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On-line, real-time collection of measurements remains a key challenge in water quality monitoring and control due to unknown and varying quality of on-line sensor data. Today’s data quality assessment is typically based on a comparison of sensor-based measurements and grab samples of the sampled solution taken next to the on-line analyzer and analyzed in a laboratory. In this work, internal data is...
Clustering is routinely used in gene expression data analysis to mine groups of co-expressed genes. Commonly used clustering algorithms require the user to specify the number of clusters a priori. We have developed a method that identifies, from a set of candidate partitions, the one with the maximal number of distinct clusters. Principal component analysis is used to characterize each cluster by...
Independent component analysis (ICA) is a popular technique for separating sources from observed linear mixtures of the sources. If the measured signals are corrupted by noise, then they are generally preprocessed before applying ICA. We make use of a recently developed technique known as the iterative principal component analysis (IPCA) to preprocess the noisy signals and estimate the signal subspace...
Data reconciliation is a technique which is used to obtain accurate estimates of variables and parameters from measured process data and a process model. The process model used for reconciling the measurements is generally derived from material and energy balances and is assumed to be exact. In this paper, we propose two modified reconciliation approaches that can be used to obtain accurate estimates...
Identifying multiple models from both static and dynamic data is an important problem in several engineering fields. Clustering based on Euclidean distance measure has been proposed to solve this problem. However, since Euclidean distance is not directly related to model fidelity, these approaches can lead to suboptimal results even when the number of models is known. In this work, through a three...
The human immune system provides rich metaphors for adaptive pattern recognition. Fault detection and diagnosis in chemical processes is commonly formulated as a pattern recognition problem. However, conventional methods for fault diagnosis often do not have a mechanism to adapt and learn as the process changes over time. In this paper, we propose an Artificial Immune System (AIS) framework that endows...
Image analysis based crystal size distribution (CSD) estimation can be very useful in the monitoring and control of crystallization process. Estimation of CSD from particle vision and measurement images is based on the characteristic length of the crystal particle alone. The estimation of the crystal width along with the length can improve the identification of the size and shape of crystals. The...
Self powered neutron detectors (SPNDs) are used for measuring neutron flux in a nuclear reactor and hence are essential for safe operation of the reactor. The main objective in this paper is to develop models on representative groups of SPNDs using principal component analysis (PCA) based techniques. In particular, we identify models using regular PCA and the iterative PCA (IPCA) technique proposed...
On-line fault detection of nonlinear processes involving dynamic dependencies and similar/overlapping fault signatures, is a fairly challenging and daunting task. Early detection and unambiguous diagnosis require that the monitoring approaches are able to deal with these daunting features. This paper compares two broad multivariate statistical approaches proposed in the literature for the detection...
Large-Eddy Simulations (LES) has been used extensively in capturing the physics of anisotropic turbulent flows. However, near wall turbulent scales in the inner layer in wall bounded flows makes it unfeasible for large Reynolds numbers. This study evaluates the use of a wall model for LES of a rotating turbulent channel flow at Reb = 34,000 and a rotating ribbed duct at Reb = 20,000 with comparisons...
The flow behind the bluff bodies is more complicated in mixed convection regime owing to the addition of buoyancy effect. In our present study fluid flow and heat transfer characteristics over elliptic cylinders of different axis ratio (AR) are investigated in mixed convection regime at Re = 100. A parametric study is also performed for higher Reynolds number, Re = 200 and Re = 500. Immersed boundary...
In typical sodium cooled fast reactors, steam generators (SG) transports heat from hot liquid sodium to high pressure feed water. Feed water gets heated and converted to superheated steam and is used to roll the turbine. In SG, tubes are in triangular pitch pattern and shell in cylindrical shape, making some non-uniform gap at periphery allowing sodium to by-pass resulting radial thermal difference...
A second-order accurate characteristic-based finite volume element method, for analyzing time-dependent scalar convection–diffusion-reaction equation in two dimensions, is presented. The concept of the characteristic-based scheme is applied to solve the convection-diffusion-reaction equation. The finite volume method is employed to establish the discretized equations for the spatial domain, while...
Steady state simulation of a 3D model of supercritical CO2 based natural circulation loop with end heat exchangers has been carried out employing the commercial CFD (computational fluid dynamics) code, FLUENT. The simulation considers phenomena such as viscous dissipation in fluid, axial conduction in fluid as well as in solid wall. Study has been carried out at a constant CO2 operating pressure of...
In this paper, the primary heat transport circuit of a pool type fast breeder reactor has been analyzed to demonstrate its decay heat removal capability without exceeding design safety limits even under complete power failure condition leading to natural convection flow in the system. A three dimensional model of large sodium pool (~12 m diameter) and complex inter-wrapper flow path through narrow...
Upgraded Apsara reactor is a 2 MW pool type research reactor. The reactor core is surrounded by two layers of BeO reflector assemblies. Three dimensional conjugate heat transfer analysis is carried out for the BeO reflector assemblies to predict the temperatures of the BeO as well as the aluminium surface which is used for cladding the BeO reflector. These reflectors get heated up due to interactions...
A two-dimensional numerical model of opposed flow flame spread over thin solid fuel is formulated and modeled to study effect of gas phase heat sink (a wire-mesh placed parallel to the fuel surface) on the flame spread rate and flame extinction. The work focuses on the performance of the wire-mesh in normal gravity environment of 21 % oxygen concentration. The simulations were carried out for various...
Recently, a new sub-grid-scale model pertaining to large eddy simulation methodology, namely shear improved-Smagorinsky model has been proposed. The model takes into account the mean shear arising due to anisotropy of the flow. In the present study, the model has been tested successfully on shear driven cavity flow to see its strength in predicting the complex flow features associated with separation...
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