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Weed seed burial as affected by mouldboard design parameters, ploughing depth and speed: DEM simulations and experimental validation

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BIOSYSTEMS ENGINEERING 2022年第0期216卷 79-92页

作者： Azimi-Nejadian, Hadi Karparvarfard, Seyed Hossein Naderi-Boldaji, Mojtaba Shiraz Univ Coll Agr Biosyst Engn Dept Shiraz Iran Shahrekord Univ Fac Agr Dept Mech Engn Biosyst Shahrekord *** Iran

Discrete element method (DEM) was employed to model and optimise the weed seed burial and tillage forces as affected by mouldboard design parameters (i.e. the cutting angle (epsilon), the setting of the share angle (theta(s)), the curvature parameter (q)), ploughing depth and speed. Several mouldboards were designed with combinations of e at 40 degrees, 45 degrees, 50 degrees and 60 degrees, qs at 25 degrees, 35 degrees, 45 degrees and 55 degrees and q at 20, 22, 24 and 30. A total of 64 DEM simulations were performed and the resulting percentage of weed seed burial and tillage forces were analysed. Optimisation of mouldboard design parameters was performed using the response surface methodology (RSM). The optimal combination resulted in epsilon = 32.3 degrees, theta(s) = 47.8 degrees, and q = 28.2. Then, the combined influence of ploughing depth and speed was investigated and the values of 0.3 m and 1 ms(-1) were selected as the best combination to achieve maximum weed seed burial. For validation of the simulation results, a full scale mouldboard plough was tested in the field with blue-coloured polyethylene pellets as a layer of weed seed on the topsoil. Comparison of the measured and predicted weed seed burial below the critical burial depth (i.e. 0.15 m) showed the simulated percentage of weed seed burial within bounds of +/- 15% of the measured values with R-2 of 0.93. As a conclusion, DEM can be a useful tool to optimise the design of tillage tools to improve the effectiveness of tillage. (C) 2022 IAgrE. Published by Elsevier Ltd. All rights reserved.

关键词： DEM Mouldboard plough design parameters Weed seed burial Tillage forces Response surface methodology

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design parameters for Planning the Sample Size of Individual-Level Randomized Controlled Trials in Community Colleges

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EVALUATION REVIEW 2023年第4期47卷 599-629页

作者： Somers, Marie-Andree Weiss, Michael J. Hill, Colin MDRC K-12 Educ11965 Venice Blvd Suite 402 Los Angeles CA 90066 USA MDRC New York NY USA

The last two decades have seen a dramatic increase in randomized controlled trials (RCTs) conducted in community colleges. Yet, there is limited empirical information on the design parameters necessary to plan the sample size for RCTs in this context. We provide empirical estimates of key design parameters, discussing lessons based on the pattern of estimates across outcomes, semesters, and studies. Nearly all RCTs in community colleges use student random assignment within blocks (colleges or cohorts). Key design parameters for the minimum detectable true effect (MDTE) are the within-block outcome standard deviation (sigma(vertical bar S)) and the within-block outcome variance explained by baseline covariates like student characteristics (R-vertical bar S(2)) . The main analyses use student-level data from 8 to 14 RCTs including 5,649-7,099 students (depending on the outcome) with follow-up data for 3 years. A public database created for this paper includes parameter estimates for 30 RCTs including 65,637 students. Enrollment, credits earned, credential attainment, and grade point average. The within-block standard deviation (sigma(vertical bar S)) and therefore the MDTE can be much larger in later semesters for enrollment outcomes and cumulative credits earned. There is substantial variation across studies in sigma(vertical bar S) for degree attainment. Baseline covariates explain less than 10% of the variation in student outcomes. When planning the sample size for a study, researchers should be mindful of the follow-up period, use a range of values to calculate the MDTE for outcomes that vary across studies, and assume a value of R-vertical bar S(2) between 0 and 0.05.

关键词： design parameters statistical power community college postsecondary randomized controlled trial

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design parameters for "Robust" Superoleophobic Surfaces

Design Parameters for "Robust" Superoleophobic Surfaces

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NSTI Nanotechnology Conference and Expo (Nanotech 2012)

作者： Law, K. Y. Zhao, H. Park, K-C Xerox Innovat Grp Xerox Res Ctr Webster Webster NY USA MIT Dept Mech Engn Cambridge MA 02139 USA

ISBN: (纸本)9781466562745

Earlier we reported the fabrication of a model superoleophobic surface comprising 3 pm diameter pillar arrays (height similar to 7.8 mu m, pitch 6 mu m) on silicon wafer via the conventional photolithography and surface fluorosilanation techniques. Results showed that both surface fluorination and the re-entrant structure in the pillar are crucial in achieving superoleophobicity and superhydrophobicity with hexadecane and water contact angles exceeding 150 and sliding angles at similar to 10 degrees. In this work, we investigate design parameters for the fabrication of a superoleophobic surface that is robust against wetting breakthrough pressure and mechanical abrasion. By studying the effects of pillar height, size and spacing, we show that both static and advancing contact angles remain "super" (>150 degrees) as the pillar size and spacing vary, the receding contact angle, sliding angle and contact angle hysteresis, on the other hand, are found to be sensitive to these structural changes. The receding angle decreases and both sliding angle and hysteresis increase as the solid area fraction increases. Interestingly, surface superoleophobicity remains as the height of the pillar decreases from similar to 7.8 to 1 mu m. Surface Evolver simulation was used to model the location of the contact line as well as the robustness in wetting against external pressure. The abrasion resistance of the pillar array surface was assessed by mechanical modeling and nanoindenter measurement. The design space for fabricating a mechanically robust superoleophobic surface is discussed.

关键词： Superoleophobicity surface texturing design parameters robustness breakthrough pressure

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Optimization of design parameters for controlled rocking steel braced dual-frames

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Earthquake Engineering and Engineering Vibration 2022年第4期21卷 1053-1068页

作者： Sobhan Ghasemi M.Firoozi Nezamabadi Abdolreza S.Moghadam Mahmood Hosseini Department of Civil Engineering South Tehran BranchIslamic Azad UniversityTehranIran Structural Engineering Research Center International Institute of Earthquake Engineering and Seismology(IIEES)TehranIran

A controlled rocking concentrically steel braced frame(CR-CSBF)is introduced as an alternative to conventional methods to prevent major structural damage during large *** is equipped with elastic post-tensioned(PT)cables and replaceable devices or fuses to provide overturning resistance and dissipate energy,*** CR-CSBFs are not officially legalized in globally valid codes for new buildings,it is expected to be presented in them in the near *** main goal of this study is to determine the optimal design parameters consist of the yield strength and modulus of elasticity of the fuse,the initial force of the PT cable,and the gravity load on the rocking column,considering different heights of the frame,spanning ratios and ground motion types for dual-configuration *** time-history analyses are performed in *** study aims to define the optimal input variables as effective design parameters of CR-CSBFs by comparing four seismic responses consisting of story drift,roof displacement,roof acceleration and base shear,and also using the Euclidean metric optimization *** the previous research,this study is innovative and first of its *** results demonstrate that the optimal design parameters are variable for various conditions.

关键词： self-centering rocking steel braced frame design parameters optimization low damage

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design parameters for Spatial Helix Gearing Mechanism

Design Parameters for Spatial Helix Gearing Mechanism

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2nd International Conference on Frontiers of Manufacturing and design Science (ICFMD 2011)

作者： Chen, Yangzhi Chen, Zhen Fu, Xiaoyan S China Univ Technol Sch Mech & Automot Engn Guangzhou 510640 Guangdong Peoples R China

ISBN: (纸本)9783037852828

The formulas of design parameters for spatial helix gearing mechanism are deduced based on the equation of spatial curve meshing, including teeth number, helix angle and screw pitch of driving tines, diameter of tines, corrected length of tines, height of teeth etc.. That could supply theoretical basis for industrial application of the spatial helix gearing mechanism.

关键词： spatial helix gear gearing mechanism design parameters small devices

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Effects of Electrically Activated Silver-Titanium Implant System design parameters on Time-Kill Curves Against Staphylococcus aureus

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JOURNAL OF MEDICAL AND BIOLOGICAL ENGINEERING 2016年第3期36卷 325-333页

作者： Tan, Zhuo Xu, Guangning Orndorff, Paul E. Shirwaiker, Rohan A. N Carolina State Univ Edward P Fitts Dept Ind & Syst Engn Raleigh NC 27695 USA N Carolina State Univ MITE Lab Raleigh NC 27695 USA N Carolina State Univ Dept Stat Raleigh NC USA N Carolina State Univ Dept Populat Hlth & Pathobiol Raleigh NC 27607 USA UNC NCSU Joint Dept Biomed Engn Raleigh NC 27695 USA

Implant-associated infections pose serious threats to patients in terms of morbidity, mortality, and medical costs. This paper focuses on the quantitative assessment of the antimicrobial efficacy of a silver-based prophylactic system for orthopaedic implant applications. The implant system is configured to induce controlled local administration of silver ions via low intensity direct current activation (1-14 A mu A). We developed a broth-based in vitro testing model to evaluate the effects of important design parameters on the antimicrobial efficacy of the system over a 48-h interval. The time-kill curves obtained with various parameter levels were analyzed through a longitudinal model. Five parameters were investigated independently through one-way factorial experiments (n = 12) against Staphylococcus aureus. In phase 1 of the study, we investigated the effect of cathode material on system performance. We also determined the linear structure of the longitudinal model based on the Akaike information criterion by fitting the empirical data to multiple candidate model structures. The results show that substituting the silver cathode with titanium does not weaken the antimicrobial efficacy of the system (p = 0.9946). In phase 2, a detailed analysis with four design parameters was conducted using the silver-titanium configuration. The performance of the system was found to be independent of the electrode separation distance (p = 0.9926) and the pulsating current frequency (p = 0.9956). However, the anode surface area (p < 0.0001) and the current intensity (p < 0.0001) influenced the antimicrobial efficacy in an interactive manner. Overall, this study characterizes the in vitro antimicrobial efficacy of the proposed system and provides a reference of design parameters for future product engineering.

关键词： Antimicrobial efficacy Orthopaedic implants Ionic silver Post-operative infections design parameters

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Sensitivity Analysis of design parameters in Transverse Flux Induction Heating Device

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IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY 2020年第4期30卷 1-6页

作者： Wu, Jiancheng C., Jr. Wang, Shaopeng P., Jr. Wang, Youhua H. Liu, Chengcheng Hebei Univ Technol State Key Lab Reliabil & Intelligence Elect Equip Tianjin 300130 Peoples R China

In this paper, the Morris method of qualitative global sensitivity analysis (GSA) is used to rank the sensitivity values among four design parameters and three objectives of transverse flux induction heating (TFIH) device. The design parameters include effective value and frequency of the exciting current, the moving speed of the strip and the length of the coil along the width direction of the strip. The objective functions include relative non-uniformity of strip surface temperature distribution along strip width direction at heater outlet, average temperature of strip surface perpendicular to strip movement direction at heater outlet and heating efficiency of TFIH device. Each objective function is calculated by three dimensional (3D) finite element method (FEM). The sensitivity values ranking provides an optimal priority for the optimization or change of the design parameters of TFIH device.

关键词： design parameters global sensitivity analysis (GSA) Morris method objective functions parameters optimization transverse flux induction heating (TFIH)

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The influence of design parameters on the FEA-determined stress distribution in CAD-CAM produced all-ceramic dental crowns

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DENTAL MATERIALS 2005年第3期21卷 242-251页

作者： De Jager, N Pallav, P Feilzer, AJ Acad Ctr Dent Amsterdam Dept Dent Mat Sci NL-1066 EA Amsterdam Netherlands Univ Van Amsterdam NL-1066 EA Amsterdam Netherlands Vrije Univ Amsterdam NL-1081 HV Amsterdam Netherlands

Introduction: Knowledge of factors, which influence stress and its distribution is of key importance to the successful production of durable all-ceramic restorations. The objective of this study was to evaluate, by finite element analysis (FEA), the influence of the shape of the preparation and the cement layer on the stress distribution in CAD-CAM produced all-ceramic crowns and in their cement layer. Material and methods: The CAD models of multi-layer all-ceramic crowns for posterior tooth 46 of three patients produced with CAD-CAM-technotogy were translated into a three-dimensional FEA program. The stress distribution due to the combined influences of bite forces, residual stresses caused by the difference in expansion coefficient of the two ceramic layers, and the influence of shrinkage of the cement was investigated. Results: The tensile stresses in the crown for the chamfer knife-edge preparation might put the integrity of the currently available ceramic materials at risk, while a non-uniform cement layer might result in stresses exceeding the bond strength. It was concluded that for long lasting restorations in the posterior region it is advisable to make a chamfer with collar preparation, the cement layer as uniform, and the difference in thermal expansion for the two ceramics as small as possible. Significance: This study indicates that for full ceramic crowns in the posterior region, specific design rules should be followed, and that FEA utilizing CAD-CAM data can be a successful toot to develop design guidelines for all-ceramic restorations. (C) 2004 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

关键词： design parameters finite element analysis ceramic dental crowns

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Optimal design of a Planar-Type Antenna with a Reduced Number of design parameters Using Taguchi Method and Adaptive Particle Swarm Optimization

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JOURNAL OF ELECTRICAL ENGINEERING & TECHNOLOGY 2014年第6期9卷 2019-2024页

作者： Lee, Jeong-Hyeok Jang, Dong-Hyeok Kim, Hyeong-Seok Chung Ang Univ Sch Elect & Elect Engn Seoul 156756 South Korea

This paper presents a method to optimize the design of a planar-type antenna and reduce the number of design parameters for rapid computation. The electromagnetic characteristics of the structure are analyzed, and Taguchi method is used to identify critical design parameters. Adaptive particle swarm optimization, which has a faster convergence rate than particle swarm optimization, is used to achieve the design goal effectively. A compact dual-band USB dongle antenna is tested to verify the advantage of the proposed method. In this case, we can use only five selected geometrical parameters instead of eighteen to accelerate the optimization of the antenna design. The 10 dB bandwidth for return loss ranges from 2.3 GHz to 2.7 GHz and from 5.1 GHz to 5.9 GHz, covering all the WiBro, Bluetooth, WiMAX, and 802.11 b/g/n WLAN bands in both simulation and measurement. The optimization process enables the antenna design to achieve the required performance with fewer design parameters.

关键词： Planer-type antenna design parameters Taguchi method Adaptive particle swarm optimization USB dongle

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Determining importance degrees of website design parameters based on interactions and types of websites

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DECISION SUPPORT SYSTEMS 2013年第2期54卷 1030-1043页

作者： Cebi, Selcuk Karadeniz Tech Univ Dept Ind Engn Trabzon Turkey

Nowadays, the internet is the most widely used and an effective tool for firms/organizations to reach their customers by their websites. Hence, effective design of websites helps firms/organizations to reach their aim. There are lots of design parameters that play an effective role on website design. These parameters are considered by researchers in some academic papers. However, none of the published articles takes into account both interactions among the design parameters and importance degrees of design parameters in terms of website types. Therefore, in the scope of this paper, in order to address these research gaps, an integrated multiple criteria decision making method including Delphi and DEMATEL (DEcision-MAking Trial and Evaluation Laboratory) techniques has been proposed for determining importance degrees of website design parameters. Furthermore, the website design parameters were determined based on detailed review of literature available. In addition, a new classification has been presented for websites. Finally, this paper indicates that the importance degrees of website design parameters are based on both website types and interaction among the design parameters. To illustrate the steps of the proposed algorithm, an application has been presented. (C) 2012 Elsevier B.V. All rights reserved.

关键词： Website design design parameters DEMATEL Delphi TOPSIS

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