none

Materials and manufacturing processes are an integral part of the design of a product. The need to combine materials and manufacturing processes selection during the early stages of the design has previously been realized. The work that generally attracts the most attention is by M.F. Ashby. This methodology, like others, concentrates on materials and manufacturing processes selection after the conceptual design is completed and before moving into embodiment design. The disadvantage of waiting until the conceptual design is completed to address materials and manufacturing processes is that the designer cannot search for conceptual solutions when dealing with issues relating to the materials and manufacturing processes domains. By not considering these issues early on in the design process, the scope for innovation is reduced and this results in the designer being fixated on the configuration at hand. It is well recognized that this is not the best way to address a design challenge and an even worse approach to innovation. The basic framework for which enhancements and improvements are suggested is the design methodology practiced and taught by the members of the Institute for Innovation and Design in Engineering (IIDE) at Texas A&M University. Conceptual design is very much a part of the IIDE design process; but the current format concentrates on functional parameters and how to search for conceptual solutions for these, and does not highlight materials and manufacturing issues in the preliminary design stages where it could be most helpful. The work documented in this thesis is an attempt to ensure that there is no disconnect between function oriented design and the materials and manufacturing processes that are applicable to that design. The core of the thesis is to incorporate a thought process which will help the designer during conceptual design phase to: 1. Consciously question if there materials and manufacturing issues; 2. Identify critical parameters in both of these domains; and 3. Search for conceptual solutions to these identified critical parameters.

In ordert to increasing the capacity of stocking and integration in the process of optimizing the internal cost in steel industry. The cost of material profolio is usually being ignored during opmization. Experiences-based decision paten still being carried out in material profolio in this industry.Thus the Inventory and Manufacture cost are losing inadvertently. This study aims at obtaining the minimum material profolio cost so that we provide a model concerned with cost and element limitation of target product.Using dynamic programming into material-profolio decision making process. We divided material profolio into three steps, transforming the productive limitations into mathematic constrains,and implememting by software.The real-case data is given to estabilish the model database.Comparing our data with the real data,we found that with the approach, we significately reduced and the cost and variety of material profolio in different critiria

<p>The loss and recovery of the surface hydrophobicity areimportant phenomena when highvoltage insulators, with a shedmaterial composed of polydimethylsiloxane (PDMS), are used. Theloss of hydrophobicity is mostly due to the oxidativecrosslinking which takes place on the PDMS surface duringexposure to electrical discharges, e. g. corona discharges. Thecrosslinking reaction leads to the formation of anoxygen-enriched, silica-like layer, which is brittle and henceprone to cracking, either spontaneously or upon mechanicaldeformation. Repetitive cracking leads to the propagation ofcracks into the core of the material, which is believed todeteriorate the insulator’s performance and reduce itsservice-life. Hence, an approach to make PDMS more resistant tothe build-up of the silica-like layer is beneficial for theperformance of PDMS in high voltage insulators.</p><p>In this work the effect of antioxidative stabilizers on thecorona- and air-plasma-induced surface oxidation of PDMS isstudied. Three commercial stabilizers, a hindered phenol(Irganox® 1076), a hindered amine light stabilizer(Tinuvin® 770) and a bifunctional stabilizer withchainbreaking hindered phenol and secondary amine andhydroperoxide-decomposing sulfide moieties (Irganox® 565),have been used. Surface oxidation was achieved by exposure of amodel crosslinked PDMS to an air plasma or a corona discharge,and the surface characteristics of the exposed samples wereassessed by contact angle measurements, X-ray photoelectronspectroscopy, optical and scanning electron microscopy, andsurface profilometry before and after uniaxial stretching.</p><p>A reliable rapid method for the assessment of stabilizerconcentration in PDMS was established. PDMS samples containingknown stabilizer concentrations of a phenolic antioxidant(Irganox® 1010) and a hindered amine stabilizer(Tinuvin® 144) were prepared. It was shown that thestabilizer concentration in PDMS could be determined by highperformance liquid chromatography (HPLC) of the microwaveassisted solvent extracts (MAE) of stabilized PDMS samplesusing acetone (a non-swelling solvent). This method wasemployed to measure the stabilizer concentration in PDMSsamples exposed to air plasma and corona discharges. Thestabilizer concentration in PDMS was varied by using diluteswelling solutions (0.005 wt% to 0.2 wt%) of the stabilizers inhexane. Samples stabilized with Irganox 565 showed stabilizerprecipitation on the surface after swelling in solutions with astabilizer concentration greater than 0.05 wt%. Samplescontaining Irganox 1076 and Tinuvin 770 showed no surfaceprecipitation except after swelling in a solution of 0.2 wt%stabilizer concentration.</p><p>The air plasma and corona exposure time required for theformation of the silica-like surface layer increased,essentially, in a linear fashion with increasing stabilizerconcentration. Tinuvin 770 showed the strongest overallprotecting effect during, as well air plasma as coronaexposures, whereas Irganox 565 showed the strongest protectingeffect per mass fraction stabilizer during air plasmaexposures. Irganox 1076 was of moderate efficiency. The resultssuggest that efficient protection towards discharge-inducedsurface oxidation is achieved with hindered amine stabilizersor with stabilizers combining chain-breaking andhydroperoxide-decomposing functions.</p><p>The diffusion of the stabilizers Irganox 1010 and Tinuvin144 from PDMS to water at elevated temperatures (75 °C and95 °C for Irganox 1010 and 95 °C for Tinuvin 144) wasstudied. For Irganox 1010 the diffusion constant (D), accordingto Fick’s second law for uni-dimensional penetrantdiffusion was assessed to 3.1 X 10^-9cm²s^-1at 95 °C and to 5.46 X 10^-10cm²s^-1at 75 °C. An estimate for the activationenergy for the diffusion of Irganox 1010 to the surroundingmedia was obtained (E_a=93 kJ mol^-1), on the basis of the diffusion data. For Tinuvin144, no diffusion constant could be calculated due to poorseparation of the stabilizer peak from the impurities in theextract when using the HPLC method developed earlier.</p>

Title from PDF of title page. / Document formatted into pages; contains 43 pages. / Thesis (M.S.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: Skutterudites have been of great interest for thermoelectric applications over the last ten years. Scientific interest has focused on the unique transport properties Skutterudites possess due to the unique crystal structure. Technical interest has grown since it was discovered that some compounds rival the current best thermoelectric materials. To further the understanding of this material system, and optimize its thermoelectric properties, the synthesis and characterization of polycrystalline n- and p-type CoGe&esc;b1&esc;s&&dotb;esc;b5&esc;sSe&esc;b1&esc;s&&dotb;esc;b5&esc;s was undertaken. Structural, morphological, chemical, electrical, thermal and magnetic properties were studied. These data are compared to those of the binary Skutterudite CoSb3. The results of this study show a very sensitive dependence of the physical properties on stoichiometry. / ABSTRACT: While the thermoelectric figure of merit is low in these materials, it is apparent that optimization via doping and "void filling" will lead to improved thermoelectric properties. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.

Zugl.: Erlangen, Nürnberg, Univ., Diss., 2009

The purpose of this study was to gain greater knowledge of how preschool teachers and children using an experimental- and activity box in biology. To find this out, I have used the participant observation method and semi-structured interviews since my study is qualitative. The result of the work led to a greater understanding of the biologybox. It was shown that preschool teachers' involvement is very important for children and that the biologybox contained good and inspiring materials. Although educators desired that there was more material to choose from as well as the usage time of the biologybox should be longer than 3 weeks.

Syftet med studien är att belysa hur barn i förskolan använder sig utav sina redan vunna literacyfärdigheter. Studien har genomförts med kvalitativ metod där en etnografisk fältstudie legat till grund för de resultat som presenteras. Vi har använt en metodkombination av systematisk observation och dokumentation genom filminspelning.    Vi har följt tio stycken barn och underlaget har samlats in från två förskolor i Linköpings kommun. Resultatet har bearbetats utifrån Vygotskijs sociokulturella perspektiv. Resultatet visar att de unika literacypraktiker barnen är engagerade i är beroende av ett antal olika faktorer. Dessa faktorer är bland annat: förskolans miljö, tillgång till material, barnets intellekt och sociala samspel. Ytterligare en faktor som spelar in vid barnens användande av literacy är förhållningssättet till barnen av de pedagoger som arbetar i förskolan.    Studien påvisar att interaktion mellan individer kan vara främjande vid användande av literacy, men det är ändå inte en förutsättning för att användandet ska uppstå.    Nyckelord: literacy, förskola, förskolebarn, miljö, material

Denna studie undersöker elevers erfarenheter av laborativt material.Syftet med denna studie var därför att utveckla kunskap om eleversperspektiv på arbetet med laborativt material imatematikundervisningen. Studiens två frågeställningar är: ”vilkaerfarenheter har elever av laborativ matematik?” och ”vilkauppfattningar uttrycker elever om laborativ matematik?”. Metodensom valdes för studien var en kvalitativ ansats i form av intervjuer ochkompletterande observationer. Då jag fokuserar på eleverserfarenheter och uppfattningar tar studien avstamp ilivsvärldsfenomenologi. Genom intervjuerna kunde jag som forskareta del av elevers berättelser om deras erfarna livsvärld.Dokumentationen skedde genom videoinspelningar som sedantranskriberades, tolkades och analyserades. Analysen resulterade i fyrateman: rolig och lättare matte, passande svårighetsgrad, rättförutsättningar och abstrakt eller konkret. Studiens slutsats är attelever tycker arbetet med laborativt material är roligt och givande sålänge det görs med rätt förutsättningar i deras ögon.

Dispersion, attenuation, and crosstalk are several major challenges that both a high-speed digital and a microwave serial link must overcome to achieve their desirable performance. These phenomena are directly related to the frequency dependency of the dielectric property of the material used in package and interconnect. The dielectric property of a material is commonly measured by its manufacturer in a particular direction at a few discrete frequencies using resonator and waveguide methodology. Since the dielectric property may vary during manufacturing processing, the measurements taken by the manufacturer might be not adequate. Moreover, the dielectric property of a material in a bandwidth that covers at least the second harmonics of the fundamental operational frequency is required to accurately predict the link performance. One of the efforts in this research is to investigate the methodology of realizing broadband characteristics of the dielectric property of a material in its "as packaged" configuration using various transmission line topologies, such as microstrip line and Co-Planar Waveguide (CPW). Transitions from CPW to other transmission line topologies are mandatory if CPW probes are used to achieve broadband and repeatable measurements. Since microstrip line is one of the transmission line topologies involved in this research, a research effort is dedicated to develop a broadband CPW-to-microstrip line transition. An effort is also expended to creating casual material models that can be used in electromagnetic simulators to appropriately model the link based on the polarization mechanism of the materials. In addition to focusing on the measurement method in frequency domain, Short Pulse Propagation (SPP), a time domain method, is investigated as well. A virtual test bench is created to investigate the correlation between impedance variations in stripline structures due to fabricated tolerance and the attenuation predicted by SPP.