Manufacturing of Continuous Carbon Fiber Composites Using Ultraviolet Laser-Assisted Direct Ink Write 3D Printing

Additive manufacturing (AM), commonly referred to as 3D printing, is a quickly growing field with numerous techniques available to manufacture parts which are stronger, lighter, and more complex than those which could be traditionally manufactured. With the goal of creating stronger parts, a new 3D printing technique was developed which combined properties of several different methods in order to print continuous carbon fiber-reinforced thermosets. This new method is called continuous fiber direct writing (CFDW). The process works by extruding continuous fiber and ultraviolet (UV) curable resin out of a syringe simultaneously and curing the resin immediately upon extrusion via UV lasers aimed at the extrusion point. This was created using the principles behind direct ink writing (DIW), stereolithography (SLA), and fused deposition modeling (FDM). It utilizes DIW technology to extrude liquid resin out of the syringe, SLA technology to cure the resin in situ, and FDM technology to deposit the fiber and resin onto the print path. In order to test this novel method, a custom extrusion system and print head was designed and adapted onto an existing consumer FDM printer. The developed printer is able to successfully print continuous fiber-reinforced samples with control over the fiber direction and fiber volume fraction. Several experiments were conducted in order to characterize the various printing parameters. The largest focus was on the two most important parameters: deposition speed and extrusion pressure. The deposition speed, or feed rate, describes how quickly the print head moves across the build plate, while the extrusion pressure describes how much pressure is applied to extrude the resin out of the syringe. These two parameters together greatly affect the resulting width and shape of a printed line of fiber. In general, increasing the pressure or decreasing the feed rate creates a larger line width. This is very important as it affects the hatch spacing which in turn affects the fiber volume fraction. Additionally, these factors can affect the top surface finish of the resulting part. In addition to these parameter-based studies, bulk rectangular samples and complex samples were printed in order to demonstrate the capabilities of the printer. The CFDW method works well and is fairly consistent with the proper printing parameters. Through future development of this process, composite samples can be made with individual tows of fibers oriented according to the geometry of the part, allowing for reduced weight and increased strength of the additively manufactured components

Saint Anselm of Canterbury and Charismatic Authority

The early career of Archbishop Anselm of Canterbury (c. 1033–1109) provides an opportunity to explore the operation of charismatic authority in a monastic setting. It is argued that the choice of Anselm for the archiepiscopal see of Canterbury in 1093 was the result of his growing reputation cultivated during his years as prior and abbot of the influential Norman monastery of Bec. The article explores various aspects of Anselm’s charismatic authority including his performance of charisma, the charisma derived from his fame as a scholar, and his reputation as a miracle-working holy man

Assessing the viability of mapping bull kelp in Puget Sound using aerial imaging platforms

Bull kelp (Nereocystis luetkeana) is an important primary producer that plays a foundational role in the marine nearshore ecosystems of Puget Sound. Evidence of significant declines in bull kelp forests in this region has motivated efforts to establish region-wide long-term monitoring programs for this critical species. As part of this drive, the Washington State Department of Natural Resources (DNR) has been testing a series of aerial imaging platforms to detect and map the distribution of bull kelp to complement existing monitoring protocols. In 2020, DNR began surveying floating bull kelp canopies in Puget Sound using RGB and multispectral Unmanned Aerial Vehicles (UAVs), as well as low-cost RGB and near-infrared sensors carried by fixed wing aircraft. We have conducted surveys at five diverse kelp forest sites using three different imaging platforms, and additional surveys at many other sites with one or two methods, representing a range of potential trade-offs. Surveys conducted at sites in North Puget Sound were done so in partnership with county Marine Resource Committees through the Northwest Straits Commission, which involved community science efforts from volunteers. Orthomosaics (large format image products) generated from our aerial surveys were georeferenced, analyzed using a supervised object-based random forest classifier, and assessed against technician-verified stratified random accuracy assessment points. From these final classified results, we generated map layers of the floating bull kelp canopy at each site and developed derived metrics to describe each kelp bed including canopy area, overall bed area, and canopy percent cover. Our findings demonstrate the comparative strengths and limitations of each aerial imaging platform with regard to cost, kelp canopy detection capability, resolution, and spatial coverage. These findings enable us to make recommendations for the most appropriate use for each platform with regard to bull kelp canopy mapping in Puget Sound

Madrigal of May

https://digitalcommons.ithaca.edu/sheetmusic/1153/thumbnail.jp

Is there an optimal length of psychological treatment for eating disorder pathology?

Objectives: Treatment guidelines for eating disorders (ED) are unclear about the optimal length of psychological care. We aimed to investigate associations between treatment duration and changes in ED pathology. Method: Data for 164 outpatients accessing psychological interventions for ED were analyzed using MANOVA. We tested associations between number of therapy sessions and pre-post treatment changes in clinical outcomes (EDE-Q global scores, binge eating, purging); adjusting for baseline measures, diagnoses and treatment type. Secondary analyses included rapid response variables in the above outcomes by treatment session eight. Partial correlations between treatment duration and BMI changes (adjusting for intake BMI) were examined for anorexia nervosa cases. Results: Treatment duration was not significantly associated with changes in ED outcomes after adjusting for rapid response. BMI change (weight regain) was not correlated with treatment duration in anorexia nervosa cases. Rapid response was associated with better EDE-Q outcomes, but not with changes in binge eating or purging behaviors. Discussion: ED outcomes are unrelated to treatment duration; rapid response is a useful prognostic indicator for treatment planning

Wind-tunnel experiments on the squidding of parachutes

To determine the underlying cause of the collapse of a parachute, known as 'squidding.' Measurements of pressure were made in a wind tunnel at a number of positions over the surfaces of rigid models representing (a) a fully inflated canopy (b) a semi-squidded shape, and also at points over the surface of a small parachute. Each rigid model was uniformly perforated with holes representing a degree of porosity which was varied in some of the tests by covering different areas of the surface. Tests on the parachute were made with it tethered, (1) with rigging lines to a fixed point, (2) by wires to the sides of the tunnel. Directional measurements of flow required for tracing streamlines were made in the neighbourhood of the parachute both before and after the fabric had been rendered non-porous. It was found that, through the lack of deformable areas near each mouth, the rigid models did not reproduce adequately the prerequisite conditions of flow which normally lead to squidding. Radial outward forces tending to prevent collapse were shown to depend not only on the pressure inside the canopy but also on the strength and direction of the local flow. Any change which brings the direction nearer to that of the axis of the parachute decreases the incidence of the lip of each gore, and hence reduces the outward radial force. Such a change results from an increase in porosity of the fabric, and since an increase in porosity usually occurs with rise of speed, the process of squidding starts at a speed when the lips of the gores become deformed inwards. Similar changes of flow were not observed with a non-porous parachute, which remained fully inflated at the highest speeds attainable in the tests