A robust and efficient numerical finite element method for cables

Numerical simulation of cable systems remain delicate due to their geometrical nonlinearity and also to their intrinsic unilateral constitutive law. Indeed Finite Element approaches (if not implemented carefully) fail to predict accurate equilibrium for cable structures. The major issue to be addressed is the ill-conditioning, starting configuration and wrong choice of descent direction during iterative methods. An iterative scheme based on Finite Element Method is presented to overcome this issue, even with large number of elements.     

Coaxial cavity waveguide antennas excited by stacked circular microstrip patches for use as prime‐focus reflector feeds

A coaxial cavity antenna excited by a stacked circular microstrip antenna is investigated as a feed for prime‐focus parabolic reflector antennas. The radiation pattern of the proposed cavity‐backed antenna is saddle shaped, which widens the ?10 dB beamwidths and increases the reflector efficiency especially for deep reflectors with small focal length‐to‐diameter ratios. With a single‐probe feed, the co‐polar radiation pattern is slightly asymmetric in the E‐plane, but is made symmetric by a differential feeding technique, using two probes. The impedance bandwidth of the proposed feed antenna is 20%. The antenna was fabricated and tested, and it exhibited good agreement between simulation and measurement results. The gain factor of the feed was also studied with a circular‐symmetric reflector and provided a gain factor of 79% at f/D = 0.375. This type of feed can be used as an alternative to conventional horn or waveguide feeds, where reduced size and light‐weight are desirable with added advantage of easy integration with electronics.     

Novel design of a RF-MEMS tuneable capacitor based on electrostatically induced torsion

Micro-Electro-Mechanical System (MEMS) RF switches have been one of the most interesting areas for research and development in the last years. It has been shown that they have an excellent performance in the RF and microwave frequency range and a great effort has been dedicated in designing suitable geometries and structures best suited for switching application. In parallel other devices useful for the construction of complex RF circuits have been proposed and studied. Among these tuneable capacitors are of high interest for a variety of applications. In this paper we present a new electromechanical design for a tuneable capacitor with a totally different shape from usual designs. In particular we try to exploit the effect of the small in-plane force that develops during the polarization of a parallel plate capacitor with partially overlapping plates. First prototype realizations aiming at the development of the electromechanic aspects of the concept are discussed and analyzed and as the first realization showed some problems an improved design is presented.     

Dynamic rheological and thermal study of the heat-induced gelation of tomato-seed proteins

The structural aspects of proteins prepared from tomato seeds were studied by dynamic rheology, modulated differential scanning calorimetry (MDSC) and Fourier transform infrared (FTIR) spectroscopy. The critical gel point was determined from storage (G’) and loss (G”) moduli as functions of time and frequency. The findings indicate that tomato-seed proteins can create gels during heat treatment at 90–95 °C. Mechanical spectra of the tomato-seed protein gels were classified as weak gels based on the frequency sweep, complex viscosity (η∗) and tan δ results. Moreover, G’ and G” changes were found to be dependent on both concentration and frequency. MDSC showed two peaks, with gelation temperatures (T_d) of 70 and 87 °C, which we attribute to starch and globular protein fractions, respectively. The FTIR spectra show an increase in the absorbance of amides I and II after increasing the solid content from 1 to 10% w/w, indicating mostly β-sheet and α-helical conformations.     

EFFECTS OF VARIOUS PROCESS PARAMETERS ON TEMPERATURE PROFILE OF ADIABATIC FIXED BED REACTOR FOR PRODUCTION OF DIMETHYL ETHER (DME) FROM METHANOL

Catalytic dehydration of methanol for production of dimethyl ether (DME) is an exothermic reaction. Therefore, the temperature of the adiabatic reactor of DME production will be increased by the progress of the reaction. In this article, effects of various process parameters are considered on the temperature profile of a fixed catalyst bed in a laboratory-scale reactor of DME production from methanol. Acidic gamma alumina is used for DME production, and effects of inlet feed temperature, flow rate of the feed, pressure of the reactor, and catalyst particle sizes on the temperature profile of the catalyst beds are investigated.     

Application of partial least squares and radial basis function neural networks in multivariate imaging analysis-quantitative structure activity relationship: study of cyclin dependent kinase 4 inhibitors

The detailed application of multivariate image analysis (MIA) method for the evaluation of quantitative structure activity relationship (QSAR) of some cyclin dependent kinase 4 inhibitors is demonstrated. MIA is a type of data mining methods that is based on data sets obtained from 2D images. The purpose of this study is to construct a relationship between pixels of images of investigated compounds as independent and their bioactivities as a dependent variable. Partial least square (PLS) and principal components-radial basis function neural networks (PC-RBFNNs) were developed to obtain a statistical explanation of the activity of the molecules. The performance of developed models were tested by several validation methods such as external and internal tests and also criteria recommended by Tropsha and Roy. The resulted PLS model had a high statistical quality (R2 = 0.991 and R2(CV) = 0.993) for predicting the activity of the compounds. Because of high correlation between values of predicted and experimental activities, MIA-QSAR proved to be a highly predictive approach.     

Mechanical and gelling properties of comminuted sausages containing chicken MDM

The present investigation focuses on the physicochemical properties, rheological behaviors and texture of raw and cooked emulsions containing different mechanically deboned meat (MDM) from chicken. MDMs were produced from the neck, backs and thighs. The texture and mechanical profile analyses were performed using a small deformation dynamic oscillation in a shear and instrumental texture analyzer. The mechanical spectra of the raw and cooked MDM emulsion gels were classified as weak gels based on their frequency sweep and tan δ results. Both the G′ and G″ values increased with increasing frequency in the temperature of 4 and 10 °C. The MDM from thighs had the lowest water holding capacity (WHC) and emulsifying (EC) values, while the MDM from backs had significant values of 2.41 and 128.87, respectively. The cooked emulsion containing backs showed the highest hardness and cohesiveness values, while the emulsion containing necks and thighs had the lowest texture parameters.     

Targeted energy transfer in mechanical systems by means of non-smooth nonlinear energy sink

Targeted energy transfer (TET) in a compound nonlinear 2 degrees-of-freedom system during free and forced excitations is studied analytically and numerically. The nonlinearity of the system is represented intentionally by a non-smooth piece-wise linear function for the sake of practical investigations. Further stability analysis of the system is demonstrated and commented upon and the behavior of the system during relaxation and its strongly modulated response is studied and pinpointed.     

Design procedure of a filter-antenna module implemented in substrate integrated waveguide technology

A design procedure for filter-antenna modules in substrate integrated waveguide technology is presented. The filter antenna module is designed as a second order filter, with the output resonator loaded with the radiating element. The design procedure is developed in three stages, which are explained in detail through the design of two filter-antenna modules with different electrical specifications. The integrated filter-antenna response of the designed modules is verified through electromagnetic simulations and experimental results. One of the designed modules is fabricated and measured. Measurement results yield central frequency of 1.94 GHz, ?10 dB-fractional bandwidth of 1.55 % and directive radiation pattern with maximum gain of 4.87 dBi and front-to-back ratio of 25.60 dB. These experimental results present good agreement with electromagnetic simulations.