Theory of weakly nonlinear self sustained detonations

We propose a theory of weakly nonlinear multi-dimensional self sustained detonations based on asymptotic analysis of the reactive compressible Navier-Stokes equations. We show that these equations can be reduced to a model consisting of a forced, unsteady, small disturbance, transonic equation and a rate equation for the heat release. In one spatial dimension, the model simplifies to a forced Burgers equation. Through analysis, numerical calculations and comparison with the reactive Euler equations, the model is demonstrated to capture such essential dynamical characteristics of detonations as the steady-state structure, the linear stability spectrum, the period-doubling sequence of bifurcations and chaos in one-dimensional detonations and cellular structures in multi- dimensional detonations

Theory of weakly nonlinear self-sustained detonations

We propose a theory of weakly nonlinear multidimensional self-sustained detonations based on asymptotic analysis of the reactive compressible Navier-Stokes equations. We show that these equations can be reduced to a model consisting of a forced unsteady small-disturbance transonic equation and a rate equation for the heat release. In one spatial dimension, the model simplifies to a forced Burgers equation. Through analysis, numerical calculations and comparison with the reactive Euler equations, the model is demonstrated to capture such essential dynamical characteristics of detonations as the steady-state structure, the linear stability spectrum, the period-doubling sequence of bifurcations and chaos in one-dimensional detonations and cellular structures in multidimensional detonations

On "jamitons," self-sustained nonlinear traffic waves

"Phantom jams," traffic blockages that arise without apparent cause, have long frustrated transportation scientists. Herein, we draw a novel homology between phantom jams and a related class of self-sustained transonic waves, namely detonations. Through this analogy, we describe the jam structure; favorable agreement with reported measurements from congested highways is observed. Complementary numerical simulations offer insights into the jams' development. Our results identify conditions likely to result in a dangerous concentration of vehicles and thereby lend guidance in traffic control and roadway design.Comment: 6 pages, 4 figure

PENGARUH PENGGANTIAN KONSENTRAT DENGAN AMPAS AREN FERMENTASI DALAM RANSUM TERHADAP KECERNAAN BAHAN KERING DAN SERAT KASAR DOMBA EKOR TIPIS JANTAN

ABSTRAK Penelitian ini bertujuan untuk mengetahui pengaruh penggantian konsentrat dengan ampas aren fermentasi (AAF) dalam ransum terhadap kecernaan bahan kering dan serat kasar pada domba ekor tipis jantan. Penelitian ini dilaksanakan pada 22 Februari sampai 22 Maret 2016 di kandang domba Minifarm milik Program Studi Peternakan, Fakultas Pertanian, Universitas Sebelas Maret Surakarta yang berlokasi di Desa Jatikuwung, Gondangrejo, Karanganyar. Materi yang digunakan 12 domba ekor tipis jantan dengan bobot badan awal rata-rata 15,66±2,75 Kg. Desain penelitian yang digunakan adalah rancangan acak kelompok (RAK) dengan tiga perlakuan dan setiap perlakuan terdiri dari empat kelompok bobot badan. Perlakuan yang diberikan adalah penggantian konsentrat dengan AAF dalam ransum, yaitu : P0 = 60% rumput raja + 39% konsentrat + 1% Premix + 0% AAF, P1 = 60% rumput raja + 39% konsentrat + 1% Premix + 5% AAF, P2 = 60% rumput raja + 29% konsentrat + 1% Premix + 10% AAF masing ˗ masing berdasarkan bahan kering. Peubah yang diamati adalah konsumsi bahan kering (BK), konsumsi serat kasar (SK), kecernaan bahan kering (KcBK) dan kecernaan serat kasar (KcSK). Analisis variansi digunakan untuk mengetahui adanya pengaruh perlakuan terhadap peubah yang diamati. Hasil penelitian menunjukkan bahwa tidak terdapat pengaruh nyata penggantian konsentrat sampai tingkat 25,64% atau penggantian 10% dalam ransum. Simpulan penelitian ini adalah AAF mampu menggantikan konsentrat sampai tingkat 25,64% atau penggantian 10% dalam ransum dilihat dari konsumsi bahan kering dan serat kasar serta kecernaan bahan kering dan serat kasar. Kata kunci : domba ekor tipis, ampas aren fermentasi, bahan kering, serat kasa