Rheological behaviour of processed avocado pulp emulsions

Shear rate vs. shear stress data were obtained on avocado pulp in water emulsions using a concentric cylinder rheometer and fitted to a power law model. Dilution, as volume fraction of water, had a pronounced effect on the apparent viscosity of the pulp emulsions and the Richardson equation, (η_R= exp.( a φ) for the emulsion viscosity fitted the data well. A mean slope coefficient, a , of 4.57 can be used as a first approximation. Enzymatic treatment (40°C, 1 h), is slightly more effective than thermal treatment (65°C, 1 h), in reducing the initial apparent viscosity of the pulp-water emulsions     

Improving security of the Internet of Things via RF fingerprinting based device identification system

Neural Computing and Applications - Security is one of the primary concerns when designing wireless networks. Along detecting user identity, it is also important to detect the devices at the...     

A general particle stress equation for fixed and fluidised beds

A general constitutive equation is proposed for the solid particle stress in a fluidised bed. This equation reduces in a straightforward manner to describe the particle stress in a fixed bed, and it implies a Mohr-Coulomb yield criterion for the transition from the fixed-bed to the fluidised-bed state. Experimental evidence is given to show that at incipient fluidisation, the particle stress assumes a form agreeing with that predicted by theory.     

Wireless Channel Tracking Based on Optimum Predictive LMS

A frequency domain analysis is presented to optimize the Predictive Least Mean Square (PLMS) algorithm used for wireless channel tracking. Simulation results show that the PLMS offers significant improvement in tracking performance compared to that of the conventional LMS based method. The algorithm parameters should be carefully selected in order to gain such improvements. The objective of this paper is to use frequency domain analysis to determine an expression for the Mean Square Tracking Error (MSTE) and use it to obtain the optimum PLMS algorithm parameters such as step size (μ) and smoothing constant (θ) with numerical optimization methods.

Novel Approach for Modeling Wireless Fading Channels Using a Finite State Markov Chain

Empirical modeling of wireless fading channels using common schemes such as autoregression and the finite state Markov chain (FSMC) is investigated. The conceptual background of both channel structures and the establishment of their mutual dependence in a confined manner are presented. The novel contribution lies in the proposal of a new approach for deriving the state transition probabilities borrowed from economic disciplines, which has not been studied so far with respect to the modeling of FSMC wireless fading channels. The proposed approach is based on equal portioning of the received signal‐to‐noise ratio, realized by using an alternative probability construction that was initially highlighted by Tauchen. The associated statistical procedure shows that a first‐order FSMC with a limited number of channel states can satisfactorily approximate fading. The computational overheads of the proposed technique are analyzed and proven to be less demanding compared to the conventional FSMC approach based on the level crossing rate. Simulations confirm the analytical results and promising performance of the new channel model based on the Tauchen approach without extra complexity costs.     

FIR digital filter-based ZCDPLL for carrier recovery

The objective of this work is to analyse the performance of the newly proposed two-tap FIR digital filter-based first-order zero-crossing digital phase-locked loop (ZCDPLL) in the absence or presence of additive white Gaussian noise (AWGN). The introduction of the two-tap FIR digital filter widens the lock range of a ZCDPLL and improves the loop’s operation in the presence of AWGN. The FIR digital filter tap coefficients affect the loop convergence behaviour and appropriate selection of those gains should be taken into consideration. The new proposed loop has wider locking range and faster acquisition time and reduces the phase error variations in the presence of noise.     

Experimental evaluation of haptic data communication with prediction

The transmission of haptic data is relatively challenging in multimedia communication. In this research study, the methods are presented for exploiting the properties of human haptic perception for data reduction of haptic data transmission. Packet-switched communication of haptic data is characterized by high packet rates on the communication channel. The quality of the internet-based haptic tele-control/tele-presence systems is highly dependent on the quality of the communication channel between the operator and the remote site, and on the delay jitter in the data exchange. The proposed research work is evaluated experimentally using a Geomagic Touch (previously PHANTOM Sensable Omni) haptic device with a sphere as a virtual model. Four experiments were conducted to evaluate the proposed research study. In the first experiment the JND Weber’s law is applied on sent force values only, while in the second experiment, the force calculation algorithm has been modified to include human movement velocity. The third experiment discusses the use of JND on the sent velocity values. The evaluation of the human’s perception shows that the proposed modification to the basic dead-band approach highly reduces the number of sent packets with minimal disturbance in haptic feeling. Further enhancements using prediction techniques have also been introduced in the fourth experimental evaluation. The linear predictions are added to the above proposed reduction methods. Combining the dead-band approach with a fast, configurable and accurate prediction algorithm enables a significant reduction in the amount of data sent across the network. The reduction is estimated to be 85%, while preserving the original data structure.     

Behaviour of fractional loop delay zero crossing digital phase locked loop (FR-ZCDPLL)

This article analyses the performance of the first-order zero crossing digital phase locked loops (FR-ZCDPLL) when fractional loop delay is added to loop. The non-linear dynamics of the loop is presented, analysed and examined through bifurcation behaviour. Numerical simulation of the loop is conducted to proof the mathematical analysis of the loop operation. The results of the loop simulation show that the proposed FR-ZCDPLL has enhanced the performance compared to the conventional zero crossing DPLL in terms of wider lock range, captured range and stable operation region. In addition, extensive experimental simulation was conducted to find the optimum loop parameters for different loop environmental conditions. The addition of the fractional loop delay network in the conventional loop also reduces the phase jitter and its variance especially when the signal-to-noise ratio is low.     

Optimizing the Preparation Parameters of Nanocrystalline Zirconia for Catalytic Applications

Nanocrystalline zirconia powder with high surface area and high tetragonal phase percentage is prepared by the precipitation method using ammonium hydroxide as a precipitating agent.The pH of precipitation,preparation temperature and calcinations’ temperature are optimized.Crystallite size,specific surface area,tetragonal phase percentage and the thermal stability of the prepared samples are identified by diferent characterization tools such as X-ray difraction(XRD),thermo gravimetric analysis(TGA),diferential scanning calorimetry(DSC),BET surface area,scanning electron microscopy(SEM)and transmission electron microscopy(TEM).The optimum preparation parameters for obtaining nanocrystalline zirconia with high percentage of tetragonal phase and high surface area are pH 9,preparation temperature of 80℃ and calcinations’ temperature of400℃.The sample prepared under optimized conditions showed a high specific surface area of 179.2 m2/g,high tetragonal phase percentage of 81%and high catalytic activity(60%)for synthesis of butyl acetate ester.     

A mixed integer linear programming model for set-up reduction superstructures

The objective of this research is to introduce the concept of a set-up reduction superstructure and evaluate its utility in set-up reduction projects. For a given set-up project, consisting of several interdependent activities as well as existing ones, a superstructure is defined. For this superstructure, a corresponding mixed integer linear programming model is developed with a view to selecting the optimum set-up project. The resulting model is applied to the set-up reduction problem in a real example of the fabrication in a CNC lathe of a vibration reduction pulley for lorry motors. The model is implemented in the Mathematica platform. It is shown that the set-up reduction superstructure is a useful concept in practice.