PEMBUATAN DAN ANALISIS EXCITER GENERATOR RF UNTUK SIKLOTRON PROTON DECY-13

PEMBUATAN DAN ANALISIS EXCITER GENERATOR RF UNTUK SIKLOTRON PROTON DECY-13.Telah dilakukan analisis dan pembuatan exciter generator RF untuk siklotron proton 13MeV. Generator RFakan digunakan sebagai sumber tegangan pemercepat bolak-balik siklotron DECY-13 rancangan PTAPBBATAN.Berdasarkan dokumen rancangan dasar yang telah dibuat siklotron Decy-13 akan menggunakanmedan magnet 1,275 Tesla, sehingga frekuensi generator RF bila menggunakan harmonik keempat adalah77,667 MHz. Salah satu teknik pembangkitan sinyal radio frekuensi untuk siklotron yang saat inidikembangkan di dunia adalah dengan teknik Direct Digital Synthesizer (DDS).Teknologi DDS adalah sirkuit arsitektur inovatif yang memungkinkan manipulasi frekuensi dengan cepatdan tepat pada keluarannya dan sepenuhnya di bawah kontrol digital. Prototip exciter generator RF yangtelah dibuat menggunakan DDS tipe AD9851 buatan Analog Device dengan frekuensi dasar 30 MHz. dandikendalikan oleh mikrokontroler ATmega16. Untuk menghindari timbulnya frekuensi yang tidak diharapkanpada keluarannya, keluaran DDS dilewatkan rangkaian band pass filter pasif. Hasil pengujian menunjukkanbahwa rentang frekuensi keluaran exciter adalah 2 MHz dengan frekuensi tengah 77,667 MHz. dan stopband -3dB. Sedangkan keluaran daya RF 10 Watt memerlukan catu daya + 12 V dengan arus 2,9 A.Meskipun prototip sudah berhasil dibuat dan hasilnya sesuai yang diharapkan, tetapi masih perludisempurnakan.Kata kunci: Exciter, generator RF, band pass filter, siklotro

PENGEMBANGAN PERANGKAT LUNAK PARAMETER PROSES MBE-P3TM

PENGEMBANGAN PERANGKAT LUNAK PARAMETER PROSES MBE-P3TM. Telah dilakukan analisis, perancangan dan pembuatan program komputer untuk mendukung Sistem Instrumentasi dan Kendali MBE di P3TM. Komputer untuk Instrumentasi MBE dilengkapi dengan kartu PCL-745B komunikasi serial untuk jaringan RS485. Komputer berfungsi untuk melakukan akuisisi data parameter proses MBE dan menampilkan data dalam bentuk numerik maupun diagram batang dan visualisasi posisi trafo variac filamen sumber elektron dan trafo variac sumber tegangan tinggi osilator daya. Kartu antarmuka Advantech PCL-718 dipasang di salah satu slot komputer bantu, berfungsi untuk mengubah masukan sinyal analog yang telah dikondisikan sesuai persyaratan menjadi bentuk dijital. Data dalam bentuk dijital dikirimkan ke komputer utama secara serial lewat pasangan kabel terpilin dengan protokol RS-485. Program komputer yang dikembangkan telah diuji coba di laboratorium secara simulasi dan juga diuji coba langsung pada saat MBE dioperasikan, memberikan hasil unjuk kerja tampilan yang stabil pada layar monitor. Hasil percobaan menunjukkan bahwa tampilan program komputer dapat memberi tambahan informasi bagi operator saat mengoperasikan MB

PROGRAM KOMPUTER UNTUK MENGHITUNG AKTIVITAS CUPLIKAN SISTEM PENCACAH KAMAR PENGION MERLIN GERIN

PROGRAM KOMPUTER UNTUK MENGHITUNG AKTIVITAS CUPLIKAN SISTEM PENCACAH KAMAR PENGIONMERLIN GERIN. Telah disusun suatu program komputer untuk perhitungan aktivitas cuplikan sistem pencacahkamar pengion. Sistem pencacah kamar pengion Merlin Gerin yang digunakan laboratorium standardisasi bidangmetrologi radiasi P3KRBiN-BATAN, merupakan salah satu jenis peralatan ukur radiasi untuk pengukuran aktivitasberbagai macam radio nuklida. Untuk menampilkan data hasil pengukuran peralatan tersebut digunakan tampilandigital, tetapi pengambilan data hasil pengukurannya masih dilakukan secara manual sehingga ketelitian data yangdiperoleh sangat bergantung pada operatornya. Untuk meningkatkan kinerja sistem, telah dilakukan penambahanperangkat keras berupa komputer personal dan multimeter digital serta analisis, perancangan dan pembuatanprogram komputer. Komputer berfungsi pengambil data secara otomatis berdasarkan runtutan perintah yangdiberikan dan dilanjutkan dengan melakukan perhitungan menggunakan persamaan-persamaan yang telahditentukan dan yang terakhir melakukan pencetakan hasil. Program komputer dibuat menggunakan bahasapemrograman Delphi dan telah diuji coba langsung pada sistem. Perbandingan antara perhitungan oleh komputerdan perhitungan secara manual diperoleh hasil yang sama, sehingga dapat disimpulkan bahwa program komputertelah berfungsi sesuai dengan yang diharapkan dan unjuk kerja dari sistem pencacah telah dapat ditingkatkan

Pengaruh Fraksi Udara Terhadap Koefisien Perpindahan Kalor Kondensasi Refrigeran Petrozon Rossy-22 Di Dalam Pipa Tegak

Petrozon Rossy-22 is one of hydrocarbon refrigerants which environmentally safe, since there is no effect on either ozone depletion or global warming. In the refrigeration cycle, imperfect vacuuming process or other factors that permit circulation of air taken place in the system predicted influencing heat transfer rate in condenser. Therefore, research on the influence of air fraction against condensation heat transfer coefficient of Petrozon Rossy-22 inside vertical pipe to be done. A modified refrigeration system of vapor compression was applied in this research, where the condensation was done in the 2 meters straight vertical condenser (double pipe heat exchanger, that further called as test section). The diameter of internal and external pipe were ¾” and 1 ¼” respectively. Electric heater was installed on upstream of the test section. Mixture of air- refrigerant was flowed downward inside internal pipe, while cooling water was flowed upward through annulus. The varied parameters were: air fraction, air-refrigerant and cooling water flow rate. The result of the research indicated that condensation heat transfer coefficient significantly decreased when air fraction increased. The proposed empiric equation is :       Nu = 0.0138. (1-w)8.8198. Re0.7941. Pr4.7315with determination coefficient of 0.6927 and average absolute deviation of 17.65 %. The equation was for Re= 6.922-12.953, Pr= 2,008-2,696, and w= (0,25-1)%

Studies on the Interaction Between Upland Rice and Other Crops in Intercropping System

The national rice requirement in Indonesia today is very high, and can not be fullfiled from irrigated lowland rice area only. However, the contribution of upland rice, which is grown in dryland and rainfed area, to national rice production is lower compared to lowland rice, although dryland area in Indonesia is much wider compared to lowland area. One of the advantages of upland rice culture compared to lowland rice is that it can be grown side by side with other crops under intercropping system. Studies on the interaction between upland rice and other crops is needed to get the crops suited to grow together. This paper is a review of the results of a series of field experiments on the intercropping between upland rice and other (legume and horticultural) crops conducted in agriculture experiment station, Gadjah Mada University, in Kalitirto district, Yogyakarta, from 2000 up to 2005. The methodology used is based on the replacement series technique. Basically, there are three different types of interaction, i.e. (1) Mutual inhibitation, when the actual yield of each species is less than expected. (2) Mutual cooperation or complementation, when the actual yield of each species is greater than expected. (3) Compensation, one species yield is less and the other is more than expected. The results of the experiments was classified into two groups i.e. (1) upland rice vs legume crops and (2) upland rice vs horticultural crops. Most of legume crops stimulated upland rice yield. However, the effect of upland rice on each legume was different, i.e. decreased yield such as in mung bean and groundnut, or no significant effect such as in velvet bean (Mucuna sp.). Thus a compensation type of interaction occurred. In horticultural crops, the results varied depending on the species of the crop. Complementary was shown on the interaction between upland rice and water melon. In intercropping upland rice-onion, upland rice stimulated onion yield while onion did not affect to upland rice yield. However, in intercropping upland rice-pineapple, both Cayenne and Queen types of pineapple gave positive effect (increased) to upland rice yield, while upland rice did not give harmful effect to pineapple.Special Revie

EVALUASI UNJUK KERJA TURBIN AIR PELTON TERBUAT DARI KAYU DAN BAMBU SEBAGAI PEMBANGKIT LISTRIK RAMAH LINGKUNGAN UNTUK PEDESAAN (Performance Evaluation of Hydraulic Pelton Turbine Made of Wood and Bamboo as Environmentally Friendly Electric Generation)

ABSTRAKPemanfaatan energi air di Indonesia, khususnya untuk pembangkit listrik skala kecil di pedesaan masih perlu diprioritaskan untuk ditingkatkan dalam program memperoleh energi bersih yang ramah lingkungan. Pemanfaatan tersebut masih terkendala oleh biaya investasi yang relatif tinggi serta teknologi yang sesuai. Pemerintah mendorong pemanfaatan energi baru dan terbarukan melalui program Desa Mandiri Energi dengan menggunakan potensi dan sumber daya yang tersedia di pedesaan. Kajian ini bertujuan untuk mengevaluasi unjuk kerja turbin air Pelton untuk pembangkit listrik skala kecil dengan sudu terbuat dari bambu dan roda turbin dari kayu. Data yang terkumpul menunjukkan bahwa efisiensi pembangkitan mampu mencapai sekitar 28% untuk debit aliran 28 liter/detik dan tinggi jatuh efektif 7 m menggunakan nosel berpenampang empat persegi panjang. Walaupun dari aspek teknik dan lingkungan penggunaan bambu sebagai sudu turbin adalah baik dan sesuai untuk digunakan di pedesaan, namun unjuk kerja yang diperoleh masih perlu ditingkatkan dibanding dengan umumnya turbin Pelton yang terbuat dari logam. Hal ini diperkirakan karena bentuk alamiah lengkung bambu yang tidak optimum untuk sudu serta bentuk penampang nosel yang masih harus disesuaikan. ABSTRACTThe use of hydroenergy in Indonesia, especially for small electric generation in rural areas is still to be priority increased in a program to find a clean and environmentally friendly energy.  The use is still limited by relatively high investation cost and appropriate technology. Government has pushed the use of new and renewable energy through the Village Self-Relliant Energy Supply Program by using potential and available resources in the village. The objective of this study is to evaluate the performance of a hydraulic Pelton turbine for small electric generation with the buckets are made of bamboo and the runner is made of wood. Data collected from the study show that the efficiency of the generation is capable to be in about 28% for the flow rate of 28 liter/s and effective head of 7 m by using nozel which has a rectangular cross section. Although the use of bamboo as turbine buckets is technicality and environmentally good and it is suitable to be operated in villages but the performance achievement is still need to be increased compared to that of usual Pelton turbine wich is made of metal. This was predicted due to the natural curve profile of the bamboo which is not optimal fit for buckets and the cross sectional geometry of the nozel is still need to be fitted.

Ukuran Omfalokel: Apakah Berhubungan dengan Anomali Kongenital ?

ABSTRACT                                                                     Background: Omphalocele (also known as exomphalus) is a condition that is seen in newborn infants, and is thought to result from failure of the intestines to return to the abdomen after the migration into the umbilical cord. Omphalocele is often associated with the presence of other congenital anomalies. One study says that a small of defect omphalocele is often accompanied by intestinal disorders and have a better prognosis. Purpose(s): Based on this study the researcher wants to review the relationship between the size of  omphalocele defect and the presence of associated congenital anomaly in Hasan Sadikin Hospital. Methods: This is a retrospective cross-sectional study. All patient with omphalocele between February 2007 – March 2012 were included in this study. Data collected were patient demographics, size of omphalocele defect and congenital anomalies identified. In this study, patients were  designated as those with large (greater than 4 cm) or small (4 cm and less) defect omphaloceles. This study analyzed correlation between size of defect with associated anomaly using Fisher exact test  and  p < 0.05 is considered to be significant. Results: There were 52 omphalocele cases (24 girls, 28 boys), median birth weight 2710gr (range 1300gr–4000gr). Twenty seven patients were classified as small defect, with 25 classified as large defect. Anomaly found in the small defect groups consists of facial anomaly (7%); cardiac anomaly (7%); intestinal disorder (22%,P=0,02) include patent omphalomesentericus duct, anorectal malformation and cloaca extrophi; limb anomaly (7%). Meanwhile, anomalies identified in the large defect group consist of facial anomaly (8%); cardac defect (32%) include dextrocardi and tetralogi Fallot; limb anomaly (16%).In this study, cardiac defects was significantly higher in the large defect group, meanwhile intestinal diorder is statistically significant in small defect groups. Conclusion: Small defect omphalocele correlates with an increased prevalence of associated gastrointestinal anomalies and a lower prevalence of cardiac anomalies.Keyword: Omphalocele; Exomphalus; Associated congenital anomalies; Defect siz

Suatu Konsep Tentang Stabilitas Serta Kemungkinan Penerapannya Dalam Analisa Sistem Pertanian. (Stability Concept and The Possibility of Its Application in Agticultural System Analysis)

ABSTRAK This paper briefly describes the concept of stability, in which its mathematical theorems were developed by Liapunov some years ago in the field of electrical engineering. Using a relatively simple mathematical model, the author tries to explain the possibility of its applications in agricultural system analysis. Key words: Stabilitas, teori Liapuno