Vibration Damping of Carbon Nanotube Assembly Materials

Vibration reduction is of great importance in various engineering applications, and a material that exhibits good vibration damping along with high strength and modulus has become more and more vital. Owing to the superior mechanical property of carbon nanotube (CNT), new types of vibration damping material can be developed. This paper presents recent advancements, including our progresses, in the development of high-damping macroscopic CNT assembly materials, such as forests, gels, films, and fibers. In these assemblies, structural deformation of CNTs, zipping and unzipping at CNT connection nodes, strengthening and welding of the nodes, and sliding between CNTs or CNT bundles are playing important roles in determining the viscoelasticity, and elasticity as well. Towards the damping enhancement, strategies for micro-structure and interface design are also discussed

Pengembangan Media Pembelajaran Fisika Berupa Buletin Dalam Bentuk Buku Saku Untuk Pembelajaran Fisikakelas VIII Materi Gaya Ditinjau Dari Minat Baca Siswa

Tujuan dari penelitian ini untuk mengembangkan media pembelajaran berupa buletin dalam bentuk buku saku untuk pembelajaran Fisika kelas VIII pada materi Gaya ditinjau dari aspek materi, konstruk, dan bahasa serta minat baca siswa. Penelitian ini termasuk penelitian pengembangan yang menggunakan metode Research and Development (R&D). Penelitian ini menggunakan model pengembangan model prosedural yaitu model yang bersifat deskriptif yang menunjukkan tahapan-tahapan yang harus diikuti untuk menghasilkan produk berupa media pembelajaran.Jenis data yang diperoleh bersifat kualitatif dan kuantitatif yaitu angket dan wawancara. Teknik analisis data yang digunakan adalah analisis deskriptif kualitatif dan kuantitatif. Hasil penelitian menunjukkan bahwa media pembelajaran yang dikembangkan berupa buletin Fisika dalam bentuk buku saku memiliki kriteria sangat baik berdasarkan penilaian dari ahli materi, ahli bahasa Indonesia, dan ahli media memberikan rata-rata penilaian sebesar 86,56%. Media pembelajaran yang dikembangkan juga memiliki kriteria sangat baik bila ditinjau dari peningkatan minat baca siswa. Hal ini terbukti pada hasil angket minat baca awal dan akhir yang diberikan kepada siswa yang memberikan rata-rata peningkatan sebesar 11,13%. Selain itu juga dianalisis dengan menggunakan uji-t berpasangan terhadap data masing-masing kelompok uji coba untuk mengetahui signifikansi dari peningkatan minat baca siswa. Untuk uji coba perorangan diperoleh hasil perhitungan thitung = 6,957 > ttabel = 1,943 dan nilai Sig. = 0,001 < 0,05 yang berarti sangat signifikan. Untuk kelompok kecil didapatkan hasil perhitungan bahwa thitung = 7,848 > ttabel = 1,725 dan nilai Sig. = 0,000 < 0,05 yang berarti sangat signifikan. Untuk kelompok besar juga didapatkan hasil perhitungan bahwa thitung = 20,214 > ttabel = 1,725 dan nilai Sig. = 0,000 < 0,05 yang berarti sangat signifikan. Simpulan dari penelitian ini adalah media pembelajaran berupa buletin dalam bentuk buku saku memiliki kriteria sangat baik bila ditinjau dari aspek materi, konstruk, dan bahasa serta minat baca siswa

Extending Focal Depth of Flower-Shaped Optical Vortex with Composited Spiral Zone Plate Grating

By combining a spiral zone plate (SZP) and a grating, we propose a single optical element, termed a composited spiral zone plate grating (CSZPG), to generate flower mode vortices with the equicohesive petals and has long focal depths. Theoretical analysis reveals that the CSZPG can generate flower mode vortices with approximately equicohesive petals, and that it has longer focal depths compared with the conventional SZP. Moreover, the performance of the CSZPG on the period, focal length and radius is investigated. The experimental results are also presented, agreeing well with the theoretical predictions. The unique characteristics of the proposed CSZPG make it attractive for many applications such as particle trapping and optical imaging

Optimized Surfactant IFT and Polymer Viscosity for Surfactant-Polymer Flooding in Heterogeneous Formations

Surfactant Polymer flooding (SP flooding) has drawn more attention than Alkaline Surfactant Polymer flooding (ASP flooding) in China due to the difficulty of demulsification and the scale formation problem from the alkali in ASP. Traditionally, the primary requirement for the surfactant in SP flooding is the lowest interfacial tension (IFT). However, core flooding tests performed in a series of heterogeneous models have demonstrated there exist optimized surfactant IFT and polymer viscosity for SP flooding, which can maximize the oil recovery of a heterogeneous formation. The optimized surfactant IFT has a low value but not the lowest possible value, and polymer viscosity is at an appropriately high value, but not the highest possible value. This paper summarizes and analyzes more than 40 core flooding test results and provides possible mechanisms for the results

A Study on the Morphology of a Dispersed Particle Gel Used as a Profile Control Agent for Improved Oil Recovery

To achieve in-depth profile control of injection water and improve oil recovery, a new profile control agent, termed as dispersed particle gel (DPG), has been developed and reported. In this paper, the morphology of DPG and the factors that influence its morphology are systematically investigated using atomic force microscopy (AFM). The AFM studies show that DPG is composed of small pseudospherical particles and that their sizes can be controlled by adjusting the shearing rate, the initial polymer mass concentration, and the salinity. Dynamic light scattering (DLS) is used to study the effects of the initial polymer mass concentration, the shearing rate, the salinity, and the high-temperature aging on the particle size of DPG. The aggregation ability of DPG is explained using the DLVO theory and space stability theory. This work provides a scientific basis and technical support for the formula design of DPG and its application in the oil and gas field

Phase transformation and microstructure of in-situ concrete after 20-year exposure to harsh mining environment: A case study

The phase transformations and microstructural properties of a drilled cylinder specimen from a C40 concrete dam used for mining wastewater disposal were evaluated in this study, covering a span of up to 20 years. Various analysis methods, including PT, ICP-MS, XRD, FTIR, TGA, MIP, and SEM-EDS, were employed to assess the performance of powder samples obtained through layer-by-layer grinding. The results obtained from XRD, FTIR, and TGA analyses indicated that the presence of calcite in all ground powder samples, suggesting that carbonation can occur in all layers, even including the inner layers. Moreover, the MIP and SEM-EDS results illustrated that the microstructural properties of the concrete could be influenced by phase transformations induced by various ions present in the mining wastewater, resulting in increased porosity and looser interfacial transition zones (ITZs) in the sample closer to the outer layer. The PT results confirmed the penetration of chloride into the concrete, although the relative chloride content decreased with the increasing depth of the layers. It was observed through TGA analysis that a portion of the chloride ions could attribute to the formation of Friedel’s salts, derived from ettringite or calcium aluminate monosulfate. Additionally, SEM-EDS examination revealed that some chloride ions could bind to the C-S-H gels. The presence of different ions, particularly magnesium ions in the mining wastewater could lead to decalcification of the hydrated gels. These research findings provide significant support for the safety assessment of the concrete structure exposed to mining environments

Enhanced Oil Production Through a Combined Application of Gel Treatment and Surfactant Huff\u27n\u27puff Technology

Surfactant huff-puff for production wells has become a recent interest, especially for extremely heterogeneous reservoirs. However, injected surfactant will preferentially move into fractures in fractured reservoirs or higher permeability zones in unfractured reservoirs and will bypass much of the reservoir. In addition, the surfactant will be produced immediately after the production well resumes to production, so the soaking time is limited. This paper introduces a novel process which couples gel treatment and surfactant huff-puff in one EOR process in which surfactant solution is first injected into the production well, then followed by gel treatment. The proposed method has been applied for 10 production wells in a polymer flooding unit in Daqing oilfield. The best compatible surfactant and gel were screened out for the given reservoir conditions before the field application. The mechanisms of the proposed method were studied using core flooding experiments. The field application design process is presented and the application results have been analyzed. Application results show pressure drawdown test can be an important criterion to select candidate for the combined method