Dynamic Niche Clustering: a fuzzy variable radius niching technique for multimodal optimisation in GAs

This paper describes the recent developments and improvements made to the variable radius niching technique called Dynamic Niche Clustering (DNC). DNC is fitness sharing based technique that employs a separate population of overlapping fuzzy niches with independent radii which operate in the decoded parameter space, and are maintained alongside the normal GA population. We describe a speedup process that can be applied to the initial generation which greatly reduces the complexity of the initial stages. A split operator is also introduced that is designed to counteract the excessive growth of niches, and it is shown that this improves the overall robustness of the technique. Finally, the effect of local elitism is documented and compared to the performance of the basic DNC technique on a selection of 2D test functions. The paper is concluded with a view to future work to be undertaken on the technique.

A variable radius niching technique for speciation in genetic algorithms

In this paper, a continuation of a variable radius niche technique called Dynamic Niche Clustering developed by (Gan & Warwick, 1999) is presented. The technique employs a separate dynamic population of overlapping niches that coexists alongside the normal population. An empirical analysis of the updated methodology on a large group of standard optimisation test-bed functions is also given. The technique is shown to perform almost as well as standard fitness sharing with regards to stability and the accuracy of peak identification, but it outperforms standard fitness sharing with regards to time complexity. It is also shown that the technique is capable of forming niches of varying size depending on the characteristics of the underlying peak that the niche is populating.

Evaluating mid-infrared spectroscopy as a new technique for predicting sensory texture attributes of processed cheese

The objective of this study was to investigate the potential application of mid-infrared spectroscopy for determination of selected sensory attributes in a range of experimentally manufactured processed cheese samples. This study also evaluates mid-infrared spectroscopy against other recently proposed techniques for predicting sensory texture attributes. Processed cheeses (n = 32) of varying compositions were manufactured on a pilot scale. After 2 and 4 wk of storage at 4 degrees C, mid-infrared spectra ( 640 to 4,000 cm(-1)) were recorded and samples were scored on a scale of 0 to 100 for 9 attributes using descriptive sensory analysis. Models were developed by partial least squares regression using raw and pretreated spectra. The mouth-coating and mass-forming models were improved by using a reduced spectral range ( 930 to 1,767 cm(-1)). The remaining attributes were most successfully modeled using a combined range ( 930 to 1,767 cm(-1) and 2,839 to 4,000 cm(-1)). The root mean square errors of cross-validation for the models were 7.4(firmness; range 65.3), 4.6 ( rubbery; range 41.7), 7.1 ( creamy; range 60.9), 5.1(chewy; range 43.3), 5.2(mouth-coating; range 37.4), 5.3 (fragmentable; range 51.0), 7.4 ( melting; range 69.3), and 3.1 (mass-forming; range 23.6). These models had a good practical utility. Model accuracy ranged from approximate quantitative predictions to excellent predictions ( range error ratio = 9.6). In general, the models compared favorably with previously reported instrumental texture models and near-infrared models, although the creamy, chewy, and melting models were slightly weaker than the previously reported near-infrared models. We concluded that mid-infrared spectroscopy could be successfully used for the nondestructive and objective assessment of processed cheese sensory quality..

Simulated annealing technique for fast learning of SOM networks

The Self-Organizing Map (SOM) is a popular unsupervised neural network able to provide effective clustering and data visualization for multidimensional input datasets. In this paper, we present an application of the simulated annealing procedure to the SOM learning algorithm with the aim to obtain a fast learning and better performances in terms of quantization error. The proposed learning algorithm is called Fast Learning Self-Organized Map, and it does not affect the easiness of the basic learning algorithm of the standard SOM. The proposed learning algorithm also improves the quality of resulting maps by providing better clustering quality and topology preservation of input multi-dimensional data. Several experiments are used to compare the proposed approach with the original algorithm and some of its modification and speed-up techniques.

A detailed single chain model for molten poly(tetrafluoroethylene) from a novel structure refinement technique on neutron scattering data

We present a new methodology that couples neutron diffraction experiments over a wide Q range with single chain modelling in order to explore, in a quantitative manner, the intrachain organization of non-crystalline polymers. The technique is based on the assignment of parameters describing the chemical, geometric and conformational characteristics of the polymeric chain, and on the variation of these parameters to minimize the difference between the predicted and experimental diffraction patterns. The method is successfully applied to the study of molten poly(tetrafluoroethylene) at two different temperatures, and provides unambiguous information on the configuration of the chain and its degree of flexibility. From analysis of the experimental data a model is derived with CC and CF bond lengths of 1.58 and 1.36 Å, respectively, a backbone valence angle of 110° and a torsional angle distribution which is characterized by four isometric states, namely a split trans state at ± 18°, giving rise to a helical chain conformation, and two gauche states at ± 112°. The probability of trans conformers is 0.86 at T = 350°C, which decreases slightly to 0.84 at T = 400°C. Correspondingly, the chain segments are characterized by long all-trans sequences with random changes in sign, rather anisotropic in nature, which give rise to a rather stiff chain. We compare the results of this quantitative analysis of the experimental scattering data with the theoretical predictions of both force fields and molecular orbital conformation energy calculations.

EMD: A novel technique for the study of tremor time series

This paper introduces the Hilbert Analysis (HA), which is a novel digital signal processing technique, for the investigation of tremor. The HA is formed by two complementary tools, i.e. the Empirical Mode Decomposition (EMD) and the Hilbert Spectrum (HS). In this work we show that the EMD can automatically detect and isolate tremulous and voluntary movements from experimental signals collected from 31 patients with different conditions. Our results also suggest that the tremor may be described by a new class of mathematical functions defined in the HA framework. In a further study, the HS was employed for visualization of the energy activities of signals. This tool introduces the concept of instantaneous frequency in the field of tremor. In addition, it could provide, in a time-frequency-energy plot, a clear visualization of local activities of tremor energy over the time. The HA demonstrated to be very useful to perform objective measurements of any kind of tremor and can therefore be used to perform functional assessment.

Application of EMD as a novel technique for the study of tremor time series

This paper introduces the Hilbert Analysis (HA), which is a novel digital signal processing technique, for the investigation of tremor. The HA is formed by two complementary tools, i.e. the Empirical Mode Decomposition (EMD) and the Hilbert Spectrum (HS). In this work we show that the EMD can automatically detect and isolate tremulous and voluntary movements from experimental signals collected from 31 patients with different conditions. Our results also suggest that the tremor may be described by a new class of mathematical functions defined in the HA framework. In a further study, the HS was employed for visualization of the energy activities of signals. This tool introduces the concept of instantaneous frequency in the field of tremor. In addition, it could provide, in a time-frequency energy plot, a clear visualization of local activities of tremor energy over the time. The HA demonstrated to be very useful to perform objective measurements of any kind of tremor and can therefore be used to perform functional assessment.

The possibility of lowering oil content of potato chips by combining atmospheric frying with postfrying vacuum application

Four protocols involving the application of low pressures, either toward the end of frying or after frying, were investigated with the aim of lowering the oil content of potato chips. Protocol 1 involving frying at atmospheric pressure followed by a 3 min draining time constituted the control. Protocol 2 involved lowering of pressure to 13.33 kPa, 40 s before the end of frying, followed by draining for 3 min at the same pressure. Protocol 3 was the same as protocol 2, except that the pressure was lowered 3 s before the end of frying. Protocol 4 involved lowering the pressure to 13.33 kPa after the product was lifted from the oil and holding it at this value over the draining time of 3 min. Protocol 4 gave a product having the lowest oil content (37.12 g oil/100 g defatted dry matter), while protocol 2 gave the product with highest oil content (71.10 g oil/100 g defatted dry matter), followed by those obtained using protocols 1 and 3(68.48 g oil/100 g defatted dry matter and 52.50 g oil/100 g defatted dry matter, respectively). Protocol 4 was further evaluated to study the effects of draining times and vacuum applied, and compared with the control. It was noted that over the modest range of pressures investigated, there was no significant effect of the vacuum applied on the oil content of the product. This study demonstrates that the oil content of potato chips can be lowered significantly by combining atmospheric frying with draining under vacuum.

A technique for delivering individualised formative problems and examples

Active learning plays a strong role in mathematics and statistics, and formative problems are vital for developing key problem-solving skills. To keep students engaged and help them master the fundamentals before challenging themselves further, we have developed a system for delivering problems tailored to a student‟s current level of understanding. Specifically, by adapting simple methodology from clinical trials, a framework for delivering existing problems and other illustrative material has been developed, making use of macros in Excel. The problems are assigned a level of difficulty (a „dose‟), and problems are presented to the student in an order depending on their ability, i.e. based on their performance so far on other problems. We demonstrate and discuss the application of the approach with formative examples developed for a first year course on plane coordinate geometry, and also for problems centred on the topic of chi-square tests.

Pressing technique and its effect on the quality of Dhaka cheese

Dhaka cheese is a semihard artisanal variety made mainly from bovine milk, using very simple pressing methods. Experimental cheeses were pressed at gauge pressures up to 31 kPa for 12 h at 24 °C and 70% RH. These cheeses were subsequently examined for their compositional, textural and rheological properties plus their microstructures investigated by confocal laser microscopy. The cheese pressed at 15.6 kPa was found to have the best compositional and structural properties.

Post-frying oil drainage from potato chips and french fries: a comparative study of atmospheric and vacuum drainage

This paper represents a study of the transient changes occurring in temperature, and moisture and oil contents during the so called “post-frying drainage”—which is the duration for which a product is held in the head space of the fryer after it is removed from the oil. Since most of the oil adhering to the product penetrates into the structure during this period, this paper examines the effects of applying vacuum during drainage (1.33 kPa) to maintain the product temperature consistently above the water saturation temperature corresponding to the prevailing pressure (11 °C), which potentially eliminates water condensation and prevents the occluded surface oil from penetrating into the product structure. Draining under vacuum significantly lowers the oil content of potato chips by 38% compared to atmospheric drainage. This phenomenon can be further confirmed by confocal laser scanning microscopy (CLSM) images, which show that the boundary between the core and the crust regions is clearly visible in the case of vacuum drainage, whereas in the case of atmospheric drainage, the oil is distributed throughout the structure. Unfortunately, the same approach did not reduce the oil content of French fries—the oil content of vacuum-drained product was found similar to the product obtained by draining under atmospheric pressure. This is because the reduction in oil content only occurs when there is net moisture evaporation from the product and the evaporation rate is sufficient to force out the oil from the product; this was clearly not the case with French fries. The CLSM images show that the oil distribution in the products drained under atmospheric pressure and vacuum was similar.

Wind observations above an urban river using a new lidar technique, scintillometry and anemometry

Flow along rivers, an integral part of many cities, might provide a key mechanism for ventilation – which is important for air quality and heat stress. Since the flow varies in space and time around rivers, there is limited utility in point measurements. Ground-based remote sensing offers the opportunity to study 3D flow in locations which are hard to observe. For three months in the winter and spring of 2011, the atmospheric flow above the River Thames in central London was observed using a scanning Doppler lidar, a dual-beam scintillometer and sonic anemometry. First, an inter-comparison showed that lidar-derived mean wind-speed estimates compare almost as well to sonic anemometers (root-mean-square error (rmse) 0.65–0.68 m s–1) as comparisons between sonic anemometers (0.35–0.73 m s–1). Second, the lidar duo-beam scanning strategy provided horizontal transects of wind vectors comparison with scintillometer rmse 1.12–1.63 m s–1) which revealed mean and turbulent flow across the river and surrounds; in particular: chanelling flow along the river and turbulence changes consistent with the roughness changes between built to river environments. The results have important consequences for air quality and dispersion around urban rivers, especially given that many cities have high traffic rates on bankside roads.

Combination of moderate vacuum frying with high vacuum drainage: relationship between process conditions and oil uptake

This paper explores the possibility of combining moderate vacuum frying followed by post-frying high vacuum application during the oil drainage stage, with the aim to reduce oil content in potato chips. Potato slices were initially vacuum fried under two operating conditions (140 °C, 20 kPa and 162 °C, 50.67 kPa) until the moisture content reached 10 and 15 % (wet basis), prior to holding the samples in the head space under high vacuum level (1.33 kPa). This two-stage process was found to lower significantly the amount of oil taken up by potato chips by an amount as high as 48 %, compared to drainage at the same pressure as the frying pressure. Reducing the pressure value to 1.33 kPa reduced the water saturation temperature (11 °C), causing the product to continuously lose moisture during the course of drainage. Continuous release of water vapour prevented the occluded surface oil from penetrating into the product structure and released it from the surface of the product. When frying and drainage occurred at the same pressure, the temperature of the product fell below the water saturation temperature soon after it was lifted out of the oil, which resulted in the oil getting sucked into the product. Thus, lowering the pressure after frying to a value well below the frying pressure is a promising method to lower oil uptake by the product.