Failures of the cranes’ structural parts unavoidably lead to serious damages or total collapses; these accidents are often followed by very high financial losses and possibly serious injuries or ...crane-related fatalities. The objective of this research was to identify the causes that led to the failure of the hammerhead tower crane (xl425C) counterjib. The crane is used for assembly works at the hydropower dam. The counterjib collapse resulted from a gusset plate failure and caused such significant damage of the whole crane structure that the crane was dismantled and removed from operation. The study of the accident includes: (1) Identification of the stress-state, where a FEM model is developed to provide a useful tool for studying stress analysis; (2) Laboratory investigations are conducted in order to define the chemical composition and mechanical properties of the material, the tensile properties, hardness, impact toughness, as well as the metallographic analyses. The analysis of the obtained results showed that the principal reasons behind the gusset plate failure originated from design and fabrication faults. The working stress was higher than the allowable one. Also, impact toughness was too low and the fabrication of welds was incorrect.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This volume contains the proceedings of the CIEM workshop on Tropical Geometry, held December 12-16, 2011, at the International Centre for Mathematical Meetings (CIEM), Castro Urdiales, Spain. ...Tropical geometry is a new and rapidly developing field of mathematics which has deep connections with various areas of mathematics and physics, such as algebraic geometry, symplectic geometry, complex analysis, dynamical systems, combinatorics, statistical physics, and string theory. As reflected by the content of this volume, this meeting was mainly focused on the geometric side of the tropical world with an emphasis on relations between tropical geometry, algebraic geometry, and combinatorics. This volume provides an overview of current trends concerning algebraic and combinatorial aspects of tropical geometry through eleven papers combining expository parts and development of modern techniques and tools.
In this paper, thermogravimetric analysis (TGA) of crude glycerol, date seeds and their blends in was performed. Blending solid biomass with crude glycerol is found in the literature to enhance the ...gasification of solid biomass and yield valuable syntheses gaseous fuels. The studied glycerol to date seeds ratios were 3:1, 1:1 and 1:3 respectively. The samples were heated from room temperature till 700°C at a ramp heating of 20°C/min in nitrogen environment supplied at 50 ml/min. The used crude glycerol was prepared from waste cooking oil. In addition, theoretical curves based on the proposed ratios were done and their results were compared to the experimental work. The main objective of this work is to study the effect of the glycerol content on the thermal degradation performance of the prepared samples. The results have shown that the crude glycerol presence in the blends has affected the TG behavior and implied some kind of chemical reaction occurring in the temperature range of 200C to 475C. Also, the theoretical curves had shown almost good agreement with the experimental ones specially at high temperature levels (475C to 700C) and indicated some kind of chemical reactions between the raw materials at lower temperature levels (200C to 475C).
Nasca society emerged at the beginning of the Early Intermediate Period (AD1-750) and flourished along the arid south coast of Peru into the Middle Horizon (AD750-1000). In this study, long- and ...short-term residential mobility, palaeodiet and stress experiences for individuals from the ceremonial centre Cahuachi (n=41) and cemeteries in the Las Trancas river valley (n=13) are reconstructed. Emphasis is placed on understanding the synergy of movement, diet, stress, and the social and physical landscapes in producing the biochemical record archived in the human body. Through oxygen-isotope analysis of human tissues and modern environmental waters, it was demonstrated that, although most individuals buried at Cahuachi came from the Southern Nasca Region middle valleys, many spent a portion of their lives in other parts of the Rio Grande de Nasca drainage. Within-lifetime relocation was assessed using strontium- and oxygen-isotope analysis of bone and enamel pairs for a subset of individuals (n=20). These analyses revealed that half of the individuals analyzed moved between childhood and adulthood. Carbon- and nitrogen-isotope analyses of bone and hair showed dietary change consistent with (semi-) permanent relocation and with local mobility in the months/years before death. Together, these analyses suggest that movement, whether associated with burial at Cahuachi, relocation and/or local mobility, likely played an important role in the engagement of Nasca people with their physical and social landscapes. Long-term average diet consisted of a mixed C3/C4 plant base with greater reliance on maize and consumption of lower trophic level meat and plant-derived protein. Sequential isotopic analysis of hair demonstrated that some individuals had stable or seasonally shifting diets, and that others exploited multiple production zones. Dietary patterns are interpreted to represent flexibility in food acquisition as a means of minimizing risk associated with environmental and social instability. Biogenic patterns of cortisol production were observed in sequential analyses of hair, enabling direct reconstruction of stress experiences. Combined sequential isotopic and cortisol data provided insight into the metabolic and physiological causes of individual stress experiences associated with dietary change and residential mobility. Keywords: bioarchaeology, residential mobility, palaeodiet, stress, stable isotope analysis, cortisol, hair, Nasca, Cahuachi, Peru
In order to solve the special type of reset option in the presence of transaction costs, we adopt the Markov chain method as well as the dual analysis. By introducing mixed stopping times, gradient ...restriction and approximate martingales, we set up the framework to perform the algorithm for the special type of reset option. After that, we elaborate on the procedures for the reset option pricing in the presence of proportional transaction costs. Finally, we propose the reset option prices for the sellers and buyers and do some case analysis.
A basic part of the logistics management in companies is the purchasing function, and the appropriate selection of vendors is one of the prime responsibilities of this function. Many conceptual and ...analytical models have been developed for addressing the vendor selection problem. While it has been recognized that vendor selection is multiobjective in nature, litle has been done to develop techniques for measuring vendors' performance on multiple criteria. Thus, this paper presents an approach for evaluating vendors in order to select the most proper one in a procurement situation. The approach uses data envelopment analysis to evaluate the vendors' efficiency. The criteria considered in this model are service quality, price, delivery and rate of rejected parts. The findings prove that the traditional supplier evaluation and selection methods are inefficient and the vendors who provide the best service quality are not necessarily efficient.
Een web aan allianties Sheikh, Haroon
Atlantisch Perspectief,
01/2024, Volume:
48, Issue:
2
Journal Article
Al 75 jaar is de NAVO het succesvolste en sterkste veiligheidsverband dat de geschiedenis ooit heeft voortgebracht. Maar een wereldorde ontstaat niet uit een enkel instituut. Deze is eerder de ...uitkomst van een geheel van overlappende instituties en verbanden die staten op verschillende manieren verbinden. Die geopolitieke lappendeken is nu volop in ontwikkeling.
75 jaar NAVO van de Wijdeven, Ivo
Atlantisch Perspectief,
01/2024, Volume:
48, Issue:
2
Journal Article
Al 75 jaar rekenen de Europese landen via de NAVO op bescherming door de Verenigde Staten. Het Noord-Atlantisch Verdrag had een wederzijds strategisch belang. Toch zijn er ook genoeg momenten geweest ...dat het binnen het bondgenootschap niet boterde. Maar ondanks verdeeldheid op tal van terreinen is er toch eensgezindheid over de noodzaak elkaars grondgebied gezamenlijk te verdedigen. Dat is misschien wel de grootste kracht van het bondgenootschap.
PDF
