Judul: Pemanfaatan Abu Sisa Pembakaran Sampah Padat Perkotaan sebagai Bahan Aditif Pembuatan Paving Block.
Abstrak: Abu yang dihasilkan dari proses pembakaran sampah menumpuk dan belum dimanfaatkan dengan baik. Salah satu solusinya adalah dengan memanfaatan abu sebagai bahan aditif dalam pembuatan paving block. Penelitian dilakukan pada bulan Maret-Juli 2019 dengan tujuan menganalisis kuat tekan paving block yang dibuat dengan tiga perlakuan dan satu kontrol, serta menganalisis kualitas air limpasan yang melewati paving block. Sampel abu yang digunakan diambil dari 6 titik sampel yang berada di Dramaga, Bogor. Penambahan abu tidak berpengaruh signifikan terhadap kuat tekan paving block. Penambahan abu pada paving block menurunkan kadar DO dan meningkatkan kadar COD. BOD dan kadar nitrit pada limpasan fluktuatif terhadap air limpasan paving block dengan penambahan abu. Paving block dengan penambahan abu 10% memiliki nilai kuat tekan sebesar 8.58 MPa yang memenuhi mutu D dengan kadar DO, BOD, dan COD pada air limpasan memenuhi baku mutu.
Keyword: air limpasan, kuat tekan, paving block, pembakaran terbuka

Judul: Formulasi Paving block dari Berbagai Bahan Berbasis Limbah Padat Spent bleaching earth
Abstrak: Spent bleaching earth (SBE) is a solid waste produced by refinery of crude palm oil industry. Utilization of SBE as a substitution material of paving sand is one alternative that can be applied SBE utilization. The research was expected to outcome formulation and determines the best type of material in paving blocks manufacture. The process began by mixing all ingredients, forming and compaction. Compaction method used in this research was conducted manually. The best mixing formulation was obtained by performing some variation of materials usages, such as sand and SBE 0, SBE1 and RSBE. Comparisons of percentage concentration between SBE 0/SBE 1/RSBE and sand were (0% : 100%), (20% : 80%), (40% : 60%), (60% : 40%), (80% : 20%) and (100% : 0%). Paving blocks formulation of A1B1 (20% SBE 0 : 80% sand) was the best formulation obtained in this study. It was proven by the value of compressive strength of 15:34 MPa, water absorption of 2.66 % and there was no defect in the testing of its resistance to sodium sulfate and thermal conductivity value of 0.5882 (W/mK).
Keyword: Formulation, Paving block, Spent bleaching earth

Judul: Bifurkasi Hopf pada Model Siklus Bisnis Kaldor Kalecki tanpa dan dengan Waktu Tunda
Abstrak: Business cycle model is one of dynamical system models in economic. One of the business cycles model is Kaldor-Kalecki model. Kaldor-Kalecki business cycle model that is written in delayed defferential equations, is a business cycle model that involves gross product and capital stock of a company. In this paper Kaldor-Kalecki business cycle model is analyzed using both nondelay and delay in time of capital stock. By Taylor expansion for the time delayed model, an analysis of stability around the fixed points has been done. Furthermore, by using Hopf bifurcation theorem, it can be shown that there exists periodic orbits and limit cycle. In the nondelayed model, changing the parameter of goods market could lead to the occurrence of Hopf bifurcation and the existence of limit cycle. Similarly, for the delayed model, it has been shown that changing the time delay parameter may result in the occurrence of Hopf bifurcation and limit cycle.
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