scholarly journals Estimation of C∗-Integral for Central Cracked Plate Under Biaxial Loading

2020 ◽  
Vol 12 (07) ◽  
pp. 2050079
Author(s):  
Yanwei Dai ◽  
Fei Qin ◽  
Yinghua Liu ◽  
Weizhe Feng ◽  
Guian Qian
Keyword(s):  
Loading Condition ◽  
Biaxial Loading ◽  
Classical Method ◽  
Creep Crack ◽  
Cracked Plate ◽  
Reference Stress ◽  
Creep Time ◽  
Relationship Of ◽  
The Relationship ◽  
Better Than

The reference stress method (RSM) is a classical method to estimate [Formula: see text]-integral of creep crack. An extended reference stress method (ERSM) is given for the central cracked plate (CCP) under biaxial loading in this paper. The applicability and verification for the proposed ERSM is given. The study finds that the solutions with the proposed ERSM agree better than those of RSM under biaxial loading condition. A theoretical form to predict the relationship of [Formula: see text]-integral between biaxial loading and uniaxial loading is discussed. Relation between [Formula: see text]-integral and creep time under biaxial loading is validated and discussed.

scholarly journals Hourly Relationship between Reference Evapotranspiration and Shoot Shrinkage in Walnut Trees and Pomegranate under Deficit Irrigation

Plants ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 31
Author(s):  
Eduardo Salgado ◽  
Nieggiorba Livellara ◽  
Esteban Chaigneau ◽  
Fernando Varas ◽  
Italo F. Cuneo
Keyword(s):  
Water Potential ◽  
Deficit Irrigation ◽  
Reference Evapotranspiration ◽  
The Novel ◽  
The Past ◽  
Slope Analysis ◽  
Daily Scale ◽  
Relationship Of ◽  
The Relationship ◽  
Better Than

Diameter fluctuations of branches, shoots, or fruits are related to plant transpiration and water potential. In the past, several models have related dendrometric variables and evapotranspiration on a daily scale. However, trunk–branch shrinkage occurs only between dawn and midday, while evapotranspiration occurs most of the day from sunrise to sunset. Previous models have failed to incorporate this key fact. The objective of the present study was to assess the relationship of hourly daily shrinkage (HDS) between dawn and the next 4 h to the hourly reference evapotranspiration (EToh) of the same period in walnut trees and pomegranate plants under different irrigation regimes. Our data show that the relationship between EToh and HDS is much better than several previous models that included maximum daily shrinkage (MDS) and reference evapotranspiration (ETo). The novel slope analysis of the relationship between HDS versus time used here corresponds to the velocity at which the HDS occurs, which depends on the ETo intensity at that moment. This new method of analyzing this type of data calls for a revision of these models and sets a new baseline for future analysis.

scholarly journals Understory vegetation relationships with soil element contents in a northern boreal forest ecosystem near a phosphate massif

2019 ◽  
Author(s):  
Laura Matkala ◽  
Maija Salemaa ◽  
Jaana Bäck
Keyword(s):  
Leaf Litter ◽  
Understory Vegetation ◽  
Forest Understory ◽  
Nutrient Contents ◽  
Humus Layer ◽  
P Content ◽  
Relationship Of ◽  
The Relationship ◽  
Total P ◽  
Better Than

Abstract. We studied the relationship of forest understory vegetation with nutrient contents of soil and tree leaves near Sokli phosphate ore in northern Finland, where the soil contains naturally high variation in phosphorus (P) contents. At most study plots boreal dwarf shrubs, bryophytes and lichen formed a dense mat under a mixture of sparsely growing Pinus sylvestris, Picea abies and Betula pubescens. However, some plots were dominated by B. pubescens and had a higher variety and number of forbs and grasses in the understory. The total P content in the soil humus layer explained the abundance and species composition of the vegetation slightly better than the total nitrogen content. The spatial variation in contents of soil elements was high both between and within plots, emphasizing the heterogeneity of soil. High contents of P in the humus layer (max. 2600 mg kg−1) were measured from the birch-dominated plots. As the P contents of birch leaves and leaf litter were also rather high (2580 mg kg−1 and 1280 mg kg−1, respectively), this may imply that the leaf litter of birch forms an important source of P to the soil.

Creep Analysis and Constraint Effect in a Center-Cracked Plate Under Biaxial Loading

2014 ◽  
Author(s):  
Zhongxian Wang ◽  
Yan-qing Zhang ◽  
Poh-Sang Lam ◽  
Yuh J. Chao
Keyword(s):  
Biaxial Loading ◽  
Crack Tip ◽  
Pressure Vessels ◽  
Contour Integral ◽  
Small Scale ◽  
Crack Tip Field ◽  
Cracked Plate ◽  
Creep Analysis ◽  
Creep Time ◽  
Crack Tip Constraint

Typical pressure vessels are subject to biaxial loading. Creep analysis was conducted with two-dimensional finite element method for a center-cracked plate under a range of biaxial loading ratios (λ = −1, 0, and 0.5). The effects of crack size and the biaxial loading ratio on the crack tip field are reported. In addition, based on a two-parameter fracture theory, C(t)−A2(t), where C is a contour integral and is path-independent when the steady state creep is reached (denoted by C*), and A2 is a time dependent crack tip constraint parameter. The crack tip stress field calculated from the C(t)−A2(t) theory is shown to be more accurate than the Hutchinson–Rice–Rosengren (HRR) singularity solution, especially in the case of λ = 0.5. The loading level appears to have little effects on the constraint parameter A2(t). As creep time increases, the creep zone (based on the equivalent creep strain) increases rapidly but the yield zone (with respect to a reference stress) decreases. Meanwhile, the crack tip constraint is increasing with creep time, particularly for the small cracks. It was also found that the normalized relationship between the contour integral C(t)/C* and the creep time t/tT (where tT is the characteristic time for transition from small-scale creep to extensive creep) is insensitive to the biaxial loading. Therefore, the relationship previously provided for uniaxial loading can be used for biaxial loading.

The Research about the Vibroacoustic Characteristics of the Surface Cracked Plate

2014 ◽  
Vol 602-605 ◽  
pp. 303-310
Author(s):  
Gui Jie Liu ◽  
Meng Meng Li ◽  
Yu Qian Wang ◽  
Yu Zhan Yuan
Keyword(s):  
Theoretical Formula ◽  
Spring Model ◽  
Cracked Plate ◽  
Structural Intensity ◽  
Line Spring Model ◽  
Simulation Results ◽  
Shell Finite Element ◽  
Vibration Parameters ◽  
Relationship Of ◽  
The Relationship

Vibration characteristics of surface cracked plate are studied from the view of structural intensity .Line-spring model of the surface crack is put forward based on fracture mechanics. The relationship of the additional angle and displacement with the crack parameters is derived. The concept of additional structural intensity is presented and the additional structural intensity’s expression of shell finite element is deduced. The change regulars between structural intensity and vibration parameters with crack’s parameters are concluded by using ANSYS and MATLAB software, the simulation results are matched with the trend of theoretical formula.

scholarly journals STUDY ON TEMPERATURE FIELD OF ASYMMETRIC LARGE-SPAN ARCH SHEDS UNDER LOW-TEMPERATURE ENVIRONMENT

2020 ◽  
pp. 239-248
Author(s):  
Kai Zhou ◽  
Zhiwei Meng ◽  
Jialin Hou ◽  
Min Wei ◽  
Tianguo Jin ◽  
...  
Keyword(s):  
Temperature Distribution ◽  
Wind Speed ◽  
Low Temperature ◽  
Storage Capacity ◽  
Heat Storage ◽  
Large Span ◽  
Distribution Uniformity ◽  
Relationship Of ◽  
The Relationship ◽  
Better Than

In order to improve the effective sunshine time, heat storage capacity and temperature distribution uniformity of traditional arch shed under low temperature, this paper designed a large-span arch shed which has larger sunny side span and east-west orientation. According to the numerical and measured data, it is concluded that the heat storage capacity and temperature distribution of asymmetrical arch shed are better than those of symmetrical arch shed within a certain range of the ratio between sunny and shaded side. After that, ten different asymmetric arch sheds were designed. It is concluded that the structure of 11+9 m along north-south direction has the best heat storage capacity. Besides that, the analysis of outside wind speed and opening size of top vent were carried out. It is found that the outside wind and top vent can effectively promote convection and exchange of the air, and then achieve the purpose of reducing the temperature. At the end of this paper, in order to identify the relationship of temperature with the structure of arch shed, outside wind speed, and opening size of top vent, a mathematical model was built based on response surface methodology, which would provide theoretical guidance for the design of arch sheds.

scholarly journals Analyzing the spatial-temporal influence of built environment on taxi ridership

2020 ◽  
Vol 66 (4) ◽  
pp. 1-9
Author(s):  
Que Yuhua
Keyword(s):  
Built Environment ◽  
Regression Models ◽  
Transportation System ◽  
Critical Dimensions ◽  
Taxi Service ◽  
Global Regression ◽  
Temporal Influence ◽  
Relationship Of ◽  
The Relationship ◽  
Better Than

Taxi is an important component in urban transportation system, which covers wide area and maintains 24h available. Exploring the relationship of taxi and built environment is very important to manage taxi service and improve transportation system. The issue is addressed by capturing the influence of built environment on taxi ridership considering spatial and temporal non-stationarities. The grid cells are developed as analysis units and the global regression model is adopted for preliminary exploring. Then the GWR are implemented considering spatial heterogeneity and the GTWR is used to analyze the spatiotemporal influence of built environment on taxi ridership. An empirical study conducted in Hong Kong Island using one-week taxi’s GPS data demonstrates the effectiveness of the regression models. It’s verified that GWR performs better than OLS, and GTWR outperforms the rest two regression models, indicating both time and space are critical dimensions.

MANEUVERING OF BIOMIMETIC FISH BY INTEGRATING A BUOYANCY BODY WITH MODULAR UNDULATING FINS

2007 ◽  
Vol 04 (04) ◽  
pp. 671-695 ◽  
Author(s):  
K. H. LOW
Keyword(s):  
Field Trials ◽  
Biomimetic Robots ◽  
Laboratory Tank ◽  
The Individual ◽  
Relationship Of ◽  
Phase Angles ◽  
The Relationship ◽  
Undulating Fin ◽  
Better Than ◽  
Buoyancy Control

Biomimetic robots borrow their senses and structure from animals, such as insects, fishes, and human. Development of underwater vehicles is one of the areas where biomimetic robots can potentially perform better than conventional robots. In this paper, an undulating fin mechanism has been developed and used as the propulsion system of fish in various fin types. The layout and workspace of the modular fin segments are considered and analyzed. The relationship of the individual fin segment and phase angles with the overall fin trajectory is also discussed. A gymnotiform knifefish robot, as an example, has been developed to demonstrate the design methodology and prototype performance. The maneuvering and the buoyancy control can be achieved by the integration of a buoyancy tank with the undulating fin. Experiments were conducted in the laboratory tank and the variation of velocity with respect to several swimming parameters was analyzed. Field trials have also been conducted in an outdoor pool to demonstrate the swimming capability of the knifefish robot and its buoyancy performance in 4 m deep water.

Relationship of Preservice Music Teachers’ Primary Instrument Background and Teaching Effectiveness in Brass and Woodwind Techniques Classes

2017 ◽  
Vol 27 (3) ◽  
pp. 38-50 ◽  
Author(s):  
Sean R. Powell ◽  
Molly A. Weaver ◽  
Robin K. Henson
Keyword(s):  
Teaching Effectiveness ◽  
Music Teachers ◽  
Music Teacher ◽  
Music Teacher Education ◽  
Brass Players ◽  
Study Participants ◽  
Relationship Of ◽  
The Relationship ◽  
Better Than ◽  
Primary Instrument

The purpose of this study was to examine the relationship between preservice music teachers’ primary instrument background and their teaching effectiveness in brass and woodwind techniques classes. Study participants ( N = 135) were preservice music teachers enrolled in secondary instrument techniques courses (brass and woodwinds) from fall 2011 through spring 2015 in three universities. Participants taught a 10-minute video recorded lesson to a beginning-level university student on a brass or woodwind instrument at the end of the semester. All videos were subsequently assessed by two researchers using a researcher-designed rubric. The results of analyses of variance showed that brass-teaching scores tended to be higher than woodwind-teaching scores for all groups. Brass players taught brass more effectively than woodwind players, and woodwind players taught woodwinds better than brass players. Brass and woodwind players scored higher than percussionists, vocalists, pianists, and string players in both brass and woodwind teaching. Implications for music teacher education are discussed.

Development and Validation of a Music Education Competency Test

1981 ◽  
Vol 29 (1) ◽  
pp. 5-10 ◽  
Author(s):  
Herschel V. Beazley
Keyword(s):  
Music Education ◽  
Transfer Students ◽  
Teacher Rating ◽  
University Of Illinois ◽  
Course Grades ◽  
The University ◽  
Development And Validation ◽  
Relationship Of ◽  
The Relationship ◽  
Better Than

The purpose of the study was to develop and validate a competency test in music education. The resulting Music Education Competency Test (MECT), pilot form, provided information on a student' s proficiency in selected singing, conducting, key board, and rehearsal skills. Three validity studies were conducted in order to obtain evidence on the relationship of MECT scores to (1) the student' s course grades, academic status, and teacher rating; (2) students entering as freshmen as opposed to those entering as transfer students; and (3) students with piano as the principal instrument as opposed to voice or orchestral instruments. One hundred and twenty-five undergraduates at the University of Illinois took one of the test forms. Results indicated that: (1) seniors score better than freshmen on the singing and conducting subtests; (2) instrumentalists score better than vocalists on the conducting subtest; and (3) students' scores on the conducting and diagnostic rehearsal skills subtests correlate significantly with instructors' ratings in corresponding areas.

scholarly journals A Simplified SSY Estimate Method to Determine EPFM Constraint Parameter for Sensor Design

Sensors ◽  
2019 ◽  
Vol 19 (3) ◽  
pp. 717
Author(s):  
Ping Ding ◽  
Xin Wang
Keyword(s):  
Loading Condition ◽  
Biaxial Loading ◽  
External Loading ◽  
Small Scale ◽  
Cracked Plate ◽  
T Stress ◽  
Estimate Method ◽  
Parameter Values ◽  
Parameter Approach ◽  
Two Parameter

To implement a sensor structure analysis and design (as well as other engineering applications), a two-parameter approach using elastic–plastic fracture mechanics (EPFM) could be applied to analyze a structure more accurately than a one-parameter approach, especially for structures with low crack constraint. The application of the J-A two-parameter approach on sensors and other structures depends on the obtainment of a constraint parameter A. To conveniently and effectively obtain the A parameter values, the authors have developed a T-stress-based estimate method under a small-scale yielding (SSY) condition. Under a uniaxial external loading condition, a simplified format of the T-stress-based estimate has been proposed by the authors to obtain the parameter A much more conveniently and effectively. Generally, sensors and other practical engineering structures endure biaxial external loading instead of the uniaxial one. In the current work, the simplified formation of the estimate method is extended to a biaxial loading condition. By comparing the estimated A parameter values with their numerical solutions from a finite element analysis (FEA) results, the extension of the simplified formation of T-stress-based estimate method to biaxial loading was discussed and validated. The comparison procedure was completed using a wide variety of materials and geometrical properties on three types of specimens: single edge cracked plate (SECP), center cracked plate (CCP), and double edge cracked plate (DECP).

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