level of individuals in a population, each human bears a set of cultural traits that he or she can transmit to its offspring (vertical transmission) or to other members of his or her society (horizontal transmission). The relative frequency of a cultural trait in a population or society can thus increase or decrease with the relative reproductive success of its bearers (individual's level) or the relative success of transmission (called the idea's level). This article presents a mathematical model on the interplay between these two levels. The first aim of this article is to explore when cultural evolution is driven by the idea's level, when it is driven by the individual's level and when it is driven by both. These three possibilities are explored in relation to (a) the amount of interchange of cultural traits between individuals, (b) the selective pressure acting on individuals, (c) the rate of production of new cultural traits, (d) the individual's capacity to remember cultural traits and to the population size. The aim is to explore the conditions in which cultural evolution does not lead to a better adaptation of individuals to the environment. This is to contrast the spread of fitness-enhancing ideas, which make individual bearers better adapted to the environment, to the spread of "selfish" ideas, which spread well simply because they are easy to remember but do not help their individual bearers (and may even hurt them). At the same time this article explores in which conditions the adaptation of individuals is maximal. The second aim is to explore how these factors affect cultural diversity, or the amount of different cultural traits in a population. This study suggests that a larger interchange of cultural traits between populations could lead to cultural evolution not improving the adaptation of individuals to their environment and to a decrease of cultural diversity.
A two level hierarchical model of protein retention in ion exchange chromatography.
Salvalaglio, Matteo; Paloni, Matteo; Guelat, Bertrand; Morbidelli, Massimo; Cavallotti, Carlo
2015-09-11
Predicting protein retention in ion exchange chromatography (IEX) from first principles is a fascinating perspective. In this work a two level hierarchical modeling strategy is proposed in order to calculate protein retention factors. Model predictions are tested against experimental data measured for Lysozyme and Chymotrypsinogen A in IEX columns as a function of ionic strength and pH. At the highest level of accuracy Molecular Dynamics (MD) simulations in explicit water are used to determine the interaction free energy between each of the two proteins and the IEX stationary phase for a reference pH and ionic strength. At a lower level of accuracy a linear response model based on an implicit treatment of solvation and adopting a static protein structure is used to calculate interaction free energies for the full range of pHs and ionic strengths considered. A scaling coefficient, determined comparing MD and implicit solvent simulations, is then introduced in order to correct the linear response model for errors induced by the adoption of a static protein structure. The calculated free energies are then used to compute protein retention factors, which can be directly compared with experimental data. The possibility to introduce a third level of accuracy is explored testing the predictions of a semiempirical model. A quantitative agreement between the predicted and measured protein retention factors is obtained using the coupled MD-linear response models, supporting the reliability of the proposed approach. The model allows quantifying the electrostatic, van der Waals, and conformational contributions to the interaction free energies. A good agreement between experiments and model is obtained also using the semiempirical model that, although requiring parameterization over higher level models or experimental data, proves to be useful in order to rapidly determine protein retention factors across wide pH and ionic strength ranges as it is computationally inexpensive.
Programming macro tree transducers
DEFF Research Database (Denmark)
Bahr, Patrick; Day, Laurence E.
2013-01-01
A tree transducer is a set of mutually recursive functions transforming an input tree into an output tree. Macro tree transducers extend this recursion scheme by allowing each function to be defined in terms of an arbitrary number of accumulation parameters. In this paper, we show how macro tree...... transducers can be concisely represented in Haskell, and demonstrate the benefits of utilising such an approach with a number of examples. In particular, tree transducers afford a modular programming style as they can be easily composed and manipulated. Our Haskell representation generalises the original...... definition of (macro) tree transducers, abolishing a restriction on finite state spaces. However, as we demonstrate, this generalisation does not affect compositionality....
Programming macro tree transducers
DEFF Research Database (Denmark)
Bahr, Patrick; Day, Laurence E.
2013-01-01
A tree transducer is a set of mutually recursive functions transforming an input tree into an output tree. Macro tree transducers extend this recursion scheme by allowing each function to be defined in terms of an arbitrary number of accumulation parameters. In this paper, we show how macro tree...... transducers can be concisely represented in Haskell, and demonstrate the benefits of utilising such an approach with a number of examples. In particular, tree transducers afford a modular programming style as they can be easily composed and manipulated. Our Haskell representation generalises the original...... definition of (macro) tree transducers, abolishing a restriction on finite state spaces. However, as we demonstrate, this generalisation does not affect compositionality....
Tunkelang, Daniel
2009-01-01
We live in an information age that requires us, more than ever, to represent, access, and use information. Over the last several decades, we have developed a modern science and technology for information retrieval, relentlessly pursuing the vision of a "memex" that Vannevar Bush proposed in his seminal article, "As We May Think." Faceted search plays a key role in this program. Faceted search addresses weaknesses of conventional search approaches and has emerged as a foundation for interactive information retrieval. User studies demonstrate that faceted search provides more
morePhyML: improving the phylogenetic tree space exploration with PhyML 3.
Criscuolo, Alexis
2011-12-01
PhyML is a widely used Maximum Likelihood (ML) phylogenetic tree inference software based on a standard hill-climbing method. Starting from an initial tree, the version 3 of PhyML explores the tree space by using "Nearest Neighbor Interchange" (NNI) or "Subtree Pruning and Regrafting" (SPR) tree swapping techniques in order to find the ML phylogenetic tree. NNI-based local searches are fast but can often get trapped in local optima, whereas it is expected that the larger (but slower to cover) SPR-based neighborhoods will lead to trees with higher likelihood. Here, I verify that PhyML infers more likely trees with SPRs than with NNIs in almost all cases. However, I also show that the SPR-based local search of PhyML often does not succeed at locating the ML tree. To improve the tree space exploration, I deliver a script, named morePhyML, which allows escaping from local optima by performing character reweighting. This ML tree search strategy, named ratchet, often leads to higher likelihood estimates. Based on the analysis of a large number of amino acid and nucleotide data, I show that morePhyML allows inferring more accurate phylogenetic trees than several other recently developed ML tree inference softwares in many cases.
Directory of Open Access Journals (Sweden)
M. R. Abdullah
2017-02-01
Full Text Available This study aims to identify the essential performance indicators in two level of soccer expertise. A total of 84 elite’s soccer players and 100 novice players from eight soccer academies in Malaysia were enrolled and subjected to standard anthropometric, fitness, skills related performance testing and responded to the questionnaire in mastery and performance. Principal component analysis (PCA was employed to determine the most indispensable variables pertinent to the requirement of the game in relation to the level of expertise of the players. The initial PCA shows seven components out of 26 as the most significant for both elite and novice soccer players with a considerable eigenvalue > 1. Moreover, the PCA after varimax rotation highlighted seven principles components (PCs for elite and novice players respectively. Each of the seven components contained varifactors (VF selected based on their higher factor loading and that distinguish the players on their expertise. The first PCs for elite’s players revealed strong loading from sit and reach (0.780, vertical jump (0.635, VO2max (0.637 and age (0.752. The second PCs revealed weight (0.639, biceps (0.859, triceps (0.769, subscapular (0.847, suprailiac (0.886 and middle upper arm circumference (0.776. The third PCs revealed 505 agility (0.618, 5m speed (0.712, 10m speed (0.858 and 20m speed (0.929. The forth PCs revealed task (-0.675 and short pass (0.789 and the last PCs revealed sit up (-0.702. For novice’s players, the first PCs revealed vertical jump (0.624, weight (0.861, height (0.856, sitting height (0.632, middle upper arm circumference (0.673, calf circumference (0.790 and maturity (0.651. The second PCs revealed biceps (0.832, triceps (0.899, subscapular (0.816 and suprailiac (0.869. The third PCs revealed 5m speed (-0.847, 10m speed (-0.877, 20m speed (-0.785 and VO2max (0.658. The forth PCs revealed task (0.694 and ego (0.747 and the last PCs revealed short pass (0.766.
Pattern Avoidance in Ternary Trees
Gabriel, Nathan; Pudwell, Lara; Tay, Samuel
2011-01-01
This paper considers the enumeration of ternary trees (i.e. rooted ordered trees in which each vertex has 0 or 3 children) avoiding a contiguous ternary tree pattern. We begin by finding recurrence relations for several simple tree patterns; then, for more complex trees, we compute generating functions by extending a known algorithm for pattern-avoiding binary trees. Next, we present an alternate one-dimensional notation for trees which we use to find bijections that explain why certain pairs of tree patterns yield the same avoidance generating function. Finally, we compare our bijections to known "replacement rules" for binary trees and generalize these bijections to a larger class of trees.
The Cost of Cache-Oblivious Searching
DEFF Research Database (Denmark)
Bender, Michael A.; Brodal, Gerth Stølting; Fagerberg, Rolf
2011-01-01
This paper gives tight bounds on the cost of cache-oblivious searching. The paper shows that no cache-oblivious search structure can guarantee a search performance of fewer than lg elog B N memory transfers between any two levels of the memory hierarchy. This lower bound holds even if all...... increases. The expectation is taken over the random placement in memory of the first element of the structure. Because searching in the disk-access machine (DAM) model can be performed in log B N+O(1) block transfers, this result establishes a separation between the (2-level) DAM model and cache......-oblivious model. The DAM model naturally extends to k levels. The paper also shows that as k grows, the search costs of the optimal k-level DAM search structure and the optimal cache-oblivious search structure rapidly converge. This result demonstrates that for a multilevel memory hierarchy, a simple cache...
NASA Indexing Benchmarks: Evaluating Text Search Engines
Esler, Sandra L.; Nelson, Michael L.
1997-01-01
The current proliferation of on-line information resources underscores the requirement for the ability to index collections of information and search and retrieve them in a convenient manner. This study develops criteria for analytically comparing the index and search engines and presents results for a number of freely available search engines. A product of this research is a toolkit capable of automatically indexing, searching, and extracting performance statistics from each of the focused search engines. This toolkit is highly configurable and has the ability to run these benchmark tests against other engines as well. Results demonstrate that the tested search engines can be grouped into two levels. Level one engines are efficient on small to medium sized data collections, but show weaknesses when used for collections 100MB or larger. Level two search engines are recommended for data collections up to and beyond 100MB.
Blundell, Charles; Heller, Katherine A
2012-01-01
Hierarchical structure is ubiquitous in data across many domains. There are many hier- archical clustering methods, frequently used by domain experts, which strive to discover this structure. However, most of these meth- ods limit discoverable hierarchies to those with binary branching structure. This lim- itation, while computationally convenient, is often undesirable. In this paper we ex- plore a Bayesian hierarchical clustering algo- rithm that can produce trees with arbitrary branching structure at each node, known as rose trees. We interpret these trees as mixtures over partitions of a data set, and use a computationally efficient, greedy ag- glomerative algorithm to find the rose trees which have high marginal likelihood given the data. Lastly, we perform experiments which demonstrate that rose trees are better models of data than the typical binary trees returned by other hierarchical clustering algorithms.
A study of two-level system defects in dielectric films using superconducting resonators
Khalil, Moe Shwan
In this dissertation I describe measurements of dielectric loss at microwave frequencies due to two level systems (TLS) using superconducting resonators. Most measurements were performed in a dilution refrigerator at temperatures between 30 and 200 mK and all resonators discussed were fabricated with thin-film superconducting aluminum. I derive the transmission through a non-ideal (mismatched) resonant circuit and find that in general the resonance line-shape is asymmetric. I describe an analysis method for extracting the internal quality factor (Q i), the diameter correction method (DCM), and compare it to a commonly used phenomenological method, the phi rotation method (phiRM). I analytically find that the phiRM deterministically overestimates Qi when the asymmetry of the resonance line-shape is high. Four coplanar resonator geometries were studied, with frequencies spanning 5-7 GHz. They were all superconducting aluminum fabricated on sapphire and silicon substrates. These include a quasi-lumped element resonator, a coplanar strip transmission line resonator, and two hybrid designs that contain both a coplanar strip and a quasi-lumped element. Measured Qi's were as high as 2 x 105 for single photon excitations and there was no systematic variation in loss between quasi-lumped and coplanar strip resonance modes. I also measured the microwave loss tangent of several atomic layer deposition (ALD) grown dielectrics and obtained secondary ion mass spectrometry (SIMS) measurements of the same films. I found that hydrogen defect concentrations were correlated with low temperature microwave loss. In amorphous films that showed excess hydrogen defects on the surface, two independent TLS distributions were required to fit the loss tangent, one for the surface and one for the bulk. In crystalline dielectrics where hydrogen contamination was uniform throughout the bulk, a single bulk TLS distribution was sufficient. Finally, I measured the TLS loss in 250 nm thick HD
Priority Queue Based on Multilevel Prefix Tree
Planeta, David S
2007-01-01
Tree structures are very often used data structures. Among ordered types of trees there are many variants whose basic operations such as insert, delete, search, delete-min are characterized by logarithmic time complexity. In the article I am going to present the structure whose time complexity for each of the above operations is $O(\\frac{M}{K} + K)$, where M is the size of data type and K is constant properly matching the size of data type. Properly matched K will make the structure function as a very effective Priority Queue. The structure size linearly depends on the number and size of elements. PTrie is a clever combination of the idea of prefix tree -- Trie, structure of logarithmic time complexity for insert and remove operations, doubly linked list and queues.
Motif Yggdrasil: sampling sequence motifs from a tree mixture model.
Andersson, Samuel A; Lagergren, Jens
2007-06-01
In phylogenetic foot-printing, putative regulatory elements are found in upstream regions of orthologous genes by searching for common motifs. Motifs in different upstream sequences are subject to mutations along the edges of the corresponding phylogenetic tree, consequently taking advantage of the tree in the motif search is an appealing idea. We describe the Motif Yggdrasil sampler; the first Gibbs sampler based on a general tree that uses unaligned sequences. Previous tree-based Gibbs samplers have assumed a star-shaped tree or partially aligned upstream regions. We give a probabilistic model (MY model) describing upstream sequences with regulatory elements and build a Gibbs sampler with respect to this model. The model allows toggling, i.e., the restriction of a position to a subset of nucleotides, but does not require aligned sequences nor edge lengths, which may be difficult to come by. We apply the collapsing technique to eliminate the need to sample nuisance parameters, and give a derivation of the predictive update formula. We show that the MY model improves the modeling of difficult motif instances and that the use of the tree achieves a substantial increase in nucleotide level correlation coefficient both for synthetic data and 37 bacterial lexA genes. We investigate the sensitivity to errors in the tree and show that using random trees MY sampler still has a performance similar to the original version.
Favre, Charles
2004-01-01
This volume is devoted to a beautiful object, called the valuative tree and designed as a powerful tool for the study of singularities in two complex dimensions. Its intricate yet manageable structure can be analyzed by both algebraic and geometric means. Many types of singularities, including those of curves, ideals, and plurisubharmonic functions, can be encoded in terms of positive measures on the valuative tree. The construction of these measures uses a natural tree Laplace operator of independent interest.
Cardona, Gabriel; Llabrés, Mercè; Rosselló, Francesc; Valiente, Gabriel
2011-01-01
Galled trees, directed acyclic graphs that model evolutionary histories with isolated hybridization events, have become very popular due to both their biological significance and the existence of polynomial-time algorithms for their reconstruction. In this paper, we establish to which extent several distance measures for the comparison of evolutionary networks are metrics for galled trees, and hence, when they can be safely used to evaluate galled tree reconstruction methods.
A theory of game trees, based on solution trees
W.H.L.M. Pijls (Wim); A. de Bruin (Arie); A. Plaat (Aske)
1996-01-01
textabstractIn this paper a complete theory of game tree algorithms is presented, entirely based upon the notion of a solution tree. Two types of solution trees are distinguished: max and min solution trees respectively. We show that most game tree algorithms construct a superposition of a max and a
A theory of game trees, based on solution trees
W.H.L.M. Pijls (Wim); A. de Bruin (Arie); A. Plaat (Aske)
1996-01-01
textabstractIn this paper a complete theory of game tree algorithms is presented, entirely based upon the notion of a solution tree. Two types of solution trees are distinguished: max and min solution trees respectively. We show that most game tree algorithms construct a superposition of a max and a
DEFF Research Database (Denmark)
Brodal, Gerth Stølting; Sioutas, Spyros; Pantazos, Kostas;
2015-01-01
We present a new overlay, called the Deterministic Decentralized tree (D2-tree). The D2-tree compares favorably to other overlays for the following reasons: (a) it provides matching and better complexities, which are deterministic for the supported operations; (b) the management of nodes (peers......-balancing scheme of elements into nodes is deterministic and general enough to be applied to other hierarchical tree-based overlays. This load-balancing mechanism is based on an innovative lazy weight-balancing mechanism, which is interesting in its own right....
Sexton, Alan P
2010-01-01
The M-tree is a paged, dynamically balanced metric access method that responds gracefully to the insertion of new objects. To date, no algorithm has been published for the corresponding Delete operation. We believe this to be non-trivial because of the design of the M-tree's Insert algorithm. We propose a modification to Insert that overcomes this problem and give the corresponding Delete algorithm. The performance of the tree is comparable to the M-tree and offers additional benefits in terms of supported operations, which we briefly discuss.
Demonstration of multi-robot search and secure
2010-01-01
We consider the search and secure problem, where intruders are to be detected in a bounded area without allowing them to escape. The problem is tackled by representing the area to be searched as a traversability graph, which is reduced to a tree graph by placing stationary robots to remove loops. The search of the remaining tree is performed using two strategies that represent different trade-offs between the needed search time and the number of robots. Proof of correctness is provided for th...
Hamadi, Youssef; Saubion, Frédéric
2012-01-01
Autonomous combinatorial search (AS) represents a new field in combinatorial problem solving. Its major standpoint and originality is that it considers that problem solvers must be capable of self-improvement operations. This is the first book dedicated to AS.
J.R. Simpson; E.G. McPherson
2011-01-01
Urban trees can produce a number of benefits, among them improved air quality. Biogenic volatile organic compounds (BVOCs) emitted by some species are ozone precursors. Modifying future tree planting to favor lower-emitting species can reduce these emissions and aid air management districts in meeting federally mandated emissions reductions for these compounds. Changes...
Matching Subsequences in Trees
DEFF Research Database (Denmark)
Bille, Philip; Gørtz, Inge Li
2009-01-01
Given two rooted, labeled trees P and T the tree path subsequence problem is to determine which paths in P are subsequences of which paths in T. Here a path begins at the root and ends at a leaf. In this paper we propose this problem as a useful query primitive for XML data, and provide new...
Structural Equation Model Trees
Brandmaier, Andreas M.; von Oertzen, Timo; McArdle, John J.; Lindenberger, Ulman
2013-01-01
In the behavioral and social sciences, structural equation models (SEMs) have become widely accepted as a modeling tool for the relation between latent and observed variables. SEMs can be seen as a unification of several multivariate analysis techniques. SEM Trees combine the strengths of SEMs and the decision tree paradigm by building tree…
Tree biology and dendrochemistry
Kevin T. Smith; Walter C. Shortle
1996-01-01
Dendrochemistry, the interpretation of elemental analysis of dated tree rings, can provide a temporal record of environmental change. Using the dendrochemical record requires an understanding of tree biology. In this review, we pose four questions concerning assumptions that underlie recent dendrochemical research: 1) Does the chemical composition of the wood directly...
The major tree nuts include almonds, Brazil nuts, cashew nuts, hazelnuts, macadamia nuts, pecans, pine nuts, pistachio nuts, and walnuts. Tree nut oils are appreciated in food applications because of their flavors and are generally more expensive than other gourmet oils. Research during the last de...
Inhibition of acetylcholinesterase by Tea Tree oil.
Mills, Clive; Cleary, Brian J; Gilmer, John F; Walsh, John J
2004-03-01
Pediculosis is a widespread condition reported in schoolchildren. Treatment most commonly involves the physical removal of nits using fine-toothcombs and the chemical treatment of adult lice and eggs with topical preparations. The active constituents of these preparations frequently exert their effects through inhibition of acetylcholinesterase (AChE, EC 3.1.1.7). Increasing resistance to many preparations has led to the search for more effective treatments. Tea Tree oil, otherwise known as Melaleuca oil, has been added to several preparations as an alternative treatment of head lice infestations. In this study two major constituents of Tea Tree oil, 1,8-cineole and terpinen-4-ol, were shown to inhibit acetylcholinesterase at IC50 values (inhibitor concentrations required to give 50% inhibition) of 0.04 and 10.30 mM, respectively. Four samples of Tea Tree oil tested (Tisserand, Body Treats, Main Camp and Irish Health Culture Association Pure Undiluted) showed anticholinesterase activity at IC50 values of 0.05, 0.10, 0.08 and 0.11 microL mL(-1), respectively. The results supported the hypothesis that the insecticidal activity of Tea Tree oil was attributable, in part, to the anticholinesterase activity of Tea Tree oil.
Coded Splitting Tree Protocols
DEFF Research Database (Denmark)
Sørensen, Jesper Hemming; Stefanovic, Cedomir; Popovski, Petar
2013-01-01
This paper presents a novel approach to multiple access control called coded splitting tree protocol. The approach builds on the known tree splitting protocols, code structure and successive interference cancellation (SIC). Several instances of the tree splitting protocol are initiated, each...... instance is terminated prematurely and subsequently iterated. The combined set of leaves from all the tree instances can then be viewed as a graph code, which is decodable using belief propagation. The main design problem is determining the order of splitting, which enables successful decoding as early...... as possible. Evaluations show that the proposed protocol provides considerable gains over the standard tree splitting protocol applying SIC. The improvement comes at the expense of an increased feedback and receiver complexity....
Quantum optical properties of a single Inx Ga1-x As-GaAs quantum dot two-level system
Stufler, S.; Ester, P.; Zrenner, A.; Bichler, M.
2005-09-01
We report on a two-level system, defined by the ground-state exciton of a single InGaAs/GaAs quantum dot. Saturation spectroscopy combined with ultrahigh spectral resolution gives us a complete description of the system in the steady-state limit. Rabi oscillations and quantum interference experiments, on the other hand, provide a detailed insight into the coherent high excitation regime. All fundamental properties of the two-level system show an excellent quantitative agreement in both domains, even though obtained under entirely different experimental conditions. We thus are able to demonstrate control over an almost ideal two-level system, suitable for possible applications in quantum information processing.
Xu, Hui; Zhang, Yonggang; Zhao, Yongfei; Zhang, Xuesong; Xiao, Songhua; Wang, Yan
2015-02-01
Single pedicle subtraction osteotomy (PSO) has been used to correct ankylosing spondylitis (AS) kyphosis successfully, but this approach seems insufficient to correct severe kyphosis. Two-level PSO has been attempted to correct advanced kyphosis in recent years. However, studies have not yet compared outcomes between single and double PSOs, and the indications to perform two-level PSO are unclear. This study aimed to compare the radiologic and clinical outcomes between single- and two-level PSOs in correcting AS kyphosis. This work is a retrospective cohort study. Sixty patients were included. Thirty-seven underwent single-level PSO, and 23 underwent one stage two-level PSO. The radiologic analysis included thoracic kyphosis, thoracolumbar junction, lumbar lordosis, pelvic index, chin-brow vertical angle (CBVA), sagittal vertical axis (SVA), and pelvic tilt (PT). Clinical assessment was performed with a Scoliosis Research Society-22 (SRS-22) outcomes instrument. The operative time, blood loss, and complications were also documented. All of the aforementioned measurements were recorded before surgery, after surgery, and at the last follow-up. The outcomes were compared between the two groups. The operating time was 232±52 minutes for single- and 282±43 minutes for two-level PSOs. The blood loss was 1,240±542 mL (Level 1) and 2,202±737 mL (Level 2). The total spine correction was 43.2°±15.1° (Level 1) and 60.6°±19.1° (Level 2) (p.05). All patients could walk with horizontal vision and lie on their backs postoperatively. The SRS-22 improved from 1.7±0.4 to 4.2±0.8 in the two-level group and 1.8±0.8 to 4.3±0.7 in the single-level group. The fusion of the osteotomy was achieved in each patient. The complications were similar in both groups. Pedicle subtraction osteotomy is an effective method to correct kyphosis with AS. Most patients can be successfully treated by single PSO. In severe patients, two-level PSO may be preferable because its correction
Energy Technology Data Exchange (ETDEWEB)
Wang, Z.M. [Institute of Theoretical Physics and Department of Physics, Shanxi University, Taiyuan 030006 (China); Xue, H.B. [College of Physics and Optoelectronics, Taiyuan University of Technology, Taiyuan 030024 (China); Xue, N.T. [Institute of Theoretical Physics and Department of Physics, Shanxi University, Taiyuan 030006 (China); Liang, J.-Q., E-mail: jqliang@sxu.edu.cn [Institute of Theoretical Physics and Department of Physics, Shanxi University, Taiyuan 030006 (China)
2015-02-15
We study the full counting statistics of transport electrons through a semiconductor two-level quantum dot with Rashba spin–orbit (SO) coupling, which acts as a nonabelian gauge field and thus induces the electron transition between two levels along with the spin flip. By means of the quantum master equation approach, shot noise and skewness are obtained at finite temperature with two-body Coulomb interaction. We particularly demonstrate the crucial effect of SO coupling on the super-Poissonian fluctuation of transport electrons, in terms of which the SO coupling can be probed by the zero-frequency cumulants. While the charge currents are not sensitive to the SO coupling.
Institute of Scientific and Technical Information of China (English)
Yin-nianHe
2004-01-01
In this article we consider a two-level finite element Galerkin method using mixed finite elements for the two-dimensional nonstationary incompressible Navier-Stokes equations. The method yields a H1-optimal velocity approximation and a L2-optimal pressure approximation. The two-level finite element Galerkin method involves solving one small,nonlinear Navier-Stokes problem on the coarse mesh with mesh size H, one linear Stokes problem on the fine mesh with mesh size h <
Non-Hermitian wave packet approximation for coupled two-level systems in weak and intense fields
Puthumpally-joseph, Raiju; Charron, Eric
2016-01-01
We introduce an accurate non-Hermitian Schr\\"odinger-type approximation of Bloch optical equations for two-level systems. This approximation provides a complete description of the excitation, relaxation and decoherence dynamics in both weak and strong laser fields. In this approach, it is sufficient to propagate the wave function of the quantum system instead of the density matrix, providing that relaxation and dephasing are taken into account via automatically-adjusted time-dependent gain and decay rates. The developed formalism is applied to the problem of scattering and absorption of electromagnetic radiation by a thin layer comprised of interacting two-level emitters.
Beacham, James
The Standard Model of particle physics encompasses three of the four known fundamental forces of nature, and has remarkably withstood all of the experimental tests of its predictions, a fact solidified by the discovery, in 2012, of the Higgs boson. However, it cannot be the complete picture. Many measurements have been made that hint at physics beyond the Standard Model, and the main task of the high- energy experimental physics community is to conduct searches for new physics in as many di↵erent places and regimes as possible. I present three searches for new phenomena in three di↵erent high-energy collider experiments, namely, a search for events with at least three photons in the final state, which is sensitive to an exotic decay of a Higgs boson into four photons via intermediate pseudoscalar particles, a, with ATLAS, at the Large Hadron Collider; a search for a dark photon, also known as an A0 , with APEX, at Thomas Je↵erson National Accelerator Facility; and a search for a Higgs decaying into four...
Siddeq, M. M.; Rodrigues, M. A.
2015-09-01
Image compression techniques are widely used on 2D image 2D video 3D images and 3D video. There are many types of compression techniques and among the most popular are JPEG and JPEG2000. In this research, we introduce a new compression method based on applying a two level discrete cosine transform (DCT) and a two level discrete wavelet transform (DWT) in connection with novel compression steps for high-resolution images. The proposed image compression algorithm consists of four steps. (1) Transform an image by a two level DWT followed by a DCT to produce two matrices: DC- and AC-Matrix, or low and high frequency matrix, respectively, (2) apply a second level DCT on the DC-Matrix to generate two arrays, namely nonzero-array and zero-array, (3) apply the Minimize-Matrix-Size algorithm to the AC-Matrix and to the other high-frequencies generated by the second level DWT, (4) apply arithmetic coding to the output of previous steps. A novel decompression algorithm, Fast-Match-Search algorithm (FMS), is used to reconstruct all high-frequency matrices. The FMS-algorithm computes all compressed data probabilities by using a table of data, and then using a binary search algorithm for finding decompressed data inside the table. Thereafter, all decoded DC-values with the decoded AC-coefficients are combined in one matrix followed by inverse two levels DCT with two levels DWT. The technique is tested by compression and reconstruction of 3D surface patches. Additionally, this technique is compared with JPEG and JPEG2000 algorithm through 2D and 3D root-mean-square-error following reconstruction. The results demonstrate that the proposed compression method has better visual properties than JPEG and JPEG2000 and is able to more accurately reconstruct surface patches in 3D.
Rooting the eukaryote tree by using a derived gene fusion.
Stechmann, Alexandra; Cavalier-Smith, Thomas
2002-07-05
Single-gene trees have failed to locate the root of the eukaryote tree because of systematic biases in sequence evolution. Structural genetic data should yield more reliable insights into deep phylogenetic relationships. We searched major protist groups for the presence or absence of a gene fusion in order to locate the root of the eukaryote tree. In striking contrast to previous molecular studies, we show that all eukaryote groups ancestrally with two cilia (bikonts) are evolutionarily derived. The root lies between bikonts and opisthokonts (animals, Fungi, Choanozoa). Amoebozoa either diverged even earlier or are sister of bikonts or (less likely) opisthokonts.
Compact Ancestry Labeling Schemes for Trees of Small Depth
2009-01-01
An {\\em ancestry labeling scheme} labels the nodes of any tree in such a way that ancestry queries between any two nodes in a tree can be answered just by looking at their corresponding labels. The common measure to evaluate the quality of an ancestry labeling scheme is by its {\\em label size}, that is the maximal number of bits stored in a label, taken over all $n$-node trees. The design of ancestry labeling schemes finds applications in XML search engines. In the context of these applicatio...
Rate-Monotonic Optimal Design Based on Tree-Like Linear Programming Search%基于树状线性规划搜索的单调速率优化设计
Institute of Scientific and Technical Information of China (English)
陈力; 王永吉; 吴敬征; 吕荫润
2015-01-01
改善单调速率(rate monotonic,称RM)可调度性判定算法的效率,是过去40年计算机实时系统设计的重要问题.最近,研究人员把可调度性判定问题扩展到了更一般的优化设计问题,即,如何调节在区间可选择情况下的任务运行时间,使得:(1)系统RM可调度;(2)系统的某个性能(如CPU利用率)达到最优.在已有的求解实时系统RM优化设计问题的方法中,都是先把原问题建模成广义约束优化问题,然后再对广义约束优化问题进行求解.但现有方法的求解速度较慢,任务数较多时不再适用.提出一种求解优化问题的方法一一基于树状的线性规划搜索(linear programming search,简称LPS)方法.该方法先将实时系统RM优化设计问题建模成广义约束优化问题,再将其分拆成若干线性规划子问题,然后构造线性规划搜索树,利用剪枝搜索算法求解部分线性规划子问题,最后得到优化解.实验结果表明:LPS方法相比于已有的方法能够节省20％～70％的求解时间,任务数越多,节省时间越多.该研究成果可以与计算机可满足性模定理(satisfiability modulo theories,简称SMT)领域的多个研究热点问题联系起来,并可望改善SMT问题的求解效率.
The Prevalence of Tree Nut Allergy: A Systematic Review.
McWilliam, Vicki; Koplin, Jennifer; Lodge, Caroline; Tang, Mimi; Dharmage, Shyamali; Allen, Katrina
2015-09-01
Tree nuts are one of the most common foods causing acute allergic reactions and nearly all tree nuts have been associated with fatal allergic reactions. Despite their clinical importance, tree nut allergy epidemiology remains understudied and the prevalence of tree nut allergy in different regions of the world has not yet been well characterised. We aimed to systematically review the population prevalence of tree nut allergy in children and adults. We searched three electronic databases (OVID MEDLINE, EMBASE and PubMed) from January 1996 to December 2014. Eligible studies were categorised by age, region and method of assessment of tree nut allergy. Of the 36 studies identified most were in children (n = 24) and from Europe (n = 18), UK (n = 8) or USA (n = 5). Challenge-confirmed IgE-mediated tree nut allergy prevalence was less than 2 % (although only seven studies used this gold standard) while probable tree nut allergy prevalence ranged from 0.05 to 4.9 %. Prevalence estimates that included oral allergy syndrome (OAS) reactions to tree nut were significantly higher (8-11.4 %) and were predominantly from Europe. Prevalence of individual tree nut allergies varied significantly by region with hazelnut the most common tree nut allergy in Europe, walnut and cashew in the USA and Brazil nut, almond and walnut most commonly reported in the UK. Monitoring time trends of tree nut allergy prevalence (both overall and by individual nuts) as well as the prevalence of OAS should be considered given the context of the overall recent rise in IgE-mediated food allergy prevalence in the developed world.
Phylogenetic trees in bioinformatics
Energy Technology Data Exchange (ETDEWEB)
Burr, Tom L [Los Alamos National Laboratory
2008-01-01
Genetic data is often used to infer evolutionary relationships among a collection of viruses, bacteria, animal or plant species, or other operational taxonomic units (OTU). A phylogenetic tree depicts such relationships and provides a visual representation of the estimated branching order of the OTUs. Tree estimation is unique for several reasons, including: the types of data used to represent each OTU; the use ofprobabilistic nucleotide substitution models; the inference goals involving both tree topology and branch length, and the huge number of possible trees for a given sample of a very modest number of OTUs, which implies that fmding the best tree(s) to describe the genetic data for each OTU is computationally demanding. Bioinformatics is too large a field to review here. We focus on that aspect of bioinformatics that includes study of similarities in genetic data from multiple OTUs. Although research questions are diverse, a common underlying challenge is to estimate the evolutionary history of the OTUs. Therefore, this paper reviews the role of phylogenetic tree estimation in bioinformatics, available methods and software, and identifies areas for additional research and development.
DEFF Research Database (Denmark)
Malossi, Nicola; Bason, Mark George; Viteau, Matthieu
2013-01-01
We present experimental results on the preparation of a desired quantum state in a two-level system with the maximum possible fidelity using driving protocols ranging from generalizations of the linear Landau-Zener protocol to transitionless driving protocols that ensure perfect following of the ...
Talero, Paco; Barbosa, Luis
2012-01-01
We applied the FCI to 646 engineering students from Bogota when they began your first year physics, we found that the relative frequency of the number of correct answers has a random pattern of two levels, also we found that they don't have clear mental models about physical world.
Comparison of PI and PR current controllers applied on two-level VSC-HVDC transmission system
DEFF Research Database (Denmark)
Manoloiu, A.; Pereria, H.A.; Teodorescu, Remus;
2015-01-01
This paper analyzes differences between αβ and dq reference frames regarding the control of two-level VSC-HVDC current loop and dc-link voltage outer loop. In the first part, voltage feedforward effect is considered with PI and PR controllers. In the second part, the feedforward effect is removed...
The dynamical Cooperative Lamb Shift in a system of two-level atoms in a slab-geometry
Energy Technology Data Exchange (ETDEWEB)
Friedberg, Richard [Department of Physics, Columbia University, New York, NY 10027 (United States); Manassah, Jamal T., E-mail: jmanassah@gmail.co [HMS Consultants, Inc., PO Box 592, New York, NY 10028 (United States)
2009-09-14
Using the eigenmode analysis, we compute the Cooperative Lamb Shift (CLS) as a function of time from the vector photon model for a system of two-level atoms in a slab-geometry for forward and backward emission in two initial states of weak excitation and complete inversion.
Institute of Scientific and Technical Information of China (English)
邹旭波; 许晶波; 高孝纯; 符建
2001-01-01
We adopt a dynamical algebraic approach to study the system of a two-level atom moving in a quantized travelling light field and a gravitational field with a multiphoton interaction. The exact solution of the system is obtained and used to discuss the influence of the gravitational field on the collapses and revivals of atomic population, sub-Poissonian statistics.
DEFF Research Database (Denmark)
Kouchaki, Alireza; Nymand, Morten
2016-01-01
This paper presents LCL filter design method for three-phase two-level power factor correction (PFC) using line impedance stabilization network (LISN). A straightforward LCL filter design along with variation in grid impedance is not simply achievable and inevitably lead to an iterative solution...
Energy Technology Data Exchange (ETDEWEB)
Xia Keyu [State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China); Graduate University of Chinese Academy of Sciences (China); Niu Yueping [State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China); Graduate University of Chinese Academy of Sciences (China); Li Chunfang [Department of Physics, Shanghai University, Shanghai 200436 (China); Gong Shangqing [CCAST (World Laboratory), PO Box 8730, Beijing 100080 (China) and State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China)]. E-mail: sqgong@siom.ac.cn
2007-01-22
Using a {omega}-3{omega} combination scenario, we investigate the absolute phase control of the spectra effects for ultrashort laser pulses propagating in a two-level medium. It is found that the higher spectral components can be controlled by the absolute phases. In particular, different absolute phase combinations can lead to the buildup or split of the even harmonics.
Institute of Scientific and Technical Information of China (English)
LI Zuo-wei; YANG Yi-xian; YUAN Dong-feng; HU Zheng-ming
2004-01-01
In this paper, we propose a novel Unequal Error Protection (UEP) scheme with two levels for image transmission using Multilevel Codes (MLC). By providing the best protection for the most important data, the final recovered image quality is remarkably improved both in visual effect and in Peak Signal to Noise power Ratio (PSNR) performance.
Directory of Open Access Journals (Sweden)
M. Corgini
2010-01-01
Full Text Available For a Bose atom system whose energy operator is diagonal in the so-called number operators and its ground state has an internal two-level structure with negative energies, exact expressions for the limit free canonical energy and pressure are obtained. The existence of non-conventional Bose-Einstein condensation has been also proved.
DEFF Research Database (Denmark)
Malossi, Nicola; Bason, Mark George; Viteau, Matthieu
2013-01-01
We present experimental results on the preparation of a desired quantum state in a two-level system with the maximum possible fidelity using driving protocols ranging from generalizations of the linear Landau-Zener protocol to transitionless driving protocols that ensure perfect following...
Institute of Scientific and Technical Information of China (English)
Fan Aihua
2004-01-01
The vertices of an infinite locally finite tree T are labelled by a collection of i.i.d. real random variables {Xσ}σ∈T which defines a tree indexed walk Sσ = ∑θ＜r≤σXr. We introduce and study the oscillations of the walk:Exact Hausdorff dimension of the set of such ξ 's is calculated. An application is given to study the local variation of Brownian motion. A general limsup deviation problem on trees is also studied.
Fatmaa El Zahraa Mohamed Abdou
2004-01-01
A general study about the internet search engines, the study deals main 7 points; the differance between search engines and search directories, components of search engines, the percentage of sites covered by search engines, cataloging of sites, the needed time for sites appearance in search engines, search capabilities, and types of search engines.
Directory of Open Access Journals (Sweden)
Fatmaa El Zahraa Mohamed Abdou
2004-09-01
Full Text Available A general study about the internet search engines, the study deals main 7 points; the differance between search engines and search directories, components of search engines, the percentage of sites covered by search engines, cataloging of sites, the needed time for sites appearance in search engines, search capabilities, and types of search engines.
Tree-growth analyses to estimate tree species' drought tolerance
Eilmann, B.; Rigling, A.
2012-01-01
Climate change is challenging forestry management and practices. Among other things, tree species with the ability to cope with more extreme climate conditions have to be identified. However, while environmental factors may severely limit tree growth or even cause tree death, assessing a tree specie
Generalising tree traversals and tree transformations to DAGs
DEFF Research Database (Denmark)
Bahr, Patrick; Axelsson, Emil
2017-01-01
We present a recursion scheme based on attribute grammars that can be transparently applied to trees and acyclic graphs. Our recursion scheme allows the programmer to implement a tree traversal or a tree transformation and then apply it to compact graph representations of trees instead...
Larson, David; Jacob, Sharon E
2012-01-01
Tea tree oil is an increasingly popular ingredient in a variety of household and cosmetic products, including shampoos, massage oils, skin and nail creams, and laundry detergents. Known for its potential antiseptic properties, it has been shown to be active against a variety of bacteria, fungi, viruses, and mites. The oil is extracted from the leaves of the tea tree via steam distillation. This essential oil possesses a sharp camphoraceous odor followed by a menthol-like cooling sensation. Most commonly an ingredient in topical products, it is used at a concentration of 5% to 10%. Even at this concentration, it has been reported to induce contact sensitization and allergic contact dermatitis reactions. In 1999, tea tree oil was added to the North American Contact Dermatitis Group screening panel. The latest prevalence rates suggest that 1.4% of patients referred for patch testing had a positive reaction to tea tree oil.
Aval, Jean-Christophe; Nadeau, Philippe
2011-01-01
In this work we introduce and study tree-like tableaux, which are certain fillings of Ferrers diagrams in simple bijection with permutation tableaux and alternative tableaux. We exhibit an elementary insertion procedure on our tableaux which gives a clear proof that tableaux of size n are counted by n!, and which moreover respects most of the well-known statistics studied originally on alternative and permutation tableaux. Our insertion procedure allows to define in particular two simple new bijections between tree-like tableaux and permutations: the first one is conceived specifically to respect the generalized pattern 2-31, while the second one respects the underlying tree of a tree-like tableau.
Minnesota Department of Natural Resources — The National Land Cover Database 2001 tree canopy layer for Minnesota (mapping zones 39-42, 50-51) was produced through a cooperative project conducted by the...
Energy Technology Data Exchange (ETDEWEB)
Kelly, K.; White, K.
1981-03-01
An important harvesting alternative in North America is the Full Tree Method, in which trees are felled and transported to roadside, intermediate or primary landings with limbs and branches intact. The acceptance of Full Tree Systems is due to many factors including: labour productivity and increased demands on the forest for ''new products''. These conditions are shaping the future look for forest Harvesting Systems, but must not be the sole determinants. All harvesting implications, such as those affecting Productivity and silviculture, should be thoroughly understood. This paper does not try to discuss every implication, nor any particular one in depth; its purpose is to highlight those areas requiring consideration and to review several current North American Full Tree Systems. (Refs. 5).
1981-01-01
to be Evaluated Manufacturer Location Seismic Susceptibility Flood Susceptibility Temperature Humidity Radiation Wear-out Susceptibility Test...For the category " Seismic Susceptibility," we might define several sensitivity levels ranging from no sensitivity to extreme sensitivity, and for more... Hanford Company, Richland, Wash- ington, ARH-ST-l 12, July 1975. 40. W.E. Vesely, "Analysis of Fault Trees by Kinetic Tree Theory," Idaho Nuclear
DEFF Research Database (Denmark)
Jaeger, Manfred
2006-01-01
We introduce type extension trees as a formal representation language for complex combinatorial features of relational data. Based on a very simple syntax this language provides a unified framework for expressing features as diverse as embedded subgraphs on the one hand, and marginal counts...... of attribute values on the other. We show by various examples how many existing relational data mining techniques can be expressed as the problem of constructing a type extension tree and a discriminant function....
DEFF Research Database (Denmark)
Jaeger, Manfred
2006-01-01
We introduce type extension trees as a formal representation language for complex combinatorial features of relational data. Based on a very simple syntax this language provides a unified framework for expressing features as diverse as embedded subgraphs on the one hand, and marginal counts...... of attribute values on the other. We show by various examples how many existing relational data mining techniques can be expressed as the problem of constructing a type extension tree and a discriminant function....
DEFF Research Database (Denmark)
Somchaipeng, Kerawit; Sporring, Jon; Johansen, Peter
2007-01-01
We propose MultiScale Singularity Trees (MSSTs) as a structure to represent images, and we propose an algorithm for image comparison based on comparing MSSTs. The algorithm is tested on 3 public image databases and compared to 2 state-of-theart methods. We conclude that the computational complexity...... of our algorithm only allows for the comparison of small trees, and that the results of our method are comparable with state-of-the-art using much fewer parameters for image representation....
DEFF Research Database (Denmark)
Schmidt, Lars Holger
Forest tree improvement encompasses a number of scientific and technical areas like floral-, reproductive- and micro-biology, genetics breeding methods and strategies, propagation, gene conservation, data analysis and statistics, each area with a comprehensive terminology. The terms selected...... for definition here are those most frequently used in tree improvement literature. Clonal propagation is included in the view of the great expansion of that field as a means of mass multiplication of improved material....
Directory of Open Access Journals (Sweden)
Xuemei Sun
2015-01-01
Full Text Available Degree constrained minimum spanning tree (DCMST refers to constructing a spanning tree of minimum weight in a complete graph with weights on edges while the degree of each node in the spanning tree is no more than d (d ≥ 2. The paper proposes an improved multicolony ant algorithm for degree constrained minimum spanning tree searching which enables independent search for optimal solutions among various colonies and achieving information exchanges between different colonies by information entropy. Local optimal algorithm is introduced to improve constructed spanning tree. Meanwhile, algorithm strategies in dynamic ant, random perturbations ant colony, and max-min ant system are adapted in this paper to optimize the proposed algorithm. Finally, multiple groups of experimental data show the superiority of the improved algorithm in solving the problems of degree constrained minimum spanning tree.
MusiCat System Makes Library Searches More Fruitful.
Hansen, Per Hofman
2002-01-01
Describes MusiCat, an experimental user interface designed in Denmark that reflects the different ways that patrons think when searching for musical material on the Web. Discusses technology versus content; search trees that use a hierarchy of subject terms; and usability testing. (LRW)
Fast string searching in secondary storage: Theoretical developments and experimental results
Energy Technology Data Exchange (ETDEWEB)
Ferragina, P. [Universita di Pisa (Italy); Grossi, R. [Universita di Firenze (Italy)
1996-12-31
In a previous work, we proposed a text indexing data structure for secondary storage, which we called SB-tree, that combines the best of B-trees and suffix arrays, overcoming the limitations of inverted files, suffix arrays, suffix trees, and prefix B-trees. In this paper we study the performance of SB-trees in a practical setting, performing a set of searching and updating experiments. Improved performance was obtained by a new space efficient and alphabet-independent organization of the internal nodes of the SB-tree, and a new batch insertion procedure that avoids thrashing.
Manwani, Naresh
2010-01-01
In this paper we present a new algorithm for learning oblique decision trees. Most of the current decision tree algorithms rely on impurity measures to assess the goodness of hyperplanes at each node while learning a decision tree in a top-down fashion. These impurity measures do not properly capture the geometric structures in the data. Motivated by this, our algorithm uses a strategy to assess the hyperplanes in such a way that the geometric structure in the data is taken into account. At each node of the decision tree, we find the clustering hyperplanes for both the classes and use their angle bisectors as the split rule at that node. We show through empirical studies that this idea leads to small decision trees and better performance. We also present some analysis to show that the angle bisectors of clustering hyperplanes that we use as the split rules at each node, are solutions of an interesting optimization problem and hence argue that this is a principled method of learning a decision tree.
2014-01-01
With a view to creating new landscapes and making its population of trees safer and healthier, this winter CERN will complete the tree-felling campaign started in 2010. Tree felling will take place between 15 and 22 November on the Swiss part of the Meyrin site. This work is being carried out above all for safety reasons. The trees to be cut down are at risk of falling as they are too old and too tall to withstand the wind. In addition, the roots of poplar trees are very powerful and spread widely, potentially damaging underground networks, pavements and roadways. Compensatory tree planting campaigns will take place in the future, subject to the availability of funding, with the aim of creating coherent landscapes while also respecting the functional constraints of the site. These matters are being considered in close collaboration with the Geneva nature and countryside directorate (Direction générale de la nature et du paysage, DGNP). GS-SE Group
Attack Trees with Sequential Conjunction
Jhawar, Ravi; Kordy, Barbara; Mauw, Sjouke; Radomirović, Sasa; Trujillo-Rasua, Rolando
2015-01-01
We provide the first formal foundation of SAND attack trees which are a popular extension of the well-known attack trees. The SAND at- tack tree formalism increases the expressivity of attack trees by intro- ducing the sequential conjunctive operator SAND. This operator enables the modeling of
Quaggio José Antônio; Mattos Junior Dirceu; Cantarella Heitor; Stuchi Eduardo Sanches; Sempionato Otávio Ricardo
2004-01-01
The majority of citrus trees in Brazil are grafted on 'Rangpur lime' (Citrus limonia Osb.) rootstock. Despite its good horticultural performance, search for disease tolerant rootstock varieties to improve yield and longevity of citrus groves has increased. The objective of this work was to evaluate yield efficiency of sweet oranges on different rootstocks fertilized with N, P, and potassium. Tree growth was affected by rootstock varieties; trees on 'Swingle' citrumelo [Poncirus trifoliata (L....
Nakatani, Masatoshi; Nobuhiro, Atsushi; Yokoshi, Nobuhiko; Ishihara, Hajime
2013-06-07
We theoretically investigate photoexcitation processes of a two-level molecular system coherently coupled with an antenna system having a significant dissipation. The auxiliary antenna enables the whole system to exhibit anomalous optical effects by controlling the coupling with the molecule. For example, in the weak excitation regime, the quantum interference yields a distinctive energy transparency through the antenna, which drastically reduces the energy dissipation. On the other hand, in the strong excitation regime, a population inversion of the two-level molecule appears due to the nonlinear effect. Both phenomena can be explained by regarding the antenna and molecule as one quantum-mechanically coupled system. Such an approach drives further research to exploit the full potential of the coupled systems.
RESIDUAL A POSTERIORI ERROR ESTIMATE OF A NEW TWO-LEVEL METHOD FOR STEADY NAVIER-STOKES EQUATIONS
Institute of Scientific and Technical Information of China (English)
Chunfeng REN; Yichen MA
2006-01-01
Residual-based a posteriori error estimate for conforming finite element solutions of incompressible Navier-Stokes equations, which is computed with a new two-level method that is different from Volker John, is derived. A posteriori error estimate contains additional terms in comparison to the estimate for the solution obtained by the standard finite element method. The importance of the additional terms in the error estimates is investigated by studying their asymptotic behavior. For optimal scaled meshes, these bounds are not of higher order than the convergence of discrete solution. The two-level method aims to solve the nonlinear problem on a coarse grid with less computational work,then to solve the linear problem on a fine grid, which is superior to the usual finite element method solving a similar nonlinear problem on the fine grid.
Institute of Scientific and Technical Information of China (English)
XIAO Dong-hai; TAN Chun-lu; WANG Jun-qiang; ZHONG Yuan-chang
2007-01-01
To fit the complicated geographic conditions of the Three Gorges Reservoir area, a two-level multi-objective monitoring system was developed to monitor the atmosphere of the area. Statistical analysis of environmental monitoring data and the macro control principle were employed to configure the upper layer. The lower layer was designed by the application of the thumb rule to a local terrain and specific point sources of pollution therein. The optimized two-level system comprises an upper layer of 16 monitoring stations distributed at places of diverse geographical, ecological, economical and social characteristics, and a lower layer of 16 sub-machines at each monitoring station of the upper layer. This optimal outcome fits the complicated conditions of the Three Gorges Reservoir area, substantially cuts down the installation cost and the operation cost, and provides accurate monitoring data of atmosphere over the entire area with a high resolution.
Economic-mathematical model of two-level minimax program control of economic security of a region
Directory of Open Access Journals (Sweden)
Andrey Fyodorovich Shorikov
2014-09-01
Full Text Available This article discusses a discrete-time dynamical system consisting of a set of a controllable objects (region and forming it municipalities. The dynamics each of these is described by the corresponding vector linear discrete-time recurrent relations, and its control system consist from two levels: basic (control level I that is dominating and subordinate level (control level II. Both levels have different criterions of functioning and united a priori by determined informational and control connections defined in advance. Considered addresses the problem of optimization of management of economic security of the region in the presence of risks. For the investigated problem is proposed in this work an economic-mathematical model of two-level hierarchical minimax program control of economic security of the region in the presence of risk and the general scheme of the solution.
Propagation of subcycle pulses in a two-level medium: Area-theorem breakdown and pulse shape
Novitsky, Denis
2013-01-01
We solve the problem of ultrashort pulse propagation in a two-level medium beyond the rotating-wave (RWA) and slowly-varying-envelope approximations. The method of solution is based on the Maxwell--Bloch equations represented in the form that allows one to switch between RWA and general (non-RWA) cases in the framework of a single numerical algorithm. Using this method, the effect of a subcycle pulse (containing less than a single period of field oscillations) on the two-level medium was analyzed. It is shown that for such short pulses, the clear breakdown of the area theorem occurs for the pulses of large enough area. Moreover, deviations from the area theorem appear to be strongly dependent on the pulse shape that cannot be observed for longer few-cycle pulses.
Squeezing Effect of a Nanomechanical Resonator Coupled to a Two-Level System:an Equilibrium Approach
Institute of Scientific and Technical Information of China (English)
LI Jing; CHEN Zhi-De
2009-01-01
The squeezing effect of a nanomechanical resonator coupled to a two-level system is studied by variational calculations based on both the displaced-squeezed-state (DSS) and the displaced-oscillator-state (DOS).The stable region of the DSS ground state at both T = 0 and T≠0 and the corresponding squeezing factor are alculated.It is found that when the resonator frequency lies in (kBT,△),where △ is the tunnelling splitting of the two-level-system in the presence of dissipation,tunnelling splitting of a DSS ground state decreases with the temperature,while tunnelling splitting of a DOS ground state increases with the temperature in low temperature region.This opposite temperature dependence can help to distinguish between the DSS and DOS ground state in the experiment.
Directory of Open Access Journals (Sweden)
Ahmet Mete Vural
2016-09-01
Full Text Available This paper presents the design details of a two-level space vector pulse width modulation algorithm in PSCAD that is able to generate pulses for three-phase two-level DC/AC converters with two different switching patterns. The presented FORTRAN code is generic and can be easily modified to meet many other kinds of space vector modulation strategies. The code is also editable for hardware programming. The new component is tested and verified by comparing its output as six gating signals with those of a similar component in MATLAB library. Moreover the component is used to generate digital signals for closed-loop control of STATCOM for reactive power compensation in PSCAD. This add-on can be an effective tool to give students better understanding of the space vector modulation algorithm for different control tasks in power electronics area, and can motivate them for learning.
Astier, P.; Autiero, D.; Baldisseri, A.; Baldo-Ceolin, M.; Banner, M.; Bassompierre, G.; Benslama, K.; Besson, N.; Bird, I.; Blumenfeld, B.; Bobisut, F.; J. Bouchez; Boyd, S.; A. Bueno; Bunyatov, S.
2003-01-01
Neutrinos; We present the results of a search for nu_mu → nu_e oscillations in the NOMAD experiment at Cern. The experiment looked for the appearance of nu_e in a predominantly nu_mu wide-band neutrino beam at the CERN SPS. No evidence for oscillations was found. The 90% confidence limits obtained are Delta m^2 ~ 10 eV^2.
Astier, Pierre; Baldisseri, Alberto; Baldo-Ceolin, Massimilla; Banner, M; Bassompierre, Gabriel; Benslama, K; Besson, N; Bird, I; Blumenfeld, B; Bobisut, F; Bouchez, J; Boyd, S; Bueno, A G; Bunyatov, S A; Camilleri, L L; Cardini, A; Cattaneo, Paolo Walter; Cavasinni, V; Cervera-Villanueva, A; Challis, R C; Chukanov, A; Collazuol, G; Conforto, G; Conta, C; Contalbrigo, M; Cousins, R D; Daniels, D; De Santo, A; Degaudenzi, H M; Del Prete, T; Di Lella, L; Dignan, T; Dumarchez, J; Feldman, G J; Ferrari, A; Ferrari, R; Ferrère, D; Flaminio, Vincenzo; Fraternali, M; Gaillard, J M; Gangler, E; Geiser, A; Geppert, D; Gibin, D; Gninenko, S N; Godley, A; Gosset, J; Gouanère, M; Grant, A; Graziani, G; Guglielmi, A M; Gómez-Cadenas, J J; Gössling, C; Hagner, C; Hernando, J; Hong, T M; Hubbard, D B; Hurst, P; Hyett, N; Iacopini, E; Joseph, C L; Juget, F R; Kent, N; Kirsanov, M M; Klimov, O; Kokkonen, J; Kovzelev, A; Krasnoperov, A V; Kustov, D; La Rotonda, L; Lacaprara, S; Lachaud, C; Lakic, B; Lanza, A; Laveder, M; Letessier-Selvon, A A; Linssen, Lucie; Ljubicic, A; Long, J; Lupi, A; Lévy, J M; Marchionni, A; Martelli, F; Mendiburu, J P; Meyer, J P; Mezzetto, Mauro; Mishra, S R; Moorhead, G F; Méchain, X; Naumov, D V; Nefedov, Yu A; Nguyen-Mau, C; Nédélec, P; Orestano, D; Pastore, F; Peak, L S; Pennacchio, E; Pessard, H; Petti, R; Placci, A; Polesello, G; Pollmann, D; Polyarush, A Yu; Popov, B; Poulsen, C; Rebuffi, L; Renò, R; Rico, J; Riemann, P; Roda, C; Rubbia, André; Salvatore, F; Schahmaneche, K; Schmidt, B; Schmidt, T; Sconza, A; Sevior, M E; Shih, D; Sillou, D; Soler, F J P; Sozzi, G; Steele, D; Stiegler, U; Stipcevic, M; Stolarczyk, T; Tareb-Reyes, M; Taylor, G N; Tereshchenko, V V; Toropin, A N; Touchard, A M; Tovey, Stuart N; Tran, M T; Tsesmelis, E; Ulrichs, J; Vacavant, L; Valdata-Nappi, M; Valuev, V Yu; Vannucci, François; Varvell, K E; Veltri, M; Vercesi, V; Vidal-Sitjes, G; Vieira, J M; Vinogradova, T G; Weber, F V; Weisse, T; Wilson, F F; Winton, L J; Yabsley, B D; Zaccone, Henri; Zuber, K; Zuccon, P; do Couto e Silva, E
2003-01-01
We present the results of a search for nu_mu → nu_e oscillations in the NOMAD experiment at Cern. The experiment looked for the appearance of nu_e in a predominantly nu_mu wide-band neutrino beam at the CERN SPS. No evidence for oscillations was found. The 90% confidence limits obtained are Delta m^2 ~ 10 eV^2.
Astier, Pierre; Baldisseri, Alberto; Baldo-Ceolin, Massimilla; Banner, M; Bassompierre, Gabriel; Benslama, K; Besson, N; Bird, I; Blumenfeld, B; Bobisut, F; Bouchez, J; Boyd, S; Bueno, A G; Bunyatov, S; Camilleri, L L; Cardini, A; Cattaneo, Paolo Walter; Cavasinni, V; Cervera-Villanueva, A; Challis, R C; Chukanov, A; Collazuol, G; Conforto, G; Conta, C; Contalbrigo, M; Cousins, R; Daniels, D; Degaudenzi, H M; Del Prete, T; De Santo, A; Dignan, T; Di Lella, L; do Couto e Silva, E; Dumarchez, J; Ellis, M; Feldman, G J; Ferrari, R; Ferrère, D; Flaminio, Vincenzo; Fraternali, M; Gaillard, J M; Gangler, E; Geiser, A; Geppert, D; Gibin, D; Gninenko, S N; Godley, A; Gómez-Cadenas, J J; Gosset, J; Gössling, C; Gouanère, M; Grant, A; Graziani, G; Guglielmi, A M; Hagner, C; Hernando, J A; Hubbard, D B; Hurst, P; Hyett, N; Iacopini, E; Joseph, C L; Juget, F R; Kent, N; Kirsanov, M M; Klimov, O; Kokkonen, J; Kovzelev, A; Krasnoperov, A V; Kustov, D; Lacaprara, S; Lachaud, C; Lakic, B; Lanza, A; La Rotonda, L; Laveder, M; Letessier-Selvon, A A; Lévy, J M; Linssen, Lucie; Ljubicic, A; Long, J; Lupi, A; Marchionni, A; Martelli, F; Méchain, X; Mendiburu, J P; Meyer, J P; Mezzetto, Mauro; Mishra, S R; Moorhead, G F; Naumov, D V; Nédélec, P; Nefedov, Yu A; Nguyen-Mau, C; Orestano, D; Pastore, F; Peak, L S; Pennacchio, E; Pessard, H; Petti, R; Placci, A; Polesello, G; Pollmann, D; Polyarush, A Yu; Popov, B; Poulsen, C; Rebuffi, L; Renò, R; Rico, J; Riemann, P; Roda, C; Rubbia, André; Salvatore, F; Schahmaneche, K; Schmidt, B; Schmidt, T; Sconza, A; Sevior, M E; Sillou, D; Soler, F J P; Sozzi, G; Steele, D; Stiegler, U; Stipcevic, M; Stolarczyk, T; Tareb-Reyes, M; Taylor, G; Tereshchenko, V V; Toropin, A N; Touchard, A M; Tovey, Stuart N; Tran, M T; Tsesmelis, E; Ulrichs, J; Vacavant, L; Valdata-Nappi, M; Valuev, V Y; Vannucci, François; Varvell, K E; Veltri, M; Vercesi, V; Vidal-Sitjes, G; Vieira, J M; Vinogradova, T G; Weber, F V; Weisse, T; Wilson, F F; Winton, L J; Yabsley, B D; Zaccone, Henri; Zuber, K; Zuccon, P
2001-01-01
We present the results of a search for nu(mu)-->nu(e) oscillations in the NOMAD experiment at CERN. The experiment looked for the appearance of nu(e) in a predominantly nu(mu) wide-band neutrino beam at the CERN SPS. No evidence for oscillations was found. The 90% confidence limits obtained are delta m^2 10 eV^2.
Shuval-Sergeeva, E. V.; Zaitsev, A. I.
2008-03-01
When describing the phenomenon of bistability of optical response of an ultra thin layer consisting of two-level atoms it is important to take into account the local field correction. The account of the correction results in the improvement of existence conditions of bistability. One more bistable region is formed starting with certain value of local field parameter. Both effects are induced by the dynamical frequency shift.
On a Connection between Ideal Two-level Autocorrelation and Almost Balancedness of $p$-ary Sequences
Borissov, Yuri L
2011-01-01
In this correspondence, for every periodic $p-$ary sequence satisfying ideal two-level autocorrelation property the existence of an element of the field ${\\bf GF}(p)$ which appears one time less than all the rest that are equally distributed in a period of that sequence, is proved by algebraic method. In addition, it is shown that such a special element might not be only the zero element but as well arbitrary element of that field.
Institute of Scientific and Technical Information of China (English)
赵延霆; 赵建明; 肖连团; 尹王保; 贾锁堂
2004-01-01
The electromagnetically induced absorption and electromagnetically induced transparency spectra of degenerate two-level systems with a strong coupling laser were observed. The frequency detuning and intensity effect of the coupling laser were demonstrated simultaneously. A dispersion-like spectrum can be obtained when the coupling laser is situated at blue-side detuning. The absorption inversion was realized when the coupling laser intensity is small. The coherent resonance has a linewidth much narrower than the natural linewidth of the optical transitions.
Two-Level Dipolar System in a Heat Bath: High-Pump Power Effects in the Nonlinear Optical Responses
Paz, J. L.; León-Torres, J. R.; Lascano, Luis; Alvarado, Ysaias J.; Costa-Vera, Cesar
2017-06-01
Using the four-wave mixing spectroscopy, we analyze the nonlinear optical properties in a strongly driven two-level system, using a perturbative treatment where, the pump field is considered at all orders, second order in the probe, and first order for the signal field, when the stochastic effects of the solvent are considered. Significant variations in the nonlinear optical properties due mainly to changes in the probe intensity, chemical concentrations, and transversal relaxation times are observed.
NAFTA as an agricultural "policy option" for Mexico : a case study within a two-level framework
Røssaak, Camilla
1996-01-01
NAFTA AS AN AGRICULTURAL 'POLICY OPTION' FOR MEXICO: A CASE STUDY WITHIN A TWO- LEVEL FRAMEWORK The main focus of the thesis was the agricultural negotiation process between Mexico and the United States within the NAFTA process. I wanted to investigate to what extent this process led to changes in Mexican agricultural policy. Furthermore I wanted to find out whose interests were taken into consideration when Mexico negotiated agriculture in NAFTA. If so, was this done at the expense o...
Merged Search Algorithms for Radio Frequency Identification Anticollision
Directory of Open Access Journals (Sweden)
Bih-Yaw Shih
2012-01-01
The arbitration algorithm for RFID system is used to arbitrate all the tags to avoid the collision problem with the existence of multiple tags in the interrogation field of a transponder. A splitting algorithm which is called Binary Search Tree (BST is well known for multitags arbitration. In the current study, a splitting-based schema called Merged Search Tree is proposed to capture identification codes correctly for anticollision. Performance of the proposed algorithm is compared with the original BST according to time and power consumed during the arbitration process. The results show that the proposed model can reduce searching time and power consumed to achieve a better performance arbitration.
Every DFS tree of a 3-connected graph contains a contractible edge
DEFF Research Database (Denmark)
Elmasry, Amr Ahmed Abd Elmoneim; Mehlhorn, Kurt; Schmidt, Jens M.
2013-01-01
Tutte proved that every 3-connected graph G on more than 4 vertices contains a contractible edge. We strengthen this result by showing that every depth-first-search tree of G contains a contractible edge. Moreover, we show that every spanning tree of G contains a contractible edge if G is 3-regular...
Concept Tree Based Information Retrieval Model
Directory of Open Access Journals (Sweden)
Chunyan Yuan
2014-05-01
Full Text Available This paper proposes a novel concept-based query expansion technique named Markov concept tree model (MCTM, discovering term relationship through the concept tree deduced by term markov network. We address two important issues for query expansion: the selection and the weighting of expansion search terms. In contrast to earlier methods, queries are expanded by adding those terms that are most similar to the concept of the query, rather than selecting terms that are similar to a signal query terms. Utilizing Markov network which is constructed according to the co-occurrence information of the terms in collection, it generate concept tree for each original query term, remove the redundant and irrelevant nodes in concept tree, then adjust the weight of original query and the weight of expansion term based on a pruning algorithm. We use this model for query expansion and evaluate the effectiveness of the model by examining the accuracy and robustness of the expansion methods, Compared with the baseline model, the experiments on standard dataset reveal that this method can achieve a better query quality
On the neighbourhoods of trees
Humphries, Peter J
2012-01-01
Tree rearrangement operations typically induce a metric on the space of phylogenetic trees. One important property of these metrics is the size of the neighbourhood, that is, the number of trees exactly one operation from a given tree. We present an expression for the size of the TBR (tree bisection and reconnection) neighbourhood, thus answering a question first posed in [Annals of Combinatorics, 5, 2001 1-15].
Entropy squeezing for a two-level atom in two-mode Raman coupled model with intrinsic decoherence
Institute of Scientific and Technical Information of China (English)
Zhang Jian; Shao Bin; Zou Jian
2009-01-01
In this paper,we investigate the entropy squeezing for a two-level atom interacting with two quantized fields through Raman coupling.We obtain the dynamical evolution of the total system under the influence of intrinsic decoherence when the two quantized fields are prepared in a two-mode squeezing vacuum state initially.The effects of the field squeezing factor,the two-level atomic transition frequency,the second field frequency and the intrinsic decoherence on the entropy squeezing are discussed.Without intrinsic decoherence,the increase of field squeezing factor can break the entropy squeezing.The two-level atomic transition frequency changes only the period of oscillation but not the strength of entropy squeezing.The influence of the second field frequency is complicated.With the intrinsic decoherence taken into consideration,the results show that the stronger the intrinsic decoherence is,the more quickly the entropy squeezing will disappear.The increase of the atomic transition frequency can hasten the disappearance of entropy squeezing.
Liu, Ju; Li, Zhi-Yuan
2014-11-17
One of the simplest models involving the atom-field interaction is the coupling of a single two-level atom with single-mode optical field. Under the rotating wave approximation, this problem is reduced to a form that can be solved exactly. But the approximation is only valid when the two levels are resonant or nearly resonant with the applied electromagnetic radiation. Here we present an analytical solution without the rotating wave approximation and applicable to general atom-field interaction far away from the resonance. We find that there exists remarkable influence of the initial phase of optical field on the Rabi oscillations and Rabi splitting, and this issue cannot be explored in the context of the rotating wave approximation. Due to the retention of the counter-rotating terms, higher-order harmonic appears during the Rabi splitting. The analytical solution suggests a way to regulate and control the quantum dynamics of a two-level atom and allows for exploring more essential features of the atom-field interaction.
Optimal Fungal Space Searching Algorithms.
Asenova, Elitsa; Lin, Hsin-Yu; Fu, Eileen; Nicolau, Dan V; Nicolau, Dan V
2016-10-01
Previous experiments have shown that fungi use an efficient natural algorithm for searching the space available for their growth in micro-confined networks, e.g., mazes. This natural "master" algorithm, which comprises two "slave" sub-algorithms, i.e., collision-induced branching and directional memory, has been shown to be more efficient than alternatives, with one, or the other, or both sub-algorithms turned off. In contrast, the present contribution compares the performance of the fungal natural algorithm against several standard artificial homologues. It was found that the space-searching fungal algorithm consistently outperforms uninformed algorithms, such as Depth-First-Search (DFS). Furthermore, while the natural algorithm is inferior to informed ones, such as A*, this under-performance does not importantly increase with the increase of the size of the maze. These findings suggest that a systematic effort of harvesting the natural space searching algorithms used by microorganisms is warranted and possibly overdue. These natural algorithms, if efficient, can be reverse-engineered for graph and tree search strategies.
Merrill, Robert K; McAnany, Steven J; Albert, Todd J; Qureshi, Sheeraz A
2017-08-14
Cost-effectiveness analysis. Investigate the 7-year cost-effectiveness of two-level cervical disc replacement (CDR) and anterior cervical discectomy and fusion (ACDF). CDR and ACDF are both effective treatment strategies for managing degenerative conditions of the cervical spine. CDR has been shown to be a more-cost effective intervention in the short term, but the long-term cost-effectiveness has not been established. We analyzed 7-year follow-up data from the two-level Medtronic Prestige LP investigational device exemption study. Short-form 36 (SF-36) data were converted into health utility scores using the SF-6D algorithm. Costs were based on direct costs from the payer perspective, and effectiveness was measured as quality adjusted life years (QALYs). The willingness to pay (WTP) threshold was set to $50,000/QALY. A probabilistic sensitivity analysis was conducted via Monte Carlo simulation. Two-level CDR had a 7-year cost of $176,654.19, generated 4.65 QALYs, and had a cost-effectiveness ratio of $37,993.53/QALY. Two-level ACDF had a 7-year cost of $158,373.48, generated 4.44 QALYs, and had a cost-effectiveness ratio of $35,635.72. CDR was associated with an incremental cost of $18,280.71 and an incremental effectiveness of 0.21 QALYs, resulting in an incremental cost-effectiveness ratio (ICER) of $89,021.04, above the WTP threshold. Our Monte Carlo simulation demonstrated CDR would be chosen 46% of the time based on 10,000 simulations. Two-level CDR and ACDF are both cost-effective procedures at 7-year follow-up for treating degenerative conditions of the cervical spine. Based on an ICER of $89,021.04/QALY, we cannot conclude which treatment is the more cost-effective option at 7-years. CDR would be chosen 46% of the time based on 10,000 iterations of our Monte Carlo probabilistic sensitivity analysis. 3.
The inference of gene trees with species trees.
Szöllősi, Gergely J; Tannier, Eric; Daubin, Vincent; Boussau, Bastien
2015-01-01
This article reviews the various models that have been used to describe the relationships between gene trees and species trees. Molecular phylogeny has focused mainly on improving models for the reconstruction of gene trees based on sequence alignments. Yet, most phylogeneticists seek to reveal the history of species. Although the histories of genes and species are tightly linked, they are seldom identical, because genes duplicate, are lost or horizontally transferred, and because alleles can coexist in populations for periods that may span several speciation events. Building models describing the relationship between gene and species trees can thus improve the reconstruction of gene trees when a species tree is known, and vice versa. Several approaches have been proposed to solve the problem in one direction or the other, but in general neither gene trees nor species trees are known. Only a few studies have attempted to jointly infer gene trees and species trees. These models account for gene duplication and loss, transfer or incomplete lineage sorting. Some of them consider several types of events together, but none exists currently that considers the full repertoire of processes that generate gene trees along the species tree. Simulations as well as empirical studies on genomic data show that combining gene tree-species tree models with models of sequence evolution improves gene tree reconstruction. In turn, these better gene trees provide a more reliable basis for studying genome evolution or reconstructing ancestral chromosomes and ancestral gene sequences. We predict that gene tree-species tree methods that can deal with genomic data sets will be instrumental to advancing our understanding of genomic evolution.
Du, Ding-Zhu
2001-01-01
This book is a collection of articles studying various Steiner tree prob lems with applications in industries, such as the design of electronic cir cuits, computer networking, telecommunication, and perfect phylogeny. The Steiner tree problem was initiated in the Euclidean plane. Given a set of points in the Euclidean plane, the shortest network interconnect ing the points in the set is called the Steiner minimum tree. The Steiner minimum tree may contain some vertices which are not the given points. Those vertices are called Steiner points while the given points are called terminals. The shortest network for three terminals was first studied by Fermat (1601-1665). Fermat proposed the problem of finding a point to minimize the total distance from it to three terminals in the Euclidean plane. The direct generalization is to find a point to minimize the total distance from it to n terminals, which is still called the Fermat problem today. The Steiner minimum tree problem is an indirect generalization. Sch...
Berestovskii, V N
2007-01-01
We show that every inner metric space X is the metric quotient of a complete R-tree via a free isometric action, which we call the covering R-tree of X. The quotient mapping is a weak submetry (hence, open) and light. In the case of compact 1-dimensional geodesic space X, the free isometric action is via a subgroup of the fundamental group of X. In particular, the Sierpin'ski gasket and carpet, and the Menger sponge all have the same covering R-tree, which is complete and has at each point valency equal to the continuum. This latter R-tree is of particular interest because it is "universal" in at least two senses: First, every R-tree of valency at most the continuum can be isometrically embedded in it. Second, every Peano continuum is the image of it via an open light mapping. We provide a sketch of our previous construction of the uniform universal cover in the special case of inner metric spaces, the properties of which are used in the proof.