King's College, Aberdeen

About: King's College, Aberdeen is a based out in . It is known for research contribution in the topics: Poison control & Sedimentary depositional environment. The organization has 712 authors who have published 918 publications receiving 25421 citations. The organization is also known as: King's College, Aberdeen & The University and King's College of Aberdeen.

Variable selection and the interpretation of principal subspaces

Abstract: Principal component analysis is widely used in the analysis of multivariate data in the agricultural, biological, and environmental sciences. The first few principal components (PCs) of a set of variables are derived variables with optimal properties in terms of approximating the original variables. This paper considers the problem of identifying subsets of variables that best approximate the full set of variables or their first few PCs, thus stressing dimensionality reduction in terms of the original variables rather than in terms of derived variables (PCs) whose definition requires all the original variables. Criteria for selecting variables are often ill defined and may produce inappropriate subsets. Indicators of the performance of different subsets of the variables are discussed and two criteria are defined. These criteria are used in stepwise selection-type algorithms to choose good subsets. Examples are given that show, among other things, that the selection of variable subsets should not be based only on the PC loadings of the variables.

Incident Command Skills in the Management of an Oil Industry Drilling Incident: a Case Study

Abstract: The successful management of a complex, hazardous event in many domains demands a high level of incident command skills. In the oil and gas exploration and production industry, these skills were required by members of an Incident Management Team (IMT) established to respond the failure of a drilling riser in the Gulf of Mexico. When an incident occurs, members of an industrial IMT form an interdisciplinary, interdependent, but ad-hoc team. As actual experience of dealing with major incidents of this nature is relatively rare, IMT members have to rely on emergency exercises in training, along with existing domain-specific knowledge. Following a serious incident on an offshore drilling rig, semi-structured interviews with the on-shore strategic and tactical level IMT members (n=7) were conducted. These interviews have resulted in the identification and definition of incident command skills for members of an industrial IMT, namely decision making, situation awareness, communication, leadership, and teamwork, all of which can be affected by stress, as well as organisational factors that influenced the outcome of the incident. Limitations in current incident management training were identified, namely the need for specific incident command skills training. A framework is suggested around which specific incident command skills training can be structured. Key learnings from this case study are also presented which can provide guidance for the training and preparation of industrial incident management teams.

Stratifying modular representations of finite groups

Abstract: We classify localising subcategories of the stable module category of a finite group that are closed under tensor product with simple (or, equivalently all) modules. One application is a proof of the telescope conjecture in this context. Others include new proofs of the tensor product theorem and of the classification of thick subcategories of the finitely generated modules which avoid the use of cyclic shifted subgroups. Along the way we establish similar classifications for differential graded modules over graded polynomial rings, and over graded exterior algebras.

Experimental Study of a Symmetrical Piecewise Base-Excited Oscillator

Abstract: This paper presents an experimental study on a base-excited piecewise linear oscillator with symmetrical flexible constrains of high stiffness ratio (above 20). The details of the adopted design of the oscillator, the experimental set-up, and calibration procedure are briefly discussed. The regions of chaotic motion predicted theoretically were confirmed by the experimental results arranged into bifurcation diagram Clearance, stiffness ratio, amplitude, and frequency of the external force were used as branching parameters. The discussion of the system dynamics is based on bifurcation diagrams and Lissajous curves. The investigated system tends to be periodic for large clearances and chaotic for small ones. This picture is reversed for the amplitude of the forcing change where periodic motion occurred for small values and chaos dominated for larger forcing. The same behavior is observed for increasing frequency ratio where, for values below the natural frequency, the most interesting dynamics occurs. For the investigated parameter values, the stiffness ratio variation produces only periodic motion.