Blind source separation using temporal predictability

A measure of temporal predictability is defined and used to separate linear mixtures of signals. Given any set of statistically independent source signals, it is conjectured here that a linear mixture of those signals has the following property: the temporal predictability of any signal mixture is less than (or equal to) that of any of its component source signals. It is shown that this property can be used to recover source signals from a set of linear mixtures of those signals by finding an un-mixing matrix that maximizes a measure of temporal predictability for each recovered signal. This matrix is obtained as the solution to a generalized eigenvalue problem; such problems have scaling characteristics of O (N3), where N is the number of signal mixtures. In contrast to independent component analysis, the temporal predictability method requires minimal assumptions regarding the probability density functions of source signals. It is demonstrated that the method can separate signal mixtures in which each mixture is a linear combination of source signals with supergaussian, sub-gaussian, and gaussian probability density functions and on mixtures of voices and music

The ICD in heart failure - time for a rethink?

No abstract available

Feature-based and Model-based Semantics for English, French and German Verb Phrases

This paper considers the relative merits of using features and formal event models to characterise the semantics of English, French and German verb phrases, and con- siders the application of such semantics in machine translation. The feature-based ap- proach represents the semantics in terms of feature systems, which have been widely used in computational linguistics for representing complex syntactic structures. The paper shows how a simple intuitive semantics of verb phrases may be encoded as a feature system, and how this can be used to support modular construction of au- tomatic translation systems through feature look-up tables. This is illustrated by automated translation of English into either French or German. The paper contin- ues to formalise the feature-based approach via a model-based, Montague semantics, which extends previous work on the semantics of English verb phrases. In so doing, repercussions of and to this framework in conducting a contrastive semantic study are considered. The model-based approach also promises to provide support for a more sophisticated approach to translation through logical proof; the paper indicates further work required for the fulfilment of this promise

NITROGEN DYNAMICS IN THE RUMEN AND ABOMASUM OF SHEEP DETERMINED WITH 15 N-LABELLED AMMONIA OR 15 N-LABELLED DUCKWEED

An experiment was carried out to investigate the dynamics of nitrogen (N) in the rumen and abomasum of rumen and abomasum-cannulated sheep using 15 N dilution techniques. The 15 N tracer was administered into the rumen as 15 N-ammonia or 15 N-labelled duckweed and the transfer of the 15 N label to various N pools was followed. Flow of digesta from the rumen into the abomasum was ascertained by double marker technique with cobalt and acid insoluble ash as liquid digesta and particle digesta marker, respectively. Results showed that the average of rumen water volume was 4.5 l ± SEM 0.57 and the mean water flow through the abomasum (8.6 ± 0.45 l/d) was higher than outflow from the rumen (7.4 ± 0.55 l/d). Nitrogen intake tended to be higher, but total-N passing the abomasum tended to be lower when the sheep were infused by 15 N-ammonia than when they were ingesting 15 N-duckweed. The ammonia concentration in abomasal digesta was about 93 mg N/kg and non ammonia N (NAN) was about 1.58 g N/kg. The rates of flow of total-N as ammonia-N and as NAN did not differ (P>0.05) between animals or diets, with means (± SEM) of 57.7 ± 0.96 and 964 ± 2.13 mmol/d (or 0.81 and 13.5 g N/d), respectively. About 34-59% of the dietary N was removed from the rumen as ammonia (absorbed and in digesta). The enrichments of rumen ammonia N appeared to have reached plateau values after about 10 h of 15 N-ammonia infusion. The percentage of bacterial-N derived from ammonia-N (from the period of 15 N-ammonia infusion) was 53.63 % (ratio of plateau enrichments) and thus 37.47% of bacterial-N was derived from NAN sources in the rumen. The total 15 N flow through the abomasum was higher (P<0.001) when 5 N duckweed was given rather than 15 N-ammonia (2.40 0.02 mmol/d). The 15 N in NAN flowing to the abomasum (mmol/d) was also significantly higher (P<0.001) when 15 N-duckweed was given rather than 15 N ammonia, with means of 0.00, respectively. The flow of 15 N in ammonia, on the other hand, was lower (P<0.01) when sheep ingested 15 N-duckweed than when they were infused with 15 N-ammonia (0.09  0.00v. 0.13  0.09  mmol/d).Damry 1 Keywords : Nitrogen Dynamics, Rumen, Ammonia-N, Bacterial-

Complexity Theory and the Operational Structure of Algebraic Programming Systems

An algebraic programming system is a language built from a fixed algebraic data abstraction and a selection of deterministic, and non-deterministic, assignment and control constructs. First, we give a detailed analysis of the operational structure of an algebraic data type, one which is designed to classify programming systems in terms of the complexity of their implementations. Secondly, we test our operational description by comparing the computations in deterministic and non-deterministic programming systems under certain space and time restrictions

Exploring the relationships among bio-physical and socio-cultural ecosystem services of agroforestry systems across Europe

N/

An Evaluation of Heat Exchangers Using System Information and PEC

This report describes analyses aimed at integrating component optimization and system design by developing heat-exchanger performance evaluation criteria (PEC) that account for the system-level performance impacts of heat exchanger design. It builds on earlier studies that used relatively simple PEC to capture some of the component-level tradeoffs, but which usually ignore the system impact of component design. This report evaluates four PEC-j/f, heat transfer/pumping power (8), heat transfer/(pumping + compressor power) (n), and system COP. It is shown that j/f and 8 are better used as comparison criteria for existing heat exchangers of equal heat duty rather than as design criteria. The other two PEC, n and COP, include the system effect of compressor efficiency and therefore can be used more effectively in heat exchanger and system design. Through a combination of PEC and system optimization techniques, a method is developed to evaluate and design heat exchangers for maximum system performance.Air Conditioning and Refrigeration Project 9