Passive Structures Research Articles

Effect of temperature on the passive film structure and corrosion performance of CoCrFeMoNi high-entropy alloy

The effect of temperature on the passive film structure and corrosion performance of CoCrFeMoNi HEA was studied. The results indicated that the passive films exhibited a bilayer structure, where Co and Mo were segregated in the outer film, while Cr was enriched in the inner layer. The content of Fe and Mo species in the passive films decreased with rising temperature, leading to the passive film degradation. The CPT of the HEA was 50–60 ℃. The HEA suffered from selective dissolution of FCC phase below 50 ℃ during the potentiodynamic polarization tests, while pitting corrosion occurred above 60 ℃.

Bridging the Gap between Physical and Circuit Analysis for Variability-Aware Microwave Design: Power Amplifier Design

Process Induced Variability (PIV) stemming from fabrication tolerance can impact the performance of integrated circuits. This issue is particularly significant at high frequencies, since Monolithic Microwave Integrated Circuits (MMICs) rely on advanced semiconductor technologies exploiting device sizes at the nanoscale in conjunction with complex passive structures, featuring both distributed elements (transmission lines) and lumped components. Black-box (behavioral) models extracted from accurate physical simulations can be profitably exploited to incorporate PIV into circuit-level MMIC analysis. In this paper, these models are applied to the statistical analysis of a single and of a combined MMIC power amplifier designed in GaAs technology for X-band applications. The relative impact of the active device variability towards the passive matching networks one is evaluated, demonstrating the relevance of PIV. The significant spread found, with only two variable parameters, confirms the importance of a PIV-aware PA design approach, with suitable margins and careful network optimization.

Programmable bulk modulus in acoustic metamaterials composed of strongly interacting active cells

Active acoustic metamaterials are one path to acoustic properties difficult to realize with passive structures, especially for broadband applications. Here, we experimentally demonstrate a 2D metamaterial composed of coupled sensor-driver unit cells with effective bulk modulus (κeff) precisely tunable through adjustments of the amplitude and phase of the transfer function between pairs of sensors and drivers present in each cell. This work adopts the concepts of our previous theoretical study on polarized sources to realize acoustic metamaterials in which the active unit cells are strongly interacting with each other. To demonstrate the capability of our active metamaterial to produce on-demand negative, fractional, and large κeff, we matched the scattered field from an incident pulse measured in a 2D waveguide with the sound scattered by equivalent continuous materials obtained in numerical simulations. Our approach benefits from being highly scalable, as the unit cells are independently controlled and any number of them can be arranged to form arbitrary geometries without added computational complexity.

Ligamentum arteriosum: Muscular and contractile.

Ductus arteriosus is a muscular artery in fetal circulation, spanning from the bifurcation of the pulmonary trunk to the aortic arch, shunting blood directly from pulmonary circulation into systemic circulation thus by-passing the fluid-filled lungs. Postnatally, it changes name to the ligamentum arteriosum (LA), when a cascade of anatomical and physiological processes leads to its closure. Though the LA has generally been considered as a fibrosed remnant of the ductus arteriosus, anecdotal and contradictory reports still describe the LA as a small muscular artery. We hypothesized the likelihood of contractile muscular elements retainment in this so-called ligament. To investigate this, mediastinum of wild-type mouse, pig, and human LA were subjected to routine and special histological staining, single-immunolabeling, electron microscopy (mouse and pig only), and tension recording of explanted pig LA in organ bath experiments. Contrary to a canonical ligament, the LA was mainly made up of α-smooth muscle actin-positive cells in all three species, confirmed by routine and special histological staining as well as transmission electron microscopy. Myocytes within the LA contracted in response to exogenous noradrenalin (NA). NA-induced precontracted LA relaxed upon administration of the α1-adrenergic blockers (prazosin and tamsulosin). Though the LA does not function in its original capacity as fetal shunt, it is clearly not a passive structure, and may be described as muscular and contractile. The contractile abilities of LA myocytes may act on the two great vessels to which it is attached causing a change in their distensibility.

Learn to swim: Online motion control of an underactuated robotic eel based on deep reinforcement learning

As a typical underwater robot, the robotic fish has been a hot topic of research in terms of the swimming control method and the reduction of energy consumption. Body flexibility and passive designs have been proven to be effective approaches for improving the swimming performance of robotic fishes. However, the addition of passive structures or motions of these approaches makes it more difficult to control the movement of robotic fish. In this paper, we proposed a deep reinforcement learning-based method for online learning control of a robotic eel with multiple passive structures. First, we designed a robotic eel with two wire-driven segments and two complaint bodies made of elastic material. Second, a simulation model of the robotic eel was built and the validity of the model was tested. Following that, the neural network was trained in simulation and deployed directly on the robotic eel, which was controlled without an underlying control model or strategy and directly online by the neural network. Finally, extensive experiments verified the effectiveness of our control method, which offers a valuable and potential solution for robots difficult to model and control.

Electromagnetic Analysis of DTT Poloidal Field Coils During an Electrical Transient

The magnetic system of the Divertor Tokamak Test facility (DTT), comprising all the superconducting poloidal coils, is an important part of the machine. It is composed of several parts mutually coupled among them: six Central Solenoid (CS) coils, six Poloidal Field (PF) coils, the passive structures and the plasma. This implies that a current variation in any poloidal coil (CS or PF) can cause a significant current or voltage variation in the others, as well as a change of the plasma current. In particular, during a major plasma disruption, the magnetic flux in the tokamak changes rapidly producing over-voltage and/or over-current in each poloidal coil, and can be at the origin of severe damage to the components. The assessment of the overvoltage occurring in each poloidal coil has been carried out by an electromagnetic analysis in <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Ansys</i> environment, step-by-step. Different initial conditions were considered for electromagnetic analysis and two possible electrical transients were simulated: a Breakdown event and a major plasma disruption. The Finite Element Model (FEM), the concentrated parameters circuit and the simulation results are here described and presented.

Translation of the Passive Voice from English into B/C/S

The passive voice is generally overused in English, hence the need to investigate how it translates to other languages, B/C/S in particular. It is also widely used in academic and business English in order to make the text diplomatic and objective, as it is preferable for business. The aim of this paper is to determine whether passive in business English texts remains intact after translation to B/C/S, and whether it plays a more central role in English or in B/C/S. After gathering data from 30 different academic articles related to economics, 63 passive structures were selected and analyzed. Subsequently, a comparison was made between them and their B/C/S counterparts in order to determine how many were translated literally to B/C/S, how many preserved the voice but changed the form, and how many samples changed both voice and form. It was discovered that 17 samples were translated literally to B/C/S, 25 retained their voice but changed the form, and 21 samples retained neither voice nor form. Based on the results obtained we have come to an expected conclusion that passive is not as present in B/C/S as it is in academic and business English, thereby it plays a more central role in English than it does in B/C/S. Interestingly, there were two examples where voice transformation was reversed, the B/C/S passives became English actives. We find such occurrences unusual, as the passive voice is typically more common in English than in B/C/S.

Silicon Cantilever for Micro/Nanoforce and Stiffness Calibration.

The paper deals with cantilevers made from monocrystalline silicon by processes of microtechnology. The cantilevers are passive structures and have no transducers. The application as a material measure for the inspection of stylus forces is in the center of investigations. A simple method is the measurement of the deflection of the cantilever at the position of load by the force if the stiffness of the cantilever at this position is known. Measurements of force–deflection characteristics are described and discussed in context with the classical theory of elastic bending. The methods of determining the stiffness are discussed together with results. Finally, other methods based on tactile measurements along the cantilever are described and tested. The paper discusses comprehensively the properties of concrete silicon chips with cantilevers to underpin its applicability in industrial metrology. The progress consists of the estimation of the accuracy of the proposed method of stylus force measurement and the extraction of information from a tactile measured profile along the silicon cantilever. Furthermore, improvements are proposed for approaches to an ideal cantilever.

Stability and Resilience—A Systematic Approach

Stability and resilience are two crucial concepts to the proper functioning and understanding of the behavior of both natural and man-made systems exposed to perturbations and change. However, although the two have covered a similar territory within dynamic systems, the terminology and applications differ significantly. This paper presents a critical analysis of the two concepts by first collating the wealth of modern stability concept literature within dynamics systems and then linking it to resilience thinking, defined as adaptation where the system has the ability to respond perturbations and change through passive and active feedback structures. A lumped mass and simple pendulum, two simple linear and nonlinear dynamic systems following a state-space approach from modern control systems theory, are used to support the analysis and application. The research findings reveal that the two overarching categories of engineering resilience and socio-ecological resilience (extended ecological resilience) are in fact a reinvention of a closed-loop system dynamic stability with different types of active feedback mechanisms. Additionally, structural stability describes some vital aspects of social–ecological resilience such as critical thresholds where, under change, a system loses the ability to return to the starting form or move to another suitable form through active feedback mechanisms or direct management actions.

Different passivation behavior between α and β phases of Ti-6Al-4V in HCl solutions under oxygenated/deoxygenated conditions

The passivation behavior of the α and β phases in a Ti-6Al-4V alloy under different oxygen conditions was investigated. The α and β phases exhibit a stronger tendency toward galvanic corrosion under deoxygenated conditions, but not under oxygenated conditions. From in situ scanning Kelvin probe force microscopy (SKPFM) method we find the α oxidation rate is higher. Meanwhile, the passive film composition and structure of α's and β's were compared by using FIB-STEM. The α phase has a lower Al/V element concentration and more atoms in the matrix to participate in the annihilation reaction of metal vacancies. Furthermore, based on first principles and statistical mechanics, the alloying element Al/V alters the Ti atoms coordination environment and reduces the Ti atoms adsorption potential.

Experimental Study on the Interaction between Backfill and Surrounding Rock in the Overhand Cut-and-Fill Method

Backfilling is commonly used in underground mines to improve the stability of overlying strata. The performance of the backfill and its interaction with surrounding rock are the key issues in backfill mining research. In this paper, the displacement and stress field evolution characteristics of the overlying strata in backfill mining were analyzed by a physical model, as well as the interaction between the backfill and surrounding rock. The research results show that when backfill mining is employed, the backfill mass and the unexcavated rock mass jointly bear the loads of the overlying strata. The loads of the overlying strata are transferred to the dense backfill mass and the surrounding rock. The stress in the near-field area of the surrounding rock increases and stabilizes gradually. The backfill mass improves the stress distribution state and reduces the stress concentration of the surrounding rock, which is conducive to preventing the progressive damage of the overlying strata. In addition, the backfill mass excavation has a significant influence on the stability of the overlying strata and the surrounding rock stress field. The backfill mass is a passive force-bearing structure that can effectively manage the deformation of the overlying strata and the phenomenon of underground pressure.

Processing instruction with structured/unstructured output: Does it make any changes in automatic/non-automatic explicit grammar knowledge?

Research has underscored the separate role of output to promote processing instruction (PI) effects in language learning. Yet, there is a need to scrutinize the interplay between structured output (SO) and unstructured output (USO) within PI to understand how innovative combinations may enhance ultimate educational attainment. The present quasi-experimental study investigated the possible effects of PI with/without SO and USO on learners’ short-term and long-term automatic and non-automatic explicit knowledge of English passive structure. A homogeneous sample of 115 Intermediate learners of English as a foreign language (EFL) in intact groups was selected and randomly assigned to four experimental groups (PI, PI+SO, PI+USO, and PI+SO+USO). We administered parallel timed and untimed grammaticality judgment tests (GJT) to measure learning. Kruskal–Wallis, Mann–Whitney, Friedman, and Wilcoxon Signed Rank Tests revealed that the PI+SO+USO group outperformed the other groups. The findings underscore the significance of adding SO and USO to PI in promoting grammar knowledge and offer several pedagogical implications.

Cosserat modeling for deformation configuration of shape memory alloy unimorph actuators

Shape memory alloys (SMAs) can contract their length via a crystalline phase transition that is dependent upon their temperature and stress state. SMAs have been used as linear micro-actuators due to their high strength to weight ratio and compact structure. However, the relatively low linear contraction ([Formula: see text]4%–5% in length) limits their use. To remedy this, the SMA can be offset from a passive structure, which acts to magnify the deformation. The resulting amount of deformation depends upon the material properties and geometry of both the SMA and the passive structure. In this work, geometrically exact beam theory (also known as Cosserat theory) is coupled with SMA constitutive relations to model the maximum deformation configuration of these actuators. Four of these actuators of various lengths were fabricated and tested to verify the model. For the four actuators tested, the mean squared error between the experimental results and the Cosserat model were between 0.0702 mm (0.1% error) for the shortest actuator (66 mm in length) and 3.59 mm (2.7% error) for the longest actuator (135 mm in length). These results show that the closed form solution derived for this Cosserat beam model can accurately model the deformation of these active structures.

Earlier spring snowmelt drives arrowleaf balsamroot phenology in montane meadows

AbstractClimate change is shifting phenology globally, altering when and how species respond to environmental cues such as temperature and the timing of snowmelt. These shifts may result in phenological mismatches among interacting species, creating cascading effects on community and ecosystem dynamics. Using passive warming structures and snow removal, we examined how experimentally increased temperatures, earlier spring snowmelt, and the poorly understood interaction between warming and earlier spring snowmelt affected flower onset, flowering duration, and maximum floral display of the spring‐flowering montane species, arrowleaf balsamroot (Balsamorhiza sagittata), over a 7‐year period. Additionally, potential cumulative effects of treatments were evaluated over the study duration. The combination of heating with snow removal led to earlier flower onset, extended flowering duration, and increased maximum floral display. While there was year‐to‐year variation in floral phenology, the effect of heating with snow removal on earlier onset and maximum floral display strengthened over time. This suggests that short‐term studies likely underestimate the potential for climate change to influence phenological plant traits. Overall, this research indicates that B. sagittata's flowering onset responded more strongly to snow removal than to heating, but the combination of heating with snow removal allowed plants to bloom earlier, longer, and more profusely, providing more pollinator resources in spring. If warming and early snowmelt cause similar responses in other plant species, these patterns could mitigate phenological mismatches with pollinators by providing a wider window of time for interaction and resiliency in the face of change. This example demonstrates that a detailed understanding of how spring‐flowering plants respond to specific aspects of predicted climatic scenarios will improve our understanding of the effects of climate change on native plant–pollinator interactions in montane ecosystems. Studies like this help elucidate the long‐term physiological effects of climate‐induced stressors on plant phenology in long‐lived forbs.

Structural Foundations of Concrete Outcomes: Embeddedness Fosters Gossip, Trust, and Performance

Prior work has shown that employees are more likely to trust colleagues that are more embedded in their professional network. The prevailing assumption is that embeddedness serves a social monitoring function: the more third-party connections employees share, the less they would risk engaging in behaviors that might destroy trust, such as lying and cheating. We propose that embeddedness not only deters behaviors that are harmful to trust, but also serves as a structural foundation for behaviors that establish and increase trust, such as gossip. We thus propose a structural theory of gossip. Data from field studies across three organizations in Mainland China supported the hypothesis that gossip mediated the positive relationship between embeddedness and trust. The higher levels of trust linked to embeddedness and gossip was associated with positive downstream consequences in colleagues’ peer performance evaluations of the gossiper. We further discuss the role of gender in moderating trust relationships developing from positive and negative gossip. This research underscores the role that seemingly passive network structures can play in shaping concrete behaviors that have important interpersonal and organizational outcomes.

Effect of the Passive Oxide Films Structure and Surface Temperature on the Rate of Anodic Dissolution of Chromium-Nickel and Titanium Alloys in Electrolytes for Their Electrochemical Machining. Part 2. Anodic Dissolution of Titanium Alloys in Nitrate and Chloride Solutions

An experimental study of the anodic dissolution of titanium and its alloys, including pulsed dissolution (up to 100 A/cm2) under control of hydrodynamic conditions and surface temperature in nitrate and chloride solutions, showed that the process is carried out through the electrochemical formation of anodic oxide films (AOF) which can be chemically dissolved. An AOF has a bilayered structure, i.e. two barrier films on the interface with a metal and a solution. Its model is PDM-III (Point Defect Model). At certain conditions, it is possible to achieve a steady state in which the film growth rate is compensated by the rate of its chemical dissolution (observed at pulsed conditions). In this case, over 100% current efficiency based on the ionization of titanium in the oxidation state is achieved. During the conducted experiments, when treated with the direct current, the rate of the electrochemical formation of an AOF exceeded the rate of its chemical dissolution, which led to a decrease in to current efficiency which did not exceed 75%. An increase of the dissolution rate takes place with an increase in the electrolyte flow rate. Upon reaching the thermokinetic instability (TKI) of the AOF (thermal explosion due to a feedback rate of the electrochemical reaction-surface tem-perature-rate of an electrochemical reaction), the interaction of electrolyte components with the surface free of the film takes place, and, as a result, an “anomalous” anodic dissolution is observed with the current efficiency greater than 100%. Regardless the nature of the electrolyte, TKI is achieved at a current density of 1 A/cm2. It is shown that in nitrate solutions with certain parameters of pulsed processing (duty factor 2, dc 50%), the dissolution rate, and, in the case of electrochemical machining, the feed rate of a cathode-tool, can be more than twice higher than the rate of machining with the direct current of the same density.

Time-Varying Radiation Impedance of Microcontroller GPIO Ports and Their Dependence on Software Instructions

The coupling of short wavelength electromagnetic (EM) interference to critical electronic systems in highly reverberant enclosures is a growing concern in the EM interference/compatibility community. In such highly reverberant cavities, prior research has shown that the induced EM fields, voltages, or currents can be modeled using the wave-chaotic random coupling model (RCM). The RCM partitions the interaction within the cavity into a universally fluctuating part, derived from random matrix theory, and a system-specific part, defined by the radiation impedance of the ports of interest, where the voltages or currents are induced. Earlier researchers have treated the radiation impedance as a time-invariant, frequency-dependent complex quantity. This is true for passive structures but is not true for active semiconductor devices, such as microcontrollers, which can exhibit time-varying radiation properties depending on the instruction cycle being executed at a given instant of time. The estimate of such a time-varying radiation impedance and its correlation with instruction cycles in an elemental microcontroller is the focus of this work. Utilizing clustering algorithms, we observe that the measured radiation impedance, as well as radiative emissions, are correlated to the class of instruction cycles being executed. By clustering the radiation impedance and emissions of the general-purpose input/output ports utilizing the class of instructions being executed, predictive models for microcontroller susceptibility can be derived even when detailed knowledge of the specific instruction cycle being executed is unknown a priori. Such a predictive capability can find multiple applications in the EMI/EMC community.

Analysis of Korean-to-English Machine Translation Systems’ Treatment of Passives

This study explores how Korean-to-English machine translation (MT) systems (e.g., Google Translator, NAVER Papago) deal with Korean passive structures. Cross-linguistically, Korean and English passives show different ways to construct passive-voice sentences from active structure. English passives including with be+p.p. may have a ‘by phrase’ after the verb, which perform the agent of the action. However, Korean has three different passive structures and a rich repertoire of affixes, including case markers, which play critical roles in the production and comprehension of passives, complicating translation to English. Moreover, the grammatical constructions that express passive voice in Korean and English differ in terms of frequency in both written and spoken contexts. To explore production accuracy by two MTs, 213 Korean passive sentences were translated into English passives. This finding shows that current Korean-to-English MTs almost always produce translations that are correct in meaning when they generally translate Korean passives into English passives. They also translate Korean passives into English active voice constructions at significant rates.

High‐Output Photodetector by Microlithographic Mono‐Layer MoS2 for Image Sensor

AbstractDue to the unique structure and properties, the 2D transition metal dichalcogenides attract extensive research interest. Especially, the 2D MoS2 film with high photoelectric response makes important research progress in the field of the photodetection and image sensing. However, at present, most of the 2D material image sensors are passive pixel structures, and the interfering noise of the external readout circuit can easily lead to a decrease in the actual detection rate of the sensors. Here, a microlithographic Y‐MoS2 photodetector, which integrates three identical MoS2 photosensitive units by micro‐lithographing a mono‐layer MoS2, is reported. Compared with the MoS2 photodetector with only one photosensitive unit, the Y‐MoS2 photodetector has the stronger output and anti‐noise ability. In the image sensing test, the peak signal to noise ratio (PSNR) and structural similarity (SSIM) of output images are increased by ≈1.9 and 3 times, respectively. It provides a certain reference for the preparation of high‐output 2D material photodetectors by microlithography.

Charge Collection Dynamics of the ARCADIA Passive Pixel Arrays: Laser Characterization and TCAD Modeling

Monolithic Active Pixel Sensors (MAPS) represent one of the most promising technologies for the next generation of radiation detectors. The ARCADIA project aims at the development of Fully Depleted (FD) MAPS employing a production process compatible with a 110 nm commercial CMOS technology. The first engineering run of the project included matrices of active pixels with embedded analog and digital frontend electronics and passive test structures such as passive pixel arrays, MOS capacitors and backside diodes. Although the produced samples were already characterized from the electrical point of view, a thorough study of the charge collection dynamics of the passive pixel arrays was still missing. In this paper we show the results of the dynamic characterization of a group of passive pixel arrays with different pixel pitches (50, 25 and 10 μm) and different pixel layouts. The tested samples have been illuminated from the backside with an infrared and a red laser with wavelengths equal to 1,060 nm and 660 nm, respectively. The pixel arrays have been mounted on a custom readout PCB connected to an external amplifier with 1 GHz bandwidth and the signals have been acquired through a fast digital oscilloscope. We employed both focused and unfocused laser spots to evaluate the change in the measured signal as a function of the laser spot position and the average response of the pixel arrays. An excellent agreement has been demonstrated by comparing the measured signals with the results of transient TCAD simulations and a time for 50% charge collection of 7.8, 4.2 and 2.6 ns has been predicted and experimentally validated in pixels with 50, 25 and 10 μm pitch, respectively.