Thesaurus-assisted search term selection and query expansion: a review of user-centred studies

This paper provides a review of the literature related to the application of domain-specific thesauri in the search and retrieval process. Focusing on studies which adopt a user-centred approach, the review presents a survey of the methodologies and results from empirical studies undertaken on the use of thesauri as sources of term selection for query formulation and expansion during the search process. It summaries the ways in which domain-specific thesauri from different disciplines have been used by various types of users and how these tools aid users in the selection of search terms. The review consists of two main sections covering, firstly studies on thesaurus-aided search term selection and secondly those dealing with query expansion using thesauri. Both sections are illustrated with case studies that have adopted a user-centred approach

Assessing the impact of user interaction with thesaural knowledge structures: a quantitative analysis framework

Thesauri have been important information and knowledge organisation tools for more than three decades. The recent emergence and phenomenal growth of the World Wide Web has created new opportunities to introduce thesauri as information search and retrieval aids to end user communities. While the number of web-based and hypertextual thesauri continues to grow, few investigations have yet been carried out to evaluate how end-users, for whom all these efforts are ostensibly made, interact with and make use of thesauri for query building and expansion. The present paper reports a pilot study carried out to determine the extent to which a thesaurus-enhanced search interface to a web-based database aided end-users in their selection of search terms. The study also investigated the ways in which users interacted with the thesaurus structure, terms, and interface. Thesaurus-based searching and browsing behaviours adopted by users while interacting with the thesaurus-enhanced search interface were also examined

Status of the demersal fishery resources of Bangladesh

The present study makes use of the fisheries survey data collected during the period 1984 - 87 by the multi-purpose research vessel RV Anusandhani in the waters of Bangladesh, Bay of Bengal. The data consists of twelve survey cruises directed at the shrimp resources (1985 - 87) and nineteen survey cruises directed at the demersal fish resources (1984 - 86). The biomasses for shrimp and demersal fish during the survey period were estimated, along with a detailed analysis of biomass distribution by depth zone and catch rates for important species of shrimp and demersal fish species. The demersal fish and shrimp biomass during the survey period was estimated as 176 160 t and 857 t, respectively. The levels of biomass when compared with 1973 estimates indicate a tremendous decline, by about 90% for shrimps and 30% for demersal fish. Population parameters for four species of shrimps (for both males and females) as well as for eight demersal fish species were also estimated. The parameter estimates were validated using available growth and mortality parameter values from the literature, and were in turn used to estimate the mean exploitation rate (E) of demersal fish and shrimp species comprising the trawl catch. Mean E values for shrimp species is at 0.61 and 0.57 for demersal fish species, indicating over-exploitation of demersal resources in the Bay of Bengal. Exploratory analysis using surplus production modeling of catch and effort data shows that the maximum sustainable yield (MSY) level for shrimp resources is around 3 500 t, corresponding to a maximum effort level of approximately 6 480 fishing days. Similar analysis for demersal fish catches gave poor correlations between catch rates and fishing effort.Fishery resources, Demersal fisherie, Fishery surveys, Biomass, Population density, Shrimp fisheries, Catch/effort, ISW, Bangladesh,

Locational Marginal Pricing Basics for Restructured Wholesale Power Markets

Abstract: Although Locational Marginal Pricing (LMP) plays an important role in many restructured wholesale power markets, the detailed derivation of LMPs as actually used in industry practice is not readily available. This lack of transparency greatly hinders the efforts of researchers to evaluate the performance of these markets. In this paper, different AC and DC optimal power flow (OPF) models are presented to help understand the derivation of LMPs. As a byproduct of this analysis, the paper provides a rigorous explanation of the basic LMP and LMP-decomposition formulas (neglecting real power losses) presented without derivation in the business practice manuals of the U.S. Midwest Independent System Operator (MISO)

IMPACT OF STRATEGIC CHANGES ON THE PERFORMANCE OF TRUCKING FIRMS IN THE AGRICULTURAL COMMODITY TRANSPORTATION MARKET

Econometric models were developed to estimate factors that influence strategic changes and evaluate the impacts that strategic changes will have on the subsequent performance of agricultural commodity trucking firms. Results reveal that GDP and change in firm size will have positive impacts on strategic changes made by firms.Public Economics,

GPU-parallelisation of Haar wavelet-based grid resolution adaptation for fast finite volume modelling: application to shallow water flows

Wavelet-based grid resolution adaptation driven by the ‘multiresolution analysis’ (MRA) of the Haar wavelet (HW) allows to devise an adaptive first-order finite volume (FV1) model (HWFV1) that can readily preserve the modelling fidelity of its reference uniform-grid FV1 counterpart. However, the MRA entails an enormous computational effort as it involves ‘encoding’ (coarsening), ‘decoding’ (refining), analysing and traversing modelled data across a deep hierarchy of nested, uniform grids. GPU-parallelisation of the MRA is needed to handle its computational effort, but its algorithmic structure (1) hinders coalesced memory access on the GPU and (2) involves an inherently sequential tree traversal problem. This work redesigns the algorithmic structure of the MRA in order to parallelise it on the GPU, addressing (1) by applying Z-order space-filling curves and (2) by adopting a parallel tree traversal algorithm. This results in a GPU-parallelised HWFV1 model (GPU-HWFV1). GPU-HWFV1 is verified against its CPU predecessor (CPU-HWFV1) and its GPU-parallelised reference uniform-grid counterpart (GPU-FV1) over five shallow water flow test cases. GPU-HWFV1 preserves the modelling fidelity of GPU-FV1 while being up to 30 times faster. Compared to CPU-HWFV1, it is up to 200 times faster, suggesting that the GPU-parallelised MRA could be used to speed up other FV1 models

LISFLOOD-FP 8.1: new GPU-accelerated solvers for faster fluvial/pluvial flood simulations

The local inertial two-dimensional (2D) flow model on LISFLOOD-FP, the so-called ACCeleration (ACC) uniform grid solver, has been widely used to support fast, computationally efficient fluvial/pluvial flood simulations. This paper describes new releases, on LISFLOOD-FP 8.1, for parallelised flood simulations on the graphical processing units (GPUs) to boost efficiency of the existing parallelised ACC solver on the central processing units (CPUs) and enhance it further by enabling a new non-uniform grid version. The non-uniform solver generates its grid using the multiresolution analysis (MRA) of the multiwavelets (MWs) to a Galerkin polynomial projection of the digital elevation model (DEM). This sensibly coarsens the resolutions where the local topographic details are below an error threshold ε and allows classes of land use to be properly adapted. Both the grid generator and the adapted ACC solver on the non-uniform grid are implemented in a GPU new codebase, using the indexing of Z-order curves alongside a parallel tree traversal approach. The efficiency performance of the GPU parallelised uniform and non-uniform grid solvers is assessed for five case studies, where the accuracy of the latter is explored for and 10−3 in terms of how close it can reproduce the prediction of the former. On the GPU, the uniform ACC solver is found to be 2–28 times faster than the CPU predecessor with increased number of elements on the grid, and the non-uniform solver can further increase the speed up to 320 times with increased reduction in the grid's elements and decreased variability in the resolution. LISFLOOD-FP 8.1, therefore, allows faster flood inundation modelling to be performed at both urban and catchment scales. It is openly available under the GPL v3 license, with additional documentation at https://www.seamlesswave.com/LISFLOOD8.0 (last access: 12 March 2023)

The S-matrix of the Faddeev-Reshetikhin Model, Diagonalizability and PT Symmetry

We study the question of diagonalizability of the Hamiltonian for the Faddeev-Reshetikhin (FR) model in the two particle sector. Although the two particle S-matrix element for the FR model, which may be relevant for the quantization of strings on $AdS_{5}\times S^{5}$, has been calculated recently using field theoretic methods, we find that the Hamiltonian for the system in this sector is not diagonalizable. We trace the difficulty to the fact that the interaction term in the Hamiltonian violating Lorentz invariance leads to discontinuity conditions (matching conditions) that cannot be satisfied. We determine the most general quartic interaction Hamiltonian that can be diagonalized. This includes the bosonic Thirring model as well as the bosonic chiral Gross-Neveu model which we find share the same S-matrix. We explain this by showing, through a Fierz transformation, that these two models are in fact equivalent. In addition, we find a general quartic interaction Hamiltonian, violating Lorentz invariance, that can be diagonalized with the same two particle S-matrix element as calculated by Klose and Zarembo for the FR model. This family of generalized interaction Hamiltonians is not Hermitian, but is $PT$ symmetric. We show that the wave functions for this system are also $PT$ symmetric. Thus, the theory is in a $PT$ unbroken phase which guarantees the reality of the energy spectrum as well as the unitarity of the S-matrix.Comment: 32 pages, 1 figure; references added, version published in JHE

Integrable open spin chains from giant gravitons

We prove that in the presence of a maximal giant graviton state in N=4 SYM, the states dual to open strings attached to the giant graviton give rise to an PSU(2,2|4) open spin chain model with integrable boundary conditions in the SO(6) sector of the spin chain to one loop order.Comment: 18 pages, 2 figures, uses JHEP

A study of open strings ending on giant gravitons, spin chains and integrability

We systematically study the spectrum of open strings attached to half BPS giant gravitons in the N=4 SYM AdS/CFT setup. We find that some null trajectories along the giant graviton are actually null geodesics of AdS_5x S^5, so that we can study the problem in a plane wave limit setup. We also find the description of these states at weak 't Hooft coupling in the dual CFT. We show how the dual description is given by an open spin chain with variable number of sites. We analyze this system in detail and find numerical evidence for integrability. We also discover an interesting instability of long open strings in Ramond-Ramond backgrounds that is characterized by having a continuum spectrum of the string, which is separated from the ground state by a gap. This instability arises from accelerating the D-brane on which the strings end via the Ramond-Ramond field. From the integrable spin chain point of view, this instability prevents us from formulating the integrable structure in terms of a Bethe Ansatz construction.Comment: 38 pages+appendices, 9 figures. Uses JHEP3. v2: added reference