Design of dissipative linear phase filters

Set of design curves eliminates work involved in designing linear phase filters by being normalized in such a way as to apply to low, band, and high-pass filters of any bandwidth. Similar curves for any number of poles are plotted by solving a system of simultaneous equations

An integral turbulent kinetic energy analysis of free shear flows

Mixing of coaxial streams is analyzed by application of integral techniques. An integrated turbulent kinetic energy (TKE) equation is solved simultaneously with the integral equations for the mean flow. Normalized TKE profile shapes are obtained from incompressible jet and shear layer experiments and are assumed to be applicable to all free turbulent flows. The shear stress at the midpoint of the mixing zone is assumed to be directly proportional to the local TKE, and dissipation is treated with a generalization of the model developed for isotropic turbulence. Although the analysis was developed for ducted flows, constant-pressure flows were approximated with the duct much larger than the jet. The axisymmetric flows under consideration were predicted with reasonable accuracy. Fairly good results were also obtained for the fully developed two-dimensional shear layers, which were computed as thin layers at the boundary of a large circular jet

The wall shear stress produced by the normal impingement of a jet on a flat surface

A method for the theoretical determination of the wall shear stress under impinging jets of various congurations is presented. Axisymmetric and two-dimensional incompressible jets of a wide range of Reynolds numbers and jet heights are considered. Theoretical predictions from this approach are compared with available wall shear stress measurements. These data are critically evaluated based on the method of measurement and its applicability to the boundary layer under consideration. It was found that impingement-region wall shear stress measurements using the electrochemical method in submerged impinging liquid jets provide the greatest accuracy of any indirect method. A unique wall shear stress measurement technique, based on observing the removal of monosized spheres from well-characterized surfaces, was used to conrm the impinging jet analysis presented for gas jets. The technique was also used to determine an empirical relation describing the rise in wall shear stress due to compressibility eects in impinging high-velocity jets

Unintended Consequences of Public Policy and Government Regulation on Supply Chain Structure, Conduct, and Performance

Supply chains, and the firms within them, change their behaviors in response to industry conditions so they can provide efficiency, effectiveness, strategic enablement, and customer utility. Social and economic policies enacted to promote social welfare by correcting market failures can alter these conditions. While these policies may serve their intended purposes, they may also create unintended consequences that may make managing logistics, operations, and supply chains more challenging. This dissertation contributes to the nascent body of knowledge concerning the intended and unintended consequences of policy on supply chain management by examining three unique contextual settings using different methodologies and levels of analysis. In the first essay, I examine the impacts of relationship-focused regulations on supply chain collaboration. Using a grounded theory approach, I theorize new barriers to collaboration unique to this regulatory context using data from multiple interviews with executives from suppliers and distributors in the beer industry supply chain. I find that regulations meant to promote social welfare by constraining the flow of alcohol to consumer also constrain choice in supply chain relationships that negatively affect supply chain collaboration. In the second essay, I examine how capacity-limiting structural regulation in healthcare, specifically certificate of need (CON) laws, interacts with case complexity to affect hospital operational performance. Using a hybrid estimation approach to analyze a unique data set collected from multiple sources, I tested a conceptual model developed using the structure-conduct-performance (SCP) framework and the complex adaptive systems (CAS) perspective. I find that indicate that CON does reduce costs but also worsens quality. I also find that these relationships are intensified by case complexity. In the third essay, I examine whether nuclear verdicts over $10 million resulting from harm caused by large truck crashes result in improved industry-level motor carrier safety performance. Drawing on institutional theory to hypothesize the effects of nuclear verdicts on safety performance and insurance spending. I test these hypotheses using autoregressive distributed lag time series econometric models. I find that nuclear verdicts may result in improvements in industry safety but may also result in increased insurance spending. Collectively, these essays demonstrate multiple perspectives of how policies can affect supply chain behaviors and performance at the individual-, firm-, and industry-level that may be undesirable or unexpected. Findings from these essays offer important insights for researchers, practitioners, and policymakers

A design methodology for a low volume road bridge alternative: steel beam precast units

Recent reports have indicated that 23.5 percent of the nation\u27s highway bridges are structurally deficient and 17.7 percent are functionally obsolete. A significant number of these bridges are on the Iowa secondary road system where over 86 percent of the rural bridge management responsibilities are assigned to the counties. Some of the bridges can be strengthened or otherwise rehabilitated, but many more are in need of immediate replacement;In a recent investigation, HR-365 Evaluation of Bridge Replacement Alternatives for the County Bridge System several types of replacement bridges that are currently being used on low volume roads were identified. It was also determined that a large number of counties (69 percent) have the ability and are interested in utilizing their own forces to design and construct short span bridges. In reviewing the results from HR-365, a new bridge replacement concept was developed;This concept involves the fabrication of precast units (two steel beams connected by a concrete slab) by county work forces. Deck thickness is limited so that the units can be fabricated at one site and then transported to the bridge site where they are connected and the remaining portion of the deck placed. Since the bridge is primarily intended for use on low-volume roads, the precast units can be constructed with new or used beams;In the experimental portion of the investigation, there were three types of static load tests: small scale connector tests, handling strength tests, and service and overload tests of a model bridge. Three finite element models for analyzing the bridge in various states of construction were also developed and extrapolated to various bridge configurations;Small scale connector tests were completed to determine the best method of connecting the precast double-T (PCDT) units. Handling strength tests on an individual PCDT unit were performed to determine the strength and behavior of the precast unit in this configuration;The majority of the testing was completed on the model bridge (L = 9,750 mm (32 ft), W = 6,400 mm (21 ft)) which was fabricated using the precast units developed. Some of the variables investigated in the model bridge tests were number of connectors required to connect adjacent precast units, contribution of diaphragms to load distribution, influence of position of diaphragms on bridge strength and load distribution, and effect of cast-in-place portion of deck on load distribution. In addition to the service load tests, the model bridge was also subjected to overload conditions. Using the finite element models developed, one can predict the behavior and strength of bridges similar to the laboratory model as well as design them;Based on the experimental investigation and analytical models that were developed to describe the model bridge behavior, a design methodology for the PCDT bridge has been developed for the bridge superstructure. This design methodology has been programmed in to an easy to use program that allows quick and easy bridge design. A pre-prepared set of plans has also been developed that can be used to construct the PCDT bridge superstructure

High school chemistry students\u27 learning of the elements, structure, and periodicity of the periodic table: contributions of inquiry-based activities and exemplary graphics

The main research question of this study was: How do selected high school chemistry students\u27 understandings of the elements, structure, and periodicity of the Periodic Table change as they participate in a unit study consisting of inquiry-based activities emphasizing construction of innovative science graphics? The research question was answered using a multiple case study/mixed model design which employed elements of both qualitative and quantitative methodologies during data collection and analyses. The unit study was conducted over a six-week period with 11th-grade students enrolled in a chemistry class. A purposive sample of six students from the class was selected to participate in interviews and concept map coconstruction (Wandersee & Abrams, 1993) periodically across the study. The progress of the selected students of the case study was compared to the progress of the class as a whole. The students of the case study were also compared to a group of high school chemistry students at a comparative school. The results show that the students from both schools left traditional instruction on the periodic table (lecture and textbook activities) with a very limited understanding of the topic. It also revealed that the inquiry-based, visual approach of the unit study helped students make significant conceptual progress in their understanding of the periodic table. The pictorial periodic table (which features photographs of the elements), used in conjunction with the graphic technique of data mapping, enhanced students understanding of the patterns of the physical properties of the elements on the periodic table. The graphic technique of compound mapping helped students learn reactivity patterns between types and groups of elements on the periodic table. The recreation of the periodic table with element cards created from the pictorial periodic table helped students progress in their understanding of periodicity and its key concepts. The Periodic Table Literacy Rubric (PTLR) proved to be a valuable tool for assessing students’ conceptual progress, and helped to identify a critical juncture in the learning of periodicity. In addition, the PTLR rubric\u27s historical-conceptual design demonstrates how the history of science can be used to inform today\u27s science teaching

PREDICTORS OF READINESS TO INITIATE INSULIN THERAPY IN PATIENTS WITH TYPE 2 DIABETES WHEN ORAL MEDICATIONS FAIL TO CONTROL HYPERGLYCEMIA

Type 2 diabetes (T2DM) has reached epidemic levels worldwide during the past two decades. It affects nearly 26 million adults in the U.S. Advances in both the treatments for T2DM and guidelines for its optimal management are extensive. Despite these advances, barely half of type 2 diabetics achieve recommended glycemic targets. Specific Aims: The specific aims were to: Describe the available research on clinical inertia and interventions that have been implemented to reduce it. Analyze various behavioral theories that explain and predict self-care practices in diabetes in order to develop a conceptual model on which to base an investigation of predictors of readiness to initiate insulin therapy in type 2 diabetics. Determine predictors of readiness to initiate insulin therapy in patients with T2DM when oral medications fail to control hyperglycemia using the conceptual model based on Self-Determination Theory (SDT) as a framework. Results: A review of research articles published from 1990 to 2010 concluded that clinical inertia of primary care providers treating T2DM resulted in a majority of patients experiencing unnecessary chronic uncontrolled hyperglycemia. Behavioral theories were analyzed for their ability to predict self-care behaviors in type 2 diabetics. A conceptual model was developed based on the major constructs of SDT in order to guide the design of study to investigate predictors of readiness to begin insulin therapy in T2DM. Finally, a descriptive, correlational study was performed to determine readiness to initiate insulin therapy in patients with T2DM when oral medications fail to control hyperglycemia. Results of the study revealed that participants who had a friend or family using insulin were 5.5 times more likely to rate their readiness to initiate insulin as high than those who had neither (p=.020). In addition, those with greater negative beliefs and attitudes toward insulin therapy were more likely to rate their readiness to initiate insulin as low (p=.012). A majority (58%) of participants rated their readiness to begin insulin therapy as immediate if it would give them better control over their hyperglycemia. The study also confirmed findings from previous studies that clinical inertia was present in this setting