Contraction integral equation method in three-dimensional electromagnetic modeling

Journal ArticleThe integral equation method has been proven to be an efficient tool to model threedimensional electromagnetic problems . Owing to the full linear system to be solved, the method has been considered effective only in the case of models consisting of a strongly limited number of cells. However, recent advances in matrix storage and multiplication issues facilitate the modeling of horizontally large structures. Iterative methods are the most feasible techniques for obtaining accurate solutions for such problems. In this paper we demonstrate that the convergence of iterative methods can be improved significantly, if the original integral equation is replaced by an equation based on the modified Green's operator with the norm less or equal to one. That is why we call this technique the Contraction Integral Equation (CIE) method. We demonstrate that application of the modified Green's operator can be treated as a preconditioning of the original problem. We have performed a comparative study of the convergence of different iterative solvers applied to the original and contraction integral equations. The results show that the most effective solvers are the BIGGSTAB, QMRCGSTAB, and CGMRES algorithms, equipped with preconditioning based on the CIE method

Analisis Faktor yang Berhubungan Dengan Stres Narapidana Tipidum di Lembaga Pemasyarakatan Kelas IIA Yogyakarta

Latar belakang: Seseorang yang menjalani kehidupan didalam lapas dapat membuat suatu perubahan psikologis bagi seorang narapidana, beban serta tekanan yang dialami menyebabkan narapidana mudah mengalami stres. Stres merupakan respon adaptif terhadap kondisi mental seseorang sehingga mempengaruhi perubahan fisik, psikologis, dan perilaku seseorang. Tujuan: dari penelitian ini adalah untuk mengetahui faktor-faktor apa saja yang berhubungan dengan stres pada narapidana selama berada dilapas. Metode: penelitian ini adalah penelitian kuantitatif observasional analitik dengan desain cross sectional. Sampel dalam penelitian ini adalah narapidana kasus tindak pidana umum (tipidum) yang sedang menjalani masa hukuman 1 sampai 5 tahun sebanyak 127 responden dengan menggunakan teknik total sampling. Data dikumpulkan dengan menggunakan kuesioner dan dianalisis menggunakan uji korelasi Spearman Rank. Hasil: uji korelasi Spearman Rank menunjukkan bahwa dukungan sosial keluarga mendapat hasil (p = 0,000 < 0,05) dengan nilai koefisien korelasi 0,662 menunjukkan korelasi positif, sedangkan adaptasi mendapatkan hasil (p = 0,021 < 0,05) dengan korelasi koefisien sebesar 0,025 menunjukkan korelasi positif, serta untuk tingkat spiritual narapidana diperoleh hasil (p = 0,017 > 0,05) dimana nilai koefisien korelasi 140 menunjukkan korelasi negatif. Kesimpulan: ada hubungan dukungan sosial keluarga dengan stres, ada hubungan adaptasi dengan stres, dan tidak ada hubungan tingkat spiritual dengan stres pada narapidana dilapas Kelas IIA  Yogyakarta.

Additive manufacturing: unlocking the evolution of energy materials

The global energy infrastructure is undergoing a drastic transformation towards renewable energy, posing huge challenges on the energy materials research, development and manufacturing. Additive manufacturing has shown its promise to change the way how future energy system can be designed and delivered. It offers capability in manufacturing complex 3D structures, with near-complete design freedom and high sustainability due to minimal use of materials and toxic chemicals. Recent literatures have reported that additive manufacturing could unlock the evolution of energy materials and chemistries with unprecedented performance in the way that could never be achieved by conventional manufacturing techniques. This comprehensive review will fill the gap in communicating on recent breakthroughs in additive manufacturing for energy material and device applications. It will underpin the discoveries on what 3D functional energy structures can be created without design constraints, which bespoke energy materials could be additively manufactured with customised solutions, and how the additively manufactured devices could be integrated into energy systems. This review will also highlight emerging and important applications in energy additive manufacturing, including fuel cells, batteries, hydrogen, solar cell as well as carbon capture and storage