Passive Structures Research Articles

A compact bent microstrip-based wideband millimeter wave MIMO antenna for 5G applications

Abstract This paper proposes a wideband four-element multiple-input multiple-output (MIMO) antenna operating in the millimeter-wave frequency band for 5G communications from 24.37–39.44 and 45.09–50.62 GHz. The antenna design has been realized using Rogers 5880 substrate and consists of a T-shaped strip that is attached to the top of a 50 Ω feeding line. Two microstrip lines are affixed at the terminal points of T-shaped strip and bent toward the feeding structure. These bent strip lines are then extended by joining two additional L-shaped microstrip lines. On the back, there is a partial defective ground plane featuring a rectangular slot and a thin strip line located at its center. The dimensions of the proposed single element and MIMO antenna are 0.933λ × 0.933λ × 0.024λ and 1.865λ × 1.865λ × 0.024λ, respectively (at 28 GHz), while the edge-to-edge distance between the radiation elements of the MIMO antenna is 4.0 mm. The design incorporates an efficient passive fan-shaped decoupling structure to decrease coupling between antenna elements. Simulations and experimental results show good agreement with each other. For all resonant frequencies the measured peak gain is greater than 4.85 dBi, radiation efficiency is over 90%, diversity gain is greater than 9.5, ECC is less than 0.025, TARC is less than -10 dB and CCL is below 0.4 bits/s/Hz. The proposed MIMO antenna, with its wide bandwidth, high gain, high inter-port isolation, and high efficiency characteristics, can be used for 5G wireless communication applications.

Uncovering Ganymede's past: Tectonics at Nippur/Philus Sulci

Observations of Jupiter's largest moon Ganymede by Voyager and Galileo revealed fractures and evidence of strike-slip faulting, leading to studies for the mechanisms of these structures focused on extensional tectonism and gravitational tidal stresses. In this analysis, we investigate the geologic history of Ganymede in the area of Nippur/Philus Sulci (175°E, 36.9°N) by examining Galileo high-resolution data available for this region (∼100 m/pixel) and conducting a tidal stress investigation of Ganymede's past. Several crosscutting bands of light terrain in the Nippur/Philus Sulci site show varying degrees of tectonic deformation, ranging from smooth and less distorted bands to highly grooved and deformed terrain. The chronology of tectonic activity implied by mapped crosscutting relationships reveals three eras of distinct geologic activity: 1. Ancient, 2. Intermediate and 3. Youngest. Indicators of shear deformation are found throughout all ages of terrain, but mapped early-stage indicators of strike-slip features are exclusively located in intermediate and youngest terrain. An investigated offset feature in intermediate-aged terrain corresponds in slip direction to the predictions from modeling stresses of a higher past eccentricity. However, the en echelon structures found in a younger geologic unit do not align in slip direction with typical first-order R Riedel shears. This suggests that these features might have formed through another process and the observed en echelon folds could be passive structures, which can be created through relatively rapid large displacement on a fault. Through modeling of Ganymede's past tidal stresses, we can conclude that a past higher eccentricity (e > 0.02) could have distorted the Nippur/Philus Sulci region in its second, intermediate phase of main deformation, yielding a stress field conducive to shear failure of the icy upper crust. New data from NASA's Juno mission, as well as future observations by ESA's Jupiter Icy Moons Explorer (JUICE) mission and NASA's Europa Clipper mission, will further aid our understanding of the tectonic history of Ganymede and improve the resolution of tectonic feature analysis.

Is Syntax Separate or Shared Between Arabic and English? Syntactic Priming in Arabic-English Bilinguals

Syntactic priming refers to the likelihood that a particular structure is repeated when preceded by an utterance with the same or a related syntactic structure. Experimental studies that demonstrate syntactic priming have attracted the attention of scholars because syntactic priming provides insightful information about the way language is processed in the human cognitive system, facilitates dialogue and informs linguistic theories about the knowledge of language that is activated via syntactic priming. In this study, we investigate syntactic priming in 15 Arabic-English bilinguals through the Confederate-Scripted Dialogue Game technique, targeting four structures: active, passive, double-object (DO), and prepositional-object structures (PO). The results of the study indicate that the syntax of Arabic-English bilinguals is separate for each language. Participants tend to use the active structure regardless of the structure of the prime sentence. The findings of this study illustrate how the syntax of two unrelated languages (Arabic and English) is represented and processed in bilingual brains, contributing to the fields of bilingualism, syntax, psycholinguistics, and second language acquisition.

Design and correlation analysis of quasi-zero stiffness passive vibration isolation air spring

Vibration isolation systems are widely used in high-end automobile manufacturing, precision instrument processing, building and bridge seismic resistance, ship machinery noise reduction and other engineering fields, with good development prospects. At present, the existing vibration isolation systems on the market are mainly divided into active and passive vibration isolation systems. Passive vibration isolation does not require external energy input. Its structure is simple and the control scheme is easy to implement. However, passive vibration isolation performs well in high frequency vibration but not in low frequency. As a new nonlinear low-frequency vibration isolation technology, the quasi-zero stiffness vibration isolation system has changed the traditional concept of linear system vibration isolation. In addition, compared with traditional spring, air spring as a new type of elastic vibration isolation mechanism has many excellent performances, such as high fatigue resistance and high stiffness. Therefore, this paper uses air spring to design a passive vibration isolation quasi-zero stiffness air spring structure with good vibration isolation effect, simple structure and low cost in both low-frequency and high-frequency vibration.

An Enhanced Spine Model Validated for Simulating Dynamic Lifting Tasks in OpenSim.

A fully articulated thoracolumbar spine model had been previously developed in OpenSim and had been extensively validated against experimental data during various static tasks. In the present study, we enhanced this detailed musculoskeletal model by adding the role of passive structures and adding kinematic constraints to make it suitable for dynamic tasks. We validated the spinal forces estimated by this enhanced model during nine dynamic lifting/lowering tasks. Moreover, we recently developed and evaluated five approaches in OpenSim to model the external loads applied to the hands during lifting/lowering tasks, and in the present study, we assessed which approach results in more accurate spinal forces. Regardless of the external load modeling approach, the maximum forces predicted by our enhanced spine model across all tasks, as well as the pattern of estimated spinal forces within each task, showed strong correlations (r-values and cross-correlation coefficients > 0.9) with experimental data. Given the biofidelity of our enhanced model, its accessibility via the open-source OpenSim software, and the extent to which this model has been validated, we recommend it for applications requiring estimation of spinal forces during lifting/lowering tasks using multibody-based models and inverse dynamic analyses.

Acoustic Flow Sensor Using a Passive Bell Transducer

Sensing based on a passive transducer that is wirelessly linked to a nearby data collection node can offer an attractive solution for use in remote, inaccessible, or harsh environments. Here we report a pipe flow sensor based on this principle. A transducer mounted inside the pipe generates an acoustic signal that is picked up by an external microphone. The passive transducer comprises a cavity with a trapped ball that can oscillate in response to flow. Its collisions generate an acoustic signal correlated to the flow speed. The transducer is implemented on a 6 mm diameter probe and characterized as a water flow meter. The time - average microphone voltage output is calculated by an analogue circuit, without any further signal processing. With the microphone mounted on the probe, and for flow rates in the range 0.35 m/s to 6.5 m/s, correlation between the sensor voltage output and flow rate data from a commercial flow meter is demonstrated with a worst-case accuracy of 2%. This was achieved by simple averaging of the acoustic pulse train over a 5-second time interval. Consistent correlation with the microphone mounted on the pipe wall at distances up to 150 mm from the probe location is also reported. These results demonstrate the viability of remote acoustic flow sensing using passive structures and offer a simple and minimally invasive flow monitoring method.

Ultra-Wideband Six-Port Network Miniaturization—Matching

AbstractIn this paper, a new design approach for the six-port (SP) junction is introduced. The proposed design includes a generalized broadband matching and smooth miniaturization scheme and is extendable for any passive multiport structure. A multilayer technology and a microstrip to slot coupling operation are employed for the designed SP, which comprises power divider and three hybrid couplers. The conducted measurements of the constructed SP junctions validates the design approach. Optimal performance of the SP network in terms of miniaturization, bandwidth, and response accuracy were obtained for the 5G low band.

Vibration Control of Innovative Lightweight Thermoplastic Composite Material via Smart Actuators for Aerospace Applications

Piezoelectric actuators and sensors can be incorporated into aerospace structures to suppress unwanted flexible oscillations. These devices need to interact with various passive structures, including innovative materials such as thermoplastic composites, which offer several advantages over traditional options. This study explores the application of a piezoelectric-based vibration control system on a lightweight carbon-reinforced thermoplastic material. Numerical and experimental investigations are conducted to assess the mechanical properties and damping behavior of the composite. As a case study, an equivalent orthotropic shell laminate is developed to facilitate finite element modeling of two composite solar panel structures equipped to a spacecraft. Moreover, an electro-mechanical formulation is implemented to integrate smart actuators and sensors onto the composite hosting structure. Finally, the efficiency of the active vibration control system is assessed when significant vibration perturbations are caused on the panels by rigid–flexible dynamics coupling during agile attitude maneuvers. The results demonstrate the damping factor of the material can be noticeably improved, making the proposed system a promising technological solution for further aerospace applications.

Holistic pedestrian safety assessment for average males and females.

An integrated assessment framework that enables holistic safety evaluations addressing vulnerable road users (VRU) is introduced and applied in the current study. The developed method enables consideration of both active and passive safety measures and distributions of real-world crash scenario parameters. The likelihood of a specific virtual testing scenario occurring in real life has been derived from accident databases scaled to European level. Based on pre-crash simulations, it is determined how likely it is that scenarios could be avoided by a specific Autonomous Emergency Braking (AEB) system. For the unavoidable cases, probabilities for specific collision scenarios are determined, and the injury risk for these is determined, subsequently, from in-crash simulations with the VIVA+ Human Body Models combined with the created metamodel for an average male and female model. The integrated assessment framework was applied for the holistic assessment of car-related pedestrian protection using a generic car model to assess the safety benefits of a generic AEB system combined with current passive safety structures. In total, 61,914 virtual testing scenarios have been derived from the different car-pedestrian cases based on real-world crash scenario parameters. Considering the occurrence probability of the virtual testing scenarios, by implementing an AEB, a total crash risk reduction of 81.70% was achieved based on pre-crash simulations. It was shown that 50 in-crash simulations per load case are sufficient to create a metamodel for injury prediction. For the in-crash simulations with the generic vehicle, it was also shown that the injury risk can be reduced by implementing an AEB, as compared to the baseline scenarios. Moreover, as seen in the unavoidable cases, the injury risk for the average male and female is the same for brain injuries and femoral shaft fractures. The average male has a higher risk of skull fractures and fractures of more than three ribs compared to the average female. The average female has a higher risk of proximal femoral fractures than the average male. A novel methodology was developed which allows for movement away from the exclusive use of standard-load case assessments, thus helping to bridge the gap between active and passive safety evaluations.

Effect of plasma-assisted N2O/Ar oxidation on TOPCon solar cells

N2O/Ar gas mixture are used to deposit ultra-thin silicon oxide (SiOx) layer by plasma enhanced chemical vapor deposition (PECVD), which is used as the tunneling oxide layer in the TOPCon (tunnel oxide passivated contacts) structure. It is found that the N2O/Ar flow ratios strongly affect the properties of SiOx layer, such as deposition rate, the resistance of high temperature, passivation quality, etc., thus significantly affect the properties of polysilicon passivated contact structures and the efficiency of TOPCon solar cells. The deposition rate of SiOx layer and contact resistivity of SiOx/poly-Si(n+)/SiNx:H structure decrease with the increases of Ar flow. However, there is an optimal N2O/Ar flow ratio to obtain the best passivation quality and the champion efficiency. The optimal flow ratio of N2O/Ar= 5:2 is found, and obtain the optimum thickness of SiOx and uniform polysilicon passivated contact. The highest minority carrier lifetime (τ) of 5751 μs, highest implied open circuit voltage (iVoc) of 741.3 mV, lowest single side recombination saturation current density(J0) of 4.79 fA/cm2, contact resistivity(ρcontact) of 2.23 mΩ/cm2 and champion efficiency of 25.06% are obtained at the flow ratio of N2O/Ar= 5:2.

Numerical Simulation Analysis and Full-Scale Experimental Validation of a Lower Wall-Mounted Solar Chimney with Different Radiation Models

As a type of passive architectural structure, wall-mounted solar chimneys enhance the natural ventilation volume of a building’s interior, and maximize reductions in the building’s operational energy consumption. They are indispensable in the building’s energy conservation and emission reduction. Therefore, measuring the wall-mounted solar chimney’s flow characteristics and relevant index parameters is particularly important. This paper uses a combination of full-scale experiments and numerical simulation to conduct a detailed analysis of the wall-mounted solar chimney. Four different radiation models, namely DO (discrete ordinates), S2S (surface-to-surface), MC (Monte Carlo), and Rosseland are used for comparison, and the results of the numerical simulation are compared with the experimental data. The results show that the maximum turbulent viscosity of the fluid predicted by the S2S radiation model is higher than that of the MC and DO models by 16.87% and 8.44%, respectively. The errors of the DO radiation model in the midline and glass cover plate direction concerning the experimental results are only 0.33% and 0.15%, respectively. The mistakes of the MC radiation model in these two directions are 0.51% and 0.47%, respectively. The DO radiation model is more suitable in numerical simulation predictions related to the wall-mounted solar chimney.

Beyond 25% efficient crystalline silicon heterojunction solar cells with hydrogenated amorphous silicon oxide stacked passivation layers for rear emitter

Hydrogenated amorphous silicon oxide (a-SiOx:H) alloy is considered as a promising alternative to hydrogenated amorphous silicon (a-Si:H) in crystalline silicon heterojunction (SHJ) solar cells due to its reduced parasitic absorption induced by the incorporation of oxygen. However, the large valence band offset (ΔEV) between a-SiOx:H and crystalline silicon (c-Si) usually leads to low fill factor (FF) for the solar cells. Here, we designed a trilyer a-SiOx:H(i) stacked passivation scheme underneath the rear emitter (p) for the SHJ solar cell on n-type c-Si wafer via depositing the a-SiOx:H(i) layers with different oxygen contents by plasma-enhanced chemical vapor deposition (PECVD). Highly efficient SHJ solar cells with the average efficiency of 25.37% were obtained by optimizing the trilayer a-SiOx:H(i) passivation structure with an oxygen-rich layer inserted between two oxygen-less layers. Comparing to the solar cells with complete a-Si:H passivation layers, higher short-circuit current density (JSC) and open-circuit voltage (VOC) of the solar cells were achieved, which indicated excellent passivation and low parasitic absorption contributed from the a-SiOx:H(i) stacked layers. At the same time, FF of the solar cells was also increased slightly. The corresponding improvement mechanisms were analyzed carefully. As a demonstration, the highest efficiency of the SHJ solar cells passivated by the trilayer a-SiOx:H(i) scheme for rear emitter was up to 25.44%.

Energy Efficiency Optimization of IRS-Assisted UAV Networks Based on Statistical Channels

In this letter, intelligent reflecting surface (IRS) is adopted to assist unmanned aerial vehicle (UAV) to achieve energy-efficient transmission. Specifically, the energy efficiency is maximized by jointly optimizing the UAV trajectory, transmit power and IRS phase shifts based on the statistical channel state information (CSI), since the instantaneous CSI is difficult to obtain due to the mobility of UAV and the passive structure of IRS. The non-convex problem is decomposed into two sub-problems of the trajectory and transmit power optimization, and the phase-shift optimization. To deal with the non-convexity of the first one, the successive convex approximation and Dinkelbach’s algorithm are utilized. For the second one, a closed-form solution is derived directly through equivalent transformations. Then, the two sub-problems are solved iteratively to obtain an effective solution to the original problem. Simulation results are presented to validate the effectiveness of the proposed scheme.

AC Losses Calculations for the ITER CS and PF Magnet Systems During Plasma Operation

While the ITER magnet system assembly is progressing, models are being developed to predict the performances of the coils in support of the preparation of commissioning and operation. In particular, the AC losses generated in the coils during a plasma scenario need to be estimated as input to thermo-hydraulic performance simulations. The largest AC losses during plasma operation are expected in the CS and PF coils. This paper discusses the results of simulations of AC losses in these coils during a representative ITER plasma pulse. These calculations also take into account the electromagnetic screening provided by the ITER passive structures, most importantly the vacuum vessel, discussing its impact on the conductor AC losses. The results will also be compared to earlier predictions. Finally, the CS and PF coil AC losses expected during commissioning will be briefly discussed.

How does the pore solution chemistry influence the passivation of reinforced alkali‐ and salt‐activated slag materials?

AbstractService life predictions of reinforced concrete structures are underpinned by the passivation film chemistry, structure, and thickness. In this work, we present how the formation of passive films at the steel–concrete interface of reinforced alkali‐ and salt‐activated slag materials can be affected by the pore solution chemistry, namely, pH, Eh, and chemical composition. Thermodynamic simulations are used to illustrate the time‐dependent changes to the pore solution chemistry, where estimated electrical conductivities of the pore solution are used as a single‐value parameter to understand the solution complexity and capacity for charge transfer. A set of passivation reactions are proposed to understand the effects of OH− and HS− (reduced sulfur species) competition on the passivation pathways. These passivation reactions become more complex considering that a reducing pore solution might not establish until 3 days into the curing process—a crucial factor explaining the significant differences in the phase composition of passive films of activated slag materials (FeOOH, FeS). This study sheds light on recent progress in understanding these initial passivation reactions, emphasizing the essential role of material design and, therefore, the pore solution chemistry of these cements, along with significant insights for vital research and development concerning the corrosion durability of activated slag materials.

Approximate analytical solution of a (V,m,h) reduced system for backpropagating action potentials in sparsely excitable dendrites

We derive an approximate analytical solution of a nonlinear cable equation describing the backpropagation of action potentials in sparsely excitable dendrites with clusters of transiently activating, TTX-sensitive Na+ channels of low density, discretely distributed as point sources of transmembrane current along a continuous (non-segmented) passive cable structure. Each cluster or hot-spot, corresponding to a mesoscopic level description of Na+ ion channels, included known cumulative inactivation kinetics observed at the microscopic level. In such a reduced third-order system, the ‘recovery’ variable is an electrogenic sodium-pump and/or a Na+-Ca2+ exchanger imbedded in the passive membrane, and a high leakage conductance stabilizes the system. A nonlinear cable equation was used to investigate back-propagation and repetitive activity of action potentials, exhibiting characteristics of the modified Hodgkin-Huxley kinetics (in the presence of suprathreshold input). In particular, a time-dependent analytical solution was obtained through a perturbation expansion of the non-dimensional membrane potential (Φ) for all voltage dependent terms including the voltage dependent Na+ activation μ) and state-dependent inactivation (η) gating variables and then solving the resulting system of integral equations. It was shown that back-propagating action potentials attenuate in amplitude with the frequency following experimental findings and that the discrete and low-density distributions of transient Na+ channels along the cable structure contribute significantly to their discharge patterns. A major significance of integrative modelling is the provision of a continuous description of the non-dimensional membrane potential (Φ) as a function of position.

Single-channel acoustic vortex tweezer with attachable fan-shaped holographic lens

The utilization of acoustic vortices presents a promising technique for contactless particle manipulation. However, existing methods for generating acoustic vortices typically rely on complex active driving systems and array ultrasound transducers. Therefore, more simplified and robust approaches to inducing acoustic vortices should be considered. With inspiring the fact that acoustic vortices can be generated by the differences in the height of adjacent sectors in conventional four-panel transducers, we aim to develop a single-channel acoustic vortex tweezer with a simplified driving system by incorporating attachable fan-shaped polydimethylsiloxane (PDMS) holographic lens. This passive lens structure with different heights in adjacent sectors can generate phase-modulated ultrasonic waves. Therefore, the interaction of phase-modulated waves passing through the lens is expected to result in a vortex-like beam. The available materials of fan-shaped lens are not limited to the PDMS. This lens type can be appropriately fabricated with an understanding of the sound of speed within the desired material and predetermined thickness, inducing π/2 phase difference in the adjacent lobes. As a result, the excited acoustic waves propagated through the lens were under mutual interaction without any active electrical setup, forming a null pressure region enveloped by four distinct acoustic lobes. We systemically investigated the tweezing potential using vortex-like waves. Several types of bioparticles were utilized in these investigations: microbubbles, polystyrene (PS) beads, and cancer cells. Our findings demonstrate that the transducer with lens is sufficiently capable of spatial manipulation of bioparticles. Remarkably, the microbubbles traveling at a flow velocity of 32 cm/s in a blood vessel-mimicking phantom were feasibly trapped in the proposed transducer. Furthermore, the spatial control of PS and cells with higher acoustic impedance was also feasible in static conditions. Consequently, the proposed transducer offers an economically and practically viable solution for various biomedical applications, such as drug delivery and cell-based bioengineering.

Comparison of Flexion Relaxation Phenomenon After Single-Level and Multi-Level Anterior Cervical Discectomy and Fusion

This prospective cohort study aimed to assess the influence of the number of fused segments in cervical paravertebral muscles by comparing the changes of the cervical flexion relaxation phenomenon (FRP) after single-level versus multilevel anterior cervical discectomy and fusion (ACDF). A total of 115 patients who had undergone ACDF were retrospectively recruited and divided into a 1-level group (n= 44), a 2-level group (n= 40) and a 3- to 4-level group (n= 31). The flexion relaxation experiment was carried out 3 days preoperatively and 12 months postoperatively by surface electromyography (SEMG). Patients were examined using the neck visual analog scale, cervical Japanese Orthopedic Association score, Neck Disability Index, and C2-C7 range of motion (ROM). There was a significant difference in the time-related changes in flexion relaxation ratio (FRR) among the 3 study groups before and after surgery (F= 85.701; P < .001). Thirty-five patients (79.55%) with 1-level ACDF and 11 patients (27.5%) with 2-level ACDF had FRP were restored to normal at 12 months postoperatively; however, only 1 patient (3.33%) had normalized FRP after 3- to 4-level ACDF. There were significant differences in the time-related changes of the normalized SEMG root mean square values in each phase before and after surgery (P= .018, <.001, <.001, and <.001). A significant correlation was found between the changes in C2-C7 ROM and FRR in the 3 study groups (P= .007 for 1 level, P= .003 for 2 levels, and P=.036 for 3-4 levels). Single-level ACDF contributes to normalizing the FRP of cervical paravertebral muscles, which is not ideally recovered by 2-level ACDF. In contrast, 3- or 4-level ACDF could not normalize the cervical FRP. Our research supports the passive structure hypothesis.

THE FUNCTIONAL-COMMUNICATIVE VALUE OF PASSIVE CONSTRUCTIONS IN ENGLISH AND ARMENIAN VERSIONS OF THE RA FAMILY CODE

The article examines the use of passive voice and passive structures in the legal context, and particularly its use in the English and Armenian versions of the RA Family Code. Based on qualitative and quantitative, as well as case study methodology, the purposeful use of passive structures, their tendency to ensure maximum accuracy, as well as their functional-communicative features and the functions performed by them in legal speech are revealed in the study. The research also states that the frequency of applicability of the passive voice is due to the emphasis on the role of the action and not on the doer in both English and Armenian versions of the mentioned document belonging to legal discourse.

Aesthetic Experience and Empathy in Vasily Sesemann’s Phenomenological Aesthetics

ABSTRACTVasily Sesemann’s aesthetics is a transcendental philosophy that seeks to answer the question of how an experience of beauty is possible. Sesemann insists that aesthetics should focus on the study of the aesthetic object itself, and through it go to the problematics of the act of perception and creativity. Sesemann states that not only the relationship between the work of art and the perceiver is important in order to understand the aesthetic object, but also the relationship between the work of art and the creator. The aesthetic object in its sedimented form not only retains indications of the act of creation, but also makes demands on the perceiving subject. Aesthetic objects are sedimented passive structures that can be activated by the performative actions of the perceiver when she discovers the appropriate way of perception. Sesemann, like Moritz Geiger, claims that aesthetics is impossible without an analysis of feelings. He, like Geiger, recognizes the importance of empathy in aesthetic experience. However, Sesemann develops the concept of aesthetic empathy using Max Scheler’s arguments. Empathy is necessary, because the perceiver must be able to understand expressions. The aim of this paper is to analyse the phenomenological aspects of Vasily Sesemann’s aesthetics. Firstly, this paper analyzes the Sesemann’s phenomenology of aesthetic experience. Secondly, it shows that the analysis performed by Sesemann demonstrates why empathy plays a leading role in aesthetic experience.