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"Since the analytical result of the frictional resistance of a rotating disk has been reported by Kérrnén (l92l), many studies have been done experimentally or analytically on the characteristics of the three-dimensional boundary layer at the disk surface. Frictional resistance of an impeller of a turbo-machinery is calculated by applying that of a rotating disk flow. To improve the performance of a turbo-machinery, attempt was done by applying a drag reduction to the tlow. Thus, the drag reduction phenomena have been studied on a rotating disk in drag reducing additives (Watanabe, K., l978) or a disk with hydrophobic wall (Watanabe, K., and Ogata, S., 1997). However, the drag reducing method reported in the past remains a problem- that the degradation or the durability becomes the iitilure forthe practical application.In this study, the experiments were carried out the measurement on the frictional moment, velocity fluctuation and protlle and flow visualization of an enclosed rotating disk in order to obtain a new passive drag reduction wall that is excellent in the durability and is practically applicable. An approximation theoretical analysis base on the momentum integral equation -also has been accounted for axial clearance ratio effects for the case of separate boundary layers onthe disk. This theory has been checked against experimental results.lt is well known that fluid in the boundary layer ata rotating disk surface flow with keeping a flow angle (Gregory, N. et al., 1955); By considering this flow pattern, was made a disk with a new passive drag reduction wall by an etching method. The disk with many fine spiral grooves is made of aluminum. The number of the spiral grooves varying at 120, 144, 150, 155 and 160 with 0.l and 0.2 mm depth each. The clearance between the disk and the housing wall was varied at l, 3, IO, 20 and 30 mm thick. Experimental result showed that for the close clearance l mm the moment coefficient in the turbulent region in the Reynolds number range of 4x 10" S Re S 6x 10? for the disks of l50 and |55 grooves with 0.1 and 0.2 mm depth, the drag reduction ratio was obtained about 15 %. While for the large clearance 20 mm for the disk of 144,150 and 155 grooves with 0.1mm depth in the Reynolds number range of 3.3 x to? < Re <4.0x105 the drag reduction ratio was obtained about 11 % .The experimental results of the velocity fluctuation, velocity profile and the flow visualization also add other evidences: the fine spiral grooves control the secondary flow of the boundary layer and have the effect which delays the generation oft he local turbulence in the transition range, and reduce wall skin friction in the turbulent region."

"Peningkatan jumlah emisi karbon menyebabkan pemerintah Indonesia memasang target bebas gas rumah kaca pada tahun 2060 dan membuat kebijakan penggunaan kendaraan listrik untuk mendukung tercapainya target tersebut. Pada kendaraan listrik, terdapat motor listrik yang berfungsi untuk mengonversikan energi listrik menjadi energi mekanik agar dapat bergerak, namun dalam proses konversi ini terjadi kerugian-kerugian yang menyebabkan temperatur motor meningkat. Temperatur motor yang terus meningkat hingga lebih dari 60℃ dapat menyebabkan penurunan performa dan kerusakan pada motor listrik, sehingga perlu adanya sistem pendinginan yang dapat mempertahankan temperatur motor listrik. Penelitian ini akan meneliti dan menguji Rotating Heat Pipe (RHP) sebagai sistem pendinginan pasif untuk motor listrik. Tujuan dari penelitian ini adalah untuk mengembangkan metode pengukuran untuk pengujian RHP dan mengetahui kinerja dari RHP. Penelitian ini menggunakan RHP dengan termokopel yang sudah terpasang di permukaannya. Penelitian ini juga menggunakan slip ringyang akan diuji kemampuannya ketika digunakan sebagai perantara antara modul akuisisi data dan sensor termokopel. Dari penelitian, diketahui bahwa slip ring dapat digunakan untuk menguji RHP karena kemampuannya untuk mengukur temperatur dalam kondisi berputar. Selain itu, penggunaan RHP juga mampu menurunkan resistansi termal sebesar 30-66% dibandingkan pipa kalor diam. ......The increase in carbon emissions has prompted the Indonesian government to set a target of carbon neutrality by 2060 and implement policies promoting the use of electric vehicles to support the achievement of this target. Electric vehicles are equipped with electric motors that convert electrical energy into mechanical energy to propel the vehicle. During this energy conversion process, the motor experiences an increase in temperature due to various losses that cause the motor temperature rise. If the heat continues to increase and the motor temperature exceeds 60°C, it will reduce the performance or even lead to damage. Therefore, there is a need for a cooling system that can maintain the electric motor's temperature within its working range. This study aims to investigate and test the Rotating Heat Pipe (RHP) as a passive cooling system for electric motors. The objectives of this research are to develop measurement methods for RHP testing and evaluate the performance of the RHP. The study employs an RHP with installed thermocouples on its surface. Additionally, a slip ring is utilized to test its capability as a connector of the data acquisition module and the thermocouple sensor. The research confirms that the slip ring can be used to test the RHP due to its ability to measure temperature under rotating conditions. Furthermore, the use of RHP can reduces thermal resistance by 30-66% compared to stationary heat pipes."

"Rumah Sakit merupakan institusi yang berpotensi menimbulkan pencemaran lingkungan, terutama dari limbah cair yang dihasilkan karena kegiatan sehari-hari. Penanganan limbah cair dapat dilakukan dengan cara fisik, kimia dan biologis atau gabungan dari ketiganya. Salah satu pengolahan limbah cair secara biologis adalah menggunakan Rotating Biological Contactors (RBC). Metode ini memanfaatkan kemampuan mikrobia daiam merombak bahan cemaran sampai menjadi senyawa yang stabil.Penelitian ini dilatar belakangi masih tingginya parameter limbah cair Rumah Sakit Umum Daerah Raden Mattaher Jambi, yang angkanya masih diatas Baku Mutu Limbah Cair Rumah Sakit sehingga dimungkinkan dapat menimbulkan dampak negatif terhadap lingkungan sekitarnya.Penelitian ini bertujuan untuk mengetahui penurunan kandungan BOD, COD, P04, TSS, NH3 dan MPN Coli limbah cair Rumah Sakit Umum Daerah Raden Mattaher Jambi setelah diolah dengan RBC sebagai unit pengolahan limbah cair secara biologis, sehingga didapatkan limbah cair yang kualitasnya lebih baik. Disamping itu juga untuk mengetahui penurunan terbaik parameter limbah cair tersebut berdasarkan waktu tinggal dan waktu putar (3 rpm).Jenis penelitian adalah Eksperimen dengan rancangan One Group Pretest-Postest, dimana sebelum penelitian dilaksanakan terlebih dahulu dilakukan aklimasi.Hasil penelitian menunjukan bahwa limbah cair Rumah Sakit Umum Daerah Raden Mattaher Jambi setelah diolah dengan RBC, terdapat penurunan parameter berdasarkan variasi waktu tinggal dan waktu putar (3 rpm). Hasil penelitian dilapangan ditemukan penurunan parameter BOD, COD, P04, pada waktu tinggal 60 menit dengan putaran 3 rpm, merupakan penurunan yang optimum. Artinya dalam waktu 60 menit diolah dengan RBC maka parameter BOD, COD, dan PO4 terjadi penurunan yang memenuhi Standar Baku Mutu Limbah Cair Rumah Sakit yaitu BOD = 14,25 mg/L, COD = 22,25 mg/L, dan P04 = 0,72 mg/L. Sedangkan waktu tinggal 120 menit, 180 menit, 240 menit dan 300 menit terjadi penurunan parameter BOD, COD dan P04 tetapi penurunannya sangat kecil.Parameter TSS dan NH3 terjadi penurunan pada semua waktu tinggal tetapi, penurunan yang terjadi hasilnya masih diatas Standar Baku Mutu Limbah Cair Rumah Sakit yaitu TSS antara 1,64 mg/L sampai dengan 174,75 mg/L dan NH3 antara 1,31 mg/L sampai dengan 1,52 mg/L.Sedangkan parameter bakteriologis terbukti terjadi penurunan MPN Coli yang optimum oleh karena dari semua waktu tinggal yang digunakan hasilnya menunjukan penurunan MPN Coli dapat memenuhi Standar Baku Mutu Limbah Cair Rumah Sakit yaitu antara 2090 sampai 5260.Dari hasil tersebut dapat disimpulkan bahwa :1. RBC dapat menurunkan kandungan parameter limbah cair Rumah Sakit.2. Penurunan kandungan parameter yang optimum berdasarkan waktu tinggal adalah BOD, COD, PO4 dan MPN Coli.3. Penurunan kandungan parameter TSS dan NH3 terjadi berdasarkan waktu tinggal tetapi hasil penurunan tersebut masih diatas Standar Baku Mutu Limbah Cair Rumah Sakit.Untuk itu disarankan kepada manajemen RSUD Raden Mattaher Jambi, dapat menggunakan metode RBC ini yang dimodifikasi sesuai volume limbah cair yang dihasilkan. Disamping itu perlu mengfungsikan kembali aerator yang ada pads IPAL. Sedangkan kepada peneliti lain yang berminat untuk penelitian lanjutan agar metode ini lebih sempurna.

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Processing of the Liquid Garbage at the General Hospital of Raden Mattaher, Jambi by Rotating Biological Contactors (RBC) (Case Study at the General Hospital of Raden Mattaher, Jambi)Hospital is an institution that having potency in rising of environment contamination, especially to liquid garbage that resulted from the daily activities. The management of liquid garbage can be conducted by physical, chemical and biological ways or combination of them. One of liquid garbage biologically processing, it was using Rotating Biological Contactor (RBC). This method is utilizing the capability of microbial in changing the pollution material up to stable compound.The background of this study, it is still high the content parameter of liquid garbage at the General Hospital of Raden Mattaher, Jambi, which is the rate still over than the Basic Quality of liquid garbage of Hospital, so it is possibility raising the negative impact to the surroundings environmental.The objective of this study is to determine the reducing of BOD, COD, P04, TSS, NH3 contents, and MPN Collie liquid garbage at General Hospital, Raden Mattaher, Jambi after processing by RBC as processor unit of liquid garbage biologically, so it obtained liquid garbage in good quality. Besides that, it is to determine the best reducing on content parameter of liquid garbage based on stay time and cycle time (3 rpm).This study is experimental with the design one group pretest posttest, where before conducting the study, it done acclamation in the previous.The result of this study shows that the liquid garbage at General Hospital of Raden Mattaher, Jambi after processing with RBC, there was reducing parameter based on variation of staying time and cycle time (3 rpm) in differently. The result at the field found that the reducing parameter of BOD, COD, P04, on the stay time is 60 minutes with 3 rpm, it is optimum reducing. It means that in 60 minutes processing by RBC, so the parameter of BOD, COD, and P04, shows reducing that meet with the Standard of Basic Quality of liquid garbage at the Hospital that is BOD = 14.25 mg/L, COD = 22.25 mg/L, and PO4 = 0.72 mg/L. While the stay time 120 minutes, 180 minutes, 240 minutes and 300 minutes shows reducing parameter of BOD, COD, and P04, but the reducing is very small.The parameter TSS and NH3 shows the reducing on all stay time, however the reducing the showed still above the Standard of Basic Quality of liquid garbage at the Hospital that is TSS between 1.64 mg/L - 174.75 mg/L, and NH3 between 1.31 mg/L - 1.522 mg/L.While the parameter of bacteriologic proves occur reducing MPN Collie that optimum, because out of all the stay time that used result shows reducing MPN Collie meet with the Standard of Basic Quality of liquid garbage at the Hospital those are between 2090 to 5260.Based on the result above, it can be concluded as the followings:1. The RBC could reduce the parameter contents of liquid garbage of hospital.2. The reducing of optimum parameter content based on the stay time is BOD, COD, P04, and MPN Collie.3. The reducing parameter content of TSS and NH3 occur based on stay time, but the result of reducing is still above the Standard of Basic Quality of liquid garbage at the hospital.It is recommended to the management of the General Hospital of Raden Matther Jambi to use the RBC method that modified according to the volume of liquid garbage that resulted. Besides that, it should reutilize aerator that available on IPAL. While the other researchers that interested to do further study to make this method more perfectly."

"Rotasi bintang tentunya akan memberikan efek pada sifat-sifat bintang yang digambarkan oleh persamaan keseimbangan hidrostatik [1]. Gaya sentrifugal akan mendistorsi bentuk bintang dan memodifikasi struktur keseimbangan bintang sedangkan gaya coriolis akan mempengaruhi osilasi bintang [2]. Pemilihan teori gravitasi termodifikasi seperti Eddington inspired Born Infeld (EiBI) dan Beyond Horndeski (BH) juga akan mempengaruhi geometri dari bintang. Pada studi ini pemilihan teori gravitasi termodifikasi akan mengubah persamaan Poisson yang mendeskripsikan bintang. Sehingga dapat dilihat perubahan pada persamaan keseimbangan hidrostatik dari bintang [3]. Persamaan Lane Emden telah banyak digunakan untuk menggambarkan distribusi massa pada sebuah bintang dengan atau tanpa rotasi [4]. Pada studi ini, kami ingin menghitung persamaan Lane-Emden termodifikasi secara analitik dan numerik pada bintang yang berotasi dengan teori gravitasi termodifikasi EiBI dan BH.

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The star rotation will undoubtedly affect the star's characteristics described by the hydrostatic equilibrium equation [1]. The centrifugal force distorts the star's shape and modifies its equilibrium structure [2]. The choice of the gravity model such as Eddington inspired Born Infeld theory of gravity will also affect the geometry properties of stars. In this case, it will change the corresponding Poisson's equations. So it is desirable to see the modification of hydrostatic equation of states of the non-relativistic rotating stellar object within Eddington inspired Born Infeld and Beyond Horndeski theories of gravity [3] . Lane-Emden equations have been used to describe the mass-density distribution in the stars of polytropic equation state of the stars with and without rotation [4]. In this paper, we would like to derive analytically and numerically the modified Lame-Emden equations for rotating non-relativistic stars within both theories and discuss the corresponding numerical results."

"Di alam semesta terdapat benda kompak yang merupakan sisa peluruhan dari evolusi bintang selama ratusan tahun. Salah satu benda kompak yang menarik untuk diteliti adalah bintang neutron. Karakteristik bintang neutron adalah ukurannya yang kecil dengan kerapatannya yang besar. Struktur bintang neutron didefinisikan dalam persamaan medan Einstein pada keadaan equilibrium yang disebut dengan persamaan Tolman,Oppenheimer dan Volkoff (TOV). Dalam keadaan isotropik, bintang neutron diasumsikan bersifat statis, bulat dan tidak berotasi. Penelitian mengenai bintang neutron dalam keadaan statik dan slow rotating sudah banyak dipelajari, namun penambahan efek konstanta kosmologi menjadi menarik untuk diteliti bagaimana pengaruhnya terhadap sifat bintang neutron. Pada keadaan slow rotating persamaan keadaan Einstein memiliki suku tambahan yang mengandung ω(r). Penambahan konstanta kosmologi (Λ) pada persamaan keadaan akan otomatis mengubah sifat bintang neutron. Perubahan terhadap massa-radius, momen inersia dan crust menjadi fokus yang dipelajari dalam penelitian ini.......In the universe there are compact objects that are remnants of decay from the evolution of stars over hundreds of years. One compact object that is interesting to study is the neutron star. The characteristic of a neutron star is its small size and large density. The structure of a neutron star is defined in the Einstein field equation in a equilibrium state called the Tolman, Oppenheimer, and Volkoff (TOV) equation. In isotropic conditions, the neutron star is assumed to be static, spherical and not rotating. neutron star in static and slow rotating states have been widely studied, but the addition of the effects of cosmological constants is interesting to inverstigate how they affect the properties of neutron stars. In the slow rotating state, the Einstein state equation has an additional term containing ω(r). The addition of cosmological constants (Λ) to the state equation will automatically change the neutron stars nature. The changes of mass radius, moment of inertia and crust are the focus of this investigation."

"ABSTRAKBioteknologi pengolahan air limbah akhir-akhir ini semakin menjadi tumpuan danharapan untuk pengendalian pencemaran (sistem sanitasi dan kelangsungan kehidupan)secara efisien, efektif dan "low cost." ini dimaksudkan untuk mengantisipasidampak yang akan ditimbulkan oleh fenomena-fenomena industrialisasi pertambahanpenduduk dan peningkatan aktivitas kehidupan, seperti :- Semakin meningkatnya kebutuhan terhadap air bersih.- Peningkatan kuantitas dan keanekaragaman air limbah (domestik maupun industri) yang dihasilkan.Disebabkan oleh berbagai kendala dan tantangan yang muncul, rekayasa biologidalam Sistem Pengolahan Air Limbah semakin menunjukan trend kearah nilaikompetitif dan komparatif dari aspek-aspek ekonomi. disain, efektifitas, efisiensi dankeamanan dari suatu sistem.RBC (Rotating Biological Contactor) merupakan salah satu "inovasi teknologi" dalambioteknologi pengolahan air limbah secara biologis, karena dalam banyak hal RBCmerupakan solusi terhadap berbagai kelemahan dan kekurangan dari sistem pengolahanlahan biologis konvensional, terutama dalam hal :- Konservasi energi dalam O & M (Hemat Energi)- Keterbatasan lahan (Hemat Lahan/Space)- Stabilitas sistem terhadap Shock Loading- Kinerja proses sistem yang sangat tinggi.Banyak faktor yang dapat mempengaruhi performansi proses sistem RBC, sepertiumumnya sistem pengolahan biologis lainnya. Untuk tujuan optimasi suatu proses,penelitian dan evaluasi dengan menggunakan Model Skala-Lab. (Bench Scale)maupun Pilot Plam adalah relatif lebih efektif dan representatif.Kerlas Kerja Seminar Penelilian ini membahas tentang Model Skala Laboratoriumdari Sistem Rotating Biological Conracror (RBC) yang digunakan dalam penelitian diLaboranorium Teknik Penyehatan & Lingkungan, Jurusan Sipil PTUI. Karena dalamdisain model ini telah dilakukan modifikasi konfigurasi media untuk optimasi bidankomak Aerasi. Modifikasi yang dimaksud adalah dengan merubah konfigurasi mediadari berbentuk cakram (disc) ke bentuk Pipa Biologis (Biopipe).Dari hasil penelitian yang telah dilakukan, diketahui bahwa Model Skala Laboratorium(Laboratory Scale Unit) Sistem RBC ini mempunyai performansi/kinerja yangsangat baik. Hal ini dapat diketahui dari tingkat penguraian/pemisahan OverallRemoval Zat Organik Carbon yang mencapai nilai (96,2 - 98,9) %. yang terjadi padareaktor RBC tersebut.Pada penelitian ini juga dapat dilihat dan diamati tentang terjadinya "Suksesi Mikroorgamlsma"dalam reaktor bertingkat (stages), seperti pada Sistcm Rotating Bio1ogical Contactor."

"In this study, the limiting maximum drag reduction asymptote for the moment coefficient of an enclosed rotating diskwith fine spiral grooves in turbulent flow region were obtained analytically. Analysis which were based on anassumption for a simple parabolic velocity distribution of turbulent pipe flow to represent relative tangential velocity,was carried out using momentum integral equations of the boundary layer. For a certain K- parameter the momentcoefficient results agree well with experimental results for maximum drag reduction in an enclosed rotating disk withfine spiral grooves and drag reduction ratio approximately was 15 %. Additionally, the experimental results for dragreduction on a rotating disk can be explained well with the analytical results."

"ABSTRAKThe main purpose of the current study is to represent numerical simulations for magneto-nanofluid slip flow and heat transfer over a permeable rotating disk in the presence of thermophoresis and Brownian motion. to carry out the experiment, the governing nonlinear partial differential equations are converted into nonlinear ordinary differential equations by using similarity analysis and the solutions are computed through the algebra software MATLAB. The obtained results are consistent with previously available studies to a particular extent. The natures of the involved interesting parameters on the temperature and concentration are drawn graphically. The present study further computes and examines the local Nusselt Number. the emerged results may be useful for environmental, industrial and engineering phenomena."

"A correlation has been proposed for mean drop diameter in a Rotating Sieved Disc Contactor (RSDC) considering drops break up, as well as drops coalescence with static holdup in the case of no mass transfer. The proposed correlation is a function of a number of stages, rotating speed in the form of Reynolds number, static hold-up and mother drop size. The effects of the last two terms have not been considered by other researchers. Therefore, the results are compared with two reported correlations to show how these two important terms influence the size of drops. Distilled water was used as a continuous phase and toluene was applied as a dispersed phase in the experiments. The absolute average relative error and standard deviation for the correlation were 14.74% and 10.08%, respectively."

"IFToMM conferences have a history of success due to the various advances achieved in the field of rotor dynamics over the past three decades. These meetings have since become a leading global event, bringing together specialists from industry and academia to promote the exchange of knowledge, ideas, and information on the latest developments in the dynamics of rotating machinery. The scope of the conference is broad, including e.g. active components and vibration control, balancing, bearings, condition monitoring, dynamic analysis and stability, wind turbines and generators, electromechanical interactions in rotor dynamics and turbochargers. The proceedings are divided into four volumes. This fourth volume covers the following main topics: aero-engines; turbochargers; eolian (wind) generators; automotive rotating systems; and hydro power plants. "