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All Journal International Journal of Electrical and Computer Engineering Bulletin of Electrical Engineering and Informatics MUQTASID InfoTekJar : Jurnal Nasional Informatika dan Teknologi Jaringan Sinkron : Jurnal dan Penelitian Teknik Informatika JOURNAL OF INFORMATICS AND TELECOMMUNICATION ENGINEERING AKSIOLOGIYA : Jurnal Pengabdian Kepada Masyarakat Inovasi : Jurnal Ekonomi, Keuangan, dan Manajemen Abdimas Talenta : Jurnal Pengabdian Kepada Masyarakat Indonesian Physical Review JTIK (Jurnal Teknik Informatika Kaputama) Jurnal Sistem Komputer dan Informatika (JSON) Journal of Research in Mathematics Trends and Technology Unri Conference Series: Community Engagement Journal of Applied Data Sciences Journal of English Language and Education International Journal of Trends in Mathematics Education Research (IJTMER)
Tulus Tulus
Departemen Matematika, FMIPA Universitas Sumatera Utara
Agriculture, Biological Sciences & Forestry Humanities Computer Science & IT Control & Systems Engineering Decision Sciences, Operations Research & Management Economics, Econometrics & Finance Education Electrical & Electronics Engineering Engineering Languange, Linguistic, Communication & Media Law, Crime, Criminology & Criminal Justice Mathematics Physics Social Sciences Other

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Numerical Simulation of Effective Viscosity Distribution of Power-Law Engine Oil in Piston–Cylinder Lubrication Under High Shear Conditions Andre Ronaldo Situmorang; Tulus
Journal of Research in Mathematics Trends and Technology Vol. 8 No. 1 (2026): Journal of Research in Mathematics Trends and Technology (JoRMTT)
Publisher : Talenta Publisher

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32734/jormtt.v8i1.24922

Abstract

This study investigates the behavior of engine oil modeled as a non-Newtonian pseudoplastic fluid using the Power-Law equation under high operational conditions. The computational domain represents the lubricating oil film between the piston and cylinder wall. The governing equations include incompressible continuity and Navier–Stokes equa- tions coupled with a shear-rate-dependent viscosity model. Results show that shear rate con- centrates near the piston surface, reaching the order of 107 s−1 due to strong velocity gradients. As a consequence, effective viscosity decreases significantly in high shear regions, confirming shear-thinning behavior. The viscosity reduction directly affects the hydrodynamic pressure distribution while maintaining stable lubrication performance. These findings highlight the importance of incorporating shear-dependent viscosity to accurately predict lubrication characteristics in piston–cylinder systems operating at elevated shear conditions.
Empowering Scout Members of the 015-016 Scout Group through Digital Screen-Printing Training to Foster Creative Entrepreneurship in Dolok Ilir Tulus; Nuraini Abdul Azis; Tulus Joseph Marpaung; Putri Khairiah Nasution; Suriati; J.L. Marpaung
ABDIMAS TALENTA: Jurnal Pengabdian Kepada Masyarakat Vol. 10 No. 2 (2025): ABDIMAS TALENTA: Jurnal Pengabdian Kepada Masyarakat
Publisher : Talenta Publisher

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32734/abdimastalenta.v10i2.24600

Abstract

This community service program aimed to empower members of the 015-016 Scout Group at SMP Swasta Dolok Ilir, Indonesia, through digital screen-printing training to foster creative entrepreneurship. The program was implemented using a participatory and experiential learning approach, integrating digital graphic design training, hands-on practice with Direct-to-Film (DTF) screen-printing technology, product production, and basic entrepreneurial orientation. Training activities were supported by international collaboration with lecturers from Malaysia as part of strengthening Indonesia–Malaysia cooperation in education and community engagement. The results showed a clear improvement in participants’ digital skills, creativity, and practical production abilities. Most participants were able to independently design and produce screen-printed products with acceptable quality standards. The provision of modern screen-printing equipment and the establishment of a Creative Entrepreneurial Corner within the school further supported program sustainability by enabling continuous practice and school-based entrepreneurial activities. Furthermore, participants learned how to package and brand their products while exploring e-commerce platforms to access broader markets. The establishment of a school-based Creative Entrepreneurial Corner under the Scout Group further strengthened program continuity, serving as a platform for ongoing practice and business development. Overall, this initiative demonstrates that integrating digital skills with entrepreneurial training can significantly enhance the self-reliance, creativity, and economic potential of rural youth, offering a replicable model for community development in similar contexts.
Efficiency of Environmental Performance Measurement Using Data Envelopment Analysis (DEA) With Fuzzy Approach: English Nurul Nadhila; Tulus; Mardiningsih
Journal of Research in Mathematics Trends and Technology Vol. 7 No. 2 (2025): Journal of Research in Mathematics Trends and Technology (JoRMTT)
Publisher : Talenta Publisher

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32734/jormtt.v7i2.21717

Abstract

This study aims to analyze and measure environmental performance efficiency in residential areas in Medan City using the Data Envelopment Analysis (DEA) method combined with a fuzzy approach. Environmental performance is measured based on relevant inputs and outputs, where the data used are secondary data obtained from previous research reports. Fuzzification is applied to address uncertainty in the data by converting input and output values into Triangular Fuzzy Numbers (TFN). The results of the study show that out of the 4 Decision Making Units (DMUs) studied without using the fuzzy approach, only the Helvetia housing complex achieved 100% efficiency. Meanwhile, the efficiency values for Tuntungan, Martubung, and Johor housing estates were 85.92%, 88.69%, and 94.87%, respectively. When the fuzzy approach was applied, the efficiency values of the Johor and Helvetia housing estates reached 100% efficiency, while the Tuntungan and Martubung housing estates had an efficiency of 78.22%, indicating inefficiency. This inefficiency is caused by excessive use of drainage inputs, indicating that these housing complexes are unable to produce environmental outputs commensurate with the inputs used. This study recommends improving the quality and quantity of environmental management and cleanliness, as well as the availability and quality of green spaces, to enhance environmental efficiency in housing. The findings of this study provide important insights into the efficiency of environmental performance measurement and highlight opportunities for improvement in environmental management within housing.
Pemberdayaan Masyarakat Melalui Penangkaran Lebah Kelulut dan Konservasi Mangrove di Bagan Kuala Ameilia Zuliyanti Siregar; Tulus; Putri Chandra Ayu; Mohammad Basyuni
Aksiologiya: Jurnal Pengabdian Kepada Masyarakat Vol 10 No 3 (2026): Agustus
Publisher : Universitas Muhammadiyah Surabaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30651/aks.v10i3.29233

Abstract

Budidaya lebah kelulut (Heterotrigona itama) di kawasan pesisir tropis merupakan peluang ekonomi yang belum dimanfaatkan secara optimal oleh masyarakat Desa Bagan Kuala, Serdang Bedagai. Program Pengabdian kepada Masyarakat Desa Binaan Universitas Sumatera Utara bertujuan meningkatkan pengetahuan dan keterampilan masyarakat dalam pengelolaan mangrove, budidaya lebah kelulut, dan identifikasi hama serta pengelolaan habitat mangrove secara berkelanjutan. Program melibatkan 12 peserta lokal dan dilaksanakan melalui survei, sosialisasi, focus group discussion, pelatihan, praktik lapangan, pendampingan, dan evaluasi pada Agustus–September 2023. Peserta memperoleh tiga stup lebah kelulut beserta peralatan pendukung budidaya, sedangkan perangkap warna digunakan untuk mendukung pemantauan serangga pada kawasan mangrove. Program juga mendukung kegiatan penanaman 5.000 bibit mangrove. Hasil evaluasi menunjukkan peningkatan pemahaman peserta dari 40% sebelum program menjadi 90% setelah kegiatan. Integrasi konservasi mangrove dan budidaya lebah kelulut diharapkan dapat memperkuat peluang mata pencaharian yang ramah lingkungan dan berkontribusi terhadap kesejahteraan masyarakat pesisir di Desa Bagan Kuala, Kabupaten Serdang Bedagai, Sumatera Utara.
Co-Authors Abdul Aziz Ahmad Agusnady, Alfian Ameilia Zuliyanti Siregar Ameilia Zuliyanti Siregar Amlys, Amlys Syahputra Silalahi Andre Ronaldo Situmorang Badawi, Afif Budhiarti Nababan, Erna Butar Butar, Kartika Dewi Christian Sinaga, Christian Christy, Claudia Dardanila, Dardanila Dewi, Rafiqa Efendi, Syahril Erna Budhiarti Nababan Eva, Eva Sartini Bayu Farida Ariani Hariadi , Hariadi Susilo Herman Mawengkang J.L. Marpaung Junerdi Nababan Liana Liana Lubis, Rahmi Suliani Ma'ruf, Ma'ruf Tafsin Mardiningsih Mardiningsih Mardiningsih, Mardiningsih Marpaung, Rony Genevent Mohammad Basyuni Muhammad Zarlis, Muhammad Nabiyah, Ismi Ratin Napitu, Daniel Halomoan Saragi Nuraini Abdul Azis Nurul Nadhila Panjaitan, Nismah Poltak Sihombing Putri Chandra Ayu Putri Khairiah Nasution Putri, Mimmy Sari Syah Saib Suwilo Salim, Opim Sawaluddin Sawaluddin, Sawaluddin Sitompul, Opim Salim Sitompul Suharno Suharno Suriati Syahputra, Indra Edy Syamsul Arifin Tugiman Tugiman Tulus Joseph Marpaung Zakarias Situmorang Zarlis, M Zulkifli Nasution