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2. Chemical Composition and Morphological Characterization of Enset (E. ventricosum) Leaf Residues for Paper Pulping Production: Kraft Pulping
- Author
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Melesse, Emiru Yidnekachew, primary and Asrat, Zelelam Belay, additional
- Published
- 2022
- Full Text
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3. Study of the Mechanical Properties of Sugar Cane Fiber for Packaging Paper Based on Polyacrylamide and Natural Fibers
- Author
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Danielle Ferreira dos Santos and Artur Junger Vasconcelos
- Subjects
General Engineering - Abstract
Natural fibers have been extensively studied as a reinforcement filler in obtaining composites, replacing partially synthetic fibers. The vast majority of these materials originate from agro-industrial waste with a high content of lignin and cellulose making it a very interesting material with low cost and good mechanical properties. The purpose of the study was to obtain a composite based on alkyl ketene dimer resin, for the manufacture of sustainable packaging, made of paper by adding a 10% (w/w) con-tent of green coconut fiber and sugarcane bagasse fiber, and evaluated the impact of the filler on the mechanical behavior of the systems. The studied material was characterized from mechanical tests, such as Ring Crush Test (RCT) and Concora Medium Test (CMT) evaluating the maximum resistance supported by centimeter in the pre-pared composites, by the specimens. Through the RCT tests, with 10% w/w fibers, it was possible to verify that the fiber from sugarcane bagasse reached an increase of about 1% in the reinforcement effect compared to pure paper, and a difference of up to 2% in strength mechanics in relation to coir fiber, and CMT tests shows the reinforcement effect of the presence of sugarcane bagasse fiber, with an increase of about 3% compared to pure paper, and with a mechanical strength higher by 1% compared to coconut fiber. Therefore, the study was funneled with sugar cane fiber, varying the content by 20 and 30 % (w/w), evaluating the impact on the dispersion of this filler in the polymeric matrix and, consequently, the mechanical response of the composite with these compositions. The conclusion of the study was that the system prepared with 20% (w/w) was the one that achieved the greatest optimization of the mechanical properties, evaluated by the tests. This type of material can be applied to obtain cardboard boxes with resistance to high loads, due to the achievement of good mechanical properties.
- Published
- 2022
4. Chemical Composition and Morphological Characterization of Enset (E. ventricosum) Leaf Residues for Paper Pulping Production: Kraft Pulping
- Author
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Emiru Yidnekachew Melesse and Zelelam Belay Asrat
- Subjects
General Engineering - Abstract
Currently, paper pulping production from woody materials has many disadvantages due to its high energy, chemical, water consumption, methane emissions, and deforestation. However, the use of non-woody materials solves these problems. This study focused on the use of non-virgin raw material (Enset leaf fiber) in pulp and paper making. Enset leaf residues are the primary solid residues after the steam plant is used for “Kocho” processing. This leaf fiber has a lignocellulose component, converting this residue into Pulp and paper is crucial in terms of economic and waste management via the Kraft process. It has a higher fiber quality, lower energy consumption, and high recoverability of the chemical raw materials used in the process. The chemical composition of the Enset leaf fiber was analyzed using the Technical Association of Pulp and Paper. It has an excellent fiber length (2.12±1.46mm), fiber diameter (26.55±15.6µm) andacceptable rigidity coefficient (1.05±0.07), and flexibility coefficient (125.23±0.04). The maximum pulp yield was obtained at a temperature of 120°C, NaOH concentration of 8%, and 40 min cooking time off, which was 69.92% w/w. The functional groups of the Enset leaf fiber and morphological characteristics of the fiber were investigated.
- Published
- 2022
5. Principles of Logic Design with Nanoscale Thin Film Memristive Systems for High Performance Digital Circuit Applications
- Author
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Chakraverty, Mayank and Ramakrishnan, V.N.
- Abstract
The characteristic pinched hysteresis behavior of memristors has been reported by stacks of a variety of materials. This paper aims to examine the principles of logic design using such two terminal memristive systems for high performance digital circuit applications. As against logic design with standard CMOS, the benefits of logic design with memristors have been stated. The realization and operation of memristor based AND and OR hybrid logic gates obtained by integrating memristors with standard CMOS logic have been discussed. The IMPLY and MAGIC logic families have been demonstrated by covering MAGIC NOR and NAND logic gate implementation with MAGIC NOR in detail. A qualitative comparison has been drawn towards the end of the paper to conclude on the suitability and application space for each of the logic families studied in this paper. This work also describes the hybrid CMOS-memristive logic family known as MRL (Memristor Ratioed Logic). With the addition of CMOS inverters, this logic family's OR and AND logic gates, which are based on memristive components, are given a full logic structure and signal restoration. The MRL family, in contrast to earlier memristor-based logic families, is compatible with conventional CMOS logic.
- Published
- 2023
- Full Text
- View/download PDF
6. Effect of Alloying Elements on Strengthening Phase and Solidification Structure of Ti-Al-Mo-Zr Titanium Alloy
- Author
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Tang, Jin Jun, Liang, Cui, Xu, Chen Guang, and Li, Ji Qiang
- Abstract
This paper mainly studies the composition of strengthening phase, characteristic precipitation temperature and composition range of strengthening phase in Ti-Al-Mo-Zr-Si medical titanium alloy, and the influence of element changes on the content and microstructure of strengthening phase. Promote the formulation of thermodynamic process of titanium alloy powder metallurgy, as well as the formulation of alloy hot working and solid solution aging process. In this paper, Panda thermodynamic software is used to calculate the multicomponent alloy thermodynamics and multicomponent phase diagram of titanium alloy materials. The effects of Al, Mo, Zr, Si and other elements on the precipitation of strengthening phase and the phase transformation content of solidification structure were obtained. It is found that the content of Mo is more than 2 wt.% β phase transition precipitation angle. Meanwhile, in order to avoid the excess of precipitates such as Mo5Si3 and M3Si, the content of Mo should be less than 4.6 wt.%. The content of Zr can be maintained at about 1.5 wt.%. If the aging precipitation of the material is considered, it can be controlled to be less than 2 wt.%. The content of this paper is the basis and improvement of titanium powder metallurgy technology and rapid prototyping technology.
- Published
- 2022
- Full Text
- View/download PDF
7. Simulation of Thermal Field in Eutectic Microwave Bonding for Electrical Connection of Photovoltaic Cells
- Author
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Ghelsingher, Cristian Daniel, Marin, Robert Cristian, Ştefan, Iulian, Sîrbu, Nicușor-Alin, Savu, Ionel Dănuț, David, Andrej, Savu, Sorin Vasile, and Olei, Adrian Bebe
- Abstract
Sustainable development requires green energy and low carbon footprint in manufacturing sector of photovoltaic systems. The electrical connections of photovoltaic cells need to have low electrical resistance in order to reduce the electrical losses and therefore to improve the performance of the photovoltaic panels. This paper aims to present researches related to bonding of wires that connect solar cells by using microwave technology. The microwave bonding has the main advantage that offers fast bonding but, in the same time, this technology does not offer stability of the thermal heating. Two different unwanted phenomena like thermal runaway and plasma arc discharge often lead to the damaging of copper and aluminum wires used in electrical connection. The study presented in this paper is focused on simulation of the thermal field developed in copper wires in order to optimize the bonding process and increase the quality of products. The simulation of the thermal field has been done using Fourier equations for conducting heating in copper materials and eutectic alloys. The simulation model has been validated through experimental heating using a 6 kW water-cooled microwave generator controlled by a matching load auto-tuner for best transfer of the power from generator to copper wires. The temperature has been measured in real time using an infrared pyrometer for metals with 2.3 μm spectral range and measurement range between 0o C and 7000 C. The study is finalized with elaboration of mathematical model for microwave-injected power as function for temperature developed in copper wires that can be applied with success in further microwave bonding applications of copper wires. In addition, the electrical resistance of bonded wires was measured in order to collect feedback for improving the microwave bonding process.
- Published
- 2022
- Full Text
- View/download PDF
8. Estimation of Durability Benchmark on Concrete Samples Using Artificial Intelligence
- Author
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Guzmán-Torres, José Alberto
- Abstract
This paper proposes a deep learning model for predicting the durability benchmark on concrete specimens. The durability benchmark on concrete samples is commonly estimated throughout the Ultrasonic Pulse Velocity measurements. This test establishes a relationship with concrete durability taken into consideration the material's homogeneity. The model proposed in this paper is feed by standard laboratory tests as input parameters, making the model a practical and efficient alternative to predict durability concrete benchmark, saving time, short-cut laboratory work, and avoiding sophisticated instrumentation use. Furthermore, it is an attractive alternative to the need for sophisticated instrumentation for estimating the Ultrasonic Pulse Velocity. The outcomes depict a high predictive accuracy about of 96% in the validation stage. In addition, the model was tested by a new dataset with different properties to demonstrate robustness and certainty in the model. Finally, the model achieves an impressive accuracy of 95.89% in the new validation dataset.
- Published
- 2022
- Full Text
- View/download PDF
9. Computer Modelling of Influence of Crystal Lattice Friction Stress on the Dislocation Annihilation Process
- Author
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Borysovska, Kateryna
- Abstract
In this paper the effect of lattice friction stress on the process of dislocations annihilation is considered using dislocation dynamics method. It is shown that if dislocations of the opposite sign are located in the area where their own tension is greater than the friction stress, they annihilate. Consideration of this fact allows to connect the microscopic processes of annihilation with evolution of dislocation density in the sample under small external stresses and unloading. The area in which annihilation occurs is calculated to be proportional to the square of the friction stress/shear modulus ratio.It is also shown that the parameter responsible for the rate of dislocation annihilation depends on the cube of the ratio of the friction stress to the shear modulus, because it is inversely proportional to the number of annihilating dislocations and the time in which a dislocation pair annihilates.
- Published
- 2023
- Full Text
- View/download PDF
10. Impact of Sodium Tripolyphosphate on the Rheological Properties of Dams Sediments and Friction Factor during Hydraulic Dredging of Dams
- Author
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Lakhache, Brahim, Hammadi, Larbi, and Gaidi, Laouni
- Abstract
The transporting of sediments across watershed systems and their placement in reservoirs causes expensive issues for the operators of dams in many different nations throughout the world. In addition to the reservoir's functional capacity steadily decreasing as sediment settles in it, silt removal is a sensitive and challenging process that frequently necessitates taking the reservoir out of service, which is practically unachievable in dry and semi-arid regions. De-silting by hydraulic dredging has recently become a necessity to increase their longevity. But during this operation there are load loss exists so it is necessary to find solutions to reduce it. The present paper revealed that use the Sodium Tripolyphosphate as a reducing agent of the friction factor during the hydraulic dredging of dams. To carry out this study, a rheumatic characterization of dams sediments and dams sediments -sodium tripolyphosphate mixtures was carried out using a torque controlled rheometer (Discovery Hybrid Rheometer DHR2 from TA instrument). The flow curves as a function of dose of sodium tripolyphosphate added to dam sediments were analysed by the modified Cross model. It is clearly shown, in this work, when the quantity of sodium tripolyphosphate is less than of 0.4 % causes a decrease in the yield stress, the zero shear rate viscosity (lower Newtonian plateau) and the infinite shear rate viscosity (upper Newtonian plateau). However, when dose of sodium tripolyphosphate is greater than the critical dose, the the yield stress, the zero shear rate viscosity (lower Newtonian plateau) and the infinite shear rate viscosity (upper Newtonian plateau) are increased. As a result, this study find that the increase on thixotropic behavior of dams sediments is occurred by the addition of sodium tripolyphosphate in a concentration ranging between 0.2 wt% and 0.8 wt% to 40 wt% and 45 wt% of dams sediments. The study also demonstrated that adding of 0.4 wt% of sodium tripolyphosphate to 40 wt% and 45 wt% dam sediments decreased the friction factor by 96% and 25% respectively.
- Published
- 2023
- Full Text
- View/download PDF
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