As-received microstructure of a SiC/Ti-15-3 composite

A silicon carbide fiber reinforced titanium (Ti-15V-3Cr-3Sn-3Al) composite is metallographically examined. Several methods for examining composite materials are investigated and documented. Polishing techniques for this material are described. An interference layering method is developed to reveal the structure of the fiber, the reaction zone, and various phases within the matrix. Microprobe and transmission electron microscope (TEM) analyses are performed on the fiber/matrix interface. A detailed description of the fiber distribution as well as the microstructure of the fiber and matrix are presented

Plasma etching a ceramic composite

Plasma etching is found to be a superior metallographic technique for evaluating the microstructure of a ceramic matrix composite. The ceramic composite studied is composed of silicon carbide whiskers (SiC(sub W)) in a matrix of silicon nitride (Si3N4), glass, and pores. All four constituents are important in evaluating the microstructure of the composite. Conventionally prepared samples, both as-polished or polished and etched with molten salt, do not allow all four constituents to be observed in one specimen. As-polished specimens allow examination of the glass phase and porosity, while molten salt etching reveals the Si3N4 grain size by removing the glass phase. However, the latter obscures the porosity. Neither technique allows the SiC(sub W) to be distinguished from the Si3N4. Plasma etching with CF4 + 4 percent O2 selectively attacks the Si3N4 grains, leaving SiC(sub W) and glass in relief, while not disturbing the pores. An artifact of the plasma etching reaction is the deposition of a thin layer of carbon on Si3N4, allowing Si3N4 grains to be distinguished from SiC(sub W) by back scattered electron imaging

Bounds on the Chabauty--Kim Locus of Hyperbolic Curves

Conditionally on the Tate--Shafarevich and Bloch--Kato Conjectures, we give an explicit upper bound on the size of the $p$-adic Chabauty--Kim locus, and hence on the number of rational points, of a smooth projective curve $X/\mathbb{Q}$ of genus $g\geq2$ in terms of $p$, $g$, the Mordell--Weil rank $r$ of its Jacobian, and the reduction types of $X$ at bad primes. This is achieved using the effective Chabauty--Kim method, generalising bounds found by Coleman and Balakrishnan--Dogra using the abelian and quadratic Chabauty methods.Comment: 24 pages, comments welcom

Barrel vibrations in small arms using combined experimental/computational methods.

Small arms are used on a global scale by militaries, hunters, competitive shooters, recreational shooters, and others. Despite this widespread use, the design and development of these tools depends heavily on prototyping and iterative testing. Additionally, the open literature concerning small arms is limited, especially in regard to those types of firearms in common use by civilians. The goal of this research was to develop a high-fidelity finite element model that would enable a detailed look into the factors governing the vibration of rifle barrels. Such a model can serve as a valuable research and development tool, reducing the high cost of prototyping. This thesis first addresses the degree of detail required in such a model to adequately capture the behavior of a sporting firearm. Experimental testing was performed in order to validate the model and lend additional insight into the factors at play. The validated model is then used to examine the influenced of curved barrel centerlines on projectile trajectories. Finally, the validity of a method of predicting shot dispersion from a single simulation is investigated

Recovery and serious mental illness: a review of current clinical and research paradigms and future directions

Introduction: Recovery from serious mental illness has historically not been considered a likely or even possible outcome. However, a range of evidence suggests the courses of SMI are heterogeneous with recovery being the most likely outcome. One barrier to studying recovery in SMI is that recovery has been operationalized in divergent and seemingly incompatible ways, as an objective outcome, versus a subjective process. Areas Covered: This paper offers a review of recovery as a subjective process and recovery as an objective outcome; contrasts methodologies utilized by each approach to assess recovery; reports rates and correlates of recovery; and explores the relationship between objective and subjective forms of recovery. Expert Commentary: There are two commonalities of approaching recovery as a subjective process and an objective outcome: (i) the need to make meaning out of one’s experiences to engage in either type of recovery and (ii) there exist many threats to engaging in meaning making that may impact the likelihood of moving toward recovery. We offer four clinical implications that stem from these two commonalities within a divided approach to the concept of recovery from SMI

The Concise Guide to the Modern Calvinist/Arminian Debate

The Calvinist/Arminian debate is not a new issue to the Protestant Church; however, it is an issue that has resurged within contemporary Christianity. One major offense committed in this controversial debate occurs when a person or group uses a term from the opposite side in a way that is not the proponent’s original intent or meaning. Furthermore, misconceptions concerning the actual doctrines maintained by either side have become commonplace in the debate. In order to correct this problem, this thesis will serve as a guide for understanding the Calvinist/Arminian debate. It will provide information on the founders of the two systems, the definitions of fundamental doctrines of each, the definitions of lesser-known terminology of the debate, the truth behind common misconceptions, and an analysis on the debate. This thesis will, in no way, attempt to determine a correct view. All the definitions, information concerning the founders, and information regarding misconceptions have been retrieved from the proponents of the respective theologies. Only Calvinists will define Calvinist terminology and only Arminians will define Arminian terminology. The goal of this work is to present an accurate depiction of both Calvinism and Arminianism

Quantifying cardiorespiratory thorax movement with motion capture and deconvolution

Unobtrusive sensing is a growing aspect in the field of biomedical engineering. While many modalities exist, a large fraction of methods ultimately relies on the analysis of thoracic movement. To quantify cardiorespiratory induced thorax movement with spatial resolution, an approach using high-performance motion capture, electrocardiography and deconvolution is presented. In three healthy adults, motion amplitudes are estimated that correspond to values reported in the literature. Moreover, two-dimensional mappings are created that exhibit physiological meaningful relationships. Finally, the analysis of waveform data obtained via deconvolution shows plausible pulse transit behavior