Summary of Presentations

Summary of Presentations Free Essay

Life of Astronauts

by Ph.D., P.E. Lee Moradi

The goal of the current presentation is to generalize the description of major steps required for becoming an astronaut. Moreover, it discusses the benefits of modern world gained from the researches performed in space as well as depiction of distinct characteristics of astronauts’ life in space. The person who intends to become an astronaut should get Ph.D, apply to NASA, undergo successfully the selection process, perform special trainings, go to space and prepare the research.

The speaker provides the list of astronauts from different cities and towns of Alabama: Henry Hartsfield, James Voss, Mae Jemison, Kathryn P. Hire, Clifton Williams, and Kathryn C. Thornton. The aim is to show that any person from this state could become an astronaut. The speaker states that humanity goes to space because this is exciting and due to necessity to explore new locations for living. People would not be able to live on the Earth eternally for the reason of depleting resources.

The speaker pays additional attention to the benefits of space research reflected in numerous inventions, which are currently widely used in the everyday life. These inventions are the following: Velcro, car airbags, telecommunications, shock absorbing foams and materials, insulation for refrigerators and coolers, medical devices, ceramic teeth braces, microwave ovens, and development of drugs. Even the space stations resemble laboratories without gravitation force in them.

This presentation incorporates three videos, which cover the topic of astronauts’ wear, behavior of water in space using the example of washcloths, and how astronauts clean their teeth there. Their  wear consists of the underwear and special costume, which has the underpart, upper part, special gloves, and space helmet. The astronauts also use numerous tools, which enable them to repair the stations in space. The tools connect with the costume by means of ropes considering  that in case of losing an object the astronaut will not be able to return it. The underwear contains water, which provides cooling and heating of the suit. In case of any leakages, the water flooding inside the costume may create inconveniences and serious threat to the astronaut’s life. The second video shows the process of moistening the washcloths in the hockey pack using water from special bag in the environment of space station without gravitation.  Pressing the wash clothing causes water adhesion to the hands, like a gel. This video also shows the interior of space station, which compiles wires and different equipment. The astronauts should pay special attention to their feet and hands because they can easily damage and pull the wires. The speaker also emphasizes that the astronauts train in the filled water pools because sending them into space is a rather expensive task. The last video depicts the process of brushing teeth in space characterized by the absence of gravity and necessity to use the mouth for cleaning the toothbrush.

The speaker also associates such distinct characteristic with the absence of gravity whereas all human floods appear in the upper parts of the body. This causes additional pressure in the head, increase of shoulders, and loss of muscles. Thus, astronauts are obliged to perform exercises on specialized machines for 3-4 hours a day for addressing this loss.

My Response: This presentation demonstrates the specifics of becoming the astronaut, the reasons, for which people engage in this activity, enormous benefits of this profession to the humanity living on the Earth, and distinct characteristics of life on the space stations. This information is extremely useful for obtaining broad understanding of living conditions faced by the astronauts. The speaker engaged the audience into the discussion about the life in space by raising the curiosity to this topic.

Digital Child Project: Numerical Model Development

by Kenneth Walls

The major goal of this presentation is to show the necessity and the ability to design the special model for children that will differ from that of the adults. It provides understanding of the existing discrepancies between children and adults, due to which the scalability of the models is impossible. The major objective of the presented work is the development and introduction of age-dependent finite element models for the children.

The overall process repressed the cycle composed of the following elements: geometry, meshes, trial simulations, material identification, and post processing. The first element is essential for the beginning of simulation process. In the depicted project, it is possible to obtain the models from CT/MR image databases. The next step is the designation of  the certain algorithms. Their application will provide generation of hexahedral and quadrilateral elements. The surface geometry presented by WSU serves as the background for creation of FE meshes for the children of chosen ages. The presentation paid additional attention to the assurance of high quality meshes. Notwithstanding the fact that tetrahedral mesh provides excellent visualization of the object, it is not applicable to the current work due to the inappropriateness of its computational structural analysis. Mesh generation and mesh refinement provides shape smoothing and insertion of buffer layer, surface creation and node smoothing for the generation of hexahedral and quadrilateral algorithms. In the process of mesh generation, it is necessary to make the additional emphasis on the enormous relevance of buffer layer insertion (also known as sheet insertion) in order to eliminate the creation of low-quality hexahendra.

The speaker provided the examples of hex meshing for 5YO-liver, 10YO-Pelvis, and 10YO-Rib Cage. In the second example, the depicted methodology enables to eliminate negative volume elements and, at the same time, provides the ability to control mesh density by a parameter. The presentation also visualizes geometry differences between adult and child pelvis: breadth on 69 % and high on 91 %. Thus, it is impossible to decrease the adult models for the application to those of children, as the proportions of breadth and high are different.

The speaker discusses these findings providing the example of an experiment using child cadavers. He applies the following loading and boundary conditions: impact velocity of 7.5 m/s; impact mass of 3.24 kg, 12 participants aged from 2 to 12; fixing of head, torso, and contralateral side. The speaker introduces pre-optimization preliminary results and starts the necessity of optimization.

The project presents further actions using material identification by means of computational simulation and optimization technique. It was necessary to identify  material constants due to the understanding of limited efforts directed to pediatric properties and responses. This is due to the difficulties in obtaining pediatric cadavers, existing differences between adult and child material properties of pediatric bones and tissues, absence of full validation of applied scaling of adult data, and necessity to investigate pediatric properties using tested information.

The identification of material constants started from the assignation constitutive of every component. Then, the researchers estimated constants and their ranges for the used materials; applied optimization techniques with the aim to decrease the discrepancy between experimental and simulation results; and performed dynamic and static finite element assessment.

The following design variables (DV)  influenced significantly  the morel responses: thickness of cortical bone, elastic modulus of cortical bone, stiffness of sacroiliac joints and public symphysis joints. The researchers devoted much effort to the identification of DVs that minimize objective functions of peak impact force, viscous criteria, and pelvic compression between simulation and experiment model. The speaker used successfully the described technique for determination of age specific properties of the cervical spine and rib cage.

My Response: This presentation shows how hexahedral and quadrilateral algorithms can be developed and effectively applied to the identification of age specific properties. The enormous relevance of this research refers to the understanding of the existing significant discrepancies between child and adult pelvis. I expect that I will be able to apply this knowledge in the future.

An Improved Contact Algorithm for Multi-material Arbitrary Lagrangian-Eulerian Hydrocodes

by Kenneth Walls

The speaker introduced his dissertation with the aim to improve contact algorithm for multi-material arbitrary Lagrangian-Eulerian Hydrocodes. He provides the definition and short explanation of Hydrocodes. One considers them  as the class of computer programs, applied to solve the large deformation, finite strain transient problems using short time scales. In major cases, Hydrocodes include strength of materials and use explicit time integration with inserter energy equation. Modeling of deviatoric and pressure terms is separated. The speaker pays additional attention to the accurate resolution of Hydrocodes in space and time.

He applies modeling of Hydrocodes in tests, which are difficult and/or expensive to do experimentally. Usually they are applicable in such fields as defense, astrophysics, automobile crashworthiness, aircraft influence by birds, and manufacturing processes.

There are different types of Hydrocodes: Lagrangian, Eulerian, and others. The relevant characteristics of Lagrangian are high aligning with the material and deformations, application of singe material per element and natural development of contact. However, this type has difficulties in assessment of serious problems, which involve large-scale and mesh deformations. Lagrangian type plays a crucial role in the performance of industry tasks. Eulerian type is associated with fixation of mesh in space and movement of material through the mesh. This type enables modeling of large-scale deformations and avoids occurrence of any ash distortion issues. The major issue of Eulerian type is lack of physical accuracy. It is applicable to the situations, which require modeling of serious deformations and for defensive purposes.

The speaker also emphasized the contact-impact problem reflected in the necessity to predict the behavior of two (or more) contacting bodies in time domain by the application of equations. These include equations of motion, constitutive equations, BC’s (deformation dependent and independent) and IC’s equations.

The major motivator for the preparation of the discussed dissertation was the enormous issue of Eulerian type reflected in the application of only single velocity field for all materials in the mixed cell. The researcher tried to designate a new approach to the modeling of this type of Hydrocodes for addressing the corresponding issue. This approach undermines application of unique mixed-element algorithms, separate solution of conservation equations for each material and imposition of traction integrals. The conservation equations (mass, momentum, and energy) were applied for identification of velocity, density, and specific energy.

Introduced ALE form of conservation equations incorporates Lagrangian and Eulerian elements, contact enforcement and mesh returned to the original position. Contact enforcement undermines reposition of materials, determination of new material velocities, imposition of tractions, and mesh deformations. The researcher pays additional attention to the necessity of satisfying the inequality constraints on the boundary of material interface and restriction of any penetration due to the application of special condition. It is possible to alter the velocities of neighboring nodes by means of nodal forces (velocities of master node and slave node). Contact enforcement step is applicable only to the elements characterized by violation of contact constraints. This step  involves conservation of mass, momentum, and energy. Second advection step provides returning of the mesh to the original configuration applying other equations of mass conservation, momentum, and energy. This step also incorporates interface tracking, which is possible to perform due to SLIC and Young’s algorithm. The first algorithm involves the assumption that interfaces and mesh contours are parallel. SLIC algorithm is rather inaccurate for consideration of multi-dimensional tasks. Young’s algorithm enables representation of interface boundaries at arbitrary angles. Its major benefit is significant decreasing of artificial distortion. The researcher applied quadrilateral condition of intersection condition.

The introduced approach has numerous benefits such as absence of mixing theories and quantities associated with the whole cell, guarantee of element level conservation in momentum, energy, and mass, as well as separate momentum balancing for every material. At the same time, the application of this methodology is associated with the difficulties, such as possibility of the extreme volumes complexity due to the distinct velocities of materials.

My Response: This presentation depicts the unique approach for the multi-material arbitrary Lagrangian-Eulerian Hydrocodes that combines common elements (Lagrangian and Eulerian) and innovations (contact enforcement and mesh returned to original position). This research enables to improve the existing issues. However, it is not complete yet. I hope that the results of this study will be useful for me and for the science.

AWD Vehicle Engineering: Research and Engineering in New Directions

by Vantsevich V.V.

The goal of this presentation is to show that the design of power distribution system influences energy efficiency, stability, and mobility of a vehicle. The application of this knowledge is extremely important in the situations, when some of the vehicle wheels do not touch the ground. In such cases, it is necessary to change the split of power between the wheels for obtaining best operational properties. The speaker showed in the examples that the number of power dividing units is equal to the number of drive wheels, excluding one.

The researcher introduced these notions providing the examples of splitting the power and energy efficiency in 4 x 2, 4 x 4, 6 x 6 and 10 x 10 vehicles. He performed these researches for governmental institutions and international companies (for example, Ford), which are interested in the improvement of energy efficiency in their vehicles. The topic of splitting power is relevant because the researchers should clearly understand how to distribute the power in such a manner that it would enable to obtain the required energy efficiency of full and empty vehicles in different conditions. This knowledge is also applicable to several vehicles in convoy.

Additionally, the speaker introduced several dissertations, which disclose these ideas in details applying them to various vehicles in different operational conditions. The examples of these dissertations are the following: U.S. army Tardec – Convoy mobility / tire communication for energy efficiency; coupled dynamics of steering and driveline system; Agile tire slippage dynamics & control program. The aim of these dissertations is to investigate and depict the designation methods and control over the development of driveline system in order to be more close to the optimal power distribution between the wheels for providing the optimal properties at the higher level. Electric systems provide these abilities better than the mechanic ones.

My Response: This presentation provides generalized understanding regarding the extreme importance of drivelines variations and power distributions in various systems according to the examples of real-life researches and recent dissertations. This work encourages for the further investigation of possible methods for improving mobility, stability and energy efficiency of the vehicles and their groups in different conditions. I consider that the researches in this field will be rather useful for military and civilian purposes. I expect that I will be able to continue these researches in the future.


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