Surrogate‐assisted EM‐driven miniaturization of wideband microwave couplers by means of co‐simulation low‐fidelity models

This article proposes a methodology for rapid design optimization of miniaturized wideband couplers. More specifically, a class of circuits is considered, in which conventional transmission lines are replaced by their abbreviated counterparts referred to as slow‐wave compact cells. Our focus is on explicit reduction of the structure size as well as on reducing the CPU cost of the design process. For the sake of computational feasibility, a surrogate‐based optimization paradigm involving a co‐simulation low‐fidelity model is used. The latter is a fundamental component of the proposed technique. The low‐fidelity model represents cascaded slow‐wave cells replacing the low‐impedance lines of the original coupler circuit. It is implemented in a circuit simulator (here, ADS) and consists of duplicated compact cell EM simulation data as well as circuit theory‐based feeding line models. Our primary optimization routine is a trust‐region‐embedded gradient search algorithm. To further reduce the design cost, the system response Jacobian is estimated at the level of the low‐fidelity model, which is sufficient due to good correlation between the low‐ and high‐fidelity models. The coupler is explicitly optimized for size reduction, whereas electrical performance parameters are controlled using a penalty function approach. The presented methodology is demonstrated through the design of a 1‐GHz wideband microstrip branch‐line coupler. Numerical results are supported by experimental validation of the fabricated coupler prototype.     

Durability and surface chemistry of horizontally aligned CNT films as electrodes upon electrolysis of acidic aqueous solution

We devised a simple and effective method of electrochemical functionalization of horizontally aligned CNT films in diluted HCl and H₂SO₄ solutions upon their electrolysis under a constant current mode. We were able to cause notable generation of carbon–oxygen and carbon–chlorine functional groups on the CNT film anodes as proven by EDX, XPS, and Raman spectroscopy. As a consequence, we observed significant changes of the morphology of the material under electron microscopy, what translated into improved compatibility of CNTs with hydrophilic media. In turn, application of CNT films as cathodes was found as a powerful tool for a thorough cleaning of the nanotubes. Finally, we demonstrated that by the selection of appropriate conditions, CNT films can act as easy-to-make and flexible electrodes with a high stability and performance superior to graphite for generation of non-oxidizing gases such as hydrogen from solution. CNT film electrodes are two orders of magnitude lighter and require much lower overpotential for faradaic splitting of water.     

Calculation of the internal thermal resistance and ampacity of3-core screened cables with fillers

All 3-core cables require fillers to fill the space between insulated cores and the belt insulation or a sheath. The equations given in IEC 287 and in the Neher-McGrath paper (1957) for the internal thermal resistance of 3-core cables were developed for paper insulated cables. For such cables, it was assumed that the insulation and filler materials have the same thermal resistivities. In reality, in 3-core cables a variety of materials are used as fillers. The majority of these will have a higher thermal resistivity than the insulation. In the previous paper, a new formula was developed to compute the value of the internal thermal resistance of belted cables taking into account the thermal resistivity of the filler. In this paper, screened cables are considered and a new formula for the computation of the internal thermal resistance of such cables is presented. The effect of filler resistivity on cable ampacity is also discussed     

Accurate design‐oriented simulation‐driven modeling of miniaturized microwave structures

One of the important prerequisites for efficient design optimization of microwave structures is availability of fast yet reliable replacement models (surrogates) so that multiple evaluations of the structure at hand can be executed in reasonable timeframe. Direct utilization of full‐wave electromagnetic (EM) simulations for handling optimization‐related tasks is often prohibitive. A popular approach to construction of fast surrogates is data‐driven modeling. Unfortunately, it normally requires a large number of training samples, and it is virtually infeasible for structures that exhibit highly nonlinear responses (e.g. filters or couplers). In this work, a design‐oriented modeling technique is proposed where good accuracy is achieved by careful non‐uniform design space sampling that accounts for nonlinear relationship between the operating frequency of the structure and its geometry parameters, as well as carrying out the modeling process only for selected characteristic points of the structure responses (those that determine satisfaction/violation of given design specifications). Our approach is demonstrated using a miniaturized microstrip rat‐race coupler modeled in a wide range of geometry parameters and compared to conventional data‐driven modeling using kriging interpolation. Design optimization examples are also provided. Copyright © 2016 John Wiley & Sons, Ltd.     

Benzene-induced hydro(solvo)thermal synthesis of Cu and Zn coordination polymers based on 1,3-benzenedicarboxylate

Hydro(solvo)thermal reactions of Cu(NO₃)₂·2.5H₂O or Zn(NO₃)₂·6H₂O with 1,3-H₂bdc provided two structurally different coordination polymers; a 2D network “metallacalixarene” based on the paddlewheel-type cluster with the formula [Cu(1,3-bdc)·H₂O]·H₂O (1) and a 3D framework [Zn(1,3-bdc)] (2), respectively. The use of a base was unnecessary in this synthesis; however, the presence of benzene played a crucial role in the crystallization of the desired products and could act as a template molecule in the synthesis of polymer (1). The unsaturated apical sites in the Cu₂ cluster of polymer (1) were occupied by water molecules, what consequently led to the structural decomposition of the framework after exposing the sample in air, which was not the case of the Zn-coordination polymer (2).     

丝网印刷聚酰亚胺晶圆保护

适用性 使用丝网印刷的方法对晶圆表面施涂聚酰亚胺保护层相对于传统的旋转-蚀刻工艺技术具有效率和成本的优势.丝网印刷晶圆表面保护只需要两步工序(印刷和固化),而旋转-蚀刻工艺需要七步或更多的工序.     

DNA-PK is essential only for coding joint formation in V(D)J recombination

The analysis of the role of DNA-dependent protein kinase (DNA-PK) in DNA double-strand break repair and V(D)J recombination is based primarily on studies of murine scid, in which only the C-terminal 2% of the protein is deleted and the remaining 98% is expressed at levels that are within an order of magnitude of normal. In murine scid, signal joint formation is observed at normal levels, even though coding joint formation is reduced over three orders of magnitude. In contrast, a closely associated protein, Ku, is necessary for both coding and signal joint formation. Based on these observations, a reasonable hypothesis has been that absence of the DNA-PK protein (rather than merely its C-terminal 2% truncation) would ablate signal joint formation along with coding joint formation. In fact, a study of equine SCID, in which there is a much larger truncation of the DNA-PK protein, has suggested that signal joints do fail to form. In our current study, we have analyzed signal and coding joint formation in a malignant glioma cell line, M059J, which was previously shown to be deficient in DNA-PK. Our quantitative analysis shows that full-length protein levels are reduced at least 200-fold, to a level that is undetectable, yet signal joint formation occurs at wild-type levels. This result demonstrates that at least this form of non-homologous DNA end joining can occur in the absence of DNA-PK.     

Reducing average and peak temperatures of VLSI CMOS circuits by means of evolutionary algorithm applied to high level synthesis

In this paper an adaptive evolutionary algorithm (AEA) for high-level synthesis, resulting in reduction of the power dissipation in CMOS circuits is presented. It enables us to design contemporary electronic circuits/systems with minimisation of the peak and average power consumption, which leads to reduction of the peak and average temperature of the designed chip. Therefore, the reliability of the integrated circuit (IC) can be improved. The results of experiments carried out for the chosen benchmark circuits show that the achieved reduction of power consumption varies from 4 to 52%.