scholarly journals An Evaluation of Data Collected by Middle School and College-Level Students in Stream Channel Geomorphic Assessment

2013 ◽  
Vol 2013 ◽  
pp. 1-9
Author(s):  
Martin D. Lafrenz
Keyword(s):  
Middle School ◽  
Cross Sections ◽  
Stream Velocity ◽  
College Level ◽  
Stream Channel ◽  
Channel Geometry ◽  
Student Groups ◽  
Portland State University ◽  
Bed Material ◽  
Accuracy And Repeatability

This project tested the accuracy and repeatability of geomorphic stream channel assessments conducted by two different middle school classes from the Walt Morey Middle School in Troutdale, OR and college students from Portland State University in Portland, OR. Each group surveyed the same three cross-sections in Fairview Creek, a tributary to the Lower Columbia River, in order to assess stream channel geometry, discharge, composition of the bed material, and water quality. The three student groups were all able to accurately document the stream channel geometry, including stream width and mean depth, indicating that these data can be successfully collected by volunteers of various ages. However, stream velocity obtained using the float method was consistently overestimated leading to a biased calculation of discharge, and the low precision of the measurements did not allow for a correction of the bias. The median particle size of the bed material determined by a pebble count was also overestimated by each group, but the low precision also negated the possibility of correcting the estimate. The stored fine sediment in the bed was underestimated by each group and again with low precision. The temperature, pH, and conductivity measured with a calibrated multimeter were accurate and precise for all groups.

scholarly journals Is ink heating a relevant concern in the High Speed Sintering process?

2021 ◽  
Author(s):  
Rhys J. Williams ◽  
Patrick J. Smith ◽  
Candice Majewski
Keyword(s):  
Cross Sections ◽  
Inkjet Printing ◽  
High Speed ◽  
Sintering Process ◽  
Significant Drop ◽  
Powder Bed ◽  
Consistent Manner ◽  
Fluid Properties ◽  
Different Temperatures ◽  
Accuracy And Repeatability

AbstractHigh Speed Sintering (HSS) is a novel polymer additive manufacturing process which utilises inkjet printing of an infrared-absorbing pigment onto a heated polymer powder bed to create 2D cross-sections which can be selectively sintered using an infrared lamp. Understanding and improving the accuracy and repeatability of part manufacture by HSS are important, ongoing areas of research. In particular, the role of the ink is poorly understood; the inks typically used in HSS have not been optimised for it, and it is unknown whether they perform in a consistent manner in the process. Notably, the ambient temperature inside a HSS machine increases as a side effect of the sintering process, and the unintentional heating to which the ink is exposed is expected to cause changes in its fluid properties. However, neither the extent of ink heating during the HSS process nor the subsequent changes in its fluid properties have ever been investigated. Such investigation is important, since significant changes in ink properties at different temperatures would be expected to lead to inconsistent printing and subsequently variations in part accuracy and even the degree of sintering during a single build. For the first time, we have quantified the ink temperature rise caused by unintentional, ambient heating during the HSS process, and subsequently measured several of the ink’s fluid properties across the ink temperature range which is expected to be encountered in normal machine operation (25 to 45 ∘C). We observed only small changes in the ink’s density and surface tension due to this heating, but a significant drop (36%) in its viscosity was seen. By inspection of the ink’s Z number throughout printing, it is concluded that these changes would not be expected to change the manner in which droplets are delivered to the powder bed surface. In contrast, the viscosity decrease during printing is such that it is expected that the printed droplet sizes do change in a single build, which may indeed be a cause for concern with regard to the accuracy and repeatability of the inkjet printing used in HSS, and subsequently to the properties of the polymer parts obtained from the process.

scholarly journals Two-Side Laser Processing Method for Producing High Aspect Ratio Microholes

2017 ◽  
Vol 5 (4) ◽  
Author(s):  
Vahid Nasrollahi ◽  
Pavel Penchev ◽  
Stefan Dimov ◽  
Lars Korner ◽  
Richard Leach ◽  
...  
Keyword(s):  
Cross Sections ◽  
Laser Processing ◽  
Industrial Applications ◽  
Laser Drilling ◽  
Special Focus ◽  
Geometrical Accuracy ◽  
Aspect Ratios ◽  
Wide Range ◽  
High Flexibility ◽  
Accuracy And Repeatability

Laser microprocessing is a very attractive option for a growing number of industrial applications due to its intrinsic characteristics, such as high flexibility and process control and also capabilities for noncontact processing of a wide range of materials. However, there are some constrains that limit the applications of this technology, i.e., taper angles on sidewalls, edge quality, geometrical accuracy, and achievable aspect ratios of produced structures. To address these process limitations, a new method for two-side laser processing is proposed in this research. The method is described with a special focus on key enabling technologies for achieving high accuracy and repeatability in two-side laser drilling. The pilot implementation of the proposed processing configuration and technologies is discussed together with an in situ, on-machine inspection procedure to verify the achievable positional and geometrical accuracy. It is demonstrated that alignment accuracy better than 10 μm is achievable using this pilot two-side laser processing platform. In addition, the morphology of holes with circular and square cross sections produced with one-side laser drilling and the proposed method was compared in regard to achievable aspect ratios and holes' dimensional and geometrical accuracy and thus to make conclusions about its capabilities.

scholarly journals Using Student-Centered Projects To Teach Mathematics Content Standards

2006 ◽  
Vol 3 (4) ◽  
Author(s):  
Carryn Bellomo
Keyword(s):  
Middle School ◽  
School District ◽  
Teaching And Learning ◽  
Academic Community ◽  
School Level ◽  
Content Standards ◽  
College Level ◽  
Mathematical Content ◽  
Clark County ◽  
Clark County School District

Teaching and learning standards across the country are becoming more content driven, especially in mathematics.  As such, it is essential to develop substantive college level math courses for pre-service and in-service teachers.  These courses should deliver mathematical content in a relevant way.  Teachers must not only be proficient in their subject, but also recognize how to apply content meaningfully to student’s lives.  As part of a grant funded through the Department of Education in coordination with the Clark County School District, I have designed two college level courses that will deliver mathematical content standards to middle school teachers.  These courses will help prepare teachers at the middle school level by focusing on mathematical content, making connections within the curriculum, using technology, and enhancing the role of mathematics in everyday life and problem solving. The primary purpose of this paper is to share with the academic community the projects used to develop content understanding in mathematics topics such as:  mathematical notation, proportion, computation, estimation, linear regression, reflections, translations, finding relationships, and analyzing data.  This paper will present these projects, and tie them to mathematics standards outlined in the Clark County School District (and Nevada State) Standards.

scholarly journals Middle School Students as Social Theorists: Using a Short-Term Unit to Engage Students in Thinking Critically about Gender

2009 ◽  
Vol 11 (2) ◽  
Author(s):  
Brandelyn Tosolt
Keyword(s):  
Middle School ◽  
Middle School Students ◽  
Identity Development ◽  
Gender Roles ◽  
Language Arts ◽  
College Level ◽  
Short Term ◽  
School Students ◽  
Gender Schemas ◽  
Binary Model

Because middle school is a time of identity development, it may also be an appropriate time to focus on students’ conceptions of social roles. This article examines a unit focused on gender roles taught to a group of seventh grade language arts students at a private, urban school. The students deconstructed and reconstructed their gender schemas, gained awareness of gender as a lens, and began to question the adequacy of the male/female binary model. The findings suggest that ideas typically found in college-level courses may have appropriate applications in classrooms of much younger students.

Clay Caterpillar Whodunit: A Customizable Method for Studying Predator–Prey Interactions in the Field

2013 ◽  
Vol 75 (1) ◽  
pp. 47-51 ◽  
Author(s):  
Rachel Curtis ◽  
Jeffrey A. Klemens ◽  
Salvatore J. Agosta ◽  
Andrew W. Bartlow ◽  
Steve Wood ◽  
...  
Keyword(s):  
Middle School ◽  
Community Ecology ◽  
Prey Species ◽  
College Level ◽  
Predator Prey ◽  
Important Concept ◽  
Predator Attack ◽  
Field Laboratory

Predator–prey dynamics are an important concept in ecology, often serving as an introduction to the field of community ecology. However, these dynamics are difficult for students to observe directly. We describe a methodology that employs model caterpillars made of clay to estimate rates of predator attack on a prey species. This approach can be implemented as a field laboratory in almost any natural or seminatural setting, and is designed to allow educators to pursue any number of student-generated hypotheses representing varying degrees of scientific sophistication ranging from middle school to college level.

scholarly journals ANALYSIS OF STREAM CHANNEL GEOMETRY AND PHYSIOGRAPHIC FORMATIVE PROCESS IN VALLEY FLATS

2007 ◽  
Vol 51 ◽  
pp. 991-996 ◽  
Author(s):  
Takeshi NOGAMI ◽  
Yasuharu WATANABE ◽  
Hiroyasu YASUDA ◽  
Kazuyoshi HASEGAWA
Keyword(s):  
Stream Channel ◽  
Channel Geometry
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