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Abstrak :
Penelitian tesis ini mengembangkan pemodelan matematis pembangkitan panas pada FSSW. Pemodelan secara analitik dibuat untuk empat jenis geometri pahat. Parameter kecepatan putar pahat yang dipergunakan sangat tinggi saat tidak ada beban asymp; 32000 RPM jika dibandingkan dengan penelitian lainnya yang berkisar 600 ndash; 3000 RPM. Berdasarkan hasil eksperimen didapatkan bahwa kecepatan putar nilainya sangat dinamis, hal ini dipengaruhi oleh beberapa faktor antara lain, gaya aksial, dimensi pahat, koefisien gaya gesek, kedalaman penetrasi, dan faktor slip. Fokus dari penelitian ini adalah mencari tahu sejauh mana parameter faktor slip slip factor dapat mempengaruhi nilai pembangkitan panas. Parameter lainnya telah dibatasi dan diasumsikan dengan merujuk pada studi literatur, sedangkan dari keempat geometri yang telah dibuat hanya pahat pelat datar yang dilakukan uji simulasi. Untuk melihat pengaruh variasi faktor slip maka dilakukan uji simulasi pembangkitan panas dengan menggunakan MATLAB dan simulasi temperatur transien dengan menggunakan ANSYS. Objek benda kerja yang dipergunakan adalah pelat tipis alumunium alloy AA2024 dengan ketebalan 0,4 mm. Hasil simulasi menunjukkan faktor slip sangat mempengaruhi hasil pembangkitan panas, hal ini dikarenakan nilai flow stress yang dihitung dengan menggunakan Sheppard-Wright material model jauh lebih besar dari nilai shear stress sehingga sedikit saja pertambahan faktor slip akan berdampak signifikan terhadap nilai pembangkitan panas.

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This thesis research develops mathematical modeling of heat generation in FSSW. Analytical modeling was made for four types of tools geometry. Rotational speed parameters used are extremely high when no load asymp 32000 RPM when compared with other studies ranging from 600 to 3000 RPM. Based on experimental results it is found that the rotational speed is very dynamic, this was influenced by several factors, among others, axial force, tool dimension, coefficient of friction force, penetration depth, and slip factor. The focus of this study is to find out the extent to which slip factor parameters can affect the value of heat generation. Other parameters have been limited and assumed by referring to literature studies, whereas of the four geometries that have been made only flat tool performed simulation tests. To see the effect of variation of slip factor, the simulation of heat generation using MATLAB and transient temperature simulation using ANSYS. The object of the workpiece used was a thin plate of aluminum alloy AA2024 with a thickness of 0.4 mm. Simulation results show that the slip factor greatly affects heat generation results, this is because the value of the flow stress calculated by using Sheppard Wright material model is much larger than the shear stress so that a slight increase in the slip factor will have a significant impact on the heat generation value.

Abstrak :
ABSTRAK
Nuklir adalah salah satu sumber energi baru yang patut dipertimbangkan untuk memenuhi kebutuhan energi nasional. Penggunaan bahan nuklir berbasis thorium oksida ThO2 telah dikembangankan oleh beberapa negara maju sebagai bahan bakar nuklir untuk mengurangi dan menggantikan pemakaian uranium yang banyak digunakan sebagai bahan bakar untuk pembangkit listrik tenaga nuklir PLTN di dunia. Pada saat ini Batan Tenaga Nuklir Nasional BATAN berusaha merancang suatu reaktor daya eksperimental RDE dari turunan reaktor tipe High Temperature Gas-cooled Reactor HTGR . Reaktor nuklir tipe HTGR mempunyai dua bentuk bahan bakar yaitu prismatik dan bola pebble . RDE yang akan dikembangkan di Indonesia mempunyai bahan bakar uranium dan atau thorium berbentuk bola. Dalam penelitian ini dilakukan pemodelan dan simulasi panas pembangkitan oleh reaksi fisi yang disebabkan oleh neutron, dan perpindahan panas antara bahan bakar bentuk pebble dengan media pendingin gas helium pada reaktor daya eksperimental. Analisis neutronik dan termal-aliran dalam teras RDE seperti ini belum pernah dilakukan di Indonesia. Tujuan dilakukannya penelitian ini adalah untuk memperoleh desain teras yang aman pada kondisi neutronik yang kritis dari teras RDE. Pemodelan dan simulasi transport partikel neutron untuk analisis pembangkitan panas reaksi fisi dilakukan dengan perangkat lunak berbasis metoda monte carlo-MCNP, dan untuk fenomena transport dalam proses pendinginan RDE dilakukan dengan perangkat lunak komputasi dinamika fluida FLUENT 6.3. Teras aktif RDE dimodelkan dengan geometri silinder berdiameter 180 cm dan tinggi 197 cm. MCNP dapat memodelkan struktur geometri bahan bakar bola dalam teras reaktor RDE dengan baik untuk mensimulasikan transport neutron dan distribusi reaksi fisi. Aliran pendingin gas helium melalui bola-bola bahan bakar dalam teras reaktor dimodelkan sebagai aliran fluida dalam medium berpori. Tiga mode perpindahan panas dan aliran turbulen pendingin dimodelkan dalam proses pendinginan. Dari pemodelan dan simulasi neutronik diperoleh nilai kritikalitas keff =1.0921 dan densitas daya yang dihasilkan sebesar 2.03 watts/cm3. Hasil ini kemudian dimasukkan dalam pemodelan proses pendinginan dan aliran fluida dalam teras RDE sehingga menghasilkan temperatur maksimum pendingin gas helium sebesar 970.32K. Kritikalitas neutronik keff lebih dari satu, tetapi tak melebihi 1,3 dan kondisi termal teras menunjukkan bahwa desain teras RDE sangat aman.

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ABSTRACT
Nuclear is one of new energy sources that should be considered to meet national energy demands. The usage of Thorium Oxide ThO2 based nuclear fuel has been developed by some developed countries to reduce and replace Uranium that was commonly used as nuclear fuel for nuclear power plants in the world. Nowdays, BATAN is trying to design an experimental power reactor RDE which is the derivative type of High Temperature Gas cooled Reactor HTGR . HTGR has two types of fuel i.e. Prismatic and Pebble. RDE, which will be developed in Indonesia uses spherical uranium and or thorium as its fuel. This research performs modeling and simulation of fission heat generation caused by neutronas well heat transfer between fuel pebble and helium gas as cooling medium in the experimental power reactor. This thermal flow analysis in the RDE core has never been conducted in Indonesia. The objective of this study is to obtain a safe reactor core design in critical neutronic condition of the RDE core. Modeling and simulation of neutron particle transport for fission heat generation analysis were conducted using a software based on Monte Carlo method MCNP, and for the transport phenomena in the cooling process of RDE was conducted using computational fluid dynamics software FLUENT 6.3.26. RDE active core was modeled using cylindrical geometry with a diameter of 180 cm and 197 cm high. MCNP can model the geometrical structure of the Pebble fuel within the RDE core properly to simulate neutron transport and distribution of fission reaction. Flow of helium gas coolant through the pebble fuel in the reactor core was modeled as a fluid flow in a porous medium. Three types of heat transfer and turbulent coolant flow were modeled in the cooling process. Results obtained from Neutronic modeling and simulation i.e. criticality values of 1.0921 keff and average power density of 2.03 watts cm3. These results were later inserted into the cooling process and fluid flow modeling in the RDE core, so that generate the maximum temperature of the coolant helium gas at about 970.32 K. Neutronic criticality more than one, but not exceeding 1.3 and the core thermal conditions showed that the design of the RDE core is very safe.

Abstrak :
This book highlights the theoretical foundations of and experimental techniques in photothermal heating and applications involving nanoscale heat generation using gold nanostructures embedded in various media. The experimental techniques presented involve a combination of nanothermometers doped with rare-earth atoms, plasmonic heaters and near-field microscopy. The theoretical foundations are based on the Maxwells and heat diffusion equations. In particular, the working principle and application of AlGaN:Er3+ film, Er2O3 nanoparticles and β-NaYF4:Yb3+,Er3+ nanocrystals for nanothermometry based on Er3+ emission are discussed. The relationship between superheated liquid and bubble formation for optically excited nanostructures and the effects of the surrounding medium and solution properties on light absorption and scattering are presented. The application of Er2O3 and β-NaYF4:Yb3+,Er3+ nanocrystals to study the temperature of optically heated gold nanoparticles is also presented. In closing, the book presents a new thermal imaging technique combining near-field microscopy and Er3+ photoluminescence spectroscopy to monitor the photothermal heating and steady-state sub-diffraction local temperature of optically excited gold nanostructures.

Abstrak :
This book highlights the theoretical foundations of and experimental techniques in photothermal heating and applications involving nanoscale heat generation using gold nanostructures embedded in various media. The experimental techniques presented involve a combination of nanothermometers doped with rare-earth atoms, plasmonic heaters and near-field microscopy. The theoretical foundations are based on the Maxwell’s and heat diffusion equations. In particular, the working principle and application of AlGaN:Er3+ film, Er2O3 nanoparticles and β-NaYF4:Yb3+,Er3+ nanocrystals for nanothermometry based on Er3+ emission are discussed. The relationship between superheated liquid and bubble formation for optically excited nanostructures and the effects of the surrounding medium and solution properties on light absorption and scattering are presented. The application of Er2O3 and β-NaYF4:Yb3+,Er3+ nanocrystals to study the temperature of optically heated gold nanoparticles is also presented. In closing, the book presents a new thermal imaging technique combining near-field microscopy and Er3+ photoluminescence spectroscopy to monitor the photothermal heating and steady-state sub-diffraction local temperature of optically excited gold nanostructures.