Independence Relations Produced by Parameter Values in Causal Models

Optimal fitting of a myocardial time-activity curve is accomplished with a monoexponential plus a constant, resulting in three parameters: amplitude and half-time of the monoexponential and the constant. The aim of this study was to estimate the precision of the calculated parameters. The variability of the parameter values as a function of the acquisition time was studied in 11 patients with cardiac complaints. Of the three parameters the half-time value varied most strongly with the acquisition time. An acquisition time of 80 min was needed to keep the standard deviation of the half-time value within ±10%. To estimate the standard deviation of the half-time value as a function of the parameter values, of the noise content of the time-activity curve and of the acquisition time, a model experiment was used. In most cases the SD decreased by 50% if the acquisition time was increased from 60 to 90 min. A low amplitude/constant ratio and a high half-time value result in a high SD of the half-time value. Tables are presented to estimate the SD in a particular case.

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Stable and Supported Semantics in Continuous Vector Spaces

Proceedings of the Seventeenth International Conference on Principles of Knowledge Representation and Reasoning ◽

10.24963/kr.2020/7 ◽

2020 ◽

Author(s):

Yaniv Aspis ◽

Krysia Broda ◽

Alessandra Russo ◽

Jorge Lobo

Keyword(s):

Logic Program ◽

Matrix Multiplication ◽

Vector Spaces ◽

Continuous Space ◽

Continuous Vector ◽

Novel Approach ◽

Gradient Based ◽

Normal Logic ◽

Parameter Values ◽

Normal Logic Program

We introduce a novel approach for the computation of stable and supported models of normal logic programs in continuous vector spaces by a gradient-based search method. Specifically, the application of the immediate consequence operator of a program reduct can be computed in a vector space. To do this, Herbrand interpretations of a propositional program are embedded as 0-1 vectors in $\mathbb{R}^N$ and program reducts are represented as matrices in $\mathbb{R}^{N \times N}$. Using these representations we prove that the underlying semantics of a normal logic program is captured through matrix multiplication and a differentiable operation. As supported and stable models of a normal logic program can now be seen as fixed points in a continuous space, non-monotonic deduction can be performed using an optimisation process such as Newton's method. We report the results of several experiments using synthetically generated programs that demonstrate the feasibility of the approach and highlight how different parameter values can affect the behaviour of the system.

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The Role of Causal Models in Analogical Inference

Acta Psychologica Sinica ◽

10.3724/sp.j.1041.2010.00834 ◽

2010 ◽

Vol 42 (8) ◽

pp. 834-844

Author(s):

Ting-Ting WANG ◽

Lei MO

Keyword(s):

Causal Models ◽

Analogical Inference

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Heterotrophic Kinetic Parameter Estimation for Enhanced Biological Phosphorus Removal Processes Operated in Conventional and Membrane-Assisted Modes

Water Quality Research Journal ◽

10.2166/wqrj.2006.008 ◽

2006 ◽

Vol 41 (1) ◽

pp. 72-83 ◽

Cited By ~ 2

Author(s):

Zhe Zhang ◽

Eric R. Hall

Keyword(s):

Parameter Estimation ◽

Phosphorus Removal ◽

Growth Yield ◽

Pilot Scale ◽

Enhanced Biological Phosphorus Removal ◽

Biological Phosphorus Removal ◽

Nitrogen And Phosphorus ◽

Parameter Values ◽

The Impact ◽

Biological Phosphorus

Abstract Parameter estimation and wastewater characterization are crucial for modelling of the membrane enhanced biological phosphorus removal (MEBPR) process. Prior to determining the values of a subset of kinetic and stoichiometric parameters used in ASM No. 2 (ASM2), the carbon, nitrogen and phosphorus fractions of influent wastewater at the University of British Columbia (UBC) pilot plant were characterized. It was found that the UBC wastewater contained fractions of volatile acids (SA), readily fermentable biodegradable COD (SF) and slowly biodegradable COD (XS) that fell within the ASM2 default value ranges. The contents of soluble inert COD (SI) and particulate inert COD (XI) were somewhat higher than ASM2 default values. Mixed liquor samples from pilot-scale MEBPR and conventional enhanced biological phosphorus removal (CEBPR) processes operated under parallel conditions, were then analyzed experimentally to assess the impact of operation in a membrane-assisted mode on the growth yield (YH), decay coefficient (bH) and maximum specific growth rate of heterotrophic biomass (µH). The resulting values for YH, bH and µH were slightly lower for the MEBPR train than for the CEBPR train, but the differences were not statistically significant. It is suggested that MEBPR simulation using ASM2 could be accomplished satisfactorily using parameter values determined for a conventional biological phosphorus removal process, if MEBPR parameter values are not available.

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Modelling of Nitrification at the Mogden Treatment Works

Water Science & Technology ◽

10.2166/wst.1989.0233 ◽

1989 ◽

Vol 21 (4-5) ◽

pp. 305-314

Author(s):

J. P. Lumbers ◽

S. C. Cook ◽

G. A. Thomas

Keyword(s):

Sensitivity Analysis ◽

Monte Carlo Simulation ◽

River Basin Management ◽

Independent Data ◽

Activated Sludge Process ◽

Basin Management ◽

Alternative Control ◽

Control Actions ◽

Parameter Values ◽

Generalised Sensitivity Analysis

An application of a dynamic model of the activated sludge process is described within the context of real-time river basin management. The model has been calibrated and validated on independent data and then applied to investigate losses of nitrification at the Mogden Works. Monte Carlo simulation and generalised sensitivity analysis were found to be effective ways of identifying appropriate parameter values and their importance. The prediction of unmeasured states such as the autotroph population enabled the effects of alternative control actions to be better understood and the most suitable measures found.

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Oscillatory Dynamics of P53 Network With Time Delays

Combinatorial Chemistry & High Throughput Screening ◽

10.2174/1386207321666180601080026 ◽

2018 ◽

Vol 21 (6) ◽

pp. 411-419 ◽

Cited By ~ 2

Author(s):

Conghua Wang ◽

Fang Yan ◽

Yuan Zhang ◽

Haihong Liu ◽

Linghai Zhang

Keyword(s):

Hopf Bifurcation ◽

Cell Fate ◽

Time Delays ◽

Sustained Oscillation ◽

Multiple Time ◽

Cell Fate Decisions ◽

Oscillatory Dynamics ◽

Main Components ◽

Parameter Values ◽

P53 Network

Aims and Objective: A large number of experimental evidences report that the oscillatory dynamics of p53 would regulate the cell fate decisions. Moreover, multiple time delays are ubiquitous in gene expression which have been demonstrated to lead to important consequences on dynamics of genetic networks. Although delay-driven sustained oscillation in p53-based networks is commonplace, the precise roles of such delays during the processes are not completely known. Method: Herein, an integrated model with five basic components and two time delays for the network is developed. Using such time delays as the bifurcation parameter, the existence of Hopf bifurcation is given by analyzing the relevant characteristic equations. Moreover, the effects of such time delays are studied and the expression levels of the main components of the system are compared when taking different parameters and time delays. Result and Conclusion: The above theoretical results indicated that the transcriptional and translational delays can induce oscillation by undergoing a super-critical Hopf bifurcation. More interestingly, the length of these delays can control the amplitude and period of the oscillation. Furthermore, a certain range of model parameter values is essential for oscillation. Finally, we illustrated the main results in detail through numerical simulations.

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Recent Patents on Nanoporous Filtration Membranes with Complex Pores

Recent Patents on Engineering ◽

10.2174/1872212113666190913182646 ◽

2020 ◽

Vol 14 (2) ◽

pp. 229-233

Author(s):

Yongbin Zhang

Keyword(s):

Geometrical Parameter ◽

Filtration Membranes ◽

Analytical Results ◽

Parameter Values ◽

Mechanical Strengths ◽

Better Than

Background:: The challenges to nanoporous filtration membranes are small fluxes and low membrane mechanical strengths. Objective:: To introduce newly invented nanoporous filtration membranes with complex pores, improved fluxes and mechanical strengths as registered in patents. Methods:: The analytical results are presented for the addressed membranes. Results:: The geometrical parameter values of the addressed membranes can be optimized for the highest fluxes. Conclusion:: The overall performances of nanoporous filtration membranes with complex cylindrical or/and conical pores can be significantly better than that of the conventional nanoporous filtration membranes with single cylindrical or conical pores.

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Causal Models and Intelligent Data Management

10.1007/978-3-642-58648-4 ◽

1999 ◽

Cited By ~ 2

Keyword(s):

Data Management ◽

Causal Models

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