9,317 research outputs found
A novel probabilistic data association based MIMO detector using joint detection of consecutive symbol vectors
No full textA new probabilistic data association (PDA) approach is proposed for symbol detection in spatial multiplexing multiple-input multiple-output (MIMO) systems. By designing a joint detection (JD) structure for consecutive symbol vectors in the same transmit burst, more a priori information is exploited when updating the estimated posterior marginal probabilities for each symbol per iteration. Therefore the proposed PDA detector (denoted as PDA-JD detector) outperforms the conventional PDA detectors in the context of correlated input bit streams. Moreover, the conventional PDA detectors are shown to be a special case of the PDA-JD detector. Simulations and analyses are given to demonstrate the effectiveness of the new method
Effects of mixing procedures on properties of compatibilized polypropylene/nylon 6 blends
No full textThis paper considers the effects of compatibilization with maleic anhydride grafted polypropylene (PP-g-MAH) on the properties of immiscible blends of polypropylene (PP) and nylon 6 (N6). We prepared the blends by three different mixing processes; single-step blending, two-step blending with reactive premixing, and two-step blending with nonreactive premixing, to determine the effective mixing process for fine morphological structure, thermal stability, and mechanical properties. Dynamic melt theological properties were measured to examine the modification of elastic properties by the compatibilizer. In addition, thermal analysis was also carried out to detect the change in-crystallization and thereby to probe the degree of compatibilization. The results show that compatibilized blends prepared by the single-step process exhibit improved phase morphology, thermal stability, and mechanical properties for dried conditions, compared with other blend types. Finally, the water absorption test indicates that the added compatibilizer yields enhanced water resistance in spite of the strong intrinsic hydrophilicity of N6. In particular, two-step blending with reactive premixing is most effective in improving water resistance and reducing degradation of mechanical properties after moisture absorption
Rheo-optical behaviors and stability of a silica particle suspension coated with silane coupling agents
No full textThe rheo-optical behaviors and suspension stability of silica particles coated with silane coupling agents were investigated experimentally. Mono-dispersed silica particles were synthesized by the sol-gel method and the particles were coated with silane coupling agents such as vinyltriethoxy silane (VTES) and gamma-methacryloxypropyl triethoxy silane (MPTES). Although all the suspensions of identical particle volume fraction exhibited similar rheological behaviors at high shear rates, only the stabilized suspensions coated with either VTES or MPTES displayed smooth shear thinning rather than abrupt change in the shear viscosity, as is typical of suspensions with no surface treatment. The present study showed that the MPTES coating was very effective in enhancing the phase stability compared to the VTES coating. The flow-induced dichroism for the MPTES-coated suspensions did not experience sign change, while those of the non-stabilized suspensions changed sign as the shear rate was increased. The VTES-coated suspensions underwent a transition from a stable to an unstable state as the particle volume fraction increased. Specifically, the rheological behaviors of the VTES-coated suspensions of particle volume fraction 0.35 were similar to those of the MPTES-coated suspensions. When the volume fraction exceeded 0.45, however, the effect of VTES coating diminished. Finally, the stress-optical rule proposed by Bender and Wagner was adopted to model the stabilized suspensions considered here. The present results indicated that the stress-optical coefficient could be predicted successfully by the proposed stress-optical rule if the contribution from the hydrodynamic interaction is considered separately from the thermodynamic contribution. (C) 1998 Academic Press.This work has been supported by the Korea Science and Engineering
Foundation under Grant KOSEF 951-1105-1-011-2
Mechanical and Rheological Properties of Compatibilized Blends of Polypropylene and Nylon
No full textEffects of mixing procedures on properties of compatibilized polypropylene-nylon 6 blends
No full textPreparation of silica-based hybrid materials coated on polypropylene film
No full textIn this study, silica-based organic-inorganic hybrid coating materials were prepared by the sol-gel method. Tertaethoxysilane and polyvinyl alcohol were used as the inorganic and organic compounds, respectively. The substrate polypropylene film surface was modified by corona-plasma treatment to provide appropriate adhesion between the coating material and the polymer base film. A silane-coupling agent of vinyltriethoxysilane was also used to improve the adhesion between the base film and the coated layer. The effects of vinyltriethoxysilane in the hybrid materials were investigated using Fourier transform infrared analyses and X-ray diffraction. The vinyl group of vinyltriethoxysilane increased the hydrophobicity of the hybrid materials. The polypropylene films coated with the hybrid materials were characterized by examining their morphology, optical transparency and oxygen permeability. The results showed that the formation of hydrogen bonds between polyvinyl alcohol and the other compounds affected the microstructure of the coating solution and the final oxygen permeation property. Further, although the presence of vinyltriethoxysilane in the hybrid coating solution could improve adhesion between the coated layer and the polymer base film, it deteriorates the effectiveness of the barrier to prevent of oxygen permeation through the coated film. However, the coated film maintained visible transparency and even enhanced the transmission of long wavelength visible-light owing to refractive index matching. (C) 1999 Kluwer Academic Publishers.This work was supported by the Korea Science and Engineering
Foundation (KOSEF) under grant 971-1109-
058-2. Honam Petrochemical Research Center kindly
provided the PP base films and corona-plasma facility
and the R&D Center of SK Corp. helped us to measure
gas permeability. The authors appreciate their support
A probabilistic data association based MIMO detector using joint detection of consecutive symbol vectors
No full textA new probabilistic data association (PDA) approach is proposed for symbol detection in spatial multiplexing multiple-input multiple-output (MIMO) systems. By designing a joint detection (JD) structure for consecutive symbol vectors in the same transmit burst, more a priori information is exploited when updating the estimated posterior marginal probabilities for each symbol per iteration. Therefore the proposed PDA detector (denoted as PDA-JD detector) outperforms the conventional PDA detectors in the context of correlated input bit streams. Moreover, the conventional PDA detectors are shown to be a special case of the PDA-JD detector. Simulations and analyses are given to demonstrate the effectiveness of the new method
PERAN WORK ENGAGEMENT TERHADAP HASIL KINERJA YANG BAIK BISNIS MAHASISWA IBM-RC MENGGUNAKAN JD-R MODEL
No full textPenelitian ini bertujuan untuk mempraktikkan kegunaan JD-R model sebagai alat pengukuran keterlibatan mahasiswa dalam engagement tugas dalam bisnis. Adapun latar belakang dari penulisan ini adalah Universitas Ciputra merupakan Universitas yang dikenal sebagai penerap entrepreneurship yang mana diharapkan menciptakan lulusan entrepreneur berkelas dunia. Walaupun penerapan entrepreneurship di Universitas Ciputra sudah baik, namun hal tersebut tidak menutup kemungkinan bahwa setiap bisnis yang sedang didirikan mahasiswa mengalami masalah dalam pengimplementasiannya. Masalah-masalah tersebut meliputi: operasional bisnis tidak mencapai satu tahun, pembagian tugas tidak spesifik, performa individu tidak sesuai target. JD-R Model merupakan teori kembangan Bakker yang ditujukan agar mencari tahu mengenai indikasi apa saja yang dapat membantu karyawan agar dapat engage terhadap pekerjaan yang sudah menjadi kewajibannya. Penelitian ini dilakukan dengan Structural Equation Modeling (SEM) menggunakan AMOS 22 terhadap mahasiswa Universitas Ciputra Angkatan 2016 IBM-RC. Dari penelitian ini, terbukti bahwa mahasiswa Ciputra lebih terpengaruhi Personal Resources agar lebih terlibat dalam pekerjaannya (Work Engagement).
Kata kunci: Keterlibatan Kerja Individu, Model JD-R, Kinerja yang Baik, AMOS 22, mahasiswa Universitas Ciputra
 
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