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All Journal Jurnal Matematika & Sains Krigan: Journal of Management and Sharia Business
Muhamad Irfan Hakim
Astronomy Group, Faculty Of Mathematics And Natural Sciences Bandung Institute Of Technology, Bandung
Economics, Econometrics & Finance Mathematics

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The Temporal Variations in Sunspot Number, Geomagnetic aa index and Southern Oscillation Index Iratius Radiman; Hiroshi Miyake; Chatief Kunjaya; Yoji Takeoka; Muhamad Irfan Hakim; Zadrach L. Dupe
Jurnal Matematika & Sains Vol 7, No 1 (2002)
Publisher : Institut Teknologi Bandung

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Abstract

A study of three monthly solar-terrestrial indices of mean sunspot number, geomagnetic aa index, and Southern Oscillation Index during period of 1882 to 2000 was carried out to find any consistent short –term periodicities. We found 19, 22, and 26-month periodicities persistently occur in the above data, i nstead of 11-year pattern. We suggest that they might have solar activity origin.
Solar Cycle Variations and its Effects on El Niño/La Niña Behaviour Iratius Radiman; Dhani Herdiwidjaja; Zadrach L. Dupe; Chatief Kunjaya; Muhammad Irfan Hakim
Jurnal Matematika & Sains Vol 8, No 2 (2003)
Publisher : Institut Teknologi Bandung

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Abstract

Variations in the Solar Cycle has been known for a long time. The Solar Cycle is observed to vary from 14 to 8 years in length. The reconstructions of the annual solar total irradiance since the beginning of Maunder Minimum (from year 1600) to year 2000 show that there are envelopes of groups sunspot numbers. The intensities delineated by the envelopes are consistent with the range of CaII brightness. The timelength of the envelopes corresponds to long term variabilities such as the Gleissberg Cycle of 88 and 124 years period. A close correlation between total irradiance and sunspot number from 1610 to 2000 is found to be 0.88. Although the work of Labitzke and van Loon has clearly shown the existence of an oscillation in many atmospheric parameters with a period in the vicinity of 11 years and a phase that is related to that of solar activity, there is reluctance to accept a relationship to the 11-year solar cycle. Therefore this study aimed to pursue the investigations further by determining the correlation coefficients to lower trophospheric layers. Our studies reveal to results, which we summarized as follows: A weak correlation at 27 month delay is found between solar activities and the El Niño/La Niña phenomena. The next El Niño/La Niña event is expected to occur from year 2002 until mid 2003. A major change in the pattern of the solar cycle since 1700 appears. The sun is seen to be more frequent in its active states over the last 100 years. The length of the cycle is becoming shorter. The solar cycles modulate from 5, 8, 12 and 25-year period obtained from its total irradiance plot. The 5-year period coincides very well within the El Niño/La Niña period of 2 to 7-year. The El Niño/La Niña phenomenon has a 10-12 month duration. Every El Niño/La Niña event is separated from 24 to 84 months duration in an irregular pattern. Every El Niño/La Niña event is unique. These conclusions are drawn after decomposing the SST Anomaly Index through applied Fourier Transform. The effect of the solar cycle variations is to generate long period harmonics in the coming El Niño/La Niña events. We expect that more variability in climate will occur in the coming decade.
Database and Animation Package of Stellar Evolution Study Mahaseana Putra; Muhamad Irfan Hakim; Aprilia Wardana; Winardi Sutantyo
Jurnal Matematika & Sains Vol 11, No 3 (2006)
Publisher : Institut Teknologi Bandung

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The study of stellar evolution is an active major branch in astrophysics. Results from stellar evolution studies are indispensable for studies in some other areas such as chemical evolution of star clusters and galaxies. Recently theoretical/computational studies of stellar evolution often involve large populations of stars (~106) which need databases of evolution tracks with various realistic parameters (mass, chemical composition, etc). In this paper, an attempt in building such a database and construction of animations of the evolution of stellar internal structures and isochrones which is useful in teaching stellar evolution were described.
Analisis Kendala Operasional Travel Umrah Terkait Visa, Transportasi, Akomodasi (Studi Kasus PT. Arasy Bungo Mandiri) Muhamad Irfan Hakim
Krigan: Journal of Management and Sharia Business Vol. 3 No. 1 (2025): Juni 2025
Publisher : Universitas Islam Negeri Sjech M. Djamil Djambek Bukittinggi

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30983/krigan.v3i1.9457

Abstract

Penelitian ini bertujuan untuk menganalisis kendala operasional yang dihadapi oleh biro perjalanan umrah, khususnya PT. Arasy Bungo Mandiri, dalam mengelola tiga aspek penting yaitu pengurusan visa, penyediaan transportasi, dan akomodasi jamaah, di tengah fluktuasi nilai tukar rupiah dan kenaikan harga hotel di Arab Saudi. Perubahan sistem digitalisasi visa melalui platform Nusuk, ketergantungan terhadap mata uang asing dalam pembiayaan operasional, serta dinamika pasar akomodasi di kota suci menjadi tantangan besar bagi PPIU (Penyelenggara Perjalanan Ibadah Umrah) skala menengah. Penelitian ini menggunakan pendekatan kualitatif dengan metode studi kasus, pengumpulan data dilakukan melalui wawancara mendalam, observasi partisipatif, dan dokumentasi. Hasil penelitian menunjukkan bahwa tantangan pengelolaan visa mencakup kendala teknis sistem digital, keterbatasan SDM IT, serta ketergantungan pada pihak ketiga dalam pengajuan visa. Sementara itu, fluktuasi kurs menyebabkan ketidakseimbangan antara biaya dan harga paket, yang berdampak pada margin keuntungan dan keberlanjutan usaha. Kenaikan harga hotel turut memaksa biro untuk menyesuaikan layanan akomodasi, yang terkadang berdampak pada kenyamanan dan kepuasan jamaah. Penelitian ini menyimpulkan bahwa strategi adaptif seperti penguatan SDM digital, diversifikasi paket umrah, manajemen risiko keuangan, serta komunikasi yang transparan kepada jamaah menjadi solusi penting dalam menghadapi tekanan eksternal tersebut. Implikasi dari temuan ini memberikan kontribusi teoritis dalam kajian manajemen operasional berbasis syariah serta implikasi praktis bagi peningkatan kualitas layanan PPIU di Indonesia.
Co-Authors Aprilia Wardana Chatief Kunjaya Dhani Herdiwidjaja Hiroshi Miyake Iratius Radiman Mahaseana Putra Winardi Sutantyo Yoji Takeoka Zadrach L. Dupe