Two-Element Biomimetic Antenna Array Design for Power Extraction / Phase Amplification Tradeoff

The inertia plays a significant role in the response of a system undergoing flow-induced vibrations, which has been extensively investigated by previous researchers. However, the inertial effects of an energy harvester employing the mechanism of flow-induced vibrations have attracted little attention. This paper concentrates on a semi-passive energy extraction system considering its inertial effects. The incompressible Navier-Stokes equations are solved using a finite-volume based numerical solver with a moving grid technique. A partitioned method is used to couple the fluid and structure motions with the sub-iteration technique and an Aitken relaxation, which guarantees a strong fluid-structure coupling. In addition, a fictitious mass is added to resolve the numerical instability aroused by low density ratios. First, at a fixed mass ratio of r = 1, we identify an optimal set of parameters, at which a maximum efficiency of η = 34% is achieved. Further studies with r ranging from 0.125 to 100 are performed around the optimal parameters. The results show that for the semi-passive flapping energy harvester, the energy harvesting efficiency decreases monotonically with increasing mass ratio. We also notice that the total power extraction stays at a high level with little variation for r < 10; therefore, if we concern more about the amount of power extraction rather than its efficiency, the inertial effects can be neglectable for r < 10. Moreover, since one degree of freedom is released for the semi-passive system, it is possible for the system to automatically determine its optimal operational parameters. We note that the optimal phase difference ϕ = 82° has been well determined, which leads to a good timing of vortex-foil interactions. We note two different trends on phase difference for the effects of reduced frequency and mass ratio, respectively. By varying the reduced frequency f∗, an optimal f∗ is identified, at which the minimum phase difference is achieved. While the relationship between phase difference and mass ratio is monotonic, a maximum phase difference is achieved at the nearly zero mass ratio. Nevertheless, both trends point to the same optimal phase difference, i.e., ϕ = 82° at θ0 = 75°. Furthermore, the relationship between the leading edge vortex and the phase difference is systematically investigated, accounting for the physical reason of existence of the optimal phase difference.

Multi-stage collaborative planning of electricity-hydrogen-transportation coupling network considering carbon emission reduction

Influence of stroke deviation on the power extraction performance of a fully-active flapping foil

A novel sub-harmonic injection-locked balanced oscillator is proposed. The circuit provides two outputs with a 180° phase difference by employing a transmission line section for impedance transformation to meet the oscillation conditions. A coupling network is connected at the mid-point of the transmission line to inject the sub-harmonic frequency. This eliminates the need for a circulator or balun. The circuit is small and consumes low DC power. Under the locking state, the circuit provides double the injection frequency and also the phase noise of the two outputs is substantially improved.

In this paper, modified circuit topologies of a differential voltage-controlled oscillator (VCO) and a quadrature VCO (QVCO) in a standard bulk 90-nm CMOS process are presented for low dc power and low phase-noise applications. By utilizing current-reuse and transformer-feedback techniques, the proposed VCO and QVCO can be operated at reduced dc power consumption while maintaining extraordinary circuit performance in terms of low phase-noise and low amplitude/phase errors. The VCO circuit topology is investigated to obtain the design procedure. The VCO is further applied to the QVCO design with a bottom-series coupling technique. The coupling network between two differential VCOs and device size are properly designed based on our proposed design methodology to achieve low amplitude and phase errors. Moreover, the VCO and the QVCO are fully characterized with amplitude and phase errors via a four-port vector network analyzer. With a dc power of 3 mW, the VCO exhibits a frequency tuning range from 20.3 to 21.3 GHz, a phase noise of - 116.4 dBc/Hz at 1-MHz offset, a figure-of-merit (FOM) of -198 dBc/Hz, a phase error of 3.8° , and an amplitude error of 0.9 dB. With a dc power of 6 mW, the QVCO demonstrates a phase noise of -117.4 dBc/Hz, a FOM of -195.6 dBc/Hz, a phase error of 4° , and an amplitude error of 0.6 dB. The proposed VCO and QVCO can be compared with the previously reported state-of-the-art VCOs and QVCOs in silicon-based technologies.

A design method is presented for a uniform array made of half‐wavelength dipoles placed in parallel with the mutual coupling between elements taken into account. In the design, the induced electromotive force method is used. By using the variations of the input impedance and the current due to change of the element length, the desired current value is approached. In addition, the reactance component of the input impedance is suppressed. Numerical calculations by the moment method are carried out with the obtained element length. The results are confirmed and also verified by experiment. The experimental results demonstrate that the proposed design method is useful. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 86(1): 1–15, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10054

The classical framework for phased array beamforming, analysis, and design is based on the array factor approximation. As research in antenna arrays has progressed, attention has turned to sophisticated, high sensitivity applications that require more accurate models. Mutual coupling, edge effects, surface waves, and other non-ideal effects can be accounted for full wave numerical methods, but the run time for the model becomes large, and design optimization can be unduly time consuming. A middle ground between the array factor and full wave numerical models is provided by the lossless, resonant, minimum scattering (LRMSA)approximation. Embedded element radiation patterns with open circuit loads on the element ports are approximated using an analytically known or modeled isolated element pattern, and mutual coupling is included to first order using the element pattern overlap matrix and relationships from the network theory of antenna arrays. We give an overview of the LRMSA method for fast phased array modeling and design in this paper, and the presentation will include numerical comparisons and design examples for a variety of phased array application areas.

Power Extraction Performance of a Semi-activated Flapping Foil in Gusty Flow

Most of beamforming methods rely on the proper estimation of the steering vectors of the incoming signals in order to calculate appropriate array feeding weights. However, this estimation is often performed on a theoretical basis, since most methods assume that the array elements radiate like isotropic sources and consider only the phase differences between them due to their different spatial positions. This is a rough estimation as it ignores both the non-isotropic radiation pattern of the array elements and the mutual coupling between them. To overcome these limitations, we use a different approach for the construction of steering vectors based on the embedded patterns of the array elements, extracted through full-wave analysis. This approach is used in this paper to modify two well-known beamforming methods, namely the null steering beamforming and the minimum variance distortionless response method. Both modified methods are applied to a realistic model of a microstrip planar antenna array, and thus, both the azimuth and polar angles of the main lobe and nulls directions are controlled (beamforming in 3D space). Extensive statistical analyses are performed by implementing several scenarios of escalating difficulty, in order to examine the performance and temporal response of the modified beamforming methods in comparison to the respective conventional methods and also in comparison to beamforming methods based on evolutionary techniques.

This paper presents a simple and precise design method for asymmetric resonant inductive coupled wireless power transfer (WPT) systems without the involvement of circuit or electromagnetic (EM) simulators. The design method is based on the generalized second-order band-pass filter (BPF). First, the values of the BPF's J-inverters are computed based on the mutual coupling between the transmitter (TX) and the receiver (RX). Then, the required components are extracted from the J-inverters values. We achieved good agreements between the analytical design procedure, the circuit and the EM simulations, and the measurements. The measured efficiency is 75% at a transmission distance of 38 mm, and the sizes of the TX and RX are 50×50 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and 30×30 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , respectively.

This paper concerns on the simulation-based proper design method for the efficient production of hydraulic cylinders using CAE techniques which are widely used in various industries. Simulation-based design techniques are actively being used to reduce time and cost for product design in the industries. However, the hydraulic cylinder cannot be designed with general simulation-based design method, because it is designed and manufactured by the standard regulations such as ISO and KS. To tackle this problem, we developed CAEbased proper design method that combines simulation-based design optimization with a production design method using commercial production database according to standard rules. This technology allows designers to efficiently select the best commercial products of the equipment and components required for the system. The developed technology was verified by applying it to the design study of the lifting pump mounting system in deep-seabed integrated mining system developed in 2015.

This is a reply to comments from Hu etal. regarding, of which there are three concerns. The first concern in the comments is a one-to-one mapping relationship between coupling paths in a transversal array network topology and coupling elements in a physical filter structure. In conclusion, it is not necessary to determine the order of parallel paths corresponding to physical structures, as shown. This is because resonators in parallel paths of a transversal array network topology represent eigenmode resonances appearing in coupled resonators. This physical understanding has already been presented in using an example of a direct-coupled waveguide filter. The viewpoint of the order in parallel paths may come from a conventional design method of direct-coupled resonator filters, where the one-to-one mapping relationships can be easily found because the filters are composed of physically separated resonators. On the other hand, multiple resonances of a multi-mode resonator cannot be divided into physical coupling elements. In such cases, the transversal array network topology is a powerful tool for multi-mode filter designs. Therefore, three multi-mode filters have been demonstrated as examples of applications of our proposed parameter-extraction technique. The second concern in the comments of Hu et al. is the treatment of stray couplings in the transversal array coupling network. The stray couplings such as undesired cross couplings need to be evaluated in conventional filter designs based on direct-coupled resonator filter synthesis theory in order to obtain a desired frequency response. In the transversal resonator array network, as pointed out in, such stray couplings are included into parallel paths of resonators. We think that this is one of the advantages of the transversal resonator array network since coupled-resonator filters may be designed without any decomposition of main and stray couplings. In the initial design step of a filter, a well-known design approach of coupled-resonator filters is useful for intuitive designs, but stray couplings are not taken into account in this design step. In the final design step, the introduction of a transversal coupling network may help the fine adjustments of structural parameters, because all couplings are considered in terms of eigenmodes. To verify this idea, further studies will be needed. A similar design methodology has already been provided. The third concern in the comments of Hu etal. is a reference-phase equation.

This paper describes the development of the 2004 Canadian Standards Association (CSA) A23.3 shear design provisions for reinforced and prestressed concrete structures. These methods are similar to the 1994 standard in providing a simplified and general shear design method. They differ from previous standards by providing a direct link between these two methods and simple equations for the calculation of β and θ used in the general method rather than providing these values in a table. The paper explains the basic assumptions behind the new shear provisions, provides a derivation of the new equations, and compares designs made with the new equations to designs obtained from previous standards. In general, the new shear provisions require slightly less shear reinforcement than that required by the previous standard. The new general method is significantly easier to use, particularly with spreadsheets.Key words: shear, building codes, reinforced concrete, size effect, structural design.

New design methods for concrete filled steel tubular columns

In this paper, a design method is presented for frequency-phase composite reconfigurable metasurfaces. &lt;i&gt;N&lt;/i&gt; PIN diodes are introduced into the metasurface unit. The on-off states of these PIN diodes regulate the resonance characteristics of the unit, constructing 2&lt;sup&gt;&lt;i&gt;N&lt;/i&gt;&lt;/sup&gt; switchable reflection phase states. After optimizing structural parameters, these reflection phase curves show that there is a 180° phase difference between different frequency bands. By regulating frequency and phase regulation, the operational bandwidth of reconfigurable phase-shifting metasurface is effectively expanded. Based on this method, an ultra-wideband 1-bit phase-shifting metasurface unit is designed. Its 1-bit phase regulation band covers 5.4–13.0 GHz, with a relative bandwidth of 82.6%. Lumped capacitors are adopted and their positions are optimized to precisely adjust current distribution, enabling low-loss performance of the unit. The unit with a thickness of only 0.09 &lt;i&gt;λ&lt;/i&gt; features low profile, low cost, and low loss. A 16×16 unit array is further constructed. Through coding regulation, the metasurface can generate scattering-controllable beams and orbital angular momentum vortex waves. Experimental results show that the metasurface can achieve a radar cross section reduction of over 10 dB in the ultra-wideband range, demonstrating dynamic beam steering capability and high-efficiency low-scattering performance. This design offers new insights into applying reconfigurable metasurfaces to broadband communication, radar stealth, and intelligent electromagnetic environment regulation.