Domain analysis and information retrieval through the construction of heliocentric maps based on ISI-JCR category cocitation

We propose the use of ISI-JCR categories as units of cocitation and measurement for the construction of heliocentric maps. The use of a spatial metaphor allows us to illustrate, analyze and compare domains in terms of the categories and their interconnections or links. We can also move around within the structure of these domains for further analysis, and access the documents associated to the categories and to the links that cocite or relate them.     

OpinionLink: Leveraging user opinions for product catalog enrichment

A vast number of user opinions are available from reviews posted on e-commerce websites. Although these opinions are a valuable source of knowledge for both manufacturers and customers, they provide volumes of information that exceeds the human cognitive processing capacity, which can be a major bottleneck for their effective use. To address this problem, a number of opinion-summarization methods have been proposed to organize these opinions by grouping them around aspects. However, these methods tend to generate an excessive number of aspect groups that are frequently overly generic and difficult to interpret. We argue that a superior alternative would be to organize opinions around product attributes as defined in a product catalog. Typically, product attributes correspond to the most important characteristics of the products. Furthermore, they are common to all products in a given category and thus, form a more stable set than aspects. In this paper, we propose a novel approach called OpinionLink to products in a catalog at the attribute granularity level with opinions extracted from product reviews. The proposed approach is divided into two phases. In the first phase, OpinionLink uses a classifier to identify opinionated sentences in the reviews on a particular product. In the second phase, another classifier is used to map the opinions that were previously extracted from the user reviews to the attributes of the products in the product catalog. We performed a series of experiments on these phases. For the first phase, our experiments indicated that using classifiers with the proposed features achieved an average of 0.87 in terms of F₁ measure for the task of identifying opinionated sentences. In the second phase, the method we proposed for the opinion-mapping task achieved an average of 0.85 in terms of F₁. Further, we verified the effectiveness of the proposed approach as a realistic end-to-end application, indicating that we can use OpinionLink in a real setting. Finally, we empirically demonstrate the feasibility of using the proposed approach with an extremely large volume of opinions available in a collection of more than 600,000 real reviews. We also set forth a number of directions for future research.     

Adaptive stabilization of linear and nonlinear plants in the presence of large and arbitrarily fast variations of the parameters

The problem of adaptive stabilization of a class of continuous-time and time-varying nonlinear plants is treated in this paper. The control scheme guarantees that the state of the plant, with bounded time-varying parameters, asymptotically converges to zero. For the nonlinear case with n²+n unknown parameters (n time-varying and n² constant), when the control matrix B is unknown the controller has to adjust n²+1 parameters providing only local stability results. On the contrary, when the control matrix B is known only one parameter has to be adjusted and the proposed scheme provides global stability results. The general methodology is particularized for the linear case with 2n² unknown parameters (n² time-varying and n² constant), adjusting n²+1 parameters when the control matrix B is unknown and guarantees only local stability results, whereas in the case when the control matrix B is known only one parameter has to be adjusted and the proposed scheme provides global stability results.     

An experimental investigation of forced vibrations

The solution of the differential equation y″ + 2Ry′ + n²y = E cos pt is written in a new form which clearly exhibits many important facts thus far overlooked by theoretical and experimental investigators. Writing s = n ? p, and Δn = n ? √n² ? R², it is found: (a) When s ≠ Δn, there are “beats,” and the first “beat” maximum is greater than any later maximum while the first “beat” minimum is less than any later “beat” minimum. The “beat” frequency is $\text{(s ?}\text{Δ}\text{n)}\text{2π}$. (b) When n² ? p² = R², there are no “beats,” and the resultant amplitude grows monotonically from zero to the amplitude of the forced vibration, (c) At resonance, when n = p, we still have maxima which occur with a frequency $\text{Δ}\text{n}\text{2π}$ in a damped system. (d) The absence of “beats” is neither a sufficient nor a necessary condition for resonance in a damped system.In the experimental investigation the upper extremity of a simple pendulum was moved in simple harmonic motion and photographic records obtained of the motion of the pendulum bob. Different degrees of damping were used, ranging from very small to critical.The experimental results are in excellent agreement with theory.     

On the two-dimensional steady flow of a compressible viscous fluid far behind a solid symmetrical body

A number of writers have observed that the particle size distributions obtained from some breakage processes appear to be logarithmico-normal. There have been virtually no attempts to explain this phenomenon. In this paper a statistical model is constructed for a breakage mechanism which will generate size distributions which are asymptotically logarithmico-normal. In this model, F_n(x), the distribution function of the particle sizes, after n steps of the breakage process, is the distribution function of the product of (n + 1) independent random variables and hence, by the central limit theorem, is asymptotically logarithmico-normal.     

Comparing inverted files and signature files for searching a large lexicon

Signature files and inverted files are well-known index structures. In this paper we undertake a direct comparison of the two for searching for partially-specified queries in a large lexicon stored in main memory. Using n-grams to index lexicon terms, a bit-sliced signature file can be compressed to a smaller size than an inverted file if each n-gram sets only one bit in the term signature. With a signature width less than half the number of unique n-grams in the lexicon, the signature file method is about as fast as the inverted file method, and significantly smaller. Greater flexibility in memory usage and faster index generation time make signature files appropriate for searching large lexicons or other collections in an environment where memory is at a premium.     

Distributed Expert-Based Information Systems: An interdisciplinary approach

An international workshop on Distributed Expert-Based Information Systems (DEBIS) was held at Rutgers University in March 1987. The aims of the workshop were to discuss problems and issues in the design of such systems, and to develop research and implementation strategies for them. The workshop attendees discussed both models and implementations of DEBIS. A prototypical implementation operates on one or more workstations and connects an end-user to an information source after invoking multiple expert functions. The design of these functions depends in part on careful study of end-user and search intermediary behavior. Such studies suggest a dozen basic functions which must be incorporated in a DEBIS. including ones to model the user, generate search strategies, and manage the interface. The favored methods of implementation use blackboards to simplify communications between functional modules. Two large systems, I³R and CODER, have been developed which illustrate the complexity but also the feasibility of DEBIS.     

Using surface plasmon resonance imaging to study bacterial biofilms

This paper describes the use of Surface Plasmon Resonance imaging (SPRi) as an emerging technique to study bacterial physiology in real-time without labels. The overwhelming majority of bacteria on earth exist in large multicellular communities known as biofilms. Biofilms are especially problematic because they facilitate the survival of pathogens, leading to chronic and recurring infections as well as costly industrial complications. Monitoring biofilm accumulation and removal is therefore critical in these and other applications. SPRi uniquely provides label-free, high-resolution images of biomass coverage on large channel surfaces up to 1 cm² in real time, which allow quantitative assessment of biofilm dynamics. The rapid imaging capabilities of this technique are particularly relevant for multicellular bacterial studies, as these cells can swim several body lengths per second and divide multiple times per hour. We present here the first application of SPRi to image Escherichia coli and Pseudomonas aeruginosa cells moving, attaching, and forming biofilms across a large surface. This is also the first time that biofilm removal has been visualized with SPRi, which has important implications for monitoring the biofouling and regeneration of fluidic systems. Initial images of the removal process show that the biofilm releases from the surface as a wave along the direction of the fluid flow.     

Character n-gram application for automatic new topic identification

The widespread availability of the Internet and the variety of Internet-based applications have resulted in a significant increase in the amount of web pages. Determining the behaviors of search engine users has become a critical step in enhancing search engine performance. Search engine user behaviors can be determined by content-based or content-ignorant algorithms. Although many content-ignorant studies have been performed to automatically identify new topics, previous results have demonstrated that spelling errors can cause significant errors in topic shift estimates. In this study, we focused on minimizing the number of wrong estimates that were based on spelling errors. We developed a new hybrid algorithm combining character n-gram and neural network methodologies, and compared the experimental results with results from previous studies. For the FAST and Excite datasets, the proposed algorithm improved topic shift estimates by 6.987% and 2.639%, respectively. Moreover, we analyzed the performance of the character n-gram method in different aspects including the comparison with Levenshtein edit-distance method. The experimental results demonstrated that the character n-gram method outperformed to the Levensthein edit distance method in terms of topic identification.     

Use of widgets as information management tools in online shared spaces

Online shared spaces are destinations where people of common interests interact to achieve common goals or borrow each other's expertise for personal pursuits. Due to a multitude of users, such spaces generate large amounts of content, thus creating a potential for information overload. To deal with it, users of online shared spaces develop information management strategies that frequently involve the use of information technology. In this paper we present a case study of the use of widgets as information management tools in uCern, an online shared workspace where healthcare industry stakeholders get involved in various types of interactions. To understand how widgets served the purpose of information management and whether they were considered useful, we administered an online questionnaire (n = 183) followed by qualitative interviews (n = 5). Data analysis revealed that study participants used widgets as tools that promoted their situation and activity awareness of events and activities going on in uCern and helped them with organizing and accessing the content in a quick and efficient manner. We also describe issues associated with the use of widgets and their usefulness as reported by participants and propose implications for design and development of online shared spaces in relation to information management tools.     

Non-iterative pole placement technique: A step further

This paper comes back to the hard problem of pole placement by static output feedback: let a triplet of matrices {A;B;C}∈R^n×n×R^n×m×R^p×n be given, find a matrix K∈R^m×p such that the spectrum of A+BKC equals a specified set. More precisely, this article focuses on the derivation of non-iterative techniques, based upon the notion of eigenstructure assignment, to solve the problem, especially when Kimura's condition does not hold. Some solutions can sometimes be found.     

Kinetics of acoustic release of doxorubicin from stabilized and unstabilized micelles and the effect of temperature

Ultrasound is being investigated as a trigger mechanism to deliver high concentrations of chemotherapy drugs to cancerous tissues using polymeric micelles. In this paper, we examined the kinetics of acoustic release of doxorubicin using stabilized and non-stabilized micelles. Kinetic models were used to regress release and re-encapsulation time constants for three different compounds, namely non-stabilized Pluronic^® P105 micelles, P105 micelles stabilized using an interpenetrating network of N,N-diethylacrylamide and micelles formed by PEO-b-poly(NIPAAm-co-HEMA-lactate_n). Results showed that the kinetic release constant (k_r) depends on the micellar system under investigation. On the other hand, there is no statistically significant difference between re-encapsulation rate constants for stabilized and unstabilized micelles. We hypothesize that k_r depends on the degree of cross-linking or stabilization.     

Optimal tensegrity structures in bending: The discrete Michell truss

This paper provides the closed form analytical solution to the problem of minimizing the material volume required to support a given set of bending loads with a given number of discrete structural members, subject to material yield constraints. The solution is expressed in terms of two variables, the aspect ratio, ρ^-1, and complexity of the structure, q (the total number of members of the structure is equal to q(q+1)). The minimal material volume (normalized) is also given in closed form by a simple function of ρ and q, namely, V=q(ρ^-1/q-ρ^1/q). The forces for this nonlinear problem are shown to satisfy a linear recursive equation, from node-to-node of the structure. All member lengths are specified by a linear recursive equation, dependent only on the initial conditions involving a user specified length of the structure. The final optimal design is a class 2 tensegrity structure. Our results generate the 1904 results of Michell in the special case when the selected complexity q approaches infinity. Providing the optimum in terms of a given complexity has the obvious advantage of relating complexity q to other criteria, such as costs, fabrication issues, and control. If the structure is manufactured with perfect joints (no glue, welding material, etc.), the minimal mass complexity is infinite. But in the presence of any joint mass, the optimal structural complexity is finite, and indeed quite small. Hence, only simple structures (low complexity q) are needed for practical design.     

Optimal complexity of deployable compressive structures

The usual use of fractals involves self-similar geometrical objects to fill a space, where the self-similar iterations may continue ad infinitum. This is the first paper to propose the use of self-similar mechanical objects that fill an alloted space, while achieving an invariance property as the self-similar iterations continue (e.g. invariant strength). Moreover, for compressive loads, this paper shows how to achieve minimal mass and invariant strength from self-similar structures. The topology optimization procedure uses self-similar iteration until minimal mass is achieved, and this problem is completely solved, with global optimal solutions given in closed form. The optimal topology remains independent of the magnitude of the load. Mass is minimized subject to yield and/or buckling constraints. Formulas are also given to optimize the complexity of the structure, and the optimal complexity turns out to be finite. That is, a continuum is never the optimal structural for a compressive load under any constraints on the physical dimension (diameter). After each additional self-similar iteration, the number of bars and strings increase, but, for a certain choice of unit topology shown, the total mass of bars and strings decreases. For certain structures, the string mass monotonically increases with iteration, while the bar mass monotonically reduces, leading to minimal total mass in a finite number of iterations, and hence a finite optimal complexity for the structure. The number of iterations required to achieve minimal mass is given explicitly in closed form by a formula relating the chosen unit geometry and the material properties. It runs out that the optimal structures produced by our theory fall in the category of structures we call tensegrity. Hence our self-similar algorithms can generate tensegrity fractals.     

Interpolative coding of integer sequences supporting log-time random access

Sequences of integers are common data types, occurring either as primary data or ancillary structures. The sizes of sequences can be large, making compression an interesting option. Effective compression presupposes variable-length coding, which destroys the regular alignment of values. Yet it would often be desirable to access only a small subset of the entries, either by position (ordinal number) or by content (element value), without having to decode most of the sequence from the start. Here such a random access technique for compressed integers is described, with the special feature that no auxiliary index is needed. The solution applies a method called interpolative coding, which is one of the most efficient non-statistical codes for integers. Indexing is avoided by address calculation guaranteeing sufficient space for codes even in the worst case. The additional redundancy, compared to regular interpolative coding, is only about 1 bit per source integer for uniform distribution. The time complexity of random access is logarithmic with respect to the source size for both position-based and content-based retrieval. According to experiments, random access is faster than full decoding when the number of accessed integers is not more than approximately 0.75 · n/log₂n for sequence length n. The tests also confirm that the method is quite competitive with other approaches to random access coding, suggested in the literature.     

Iterative radial basis functions neural networks as metamodels of stochastic simulations of the quality of search engines in the World Wide Web

Stochastic simulation has been very effective in many domains but never applied to the WWW. This study is a premiere in using neural networks in stochastic simulation of the number of rejected Web pages per search query. The evaluation of the quality of search engines should involve not only the resulting set of Web pages but also an estimate of the rejected set of Web pages. The iterative radial basis functions (RBF) neural network developed by Meghabghab and Nasr [Iterative RBF neural networks as meta-models for stochastic simulations, in: Second International Conference on Intelligent Processing and Manufacturing of Materials, IPMM’99, Honolulu, Hawaii, 1999, pp. 729–734] was adapted to the actual evaluation of the number of rejected Web pages on four search engines, i.e., Yahoo, Alta Vista, Google, and Northern Light. Nine input variables were selected for the simulation: (1) precision, (2) overlap, (3) response time, (4) coverage, (5) update frequency, (6) boolean logic, (7) truncation, (8) word and multi-word searching, (9) portion of the Web pages indexed. Typical stochastic simulation meta-modeling uses regression models in response surface methods. RBF becomes a natural target for such an attempt because they use a family of surfaces each of which naturally divides an input space into two regions X+ and X− and the n patterns for testing will be assigned either class X+ or X−. This technique divides the resulting set of responses to a query into accepted and rejected Web pages. To test the hypothesis that the evaluation of any search engine query should involve an estimate of the number of rejected Web pages as part of the evaluation, RBF meta-model was trained on 937 examples from a set of 9000 different simulation runs on the nine different input variables. Results show that two of the variables can be eliminated which include: response time and portion of the Web indexed without affecting evaluation results. Results show that the number of rejected Web pages for a specific set of search queries on these four engines very high. Also a goodness measure of a search engine for a given set of queries can be designed which is a function of the coverage of the search engine and the normalized age of a new document in result set for the query. This study concludes that unless search engine designers address the issue of rejected Web pages, indexing, and crawling, the usage of the Web as a research tool for academic and educational purposes will stay hindered.     

Magnetic losses in remanent state ferrites

Magnetic loss in remanent state ferrites¹ has generally been described through the artifice of a magnetic loss tangent (tanδ_m = μ^″?μ′). This characterization is not directly relatable to intrinsic material parameters. The results presented in this paper indicate that magnetic loss in the remanent state can be related to intrinsic material parameters by describing the ferrite mathematically by a complex “average” permeability tensor. The “average” permeability includes the effects of magnetocrystalline anistropy, remanent magnetization, linewidth and an average demagnetizing field appropriate to the distribution of magnetic domains. Experimental examples are given showing that excellent agreement is obtained between theoretically predicted and measured losses.     

Leveraging relevance cues for language modeling in speech recognition

Language modeling (LM), providing a principled mechanism to associate quantitative scores to sequences of words or tokens, has long been an interesting yet challenging problem in the field of speech and language processing. The n-gram model is still the predominant method, while a number of disparate LM methods, exploring either lexical co-occurrence or topic cues, have been developed to complement the n-gram model with some success. In this paper, we explore a novel language modeling framework built on top of the notion of relevance for speech recognition, where the relationship between a search history and the word being predicted is discovered through different granularities of semantic context for relevance modeling. Empirical experiments on a large vocabulary continuous speech recognition (LVCSR) task seem to demonstrate that the various language models deduced from our framework are very comparable to existing language models both in terms of perplexity and recognition error rate reductions.     

Cl-指示的石羊河流域地下水演化

化学示踪剂是研究干旱区地下水化学演化和补给来源追踪的有效手段之一。本文以Cl-为示踪剂,通过其他离子与Cl-的相互关系对石羊河流域地下水演化特征及影响因子进行分析:Br-/Cl-、Na+/Cl-、S042-/Cl-、HCO3-/Cl-、Ca2+/Cl-、Mg2+/Cl-相互关系指示了流域中游地区地下水与地表水补给关系密切,水质较好,水化学作用以溶滤为主,蒸发也起到一定作用,下游盆地地下水矿化度较高,不完全是现代降水的补给,石膏、方解石溶解和阳离子交换作用使得地下水富镁。总体而言,石羊河流域地下水演化在多种地球化学作用下进行,在以蒸发为主导动力的条件下,水岩相互作用和阳离子交换过程促使地下水演化为现代特征。