bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of a Test Article for Acoustic Streaming in High-Speed Flow
Authors: Rahbari Iman , Butzen Michael , Twaddle James , Paniagua Guillermo
Published: October 2022

Acoustic streaming can provide a viable, lightweight solution to improve the heat exchangers’ capacity with a reduced drag penalty. The present work aims to develop a test article to experimentally create large-amplitude acoustic pulsations at high frequencies required for generating acoustic streaming and characterize its impact on the unsteady heat flux and shear stress within a narrow channel. Our combined computational and experimental approach iteratively produced multiple test sections. Instead of experimental testing, the CFD calculations to assess each design iteration reduce the effective geometry cost. the flow topology was assessed via CFD calculations. The final test model consists of two long hollow plates placed parallel creating a narrow channel within a larger flow area. As a result, three flow paths are created within the wind tunnel’s test section and the area ratio between the main and the bypass flow controls the Mach number within the narrow channel. The acoustic waves drive acoustic streaming and are generated by a shallow open cavity, which produces pressure oscillations with the dominant frequency of ∼8 kHz in a Mach 0.8 flow. Pressure taps and K type thermocouples monitor the pressure and temperature distributions over the walls while the total pressure and temperature are measured upstream of the plates. Kulite miniature pressure transducers measure the pressure fluctuations at high frequencies near the open cavity. Optical shear stress sensors are selected to monitor the unsteady wall shear stress immediately downstream of the open cavity. A thin film sensor array is designed for high-frequency wall temperature measurements which serve as the boundary condition for inverse heat flux calculations. High-speed Schlieren imaging is taken to visualize the flow structures near the cavity region. The experiments performed at the Purdue Experimental Turbine Aerothermal Lab indicate that the designed test article successfully reaches Mach 0.8. The open cavity creates the high-amplitude pressure pulsations at the frequency of ∼8 kHz. The successful commissioning sets the stage for future experiments to determine the potential of acoustic streaming as a low weight modification to improve compact heat exchangers.
A Microscale-Based Methodology to Predict the Performance Degradation in Turbomachinery due to Particle Deposition
Authors: Friso Riccardo , Zanini Nicola , Suman Alessio , Casari Nicola , Pinelli Michele
Published: October 2022

Solid particle ingestion is one of the main causes of gas turbine compressors degradation for both heavy-duty and aero-propulsion applications. Particles that enter the engine can stick to the internal surfaces and then form deposits. These, in turn, involve a change in the surface roughness and then performance deterioration. In the literature, several strategies have been proposed in order to account for the deposits effects on compressor numerical simulations. Among the others, the most used is the mesh-morphing strategy, which consists of the modification of the computational grid according to the particle deposition. Even though it is well suited for turbine fouling, the large computational costs and complexity of this strategy are not acceptable for compressor simulations. In this work, an innovative microscale-based approach has been proposed. An axial compressor deposition experiment from the literature has been considered as the reference case to test the reliability of the presented strategy. The main advantage of this approach consists of reducing both computational costs and numerical instability since it does not need the modification of the mesh. The deposition has been modelled by means of the OSU model and the roughness influence on the fluid flow has been accounted for by using the well-known sand-grain-roughness height (ks). Efforts have been made to find the ks correlation that best represents a fouled surface. The presented strategy enables the prediction of the fouling effects on axial flow compressors, and the prediction of the performance losses during the operation.
An Innovative Measurement Technique for the Direct Evaluation of the Isentropic Efficiency of Turbocharger Turbines
Authors: Marelli Silvia , Usai Vittorio , Cordalonga Carla , Capobianco Massimo
Published: October 2022

Turbocharging plays a key role not only in improving automotive engine performance, but also in reducing fuel consumption and exhaust emissions for Spark Ignition and diesel engines. In depth experimental investigations on turbochargers are therefore necessary to better understand their performance. The availability of experimental information on realistic turbine steady flow performance is an essential requirement for optimizing engine-turbocharger matching calculations developed in simulation models. This is most evident with regards to the turbine efficiency, as its swallowing capacity can be accurately assessed by measuring the mass flow, inlet temperature and pressure ratio across the machine. In fact, in the case of a turbocharger radial flow turbine, the isentropic efficiency evaluated directly starting from the measurement of the thermodynamic parameters at the inlet and outlet sections can give significant errors. This inaccuracy is mainly related to the difficulty of a correct evaluation of the turbine outlet temperature due to the flow field and the temperature distribution at the machine outlet.

The purpose of this work is to obtain a reliable measurement of the turbine outlet temperature thanks to a specific device installed before the standard measurement section to dissipate the flow structures dominated by vorticity, thus obtaining a uniform distribution of the flow fields and of temperature to the measurement section. This measurement allows to optimize turbocharger experimental performance implemented in simulation models, obtaining a better control of the after-treatment device generally adopted downstream of the turbine. To this aim, a non-intrusive 3-hole probe was adopted to perform measurement of the flow field, pressure, and temperature downstream the turbine. The main results obtained through the non-standard measurements are compared with those achieved through a direct measurement of turbine outlet temperature by three probes inserted in pipe with a different protrusion. The experimental campaign concerns investigations also developed in almost adiabatic conditions and to be adopted to carry out a realistic measurement of the turbine outlet temperature in a simpler and less time-consuming way.
Gas Turbine Combined Cycle Range Enhancer - Part 2: Performance Demonstration
Authors: Reboli Tommaso , Ferrando Marco , Gini Lorenzo , Mantelli Luca , Sorce Alessandro , Traverso Alberto
Published: October 2022

In the current energy scenario, gas turbine combined cycles (GTCCs) are considered key drivers for the transition towards fossil-free energy production. However, to meet this goal, they must be able to cope with rapid changes of power request, and to extend their operating range beyond the limits imposed by the environmental conditions in which they operate.

The European H2020 project PUMPHEAT [1] aims at achieving this goal thanks to the integration of the GTCC with a heat pump (HP) and a thermal energy storage (TES). Both HP and TES are used to condition the air flow at the gas turbine compressor inlet, thus modifying the whole GTCC power output and extending its operative range. To study this setup, a dedicated cyber-physical facility was built at the University of Genova laboratories, Italy.

The plant includes physical hardware, such as a 100kWel micro gas turbine, (mGT), a 10 kWel HP and a 180 kWh change phase material-based TES. These real devices are up-scaled thanks to performance maps and real-time dynamic models to emulate a full-scale heavy duty 400 MW GTCC with a cyber-physical approach. The three real key components (mGT, HP and TES) are run in the laboratory. Data collected by various sensors is monitored in real-time and used to feed both the simulated GTCC bottoming cycle model and the four-level control system. The control system determines the optimal configuration of the whole plant and the operative point of the real devices to minimize the mismatch with a real electric power demand curve.

With the aim of analyzing the performance of the facility and to assess the potential of the proposed GTCC range enhancer, different operative configurations are tested: one for reducing the power production of the plant below the minimum environmental load (MEL) and two for augmenting the plant maximum power at certain ambient conditions.

From the analysis of these tests it is possible to verify the effectiveness of the proposed concept and to characterize the transient behavior of the real components.
Evaluation of Surge Prediction Capabilities of Body-Force Model on a High-Speed Multi-Stage Axial-Radial Compressor
Authors: Zeng Hanxuan , Fan Tengbo , Sun Zhenzhong , Wang Baotong , Zheng Xinqian
Published: October 2022

Multi-stage axial-radial compressors are typical configurations of compression systems used in turboshaft engines. The aerodynamic instabilities encountered in this type of compressor are commonly identified as surge, which seriously threaten the operability and reliability of the compressor itself and even the entire engine. Therefore, correct prediction of surge characteristics and the aerodynamic loading are crucial during the design process. However, due to the complexity of compressor surge, high-fidelity numerical methods, like unsteady Reynolds-averaged Navier-Stokes (URANS) simulation, require enormous computational resources and time costs, which can barely be used in design iterations. Therefore, finding a more efficient way for surge prediction is essential.

This paper describes a general method of surge prediction based on an in-house code of body-force model. A high-speed multi-stage axial-radial compressor is used to evaluate the capabilities of this method to predict surge characteristics against URANS. The run-time is reduced by approximately 2 orders of magnitude. Key features of surge (i.e., flow reversal, flow resumption, and repressurization) and the aerodynamic loading during surge are compared. Overall, the results from the two method show a close matching. Additional analyses are also made on the fidelity limitations of this method in the prediction of finer surge features, and the corresponding modifications are proposed.
Exploiting GPU-Based HPC Architectures to Accelerate an Unsteady CFD Solver for Turbomachinery Applications
Authors: Poli Francesco , Marconcini Michele , Pacciani Roberto , Magarielli Donato , Spano Ennio , Arnone Andrea
Published: October 2022

Aircraft engine designers are nowadays facing more and more challenges: they strive to reduce fuel consumption, obtain better engine performance, and create quieter, safer, and environmentally friendlier products. One of the key factors to achieve these goals is the availability of numerical simulation tools able to accurately predict engine behavior and of hardware/software platforms where the tools can successfully run.

However, accurate numerical simulations, particularly unsteady Computational Fluid Dynamics (CFD) ones based on sophisticated solvers, are time-consuming and demanding in terms of hardware resources. This may limit the industrial applicability of these methods.

A possible strategy to overcome this problem is the acceleration of numerical solvers on advanced High Performance Computing (HPC) architectures, in order to reduce the execution time down to values compatible with industrial needs.

Traf is a CFD solver for steady/unsteady three-dimensional Reynolds-averaged Navier-Stokes equations. It is developed at the University of Florence, with a special focus on turbomachinery applications. The current production release is a parallel code that runs on CPU-based platforms.

A new version of Traf has been ported to and optimized for GPU-based HPC architectures, in order to dramatically accelerate CFD analyses. The code has been tested on an industrial-grade use case concerning a low-pressure turbine module for aeronautical applications in the context of the EU H2020 funded project LEXIS (Large-Scale Execution for Industry & Society, GA 825532), comparing its performance with the CPU-based release and obtaining promising results. To this aim, the speedup weighted to account for the different hardware cost is selected as a meaningful Key Performance Indicator (KPI).
Impact of Epistemic Uncertainty on Performance Parameters of Compressor Blades
Authors: Prots Andriy , Schlüter Lukas , Voigt Matthias , Mailach Ronald , Meyer Marcus
Published: October 2022

An well-established tool for probabilistic analysis is the Monte Carlo simulation (MCS), which can be used to gain insight into an unknown system behavior. The variability of the input variables is usually defined by parametric probability density functions (PDFs) or parametric cumulative density functions (CDFs). An example is the Gaussian normal distribution, which is characterized by its mean and standard deviation. When analyzing compressor blades, e.g. in the context of robust design optimization, the variation of profile variables such as chord length or stagger angle may be of interest. The distribution parameters are oftentimes obtained from a limited set of optical measurements. When performing the MCS, the distribution parameters must be fixed. However, the use of fixed parameters neglects the uncertainty and the effects resulting from the uncertain distribution parameters.

In this paper, the influence of epistemic uncertainty is illustrated using the example of compressor blades, which are subject to both manufacturing variability as well as wear and tear. Only a limited set of optical measurements is available. The resulting effect of the epistemic uncertainty is quantified using parametric probability boxes. The results of this approach are compared with the result from classical confidence interval analysis. This allows an estimation of the required number of measurements to achieve the desired statistical confidence.
Design Procedure of a Rotating Cavity Rig for Hot Gas Ingestion Investigation
Authors: Orsini Lorenzo , Picchi Alessio , Bonini Alessio , Innocenti Luca , Di Benedetto Daniele , Da Soghe Riccardo , Mazzei Lorenzo
Published: October 2022

This paper presents the design procedure and the setup of a Rotating Cavity Rig to investigate the problem of the high-pressure turbine main annulus flow ingestion into wheel-spaces. The single-stage test rig has been developed to run at cold flow conditions and it consists of a stationary and a rotating disk housing interchangeable cover plates to mimic different seal geometries. Thanks to such interchangeable covers, the rim seal configuration can be easily modified to investigate different arrangements and to perform optimization studies. Although some geometry simplifications are inevitable in scaled down models, such covers have been modelled as to represent a real engine rim seal as close as possible. Beside the standard pressure and CO2 concentration measurements inside the cavity, the rig implements optical accesses to exploit measurement techniques based on Pressure Sensitive Paints (PSP). Optical approaches will then be used to explore the rim sealing effectiveness on both stator and rotor disk under real engine representative operating conditions. CFD and FEM analyses run to support the rig design choices and to define its operating limits are hence highlighted and properly explained.
Numerical Study of Methane Pyrolysis Inside a Single-Channel Shock Wave Reformer
Authors: Mahmoodi-Jezeh S. V. , Tüchler Stefan , Madiot Ghislain , Davidson Mark , Akbari Pejman , Copeland Colin D.
Published: October 2022

The paper describes a numerical investigation of the thermal decomposition of methane to hydrogen and carbon within a single-channel, four-port wave rotor using a three-dimensional (3-D), Reynolds-averaged Navier-Stokes (RANS) CFD model. This work is in support of the New Wave Hydrogen, Inc. (NWH2) proprietary technology development. A Menter’s k-ω SST turbulence is used for the closure of the mean momentum equations and is coupled to multispecies transport equations with a one-step finite-rate chemistry model. The kinetic model is validated based on a set of measurement data of a double-diaphragm shock tube case. To further examine the predictive accuracy of the numerical approach, the results of the 3-D single-channel wave rotor are compared with those of quasi-one-dimensional unsteady model that has been previously reported extensively in literature. It is observed that when the wave rotor channel is exposed to the high-pressure driven gas (HPDRV N) port, a secondary right-running shock wave is generated, which greatly energizes the flow around the HPDRV N port, resulting in large magnitudes of pressure and temperature; and consequently, the cracking of methane into hydrogen and carbon. The comparison between 1-D and 3-D simulation results indicate that the LPDRV N gas penetration is around 75% of the channel width in the case of 1-D, but is below 50% in the 3-D case. Furthermore, the conversion rate of methane in the 3-D case is one order of magnitude smaller than that in the 1-D case.
Local Heat/Mass Transfer Measurements in a Shrouded Rotor-Stator Cavity
Authors: Choi Seungyeong , Lee Hee Jae , Heo Jeonghun , Park Hee Seung , Moon Hee-Koo , Cho Hyung Hee
Published: October 2022

Local heat/mass transfer and flow characteristics data applicable to the cooling design of the wheel space with rim seal in the gas turbine engine are essential. Experimental facility was designed to obtain local heat/mass transfer coefficients on stator and rotor surface in rotor-stator cavity with hub injection flows using the naphthalene sublimation method. This study investigated three configurations of rotor-stator cavity; unshrouded, shroud on rotor, and shroud on stator. The experiments were conducted for various rotational Reynolds numbers (ReΦ = 0, 5.6 × 105, 1.12 × 106), gap ratios (G = 0.03, 0.0375, 0.05) and non-dimensional flow rates (Cw = 7.0 × 103, 14.0 × 103). The local Sherwood numbers appeared similar in the circumferential direction, so the radial Sherwood numbers were analyzed. At low radius (r/b < 0.4), the heat/mass transfer is dominated by the hub injection flow, and the Sherwood number on rotor and stator surfaces are similar due to small gap ratio (G < 0.05). At large radius (r/b > 0.5), the Sherwood number on rotor increase as rotational Reynolds number increases, however the Sherwood number on stator is independent. At the low opening ratio (Go = 0.17), the shroud increases the pressure in the cavity and reduces the Sherwood number regardless of the shroud installation location. Especially, at large radius, the Sherwood number on stator is reduced significantly. At the large opening ratio (Go = 0.5), there is no effect of the shroud on heat/mass transfer. And the shroud on the rotor enhances the overall Sherwood number on the rotor and stator under high injection flow conditions. Thus, the shroud clearly changes the flow and heat/mass transfer in the rotor-stator cavity at low opening ratio conditions.
Optimal Blade Design of Stator Based on Adjoint Fluid Topology Optimization Method in a Torque Converter
Authors: Tao Tianlang , Ke Zhifang , Wei Wei , Liu Cheng , Yan Qingdong
Published: October 2022

Traditional forward design method for blade of hydrodynamic torque converter is limited by empirical design so that it is difficult to produce innovative blade design results. Based on the adjoint sensitivity, an unconventional optimization blade design method, Adjoint Fluid Topology Optimization method was proposed. Based on this method, a directional topological optimization of stator blade design was carried out as an example to achieve a better torque ratio performance for torque converter under stalling condition. Such optimization method can achieve irregular stator blade with better performance. Moreover, the flow energy distribution before and after such topology optimization are further studied, the results show that the optimized torque ratio is increased by 9.99% under stalling condition when comparing with the original design result, and the irregular blade result has a more reasonable distribution of flow energy, indicating that fluid topology optimization can not only get rid of the restriction of forward blade design method and provide an innovation way for irregular blade design, but also improve the potential performance of turbomachinery.
An Evaluation of Passive Wall Treatment With Circumferential Grooves in a High-Performance Multi-Stage Axial Compressor
Authors: Bruno Díaz Rubén , Takachi Tomita Jesuíno , Bringhenti Cleverson , Tonon da Silva Daniel , Ferraz Cavalca Diogo
Published: October 2022

Passive wall treatments with circumferential grooves in axial compressors proved to be effective in increasing the compressor stall margin in previous researches by creating a resistance to the flow that leaks in the tip clearance region of the compressor, from the rotor blade pressure side to the suction side. In the present work, a passive wall treatment with circumferential grooves was implemented in a multi-stage axial compressor. Different configurations of circumferential grooves were created at the casing of the first rotor row used in a four-stage axial flow compressor. 3D CFD flow simulations were performed in order to evaluate all the specified configurations aiming to find improvements on compressor stall margin. Investigations on the compressor flow characteristics were realized and the stall margin variations were determined. The numerical simulations were performed based on the Reynolds-Averaged Navier Stokes equations and the turbulence model was the k-ω SST. After the simulations, several rotational speeds of the compressor map characteristics, including the design-point rotational speed, were obtained for the case without casing treatment (smooth wall case) and for the case with circumferential grooves. In the results, passive wall treatment with circumferential grooves demonstrated an improvement in the compressor stall margin, especially for N = 0.60 and N = 0.90 rotational speeds.
Numerical Investigation of Rich-Lean Staging in SGT-750 Scaled DLE Burner With Partially-Decomposed Ammonia
Authors: Indlekofer Thomas , Gruber Andrea , Wiseman Samuel , Nogenmyr Karl-Johan , Larfeldt Jenny
Published: October 2022

Ammonia is emerging as a very convenient hydrogen- and energy-carrier chemical that, in the context of present efforts to curb carbon emissions from the power-generation and transport sectors, can be manufactured from both green hydrogen, generated from renewable energy sources, and blue hydrogen, generated from natural gas in combination with carbon capture and storage. As opposed to hydrogen, however, the properties of ammonia make it significantly simpler to transport across long distances and store for relatively long periods of time. Early exploratory work on combustion of pure ammonia in laboratory-scale gas turbine burners was conducted at Tohoku University and AIST (Japan) and revealed that the adoption of a longitudinal rich-lean staging strategy in the operation of the device is a convenient approach to minimize NOx and N2O emissions from fuel-bound nitrogen oxidation. Moreover, very recent experimental evidence acquired at SINTEF using a laboratory-scale 4th-generation DLE burner design by Siemens Energy (SGT-750) confirms that the low-emission performance achieved with rich-lean staging also applies to combustion of partially-decomposed ammonia [ASME paper GT2021-60057]. In the present paper we report a comprehensive numerical modelling study that exploits Large Eddy Simulation (LES) in conjunction with detailed chemical kinetics and a Chemical Reactor Network (CRN) model to assess a rich-lean staging strategy applied to combustion of partially-decomposed ammonia in the Siemens Energy 4th-generation DLE burner. Data analysis performed from both numerical modelling approaches, LES and CRN, confirm that the rich-lean staging strategy tested in the present study indeed results in significantly lower emissions compared to the conventional operational profile of the burner. Furthermore, reaction pathways analysis performed on the CRN data reveals important details that characterize the different evolution of nitrogen species between the non-staged and staged operation of the burner, ultimately leading to the observed difference in NOx and N2O emissions.
Development and Evaluation of Shaped Film Cooling Holes Designed for Additive Manufacturing
Authors: Furgeson Michael T. , Veley Emma M. , Yoon Christopher , Gutierrez Daniel , Bogard David G. , Thole Karen A.
Published: October 2022

Film cooling remains a critical technology for cooling gas turbine components. In recent years, additive manufacturing (AM) has been used to develop novel film cooling hole designs which significantly increase the film cooling effectiveness. However, engine scale AM builds have imperfections and roughness that can have a noticeable effect on performance. In this study, 9-9-3 shaped film cooling holes were constructed at engine scale using metal AM, specifically direct laser metal sintering (DMLS). These “as built” geometries were characterized through computerized tomography (CT) scans to quantify deviations from holes with design intent, or “as-designed” holes. To evaluate the performance of the “as-built” holes compared to “as-designed” holes, both adiabatic and overall cooling effectiveness were measured experimentally for 5x scale models. The larger scale enabled the use of finite deposition modeling (FDM) to construct hole geometry that closely matched the “as-designed” holes and the CT scans of the “as-built” holes. Two versions of the 9-9-3 hole were studied, the 9-9-3 rounded inlet (RI) hole with rounding at the inlet, and the 9-9-3 rounded inlet and exit (RIE) hole with additional rounding at the hole inlet, and rounding at the hole exit. Results showed that the adiabatic effectiveness and overall cooling effectiveness for the “as-built” holes were similar to the performance of the “as-designed” film cooling holes for both hole geometries tested.
A Novel Yield Criterion for Nickel-Based Superalloys
Authors: Irmak Firat , Hanekom Kevin , Torkaman Alex , Gordon Ali P.
Published: October 2022

With the significant evolution of modern gas turbine engines, selection of high-temperature resistant alloys in the hot section is known to be the fundamental solution to enhance the capabilities of these engines. In general, the high-temperature components are mainly comprised of polycrystalline, directionally solidified, and single crystal superalloys. Single crystal (SX) superalloys were developed in the 1980s to achieve high fatigue resistance and substantial creep rupture strength by eliminating grain boundaries. Directional solidification methods enabled the solidification arrangement of the materials to be comprised of columnar grains which are aligned parallel to the <001> direction. These casting types have been frequently used with nickel-based superalloys (NBSAs) to develop modern gas turbine blades. In the present work, the yield behavior of generic SX and DS NBSAs is studied. By observing various SX and DS alloys, it was concluded with need for a novel criterion that can present anisotropic and tensile/compressive asymmetric yield surfaces. This novel criterion is comprised of the criterion proposed by Hill for anisotropic materials and the method developed by Drucker and Prager for alloys that have different tensile and compressive yield strengths. Additional terms to Hill’s criterion are introduced to capture the coupling effect of normal stress and shear stress when the applied loads are not in the direction of principal axes of the material coordinate system for single crystal alloys. The parameters for the criterion are obtained from simple uniaxial tension and compression experiments. Results are compared with various well-established yield criterions. Additionally, the novel criterion is utilized to capture the effective stress and strain of multi-axial loading of turbine blades under non-isothermal conditions.
Helium electron beam rf plasma for low-k surface functionalization
Authors: Voronina Ekaterina N. , Sycheva Anastasia A. , Solovykh Alexander A. , Proshina Olga V. , Rakhimova Tatyana V. , Palov Alexander A. P. , Rakhimov Alexander T.
Published: October 2022

A complex simulation approach is applied to determine optimal conditions for the functionalization of low-k materials in e-beam rf discharge generated by 1 keV electron beam in He. The possibility and mechanisms of methyl group elimination from low-k surfaces with low-energy He ions and fast He atoms are studied with ab initio dynamic density functional theory-based simulations. The effect of gas pressure, rf voltage, and rf frequencies on the ion energy and angle distribution functions is analyzed using a 1D Particle-in-Cell Monte Carlo model. The relative contribution of fast atoms in the surface functionalization is estimated. Ion fluxes on the 2D trench walls and bottom are calculated with the developed analytical approach.
Sound absorption and insulation performance of a finite cylindrical micro-perforated panel absorber
Authors: Xu He , Kong Deyi
Published: October 2022

This paper describes the theoretical prediction, simulation research, and experimental verification conducted to understand the potential of finite cylindrical micro-perforated panel absorbers (FC-MPPAs) in noise control. The simplified Rayleigh integral method is extended to predict the dissipation of sound energy in cylindrical micro-perforations with sub-millimeter aperture. The sound absorption and insulation performance of a FC-MPPA and the influence of its structural parameters on its acoustic performance were studied by model simulation and experiment, and the directional distribution of the sound field was revealed. The simulation and experimental results show that the FC-MPPA has unique acoustic characteristics different from the panel-type absorber, and its structural parameters are closely related to the acoustic-energy dissipation efficiency. Moreover, the absorption coefficient of FC-MPPA is a function of the incidence angle and frequency of the sound wave, and its acoustic properties are controlled by the coupling between the micro-perforated panel and the acoustic modes in the annular cavity domain. These studies can provide help in the design and application of FC-MPPA to achieve better noise reduction effect.
Broadband ventilated meta-barrier based on the synergy of mode superposition and consecutive Fano resonances
Authors: Tang Yifan , Liang Bin , Lin Shuyu
Published: October 2022

Sound insulation under ventilation conditions is an important issue in acoustic fields that has significant applications in various practical scenarios. The emergence of acoustic metasurfaces breaks the limitation of manipulating large-scale waves at subwavelength scales and enables a better ventilating capability, while there is still a problem that the bandwidth of previous studies is usually smaller than half an octave. Here, we design and experimentally implement a ventilated meta-barrier with subwavelength thickness capable of realizing broadband sound insulation while maintaining efficient ventilation. The underlying mechanism is the synergy of the consecutive Fano resonances and superposition of equal-strength monopolar mode of the gradient helical structure and dipolar mode of the central orifice, leading to an efficient blocking of approximately 90% of sound waves coming from various directions in the range from 1145 to 1815 Hz while preserving high-efficiency ventilation. The experiments are conducted to verify the effectiveness of the resulting device, which is in good agreement with the simulated results and theoretical predictions. Our design with functionality and flexibility opens up possibilities for the design of broadband ventilated acoustic devices and may find important application prospects in diverse fields such as noise control and architectural acoustics.
Factors Associated With Participation in Physical Leisure Activities in Taiwanese Community-Dwelling Older Adults
Authors: Chen Szu-Wei , Chippendale Tracy , Weinberg Sharon L.
Published: October 2022

This study was to identify factors at the intrapersonal, interpersonal, and community levels that relate to physical leisure participation in Taiwanese community-dwelling older adults and to examine their relative importance. We used a cross-sectional study with purposive sampling (N = 160). Physical leisure participation was quantified as the variety, frequency, and duration of participation. Data were analyzed using a series of hierarchical multiple linear regressions. The results showed that higher variety, frequency, or duration of physical leisure participation was associated with older males and with those who reported having better health, fewer depressive symptoms, and greater social support. Intrapersonal- and interpersonal-level factors play a relatively more important role in predicting physical leisure participation than factors at the community level. Understanding factors that relate to these three levels of participation has the potential to inform interventions that are tailored to individual profiles.
Chip-based laser with 1-hertz integrated linewidth
Authors: Guo Joel , McLemore Charles A. , Xiang Chao , Lee Dahyeon , Wu Lue , Jin Warren , Kelleher Megan , Jin Naijun , Mason David , Chang Lin , Feshali Avi , Paniccia Mario , Rakich Peter T. , Vahala Kerry J. , Diddams Scott A. , Quinlan Franklyn , Bowers John E.
Published: October 2022

Lasers with hertz linewidths at time scales of seconds are critical for metrology, timekeeping, and manipulation of quantum systems. Such frequency stability relies on bulk-optic lasers and reference cavities, where increased size is leveraged to reduce noise but with the trade-off of cost, hand assembly, and limited applications. Alternatively, planar waveguide–based lasers enjoy complementary metal-oxide semiconductor scalability yet are fundamentally limited from achieving hertz linewidths by stochastic noise and thermal sensitivity. In this work, we demonstrate a laser system with a 1-s linewidth of 1.1 Hz and fractional frequency instability below 10
−14
to 1 s. This low-noise performance leverages integrated lasers together with an 8-ml vacuum-gap cavity using microfabricated mirrors. All critical components are lithographically defined on planar substrates, holding potential for high-volume manufacturing. Consequently, this work provides an important advance toward compact lasers with hertz linewidths for portable optical clocks, radio frequency photonic oscillators, and related communication and navigation systems.
Atomically engineered cobaltite layers for robust ferromagnetism
Authors: Chen Shengru , Zhang Qinghua , Li Xujing , Zhao Jiali , Lin Shan , Jin Qiao , Hong Haitao , Huon Amanda , Charlton Timothy , Li Qian , Yan Wensheng , Wang Jiaou , Ge Chen , Wang Can , Wang Baotian , Fitzsimmons Michael R. , Guo Haizhong , Gu Lin , Yin Wen , Jin Kui-juan , Guo Er Jia
Published: October 2022

Emergent phenomena at heterointerfaces are directly associated with the bonding geometry of adjacent layers. Effective control of accessible parameters, such as the bond length and bonding angles, offers an elegant method to tailor competing energies of the electronic and magnetic ground states. In this study, we construct unit-thick syntactic layers of cobaltites within a strongly tilted octahedral matrix via atomically precise synthesis. The octahedral tilt patterns of adjacent layers propagate into cobaltites, leading to a continuation of octahedral tilting while maintaining substantial misfit tensile strain. These effects induce severe rumpling within an atomic plane of neighboring layers, further triggering the electronic reconstruction between the splitting orbitals. First-principles calculations reveal that the cobalt ions transit to a higher spin state level upon octahedral tilting, resulting in robust ferromagnetism in ultrathin cobaltites. This work demonstrates a design methodology for fine-tuning the lattice and spin degrees of freedom in correlated quantum heterostructures by exploiting epitaxial geometric engineering.
Quantum arbitrary waveform generator
Authors: Takase Kan , Kawasaki Akito , Jeong Byung Kyu , Kashiwazaki Takahiro , Kazama Takushi , Enbutsu Koji , Watanabe Kei , Umeki Takeshi , Miki Shigehito , Terai Hirotaka , Yabuno Masahiro , China Fumihiro , Asavanant Warit , Endo Mamoru , Yoshikawa Jun-ichi , Furusawa Akira
Published: October 2022

Controlling the temporal waveform of light is the key to a versatile light source in classical and quantum electronics. Although pulse shaping of classical light is mature and has been used in various fields, more advanced applications would be realized by a light source that generates arbitrary quantum light with arbitrary temporal waveforms. We call such a device a quantum arbitrary waveform generator (Q-AWG). The Q-AWG must be able to handle various quantum states of light, which are fragile. Thus, the Q-AWG requires a radically different methodology from classical pulse shaping. Here, we invent an architecture of Q-AWGs that can operate semi-deterministically at a repetition rate over gigahertz in principle. We demonstrate its core technology via generating highly nonclassical states with temporal waveforms that have never been realized before. This result would lead to powerful quantum technologies based on Q-AWGs such as practical optical quantum computing.
Outpatient palliative care referral system (PCRS) for patients with advanced cancer: an impact evaluation protocol
Authors: Brunelli Cinzia , Zecca Ernesto , Pigni Alessandra , Bracchi Paola , Caputo Mariangela , Lo Dico Silvia , Fusetti Viviana , Tallarita Antonino , Bergamini Cristiana , Brambilla Marta , Raimondi Alessandra , Niger Monica , Provenzano Salvatore , Sepe Pierangela , Alfieri Sara , Tinè Gabriele , De Braud Filippo , Caraceni Augusto Tommaso
Published: October 2022

Introduction

Early palliative care (PC) in the clinical pathway of advanced cancer patients improves symptom control, quality of life and has a positive impact on overall quality of care. At present, standardised criteria for appropriate referral for early PC in oncology care are lacking. The aim of this project is to develop a set of standardised referral criteria and procedures to implement appropriate early PC for advanced cancer patients (the palliative care referral system, PCRS) and test its impact on user perception of quality of care received, on patient quality of life and on the use of healthcare resources.

Setting

Selected oncology clinics and PC outpatient clinic.

Methods and analysis

A scoping literature review and an expert consultation through a nominal group technique will be used to revise existing referral tools and to develop a new one, the PCRS. 25 patients will be enrolled in a pilot study to assess feasibility of the implementation of PCRS; 10 interviews with patients and healthcare professionals will be carried out to evaluate applicability.

A pretest–post-test quasiexperimental study involving 150 patients before implementation of the PCRS and 150 patients after implementation will be carried out.

Patient satisfaction with care received, quality of life and use of resources, and caregiver satisfaction with care will also be assessed to explore the impact of the intervention.

Ethics and dissemination

Ethical approval for the study has been granted by the Institutional Review board of the Fondazione IRCCS Istituto Nazionale Tumori; approval reference INT201/19.

Results will be disseminated through open access publications and through scientific communication presented at national and international conferences.

Trial registration number

NCT04936568.
Epidemiology, aetiology, interventions and genomics in children with arthrogryposis multiplex congenita: protocol for a multisite registry
Authors: Dahan-Oliel Noémi , van Bosse Harold , Darsaklis Vasiliki Betty , Rauch Frank , Bedard Tanya , Bardai Ghalib , James Michelle , Raney Ellen , Freese Krister , Hyer Lauren , Altiok Haluk , Pellett Jonathan , Giampietro Philip , Hall Judith , Hamdy Reggie Charles
Published: October 2022

Introduction

Arthrogryposis multiplex congenita (AMC) is an umbrella term including hundreds of conditions with the common clinical manifestation of multiple congenital contractures. AMC affects 1 in 3000 live births and is caused by lack of movement in utero. To understand the long-term needs of individuals diagnosed with a rare condition, it is essential to know the prevalence, aetiology and functional outcomes in a large sample. The development and implementation of a multicentre registry is critical to gather this data. This registry aims to improve health through genetic and outcomes research, and ultimately identify new therapeutic targets and diagnostics for treating children with AMC.

Methods and analysis

Participants for the AMC registry will be recruited from seven orthopaedic hospitals in North America. Enrollment occurs in two phases; Part 1 focuses on epidemiology, aetiology and interventions. For this part, retrospective and cross-sectional data will be collected using a combination of patient-reported outcomes and clinical measures. Part 2 focuses on core subset of the study team, including a geneticist and bioinformatician, identifying causative genes and linking the phenotype to genotype via whole genome sequencing to identify genetic variants and correlating these findings with pedigree, photographs and clinical information. Descriptive analyses on the sample of 400 participants and logistic regression models to evaluate relationships between outcomes will be conducted.

Ethics and dissemination

Ethical approval has been granted from corresponding governing bodies in North America. Dissemination of findings will occur via traditional platforms (conferences, manuscripts) for the scientific community. Other modalities will be employed to ensure that all stakeholders, including youth, families and patient support groups, may be provided with findings derived from the registry. Ensuring the findings are circulated to a maximum amount of interested parties will ensure that the registry can continue to serve as a platform for hypothesis-driven research and further advancement for AMC.
Prognostic prediction models for endovascular abdominal aortic aneurysm repair: protocol for a scoping review
Authors: Ul-Mulk Zoheb , Antoniou George A
Published: October 2022

Introduction

Endovascular aneurysm repair (EVAR) has a marked short-term advantage over open surgical repair in managing abdominal aortic aneurysms (AAA); however, this benefit is lost in the long term. The current trend towards stratified medicine has given rise to diverse prognostic prediction models and scoring systems for EVAR. These models could act as decision support tools that employ patient and operative factors, to improve long-term outcomes. Past literature evaluated and compared model performance for predicting one outcome, for example, mortality. None were deemed competent for clinical application. The proposed study will use a scoping review approach to capture literature on prognostic modelling in EVAR for all predictable outcomes. The results are anticipated to inform future research, identify knowledge gaps, and assist in determining the potential of models for clinical use.

Methods and analysis

The proposed study will use the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) extension for scoping Reviews as a framework for conducting the review. PubMed Central, Embase and Cochrane Library will be searched and screened for peer-reviewed studies on prognostic modelling for EVAR, published between 2000 and 2022. No limits exist on predictor variables used and outcomes predicted by the model for inclusion, provided they apply to AAA patients managed with EVAR. Data will be abstracted using a charting form based on the Critical Appraisal and Data Extraction for Systematic Reviews of Prediction Modelling Studies guidelines and PRISMA guidelines for systematic reviews. The Prediction model Risk of Bias Assessment Tool and the Transparent Reporting of a multivariable prediction model for Individual Prognosis Or Diagnosis checklist will be used to critically appraise included studies.

Ethics and dissemination

Since scoping reviews cover secondary data from published literature, ethical approval is not required. The findings will be disseminated via peer-reviewed publications and presentations at key conferences.
Experiences and perception of character strengths among patients with breast cancer in China: a qualitative study
Authors: Yan Tingting , Chan Carmen Wing Han , Chow Ka Ming , Li Mingzi
Published: October 2022

Objective

To explore the patients’ experiences on character strengths that Chinese patients experience after the diagnosis of breast cancer.

Design

A qualitative, exploratory study using semistructured interviews based on the patients’ lived experience after being diagnosed with breast cancer. Ethics approval was granted. Interviews were audiorecorded and transcribed verbatim. Values in Action Classification of Strengths provided conceptual framework for analysing strengths. Directed content analysis based on the classification of strengths and framework analysis were used to analyse transcribed data. The Standards for Reporting Qualitative Research guideline was followed.

Setting

The Second Affiliated Hospital of Zhengzhou University and Henan Provincial Cancer Hospital in China.

Participants

Adult patients over 18 years, diagnosed with breast cancer between October 2019 and December 2020 were recruited. We used purposive sample method to collected data from 24 participants diagnosed with breast cancer.

Results

Six themes (virtues) emerged from our analysis. In addition, two new subthemes (character strengths) emerged in this study, selflessness and pragmatism, respectively. Patients with breast cancer described a large repertoire of character strengths they used or wished for during survivorship, including gratitude, hope, humility, kindness, humour, honesty and forgiveness. Cultural values (eg, collectivism, familyism, Confucianism and Buddhist beliefs) helped structure the experiences of Chinese patients’ character strengths. Patients wanted their character strengths to be more noticed, appreciated and encouraged by others and reported their psychological trajectory of using personal strengths.

Conclusion

The findings indicated that patients with breast cancer believing character strengths are important to them. Medical staff should pay more attention to motivating and cultivating character strengths of patients with breast cancer. Attention to make strength-based practices workable in clinical health promotion programmes is necessary. The healthcare system should develop tailored individualised psychological services that specifically address patients' needs for the application of personalised character strengths.

Trial registration number

NCT04219267, Pre-results.