A flexure-based displacement reducer capable of achieving very large reduction ratio

2022 ◽  
Vol 170 ◽  
pp. 104658
Author(s):  
Houqi Wu ◽  
Guimin Chen
Keyword(s):  
Reduction Ratio ◽  
Large Reduction

A Flexure-Based Displacement Reducer Capable of Achieving Very Large Reduction Ratio

2021 ◽  
Author(s):  
Houqi Wu ◽  
Guimin Chen
Keyword(s):  
Element Model ◽  
Reduction Ratio ◽  
Large Reduction ◽  
Magnetostrictive Actuators ◽  
Limited Output ◽  
Bridge Type ◽  
The Difference ◽  
Kinetostatic Model ◽  
The Finite Element Model ◽  
Very High

Abstract Piezo actuators and giant magnetostrictive actuators are widely used in micropositioning and micromanipulating devices. Due to their limited output stroke, flexure-based displacement amplifiers are usually employed to meet the large-stroke requirements. Although amplifiers increase the stroke of the actuators, they lower the resolution of the motion, making it difficult to obtain positioning of nanometer or even sub-nanometer resolution. To achive very high resolution from these actuators, a compact flexure-based displacement reducer, which shows the capability of obtaining very large reduction ratio, is proposed in this work. The reducer contains two bridge-type flexure mechanisms connected in a way that the output of the reducer equals the difference of the outputs of the two mechanisms (thus is called the bridge-type differential displacement reducer). If the two bridge-type flexure mechanisms are identical, no matter how large the input is, the output will always be 0, indicating an infinite reduction ratio theoretically. Therefore, introducing a slight difference between the two mechanisms can yield a very large reduction ratio. A kinetostatic model for the reducer is developed, base on which a reducer exhibiting a reduction ratio of 100 is designed and prototyped. The results of the kinetostatic model, the finite element model and the experiment agree well with each other, validating the effectiveness of the proposed reducer and the correctness of kinetostatic model.

Weak Beam Imaging and Diffraction Studies of Stacking Faults in Silicon

1976 ◽  
Vol 34 ◽  
pp. 590-591
Author(s):  
T. Y. Tan ◽  
W. K. Tice
Keyword(s):  
Fast Neutron ◽  
Rapid Determination ◽  
Stacking Faults ◽  
Imaging Method ◽  
Large Reduction ◽  
Dislocation Loops ◽  
Fringe Spacing ◽  
Weak Beam ◽  
Kinematical Theory

In studying ion implanted semiconductors and fast neutron irradiated metals, the need for characterizing small dislocation loops having diameters of a few hundred angstrom units usually arises. The weak beam imaging method is a powerful technique for analyzing these loops. Because of the large reduction in stacking fault (SF) fringe spacing at large sg, this method allows for a rapid determination of whether the loop is faulted, and, hence, whether it is a perfect or a Frank partial loop. This method was first used by Bicknell to image small faulted loops in boron implanted silicon. He explained the fringe spacing by kinematical theory, i.e., ≃l/(Sg) in the fault fringe in depth oscillation. The fault image contrast formation mechanism is, however, really more complicated.

Teledentistry and mHealth for Promotion and Prevention of Oral Health: A Systematic Review and Meta-analysis

2021 ◽  
pp. 002203452110038
Author(s):  
C.E. Fernández ◽  
C.A. Maturana ◽  
S.I. Coloma ◽  
A. Carrasco-Labra ◽  
R.A. Giacaman
Keyword(s):  
Systematic Review ◽  
Oral Health ◽  
Randomized Controlled Trials ◽  
Communication Systems ◽  
Text Messages ◽  
Mean Difference ◽  
Controlled Trials ◽  
Large Reduction ◽  
Randomized Controlled ◽  
Standardized Mean Difference

The dental profession has experienced a dramatic acceleration in the use of communication systems and information-based technologies over recent years, originating new paradigms for the prevention and promotion of oral health. The purpose of this systematic review was to determine the effect of teledentistry-based (telematic) strategies, reported in randomized controlled trials and quasi-randomized trials, with a focus on oral health prevention and promotion–related outcomes in patients of all ages. We searched Medline via PubMed, SCOPUS, and Web of Science from inception until August 2020, regardless of the language of publication. We selected studies for inclusion and conducted data extraction, assessed risk of bias (Cochrane tool), and evaluated the certainty of the evidence (GRADE approach) in duplicate and independently. Out of 898 potentially eligible references, we selected 43 for full-text screening, of which 19 studies proved eligible: 18 randomized controlled trials and 1 quasi-randomized study. Virtual interventions were mostly asynchronous via apps ( n = 9), text messages ( n = 9), or computer-aided learning ( n = 1). The use of teledentistry as compared with conventional strategies may result in a large reduction in the plaque index (standardized mean difference, −1.18; 95% CI, −1.54 to −0.82; I2 = 92%; low certainty) and will likely result in a large reduction in the gingival index (standardized mean difference, −2.17; 95% CI, −3.15 to −1.19; I2 = 97%; moderate certainty) and in the incidence of white spot lesions (risk ratio, 0.48; 95% CI, 0.35 to 0.66; I2 = 0%; moderate certainty), with an increased effect over time. Evidence suggests that teledentistry, particularly mHealth (messages and apps), is a promising clinical tool for preventing and promoting oral health, especially under the accelerated virtualization of dentistry. Future studies should include a broader spectrum of the population, including adults and elders, to better inform policy and implementation of teledentistry (PROSPERO: CRD42020192685).

Impact of cardiovascular health status on the association between changes in physical activity and major cardiovascular events and mortality among 88,320 adults: outcomes of the Lifelines Cohort Study

2021 ◽  
Vol 28 (Supplement_1) ◽  
Author(s):  
EA Bakker ◽  
DC Lee ◽  
MTE Hopman ◽  
DHJ Thijssen ◽  
TMH Eijsvogels
Keyword(s):  
Cardiovascular Events ◽  
Cardiovascular Health ◽  
Large Reduction ◽  
Healthy Individuals ◽  
Moderate Improvement ◽  
Moderate Reduction ◽  
Lower Baseline ◽  
All Cause Mortality ◽  
The Impact ◽  
Large Improvement

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): The Lifelines Biobank initiative received funding from the Dutch Ministry of Health, Welfare and Sport, the Dutch Ministry of Economic Affairs, the University Medical Center Groningen [UMCG], University Groningen and the Northern Provinces of the Netherlands. The work of T.M.H.E is supported by the Netherlands Heart Foundation [Senior E-Dekker grant #2017T051]. Background. Regular physical activity (PA) improves health. Many observational studies investigated the association between PA and health at a single time-point, but PA might change over time. Purpose. To examine the association between change in PA and major adverse cardiovascular events (MACE) and all-cause mortality, and to investigate the impact of cardiovascular health status at baseline on these outcomes. Methods. This study used data from the Lifelines Cohort Study (N = 88,320). Self-reported PA volumes were presented as Metabolic Equivalent of Task (MET) min/week. Change in PA was calculated by subtracting MET-min/week at the first assessment from the second assessment (median interval: 4 yrs), and 5 groups were created; large reduction (< -1500), moderate reduction (-1500 to -250), no change (-250 to 250), moderate improvement (-250 to 250) and large improvement (>1500). The outcome was a combination of MACE and all-cause mortality. Results. During a median follow-up of 7 years, 667 events occurred among healthy individuals (43 ± 12 yrs, 1% of 69,818) and 599 in individuals with CVRF (55 ± 11 yrs, 3% of 18,502). Adjusted for confounders and baseline PA, healthy individuals with a large reduction in PA had a greater risk of incident MACE and mortality (Table). In CVRF, moderate to large improvements in PA were associated with reductions in adverse outcomes. Risk estimates became stronger in individuals with lower baseline PA (<2000 MET-min/week), Table). Conclusions. Maintaining PA in healthy individuals and increasing PA in individuals with CVRF over time is important to prevent MACE and mortality. The impact of changes in PA was stronger for individuals with lower baseline PA. Table. Change of PA, MACE and mortality. Changes in PA Healthy CVRF Large reduction 1.40 [1.02;1.93] 1.27 [0.95;1.70] Moderate reduction 1.22 [0.89;1.68] 0.97 [0.72;1.30] No changes Ref Ref Moderate improvement 1.04 [0.74;1.44] 0.65 [0.47;0.91] Large improvement 0.96 [0.71;1.31] 0.69 [0.51; 0.94] Individuals with lower baseline PA Large reduction 2.24 [0.96;5.21] 2.85 [1.44;5.63] Moderate reduction 1.77 [1.10;2.84] 1.33 [0.89;1.98] No changes Ref Ref Moderate improvement 1.16 [0.73;1.83] 0.49 [0.31;0.76] Large improvement 0.77 [0.48;1.23] 0.58 [0.39;0.86]

Analysis of Precipitation of NbC in Low Reduction Ratio Conditions

2021 ◽  
Author(s):  
Mei-Ling Liu ◽  
Guo-Hui Zhu ◽  
Heng-Qiang Tang ◽  
Xiao-Ping Ma ◽  
S. V. Subramanian
Keyword(s):  
Reduction Ratio

The Engineering Design of Helical Spur Gear Transmission with Single Gear Pair for Electric Scooter

2015 ◽  
Vol 764-765 ◽  
pp. 374-378 ◽  
Author(s):  
Long Chang Hsieh ◽  
Tzu Hsia Chen ◽  
Hsiu Chen Tang
Keyword(s):  
Engineering Design ◽  
Spur Gear ◽  
Gear Transmission ◽  
Reduction Ratio ◽  
Gear Pair ◽  
Engineering Drawing ◽  
Electric Scooter ◽  
High Reduction ◽  
Cost Of Production ◽  
The Cost

Traditionally, the reduction ratio of a spur gear pair is limited to 4 ~ 7. For a spur gear transmission with reduction ratio more than 7, it is necessary to have more than two gear pairs. Consider the cost of production, this paper proposes a helical spur gear reducer with one gear pair having reduction ratio 19.25 to substitute the gear reducer with two gear pairs. Based on the involute theorem, the gear data of helical spur gear pair is obtained. According to the gear data, its corresponding engineering drawing is accomplished. This manuscript verify that one spur gear pair also can have high reduction ratio (20 ~ 30).

Effects of Cold-Rolling Reduction on Microstructure and Mechanical Properties of Ti50Zr30Nb10Ta10 Alloy

2016 ◽  
Vol 849 ◽  
pp. 376-381
Author(s):  
Ming Long Li ◽  
Yu Jie Geng ◽  
Chen Chen ◽  
Shu Jie Pang ◽  
Tao Zhang
Keyword(s):  
Mechanical Properties ◽  
Titanium Alloy ◽  
Plastic Strain ◽  
Cold Rolling ◽  
Reduction Ratio ◽  
High Fracture ◽  
Dendrite Structure ◽  
Microstructure And Mechanical Properties ◽  
Cold Rolling Reduction ◽  
Cold Rolled

The effects of cold-rolling with different reduction ratios of 70%-90% on the microstructure and mechanical properties of Ti50Zr30Nb10Ta10 alloy were investigated. It was found that the β-Ti phase in this alloy was stable under cold-rolling. With the increase in reduction ratio from 70% to 90%, the microstructure of the alloys evolved from deformed dendrite structure to fiber-like structure. The alloy cold-rolled with the reduction ratio of 70% exhibited optimum mechanical properties of combined high fracture strength of 1012 MPa and plastic strain of 10.1%, which are closely correlated with the dendrite structure of the alloy. It is indicated that the proper cold-rolling is an effective way to improve the mechanical properties of the titanium alloy.

Sign in / Sign up

Export Citation Format

Share Document