Vibration Isolation of a Compound Mounting System on an Elastic Floor

This paper describes a theoretical investigation of a vibration isolation of a mounting system which consists of three masses and two isolators on an elastic floor. The formulation of the transmissibility of the system is derived in a plain expression by the use of the receptance method. The following conclusions are obtained from the results of numerical calculations. The effect of the two mounting frequencies on the transmissibility is not changed, though the combination of them is exchanged. The loss factor of one of the isolators whose mounting frequency is lower than that of the other has a great effect on the first resonance. The loss factor of the other isolator has a great effect on the second resonance. When the top mass becomes lighter and the middle mass becomes heavier, the transmissibility is reduced above the second resonant frequency. The heavy bottom mass reduces the transmissibility above the third resonant frequency, but it makes the third resonance level rise

Agile Testing: Improving the Process : Case Descom

The thesis was assigned by Descom, a marketing and technology company based in Jyväskylä. The aim of the thesis was to research the current state of testing inside the organization, and to improve on the existing processes and practices. The thesis was carried out as a design research (applied action research), because the focus was improving already existing processes inside a company. The theory base contains a wide range of subjects from agile development models, the testing process, and process improvement models to agile testing. Without a solid base of multiple aspects it would have been impossible to understand how the testing works as a process and how it could have been improved. As Descom uses agile development it was necessary to follow the same principles throughout the writing of the thesis and on results. As a result information was provided for the company about the current state of testing procedures at Descom and how to improve the testing and processes in the future. The documentation already existing for testing such as the test plan and test report were updated. New documents such as a process improvement plan based on Critical Testing Processes, test strategy and testing policy were also created. Figures of the testing process, and the processes for all test types in use were created to be used as a visual aid for understanding the testing as whole at Descom.Opinnäytetyön toimeksianto tuli Descomilta, joka on Jyväskylästä lähtöisin oleva markkinointi ja teknologia yritys. Työn tavoitteena oli tutkia testauksen tilaa organisaatiossa ja kehittää olemassa olevia prosesseja ja käytäntöjä. Tutkimusmenetelmäksi valikoitui kehittämistutkimus, koska painotus oli olemassa olevien prosessien kehityksessä yrityksen sisällä. Teoriapohjassa käsiteltiin monia aiheita ketterästä sovelluskehityksestä, testausprosessista ja prosessi kehityksestä aina ketterään testaukseen asti. Ilman kattavaa pohjaa monille osa-alueille, olisi ollut mahdotonta ymmärtää miten testaus toimii prosessina ja miten sitä pystyy kehittämään. Descom toimii ketterän sovelluskehityksen mukaisesti projekteissaan, joten oli tärkeää seurata samoja ketteriä periaatteita läpi opinnäytetyön kirjoittamisen ja tuloksissa. Tuloksena saatiin tietoa yritykselle, siitä miten testaus on toiminut Descomilla ja kuinka testausta ja prosesseja tulisi kehittää tulevaisuudessa. Myös aiemmin olemassa olleet testausdokumentit päivitettiin. Uusina dokumentteina laadittiin suunnitelma prosessikehitykseen, joka perustui Critical Testing Processes –malliin, testausstrategia ja testauspolitiikka. Prosessikuvaus tehtiin kaavioita käyttäen, joilla kuvattiin prosessi kokonaisuutena sekä käytettävät testaustasot

Condensation of Nonazeotropic Refrigerant Mixture R114/R113 in Horizontal Annuli with an Enhanced Inner Tube : Experimental Results

Local heat transfer and pressure drop measurements were made during condensation of a nonazeotropic refrigerant mixture R114/R113 in the annuli of horizontal double-tube condensers. The inner tube was a 19.1mm o.d. corrugated copper tube with soldered wire fins on the outer surface. The outer tubes were smooth tubes with inside diameter D_i of 29.9 and 25.0mm. The pressure drop and the heat transfer coefficient based on the bulk vapor-to-wall temperature difference were considerably smaller for R114/R113 than for R113. The vapor phase mass transfer coefficient β_n was higher for larger test fluid mass velocity G and D_i. At constant values of G and D_i, β_n was higher for larger condensation mass flux. The radial distribution of the vapor temperature was affected by the vapor velocity, becoming flatter at the outer part of the annulus and steeper near the liquid-vapor interface as the vapor velocity increased.蒸気圧縮式ヒートポンプ、冷凍機などの成績係数を向上させるための一方策としてローレンツサイクルが提案され、このサイクルに近づけることのできる非共沸2成分混合冷媒が実用されつつある。しかし、この冷媒が凝縮する際には低沸点蒸気が不凝縮ガスと類似の挙動を示すため、凝縮伝熱性能が単成分蒸気に比べて低下する。したがって、この冷媒を用いる凝縮器の性能向上を図るためには、凝縮液膜の熱抵抗と混合気の拡散抵抗の両者を減少させる必要がある。著者らは前提で純冷媒用の伝熱促進管の一種であるワイヤフィン付きコルゲート管を内管とする水平二重管環状部における非共沸混合冷媒R114/R113の凝縮実験を行い、圧力降下の摩擦成分は純冷媒に対する実験式で整理できること、凝縮側の熱抵抗にしめる気相の熱抵抗の割合は冷媒流量の増大につれて減少することを示した。そして、混合気相の物質伝達係数を円管上の強制対流凝縮理論から導かれた無次元パラメータを用いて整理した。しかし、より一般性のある整理式を得るためにはフィン形状、内外管径比などの影響を明らかにする必要がある。なお、フロン系非共沸2成分混合冷媒の管内、シェル側あるいは環状部における凝縮については最近多くの実験的研究が報告されているが、混合気相の物質伝達について検討したものは少なく、実験データの蓄積が望まれる。本報では、前報の内管とフィン配列が多少異なる管を内管とし、内径の異なる2種類の平滑管を外管とする水平二重管環状部におけるR114/R113の凝縮実験を行い、前報の結果と比較する。また、混合気相の温度分布測定結果についても述べる

Experimental Study of Condensation Heat Transfer from Downward-Facing Inclined Surfaces

Experiments were perfomed to study the effect of surface inclination on condensation heat transfer from downward-facing horizontal surfaces. A smooth surface and two low-finned surfaces with a length of 50mm were tested for condensation of R-113. The angle of inclination from the horizontal φ ranged from 0 to 90 deg. For the smooth surface, the heat tranfer coefficient α first decreased with the increasing of φ, then took a minimum near 5 deg, and then increased monotonically with further increasing φ. For the low-finned surfaces, α increased sharply with φ in the range of 0 to 30 deg, and then increased moderately with further increasing φ. The heat tranpfer coefficient for the better performing finned surface was 2.5, 9 and 12 times the smooth surface value for φ=0, 10 and 90 deg., respectively.電子素子の発熱密度の増大にともない、高性能の冷却法として浸漬冷却に対する関心が高まり、研究が盛んになっている。この冷却法では、発生蒸気を凝縮させるための凝縮器が必要となる。その形式として種々のものが検討されているが、容器の上面または側面を凝縮器として使用するものが最も簡便な方式であると考えられる。著者らはさきに下向き水平凝縮面下部に蒸気空間が存在する場合および凝縮面が液中に浸漬されている場合の熱伝達特性とその促進法について実験的に検討し、多孔質排液板を取付けたフィン付き面を使用することによって熱伝達が平滑面に比べて大幅に促進されることを見いだした。これは、フィン間溝部に充満した凝縮液が毛細管力によって効率良く多孔質排液板へ引き込まれ、フィン頂部が高性能の凝縮面として働くためである。同様の排液効果は伝熱面を傾斜させ、重力を利用することによっても期待できる。本報では平滑面と2種類のローフィン付き面をとりあげ、下向き面上の凝縮熱伝達に及ぼす伝熱面傾斜角の影響を冷媒R113を用いて実験的に検討する

Lattice realization of the axial U(1)U(1) noninvertible symmetry

In $U(1)$ lattice gauge theory with compact $U(1)$ variables, we construct the symmetry operator, i.e.\ the topological defect, for the axial $U(1)$ noninvertible symmetry. This requires a lattice formulation of chiral gauge theory with an anomalous matter content and we employ the lattice formulation on the basis of the Ginsparg--Wilson relation. The invariance of the symmetry operator under the gauge transformation of the gauge field on the defect is realized, imitating the prescription by Karasik in continuum theory, by integrating the lattice Chern--Simons term on the defect over \emph{smooth\/} lattice gauge transformations. The projection operator for allowed magnetic fluxes on the defect then emerges with lattice regularization. The resulting symmetry operator is manifestly invariant under lattice gauge transformations. In an appendix, we give another way of constructing the symmetry operator on the basis of a 3D $\mathbb{Z}_N$ topological quantum field theory, the level-$N$ BF theory on the lattice.Comment: 47 pages, 5 figures, the final version to appear in PTE