1,263 research outputs found

    Numerical simulation of mold filling and casting solidification

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    Cílem této diplomové práce je, na základě numerické simulace stávající technologie výroby hliníkového odlitku držáku kladky V9X, analyzovat příčiny vzniku vad typu zavaleniny a studené spoje. Následným cílem je vypracovat návrh variantního řešení tvaru odlitku tak, aby došlo k odstranění zmíněných vad. Toto variantní řešení bude rovněž ověřeno numerickou simulací. Úspěšnost navržených změn, pak posoudí zkušební odlití odlitku. V rámci řešení problému bude provedena simulace cyklování formy a následně plnění odlitku. Během analýzy plnění dutiny formy bude rovněž rozebrána první fáze plnění, tedy pohyb pístu v tlakové komoře. S ohledem na typ vznikajících vad nebude provedena analýza tuhnutí odlitku.The object of this diploma thesis is to analyze, persuant to numerical simulation of current technology of production aluminous casting roller-reck V9X, causes of the rise of cold lap and laminations defects. Consequently, to work up a project of variant solution of the shape of casting so, as to come to elimination mentioned defects. This variant solving will be tested with numerical simulation as well. Fruitfulness of these designed changes will be verified by testing molten of the casting. In terms of solve the problem the simulation of cycling of the mold and subsequently the filling of the casting will be effected. During the analyse of filling of the die the first phase of filling will be effected too.It means the movement of the piston throught the chambre. Simulation of solidification of the casting wont be effected because of the type of the defect.

    The Higgs Mass and New Physics Scales in the Minimal Standard Model

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    We study the theoretical correlation between the Higgs mass of the minimal standard model and the scale at which new physics is expected to occur. In addition to the classic constraints of unitarity, triviality and vacuum stability, we reexamine the constraints imposed by the precision electroweak data. We then pay particular attention to the constraint imposed by the absence of fine-tuning in the Higgs mass parameter (the Veltman condition). We find that the fine-tuning condition places a significant constraint on the new physics scale for the Higgs mass range 100 GeV < m_h < 200 GeV mostly unconstrained by the classic constraints.Comment: 19 pages Latex, 2 figure

    Quintessential Difficulties

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    An alternative to a cosmological constant is quintessence, defined as a slowly-varying scalar field potential V(\phi). If quintessence is observationally significant, an epoch of inflation is beginning at the present epoch, with \phi the slowly-rolling inflaton field. In contrast with ordinary inflation, quintessence seems to require extreme fine tuning of the potential V(\phi). The degree of fine-tuning is quantified in various cases.Comment: 7 pages LaTeX. Revised to be more pedagogical; results unchange
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