Research Blogs
All Graduate Junction researchers get a mini blog to share their day to day experiences. Log in to see who is posting and make contact.
Winners of the poster competition will be announced in the next few days.
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There have been hundreds of votes placed already. Get yours in now....
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The poster competition closes in just one week. Vote Now!
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Hello, I am new to GJ and have some questions to share with everyone. Does anyone have any thoughts or good articles on international comparative education? What I mean is, I am studying education in Toronto Canada at a graduate level, and I often wonder if the same issues apply to education in England for example. In my department, (theory and policy), we spend a great deal of time talking about student engagement, student success, discrimination, and social justice. Just wondering if anyone is in a graduate program in education and would like to share some thoughts...
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Hi, I have just joined toward my phd in epigenetics at the University of Otago. and we are planning to go for coparative methylation analysis...
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Lets see how this looks...
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Well, I just had a meeting with my supervisor where we discussed my first draft of my Analysis chapter. A lot of positive feedback. She liked my approach to the analysis. She mostly identified areas for improvement that I had already anticipated.
Given that I didn't have a defined plan of attack for my analysis this was a very good outcome.
A lack of participants opting into the study meant that I only had one interview to analyse. So I needed to find a new approach to analysing this interview. Previously I had anticipated looking for themes common to upto 5 participants. So I selected the 'multiple lens' approach where I looked at her responses from a number of different perspectives - VCE Student, Math Teacher, Institution, & Society. I also tried a number of approaches to analysing the data - rewriting as narrative, using screenprints of audio waveforms to help describe the participants manner of speech, use poetic representation to make the emotional tone of the interview 'visible'.
I also look at the interview from the three different 'theoretical' frameworks - Attrition research (especially Tinto), Motivation and Volition (Corno), and Self-Theories of Intelligence (Dweck). Plus how this research links to Early School Leavers and Transition between different 'learning cultures'
I'm extending the data collection by interviewing at least 2 students who are persisters in the same class/school as Danielle. I intend to use the 'themes' indentified in the Analysis of Danielle's interview to analyse the interview of these students.
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Blu-Tack is a versatile, reusable putty-like pressure-sensitive adhesive. The original version of the product was blue, but many colours are now available. Blu-Tack can leave an oily stain on paper materials if attached for a long period of time. Blu Tack is known as "Zorkai" in north eastern areas of Canada.[1] In South Africa it is commonly known as "Prestik" (as made by Bostik), or "Sticky Stuff" (as made by Pritt). //From:http://en.wikipedia.org/wiki/Blu-Tack
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Well, what a summer! Hubby had right knee replacement, then I submitted my thesis. All had a holiday before my viva, after which hubby had left knee replacement, and I did my revisions. (I had two months in which to do them, but managed in one month, as I was fearful of missing the winter graduation deadline!) I'm having a pre-graduation party next weekend (whoo-hoo!), then the graduation ceremony is on Wednesday 2nd December. I can only take two guests, but my younger sons don't mind, as I have kept our Guy Fawkes fireworks for the late afternoon. It gets dark early in Scotland!
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Indentation hardness tests are used to determine the hardness of a material to deformation. Several such tests exist, wherein the examined material is indented until an impression is formed; these tests can be performed on a macroscopic or microscopic scale.// For measuring hardness of very small samples nanoindentation is used.// When testing metals, indentation hardness correlates linearly with tensile strength. This important relation permits economically important nondestructive testing of bulk metal deliveries with lightweight, even portable equipment, such as hand-held Rockwell hardness testers. [1]// Material hardness// As the direction of materials science continues towards studying the basis of properties on smaller and smaller scales, different techniques are used to quantify material characteristics and tendencies. Measuring mechanical properties for materials on smaller scales, like thin films, can not be done using conventional uniaxial tensile testing. As a result, techniques testing material "hardness" by indenting a material with an impression have been developed to determine such properties./// Hardness measurements quantify the resistance of a material to plastic deformation. Indentation hardness tests compose the majority of processes used to determine material hardness, and can be divided into two classes: microindentation and macroindentation tests. Microindentation tests typically have forces less than 2 N (0.45 lbf). Hardness, however, cannot be considered to be a fundamental material property. Instead, it represents an arbitrary quantity used to provide a relative idea of material properties.[2] As such, hardness can only offer a comparative idea of the material's resistance to plastic deformation since different hardness techniques have different scales./// The main source of error with indentation tests is the strain hardening effect of the process. However, it has been experimentally determined through "strainless hardness tests" that the effect is minimal with smaller indentations.[3]/// Surface finish of the part and the indenter do not have an effect on the hardness measurement, as long as the indentation is large compared to the surface roughness. This proves to be useful when measuring the hardness of practical surfaces. It also is helpful when leaving a shallow indentation, because a finely etched indenter leaves a much easier to read indentation than a smooth indenter.[4]/// The indentation that left after the indenter and load are removed is known to "recover", or spring back slightly. This effect is properly known as shallowing. For spherical indenters the indentation is known to stay symmetrical and spherical, but with a larger radius. For very hard materials the radius can be three times as large as the indenter's radius. This effect is attributed to the release of elastic stresses. Because of this effect the diameter and depth of the indentation do contain error. The error from the change in diameter is known to be only a few percent, with the error for the depth being greater.[5]/// Another effect the load has on the indentation is the piling-up or sinking-in of the surrounding material. If the metal is work hardened it has a tendency to want to pile up and form a "crater". If the metal is annealed it will sink in around the indentation. Both of these effects add to the error of the hardness measurement.[6]/// [edit] Macroindentation tests The term "macroindentation" is applied to tests with a larger test load, such as 1 kgf or more. There are various macroindentation tests, including:/// * Vickers hardness test (HV), which has one of the widest scales/// * Brinell hardness test (HB)//// * Knoop hardness test (HK), for measurement over small areas// * Janka hardness test, for wood// * Meyer hardness test// * Rockwell hardness test (HR), principally used in the USA// * Shore durometer hardness, used for polymers// * Barcol hardness test, for composite materials// There is, in general, no simple relationship between the results of different hardness tests. Though there are practical conversion tables for hard steels, for example, some materials show qualitatively different behaviors under the various measurement methods. The Vickers and Brinell hardness scales correlate well over a wide range, however, with Brinell only producing overestimated values at high loads./// [edit] Microindentation tests/// The term "microhardness" has been widely employed in the literature to describe the hardness testing of materials with low applied loads. A more precise term is "microindentation hardness testing." In microindentation hardness testing, a diamond indenter of specific geometry is impressed into the surface of the test specimen using a known applied force (commonly called a “load” or “test load”) of 1 to 1000 gf. Microindentation tests typically have forces of 2 |N (roughly 200 gf) and produce indentations of about 50 μm. Due to their specificity, microhardness testing can be used to observe changes in hardness on the microscopic scale. Unfortunately, it is difficult to standardize microhardness measurements; it has been found that the microhardness of almost any material is higher than its macrohardness. Additionally, microhardness values vary with load and work-hardening effects of materials.[2] The two most commonly used microhardness tests are tests that also can be applied with heavier loads as microindentation tests:// * Vickers hardness test (HV)/// * Knoop hardness test (HK)/// In microindentation testing, the hardness number is based on measurements made of the indent formed in the surface of the test specimen. The hardness number is based on the surface area of the indent itself divided by the applied force, giving hardness units in kgf/mm². Microindentation hardness testing can be done using Vickers as well as Knoop indenters. For the Vickers test, both the diagonals are measured and the average value is used to compute the Vickers pyramid number. In the Knoop test, only the longer diagonal is measured, and the Knoop hardness is calculated based on the projected area of the indent divided by the applied force, also giving test units in kgf/mm²./// The Vickers microindentation test is carried out in a similar manner to the Vickers macroindentation tests, using the same pyramid. The Knoop test uses an elongated pyramid to indent material samples. This elongated pyramid creates a shallow impression, which is beneficial for measuring the hardness of brittle materials or thin components. Both the Knoop and Vickers indenters require prepolishing of the surface to achieve accurate results./// Scratch tests at low loads, such as the Bierbaum microcharacter test, performed with either 3 gf or 9 gf loads, preceded the development of microhardness testers using traditional indenters. In 1925, Smith and Sandland of the UK developed an indentation test that employed a square-based pyramidal indenter made from diamond.[7] They chose the pyramidal shape with an angle of 136° between opposite faces in order to obtain hardness numbers that would be as close as possible to Brinell hardness numbers for the specimen. The Vickers test has a great advantage of using one hardness scale to test all materials.The first reference to the Vickers indenter with low loads was made in the annual report of the National Physical Laboratory in 1932. Lips and Sack describes the first Vickers tester using low loads in 1936.[citation needed]/// There is some disagreement in the literature regarding the load range applicable to microhardness testing. ASTM Specification E384, for example, states that the load range for microhardness testing is 1 to 1000 gf. For loads of 1 kgf and below, the Vickers hardness (HV) is calculated with an equation, wherein load (L) is in grams force and the mean of two diagonals (d) is in milimeters: HV=1854.4\times\tfrac{L}{d^2}/// For any given load, the hardness increases rapidly at low diagonal lengths, with the effect becoming more pronounced as the load decreases. Thus at low loads, small measurement errors will produce large hardness deviations. Thus one should always use the highest possible load in any test. Also, in the vertical portion of the curves, small measurement errors will produce large hardness deviations./// From: http://en.wikipedia.org/wiki/Indentation_hardness#Microindentation_tests
