scholarly journals Predicting the Fatigue Life of an AlSi9Cu3 Porous Alloy Using a Vector-Segmentation Technique for a Geometric Parameterisation of the Macro Pores

Metals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 72
Author(s):  
Dejan Tomažinčič ◽  
Žiga Virk ◽  
Peter Marijan Kink ◽  
Gregor Jerše ◽  
Jernej Klemenc
Keyword(s):  
High Pressure ◽  
Fatigue Life ◽  
Functional Performance ◽  
Research Work ◽  
Element Mesh ◽  
Work Related ◽  
Segmentation Technique ◽  
Euclidian Space ◽  
Die Cast ◽  
Published Research

Most of the published research work related to the fatigue life of porous, high-pressure, die-cast structures is limited to a consideration of individual isolated pores. The focus of this article is on calculating the fatigue life of high-pressure, die-cast, AlSi9Cu3 parts with many clustered macro pores. The core of the presented methodology is a geometric parameterisation of the pores using a vector-segmentation technique. The input for the vector segmentation is a μ-CT scan of the porous material. After the pores are localised, they are parameterised as 3D ellipsoids with the corresponding orientations in the Euclidian space. The extracted ellipsoids together with the outer contour are then used to build a finite-element mesh of the porous structure. The stress–strain distribution is calculated using Abaqus and the fatigue life is predicted using SIMULIA fe-safe. The numerical results are compared to the experimentally determined fatigue lives to prove the applicability of the proposed approach. The outcome of this research is a usable tool for estimating the limiting quantity of a structure’s porosity that still allows for the functional performance and required durability of a product.

scholarly journals Risk of Increased Acceptance for Organizational Nepotism and Cronyism during the COVID-19 Pandemic

Risks ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 59
Author(s):  
Grzegorz Ignatowski ◽  
Łukasz Sułkowski ◽  
Bartłomiej Stopczyński
Keyword(s):  
Qualitative Study ◽  
Quantitative Methods ◽  
Research Work ◽  
Negative Effects ◽  
Qualitative And Quantitative ◽  
Qualitative And Quantitative Methods ◽  
Work Related ◽  
Social And Economic Development ◽  
The Times ◽  
The Impact

Nepotism and cronyism are forms of favoritism towards certain people in the workplace. For this reason, they constitute a problem for organization managers, ethicists and psychologists. Identifying the impact of COVID-19 pandemic on the increase of nepotism and cronyism may provide a basis for organizations to assess their extent and to take possible measures to prevent their negative effects. At the same time, the research presented in the article may provide a basis for further research work related to nepotism and cronyism at the times of other threats, different from the pandemic. The aim of the article is to examine the impact of the COVID-19 pandemic on growing acceptance for nepotism and cronyism in Polish enterprises. Qualitative and quantitative methods have been included in the conducted research. Qualitative study aimed at improving knowledge of nepotism and cronyism and the impact of the COVID-19 pandemic on these phenomena, followed by a quantitative study conducted in order to verify the information obtained in the qualitative study. This research has demonstrated that Nepotism and cronyism in the workplace, are phenomenon that are basically evaluated negatively. They adversely influences social and economic development, but the impact of COVID-19 pandemic on nepotism and cronyism is not significant.

scholarly journals Towards a Functional Performance Validation Standard for Industrial Low-Back Exoskeletons: State of the Art Review

Sensors ◽  
2021 ◽  
Vol 21 (3) ◽  
pp. 808
Author(s):  
Mattia Pesenti ◽  
Alberto Antonietti ◽  
Marta Gandolla ◽  
Alessandra Pedrocchi
Keyword(s):  
Functional Performance ◽  
State Of The Art ◽  
Productivity Loss ◽  
Evaluation Criteria ◽  
The State ◽  
Low Back ◽  
Industrial Workers ◽  
Rigorous Evaluation ◽  
Work Related ◽  
Absence From Work

While the research interest for exoskeletons has been rising in the last decades, missing standards for their rigorous evaluation are potentially limiting their adoption in the industrial field. In this context, exoskeletons for worker support have the aim to reduce the physical effort required by humans, with dramatic social and economic impact. Indeed, exoskeletons can reduce the occurrence and the entity of work-related musculoskeletal disorders that often cause absence from work, resulting in an eventual productivity loss. This very urgent and multifaceted issue is starting to be acknowledged by researchers. This article provides a systematic review of the state of the art for functional performance evaluation of low-back exoskeletons for industrial workers. We report the state-of-the-art evaluation criteria and metrics used for such a purpose, highlighting the lack of a standard for this practice. Very few studies carried out a rigorous evaluation of the assistance provided by the device. To address also this topic, the article ends with a proposed framework for the functional validation of low-back exoskeletons for the industry, with the aim to pave the way for the definition of rigorous industrial standards.

scholarly journals The Effectiveness of Organic Pollutants Removal in Constructed Wetland with Horizontal Sub-Surface Flow / Efektywność Usuwania Zanieczyszczeń Organicznych W Oczyszczalni Hydrofitowej

2015 ◽  
Vol 16 (1) ◽  
pp. 69-82 ◽  
Author(s):  
Anita Jakubaszek ◽  
Zofia Sadecka
Keyword(s):  
Wastewater Treatment ◽  
Organic Pollutants ◽  
Constructed Wetland ◽  
Suspended Solids ◽  
Research Work ◽  
Vegetation Period ◽  
Surface Flow ◽  
Seasonal Temperature ◽  
Work Related ◽  
Pollutants Removal

Abstract This paper presents the results of the research work related to the removal efficiency from wastewater organic pollutants and suspended solids at HSSF (horizontal subsurface flow) constructed wetland. The average effectiveness defined as loss of value COD in wastewater has reached 77%, for BOD5 - 80% and TOC - 82%. The effect of seasonal temperature changes and the period of plant vegetation and rest on the effectiveness of wastewater treatment were also analyzed. The results of the presented research showed a decrease in the efficiency of removing organic pollutants from wastewater and suspended solids in the autumn and winter. During the vegetation the object in Małyszyn has been characterized by the effectiveness of wastewater treatment at the level of 78% for COD, 82% for BOD5, and in the non-vegetation period the effectiveness has decreased up to 75% for COD and 74% for BOD5. During the plants growth the total suspension was removed in 88%, whereas during the plants rest efficiency of removing lowered to 69%.

Design Formulas of Blind End Closures for High Pressure Vessels

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
R. D. Dixon ◽  
E. H. Perez
Keyword(s):  
High Pressure ◽  
Fatigue Life ◽  
Maximum Stress ◽  
Accurate Determination ◽  
Pressure Vessels ◽  
Stress Distributions ◽  
Fatigue And Fracture ◽  
Asme Code ◽  
Section Viii

The available design formulas for flat heads and blind end closures in the ASME Code, Section VIII, Divisions 1 and 2 are based on bending theory and do not apply to the design of thick flat heads used in the design of high pressure vessels. This paper presents new design formulas for thickness requirements and determination of peak stresses and stress distributions for fatigue and fracture mechanics analyses in thick blind ends. The use of these proposed design formulas provide a more accurate determination of the required thickness and fatigue life of blind ends. The proposed design formulas are given in terms of the yield strength of the material and address the fatigue strength at the location of the maximum stress concentration factor. Introduction of these new formulas in a nonmandatory appendix of Section VIII, Division 3 is recommended after committee approval.

Heuristics for Domain-Independent Planning: A Survey

2011 ◽  
Vol 135-136 ◽  
pp. 573-577 ◽  
Author(s):  
Rui Shi Liang ◽  
Min Huang
Keyword(s):  
State Space ◽  
Heuristic Search ◽  
Research Work ◽  
Future Research ◽  
Survey Analysis ◽  
Work Related ◽  
State Space Search ◽  
Survey Results ◽  
Domain Independent ◽  
Intense Research

Increasing interest has been devoted to Planning as Heuristic Search over the years. Intense research has focused on deriving fast and accurate heuristics for domain-independent planning. This paper reports on an extensive survey and analysis of research work related to heuristic derivation techniques for state space search. Survey results reveal that heuristic techniques have been extensively applied in many efficient planners and result in impressive performances. We extend the survey analysis to suggest promising avenues for future research in heuristic derivation and heuristic search techniques.

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