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A Study of the Nordic Bronze Age Through Anarchic Theory
Get PDFThe Nordic Bronze Age started c. 2000/1700 BCE and ended in 500 BCE with the introduction of the Iron Age. The nature of the sociopolitical organization of the Nordic Bronze Age is an area of uncertainty among archaeologists. While some authors argue that Scandinavian society consisted of centralized chiefdoms with a warrior ideology, others believe that forms of egalitarian politics and organization were more common. Some of these disagreements stem from the sources and interpretations used by different researchers. While burials reveal a society with stratified chiefdoms, settlement patterns suggest a more egalitarian society. Another issue to note is that the Nordic Bronze Age covers a timespan of ~1500 years in which many changes are seen in the availability of resources within some social systems. Anarchist theory can provide a new framework for understanding complex societies that lie outside of hierarchical and centralized organizations, as is possibly observed in Nordic Bronze Age society. I will compare Early and Late Bronze Age burials and settlements through an anarchic perspective to show that individual autonomy and decentralized power were not uncommon in Scandinavian society
The Development of a New Bond Stress-Slip Model in Continuously Reinforced Concrete Pavements
No full textContinuously reinforced concrete (CRC) pavement construction involves the placement of a reinforcing bar (rebar) with lugs on the bar surface, followed by casting concrete to create a bond. The bond stress between the rebar and concrete requires an external tensile force in the rebar direction. The tensile and compressive forces applied to the rebar transfer stresses to the concrete, creating bond stress. During this process, the rebar moves in the tensile and compressive directions while the concrete restrains it, causing differential movement that can lead to slip and cracking.
Several pullout testing techniques and standards, such as AASHTO T-177 and ASTM C78, have been developed to gauge bond strength. The bond and related bond models (such as Vetter, CRCP-9, Pavement ME, Reis, and TTICRCP program) have undergone extensive research. However, these models were developed using bond stiffness parameters, which can be difficult to ascertain, and did not include the threshold of slip.
Furthermore, previous research has conducted pullout testing that involved both tensile and compressive stress. However, since slip is caused by the relative movement between rebar and concrete, only tensile stress needs to be applied. As a result, a new bond model is required to be simplified using new bond slip coefficients and a threshold of slip based on the new pullout testing that applies only tensile stress.
A new pullout testing method was developed to define Reis slip coefficients using only tensile stress. The method involved placing rebar on a cylindrical mold and subjecting specimens to stress levels ranging from 5000 to 35000 psi on a tensile machine. Throughout the testing, peak bond stress and bond stiffness were examined, taking into account steel diameter, compressive strength of concrete, and aggregate types. Using the results obtained from the pullout testing, certain parameters were identified to rework the bond-slip relationship, resulting in a revised TTICRCP program. A revised bond model was created using the newly determined Reis slip coefficients and slip threshold. This model calculated crack spacing and width, resulting in the modification of the Pavement ME method. To validate the revised model, a comparison was made between the model's predictions of crack spacing and width and the actual field data. The results showed that the model closely matched the field data, indicating its practicality
Route Planning for a Collection of Curvature Constrained Heterogeneous Vehicles
No full textThis thesis explores the application of the Dubins vehicle model to represent fixed-wing air-craft and similar unmanned aerial vehicles in the context of heterogeneous vehicle routing. Specif-ically, it addresses the Min-Max variant of the problem, where multiple heterogeneous vehicles aim to efficiently visit a sequence of targets starting from different depots. The research proposes a Mixed-Integer Programming (MIP) formulations and uses heuristic-based approaches to tackle the problem.
The study begins by employing construction heuristics to generate an initial feasible solution, followed by the application of a Variable Neighborhood Search (VNS) based meta-heuristic for fur-ther improvement. Notably, an additional initial improvement phase utilizing the Lin-Kernighan Heuristic (LKH) was introduced after the construction phase to enhance the solution quality. The contribution of this work lies in the introduction of a depot perturbation-based VNS heuristic for the Min-Max vehicle routing problem. This heuristic demonstrates superior performance com-pared to existing VNS schemes, resulting in notable improvements for larger sample sizes and higher average improvements.
To assess the effectiveness of the proposed approach, the research modifies and utilizes the TSPLIB95 instances available online for analysis. The experimental results indicate that the de-pot perturbation-based approach consistently outperforms other methodologies when dealing with larger datasets, showing significant enhancements in average solution quality. The results also indi-cate better overall results when the LKH heuristic is run after the construction phase as it improves the quality of the initial feasible solution
