On Changing the Impedance of a Reactive Surface Using Magneto-static Responsive Particles

Low efficiency and poor stability are two major obstacles limiting the manufacturing of renewable and cost-effective polymer solar cell (PSCs). To address these problems, solution-processed poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) doped with Fe3O4 magnetic nanoparticles ((PEDOT:PSS):Fe3O4), and above (PEDOT:PSS):Fe3O4 thin film aligned by an external magnetostatic field ([(PEDOT:PSS):Fe3O4] W/H) were used as the anode buffer layer for PSCs, respectively. As compared with PSCs with PEDOT:PSS as an anode buffer layer, 38.5% enhanced efficiency and twice improved stability are observed from PSCs incorporated with [(PEDOT:PSS):Fe3O4] W/H anode buffer layer. It was found that enhanced efficiency and improved stability resulted from a combination of reduced acidity of PEDOT:PSS and enhanced electrical conductivity that originated from generated counterions and the paramagnetism of Fe3O4 magnetic nanoparticles by an external magnetostatic field.

Three methods for measuring the acoustic properties of bulk materials have been evaluated. The methods differ from one another in their practical implementation and reliability. The two more convenient methods exploit changes in surface impedance of test samples resulting from a change in the test sample geometry or boundary conditions. The results from these surface methods are compared with that obtained using Scott’s method. In Scott’s method the propagation constant is obtained by a ‘‘direct’’ measurement inside the test material by means of a probe tube. The comparisons suggest that the surface methods will provide reliable and accurate results when the test sample behaves as a rigid porous structure.

Two methods for extraction of the effective tensor surface impedance representing metasurfaces with printed elements and arbitrary geometry are presented. The surface impedance can be modelled as a shunt admittance on a transmission line. The extracted surface impedance combined with transmission line theory enables to compute easily and efficiently the transmission coefficient through a multilayer metasurface structure. The metasurface modelling as a shunt admittance enables to conduct a multi‐parameter study on the transmission and reflection performance through the metasurface structure. The results of the proposed methods are compared, and very good agreement was obtained up to 30° incident angle. Beyond 30° it is suggested to recalibrate the model or upgrade it. For model validation purposes, a 2D flat lens antenna with patch elements loaded with capacitors was designed, fabricated, and measured. Simulation and experimental results of the lens near and far‐field are presented.

We report, for the first time, the effect of a solution-processed Fe3O4 magnetic nanoparticle (MNP) thin film and a Fe3O4 MNP thin film aligned by an external magnetostatic field, used as a hole extraction layer (HEL), respectively, in polymer solar cells (PSCs). The thin film of a Fe3O4 MNP shows a smoother surface, better transparency, and higher electrical conductivity than that of a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) thin layer. Moreover, the thin film of a Fe3O4 MNP aligned by an external magnetostatic field possesses an enhanced electrical conductivity and lower internal series resistance, thus leading to greater than 13% enhancement in the power conversion efficiency of PSCs than those using a PEDOT:PSS thin film. It was also found that PSCs incorporated with a Fe3O4 MNP shows better stability compared with those using PEDOT:PSS as an anode buffer layer. These results demonstrated that utilization of a Fe3O4 MNP as a HEL in PSCs blazes a trail to achieve highly efficient and long-time-stable devices.

Reflection of an acoustic line source by an impedance surface with uniform flow

A breadboard model of a new source of high-stable oscillations - diffraction radiation generator (DRG) with local magnetostatic non-uniformity (LMN) in the interaction space - has been developed. DRG (LMN) operates in the wide frequency range with enhanced frequency stability. Output power is 8W (and more) at accelerating voltage up to 2.5kV in the continuous mode, and it is quite stable to variations of the profile of the external focusing magnetostatic field (FMF).

In the ACF packaging process, a bonding force will be applied to the ACF structure. The finite element analysis is used to simulate the ACF packaging process. Material behavior is assumed to be superelastic for resin, viscoelastic for polymer matrix, and elastic‐plastic for metal, such as bump, pad, chip, and Au‐film. The axis‐symmetric model is employed in FEA simulation with time‐varying bonding force and operating temperature. In this study, the parameters, including conductive particle diameter, Au‐film thickness, and bonding force, are analyzed with nonliner and temperature‐dependent material properties. The simulation results indicate that bonding force and operating temperature have strong effects on the formation of concave on Au‐film. In addition, surface wrinkle of Au‐film will be induced by the bonding force. Both of the concaving and the wrinkling on Au‐film will decrease the contact area between the conductive particle and the bump and the contact area between the conductive particle and the pad. Decrease of the contact area means increase of the total resistance for the ACF structure. The results show that the smaller the conductive particle diameter, the smaller the contact area. Generally, increasing the thickness of Au‐film will decrease the contact areas, except at the Au‐film thickness of 0.05 μm.

The resonances of an axially magnetised plasma column with hollow and perfectly conducting cores have been investigated using the quasistatic approach. It is found that the two resonances of a hollow plasma cylinder are shifted, but the single resonance of a plasma cylinder with a perfectly conducting core is split into three if an external magnetostatic field is impressed in the axial direction.

Transmission lines are an important part of a power system. Transmission lines have high power transmission capacity and they are prone to faults of larger magnitudes. Various faults occur in transmission lines. Therefore, protection relays are necessary to protect transmission lines. The purpose of protection system is to interrupt the faulty section from the healthy section because the fault currents may damage the electrical equipments. One of the protection relays is distance relay and it is mainly used in transmission line. Sometimes these relay are used for backup protection. Distance relays for determining the impedance need the voltage and current. Transmission lines are typically protected by distance protection relay. Distance relays are considered of high speed class and can provide transmission lines. Nowadays, numerical distance relays have been used instead of using electromechanical and static distance relays. The proposed model was verified under different tests such as single line to ground (L-G) fault, double line to ground (L-L-G) fault, line to line (L-L) fault and three phase (L-L-L) fault. SimPower System was used for modelling and simulation of distance relay, transmission lines and faults. The simulation results were obtained from MATLAB software shows the feasibility of analysis of transmission line protection with mho type distance relay for single line to ground fault, double line to ground fault, line to line fault and three phase fault at different location of transmission lines. The difficulties understanding on operation of distance relay can be cleared by using MATLAB/SIMULINK software.

In-situ method for monitoring layered hydraulic impedance development during artificial recharge with turbid water

We have fabricated absorber-coupled microwave kinetic inductance detector (MKID) arrays for sub-millimeter and farinfrared astronomy. Each detector array is comprised of λ/2 stepped impedance resonators, a 1.5μm thick silicon membrane, and 380μm thick silicon walls. The resonators consist of parallel plate aluminum transmission lines coupled to low impedance Nb microstrip traces of variable length, which set the resonant frequency of each resonator. This allows for multiplexed microwave readout and, consequently, good spatial discrimination between pixels in the array. The Al transmission lines simultaneously act to absorb optical power and are designed to have a surface impedance and filling fraction so as to match the impedance of free space. Our novel fabrication techniques demonstrate high fabrication yield of MKID arrays on large single crystal membranes and sub-micron front-to-back alignment of the microstrip circuit.

Summary form only given, as follows. Surface impedance boundary conditions (SIBC) for superconductor layers are provided. These can be used for arbitrary thick conductors from very thin to very thick. A superconducting layer is considered as a TEM transmission line so that the SIBCs can be obtained as the input impedances of an open ended and a short circuited transmission line, respectively. The SIBCs are verified for a microstrip line and a coplanar waveguide made of Niobium on a LaAlO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> substrate.

This article examines the design of a small Ultra-Wideband (UWB) antenna with an adjustable bandwidth, center frequency, and rectangular notch within a Wireless Local Area Network (WLAN) band for relocation to the worldwide interoperability for microwave access (WiMAX) band. The antenna's UWB properties are obtained by truncating the lower ends of a square microstrip patch, while the notch characteristic is achieved through an Electromagnetic Bandgap (EBG) structure. The mushroom-like EBG structure comprises five square metallic conductor patches loaded onto the back of the substrate and linked to the ground plane through shorting vias. When strips of graphene material are embedded in the EBG structure, the rectangular notch’s bandwidth and center frequency can be adjusted to suit applications with on-demand rejection bands electronically. The surface impedance of graphene is modified by adding a direct current voltage bias, which allows the material's surface impedance to be set to one of two extreme values corresponding to the ON and OFF states of typical switches. The simulation results indicate that the suggested antenna operates from 2.4 to 15.5 GHz for input reflection coefficient less than −10 dB. Based on its graphene characteristic, a reconfigurable rectangular notch moving between the two bands 5.1 to 5.8 GHz and 3.2 to 3.7 GHz is achieved, effectively denying WLAN and WiMAX band transmissions, respectively. Furthermore, the same graphene characteristics can be used to control the ON/OFF notch inside the WLAN band. Finally, the antenna has additional advantages: compact size (32×48×0.8 mm3), stable gain, and consistent radiating pattern.

In this paper, the use of a cavity‐backed Hilbert surface as an efficient slot‐like narrowband radiating aperture is suggested, to exploit its own unique electromagnetic characteristics in the context of radio frequency identification (RFID) applications. The proposed meta‐slot antenna (MSA) consists of a Hilbert surface window (HSW) made of a cascade of space‐filling slot inclusions of order three and backed by a very shallow cavity that contributes to its surface impedance and radiation characteristics. A straight longitudinal microstrip line printed on a thin, low permittivity substrate, whose ground plane includes the HSW, feeds the aperture through distributed electromagnetic coupling. As illustrated by simulation results and measurements, the antenna behaves as a magnetic current sheet over a ground plane, with a highly frequency‐selective impedance response and unidirectional radiation pattern. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2577–2581, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21995

A novel methodology for designing and applying artificial magnetic conductor (AMC) through controlling pattern’s surface impedance instead of shape is proposed and analyzed. A wideband metamaterial radar absorber applying this methodology is designed and verified numerically. Simulation results indicate this methodology can be used to widen absorption bandwidth for metamaterial radar absorbers.