Journal of Mathematical and Fundamental Sciences
Not a member yet
737 research outputs found
Sort by
B-emission Stars in Southern Sky Observed in Bosscha Observatory: Spectroscopic Study of Hα Spectral Line Variability
Get PDFHα line variations of 8 B-emission (Be) stars are presented. Stars that are listed in the Bright Star Catalogue were observed in 2009 at the Bosscha Observatory, Lembang, Indonesia. It was found that 4 stars showed phase changing from Be double-peaked to Be single-peaked emission line profiles, 1 showed single-peaked to double-peaked profiles, 1 showed double-peaked to B-normal, while two other stars did not show phase changing. The stars also showed variations in the V/R and E/C values, which represent the strength of the emission lines. The phase changes were detected from a comparison of the observed data to the current data in the BeSS database
Pengaruh Asam Metoksiasetat terhadap Organ Reproduksi Mencit (Mus musculus) Swiss Webster Jantan
No full textSari. Asam metoksiasetat (MAA) merupakan salah satu metabolit dari dimetoksietil ftalat (DMEP) yaitu suatu senyawa yang banyak digunakan dalam pembuatan plastik sebagai pelentur (plasticizer). DMEP dapat luruh dari plastik dan bila masuk ke dalam tubuh manusia, zat ini diubah menjadi MAA yang dapat menyebabkan efek teratogenik dan toksik terhadap organ tubuh. Terutama organ reproduksi jantan. Untuk meneliti pengaruh MAA terhadap organ reproduksi jantan, digunakan mencit Swiss Webster umur 7 minggu, yang cliberi dosis 100, 150, 225, dan 300 mg/kg berat badan, secara gavage setiap hari selama 4 minggu berturut-turut, dengan satu hari istirahat pada tiap akhir minggu. Kelompok mencit kontrol hanya diberi akuabides sebagai pelarut MAA. Mencit dibunuh sehari setelah pemberian MAA terakhir. Pengamatan dilakukan terhadap berat testis, berat epididimis, dan berat vesikula seminalis; jumlah, motilitas, dan morfologi spermatozoa yang diperoleh dari epididimis kauda; struktur testis yang mencakup diameter, tebal epitel, dan penampilan tubulus seminiferus; jumlah sel spermatogenik, jumlah sel Sertoli, serta jumlah sel Leydig. Dibandingkan dengan kontrol, hasil pengamatan menuniukkan penurunan berat testis dan epididimis, tetapi tidak ada penurunan berat vesikula seminalis. Jumlah dan motilitas spermatozoa menjadi lebih rendah, sedangkan jumlah spermatozoa abnormal meningkat. Diameter dan tebal epitel tubulus seminiferus menurun, demikian pula persentase tubulus seminiferus normal (fase VII), sedangkan persenfase tubulus seminiferus abnormal meningkat. Pendedahan terhadap MAA menyebabkan berdegenerasinya sel-sel spermatogenik, terutama spermatosit pakhiten dans permatid, yang ditunjukkan oleh jumlahnya yang berkurang. Spermatogonium A dan spermatosit praleptoten paling tahan terhadap MAA. Jumlah sel Sertoli dan sel Leydig tidak menurun oleh perlakuan MAA meskipun tampak adanya gejala toksik pada sel Sertoli yang ditandai oleh vakuolisasi dalam sitoplasma. Dapat disimpulkan bahwa testis merupakan organ reproduksi yang paling sensitif terhadap pengaruh MAA yang mengakibatkan terganggunya spermatogenesis pada mencit Swiss Webster. Effects of Methoxyacetic Acid on the Reproductive Organs of Male Swiss Webster Mice (Mus Musculus)Abstract. Methoxyacetic acid (MAA) is one of the metabolites of dimethoxyethyl phthalate (DMEP), which is mainly used as plasticizer in the manufacture of plastics. DMEP could leach from plastics and by entering the body, it will be metabolized into MAA which is teratogenic and toxic to several organs, particularly male reproductive organs. To investigate the effects of MAA on the male reproductive organs, seven-week-old Swiss Webster mice were treated with MAA at the doses of 100, 150, 225, and 300 mg/kg body weight daily by gavage, within four consecutive weeks with one-day interruption in each weekend. Observation was performed on the weight of testis, epididymis and seminal vesicle; the number, motility, and morphology of the spermatozoa obtained from the caudal epididymist; the histological structure of testis, including diameter, epithelial thickness and the performance of seminiferous tubule; the number of spermatogenic cells, as well as the number of Sertoli and Leydig cells. Compared to control the result showed, that testis and epididymis, but not the seminal vesicle decreased in weight. The number and motility of spermatozoa decreased, whereas the abnormal ones increased. The diameter, the epithelial thickness, as well as the percentage of normal (stage VII) seminiferous tubules were reduced, while the percentage of abnormal tubules increased. The administration of MAA led to the degeneration of spermatogenic cells, particularly the pachytene spermatocyte and spermatids, shown by the reduction in their number. The spermatogonia A and the preleptotene spermatocytes were the most resistant spermatogenic cells to MAA. The number of Sertoli and Leydig cells were not affected by MAA, despite toxic phenomenon of Sertoli cells characterized by vacuolization in the cytoplasm was shown. It is concluded that testis is the most susceptible to MAA insult, which subsequently interferes the spermatogenesis of male Swiss Webster mice
Respons Getaran Non-Linier pada Sistem Poros-rotor Bagian II: Kaji Banding Metode Runge-Kutta dan Metode Deret Fungsional Volterra
No full textSari. Bantalan gelinding digunakan secara luas sebagai pemompa pada setiap mesin rotasi. Oleh karena itu, karakteristik dinamina suatu bantalan harus dapat diketahui dengan baik. Karakteristik dinamik bantalan yang diketahui dapat digunakan untuk menganalisis respons getaran yang terjadi pada struktur yang menggunakan bantalan tersebut. Sayangnya mekanisme kontak pada bantalan mengakibatkan kekakuan yang tidak linier pada bantalan. Hal ini mengakibatkan bantalan gelinding merupakan system getaran non-linier. Analisis FRF Non-Linier dapat dilakukan dengan memanfaatkan deret Voltera. Dalam penelitian ini deret Voltera digunakan untuk menentukan FRF Non-Linier dari bantalan yang diamati sehingga dapat diramalkan respons getarannya pada frekuensi harmonic akibat sinyal pengeksitasi. Non-linear Vibration Respons of Bearing System Part II: Comparative Study of Runge-Kutta metho and Volterra-functional-series methodAbstract. Rotating machinery is commonly utilized in the processing industry. Vibration monitoring based on predictive maintenance technology is widely utilized for condition monitoring of the rotating machinery in service. This maintenance technology is based on the signature of the vibration response normally measured at the bearing house. On the other hand, the vibration response of a system is determined by the system dynamic characteristic and its working stimulus. Therefore the nature of the main component dynamic characteristics results in significant influence on the predicted vibration response at the bearing house. As mentioned above the signature of the vibration response measured at the bearing house and presented in the frequency domain contains several harmonic signals. Most of the higher harmonics do not have physical meanings, but they exist in the vibration measurement results and confused the researchers. Regarding those harmonic signals a hypothesis can be developed for identifying its origin. They are assumed to be generated due to dynamic characteristic non-linearity of the vibration system combined with the stiffness non-linearity of the roll bearing. By analyzing harmonic signal response due to nonlinear property of the vibration system, hopefully the mechanical signature of nonlinear vibration system can be generated. Therefore, many other mechanical signatures of components failure can be formulated and the harmonic signals, which are usually occurred, can be predicted more accurately
Respons Getaran Non-Linier pada Sistem Poros-rotor Bagian I: Pengaruh Celah Bantalan
Get PDFSari. Dalam kegiatan anaiisis ini diiakukan permodelan sistem getaran dengan gaya eksitasi yang berasal dari ketidakseimbangan rotor dan ketaksesumbuan poros. Gaya eksitasi ini kemudian diteruskan ke bantalan dan selanjutnya melulaui bantalan diteruskan ke rumah bantalan. Ketaklinieran kekakuan sistem bantalan yang berasal dari celah (clearance) bantalan tersebut akan menghasilkan ciri sendiri sehinngga ciri ini dapat digunakan untuk mengidentifikasi keausan bantalan yang digunakan. Hasil analisis teoritik ini selanjutnya dibandingkan dengan data gertaran domain waktu (waveform) yang diperoleh dari kaji eksperimental pada sistem poros-tutor. Mechanical Signature Analysis of Synchronous and synchronous Excited Rotating Rotor Supported by Rolling Element BearingAbstract. An analytical model of a rotor shaft vibration system subjected to rotor unbalance and shaft misalignment excitation forces has been developed. Those excitation forces are transmitted to a bearing housing through a roller bearing housing where the vibration response is measured. The non-linearity of the bearing stiffness due to the bearing clearance reveals some specific vibration signatures, which can be utilized for bearing, wear identification. The theoretical results obtained in this study are compared with those obtained from experiment.
Extention of Upper Bound Sampling Times for Discrete Implementation of a Continuous Controller
Get PDFTulisan ini memperbaiki syarat cukup yang diusulkan oleh Astuti dkk sehingga implementasi diskret suatu pengendali kontinu tetap mengendalikan suatu sistem tak linier konvergen ke suatu bola. Seperti juga dalam Astuti dkk, syarat cukup tersebut dapat digunakan untuk menentukan batas atas periode cuplik yang akan menghasilkan sistem kendali data tercuplik yang bersifat konvergen. Lebih dari itu, batas atas yang dihasilkan dapat lebih baik dibandingkan dengan batas atas yang dihasilkan dengan menggunakan syarat cukup di Astuti dkk. Contoh sederhana diberikan untuk mempertunjukkan hasil tersebut. Extention of Upper Bound Sampling Times for Discrete Implementation of a Continuous ControllerThis note improves the sufficient conditions proposed by Astuti et. al. which guarantee the discrete implementation of a continuous controller remains resulting in the convergence of a nonlinear system. As in Astuti et. al. the proposed sufficient conditions can be used to determine an upper bound of sampling times resulting in the convergence of the closed loop sampled data control system. Further, the obtained upper bound of sampling time can be better than the upper bound obtained using the conditions in Astuti et. al. A simple example is given to demonstrate the result
The Effects of Tropospheric Bias on Deformation Monitoring of MT. Guntur using GPS Survey Method
Get PDFPemantauan deformasi gunung api yang andal menuntut ketelitian yang tinggi, yaitu sampai level keteliatian mm untuk kasus gunung api yang tengah 'bangkit' kembali. Konsekuensinya adalah kesalahan dan bias yang dapat mengurangi ketelitian dalam penentuan posisi dengan satelit GPS harus dieliminasi dana tau direduksi, seperti kesalahan yang disebabkan oleh bias troposfer. Pada kasus pemantauan deformasi gunung api dengan metode survei GPS, karena adanya perbedaan tinggi yang cukup besar dan variatif antara titik-titik dalam jaringan, maka efek kesalahan bias troposfer tidak sepenuhnya dapat direduksi dengan proses pengurangan data (differencing). Residu (sisa) bias troposter ini harus dikoreksi agar tingkat keteliatian yang dituntut oleh sistem pemantauan deformasi gunung api dapat tetap tercapai. Pada makalah ini akan dibahas efek bias troposfer pada pemantauan deformasi gunung api. Pembahasan didasarkan pada hasil yang diperoleh dari pemantauan deformasi G. Guntur (Garut, Jawa Barat) dengan metode survei GPS. The Effects of Tropospheric Bias on Deformation Monitoring of MT. Guntur using GPS Survey MethodA reliable volcano deformation monitoring requires a high positioning accuracy, i.e. up to mm level in the case of reawakening volcanoes. As a consequence of this requirement, the errors and biases affecting the GPS positioning accuracy has to be eliminated or reduced, which one of them is the tropospheric bias. In the case of volcano deformation monitoring using the GPS survey method, due to a relatively large altitude variation in the stations altitude, the effects of tropospheric bias could not be effectively reduced by the differencing process. In order to meet the accuracy requirement of volcano deformation monitoring system, this residual tropospheric bias, therefore, has to be somehow corrected or taken into account. In this paper, the effects of tropospheric bias on the volcano deformation monitoring will be discussed. The discussion is based on the results from the deformation monitoring of Guntur volcano in Garut, West Java, by using repeated GPS surveys
Oscillation of Second Order Nonlinear Differential Equations
Get PDFIn this paper we consider the following second order nonlinear differential equations:u" + f(t,u) = 0, t≥0Oscillation criteria for the above equation will be established by modification of the method that has been used previously. The results obtained will contain and improve the previous results. Some conditions imposed in the theorem will be less weaker than used before. Tulisan ini membahas persamaan diferensial nonlinear orde dua yang berbentuk:u " + f ( t , u ) = 0 , t>0Kriteria oskilasi untuk persamaan di atas dikaji dengan memodifikasi metode yang pernah dilakukan untuk menentukan kriteria oskilasi untuk persamaan diferensial di atas. Hasil yang diperoleh memuat dan mengembangkan kriteria oskilasi sebelumnya. Beberapa asumsi dalam teorema lebih lemah dibandingkan dengan yang digunakan sebelumnya
A Fuzzy Relation Approach to Single Linkage
Get PDFSingle linkage is equivalent to sub-dominant ultrametric. Many algorithms are available for constructing these two objects. But all of then, except one which was proposed by Gondran, are very tedious because of the lack of algebraic structure. Gondran used a special algebraic system as theoretical bases. But it seems rather artificial. In this paper, we propose a more formal approach based on fuzzy relation. The main result presented here is the equivalence between sub-dominant ultrametric and the min-max transitive closure of a symmetric and anti reflexive fuzzy relation. This property enables us to construct an easy and efficient algorithm. At the end of this paper we will find its relationship with Gondran's approach
Ilmu Kimia Tanaman Lauraceae Indonesia: III*. Isolasi Aktinodafnin dan Boldin dari Litsea glutinosa
Get PDFAktinodafnin (I) dan boldin (lI), dua senyawa alkaloid dari jenis benzilisokuinolin, telah dipisahkan dari kulit akar tanaman Litsea glutinosa (Lour) C.B. Robinson var. littoralis Bl., suatu varitas yang belum pernah diselidiki peneliti lain. Struktur kedua alkaloid ini telah ditetapkan dengan cara-cara spektroskopi. Penemuan ini melanjutkan penemuan kami sebelumnya tentang suatu alkaloid fenantren baru, yang dinamai itebein, dari spesies tanaman yang sama. Two benzylisoquinoline alkaloids, actinodaphnine (I) and boldine (II), have been isolated from the root bark of Litsea glutinosa (Lour) C.B. Robinson var. littoralis Bl., a variety which has not yet been investigated by other workers. The chemical structures of both alkaloids have been determined by spectroscopic methods. This is to follow-up our previous work on the isolation of a new phenanthrene alkaloid, named itebeine, from the same plant species