Prediction and experimental verification of bubble and processing characteristics in blown‐film extrusion

Blown‐film modeling is useful to the flexible packaging industry for predicting process and bubble characteristics, such as freeze line height (FLH), bubble diameter, and film thickness. The use of a suitable rheological equation to describe material properties is critical in simulating the blown‐film process. In this article, we present an improved rheological constitutive equation, which incorporates more realistic parameters of stress and deformation properties of the materials by combining the Hookean model with the Phan‐Thien Tanner (PTT) model. The proposed PTT–Hookean model is aimed at enhancing the viscoelastic behavior of the melt during biaxial stretching in the blown‐film extrusion. Predictions of the blown‐film bubble characteristics and FLH obtained with the PTT–Hookean model agreed well with the experimental data of this study and previous studies with different materials and different die geometries. The justification for combining the Hookean model with the PTT model in the blown‐film process is also reported here. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Entropic lattice Boltzmann method for crystallization processes

A lattice Boltzmann method (LBM) is introduced for accurate simulation of crystallization processes modelled using one-dimensional population balance equations (PBEs) with growth and nucleation phenomena. LBM for PBEs with size independent growth is developed by identifying their similarity with the advection equation. To obtain an efficient method for PBEs with size dependent growth, a coordinate transformation scheme is introduced, which can handle processes with size independent and size dependent growth rates in the same framework. The performance of the proposed scheme is verified using benchmark examples drawn from literature, which shows that LBM provides at least the same level of accuracy, while requiring lower computation time than the well-established high resolution finite volume method.     

A connectionist model for category perception: theory andimplementation

A connectionist model for learning and recognizing objects (or object classes) is presented. The learning and recognition system uses confidence values for the presence of a feature. The network can recognize multiple objects simultaneously when the corresponding overlapped feature train is presented at the input. An error function is defined, and it is minimized for obtaining the optimal set of object classes. The model is capable of learning each individual object in the supervised mode. The theory of learning is developed based on some probabilistic measures. Experimental results are presented. The model can be applied for the detection of multiple objects occluding each other.     

Some properties and fast algorithms of slant transform in image processing

A first order stationary Markov process model has been considered for image processing problems. A relative performance measure of unitary transforms to image data has been defined. It has been proved that the slant transform is superior to Walsh-Hadamard transform in this relative performance measure for positive correlation under the assumed model. A lower bound of relative performance has also been found. Furthermore, fast algorithms for computing diagonal elements of any slant transformed matrix have been presented. Finally, it has been shown how slant transform can be modified to improve the relative performance.     

Performance bound of Walsh-Hadamard transform for feature selection and compression and some related fast algorithms

A fast algorithm of finding the diagonal elements of the covariance matrix of the two-dimensional Walsh-Hadamard (WH) transform of data is described. Its usefulness and other interesting properties of the WH transform are discussed. The performance of the WH transform is compared with the Karhunen-Loeve transform for a first-order stationary Markov process.     

Simulation of optical heterodyne single-filter FSK system with line coding

The simulation results for an optical heterodyne single-filter FSK system are presented when two different line-coding plans, viz. alternate-mark-inversion (AMI) and delay modulation (DM), for the laser-driving signal are used to overcome the adverse effect of nonuniformity in the FM response of the transmitting laser.<>     

Purification and characterisation of angiotensin I converting enzyme (ACE) inhibitory peptides derived from enzymatic hydrolysate of ovotransferrin

Three novel peptides, IQW, IRW and LKP, were predicted in our previous study in the thermolysin–pepsin ovotransferrin hydrolysate. The aims of the present study were to purify the peptides, and determine if the predicted peptides purified from the hydrolysate would have the same activity as the synthetic ones. We also determined the stability of the peptides under simulated gastrointestinal condition. IQW, IRW and LKP were then successfully purified from crude ovotransferrin hydrolysate through multi-step chromatographic purification comprising of cation exchange chromatography followed by three-step reverse-phase high performance liquid chromatography (RP-HPLC), and their sequences were analysed by UPLC-MS/MS. Our results showed that their activities were comparable to the synthetic ones. Simulated gastrointestinal incubation showed that IRW was degraded into a dipeptide of IR and a free amino acid of W by pancreatin, LKP was degraded into a dipeptide of KP and a free amino acid of L by mucosal peptidase, while IQW was stable against the digestive enzymes.     

Optimal fixture parameters considering locator errors

A machining fixture consists of elements such as locators, clamps and supports. Fixture design aims at ensuring workpiece quality by restraining the workpiece in the desired position throughout machining thereby minimising the overall machining error. Workpiece elastic deformation and geometric error of locators are major components of the overall machining error. The effect of geometric error is considerable in certain cases and hence cannot be ignored. For a given error in locators, the geometry related machining error is manifest in the locator layout whereas the workpiece deformation depends on both the layout and the external forces such as clamping and machining forces. Layout of fixturing elements and the applied clamping forces are collectively called fixture parameters. The objective of minimising the total machining error can be achieved by optimising either one or both of these parameters. In this research work both of these parameters are simultaneously optimised using a genetic algorithm (GA). A finite element model of the workpiece fixture system is developed and analysed using commercial finite element software ANSYS®. Elastic deformation of workpiece under machining loads is obtained from the finite element model. MATLAB® based GA is interfaced with ANSYS® for the determination of total machining error and subsequent optimisation with the objective of complying with tolerance requirements on the critical machining feature. Results indicate that the error sources can contribute to the final machining error in varying degrees. The results also underscore the need to consider the entire machining path for optimisation of the fixture parameters.     

Remote sensing as a tool for achieving and monitoring progress toward sustainability

Airborne and satellite remote sensing have enormous potential for facilitating and monitoring the dynamics of intergenerational natural resource management and built environment sustainability. Based on reviews of (1) the development and current state of the science for deploying remote sensing, and (2) capabilities and limitations of the array of archival and real-time remotely sensed resources as tools for attaining and monitoring sustainability, we suggest several "best practices" for incorporating remote sensing within sustainability plans for selected rural and urban ecosystems. We present sustainability indices for case studies relating to sustainable forestry, agriculture, watersheds, and urbanizing areas, as well as a conceptual prototype for incorporating remotely sensed data within a general purpose decision support system that highlights the benefits of multi-temporal historical change detection in monitoring past and ongoing change, and in visualization of alternative future scenarios. Finally, we examine the sustainability of remote sensing technology, itself, with respect to economic pressures, public policy perturbations, systems resilience, biogenic factors and both inadvertent and deliberate anthropogenic impact.