399 research outputs found

    Optimal Gear-Shifting of a Wet-Type Two-Speed Dual-Brake Transmission for an Electric Vehicle

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    In improving the efficiency of powertrain systems and ride comfort for electric vehicles (EVs), the transmission model is required to enable more accessible and more straightforward control of such vehicles. In this study, a wet-type, two-speed, dual-brake transmission system, as well as a new electromechanical clutch actuator, is presented for EVs. A new coordinated optimal shifting control strategy is then introduced to avoid sharp jerks during shifting processes in the transmission system. Based on a state-space model of the electromechanical clutch actuator and dual-brake transmission, we develop a linear quadratic regulator strategy by considering ride comfort and sliding friction work to obtain optimal control trajectories of the traction and shifting motors under model-based control. Simulations and bench tests are carried out to verify the performance of the proposed control laws. Results of the proposed coordinated control strategy show that noticeable improvements in terms of vehicle jerk and friction energy loss are achieved compared with an optimal control scheme only for the shifting motor as the input

    Computational prediction of ideal strength for a material

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    The ideal strength is crucial for predicting material behavior under extreme conditions, which can provide insights into material limits, guide design and engineer for enhanced performance and durability. In this work, we present a method within an allows for the estimation of tensile, shear, and indentation strengths in any crystallographic direction or plane. We have examined the strain-stress relationships of several well-known structures and compared our findings with previous work, demonstrating the effectiveness of our approach. Moreover, we performed extensive investigations into the indentation strength of hexagonal WC, \b{eta}-SiC, and MgAl2O4l_2O_4. The current study uncovers the modes of structural deformation and the underlying atomistic mechanisms. The insights gained from this study have significant implications for the further exploration and design of superhard materials.Comment: 15 pages,7 figure

    Eolian dust dispersal patterns since the last glacial period in eastern Central Asia: insights from a loess-paleosol sequence in the Ili Basin

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    The extensive loess deposits of the Eurasian midlatitudes provide important terrestrial archives of Quaternary climatic change. As yet, however, loess records in Central Asia are poorly understood. Here we investigate the grain size and magnetic characteristics of loess from the Nilka (NLK) section in the Ili Basin of eastern Central Asia. Weak pedogenesis suggested by frequency-dependent magnetic susceptibility (chi fd%) and magnetic susceptibility (MS) peaks in primary loess suggest that MS is more strongly influenced by allogenetic magnetic minerals than pedogenesis, and may therefore be used to indicate wind strength. This is supported by the close correlation between variations in MS and proportions of the sand-sized fraction. To further explore the temporal variability in dust transport patterns, we identified three grain size end-members (EM1, mode size 47.5 mu m; EM2, 33.6 mu m; EM3, 18.9 mu m) which represent distinct aerodynamic environments. EM1 and EM2 are inferred to represent grain size fractions transported from proximal sources in short-term, near-surface suspension during dust outbreaks. EM3 appears to represent a continuous background dust fraction under non-dust storm conditions. Of the three end-members, EM1 is most likely the most sensitive recorder of wind strength. We compare our EM1 proportions with mean grain size from the Jingyuan section in the Chinese loess plateau, and assess these in the context of modern and Holocene climate data. Our research suggests that the Siberian High pressure system is the dominant influence on wind dynamics, resulting in loess deposition in the eastern Ili Basin. Six millennial-scale cooling (Heinrich) events can be identified in the NLK loess records. Our grain size data support the hypothesis that the Siberian High acts as teleconnection between the climatic systems of the North Atlantic and East Asia in the high northern latitudes, but not for the mid-latitude westerlies

    Effect of angiotensin receptor neprilysin inhibitors on left atrial remodeling and prognosis in heart failure

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    Aims The angiotensin receptor–neprilysin inhibitor (ARNI), sacubitril/valsartan, confers additional protective effects compared with angiotensin-converting enzyme inhibitors/angiotensin II receptor blockers (ACEIs/ARBs) in terms of reversed left ventricular (LV) remodelling and improves the prognosis of patients with heart failure (HF). However, few studies have examined the effects of ARNI on the left atrium. Accordingly, this study compared the effects of ARNI and ACEI/ARB on left atrial (LA) remodelling in heart failure with reduced ejection fraction (HFrEF). Methods and results This was a single-centre retrospective study of patients with HFrEF hospitalized at the First Affiliated Hospital of Dalian Medical University between 26 February 2016 and 8 July 2020. Patients were classified into ARNI and ACEI/ARB groups and further subgroups based on the left atrial volume index (LAVI): mildly abnormal (29 mL/m2 ≀ LAVI < 34 mL/m2), moderately abnormal (34 mL/m2 ≀ LAVI < 40 mL/m2), and severely abnormal (LAVI ≄ 40 mL/m2). The primary endpoint was changes in LA parameters by echocardiography. The secondary endpoint was all-cause mortality. A total of 336 patients (mean age: 64.11 ± 12.86, 30.06% female) were included. Except those lost to follow-up, 274 HFrEF patients remained, with 144 cases in the ARNI group and 130 cases in the ACEI/ARB group. Greater reductions from baseline were seen with ARNI in LA diameter (LAD) (P = 0.013, t-test), superior and LA superior–inferior diameter (LASID) (P < 0.0001), LA transverse diameter (LATD) (P < 0.0001), LA volume (LAV) (P < 0.0001), LAVI (P < 0.0001), and LA sphericity index (LASI) (P < 0.0001). Over a mean follow-up of 19.40 months, 97 patients (67.3%) in the ARNI group and 29 patients (22.3%) in the ACEI/ARB group showed LA reverse remodelling (LARR). Kaplan–Meier analysis showed significantly lower overall mortality in the ARNI group compared with the ACEI/ARB group (P = 0.048, log-rank test). The mildly abnormal LAVI group of ARNI patients showed a reduction in mortality compared with ACEI/ARB patients (P = 0.044). However, no significant difference was observed for the moderately abnormal (P = 0.571) or severely abnormal LAVI groups (P = 0.609), suggesting that early initiation of ARNI was associated with a better prognosis. Conclusions In this proof-of-concept study, ARNI use showed greater effects on LARR and was associated with a better prognosis compared with ACEI/ARB use in HFrEF. Early initiation of ARNI in the HF disease process may produce greater benefit, but this needs to be confirmed in future studies

    Application and Curative Effect of Micro-implant Anchorage in Orthodontics

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    Purpose: To explore and analyze the curative effects of micro - implant anchorages in orthodontics.Methods: A retrospective analysis of 65 patients undergoing orthodontic treatment in Department of Stomatology, Binzhou Medical University Hospital, Shandong, China was carried out. Thirty four cases in the treatment group were treated with a micro-implant as the anchorage, while 31 cases of the control group were treated with a palatal bar and facebow as the anchorage, and the curative results of the two groups were then compared.Results: After a 13-month treatment, both anchorages were clinically effective, but the micro-implant anchorage showed higher efficacy. Measurement indices for the test group, including sella-nasion - A point (SNA) angle (- 1.88 ± 0.71), sella-nasion-B point (SNB) angle (1.39 ± 0.42), A point - nasion - B point (ANB) angle (- 2.40 ± 0.83), upper central incisor - lower central incisor (U1 - L1) angle (25.79 ± 5.90), upper central incisor - sella - nasion (U1 - SN) angle (- 10.13 ± 3.68), lower central incisor – mandibular plane (L1 - MP) angle (- 4.22 ± 0.45), upper central incisor - nasion - A point (U1 - NA) angle (- 1.32 ± 1.35) and lower central incisor - nasion - B point (L1 - NB) angle (- 1.32 ± 1.35) of the test group were significantly different those of the control group Overbite (OB), overjet (OJ), intercanine width and the width of the first molars of treatment and control groups were also remarkably). Moreover, micro-implant was observed to be more stable during treatment.Conclusion: Compared with traditional anchorages, micro-implants possess the advantages of slighter trauma, simpler operation, more reliable curative effect and high stability.Keywords: Micro-implant anchorage, Orthodontics, Facebow anchorage, Oral medicine, Clinical efficac

    Explaining variations in semiconductor catch-up strategies in China, Korea, Malaysia and Taiwan

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    Presented at the GLOBELICS 6th International Conference 2008 22-24 September, Mexico City, Mexico
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