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Abstrak :
Sub lapisan batas laminar merupakan daerah lapisan batas yang terdapat pada daerah aliran turbulen (Re >2300 untuk aliran dalam / internal flow). Dalam aliran turbulen, sub lapisan batas laminar ini mempunyai tahanan termal yang paling tinggi. Hal ini dapat dimengerti bahwa pada lapisan ini perpindahan panas berlangsung secara konduksi karena kecepatan aliran fluida sangat kecil sehingga kemungkinan terjadinya proses dpi baik termal maupun momentum sangat kecil. Pengetahuan tentang tebal sub lapisan batas laminar ini dapat memberikan dasar bagi usaha-usaha meningkatkan kinerja alat perpindahan panas / penukar kalor. Dalam penelitian ini dilakukan percobaan untuk menganalisis dan mendapatkan cara menentukan ketebalan lapisan ini pada ruangan annulus. Ternyata dengan menerapkan metoda statistik sederhana yaitu metoda kuadrat terkecil terhadap data distribusi suhu hasil percobaan, tebal sub lapisan batas laminar dapat ditemukan. ......Laminar sub-layer is a boundary layer region in the turbulent flow (Re> 2300 for internal flow). In the turbulent flow, this laminar sub-layer has the highest thermal resistance. It could be understood that at this layer, heat transfer occurred conductively because of the very small fluid velocity that made the probability of the occurrence of thermal as well as momentum d lion very small. The knowledge related to the thickness of this laminar sub-layer could provide a basic for improving/enhancing the performance of heat exchanger. In this research, an experiment to analyze and obtain boundary layer thickness determination method for airflow in annular space was conducted. It could be concluded that by applying a simple statistical method, i.e. least square method to the experimental temperature distribution data, the laminar sub layer thickness could be determined.

Abstrak :
In signal transmission through an optical fiber, a bending fiber causes degradation of efficiency. Due to mode conversion and radiation loss. Considering a light power radiated from a bending fiber has a possibility to be utilized as detectable signal, it is proposed an optical tap by using bending fiber. The study is devoted to design and construction of optical tap for fiber link, without any other optical element. The signal quality of the radiated light from optical fiber bending has been investigated in various angle of detection and in various radius of curvature. The result shows that the radiated signal has similar shapes of distribution of 20 degrees. And the bending loss increases if the radius of curvature decreases. A trial of sending optical signal from one end of the fiber link shows a detected radiated signal from the bending point. It is predicted that the bending fiber can be applied as optical tap, instead of a source of power loss.