4,007 research outputs found
Relational Approach to Knowledge Engineering for POMDP-based Assistance Systems as a Translation of a Psychological Model
Assistive systems for persons with cognitive disabilities (e.g. dementia) are
difficult to build due to the wide range of different approaches people can
take to accomplishing the same task, and the significant uncertainties that
arise from both the unpredictability of client's behaviours and from noise in
sensor readings. Partially observable Markov decision process (POMDP) models
have been used successfully as the reasoning engine behind such assistive
systems for small multi-step tasks such as hand washing. POMDP models are a
powerful, yet flexible framework for modelling assistance that can deal with
uncertainty and utility. Unfortunately, POMDPs usually require a very labour
intensive, manual procedure for their definition and construction. Our previous
work has described a knowledge driven method for automatically generating POMDP
activity recognition and context sensitive prompting systems for complex tasks.
We call the resulting POMDP a SNAP (SyNdetic Assistance Process). The
spreadsheet-like result of the analysis does not correspond to the POMDP model
directly and the translation to a formal POMDP representation is required. To
date, this translation had to be performed manually by a trained POMDP expert.
In this paper, we formalise and automate this translation process using a
probabilistic relational model (PRM) encoded in a relational database. We
demonstrate the method by eliciting three assistance tasks from non-experts. We
validate the resulting POMDP models using case-based simulations to show that
they are reasonable for the domains. We also show a complete case study of a
designer specifying one database, including an evaluation in a real-life
experiment with a human actor
A planning approach to the automated synthesis of template-based process models
The design-time specification of flexible processes can be time-consuming and error-prone, due to the high number of tasks involved and their context-dependent nature. Such processes frequently suffer from potential interference among their constituents, since resources are usually shared by the process participants and it is difficult to foresee all the potential tasks interactions in advance. Concurrent tasks may not be independent from each other (e.g., they could operate on the same data at the same time), resulting in incorrect outcomes. To tackle these issues, we propose an approach for the automated synthesis of a library of template-based process models that achieve goals in dynamic and partially specified environments. The approach is based on a declarative problem definition and partial-order planning algorithms for template generation. The resulting templates guarantee sound concurrency in the execution of their activities and are reusable in a variety of partially specified contextual environments. As running example, a disaster response scenario is given. The approach is backed by a formal model and has been tested in experiment
Constraint rule-based programming of norms for electronic institutions
Peer reviewedPostprin
Computer-aided HAZOP of batch processes
The modern batch chemical processing plants have a tendency of increasing
technological complexity and flexibility which make it difficult to control the
occurrence of accidents. Social and legal pressures have increased the demands
for verifying the safety of chemical plants during their design and operation.
Complete identification and accurate assessment of the hazard potential in the
early design stages is therefore very important so that preventative or protective
measures can be integrated into future design without adversely affecting
processing and control complexity or capital and operational costs. Hazard and
Operability Study (HAZOP) is a method of systematically identifying every
conceivable process deviation, its abnormal causes and adverse hazardous
consequences in the chemical plants. [Continues.
Invariant discovery and refinement plans for formal modelling in Event-B
The continuous growth of complex systems makes the development of correct software
increasingly challenging. In order to address this challenge, formal methods o er rigorous
mathematical techniques to model and verify the correctness of systems. Refinement
is one of these techniques. By allowing a developer to incrementally introduce design
details, refinement provides a powerful mechanism for mastering the complexities that
arise when formally modelling systems. Here the focus is on a posit-and-prove style of
refinement, where a design is developed as a series of abstract models introduced via
refinement steps. Each refinement step generates proof obligations which must be discharged
in order to verify its correctness – typically requiring a user to understand the
relationship between modelling and reasoning.
This thesis focuses on techniques to aid refinement-based formal modelling, specifically,
when a user requires guidance in order to overcome a failed refinement step. An integrated
approach has been followed: combining the complementary strengths of bottomup
theory formation, in which theories about domains are built based on basic background
information; and top-down planning, in which meta-level reasoning is used to guide the
search for correct models.
On the theory formation perspective, we developed a technique for the automatic discovery
of invariants. Refinement requires the definition of properties, called invariants,
which relate to the design. Formulating correct and meaningful invariants can be tedious
and a challenging task. A heuristic approach to the automatic discovery of invariants has
been developed building upon simulation, proof-failure analysis and automated theory
formation. This approach exploits the close interplay between modelling and reasoning
in order to provide systematic guidance in tailoring the search for invariants for a given
model.
On the planning perspective, we propose a new technique called refinement plans.
Refinement plans provide a basis for automatically generating modelling guidance when
a step fails but is close to a known pattern of refinement. This technique combines both
modelling and reasoning knowledge, and, contrary to traditional pattern techniques, allow
the analysis of failure and partial matching. Moreover, when the guidance is only partially
instantiated, and it is suitable, refinement plans provide specialised knowledge to further
tailor the theory formation process in an attempt to fully instantiate the guidance.
We also report on a series of experiments undertaken in order to evaluate the approaches
and on the implementation of both techniques into prototype tools. We believe
the techniques presented here allow the developer to focus on design decisions rather than
on analysing low-level proof failures
A Process Modelling Framework Based on Point Interval Temporal Logic with an Application to Modelling Patient Flows
This thesis considers an application of a temporal theory to describe and model the patient journey in the hospital accident and emergency (A&E) department. The aim is to introduce a generic but dynamic method applied to any setting, including healthcare. Constructing a consistent process model can be instrumental in streamlining healthcare issues. Current process modelling techniques used in healthcare such as flowcharts, unified modelling language activity diagram (UML AD), and business process modelling notation (BPMN) are intuitive and imprecise. They cannot fully capture the complexities of the types of activities and the full extent of temporal constraints to an extent where one could reason about the flows. Formal approaches such as Petri have also been reviewed to investigate their applicability to the healthcare domain to model processes.
Additionally, to schedule patient flows, current modelling standards do not offer any formal mechanism, so healthcare relies on critical path method (CPM) and program evaluation review technique (PERT), that also have limitations, i.e. finish-start barrier. It is imperative to specify the temporal constraints between the start and/or end of a process, e.g., the beginning of a process A precedes the start (or end) of a process B. However, these approaches failed to provide us with a mechanism for handling these temporal situations. If provided, a formal representation can assist in effective knowledge representation and quality enhancement concerning a process. Also, it would help in uncovering complexities of a system and assist in modelling it in a consistent way which is not possible with the existing modelling techniques.
The above issues are addressed in this thesis by proposing a framework that would provide a knowledge base to model patient flows for accurate representation based on point interval temporal logic (PITL) that treats point and interval as primitives. These objects would constitute the knowledge base for the formal description of a system. With the aid of the inference mechanism of the temporal theory presented here, exhaustive temporal constraints derived from the proposed axiomatic system’ components serves as a knowledge base.
The proposed methodological framework would adopt a model-theoretic approach in which a theory is developed and considered as a model while the corresponding instance is considered as its application. Using this approach would assist in identifying core components of the system and their precise operation representing a real-life domain deemed suitable to the process modelling issues specified in this thesis. Thus, I have evaluated the modelling standards for their most-used terminologies and constructs to identify their key components. It will also assist in the generalisation of the critical terms (of process modelling standards) based on their ontology. A set of generalised terms proposed would serve as an enumeration of the theory and subsume the core modelling elements of the process modelling standards. The catalogue presents a knowledge base for the business and healthcare domains, and its components are formally defined (semantics). Furthermore, a resolution theorem-proof is used to show the structural features of the theory (model) to establish it is sound and complete.
After establishing that the theory is sound and complete, the next step is to provide the instantiation of the theory. This is achieved by mapping the core components of the theory to their corresponding instances. Additionally, a formal graphical tool termed as point graph (PG) is used to visualise the cases of the proposed axiomatic system. PG facilitates in modelling, and scheduling patient flows and enables analysing existing models for possible inaccuracies and inconsistencies supported by a reasoning mechanism based on PITL. Following that, a transformation is developed to map the core modelling components of the standards into the extended PG (PG*) based on the semantics presented by the axiomatic system.
A real-life case (from the King’s College hospital accident and emergency (A&E) department’s trauma patient pathway) is considered to validate the framework. It is divided into three patient flows to depict the journey of a patient with significant trauma, arriving at A&E, undergoing a procedure and subsequently discharged. Their staff relied upon the UML-AD and BPMN to model the patient flows. An evaluation of their representation is presented to show the shortfalls of the modelling standards to model patient flows. The last step is to model these patient flows using the developed approach, which is supported by enhanced reasoning and scheduling
Computational approaches to shed light on molecular mechanisms in biological processes
Computational approaches based on Molecular Dynamics simulations, Quantum Mechanical methods and 3D Quantitative Structure-Activity Relationships were employed by computational chemistry groups at the University of Milano-Bicocca to study biological processes at the molecular level. The paper reports the methodologies adopted and the results obtained on Aryl hydrocarbon Receptor and homologous PAS proteins mechanisms, the properties of prion protein peptides, the reaction pathway of hydrogenase and peroxidase enzymes and the defibrillogenic activity of tetracyclines. © Springer-Verlag 2007
Design Ltd.: Renovated Myths for the Development of Socially Embedded Technologies
This paper argues that traditional and mainstream mythologies, which have
been continually told within the Information Technology domain among designers
and advocators of conceptual modelling since the 1960s in different fields of
computing sciences, could now be renovated or substituted in the mould of more
recent discourses about performativity, complexity and end-user creativity that
have been constructed across different fields in the meanwhile. In the paper,
it is submitted that these discourses could motivate IT professionals in
undertaking alternative approaches toward the co-construction of
socio-technical systems, i.e., social settings where humans cooperate to reach
common goals by means of mediating computational tools. The authors advocate
further discussion about and consolidation of some concepts in design research,
design practice and more generally Information Technology (IT) development,
like those of: task-artifact entanglement, universatility (sic) of End-User
Development (EUD) environments, bricolant/bricoleur end-user, logic of
bricolage, maieuta-designers (sic), and laissez-faire method to socio-technical
construction. Points backing these and similar concepts are made to promote
further discussion on the need to rethink the main assumptions underlying IT
design and development some fifty years later the coming of age of software and
modern IT in the organizational domain.Comment: This is the peer-unreviewed of a manuscript that is to appear in D.
Randall, K. Schmidt, & V. Wulf (Eds.), Designing Socially Embedded
Technologies: A European Challenge (2013, forthcoming) with the title
"Building Socially Embedded Technologies: Implications on Design" within an
EUSSET editorial initiative (www.eusset.eu/
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