National Institute of Technology, Kagawa College

In this letter, we propose a reconfigurable 1-bit reflectarray antenna (RAA ) with a novel varactor diode mounted multi-via mushroom-type (VDMM ) structure for heterogeneous networks (HetNets ). Specifically, its reflection phase and operating frequency band are controlled by changing a reverse bias voltage applied to a varactor diode mounted on the unit cell. Moreover, the proposed VDMM structure reduces frequency dependency in each operating frequency band by introducing multiple vias into the metasurface. As a result, the 1-bit RAA with the proposed VDMM structure can adaptively control the reflection direction and operating frequency band.

To determine the optimal arrangement of vertical-axis wind turbines (VAWTs) within wind farms, we previously developed a technique (method-1) that constructs a flow field based on two-dimensional (2D) velocity data derived from computational fluid dynamics (CFD) simulations. In this study, we introduce an improved approach (method-2), which follows the same fundamental concept as method-1 but incorporates a more efficient algorithm for generating the flow field. Comparative analyses confirmed that method-2 produces results equivalent to those of method-1 while significantly reducing computational time and cost. Method-2 reduces the computation time of method-1 by approximately 50% for parallel layouts (θ = 0°) and up to 60% for slanted layouts (θ = ±45°). Using method-2, we further investigated the performance of a wind farm composed of eight VAWT rotors arranged in a linear configuration under the assumption of a 2D flow. The results highlighted two important aspects. First, the predicted power output is unaffected by the order in which the flow fields are superimposed during calculation; second, the method exhibits high sensitivity to even small variations in rotor placement within the layout when the spacings between rotors are short. Additionally, we examined how rotor spacing affects the distribution of power generation across the rotor array. These findings of this study validate the efficiency of method-2 and offer practical insights for designing optimized VAWT layouts.

Waveguide bandstop filters (BSFs) play a key role in preventing electromagnetic wave leakage from gaps or sample entrances and exits, which can compromise safety, work efficiency, and electromagnetic compatibility. This study designs a waveguide BSF using a finite periodic structure of cascaded short-circuited E-plane stubs (chokes) to achieve a stopband with the transmission coefficient |S21| ≤ −30 dB and a 4% relative bandwidth. We investigate the impact of stub width on bandwidth broadening and stub spacing in cascade connections on spurious passband suppression. Electromagnetic and circuit simulations, validated experimentally, reveal that stub spacing at odd multiples of a quarter guided wavelength (λg/4) minimizes spurious passbands, with wider stubs and larger spacings enhancing stopband characteristics. This indicates that there is a great advantage in reducing the number of resonators and manufacturing costs. These findings provide practical and new design guidelines for designing efficient BSFs for preventing microwave leakage and may have applications in other filters or array antennas using periodicity.

This paper analyzes coefficient sensitivity for state-space descriptions of a second-order recursive notch digital filter. To this end, second-order recursive notch digital filters are realized by a lattice-form or direct-form based state-space description. The coefficient sensitivities for each state-space description are then analyzed to derive the improved l2-sensitivity measure. Moreover, adaptive recursive notch digital filters are presented by the lattice-form or direct-form based description. Finally, the coefficient sensitivity of the lattice-form based state-space description is compared with that of the direct-form based counterpart by means of numerical experiments. The simulation results clarify that the lattice-form based state-space description has much lower improved l2-sensitivity than the direct-form based counterpart.

ABSTRACT There is a growing discussion around the need for greater diversity, equity, and inclusion (DEI) in academia. Several leading publishers actively foster DEI policies related to publishing because, in the academic ecosystem, physical, linguistic, social capital, and credibility resources are unevenly distributed. Paradoxically, however, journals that promote DEI might only publish a few article types, such as original research and review papers. We argue here that journals with an editorial policy of restricted article formats, or that offer “invitation only” articles, are incompatible with DEI principles insofar as these journals offer only a limited‐choice format of publication to authors. One upshot of this is that restrictive editorial policies may perpetuate epistemic injustice against authors with fewer resources and credibility, who may collectively be denied suitable fora in which to share ideas. In consequence, we underline a new structural form of epistemic injustice, complementing existing forms, and argue that a “first page free” comment forum should exist in all academic journals to mitigate it.

Abstract Copper–antimony–sulfur (Cu–Sb–S) compound powders were synthesized using a polyol method, and their structural and optical properties were investigated. Cu–Sb–S is a promising, low-cost, earth-abundant ternary semiconductor material with low toxicity. The Cu–Sb–S powders were synthesized at temperatures ranging from 160 to 200 °C with a stirring speed of 600 rpm for 60 min under ambient pressure. X-ray diffraction and Raman spectroscopy revealed the formation of CuSbS2 at 180 °C. The morphology and elemental composition of the Cu–Sb–S powders varied with the synthesis temperature. Based on the results obtained, the synthesis mechanism and optimal synthesis temperature for CuSbS2 are discussed.

A design of sliding mode synchronize controller based on model reference control scheme and the experimental results of wheel chair bi-wheel running test are described. The controller with manual wheel chair reference model that estimated wheel drive force as the other wheel dive one is input performs one-hand driven wheel chair. The robust bi-wheel synchronization under the appropriate drive force feedback gain demonstrates one-hand driven wheel chair not only rectilinear motion but also clock wise (or counter clock wise) rotation and pivot turn.

Spotforming is a target-speaker extraction technique that uses multiple microphone arrays. This method applies beamforming (BF) to each microphone array, and the common components among the BF outputs are estimated as the target source. This study proposes a new common component extraction method based on nonnegative tensor factorization (NTF) for higher model interpretability and more robust spotforming against hyperparameters. Moreover, attractor-based regularization was introduced to facilitate the automatic selection of optimal target bases in the NTF. Experimental results show that the proposed method performs better than conventional methods in spotforming performance and also shows some characteristics suitable for practical use.

Several power assist robots have been developed to reduce workloads, and address worker shortages and an aging workforce. Previously, the authors developed a power assist device to maintain shoulder posture using a braking mechanism; however, the device presented technical issues regarding the rigidity and weight of the mechanism. To address these issues, in this study, a flexible linear brake (FLB), a brake mechanism driven by negative pressure, was developed for power assist devices. Additionally, a braking force model for the FLB is proposed; the proposed model was verified by comparing the measured and modelled values. Finally, a shoulder assist device that uses the FLB and designed based on the proposed model is discussed in detail.

So-called "middle authors," being neither the first, last, nor corresponding author of an academic paper, have made increasing relative contributions to academic scholarship over recent decades. No work has specifically and explicitly addressed the roles, rights, and responsibilities of middle authors, an authorship position which we believe is particularly vulnerable to abuse via growing phenomena such as paper mills. Responsible middle authorship requires transparent declarations of intellectual and other scientific contributions that journals can and should require of co-authors and established guidelines and criteria to achieve this already exist (ICMJE/CRediT). Although publishers, editors, and authors need to collectively uphold a situation of shared responsibility for appropriate co-authorship, current models have failed science since verification of authorship is impossible, except through blind trust in authors' statements. During the retraction of a paper, while the opinion of individual co-authors might be noted in a retraction notice, the retraction itself practically erases the relevance of co-author contributions and position/status (first, leading, senior, last, co-corresponding, etc.). Paper mills may have successfully proliferated because individual authors' roles and responsibilities are not tangibly verifiable and are thus indiscernible. We draw on a historical example of manipulated research to argue that authors and editors should publish publicly available, traceable contributions to the intellectual content of an article-both classical authorship or technical contributions-to maximize both visibility of individual contributions and accountability. To make our article practically more relevant to this journal's readership, we reviewed the top 50 Q1 journals in the fields of biochemistry and pharmacology, as ranked by the SJR, to appreciate which journals adopted the ICMJE or CRediT schools of authorship contribution, finding significant variation in adhesion to ICMJE guidelines nor the CRediT criteria and wording of author guidelines.