Comparison of Staggered Grid Finite Difference Schemes for Ultrasound Simulation in Curving Composites

The optimization of ultrasonic nondestructive evaluation (NDE) simulation tools for composites has the potential to reduce both individual part inspection time and overall certification time for composite parts and structures. Inspection guidance based on simulation provides increased confidence in the veracity of inspection results in addition to time reductions. This paper outlines ongoing work targeted to advance this objective through the use of finite difference (FD) simulation techniques formulated for composite structures with realistic geometries. Two staggered grid explicit FD schemes which show promise for this purpose are assessed: the Lebedev FD scheme and the rotated staggered grid (RSG) FD scheme. Algorithmic points which provide challenges for complex geometries are addressed, in particular handling of traction free surfaces and bi-material interfaces present at lamina boundaries. Code execution time estimates are performed as well to guide feasible domain sizes relative to algorithm choice and available hardware. Three test cases are simulated: a delaminated plate, a cylinder, and a triclinic lamina. These tests demonstrate that the Lebedev FD scheme needs additional work to handle inter-laminar interfaces and traction free boundaries in the presence of stair-stepping approximations. In contrast, the simple structure of the RSG unit cell makes it more straightforward to construct a 3D simulation technique for curved composite laminates

The Pleistocene Geology of the Middle ·Portion of the Elkhorn River Valley

The present report is a physiographic and paleontologic approach to the Pleistocene history of a portion of the Elkhorn River Valley in parts of Dodge, Cuming and Stanton counties in northeastern Nebraska. The area is important for correlation of deposits between the glacial and periglacial regions. Some of the critical stratigraphic units used for correlation in the Pleistocene of these regions are present in close association with the tills and contain fossils which make possible reliable statements on contemporaneity of deposits. The subsequent geologic history and present physiographic expression of this area have been greatly controlled and influenced by the Nebraskan and Kansan tills. It is hoped that this study will form a basis for further investigation of an area for which the geology has been largely unreported. J. E. Todd in 1899 described several exposures in the vicinity of West Point which are incorporated into this report. A. L. Lugn (1935) reported a gravel pit section within the borders of this report east of Norfolk and made general comments on Pleistocene deposits along the Elkhorn River to the east. The area has not been test drilled and, therefore, subsurface information is most limited. In a few cases information from commercial water-well drillers and others has been utilized. Fortunately, the lower part of the Elkhorn drainage has been investigated and reported (Lueninghoener 1947) and this information facilitates this present work. Lueninghoener\u27s treatment of the lower Platte River region presents the geologic information in a most satisfactory way. For this reason and because it will be convenient for future work in these contiguous areas, this report follows the general method of presentation employed in his paper

Problems of Paleontological Preservation in Iowa

A brief review of vertebrate paleontological work in Iowa reveals an early utilization of fossils in Pleistocene studies followed by a lapse in collecting and research until revived during the past decade. Legal measures enacted to protect paleontological materials have, in the opinion of many paleontologists, resulted in numerous federal and state regulations which are unrealistic and a hindrance to scientific endeavor. Efforts to modify or remove federal rules and regulations governing fossils are discussed. Legal restrictions do not constitute the primary problems of paleontological conservation in many states, including Iowa. Instead, the problems are those of (1) public education regarding the scientific value of fossils, (2) gaining the cooperation of individuals in reporting discoveries to qualified institutions, and (3) financing and handling the collection, preparation, curating, and study of paleontological specimens. These problems may be partially solved through sensible legislation, distribution of popular information about fossils, and encouraging nonprofessionals to assist in the program

CEO Compensation, Backdated Stock Options, and Compensation Committees

CEO compensation in U. S. based companies has undergone considerable scrutiny in recent years. Among the common observations are that U. S. executives are highly paid relative to those of other countries and that the disparities in compensations are increasing over time. In this study, we investigate the effects that backdated stock options, compensation committee structure and process, and ownership factors have on levels or executive compensation. Combining agency and organizational theory perspectives, we find CEO compensation positively associated with the presence of backdated stock options, few large-block stockholders, and small compensation committees

Fiber Optic Guided Wave Sensors For Structural Health Monitoring

Risks and costs associated with aging infrastructure have been mounting, presenting a clear need for innovative damage monitoring solutions. One of the more powerful damage monitoring approaches involves using ultrasonic guided waves which propagate through a structure and carry damage-related information to permanently bonded sensors. Ultrasonic fiber-optic sensors are one of the most promising technologies for this application: they are immune to electromagnetic interference, present no ignition hazard, and transmit their data over tens of kilometers. However, before they can be widely employed, several limitations need to be overcome: poor sensitivity, unidirectional sensing, and loss of ultrasonic functionality due to static loading. In this dissertation, these limitations were addressed using a mechanical design approach, combining a mechanical resonator with a fiber-optic sensing element. Based on this principle, two fiber-optic sensors were developed: a ring sensor and a wave-absorbing acoustic black hole sensor. Sensitivity improvements up to 28 dB were achieved through mechanical resonance. Prototypes were shown to be insensitive to static loads and detected waves omnidirectionally. The sensors were also miniaturized and designed to be sensitive to different types of wave motion; the ring sensor was sensitive to out-of-plane motion only, and the acoustic black hole sensor was sensitive to both in-plane and out-of-plane motion. The sensor development process is presented from concept sketch to modeling, design, verification, optimization, and calibration

The Nominating Committee As An Antecedent of Effective Corporate Governance

In this paper, we examine a possible antecedent to board effectiveness – the presence of a nominating committee. We argue that director cooptation by CEOs, and therefore ineffectual governance, may result from allowing CEOs to appoint sympathetic directors. Thus, because outside independent board members are more likely to be effective in their roles as monitors of the CEO, and because such members are more likely to have been selected by nominating committees, measures of board effectiveness should be positively associated with the presence of a nominating committee. Our results are largely consistent with our hypotheses, and are thus instructive in the design of optimal governance mechanisms. We find that firm profitability, frequency of compensation committee meetings, compensation committee size, and CEO experience of compensation committee members are all higher among firms with nominating committees

Emotional Intelligence: A Comparative Analysis of Two College Business Administration Programs

A comparative study of two universities explores the emotional intelligence (EI) of students in two College of Business Administration (CBA) programs with contrasting missions, visions, and populations. This study investigates the extent to which EI test scores and sub-scales varied among two CBA student populations. Despite the differences between the two universities, no differences were evident in the EI abilities among the two CBA student populations. Further research will explore the extent to which universities can impact EI short and long-term through classroom interventions

A Late Wisconsin Giant Beaver in Northern Iowa

Few discoveries of giant beaver, Castoroides, remains have been made in Iowa and these have usually been found under circumstances precluding determination of their geologic ages. The specimen reported herein from near Garner, Hancock County, Iowa, was recovered from a peat bed which lies within the border of a late Wisconsin, probably Cary, terminal moraine. According to radiocarbon dates recently announced for organic muck overlying till in a nearby peat bog the minimum date for the till would have to be approximately 12,000 b.p., thus older than Two Creeks interstadial. This find, places the giant beaver in Iowa during Two Creeks time or possibly slightly later. This is the latest survival yet reported for this form in Iowa and compares favorably with its terminal date reported in Ohio. Other giant beaver finds in Iowa are described and some general statements are made about the development of this animal

Preliminary Geomorphological Studies of the Lime Creek Area & Preliminary Report on the Lime Creek Sites: New Evidence of Early Man in Southwestern Nebraska

PALEONTOLOGICAL and archaeological discoveries were made near Cambridge, Nebraska, by the University of Nebraska State Museum field party in the spring of 1947 (Schultz and Frankforter, 1948, pp. 279-280) . Fossils and artifacts were found in situ at the base of a fifty-foot terrace on Lime Creek (University of Nebraska State Museum Localities Ft-41 and Ft-42) and on Medicine Creek just below the mouth of Lime Creek (Ft-50). Lime Creek is located (Fig. 1) in southwestern Nebraska in the southeastern part of Frontier County. It is a tributary of Medicine Creek which in turn is a tributary to the Republican River. The paleontological material from this site reveals new information on the Pliocene-Pleistocene boundary line problem-a fundamental problem in the over-all Pleistocene history of the region. A series of five topographic benches\u27 or terraces is developed (see Figs. 4 and 5) along the Republican River and its tributaries. Field studies indicate that these represent cycles of alluviation interrupted by erosional periods. A similarly developed series of terrace-fills in a contiguous region has been provisionally correlated with the sub-stages of the Wisconsin stage of Pleistocene continental glaciation (Lueninghoener, 1946). I N THE natural course of paleontological and geological explorations in Pleistocene deposits the fossil hunter often discovers evidence of man\u27s early occupation of North America. Artifacts and other cultural evidence are frequently found in direct association with the fossilized bones of various species of animals. Some of these remains represent extinct species while others can be referred to those found in North America today. Much is yet to be learned concerning the stratigraphic distribution of vertebrate life of the Pleistocene and the time of extinction of certain forms, but new evidence (see Schultz, Lueninghoener, and Frankforter, Part 1, Fig. 6 of this report) is constantly being accumulated which aids in clarifying the picture. In 1932 the University of Nebraska State Museum commenced a research program (Lugn, 1934, pp. 319-356; Schultz, 1934, pp. 357-393) in the field and laboratory relating to the stratigraphic distribution of the Pleistocene mammals and the study of extinction in the Great Plains. Since that time the major portion of the Museum\u27s field work has been directed to problems relating to the Pleistocene. The significance of terraces to the problems has been pointed out in Part 1 of this report (also in Schultz and Stout, 1945; 1948)

An Empirical Test of Stewardship Theory

This study tests the model of Davis, Schoorman, and Donaldson (1997) that proposed determinants of a company’s governance structure. In particular, we focus on the stewardship theory aspects of the model and its ability to predict the presence of a stewardship-orientation CEO at publicly listed U.S. companies. Using survey based data obtained from CEOs and directors of 100 companies in a match-pair design, we identified three variables that predicted the occurrence of stewardship-oriented behaviors by the company’s CEO. These results lend support for the model’s ability to predict the conditions under which stewardship-oriented individuals become CEOs