Number Of Meshes Research Articles

Material Design and Performance Study of a Porous Sound-Absorbing Sound Barrier

A new type of porous sound-absorbing sound barrier was developed with quartz sand and self-developed polysiloxane resin. The forming process of the material was studied. The test specimens of the porous sound-absorbing sound barrier were prepared with different mesh numbers of quartz sand and different proportions of resin, and the void properties, compressive strength, durability, and acoustic performance were investigated. Based on the mix design results, it is suggested that 20-mesh quartz sand and a 10:1 mass ratio of quartz sand are used to prepare the porous sound-absorbing sound barrier. The durability study showed that the porous sound-absorbing sound-barrier material had good salt and alkali resistance, poor acid resistance, good water stability, and freeze–thaw stability. The laboratory acoustic test and practical engineering application results showed that the porous sound-absorbing sound barrier had excellent acoustic performance and good noise-reduction effects.

Hydrodynamic response analysis of the aquaculture net under the combined action of irregular waves and currents

ABSTRACT The hydrodynamic response of fishing nets is crucial in aquaculture. During service, due to severe sea states and collisions with large fish, potentially resulting in net damage. Analyzing this damage is complex due to the large number of net meshes. This study establishes a mathematical model of the net system under wave-current coupling based on the rigid-body kinematics and the lumped-mass method. An analysis was conducted to investigate how various environmental conditions and types of damage affect net deformation and force. Results indicate that maximum force occurs at the connections to the rigid frame and the midpoint of the net. Among various types of net damage, the nodes motion increased exclusively around the periphery of the damaged area, while the netting twine force significantly decreased only in the direction of the damage. Notably, damage to the upper net has the greatest impact on both netting twine force and deformation.

The impact of anodic mesh density and halogen anions on the optical characteristics of gradient refractive index microlens arrays fabricated in chalcohalide glass via microthermal poling

Gradient refractive index microlens arrays (GRIN MLAs), covering the visible to mid-infrared wavelength range, are imprinted in GeS2-Ga2S3-CsX (X = Cl, Br, and I) chalcohalide glasses by an efficient and economical microthermal poling process. This study investigates the impact of anodic mesh number (ranging from 400 to 2000 mesh) and halogen anions on the optical properties, including focal length, resolution, and aberration. Findings reveal that as the mesh number decreases, the focal length and aberration of GRIN MLAs increase. Optimal resolution is achieved with the 500 mesh sample, which also shows the best phase difference performance. The migration depth of Cs+ ions, influenced by halogen anions (from Cl to I), results in contrasting optical properties between lower mesh (400–750) and higher mesh (1000–2000) samples. Notably, the Cl-500 GRIN MLAs demonstrate a focal length of 615.0 μm, a maximum resolution of 6.35 lp/mm, and minimal aberration of −0.0591. These changes are attributed to the predominant transverse and longitudinal migration of Cs+ ions in mesh square areas. This research highlights the relationship between microthermal poling conditions, ion migration, and optical performance, providing valuable insights for the application of GRIN MLAs in advanced optical systems.

Evolution of Oxygen Content of Graphene Oxide for Humidity Sensing.

Graphene oxide (GO) has shown significant potential in humidity sensing. It is well accepted that the oxygen-containing functional groups in GO significantly influence its humidity sensing performance. However, the relationship between the content of these groups and the humidity sensing capability of GO-based sensors remains unclear. In the present work, we investigate the role of oxygen-containing functional groups in the humidity sensing performance by oxidizing graphite with mesh numbers 80-120, 325, and 8000 using the Hummers method, resulting in GO-80, GO-325, and GO-8000. Infrared spectroscopy (IR) and X-ray photoelectron spectroscopy (XPS) were used to identify the types and quantification of oxygen-containing functional groups. Molecular dynamics simulation is used to simulate the adsorption energy, intercalation dynamics, and hydrogen bonding of water molecules. Electrochemical tests were used to compare the adsorption/desorption time and response sensitivity of graphene oxide to humidity. It is proposed that hydroxyl and carboxyl groups are the main contributing groups to humidity sensing. GO-8000 shows a relatively fast response time, but the large number of carboxyl groups will hinder intercalation of water molecules, thus exhibiting lower sensitivity. This research provides a reference for the future development of graphene-based sensors, catalysts, and environmental materials.

Study of Different Parameters on Removal of Methyl Violet Dye Using Coconut Shell Powder as an Adsorbent

The dyeing business is one of the most water- intensive industries. The effluent from the dyeing industry comprises a variety of chemicals and coloring compounds, and it must be properly treated before being dumped into any water body. However, dye house effluents are extremely difficult to treat properly because to their considerable variability in composition. In most cases, a combination of multiple techniques of treatment is required to eliminate all toxins from the wastewater. As a result, adsorption became one of the most efficient ways for removing color from textile effluent. In this paper, an attempt is made to remove the colored ingredient Methyl Violet present in the colored solution by using a cheaply available adsorbent, coconut shell powder of specific size. In this work, the effect of variation in the parameters like dosage of adsorbent, temperature of the solution and initial concentration of the solution are studied and the adsorption removal efficiency is studied through an experimental approach. The adsorbent used is dry coconut shell of size -100 BSS mesh number. The dosage of adsorbent was varied from 10 gms to 50 gms and It was discovered that the adsorption removal efficiency was varying between 72.9 % to 89.6 %. The Additional factors that were examined are effect of temperature on adsorption and effect of initial concentration. The temperatures varying from 500C to 700C. It was determined that the adsorption removal effectiveness of Methyl Violet was found out to be decreasing from 64.6 % at 500C to 47.9 % at 700C. Adsorption efficiency was shown to decrease as temperature increased. The initial adsorbent concentration ranged from 30 to 70 ppm. It was shown that increasing the starting concentration enhanced the adsorption removal effectiveness from 85% to 88%. Based on the results of the preceding experiments, it is possible to infer that coconut shell powder is an efficient adsorbent for removing Methyl Violet from waste water, with an 89.6% removal rate.

Theoretical and experimental analysis of evaporative cooling with hydrophilic screen mesh on condenser surface

In this study, we theoretically and experimentally analyzed the effect of evaporative cooling on the external thermal resistance of a condenser with a water-filled hydrophilic screen mesh. To calculate the external thermal resistance of the condenser theoretically, the external thermal resistance model was developed, considering evaporative cooling in the screen mesh. The evaporative mass flow rate in the screen mesh was calculated using the Lewis number, which can convert heat transfer to mass transfer. Especially, the maximum flow rate absorbed by the screen mesh was theoretically determined by the capillary limit. In experimental approach, hydrophilic screen meshes with mesh numbers M100, M150, and M200 were manufactured and attached to an aluminum plate simulating the condenser surface. The external thermal resistance of the condenser was measured. Based on the results, the theoretical model was well matched with experimental results. The effects of the air velocity, mesh number, and heat flux on the external thermal resistance of the condenser with evaporative cooling in the water-filled hydrophilic screen mesh were investigated. Finally, it is shown that the external thermal resistance of the condenser with evaporative cooling using the water-filled hydrophilic screen mesh can be reduced up to an average of 92 %.

Numerical simulation of the vortex-induced vibrations of a 4:1 rectangular cylinder subjected to yaw uniform currents

The practical engineering structures are not always perpendicular to the wind but often in skew positions. This yawed configuration may lead to more complex three-dimensional flow characteristics and different vortex-induced vibration (VIV) responses. However, the related study is very inadequate. Therefore, comprehensive numerical investigations of the VIV characteristics of a 4:1 rectangular cylinder have been conducted using the three-dimensional (3D) Large-Eddy Simulation (LES) at five different yaw angles (β = 0°, 5°, 10°, 20°, 30°). An innovative method for creating 3D meshes was introduced, demonstrating a good agreement with the experimental results while significantly reducing the mesh number, and consequently the computation time. The VIV response, pressure distribution, aerodynamic force, flow field, and energy input/output were analyzed for various yaw angles. The results demonstrate that the periodic boundary conditions on the spanwise domain side is more reliable than those of the wall boundary conditions. The velocity component parallel to the cylinder axis can be ignored in the analysis of elastically-mounted rectangular rigid cylinders for β up to 30°. If only considering the perpendicular axis velocity component, the amplitudes and lock-in regions for β = 5°, 10°, 20°, and 30° are highly consistent with those of β = 0°, which have effectively validated the accuracy of Independence Principle in evaluating the VIV of a 4:1 rectangular cylinder.

Influence of preparation parameters on rheological properties and relation analysis of waste rubber modified bitumen mastic

Waste rubber modified bitumen has gained significant attention as a sustainable and innovative material in the field of pavement engineering. This study aims to evaluate the performance of rubber modified bitumen mastic by considering its rheological properties, specifically focusing on preparation parameters, i.e., rubber content, mesh number, and filler to bitumen ratio. From the experimental results, the rheological properties of rubber modified bitumen mastic were significantly influenced by preparation parameters. Increasing the rubber powder content in bitumen mastic results in higher viscosity. Increasing the rubber content improves high-temperature rutting resistance to a certain extent, however, excessive rubber powder content would result in weakened high-temperature performance improvement. The rutting factor decreases gradually with an increase in the rubber mesh number. A ratio of filler to bitumen of 0.95 exhibits the best resistance to rutting at high temperatures. Higher rubber content and larger mesh number correspond to stronger low-temperature crack resistance in bitumen mastic. As the ratio of filler to bitumen increases, the low-temperature deformation capacity gradually decreases, resulting in weaker low-temperature crack resistance. Based on the grey relation analysis, the ratio of filler to bitumen has the greatest impact on the high and low-temperature rheological properties of bitumen mastic, followed by the rubber content. The rubber mesh number has a relatively lower impact. It is crucial to control the ratio of filler to bitumen to avoid excessive values. When possible, a higher rubber powder content should be used while meeting process requirements. These findings provide valuable insights into the design and optimization of rubber modified bitumen mastic, which can contribute to the development of sustainable and high-performance bitumen mixtures, promoting the use of recycled rubber in pavement engineering.

Influence of real particle morphology on single particle crushing behavior of rockfill based on FDEM

Particle morphology is critical in affecting the crushing behavior of rockfill materials. In contrast, most current single particle simulations lack satisfactory morphology accuracy, and the resulting crushing modes deviate from observations to some extent. Therefore, we reconstruct the real particle morphology with the spherical harmonic (SH) method and employ the finite-discrete element method (FDEM) to simulate the one-dimensional (1D) compressive crushing process of basalt particles commonly used in rockfill. The influences of four main morphological parameters, i.e. sphericity, aspect ratio, roundness, and convexity, on the single particle strength and the crushing modes are discussed. The results show that with the SH degree set to 15 and a mesh number of 20,480, the FDEM models of reconstructed particles achieve sufficient morphology accuracy and high computational efficiency. Based on the model, the simulation results demonstrate that the aspect ratio has the most significant impact on single particle strength, followed by sphericity. In contrast, roundness and convexity have a weaker effect than the above two parameters. Also, it is revealed that single particle strength decreases with increasing aspect ratio and sphericity, while it increases with higher roundness and convexity. Furthermore, aspect ratio significantly changes the initial crushing position, sphericity dominates post-crushing fragment size and quantity, and roundness mainly affects post-crushing morphology. The model results have been employed in establishing a support vector regression (SVR)-based predicted model, exhibiting good predictive performance and advantages for the optimization of rockfill particles in engineering.

Investigations of Propeller-Rudder Clearance on Propulsion Performance and Flow Field in Vicinity of Propeller

The presence of the propeller affects the hydrodynamics of the rudder in the same way that the ship's hull interferes with the function of the propeller behind and vice versa. Therefore, the arrangement of the propeller and rudder is very important in determining the overall ship propulsion performance. This paper presents a numerical analysis of the KCS propulsion system at various longitudinal clearances with respect to rudder position. The analysis was carried out in a full ship configuration using the KCS hull, propeller and rudder. The propeller clearance was varied based on the existing KCS design, design adjustments and recommendations from DNV respectively by 0.124D, 0.129D and 0.100D. Propeller performance was analysed based on individual variations, interactions between the propeller and rudder, as well as variations in the number of meshes of 0.5 mil, 1.0 mil, and 1.5 mil. The flow distribution around the propeller and the pressure distribution of the rudder inflow onto the rudder surface are also discussed. Numerical examination revealed that DNV's recommended clearance of 0.100D provided the best results and improved KCS propulsion performance compared to existing design. The mesh sensitivity analysis performed revealed that the recommended clearance showed excellent performance in all mesh variations. In response to these findings, modification of the KCS propeller clearance following DNV recommendations would be beneficial to improve overall ship performance.

Burning behavior of hydrogen jet flame inhibited by a wire mesh screen

Hydrogen is recognized as a promising energy source and the potential risks associated with leakage and jet fire accidents should be considered. The objective of this study is to explore the feasibility of utilizing wire mesh to suppress hydrogen jet flames. The experiments of hydrogen jet fire with ignitors below and above the wire mesh were performed to explore the effect of wire mesh on the burning behaviors at different mesh numbers, mesh-to-nozzle distances, and fuel flow rates. Compared to the free jet flame, the length of jet flame under the action of wire mesh is decreased by 50–90 %. The flame with topside ignition fails to pass through the mire mesh due to the cooling effect of the fuel jet. Experimental results reveal that the state of the flow field in the impingement area plays an important role in determining the upper flame height. Both the upper flame height and the flame extension length beneath the screen decrease with mesh-to-nozzle distance. As the mesh porosity decreases, the flame extension length increases, however, the upper flame height decreases. Based on the classical theory of flow resistance through porous media, a new dimensionless model was developed to predict the characteristic flame lengths of the jet flame inhibited by wire mesh. The findings presented in this paper offer fresh insight into the safeguarding of jet fires.

USE OF CATHODE RAY TUBE (CRT) COMPOSITE WASTE GLASS FOR NUCLEAR SHIELD TILES

This research is aimed at producing radiation shield tiles from cathode ray tube waste glass, borosilicate waste glassand soda lime silicate waste glass. The waste glasses were sourced for and crushed to powder. The powder wassieved through a 0.25 mm sieved with mesh number 60 and analysed using XRF spectrometer to ascertain theirchemical constituents. Twenty-one samples were generated using a 21-point triaxial blend of the three wasteglasses. The various samples were poured into moulds, fired in an electric furnace at 1000oC and soaked for anhour. Radiation shielding test using a radioactive source (cobalt 60) was carried out. The radiation shielding testsshows that sample 1 which comprises of 100% CRT had the highest radiation shielding ability with 0.178 cm-1linear attenuation coefficient and sample 21 which is made up of 100% soda lime silicate glass had the leastradiation shielding ability with 0.109 cm-1 linear attenuation coefficient.According to the 49th NCRP report,conventional tiles HVL for 60-Co gamma is 6.2 cm; whereas HVL for the RST in this work ranges between 3.8-6.3cm which shows that the RST is within the range of offering a good radiation protection. The results obtained in thisstudy showed that the radiation shielding tiles developed can be used as wall tiles in nuclear power facilities andmedical X-ray systems.

An experimental and numerical study on two-way RC slabs with openings strengthened by ferrocement technique

This study investigates the impact of creating a central square opening on reinforced concrete slabs and assesses the strengthening process using ferrocement layers. The investigated key parameters were the opening sizes, type, number, and extension length (outside the opening sides) of steel mesh layers used to strengthen the tested slabs. The experimental program included the preparation and testing of twelve two-way reinforced concrete slabs with identical dimensions, thickness, and reinforcement, but were different with respect to opening sizes and strengthening schemes. Four slabs acted as control specimens without strengthening; one was solid; the other three had different opening sizes; and the other eight slabs were strengthened using a ferrocement layer of 2 cm thickness applied on the bottom of the slab around the openings with various reinforcement schemes which included the number, type, and extension length (outside the opening) of steel mesh. All slabs were supported along the four sides with a clear span of 1 m in both directions and tested under four-point loading. The test results demonstrate that creating an opening in the slab decreases the ultimate load by 21.5 %, 31.9 %, and 40.7 % for opening dimensions (15, 25, and 35 cm), respectively. Using the ferrocement strengthening method helps to increase slabs’ flexural load-carrying capacities and reduce crack propagation from opening corners. The study found that strengthening specimens with opening sizes of 15, 25, and 35 cm increased their flexural load-carrying capacities by 26 %, 33 %, and 34 %, respectively. The expanded steel mesh type also resulted in a higher ultimate load by 6–7 % than the welded mesh type. When the length of the strengthening ferrocement layers was doubled, the ultimate load went up by 6–7 %. Increasing steel mesh layer numbers from 1 to 4 increased the ultimate load by 25 % to 40 % compared to the corresponding un-strengthened slab with an opening. The maximum load of a slab with an opening was achieved by applying a 2 cm thickness of ferrocement layer reinforced with expanded metal mesh, with extension lengths equal to the opening's length. The study utilizes commercial software ABAQUS for finite element analysis (FEA) to validate the experimental results, resulting in a great agreement between the analysis and the experimental findings.

Future Possible Changes in Medically Underserved Areas in Japan: A Geographic Information System-Based Simulation Study.

A decrease in populations could affect healthcare access and systems, particularly in medically underserved areas (MUAs) where depopulation is becoming more prevalent. This study aimed to simulate the future population and land areas of MUAs in Japan. This study covered 380,948 1 km meshes, 87,942 clinics, and 8354 hospitals throughout Japan as of 2020. The areas outside a 4 km radius of medical institutions were considered as MUAs, based on the measure of areas in the current Japanese Medical Care Act. Based on the population estimate for a 1 km mesh, the population of mesh numbers of MUAs was predicted for every 10 years from 2020 to 2050 using geographic information system analysis. If the population within a 4 km radius from a medical institution fell below 1000, the institution was operationally assumed to be closed. The number of MUAs was predicted to decrease from 964,310 (0.77% of the total Japanese population) in 2020 to 763,410 (0.75%) by 2050. By 2050, 48,105 meshes (13% of the total meshes in Japan) were predicted to be new MUAs, indicating a 31% increase in MUAs from 2020 to 2050. By 2050, 1601 medical institutions were tentatively estimated to be in close proximity. In Japan, the population of MUAs will decrease, while the land area of MUAs will increase. Such changes may reform rural healthcare policy and systems.

Application of Delaunay adaptive mesh refinement in flood risk assessment of multi-bridge system with short distance

To ensure bridge safety, the flood risk analysis is significant important. However, due to the small size and large number of piers in the short-distance multi-bridge system, the extremely long calculation time and low efficiency of the numerical model are induced by the small mesh size and large mesh number. In this paper, a flood risk assessment model of the multi-bridge system with short distance was established to improve the calculation efficiency based on the finite volume method combined with the Delaunay mesh adaptive refinement method. The calculated water level with refined and non-refined mesh was compared with the experimental data of a partial failure dam break test case and Shukry experiment of open channel bend flow. The calculated water level results are in good agreement with the experimental data. In addition, the mesh refinement model improved the calculation efficiency by more than 73% with ensuring the calculation accuracy. Finally, the flood risk of a real multi-bridge system with short distance was evaluated by using the numerical model. The calculated results shown that, different from the general flow law, the water level in the upstream and downstream channel of Bridge 2 rose with a maximum difference value of 0.326 m while the water level in the far downstream channel of Bridge 2 dropped result from the construction of Bridge 2 on the basis of the Bridges 1, 3 and 4. The construction of Bridge 2 also increased the flow velocity around Bridge 3 with maximum 0.013 m/s. This study provides a new tool and technical reference for flood risk analyses of similar multi-bridge system with short distance.

PVA Hydrogels Supplemented with PLA Mesh for Tissue Regeneration Scaffold.

This study examined the tensile strength and biocompatibility properties of polyvinyl alcohol (PVA) hydrogel tissue regeneration scaffolds with polylactic acid (PLA) mesh fabric added as reinforcement, with a focus on the impact of heat treatment temperature and the number of layers of the PLA mesh fabric. The hydrogel scaffolds were prepared using a freeze-thaw method to create PVA hydrogel, with the PLA mesh fabric placed inside the hydrogel. The swelling ratio of the PVA/PLA hydrogel scaffolds decreased with increasing layer number and heat treatment temperature of the PLA mesh. The gel strength was highest when five layers of PLA mesh fabric were added, heat-treated at 120 °C, and confirmed to be properly placed inside the hydrogel by SEM images. The MTT assay and DAPI staining using HaCaT cells demonstrated that the cell proliferation was uninterrupted throughout the experimental period, confirming the biocompatibility of the scaffold. Therefore, we confirmed the possibility of using PLA mesh fabric as a reinforcement for PVA hydrogel to improve the strength of scaffolds for tissue regeneration, and we confirmed the potential of PLA mesh fabric as a reinforcement for various biomaterials.

Experimental study on abrasive flow finishing of narrow inner cavity of alumina-dispersed copper absorber

Given the difficulties in processing and detecting the narrow and deep inner cavities of the diffusive copper absorber used by the High Energy Photon Source (HEPS), a regression equation prediction model for surface roughness and material removal depth based on abrasive flow machining was proposed through mixed-level orthogonal experiments. The influences of machining area pressure, machining cycle number, and abrasive mesh number on surface roughness and material removal were revealed. Subsequently, abrasive flow machining verification experiments were conducted on the narrow and deep inner cavities of the absorber, showing that the experimental results were within 15% error compared to the model predictions. After abrasive flow machining, the roughness decreased from about 4.4 μm to around 0.6 μm, significantly improving the surface quality of the workpiece. These research findings can provide a theoretical basis and technical support for the optical finishing of workpieces with narrow and deep variable cross-section inner cavities.

The use of Iron Sand as Filtration Media for Slaughterhouse Wastewater Treatment

An increase in slaughtering animals will have an impact on increasing the liquid waste produced. The resulting RPH liquid waste can damage the environment if it is not treated, so it is necessary to conduct research to reduce pollutant levels so that it is suitable for disposal into the environment. The technique used in processing RPH wastewater is iron sand filtration method. Iron sand filtration is a filtering process using renewable media, namely iron sand. Iron sand is known to contain the mineral magnetite (Fe3O4) which has the ability to absorb colloidal solids, so it has the potential to be used to remove pollutant content of RPH liquid waste. This research objective to determine the effect of variations in the thickness of the filtration media (cm) and grain size (mesh) on pollutant parameters. The thickness variations used were 20, 25, and 30 cm, with grain sizes of iron sand 40, 60 and 100 mesh. The experimental results showed that the iron sand filtration method was able to reduce Chemical Oxygen Demand (COD) and Total Suspended Solid (TSS) levels, increase the Dissolve Oxygen Meter (DO) value, and change the pH value. The highest reduction in COD was in the thickness variation of 30 cm with 100 mesh. the percentage of decrease in the value of Chemical Oxygen Demand (COD) was 95.05%, the highest decrease in Total Suspended Solid (TSS) value was in the media thickness variation of 30 cm with 100 mesh, the percentage of TSS value reduction was 97.11%, the pH value increased in the thickness variation media 30 cm with a mesh number of 100 from 5.8 to 7.4, and the value of Dissolve Oxygen Meter (DO) increased with variations in thickness of 30 cm with 100 mesh, increased from 1.2 to 15.2. Based on the parameter test results, it was concluded that iron sand filtration is effective in reducing pollutant levels below the quality standard, so that it is expected to be applied directly on a larger scale.

Optimizations of the Accelerated Axial Polynomial Method of Characteristics of the APOLLO3® Deterministic Neutron Transport Code

For some years now, the TDT (two- and three-dimensional transport) solver of the APOLLO3® deterministic neutron transport code has been able to perform lattice calculations on three-dimensional extruded and unstructured geometries. A polynomial expansion of the angular flux has been implemented to better describe the flux gradient axially to reduce the number of computational meshes required to reach a given accuracy. Then the polynomial approximation was extended to macroscopic cross sections to perform evolution calculations. Besides these transport schemes, synthetic acceleration has also been implemented, relying on double PN approximations of the angular flux on the boundaries of the spatial regions. The solver has already introduced several techniques to reduce the transport and memory footprint; for example, for the storage of the surfaces crossed by a trajectory or the classification of chords. In this paper, new optimizations are presented. One deals with how monomials of the polynomial basis are integrated along trajectories. Another one concerns the computation of the source term of the transmission equation in the case of polynomial cross sections. The last optimization exploits the fact that, along horizontal trajectories, the flux and the cross sections are constant to speed up the sweep algorithm. Calculations on 5 × 5 and 7 × 7 pressurized water reactor assemblies were performed to assess the gains of these recently developed strategies. The results show good improvements both in computing time and in memory footprint reductions.

Double fast algorithm for solving time-space fractional diffusion problems with spectral fractional Laplacian

This paper presents an efficient and concise double fast algorithm to solve high dimensional time-space fractional diffusion problems with spectral fractional Laplacian. We first establish semi-discrete scheme of time-space fractional diffusion equation, which uses linear finite element or fourth-order compact difference method combining with matrix transfer technique to approximate spectral fractional Laplacian. Then we introduce a fast time-stepping L1 scheme for time discretization. The proposed scheme can exactly evaluate fractional power of matrix and perform matrix-vector multiplication at per time level by using discrete sine transform, which doesn't need to resort to any iteration method and can significantly reduce computation cost and memory requirement. Further, we address stability and convergence analyses of full discrete scheme based on fast time-stepping L1 scheme on graded time mesh. Our error analysis shows that the choice of graded mesh factor ω=(2−α)/α shall give an optimal temporal convergence O(N−(2−α)) with N denoting the number of time mesh. Finally, ample numerical examples are delivered to illustrate our theoretical analysis and the efficiency of the suggested scheme.