Papers by Herman ter Horst
Exergy Efficiency of Industrial Energy Use
Elsevier eBooks, 1982
The quality of demanded energy in industrial production in the Netherlands and in the Federal Rep... more The quality of demanded energy in industrial production in the Netherlands and in the Federal Republic of Germany (FRG) is compared with the quality of supplied energy. Neither enthalpy nor exergy can be used to characterize the energy system completely. Some aspects of optimising the use of energy in society are discussed.
Recommender Systems for TV
... Our long-term goal is implicit profiling. This entails a recommender system for TV to infer t... more ... Our long-term goal is implicit profiling. This entails a recommender system for TV to infer the user's profile purely from use of the TV set. ... For these reasons, we are initially focussing on cognitive filtering methods for a recommender system for TV. ...
Expert System For Test Structure Data Interpretation
The system described here first obtains, using control charts, a qualitative summary of the non-n... more The system described here first obtains, using control charts, a qualitative summary of the non-normal data in the test structure measurements, and then finds diagnoses of the process problems, using a qualitative causal knowledge model. In this paper the main concepts behind the system are summarised and results obtained with a prototype for an NMOS process are discussed.
arXiv (Cornell University), Jun 25, 2018
In this paper we study the prediction of heart rate from acceleration using a wrist worn wearable... more In this paper we study the prediction of heart rate from acceleration using a wrist worn wearable. Although existing photoplethysmography (PPG) heart rate sensors provide reliable measurements, they use considerably more energy than accelerometers and have a major impact on battery life of wearable devices. By using energy-efficient accelerometers to predict heart rate, significant energy savings can be made. Further, we are interested in understanding patient recovery after a heart rate intervention, where we expect a variation in heart rate over time. Therefore, we propose an online approach to tackle the concept drift as time passes. We evaluate the methods on approximately 4 weeks of free living data from three patients over a number of months. We show that our approach can achieve good predictive performance (e.g., 2.89 Mean Absolute Error) while using the PPG heart rate sensor infrequently (e.g., 20.25% of the samples).
Journal of Ambient Intelligence and Smart Environments, 2012
This paper presents an approach to structuring knowledge and reasoning for high-level interpretat... more This paper presents an approach to structuring knowledge and reasoning for high-level interpretation of sensor data in e.g. independent living applications. The main contribution is to use generalized events, described in terms of 'spacetime chunks', as a unifying and simplifying structuring principle. We use reasoning with ontologies and rules in combination with a database system, and also incorporate numerical computation. We show that an easy to use modeling formalism is obtained, and that reasoning is feasible at the time of service request, by using R-entailment, which enables efficient exploitation of ontologies and rules in the presence of RDF data. Two applications were built using the approach described in this paper, both of which are related to monitoring well-being of elderly people, and both of which use simple, low-cost sensors.
Extending the RDFS Entailment Lemma
Springer eBooks, 2004
We complement the RDF semantics specification of the W3C by proving decidability of RDFS entailme... more We complement the RDF semantics specification of the W3C by proving decidability of RDFS entailment. Furthermore, we show completeness and decidability of entailment for RDFS extended with datatypes and a property-related subset of OWL. The RDF semantics specification provides a complete set of entailment rules for reasoning with RDFS, but does not prove decidability of RDFS entailment: the closure graphs used in the completeness proof are infinite for finite RDF graphs. We define partial closure graphs, which can be taken to be finite for finite RDF graphs, which can be computed in polynomial time, and which are sufficient to decide RDFS entailment. We consider the extension of RDFS with datatypes and a property-related fragment of OWL: FunctionalProperty, InverseFunctionalProperty, sameAs, SymmetricProperty, TransitiveProperty, and inverseOf. In order to obtain a complete set of simple entailment rules, the semantics that we use for these extensions is in line with the ‘if-semantics’ of RDFS, and weaker than the ‘iff-semantics’ defining D-entailment and OWL (DL or Full) entailment. Classes can be used as instances, the use of FunctionalProperty and TransitiveProperty is not restricted to obtain decidability, and a partial closure that is sufficient for deciding entailment can be computed in polynomial time.
ABSTRACTBackgroundDue to the aging of the population, the prevalence of aortic valve stenosis wil... more ABSTRACTBackgroundDue to the aging of the population, the prevalence of aortic valve stenosis will increase dramatically in upcoming years. Consequently Transcatheter Aortic Valve Implantation (TAVI) procedures will also expand worldwide. Optimal selection of patients who benefit with improved symptoms and prognosis is key since TAVI is not without risk. Currently we are not able to adequately predict functional outcome after TAVI. Quality of life measurement tools and traditional functional assessment tests do not always agree and can depend on factors unrelated to heart disease. Activity tracking using wearable devices might provide a more comprehensive assessment.ObjectivesIdentify objective parameters from a wearable device (the Philips Health Watch) associated with improvement after TAVI for severe aortic stenosis.Methods and results100 patients undergoing routine TAVI wore a Philips Health Watch for one week before and after the procedure. Watch data were analyzed offline: 97 ...
System and method for predicting heart failure decompensation
The present disclosure pertains to a system configured to predict decompensation in a subject wit... more The present disclosure pertains to a system configured to predict decompensation in a subject with heart failure. The system comprises one or more hardware processors configured by machine-readable instructions to receive weight information, blood pressure information, and heart rate information about the subject; determine one or more weight parameters, one or more blood pressure parameters, and one or more heart rate parameters based on the received information; and predict decompensation in the subject based on the one or more weight parameters, the one or more blood pressure parameters, and the one or more heart rate parameters. Prior art systems use weight parameters alone for such prediction. However, weight parameters alone are often not predictive of decompensation
The purpose of this document is to identify requirements that are too general to result from any ... more The purpose of this document is to identify requirements that are too general to result from any single use case area, cut across all use cases areas, or are not directly related to the existing use cases, but nonetheless important. ... The following requirements are recommended by the group. ... Ontologies are publicly available and different data sources can commit to the same ontology for shared meaning. ... Any use case in which distributed data sources use shared terminology. ... Interoperability requires agreements on the definitions of terms. ...
Semantic Web Ontologies and Entailment: Complexity Aspects
Intelligent Algorithms in Ambient and Biomedical Computing
This chapter presents an overview of results relating to computational complex- ity of reasoning ... more This chapter presents an overview of results relating to computational complex- ity of reasoning with Semantic Web ontologies. An overview of the complete- ness results that form the basis for these complexity results is also given. We prove NP-completeness of two standard entailment relations, simple entailment and RDFS (RDF Schema) entailment. These two entailment relations are in P if the target graph is assumed to contain no variables (blank nodes). We show that these results also apply to two stronger entailment relations, D* entailment and pD* entailment, which extend RDFS entailment to reasoning with datatypes and to reasoning with a subset of OWL (the Web Ontology Language), respec- tively. These results make use of deductive closure graphs that can be computed in polynomial time. We present new bounds on the size of these closure graphs.
Interaction concepts for the ambient home
Lecture Notes in Computer Science, 2005
This paper extends the model theory of RDF with rules, placing an emphasis on integration with OW... more This paper extends the model theory of RDF with rules, placing an emphasis on integration with OWL and decidability of entailment. We start from an abstract syntax that views a rule as a pair of rule graphs which generalize RDF graphs by also allowing rule variables in subject, predicate and object positions. We include RDFS as well as a decidable part of OWL that weakens D-entailment and OWL Full. Classes can be used as instances. Almost all examples in the DAML set of test rules are covered by our approach. For a set of rules R, we define a general notion of R-entailment. Extending earlier results on RDFS and OWL, we prove a general completeness result for R-entailment. This result shows that a restricted form of application of rules that introduce blank nodes is sufficient to determine R-entailment. For rules that do not introduce blank nodes, we prove that R-entailment and R-consistency are decidable and in PSPACE. For rules that do not introduce blank nodes and that satisfy a bound on the size of rule bodies, we prove that R-consistency is in P, that R-entailment is in NP, and that R-entailment is in P if the target RDF graph is ground.
We present research questions associated with recommender systems for TV and an example of such a
This paper presents an approach to structuring knowledge and reasoning for high-level interpretat... more This paper presents an approach to structuring knowledge and reasoning for high-level interpretation of sensor data in e.g. independent living applications. The main contribution is to use generalized events, described in terms of ‘space-time chunks’, as a unifying and simplifying structuring principle. We use reasoning with ontologies and rules in combination with a database system, and also incorporate numerical computation. We show that an easy to use modeling formalism is obtained, and that reasoning is feasible at the time of service request, by using R-entailment, which enables efficient exploitation of ontologies and rules in the presence of RDF data. Two applications were built using the approach described in this paper, both of which are related to monitoring well-being of elderly people, and both of which use simple, low-cost sensors.
Exergy Efficiency of Industrial Energy Use
The quality of demanded energy in industrial production in the Netherlands and in the Federal Rep... more The quality of demanded energy in industrial production in the Netherlands and in the Federal Republic of Germany (FRG) is compared with the quality of supplied energy. Neither enthalpy nor exergy can be used to characterize the energy system completely. Some aspects of optimising the use of energy in society are discussed.
In this paper we study the prediction of heart rate from acceleration using a wrist worn wearable... more In this paper we study the prediction of heart rate from acceleration using a wrist worn wearable. Although existing photoplethysmography (PPG) heart rate sensors provide reliable measurements, they use considerably more energy than accelerometers and have a major impact on battery life of wearable devices. By using energy-efficient accelerometers to predict heart rate, significant energy savings can be made. Further, we are interested in understanding patient recovery after a heart rate intervention, where we expect a variation in heart rate over time. Therefore, we propose an online approach to tackle the concept as time passes. We evaluate the methods on approximately 4 weeks of free living data from three patients over a number of months. We show that our approach can achieve good predictive performance (e.g., 2.89 Mean Absolute Error) while using the PPG heart rate sensor infrequently (e.g., 20.25% of the samples).
npj Digital Medicine
Wrist-worn devices with heart rate monitoring have become increasingly popular. Although current ... more Wrist-worn devices with heart rate monitoring have become increasingly popular. Although current guidelines advise to consider clinical symptoms and exercise tolerance during decision-making in heart disease, it remains unknown to which extent wearables can help to determine such functional capacity measures. In clinical settings, the 6-minute walk test has become a standardized diagnostic and prognostic marker. We aimed to explore, whether 6-minute walk distances can be predicted by wrist-worn devices in patients with different stages of mitral and aortic valve disease. A total of n = 107 sensor datasets with 1,019,748 min of recordings were analysed. Based on heart rate recordings and literature information, activity levels were determined and compared to results from a 6-minute walk test. The percentage of time spent in moderate activity was a predictor for the achievement of gender, age and body mass index-specific 6-minute walk distances (p
Structuring reasoning for interpretation of sensor data in home-based health and well-being monitoring applications
Journal of Ambient Intelligence and Smart Environments
A Method for Organizing and Presenting the Structure of a Multimedia System and for Presenting This Structure to a Person Involved, in Particular a User Person or an Author Person, and a Software Package Having Such Organization and Presentation Facility
Recommender Systems for TV
Recsys, 1998
... Our long-term goal is implicit profiling. This entails a recommender system for TV to infer t... more ... Our long-term goal is implicit profiling. This entails a recommender system for TV to infer the user's profile purely from use of the TV set. ... For these reasons, we are initially focussing on cognitive filtering methods for a recommender system for TV. ...
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Papers by Herman ter Horst