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A new dual band 4 x 4 butler matrix with dual band 3dB quadrature branch line coupler and dual band 45° phase shifter
摘要： A new dual band 4 × 4 butler matrix (BM) without crossover has been proposed, implemented and analyzed in this paper. A new dual band 45° phase shifter has also been proposed. The dual band BM, dual band 3dB quadrature branch line coupler (BLC) and dual band 45o phase shifter have been designed using Keysight Technologies’ Advanced Design System (ADS) software and implemented on the Rogers 2.33, having a thickness of 0.787 mm for 1.0 GHz and 2.5 GHz operating frequencies. Before the implementation of the proposed BM, the dual band 3dB quadrature BLC and dual band 45° phase shifter have been designed, implemented and analyzed. The proposed dual band 4 × 4 BM has been developed by placing four dual band 3dB quadrature BLCs and two dual band 45° phase shifters at their appropriate positions. Circuit parameters variation of the proposed BLC, phase shifter and BM with frequency ratios have been studied in this paper. The measured and simulated results of the dual band BM validated the design methodology. A performance analysis comparing the proposed BM with the existing butler matrices has also been carried out.
关键词： branch line coupler,Butler matrix,dual band,impedance transformer,45o phase shifter,advanced design system
更新于2025-09-23 15:21:21
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Multi-fidelity EM simulations and constrained surrogate modelling for low-cost multi-objective design optimisation of antennas
摘要： In this study, a technique for low-cost multi-objective design optimisation of antenna structures has been proposed. The proposed approach is an enhancement of a recently reported surrogate-assisted technique exploiting variable-fidelity electromagnetic (EM) simulations and auxiliary kriging interpolation surrogate, the latter utilised to produce the initial approximation of the Pareto set. A bottleneck of the procedure for higher-dimensional design spaces is a large number of training data samples necessary to construct the surrogate. Here, the authors propose a procedure that allows us to confine the model domain to the subset spanned by the reference points, including the extreme Pareto-optimal designs obtained by optimising the individual objectives as well as an additional design that determines the Pareto front curvature. Setting up the surrogate in the constrained domain leads to a dramatic reduction of the required number of data samples, which results in lowering the overall cost of the optimisation process. Furthermore, the model domain confinement is generic, i.e. applicable for any number of design goals considered. The proposed technique is demonstrated using an ultra-wideband monopole antenna optimised with respect to three objectives. Significant reduction of the design cost is obtained as compared to the reference surrogate-assisted algorithm.
关键词： Pareto set,antenna structures,variable-fidelity EM simulations,kriging interpolation surrogate,multi-objective design optimisation,ultra-wideband monopole antenna
更新于2025-09-23 15:21:21
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Simulated performance analysis of a solar aided power generation plant in fuel saving operation mode
摘要： Solar aided (coal-fired) power generation (SAPG) system has been proved to be an efficient way to utilize the solar energy for power generation. Due to the instability of the solar radiation, a SAPG system generally operates under transient working conditions. In this paper, performance simulation sub-models of main components in a SAPG plant are established based on the lumped parameter assumption. A 330 MW SAPG power plant as a case study is simulated. The variations of the performances, main parameters of the plant with the solar field heat output and the dynamic responses under a typical day are analyzed. The results show that when the heat output of the solar field changes from 0 kJ/h to 2.13 × 108 kJ/h, the coal saving rate will increase to 6.4%, and the solar power generation share (the proportion of the power from the solar energy to the total power from the SAPG plant) will increase to 7.74%. During the analysis process, in order to optimize the solar field, the concept of the solar field equivalent efficiency (SFEE) is proposed and the optimal velocity of heat transfer fluid (HTF) in absorber tube is obtained.
关键词： Optimize design,Dynamic responses,Solar aided coal-fired power generation,Parameter variation
更新于2025-09-23 15:21:21
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Simple imaging for the diamond anvil cell: Applications to hard-to-reach places
摘要： The employment of high-pressure gases as a pressure-transmitting medium, sample, or reactant for diamond anvil cell experiments is widespread. As a pressure transmitter, high-pressure gases are crucial to forming quasi-hydrostatic compression atmospheres for samples inside the uniaxially driven cell. We describe an optical design for forming high-resolution images of the gasket and sample chamber of the diamond anvil cell under high gas pressures in a gas loading apparatus. Our design is simple, is of low-cost, and may be easily adapted to suit gas loading apparatus of any design, as well as other common hard-to-reach environments in diamond anvil cell experiments, i.e., those with large stand-off distances, such as cryostats.
关键词： optical design,high-pressure gases,gas loading apparatus,diamond anvil cell,imaging
更新于2025-09-23 15:21:21
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Raman spectroscopy combined with advanced chemometric methods: A new approach for detergent deformulation
摘要： Deformulation of a commercial surfactant mixture using RAMAN spectroscopy and advanced chemometric tools have been investigated. Since the use of surfactants is drastically expanding, their fine identification and quantification are required for quality control and regulation. Dilution of the detergent mixtures combined with RAMAN spectroscopy for signal extraction tools allowed the extraction of the first information concerning the composition of the mixture. The raw materials identified were thus used in an experimental design to obtain a robust model for the determination of detergent composition. The combination of chemometric tools (Independent Component Analysis and Partial Least Square) and spectroscopic methods provided pertinent information for detergent composition. This methodology can easily be transposed to the industrial world.
关键词： detergents deformulation,RAMAN spectroscopy,surfactants characterization,design of experiments,Chemometrics,blind source separation methods
更新于2025-09-23 15:21:21
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Mathematical optimisation of location and design of windows by considering energy performance, lighting and privacy of buildings
摘要： Purpose – The Middle East and North Africa (MENA) region is known for its extreme weather conditions during Summer. A major determinant of the sustainability of the design of a building is its fenestrations. The purpose of this paper is to explore the problem of designing and locating windows on building facades such that a number of relevant criteria to the MENA region are optimised, including solar heat gain, privacy, daylighting and cost of installation. Design/methodology/approach – A multi-objective optimisation problem is proposed with the focus on capturing the requirements of residential dwellings in the MENA region. Since the problem contains conflicting objectives that need to be optimised, a lexicographic approach is adopted. In order to display the Pareto curve, a bi-objective analysis based on the ε-constraint method is utilised. Findings – The conflicting nature of the proposed problem is indicated via the Pareto optimal solutions yielded. Depending on the preference of criteria adopted in lexicographic optimisation, the location of the windows on the building fa?ade tends to change. The bi-objective analysis indicates the importance of balancing out the daylight factor against each of privacy, solar heat gain and installation cost criteria. Furthermore, an analysis conducted in three major cities in the MENA region highlights the discrepancy in design alternatives generated depending on the local climatic condition. Originality/value – This work proposes a novel mathematical optimisation model which focuses on producing a sustainable design and layout for windows on the facades of residential dwellings located in the MENA region. The proposed model provides designers with guidance through an automated support tool that yields optimised window designs and layout to ensure the sustainability of their designed buildings.
关键词： Window location,Pareto curve,Mathematical optimization,Window design,Multi-objective,Mixed integer programming
更新于2025-09-23 15:21:21
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[IEEE 2018 IEEE MTT-S International Conference on Numerical Electromagnetic and Multiphysics Modeling and Optimization (NEMO) - Reykjavik, Iceland (2018.8.8-2018.8.10)] 2018 IEEE MTT-S International Conference on Numerical Electromagnetic and Multiphysics Modeling and Optimization (NEMO) - Low-Cost Simulation-Driven Design of Broadband Rectifiers for Ambient RF Energy Harvesting
摘要： A steady growth of ambient RF energy density associated with a rapid increase of the number of broadcasting devices stimulates the research on broadband harvesting circuits. Such circuits can be used as energy sources for low-power sensors or Internet-of-Things devices. On the other hand, dedicated design techniques for rectifiers are lacking which results in poor performance of existing circuits. Also, their design cost is high because it involves hybrid electromagnetic (EM) and harmonic balance (HB) simulations. In this work, we propose a novel design procedure for low-cost design of broadband rectifiers. The core component of the approach is a novel equivalent-circuit-based low-fidelity model which does not involve harmonic balance (HB) simulations. The model consists of a matching circuit loaded with the RF-to-DC converter block represented using the S-parameter matrix. The latter is obtained from a single HB simulation of the converter circuit. Inaccuracy of the model is reduced using appropriate correction techniques. At the first stage of the design process, the proposed model is optimized for minimization of the in-band reflection. At the second stage, a hybrid HB-EM-based tuning oriented towards maximization of the structure efficiency is carried out. The proposed approach is demonstrated using a novel broadband rectifier operating within 0.5 GHz to 3.5 GHz band. Numerical cost of the method is 80% lower compared to direct EM-HB- based optimization of the rectifier circuit.
关键词： broadband rectifiers,constrained optimization,simulation-driven design,surrogate-based optimization,equivalent circuit model
更新于2025-09-23 15:21:21
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[IEEE 2018 VII. Lighting Conference of the Visegrad Countries (Lumen V4) - Trebic, Czech Republic (2018.9.18-2018.9.20)] 2018 VII. Lighting Conference of the Visegrad Countries (Lumen V4) - The Floodlighting Design System Based on the Object's Daytime Photography
摘要： The article presents a solution to the problem of work and time consuming of the objects floodlighting projects creation. Currently, the only technically correct methods for creating such projects are a three-dimensional computer simulation using photometric files of luminaires or field trials using real equipment. Both of these methods have their advantages, but also many disadvantages. Among architects, in turn, a popular method of floodlighting designing is graphic processing of daytime or evening images objects. The method is relatively fast and it gives photorealistic effects but it is technically incorrect. An architect or graphic designer creates a picture that is attractive to the eye, but usually has nothing to do with reality. This is due to the fact that the lighting parameters of both lighting equipment and analyzing this type of project in terms of technology are not taken into account. The article presents a solution to this problem. It describes a system created especially for this purpose based on a dedicated computer application that allows simulation of the object floodlighting using its daily photograph. This is technically correct simulation, because it uses photometric files of luminaires. The system allows correction of basic photometric parameters: editing of photometric files, luminous flux, light in different directions, color temperature and the use of color filters. The computer application also enables photo editing, geometric correction, measurement and defining reflection and transmission properties of materials from which the object is actually built. Full lighting analysis is also possible and is based on luminance and illuminance distributions generated in the false color scale and measurements in points and selected areas. The advantages, disadvantages and limitations of the developed system are presented.
关键词： luminance distribution,visualization,floodlighting,advanced lighting simulation,lighting design
更新于2025-09-23 15:21:21
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[IEEE 2018 VII. Lighting Conference of the Visegrad Countries (Lumen V4) - Trebic (2018.9.18-2018.9.20)] 2018 VII. Lighting Conference of the Visegrad Countries (Lumen V4) - Lighting Design Using Ray Tracing
摘要： This article describes lighting system design using ray tracing. This method can be applied in cases where calculation includes non-diffuse reflective materials, light sources have dimensions comparable to distances from reflective materials and also in case where diffused reflective surfaces influence each other in terms of distribution of light.
关键词： illumination,luminaire,ray tracing,lighting system design
更新于2025-09-23 15:21:21
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Cyanide degradation in aqueous solution by heterogeneous photocatalysis using boron-doped zinc oxide
摘要： The photocatalytic activity of boron-doped ZnO with varying concentration (1, 1.5 and 2% wt of B) synthesized by sol-gel method was evaluated on cyanide (CN-) degradation in aqueous solution under simulated solar radiation. The obtained catalysts were characterized by XRD, UV-Vis/DRS, ICP-OES, FT-IR, and XPS. The photocatalytic experiments were carried out in a quartz batch reactor using 300 mL of cyanide solution adjusted at pH 11, evaluating different parameters such as the amount of B dopant, catalyst loading and initial concentration of cyanide solution. A 23 central composite faced design was used to maximize CN- photocatalytic degradation. The cyanide concentration was measured by ISE potentiometric method and the content of intermediate ions (OCN?, NO3?, and NH4+) was determined by UV-visible spectrophotometry. The boron incorporation into ZnO lattice (ZnO-B) reduced wurtzite crystallite size (25 nm) and narrowed band gap (3.0 eV) compared to bare ZnO (43 nm and 3.2 eV, respectively). The ZnO-B 1.5 wt% showed better photocatalytic performance by degrading 89% of a 10 mg L-1 CN- solution compared to 75% that was reached by undoped ZnO; using in both cases 1.4 g L-1 of catalyst loading at accumulated energy of 400 kJ m-2.
关键词： central composite faced design,ZnO-B,sol-gel,cyanate,cyanide
更新于2025-09-23 15:21:21