Large Number Of Rows Research Articles

Wave power calculation of a large periodic array of bottom-hinged paddle wave energy converters using Floquet–Bloch theory

In this study we consider a wave energy farm consisting of a large number of bottom-hinged paddles. The paddles are arranged in a doubly-periodic manner, with a finite number of identical rows and each row containing an infinite number of paddles. Each paddle is attached to its own damper and spring, allowing power to be generated through its pitching motion. Unlike previous studies into paddle arrays, we envisage compact arrays consisting of small devices arranged across a large number of rows. The mathematical analysis of this proposed configuration is best suited to methods that exploit the periodicity of the array. It is shown that the velocity potential everywhere within the array can be described by an expansion in terms of suitably-defined Floquet–Bloch eigenmodes and this allows the solution to the scattering problem involving waves incident upon the array to be determined by a simple low-order system of equations. The method used in this study is exact within the setting of linearised water waves and has all of the advantages of classical low-frequency multi-scale homogenisation without the low-frequency restriction. It may also be regarded as a natural extension of the well-known wide-spacing approximation without the large separation restriction. Although the focus of this paper is on the mathematical approach to the solution of the problem, we provide a range of results to illustrate the performance of this proposed wave energy converter concept.

Architected material analogs for shape memory alloys

Architected material analogs for shape memory alloys

Xeromorphic Features of the Leaves of Liriodendron Tulipifera L. (Magnoliaceae) in the Arid Climate of Central Asia

High irradiance of a habitat in arid areas is usually associated with high temperature and dry air, which can cause water deficiency in plants. The Tulip tree (Liriodendron tulipifera) is a light-loving mesophytic species. This study showed that L. tulipifera forms shade or sun leaves depending on the light conditions. Some xeromorphic features were found in leaves of the trees in illuminated habitats. These sun leaves are smaller, denser, and thicker, with smaller epidermal cells and a thick cuticle; the spongy parenchyma consists of a larger number of rows of small cells; the cells of the columnar parenchyma are larger than the shade leaves. The sun leaf contains more total chlorophyll (by 20–30%), and the guard cells of the stomata of the sun leaf contain chloroplasts. The increased concentration of chlorophyll probably maintains the energy balance in the conditions of inhibited photosynthesis under high illumination and temperature. Decreased sizes of the sun leaf and epidermis cells, thickening of the cuticle and cell wall of epidermal cells, sunken stomata, compact mesophyll with small intercellular spaces, and multirow spongy parenchyma protect from overheating and passive loss of water and can be considered as xeromorphic features. Large numerous stomata and vascular bundles contribute to effective cooling of the surface by transpiration at high temperatures under sufficient water supply. Thus, the leaves of L. tulipifera have an ecological plasticity in relation to illumination and temperature, which contributed to the acclimation of the species to the habitat conditions in arid climates.

Revision of the Alitta virens species complex (Annelida: Nereididae) from the North Pacific Ocean

Alitta virens species complex encompasses elongate nereidids appreciated commercially both in the fishing and aquaculture industries. This complex has been well studied in biological and ecological terms. Nevertheless, detailed taxonomic analyses have scarcely been addressed, to the extent that only a few species in the complex have been recognized as valid but with some difficulties: Alitta brandti Malmgren, 1865 (Sea of Okhotsk), A. grandis (Stimpson, 1853) (northeastern USA) and A. virens (Sars, 1835) (Norway). Whereas, other several species have typically been regarded as synonyms, including those originally described from the North Pacific Ocean: Nereis (Alitta) virens plenidentata Moore, 1909 (California, USA), Nereis dyamusi Izuka, 1912 (Japan) and Nereis foliata Baird, 1863 (Vancouver, Canada). In this study, an examination of the immature and epitoke type and non-type material available for the A. virens species complex from the North Pacific was carried out. Herein, the status of A. brandti as a valid species is reinforced being clearly distinct from A. virens and related species. Alitta dyamusi n. comb., A. plenidentata n. comb. and A. williami nom. nov. are reinstated and transferred to Alitta, the specific epithet of the latter species is a replacement name for Nereis foliata Baird, 1863, which is a junior, primary homonym of Nereis foliata Dalyell, 1853. Lectotypes for A. plenidentata n. comb. and A. williami nom. nov. are designated. The North Pacific species of the A. virens complex, excluding A. plenidentata n. comb. which has several distinctive features that differ from all the Alitta species, are characterized by having homogomph spinigers in both supracicular and subacicular neurochaetae, oral ring with a larger number of rows and paragnaths, and epitoke males with unmetamorphosed pygidium and epitoke-modified chaetae in both neuropodial fascicles. The morphology of epitoke females in the A. virens complex is described for the first time. Identification keys to atoke and epitoke species of this complex are also provided.

Basis selection in spectral learning of predictive state representations

Abstract Predictive State Representations (PSRs) are powerful techniques for modelling dynamical systems, which represent state as a vector of predictions about future observable events (tests). In PSRs, one of the fundamental problems is the learning of the PSR model of the underlying system. Recently, spectral methods have been successfully used to address this issue by treating the learning problem as the task of computing Singular Value Decompositions (SVD)over a submatrix of a special type of matrix called the Hankel matrix. Under the assumptions that the rows and columns of the submatrix of the Hankel Matrix are sufficient (which usually means a very large number of rows and columns, and almost fails in practice) and the entries of the matrix can be estimated accurately, it has been proven that the spectral approach for learning PSRs is statistically consistent and the learned parameters can converge to the true parameters. However, in practice, due to the limit of the computation ability, only a finite set of rows or columns can be chose to be used for the spectral learning. While different sets of columns usually lead to variant accuracy of the learned model, in this paper, we propose an approach for selecting the set of columns, namely basis selection, by adopting a concept of model entropy to measure the accuracy of the learned model. Experimental results are shown to demonstrate the effectiveness of the proposed approach.

ComVisMD - compact visualization of multidimensional data: experimenting with cricket players data

Database information is multidimensional and often displayed in tabular format (row/column display). Presented in aggregated form, multidimensional data can be used to analyze the records or objects. Online Analytical database Processing (OLAP) proposes mechanisms to display multidimensional data in aggregated forms. A choropleth map is a thematic map in which areas are colored in proportion to the measurement of a statistical variable being displayed, such as population density. They are used mostly for compact graphical representation of geographical information. We propose a system, ComVisMD inspired by choropleth map and the OLAP cube to visualize multidimensional data in a compact way. ComVisMD displays multidimensional data like OLAP Cube, where we are mapping an attribute a (first dimension, e.g. year started playing cricket) in vertical direction, object coloring based on b (second dimension, e.g. batting average), mapping varying-size circles based on attribute c (third dimension, e.g. highest score), mapping numbers based on attribute d (fourth dimension, e.g. matches played). We illustrate our approach on cricket players data, namely on two tables Country and Player. They have a large number of rows and columns: 246 rows and 17 columns for players of one country. ComVisMD’s visualization reduces the size of the tabular display by a factor of about 4, allowing users to grasp more information at a time than the bare table display.

Graphene antidot lattice transport measurements

We investigate graphene devices patterned with a narrow band of holes perpendicular to the current flow, a few-row graphene antidot lattice (FR-GAL). Theoretical reports suggest that a FR-GAL can have a bandgap with a relatively small reduction of the transmission compared to what is typical for antidot arrays devices. Graphene devices were fabricated using 100 keV electron beam lithography (EBL) for nanopatterning as well as for defining electrical contacts. Patterns with hole diameter and neck widths of order 30 nm were produced, which is the highest reported pattern density of antidot lattices in graphene reported defined by EBL. Electrical measurements showed that devices with one and five rows exhibited field effect mobility of ∼100 cm2/Vs, while a larger number of rows, around 40, led to a significant reduction of field effect mobility (<5 cm2/Vs). The carrier mobility was measured as a function of temperature, with the low-temperature behaviour being well described by variable range hopping, indicating the transport to be dominated by disorder.

A factored variant of the Newton iteration for the solution of algebraic Riccati equations via the matrix sign function

In this paper we introduce a variant of the Newton iteration for the matrix sign function that results in an efficient numerical solver for a certain class of algebraic Riccati equations (AREs). In particular, when the Hamiltonian matrix associated with the ARE can be composed as A B B T C T C ? A T $\left [\begin {array}{llll}{A}&{BB^{T}}\\{C^{T}C}&{-A^{T}}\end {array}\right ]$ , with B and C T $C^{T}$ having a much larger number of rows than columns, the new algorithm exploits the special structure of the off-diagonal blocks to yield an alternative factored Newton iteration which reduces the cost per iteration by a factor of up to 8 (16 in case A is symmetric negative definite) w.r.t. the conventional iterative scheme. Experiments with a large collection of benchmark examples show that the factored iteration attains numerical accuracy similar to that of the conventional Newton iteration as well as the structure-preserving doubling algorithm. High-performance implementations of these methods, making heavy use of LAPACK linked to a multi-threaded implementation of BLAS, demonstrate the clear advantage of the new iteration on a 48-core AMD-based platform.

Minimising the number of gap-zeros in binary matrices

We study a problem of minimising the total number of zeros in the gaps between blocks of consecutive ones in the columns of a binary matrix by permuting its rows. The problem is referred to as the Consecutive Ones Matrix Augmentation Problem, and is known to be NP-hard. An analysis of the structure of an optimal solution allows us to focus on a restricted solution space, and to use an implicit representation for searching the space. We develop an exact solution algorithm, which is linear-time in the number of rows if the number of columns is constant, and two constructive heuristics to tackle instances with an arbitrary number of columns. The heuristics use a novel solution representation based upon row sequencing. In our computational study, all heuristic solutions are either optimal or close to an optimum. One of the heuristics is particularly effective, especially for problems with a large number of rows.

Increasing Database Performance through Optimizing Structure Query Language Join Statement

Problem statement: A join statement is a select statement with more th an table in the FROM clause. A join predicate is a predicate in the WHERE clause that combines the columns of two of the tables in the join. Any database gives you t he ability to join various tables together through different types of joins, resulting large number of rows to process. Query language can be used to join these tables and as it is well known query lan guage should be declarative, so we can write alternative formulas to perform join statements. Di fferent formulas provide variation in performance. Approach: This research presented a transparent middle layer between application interface front end and database back end. Results: The responsibilities of this layer were catching t he SQL commands sent by application before reaching the database then examining these commands to see if they join more than one table, after that re writing the SQL command taking into consideration the order of executing join predicates and none joi n predicates. This research focused on rewriting th e SQL commands without application modification. Conclusion: Rewriting stage is the most complex stage because the system will restructure the SQL c ommand with new syntax taking two things in its consideration, the first one was rewriting the comm and with better performance syntax after getting th e help from recommendation dictionary, the second one was resulting the same data (output) as previous old command.

A new species of Palaemon (Crustacea, Decapoda, Palaemonidae) from West Africa, with a re-description of Palaemon maculatus (Thallwitz, 1892)

A new species of Palaemon, P. powelli sp. nov., is described from tropical West Africa. The new species is characterised by the shape and proportions of its chelae, the shape of the rostrum, spacing between dorsal rostral teeth and a poorly developed grooming brush on the fifth pereiopod. Palaemon maculatus (Thallwitz, 1892) is redescribed and can be separated from other eastern Atlantic members of the genus by the form of the rostrum, the proportions of the segments of pereiopod 2 and the large number of rows of setae in the grooming brush on the fifth pereiopod.

Minimal set of class-sums characterizing the ordinary irreducible representations of the symmetric group, and the Tarry-Escott problem

The shape of a Young diagram Y (| Y| = n) can be specified in terms of the set of symmetric power sums over its contents, σ l = Σ ( ij) ϵY ( j − i) l ; l = 1, 2, …, n. It is remarkable that the set of power sums σ 1, σ 2, …, σ k is sufficient to characterize the Young diagrams possessing up to n( k) boxes, where n( k) is considerably larger than k. Numerical evidence for k⩽5 is roughly consistent with n(k) ∼ 4( 4 3 ) 2k . The lower bound n( k) > k + max(2, √ k) has been derived by examination of some properties of Young diagrams with a large number of rows, and the upper bound n( k) < 2 2 k+1 has been established using a variant of the Tarry-Escott problem.

A "Short-Cut" Method for the Complete Solution of Game Theory and Feed-Mix Problems

Previous methods of solving linear programming problems have always had to revert to the simplex method, after the first two or three most promising activities have been located. The present paper shows that this is unnecessary, and presents a method of solving game theory and programming problems without using the simplex method. Despite its title the new method may, in large problems, involve the same amount of computing as the simplex method. A BRIEF DISCUSSION of the special terms used in the title provides a convenient summary of this paper. The adjective has been used to signify that the method presented here is an extension of the graphical short-cut methods previously presented by Waugh and Burrows [5] and Boles [1]. By complete is meant that with this method it is unnecessary to revert to the simplex method at the end of the short-cut; the short-cut leads to the solution of the problem, even when there is a large number of rows and columns. The game theory problems referred to are two-person zero-sum games, and the feed-mix problems refer to programming problems in which all resource supplies are positive, and prices are either all positive or all negative. The notation to be employed will now be described and then the short-cut method will be introduced in conjunction with a discussion of a small game theory problem. 1. NOTATION