An Approach for Robust Design of Reactive Power Metal Mixtures Based on Non-deterministic Micro-scale Shock Simulation

In this paper, we propose a method for the robust design of materials involving processes that are computationally intensive and selectively random. The material system considered is a reactive particle metal mixture (RPMM) composed of aluminum and iron oxide (Al+Fe₂O₃). Shock simulations of discrete energetic particle mixtures are performed to predict the system’s mechanical and thermal behavior that will be used by a designer of the mixture to achieve robust micro-scale reaction initiation. The method used to predict the behavior of the material system is the robust concept exploration method with error margin index (RCEM-EMI). An error margin index is a mathematical construct indicating the location of mean system performance and the spread of this performance considering both variability in design variables and models of the system. Variability in responses of a model may be due to system variation that cannot be easily parameterized in terms of noise factors. Furthermore, lack of data, due to the cost of simulations and experiments, leads to uncertain parameters in empirical models. System response variability and parameter uncertainty in an empirical model are estimated in a computationally efficient manner to formulate the error margin indices, which are then leveraged to search for ranged sets of design specifications. Finally, the RCEM-EMI is illustrated for designing a RPMM.     

Collaborative multidisciplinary decision making using game theory and design capability indices

The complexity of modern product realization processes requires collaborative work of engineering teams from different disciplines. We apply principles from game theory to model the relationships between engineering teams and facilitate collaborative decision making. In order to maintain design freedom in the early stages of product realization so that engineering teams in the later stages can adjust their decisions while still maintaining feasibility, we postulate the use of design capability indices to facilitate the teams making a ranged set of decisions, instead of specific ones. The effect of game theoretic principles and design capability indices on design freedom and therefore on the design solutions is also investigated. An electronic package design and analysis scenario is used to demonstrate the efficacy of the proposed method.     

Synthesis of Fe3O4/SiO2/Polypyrrole magnetic nanocomposite polymer powder: Investigation of structural properties and ability to purify of edible sea salts

In this study, Fe₃O₄/SiO₂/polypyrrole magnetic nanocomposite polymer powder was chemically synthesized. The structure of the prepared composite powders were studied using scanning electron microscopy, FTIR and XRD techniques. The results showed that the prepared composites have a nanometer structure. The FTIR results confirmed the electrostatic interactions between the composite components. XRD also showed the crystal structure of Fe₃O₄ and its composites. Optimal nanocomposite powder was used to purify the salt of Lake Urmia. Salt samples were treated with powder and the chemical properties of salt were investigated before and after treatment. Qualitative tests performed on salt included COD, BOD, organic compounds, heavy metals, nitrate and nitrite, and color characteristics. Finally, the efficiency of the nanoparticle powder in the lake salt treatment was calculated. The results showed that the composite powder reduced BOD and COD as well as the heavy metal salts of the lake. Also, the organic compounds in the salt decreased and the color factors such as the white index of the salt increased. Under optimal conditions, Fe₃O₄/SiO₂/PPy composite showed the best performance at 37 min of purification time. In general, Fe₃O₄/SiO₂/PPy composite can be easily used to purify sea salts and also reduce environmental pollutants.     

Dynamic Analysis of Nonlinear Frames by Prandtl Neural Networks

A new type of activation function, based on the use of the Prandtl–Ishlinskii operator, has been developed and used in the feed forward neural networks in order to improve their capabilities in learning to identify and analyze nonlinear structures subject to dynamic loading. The genetic algorithm has been used in its training. The neural network, which is referred to as the Prandtl neural network here, has been trained and used in the analysis of two shear frames, a single degree of freedom (SDOF) and a 3DOF, both subjected to earthquake excitations. To assess the capabilities of the Prandtl neural network under ideal situations, the data on the response of the frames have been obtained through the integration of their governing nonlinear equations of motion. The training has been based on the white noise while the strong earthquakes of 200% El Centro in 1940 and Gilroy have been used for testing. Results have shown the high precision of the Prandtl neural network in solving highly hysteretic problems. The issue is important for two main applications in structural dynamics and control: (1) analysis of highly nonlinear structures where it is desired to train a neural network to directly learn the behavior of a structure from experimental data; and (2) intelligent active control of structures where neural network emulators are designed to provide as precise predictions about the future response of the structures as possible, in order to be used in the determination of the required control forces.     

Primary and secondary tools’ life evaluation for soft ground TBMs

Bulletin of Engineering Geology and the Environment - Tool wear and tool life are very important issues for soft ground tunnel boring machines (TBMs) as they are directly related to the time and...     

Microgrid dynamic security: Challenges,solutions and key considerations

The manifested merits of microgrids (μGs) are well-known in the era of modern power systems; however, μGs are in challenge with new technical issues pertaining to their operation, control, and protection. Maintaining dynamic security in μGs is one of the challenges addressed in this paper.     

The Report of the Subpanel to FESAC Concerning Alternative Concepts

This is the July 1996 report of a subpanel of the US Department of Energy Fusion Energy Sciences Advisory Committee (FESAC), charged with reviewing the present status of fusion alternative concept development and the prospects for alternative concepts not only as fusion power systems but also the scientific contributions of alternative concept research to the fusion energy sciences program and to plasma science in general.     

Contribution of imaging in intestinal intussusception in the adult. Apropos of a case of ileocolic intussusception secondary to cecal lipoma

On the basis of a case of ileocolonic intussusception in a 35-year-old patient secondary to an obstructive lipoma of the caecum, the authors review the literature and discuss the clinical and radiological aspects of this disease. The diagnosis was established by CT scan and barium enema before surgery. Adult intussusception is a rare disease, which does not have any specific clinical features. Radiological imaging is the only complementary investigation which can suggest the diagnosis.