Asymmetric Structure Research Articles

Impact of potential function asymmetry on the performance of a novel stochastic resonance system

Due to output saturation and parameter coupling, the traditional classical bistable stochastic resonance (CBSR) system is often unable to effectively handle the extraction of weak signal features encountered in many engineering applications. To overcome this limitation, an asymmetric decoupled unsaturated bistable stochastic resonance (ADUBSR) system is proposed in this paper. Subsequently, the impact of barrier asymmetry on system output has been analyzed by taking signal-to-noise ratio (SNR), peak signal-to-noise ratio (PSNR), and the optimal noise required for obtaining PSNR as evaluation indicators. The results indicate that: (1) The output SNR is effectively enhanced by barrier-width asymmetry only when the left barrier is narrower than the right. (2) Barrier-height asymmetry fails to effectively improve the output SNR. (3) In the case of barrier-height-width asymmetry, the barrier width asymmetry predominantly enhances the output SNR, resulting in the best performance. (4) For all three asymmetric structures, regardless of noise type, the optimal noise intensity depends greatly on barrier height and width values, and is less influenced by asymmetry. Finally, the proposed system is used for engineering data, and the results show that the signal processed by the ADUBSR system achieves a higher output SNR and the amplitude at the fault frequency is 10 times greater than that of the signal processed by the CBSR system.

Non-fullerene acceptor with asymmetric structure and phenyl-substituted alkyl side chain for 20.2% efficiency organic solar cells

Non-fullerene acceptor with asymmetric structure and phenyl-substituted alkyl side chain for 20.2% efficiency organic solar cells

Bionic programmed wearable actuators based on 4D printing of liquid metal-spidroin-liquid crystal elastomer composite

ABSTRACT As a pivotal component of robotic systems and wearable devices, flexible actuators play a significant role; while it remains a challenge to achieve intelligent applications due to complex high-degree-of-freedom deformation control and insufficient functionality. Here, inspired by the leaf structure of Ficus benjamina 'Barok', a new type of programmable flexible actuator (PFA) prototype that can be 4D printed is designed, featuring a liquid metal-spidroin-liquid crystal elastomer composite printing functional structure and microstructure substrate, which achieves selective actuation and integrates sensing functions through differentiated manufacturing and pattern design. The interior of PFA is composed of functional masks with photothermal effects and differentiated photopolymerization mesogen structures. The microscopic rearrangement of asymmetric structures at different positions makes remote control of programming deformation convenient. Furthermore, benefiting from the integration of material properties, PFA can sense strain through resistive changes and connect to intelligent devices to transmit signals. The motion support and sensing performance of PFA have the potential to be applied to advanced robotics and human-machine interfaces.

Feasibility Study on Active Structural Attenuation: Addressing Multiband Vibration in Automotive Vehicles on 2D Asymmetric Structures with a Faulty Horizontal Actuator

This work presents a study on the modeling, analysis, and control of asymmetric source structures, which focuses on a multi-directional active mounting system that aims to consider the location and orientation of an actual automotive powertrain mount. An active mount was created by connecting a PZT (piezo-stack) actuator with a rubber grommet. Additional force necessary for every mount was determined by using forces caused by harmonic stimulation and the control input has the capability to reduce vibrations by engaging in detrimental opposition against the input. In addition, the vibration in the horizontal direction can be reduced with the adjustment of variables that can be modified via the dynamic interconnection of the source frame. This study especially evaluated the effectiveness of vibration reduction without a horizontal active component and determined the feasibility of control. Through sequences of simulated outcomes, it was demonstrated that the implementation of this asymmetric, bi-directional (both horizontally and vertically) active mount may effectively reduce stimulation oscillations. Additionally, a numerical validation was performed to reduce the vibrations generated by the modulation. It was accomplished by observing the system’s response utilizing a digital filter with a normalized least mean square method. The simulations of adaptive digital filters demonstrated that the efficacy of control diminishes when faced with intricate noise and signals, while the attenuation trend stays unaltered.

Strong coupling in an asymmetric two-dimensional guided mode resonance metasurface structure and enhancement for optical third-harmonic generation

A two-dimensional guided mode resonance structure supports a transverse magnetic (TM) resonant mode in the direction of incident polarization and a transverse electric (TE) resonant mode in the direction perpendicular to the polarization. In this work, the coupling between the transverse magnetic and the transverse electric resonant modes in an asymmetric two-dimensional dielectric metasurface structure is investigated. The asymmetric structure consists of a two-dimensional square nanohole array etched in a titanium dioxide thin film on a transparent silica substrate. With finite difference time domain simulations, anti-crossing of the resonant spectra of the TM and TE modes is observed by adjusting the asymmetry of the structure. The anti-crossing indicates that the interaction between TM and TE resonant modes results in a strong coupling state. A coupled harmonic oscillator model is used to explain the strong coupling effect. The results of the coupled harmonic oscillator modeling agree well with the results of numerical simulations. Furthermore, it is shown that the strong coupling can significantly enhance the third harmonic generation intensity compared with the uncoupled TM and TE resonant modes.

Two-Stage Optimal Design Method for Asymmetric Base-Isolated Structures Subject to Pulse-Type Earthquakes

Asymmetric base-isolated structures subjected to severe torsion may suffer further aggravation of their torsional and translational responses under pulse-type earthquakes. To counteract these detrimental impacts, this study introduces a two-stage optimal design method. The first stage involved the application of the NSGA-II algorithm for determining an optimal isolator arrangement—namely, position and category—with the objective of reducing both the maximum interstory rotation of the superstructure and the isolation layer. In the second stage, the inclusion of viscous dampers served to minimize the excessive translational response triggered by pulse-type earthquakes. The influence of these dampers’ positions on the structural response was carefully evaluated. The final application of this optimal design method was demonstrated on an asymmetric base-isolated structure. The results indicated a significant reduction in the translational and torsional responses of the asymmetric base-isolated structure when the two-stage optimal design method was utilized, compared to those of structures designed using traditional conceptual methods. It was found that by installing viscous dampers in the isolation layer along both the x and the y directions—specifically, underneath the mass center of the superstructure (CMS)—the effectiveness of the torsional resistance from the first stage could be effectively maintained.

A dynamic rifting model of the Caroline Ridge, West Pacific

The dynamic rifting model of the Caroline Ridge, an oceanic plateau in the West Pacific, remains unclear. Previous studies have revealed that the crustal width of the Caroline Ridge clearly varies from the northwest to the southeast. Here, we investigate Caroline Ridge rifting using numerical simulation and reveal the relationships between different plateau sizes and rifting. For small-scale oceanic plateaus, the initial rift migration forms a symmetric structure. The strain transfers toward one side of the margin. The rifting manifests as a process from landward migration to seaward migration, accompanied by a transition from a symmetric to an asymmetric structure. With larger initial lithospheric thinning, larger ranges of crustal deformation appear with less basement tectonic subsidence. For large-scale oceanic plateaus, basement tectonic subsidence occurs within narrower ranges. The proximal half-graben structures rapidly abandon with relatively horizontal basement and small fault offsets on the rift flank, leading to a symmetric structure during breakup. With larger initial lithospheric thinning, crustal deformation occurs within a narrower region during the early stage. Landward rift migration dominates the deformation, resulting in an asymmetric structure. On the basis of these results, for the large-scale section of the Caroline Ridge, NW-trending normal faults originated from the landward rift migration. At present, seaward rift migration dominates the Caroline Ridge deformation, forming a relatively symmetric structure. For the small-scale section of the Caroline Ridge, the initial landward rift migration occurred. Larger initial lithospheric thinning may exist beneath the Caroline Ridge during the initiation of Miocene rifting.

Hyphenation of Liquid Chromatography and Trapped Ion Mobility - Mass Spectrometry for Characterization of Isomeric Phosphatidylethanolamines with Focus on N-Acylated Species.

In prior research, hydrophilic interaction liquid chromatography coupled to tandem mass spectrometry (HILIC-MS/MS) has demonstrated applicability for characterizing regioisomers in lipidomics studies, including phosphatidylglycerols (PG) and bis(monoacyl)glycerophosphates (BMP). However, there are other lipid regioisomers, such as phosphatidylethanolamines (PE) and lyso-N-acyl-PE (LNAPE), that have not been studied as extensively. Therefore, hyphenated mass spectrometric methods are needed to investigate PE and LNAPE regioisomers individually. The asymmetric structure of LNAPE favors isomeric species, which can result in coelution and chimeric MS/MS spectra. One way to address the challenge of chimeric MS/MS spectra is through mobility-resolved fragmentation using trapped ion mobility spectrometry (TIMS). Therefore, we developed a multidimensional HILIC-TIMS-MS/MS approach for the structural characterization of isomeric phosphatidylethanolamines in both negative and positive ionization modes. The study revealed the complementary fragmentation pattern and ion mobility behavior of LNAPE in both ionization modes, which was confirmed by a self-synthesized LNAPE standard. With this knowledge, a distinction of regioisomeric PE and LNAPE was achieved in human plasma samples. Furthermore, regioisomeric LNAPE species containing at least one unsaturated fatty acid were noted to exhibit a change in collision cross-section in positive ionization mode, leading to a lipid characterization with respect to fatty acyl positional level. Similar mobility behavior was also observed for the biological LNAPE precursor N-acyl-PE (NAPE). Application of this approach to plasma and cereal samples demonstrated its effectiveness in regioisomeric LNAPE and NAPE species' elucidation.

Antenna-enhanced high-resistance photovoltaic infrared detectors based on quantum ratchet architecture

We demonstrate a quantum ratchet detector, which is a high-resistance photovoltaic mid-infrared detector based on an engineered spatial arrangement of subbands. In photovoltaic quantum-well photodetectors, in which unidirectional photocurrent is generated by asymmetric quantum-well structures, maximization of device resistance by suppressing undesired electron transports is crucial for minimizing noise. A semi-quantitative guideline suggests the significance of spatial separation between wavefunctions for reducing the conductance from the ground state. Here, we employ a step quantum well made of a shallow floor and a deep well. Photoexcited electrons are quickly transferred to a separated location from the ground state through fast resonant tunneling and phonon scattering, and then they are allowed to flow in only one direction. This architecture is made possible by the use of a GaAs/AlGaAs material system, and it achieves a resistance as high as 6.0 × 104 Ωcm2 with a single-period structure. Combined with optical patch antennas for responsivity enhancement, we demonstrate a maximum background-limited specific detectivity of 6.8 × 1010 cmHz1/2/W at 6.4 μm, 77 K for normal incidence, and a background-limited-infrared-photodetector temperature of 98 K.

Bioinspired Superhydrophobic All-In-One Coating for Adaptive Thermoregulation.

The development of scalable and passive coatings that can adapt to seasonal temperature changes while maintaining superhydrophobic self-cleaning functions is crucial for their practical applications. However, the incorporation of passive cooling and heating functions with conflicting optical properties in a superhydrophobic coating is still challenging. Herein, an all-in-one coating inspired by the hierarchical structure of a lotus leaf that combines surface wettability, optical structure, and temperature self-adaptation is obtained through a simple one-step phase separation process. This coating exhibits an asymmetrical gradient structure with surface-embedded hydrophobic SiO2 particles and subsurface thermochromic microcapsules within vertically distributed hierarchical porous structures. Moreover, the coating imparts superhydrophobicity, high infrared emission, and thermo-switchable sunlight reflectivity, enabling autonomous transitions between radiative cooling and solar warming. The all-in-one coating prevents contamination and over-cooling caused by traditional radiative cooling materials, opening up new prospects for the large-scale manufacturing of intelligent thermoregulatory coatings.

Impact of a contract manufacturer's entry on two competing platforms' sourcing strategies

Many platforms, including the likes of Google, Amazon, and Microsoft, are now no longer merely satisfied with providing services or software but are increasingly eager to shape the future landscape of hardware devices. However, contract manufacturers (CMs) who supply hardware devices to such platforms might also produce competing products. This potential competition could prompt these platforms to consider in-house production for their devices. Motivated by this practice, we investigate the sourcing strategies of two competing platforms in the presence of a CM's entry and further explore the interaction between entry and sourcing strategies in a platform supply chain. The platforms select between insourcing the device through in-house production and outsourcing it to the CM. We find that, without entry, the CM's large cost advantage in producing the device relative to the platform induces the platform to choose the outsourcing strategy. In contrast, under entry, the equilibrium sourcing structures hinge upon the extent of the production cost difference between the platform and the CM in producing the device, as well as the degree of the high-efficiency platform's advantage in research and development efficiency over the low-efficiency platform in designing the platform. Particularly, when the CM enters through the platform with low efficiency, the asymmetric sourcing structure in which only the low-efficiency platform outsources is not an equilibrium, whereas the other sourcing structures may exist in equilibrium. Furthermore, in asymmetric sourcing structures, the large production cost difference prevents the CM from entering the market and, more intriguingly, the CM prefers the platforms to adopt the insourcing strategy to gain favourable market entry if the cost difference in producing the device is small. Several extensions are studied to obtain additional insights and demonstrate the robustness of the main findings from the baseline model.

Light‐activated 3D printed fish‐like actuator

AbstractHydrogel‐based actuators are innovative materials that exhibit responsive and dynamic behavior in response to external stimuli, making them promising candidates for a wide range of applications in fields such as soft robotics. We employ 3D printing to create layered rectangles, using a passive ink composed of gelatin methacryloyl (GelMA) and an active ink consisting of GelMA and poly(N‐isopropylacrylamide) (PNIPAM). Our aim is to assess and compare the bending capabilities of these structures based on their layer arrangements in a buffer above the lower critical solution temperature. Therefore, an asymmetric rectangular structure is selected as the shape‐changing component in the tail of a 3D printed fish‐shaped hydrogel actuator. We show that gold nanostars integrated into the actuators serve as photothermal elements, enabling the fish tail to repeatedly bend when near infrared light is turned on and off. Our effort illustrates the potential of combining 3D printing, responsive hydrogels and photothermal elements with near infrared light towards soft robotic applications. This combination yields actuators capable of shape‐shifting without requiring localized light or transitioning between environments with varying temperatures.

Negative curvature fiber (NCF) polarization filter with large polarization loss ratio and ultralow loss in the terahertz range

A high-performance polarization filter based on the negative curvature fiber (NCF) with an asymmetric cladding structure is proposed and analyzed. The resonant effects of the x-polarization fundamental mode (XPFM) of the NCF are enhanced by the single-layer semi-elliptical tubes with a gradient wall thickness in the x-axis direction, while the anti-resonant effects of the y-polarization fundamental mode (YPFM) are strengthened by the nested double-layer elliptical tubes in the y-axis direction. The optimized structure shows a polarization loss ratio of greater than 100 in the range of 0.98–1.02 THz in addition to propagation losses of 0.94 dB/m and 7.43 × 10−4 dB/m at 1 THz for XPFM and YPFM, respectively. A polarization loss ratio of 1,276 is achieved and the polarization loss ratio is 6,321 at 0.98 THz. Our results show that the NCF polarization filter delivers better performance than recently reported filters in the terahertz band and the results reveal a new strategy to design high-performance polarization filters.

Hybrid Double-Sided Tape with Asymmetrical Adhesion and Burst Pressure Tolerance for Abdominal Injury Treatment.

Patients with open abdominal (OA) wounds have a mortality risk of up to 30%, and the resulting disabilities would have profound effects on patients. Here, we present a novel double-sided adhesive tape developed for the management of OA wounds. The tape features an asymmetrical structure and employs an acellular dermal matrix (ADM) with asymmetric wettability as a scaffold. It is constructed by integrating a tissue-adhesive hydrogel composed of polydopamine (pDA), quaternary ammonium chitosan (QCS), and acrylic acid cross-linking onto the bottom side of the ADM. Following surface modification with pDA, the ADM would exhibit characteristics resistant to bacterial adhesion. Furthermore, the presence of a developed hydrogel ensures that the tape not only possesses tissue adhesiveness and noninvasive peelability but also effectively mitigates damage caused by oxidative stress. Besides, the ADM inherits the strength of the skin, imparting high burst pressure tolerance to the tape. Based on these remarkable attributes, we demonstrate that this double-sided (D-S) tape facilitates the repair of OA wounds, mitigates damage to exposed intestinal tubes, and reduces the risk of intestinal fistulae and complications. Additionally, the D-S tape is equally applicable to treating other abdominal injuries, such as gastric perforations. It effectively seals the perforation, promotes injury repair, and prevents the formation of postoperative adhesions. These notable features indicate that the presented double-sided tape holds significant potential value in the biomedical field.

Janus XMPYS (X=Se, Te; M=Mo, W; Y[dbnd]Al, Ga) monolayers with enhanced spintronic properties and boosted solar-to-hydrogen efficiency for photocatalytic water splitting

In this article, we investigate the potential feasibility of new Janus XMPYS (X = Se, Te; M = Mo, W; YAl, Ga) monolayers using first-principles calculations. All eight studied monolayers are shown to be direct semiconductors with moderate bandgaps ranging from 1.30 eV to 1.47 eV. The asymmetric structure of Janus XMPYS together with the presence of heavy transition metals (M = Mo, W) results in the considerable valley and Rashba spin-splittings desirable for valleytronic and spintronic applications. It is also shown that strain can be used to modulate the spin-related properties of the proposed structures. Among XMPYS monolayers, the four with X = Se meet the band alignment requisite for overall water splitting. Moreover, these monolayers are predicted to have excellent solar-to-hydrogen efficiency of 25.61%–28.08%. Excitingly, it is found that by applying tensile strain an impressive efficiency of 39% can be achieved in SeWPAlS and SeWPGaS monolayers.

A Review on Seismic Performance of Asymmetric Buildings with Shear Walls

There is an increasing trend in the construction field to build structures that are asymmetric both horizontally and vertically due to the need for unique aesthetic appearance. Also, the increase in population forces people to build structures in densely populated cities leading to scarcity of land for construction. Many other circumstances pave the way for structures to be irregular in nature. These structures have to be made seismically resistant in order to avoid loss of life and property. Shear walls are one among the solutions to conditions that don't satisfy seismic resistance. They have high stiffness which counteracts the lateral loads of the building due to earthquake forces. This study aims at providing insight to major findings about the behavior of asymmetric structures with different locations of shear walls in terms of seismic response parameters.

Some novel results of a two-community SIR model with asymmetric structure

In this paper, a two-community SIR model with an asymmetric structure is proposed. We provide a concise method to derive an explicit formula of the basic reproduction number ℛ0 and present a route conception for the explanation of ℛ0. Finally, we find a close relationship between ℛ0 and the final size by the Perron–Frobenius theorem and the Krasnoselskii fixed point theorem.

A voltage-driven dual-mode MoSe2 photodetector with graphene as van der Waals contact

Two-dimensional (2D) molybdenum selenide (MoSe2) is promising for use in the development of photodetectors for the harvesting of light from the ultraviolet to the near-infrared band, while high responsivity and fast response speed are difficult to simultaneously realize. Herein, we present a dual-mode MoSe2 photodetector with asymmetric electrodes, in which graphene and Cr metal are utilized as ohmic and Schottky contacts, respectively. The photodiode possesses fabulous Schottky characteristics, with a rectification ratio of ∼250 and a low dark current of ∼40 pA at −1 V. Under forward bias voltage of 1 V, the photodetector works in photoconductive mode with a slow response speed (decay time: ∼5 min) but high responsivity (632 mA W−1). However, at reverse bias voltage, the photodetector acts as a photovoltaic-type device due to the Schottky barrier between Cr and MoSe2. Because of the reinforced built-in electric field, the photodetector driven at −5 V shows much faster response speeds (rise time: 1.96 ms; decay time: 755 µs). This study provides a deep understanding of asymmetric structure MoSe2 photodetectors operated in two modes, which promotes a forward step toward 2D material optoelectronics.

Josephson diode effect in junctions of superconductors with band asymmetric metals

At interfaces connecting two superconductors (SCs) separated by a metallic layer, an electric current is induced when there is a disparity in the phases of the two superconductors. We elucidate this phenomenon based on the weights of the Andreev bound states associated with the states carrying currents in forward and reverse directions. Typically, current phase relation (CPR) in Josephson junctions is an odd function. When time reversal and inversion symmetries are broken at the junction, CPR ceases to be an odd function and the system may exhibit Josephson diode effect. This phenomenon has been studied in spin orbit coupled systems under an external Zeeman field wherein the magnetochiral anisotropy is responsible for the Josephson diode effect. Recently introduced the band asymmetric metal (BAM) model presents a novel avenue, featuring an asymmetric band structure. We investigate DC Josephson effect in SC-BAM-SC junctions and find that band asymmetry can lead to Josephson diode effect and anomalous Josephson effect. We explain the mechanism behind these effects based on interference of plane wave modes within the Bogoliubov de-Genne formalism. We calculate diode effect coefficient for different values of the parameters.

Coupling of supra-to sub-salt structures during gravity gliding: A physical analogue modelling investigation

Viscous salt layers can introduce significant structural complexity to the basins in which they are deposited. Along basin margins, salt typically flows basinward due to regional tilting of the margin, and can be influenced by the geometry of the surface that it flows over (e.g. fault scarps on the base-salt surface). This interaction can lead to coupling of sub- and supra-salt structures, with the orientation and distribution of base-salt structures reflected in the structure of the overburden. However, the controls on the degree of strain coupling during salt-detached translation are relatively poorly understood, in particular the roles played by the thickness and mechanical heterogeneity of the salt unit. This is, in part, caused by difficultly in deconvolving the relative contribution of variables such as salt thickness, the magnitude of base-salt relief, sediment supply, and regional tectonic regime. In addition, seismic reflection data provide only the present structure of the basin, from which its evolution must be inferred.To evaluate the influence of salt thickness and heterogeneity on sub-to supra-salt strain coupling during salt-detached translation in the extensional domain, we present a series of physical analogue models with controlled boundary conditions. We use a model apparatus with a simple geometry comprising three oblique basal steps, and vary the thickness and composition of the salt analogue in each experiment to evaluate the proposed variables. X-ray tomography allows us to image the internal structure during model evolution and therefore gain a 4D view of its structural development. Results show that supra-salt structures associated with thicker and more homogeneous salt units are characterised by symmetric extensional structures and large diapirs, with significant vertical and lateral displacements and only weak coupling to the underlying base-salt relief. Conversely, thinner and more heterogeneous salt units are characterised by asymmetric extensional structures and primary welds, with restricted vertical displacement, such that the resultant overburden structure is strongly coupled to the geometry of the base-salt surface. These results document the important role of base-salt relief in the structural evolution of salt basins and provide model analogues that are valuable assets in seismic interpretation efforts on salt-influenced basin margins.