【Purposes】Flexible photovoltaic （PV） supports are wind-sensitive, yet research on their wind-induced vibrations and wind vibration coefficients remains insufficient.【Methods】 In this study, a three-row, single-span flexible PV array was investigated by using large eddy simulation （LES） to analyze wind loads and flow field characteristics with varying wind directions and panel tilt angles. Furthermore, the effects of tilt angle and cable prestress on the wind-induced dynamic response of the array were examined, and recommended values for the wind vibration coefficient were finally proposed.【Results】 The results indicate that with 0° and 180° wind directions, the first row exhibits the maximum absolute values of overall wind pressure coefficients. As the tilt angle increases, the interference effect from the wake of upstream modules becomes more pronounced. For varying tilt angles, the first-row supports show the largest vertical mean displacement response; however, when the tilt angle exceeds 15°, downstream supports exhibit more severe vibration amplitudes. The vertical mean displacement and its standard deviation decrease with increasing prestress. By analyzing the influence of various factors on the wind vibration coefficient of the array, a calculation formula incorporating these parameters is proposed.
【Purposes】To investigate the residual stress distribution patterns in high-strength welded circular steel tubes, the hole-drilling strain-gage method is used to measure the surface residual stresses of two Q460C circular steel tube specimens with different cross-sectional sizes.【Methods】Plastic corrections based on the shape change ratio theory were applied to the measured results. The influence of welding on the residual stress distribution pattern of the specimens was examined, and the effect of cross-sectional size on the residual stress of circular steel tubes was analyzed.【Results】The experimental results show that, for circular steel tubes with diameters of 650 and 380 mm with the same welding conditions, the range of heat-affected zone of weld seam is 100 mm, and welding has a minor effect on larger diameter steel tubes. In the non-heat-affected zone, both the transverse and longitudinal residual stresses on the surface are tensile stresses, with the transverse residual stress being significantly greater than the longitudinal residual stress. According to the experimental results, a three-segment linear residual stress distribution model for straight tubes considering the tube diameter and the heat-affected zone of the weld seam is proposed. Comparison with the experimental results shows that the proposed surface residual stress distribution model aligns well with the experimental results, providing valuable reference for stability analysis and load-bearing capacity calculation of welded circular steel tubes.
【Purposes】To investigate the effect of increasing longitudinal reinforcement ratio on the mechanical performance of ultra-high strength concrete-filled steel tube short columns, three groups of reinforced ultra-high strength concrete-filled steel tube （R-CuFST） short columns with different reinforcement ratios and one group of CuFST short columns are subjected to axial compression tests.【Methods】By analyzing the failure modes, bearing capacity, ductility, and confinement effects of specimens, the enhancement effect of longitudinal reinforcement on the mechanical performance of CuFST short columns with axial compression was clarified.【Results】The results indicate that reinforcement can enhance the integrity of concrete inside the steel tube, improving the adverse effects of high brittleness of ultra-high strength concrete on the load-bearing performance of short columns with axial compression. However, with the increase in longitudinal reinforcement ratio, the improvement effect of unit reinforcement ratio on the mechanical performance of short columns shows a trend of first increasing and then decreasing. Therefore, it is recommended that the longitudinal reinforcement ratio should not exceed 3.42%. Compared with reinforced concrete filled steel tube short columns and reinforced recycled aggregate concrete filled steel tube short columns, increasing the amount of reinforcement appropriately has the most significant effect on the load-bearing capacity of unit reinforcement ratio of R-CuFST.
[Purposes]In view of the lack of a unified evaluation system for comprehensively as-sessing the solidification performance of the novel curing agent(red mud+carbide slag+phospho-gypsum)on soils contaminated with different heavy metals,in this study,an evaluation model is estab-lished and the weight of each evaluation index is clarified.[Methods]In this study,a"red mud+cal-cium-based+phosphorus-based"stabilizer was used to examine the performance of soils contaminat-ed with high concentrations of various heavy metals,and the Analytic Hierarchy Process(AHP)was employed to identify the primary factors influencing stabilization effectiveness.An evaluation model was developed to assess the stabilization performance of the contaminated soils,and the weights of the evaluation indices were determined.The study's conclusions were validated through microscopic anal-yses and speciation analyses of heavy metals,confirming the high reliability of the results.[Results]The study results indicate that the factors influencing the evaluation of heavy metal soil stabilizers ef-fectiveness are as follows:compressive strength=permeability coefficient>pH value>environmen-tal hazard>stabilization efficiency,with corresponding weight coefficients of 0.320,0.320,0.164,0.160,and 0.036,respectively.
【Purposes】 Focusing on the operation optimization of a 150 MW CFB boiler, in this paper, the operation, the specific operation optimization scheme, and the test results after operation optimization of the boiler are introduced in detail.【Methods】Drawing on the design concept of fluidization pattern reconstruction, the boiler is optimized to run under low bed pressure, and the effect similar to fluidization pattern reconstruction was achieved by reducing the amount of invalid bed material. In order to verify the correctness of the idea, the operations of the optimized boiler under two working conditions were tested.【Results】By testing the carbon contents of the bottom slag and the bed material, the carbon content of the bottom slag is 1.75%, indicating the operation optimization leads to the reduction of the carbon content and the increase of the boiler thermal efficiency. The carbon content of the bed material decreases first and then increases with the increase of particle size, and there is a minimum value at 100 μm. By measuring the particle size distributions of bottom slag and bed material, it is found that the particle size of furnace material decreases with the increase of height and increases with the increase of load. After operation optimization, the particle size of the bed material is reduced, which effectively alleviates the wear. From the radial temperature distribution of the furnace, there is a high temperature gradient in the boundary layer near the water wall after optimized operation, while the temperature distribution outside the boundary layer is uniform, which indicates that the boiler runs stably after optimized operation and effectively reduces the generation of nitrogen oxides caused by local overtemperature. It shows that the optimized boiler can run safely and stably, with low power consumption, high efficiency, and less wear.
【Purposes】 Biochar and its modified materials have shown certain application potential in the remediation of heavy metal-contaminated soils. However, the electrochemical response characteristics during the remediation of lead-contaminated soil by using red mud-modified biochar （RMBC） require further clarification.【Methods】 Electrochemical impedance spectroscopy （EIS） was used to measure the impedance of soil specimens with different RMBC dosages and curing ages. The evolution of impedance spectra was analyzed by using equivalent circuit model, low-field nuclear magnetic resonance, and machine learning.【Results】 The results show that RMBC increases the radius of the capacitive arc in the Nyquist plots, which first increases and then tends to stabilize with increasing RMBC dosage. With prolonged curing age, the diffusion feature in the low-frequency region gradually weakens, and the charge-transfer process becomes dominant. The equivalent circuit parameters indicate that RMBC affects the conductivity of the pore solution, interfacial charge transfer, and diffusion impedance. Low-field nuclear magnetic resonance results show that RMBC reduces the proportion of micropores and increases the proportions of small and mesopores. A data-driven model is developed by dividing the training and testing sets at the level of complete Nyquist curves. The model captures the overall trend of impedance spectra, although deviations remain in the high-impedance and low-frequency region.【Conclusions】These results indicate that EIS can characterize the impedance response of RMBC-remediated lead-contaminated soil, and machine learning can serve as an auxiliary tool for rapid estimation of Nyquist curves.
【Purposes】Cold-formed thin-wall steel shelves are widely used in the storage industry owing to their light weight, easy assembly and disassembly, and high space utilization. However, this type of structure is highly sensitive to corrosion damage, and as service time increasing, the safety issues caused by corrosion become increasingly prominent.【Methods】Therefore, mechanical property analyses and safety monitoring of the three-dimensional shelf structure were conducted, taking corrosion damage into account.【Results】 The applicabilities of random non-uniform corrosion damage model and uniform corrosion damage model to cold-formed thin-walled steel structures are analyzed and verified. Based on the mechanical analysis of the corrosion shelf, the safety monitoring scheme for existing three-dimensional shelf during service life is determined. The principles for the layout of stress and deformation monitoring points and the method for establishing the monitoring threshold under multiple safety levels are proposed. The mechanical analyses and safety monitoring of cold-formed thin-wall steel shelf are performed, and the feasibility and effectiveness of the proposed method are validated.
【Purposes】 To investigate how loading path affects the static liquefaction responses of the saturated sand.【Methods】 The static liquefaction responses of saturated loose sand were investigated by performing the triaxial tests involving varied loading paths.【Results】The test results show that the saturated loose sand liquefies with different confining stresses when subjected to undrained triaxial compression loading path. The presence of initial shear prior to the undrained triaxial compression accelerates the onset of static liquefaction related instability. The suppressed contraction occurs in the saturated loose sand sample when constant deviator stress is imposed in the undrained condition, which leads to a slow build-up of the excess pore water pressure and spontaneous liquefaction. The undrained loading is not a necessity to trigger the static liquefaction related instability. Under the drained condition, static liquefaction related instability arises in the saturated loose sample when subjected to the loading path involving the increase of the deviator stress as well as the drop of the effective radial stress with a rate of -0.5 kPa/s. The effective stress ratio （q/p′） of the saturated loose sand under the varied loading paths is approximately 0.74, and the corresponding internal friction angle is 19.2°. The flow liquefaction line （FLL） is not an inherent property of the sand with the absence of physical significance. Whether the instability initiates or not when the effective stress path of saturated loose sand approaches the FLL is largely controlled by the loading path. With a certain loading path, the static liquefaction related instability may be triggered once δp′/δσ′3=1 is attained, and to achieve this it should be ensured that loading path before the initiation of instability has not significantly affected the void ratios of samples.
【Purposes】Electrodes based on polypyrrole （PPy） tend to detach from substrates, resulting in poor cycling-stability. Volume expansion and contraction may occur during intercalation and de-intercalation of conductive polymers. Accordingly, incorporating other active materials to fabricate composite materials is essential for improving electrochemical performance.【Methods】In this work, nanoporous gold （NPG） electrodes of carbon quantum dots （CQDs） and PPy were prepared by electrodeposition.【Results】 The prepared CQDS-PPy/NPG exhibit excellent chemical properties owing to the combination of the large specific area of NPG substrate, the active site provided by CQDs, and the excellent electronic conductivity of PPy. Based on these synergistic effects, the CQDs-PPy/NPG composite electrode has a specific capacitance of 792 F/g at a current density of 1 A/g and 90.5% of the specific capacitance is maintained when the number of cycles is increased to 5 000.【Conclusions】In this study, the combination of CQDs and PPy is explored to prepare supercapacitor electrode materials, which provides an important experimental basis and theoretical reference for the development of advanced energy storage devices.
【Purposes】The cantilever-beam structural components of mining excavators are mainly fabricated by welding Q355ME low-alloy high-strength steel plates. The strength and fatigue performance of welded joints govern the failure mode of cantilever-beam parts and further determine the overall service life of mining excavators. Hence, investigating fatigue-failure behaviors of welded joints of Q355ME steel plates used for mining excavators is vital for their safe in-service operation.【Methods】 On the basis of the irreversible deformation of metal materials and the variation of sample surface temperature, the initiation and propagation of fatigue cracks in welded joints of Q355ME steel were characterized in this paper. The fatigue damage mechanism and crack propagation mechanism were studied from the perspective of microstructure and energy evolution of fatigue crack tip region.【Results】The results show that, the fatigue limit of Q355ME steel welded joints is 350 MPa, and the fatigue limit fitted with the fatigue surface temperature rise stabilization value of Q355ME steel welded joints is 324 MPa, showing is a difference of 7.4%. It is shown that fatigue fracture of Q355ME steel welded joints can be evaluated according to temperature evolution. The results of the study ensure the safety and reliability of Q355ME steel welded joints in-service.
【Purposes】The limit equilibrium method is the most prevalent approach in slope stability analysis. For rigorous methods applicable to any sliding surface, numerical problems often arise in the process of safety factor solving.【Methods】Regarding the above points, the force balance equation was organized into the framework of unbalanced thrust method considering the influence of interbar forces without assuming their specific direction. By leveraging the geometric relationships between adjacent soil strips and the horizontal normal forces on the outermost soil strips （the first and nth strips） on both sides of the sliding mass, a moment recursion relationship was established with the condition that the moment at the midpoint of sliding surface at the base of soil strip was zero. Two separate expressions for the safety factor Fs and the proportionality factor λ were derived. In calculating the safety factor, an initial estimate was made by using Fs=1 and λ=0 to determine a satisfactory Fs。This safety factor was then substituted back into the equation to solve for the corresponding λ. This iterative process was repeated 7-8 times to achieve Fs and λ values with tolerances as small as 0.000 1.【Results】The results indicate that this algorithm is simpler, more straightforward, and converges more easily than other rigorous methods, making it applicable to sliding surfaces of any shape. Furthermore, it can be efficiently implemented on a computer through a simple program and has the potential for widespread applications in the engineering field.
【Purposes】As a common stratum in the development of hydrothermal geothermal resources, the change rule of permeability with thermal coupling is crucial.【Methods】In this work, a radial seepage experimental reactor was designed and developed independently to conduct radial multifracture group granite seepage tests at different temperature and pressure conditions （normal stress:30～50 MPa, temperature: 6～150 ℃）.【Results】The results show that: with the action of thermal coupling, the radial multi-fractured granite seepage flow and permeability monotonically increase with the increase in temperature, while with the increase in normal stress the seepage shows a negative exponential relationship of decay. There is a threshold pressure of 5 MPa in 1～7 MPa osmotic pressure range, before the threshold pressure, with the osmotic osmotic pressure increasing, the permeability of the rapid increases. Thermal damage to granite bedrock with thermal coupling has a negligible effect on permeability changes, and seepage water rock dissolution and thermal expansion of mineral particles are the main factors affecting changes in fracture morphology and seepage characteristics.
【Purposes】To promote the use of industrial solid wastes such as red mud and carbide slag in engineering materials, a multi-source solid waste flowable solidified soil is prepared by using red mud, carbide slag, metakaolin, and magnesium slag as main constituents.【Methods】 Carbonated and non-carbonated specimens were produced and subjected to freeze-thaw cycles and wet-dry cycles, separtately. Changes in macroscopic appearance, mass loss rate, linear shrinkage, unconfined compressive strength, pH value, and electrical resistivity were examined, and the associated structural evolutions were analyzed with SEM and FTIR.【Results】 The results indicate that both freezethaw cycling and wet-dry cycling lead to deterioration of the flowable solidified soil. During freezethaw cycles, the strength decreases continuously, whereas during wet-dry cycles it increases first and then declines. Carbonation improves the initial structure of the specimens. At the early stage of freezethaw cycling, mass loss and shrinkage reduce while early strength increases; however, this beneficial effect becomes less evident with increasing cycle number. During wet-dry cycles, the carbonated specimens show comparatively larger mass loss and shrinkage at later stages. Among different mixtures, the specimen containing 30% magnesium slag shows better stability with both environmental conditions. In both cases, the pH value decreases overall, and electrical resistivity shows a positive correlation with unconfined compressive strength. Microscopic observations further show that gel products gradually decrease during cyclic exposures, while pores and microcracks continue to develop, leading to progressive degradation of cementitious structure.
【Purposes】 In the dual-background of ecological civilization construction and concentrated contiguous protection of traditional villages, in this study, the challenges of impaired landscape continuity and insufficient synergy of ecological functions in traditional villages are addressed by taking Xiaoyi City in Shanxi Province as a case study.【Methods】First, a comprehensive evaluation method was employed to assess the natural-cultural ecological value of traditional village nodes. Subsequently, fourteen key factors were selected from the three dimensions of natural environment, socioeconomic conditions, and service facilities, and the analytic hierarchy process was applied to determine their weights and construct an integrated composite resistance surface. The minimum cumulative resistance model was then used to identify ecological corridors, and the gravity model was further applied to classify these corridors into hierarchical levels. Finally, a traditional village ecological network characterized by a “three-level node and three-level corridor” structure was identified.【Results】 The results show that ecological resistance in the study area exhibits a pattern of being high in the northwest and low in the southeast. Traditional villages are predominantly located in medium- to low-resistance areas, which are conducive to constructing a low-cost ecological flow network structure. Core nodes and corridors are mainly concentrated on the northern side of Shengxi Lake, while the remaining nodes and corridors are evenly distributed and extensively connected, forming a secondary network. Through the identification and optimization of the traditional village ecological network, this study provides a scientific basis for the contiguous conservation and sustainable ecological development of traditional villages.
【Purposes】Middling coal has serious dirt band, and the embedded particle sizes of coal and other gangue minerals are fine, which affects the ash content of flotation clean coal and is extremely difficult to recycle. Thus, the purpose of this paper is to fully dissociate the middling coal through superfine grinding pretreatment. At the same time, dispersant is added in the flotation process to weaken the agglomeration of ultrafine particles in the flotation process and improve the flotation effect together.【Methods】 The flotation effects with different grinding times and pretreatment with lignin, car boxymethyl cellulose （CMC-Na）, and sodium hexametaphosphate （SHMP） were compared, and the flotation mechanism at the macro and meso levels was analyzed.【Results】The results of the macroscopic experiments show that the exposure of hydrophobic functional groups such as alkyl chains after grinding results in the dissociation of more fresh carbonaceous surfaces of coal samples, which ultimately leads to the enhancement of hydrophobicity. At the same time, polar functional groups such as carboxyl （—COOH） and hydroxyl （—OH） are exposed and ionized in the water, which enhances the negative electrification of coal surface, and weakens the phenomenon of intermediate coal entrapment as well as fine mud capping. Mesoscopic characterization reveals that lignin adsorption hardly occurs on the surface of coal samples. In addition, the mojor composiation of CMC-Na is the carbon chain that is easy to produce hydrophobic bonding cooperation with the carbonaceous surface, making its side chain —OH structure be exposed on the surface, and the hydrophilicity of the solid CMC-Na modified coal samples is enhanced. The cyclic structure of SHMP may produce p-π stacking interaction with the aromatic ring, so that the oxygen-containing functional groups of the SHMP agent part are exposed on the surface, and the negative electronegativity of the modified middling coal is significantly enhanced, which disperses the coal samples greatly through electrostatic repulsion, reduces the probability of agglomeration of carbonaceous and chalcopyrite minerals, and enhances the flotation separation effect. The final results show that SHMP has the best effect.【Conclusions】The results show that the effects of chemicals on flotation effect can be divided into two types—adsorption of chemicals to improve wettability and dispersion by electrostatic repulsion, and the dispersion occupies the dominant factor, which improves wettability better. This study hopes to provide a new idea for the flotation of middling coal.
【Purposes】As a new method of fracturing, high-voltage pulse discharge in water has been widely used in coalbed methane fracturing owing to its green, safe, efficient, and controllable characteristics. Since to the abundant primary cracks in coal and rock mass, the water shock wave generated by high-voltage pulse discharge in water will produce transmission and reflection at the primary fracture, and the reflected wave and the next water shock wave will superimpose to form interference, resulting in more cracks. The cracking effect of high-voltage pulse discharge in water on rock mass un der different primary fracture lengths is studied.【Methods】The parameters such as crack length, force chain fracture number, crack width, and vibration velocity measured at fixed point were counted through discharge fracture test and numerical simulation of large-size rock specimens with triaxial pressure in the laboratory, and the influence of primary fracture length on the initiation and propagation of rock fractures was studied.【Results】The results show that the number of pulse discharges has a significant effect on the initiation and propagation of cracks in coal and rock mass, and the growth rate of crack width increases with the increase of the length of the cracks. The presence of primary cracks increases the total length and total number of cracks generated when electrical pulse induces cracking. The existence of primary fractures changes the stress distribution in coal and rock mass, and with the increase of the length of primary fractures, the compressive stress in the wavefront region decreases, and cracks are more likely to occur under the same impact load. With the increase of the length of the primary crack, the number of force chain fractures increases, the peak value of the vibration velocity at the measured point in the frontal side region increases, and the number of time steps required to reach the maximum vibration velocity decreases.【Conclusions】The research results provide a theoretical basis for the dynamic fracturing technology of high-gas coal seam discharge.
【Purposes】Coal gasification fine slag is a solid waste formed during the coal gasification process.【Methods】 To improve its utilization rate, in this research, the substitution of part of cement with coal gasification fine slag was conducted. The setting time of paste, workability, and mechanical properties of the mortar were investigated. Besides, the hydration mechanism of the coal gasification fine slag-cement composite was analyzed by using isothermal calorimetry, XRD, scanning electron microscopy, and thermodynamic simulation.【Results】The results indicate that as the content of coal gasification fine slag increasing, the setting time of pure cement paste is prolonged, and the workability of the mortar gradually decreases. When the coal gasification fine slag content is 10%, the 28 d compressive strength of the mortar reaches the level of the control group. Adding an appropriate amount （not exceeding 10%） of coal gasification fine slag into cement-based materials reduces heat of hydration of cement, decreases cement consumption, and improves the utilization rate of coal gasification fine slag without significantly affecting the performance indicators of cement-based materials.
【Purposes】To optimize the performance of red mud-based geopolymer for tail grouting, the effects of Na2O content on the fresh properties, hardened mechanical properties, electrical characteristics, and microstructure of the slurry are investigated in this study.【Methods】A single-factor experimental design was employed, with Na2O content （0～8%） as the variable, to systematically analyze the slurry's density, fluidity, consistency, stone rate, bleeding rate, setting time, unconfined compressive strength, resistivity, electrochemical properties, and microscopic morphology.【Results】The results indicate that as the Na2O content increases, the slurry density gradually increases, fluidity decreases, the slurry becomes more viscous, and the setting time is significantly shortened. The compressive strength exhibits an exponential growth trend, with a significant increase at 5%～8% Na2O content, reaching a maximum of 60.64 MPa at 28 d. Resistivity increases with Na2O content, and long-term curing further enhances the material's microstructural compactness. Electrochemical tests show that higher Na2O content promotes the formation of geopolymerization products, improving material durability. Scanning electron microscope analyses reveal that increasing Na2O content transforms the material from a porous and loose structure to a dense and uniform one, with the 5%～8% content samples exhibiting the most favorable microstructural characteristics. In summary, Na2O content in the range of 5%～7% optimizes slurry performance, balancing workability and mechanical durability.
【Purposes】At present, the treatments of heavy metal contaminated sites are mostly based on mechanical and chemical property tests, thus proposing non-destructive, fast, convenient, and cost-effective physical evaluation methods is a key issue that needs to be solved urgently.【Methods】In this paper, the curing effect of red mud-based curing agent on copper-contaminated loess was investigated, and the unconfined compressive strength and electrochemical impedance response of the cured body were systematically analyzed and evaluated, and the corresponding equivalent model was established for fitting.【Results】The results show that the unconfined compressive strength of the so lidified body shows a trend of increasing and then decreasing with the increasing mass ratio of red mud fly ash, and the maximum strength value is achieved at the ratio of 13∶2. By analysing the image characteristics of Nyquist and Bode plots of electrochemical impedance spectra, the same can be concluded that the mass ratio of 13∶2 for red mud fly ash is the optimum mass ratio. In addition, the equivalent circuit of the solidified body electrochemical system is established as （QR）（Q（RW））R, and the relationships between the parametric components and the strength are analysed. The values of the equivalent circuit components Rs, Rct1, and Rct2 parameters are positively correlated with the strength, and the values of CPE1, CPE2, and W parameters are negatively correlated with the strength. The relationships between the pore solution resistance Rs, the ion transfer resistance Rct2 within the solidified body, and the strength and the mass ratio of red mud and fly ash （RM-FA） are established by parameter fitting, separtely, and the associated polynomials are obtained. The results of electrochemical impedance spectroscopy and the coincidences of parameters of each element of the equivalent circuit with traditional strength indices, indicating that the electrochemical impedance spectroscopy technique can be effectively used to evaluate the curing effect of copper-contaminated soils.
【Purposes】In order to study the anti-reflection effect of mechanical cavitation technology on soft and low-permeability coal seam, a fluid-solid coupling numerical model for gas extraction is established on the basis of the engineering background of No.3 coal seam in Tangan Coal Mine.【Methods】The effects of cavitation section length and spacing on gas extraction effect were studied by using COMSOL Multiphysics software. 【Results】The results show as follows: Increasing the length of cavitation section or decreasing the spacing of cavitation section can increase the contact area between coal and air in the cavity, generate new cracks in the coal body or enlarge the original cracks, increase gas migration channels, make gas desorption faster in the process of pressure relief, and increase permeability of coal body. Considering the improvement of coal seam gas extraction effect and the saving of engineering cost and construction time, the reasonable length and spacing of cavitation section should be 1 and 10 m, respectively. A field test was carried out in the No. 3 coal seam of Tangan Coal Mine to compare the influence of different caving section lengths and caving section spacing on the extraction purity. The field investigation results are in agreement with numerical simulation results. Compared with ordinary drilling, the pure gas extraction from single hole of mechanical cavitation drilling is increased by 2.95～3.65 times, indicating that mechanical cavitation drilling is more suitable for soft and low-permeability coal seam than ordinary drilling.
