A topic model approach to measuring interdisciplinarity at the National Science Foundation

As the National Science Foundation (NSF) implements new cross-cutting initiatives and programs, interest in assessing the success of these experiments in fostering interdisciplinarity grows. A primary challenge in measuring interdisciplinarity is identifying and bounding the discrete disciplines that comprise interdisciplinary work. Using statistical text-mining techniques to extract topic bins, the NSF recently developed a topic map of all of their awards issued between 2000 and 2011. These new data provide a novel means for measuring interdisciplinarity by assessing the language or content of award proposals. Using the Directorate for Social, Behavioral, and Economic Sciences as a case study and drawing on the new topic model of the NSF’s awards, this paper explores new methods for quantifying interdisciplinarity in the NSF portfolio.     

Fuzzy geometric programming approach to a fuzzy machining economics model

Machining economics is an important function of the process planning activity for manufacturing products with high quality and low cost. The machining economics model usually contains a highly non-linear objective function and equations that could be formulated as a geometric programming problem. The paper develops a solution method for deriving the fuzzy objective value of the fuzzy machining economics problem when some of the parameters in the problem are fuzzy numbers. A pair of geometric programs is formulated to calculate the lower and upper bounds of the unit production cost at possibility level α. With the ability to calculate the fuzzy objective value developed, it might help lead to a more realistic modelling effort. The developed methodology can also be applied to other engineering design problems with fuzzy numbers.     

A scientific approach to engineering design

Current developments of a scientific approach to design are outlined. It is shown than in order to establish a scientific theory of design, the following aspects need to be studied and covered: the designer, the activity, the object, the context in which engineering design takes place, and the context of use of the resulting technical system. The current state of such theory is presented, together with discussions of related literature. Design science is brought into connection with necessary development of computer aids.     

A new model of scientific colloboration part 1. Theoretical approach

This study deals with the uniformity of the collaboration process within the scientist's system by describing all two-dimensional and three-dimensional referential patterns with only one nonliear function. The variety of these patterns is expressed in dependence upon the conditions or environment that induced them by means of varying the parameters of this non-linear function. Based on their similarity these various patterns can be divided into different types.     

A bibliometric approach to tracking international scientific migration

A bibliometric approach is explored to tracking international scientific migration, based on an analysis of the affiliation countries of authors publishing in peer reviewed journals indexed in Scopus?. The paper introduces a model that relates base concepts in the study of migration to bibliometric constructs, and discusses the potentialities and limitations of a bibliometric approach both with respect to data accuracy and interpretation. Synchronous and asynchronous analyses are presented for 10 rapidly growing countries and 7 scientifically established countries. Rough error rates of the proposed indicators are estimated. It is concluded that the bibliometric approach is promising provided that its outcomes are interpreted with care, based on insight into the limits and potentialities of the approach, and combined with complementary data, obtained, for instance, from researchers’ Curricula Vitae o, survey or questionnaire- based data. Error rates for units of assessment with indicator values based on sufficiently large numbers are estimated to be fairly below 10 %, but can be expected to vary substantially among countries of origin, especially between Asian countries and Western countries.     

A thermodynamic approach to selecting a number of clusters based on topic modeling

A thermodynamic approach has been applied to solving the problem of selecting the number of clusters/topics in topic modeling. The main principles of this approach are formulated and the behavior of topic models during temperature variations is studied. Using thermodynamic formalism, the existence of the entropy phase transition in topic models is shown and criteria for the choice of optimum number of clusters/ topics are determined.

     

A distributional approach to multinationality measures of international scientific collaboration

In a recent study, de Lange and Glänzel introduced a model for the bibliometric analysis of the extent of multinational co-authorship links. They showed that this model can be considered a generalisation of the "fractionation approach" by Nederhof and Moed. The authors analysed international collaboration links (the Multilateral Collaboration Index) as a function of the share of internationally co-authored papers. The measurement of the deviation of individual countries from (sub-)field peculiarities proved, however, complicated. The intensifying international collaboration and, in several fields, the substantial growth of number of multinational papers (involving three or more countries) in the 90s necessitates a detailed analysis of co-publication distributions, that is, of the distributions of partner countries in a given country"s publication output. The main objective of the study is to elaborate such a measure to be used in addition to the share of international publications and the Multilateral Collaboration Index. In addition, a detailed analysis of national citation impact of domestic, bilateral and multilateral papers in the major science fields is conducted. The model, we develop and the statistical analysis that it allows, support the practical conclusion that the ratio of the number of international links and international papers turns out to be roughly proportional to the ratio of full and fractional publication counts.     

A geometric approach to the construction of scientific impact indices

Two broad classes of scientific impact indices are proposed and their properties - both theoretical and practical — are discussed. These new classes were obtained as a geometric generalization of the well-known tools applied in scientometric, like Hirsch’s h-index, Woeginger’s w-index and the Kosmulski’s Maxprod. It is shown how to apply the suggested indices for estimation of the shape of the citation function or the total number of citations of an individual. Additionally, a new efficient and simple O(log n) algorithm for computing the h-index is given.     

A physical approach to structural stochastic optimal controls

The generalized density evolution equation proposed in recent years profoundly reveals the intrinsic connection between deterministic systems and stochastic systems by introducing physical relationships into stochastic systems. On this basis, a physical stochastic optimal control scheme of structures is developed in this paper, which extends the classical stochastic optimal control methods, and can govern the evolution details of system performance, while the classical stochastic optimal control schemes, such as the LQG control, essentially hold the system statistics since there is still a lack of efficient methods to solve the response process of the stochastic systems with strong nonlinearities in the context of classical random mechanics. It is practically useful to general nonlinear systems driven by non-stationary and non-Gaussian stochastic processes. The celebrated Pontryagin’s maximum principles is employed to conduct the physical solutions of the state vector and the control force vector of stochastic optimal controls of closed-loop systems by synthesizing deterministic optimal control solutions of a collection of representative excitation driven systems using the generalized density evolution equation. Further, the selection strategy of weighting matrices of stochastic optimal controls is discussed to construct optimal control policies based on a control criterion of system second-order statistics assessment. The stochastic optimal control of an active tension control system is investigated, subjected to the random ground motion represented by a physical stochastic earthquake model. The investigation reveals that the structural seismic performance is significantly improved when the optimal control strategy is applied. A comparative study, meanwhile, between the advocated method and the LQG control is carried out, indicating that the LQG control using nominal Gaussian white noise as the external excitation cannot be used to design a reasonable control system for civil engineering structures, while the advocated method can reach the desirable objective performance. The optimal control strategy is then further employed in the investigation of the stochastic optimal control of an eight-storey shear frame. Numerical examples elucidate the validity and applicability of the developed physical stochastic optimal control methodology.     

Some incentives and contraints of scientific performance in economics

Spangenberg, et al. have tested hypotheses concerning' facilitators and inhibitors of scientific performance in Dutch economics. In order to examine the external validity of the findings, a comparison is made with large scale empirical studies conducted in two other countries. In order to examine the convergent validity of the overall performance measure, the relationship with other scientometric indicators is inspected. In order to test the robustness of their univariate and multivariate tests, multiple regressions were performed on three criteria: scientific productivity, citation impact, and individual performance index.     

Validation of scientific topic models using graph analysis and corpus metadata

Probabilistic topic modeling algorithms like Latent Dirichlet Allocation (LDA) have become powerful tools for the analysis of large collections of documents (such as papers, projects, or funding applications) in science, technology an innovation (STI) policy design and monitoring. However, selecting an appropriate and stable topic model for a specific application (by adjusting the hyperparameters of the algorithm) is not a trivial problem. Common validation metrics like coherence or perplexity, which are focused on the quality of topics, are not a good fit in applications where the quality of the document similarity relations inferred from the topic model is especially relevant. Relying on graph analysis techniques, the aim of our work is to state a new methodology for the selection of hyperparameters which is specifically oriented to optimize the similarity metrics emanating from the topic model. In order to do this, we propose two graph metrics: the first measures the variability of the similarity graphs that result from different runs of the algorithm for a fixed value of the hyperparameters, while the second metric measures the alignment between the graph derived from the LDA model and another obtained using metadata available for the corresponding corpus. Through experiments on various corpora related to STI, it is shown that the proposed metrics provide relevant indicators to select the number of topics and build persistent topic models that are consistent with the metadata. Their use, which can be extended to other topic models beyond LDA, could facilitate the systematic adoption of this kind of techniques in STI policy analysis and design.

     

结构时域识别的超单元法

在实际应用中 ,传感器数目通常远远小于结构模型自由度的数目。而为了实现识别结果的唯一性 ,一般的时域识别方法要求测量信息是完备的。由于超单元法的分散识别能力 ,使得该方法可以在传感器数目有限的情况下实现大型结构的识别。首先建立了超单元模型 ,其次提出了对超单元模型进行参数化的方法 ,针对结构识别中的荷载未知问题对超单元的划分进行了讨论。最后用大型结构的识别算例对整体识别方法和超单元识别方法进行了比较。结果表明 :超单元法不但可以在传感器数目有限的情况下实现结构参数的完整识别 ,而且其识别效率远远高于一次完成型算法。     

A unified parametric design approach to structural shape optimization

This paper presents a general parametric design approach for 2-D shape optimization problems. This approach has been achieved by integrating practical design methodologies into numerical procedures. It is characterized by three features: (i) automatic selection of a minimum number of shape design variables based on the CAD geometric model; (ii) integration of sequential convex programming algorithms to solve equality constrained optimization problems; (iii) efficient sensitivity analysis by means of the improved semi-analytical method. It is shown that shape design variables can be either manually or systematically identified with the help of equality constraints describing the relationship between geometric entities. Numerical solutions are performed to demonstrate the applicability of the proposed approach. A discussion of the results is also given:     

A structural approach to the calculation of j

The calculation of the elastic-plastic fracture parameter, J, is often assumed to demand finite element analysis, particularly when the loads applied are secondary, or partly secondary, in nature, e.g. thermal load. However, it is shown that a simple technique based on the reference stress approach can be used to calculate J even in these cases. Example results are given, and compare well with finite element solutions.     

A bibliometric approach to the role of author self-citations in scientific communication

The present paper analyses the role of author self-citations aiming at finding basic regularities of self-citations within the process of documented scientific communication and thus laying the methodological groundwork for a possible critical view at self-citation patterns in empirical studies at any level of aggregation. The study consists of three parts; the first part of the study is concerned with the comparative analysis of the ageing of self-citations and of non-self citations, in the second part the possible interdependence between self-citations and foreign citations is analysed and in the third part the interrelation of the share of self-citations in all citations with other citation-based indicators is studied. The outcomes of this study are two-fold; first, the results characterise author self-citations - at least at the macro level - as an organic part of the citation process obeying rules that can be measured and described with the help of mathematical models. Second, these rules can be used in evaluative micro and meso analyses to identify significant deviations from the reference standards.     

Some incentives and constraints of scientific performance in departments of economics

The main purpose of this paper is to explore why publication records differ among Dutch departments of economics. The results of a large scale performance evaluations have been used for classifying research units in subsamples of high and low performers. After collecting data on organizational characteristics of economics research units, univariate and multivariate statistics have been applied to test hypotheses regarding determinants of scientific productivity in economics. “The extreme clannishness, not to say xenophobia, of the Econ makes life among them difficult and perhaps even somewhat dangerous for the outsider. This probably accounts for the fact that the Econ have so far not been systematically studied (...) More research on this interesting tribe is badly needed”.     

A structural approach to assessing postponement strategies: construct development and validation

This paper endeavours to introduce and validate constructs and measured variables for postponement strategies. Although empirical researchers have examined postponement, a consistent set of valid, reliable factors has not been developed and used. The lack of valid constructs is a barrier to hypothesis testing and meta-analysis on postponement. Using confirmatory factor analysis (CFA), the validity and reliability of the proposed postponement constructs are examined. This is performed through a pilot study and a large scale survey on a sample of 219 manufacturing firms which represent a wide range of manufacturing operations. The outcomes of this paper establish a set of variables which can measure shipment, manufacturing, purchasing and design postponements.