Abstract: The cemented paste backfill (CPB) technology provides a safe, green and efficient access to deep underground mining and sustainable exploitation of mineral resources, and it has become one of the research focuses and development trends in the mining field. The CPB technology mainly includes four key processes, namely, the thickening of unclassified tailings, homogeneous mixing of multi-scale materials, pipeline transportation of fresh CPB, and its consolidation in the mined-out underground stopes. As a relatively new material that is comprised of various constituents, typically the tailings, cement, and water, as well as a high solid concentration, CPB tends to show complicated behaviors under the effects of surroundings. Therefore, understanding CPB behaviors is of practical significance for the development of the technology, since knowledge of CPB behavior is essential in the preliminary backfill system design and operation. It has been pointed out that the use of solid-liquid two-phase flows shows some limitations for the paste. In comparison, the rheology which targets on the flow and deformation of the paste under the influence of external shearing can provide a theoretical basis for the whole processes of paste backfill technology and deeply affect its development. Based on the characteristics of the paste materials, the necessity, particularity and complexity of the research on paste rheology were systematically discussed. Typical rheological properties of paste and the latest achievements were analyzed with the summarized results from rheological experiments. The commonly used rheological models of yielding non-Newtonian fluids were reviewed, and the applicability of corresponding constitutive equations to paste slurry was discussed with reasonable suggestions provided for its practical application. Meanwhile, the key influence factors of paste rheological properties were summarized. According to the research status, the priorities and difficulties of research on paste rheology were summarized and proposed, with emphases on test standards, constitutive equations, microscopic mechanisms and engineering applications.
Abstract: As vehicle ownership increases, the trend lightweight design puts energy consumption and environmental concerns on automotive steel. The research concept of the third generation of automotive steel currently under development is to combine the addition of lightweight elements with “light” and improve plasticization with “thin”. Some of the research hotspots are Fe?Mn?Al?C medium Mn steels as the main component of the third generation of automotive steel. This paper summarized the research literature of Fe?Mn?Al?C steels in recent years in different countries, and discussed the advantages of Fe?Mn?Al?C medium Mn steels in terms of production cost and mechanical properties; the mechanical properties of that is not worse or even better than the second generation of advanced high-strength automotive steel such as TWIP steel can be obtained under the premise of cost savings. The literature was reviewed from the aspects of composition design, process design, microstructure characteristics, deformation and fracture mechanism, and the effect on the efficiency of chemical composition, process route, and microstructure on performance was summarized. It proposed a reasonable range of chemical elements especially Mn and Al, and compared the focus of the two different process routes (Intercritical annealing and quenching + Tempering). The deformation mechanism of medium Mn steel, especially transformation-induced plasticity (TRIP) effect, and the stacking fault energy and austenite stability were identified, in particular, the factors affecting the austenite stability such as grains size, grain morphology and chemical elements were described, and the three-stage work hardening behavior that often occurs in Fe?Mn?Al?C steels was explained. Furthermore, the literature proposed suggestions on regulating the organization of Fe?Mn?Al?C steels by studying the fracture mechanism of materials. Typically the initiation of cleavage cracks is linked to the process of coarse δ-ferrite and κ* phase. Finally, this paper summarized the controversial issues in Fe?Mn?Al?C medium Mn steels research and prospected the future development trend, to provide a reference for the follow-up research and actual production of medium Mn steels.
Abstract: Hydration and setting time of paste-like backfill slurry in the Gansu Province’s Jinchuan copper and nickel mine is slow, and the degree of segregation of coarse aggregate is high, seriously affecting the quality of cemented paste backfill. In this paper, by taking the unclassified tailings, waste rock and rod milling sand in Jinchuan’s No. 2 mining area as the experimental materials, and adopting the comprehensive test design method, the effects of different mass fraction, coarse aggregates and tailings-coarse aggregate ratio (mass ratio of unclassified tailings to coarse aggregate) on the setting performance, unconfined compressive strength and rheological properties of cemented paste backfill were studied. The experimental results show that the coarse aggregate's specific surface area and chemical composition (active MgO and CaO) in the unclassified tailings-coarse aggregate paste are the main factors influencing the setting time. Increasing the tailings-coarse aggregate ratio decreased the setting time of the paste backfill theory. Increasing the tailings-coarse aggregate ratio increased the yield stress of paste backfill slurry. With the increase in the tailings-coarse aggregate ratio, the plastic viscosity of paste backfill slurry (unclassified tailings-waste rock, unclassified tailings-waste rock-rod milling sand paste) increased. The unconfined compressive strength of the unclassified tailings-waste rock paste is better than that of the unclassified tailings-waste rock-rod milling sand paste. The shortest setting time and the best unconfined compressive strength (the unclassified tailings-waste rock paste, tailings-coarse aggregate ratio 5∶5) were reduced by 2.1 h, individually. They were also increased by more than 33% relative to the setting time, and unconfined compressive strength of the mine. Finally, the setting performance was optimized for single-objective and multi-objective regression. The multi-objective regression optimization showed that optimum setting time for the unclassified tailings-waste rock-rod milling sand paste was approximately 270 to 300 min, while for the unclassified tailings waste rock rod milling sand was approximately 10∶6∶6–10∶7∶7 and yield stress was about 167.0 to 169.0 Pa. The optimum setting time of the unclassified tailings-rod milling sand paste was found to be about 300–330 min for the single-objective regression, the unclassified tailings rod milling sand was approximately 10∶14–10∶16, and yield stress was about 164.0–167.0 Pa, which met the mine production requirements.
Abstract: The exploitation of refractory iron ores has become increasingly important around the world because of the rapid depletion of easy-to-process iron ores. Ironsand is extensively distributed in the coastal areas of Indonesia, China, and New Zealand, and can provide an alternative to conventional iron ores. Although the composition of ironsand is partially dependent on its location and position, it approximates that of titanomagnetite (Fe3-xTixO4) containing ~ 60% total Fe (TFe). However, the conventional smelting route for smelting beach titanomagnetite concentrate with carbon uses a blast furnace to produce pig iron and titanium slag, which has many disadvantages. First, the smelting process requires lots of coke and a high temperature. Second, sinter blend allows for the addition of only a small amount of beach titanomagnetite concentrate to ensure the desired sintering characteristics. Therefore, in order to efficiently utilize beach titanomagnetite, the processes of direct reduction followed by magnetic separation are generally applied to recover iron. In addition, additives such as CaO, CaCO3, and NaCO3 are often used in the reduction roasting process. These additives may improve the reduction characteristics or facilitate the growth of iron particles to some extent. In order to study the effect of the additive CaO on the direct reduction and magnetic separation of beach titanomagnetite concentrate which contains 58.58% of TFe and 12.04% of TiO2, the mechanisms were investigated by gas composition of CO and CO2, gasification rate of total reaction, CO partial pressure, metallization rate, mineral composition and so on. The results indicate that adding CaO can improve the gasification rate of reductant and facilitate the reduction of titanomagnetite, which improves the generation of CO2 gas and decreases the CO partial pressure. Besides, CaO can participate in solid-solid reaction, reduce FeO content in Ti-containing mineral and facilitate the migration and enrichment of Ti and Fe components, which promote the growth of metallic iron particles. Thus, adding CaO is good for the separation and recovery of Fe and Ti by grinding and magnetic separation.
Abstract: Interstitial-free (IF) steel is widely used in the automobile industry, home appliance industry, etc. Not only very low content of carbon and nitrogen, but also high quality surface of the final product are required for this steel grade. The contents of oxygen and inclusions in the steel have a great influence on the surface quality of the final product. Therefore, it is very important to decrease the carbon content effectively and keep high steel cleanliness at the same time in industrial production. In present work, the effect of oxygen blowing on the cleanliness of IF steel under the forced decarburization by oxygen blowing in the Ruhrstahl Hereaeus (RH) refining process was studied through dense sampling during RH and continuous casting process, and inclusion analysis was carried out with automatic scanning electron microscopy (ASPEX). Oxygen blowing was found to have little effect on the inclusions’ types and morphology throughout the process. The oxygen blowing rate had a great influence on the cleanliness of the molten steel in the early stage of RH refining (within 4 min after adding Al). An increase in the oxygen blowing rate led to an increase in the content of total oxygen (T.O) and the amount of inclusions in the steel, but it had little effect on the steel cleanliness in the subsequent process. Cluster inclusions were mainly found before the vacuum was broken, and finding them in steel after RH refining was difficult. The steel cleanliness in a tundish had little correlation with the oxygen blowing rate during RH treatment, but had a great correlation with the oxygen content in the molten steel before Al deoxidation. The higher the oxygen content before Al deoxidation, the worse the steel cleanliness in the tundish. To improve the cleanliness in the tundish, the oxygen content in molten steel before Al addition should be decreased as much as possible. The T.O and the inclusions amount in the steel showed a downward trend as the production proceeded, which indicates that the steel cleanliness was gradually improved.
Abstract: Several common models for carbon prediction were discussed based on an off-gas analysis of the basic oxygen furnace (BOF) process, and the basic principles, advantages and disadvantages of three exponential decay models with different correction algorithm were analyzed respectively. An improved exponential model of “critical carbon content fitting + update curves simultaneously” algorithm was established by combining the advantages of previous algorithms. Firstly, the historical decarburization curve in the end blowing stage and the critical carbon content in the bath were obtained by exponentially fitting the decarburization data of historical heats. Secondly, the reference decarburization curve was obtained by replacing the corresponding parameter of the historical decarburization curve with the maximum specific decarburization rate in the middle blowing stage of the real-time heat. Subsequently, the specific decarburization rates of the historical decarburization curve and the reference decarburization curve were converted to dimensionless values within the range of 0 to 1 by normalizing. Then, a multi-point correction method was used to correct the calculation results of the carbon content in the bath and repeatedly modify the key parameters of the calculated decarburization curve, according to the deviation of the removed carbon amount between the normalized reference curve and the actual process. The key parameters of the calculated and the reference decarburization curves were updated simultaneously after each calculation step, and the calculation error of the carbon content prediction decreased gradually through iterative calculation. Finally, the carbon content in the bath were precisely predicted in the end blowing stage of the BOF process. Plant trials were carried out in a BOF converter to demonstrate the performance of the proposed models. The results show that the new model exhibits better adaptability and higher accuracy than the other ones. The hit ratio of the new model to predict the end-point carbon content reaches 90% within a tolerance of ±0.02%.
Abstract: Due to moisture in the ore, auxiliary material, and ladle refractory material, the hydrogen element is easily enriched in molten steel. In the metallurgy process, some hydrogen atoms form bubbles and are removed by gravity, whearas others solidify in the strand and remain in the produced steel. When the hydrogen content reaches a certain critical value, the enriched hydrogen atoms congregate to produce a white spot, which greatly reduces the strength and toughness of the steel product, and leads to brittle fracture during its service period. At present, the RH (Ruhrstahl–Heraeus) and VD (vacuum degasser) refining processes are commonly applied in steel plants, which can reduce the hydrogen content to less than 2×10?6. With the demand for high quality steel, the hydrogen content must be further decreased, so hydrogen diffusion in solid steel during the annealing process is gradually attracting increasing attention. In this study, a two-dimensional model was built to investigate the characteristic of dehydrogenation in the bloom annealing process of rail steel. Moreover, the effect of annealing temperature and annealing time on hydrogen diffusion were analyzed, and the annealing parameters were optimized. During the dehydrogenation annealing process, the hydrogen content at the corners and edges of the bloom are found to decrease rapidly, while that in the center of the strand begin to decrease in the later heating stage. As the annealing temperature increases, the starting point of dehydrogenation in the bloom center moves ahead and the maximum dehydrogenation rate increases significantly. With the extension of the soaking period, the central hydrogen content of bloom decreases significantly, but the increase rate of the dehydrogenation gradually decreases. By optimizing the bloom annealing parameters, the hydrogen content in the bloom can be steadily reduced to 0.6×10?6, which fully meets the requirement of high quality steel production.
Abstract: Chambersite (Mn3B7O13Cl) is both a rare inorganic macromolecular manganese chloroborate and a rare mineral. The chambersite deposit was firstly discovered in Jixian, Tianjin, China, which is the only mineable chambersite deposit in the world. Due to its unique multi-element composition and structure type, it has great application potential as a light-emitting material in biological anti-virus, anti-tumor, and anti-microbial applications, as well as a nuclear-protection and LED applications. However, as yet there are few reports on the material science of chambersite. Rare-earth and transition-group ion-activated borate are important constituent systems in luminescent materials. In this paper, nano-chambersite and rare-earth-element Eu3+-doped nano-chambersite were successfully synthesized by Sol-Gel method. The crystal structure of the nano-chambersite was characterized by X-ray diffraction, transmission electron microscopy, and high-resolution transmission electron microscopy. The performance comparison between natural chambersite and synthetic chambersite was provided to provide a basis for the rational development and utilization of chambersite. The results show that the artificially synthesized chambersite has a spherical shape with a particle size of less than 50 nm, and has the same phase structure as natural chambersite. It belongs to the orthorhombic system and has a structure similar to that of spinel. The inter planar spacing of (010) is 0.8565 nm. Under 490 nm excitation light, the natural chambersite, artificially synthesized chambersite, and rare-earth-element Eu3+-doped chambersite crystal all showed a Mn2+ emitting center. The Mn2+ that filled the center of the tetrahedral lattice site of the crystal exhibited a green emission, whereas the Mn2+ that filled the center of the octahedral lattice site of the crystal exhibited a red emission. The artificially synthesized chambersite showed a unique red shift of the emission spectrum with increases in the emitting-light wavelength. This unique phenomenon is beneficial to the conversion of cold and warm luminescence. Eu3+ doping in the artificially synthesized chamversite further increased the intensity of the luminescence.
Abstract: A two-step reduction method was used to synthesize nano tungsten powder via carbothermic pre-reduction of tungsten oxide, followed by a deep hydrogen reduction. In this process, carbon black first reduced most of the oxygen in tungsten trioxide, while the residual oxygen was removed by hydrogen reduction. The tungsten powder prepared by the two-step reduction method had a spherical shape with an average grain size of 90 nm. Simultaneously, tungsten powders doped with 1% and 2% alumina (mass fraction) were similarly prepared to study the effect of alumina on its sintering behavior. Analysis of fracture morphologies and average grain size of sintered samples showed that alumina significantly inhibited grain growth at the final sintering stage and grain size decreased at the same sintering temperature with an increase in the alumina content. At 1600 ℃, the average grain size of sintered sample of pure tungsten was approximately 2.75 μm, but it was about 1.5 μm for the sintered samples doped with 1% and 2% alumina. This finding could be based on the fact that tungsten grain growth in the final stage of sintering can be effectively inhibited by alumina particles. The sintered pure tungsten powder and alumina doped tungsten powders had different hardness variation levels with temperature increase. The hardness of the sintered sample doped with alumina has always increased with temperature increases, reaching a maximum value above 800 HV. As for the sintered sample of pure tungsten, the hardness first increased and then decreased with temperature increase, reached its maximum value of 473.6 HV at 1400 °C that was caused by the rapid growth of grain size of tungsten at higher temperatures. At a sintering temperature of 1600 ℃, the relative density of the pure tungsten powder was 98.52%, while that of the tungsten powder doped with 1% and 2% alumina were 95.43% and 93.5%, respectively.
Abstract: The rise in the price of petroleum coke and needle coke, which are used as anode materials of lithium-ion batteries, has revealed the difficulty of the industry in finding high-performance and low-cost alternatives of these raw materials. In this study, anthracite, a low-cost, high-quality raw material, of which China is rich in resources, was used. After a 2800 °C purification and graphitization treatment, the anode material for lithium battery was prepared. Petroleum coke, as the precursor of commercial graphite, was treated using the same method that was being used for graphitized anthracite, for comparison reasons. The microstructure of anthracite-based anode materials was characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy (Roman), and nitrogen adsorption-desorption. Cyclic voltammetry (CV) was used to characterize the electrochemical performance of anthracite-based anode materials by applying constant current charge and discharge (GCD). The experimental results show that the graphitization degree of anthracite-based graphitized anode material can reach 95.44%, with the specific surface area being 1.1319 m2·g?1, and the graphite sheet structure is found to be smooth. The graphitized anthracite, as the anode material of a lithium-ion battery, has a first coulombic efficiency of 87% and a reversible capacity of 345.3 mA·h·g?1 at a current rate of 0.1C, and the material has better lithium storage performance than graphitized petroleum coke material at a high rate. The relatively highly ordered surface structure of graphitized anthracite leads to a better storage performance of lithium. When the current rate returns to 0.1C after different current rates, the capacity has basically no attenuation. After 100 cycles, the reversible capacity retention rate is as high as 93.8%, which is basically equivalent to the rate of graphitized petroleum coke anode while the graphitized anthracite also shows excellent cycle stability. Anthracite-based graphite is equivalent or even superior to graphitized petroleum coke in terms of capacity, rate performance, and cycle stability. This study shows that the use of high-quality anthracite as raw material for the production of lithium-ion battery anode materials has a potential research value and broad commercial prospects.
Abstract: In recent years, many accidents caused by alternating current (AC) corrosion have been reported. AC corrosion has become a serious potential damage to buried steel pipelines. The X100 pipeline steel is a very promising material for long-distance gas pipelines, and Korla soil is a typical saline-alkali soil of West China. The coarse-grained heat-affected zone (CGHAZ) and the intercritically reheated coarse-grained heat-affected zone (ICCGHAZ) were simulated by a Gleeble thermomechanical processing machine through different thermal cycle times, peak temperatures, and cooling rates. Electrochemical corrosion measurements, immersion experiments and surface analysis techniques were used to characterize the corrosion behavior of the base metal, CGHAZ, and ICCGHAZ of the X100 pipeline steel in simulated Korla soil solution under AC interference. The X100 pipeline steel base metal, CGHAZ, and ICCGHAZ exhibited active dissolution in the simulated Korla soil solution under AC interference, and the average corrosion rate increased with the increase in AC density. The amplitude of the polarization potential oscillation caused by AC interference and the microstructure had an important influence on the corrosion rate and corrosion morphology of the X100 pipeline steel base metal, CGHAZ and ICCGHAZ. Under the interference of 5 mA·cm?2 AC density, the X100 pipeline steel base material shows the most negative corrosion potential and the largest average corrosion rate, while the ICCGHAZ shows the most positive corrosion potential and the smallest average corrosion rate. Under the interferences of 20 and 50 mA·cm?2 AC densities, the ICCGHAZ of X100 pipeline steel shows the most negative corrosion potential and the largest average corrosion rate, while the base metal shows the most positive corrosion potential and the smallest average corrosion rate. Under the interference of 20 mA·cm?2 AC density, the X100 pipeline steel is locally corroded. CGHAZ and ICCGHAZ have obvious grain boundary corrosion, whereby GCHAZ grain boundary corrosion morphology is slit-shaped, and ICCGHAZ grain boundary corrosion morphology is continuous pores.
Abstract: Hot-work die steels are widely used to meet the requirements of industrial applications in which the steels must endure high temperature and mechanical loads, such as the hot stamping of very-high-strength steel. In the field of hot-stamping technology applications, the tool materials must have excellent high-temperature performance, such as the high-temperature stability of the microstructure. Research on hot-stamping die materials began somewhat late in China because high-quality die steel products had typically been imported. A new type of hot-stamping die steel with high thermal conductivity and high wear resistance was developed to meet the requirements of hot-stamping technology. In this study, we used scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to determine the high-temperature tempering performance and microstructural characteristics of this new Mo?W?V alloyed hot-work die steel. Based on the results, we derived the precipitation and evolvement rules of the carbides in the new type hot-stamping die steel during the tempering process, which indicate that the new Mo?W?V alloyed test steel has an excellent secondary hardening property. We find the hardness of the microstructure to increase after tempering at 500 ℃–600 ℃; however, at tempering temperatures above 600 °C, the matrix obviously softens and the hardness of the test-steel microstructure decreases. The hardness of the test die steel is strongly linked to the segregation, precipitation and growth of the alloy carbides in the matrix. No alloy carbide precipitation is observed at tempering temperatures below 560 ℃; however, M2C-type carbide precipitation is observed at tempering temperatures higher than 560 ℃. MC-type alloy carbide is observed in the test-steel matrix at tempering temperatures up to 600 ℃. At tempering temperatures above 620 ℃, the M2C-type alloy carbides transform into M6C-type alloy carbides and the hardness curve of the test steel sharply declines. The MC-type and M6C-type alloy carbides are the main carbides in the matrix of the new Mo?W?V alloyed hot-work die steel.
Abstract: It is well known that large-sized nonmetallic inclusion seriously affects the mechanical properties of high-strength steels, particularly the fatigue properties. Therefore, significant efforts have been made to enhance the fatigue properties of gear steels by improving the cleanliness and, thus, reducing the size and the number of inclusions in steels. However, an effective inclusion inspection method is particularly important because of the relatively low-rate emergence of large-sized inclusions in highly clean steels. Herein, a new inclusion inspection strategy was proposed using a properly hydrogen-charged tensile specimen combined with the application of the statistics of extreme value (SEV) method, which can be used to conveniently and reliably estimate the maximum inclusion size in any volume of high-strength steel and its fatigue strength. A commercial heat of 20Cr2Ni4A gear steel with high cleanliness was used to verify the proposed method. Standard tensile specimens were quenched, tempered at low-temperature, and then properly charged with electrochemical hydrogen. It is found that there were many embrittled platforms, generally with large inclusions on the fracture surfaces of the specimens after normal tensile testing because of the trapping of the charged hydrogen around inclusion and the occurrence of hydrogen embrittlement. The size, composition, and distribution of these inclusions can be analyzed using a scanning electron microscopy, thus, the maximum inclusion size can be predicted using the SEV method. To verify the accuracy of the proposed method, additional inclusion rating methods of conventional optical metallographic observation and high-cycle fatigue testing were conducted. Using the proposed method, it was confirmed that the predicted maximum inclusion size and fatigue strength are consistent with that obtained via the rotating bending fatigue test. Therefore, the proposed method is a promising, efficient, and reliable for use in high-strength steels with high cleanliness to inspect the maximum size inclusion and predict fatigue strength.
Abstract: The conventional method of PM2.5 prediction requires high-precision instruments to obtain data on the concentration of pollutants, resulting in a high prediction costs. In this work, we attempt to use image data to estimate PM2.5 concentration. The concentration of atmospheric PM2.5 is closely linked to the image’s dark channel intensity, contrast, and color difference of HSI. The increase in atmospheric PM2.5 concentration leads to a decrease in the non-sky area dark channel intensity, image contrast, and HSI spatial color difference. In this paper, a Column-Generation PM2.5 prediction model based on image mixture kernel was proposed by analyzing the relationship between PM2.5 and image features. First, the sampling period was taken as 1 h, and 8:00–17:00 was taken as the sampling range daily. The scene images were recorded in different weather conditions, and five image features were extracted, including contrast, dark channel intensity, and HSI color difference. Secondly, the image data has the characteristics of large sample size and uneven distribution, and the prediction model consists of a single kernel function, which makes it difficult to meet the prediction accuracy requirement. Therefore, the linear kernel function, polynomial kernel function, and Gauss kernel function were chosen to construct a composite model according to the concept of kernel structure from simple to complex. Then each kernel's Gram matrix was calculated based on training samples, and all gram matrices were placed into a mixture kernel matrix. Using the column generation algorithm and mixture kernel matrix, the prediction model was developed and the parameters of the model were solved. Finally, simulation experiments were performed; the results show that the prediction model based on the image mixture kernel of Column-Generation PM2.5 can meet the prediction accuracy requirements. The model has higher prediction accuracy and better model stability in comparison with the single-kernel prediction model. A computational complexity analysis shows that the prediction model based on the image mixture kernel of column-generation PM2.5 has no significant increase in computational complexity in comparison with the one-kernel prediction model.
Abstract: With the rapid growth in the number of intelligent terminal devices and wireless multimedia applications, mobile communication traffic has exploded. The latest report from Cisco Visual Networking Index (CVNI) indicates that by 2022, global mobile data traffic will have grown to three times that in 2017, which will exert tremendous pressure on the backhaul link. One key approach to solve this problem is to cache popular content at the edges (base stations and mobile devices) and then bring the requested content from the edges close to the user, instead of obtaining the requested content from the content server through backhaul networks. Thus, by obtaining the required content of mobile users locally, edge caching can effectively improve network performance and reduce the pressure on the backhaul link. However, owing to the limited storage capacity of the edge nodes and the diversification of user requirements, the edge nodes can neither cache all the content in the content server nor randomly cache the content. To solve these problems, an edge-caching mechanism based on user-awareness was proposed. First, using an implicit semantic model, we predicted popular content in a macro cell in terms of the users’ interests. Small base stations within identical macro cells cache data cooperatively, which update local popular content based on the dynamic content preference of users. To further reduce the delay in content delivery, we helped users to ascertain their top communities of interest based on their content preferences. At the same time, the most appropriate user equipment (UE) is selected considering the caching willingness and caching ability to cache data for other UEs in identical communities of interest. Results show that the proposed mechanism outperforms the random cache approach and the most popular content-caching algorithm; it improves the cache hit rate and reduces the transmission delay while enhancing the quality of user experience.
Monthly, started in 1955 Supervising institution：Ministry of Education Sponsoring Institution：University of Science and Technology Beijing Editorial office：Editorial Department of Chinese Journal of Engineering Publisher：Science Press Chairperson：Ren-shu Yang Editor-in-Chief：Ai-xiang Wu ISSN 2095-9389CN 2095-9389
