The structure of problem-solving knowledge and the structure of organisations

This work presents a model of organisational problem solving able to account for the relationships between problem complexity, tasks decentralilzation and problem solving efficiency. Whenever problem solving requires the coordination of a multiplicity of interdependent elements, the varying degrees of decentralization of cognitive and operational tasks shape the solution which can be generated, tested and selected. Suboptimality and path-dependence are shown to be ubiquitous features of organisational problem solving. At the same time, the model allows a precise exploration of the possible trade-offs between decompostion patterns and search efficiency involved in different organisational architectures.-

Minkowski Sum Construction and other Applications of Arrangements of Geodesic Arcs on the Sphere

We present two exact implementations of efficient output-sensitive algorithms that compute Minkowski sums of two convex polyhedra in 3D. We do not assume general position. Namely, we handle degenerate input, and produce exact results. We provide a tight bound on the exact maximum complexity of Minkowski sums of polytopes in 3D in terms of the number of facets of the summand polytopes. The algorithms employ variants of a data structure that represents arrangements embedded on two-dimensional parametric surfaces in 3D, and they make use of many operations applied to arrangements in these representations. We have developed software components that support the arrangement data-structure variants and the operations applied to them. These software components are generic, as they can be instantiated with any number type. However, our algorithms require only (exact) rational arithmetic. These software components together with exact rational-arithmetic enable a robust, efficient, and elegant implementation of the Minkowski-sum constructions and the related applications. These software components are provided through a package of the Computational Geometry Algorithm Library (CGAL) called Arrangement_on_surface_2. We also present exact implementations of other applications that exploit arrangements of arcs of great circles embedded on the sphere. We use them as basic blocks in an exact implementation of an efficient algorithm that partitions an assembly of polyhedra in 3D with two hands using infinite translations. This application distinctly shows the importance of exact computation, as imprecise computation might result with dismissal of valid partitioning-motions.Comment: A Ph.D. thesis carried out at the Tel-Aviv university. 134 pages long. The advisor was Prof. Dan Halperi

Analytic Performance Modeling and Analysis of Detailed Neuron Simulations

Big science initiatives are trying to reconstruct and model the brain by attempting to simulate brain tissue at larger scales and with increasingly more biological detail than previously thought possible. The exponential growth of parallel computer performance has been supporting these developments, and at the same time maintainers of neuroscientific simulation code have strived to optimally and efficiently exploit new hardware features. Current state of the art software for the simulation of biological networks has so far been developed using performance engineering practices, but a thorough analysis and modeling of the computational and performance characteristics, especially in the case of morphologically detailed neuron simulations, is lacking. Other computational sciences have successfully used analytic performance engineering and modeling methods to gain insight on the computational properties of simulation kernels, aid developers in performance optimizations and eventually drive co-design efforts, but to our knowledge a model-based performance analysis of neuron simulations has not yet been conducted. We present a detailed study of the shared-memory performance of morphologically detailed neuron simulations based on the Execution-Cache-Memory (ECM) performance model. We demonstrate that this model can deliver accurate predictions of the runtime of almost all the kernels that constitute the neuron models under investigation. The gained insight is used to identify the main governing mechanisms underlying performance bottlenecks in the simulation. The implications of this analysis on the optimization of neural simulation software and eventually co-design of future hardware architectures are discussed. In this sense, our work represents a valuable conceptual and quantitative contribution to understanding the performance properties of biological networks simulations.Comment: 18 pages, 6 figures, 15 table

TOWARDS INSTITUTIONAL INFRASTRUCTURES FOR E-SCIENCE: The Scope of the Challenge

The three-fold purpose of this Report to the Joint Information Systems Committee (JISC) of the Research Councils (UK) is to: • articulate the nature and significance of the non-technological issues that will bear on the practical effectiveness of the hardware and software infrastructures that are being created to enable collaborations in e- Science; • characterise succinctly the fundamental sources of the organisational and institutional challenges that need to be addressed in regard to defining terms, rights and responsibilities of the collaborating parties, and to illustrate these by reference to the limited experience gained to date in regard to intellectual property, liability, privacy, and security and competition policy issues affecting scientific research organisations; and • propose approaches for arriving at institutional mechanisms whose establishment would generate workable, specific arrangements facilitating collaboration in e-Science; and, that also might serve to meet similar needs in other spheres such as e- Learning, e-Government, e-Commerce, e-Healthcare. In carrying out these tasks, the report examines developments in enhanced computer-mediated telecommunication networks and digital information technologies, and recent advances in technologies of collaboration. It considers the economic and legal aspects of scientific collaboration, with attention to interactions between formal contracting and 'private ordering' arrangements that rest upon research community norms. It offers definitions of e-Science, virtual laboratories, collaboratories, and develops a taxonomy of collaborative e-Science activities which is implemented to classify British e-Science pilot projects and contrast these with US collaboratory projects funded during the 1990s. The approach to facilitating inter-organizational participation in collaborative projects rests upon the development of a modular structure of contractual clauses that permit flexibility and experience-based learning.

Partial-Matching and Hausdorff RMS Distance Under Translation: Combinatorics and Algorithms

We consider the RMS distance (sum of squared distances between pairs of points) under translation between two point sets in the plane, in two different setups. In the partial-matching setup, each point in the smaller set is matched to a distinct point in the bigger set. Although the problem is not known to be polynomial, we establish several structural properties of the underlying subdivision of the plane and derive improved bounds on its complexity. These results lead to the best known algorithm for finding a translation for which the partial-matching RMS distance between the point sets is minimized. In addition, we show how to compute a local minimum of the partial-matching RMS distance under translation, in polynomial time. In the Hausdorff setup, each point is paired to its nearest neighbor in the other set. We develop algorithms for finding a local minimum of the Hausdorff RMS distance in nearly linear time on the line, and in nearly quadratic time in the plane. These improve substantially the worst-case behavior of the popular ICP heuristics for solving this problem.Comment: 31 pages, 6 figure

Parallel machine scheduling subject to machine availability constraints

Cataloged from PDF version of article.Within a planning horizon, machines may become unavailable due to unexpected breakdowns or pre-scheduled activities. A realistic approach in constructing the production schedule should explicitly take into account such periods of unavailability. This study addresses the parallel machine-scheduling problem subject to availability constraints on each machine. The objectives of minimizing the total completion time and minimizing the maximum completion time are studied. The problems with both objectives are known to be NP-hard. We develop an exact branch-and-bound procedure and propose three heuristic algorithms for the total completion time problem. Similarly, we propose exact and approximation algorithms also for the maximum completion time problem. All proposed algorithms are tested through extensive computational experimentation, and several insights are provided based on computational results.Sevindik, KayaM.S

Optimal regulatory design for the Central Bank of Russia

The Central Bank of Russia (CBR) assumes a wide range of functions not raditional to a central bank. In addition to the daily conduct of monetary policy, it acts as a regulator and supervisor of the banking sector. It is currently overssing the implementation of a deposit insurance scheme and is the main owner of Russia's largest commercial bank, Sberbank. As this additional functions may conflict with the CBR policy objectives, I review how the current design of the CBR deviates from the optimal allocation of regulatory powers within a central bank prescribed in the literature. I then empirically investigate the need for a supervisory body within the CBR. Using a simple Taylor rule framework I find that the CBR does not use its "hands-on" supervisory information to maintain financial stability, but rather to accomodate state-owned banks' balances.Central Bank; Prudential Regulation and Supervision; Monetary Policy Rules; Russia

Development of flood disaster preparedness activity (FDPA) items: a preliminary study using Rasch analysis

Introduction: Not only does flood affects the household community, but it also has an impact on business entities, particularly small and medium enterprises (SMEs) located in flood-prone areas. In order to assist SMEs to prepare for a flood disaster effectively, the set-up of a disaster preparedness plan is essential. The purpose of this study is to develop a validated instrument for identifying the different levels of disaster preparedness among SMEs in their readiness to face a flood disaster. Methods: In this preliminary study, 26 items of flood disaster preparedness activities (FDPA) reviewed from works of literature were adopted and adapted to be randomly administered to 30 respondents (SME business owners) located in the Temerloh province, Malaysia, which is identified as a flood-prone area. A Rasch analysis technique was used to identify the psychometric properties of the instrument. Results: Using the Rasch measurement analysis technique, the instrument used was able to categorise the SMEs into two level of preparedness: low and moderate. About 25 items were found to possess good psychometric features in determining the flood preparedness level of SMEs despite the lack of items on measuring high-level preparedness activities. Conclusion: The results of this preliminary study have served to highlight the strength of the instrument and gaps identified for further improvement in the near future

Resilient architecture (preliminary version)

The main objectives of WP2 are to define a resilient architecture and to develop a range of middleware solutions (i.e. algorithms, protocols, services) for resilience to be applied in the design of highly available, reliable and trustworthy networking solutions. This is the first deliverable within this work package, a preliminary version of the resilient architecture. The deliverable builds on previous results from WP1, the definition of a set of applications and use cases, and provides a perspective of the middleware services that are considered fundamental to address the dependability requirements of those applications. Then it also describes the architectural organisation of these services, according to a number of factors like their purpose, their function within the communication stack or their criticality/specificity for resilience. WP2 proposes an architecture that differentiates between two classes of services, a class including timeliness and trustworthiness oracles, and a class of so called complex services. The resulting architecture is referred to as a "hybrid architecture". The hybrid architecture is motivated and discussed in this document. The services considered within each of the service classes of the hybrid architecture are described. This sets the background for the work to be carried on in the scope of tasks 2.2 and 2.3 of the work package. Finally, the deliverable also considers high-level interfacing aspects, by providing a discussion about the possibility of using existing Service Availability Forum standard interfaces within HIDENETS, in particular discussing possibly necessary extensions to those interfaces in order to accommodate specific HIDENETS services suited for ad-hoc domain