Biến đổi cấu trúc và tính chất của vật liệu compozit polyetylen tỷ trọng cao/bột gỗ gia cường bởi hạt nano TiO2 sau thử nghiệm gia tốc thời tiết

In this study, the composites based on high density polyethylene (HDPE) and wood flour (WF) in the presence of PEgMA compatibilizer and TiO2 nanoparticles (in rutile crystal form) were investigated the accelerated weathering test. After 1.900 hours testing, tensile strength of HDPE/WF composite using PEgMA reduced siginificantly (remaining value of 55.98 %). Whereas, the mechanical properties of the HDPE/PEgMA/WF composites slightly decreased thanks to the presence of TiO2 nanoparticles, the retention of tensile strength of composite using TiO2 of 3 wt.% is 81.89 %. Calculating from Fourier transform infrared (FT-IR) spectra showed that the carbonyl index (CI) and wood index (WI) of composites without TiO2 were higher than that of composites containing TiO2. Besides, the discoloration of HDPE/PEgMA/WF composite could lead to lightening on the surface, in fact, this occurs clearly in the case of composites containg TiO2 in comparison with the sample without it. It may imply that TiO2 nanoparticles played a role as the degrading inhibitors of composites under UV irradiation. In addition, observation from the SEM images, the surface of HDPE/PegMA/WF/TiO2 composites was detroyed less than that of composites without TiO2

Việt Bắc trái tim hồng. t.I

756 tr. ; 4c cm

Việt Bắc trái tim hồng. t.II

702 tr. ; 4c cm

Mô phỏng một số thí nghiệm điện trên máy vi tính

93 tr. ; 30 c

Mô phỏng một số thí nghiệm điện trên máy vi tính : tóm tắt

28 tr. ; 21 c

Researching on Application of Multiple Objective Differential Evolution Algorithm to Solve Time-cost Trade Off Problems in Construction Projects

Along with quality criteria, time and cost are two crucial factors playing an important role in the success of a construction project. However, a number of current construction projects are related with the limitation of the budget or financial source. In construction industry, reducing the implementation time of the project without increasing the budget will be considerably beneficial for the owners. Therefore, trade-off optimization between time and cost is essential for the improvement of benefit of construction projects. This study presents a novel optimization model named Multiple Objective Differential Evolution (MODE) algorithm to deal with the time-cost trade-off problems. A numerical case study of an apartment project is used to illustrate the application of MODE. The research result shows that non-dominated solutions generated by MODE assist project managers in choosing appropriate plans. In addition, the sufficiency of the proposed optimization algorithm, MODE, is verified by comparing the solutions of this model with those of other commonly-used optimization algorithm including Non-dominated Sorting Genetic Algorithm (NSGA-II), Multiple Objective Particle Swarm Optimization (MOPSO)

Vật lý đại cương A1

161 tr. ; 31 cm

Hệ số Hilbert và độ sâu của vành phân bậc liên kết

Trong bài báo này, chúng tôi thiết lập một đẳng thức về mối quan hệ giữa hệ số Hilbert và độ sâu của vành phân bậc liên kết ứng với iđêan tham số sinh bởi một d-dã