Incremental Steps Research Articles

Enhancing Thermal Conductivity of Water-Ethylene Glycol Mixtures: A Study on TiO2-Al2O3 Hybrid Nanofluids with Surfactants

This analysis examines the thermal behaviour of 40% ethylene glycol-based TiO2-Al2O3 hybrid nanofluids by synthesizing them and assessing their thermal conductivity as a function of volume concentration and temperature. These hybrid nanofluids, emerging as a promising new class of advanced operating fluids, offer remarkable potential for enhancing heat transfer performance in various thermal engineering applications. Using a two-stage synthesis method, TiO2-Al2O3/40% ethylene glycol nanofluids were prepared across five distinct volume focuses (varying from 0.02% to 0.1%), incorporating Polyvinylpyrrolidone (PVP) as a stabilizing emulsifier. Precise thermal conductivity measurements were conducted over 30 °C to 80 °C, with incremental steps of 10 °C, ensuring comprehensive data collection. The investigation yielded significant findings, notably a substantial maximum thermal conductivity enhancement of 37.44%, observed at 80 °C with a 0.1% volume concentration, demonstrating pronounced sensitivity to elevated temperatures and concentrations. The strategic addition of PVP surfactant resulted in a remarkable 125% improvement in the nanofluid's stability period, although a maximum 5.33% reduction in thermal conductivity. Considering the inadequacy of existing predictive models to capture the observed data accurately, this study proposed developing a high-precision predictive model, achieving an impressive maximum deviation of less than 3%. The research concludes that these hybrid nanofluids, characterized by their exceptional stability and significantly enhanced thermal conductivity, hold immense potential to revolutionize heat transfer applications across various domains of practical thermal engineering. This breakthrough paves the way for developing more efficient, high-performance heat transfer systems, potentially catalysing energy efficiency and thermal management advancements across diverse industrial sectors.

Future-proofing class-incremental learning

Exemplar-free class incremental learning is a highly challenging setting where replay memory is unavailable. Methods relying on frozen feature extractors have drawn attention recently in this setting due to their impressive performances and lower computational costs. However, those methods are highly dependent on the data used to train the feature extractor and may struggle when an insufficient amount of classes are available during the first incremental step. To overcome this limitation, we propose to use a pre-trained text-to-image diffusion model in order to generate synthetic images of future classes and use them to train the feature extractor. Experiments on the standard benchmarks CIFAR100 and ImageNet-Subset demonstrate that our proposed method can be used to improve state-of-the-art methods for exemplar-free class incremental learning, especially in the most difficult settings where the first incremental step only contains few classes. Moreover, we show that using synthetic samples of future classes achieves higher performance than using real data from different classes, paving the way for better and less costly pre-training methods for incremental learning.

Measurement and analysis of residual stress of multilayer carbon fiber laminate based on incremental drilling method

In the automotive and aerospace industries, carbon fiber is widely used in structures such as chassis and wings due to its lightweight and excellent mechanical properties, and the residual stresses are crucial for product design. In this paper, six kinds of carbon fiber laminates with different layup directions are investigated by using the integral method, and the calibration coefficient matrix is numerically solved by using ABAQUS finite element software, and the effects of laminate direction and incremental step on the three-direction residual stresses are experimentally analyzed. The residual stresses in different oriented layers were predicted by classical lamination theory (CLT), and the longitudinal, transverse and in-plane shear stresses were compared by combining incremental drilling experiments with calibration factors. The results showed that the ply with [45/90/−45/0/45/90/−45/0] laminate had the best performance,the difference between theoretical and experimental values for σx was 0.421MPa. The maximum τxy measurement was 1.7103MPa, with a maximum percentage error of 25.3%. The maximum difference for σy was 0.7306MPa. These findings indicate that the method is more accurate in predicting the residual stresses in the first four layers of composite material. This provides important theoretical and experimental support for the optimal design of composites.

Study of the performance of a 3D modular geosynthetic reinforced soil bridge abutment under overloading

The objective of this study was to investigate the response characteristics of three-dimensional geosynthetic reinforced soil (GRS) bridge abutments subjected to overload conditions in terms of deformation, soil stresses, and reinforcement strains. To this end, a 1:2 scale model of a GRS bridge abutment was constructed and subjected to a detailed analysis when the vertical load was increased in incremental steps. The results showed that the GRS abutment performed well and did not reach the plastic state at six times the service limit state (SLS) load. The settlement at the top of the abutment increases with increasing load, and the settlement results in the central bulging of both the front and wing walls, which is inconsistent with the assumption of plane strain. Therefore, a novel three-dimensional facing displacement model that outperforms traditional calculation methods is presented. The incremental vertical soil stresses in the center of the abutment increased significantly, and the U.S. Federal Highway Administration (FHWA) method better predicted the vertical soil stresses on the GRS bridge abutments under SLS loads; however, this method underestimates the incremental vertical soil stresses under overloads. The maximum reinforcement strain occurred in the middle of the abutment, and the deformation of the reinforcement was not uniform under overload, indicating that an overload may lead to the destruction of the reinforcement under the beam seat. The results of this study can serve as a reference for the design and application of GRS bridge abutments.

Implementing Evidence-Based Practices in Rural Areas: Development and Testing of a Researcher Practitioner Collaboration in Mental Health

ABSTRACT Purpose Rural communities face specific challenges when attempting to implement evidence-based interventions, due to their size, distance from knowledge centers, and broad responsibility for the local population. The aim of this study was to investigate the utilization of an RPC (Research Practice Collaboration) initiative as a strategy for translation and implementation of EBPs in rural municipalities seeking to develop their services for individuals with serious mental illness. Materials and Methods Following a broad invitation consisting of a presentation of the newly produced National Psychiatry Guidelines, to four northern regions in Sweden, four municipalities participated in an RPC process that focused on the implementation of specific EBPs. Results In addition to confirming many of the challenges in rural areas, the participants reported that the RPC process helped them to understand the relevance of these methods to their own conditions and ambitions. They were able to recognize and build on their already existing strengths and achieve incremental steps toward EBPs. Discussion The collaborative nature of the structure and knowledge dissemination, requiring extremely tailored implementation strategies while considering the essential components in relation to local conditions, led to increased readiness to implement these practices as locally relevant. Conclusion Research practice collaborations may contribute to the implementation of EBPs in rural areas by increasing the accessibility and relevance of these methods in these challenging conditions. Identifying structures for sustainably supporting these types of collaborations is a challenge for national actors.

Premature deindustrialization, inter-sectoral employment shifts, and accelerated servicization

Concern about the implications of ‘premature deindustrialization’ for economic growth of developing countries has evolved into investigation over whether parts of the service sector can play a propulsive role similar to that played by manufacturing previously. Such investigation is hampered by coarse and changing service sector classifications, but it does appear that some service sectors play such a role. In this paper we take the incremental but important step of identifying whether employment growth in certain service sectors corresponds with employment loss in manufacturing through ‘premature deindustrialization’, deploying the counter-concept of ‘accelerated servicization’. Investigating employment growth in key service sectors which are more finely classified than those used in the previous studies, we find that: (1) of five broadly classified service sectors, only that encompassing ‘FIRE (finance, insurance and real estate) and business services’ demonstrates accelerated servicization, and (2) this is attributable to the component sectors of ‘information services’ and ‘business support’, but not FIRE. In fact FIRE exhibits a distinctive pattern, warranting the label ‘quasi service’.

Esophageal pressure as estimation of pleural pressure: a study in a model of eviscerated chest

BackgroundTranspulmonary pressure is the effective pressure across the lung parenchyma and has been proposed as a guide for mechanical ventilation. The pleural pressure is challenging to directly measure in clinical setting and esophageal manometry using esophageal balloon catheters was suggested for estimation. However, the accuracy of using esophageal pressure to estimate pleural pressure is debated due to variability in the mechanical properties of respiratory system, esophagus and esophageal catheter. Furthermore, while a vertical pleural pressure gradient exists across lung regions, esophageal pressure balloon provides a single value, representing, at most, the pressure surrounding the esophagus.MethodsIn a swine model with a preserved esophagus and a single homogenous, easily measurable intrathoracic pressure, we evaluated esophageal pressure’s agreement with intrathoracic pressure at different positive end-expiratory pressure (PEEP) levels (0, 5, 10, 15 cmH2O). We assessed the improvement of measurement accuracy by correcting absolute esophageal values using a previously described technique, that accounts for the pressure generated by the esophageal wall in response to esophageal balloon inflation.The study involved five swine, wherein two different esophageal catheters were used alongside the four distinct PEEP levels. Swings, uncorrected and corrected absolute esophageal pressures (end-inspiratory, end-expiratory) were compared with their respective intrathoracic pressures. The effect of correction technique was assessed with manual incremental step inflation procedure.ResultsWe found that both catheters significantly overestimated absolute esophageal pressure compared to intrathoracic pressure (5.01 ± 3.32 and 6.06 ± 5.62 cmH2O at end-expiration and end-inspiration, respectively), with error increasing at higher positive end-expiratory pressure levels (end-expiration: 2.36 ± 2.03, 3.77 ± 1.37, 6.24 ± 2.51 and 7.69 ± 4.02 for each PEEP level, P < 0.0001; end-inspiration: 1.71 ± 2.10, 3.70 ± 1.73, 7.67 ± 3.62 and 11.14 ± 7.60 for each PEEP level, P = 0.0004).Applying the correction technique significantly improved agreement for absolute values (0.82 ± 1.62 and 1.86 ± 3.94 cmH2O at end-expiration and end-inspiration, respectively). Esophageal pressure swings accurately estimated intrathoracic pressure swings at low-medium intrathoracic pressures (-0.64 ± 0.62, -0.07 ± 0.53, 1.43 ± 1.51, and 3.45 ± 3.94 at PEEP 0, 5, 10 and 15 cmH2O, respectively; P = 0.0197).ConclusionsThe correction technique, based on the mechanical response of esophageal wall to the balloon inflation, is fundamental for obtaining reliable estimations of absolute intrathoracic pressure values, and for ensuring its correct application in clinical setting.

Cigarette Smoking Impairs Cardiorespiratory and Metabolic Response at Peak Incremental Exercise and during Recovery in Young, Physically Active Adults

ABSTRACT Purpose: Cigarette smoking (CS) induces systemic changes that impair cardiorespiratory and muscular function both at rest and during exercise. Although these abnormalities are reported in sedentary, middle-aged smokers (SM) with pulmonary disease, few and controversial studies focused on young, physically active SM at the early stage of smoking history. This study aimed at assessing the impact CS on cardiorespiratory and metabolic response during an incremental test and the subsequent recovery in young, physically active SM without known lung or cardiovascular disease. Methods: After pulmonary function evaluation, 12 SM (age: 22±2 yr; body mass: 75±8 kg; stature: 1.78±0.06 m; 12±4 cigarette/day for 6±2 years; mean±SD) and 12 non-smokers (CTRL; age: 23±1 yr; body mass: 76±8 kg; stature: 1.79±0.08 m) matched for age and exercise habits, underwent an exhaustive incremental step test (25 W/2 min) on a cycle ergometer. Pulmonary O2 uptake (V’O2), expiratory ventilation (V’E), heart rate (f H) responses and lactate concentration were assessed during the test and subsequent recovery. Results: Despite similar static lung volumes, SM reported lower peak expiratory flow (-23%; P = 0.003) and maximal voluntary ventilation (-10%; P = 0.003). At submaximal exercise, no differences in the cardiorespiratory and metabolic were noted between the two groups. However, SM exhibited ventilatory (P &lt; 0.01) and lactate thresholds at lower work rates (P = 0.01). At peak exercise, SM exhibited lower V’O2 (-8%; P = 0.02), mechanical power (-11%; P = 0.02) and V’E (-9%; P = 0.01). During recovery, SM showed longer time constants (τ) in V’O2 (+52%; P = 0.002), V’E (+19%; P = 0.027) and f H (+21%; P = 0.022) and smaller f H at 30 s of recovery (HRR30; -31%; P = 0.032). Conclusions: These results are compatible with an early CS-related impairment of the cardiorespiratory and metabolic function even in young individuals with relatively short smoking history.

Local invariants of conformally deformed non-commutative tori II: Multiple operator integrals

We explicitly compute the local invariants (heat kernel coefficients) of a conformally deformed non-commutative d-torus using multiple operator integrals. We derive a recursive formula that easily produces an explicit expression for the local invariants of any order k and in any dimension d. Our recursive formula can conveniently produce all formulas related to the modular operator, which before were obtained in incremental steps for d∈{2,3,4} and k∈{0,2,4}. We exemplify this by writing down some known (k=2, d=2) and some novel (k=2, d≥3) formulas in the modular operator.

Cavity formation in silica‐filled rubber compounds observed during deformation by ultra small‐angle x‐ray scattering

AbstractWhen silica‐filled rubber compounds are deformed, structural modifications in the material's bulk lead to irreversible damage, the most significant of which is cavitation appearing within the interfaces of interconnected polymer and filler networks. This work introduces a new method to analyze cavitation in industrial‐grade rubbers based on ultra small‐angle x‐ray scattering. This method employs a specially designed multi‐sample stretching device for high‐throughput measurements with statistical relevance. The proposed data reduction approach allows for early detection and quantification of cavitation while providing at the same time information on the hierarchical filler structures at length scales ranging from the primary particle size to large silica agglomerates over four orders of magnitude. To validate the method, the scattering of SSBR rubber compounds filled with highly dispersible silica at different ratios was measured under quasi‐static strain. The strain was applied in incremental steps up to a maximum achievable elongation or breakage of the sample. From the measurements performed in multiple repetitions, it was found that the minimum strain necessary for cavity formation and the size evolution of the cavities with increasing strain are comparable between these samples. The sample with the highest polymer content showed the lowest rate of cavity formation and higher durability of silica structures. The structural stability of the compounds was determined by the evolution of the filler hierarchical structures, obtained by fitting data across the available strain range.

Small Punch Test to Estimate the Threshold Stress in Aggressive Environments by Incremental Step Loading

The present work is a relevant advance in the validation of the incremental step loading technique (ASTM F1624 standard) when applied to Small Punch tests (SPT) for the threshold load determination of medium- and high-strength steels in aggressive environments, as a novel alternative to conventional time-consuming tests under constant load. It completes previous works by the authors on this topic, extending a methodology to estimate the threshold stress from SPT tests in aggressive environments, covering the whole range of hardness marked by ASTM F1624 as the main goal. This is achieved by calibrating a model of the material’s hardness by the use of a coefficient in function of it. For this purpose, four medium- and high-strength steels of 33, 35, 50 and 60 HRC (Hardness Rockwell C) are exposed to three different cathodic polarization hydrogen embrittlement environments of 1, 5 and 10 mA/cm2 in 1N H2SO4 acid electrolyte connected to a platinum anode. Threshold stresses in these circumstances are obtained by uniaxial specimens following ASTM F1624 and compared to their homologous threshold loads obtained by Small Punch tests according to the authors’ original methodology proposal. Finally, the aforementioned model, consisting of a correlation based on composing an elastic and a plastic part, is calibrated for a hardness ranging 33–60 HRC, this being the main original contribution of this work; the elastic part is dependent just on the elastic-to-plastic transition SPT load, while the plastic part is ruled by a material hardness-dependent coefficient. This technique supposes an advance in engineering tools, due to its applicability in situations of material shortage, such as in-service components, welded joints, local areas, complex geometries, small thicknesses, etc., often present in aerospace, automotive or oil–gas, among others.

Vibrations Control of a SODF Structure Using TMD and MR Damper with Fuzzy Logic Algorithm Based on Velocity

In this study, the effects of using a passive tuned mass damper (TMD) with optimal parameters and a semi-active magnetorheological damper (MR damper) have been evaluated separately and simultaneously to control seismic vibrations of a linear single degree of freedom system, which was a simple "mass-spring-damper" model. OpenSEES software was used to model the single degree of freedom system and TMD, and MATLAB software was used to model MR damper. Fuzzy logic algorithm was used by MATLAB to determine the appropriate voltage for MR damper. By solving the dynamic equation of the damper, its force was calculated and this force was applied to the single degree of freedom system by OpenSEES. In the following, incremental dynamic analysis (IDA) has been performed using 7 earthquake records with maximum acceleration of 0.1g to1.0g with incremental step of 0.1g. Earthquakes are applied to four models without dampers, equipped with optimized TMD, equipped with MR damper, and equipped with both TMD and MR damper. The results showed that the simultaneous use of TMD and MR damper had the greatest effect on controlling the vibration of the system and reduced the maximum displacement by 22.36% and the maximum base shear by 21.85% compared to the case without dampers. Also, using only MR damper had a greater effect than using only TMD on reducing the seismic responses of the single degree of freedom system.

Catalogue of coastal-based instances with bathymetric and topographic data

Abstract. We provide a catalogue of 17 700 unique coastal-based instances distributed throughout the globe and derived from bathymetric and topographic data made publicly available by the General Bathymetric Chart of the Oceans (GEBCO) as of 2022. These instances, or digital elevation models (DEMs), are delivered in the form of raster grids with a 15 arcsec resolution and are divided equally into three libraries, namely A, B, and C. In a given library, the dimensions range from a minimum of 10×10 cells to a maximum of 300×300 cells, with an incremental step of 5, i.e. 59 unique dimensions with 100 instances per dimension. In addition, for each dimension, these instances are ordered by increasing number of maritime cells and have in common the presence of a unique maritime-connected component with a ratio of maritime cells lying between 25 % and 95 % so as to cover a broad spectrum of different coastline geometries. In this paper, we will describe in detail the procedure used for their automated generation. The resulting catalogue can be downloaded from Zenodo, a general-purpose repository operated by CERN (European Organisation for Nuclear Research) and developed under the European OpenAIRE programme, at the following persistent address: https://doi.org/10.5281/zenodo.10530247 (Thuillier et al., 2024c). Additionally, a set of 18 colour palettes specifically designed for the visualisation of DEMs has been derived for this occasion and is available at the following address: https://doi.org/10.5281/zenodo.10530296 (Thuillier et al., 2024e). Both of these repositories come with comprehensive documentation.

Differences in motivational dynamics between experienced cyclists and untrained participants during an incremental endurance exercise task

PurposeThe conflict between the desire to reduce effort during exercise and the performance goal of the exercise task contributes to explaining endurance exercise performance. However, whether the trajectories of these two motivational responses systematically differ across individuals with different characteristics is poorly understood. The present study examined whether changes in desire to reduce effort and performance goal value across moderate, heavy, and severe exercise intensity domains differed between cyclists and untrained, but active participants. MethodsFifty participants (14 cyclists and 36 untrained) completed an incremental step test on a cycle ergometer, in which work rate was increased by 25 W every 4 min until voluntary exhaustion. Desire to reduce effort, performance goal value, and blood lactate concentration (for determination of exercise intensity domains) were measured every 4 min and the data were analysed using multilevel modelling. ResultsDesire to reduce effort increased quicker for untrained participants in the moderate exercise intensity domain (b = 1.66, p < .001) and across the whole trial (b = 1.64, p < .001), compared to cyclists (b = .69, and b = 1.14, respectively, both p < .001). Untrained participants reported similar performance goal value at the beginning of the trial (b = 16.02, p < .001), compared to cyclists (b = 17.25, p < .001). Beyond moderate intensities, the performance goal value decreased significantly for the untrained participants (b = −.70, p < .001) but significantly increased for cyclists (b = .45, p = .01). This pattern was also observed when focusing solely on the severe intensity domain (cyclists: b = .90, p < .001; untrained: b = −.84, p < .001). ConclusionThere are distinct differences in the desire to reduce effort and performance goal value between cyclists and untrained athletes. Identifying these systematic differences enhances the credibility of the desire-goal conflict framework in explaining endurance performance and provides insight into the type and timing of interventions that might be successful in improving performance.

Incremental Steps on the Path to Progress

Incremental Steps on the Path to Progress

Investigation of various winglets using computational fluid dynamics for subsonic aircraft

Abstract The tiny, upturned, or downturned extensions at the tips of an aircraft’s wings are designated as winglets. By minimizing drag and improving fuel efficiency, they are introduced to increase the aircraft’s aerodynamic efficiency. Winglets are now a day’s employed in the commercial aircraft to minimise the induced effect caused by wing tip vortices produced at low subsonic speeds. In this article, we have selected NACA 2412, from which we have created a swept back wing with a 20-degree sweep angle that has eight distinct winglet configurations. SolidWorks 2023 is used for design work, and ANSYS 19.2 is used for analysis. The analysis is carried out by changing the angle of attack (AOA) from -6 degrees to 20 degrees with an incremental step of 2 degrees. Here, we have used the k-epsilon turbulence model to capture the turbulence and 100 m/s velocity is maintained throughout the analysis. From this analysis, a potential solution of aerodynamic co-efficient (lift, drag, cl, cd and cl/cd) are being observed. Blended winglet with cant angle 35 degrees produces high lift-to-drag ratio compared with another winglet configuration. The insights gained from the study are plotted in various graphs such as cl vs alpha, cd v/s alpha and cl/cd v/s alpha and the CFD results show a considerable improvement in aircraft’s performance after using winglets. Aluminium alloy’s high strength to weight ratio, robust corrosion resistance, enhanced conductivity, and outstanding ductility qualities will make it easier for us to manufacture winglets in the future.

How does running technique change with running speed? A quantitative analysis based on practice-informed principal components

Introduction &amp; Purpose “Running technique is an important component of running economy and performance” (Folland et al., 2017). While economy and performance can directly be measured, no common measuring method exists for running technique. The aims of this study were twofold: (I) develop practice-informed running technique measures based on technique characterizations used by coaches (i.e. distinct variations of body segment movements instead of discrete kinematics); (II) investigate, how running technique changes with running speed. Methods Two independent kinematic data sets were recorded on a treadmill using a retro-reflective marker setup (“Plugin-Gait”) and a 10-camera system (Vicon Motion Systems Ltd., Oxford, UK). First, 20 experienced runners (age 25 ± 2 y; 10 females, 10 males) were tasked to vary their running according to 14 technique elements (vertical, horizontal, hip and upper body movement, foot strike, track width, ankle rotation, leg swing, back posture, elbow flexion/extension, arm swing amplitude and direction, gaze direction, cadence) into two opposing extreme forms per element. Measures for the 14 running technique elements were developed using principal component analyses (one PCA per two opposing technique element variations) and selecting principal components (PCs; Federolf, 2016) that aligned with the represented technique element. Second, an additional 19 experienced runners (age 30 ± 9 y, 3 females, 16 males) ran at different speeds (10-17 km/h with 1 km/h incremental steps) without any technique instructions. Their data were projected onto the selected PCs, resulting in averaged PC score waveforms of the different speeds along each technique element. Waveforms were analysed using statistical parametric mapping (SPM) with a repeated measures ANOVA design (Pataky et al., 2013). Results For all 14 technique elements, sections of significant differences between at least two different speeds were found within the cycle-normalized PC score waveforms. Figure 1 exemplifies the results for the foot track width, where the lateral range of motion of the feet decreased with speed. Post-hoc analyses revealed further differences, such as less vertical and greater horizontal movement, as well as smaller leg swing and greater arm swing amplitude at 17 km/h compared to 10 km/h. Discussion Firstly, practice-informed and data-driven running technique measures could be developed (I). Secondly, the measures could be applied on a group of runners and plausible changes in their technique due to running speed were identified (II). So far, the speed-dependent technique adaptations only reflect the specific techniques on a treadmill for a predominately male reference group, but the presented concept can be transferred to other runners and settings. Conclusion Running technique varies with speed, and the developed technique measures facilitate comparisons of these differences using practically relevant technique elements. Since the movement adaptations associated with running speed are directly quantifiable and visualizable, technique models for different speed ranges might be developed by researchers and then utilized by runners to train and assess their technique in alignment with these models.

Design of a Fiber Temperature and Strain Sensor Model Using a Fiber Bragg Grating to Monitor Road Surface Conditions

In this paper, the types and principles of operation of fiber sensors based on fiber Bragg gratings (FBGs) are investigated. The influence of strain and temperature on the characteristics of FBGs is considered, and a method for the simultaneous measurement of these parameters is presented. Laboratory studies were carried out in the temperature range from +18 °C to +135 °C with an incremental step of 5 °C, with the actual temperature not deviating by more than ±0.5 °C. From the data obtained, the Bragg wavelength–temperature relationships were plotted, which showed a linear increase in wavelength with increasing temperature. This study shows that the use of two FBGs with a different sensitivity to temperature and strain allowed for the simultaneous measurement of both parameters. Numerical models created in the MATLAB R2022b environment confirmed the high accuracy and precision of the measurements. The FBG-based sensors demonstrated a robust performance in harsh environments, withstanding temperatures of up to 160 °C and high humidity, making them applicable in various industries and sciences. This work confirms that FBGs are a promising tool for accurate temperature and strain measurements, providing reliable results in harsh environments.

First demonstration of 2T0C-FeDRAM: a-ITZO FET and double gate a-ITZO/a-IGZO FeFET with a record-long multibit retention time of >4-bit and >2000 s.

Conventional DRAM, consisting of one transistor and one capacitor (1T1C), requires periodic data refresh processes due to its limited retention time and data-destructive read operation. Here, we propose and demonstrate a novel 3D-DRAM memory scheme available with a single transistor and a single ferroelectric field-effect transistor (FeFET) DRAM (2T0C-FeDRAM), which offers extended retention time and non-destructive read operation. This architecture uses a back-end-of-line (BEOL)-compatible amorphous oxide semiconductor (AOS) that is suitable for increasing DRAM cell density. Notably, the device structures of a double gate a-ITZO/a-IGZO FeFET, used for data storage and reading, are engineered to achieve an enlarged memory window (MW) of 1.5 V and a prolonged retention time of 104 s. This is accomplished by a double gate and an a-ITZO/a-IGZO heterostructure channel to enable efficient polarization control in hafnium-zirconium oxide (HZO) layers. We present successful program/erase operations of the double gate a-ITZO/a-IGZO FeFET through incremental step pulse programming (ISPP), demonstrating multi-level states with remarkable retention characteristics. Most importantly, we perform 2T0C-FeDRAM operations by electrically connecting the double gate a-ITZO/a-IGZO FeFET and the a-ITZO FET. Leveraging the impressive performance of the double gate a-ITZO/a-IGZO FeFET technology, we have effectively showcased an exceptionally record-long retention time exceeding 2000 s and 4-bit multi-level states, positioning it as a robust contender among emerging memory solutions in the era of artificial intelligence.

Training volume, intensity, and performance of world-class Chinese rowers prior to the 2019 world championships: A case study

Six world-class Chinese male rowers (age: 28.2 ± 3.2 years; height: 1.93 ± 0.02 m; body mass: 94.7 ± 3.9 kg) participated in the study. The training volume in different modalities and intensities were recorded over 44 weeks. To evaluate rowing performance, rowers completed four 2000 m and 5000 m maximum effort time trials and two incremental step tests. Total training time for the season was 907 h, which consisted of 67.5% of rowing training, 16.9% of strength training, 15.2% of warm-up and flexibility, and 0.4% of non-specific endurance training. The rowing training intensity distribution (TID) was 87.0% performed at low intensity (LIT), 8.4% at moderate intensity (MIT), and 4.6% at high intensity (HIT). There was no significant difference in average weekly rowing training volume (distance) at LIT across four phases (p = 0.12), as well as rowing training at MIT (p = 0.07) and HIT (p = 0.97). The fourth 2000 m time trials performance significantly improved from the first trial (−6.4 s, p = 0.02). The fourth 5000 m time trial performance was significantly improved from the first (−13.4 s, p = 0.02) and second trial (−14.1 s, p = 0.01). The final-step mean power output (W) in the second incremental step test improved significantly (p = 0.04). In the 2018–19 season, China's world-class rowers conducted considerable LIT rowing. The training volume distribution and rowing TID were similar in all phases.