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Abstrak :
ABSTRAK Alumina anhidrat terdapat dalam bentuk alumina metastabil (÷ -, ç -, ã-, ê-, ä- dan è-alumina) dan alumina stabil (á-alumina). Beberapa bentuk alumina mempunyai struktur berpori dan tuas permukaan besar, sehingga dapat dimanfaatkan sebagai adsorben. Umumnya adsorben alumina dibuat dari bauksit dengan proses Bayer. Penelitian ini bertujuan membuat adsorben alumina dari kaolin. Percobaan dilakukan dengan pemanasan campuran kaolin dan amonium sulfat pada suhu tertentu untuk menghasilkan amonium alum sebagai basil antara. Dekomposisi amonium alum untuk menghasilkan alumina dilakukan pada suhu tertentu. Suhu pembentukkan amonium alum dan suhu pembentukkan alumina ditentukan berdasarkan basil analisis DTA-TGA. Amonium alum dan alumina yang diperoleh dibuktikan dengan analisis difraksi sinar-X. Perbandingan dan waktu pemanasan campuran kaolin dengan amonium sulfat divariasikan untuk memperoleh jumlah amonium alum optimum. Untuk memperoleh alumina dengan daya adsorpsi terbesar, dilakukan variasi waktu pemanasan amonium alum. Data adsorpsi alumina yang dihasilkan ditunjang oleh pengukuran kehilangan berat, luas permukaan dan struktur kristal. Dari penelitian ini, jumlah optimum amonium alum dihasilkan dari pemanasan campuran kaolin dan amonium sulfat dengan perbandingan berat 1:4 pada suhu 363°C selama 10 jam. Adsorben alumina dengan daya adsorpsi terbesar dihasilkan dari pemanasan amonium alum pada suhu 900°C selama 3 jam. Adsorben alumina tersebut mempunyai struktur kristal yang terdiri dari campuran ÷-, ç- dan ã-Al203 dengan struktur dominan ÷-Al203, luas permukaan 139,83 m2/g dan kapasitas adsorpsi ortofosfat 0,391 mek/g. Perolehan adsorben alumina dad kaolin sebesar 14,68%.

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Anhydrate alumina, M203, consist of a stable- (á -alumina) and a metastable (÷ -, ç -, ã-, ê-, ä- dan è-alumina) forms. Some of the metastable form of alumina has a high porosity and very high surface area; these properties are commonly exploited as an adsorbent. The most commonly process for a preparation of alumina adsorbent is the "Bayer process", which employees of bauxite as a raw materials. The purpose of this research is to prepared adsorbent alumina from kaolin. It is well that when the mixture kaolin and ammonium sulphate are heated at certain temperature, intermediate compound of ammonium alum will be produced. Later, this intermediate compound decomposes to form alumina. The forming temperature ammonium alum and alumina determined by using the DTA-TGA analysis. X-Ray Diffraction (XRD) analizes ammonium alum and alumina produced at the observed temperature. To obtain the maximum amount of ammonium alum, the ratio of kaolin and ammonium sulphate mixture and the heated time at certain temperature is varied. To obtained the alumina with the maximum adsorption, the heated time of the decomposition ammonium alum also varied. Measuring the reduced weight, surface area and structural analysis supports the adsorption data. This research showed that the maximum amount of ammonium alum could be produced when the mixture kaolin and ammonium sulphate 1: 4 was heated at 363°C for 10 hours period. Alumina with maximum adsorption capacity could be produced when ammonium alum decomposed at 900°C for 3 hours period. Alumina produced from this method are dominantly composed of the -Al2O3 xstructure, with a measured surface area is 39,83 m21g and the phosphate adsorption capacity is 30,43 meg/g. The yield of alumina from kaolin is 14,68%.

Abstrak :
Lantanum manganat LaMnO3 (LMO) adalah material yang sedang menjadi perhatian banyak peneliti sampai saat ini karena memiliki potensi untuk diterapkan pada berbagai aplikasi terutama pada bidang magnetik-elektrik. Modifikasi struktur kristal senyawa LMO melalui subsitusi parsial ion La dan Mn dapat menginduksi sifat elektrik-magnetik seperti giant magneto resistance (GMR) atau colossal magneto resistance (CMR). Berdasarkan telusuran literatur, diketahui bahwa substitusi parsial ion La oleh ion Sr dan ion Mn oleh ion Fe dapat menimbulkan sifat baru, selain GMR atau CMR, juga memiliki kemampuan menyerap gelombang elektromagnetik, khususnya dalam rentang frekwensi ultra-tinggi (GHz). Dengan demikian senyawa LMO termodifikasi adalah merupakan salah satu radar absorbing materials (RAM) yaitu suatu material berkemampuan menyerap gelombang radar. Pada penelitian ini, dipelajari rekayasa struktur senyawa LMO dengan komposisi (La1-xSrx) (Mn0,25Fe0,5Ti0,25)O3 dimana x =0,25; 0,5; 0,75 dan 1,0. Pada tahapan sintesis material diperkenalkan teknik penggabungan antara pemaduan mekanik (mechanical alloying) dan destruksi sonikasi daya tinggi untuk menghasilkan ukuran rata-rata partikel skala nanometer. Karakterisasi material mencakup observasi struktur mikro, identifikasi fasa, sifat magnetik dan sifat absorbsi. Hasil penelitian menunjukkan bahwa material hasil pemaduan mekanik memiliki distribusi ukuran rata-rata partikel bimodal dengan waktu penghalusan relatif panjang (puluhan sampai ratusan jam) untuk memperoleh ukuran partikel rata-rata terendah. Bila sintesis melibatkan destruksi ultrasonik, distribusi ukuran partikel bersifat monomodal dengan ukuran partikel rata-rata mencapai <100 nm dalam waktu kurang dari 10 jam. Pola difraksi sinar X material memperlihatkan bahwa keseluruhan komposisi memiliki fasa tunggal dikarenakan jari-jari ion La dan Sr setara, demikian juga ion Fe dan Mn. Hasil evaluasi karakteristik serapan gelombang mikro material berdasarkan pengujian Vector Network Analyzer (VNA) memastikan bahwa keseluruhan material bersifat penyerap gelombang mikro dalam jangkau frekwensi 8 - 15 GHz. Serapan tertinggi terjadi pada frekwensi 14,8 GHz dengan nilai Reflection Loss ~ 1 dB atau 10 % gelombang yang datang diserap oleh material. Efek ukuran partikel dengan nilai rata-rata 90 nm meningkatkan kemampuan penyerapan hingga mencapai lebih dari 60 %. Penggabungan material ini dengan senyawa magnetik hexaferrite pada jaringan komposit memperlihatkan dua serapan setara pada dua frekwensi yang berbeda (10 dan 14,8 Ghz). Pengaruh komposisi pada sistem komposit memberikan efek pelebaran terhadap kedua puncak serapan hingga terbentuk sebuah serapan dengan jangkau frekwensi yang lebar (8-15 GHz). Kesimpulan pada penelitian ini adalah sintesis material penyerap gelombang mikro senyawa (La1-xSrx) (Mn0,25Fe0,5Ti0,25)O3 dengan ukuran rata-rata kristal berskala nanometer diperoleh secara efektif melalui penggabungan teknik pemaduan mekanik dan destruksi ultrasonik. Efek ukuran partikel adalah meningkatkan daya serap material. Penggabungan material ini dengan material magnetik hexaferrite dalam sistem komposit menghasilkan suatu material penyerap gelombang mikro dalam rentang frekwensi serapan yang lebar.

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Lanthanum manganites, LMO especially those doped LaMnO3, have attracted attentions of many researchers, due to their significant potential for applications in the field of magnetic electronic functional materials. Structural modification either through doping of La with Ca, Sr, and Ba or Mn with Fe, Cu, and Ti has been reported to induce electromagnetic properties such as giant magneto resistance (GMR) or colossal magneto resistance (CMR). A partial substitution of La with Sr or Mn with Fe gives rise to new properties, in addition to the GMR or CMR, in which the substituted LMO has the ability to absorb electromagnetic waves, especially in the ultra-high frequency range (GHz). Thus, doped LaMnO3 can be considered as one of radar-absorbing materials (RAM). In this study, structural modification of LMO with designated compositions (La1-xSrx) (Mn0.25Fe0.50Ti0.25)O3 where as x = 0.25; 0.50; 0.75 and 1.0 is reported. The materials were prepared by mechanical alloying assisted with high-power sonication to produce particles with mean size in a nanometer scale. Material characterization includes the observation of microstructures, identification oh phase materials, magnetic properties and microwave absorption characteristics. It was found that mechanically alloyed of doped LMO have a bimodal particle size distribution and required a relatively long milling time (tens to hundreds of hours) to obtain the lowest average particle size. It was also found that when sintered mechanically alloyed powders were further treated under the application of a high power sonicator, a monomodal particle size distribution with mean particle size of less than 100 nm was obtained within less than 10 hrs. X-ray diffraction traces indicated that synthesized materials are single phase due to ionic radii of La and Sr ions are almost similar. This is also applicable to Fe and Mn ions. Results of microwave absorption characteristics as evaluated by Vector Network Analyzer ensure that the entire materials have capability to absorb the microwaves in the frequency range 8-15 GHz. The highest absorption was occurred at 14.8 GHz with a Reflection Loss ~ 1 dB. It means that only 10% of the incident wave energy was absorbed by the material. However, materials with the average particle size ~ 90 nm increased the absorption up to 60%. Incorporation the doped LMO with hexaferrite particles in a composite structure has resulted two similar absorption peaks at two different frequencies (10 and 14.8 GHz). Furthermore, variation in composition of composite system was widening the absorption peak into a single peak with a wide range frequency (8-15 GHz). It is concluded that mechanical alloying coupled with ultra sonication can be an alternative route for the preparation of fine and homogeneous powder materials leading to nanoparticle-based materials. Effect of fine particles in the materials is to increase the microwave absorbing properties. Where as the composite structure is to affect the frequency absorption width.

Abstrak :
Lantanum manganat LaMnO3 (LMO) adalah material yang sedang menjadi perhatian banyak peneliti sampai saat ini karena memiliki potensi untuk diterapkan pada berbagai aplikasi terutama pada bidang magnetik-elektrik. Modifikasi struktur kristal senyawa LMO melalui subsitusi parsial ion La dan Mn dapat menginduksi sifat elektrik-magnetik seperti giant magneto resistance (GMR) atau colossal magneto resistance (CMR). Berdasarkan telusuran literatur, diketahui bahwa substitusi parsial ion La oleh ion Sr dan ion Mn oleh ion Fe dapat menimbulkan sifat baru, selain GMR atau CMR, juga memiliki kemampuan menyerap gelombang elektromagnetik, khususnya dalam rentang frekwensi ultra-tinggi (GHz). Dengan demikian senyawa LMO termodifikasi adalah merupakan salah satu radar absorbing materials (RAM) yaitu suatu material berkemampuan menyerap gelombang radar. Pada penelitian ini, dipelajari rekayasa struktur senyawa LMO dengan komposisi (La1-xSrx) (Mn0,25Fe0,5Ti0,25)O3 dimana x =0,25; 0,5; 0,75 dan 1,0. Pada tahapan sintesis material diperkenalkan teknik penggabungan antara pemaduan mekanik (mechanical alloying) dan destruksi sonikasi daya tinggi untuk menghasilkan ukuran rata-rata partikel skala nanometer. Karakterisasi material mencakup observasi struktur mikro, identifikasi fasa, sifat magnetik dan sifat absorbsi. Hasil penelitian menunjukkan bahwa material hasil pemaduan mekanik memiliki distribusi ukuran rata-rata partikel bimodal dengan waktu penghalusan relatif panjang (puluhan sampai ratusan jam) untuk memperoleh ukuran partikel rata-rata terendah. Bila sintesis melibatkan destruksi ultrasonik, distribusi ukuran partikel bersifat monomodal dengan ukuran partikel rata-rata mencapai <100 nm dalam waktu kurang dari 10 jam. Pola difraksi sinar X material memperlihatkan bahwa keseluruhan komposisi memiliki fasa tunggal dikarenakan jari-jari ion La dan Sr setara, demikian juga ion Fe dan Mn. Hasil evaluasi karakteristik serapan gelombang mikro material berdasarkan pengujian Vector Network Analyzer (VNA) memastikan bahwa keseluruhan material bersifat penyerap gelombang mikro dalam jangkau frekwensi 8 ? 15 GHz. Serapan tertinggi terjadi pada frekwensi 14,8 GHz dengan nilai Reflection Loss ~ 1 dB atau 10 % gelombang yang datang diserap oleh material. Efek ukuran partikel dengan nilai rata-rata 90 nm meningkatkan kemampuan penyerapan hingga mencapai lebih dari 60 %. Penggabungan material ini dengan senyawa magnetik hexaferrite pada jaringan komposit memperlihatkan dua serapan setara pada dua frekwensi yang berbeda (10 dan 14,8 Ghz). Pengaruh komposisi pada sistem komposit memberikan efek pelebaran terhadap kedua puncak serapan hingga terbentuk sebuah serapan dengan jangkau frekwensi yang lebar (8-15 GHz). Kesimpulan pada penelitian ini adalah sintesis material penyerap gelombang mikro senyawa (La1-xSrx) (Mn0,25Fe0,5Ti0,25)O3 dengan ukuran rata-rata kristal berskala nanometer diperoleh secara efektif melalui penggabungan teknik pemaduan mekanik dan destruksi ultrasonik. Efek ukuran partikel adalah meningkatkan daya serap material. Penggabungan material ini dengan material magnetik hexaferrite dalam sistem komposit menghasilkan suatu material penyerap gelombang mikro dalam rentang frekwensi serapan yang lebar.

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Lanthanum manganites, LMO especially those doped LaMnO3, have attracted attentions of many researchers, due to their significant potential for applications in the field of magnetic electronic functional materials. Structural modification either through doping of La with Ca, Sr, and Ba or Mn with Fe, Cu, and Ti has been reported to induce electromagnetic properties such as giant magneto resistance (GMR) or colossal magneto resistance (CMR). A partial substitution of La with Sr or Mn with Fe gives rise to new properties, in addition to the GMR or CMR, in which the substituted LMO has the ability to absorb electromagnetic waves, especially in the ultra-high frequency range (GHz). Thus, doped LaMnO3 can be considered as one of radar-absorbing materials (RAM). In this study, structural modification of LMO with designated compositions (La1-xSrx) (Mn0.25Fe0.50Ti0.25)O3 where as x = 0.25; 0.50; 0.75 and 1.0 is reported. The materials were prepared by mechanical alloying assisted with high-power sonication to produce particles with mean size in a nanometer scale. Material characterization includes the observation of microstructures, identification oh phase materials, magnetic properties and microwave absorption characteristics. It was found that mechanically alloyed of doped LMO have a bimodal particle size distribution and required a relatively long milling time (tens to hundreds of hours) to obtain the lowest average particle size. It was also found that when sintered mechanically alloyed powders were further treated under the application of a high power sonicator, a monomodal particle size distribution with mean particle size of less than 100 nm was obtained within less than 10 hrs. X-ray diffraction traces indicated that synthesized materials are single phase due to ionic radii of La and Sr ions are almost similar. This is also applicable to Fe and Mn ions. Results of microwave absorption characteristics as evaluated by Vector Network Analyzer ensure that the entire materials have capability to absorb the microwaves in the frequency range 8-15 GHz. The highest absorption was occurred at 14.8 GHz with a Reflection Loss ~ 1 dB. It means that only 10% of the incident wave energy was absorbed by the material. However, materials with the average particle size ~ 90 nm increased the absorption up to 60%. Incorporation the doped LMO with hexaferrite particles in a composite structure has resulted two similar absorption peaks at two different frequencies (10 and 14.8 GHz). Furthermore, variation in composition of composite system was widening the absorption peak into a single peak with a wide range frequency (8-15 GHz). It is concluded that mechanical alloying coupled with ultra sonication can be an alternative route for the preparation of fine and homogeneous powder materials leading to nanoparticle-based materials. Effect of fine particles in the materials is to increase the microwave absorbing properties. Where as the composite structure is to affect the frequency absorption width.

Abstrak :
Studi ini mempelajari pemanfaatan energi terbarukan menggunakan Wave Energy Converter dengan   floating absorber dalam memanfaatkan energi gelombang laut. Penelitian ini melibatkan kinematika silinder dan hidrodinamika pada badan floating absorber dengan menerapkan teori aliran potensial, serta mengevaluasi pengaruh dari variasi rasio diameter dengan draft yang berbeda. Boundary element method menggunakan simulasi Ansys Aqwa. Selanjutnya, penelitian ini menganalisis Respons Amplitude Operator (RAO) dan gaya hidrodinamika dengan variasi draft untuk menentukan desain yang optimal. Hasil analisis menunjukkan bahwa rasio lengan WEC terhadap silinder hidrolik memiliki nilai 1,23 dan variasi draft floating absorber yang optimal adalah 1,00 dengan mepertimbangkan karakteristik gelombang. ......This study studies the utilization of renewable energy using a Wave Energy Converter with a floating absorber in utilizing ocean wave energy. This study involves cylinder kinematics and hydrodynamics of the floating absorber body by applying potential flow theory, as well as evaluating the effect of variations in diameter ratio with different drafts. Boundary element method using Ansys Aqwa simulation. Furthermore, this study analyzes the Amplitude Operator Response (RAO) and hydrodynamic forces with variations in draft to determine the optimal design. The results of the analysis show that the ratio of the WEC arm to the hydraulic cylinder has a value of 1.23 and the optimal variation of the floating absorber draft is 1.00 taking into account the wave characteristics

Abstrak :
Paduan Alumunium merupakan bahan yang banyak digunakan untuk aplikasi teknik karena memiliki beberapa keunggulan sifat yaitu : ringan, tahan karat, ulet, mampu permesinan yang baik dan lain sebagainya. Alumunium seri 6063 adalah paduan alumunium dengan unsur paduan utama Mg dan Si. Paduan ini memiliki sifat mampu tempa yang paling baik di antara jenis paduan alumunium heat treatable lainnya. Dengan sifat mampu tempa yang tinggi disertai kekuatan mekanis dan ketahanan korosi yang memuaskan menyebabkan paduan tersebut banyak dipakai pada aplikasi komponen kendaraan bermotor dan pesawat terbang. Tulisan ini membahas sifat mampu tempa paduan 6063 pada pembuatan shock absorber cover cup kendaraan bermotor dengan cara tempa panas. Pembahasan menitik beratkan pada pengaruh temperatur tempa pada 360°C, 410°C dan 460°C, ratio Do/ho sebesar 0,4 ; 0,5 dan 0,6 serta volume bahan awal yaitu 115% dan 125% terhadap tingkat deformasi, nilai kekerasan dan keberhasilan produk tan pa cacat. Dari hasil pengujian didapatkan.bahwa dengan semakin tinggi rasio Do/ho, volume bahan dan temperatur proses tempa maka tingkat deformasi yang dihasilkan juga semakin besar. Sedangkan nilai kekerasan paduan bahan menurun dengan meningkatnya temperatur proses karena dimungkinkannya terjadi proses rekristalisasi.

Abstrak :
Skripsi ini membahas tentang percobaan parabolic trough collector (PTC) yang dilakukan di Universitas Indonesiadan bertujuan untuk mengetahui pengaruh pengunaan tabung kaca pada absorber. Model parabolic trough solar collector terdiri dari panel kolektor, absorber dan tabung kaca. Panel kolektor merupakan alat penangkap dan pemantul cahaya matahari, sedangkan absorber adalah pipa yang berisi fluida kerja yang akan menerima panas dari pantulan panel kolektor yang diletakkan pada titik fokusnya, dan tabung kaca adalah tabung pyrex yang diletakan bersama absorber untuk mengurangi heat loss. Desain panel kolektor dibuat 2 buah yang masing-masing memiliki lebar aperture 0.9 m, panjang 1.5 m dan jarak fokus 1 m. Desain tiang panel juga dilengkapi dengan sistem slider yang dapat mengerakan absorber pada koordinat x dan y agar dapat berubah sesuai dengan arah intensitas matahari. Penggunaan tabung kaca mengurangi heat loss absorber menjadi rata-rata 20% dibanding absorber tanpa tabung kaca yaitu sebesar 42% dan tahanan termal masing-masingnya adalah 169.87 oC/W dan 129.95 oC/W.

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This paper discusses about parabolic trough collector (PTC) experimental in University of Indonesia and the objective of the measurement is to find out the effect of using Tabung Kaca in the absorber. The designed of PTC is consisting of collector panel, absorbere, and Tabung Kaca. Collector panel is used for capturing and reflecting the solar radiation and absorber is consisting of working fluid which is absorbing the heat from the collector panel, and about Tabung Kaca is a Pyrex tube that is put in with the absorber. It protects the absorber from degradation and reduces heat losses. Collector panel there are 2 which is both of them designed with 0.9 m aperture width, 1.5 m length and 1 m focal distance. The support designs also use a slider system which is can be moved on x and y coordinate for align with the solar radiation from the collector panel. Absorber heat loss that is used Tabung Kaca is less than heat loss of the absorber that is not using glas tube, 20% and 42% respectively and for thermal resistance are 169.87 oC/W dan 129.95 oC/W either.

Abstrak :
[ABSTRAK
Deposit ampas tebu di Indonesia yang mencapai 8,5 juta ton per tahun menjadikan biomassa ini potensial untuk dikembangkan sebagai pensubstitusi bahan bakar minyak berbasis crude oil. Gelombang mikro merupakan salah satu metode pemanasan yang lebih efisien untuk mempirolisis biomassa, karena metode ini memanfaatkan prinsip konversi energi dan partikel biomassa mengalami pemanasan volumetrik. Ampas tebu dipirolisis dengan variasi daya gelombang mikro sebesar 380, 620, dan 850 Watt dan variasi bio-char dalam umpan sebanyak 0, 10, dan 20%. Karakterisasi yang dilakukan meliputi profil suhu pirolisis, yield produk pirolisis, dan kandungan senyawa di bio-oil dengan metode GC/MS. Peningkatan daya gelombang mikro akan meningkatkan laju pemanasan dan suhu pirolisis ampas tebu, walaupun efeknya tidak terlalu signifikan jika umpannya tidak ditambahkan bio-char. Penambahan bio-char sebagai absorber gelombang mikro secara signifikan meningkatkan laju pemanasan dan suhu pirolisis ampas tebu. Yield bio-oil maksimum, yaitu 42,75 dan 42,40%, diperoleh pada laju pemanasan 805oC/menit dan suhu pirolisis 515oC serta laju pemanasan 59oC/menit dan suhu pirolisis 398oC. Kondisi operasi untuk memperoleh kedua parameter laju pemanasan dan suhu pirolisis tersebut adalah daya gelombang mikro sebesar 380 Watt dengan 20% kandungan bio-char di umpan serta daya gelombang mikro sebesar 850 Watt tanpa kandungan bio-char di umpan. Bio-oil yang diperoleh dari pirolisis ampas tebu yang umpannya mengandung bio-char ternyata mengandung lebih banyak senyawa non-oksigenat dan tidak mengandung PAH. Namun, senyawa non-oksigenat tersebut juga memiliki kandungan rantai karbon panjang (C22+) yang cukup tinggi.

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ABSTRACT
Sugarcane bagasse waste in Indonesia reaching 8.5 million tons per year is potential to be developed as a substituent for petroleum-based fuel oil. Microwave is an efficient heating method for biomass pyrolysis, since this method utilizes the principle of energy conversion and biomass undergoes volumetric heating. Sugarcane bagasse was pyrolyzed at the microwave power variation of 380, 620, and 850 Watt and bio-char loading variation of 0, 10, and 20%. Characterizations were conducted on the pyrolysis temperature profile, pyrolysis products yield, and bio-oil content by GC/MS method. The microwave pyrolysis of sugarcane bagasse gave results that increasing microwave power would increase the heating rate and pyrolysis temperature, however this phenomenon was insignificant if the feed contained no bio-char. The addition of bio-char as microwave absorber in the feed significantly increased the heating rate and temperature pyrolysis. The highest bio-oil yields, i.e. 42.75 and 42.40%, were obtained at the heating rate of 805oC/min and pyrolysis temperature of 515oC and heating rate of 59oC/min and pyrolysis temperature of 398oC. Those pyrolysis heating rates and temperatures were achieved at the microwave power of 380 Watt with bio-char loading of 20% and the microwave power of 850 Watt with no bio-char loading. Bio-oil derived from the microwave pyrolysis of sugarcane bagasse which had no bio-char loading in fact contained more non-oxygenated compounds and less PAHs. However, those non-oxygenated compounds have a quite high content of long carbon chains (C22+).;Sugarcane bagasse waste in Indonesia reaching 8.5 million tons per year is potential to be developed as a substituent for petroleum-based fuel oil. Microwave is an efficient heating method for biomass pyrolysis, since this method utilizes the principle of energy conversion and biomass undergoes volumetric heating. Sugarcane bagasse was pyrolyzed at the microwave power variation of 380, 620, and 850 Watt and bio-char loading variation of 0, 10, and 20%. Characterizations were conducted on the pyrolysis temperature profile, pyrolysis products yield, and bio-oil content by GC/MS method. The microwave pyrolysis of sugarcane bagasse gave results that increasing microwave power would increase the heating rate and pyrolysis temperature, however this phenomenon was insignificant if the feed contained no bio-char. The addition of bio-char as microwave absorber in the feed significantly increased the heating rate and temperature pyrolysis. The highest bio-oil yields, i.e. 42.75 and 42.40%, were obtained at the heating rate of 805oC/min and pyrolysis temperature of 515oC and heating rate of 59oC/min and pyrolysis temperature of 398oC. Those pyrolysis heating rates and temperatures were achieved at the microwave power of 380 Watt with bio-char loading of 20% and the microwave power of 850 Watt with no bio-char loading. Bio-oil derived from the microwave pyrolysis of sugarcane bagasse which had no bio-char loading in fact contained more non-oxygenated compounds and less PAHs. However, those non-oxygenated compounds have a quite high content of long carbon chains (C22+)., Sugarcane bagasse waste in Indonesia reaching 8.5 million tons per year is potential to be developed as a substituent for petroleum-based fuel oil. Microwave is an efficient heating method for biomass pyrolysis, since this method utilizes the principle of energy conversion and biomass undergoes volumetric heating. Sugarcane bagasse was pyrolyzed at the microwave power variation of 380, 620, and 850 Watt and bio-char loading variation of 0, 10, and 20%. Characterizations were conducted on the pyrolysis temperature profile, pyrolysis products yield, and bio-oil content by GC/MS method. The microwave pyrolysis of sugarcane bagasse gave results that increasing microwave power would increase the heating rate and pyrolysis temperature, however this phenomenon was insignificant if the feed contained no bio-char. The addition of bio-char as microwave absorber in the feed significantly increased the heating rate and temperature pyrolysis. The highest bio-oil yields, i.e. 42.75 and 42.40%, were obtained at the heating rate of 805oC/min and pyrolysis temperature of 515oC and heating rate of 59oC/min and pyrolysis temperature of 398oC. Those pyrolysis heating rates and temperatures were achieved at the microwave power of 380 Watt with bio-char loading of 20% and the microwave power of 850 Watt with no bio-char loading. Bio-oil derived from the microwave pyrolysis of sugarcane bagasse which had no bio-char loading in fact contained more non-oxygenated compounds and less PAHs. However, those non-oxygenated compounds have a quite high content of long carbon chains (C22+).]

Abstrak :
[ABSTRAK
Telah dilakukan penelitian tentang pengaruh diameter perforasi terhadap koefisien absorpsi bunyi pada material gipsum secara eksperimen dengan menggunakan metode pengukuran yang tercantum dalam ISO 354-1985. Sampel divariasikan terhadap kondisi tanpa perforasi dan terhadap diameter perforasi yaitu 0,8 mm, 1,2 mm, 2 mm, 4 mm, 6 mm, 8 mm, 10 mm dan 12 mm. Ada dua konfigurasi sampel yang diteliti, yaitu sampel lapis tunggal (Sampel T) dan sampel sandwich (Sampel S). Hasil penelitian menunjukkan adanya peningkatan koefisien absorpsi bunyi hingga 27,97% seiring dengan penambahan diameter perforasi terutama di frekuensi 125 Hz, 250 Hz, dan 500 Hz. Kenaikan koefisien absorpsi bunyi juga terjadi pada saat diberikan sisipan rockwool di antara dua panel gipsum. Kedua konfigurasi sampel dengan diameter perforasi 12 mm bisa digunakan sebagai pilihan bahan penyerap bunyi untuk pengendalian bunyi di frekuensi 125 Hz, 250 Hz, dan 500 Hz.

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ABSTRACT Investigation on the influence of the perforation diameter to the sound absorption coefficient in the gypsum material has been conducted experimentally by using measurement methods in ISO 354-1985. The samples were varied on the condition perforation. Perforation diameter about none, 0.8 mm, 1.2 mm, 2 mm, 4 mm, 6 mm, 8 mm, 10 mm and 12 mm. There were two configurations of samples, namely a single-layer samples (Sample T) and sandwich samples (Sample S). The results show the increasing in sound absorption coefficients up to 27,97% along with the addition of diameter perforations, especially in the frequency of 125 Hz, 250 Hz, and 500 Hz. The increasing in sound absorption coefficient also occur during insertion of rockwool between two gypsum panels. Both sample configuration with 12 mm diameter perforation can be used as a sound absorbent material to control sound at frequencies of 125 Hz, 250 Hz, and 500 Hz., Investigation on the influence of the perforation diameter to the sound absorption coefficient in the gypsum material has been conducted experimentally by using measurement methods in ISO 354-1985. The samples were varied on the condition perforation. Perforation diameter about none, 0.8 mm, 1.2 mm, 2 mm, 4 mm, 6 mm, 8 mm, 10 mm and 12 mm. There were two configurations of samples, namely a single-layer samples (Sample T) and sandwich samples (Sample S). The results show the increasing in sound absorption coefficients up to 27,97% along with the addition of diameter perforations, especially in the frequency of 125 Hz, 250 Hz, and 500 Hz. The increasing in sound absorption coefficient also occur during insertion of rockwool between two gypsum panels. Both sample configuration with 12 mm diameter perforation can be used as a sound absorbent material to control sound at frequencies of 125 Hz, 250 Hz, and 500 Hz.]