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Abstrak :
[Adiabatic logic is a potential successor for static CMOS circuit design when it comes to ultra-low-power energy consumption. Future development like the evolutionary shrinking of the minimum feature size as well as revolutionary novel transistor concepts will change the gate level savings gained by adiabatic logic. In addition, the impact of worsening degradation effects has to be considered in the design of adiabatic circuits. The impact of the technology trends on the figures of merit of adiabatic logic, energy saving potential and optimum operating frequency, are investigated, as well as degradation related issues. Adiabatic logic benefits from future devices, is not susceptible to Hot Carrier Injection, and shows less impact of Bias Temperature Instability than static CMOS circuits. , Adiabatic logic is a potential successor for static CMOS circuit design when it comes to ultra-low-power energy consumption. Future development like the evolutionary shrinking of the minimum feature size as well as revolutionary novel transistor concepts will change the gate level savings gained by adiabatic logic. In addition, the impact of worsening degradation effects has to be considered in the design of adiabatic circuits. The impact of the technology trends on the figures of merit of adiabatic logic, energy saving potential and optimum operating frequency, are investigated, as well as degradation related issues. Adiabatic logic benefits from future devices, is not susceptible to Hot Carrier Injection, and shows less impact of Bias Temperature Instability than static CMOS circuits. ]

Abstrak :
Pembakaran spontan pada batubara merupakan salah satu masalah besar bagi industri penambangan dan pemanfaat batubara. Pembakaran spontan pada batubara di pengaruhi oleh banyak faktor , baik faktor internal maupun eksternal. Salah satu faktor eksternal adalah kelembaban relatif. Di indonesia yang beriklim tropis dan mempunyai kelembaban udara cukup tinggi faktor ini sangat penting. Metode pengujian yang digunakan untuk penelitian ini adalah metode oksidasi adiabatik. Metode ini beroperasi pada temperatur awal sekitar 40oC, sehingga mensimulasikan kondisi mendekati nyata seperti yang terjadi dilapangan. Secara khusus penelitian ini membahas pengaruh kelembaban relatif pada laju peningkatan temperatur batubara dan kondisi tercapainya pembakaran spontan.

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Spontaneous combustion of coals cause one of big problem for coal mining industry and coal user. Spontaneous combustion influences a lot of factors, internal also external factors. One of external factor is relative humidity. In Indonesian which have the tropical climate and have high air humidity enough this factor of vital importance. An adiabatic oxidation testing method used for this experiment. This method operate on initial temperature 40 oC, that condition of simulation near reality such as those which happened on the field. Special this research study influence of relative humidity on temperature rises and ignited state.

Abstrak :
Cadangan batubara Indonesia sebagian besar lebih dari 60 merupakan batubara dengan kalori rendah dan sedang yang dikenal dengan batubara peringkat rendah. Pada skenario KEN, pertumbuhan kebutuhan batubara rata-rata sebesar 5,1 dimana pada tahun 2025 kebutuhan batubara mencapai 37 juta Toe dan meningkat hingga mencapai 116 juta Toe di tahun 2050.Pemanasan mandiri self-heating dan pembakaran spontan spontaneous combustion batubara telah menjadi masalah serius di industri batubara. Kebakaran Batubara dan gambut dari Indonesia sering terjadi akibat kebakaran hutan di dekat singkapan.Kegiatan utama dari studi saat ini adalah melakukan eksperimen terhadap batubara peringkat rendah Indonesia dengan menggunakan metode uji yang berbeda TG-DTA, metode crossing point / CPT dan metode adiabatik . Selain itu, dilakukan pemodelan dengan piranti lunak COMSOL Multiphysics dan validasi dengan data eksperimen serta studi parametrik.Hasil pemodelan menunjukkan hasil yang berkesesuaian dengan data hasil ekperimen dengan penyimpangan temperatur sekitar 0,9 untuk CPT dan 1,5 untuk reaktor adiabatik.Dari studi parametrik di dapatkan bahwa porositas tumpukan dan konsentrasi oksigen memiliki efek yang cukup besar terhadap perilaku pembakaran spontan dan perlu mendapatkan perhatian dalam upaya untuk mencegah pembakaran spontan.Pemodelan dan Simulasi dapat digunakan sebagai alatbantu yang efektif untuk mencegah dan mencari solusi permasalah pembakaran spontan pada aplikasi di lapangan.

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Indonesia's coal reserves mostly over 60 are low to moderate calorie coal known as low rank coal. In the KEN scenario, the average coal demand growth of 5.1 is where in 2025 the demand for coal reaches 37 million toe and increases to 116 million toe in 2050.Self heating and spontaneous combustion of coal have become a serious problem in the coal industry. Coal and peat fires from Indonesia often occur due to forest fires near the outcrop.The main activity of the current study is to conduct experiments on Indonesia's low rank coal using different test methods TG DTA, crossing point CPT method and adiabatic method. In addition, modeling with COMSOL Multiphysics software and validation with experimental data and parametric studies were performed.The modeling results show results that are compatible with experimental data with a temperature drift of about 0.9 for CPT and 1.5 for adiabatic reactors. From the parametric study it was found that the porosity of the pile and the oxygen concentration had a considerable effect on spontaneous combustion behavior and needed to get attention in an effort to prevent spontaneous combustion.Modeling and Simulation can be used as an effective tool to prevent and solve spontaneous combustion problems in field applications.

Abstrak :
Determination of thermal time constant of fuel pin during nuclear reactor shut down by using adiabatic model. A complex shut down process of nuclear depends on different parameters of fuel design and of reactor operation. In correlation to TIA and LOCA analyses of reactor core, the shut down process is charactirized by a time constant...

Abstrak :
Pada thesis ini telah dilakukan studi dinamika domain wall (DW) magnetik pada nanowire Permalloy dengan notch simetris yang terinduksi oleh pulsa arus listrik terpolarisasi. Analisis dilakukan menggunakan pendekatan mikromagnetik menggunakan perangkat lunak OOMMF berdasarkan persamaan Landau-Lifshitz- Gilbert (LLG) yang dimodifikasi. Dalam persamaan LLG tersebut diperkenalkan besaran tambahan berupa kecepatan spin (u) dan konstanta non-adiabatik (β) yang menunjukkan suku transfer spin. Sebuah defek pada nanowire Permalloy dibuat berbentuk notch segitiga simetris sebagai potensial pinning untuk DW. Penelitian dilakukan dengan mengamati efek lebar wire, ukuran notch, dan variasi konstanta non-adiabatik terhadap sifat depinning DW di sekitar pusat notch. Berdasarkan hasil simulasi ditunjukkan bahwa penurunan nilai arus depinning (Jd) dipengaruhi oleh peningkatan lebar wire yang sesuai dengan fenomena yang terjadi pada kasus induksi medan magnet. Pada ukuran notch 40 nm, nilai Jd menurun secara drastis namun berfluktuasi sebanding dengan peningkatan ukuran notch. Diketahui juga bahwa lebar wire tidak berpengaruh terhadap waktu depinning untuk ukuran notch kurang dari 70 nm. Secara umum, proses depinning pada DW diikuti oleh perubahan struktur dari transverse wall menjadi anti-vortex wall. Berdasarkan hasil simulasi diketahui bahwa efek konstanta non-adiabatik tidak signifikan pada ukuran notch kurang dari 70 nm. Namun pada ukuran yang lebih besar terjadi fluktuasi pada karakteristik depinning DW. Hasil yang menarik diamati pada β = 0.04 yaitu ukuran notch tidak mempengaruhi waktu depinning DW. Hal ini dapat dipahami bahwa perubahan struktur DW berperan penting terhadap karakteristik depinning DW. ......We have investigated the magnetic domain wall (DW) dynamics in symmetrical notched Permalloy nanowires induced by nanosecond current pulse using micromagnetic approach. The public micromagnetic software OOMMF has been utilized to simulate the domain wall behavior based on modified Landau- Lifshitz-Gilbert (LLG) Equation. The spin transfer term was added to the LLG equation by introduced the spin drift velocity (u) and non-adiabatic constant (β) values. The constriction in the Permalloy nanowires was shaped as double symmetrical triangular notch and used as the DW pinning potential. We have observed the effect of wire width, notch size, and non-adiabatic constant to the DW depinning behavior around the center of notch. We observed that the increasing of wire width was influenced to the decreasing of depinning current density (Jd) as in the field driven case. At notch size of 40 nm, the Jd value was sharply decreased and yield slight fluctuation as the increasing of notch size. It also known that wire width was not much affect the DW depinning time for notch size smaller than 70 nm. Generally the DW depinning process was accompanied by the structure transition from transverse wall to anti-vortex wall. We observed that in the notch size smaller than 70 nm the effect of non-adiabatic constant was not significant, but at the larger notch size recorded a huge fluctuation of DW characteristics. The interesting result was founded at β = 0.04 which the depinning time was not affected by the increasing of notch size. It was understood that the DW inner structure stabilities play the role for the insensitivity of DW depinning behavior.