The effect of near-surface metallurgy on the machinability of cast iron

The increasing performance and durability of cutting tool inserts have created metallurgical challenges for production foundries to produce near-net shaped castings within strict dimensional tolerances. In order for foundries to take full advantage of the increased cutting speed capabilities, it becomes necessary to reduce machining allowances and produce much more stable casting surfaces. To accomplish this, a better understanding of the complex microstructures formed within the first 0.120 in. (3 mm) of the mold/metal interface (as-cast surface) is necessary. The goal of the work presented here was to examine the microstructures formed in the near-surface region of gray iron castings, determine what was responsible for formation, and how these microstructures behaved during the machining process. A series of experiments were performed to evaluate the effect of graphite flake morphology, matrix microstructure, and alloying elements on near-surface machinability. Three-dimensional cutting forces, quantitative metallography, and high-speed photographic measurements were used to evaluate the behavior of flake graphite, ferrite, coarse/dense pearlite, steadite, and carbides during the machining process. Data from the experiments also indentified the importance of inoculation practice, cooling rate, and mold sand properties on the final near-surface microstructure/machinability behavior. A case study was then performed for industrial brake rotor castings produced from class 35 gray cast iron, in which diagnosis of a machinability problem proved to be near-surface microstructure related. It was found that a combination of mold sand properties and inoculation practice were responsible for surface free-ferrite/graphite morphology microstructural defects --Abstract, page iii

An Analysis of “Little Bat” in the Opera Susannah

Using both a unique character development and an interweaving of the main motives found throughout the opera, Little Bat emerges as one of the prominent characters in the opera Susannah

A Game-Theoretic Model of Monkeypox to Assess Vaccination Strategies

A Game-Theoretic Model of Monkeypox to Assess Vaccination Strategies Sri Vibhaav Bankaru, Depts. of Biomedical Engineering, Math, & Chemistry, Samuel Kossol, William Hou, & Parsa Mahmoudi, with Dr. Jan Rychtar, Dept. of Mathematics Monkeypox (MPX) is a zoonotic disease similar to smallpox. Its fatality rate is about 11% and it is endemic to the Central and West African countries. In this paper, we analyze a compartmental model of MPX dynamics. Our goal is to see whether MPX can be controlled and eradicated by voluntary vaccinations. We show that there are three equilibria - disease free, fully endemic and previously neglected semi-endemic (with disease existing only among humans). The existence of semi-endemic equilibrium has severe implications should the MPX virus mutate to increased viral fitness in humans. We find that MPX is controllable and can be eradicated in a semi-endemic equilibrium by vaccination. However, in a fully endemic equilibrium, MPX cannot be eradicated by vaccination alone.https://scholarscompass.vcu.edu/uresposters/1296/thumbnail.jp

Rotorcraft aeroelastic stability

Theoretical and experimental developments in the aeroelastic and aeromechanical stability of helicopters and tilt-rotor aircraft are addressed. Included are the underlying nonlinear structural mechanics of slender rotating beams, necessary for accurate modeling of elastic cantilever rotor blades, and the development of dynamic inflow, an unsteady aerodynamic theory for low-frequency aeroelastic stability applications. Analytical treatment of isolated rotor stability in hover and forward flight, coupled rotor-fuselage stability in hover and forward flight, and analysis of tilt-rotor dynamic stability are considered. Results of parametric investigations of system behavior are presented, and correlation between theoretical results and experimental data from small and large scale wind tunnel and flight testing are discussed

Faculty Concert

This is the program for the faculty concert featuring director Mr. William Lyon Thickstun, soprano Miss Lottie May Dewey, pianist Miss Maude Sweeney, pianist Miss Sue Belle Wood, reader and violinist Mrs. Townes Randolph Leigh, and pianist Mr. James William Taylor. This concert took place on October 12, 1908

Survey of Army/NASA rotorcraft aeroelastic stability research

Theoretical and experimental developments in the aeroelastic and aeromechanical stability of helicopters and tilt-rotor aircraft are addressed. Included are the underlying nonlinear structural mechanics of slender rotating beams, necessary for accurate modeling of elastic cantilever rotor blades, and the development of dynamic inflow, an unsteady aerodynamic theory for low frequency aeroelastic stability applications. Analytical treatment of isolated rotor stability in hover and forward flight, coupled rotor-fuselage stability are considered. Results of parametric investigations of system behavior are presented, and correlations between theoretical results and experimental data from small- and large-scale wind tunnel and flight testing are discussed

LAMI: A gesturally controlled three-dimensional stage Leap (Motion-based) Audio Mixing Interface

Interface designers are increasingly exploring alternative approaches to user input/control. LAMI is a Leap (Motion-based) AMI which takes user’s hand gestures and maps these to a three-dimensional stage displayed on a computer monitor. Audio channels are visualised as spheres whose Y coordinate is spectral centroid and X and Z coordinates are controlled by hand position and represent pan and level respectively. Auxiliary send levels are controlled via wrist rotation and vertical hand position and visually represented as dial-like arcs. Channel EQ curve is controlled by manipulating a lathed column visualisation. Design of LAMI followed an iterative design cycle with candidate interfaces rapidly prototyped, evaluated and refined. LAMI was evaluated against Logic Pro X in a defined audio mixing task

HIV-1 Tat exacerbates lipopolysaccharide-induced cytokine release via TLR4 signaling in the enteric nervous system

The loss of gut epithelium integrity leads to translocation of microbes and microbial products resulting in immune activation and drives systemic inflammation in acquired immunodeficiency syndrome (AIDS) patients. Although viral loads in HIV patients are significantly reduced in the post-cART era, inflammation and immune activation persist and can lead to morbidity. Here, we determined the interactive effects of the viral protein HIV-1 Tat and lipopolysaccharide (LPS) on enteric neurons and glia. Bacterial translocation was significantly enhanced in Tat-expressing (Tat+) mice. Exposure to HIV-1 Tat in combination with LPS enhanced the expression and release of the pro-inflammatory cytokines IL-6, IL-1β and TNF-α in the ilea of Tat+ mice and by enteric glia. This coincided with enhanced NF-κB activation in enteric glia that was abrogated in glia from TLR4 knockout mice and by knockdown (siRNA) of MyD88 siRNA in wild type glia. The synergistic effects of Tat and LPS resulted in a reduced rate of colonic propulsion in Tat+ mice treated with LPS. These results show that HIV-1 Tat interacts with the TLR4 receptor to enhance the pro-inflammatory effects of LPS leading to gastrointestinal dysmotility and enhanced immune activation

Style and Technique in Selected Works for Tuba and Electronic Prepared Tape: A Lecture Recital, Together with Three Recitals of Selected Works of V. Persichetti, A. Capuzzi, E. Gregson, W. Ross, N.K. Brown, and Others

This study explores general stylistic characteristics of a sample of frequently performed works for solo tuba with prepared tape. Preliminary material includes a brief overview of the status of electronic music in the solo tuba repertoire as well as a short survey of the development of electronic music

A Union of Religion and Politics: Ngawang Tsültrim as Tibetan Regent and Imperial Preceptor

My dissertation is a study of the life of Ngawang Tsültrim (1721-1791), with a primary focus on his career as sikyong or regent of Tibet (reigning 1777-1786, 1790-1791), and a secondary focus on his religious positions and his service to the Qing emperor. By studying his life, I have sought to understand how and why regents came to serve as substitute rulers for the Dalai Lamas and dominated Tibet's Ganden Palace government for many years. As they were generally prominent Geluk monks with deep ties to the monastic system, I am especially concerned with how their rule was related to the doctrine and institutions of Geluk Tibetan Buddhism, and epitomized the “union of religion and politics” (chösi sungdrel) of Tibet. I have studied his life through two Tibetan-language biographies, a long biography focusing exclusively on his life and a short biography from an anthology of lives of the Ganden Tripa, and I have consulted secondary sources covering Tibetan (and sometimes Qing) history, religion, economics, political science and sociology to put his life and work in context. As a political figure, I have found that he could be seen as a bodhisattva ruler, not only because of his supreme position in an ideal ritual cosmos (Tibet conceived of as a buddha-field), but also because of his practical actions, such as laws against corruption and abusive taxation, by which he promoted himself as a benefactor of the common people. I found that his religious background made him especially suited to leading the chösi sungdrel, as he had been enculturated in the scholastic system of the great Geluk monasteries and rose eventually to the position of Ganden Tripa at the top of the monastic hierarchy. His actions in office strengthened the ascendancy of the Geluk monks over Tibet. He also gained influence with the Qing by forming a patron and priest (chöyön) relationship with the Qianlong emperor, serving in his court as religious preceptor, both before his reign as regent (1762-1777) and afterwards (1786-1790). This relationship enabled him to negotiate to preserve Tibetan autonomy and Tibetan traditions as the Qing moved to consolidate power. In regards to the Dalai Lama, Ngawang Tsültrim's position as tutor symbolically affirmed that the Dalai Lama was being kept off the throne, but other actions of Ngawang Tsültrim affirmed that the Dalai Lama was the real, ultimate source of the Ganden Palace's chösi sungdrel. Although Ngawang Tsültrim's regency marked the beginning of an era when the high monks and lamas of the regency displaced the Dalai Lama as actual rulers of Tibet, he ensured that the Dalai Lama lineage would continue and maintain their spiritual supremacy