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"ABSTRAKSolar energy is a huge and infinite source of energy so that solar energy can support energy resilience. Parabolic solar cell reflectors use mirrors. The purpose of this research is to determine the thermal collector's power and thermal efficiency on solar stoves. This research methodology is by taking data with time parameters that have been determined according to environmental conditions. The subjects of this study were parabolic solar cookers with a diameter of 84 cm to 500 gram water. The results of the average stove power obtained by 141.71 Watt and the thermal efficiency of the stove by 5.45%. The power of the stove is affected by the difference in temperature of the water after it has been heated by the temperature of the water before it is heated. The greater the temperature of the water after heating it will increase the power of the stove. The greater the overall heat transfer Qm and the smaller the intensity of solar radiation on the reflector using a mirror, the greater the thermal efficiency."

"Penggunaan teknologi yang semakin luas di kalangan masyarakat membuat kebutuhan akan energi listrik semakin meningkat pula. Sumber daya terbarukan adalah sumber daya yang masih dapat dikembangkan untuk memenuhi kebutuhan listrik di Indonesia, salah satunya adalah energi matahari yang memiliki potensi sebesar 207,8 GWp di Indonesia sendiri. Solar Dish Stirling adalah suatu terobosan baru yang memanfaatkan energi matahari yang terkonsentrasi untuk menggerakkan mesin konversi energi berupa mesin Stirling. Pada penelitian ini, prototipe mesin Stirling dan parabolic dish concentrator dibuat. Parameter-parameter yang diamati ditangkap sensor-sensor berupa suhu. Data diambil setiap 1 jam dalam sehari di daerah UI Depok mulai dari jam 10 sampai jam 3 sore. Efisiensi dan daya output dari sistem dihitung menggunakan model termodinamika. Hasil dari eksperimen menunjukkan perubahan tekanan dan daya output yang dihasilkan mesin per jamnya. Optimasi juga dilakukan menggunakan perangkat lunak excel dengan variasi variabel tekanan awal fluida atau charged pressure dan perbedaan fluida kerja dengan data suhu maksimum dan minimum dari pengamatan sebagai perbandingan hasil penelitian. Kesimpulan dari penelitian ini, kenaikan suhu absorber dapat menurunkan efisiensi absorber akibat naiknya heat losses pada permukaan absorber. Akan tetapi, kenaikan suhu absorber dapat meningkatkan suhu panas pada bagian mesin Stirling sehingga meningkatkan efisiensi termal dan daya output mesin Stirling.......The increasingly widespread use of technology in the community makes the need for electrical energy also increasing. Renewable resources are resources that can still be developed to meet electricity needs in Indonesia, one of which is solar energy which has a potential of 207.8 GWp in Indonesia itself. Solar Dish Stirling is a new breakthrough that utilizes concentrated solar energy to drive an energy conversion engine in the form of a Stirling engine. In this research, prototype Stirling engine and parabolic dish concentrator were made. The observed parameters are captured by sensors in the form of temperature. Data is taken every 1 hour a day in the UI Depok area from 10 am to 3 pm. The efficiency and output power of the system are calculated using a thermodynamic model. The results of the experiment show changes in pressure and output power produced by the engine per hour. Optimization is also carried out using excel software with variations in the initial fluid pressure variable or charged pressure and differences in working fluid with maximum and minimum temperature data from observations as a comparison of research results. The conclusion of this study, the increase in the temperature of the absorber can reduce the efficiency of the absorber due to the increase in heat losses on the surface of the absorber. However, an increase in the absorber temperature can increase the heat temperature of the Stirling engine, thereby increasing the thermal efficiency and output power of the Stirling engine."

"The authors give a comprehensive treatment of the Harnack inequality for non-negative solutions to p-laplace and porous medium type equations, both in the degenerate (p>2 or m>1) and in the singular range (1

"Discontinuous Galerkin (DG) methods for solving partial differential equations, developed in the late 1990s, have become popular among computational scientists. This book covers both theory and computation as it focuses on three primal DG methods -- the symmetric interior penalty Galerkin, incomplete interior penalty Galerkin, and nonsymmetric interior penalty Galerkin which are variations of interior penalty methods. The author provides the basic tools for analysis and discusses coding issues, including data structure, construction of local matrices, and assembling of the global matrix. Computational examples and applications to important engineering problems are also included."

"Kebutuhan listrik merupakan kebutuhan utama masyarakat Indonesia, dan setiap orang. Pada tahun 2020, ada 433 desa tanpa listrik di Indonesia. Indonesia memiliki potensi besar sebagai sumber energi terbarukan. Menurut Kementerian ESDM, total potensi energi terbarukan Indonesia adalah 417,8 gigawatt (GW). Potensi terbesar berasal dari matahari atau matahari sebesar 207.8 GW. Salah satu cara untuk memanfaatkan potensi energi surya yaitu dengan menggunakan Solar Dish Stirling Engine. Penelitian ini menggunakan mesin stirling tipe alpha dan menggunakan udara sebagai fluida kerja. Studi ini bertujuan untuk mengetahui kecepatan putaran mesin, daya output mesin stirling, dan efisiensi daya output mesin stirling dengan menggunakan empat variasi panajang lengan piston yaitu 5 cm – 5 cm ( , 5 cm – 4,3 cm ( , 4,3 cm – 5 cm ( dan 4,3 cm – 4,3 cm ( . Dalam studi ini, penelitian menggunakan lampu halogen 500 Watt sebagai pengganti sumber panas matahri. Dari hasil penelitian, diperoleh kecepatan rpm maksimum pada 852 rpm dengan panjang lengan di 5 cm – 5 cm ( ). Hasil penelitian juga diperoleh bahwa kecepatan putaran mesin optimum terdapat pada panjang lengan 5 cm – 5 cm ( ) dengan nilai 0,39 W pada 839 rpm. Terakhir diketahui bahwa effisiensi mesin stirling terbesar yaitu 6,5 % pada panjang lengan 5 cm – 5 cm ( ).......The need for electricity is the main need of the Indonesian people, and everyone. In 2020, there are 433 villages without electricity in Indonesia. Indonesia has great potential as a source of renewable energy. According to the Ministry of Energy and Mineral Resources, Indonesia's total renewable energy potential is 417.8 gigawatts (GW). The greatest potential comes from the sun at 207.8 GW. One way to utilize the potential of solar energy is to use the Solar Dish Stirling Engine. This research uses an alpha stirling engine and uses air as the working fluid. This study aims to determine the engine rotation speed, Stirling engine output power, and Stirling engine output power efficiency using four variations of the piston arm length, namely 5 cm – 5 cm ( , 5 cm – 4,3 cm ( , 4,3 cm – 5 cm ( and 4,3 cm – 4,3 cm ( . In this study, the research used a 500 Watt halogen lamp as a substitute for the solar heat source. From the results of the study, the maximum rpm speed was obtained at 852 rpm with an arm length of 5 cm – 5 cm ( . The results of the study also showed that optimum engine rotation speed was found in the length of the arm 5 cm – 5 cm ( dengan nilai 0,39 W pada 839 rpm. Finally, it is known that the largest stirling engine efficiency is 6,5% at arm length 5 cm – 5 cm."

"Investigasi terhadap struktur elektronik, magnetik, dan sifat termolektrik dari heavily–doped Ca0.5La0.5MnO3 (CLMO) dan Ca0.5La0.25Bi0.25MnO3 (CLBMO) dilakukan dengan metode komputasi density functional theory (DFT) dan transportasi Boltzmann. Sedangkan optimasi termoelektrik dari kedua kompon diperoleh dengan menggunakan model restructured single parabolic band. Baik CLMO dan CLBMO dengan struktur kristal orthorhombic (Pnma), menunjukkan keadaan paling stabil pada konfigurasi feromagnetik dengan energi total minimum paling rendah. Doping Bi pada CLBMO mereduksi sudut ikatan Mn–O–Mn yang menyebabkan distorsi kisi dan membentuk hibridisasi Bi 6s – O 2p yang berkompetisi dengan hibridisasi Mn 3d – O 2p. Mekanisme tersebut secara simultan menurunkan konduktivitas listrik dan konduktivitas termal dari CLBMO. CLBMO menunjukkan optimasi power factor masing-masing sebesar 49% dan 69% pada suhu 300 K dan 800 K. Sedangkan CLMO hanya memberikan optimasi sebesar 13% dan 30% pada suhu yang sama. Kedua kompon memiliki konduktivitas termal fonon tiga sampai empat orde lebih kecil dari konduktivitas termal elektroniknya. Dengan demikian perhitungan figure of merit, ZT, hanya didasarkan pada mekanisme transport pembawa muatan, dan tidak melibatkan transport fonon yang menjadikan perhitungan lebih rumit. Nilai ZT dikoreksi dengan melibatkan rasio waktu relaksasi konduktivitas listrik terhadap waktu relaksasi konduktivitas termal elektronik, ts/tke, yang berbanding terbalik dengan rasio bilangan Lorenz terhadap degenarate limit, L/Lo.......Investigations on the electronic structure, magnetic, and thermoelectric properties of heavily-doped Ca0.5La0.5MnO3 (CLMO) and Ca0.5La0.25Bi0.25MnO3 (CLBMO) are carried out using density functional theory (DFT) computational methods and Boltzmann transport. Meanwhile, the thermoelectric optimization of the two compounds is obtained by using a restructured single parabolic band model. Both CLMO and CLBMO with the orthorhombic crystal structure (Pnma), show the most stable state in the ferromagnetic configuration with the lowest minimum total energy. Bi-doping in CLBMO reduces the Mn–O–Mn bond angle which causes lattice distortion and forms Bi 6s – O 2p hybridization which competes with Mn 3d – O 2p hybridization. This mechanism simultaneously reduces the electrical conductivity and thermal conductivity of CLBMO. CLBMO shows optimization of power factors of 49% and 69% at temperatures of 300 K and 800 K, respectively. While CLMO only provides optimization of 13% and 30% at the same temperature. Both compounds have phonon thermal conductivity two to three orders of magnitude lower than their electronic thermal conductivity. Thus the calculation of the figure of merit, ZT, is only based on the mechanism of charge carrier transport and does not involve phonon transport which leads to a more complicated calculation. The ZT value is corrected by involving the ratio of the relaxation time of the electrical conductivity to the relaxation time of the electronic thermal conductivity, ts/tke, which is inversely proportional to the ratio of the Lorenz number to the degenerate limit, L/Lo."

"Parabolic solar concentrator merupakan salah satu pemanas air tenaga surya yang mempunyai kemampuan untuk membangkitkan uap air dengan temperatur yang tinggi, prinsip kerja parabolic solar concentrator yaitu mengkonsentrasikan panas matahari yang di dapat oleh oleh optik ke suatu titik. Keberhasilan alat uji ini di dasarkan pada volume air hasil destilasi dari alat tersebut.Penelitian desalinasi air laut ini dilakukan dengan menggunakan solar concentrator parabolic di buat dengan ukuran panjang 500 mm dan lebar 500 mm, dan titik fokusnya 100 mm, reflektor di rancang sedemikian rupa dan di sinari secara langsung, kolektor yang berisi sampel air laut di letakan di atas reflektor tepat pada posisi titik fokus. Selama pemanasan suhu di ukur dan diamati setiap 5 menit, hasil penelitian menunjukan bahwa suhu maksimal sampel air laut menggunakan reflektor sebesar 98,6°C dan suhu maksimum pada kolektor yaitu sebesar 165,8°C dan hasil volume destilasi yaitu sebesar 80 ml perjam. ......Parabolic solar concentrator is a solar water heater that has the ability to generate vapour at high temperatures, the working principle of solar parabolic concentrator that concentrates the sun's heat in the can by the optics to a point. The success of this test is based on the volume of water distilled from the tool.Research seawater desalination is done by using a solar concentrator parabolic created with a length of 500 mm and a width of 500 mm, and the focal point of 100 mm, the reflector is designed in such a way and illuminated directly, collectors which contains samples of sea water in the put on top right reflector at the focal point position. During the heating temperature is measured and observed every 5 minutes, research shows that the maximum temperature of the sea water sample using the reflector of 98.6°C and the maximum temperature at the collector is equal to 165.8°C and the results distillation volume amounting to 80 ml per hour. "

"Mathematical control theory for a single partial differential equation (PDE) has dominated the research literature for quite a while, new, complex, and challenging issues have recently arisen in the context of coupled, or interconnected, PDE systems. This has led to a rapidly growing interest, and many unanswered questions, within the PDE community. By concentrating on systems of hyperbolic and parabolic coupled PDEs that are nonlinear, Mathematical Control Theory of Coupled PDEs seeks to provide a mathematical theory for the solution of three main problems: well-posedness and regularity of the controlled dynamics; stabilization and stability; and optimal control for both finite and infinite horizon problems along with existence/uniqueness issues of the associated Riccati equations.Mathematical Control Theory of Coupled PDEs is based on a series of lectures that are outgrowths of recent research in the area of control theory for systems governed by coupled PDEs. The book develops new mathematical tools amenable to a rigorous analysis of related control problems and the construction of viable control algorithms. Emphasis is placed on the key role played by two interweaving features of the respective dynamical components: (1) propagation of singularities and exceptional "sharp" regularity of the traces of the solutions of the structure's hyperbolic component, and (2) analyticity of the solutions to the parabolic component of the structure, its propagation, and related analytic semigroup (singular) estimates.In addition to providing a mathematical foundation on this topic, this book is useful to engineers and professionals involved in materials science and aerospace engineering in solving fundamental theoretical control problems such as stabilization and optimal control in the context of control systems described by dynamical coupled PDEs. Modern technological applications such as smart materials, interactive systems, and intelligent controls drive further interest in this topic. Included is a wealth of examples based on the structural acoustic model. This comprises a wave equation coupled on the interface with either a plate or a shell equation. This canonical model nonetheless displays a variety of phenomena of interest."

"This book primarily focuses on rigorous mathematical formulation and treatment of static problems arising in continuum mechanics of solids at large or small strains, as well as their various evolutionary variants, including thermodynamics. As such, the theory of boundary- or initial-boundary-value problems for linear, quasilinear elliptic, parabolic or hyperbolic partial differential equations is the main underlying mathematical tool, along with the calculus of variations. Modern concepts of these disciplines as weak solutions, polyconvexity, quasiconvexity, nonsimple materials, materials with various rheologies or with internal variables are exploited."