Judul: Simulasi Numerik untuk Pola Sebaran Suhu Kolektor Surya Pelat Datar Tipe Back-pass Cover Semi Tertutup
Abstrak: Solar energy is abundantly available, so this energy is very potential to be developed, especially in Indonesia. One of the alternative to utilize solar energy is using back-pass flat plate solar collector. The thermal energy produced by the collector can be used for crop drying. In this study, the back-pass flat plate solar collector with semi-closed cover was connected to a drying box and the thermal energy will flow into it. The effect of variation of the length of cover percentage at several tilt angle to the collector performance (temperature distribution and mass flow rate) were investigated experimentally and numerically. Numerical simulation result showed that cover of 60% had adequated to produce the air temperature above 40oC that can be used for drying most of agricultural products. Increasing percentage of cover to 80% or 100% did not improve air temperature significantly. Even the effect would increase collector manufacturing cost. The results of numerical simulations showed that tilt angle 45o had optimum mass flow rate, it was about 0.009 kg/s. Validation with experiment data showed that total error was below 10% and R2 varied from 0.76 until 0.98. Simulation of temperature distribution in drying box showed that temperature varied from 41 oC until 51 oC with error below 10% and R2 varied from 0.93-0.98.
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Judul: Modifikasi dan optimasi alat pengering tipe terowongan energi surya
Abstrak: Pada pemanfaatan energi surya untuk pengeringan hasil pertanian, komponen utama dari alat pengering adalah kolektor. Kinerja pengering sangat ditentukan oleh kinerja kolektornya. Modifikasi kolektor untuk meningkatkan kinerja merupakan salah satu cara untuk meningkatkan kinerja pengering. Tujuan dari penelitian ini adalah menyusun model matematik untuk melakukan simulasi seleksi komponen kolektor, menentukan kinerj any a, dan menentukan biaya energi kolektor. Percobaan dengan menggunakan sekam sebagai insulasi, GRP serta PVC sebagai transparan penutup, dan GIS bercat hitam sebagai penyerap, dimaksudkan untuk uji kesesuaian model. Kinerja kolektor pelat datar dapat diterangkan dengan model matematik yang dinyatakan dalam persamaan Qu = Fr Ac{S - U1(Tc - Ta )) dengan koefisien penentuan 0.86 sampai 0.96. Dari modifikasi kolektor dengan merubah dimensi penampang saluran, komponen transparan penutup, insulasi dan kemiringan kolektor, diperoleh hasil efisiensi 64.7 % dengan parameter kolektor Frca = 0.719 dan FrUl = 3.09 W/m A 2 ° K untuk kecepatan aliran rata-rata 2.8 m/dt.
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Judul: Inhibitory Control of Former Drug Users.
Abstrak: Inhibitory control is one of the characteristic functions of the prefrontal cortex by which inappropriate responses to extrinsic stimuli are avoided. On the other hand, poor inhibitory control and perseveration are the common symptoms among drug users. A little known study related to the inhibitory control, including the perseveration among former drug users in Indonesia. The Go/ NoGo task was used during the research. Seventeen former drug users and seventeen controls with no record in drug abuse were asked to do the Go/ NoGo task. Former drug users show the same ability to recognize the meaning of the cue, i.e Go cue and NoGo cue, as well as in controls. However, we found the difficulty to stop Go response in NoGo trials in former drug users, which means the failure of inhibitory response. The perseveration to the old meaning of cue was also found during the reversal phase of the task. Our study suggests that less inhibitory control and perseveration behavior occurred in former drug users. These findings suggest that even the former drug users already finished or in progress of rehabilitation program, they may still have the tendency to initiate the drug abuse. Keyword: former drug users, Go/ NoGo task, inhibitory control, perseveration
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