Rheological behaviour of concentrated mandarin juice at low temperatures

Several rheological properties of concentrated mandarin juice were investigated, quantifying thixotropic behaviour and fitting experimental data to the Hahn, Weltman, and Figoni–Shoemaker equations. The latter one proved best for modelling the time dependency response. Pseudoplastic behaviour fitted well with the Herschel–Bulkley model in the interval between ?12 and 6 °C, in which yield stress and the flow behaviour index scarcely changed with temperature. The consistency coefficient and apparent viscosity both decreased as temperature increased. Fitting these consistency data to the Arrhenius‐type equation, a value of 33 kJ mol^?1 for activation energy was obtained. Concentrated mandarin juice displayed viscoelastic properties in the temperature range between ?12 and 6 °C, with the elastic character (determined by the juice’s pectin content) predominating over the viscous nature at low frequency values, but with this behaviour being inverted for high values. Furthermore, as the temperature became higher, the elastic character became more important than the viscous nature.     

Effects of Speeds,Materials, and Tool Rake Angles on Metallic Particle Emission During Orthogonal Cutting

Dry high speed machining has been proposed as a viable and cost-effective process in metal cutting industries. However, it produces fine and ultra-fine metallic particles, also referred to as dust, which can be harmful to the machine-tool operator. The risk associated with exposure to metallic particles increases as the particle size decreases. For machining processes, little data exist on the size and distribution of dust generated during the shaping of materials. In order to reduce or eliminate the generation of these particles, it is necessary to understand how and under which conditions they are formed, as well as to be able to make predictions. In this study, the effects exerted by tool geometry, material, and machining parameters on dust emission were studied experimentally in order to understand the mechanisms of dust generation and to develop a predictive model. The particle sizes studied include the PM2.5 (particles with aerodynamique diameter below 2.5 μm) and a distribution of nanoparticles varying in size from 10 nm to 10 μm. Using dry machining and reducing the amount of dust generated should improve the air quality in machine shops in addition to helping protect the environment.     

Modeling of Particle Emission During Dry Orthogonal Cutting

Because of the risks associated with exposure to metallic particles, efforts are being put into controlling and reducing them during the metal working process. Recent studies by the authors involved in this project have presented the effects of cutting speeds, workpiece material, and tool geometry on particle emission during dry machining; the authors have also proposed a new parameter, named the dust unit (D _u), for use in evaluating the quantity of particle emissions relative to the quantity of chips produced during a machining operation. In this study, a model for predicting the particle emission (dust unit) during orthogonal turning is proposed. This model, which is based on the energy approach combined with the microfriction and the plastic deformation of the material, takes into account the tool geometry, the properties of the worked material, the cutting conditions, and the chip segmentation. The model is validated using experimental results obtained during the orthogonal turning of 6061-T6 aluminum alloy, AISI 1018, AISI 4140 steels, and grey cast iron. A good agreement was found with experimental results. This model can help in designing strategies for reducing particle emission during machining processes, at the source.     

Modeling of Drinking Water Distribution Networks Using Stochastic Demand

Residential water demand is one of the most difficult parameters to determine when modeling drinking water distribution networks. It has been proven to be a stochastic process that can be characterized as a series of rectangular pulses with a set intensity, duration and frequency. These parameters can be determined using stochastic models such as the Neyman-Scott Rectangular Pulse (NSRP) model. The NSRP model is based on the solution of a non-linear optimization problem. This solution involves theoretical moments that represent the synthetic demand series (equiprobable) and the observed moments (field measurements) that statistically establish the measured demand series. The NSRP model has been applied for residential demand, and the results have been published. However, this model has not been validated for a real distribution network or compared with traditional methods. The present study compared the results of synthetic stochastic demand series, which were calculated using the NSRP model, applied to the determination of pressures, flow rates and leaks; to the results obtained using traditional simulation methods, which use the curve of hourly variation in demand, and to actual pressure and flow rate measurements. The Humaya sector of Culiacan, Sinaloa, Mexico, was used as the study area.     

Energy sector of the Russian Far East: Current status and scenarios for the future

This article describes the Russian Far East's energy sector, stressing its limited energy exports, and use of separate electricity and heating grids to geographically dispersed population centers with various supply patterns distributed across a vast territory. One key strategic trend has been to strengthen the potential of the region as an energy supplier for the countries of Northeast Asia. This underlies the framework used to develop three energy scenarios of the Russian Far East's energy future through 2030: Reference, National Alternative and Regional Alternative. While the Regional Alternative case has much greater total costs for implementation, yields almost the same amount of emissions as the BAU case, and requires greater governmental efforts to bring it to reality, it looks preferable for the RFE as a whole because it has a well-balanced primary energy consumption mix, lower energy and ecology/GDP indices, and a lower fraction of energy imports; offers greater diversity of energy supply; and provides better local energy service. The authors would like to thank Boris Saneev, Alexander Sokolov, Alexander Izhbuldin from the Institute of Energy Systems, Irkutsk; Julia Savelieva from Far Eastern Coal Research; and Alla Filatova from Far Eastern Power Engineering Institute for providing technical information, and expertise.     

Atomic force microscopy as a nanoscience tool in rational food design

Atomic force microscopy (AFM) is a nanoscience tool that has been used to provide new information on the molecular structure of food materials. As an imaging tool it has led to solutions to previously intractable problems in food science. This type of information can provide a basis for tailoring food structures to optimise functional behaviour. Such an approach will be illustrated by indicating how a basic understanding of the role of interfacial stability in complex foods systems can be extended to understand how such interfacial structures behave on digestion, and how this in turn suggests routes for the rational design of processed food structures to modify lipolysis and control fat intake. As a force transducer AFM can be used to probe interactions between food structures such as emulsion droplets at the colloidal level. This use of force spectroscopy will be illustrated through showing how it allows the effect of the structural modification of interfacial structures on colloidal interactions to be probed in model emulsion systems. Direct studies on interactions between colliding soft, deformable droplets reveal new types of interactions unique to deformable particles that can be exploited to manipulate the behaviour of processed or natural emulsion structures involved in digestion processes. Force spectroscopy can be adapted to probe specific intermolecular interactions, and this application of the technique will be illustrated through its use to test molecular hypotheses for the bioactivity of modified pectin molecules. Copyright © 2011 Society of Chemical Industry     

Considerations for Synchronization in Body Area Networks for Human Activity Monitoring

In this paper, we highlight considerations for synchronization issues in body area networks. Requirements for the synchronization accuracy in body area networks depend on the application at hand. Synchronization may be needed for power management, sample ordering, calculation of stimulus responses and for sensor fusion. This paper provides a theoretical exercise to help understand the accuracy required for typical human motion sensing. It gives an overview of various synchronisation strategies used and implemented in prototype systems. Lessons learnt from practical implementations using Bluetooth, an IEEE 802.15.4 proprietary network and Nanonet are presented to illustrate the principles involved. The discussion provides some considerations and the requirements for typical WBAN applications.