Judul: The Effect of Woven Patterns on Flexural Behaviour of Textile Reinforced Concrete (TRC) with Ramie Fiber Reinforcement
Abstrak: Kebutuhan terhadap beton telah meningkat di Indonesia. Salah satu inovasi beton yang sedang dikembangkan adalah Textile Reinforced Concrete (TRC). Serat rami memiliki potensi untuk digunakan sebagai perkuatan TRC karena memiliki kekuatan tarik yang cukup tinggi. Penelitian bertujuan menganalisis perilaku lentur TRC dengan perkuatan serat rami. Penelitian dilaksanakan pada bulan Februari hingga Juni 2021 di IPB. Penelitian dilakukan melalui beberapa tahapan, yaitu pengujian material, mix design, penganyaman dan pelapisan serat rami, pembuatan dan perawatan benda uji, dan pengujian. Perilaku lentur TRC yang dianalisis, di antaranya kuat lentur, kekakuan, daktilitas, dan perilaku retak. Perkuatan serat rami dapat meningkatkan daktilitas dan menurunkan kekakuan pelat mortar. Akan tetapi, anyaman serat rami dengan pola anyaman tertentu dapat menurunkan kuat lentur. Pelapisan Unsaturated Polyester Resin (UPR) memberikan peningkatan kuat lentur dan daktilitas serta penurunan kekakuan pada TRC. Perilaku retak TRC serat rami terlapisi UPR mengalami beberapa fase, yaitu uncracked concrete, crack formation, crack stabilization, dan failure. Pola anyaman yang menghasilkan kuat lentur tertinggi adalah pola anyaman dua sumbu yang terlapisi UPR, sebesar 7.84 MPa., The demand of concrete has increased in Indonesia. A reinforced concrete innovation being developed is Textile Reinforced Concrete (TRC). Ramie fiber has great potential to be used as a construction material because it has advantages over other natural fibers, such as tensile strength properties. The research aims to analyzed flexural behaviour of Ramie fiber TRC. This research was conducted from February until June 2021 at IPB University. The research was carried out through several stages, that are testing of TRC materials, mix design, weaving and coating ramie fiber, manufacturing and curing test objects, and testing. The flexural behavior analyzed flexural strength, stiffness, ductility, and crack behavior. Ramie fiber reinforcement can improve ductility and reduce stiffness of mortar plates. However, woven ramie fiber with a certain woven pattern can reduce flexural strength. Coating ramie fiber with Unsaturated Polyester Resin (UPR) provides an increase in flexural strength and ductility but decrease in stiffness. Phases of crack behaviour of UPR-coated are uncracked, crack formation, crack stabilization, and failure. The woven pattern that produces the highest flexural strength is the two-axis woven pattern for UPR-coated ramie, which is 7.84 MPa.
Keyword: concrete, flexural behaviour, ramie fiber, textile reinforced concrete

Judul: Characteristic of Rigid Polyurethane Foam Composite in Various Fiber Content of Ramie Stem (Boehmeria nivea (L.) Gaud)
Abstrak: Serat batang rami merupakan material berlignoselulosa yang dapat dijadikan sebagai filler produk komposit rigid polyurethane foam (RPUF). Penelitian ini bertujuan menganalisis pengaruh kandungan serat batang rami terhadap karakteristik komposit RPUF. Pengujian reaktivitas RPUF mengacu pada Soberi et al. (2017). Pengujian sifat fisis (kerapatan, kadar air, daya serap air, dan pengembangan tebal) mengacu pada standar JIS A 5908-2003. Pengujian sifat mekanis (MOE, MOR, dan keteguhan rekat) mengacu pada standar ASTM D790 dan JIS A 5908-2003. Hasil penelitian ini menunjukkan bahwa penambahan serat batang rami mampu menurunkan reaktivitas RPUF. Semakin tinggi kandungan serat batang rami, maka sifat fisis dan mekanis yang semakin menurun kualitasnya. Namun, penambahan serat batang rami tidak berpengaruh nyata secara statistik terhadap kerapatan, MOE, dan MOR. Kadar air, daya serap air, dan pengembangan tebal RPUF semakin meningkat seiring meningkatnya kandungan serat. Selain itu, keteguhan rekatnya semakin meningkat hingga kadar 7,5%., Ramie stem fiber is a lignocellulosic material that can be used as filler in rigid polyurethane foam (RPUF) composite. This study aims to analyze the effect of ramie stem fiber content on the characteristics of RPUF composite. The RPUF reactivity test refers to Soberi et al. (2017). The physical test (density, moisture content, water absorption, and thickness swelling) refers to JIS A 5908-2003. The mechanical test (MOE, MOR, and internal bond) refers to ASTM D790 and JIS A 5908-2003. The results of this study indicate that the addition of ramie stem fiber can reduce RPUF reactivity. The higher content of ramie stem fiber tends to cause lower physical and mechanical properties. However, content of ramie stem fiber had no statistically significant effect on density, MOE, and MOR. The moisture content, water absorption, and thickness of the RPUF increase when fiber content increases. In addition, internal bond was increasing up to a level of 7.5%.
Keyword: composite, ramie stem, rigid polyurethane foam, isocyanate, polyol

Judul: Dynamical System of Hepatitis B in Three Groups with Vaccination
Abstrak: The aim of this study is to modify the hepatitis B transmission model in three age groups involving vaccination from the model conducted by Zhoe and Zhang.The method used is to analyze the stability of the fixed point and its basic reproduction number (R_0). Performed stability analysis and numerical simulation to see population dynamics. Next, a sensitivity analysis of the parameters was carried out to see its effect on R_0. From the analysis obtained two fixed points, namely non-endemic and endemic fixed points. Non-endemic fixed points are locally asymptotically stable if R_0 <1 Meanwhile, the endemic fixed point is locally asymptotically stable if R_0 > 1. Hepatitis vaccination affects the number of susceptible population, because the more successful the vaccination, the smaller the number of susceptible populations so that the smaller the population will be infected.
Keyword: Dynamic, Hepatitis B, Vaccine, Mathematical model