Process mining: Discovering direct successors in process logs

Workflow management technology requires the existence of explicit process models, i.e. a completely specified workflow design needs to be developed in order to enact a given workflow process. Such a workflow design is time consuming and often subjective and incomplete. We propose a learning method that uses the workflow log, which contains information about the process as it is actually being executed. In our method we will use a logistic regression model to discover the direct connections between events of a realistic not complete workflow log with noise. Experimental results are used to show the usefulness and limitations of the presented method

Graduate recruitment at professional entry level: clinical judgements and empirically derived methods of selection

This research provides evidence to support the argument that selection procedures dependent upon clinical judgements, being used in the chartered accountancy profession, may well provide results not significantly different from those obtained by chance. Research has suggested that personality type, choice of vocation and performance are predictable from personal histories (Holland, 1976; Owens and Schoenfeldt, 1979; Eberhardt and Muchinsky, 1982a; Super, 1980; Wernimont and Campbell, 1968) and using a predictive model approach to scoring biographical data (biodata) is explored here as a means of improving the selection function. Part I of this study develops predictive models for scoring the biodata of applicants to the profession. An original contribution is made by carefully comparing two empirical model-building methodologies: the generally accepted, non-parametric, Weighted Application Blank technique and the parametric, logistic regression technique. The validity of both are explicitly tested using information from a sample of 23 training offices from 22 medium size chartered accountancy firms. The sample trainees were all non-accounting graduates entrants entering between 1985 and 1987 (N=665). Evidence is provided of the superiority of the results of the parametric models, in terms of true predictive validity. Relevant theory and the important implications of the results for related biodata studies generally are discussed. The result of applying the models to applicants, rather than recruits, is examined in a pilot study. An original approach to scoring applications is presented. Specifically developed software is provided to minimise both processing time and error margins. The biodata logit scores of the applicants and their likely success as trainees as indicated by that score, are compared with the firm's decision whether to accept or reject. Severe problems inherent in the judgemental approach to selection are revealed and the superior performance of the model-based approach demonstrated. Part II addresses the crucial issue of long term validation of biodata models by scoring a sample of recruits from 3 representative firms' 1988-90 entrants (N=323). The evidence does not support criticism of long term validity, as the logit models demonstrate effective performance, measured interms of the probability of correct classification, successfully predicting the criteria on those entering the profession up to 5 years after subjects used in model development. It is suggested that poor methodology may be responsible for excessive loss of validity over time in other studies and their lack of use of hard data. In addition, original evidence is provided to support the hypothesis of the generalizability of such models (i) across organizations and (ii) across samples significantly different from the development sample. This evidence suggests that, not only may the models be used to score applicants accounting firms of different sizes (and are therefore not organization-specific) but they may be used to score accounting graduates, who differ considerably from the original development sample (indicating that they, are not sample specific). The appropriateness of using these models in a manner similar to psychometric tests is considered. An assessment of approximate net profit associated with successful, failing or partially successful trainees is made. Accounting graduate trainees are more financially viable than non-accounting graduate

Real-time alpha emitter assay of large volumes

In this paper we discuss the design and behavior of a High Airflow Monitor (HAFM) based on Long-Range Alpha Detector (LRAD) technology [1]. The low air resistance construction of the HAFM enables the high airflow crucial for assay of rooms, vaults, or cargo vehicles. This is accomplished by orienting plates parallel to the airflow rather than perpendicular, as are the grids in other LRADS. As will be shown in this paper, the advantages of an LRAD-based volume monitor are its inexpensive simplicity, ruggedness, and its ability to detect contamination that is hidden from traditional alpha detection methods such as Geiger-Muller, gas cell, or solid-state detectors

Change Mining in Adaptive Process Management Systems

The wide-spread adoption of process-aware information systems has resulted in a bulk of computerized information about real-world processes. This data can be utilized for process performance analysis as well as for process improvement. In this context process mining offers promising perspectives. So far, existing mining techniques have been applied to operational processes, i.e., knowledge is extracted from execution logs (process discovery), or execution logs are compared with some a-priori process model (conformance checking). However, execution logs only constitute one kind of data gathered during process enactment. In particular, adaptive processes provide additional information about process changes (e.g., ad-hoc changes of single process instances) which can be used to enable organizational learning. In this paper we present an approach for mining change logs in adaptive process management systems. The change process discovered through process mining provides an aggregated overview of all changes that happened so far. This, in turn, can serve as basis for all kinds of process improvement actions, e.g., it may trigger process redesign or better control mechanisms

Development of an XSPEC-Based Spectral Analysis System for the Coded-Aperture Hard X-ray Balloon Payload EXITE2

We present the spectral analysis system for the second-generation Energetic X-ray Imaging Telescope Experiment (EXITE2) balloon payload. EXITE2 is an imaging hard X-ray telescope using a coded-aperture mask and a NaI/CsI phoswich detector operating in the energy range 20--600 keV. The instrument was flown on a high-altitude scientific balloon from Ft. Sumner, NM on 1997 May 7-8. We describe the details of the EXITE2 spectral analysis system, with emphasis on those aspects peculiar to coded-aperture instruments. In particular, we have made our analysis compatible with the standard X-ray spectral fitting package XSPEC by generating a response matrix in the appropriate format including all the effects of a coded-aperture system. The use of XSPEC, which may be a first for coded-aperture data, permits great flexibility in the fitting of spectral models. The additional effects of our phoswich system, or any other detector-specific considerations, may be easily included as well. We test our spectral analysis using observations of the Crab Nebula, and find that the EXITE2 Crab spectrum is consistent with those recorded by previous instruments operating in this energy range.Comment: 17 pages LaTeX, 6 figures, accepted to Astroparticle Physic

Localization dynamics in a binary two-dimensional cellular automaton: the Diffusion Rule

We study a two-dimensional cellular automaton (CA), called Diffusion Rule (DR), which exhibits diffusion-like dynamics of propagating patterns. In computational experiments we discover a wide range of mobile and stationary localizations (gliders, oscillators, glider guns, puffer trains, etc), analyze spatio-temporal dynamics of collisions between localizations, and discuss possible applications in unconventional computing.Comment: Accepted to Journal of Cellular Automat

Explosive events - swirling transition region jets

In this paper, we extend our earlier work to provide additional evidence for an alternative scenario to explain the nature of so-called `explosive events'. The bi-directed, fast Doppler motion of explosive events observed spectroscopically in the transition region emission is classically interpreted as a pair of bidirectional jets moving upward and downward from a reconnection site. We discuss the problems of such a model. In our previous work, we focused basically on the discrepancy of fast Doppler motion without detectable motion in the image plane. We now suggest an alternative scenario for the explosive events, based on our observations of spectral line tilts and bifurcated structure in some events. Both features are indicative of rotational motion in narrow structures. We explain the bifurcation as the result of rotation of hollow cylindrical structures and demonstrate that such a sheath model can also be applied to explain the nature of the puzzling `explosive events'. We find that the spectral tilt, the lack of apparent motion, the bifurcation, and a rapidly growing number of direct observations support an alternative scenario of linear, spicular-sized jets with a strong spinning motion.Comment: 9 pages, 3 figures, accepted for publication in Solar Physic