197,213 research outputs found
Incorporating domain knowledge into the optimization of energy systems
No full textAbstract not availableMd Shahriar Mahbub, Markus Wagner, Luigi Crem
(m) Sabīl de 'Ā'isha as-Suṭūhiyya
No full textSimaïka Marcus H., Shafik Muhammad, 'Amrusi Ahmad Fahmi al-, Mahbub Mahmud Sabri, Sayed Metoualli, Pauty Edmond. (m) Sabīl de 'Ā'isha as-Suṭūhiyya. In: Comité de Conservation des Monuments de l'Art Arabe. Fascicule 37, exercice 1933-1935, 1940. p. 144
Disc fragmentation and the formation of Population III stars
No full textOur understanding of Population III star formation is still in its infancy. They are formed in dark matter minihaloes of 10(5)-10(6) M-circle dot at z = 20-30. Recent high-resolution cosmological simulations show that a protostellar disc forms as a consequence of gravitational collapse and fragments into multiple clumps. However, it is not entirely clear if these clumps will be able to survive to form multiple stars as simulations are unable to follow the disc evolution for longer times. In this study, we employ a simple analytical model to derive the properties of marginally stable steady-state discs. Our results show that the stability of the disc depends on the critical value of the viscous parameter alpha. For alpha(crit) = 1, the disc is stable for an accretion rate of = 100 au in the presence of an accretion rate of 10(-2) M-circle dot yr(-1). For 0.06 < alpha(crit) < 1, the disc can be unstable for both accretion rates. The comparison of the migration and the Kelvin-Helmholtz time-scales shows that clumps are expected to migrate inwards before reaching the main sequence. Furthermore, in the presence of a massive central star, the clumps within the central 1 au will be tidally disrupted. We also find that UV feedback from the central star is unable to disrupt the disc, and that photoevaporation becomes important only once the accretion rate has dropped to 2 x 10(-4) M-circle dot yr(-1). As a result, the central star may reach a mass of 100 M-circle dot or even higher.European Research Council under the European Community [614199
Peran KH. Mahbub Ihsan dalam perkembangan Muhammadiyah di Tuban (1966-2000)
No full textSkripsi ini meneliti beberapa masalah, yaitu: (1) Bagaimana Biografi KH. Mahbub Ihsan; (2) Bagaimana perkembangan Muhammadiyah di Tuban, dan (3) Apa saja Kontribusi KH. Mahbub Ihsan bagi Muhammadiyah di Tuban. Permasalahan-permasalahan tersebut akan penulis teliti dengan menggunakan dua pendekatan yaitu pendekatan Biografis dan Historis. Pendekatan biografis adalah pendekatan dengan rujukan eksplisit terhadap kehidupan, kepribadian, dan pengalaman seseorang, atau suatu subyek dengan berbagai latar belakang. Sedangkan pendekatan historis bertujuan untuk mengetahui dan mendeskripsikan asal-usul perkembangan serta pertumbuhan suatu agama. Adapun teori yang digunakan sesuai teori yang diutarakan oleh Max Weber yaitu kepemimpinan. Sedangkan metode yang digunakan adalah metode sejarah yaitu melalui tahapan Heuristik, Kritik sumber, Interpretasi, dan Historiografi. Dari penelitian yang dilakukan, dapat disimpulkan bahwa: Pertama, KH. Mahbub Ihsan dilahirkan di Desa Sedayu Lawas Kecamatan Brondong Kabupaten Lamongan pada tanggal 05 Maret 1931. Ia adalah ketua PDM Tuban yang terkenal dengan kesederhanaan dan mempunyai wawasan ilmu yang luas dalam memimpin Muhammadiyah Tuban (1966-2000). Ia meninggal pada tanggal 26 Februari 2003, jenazah dikebumikan di pemakaman keluarga Sedayu Lawas Lamongan. Kedua, Perkembangan Muhammadiyah di Tuban mengalami perubahan setiap regenerasi kepengurusan PDM, baik dari aspek struktur keorganisasian maupun Amal Usaha Muhammadiyah. Ketiga, kontribusi KH. Mahbub Ihsan dalam bidang pendidikan yakni mendirikan lembaga pendidikan seperti SD (1), MI (2), SMP (4), MTs (2), dan STIE. Bidang sosial adanya toleransi antar umat beragama, berbagi kepada orang-orang lansia, dan yatim piatu. Bidang keagamaan beliau memberikan ceramah-ceramah keagamaan kepada masyarakat Tuban pada khususnya dan masyarakat Islam pada umumnya
A genetic algorithm for designing microarray experiments
No full textHeuristic techniques of optimization can be useful in designing complex experiments, such as microarray experiments. They have advantages over the traditional methods of optimization, particularly in situations where the search space is discrete. In this paper, a search procedure based on a genetic algorithm is proposed to find optimal (efficient) designs for both one- and multi-factor experiments. A genetic algorithm is a heuristic optimization method that exploits the biological evolution to obtain a solution of the problem. As an example, optimal designs for factorial microarray experiments are presented for different numbers of arrays and for various sets of research questions. Comparisons between different operators of the genetic algorithm are performed by simulation studies
8° Monographies de M. Monneret de Villard
No full textSimaïka Marcus H., Greg Robert Hyde, Verrucci Ernesto, Mahbub Mahmud Sabri, Ahmad Ali Hasan, Sayed Metoualli, Pauty Edmond. 8° Monographies de M. Monneret de Villard. In: Comité de Conservation des Monuments de l'Art Arabe. Fascicule 36, exercice 1930-1932, 1936. p. 268
m) Tombeau d'Ibrahim et Guirguis al-Gôhari
No full textSimaïka Marcus H., Greg Robert Hyde, Verrucci Ernesto, Mahbub Mahmud Sabri, Ahmad Ali Hasan, Sayed Metoualli, Pauty Edmond. m) Tombeau d'Ibrahim et Guirguis al-Gôhari. In: Comité de Conservation des Monuments de l'Art Arabe. Fascicule 36, exercice 1930-1932, 1936. p. 273
[3.] Proposition de nomination de M. Maḥmūd Eff. Aḥmad, chef du bureau des monuments, comme membre du Comité
No full textSimaïka Marcus H., Shafik Muhammad, 'Amrusi Ahmad Fahmi al-, Mahbub Mahmud Sabri, Sayed Metoualli, Pauty Edmond. [3.] Proposition de nomination de M. Maḥmūd Eff. Aḥmad, chef du bureau des monuments, comme membre du Comité. In: Comité de Conservation des Monuments de l'Art Arabe. Fascicule 37, exercice 1933-1935, 1940. p. 142
THE FORMATION OF MASSIVE PRIMORDIAL STARS IN THE PRESENCE OF MODERATE UV BACKGROUNDS
No full textRadiative feedback produced by stellar populations played a vital role in early structure formation. In particular, photons below the Lyman limit can escape the star-forming regions and produce a background ultraviolet (UV) flux, which consequently may influence the pristine halos far away from the radiation sources. These photons can quench the formation of molecular hydrogen by photodetachment of H-. In this study, we explore the impact of such UV radiation on fragmentation in massive primordial halos of a few times 10(7) M-circle dot. To accomplish this goal, we perform high resolution cosmological simulations for two distinct halos and vary the strength of the impinging background UV field in units of J(21) assuming a blackbody radiation spectrum with a characteristic temperature of T-rad = 10(4) K. We further make use of sink particles to follow the evolution for 10,000 yr after reaching the maximum refinement level. No vigorous fragmentation is observed in UV-illuminated halos while the accretion rate changes according to the thermal properties. Our findings show that a few 10(2)-10(4) solar mass protostars are formed when halos are irradiated by J(21) = 10-500 at z > 10 and suggest a strong relation between the strength of the UV flux and mass of a protostar. This mode of star formation is quite different from minihalos, as higher accretion rates of about 0.01-0.1 M-circle dot yr(-1) are observed by the end of our simulations. The resulting massive stars are potential cradles for the formation of intermediate-mass black holes at earlier cosmic times and contribute to the formation of a global X-ray background
Massive black hole factories: Supermassive and quasi-star formation in primordial halos
No full textContext. Supermassive stars and quasi-stars (massive stars with a central black hole) are both considered as potential progenitors for the formation of supermassive black holes. They are expected to form from rapidly accreting protostars in massive primordial halos. Aims. We explore how long rapidly accreting protostars remain on the Hayashi track, implying large protostellar radii and weak accretion luminosity feedback. We assess the potential role of energy production in the nuclear core, and determine what regulates the evolution of such protostars into quasi-stars or supermassive stars. Methods. We followed the contraction of characteristic mass shells in rapidly accreting protostars, and inferred the timescales for them to reach nuclear densities. We compared the characteristic timescales for nuclear burning with those for which the extended protostellar envelope can be maintained. Results. We find that the extended envelope can be maintained up to protostellar masses of 3.6 x 10(8) m(3) M-circle dot, where m. denotes the accretion rate in solar masses per year. We expect the nuclear core to exhaust its hydrogen content in 7 x 106 yr. If accretion rates m >> 0.14 can still be maintained at this point, a black hole may form within the accreting envelope, leading to a quasi-star. Alternatively, the accreting object will gravitationally contract to become a main-sequence supermassive star. Conclusions. Due to the limited gas reservoir in typical 10(7) M-circle dot dark matter halos, the accretion rate onto the central object may drop at late times, implying the formation of supermassive stars as the typical outcome of direct collapse. However, if high accretion rates are maintained, a quasi-star with an interior black hole may form
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