Multi-modelling as new estimation schema for high-gain observers

The presented paper proposes a novel method of observer design. A new two-layer observer structure is introduced. The first layer consists of multiple high-gain observers. The latter is built to connect the first layer observers into single one. As the new contribution, the new mapping is defined between an unknown state and measurable outputs allowing to explore new estimation schema. Hence, the proposed method enhances the estimation process for linear and nonlinear systems. Furthermore, it is shown that the introduced observation scheme improves the transients. Illustrative examples are calculated to show the properties of the new observation method.     

Response‐correction‐based fault detection in small linear microstrip patch arrays using magnitude‐only far‐field pattern samples

We present a computationally efficient method for detecting faulty elements in a small linear microstrip patch array from samples of the array's far‐field magnitude radiation pattern (here represented by realistic EM simulations). Regardless of the array size, our method requires only one expensive full‐wave entire‐array simulation—compared to, e.g., the 696 required by the previous best method (Patnaik et al., IEEE Trans Antennas Propag 55 (2007), 775–777) for a 16‐element array. This one simulation gives the accurate far‐field magnitude pattern of the original defect‐free array, and is used in conjunction with the defect‐free array's analytical array factor to formulate a response correction function, which can then be used to construct an accurate approximation of the EM‐simulated pattern of any arbitrary faulty array at very low cost. The low cost and high accuracy of these approximations make possible an enumeration strategy for identifying the faulty elements, which would have been computationally prohibitive were EM‐simulated patterns to be used. Our method was robust in handling arrays of double the size considered in Patnaik et al., IEEE Trans Antennas Propag 55 (2007), 775–777, while expanding on (Patnaik et al., IEEE Trans Antennas Propag 55 (2007), 775–777) by also addressing partial faults and measurement noise. Accuracies in detecting up to three faults (including partial ones) in arrays of 16 and 32 elements exceeded 97% under noise‐free conditions, and were above 93% in the presence of 2 dB measurement noise. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:683–689, 2016.     

Counter-based compaction: An analysis for BIST

According to some recently published results, counter-based compaction outperforms compaction by linear feedback shift registers. These results, however, are based on oversimplified assumptions. In this paper, we discuss an error model to describe the behavior of a faulty circuit under test. We study the three most popular counter-based compaction schemes, (i.e., one's counting, transition counting and edge counting). Using Markov processes we derive equations for iterative computations of exact aliasing probability for any test session length and determine the asymptotic probability of aliasing. For one's counting, we also present a closed form expression that, for any test session length, gives the exact aliasing probability. Finally, we present some examples to compare the aliasing in the counter-based compaction and compaction by a linear feedback shift register. These examples indicate that aliasing by LFSRs is more predictable than aliasing by counters.     

Generalized rectangular finite difference beam propagation method

A method is proposed that allows for significant improvement of the numerical efficiency of the standard finite difference beam propagation algorithm. The advantages of the proposed method derive from the fact that it allows for an arbitrary selection of the preferred direction of propagation. It is demonstrated that such flexibility is particularly useful when studying the properties of obliquely propagating optical beams. The results obtained show that the proposed method achieves the same level of accuracy as the standard finite difference beam propagation method but with lower order Padé approximations and a coarser finite difference mesh.     

Study of the moderate-temperature growth process of optical quality synthetic diamond films on quartz substrates

Growth of undoped and boron-doped diamond films on quartz substrates at moderate temperature of 500 °C by microwave plasma chemical vapor deposition method was studied in terms of growth rate, surface roughness and optical transmittance. Similar density of diamond seed particles on quartz surfaces seeded mechanically before the deposition process and diamond grains within diamond films grown on those substrates is observed. The growth rate is found similar to that reported for diamond deposited on silicon substrates in the same plasma deposition system, although with substantially higher activation energy. Furthermore, increased level of dopant concentration in the gas mixture resulted in a decrease of the growth rate, while a gradual reduction of the surface roughness occurred at high dopant levels. Overall, the highest measured regular optical transmittance of the undoped diamond film on quartz was 45% at 1100 nm (including quartz absorption), whereas that of boron-doped diamond peaked 5% at 700 nm (tail absorption of boron centers).     

Influence of mixed liquor properties and aeration intensity on membrane fouling in a submerged membrane bioreactor at high mixed liquor suspended solids concentrations

This paper presents the results of 195 days of pilot-scale submerged membrane bioreactor (SMBR) experiments on settled municipal wastewater. Short-term and long-term thickening experiments were performed at a constant membrane flux of 30L/(m(2)h) to determine the impact of the following mixed liquor properties: colloidal material, soluble COD, soluble microbial products, extracellular polymeric substances, and viscosity along with aeration intensity on membrane fouling at high mixed liquor suspended solids (MLSS) concentrations. The normalized permeability declined with increasing MLSS concentrations in all experiments and increasing the coarse bubble aeration intensity increased the permeability at a given MLSS concentration. Using a dynamic approach, this work demonstrates the importance of mixed liquor viscosity, which impacts the efficacy of the coarse bubble aeration, in sustaining membrane permeability. Over an extended thickening time period, a small increase in MLSS concentration and mixed liquor viscosity becomes more prevalent and leads to greater permeability decline at a given MLSS concentration.     

The True Amphipathic Nature of Graphene Flakes: A Versatile 2D Stabilizer

The fundamental colloidal properties of pristine graphene flakes remain incompletely understood, with conflicting reports about their chemical character, hindering potential applications that could exploit the extraordinary electronic, thermal, and mechanical properties of graphene. Here, the true amphipathic nature of pristine graphene flakes is demonstrated through wet-chemistry testing, optical microscopy, electron microscopy, and density functional theory, molecular dynamics, and Monte Carlo calculations, and it is shown how this fact paves the way for the formation of ultrastable water/oil emulsions. In contrast to commonly used graphene oxide flakes, pristine graphene flakes possess well-defined hydrophobic and hydrophilic regions: the basal plane and edges, respectively, the interplay of which allows small flakes to be utilized as stabilizers with an amphipathic strength that depends on the edge-to-surface ratio. The interactions between flakes can be also controlled by varying the oil-to-water ratio. In addition, it is predicted that graphene flakes can be efficiently used as a new-generation stabilizer that is active under high pressure, high temperature, and in saline solutions, greatly enhancing the efficiency and functionality of applications based on this material.     

Energy Level Alignment at Metal/Solution‐Processed Organic Semiconductor Interfaces

Energy barriers between the metal Fermi energy and the molecular levels of organic semiconductor devoted to charge transport play a fundamental role in the performance of organic electronic devices. Typically, techniques such as electron photoemission spectroscopy, Kelvin probe measurements, and in‐device hot‐electron spectroscopy have been applied to study these interfacial energy barriers. However, so far there has not been any direct method available for the determination of energy barriers at metal interfaces with n‐type polymeric semiconductors. This study measures and compares metal/solution‐processed electron‐transporting polymer interface energy barriers by in‐device hot‐electron spectroscopy and ultraviolet photoemission spectroscopy. It not only demonstrates in‐device hot‐electron spectroscopy as a direct and reliable technique for these studies but also brings it closer to technological applications by working ex situ under ambient conditions. Moreover, this study determines that the contamination layer coming from air exposure does not play any significant role on the energy barrier alignment for charge transport. The theoretical model developed for this work confirms all the experimental observations.     

Design of low‐loss directional couplers with compensated coupled‐line sections in suspended microstrip technique

Design of coupled line 3dB directional couplers realized in suspended microstrip technique has been presented. The main goal was to minimize the insertion losses of the coupler, what has been achieved by a proper choice of the realization technique. As the chosen coupled line geometry is asymmetric to achieve good electrical performance of the resulting coupler, capacitive compensation technique has been utilized to equalize capacitive and inductive coupling coefficients. Furthermore, a distributed‐element approach has been investigated for realization of compensation capacitances, due to their physical size resulting from the dielectric structure. The proposed coupler has been designed in two versions, having center frequencies equal to 0.89 and 1.1 GHz, manufactured and measured. The measurement results show good agreement with electromagnetic analyses and prove the correctness and usefulness of the presented design method. The manufactured couplers exhibit insertion losses as low as 0.08 dB at the center frequency.