Complicated Configurations Research Articles

Narrow-band filter design of phononic crystals with periodic point defects via topology optimization

Designing multichannel narrow passband filters working at specified frequencies is very challenging because a narrow defect band with non-zero group velocity must be achieved. This study proposes an effective topology optimization methodology for designing periodic defect unit cells in the bandgap supercell to form a specified narrow passband within the desired frequency range. A new topological optimization formulation aiming to determine the highest transmission rate around specified frequency of supercells is developed. The complicated topology configurations of the perfect bandgap unit cell and periodic defect unit cell are both described by only fifty design variables with the material-field series expansion model, and the optimization problem is solved with the sequential Kriging-based non-gradient algorithm. Through the proposed methodology, several narrow passband filtering supercell configurations with different specified frequencies are achieved. Furthermore, a multi-channel narrow filter conceptual device that can split the incident waves of three similar frequencies is designed with the optimization solutions.

Innovation Ecosystems in the Automotive Industry between Opportunities and Limitations

The creation of effective innovation ecosystems (IES) at the national or sectoral level remains a difficult and not always feasible task. Basing on evidence from the Brazilian automotive industry, a case of unused opportunities for building a strong IES is considered. This is due to the insensitivity of such ecosystems to new complicated configurations and the formats of non-traditional interaction that they suggest - a “new ecology of competition”, etc. The internal context of companies in relation to the practice of open innovation has been studied. Despite joint projects with close value chain partners, carmakers are showing a closed attitude to external collaboration, unlike players in industries such as aerospace or information and communications technology that gained growth and major transformation by building a broader IES. Only a high demand from the government for creating a strong IES can change the situation.

Evaluation of the ESFR End of Equilibrium Cycle State: Spatial Distributions of Reactivity Coefficients

Abstract The Horizon 2020 European Sodium-cooled Fast Reactor Safety Measures Assessment and Research Tools (ESFR-SMART) project investigates the behavior of the commercial-size ESFR throughout its lifetime. This paper reports work focused on the end of equilibrium cycle (EOEC) loading of the ESFR, including neutronic analysis, core- and zone-wise reactivity coefficients, and more detailed local mapping of important safety-relevant parameters. Sensitivity and uncertainty analysis on these parameters have also been performed, and a detailed investigation into decay heat mapping was carried out. Due to the scope of this work, the results have been split into three papers. The nominal operating conditions and both zone-wise and local mapping of reactivity coefficients are considered in this paper. The work was performed across four institutions using both continuous-energy Monte Carlo (MC) and deterministic reactor physics codes. A good agreement is observed between the methods, verifying the suitability of these codes for simulation of large, complicated reactor configurations and giving confidence in the results for the most limiting ESFR EOEC core state for safety analysis. The results from this work will serve as the basis for the transient calculations planned for the next stage of work on the ESFR, allowing for more in-depth studies to be performed on the multiphysics behavior of the reactor.

Vibration suppression of bridges under moving loads using the structure-immittance approach

This paper presents the possibility of suppressing the train-induced vibration on bridges using a linear passive vibration suppression device incorporating inerter. The inerter is a two-terminal mechanical element with the property that the applied force is proportional to the relative acceleration across its terminals. The inerter has been applied to various engineering structures where performance benefits have been identified. However, currently these studies are either limited to simple network configurations with moderate performance improvement, or resulted in complicated configurations with a large number of elements which are impractical for real-life applications. In addition, the potential of using inerter-based absorbers for suppressing the train-induced bridge vibrations has not been taken into consideration. In this paper, a simplified bridge model equipped with a vibration suppression device subjected to series of moving forces is presented. The structure-immittance approach, which can cover all networks with pre-determined numbers of each element type, is adopted for the identification of the optimal absorber configurations. Numerical studies for two bridges, the THSR and the Kum-gang, under three types of railway excitations, the French T.G.V., the German I.C.E. and the Japanese S.K.S. are conducted. It is demonstrated that the overall performance of the bridge can be improved by using the proposed inerter-based configuration. It is also checked that the absorber stroke is much smaller than the inner space of bridge box girder, indicating the practical installation of the absorber. Furthermore, the robustness of the proposed absorber is verified by sensitivity analysis subjected to the change of bridge parameters and the device component values.

A novel high-resolution monophenolase/diphenolase/radical scavenging profiling for the rapid screening of natural whitening candidates from Peaonia lactiflora root and their mechanism study with molecular docking

Ethnopharmacological relevanceThe root of Paeonia lactiflora is a traditionally-used whitening medicine in China for thousands of years. Although some tyrosinase inhibitors and/or antioxidants such as 1,2,3,4,6-pentagalloylglucose, gallic acid, have been isolated and identified, their tyrosinase inhibition pathway (monophenolase or diphenolase inhibition, or both two) have not been systematically studied and the underlying tyrosinase inhibition mechanism has not been revealed yet. Moreover, the exploring of new natural tyrosinase inhibitors and antioxidants is urgently needed. Aim of the studyThis review aimed to develop a new microplate-based high-resolution tyrosinase inhibition profiling assay and establish a furthermore triple high-resolution monophenolase/diphenolase/radical scavenging profiling for accelerating identification bioactive compounds from complicated plant extract. Materials and methodsThe targeted isolation and structure elucidation were performed with high-performance liquid chromatography-high-resolution mass spectrometry and preparative high-performance liquid chromatography. It allows to be a proof of concept with the root of Paeonia lactiflora crude extract as a natural whitening herbal drug. ResultsThe result showed that galloylpaeoniflorin specifically inhibited monophenolase activity. While 1,2,3,4,6-pentagalloylglucose, gallic acid and catechin demonstrated the inhibition towards both monophenolase and diphenolase. Among them, 1,2,3,4,6-pentagalloylglucose can inhibit monophenolase activity was reported for the first time. In addition, antioxidant properties were attributed to catechin, 1,2,3,4,6-pentagalloylglucose and gallic acid. Due to its low content and complicated configuration in the root of Paeonia lactiflora, a new potential tyrosinase inhibitor and radical scavenger which tentatively identified as hexagalloylglucose by high-resolution MS was still need further verification. What's more, the molecular docking unveiled that bioactive enzymatic inhibitors mainly interacted with amino acid catalytic residues of tyrosinase via H-bonds and van der wals, which may be helpful to understand their inhibition mechanisms with tyrosinase in the skin whitening. ConclusionsThe platform provided a promising and efficient strategy for the rapid screening of whitening active components from natural sources.

A Rapid Beam Pointing Determination and Beam-Pointing Error Analysis Method for a Geostationary Orbiting Microwave Radiometer Antenna in Consideration of Antenna Thermal Distortions.

When observing the Earth’s radiation signal with a geostationary orbiting (GEO) mechanically scanned microwave radiometer, it is necessary to correct the antenna beam pointing (ABP) in real time for the deviation caused by thermal distortions of antenna reflectors with the help of the on-board Image Navigation and Registration (INR) system during scanning of the Earth. The traditional ABP determination and beam-pointing error (BPE) analysis method is based on the electromechanical coupling principle, which usurps time and computing resources and thus cannot meet the requirement for frequent real-time on-board INR operations needed by the GEO microwave radiometer. For this reason, matrix optics (MO), which is widely used in characterizing the optical path of the visible/infrared sensor, is extended to this study so that it can be applied to model the equivalent optical path of the microwave antenna with a much more complicated configuration. Based on the extended MO method, the ideal ABP determination model and the model for determining the actual ABP affected by reflector thermal distortions are deduced for China’s future GEO radiometer, and an MO-based BPE computing method, which establishes a direct connection between the reflector thermal distortion errors (TDEs) and the thermally induced BPE, is defined. To verify the overall performance of the extended MO method for rapid ABP determination, the outputs from the ideal ABP determination model were compared to calculations from GRASP 10.3 software. The experimental results show that the MO-based ABP determination model can achieve the same results as GRASP software with a significant advantage in computational efficiency (e.g., at the lowest frequency band of 54 GHz, our MO-based model yielded a 4,730,000 times faster computation time than the GRASP software). After validating the correctness of the extended MO method, the impacts of the reflector TDEs on the BPE were quantified on a case-by-case basis with the help of the defined BPE computing method, and those TDEs that had a significant impact on the BPE were therefore identified. The methods and results presented in this study are expected to set the basis for the further development of on-board INR systems to be used in China’s future GEO microwave radiometer and benefit the ABP determination and BEP analysis of other antenna configurations to a certain extent.

100% saturated liquid hydrogen production: Mixed-refrigerant cascaded process with two-stage ortho-to-para hydrogen conversion

To reduce CO2 emissions and address climate change concerns, most futuristic studies investigating 100% renewable energy sources and subsequent power-to-gas/fuel/liquid/X technological developments have been based on hydrogen (H2). The long-term storage and transportation of H2 over long distances restrict its feasibility as an energy vector, mainly due to its low energy density. Liquefaction is a promising approach for overcoming these issues. However, it requires a large amount of energy, and if H2 itself is used to provide this energy, then 25% to 35% of the initial quantity of H2 is consumed. The existing H2 liquefaction plants have specific energy consumption values in the range of 10–12 kWh/kgLH2 and exergy efficiencies in the range of 20%–30% with complicated configurations. Therefore, a thermodynamically efficient and compact design is required to facilitate a roadmap to H2 economy. This paper proposes a simple, energy-efficient, and cost-effective process for H2 liquefaction. Three refrigeration cycles with optimal mixed-refrigerant compositions are used, which makes the proposed process energy-efficient. Additionally, two-stage ortho-to-para conversion makes the process compact. The proposed process is unique in terms of its configuration and mixed-refrigerant combination. The modified coordinate descent approach was adopted to identify the optimal design variables for the proposed H2 liquefaction process. The proposed process consumes an energy of 6.45 kWh/kgLH2, which is 36.5% and 16.1% lower than that consumed by the base design of the proposed process and a published base case, respectively. Additionally, the exergy efficiency of the proposed process is 47.2%. This study will help process engineers achieve a sustainable green economy by improving the competitiveness of H2 storage and transportation over long distances.

Unleashing the Sounds of Silence: Hong Kong’s Story in Troubled Times

Hong Kong’s story is difficult to tell, commented Leung Ping-kwan (1949–2013) in consideration of the city’s complicated historical configuration as well as of the aesthetic reflection on the same by the writers and artists that have come to shape and promote the colonial city’s unique culture. Confronting the post-handover government’s suppression of democratic decision-making with massive street protests, the next generation of cultural producers continues to critically interrogate, contest, and subvert the official genealogy and nationalist master narrative. In response to the various factors contributing to the ongoing silencing of the city’s critical voices, many artists, directors, and writers have turned to (absent) sound as the aesthetic signifier of the sociopolitical turn from hope and reconciliation to despair. Their performative silence simultaneously protests and mourns the denunciation, suppression, and erasure of oppositional groups. In this paper, I apply a methodological cluster comprising concepts from ecocriticism, microhistorical-discourse analysis, social anthropology, and other disciplinary fields to address the ramifications of Hong Kong’s story as inscribed within protest-related literary, visual and multimedia art productions. Street art performance, handover-themed art exhibitions, Wong King Fai’s video “Umbrella Dance for Hong Kong,” and Samson Young’s sonic multimedia installations appositely illustrate the conundrum addressed.

Scattered Far-Field Sampling in Multi-Static Multi-Frequency Configuration.

This paper deals with an inverse scattering problem under a linearized scattering model for a multi-static/multi-frequency configuration. The focus is on the determination of a sampling strategy that allows the reduction of the number of measurement points and frequencies and at the same time keeping the same achievable performance in the reconstructions as for full data acquisition. For the sake of simplicity, a 2D scalar geometry is addressed, and the scattered far-field data are collected. The relevant scattering operator exhibits a singular value spectrum that abruptly decays (i.e., a step-like behavior) beyond a certain index, which identifies the so-called number of degrees of freedom (NDF) of the problem. Accordingly, the sampling strategy is derived by looking for a discrete finite set of data points for which the arising semi-discrete scattering operator approximation can reproduce the most significant part of the singular spectrum, i.e., the singular values preceding the abrupt decay. To this end, the observation variables are suitably transformed so that Fourier-based arguments can be used. The arising sampling grid returns several data that is close to the NDF. Unfortunately, the resulting data points (in the angle-frequency domain) leading to a complicated measurement configuration which requires collecting the data at different spatial positions for each different frequency. To simplify the measurement configuration, a suboptimal sampling strategy is then proposed which, by an iterative procedure, enforces the sampling points to belong to a rectangular grid in the angle-frequency domain. As a result of this procedure, the overall data points (i.e., the couples angle-frequency) actually increase but the number of different angles and frequencies reduce and lead to a measurement configuration that is more practical to implement. A few numerical examples are included to check the proposed sampling scheme.

Angular vortex phase diagram in YBa2Cu3O7 films with c-axis correlated pinning centers

High temperature superconductors (HTSCs) exhibit rich vortex phases under the influence of nanoscale pinning centers, and complicated configurations and behavior of vortices are realized by anisotropic vortex pinning, vortex interaction, and line tension. To understand the behavior and configurations of vortices, YBa2Cu3O7 films containing self-organized nanorods (BaSnO3, BaZrO3, BaHfO3) were prepared, and the critical current density and the resistivity were measured for varying angles between the nanorods (//c-axis) and the magnetic field (θ) in the temperatures of 65–90 K. The trapping angle of the strong nanorod (θ ts) determines the vortex phase boundary in the magnetic field lower than the matching field (B< B ϕ). While the large c-axis J c peak and the resistivity dip are observed for θ< θ ts due to the vortex accommodation on the nanorods, the vortices for θ> θ ts are pinned by the matrix uncorrelated defects and/or the ab-plane pinning centers. In the magnetic field higher than B ϕ(B> B ϕ), the weak matrix c-axis correlated defects such as twin boundaries accommodate vortices at the angles smaller than the trapping angle of the matrix c-axis correlated defect. Although the matrix c-axis correlated defects do not pin the matrix-vortices for the larger angles, the matrix-vortices are pinned by the vacant nanorod portions that appear due to the magnetic field tilt. This vortex retrapping results in the off-axis J c peak and the off-axis resistivity dip. Thus, the weak pinning by matrix defects, the cage potential, and the vortex retrapping as well as the strong nanorod pinning determine the angular vortex phase of the HTSCs containing c-axis correlated pinning centers.

Identification of Lensed Gravitational Waves with Deep Learning

Abstract Similar to light, gravitational waves (GWs) can be lensed. Such lensing phenomena can magnify the waves, create multiple images observable as repeated events, and superpose several waveforms together, inducing potentially discernible patterns on the waves. In particular, when the lens is small, ≲105 M ⊙, it can produce lensed images with time delays shorter than the typical gravitational-wave signal length that conspire together to form “beating patterns.” We present a proof-of-principle study utilizing deep learning for identification of such a lensing signature. We bring the excellence of state-of-the-art deep learning models at recognizing foreground objects from background noise to identifying lensed GWs from noisy spectrograms. We assume the lens mass is around 103–105 M ⊙, which can produce time delays of the order of milliseconds between two images of lensed GWs. We discuss the feasibility of distinguishing lensed GWs from unlensed ones and estimating physical and lensing parameters. The suggested method may be of interest to the study of more complicated lensing configurations for which we do not have accurate waveform templates.

Need Analysis: Portable Web Server Development Kits for Teaching and Learning

A Portable server is the combination of popular web server software, namely Apache, MySQL, PHP and PhpMyAdmin. With a portable server, users can develop and display a developed website anywhere at any time as all web server configurations have been installed on the storage drive. Portable servers are ideal for displaying the offline version of the website anywhere when developing a website. Using a mobile server as well, users do not need hosting that requires complicated configuration and can be used to run tests before putting the website online. This study aims to obtain preliminary findings on building portable web server development kits for the teaching and learning process.

Nitrogen and Phosphate Co‐doped Graphene as Efficient Bifunctional Electrocatalysts by Precursor Modulation Strategy for Oxygen Reduction and Evolution Reactions

AbstractHeteroatoms doped carbon‐based metal‐free catalysts are important candidates as alternatives for precious group metal (PGM) catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) – two of the most important reactions in electrochemical energy conversion and storage areas. Despite the significant efforts in developing heteroatoms doped metal‐free electrocatalysts with enhanced electrocatalytic activity, few studies focus on their bifunctional activities for ORR and OER due to the unclear catalytic mechanism and complicated active sites configurations. Herein, a series of nitrogen and phosphate co‐doped carbon‐based catalysts (NP/C) are successfully synthesized via a precursor modulation strategy. In this method, 5‐aminouracil, 2, 6‐diaminopyridine and 1, 3‐diaminobenzene are selected to modulate pyridinic N (NP), graphitic N (NG) and pyrrolic N (NPY) sites, respectively, while phytic acid is used as P sites. The results demonstrate that the N and P co‐doped graphene with NP+NG+P configuration shows increased ORR performance, and on the other hand, the NP+NPY+P configuration enhances OER. Density functional theory (DFT) calculation demonstrates that different NP configurations formed by precursor modulation induce different electronic structure on surrounding carbon atoms, providing a possibility to manipulate intermediates energy in reaction pathway for ORR and OER. This study sheds new light on revealing the intrinsic correlation between active site configurations and catalytic bifunctional activity and selectivity of graphene based electrocatalysts for oxygen redox reactions.

Modelling of sensitivity of underground space stability to the in situ stress uncertainties: case study at the Bukov underground research facility phase II (Rozna mine, Czechia)

Numerical modelling has been widely used in the underground excavation design, where the in situ stress state plays a crucial role in the stability analysis. However, determination of an exact stress state for a specific geological region remains uncertain due to the complicated tectonic nature and measurement limitations. The stability is thus better analysed by considering the in situ stress as a finite spectrum and pinpointing the possible worst-case scenario. The most probable scenarios of in situ stress states in the Rožná mine area were analysed based on the varying trends in principal stress ratio and mean stress values obtained from four different measurement/analysis campaigns. The influence of different in situ stress judgement on the deformation and failure characteristics of the Bukov Underground Research Facility (URF) (Phase II, Czech) were investigated by the finite volume program FLAC3D. Results show that the increased horizontal stress anisotropy and the mean stress level jointly increase the overall deformation and lower the URF stability. Such influences on the roadway horizontal convergence are more considerable than the vertical ones. A mathematical model considering mean stress and horizontal stress ratio was proposed to quantitatively describe the overall stability, especially useful for excavations possessing complicated configuration.

Area waves on a slender vortex revisited

This paper considers the classic problem of the dynamics of axisymmetric waves on a rectilinear vortex, in the absence of viscosity. The waves alter the axial pressure distribution and thus generate axial flows which depend on the radial distribution of vorticity. To simplify this problem, models have been introduced which average over the cross-section and eliminate the radial dependence. One approach, pioneered by Lundgren and Ashurst (1989 J. Fluid Mech. 200 283–307), averages the momentum equation. Another averaging method, due to Leonard (1994 Phys. Fluids 6 765–77), focuses on the vorticity equation. The present paper takes a fresh look at the derivation of these two distinct models, which we refer to as the momentum wave model and vorticity wave model respectively, using the tools of differential geometry to develop a hybrid Eulerian–Lagrangian approach. We compare these models with area waves in the asymptotic limit of a slender vortex, with radial structure retained. Numerical calculations are presented to show the differences between waves in the full slender vortex system and those in the momentum and vorticity wave models. We also discuss modification of the vorticity wave model to allow an external irrotational flow, and simulations are presented where a vortex is subjected to uniform axial stretching. Our approach can also be developed to model more complicated configurations, such as occur during vortex collisions.

Strongly coupled partitioned iterative method for the structure–piezoelectric–circuit interaction using hierarchical decomposition

The key to the design of advanced micro electro–mechanical devices is an accurate evaluation of the circuit-integrated piezoelectric oscillator that accounts for its complicated configuration. Here, the direct numerical modeling of this oscillator leads to a general formulation as a structure–piezoelectric–circuit interaction. Hence, this study developed a strongly coupled partitioned iterative method for the structure–piezoelectric–circuit interaction. The proposed method was constructed using hierarchical decomposition, the partitioned iterative method for two coupled fields, and loop union. That is, the whole system of the coupled multiphysics is hierarchically decomposed into coupled two-field subsystems, partitioned iterative algorithms for two coupled fields are applied to these subsystems, and the coupling algorithms for these subsystems are reduced to a single coupling algorithm. In the proposed method, three distinct direct piezoelectric, inverse piezoelectric, and circuit solvers are strongly coupled with each other. The inverse piezoelectric solver uses shell finite elements to analyze the response of the thin oscillator efficiently, while the direct piezoelectric solver uses solid finite elements to accurately describe the three-dimensional distribution of the electric potential in the piezoelectric continuum. The proposed method can accurately analyze coupling phenomena in the RC circuit, piezoelectric shunt damping, and piezoelectric energy harvesting.

Fatigue assessment of a full-scale composite box-girder with corrugated-steel-webs and concrete-filled-tubular flange

Performance and aesthetic considerations push the bridge industry towards new structural solutions. A new type of composite box girder with corrugated steel webs was proposed, which utilizes concrete-filled wide-flat steel tube replacing concrete slab as bottom flange. This new design may still be susceptible to fatigue due to its complicated configuration and inevitable repeated heavy traffic loads. Therefore, this research presented a full-scale fatigue test and numerical study of this new composite girder through four-point bending. The test results demonstrated that even under a rather low stress level, the composite girder still sustains fatigue damage under a very high cycles of 9.84 million, which leads to failure as multi cracks have initiated and propagated at top and bottom surface of steel tube around mid-span location. Assessed by the structural stress approach fully relying on finite element analysis (FEA) results and modified version combining FEA results with measurement data, the cumulative damages for all fatigue-sensitive details of test girder are respectively lower and higher than the failure standard 1.0. This indicates that the modified method is in consistent with experimental results, while the original one is not. Accordingly, it is advisable to combine FEA results with measurement data to evaluate fatigue-sensitive details of this composite girder.

Superamphiphilic TiO2 Composite Surface for Protein Antifouling.

Unwanted protein adsorption deteriorates fouling processes and reduces analytical device performance. Wettability plays an important role in protein adsorption by affecting interactions between proteins and surfaces. However, the principles of protein adsorption are not completely understood, and surface coatings that exhibit resistance to protein adsorption and long-term stability still need to be developed. Here, a nanostructured superamphiphilic TiO2 composite (TiO2 /SiO2 ) coating that can effectively prevent nonspecific protein adsorption on water/solid interfaces is reported. The confined water on the superamphiphilic surface enables a low adhesion force and the formation of an energy barrier that plays a key role in preventing protein adsorption. This adaptive design protects the capillary wall from fouling in a harsh environment during the bioanalysis of capillary electrophoresis and is further extended to applications in multifunctional microfluidics for liquid transportation. This facile approach is not only perfectly applied in channels with complicated configurations but may also offer significant insights into the design of advanced superwetting materials to control biomolecule adhesion in biomedical devices, microfluidics, and biological assays.

Short-Term Scheduling Model of Cluster Tool in Wafer Fabrication

Since last decade, the cluster tool has been mainstream in modern semiconductor manufacturing factories. In general, the cluster tool occupies 60% to 70% of production machines for advanced technology factories. The most characteristic feature of this kind of equipment is to integrate the relevant processes into one single machine to reduce wafer transportation time and prevent wafer contaminations as well. Nevertheless, cluster tools also increase the difficulty of production planning significantly, particularly for shop floor control due to complicated machine configurations. The main objective of this study is to propose a short-term scheduling model. The noteworthy goal of scheduling is to maximize the throughput within time constraints. There are two modules included in this scheduling model—arrival time estimation and short-term scheduling. The concept of the dynamic cycle time of the product’s step is applied to estimate the arrival time of the work in process (WIP) in front of machine. Furthermore, in order to avoid violating the time constraint of the WIP, an algorithm to calculate the latest time of the WIP to process on the machine is developed. Based on the latest process time of the WIP and the combination efficiency table, the production schedule of the cluster tools can be re-arranged to fulfill the production goal. The scheduling process will be renewed every three hours to make sure of the effectiveness and good performance of the schedule.

On the compound sessile drops: configuration boundaries and transitions

Abstract