Thesis (M. Sc.)--University of Hong Kong, 1997. / Includes bibliographical references (leaf 56-58).

Thesis (M.S.)--University of Wisconsin--Madison, 1981. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 61-63).

Thesis (M.S.)--Ohio University, March, 1997. / Title from PDF t.p.

Thesis (M.S.)--Ohio University, August, 1995. / Title from PDF t.p.

No description available.

Environmental testing is essential to certify systems to withstand the harsh dynamic loads they may experience in their service environment or during transport. For example, satel- lites are subjected to large vibration and acoustic loads when transported into orbit and need to be certified with tests that are representative of the anticipated loads. However, tra- ditional certification testing specifications can consist of sequential uniaxial vibration tests, which have been found to severely over- and under-test systems needing certification. The recently developed Impedance-Matched Multi-Axis Test (IMMAT) has been shown in the literature to improve upon traditional environmental testing practices through the use of multi-input multi-output testing and impedance matching. Additionally, with the use of numerical models, predictive simulations can be performed to determine optimal testing pa- rameters. Developing an accurate numerical model, however, requires precise knowledge of the system's dynamic characteristics, such as boundary conditions or material properties. These characteristics are not always available and would also require additional testing for verification. Furthermore, some systems may be extremely difficult to model using numerical methods because they contain millions of finite elements requiring impractical times scales to simulate or because they were fabricated before mainstream use of computer aided drafting and finite element analysis but are still in service. An alternative to numerical modeling is data-driven modeling, which does not require knowledge of a system's dynamic characteris- tics. The Continuous Residue Interpolation (CRI) method has been recently developed as a novel approach for building data-driven models of dynamical systems. CRI builds data- driven models by fitting smooth, continuous basis functions to a subset of frequency response function (FRF) measurements from a dynamical system. The resulting fitted basis functions can be sampled at any geometric location to approximate the expected FRF at that location. The research presented in this thesis explores the use of CRI-derived data-driven models in predictive simulations for the IMMAT performed on a Euler-Bernoulli beam. The results of the simulations reveal that CRI-derived data-driven models of a Euler-Bernoulli beam achieve similar performance when compared to a finite element model and make similar decisions when deciding the excitation locations in an IMMAT. / Master of Science / In the field of vibrations testing, environmental tests are used to ensure that critical devices or structures can withstand harsh vibration environments. For example, satellites experience harsh vibrations and damaging acoustics that are transferred from it's rocket transport vehicle. Traditional environmental tests would require that the satellite be placed on a vibration table and sequentially vibrated in multiple orientations for a specified duration and intensity. However, these traditional environmental tests do not always produce vibrations that are representative of the anticipated transport or operational environment. Newly developed methods, such as the Impedance-Matched Multi-Axis Test (IMMAT) methods achieves representative test results by matching the mounting characteristics of the structure during it's transport or operational environment and vibrating the structure in multiple directions simultaneously. An IMMAT can also be optimized by using finite element models (FEM), which approximate the device to be tested with a discrete number of small volumes whose physics are described by fundamental equations of motion. However, an FEM can only be used if it's dynamic characteristics are sufficiently similar to the structure undergoing testing. This can only be achieved with precise knowledge of the dynamical properties of the structure, which is not always available. An alternate approach to an FEM is to use a data-driven model. Because data-driven models are made using data from the system it is supposed to describe, dynamical properties of the device are pre-built in the model and is not necessary to approximate them. Continuous Residue Interpolation (CRI) is a recently developed data-driven modeling scheme that approximates a structure's dynamic properties with smooth, continuous functions updated with measurements of the input-output response dynamics of the device. This thesis presents the performance of data-driven models generated using CRI when used in predictive simulations of an IMMAT. The results show that CRI- derived data-driven models perform similarly to FEMs and make similar predictions for optimal input vibration locations.

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

Chloride diffusivity in high performance concrete is influenced by the exposure environment, aside from the concrete mixture properties like, water to cementitious ratio (w/cm) and presence of add-on pozzolans. In this study, a set of concrete specimens (eleven-different concrete mixtures) were cast and exposed to three different environmental conditions (Tidal, Splash and Barge) in which the solution was seawater or brackish water. These exposures simulated environmental field conditions. After the specimens had been wet cured for 32 days (on average), the specimens were exposed to three different field simulation conditions for up to 54 months. The specimens under the field simulated conditions were cored at 6, 10, 18, 30 and 54 months at four elevations and then the chloride profiles were obtained from the cores. The apparent diffusivity values for each profile were calculated based on Fick’s 2nd law. Then, the aging factor “m” was calculated by regression analysis of the diffusivity values vs. time (days) plotted in the log10-log10 scale. This was done for samples exposed to the three different exposure conditions and then the results were compared side-by-side. First, the “m” values were calculated using the exposure duration. Then, to study the effect of including the curing time on “m” value, the curing time was added to the exposure time and a new calculation and “m” value was obtained and compared with the previous results. Moreover, upon inspecting the chloride diffusivity values vs. time plots, it was observed that in some cases, a number of data points showed significantly higher or lower values in comparison with the rest of the data points. It was decided to recalculate the “m” values for these cases, and to only use selected data points instead of all data points (i.e., remove outlier data points). In terms of chloride diffusivity value, it was found that in most cases the specimens with higher water to cementitious (w/cm) ratio showed higher diffusivity, as expected. Further, the presence of pozzolans had a noticeable impact on the chloride diffusivity by decreasing the diffusion rate due to microstructure changes that occurred with time. In terms of “m” values, the result for the field simulated conditions showed a range of “m” values dependent on the specimen’s mixture composition and the elevation at which the specimens were cored. It was observed that the chloride diffusivity declined with time and after a certain amount of time (in this research, almost after 30 months) the diffusivity reduction became small and a transition in the slope of the diffusivity trend appeared in a number of cases. After the transition, the diffusivity trend reached either a plateau zone or continued with a significantly lower slope, depending on the time, composition and exposure. It was found that the specimens under tidal and splash field simulation conditions that had only fly ash in their mixtures showed higher “m” values when compared with samples that contained fly ash and silica fume or fifty percent slag. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2019. / FAU Electronic Theses and Dissertations Collection

Environmental testing industry is a kind of knowledge industry, also a kind of technical service industry. People who engaged in environmental testing services are all knowledge workers. A knowledge worker¡¦s benefit to a company could be in the form of developing business intelligence or variety of other important gains in knowledge that aid the business. It is necessary for a company to build up its human resource management system(HRMS) in such competitive market nowadays. Peter Drucker(1989) pointed that the quality, performance, and achievement of management people is the critical issue for deciding the fate of a company. Management people is the key to success, so how to strengthen and develop the competence of management people is very important. Human resource is the intellectual capital of knowledge industry. It also could be the capital of technical service industry. Purpose of the study is to realize what should be the competence of management people and how will it be of help to the HRMS within the case environmental laboratory. It could maximize the effectiveness of human resource investment and enhance the selecting, cultivating, retaining, and positioning people in an innovation way. People who take the advantage of their management competence will positively bring in sustainable growth in profitability. Through reviewing of the essays and theses, induction of the interview information, the writer found that the conceptual difference is existence in reality of training and promotion sub-system between management people and its existing HRMS. Management people need an integrated training sub-system for developing their management competence. And, they need a clear, definite, and quantitative sub-system for promotion appraisal. Most of the interviewee were sure these two sub-system could encourage and retain good people for the company. If the case company could improve these two sub-system of the whole HRMS, it will acquire the consistency of both people and company as well as the synergistic effects. The results and suggestions of the study is wishing to benefit environmental testing industry by enhancing the management competence. Furthermore, it is wishing to benefit all other testing related industries as well.

A proper understanding of the dynamics of a mechanical system is crucial to ensure the highest levels of performance. The understanding is frequently determined through modeling and testing of components. Modeling provides a cost effective method for rapidly developing a knowledge of the system, however the model is incapable of accounting for fluctuations that occur in physical spaces. Testing, when performed properly, provides a near exact understanding of how a pat or assembly functions, however can be expensive both fiscally and temporally. Often, practitioners of the two disciplines work in parallel, never bothering to intersect with the other group. Further advancement into ways to fuse modeling and testing together is able to produce a more comprehensive understanding of dynamic systems while remaining inexpensive in terms of computation, financial cost, and time. Due to this, the goal of the presented work is to develop ways to merge the two branches to include test data in models for operational systems. This is done through a series of analytical and experimental tasks examining the boundary conditions of various systems. The first venue explored was an attempt at modeling unknown boundary conditions from an operational environment by modeling the same system in known configurations using a controlled environment, such as what is seen in a laboratory test. An analytical beam was studied under applied environmental loading with grounding stiffnesses added to simulate an operational condition and the response was attempted to be matched by a free boundaries beam with a reduced number of excitation points. Due to the properties of the inverse problem approach taken, the response between the two systems matched at control locations, however at non-control locations the responses showed a large degree of variation. From the mismatch in mechanical impedance, it is apparent that improperly representing boundary conditions can have drastic effects on the accuracy of models and recreational tests. With the progression now directed towards modeling and testing of boundary conditions, methods were explored to combine the two approaches working together in harmony. The second portion of this work focuses on modeling an unknown boundary connection using a collection of similar testable boundary conditions to parametrically interpolate to the unknown configuration. This was done by using data driven models of the known systems as the interpolating functions, with system boundary stiffness being the varied parameter. This approach yielded near identical parametric model response to the original system response in analytical systems and showed some early signs of promise for an experimental beam. After the two conducted studies, the potential for extending a parametric data driven model approach to other systems is discussed. In addition to this, improvements to the approach are discussed as well as the benefits it brings. / Master of Science / A proper understanding of the dynamics of a mechanical system in a severe environment is crucial to ensure the highest levels of performance. The understanding is frequently determined through modeling and testing of components. Modeling provides a cost-effective method for rapidly developing a knowledge of the system; however, the model is incapable of accounting for fluctuations that occur in physical spaces. Testing, when performed properly, provides a near exact understanding of how a pat or assembly functions, however, can be expensive both fiscally and temporally. Often, practitioners of the two disciplines work in parallel, never bothering to intersect with the other group and favoring one approach over the other for various reasons. Further advancement into ways to fuse modeling and testing together can produce a more comprehensive understanding of dynamic systems subject to environmental excitation while remaining inexpensive in terms of computation, financial cost, and time. Due to this, the presented work aims to develop ways to merge the two branches to include test data in models for operational systems. This is done through a series of analytical and experimental tasks examining the boundary conditions of various systems and attempting to replicate the system response using inverse approaches at first. This is then proceeded by modeling boundary stiffnesses using data-driven modeling and parametric modeling approaches. The validity and impact these methods may have are also discussed.