In this paper, we investigate the initial-boundary value problem of compressible Euler equations including friction and heating that model the transonic Fanno–Rayleigh flows through symmetric variable area nozzles. In particular, the case of contracting nozzles is considered. A new version of a generalized Glimm scheme (GGS) is presented for establishing the global existence of entropy solutions with bounded variation. Modified Riemann and boundary Riemann solutions are applied to design this GGS, which is constructed using the contraction matrices acting on the homogeneous Riemann (or boundary-Riemann) solutions. The extended Glimm–Goodman’s type of wave interaction estimates are investigated to determine the stability of the scheme and the positivity of gas velocity that results in the existence of the weak solution. The limit of approximation solutions serves as an entropy solution. Moreover, a quantitative relation between the shape of the nozzle, friction, and heat is proposed for the global existence result in the contracting nozzle. Numerical simulations of the contraction-expansion and expansion-contraction nozzles are presented to validate the scheme.
Through mathematics, this paper works to analyse the Index of Difficulty in ISO9241-Part 411: Evaluation methods for the design of physical input devices. It was proven that all the target circles always intersect for very low Index of Difficulty; which conjectured to disturb the experiment or affect the focus of the subject. Some examples are provided, in addition, to support the proof. We hope this proof will contribute to the improvement of ISO9241, where the result might become a special attention to the designer of the experiment in human-computer interaction field; especially in checking the influence of overlap area in the human factor.
Interaksi manusia dan komputer (Human Computer Interaction – HCI) adalah suatu ilmu yang mengkaji tentang interaksi antara manusia dengan komputer meliputi perancangan, evaluasi dan implementasi interface komputer agar mudah digunakan oleh manusia. Dengan dua kemajuan dibidang teknologi dan human computer interaction ini diharapkan dapat digunakan untuk membantu orang – orang yang memiliki keterbatasan yaitu penyandang disabilitas. Seseorang yang memiliki keterbatasan fisik seharusnya dibantu agar dapat tetap produktif meskipun dengan segala keterbatasan yang ada. Penelitian ini bertujuan membandingkan gesture pitch-roll dan pitch-yaw pada penggunaan sensor inersia untuk mengemulasikan gerakan kursor mouse yang dapat dimanfaatkan oleh penyandang disabilitas, dimana tidak dapat mengoperasikan mouse dalam kondisi normal. Setiap gesture akan dievaluasi menggunakan prosedur dalam ISO 9241-411 tentang evaluasi pointing device. Performansi kuantitatif yang diukur meliputi throughput dan movement time, sedangkan evaluasi kualitatif menggunakan angket uji kenyamanan. Hasil throughput untuk mouse sebesar 5.063 bps, untuk pitch-roll sebesar 1.114 bps sedangkan untuk pitch-yaw sebesar 1.116 bps. Hasil analisis statistik menyatakan terdapat perbedaan signifikan antara mouse dan kedua gesture sensor. Namun antar gesture tidak ditemukan perbedaan secara signifikan.
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