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"Oversize"
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Optimizing key parameters for grinding energy efficiency and modeling of particle size distribution in a stirred ball mill
Fine grinding using a stirred ball mill can enhance ore liberation but incurs high energy consumption, which can be minimized by optimizing operating conditions. This study explores the impact of key operational parameters—grinding time, stirrer tip speed, solid concentration, and feed size—on grinding efficiency, evaluated using specific energy inputs, in stirred milling of Egyptian copper ore. The particle size distribution (PSD) of ground products was simulated using the Gates–Gaudin-Schuhmann model (GGS) and the Rosin-Rammler-Benne (RRB) function. Taking minimum energy consumption into account, the finest particles (100% ~1 μm) were achieved at the maximum stirrer speed of 500 rpm and a moderate solid concentration of 33.3% after 17 h of grinding, consuming approximately 1225 kWh/t. Experimental data demonstrated a linear correlation between the natural logarithm of the cumulative retained fraction and particle size (µm). The proposed model accurately describes PSDs across different solid concentrations and grinding durations.
Journal Article
Ethan out and about
In four brief stories, Ethan feeds birds, squirrels, and ants, chases a cat, and rides bikes with his Dad.
Book
Automated Prototype for Bombyx mori Cocoon Sorting Attempts to Improve Silk Quality and Production Efficiency through Multi-Step Approach and Machine Learning Algorithms
Cocoon sorting is one of the most labor-demanding activities required both at the end of the agricultural production and before the industrial reeling process to obtain an excellent silk quality. In view of the possible relaunch of European sericulture, the automatization of this production step is mandatory both to reduce silk costs and to standardize fiber quality. The described research starts from this criticality in silk production (the manual labor required to divide cocoons into different quality classes) to identify amelioration solutions. To this aim, the automation of this activity was proposed, and a first prototype was designed and built. This machinery is based on the use of three cameras and imaging algorithms identifying the shape and size of the cocoons and outside stains, a custom-made light sensor and an AI model to discard dead cocoons. The current efficiency of the machine is about 80 cocoons per minute. In general, the amelioration obtained through this research involves both the application of traditional sensors/techniques to an unusual product and the design of a dedicated sensor for the identification of dead/alive pupae inside the silk cocoons. A general picture of the overall efficiency of the new cocoon-sorting prototype is also outlined.
Journal Article
Bridges : a history of the world's most spectacular spans
Examines historical and contemporary bridges, including Ponte Vecchio in Florence, Pont Neuf in Paris, Brooklyn Bridge in New York, Sydney Harbor Bridge in Australia, and Tsing Ma Bridge in Hong Kong.
Book
Effect of flow rate in minimum quantity lubrication (MQL) in micro-drilling of Ti-6Al-4V
Minimum quantity lubrication (MQL) is an environment-friendly alternative to traditional flood cooling techniques and has great potential to be successful in micro-machining. The current research work aims toinvestigate the influence of MQL flow rates (6, 50, and 100 ml/h) and cutting parameters such as spindle speed and feed on various micro-drilling characteristics of Ti-6Al-4 V. Thrust force, specific cutting energy, and hole surface roughness were found to be lower under the MQL flow rate of 6 ml/h as compared to higher flow rates. An increase in the MQL flow rate from 6 to 100 ml/h at a spindle speed of 30,000 rpm resulted in a maximum of 40% increase in the thrust force. The surface roughness and oversize error increased by a maximum of up to 162 and 66%, respectively, under a similar change in the MQL parameters. The flow rate of 100 ml/h exhibited inferior micro-drilling characteristics primarily owing to its inability to effectively penetrate the narrow machining zone. Material adhesion under the MQL environment increased with an increase in cutting velocity due to the rise in the cutting temperature. The phenomenon of the “size effect” was evident under the lowest feed of 1 µm/rev owing to the regime of rubbing and ploughing. Elevation of feed effectively promoted shear deformation in micro-drilling. Overall, the present study highlighted the superiority of the lowest flow rate of 6 ml/h owing to effective atomization during micro-machining under the MQL environment.
Journal Article
Where's the artist? : from cave paintings to modern art : a look and find book
This book opens up entire historic periods to young readers in double page spreads that are teeming with life and drawn to teach them about artistic traditions. Each spread represents a moment in history, capturing how art was integrated into daily life and illustrating contemporary styles, tools, and mediums. Children will learn about cave paintings and what humans used for light and why they painted so many animals and hunting scenes. They'll find themselves in Ancient Greece, where deities watch over a busy marketplace in front of the Parthenon. A cross-section of a medieval monastery, Leonardo's workshop, and a collection of 19th-century artists painting in nature are just a few more of the examples, which take readers through to the present day.
Book
Optimization of Multimodal Paths for Oversize and Heavyweight Cargo under Different Carbon Pricing Policies
With the increasing global concern over climate change, reducing greenhouse gas emissions has become a universal goal for governments and enterprises. For oversize and heavyweight cargo (OHC) transportation, multimodal transportation has become widely adopted. However, this mode inevitably generates carbon emissions, making research into effective emission reduction strategies essential for achieving low-carbon economic development. This study investigates the optimization of multimodal transportation paths for OHC (OMTP-OHC), considering various direct carbon pricing policies and develops models for these paths under the ordinary scenario—defined as scenarios without any carbon pricing policies—and two carbon pricing policy scenarios, namely the emission trading scheme (ETS) policy and the carbon tax policy, to identify the most cost-effective solutions. An enhanced genetic algorithm incorporating elite strategy and catastrophe theory is employed to solve the models under the three scenarios. Subsequently, we examine the impact of ETS policy price fluctuations, carbon quota factors, and different carbon tax levels on decision-making through a case study, confirming the feasibility of the proposed model and algorithm. The findings indicate that the proposed algorithm effectively addresses this problem. Moreover, the algorithm demonstrates a small impact of ETS policy price fluctuations on outcomes and a slightly low sensitivity to carbon quota factors. This may be attributed to the relatively low ETS policy prices and the characteristics of OHC, where transportation and modification costs are significantly higher than carbon emission costs. Additionally, a comparative analysis of the two carbon pricing policies demonstrates the varying intensities of emission reductions in multimodal transportation, with the ranking of carbon emission reduction intensity as follows: upper-intermediate level of carbon tax > intermediate level of carbon tax > lower-intermediate level of carbon tax = ETS policy > the ordinary scenario. The emission reduction at the lower-intermediate carbon tax level (USD 8.40/t) matches that of the ETS policy at 30%, with a 49.59% greater reduction at the intermediate level (USD 50.48/t) compared to the ordinary scenario, and a 70.07% reduction at the upper-intermediate level (USD 91.14/t). The model and algorithm proposed in this study can provide scientific and technical support to realize the low-carbonization of the multimodal transportation for OHC. The findings of this study also provide scientific evidence for understanding the situation of multimodal transportation for OHC under China’s ETS policy and its performance under different carbon tax levels in China and other regions. This also contributes to achieving the goal of low-carbon economic development.
Journal Article
Parameters affecting the quality of friction drilled holes and formed thread in austenitic stainless steel AISI 304
The main purpose of this research paper is to improve the quality of the friction-drilled holes and formed thread by investigating the influence of the input working parameters that have not been investigated yet on the quality of the produced bores. Due to lack of research related to the hardness macro- and microstructure of formed threads, experiments were conducted to investigate these important issues. Finally, a tension test was performed to compare the performance of the form tapped thread with the conventionally cut thread. The experiments were conducted on difficult-to-cut material AISI 304 stainless steel workpieces with (2 and 3 mm) wall thicknesses. Tungsten carbide friction drills with diameters (Ø9.2, Ø7.3, and Ø4.5 mm) were used to perform the experiments. The effects of the ratio of workpiece thickness (t) to tool diameter (dT), rotational speed (N), and feed speed (f) on the hole diametral oversize (U), cylindricity error, and collar height were studied. The analysis of variance (ANOVA) showed that the t/d ratio was the most significant factor affecting the mean cylindricity error and the collar height. By comparing the performance of the three tools, it was noticeable that the friction drill Ø7.3 realized better results in terms of mean hole diametral oversize and mean cylindricity error. The elevated temperature associated with high plastic deformation during the processes resulting in fine grains with high hardness values were observed at the heat-affected zone. The longer effective thread length of the formed thread realized higher strength values than the cut thread.
Journal Article
A Comprehensive Set of Cooling Measures for the Overall Control and Reduction of High Temperature-Induced Thermal Damage in Oversize Deep Mines: A Case Study
The mining process in deep mines occurs at elevated temperatures and thus is significantly jeopardized by the thermal damage. In this study, the main factors causing high-temperatures under particular mining geological and prevailing conditions of coal mine production, namely for the Longgu Coal Mine (LCM) in Shandong Province of China, were specified and analyzed in detail. This included exothermic heat from the surrounding rock of an underground roadway, inflow of high-temperature water, seasonal temperature rise, mechanical and electrical equipment operation, and airflow compression in the mine. The integrated artificial cooling mode was implemented on the basis of the original normal ventilation and cooling facilities of the LCM, which involved cooling by mobile refrigeration units, water source heat pump refrigeration units, and a ground centralized ice-cooling radiation system, as well as the underground centralized cooling system provided by Wärme-Austausch-Technik (WAT) GmbH. Eventually, a comprehensive set of measures for the overall control and reduction of high-temperature-induced damage was realized, which ensured more effective cooling of the LCM. Thus, the average temperature of the main operation sites was reduced by 8 K, while that of the underground working faces was maintained at 299.15 K. These measures also resulted in excellent technical and economic benefits: the total three-year increase in revenue and savings reached 76.3 million USD, hence relevant findings of the study are expected to provide technical guidance on the treatment of high-temperature-induced damage in deep mines.
Journal Article