Thermal stresses during freezing of a two-layer food

Thermal stresses during freezing of a two-layer material, that can contribute to crack formation, are studied. A 3D numerical model of a two-layer food with food analog Tylose^® and chocolate is presented. An apparent specific heat formulation was used to model the heat transfer with phase change over a temperature range. The mechanics model considered viscoelasticity in Tylose^®; thermal strains were imposed due to the increase in volume from ice formation in Tylose^® and the decrease in volume from freezing of the chocolate. Results show that complex evolution of stresses, that include compressive and tensile values, occur during freezing. Sensitivity analysis showed that the Poisson's ratio was a very important parameter that affects the magnitude of stress. Variations in calculated stresses were found to be proportional to variations in Young's modulus. Knowing the stresses, the possibilities of undesired cracking of a chocolate coating applied onto another material such as ice cream could be evaluated.     

On the validity of soft particle approximations for the light scattering by a homogeneous dielectric sphere

Abstract

The validity of various soft particle approximations has been examined for the scattering of light by a homogeneous dielectric sphere. A scalar analogue of the S-approximation has been presented. It is shown that this much simpler approximation could be nearly as good as the sophisticated S-approximation itself. Numerical results for the extinction and the scattered intensities are examined over a wide refracted index and size parameter domain. The anomalous diffraction approximation has also been included in numerical comparisons.     

Fall detection method based on Spatio-temporal feature fusion using combined two-channel classification

Nowadays, the growing population of senior citizens is a challenge for almost all developing countries. New technologies can help monitor elderlies at home by providing an innovative and secure environment and further enhancing their quality of living. Vision-based systems offer promising results in analyzing human posture and detecting abnormal events like falls. Falls appear to possess the most considerable risk for seniors living alone. In this article, a new fall detection method is proposed based on a fusion of motion-based and human shape-based features. Motion History Images (MHI) represent the temporal feature in our approach. Simultaneously, the height-to-width ratio and centroid of the moving person represent the spatial features. A two-channel classification model is designed using a threshold-based and a keyframe-based approach. The two channels are further combined based on any classification disparity for which more information is used to classify between falls and daily activities. Keyframes are selected based on the displacement of the spatial features having a threshold higher than a preset value. Keyframes are subject to a K-NN classification. The proposed algorithm delivers promising results on the UR fall detection dataset’s simulated fall and daily activity sequences. It provides satisfactory performance compared to existing state-of-the-art methods and shows a peak accuracy of 98.6% and recall of 100% in detecting falls. Specificity and precision are over 96%.

     

SQuad: Compact Representation for Triangle Meshes

The SQuad data structure represents the connectivity of a triangle mesh by its “S table” of about 2 rpt (integer references per triangle). Yet it allows for a simple implementation of expected constant‐time, random‐access operators for traversing the mesh, including in‐order traversal of the triangles incident upon a vertex. SQuad is more compact than the Corner Table (CT), which stores 6 rpt, and than the recently proposed SOT, which stores 3 rpt. However, in‐core access is generally faster in CT than in SQuad, and SQuad requires rebuilding the S table if the connectivity is altered. The storage reduction and memory coherence opportunities it offers may help to reduce the frequency of page faults and cache misses when accessing elements of a mesh that does not fit in memory. We provide the details of a simple algorithm that builds the S table and of an optimized implementation of the SQuad operators.     

Parallel simulation of cyber-physical systems

Innovations in Systems and Software Engineering - Model-based design (MBD) in systems engineering is a well-accepted technique to abstract, analyze, verify, and validate complex systems. In MBD, we...     

Heavy metal contamination in sediments from vehicle washing: a case study of Olarong Chhu Stream and Paa Chhu River,Bhutan

Heavy metal contamination owing to anthropogenic activities affects human health and is of worldwide concern. The aim of the study was to investigate the possible linkage between vehicle washing and heavy metal contamination. Heavy metal concentration in sediment samples from vehicle wash wastewater settlement tanks (WSTs) and water bodies (Olarong Chhu and Paa Chhu) used for discharging untreated wastewater was determined with an atomic absorption spectrophotometer. High concentrations of Cd, Cr, Cu, Fe, Pb, Ni and Zn were found in WSTs. Assessment of sediment pollution in water bodies was determined using contamination factor (CF), pollution load index (PLI), geo-accumulation index (Igeo) and enrichment factor (EF); these indices denoted anthropogenic inputs of heavy metals. Significant Pearson correlations between heavy metals in sediments from Olarong Chhu, Paa Chhu and WSTs indicated their common origin. Thus, this study confirms the linkage between vehicle washing and heavy metal contamination. Bhutan’s policy on installation of wastewater treatment plants should be implemented effectively. Bhutan should consider feasible methods for the safe disposal of sludge from WSTs.

Abbreviations: Atomic Absorption Spectrophotometry - (AAS)     

Removal of FeCl3 from aqueous solution by ultrafiltration using ordered mesoporous MCM-48 ceramic composite membrane

Mesoporous MCM-48 membrane was prepared on a low-cost circular-shaped ceramic support by a hydrothermal crystallization technique. The characteristics of MCM-48 powder and composite membrane were evaluated using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), porosity and water permeation test. The porosity and pore size of the composite membrane were found to be 22% and 0.142 µm, respectively. The MCM-48 composite membrane was investigated for the separation potential of FeCl₃ from aqueous solution and a maximum rejection of 86% was obtained for a feed concentration of 250 ppm at lower pH 2.     

Experimental and Analytical Temperature Distributions during Oven-Based Convection Heating

ABSTRACT:  Mathematical models, combined with experimental evaluation, provide an approach to understand, design, and optimize food process operations. Magnetic resonance imaging (MRI), as an experimental technique, is used extensively in both medical and engineering applications to measure and quantify transport processes. Magnetic resonance (MR) was used in this study to assess a mathematical model based on Fourier's second law. The objective was to compare analytical solutions for the prediction of internal temperature distributions in foods during oven-based convective heating to experimental temperature measurements and determine at what point during the heating process a coupled heat and mass transport process should be considered. Cylindrical samples of a model food gel, Russet potato and rehydrated mashed potato were heated in a convection oven for specified times. Experimentally measured internal temperatures were compared to the internal temperatures predicted by the analytical model. Temperatures distributions in the axial direction compared favorably for the gel and acceptably for the Russet and mashed potato samples. The MR-acquired temperatures in the radial direction for the gel resulted in a shallower gradient than predicted but followed the expected trend. For the potato samples, the MR-acquired temperatures in the radial direction were not qualitatively similar to the analytical predictions due to moisture loss during heating. If temperature resolution is required in the radial direction, moisture losses merit the use of transport models that couple heat and mass transfer.     

Enabling computer-aided food process engineering: Property estimation equations for transport phenomena-based models

During processing of a food, its temperature, moisture and other compositions, structure, etc., can change, continuously changing its physical properties. Realistic simulation of food processes require dynamic estimation of the food physical properties as they continue to change during the process. Having a few data points for a few states of the material, as is true for the majority of food properties data, is not sufficient for realistic process simulations. The goal of this article is a practical one: it is to develop a concise resource for the equations that can estimate food properties as they change during processing. Such a resource should make computer-aided food product, process and equipment design one step closer to reality by making the necessary input parameters available in one location and in a format that can be readily used in a simulation software. Several equilibrium, transport and electrical properties are included. The estimation equations for any property are chosen from among the most successful and accurate, staying away from property estimators that have theoretical basis but have not been as successful for food materials. For each property, implementation of its prediction equations in a computer model has also been discussed. Accuracy of each property estimation process have been included from the literature, showing most properties can be estimated to within 10% accuracy, sufficient for modeling purposes. Having such reasonable prediction models has the important implication that unavailability of sufficient data, that is expected to be always true due to the variety and complexity of food materials and processes, is not a bottleneck for computer-aided food process engineering.