Passive Structures Research Articles

Expedited re-design of multi-band passive microwave circuits using orthogonal scaling directions and gradient-based tuning

Geometry scaling of microwave circuits is an essential but challenging task. In particular, the employment of a given passive structure in a different application area often requires re-adjustment of the operating frequencies/bands while maintaining top performance. Achieving this necessitates the utilization of numerical optimization methods. Nonetheless, if the intended frequencies are distant from the ones at the starting point, local search procedures tend to fail, whereas global search algorithms are computationally expensive. As recently demonstrated, a combination of large-scale concurrent geometry parameter scaling with intermittent local tuning allows for dependable re-design of high-frequency circuits at low CPU costs. Unfortunately, the procedure is only applicable to single-band structures due to synchronized modifications of all operating bands under scaling. This article discusses a novel procedure that leverages a similar overall concept, but allows for independent control of all center frequencies. To achieve this goal, an automated decision-making procedure is developed in which a set of orthogonal scaling directions are determined based on their effect on individual circuit bands, and using auxiliary optimization sub-problems. The scaling range is then automatically computed by solving an appropriately-defined least-square design relocation problem. The methodology introduced in the work is illustrated using two planar passive devices. In both cases, wide-range operating frequency re-design has been demonstrated and favorably compared to conventional gradient-based tuning. Furthermore, the presented procedure has been shown to be computationally efficient. It is also easy to implement and integrate with a variety of gradient-based optimization procedures of a descent type.

Numerical investigation and optimization of the melting performance of latent heat thermal energy storage unit strengthened by graded metal foam and mechanical rotation

In this paper, a combined passive graded metal foam and active mechanical rotation strategy is proposed to simultaneously solve the problem of slow melting rate and non-uniform phase change problem of the latent heat thermal energy storage (LHTES) technology. The enthalpy-porosity method and fixed grid structure are employed to numerically investigate the effects of porosity range, the number of graded layers, and the rotational angular velocity. Moreover, the response surface method (RSM) is further selected to optimize the structural parameters and obtain the function of melting performance and various factors. The result shows that there is an optimal porosity range and the total melting time decreases first and then increases with the increase of porosity range. When the porosity range is 12 % and the graded layer is three, it can shorten the melting time by 35.54 % and increase the thermal energy storage rate (TESR) by 51.57 %. In addition, the melting performance is gradually improved as the number of graded layers increases. The strengthening effect of graded metal foam with just four layers is close to that of the maximum layers considered in this paper. The trend of the influence of rotation speed on the melting performance of the LHTES unit is consistent with the porosity range, indicating the existence of the optimal rotational speed. The RSM optimization structure, with a 14.969 % porosity range, 5-layer graded number, and 2.267 rpm rotational speed, shortens the melting time by 42.42 % and increases the TESR by 62.75 % compared with the stationary case with uniform metal foam. This work verifies the effectiveness of active rotation coupling with passive graded porous structures, which could provide a new strengthening approach to enhance LHTES.

The Production of Jordanian Arabic Passive Structures by Children with Autism Spectrum Disorder

The Production of Jordanian Arabic Passive Structures by Children with Autism Spectrum Disorder

Damascene versus subtractive line CMP process for resistive memory crossbars BEOL integration

In recent years, resistive memories have emerged as a pivotal advancement in the realm of electronics, offering numerous advantages in terms of energy efficiency, scalability, and non-volatility [1]. Characterized by their unique resistive switching behavior, these memories are well-suited for a variety of applications, ranging from high-density data storage to neuromorphic computing [2]. Their potential is further enhanced by their compatibility with advanced semiconductor processes, enabling seamless integration into modern electronic circuits [3]. A particularly promising avenue for resistive memory lies in its integration at the Back-End-of-Line (BEOL) stage of semiconductor manufacturing [4]. BEOL integration involves processes that occur after the fabrication of the transistors, primarily focusing on creating interconnections that electrically link these transistors. Integrating resistive memories at this stage can lead to compact, efficient, and high-performance architectures, pivotal for in-memory computing applications where data storage and processing are co-located [5]. This paper studies three ways to integrate TiOx-based resistive memory into passive crossbar array structures, using chemical mechanical polishing (CMP) processes, focusing on identifying the optimal integration techniques.

Is Syntactic Priming from Multiple Speakers Stronger?

Syntactic priming in dialogue occurs when exposure to a particular syntactic structure implicitly induces a speaker’s subsequent preference for the same syntactic structures in their own speech. Here, we asked whether this priming effect is boosted when individuals are primed by several different speakers as opposed to one. In an initial baseline session involving a picture description task, we assessed adult participants’ production of double object/DO (vs. prepositional/PO) dative and passive (vs. active) transitive structures. Subsequently, participants played a picture description and verification game, in turns, with six other players (confederates). During verification turns, confederates primed participants by using DO and passive utterances. Crucially, participants were primed either by a single confederate (single-speaker priming condition, SSP) or by five confederates (multi-speaker priming condition, MSP). Across conditions, the same priming stimuli were presented in the same order, leaving speaker source/variation as the only different feature. The degree to which participants were primed for the target structures compared to baseline was measured. Results indicated a robust priming effect in both conditions. Nevertheless, the increase in the target structures’ use did not differ significantly between the SSP and MSP conditions, suggesting that speaker variation did not promote stronger priming.

FreeGSNKE: A Python-based dynamic free-boundary toroidal plasma equilibrium solver

We present a Python-based numerical solver for the two-dimensional dynamic plasma equilibrium problem. We model the time evolution of toroidally symmetric free-boundary tokamak plasma equilibria in the presence of the non-linear magnetohydrodynamic coupling with both currents in the “active” poloidal field coils, with assigned applied voltages, and eddy currents in the tokamak passive structures. FreeGSNKE (FreeGS Newton–Krylov Evolutive) builds and expands on the framework provided by the Python package FreeGS (Free boundary Grad–Shafranov). FreeGS solves the static free-boundary Grad–Shafranov (GS) problem, discretized in space using finite differences, by means of Picard iterations. FreeGSNKE introduces: (i) a solver for the static free-boundary GS problem based on the Newton–Krylov (NK) method, with improved stability and convergence properties; (ii) a solver for the linearized dynamic plasma equilibrium problem; and (iii) a solver for the non-linear dynamic problem, based on the NK method. We propose a novel “staggered” solution strategy for the non-linear problem, in which we make use of a set of equivalent formulations of the non-linear dynamic problem we derive. The alternation of NK solution steps in the currents and in the plasma flux lends this strategy an increased resilience to co-linearity and stagnation problems, resulting in favorable convergence properties. FreeGSNKE can be used for any user-defined tokamak geometry and coil configuration. FreeGSNKE's flexibility and ease of use make it a suitably robust control-oriented simulator of plasma magnetic equilibria. FreeGSNKE is entirely written in Python and easily interfaced with Python libraries, which facilitates machine learning based approaches to plasma control.

Investigating Passive Voice Problems in Kurdish Students’ Translation from and into English

Metaheuristic Translation is a means in which communication takes place between people who do not speak the same language and do not share the same culture. It is an undeniable fact that learners of language encounter problems in shifting a language into another using accurate aspects of the target one. This research looks at Badini-Kurdish students’ difficulties while translating passive voice structures from and into English. It also determines similarities and differences between English and Badini-Kurdish in terms of passive voice constructions. The participants of this study are 30 undergraduate students of the Department of Translation, College of Languages, University of Duhok. Two tests, i.e., an English language proficiency test and a translation test have been conducted for the purpose of data collection. Moreover, Larson’s (1984) model for translation assessment is used to assess the data obtained, combining statistical analysis with a qualitative evaluation. For data analysis, a descriptive method is used to explain the passive voice structure in both languages, a contrasted method is used to identify similarities and differences between the two languages, and a mixed method is used to accomplish the study’s goal. This research adds to the body of literature by illuminating the challenges and difficulties Badini-Kurdish students confront while translating passive voice constructs and offers insightful information for translators and language educators.

A comparative study of lexical bundles in linguistics and biology Ph.D. dissertations

Lexical bundles are considered as one of the main rhetorical features in academic genres. The appropriate use of these features adds to the coherence and naturalness of the texts. Recently, genre analysis studies tend to investigate the similarities and differences across different academic disciplines and the effects of the first language of writers on the employment of these linguistic features. There are limited studies, however, in the field with a mere focus on the use of lexical bundles in PhD dissertations and the similarities and differences on the employment of these features among native and non-native English writers. In this regard, the current study, following a comparative corpus-based approach, investigated the use of lexical bundles in English PhD dissertations written by native English-speaking and nonnative Kurdish-speaking writers across the two disciplines of biology and linguistics. All the compiled dissertations were selected from the ones published between 2010 to 2020 in British universities to keep the compiled corpora comparable. In the next phase, the distribution, linguistic structures, and functions of bundles used in introduction and literature review sections of the compiled dissertations were analyzed using WordSmith 6th edition concordancing software. The analysis provides a list of the most frequently used lexical bundles in each scientific field and among the two groups of writers. The structural analysis showed that noun phrases and prepositional phrases were the most frequently used bundles between both groups of writers and of disciplines. It was also found that passive structures were commonly used in biology dissertations. The functional analysis revealed that non-native Kurdish writers tended to use more research-oriented and text-oriented bundles in comparison with their native counterparts. It was suggested that the rhetorical differences and similarities between the two groups of writers and the disciplines could be attributed to the experience or proficiency levels of writers and the conventions, knowledge construction principles and research approaches of each academic discourse community. Pedagogically speaking, it is discussed that teaching discursive features and including language teaching tasks drawn from authentic texts such as text analysis tasks, focused tasks, extended writing tasks enable EAP learners to learn how to employ these linguistic features effectively to improve the flow of information, coherence and fluency in their academic texts.

Breakdown performance of guard ring designs for pixel detectors in 150 nm CMOS technology

Silicon pixel sensors manufactured using commercial CMOS processes are promising instruments for high-energy particle physics experiments due to their high yield and proven radiation hardness. As one of the essential factors for the operation of detectors, the breakdown performance of pixel sensors constitutes the upper limit of the operating voltage. Six types of passive CMOS test structures were fabricated on high-resistivity wafers. Each of them features a combination of different inter-pixel designs and sets of floating guard rings, which differ from each other in the geometrical layout, implantation type, and overhang structure. A comparative study based on leakage current measurements in the sensor substrate of unirradiated samples was carried out to identify correlations between guard ring designs and breakdown voltages. TCAD simulations using the design parameters of the test structures were performed to discuss the observations and, together with the measurements, ultimately provide design features targeting higher breakdown voltages.

Role of compliant mechanics and motor control in hopping - from human to robot

Compliant leg function found during bouncy gaits in humans and animals can be considered a role model for designing and controlling bioinspired robots and assistive devices. The human musculoskeletal design and control differ from distal to proximal joints in the leg. The specific mechanical properties of different leg parts could simplify motor control, e.g., by taking advantage of passive body dynamics. This control embodiment is complemented by neural reflex circuitries shaping human motor control. This study investigates the contribution of specific passive and active properties at different leg joint levels in human hopping at different hopping frequencies. We analyze the kinematics and kinetics of human leg joints to design and control a bioinspired hopping robot. In addition, this robot is used as a test rig to validate the identified concepts from human hopping. We found that the more distal the joint, the higher the possibility of benefit from passive compliant leg structures. A passive elastic element nicely describes the ankle joint function. In contrast, a more significant contribution to energy management using an active element (e.g., by feedback control) is predicted for the knee and hip joints. The ankle and knee joints are the key contributors to adjusting hopping frequency. Humans can speed up hopping by increasing ankle stiffness and tuning corresponding knee control parameters. We found that the force-modulated compliance (FMC) as an abstract reflex-based control beside a fixed spring can predict human knee torque-angle patterns at different frequencies. These developed bioinspired models for ankle and knee joints were applied to design and control the EPA-hopper-II robot. The experimental results support our biomechanical findings while indicating potential robot improvements. Based on the proposed model and the robot’s experimental results, passive compliant elements (e.g. tendons) have a larger capacity to contribute to the distal joint function compared to proximal joints. With the use of more compliant elements in the distal joint, a larger contribution to managing energy changes is observed in the upper joints.

The -eci Syncretism in Korean: Implications for the Theory of v and Voice

Abstract This paper investigates the syncretism exhibited by the Korean verbal suffix -eci. In addition to its widely known appearance in the passive construction, -eci can also be used to derive verbs expressing potentiality. In this paper, I show that two independently motivated theoretical tools — (i) the articulated verbal structure with root, verbalizer, and Voice; and (ii) the assumption that morphological identity signifies the morpheme's realization of an identical syntactic head — accurately explain the passive-potential syncretism in Korean. Specifically, I argue that -eci realizes a syntactic head that the passive and potential structures have in common: vGO, the verbalizer marking the eventuality of ‘change’. I attribute the systematic morpho-syntactic and semantic contrasts between passives and potentials to the (non)existence of VoicePASS, the projection introducing an implicit external argument. The analysis successfully captures the properties of the other constructions formed upon -eci — namely, derived change-of-state and lexical inchoative predicates.

Lithium stabilization of amorphous ZrO2

Small modular reactors (SMRs) are a key option to aid the worldwide net zero targets for carbon emissions. Some pressurised water reactors aim to operate with a boron-free coolant chemistry for simplification in plant design. In the absence of boron, Li has been found to accelerate the corrosion of the zirconium-based alloy fuel cladding under certain conditions and concentrations within pressurised water reactors (PWRs). The cause of the accelerated corrosion has yet to be identified. This work identifies the potential for amorphous ZrO2 phase stabilization by lithium that will potentially have an impact on the passive oxide's grain boundary structure. Higher lithium concentrations are found to stabilise the amorphous phase's stability before re-crystallisation to higher temperatures. Chemical assessment has also shown the lithium phase to be soluble in water, indicating a potential mechanism for lithium to alter grain boundaries and increase the pathways for further oxidation of the underlying zirconium material.

First language interference in speaking and writing Indonesian language of Azerbaijani students in Indonesian language course at Azerbaijan University of Languages

This study examines the issue of first language interference in spoken and written Indonesian by Azerbaijani students who are taking an Indonesian language course at Azerbaijan University of Languages. The study is framed within the context of bilingualism, where first language interference occurs when individuals learn a foreign language. The aim of this research is to identify the types and causes of interference displayed by Azerbaijani-speaking students when using Indonesian language, with a focus on speaking and writing during classroom activities. A descriptive qualitative approach was used to collect data through observation and documentation, including oral recordings and written assignments. Analysis revealed that Azerbaijani students face pronunciation, morphology, and syntax challenges due to interference based on Weinreich’s theory. Pronunciation challenges arise from the lack of the phonetic sound [ê] in Azerbaijani, resulting in substitutions with [é]. Morphological complexities arise from the unfamiliarity with prefixes in Azerbaijani, making it difficult to transform active sentences into passive structures. Syntactic challenges arise due to the differing sentence structures between Azerbaijani (S-O-P-C) and Indonesian (S-P-O-C). To mitigate interference, it is recommended to include targeted phonological drills, increased morphological exercises, and enhanced syntactic practice to facilitate a smoother language acquisition journey for Azerbaijani students who are mastering Indonesian language.

Impedance control for a Stewart‐structure‐based wheel‐legged robotic system in wheel motion

SummaryAn impedance control scheme is proposed for a Stewart‐structure‐based wheel‐legged robotic system to strengthen the dynamic attitude adjustment stability in wheel motion. The wheel‐leg, which is driven by electrical cylinders in the Stewart structure, is analyzed in kinematics and dynamics. The rotation in the axial direction of every electric cylinder is calculated to improve the accuracy of the kinematic model. To fulfill the impedance demands, a passive structure with 6 degrees of freedom (DOF) is modeled. The mass of the mechanism has a coupling effect on the impedance model for each DOF, which is a nonlinear function. As motion decoupling in the workspace has been completed for the Stewart structure, an impedance control strategy with inner‐loop position tracking is employed. An extended state observer (ESO) is designed to estimate the disturbances arising from the nonlinear coupling effects. Based on the ESO observation outputs, an active disturbance rejection control that explicitly handles the workspace limit is designed with guaranteed practical stability. By reducing force interaction and body vibration, the wheel‐legged robotic system keeps wheel motion stability on uneven roads. Multiple comparative experimental results are presented to validate the stability and effectiveness of the proposed method.

Pre-existing structural control on the recent Holuhraun eruptions along the Bárðarbunga spreading center, Iceland

The active rift zones in Iceland provide unique insight into the geodynamic processes of divergent plate boundaries. The geodynamics of Iceland are studied intensively, particularly, by geophysical methods sensitive to active and/or visible structures such as earthquake seismic and Synthetic Aperture Radar observations or aerial photographs. However, older and less active structures, that may exert a strong control on the presently active geodynamics, are often buried beneath recent volcanic or sedimentary deposits and are—due to their passive mode—overseen by the typical geophysical investigations. Aeromagnetic surveys provide spatial information about subsurface magnetization contrasts relating to both active and inactive structures. However, the aeromagnetic data in Iceland were collected in the 1970-80s and are relevant only to large-scale regional rift studies. With the availability of reliable drones and light-weight atomic scalar sensors, high-quality drone magnetic surveys can provide an unprecedented spatial resolution of both active and passive structures of rift systems as compared to conventional airborne surveys. Here, we present the results of a drone-towed magnetic scalar field and scalar gradiometry study of the north-northeast trending Bárðarbunga spreading center to the north of the Vatnajökull ice cap, Iceland. Our results provide new information about the structural complexity of rift zones with evidence of densely-spaced, conjugate and oblique faults throughout the area. Evidence is shown of a hitherto unknown and prominent east-northeast trending fault structure that coincides with the northern tip of the main eruption edifice of the 1797 and 2014-15 Holuhraun volcanic events. We suggest that this pre-existing structure controlled the locus of vertical magma migration during the two Holuhraun events.

Validating the measurement of passive Musculo-articular wrist stiffness without intentional or reactive contraction using axillary plexus block

BackgroundPassive stiffness describes how easily a joint may move passively. To accurately measure wrist stiffness, an electro-oscillation device was developed. The objectives were to 1) ensuring that the measurement are free from intentional or reflex contraction, 2) analyzing how forearm anatomy affects the passive stiffness of the wrist and 3) determining the clinical practical relevance of the device. MethodsIn this prospective study, the device generated low amplitude sinusoidal motions in flexion and extension on the wrist to quantify elastic and viscous passive stiffness in voluntary orthopaedic patients. The first series of measurements was carried out in the state of voluntary relaxation, the second series of measurements was carried out after an axillary plexus anesthetic block. A matched group of healthy subjects were use for control. FindingsThe Electromechanical Oscillation methods effectively enable the measurement of passive joint stiffness since the stiffness values obtained show no statistically significant difference pre-post the anesthesia. The stiffness values are comparable to those of healthy subjects. The effect of forearm passive structure, estimated by the perimeter of the forearm, influences the passive stiffness of the wrist, mainly the viscous component. InterpretationThe use of sinusoidal oscillation was well accepted by the participants, demonstrating its usefulness and applicability in a clinical setting. This work serves as a foundation for future investigations of orthopaedic and/or neurological pathological conditions characterized by abnormal passive joint stiffness of the wrist. It paves the way for its use as a diagnostic, prognostic, and monitoring tool in these pathologies.

Beam-type acoustic black holes incorporating the microstructure-dependent nonlocal effect

Acoustic black holes (ABHs) are effective passive damping structures for capturing bending waves at wedge edges. However, as the wedge shape continuously reduces in size, the intrinsic length scale of the ABH's tip gradually approaches the external length scale, such as the wavelength of wave, which causes a phenomenon known as the "scale effect" to take hold of the ABH. Despite gaining considerable attention in the past two decades, the influence of intrinsic length on the energy aggregation of ABHs has not been thoroughly investigated. This study aims to explore the significant contribution of microstructure-dependent nonlocal effects on the dynamic behavior of ABHs, which holds great scientific importance. The nonlocality arises from the inherent length of the material being studied. A nonlocal elastic theory (NET) is employed to model the dynamic behavior of one-dimensional ABH beams. Geometric acoustic method is proposed to analyze the power-law beam wave number and microstructure-related reflection coefficient. Results indicate a significant impact of nonlocality on the acoustic energy of beam-type ABHs, particularly when the nonlocal intrinsic length approaches the truncation length of the wedge. Moreover, a comparison between the present study and classical theory reveals an overestimation of the reflection coefficient in conventional works for small truncation lengths. The relationship between the reflection coefficient, truncation length, and nonlocal characteristic lengths is thoroughly examined. Additionally, the influence of the damping layer and different power-law exponents m on ABH behavior is extensively studied.

Thermal buckling characterization of nanocomposite beams activated by PZT with temperature-dependent characteristics considering the pyroelectricity

Employing piezoelectrically activated beam-like structures is extending in numerous applications for instance energy harvesters and sensors. On the other hand, advanced materials such as carbon nanotube-reinforced nanocomposites are widely implemented in making passive structures with the aim of using their advantages. For the first time, a study is established on the critical temperature of a piezoelectric sandwich aggregated CNTRC beam regarding the pyroelectricity. The stabilization contribution of pyroelectricity against the thermal buckling incidence of sandwich beams has been demonstrated specifically. It is found that the pyroelectricity develops the critical point for the temperature of a clamped-clamped piezoelectric sandwich non-reinforced beam.

Topology optimization of multi-material active structures to reduce energy consumption and carbon footprint

A multi-material active structure is a mechanical system made of passive and active materials with the ability to alter its configuration, form, or properties in response to changes in the environment. Active structures have been investigated to design lightweight structures and structures with the ability to “smartly” alter their shapes and/or internal forces. Recently, the potential of active structures to reduce environmental impact, i.e., reduce energy consumption and greenhouse gas (GHG) emissions, has been investigated. It has been verified that, compared to passive structures, active structures can not only use less material but also consume less energy and cause less GHG emissions during their service life, and thus have a significant potential to be applied as environment-friendly mechanical structures. This study aims to develop a general topology optimization (TO) approach to design novel multi-material active structural systems to reduce environmental impact. The approach is based on the density-based TO scheme. Passive and active materials are considered in the TO process and are required to be optimally distributed according to the optimization objective and constraints. The energy consumption or GHG emissions caused by the structure during its service life are treated as the objective function to be minimized under multiple displacement requirements. Typical examples are carried out to verify the developed approach. Results show that the topology optimized active structures may not only achieve significant weight savings but also less energy consumption and GHG emissions compared to equivalent topology optimized passive structures, which indicates that the developed approach has the potential to be applied to design novel structural systems with lighter weight, larger span, and with less environmental impact compared to conventional passive structural systems.

Postpartum Pelvic Floor Muscle Training for Reducing Urinary Incontinence: A Systematic Review of Randomized Control Trials

Postpartum urinary incontinence is an increasingly prevalent problem for women, as it affects about one-third of women. The clinical significance of urine incontinence in relation to deficiencies in the active and passive pelvic floor structures is well recognized. Hence, pelvic floor muscle training (PMFT) treatment for urine incontinence is recommended. Several research studies suggest that PFMT prevents and treats pregnancy- and delivery-related urine incontinence. This study aimed to determine the effectiveness of postpartum PFMT for the treatment of urinary incontinence. Randomized control trials reporting the efficiency of PFMT among postpartum women from 2003–2023 were included. Studies including pregnant women or women who underwent any surgical intervention, along with studies describing pharmacological interventions and others apart from PFMT or PFMT with electrostimulation or biofeedback, were excluded. Additionally, studies with insufficient or unclear data regarding pregnancy outcomes were excluded. A Cochrane bias risk assessment tool was utilized to assess the quality of the studies. Final inclusion resulted in 7 studies that recruited 1398 patients. Four of the included trials assessed the endurance and strength of PFMT, and various rates of strength and endurance were observed among participants in both the intervention and control groups. The prevalence of urinary incontinence in comparison to the control group was observed to be lower in the intervention group, which demonstrates the beneficial role of PFMT in the management of urinary incontinence postpartum. There is strong evidence to suggest the effectiveness of PFMT in the management of postpartum urinary incontinence. However, this beneficial role of PFMT is often overlooked or under-described in clinical practice, for which awareness among clinicians and patients is vital. Additionally, awareness and planning for PFMT execution during antenatal visits can also help prevent urinary incontinence postpartum.