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Author(s):  
André Antunes ◽  
Christophe Domingos ◽  
Luísa Diniz ◽  
Cristina P. Monteiro ◽  
Mário C. Espada ◽  
...  

The present study sought to investigate if faster upper body oxygen uptake (VO2) and hemoglobin/myoglobin deoxygenation ([HHb]) kinetics during heavy intensity exercise were associated with a greater upper body repeated-sprint ability (RSA) performance in a group of judokas and in a group of individuals of heterogenous fitness level. Eight judokas (JT) and seven untrained healthy participants (UT) completed an incremental step test, two heavy intensity square-wave transitions and an upper body RSA test consisting of four 15 s sprints, with 45 s rest, from which the experimental data were obtained. In the JT group, VO2 kinetics, [HHb] kinetics and the parameters determined in the incremental test were not associated with RSA. However, when the two groups were combined, the amplitude of the primary phase VO2 and [HHb] was positively associated with the accumulated work in the four sprints (ΣWork). Additionally, maximal aerobic power (MAP), peak VO2 and the first ventilatory threshold (VT1) showed a positive correlation with ΣWork and an inverse correlation with the decrease in peak power output (Dec-PPO) between the first and fourth sprints. Faster VO2 and [HHb] kinetics do not seem to be associated with an increased upper body RSA in JT. However, other variables of aerobic fitness seem to be associated with an increased upper body RSA performance in a group of individuals with heterogeneous fitness level.


Author(s):  
Fang Li ◽  
Chun-Hao Chang ◽  
Chia-An Ho ◽  
Cheng-You Wu ◽  
Hung-Chih Yeh ◽  
...  

The maximal oxygen uptake (VO2max) prediction models established by step tests are often used for evaluating cardiorespiratory fitness (CRF). However, it is unclear which type of stepping frequency sequence is more suitable for the public to assess the CRF. Therefore, the main purpose of this study was to test the effectiveness of two 3-min incremental step-in-place (3MISP) tests (i.e., 3MISP30s and 3MISP60s) with the same total number of steps but different step-frequency sequences in predicting VO2max. In this cross-sectional study, a total of 200 healthy adults in Taiwan completed 3MISP30s and 3MISP60s tests, as well as cardiopulmonary exercise testing. The 3MISP30s and 3MISP60s models were established through multiple stepwise regression analysis by gender, age, percent body fat, and 3MISP-heart rate. The statistical analysis included Pearson’s correlations, the standard errors of estimate, the predicted residual error sum of squares, and the Bland–Altman plot to compare the measured VO2max values and those estimated. The results of the study showed that the exercise intensity of the 3MISP30s test was higher than that of the 3MISP60s test (% heart rate reserve (HRR) during 3MISP30s vs. %HRR during 3MISP60s = 81.00% vs. 76.81%, p < 0.001). Both the 3MISP30s model and the 3MISP60s model explained 64.4% of VO2max, and the standard errors of the estimates were 4.2043 and 4.2090 mL·kg−1·min−1, respectively. The cross-validation results also indicated that the measured VO2max values and those predicted by the 3MISP30s and 3MISP60s models were highly correlated (3MISP30s model: r = 0.804, 3MISP60s model: r = 0.807, both p < 0.001). There was no significant difference between the measured VO2max values and those predicted by the 3MISP30s and 3MISP60s models in the testing group (p > 0.05). The results of the study showed that when the 3MISP60s test was used, the exercise intensity was significantly reduced, but the predictive effectiveness of VO2max did not change. We concluded that the 3MISP60s test was physiologically less stressful than the 3MISP30s test, and it could be a better choice for CRF evaluation.


Metals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 6
Author(s):  
Matthias Castens ◽  
Stefanie Hoja ◽  
Holger Surm ◽  
Franz Hoffmann ◽  
Rainer Fechte-Heinen ◽  
...  

Damages to case-hardened components are often associated with the phenomenon of hydrogen embrittlement due to their specific fracture pattern. In the present work, the effects of the case hardening process on the hydrogen content in the material were investigated and the effects of hydrogen on the mechanical properties were examined. In order to determine not only the influence of the heat treatment process but also the influence of the material, the case-hardening steels EN20MnCr5 (SAE5120) and EN18CrNiMo7-6 (SAE4820) with different degrees of purity were investigated. From the results it can be deduced that the sulphidic and oxidic inclusions have no significant influence on the hydrogen content. When checking the mechanical properties, it was shown in the incremental step loading technique according to ASTM F1624 that a purely case-hardened condition only has a slight tendency to hydrogen embrittlement. However, if the material is additionally loaded with hydrogen, the material fails significantly below the maximum expected load in the incremental step loading test, which is to be interpreted as a clear indication of failure due to hydrogen embrittlement. However, the fracture patterns of these two states do not show any significant differences. Therefore, it does not seem possible to attribute damage to a case-hardened component to hydrogen embrittlement on the basis of the fracture pattern alone.


Author(s):  
Michiru Hogyoku ◽  
Yoshinori Yokota ◽  
Kazuhito Nishitani

Abstract We propose the novel trap-assisted tunneling (TAT) model that incorporates the ability to calculate dissipation of the kinetic energy of carriers propagating in the conduction or valence band. The proposed model allows us to evaluate capture efficiency (or the capture cross section) of carriers injected into the SiN charge trap layer via Fowler-Nordheim tunneling. By applying our TAT model to large planar Metal-Oxide-Nitride-Oxide-Semiconductor (MONOS) capacitors, experimental data showing that electron capture efficiency depends on the tunnel oxide thickness are physically interpreted. Furthermore, 3-dimensional technology computer-aided design (TCAD) simulation using SiN trap parameters roughly extracted from planar MONOS data shows that the calculated incremental step pulse programming characteristics of the charge trap memory (CTM) prototype device are comparable with measured data. We have found that additional time to calculate SiN trap charges is less than only 5 % of all remaining calculation time.


Author(s):  
Hussain Attia ◽  
Suleyman Ulusoy

Based on the fact that the effectiveness of perturb and observe algorithm in a maximum power point tracking maximum power point tracking (MPPT) in a photovoltaic array is a tradeoff between the tracking speed during the transient response and the oscillation around the stable level during the steady state response. To have a high tracking speed, incremental step should be high, but this high incremental step increases the oscillation level around the steady level of MPPT, whereas adopting low incremental step reduces the algorithm response time but improve the response during the steady state condition. This paper presents a new perturb and observe algorithm based on two step variable control for MPPT applications. A two variable incremental step control is proposed to gain the merit of high step for guaranteeing a fast response during tracking process, and also for guaranteeing the merit of low oscillation during the steady state working condition through adopting a low step during steady state response. The effectiveness of the proposal is proved by the analysis of the simulation results via MATLAB/Simulink software, and by the comparison of the simulation results with a conventional perturb and observe MPPT algorithm.


Electronics ◽  
2021 ◽  
Vol 10 (22) ◽  
pp. 2784
Author(s):  
Gerardo Malavena ◽  
Alessandro Sottocornola Sottocornola Spinelli ◽  
Christian Monzio Monzio Compagnoni

In this work, we investigate the implementation of a neuromorphic digit classifier based on NOR Flash memory arrays as artificial synaptic arrays and exploiting a pulse-width modulation (PWM) scheme. Its performance is compared in presence of various noise sources against what achieved when a classical pulse-amplitude modulation (PAM) scheme is employed. First, by modeling the cell threshold voltage (VT) placement affected by program noise during a program-and-verify scheme based on incremental step pulse programming (ISPP), we show that the classifier truthfulness degradation due to the limited program accuracy achieved in the PWM case is considerably lower than that obtained with the PAM approach. Then, a similar analysis is carried out to investigate the classifier behavior after program in presence of cell VT instabilities due to random telegraph noise (RTN) and to temperature variations, leading again to results in favor of the PWM approach. In light of these results, the present work suggests a viable solution to overcome some of the more serious reliability issues of NOR Flash-based artificial neural networks, paving the way to the implementation of highly-reliable, noise-resilient neuromorphic systems.


2021 ◽  
Vol 20 (5s) ◽  
pp. 1-20
Author(s):  
Shiqiang Nie ◽  
Weiguo Wu ◽  
Chi Zhang

3D charge-trap (CT) NAND flash-based SSD has been used widely for its large capacity, low cost per bit, and high endurance. One-shot program (OSP) scheme, as a variation of incremental step pulse programming (ISPP) scheme, has been employed to program data for CT flash, whose program unit is the Word-Line (WL) instead of the page. The existing program optimization schemes either make trade-offs among program latency and reliability by adjusting the program step voltage on demand; or remap the most error-prone cell states to others by re-encoding programmed data. However, the data pattern, which represents the ratio of 1s in data values, has not been thoroughly studied. In this paper, we observe that most small files do not contain uniform 1s and 0s among these common file types (i.e., image, audio, text, executable file), leading to programming WL cells in different states unevenly. Some cell states dominate over the WL, while others are not. Based on this observation, we propose a flexible reliability enhancement scheme based on the OSP scheme. This scheme programs the cells into different states with varied , i.e., these cells in one state, whose number is the largest in one WL, are programmed with a fine-grained (namely slow write). In contrast, the minority are programmed with a coarse-grained (namely fast write). So the reliability is improved due to averaging the major enhanced cells with the minor degraded cells without program latency overhead. A series of experiments have been conducted, and the results indicate that the proposed scheme achieves 34% read performance improvement and 16% lifetime elongation on average.


Author(s):  
Fang Li ◽  
Chun-Hao Chang ◽  
Yu-Chun Chung ◽  
Huey-June Wu ◽  
Nai-Wen Kan ◽  
...  

The purpose of this research was to develop the 3 min incremental step-in-place (3MISP) test for predicting maximal oxygen uptake (V•O2max). A total of 205 adults (20–64 years) completed the 3MISP and V•O2max tests. Using age, gender, body composition (BC) including percent body fat (PBF) or body mass index (BMI), and with or without heart rate (HR) at the beginning of exercise (HR0) or difference between HR at the third minute during the exercise and the first minute post exercise (ΔHR3 − HR4) in the 3MISP test, six V•O2max prediction models were derived from multiple linear regression. Age (r = −0.239), gender (r = 0.430), BMI (r = −0.191), PBF (r = −0.706), HR0 (r = −0.516), and ΔHR3 − HR4 (r = 0.563) were significantly correlated to V•O2max. Among the six V•O2max prediction models, the PBF model∆HR3 − HR4 has the highest accuracy. The simplest models with age, gender, and PBF/BMI explained 54.5% of the V•O2max in the PBF modelBC and 39.8% of that in the BMI modelBC. The addition of HR0 and ∆HR3 − HR4 increases the variance of V•O2max explained by the PBF and BMI models∆HR3 − HR4 by 17.98% and 45.23%, respectively, while standard errors of estimate decrease by 10.73% and 15.61%. These data demonstrate that the models established using 3MISP-HR data can enhance the accuracy of V•O2max prediction.


2021 ◽  
Vol 9 (209) ◽  
pp. 1-51
Author(s):  
Cleiton Ferreira

This study aims to evaluate the behavior of ASTM A653 CS-A G90 steel in the process of Incremental Sheet Forming – ISF, based on the following parameters: diameter of the tool (Dt in mm) and the vertical step size between consecutive contours (∆z in mm). The experiments were based on a variation of the ISF process, called Single Point Incremental Forming - SPIF. In this study, seventeen tests were conducted using a punching tool with diameters (Dt ) of 5, 6 and 8 mm and vertical steps (∆z) of 0.4, 0.6 and 0.8 mm, intending to evaluate the true strain to the ISF process and the surface finishing measured by roughness parameter (Rz). Whereas, for the execution of practical testing, the resources used were a CNCmachining center with three axes, tools for incremental forming and a sheet-press device. As a result, greater depths were achieved using an incremental step of 0.4 mm. In additional tests, it came to attention that the diameter of the tool was also an important parameter when it is desired to increase the formability and greater depths are obtained when using small diameters. It can be observed yet, there is a tendency to increase the roughness parameter Rz when using greater vertical steps ∆z


2021 ◽  
Author(s):  
Michelle Kent ◽  
Kip Findley

Abstract Hydrogen embrittlement (HE) susceptibility was investigated for Alloy 718 and Alloy 945X specimens heat treated to a set of conditions within the specifications of API Standard 6ACRA. Heat treatments were selected to simulate the potential variation in thermal history in thick sections of bar or forged products and produce various amounts of discontinuous grain boundary δ phase in Alloy 718 and M23C6 carbides in Alloy 945X, while maintaining a constant hardness in the range of 35-45 HRC for Alloy 718 and 34-42 HRC for Alloy 945X. Time-temperature-transformation (TTT) diagrams and experimentation were used to select a set of heat treatments containing no δ phase, a small quantity of δ, and a larger quantity of δ in Alloy 718. The presence of δ phase has not been verified for the moderate condition. A similar approach was taken regarding M23C6 carbides in Alloy 945X. Incremental step loading (ISL) tests were conducted under in-situ cathodic charging on circular notch tensile (CNT) specimens in a 0.5 M H2SO4 solution. During the test, the direct current potential drop (DCPD) was measured across the notch to determine the stress intensity associated with unstable crack growth. Results indicate that even very small quantities of δ phase in Alloy 718 are detrimental to HE resistance. Both Alloy 718 and Alloy 945X show decreases in HE resistance with aging, with a greater degradation in Alloy 718.


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