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"ABSTRAKSebagai salah satu teknologi perpindahan panas dua fasa terbaru, pulsating heat pipe (PHP) mempunyai daya tarik tersendiri dalam perkembangan teknologi heat pipe. Pemanfaatan PHP sangat beragam mulai dari aplikasi pendingin elektronika, sampai dengan heat recovery heat exchanger. Pada penelitian ini sebuah PHP didesain pada penggunaan ductwork dengan ukuran 300 x 470 mm. PHP dibuat dengan menggunakan pipa kapiler tembaga dengan diameter dalam 1,7 mm dan diameter luar 3 mm dan panjang total 13,5 m. Panjang bagian evaporator, adiabatik dan kondenser berturut-turut , 260 mm, 240 mm, dan 260 mm. Ethanol dipergunakan sebagai fluida kerja dengan filling ratio sebesar 60%. Hasil penelitian didapatkan bahwa nilai resistansi termal terendah adalah 0.36 K/W pada input kalor 76,1 W. Resistansi PHP cenderung stabil saat sudut inklinasi dari PHP divariasikan. Dengan hasil pengujian kinerja didapatkkan, bahwa PHP sangat mungkin dimanfaatkan heat recovery pada pemanfaatan dengan temperatur 50oC-70oC.

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ABSTRACTAs one of the latest technologies of heat transfer in two phases, pulsating heat pipe (PHP) has a special attraction in the development of heat pipe technology. Utilization of PHP is very diverse ranging from electronics cooling applications, up to the heat recovery heat exchanger. In this study, the use of a PHP was designed in ductwork with a size of 300 x 470 mm. PHP created using copper capillary tube with an inner diameter of 1.7 mm and an outer diameter of 3 mm and a total length of 13.5 m. The length of the evaporator, adiabatic and condenser, respectively, 260 mm, 240 mm and 260 mm. Ethanol is used as a working fluid with filling ratio of 60%. The results showed that the lowest thermal resistance value is 0.36 K / W at a heat input 76.1 W. PHP tend to be stable when the angle of inclination of PHP varied. With performance test results obtained, that PHP is very possibly being heat recovery in the utilization temperature of 50 oC-70 oC."

"Heat pipe sebagai alat penukar panas berukuran kecil memiliki banyak kegunaan di era modern ini. Mulai digunakan oleh NASA untuk sistem pendingin aplikasi luar angkasa karena kemampuan fluks panasnya yang tinggi, dan sekarang heat pipe dapat ditemukan sebagai sistem pendingin pada laptop pada umumnya. Karena dikenal luas sebagai sistem yang efisien, telah banyak penelitian tentang ketahanan termal pipa panas apakah kinerjanya tergantung pada beberapa variabel, dalam hal ini kinerjanya sangat tergantung pada fluida kerja, sudut kemiringan dan masukan panas ke pipa panas. Studi ini berfokus pada merancang pengukur untuk pipa panas bentuk-L untuk tujuan eksperimental untuk memahami bagaimana kinerja termal pipa panas dibandingkan dengan pipa panas lainnya tidak ada fluida kerja di dalamnya yang menjadikannya hanya pipa tembaga biasa, tambahkan juga sudut kemiringan yang dapat disesuaikan untuk menemukan posisi kerja yang paling efisien untuk pipa panas.

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Heat pipe as a small heat exchanger has many uses in this modern era. Started to be used by NASA for spaceflight application cooling systems due to its high heat flux capability, and now the heat pipe can be found as a cooling system on laptops in general. As widely recognized as an efficient system, there have been many studies on the thermal resistance of heat pipes whether its performance depends on several variables, in this case its performance is highly dependent in the working fluid, the angle of inclination and the heat input to the heat pipe. This study focuses on designing gauges for L-shape heat pipes for experimental purposes to understand how the thermal performance of the heat pipe compares to other heat pipes no working fluid in it which makes that one just a regular copper pipe, add it too adjustable tilt angle to find the most efficient working position for the heat pipe.

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"Perkembangan teknologi yang sangat pesat pada zaman ini menuntut ilmu fabrikasi mikro untuk berkembang lebih pesat lagi. Dewasa ini, sedang dikembangkan teknik mikrofabrikasi menggunakan mikroorganisme (biomachining). Bakteri yang digunakan adalah bakteri jenis Achidithiobacilus ferooxidans. Penelitian ini melanjutkan penelitian sebelumnya dengan menambahkan parameter inklinasi dan aliran udara (aerasi) pada prosesnya. Sudut yang digunakan adalah variasi dari 200, 300, dan 400. Benda kerja berupa material nikel diberi sebuah pola melalui proses photolithography dan dimasukkan ke dalam cairan medium kultur dalam posisi bersudut yang sudah terisi bakteri, dan dijaga temperatur ruangannya menggunakan inkubator serta dialirkan udara. Percobaan dilakukan selama 24 jam. Pengolahan data dilakukan menggunakan SURFCOM dan foto SEM. Hasil yang didapat bahwa tingkat kekasaran (Ra) sangat bergantung kepada kondisi bakteri.

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The rapid development of technology in this day and age require microfabrication knowledge to grow more rapidly again. Today, the technique is being developed by using microorganisms (biomachining). The bacteria used is Achidithiobacilus ferooxidans types of bacteria. This study continues the previous research by adding the inclination and airflow parameters (aeration) in the process. The angle used is a variation of the 200, 300, and 400. Workpiece material in the form of nickel given a pattern through a photolithography process and put into liquid culture medium in the angular position of the bacteria that are already filled, and kept the room temperature using an incubator and air flows. The experiments were conducted for 24 hours. Data processing was performed using Surfcom and SEM. The results that the degree of roughness (Ra) is very dependent on the condition of the bacteria."

"Patient with severe condition which single conventional orthodontic treatment cannot be carried out, it must be considered to undergo combination treatment between orthodontic and orthognathic surgery, so that patient's complaint about aesthetic, mastication and speech function can receive better correction. The aim of performing the orthodontic treatment before orthognathic surgery is to place teeth position ideally to the bone base before correcting the abnormality of its sceletal bone. After the orthognathic surgery there is still the orthodontic treatment to be done which has the aim to achieve good teeth occlusion, inclination and angulation. if possible comparable to the conditions described by Andrew in Six Keys of Normal Occlusion."

"A factor to pay attention to in orthodontic treatment is the inclination of upper and lower incisives. The inclination could be evaluated from interincisal angle and angle of upper incisive (UI) with cranium base (SN). This research is to evaluate those angles after the retraction of upper and lower incisives on malocclusion class I with bimaxillary prostrusion. In total, 34 samples were treated using edgewise system. The results show that mean for UI ? LI is 138.06°±1.47°, and for UI ? SN 95.97°±1.27°."

"ABSTRACTTo overcome the disadvantages of open pond and cement tube as an outdoor algal cultured system, a simple inclined algal culture system was developed. the system composed of an 18.9 L polyethylene terephthalate (PET)bottle placed on a degree adjustable stand using an air pump to generate water mixing and circulation. The system was tested by culturing 45 mL Oscillatoria sp. in 13 L Blue-Green-11 (BG-11)medium supplemented with 3 g L-1 NaNO3 in plastic bottle, which was placed on different angles of inclination, viz. 45°, 60° and 90°. The system was operated outdoor under natural daylight and temperature. After 11 days, 11.5 L culture medium was poured out and 11.5 L fresh medium was refilled. Algal cell was precipitated to measure algal yield. Then, cell harvesting was done every 7 days for 6 batches. This system could culture algae continuously for 5 batches. The highest productivity was 32.23 gram wet (gw) ×m-2×d-1, which was recorded from a second and fifth round of 45° angular system and also from third round of 60° angular system. The result showed that this simple inclined algal culture system can be done continuously for one and a half month with high productivity by 45° inclination, which was proved as a good mixing and circulation. Showing advantages over open-pond, this system was moveable and could reduce possibility of contamination."

"Entrepreneurship has been the fundamental topics of discussion among the politicians, economists,and academics. Business creation is especially critical in developing countries to stimulateeconomic growth. The present study attempts to examine entrepreneurial inclination among studentswho are a potential source of entrepreneurs. The findings of the present research study indicatethat majority of our business students are not entrepreneurial-inclined. They do not seem topossess strong entrepreneurial characteristics and entrepreneurial skills, and they are not keen instarting a new business. The roles of higher institutes of education and the government in promotingentrepreneurship are discussed."

"Biomachining merupakan salah satu proses alternatif dalam fabrikasi mikro. Beberapa keunggulan yang dimiliki dalam proses biomachining adalah ramah lingkungan, tidak terjadi thermal damage pada permukaan benda kerja, dan efisien energi. Dalam penelitian biomachining multi-axis sebelumnya inklinator sudah dikembangkan dengan menggunakan konsep sendi peluru pada fixture sehingga memiliki dua sumbu rotasi dan sudut inklinasi dapat dilakukan ke segala arah. Telah dilakukan percobaan biomachining pada permukaan benda kerja tembaga dimana tiap - tiap posisi diberi sudut inklinasi 20° dan 40°. Percobaan dilakukan dalam waktu 6 jam untuk tiap - tiap posisi inklinasi. Pada penelitian kali ini proses yang sama dilakukan pada benda kerja nikel. Percobaan dilakukan dengan temperatur ruangan 23 - 25°C. Tujuan dilakukan penelitian ini adalah untuk melihat karakterisasi dan bentuk profil permukaan dari benda kerja nikel dengan perlakuan inklinasi sudut yang berbeda.Selain itu penelitian ini juga bertujuan untuk melihat perbandingan surface roughness dan bentuk profil permukaan dari benda kerja nikel dan tembaga yang telah melalui proses biomachining dengan sudut inklinasi yang sama. Berdasarkan hasil pengukuran didapatkan nilai material removal rate (MRR) dari benda kerja nikel dengan perlakuan inklinasi 20° dan 40° sebesar 0,102 mm3/jam dan 0,129 mm3/jam. Tingkat kekasaran yang paling rendah adalah nikel 40o dengan nilai rata-rata Ra 1,76 ± 0.31 µm dan diikuti oleh nikel 20o dengan nilai rata-rata Ra 2,41± 0.39 µm. Nilai rata-rata tingkat kekasaran benda kerja tembaga yang didapat dari penelitian sebelumnya lebih besar dibandingkan dengan benda kerja nikel. Dari hasil perbandingan dengan penelitian sebelumnya menunjukkan bahwa benda kerja tembaga memiliki kedalaman permukaan lebih besar dibanding dengan benda kerja nikel.

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Biomachining is one of the alternatives in the micro fabrication process. The advantages of biomachining is environmentally friendly, no effect of thermal damage on the workpiece surface, and energy efficient. Previously, the study of multi-axis biomachining inklinator have been developed using the concept of joint bullets on his desk so that it has two axes of rotation and the angle of inclination which can be done in any direction. Biomachining experiments have been conducted on the surface of the copper workpiece where each position given the angles of inclination of 20° and 40°. Experiments performed within 6 hours for each position of inclination. In the present study, the same process carried out on nickel workpiece. The experiments were performed with room temperature 23-25°C.

The purpose of this study is to look at characterization and profile shape of nickel with different inclination angles . In addition , this study aimed to compare the surface roughness and the shape of the workpiece surface profile nickel and copper that has been through the process biomachining with the same angle of inclination . Based on the results, the value of material removal rate ( MRR ) from nickel workpiece with inclination angle 20° and 40° are 0.102 mm3/hour and 0.129 mm3/hour . The lowest level of roughness (Ra) is nickel 40o with an average value 1.76 ± 0.31 µm and followed by nickel 20o with an average value 2.41 ± 0.39 µm. Average roughness of the copper samples were obtained from previous studies is greater than the nickel workpiece. From the comparison with previous research showing that copper workpiece surface has a depth greater than the nickel workpiece."

"Oil and gas exploration is increasingly moving to deepwater locations to meet the increasing energy demands. In this environment, floating structures with suction pile foundations are commonly used because their the cost-effectiveness. Some studies have been conducted to examine the behavior of suction piles in clays, but the clay conditions considered are typically normally consolidated and lightly overconsolidated. In this paper, the behavior of suction piles in underconsolidated clays and underconsolidated-normally consolidated clays adopted from actual deepwater soil conditions. The evaluation was performed using geotechnical 3D finite element software Plaxis. Suction piles with two different aspect ratios (L/D = 2 and 6) were considered, and the focus was on the effect of load angles (0? to 90?) and the effects of padeye position (0.5 L to 0.9 L). For short piles, the load angles had a relatively insignificant effect on the overall ultimate resistance, while for long piles, the angles affected the overall resistance considerably with a decrease in resistance up to about 50 percent. This different behavior could be explained from the observed pile deformation patterns. The padeye positions affected the pile resistances significantly as well with a decrease in resistance up to about 30 percent. Nevertheless, it can be concluded that the overall behavior of suction piles in a combined clay conditions is practically similar to that of piles in normally consolidated and overconsolidated clays."

"Teknologi fabrikasi berskala mikro saat ini sangat bervariasi dan sedang terus dikembangkan. Salah satunya menggunakan mikroorganisme (biomachining). Terdapat jenis bakteri yang dapat melakukan pemakanan pada logam sebagai sumber energinya, salah satunya adalah Acidithiobacillus ferooxidans. Penelitian sebelumnya telah membuktikan kemampuan Acidithiobacillus ferooxidans dalam karakterisasi proses pemakanan dan hasil akhir material benda kerja. Namun, perkembangan teknologi biomachining belum selesai. Dalam penelitian ini, proses biomachining diberikan tambahan parameter variasi sudut inklinasi terhadap benda kerja material tembaga untuk mengetahui pengaruhnya terhadap profil permukaan dan tingkat kekasaran yang dihasilkan. Benda kerja diberi sebuah pola dengan metode photolithography dan dimasukkan dalam cairan medium kultur bakteri, dengan diberikan sudut inklinasi sebesar 20° dan 30° dengan alat bantu inklinator. Data hasil pengukuran bentuk profil dan tingkat kekasaran permukaan oleh mesin SURFCOM akan dibandingkan dengan hasil biomachining yang diberi sudut inklinasi berbeda yaitu 40° dari hasil penelitian sebelumnya. Hasil penelitian ini yaitu pemakanan sampel 20° memiliki kedalaman yang lebih kecil dibandingkan dengan sampel 30°, namun center island yang dihasilkan cenderung lebih panjang. Tren untuk nilai tingkat kekasaran (Ra) yaitu sampel 20°>30°>40°. Perbedaan karakteristik pemakanan ini diharapkan dapat mendukung pengembangan proses biomachining multi-axis kedepannya.

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Nowadays, micro fabrication technology is very varied and being continuosly developed. One of them uses microorganisms culture (biomachining). There is a type of bacteria which can do metal removal as a source of energy, one of which is Acidithiobacillus ferooxidans. The previous research has proven the ability of Acidithiobacillus ferooxidans in the characterization and result of workpiece material removal process. However, biomachining technology has not done yet.

In this research, biomachining process is added by angle of inclination parameter to know the effect on copper surface profile and roughness. Workpieces are given a pattern by photolithography method and put in the bacterial culture medium, which is added inclination angle of 20° and 30° on inclinator. Profile shape and the surface roughness measurement data which are taken by SURFCOM machine will be compared with the inclination angle of 40° measurement data from previous research.

The results of this research that removal depth of sample 20° is smaller than the sample 30°, but the center island tend to be longer. Result for the value of roughness average (Ra) is the sample 20° > 30° > 40°. This characteristic differences are expected can support the development of multi-axis biomachining."