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To devise a parametric study using a new application of the boundary element method (BEM) and to propose an efficient approach for speeding up the computation time of the BEM based on neural networks (NNs).

A 3D finite elements formulation is combined with radial basis function NNs to speeding up the computation time.

The paper shows how to estimate the role of thin slabs filled with unconventional media in order to increase the coupling values when placed between two metallic strips in a coupled microstrip line layout or to improve the shielding properties when used as absorber.

The numerical results here presented are not bianisotropic but can be easily extended to take into account bianisotropic media.

The formulation is one of the only with the potential for investigating unconventional bianisotropic media like Chiral materials which are seen as one possible route to achieving double negative media.

The purpose of this paper is to present the temporal reflection of electromagnetic waves (EMWs) in simple polar-molecule reactions whose polarization changes with the proceeding of the reactions.

At a temporal boundary, based on the continuity of the electric displacement and magnetic induction, the reflected condition of EMWs is obtained, and the expression of the transmission and reflection coefficients in the reactions is derived. Subsequently, a one-dimensional model is used to validate the reflected condition and expression.

If the time scale of the component concentration variation is greater than the wave period, the polarization of the reactions at a temporal boundary is continuous. The reflection does not happen. On the other hand, when the time scale of the component concentration variation is smaller than the wave period, the polarization is not continuous at a temporal boundary. The impedance of the reactions at the temporal boundary changes and the reflection occurs.

The results may be helpful in disclosing the non-uniform distribution of EMWs in chemical reactions.

The aim of this study was to prove that radio-frequency (RF) energy with 13.56 MHz can be used for heating building structures in a controlled manner exploiting the advantage that homogeneous heating with sufficient penetration depths can be achieved.

Because parallel electrodes on both sides of the heated structure cannot be used in many practical applications, two special electrode designs have been developed by modeling the field distribution and energy absorption and by carrying out test experiments to validate the simulation results.

One solution is based on a two-dimensional surface capacitor providing certain penetration depths and being especially suitable for treating thin structures such as wooden parquet floor. Such an arrangement can be particularly used for pest control even when sensitive surfaces have to be protected. The other solution uses a capacitive coupling between the grounded shielding and an electrode or an equivalent structure (e.g. moist soil) at the other side of the masonry to establish a sufficiently strong electrical field between a “hot” electrode on the side of the shielding and the coupled rear electrode.

Both solutions significantly enhance the application potential of RF heating.

The purpose of this paper is to propose a miniaturized tri-band bandstop filter that finds application in a modern dense communication system where size and multi-band plays a vital role.

In this paper, the authors propose a miniaturized tri-band microstrip bandstop filter which combines the conventional bandstop filter and spur microstrip line structures such that this design achieves tri-band operation at 1.8 GHz and 3 GHz. The overall length of the microstrip filter is found to reduce from 126 to 45 mm because of introduction of spur lines and via-hole grounding. The addition of spur lines replaces two resonators, introduces two additional resonant frequencies and enhances the −6 dB bandwidth of the center frequency by 14 %.The addition of via-holes in each resonator reduces its length into half of its original length, thereby reducing filter size.

Resonance occurs at three different frequencies 1.8, 2.4 and 3 GHz. The filter size reduces from 126 to 45 mm, and the −6 dB rejection bandwidth of center frequency improves by 14 %.

The overall filter size is reduced by 65% and it resonates at three different frequencies 1.8, 2.4 and 3 GHz with an improved bandwidth of 10 % around the center frequency.

The purpose of this paper is to report upon high power, internally matched GaN high electron mobility transistors (HEMTs) at Ku band with 1.5 GHz bandwidth, which employ a simple and cost‐effective lossless compensated matching technique.

Two 4 mm gate periphery GaN HEMTs are parallel combined and internally matched with multi‐section reactive impedance transformers at the input and output networks. The output matching network is designed at the upper frequency of the design band for a flat power of the circuit, while the input matching network is designed at the upper frequency for a flat gain.

With the reactively compensated matching technique, the internally matched GaN HEMTs exhibit a flat saturated output power of 43.2+0.7 dBm and an average power added efficiency of 15 per cent over 12 to 13.5 GHz.

This paper provides useful information for the internally matched GaN HEMTs.

This paper aims to present the design of a compact quad-band coplanar-fed monopole antenna for tablet computer applications.

The antenna has the smallest size of 26 × 14 mm and supports GSM, Wi-Fi, WIMAX and Bluetooth. The proposed antenna consists of a coplanar fed main radiator, c-shaped stubs and parasitic meandered stub. The inverted c-shaped stubs enhance the bandwidth of upper frequencies. The resonance at 2.4 GHz is individually controlled by the coupled meandered stub.

The percentage bandwidth in the four operating bands are 8.7/4.12/27.8/13.3%. Furthermore, the antenna is integrated with the mock-up ground plane and specific absorption rate (SAR) calculations are performed. The estimated SAR is less than 1.6 W/kg for a 1 g body tissue. The gain and efficiency of the antenna are 3.56/4.37/4.97/6 dBi and 82.4/85/97.1/89.3%, respectively. The measured impedance and radiation characteristics of the fabricated prototype are in good correlation with the simulated results.

In the proposed work, vias and lumped elements are not used for lower band excitation, and most of the wireless applications in the tablet computers have been covered. Further, the effect of antenna with different orientation has been tested for the estimation of SAR.

This study aims to investigate consumer acceptance for a set of innovations that can be applied to the production process of extra-virgin olive oil. The final purpose is to verify whether, and to what extent, consumer acceptance of innovations varies depending on the type of technology used and the profile of consumers.

A cross-sectional consumer survey has been carried out in Italy. A structured questionnaire was administered to a national representative sample of individuals who are responsible for grocery shopping (N = 1,003). Consumer acceptance for a set of ten innovations has been measured. Statistical differences between the various measures have been analysed through pairwise comparisons using Wilcoxon's signed-rank test, and subsequent effect sizes have been estimated. A cluster analysis has been also performed to distinguish consumer segments with different response patterns.

The results showed that the type of technology affects significantly the level of consumer acceptance of the tested innovations. In addition, high heterogeneity has been detected among consumer responses, and this leads to identify three consumer segments with different response patterns.

The study is focused on extra-virgin olive oil, which is one of the most important traditional food product in Mediterranean countries. This is the first study where several innovations for extra-virgin olive oil were jointly tested and compared for acceptance through a survey on a nation-wide representative sample of consumers.

In this article, the authors intended to analyze the shielding properties of a fabric frequency selective surface (FSS) structure to the basis of substrate fabric properties. For this purpose, the effect of the properties and structural parameters of the substrate fabric layer were analyzed on the shielding properties of the developed FSS.

The experimental and theoretical evaluations were done at the frequency band of 1,805–1,880 MHz and computer simulation technology (CST) was used in modeling. In experiments were developed the FSS structures by different fabrics as the substrate layers and the copper as the patch cells. The shielding properties of these samples were measured experimentally by the developed setup.

Confirming resonant frequencies, transmission coefficients, and the bandwidths results obtained from modeling and experiments show that the thickness, weight and interweaving structure parameters were affect the porosity of the substrate fabric. Porosity of the fabric moves the resonant frequency due to the changing of the dielectric properties of the fabric. Therefore, shielding properties of the FSS structure were affected by these parameters as the important characteristics of the substrate fabric. In addition, shielding properties of the samples (resonant frequencies and transmission coefficients) in different incident angles are not same in two modes of transverse electric and transfer magnetic.

The experimental results suggest that the introduced flexible FSS structures are suitable for shielding applications in the proposed frequency band.

Runcorn and neighbouring Widnes have strong connections with the beginnings of the chemical industry. Indeed, one of the four companies which merged in 1926 to form Imperial Chemical Industries Ltd (now Imperial Chemical Industries PLC) was Brunner Mond & Company, with manufacturing facilities in Runcorn and today Runcorn remains a major manufacturing centre and headquarters for ICI Chemicals and Polymers. Since its formation, ICI has grown enormously to become a truly international chemical company with over 120,000 employees and manufacturing locations in over 40 countries. Sales total over £11 billion in over 150 countries worldwide. The main business sectors are Petrochemicals and Plastics (20%), General Chemicals (16%), Fibres (6%), Industrial Explosives (3%), Pharmaceuticals (10%), Paints (12%), Agriculture (15%), and Other Effect Products (18%). Sales to principal geographical areas in 1987 were United Kingdom (25%), Continental Europe (25%), The Americas (27%), Australasia, Japan and the Far East (17%), and Indian Subcontinent and others (6%).

The purpose of this paper is to investigate the feasibility of using land grid array (LGA) solder joints as a second-level interconnection option in low-temperature co-fired ceramic (LTCC)/printed wiring board (PWB) assemblies for telecommunication applications. The characteristic behaviour of two commercial lead-free solder materials (Sn4Ag0.5Cu and Sn3Ag0.5Cu0.5In0.05Ni) in reflow processes and thermal cycling tests are also evaluated.

The effect of the reflow temperature profile on voiding in two lead-free solders in LTCC/PWB assemblies was investigated using X-ray and scanning electron microscopy (SEM) investigations. The test assemblies were fabricated and exposed to a temperature cycling test (TCT) in a 0-100°C or −40 to 125°C temperature range. Organic PWB material with a low coefficient of thermal expansion (CTE) was primarily used. In addition, to compare LGA assemblies with low and high global thermal mismatches, an LTCC module/FR-4 assembly was also fabricated and exposed to a TCT in a 0-100°C temperature range. The characteristic lifetime of the test assemblies was determined using DC resistance measurements. The failure mechanisms of the interconnections were verified using scanning acoustic microscopy, SEM and finite element (FE)-SEM investigations.

This work showed that the solderability of AgPt-metallized LTCC modules was poor, resulting in excessive voiding. This problem was avoided by using pre-tinned modules. In the test assemblies, the Sn4Ag0.5Cu joints had a lower void content and a higher characteristic lifetime compared with the Sn3Ag0.5Cu0.5In0.05Ni joints. Furthermore, it was observed that the Sn3Ag0.5Cu0.5In0.05Ni joints were more prone to fail along the interface between the Ag₃Sn layer and the solder matrix than were the Sn4Ag0.5Cu joints. It was assumed that the observed difference in the primary failure mechanisms resulted in the decreased lifetime duration of the SnAgCu-InNi/Arlon in both temperature cycling conditions.

The results proved that the solderability of both solders in AgPt-metallized modules in a typical surface mount technology process was poor; however, the solderability of the test modules can be notably enhanced with pre-tinned pads. This work also demonstrated the effect of the metallization/solder pair on the failure mechanisms and failure rate in LTCC/PWB assemblies with LGA joints; the work also proved in the TCT, over a temperature range of 0-100°C, that using the present LGA joints in LTCC/PWB assemblies with a high global thermal mismatch did not increase the lifetime duration of the joints to the preferred level (3,000 cycles), whereas the performance of these joints was adequate in assemblies with a low global thermal mismatch. Moreover, the results indicated that using the LGA joint configuration enhanced the reliability of the LTCC/PWB assemblies compared with similar assemblies with collapsible ball grid array solder spheres.