Dynamic hardness of rock materials under strong impact loading

2020 ◽  
Vol 140 ◽  
pp. 103555
Author(s):  
Tianhan Xu ◽  
Mingyang Wang ◽  
Jie Li
Keyword(s):  
Impact Loading ◽  
Strong Impact ◽  
Dynamic Hardness ◽  
Rock Materials

Finite Element Analysis of Dynamic Responses of Plain Concrete Pavements Under Strong Impact Loading

2013 ◽  
Vol 838-841 ◽  
pp. 23-29
Author(s):  
Xiao He Zhou ◽  
Da Wei Ma ◽  
Gui Gao Le
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Failure Mode ◽  
Impact Loading ◽  
Shear Failure ◽  
Plain Concrete ◽  
Dynamic Responses ◽  
Crack Model ◽  
Strong Impact ◽  
Concrete Pavements

Plain concrete pavements under heavy impact loading will induce flexure, crack and direct shear failure. To obtain dynamic response and failure mode of plain concrete pavement under heavy impact loading, the concrete brittle crack model is adopted and finite element model of plain concrete pavements is established; the dynamic response and failure mode under heavy impact loading in different loading points and different loading times are studied; the production, stretching and extension of cracking are researched; which is a powerful reference for practical engineering application.

Trends in Periprosthetic Knee Infection and Associated Costs: A Population-Based Study Using National Data

2020 ◽  
Author(s):  
Robert Brochin ◽  
Jashvant Poeran ◽  
Khushdeep S. Vig ◽  
Aakash Keswani ◽  
Nicole Zubizarreta ◽  
...  
Keyword(s):  
Total Knee Arthroplasty ◽  
Length Of Stay ◽  
Knee Arthroplasty ◽  
Trend Test ◽  
Strong Impact ◽  
Hospitalization Costs ◽  
Teaching Status ◽  
Increasing Trend ◽  
Total Knee ◽  
Increasing Trends

AbstractGiven increasing demand for primary knee arthroplasties, revision surgery is also expected to increase, with periprosthetic joint infection (PJI) a main driver of costs. Recent data on national trends is lacking. We aimed to assess trends in PJI in total knee arthroplasty revisions and hospitalization costs. From the National Inpatient Sample (2003–2016), we extracted data on total knee arthroplasty revisions (n = 782,449). We assessed trends in PJI prevalence and (inflation-adjusted) hospitalization costs (total as well as per-day costs) for all revisions and stratified by hospital teaching status (rural/urban by teaching status), hospital bed size (≤299, 300–499, and ≥500 beds), and hospital region (Northeast, Midwest, South, and West). The Cochran–Armitage trend test (PJI prevalence) and linear regression determined significance of trends. PJI prevalence overall was 25.5% (n = 199,818) with a minor increasing trend: 25.3% (n = 7,828) in 2003 to 28.9% (n = 19,275) in 2016; p < 0.0001. Median total hospitalization costs for PJI decreased slightly ($23,247 in 2003–$20,273 in 2016; p < 0.0001) while median per-day costs slightly increased ($3,452 in 2003–$3,727 in 2016; p < 0.0001), likely as a function of decreasing length of stay. With small differences between hospitals, the lowest and highest PJI prevalences were seen in small (≤299 beds; 22.9%) and urban teaching hospitals (27.3%), respectively. In stratification analyses, an increasing trend in PJI prevalence was particularly seen in larger (≥500 beds) hospitals (24.4% in 2003–30.7% in 2016; p < 0.0001), while a decreasing trend was seen in small-sized hospitals. Overall, PJI in knee arthroplasty revisions appears to be slightly increasing. Moreover, increasing trends in large hospitals and decreasing trends in small-sized hospitals suggest a shift in patients from small to large volume hospitals. Decreasing trends in total costs, alongside increasing trends in per-day costs, suggest a strong impact of length of stay trends and a more efficient approach to PJI over the years (in terms of shorter length of stay).

Aerodynamic Shape Influence and Optimum Thickness Distribution Analysis of Perceptive Wind Turbine Blade

2018 ◽  
Vol 7 (3) ◽  
pp. 1
Author(s):  
J. V. Muruga Lal Jeyan ◽  
Akhila Rupesh ◽  
Jency Lal
Keyword(s):  
Wind Energy ◽  
Wind Turbine ◽  
Thickness Distribution ◽  
Turbine Blades ◽  
Reduced Form ◽  
Load Factor ◽  
Strong Impact ◽  
Theory Approach ◽  
Distribution Analysis ◽  
Optimum Thickness

The aerodynamic module combines the three-dimensional nonlinear lifting surface theory approach, which provides the effective propagated incident velocity and angle of attack at the blade section separately, and a two-dimensional panel method for steady axisymmetric and non-symmetric flow has to be involved to obtain the 3D pressure and velocity distribution on the wind mill model blade. Wind mill and turbines have become an economically competitive form of efficiency and renewable work generation. In the abroad analytical studies, the wind turbine blades to be the target of technological improvements by the use of highly possible systematic , aerodynamic and design, material analysis, fabrication and testing. Wind energy is a peculiar form of reduced form of density source of power. To make wind power feasible, it is important to optimize the efficiency of converting wind energy into productivity source. Among the different aspects involved, rotor aerodynamics is a key determinant for achieving this goal. There is a tradeoff between thin airfoil and structural efficiency. Both of which have a strong impact on the cost of work generated. Hence the design and analysis process for optimum design requires determining the load factor, pressure and velocity impact and optimum thickness distribution by finding the effect of blade shape by varying thickness on the basis of both the aerodynamic output and the structural weight.

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