Master of Science (MS), Ohio University, 2009, Industrial and Systems Engineering (Engineering and Technology)

Consumption driven finite capacity multi independent item inventory planning problem is studied. Four models are generated to solve the problem to minimize the total cost of inventory carrying, ordering and backordering. The first model reflects the classic (s, Q) policy. Model 2 has a feature of dynamic order quantity which enables system to increase or decrease the amount of items released as production orders. Models 3 and 4 both have the features of dynamic order quantities and dynamic reorder points. Dynamic reorder point is used to allow a production order to be released before reorder point violation occurs with respect to the vulnerability of backlog. In addition system is protected from overproduction and excessive inventory built by limitation parameters for r and Q. As a result, significant amounts of backlogs are prevented and total cost reductions are obtained by Model-4 in highly variable demand environments.

Committee: Gursel A. Suer (Advisor); Diana Schwerha (Committee Member); Dusan Sormaz (Committee Member); Khurrum Bhutta (Committee Member) Subjects: Computer Science; Industrial Engineering; Information Systems; Systems Design

Master of Science, The Ohio State University, 2014, Anatomy

Data are desired that accurately represent the pediatric population for anthropomorphic test devices (ATD). Current pediatric ATDs are designed from scaled-down adult data, but their biofidelity is questioned. Because the use of pediatric cadavers is an ethical issue, different methods of testing are required to obtain data. This study will ultimately aid in leading to a more appropriate pediatric model of the shoulder. The data from this study will allow for (1) a comparison between adult volunteer and post mortem human subject (PMHS) quasi-static data, (2) a comparison between PMHS quasi-static and dynamic data, and (3) a comparison between dynamic lateral and oblique loading conditions. Side impacts of the PMHS were conducted in both quasi-static and dynamic manners. The impact was delivered in both purely lateral and oblique loading conditions for each test. With the application of a light load to the impacting shoulder in quasi-static testing, translational data were acquired from sensors fixed to the acromion processes and manubrium. Force data were also acquired. In dynamic testing, the PMHS was instrumented with a triaxial accelerometer block on each acromion process, the manubrium, and T1, strain gages placed on ribs 2–5 and the clavicles, and a chest band in the axillae. A 4.5 m/s impact was delivered through a pneumonic ram to one shoulder in the lateral loading condition while the opposing shoulder was impacted next at the same speed in the oblique loading condition. For all tests, the full girdle (acromion-to-acromion) deflection was calculated to determine overall deflection. A force-displacement plot was generated and stiffness values were calculated and were compared to previous studies. Injuries resulting from dynamic testing were included to demonstrate differences between lateral and oblique impacts. To date, quasi-static stiffness in the oblique direction, X-component (KX) and Y-component (KY), is very similar to adult volunteer data (KY = 10.3 ± (open full item for complete abstract)

Committee: John Bolte (Advisor) Subjects: Anatomy and Physiology; Biomechanics; Biomedical Engineering

Doctor of Philosophy, The Ohio State University, 2009, Computer Science and Engineering

In Java software, two important flexibility mechanisms are dynamic class loading and reflection. Unfortunately, the vast majority of static analyses for Java handle these features either unsoundly or overly conservatively. Our work targets techniques that will increase static analyses' ability to handle dynamic features in a more precise manner. Since many of these dynamic features rely on string values to specify their run-time behavior, some static analyses have used string analysis to aid in resolution of such features. There are two main concerns with this practice: (1) often a string analysis is not powerful enough to accurately model the needed string values, and (2) the computing costs associated with a precise string analysis make it impractical to incorporate into many static analysis frameworks. We address the first concern by presenting a novel semi-static approach for resolving dynamic class loading by combining static string analysis with dynamically gathered information about the execution environment. The insight behind the approach is that dynamic class loading often depends on characteristics of the environment that are encoded in various environment variables. An experimental evaluation on the Java 1.4 standard libraries shows that a state-of-the-art string analysis resolves only 28% of non-trivial sites while our approach resolves 74% of such sites. For string analysis to be useful for resolution of dynamic features, it has to exhibit practical cost in term of running time and memory usage. We propose several techniques to improve the scalability of string analysis. Our approach parallelizes a significant portion of the analysis, allowing it to take advantage of modern multi-core architectures. We also propose several extensions which reduce the amount of irrelevant information processed by the analysis. We applied an implementation of our proposed enhancements to 25 benchmark applications. For all benchmarks, our implementation realized a speedu (open full item for complete abstract)

Committee: Atanas Rountev PhD (Advisor); Timothy Long PhD (Committee Member); Neelam Soundarajan PhD (Committee Member) Subjects: Computer Science

Master of Science, The Ohio State University, 2009, Civil Engineering

This thesis presents internal shear strength data for a needle-punched geosynthetic clay liner obtained with a large direct shear device at four normal stresses. Previous research in the literature studying geosynthetic clay liner shear strengths utilized normal stress levels of 100 kPa or less and no research has been performed with stress levels above 520 kPa (75 psi). These stresses are acceptable for landfill cover systems, but are not representative of the stresses observed by landfill liner systems. Additionally, current literature lacks detailed information regarding cyclic testing of internal shear strength of geosynthetic clay liners. The research discussed in this thesis intends to address these issues by providing a comprehensive testing program of internal shear strength under both monotonic and cyclic loading at four normal stress loads of 141 kPa (20 psi), 348 kPa (50 psi), 692 kPa (100 psi) and 1382 kPa (200 psi). The largest normal stress is similar in magnitude to the normal stress experienced for a geosynthetic clay liner in the bottom cover system of a landfill. Monotonic and cyclic shear tests illustrate the effect of shear displacement rate R and displacement amplitude Δa on material response. Monotonic peak shear strengths first increased and then decreased as R was increased from 0.1 to 28,000 mm/min. The highest peak strengths occurred at R = 100 to 1,000 mm/min. R = 0.1 mm/min peak strengths were found to be generally conservative at each normal stress. Displacements at peak strength generally decreased with increasing normal stress. Residual shear strengths increased with increasing R for R ≥ 1 mm/min, whereas the reverse trend was observed for R < 1 mm/min. Higher normal stresses resulted in both higher peak strengths and higher residual strengths. The displacement necessary to reach peak decreased with increasing normal stress. During cyclic shear, specimens exhibited the highest strengths during the first cycle of testing, and then dec (open full item for complete abstract)

Committee: Patrick Fox PhD (Advisor); Harold Walker PhD (Committee Member); William Wolfe PhD (Committee Member) Subjects: Civil Engineering; Environmental Engineering

Master of Science (MS), Ohio University, 2010, Civil Engineering (Engineering and Technology)

This work studies the response of jointed plain concrete pavement to traffic loading as well as temperature variations, using the three-dimensional FE program EverFE2.24. The traffic loading is modeled using ODOT single axle dump truck rolling on top of the pavement, while the environmental loading is modeled using temperature measurements by thermocouples inserted throughout the depth of the slab. Picking a reference point in the temperature data, the change in stresses with respect to time has been computed and compared with the field data. Performing a fatigue analysis, the temperature is found to be considerably more detrimental to the concrete pavement compared to axle loads. Measurement of the surface temperature, especially in the top, is evaluated to be critical in convergence of EverFE2.24 model. The 3D FE program EverFE2.24 results followed the trend of the measured data from the field.

Committee: Shad Sargand PhD (Committee Chair); Teruhisa Masada PhD (Committee Member); Eric Steinberg PhD (Committee Member); Martin Mohlenkamp PhD (Committee Member) Subjects: Civil Engineering

Master of Science (MS), Ohio University, 2001, Civil Engineering (Engineering)

Evaluation of performance of composite bridge deck panels under static and dynamic loading and environmental conditions

Committee: Shad Sargand (Advisor) Subjects: Engineering, Civil

Master of Science, University of Akron, 2009, Mechanical Engineering

Dynamic pulse buckling, vibration and failure of laminated, composite cylindrical shells subjected to blast loading were studied. The dynamic response of the shells with orthotropic, symmetric, anti-symmetric and quasi-isotropic layups subjected to both uniform and asymmetric pressure pulse loading (side-on explosion) were examined by use of Fourier series and Lagrange's equation of motion. The solutions for the radial shell deformations were represented by Mathieu differential equations. Dynamic stability of the shells was determined from a Mathieu stability diagram. It was found that the stability of the shells were affected by lay-up, aspect ratio as well as impulse distribution. The stable vibration response of the orthotropic cylindrical shell with side-on explosion compared well with finite element solutions using an implicit dynamic analysis in ABAQUS Standard. First-ply failure of the orthotropic composite cylindrical shell was predicted using a modified Hashin-Rotem failure criterion. It was observed that the thinner shell were more likely to fail by dynamic instability, whereas the thicker shells were more likely to fail by first-ply failure.

Committee: Michelle S Hoo Fatt (Advisor) Subjects: Mechanical Engineering