Ratio Of Grains Research Articles

Study of the Dynamic Recrystallization Process of the Inconel625 Alloy at a High Strain Rate.

High-temperature compression and electron backscatter diffraction (EBSD) techniques were used in a systematic investigation of the dynamic recrystallization (DRX) behavior and texture evolution of the Inconel625 alloy. The true stress–true strain curves and the constitutive equation of Inconel625 were obtained at temperatures ranging from 900 to 1200 °C and strain rates of 10, 1, 0.1, and 0.01 s−1. The adiabatic heating effect was observed during the hot compression process. At a high strain rate, as the temperature increased, the grains initially refined and then grew, and the proportion of high-angle grain boundaries increased. The volume fraction of the dynamic recrystallization increased. Most of the grains were randomly distributed and the proportion of recrystallized texture components first increased and then decreased. Complete dynamic recrystallization occurred at 1100 °C, where the recrystallized volume fraction and the random distribution ratios of grains reached a maximum. This study indicated that the dynamic recrystallization mechanism of the Inconel625 alloy at a high strain rate included continuous dynamic recrystallization with subgrain merging and rotation, and discontinuous dynamic recrystallization with bulging grain boundary induced by twinning. The latter mechanism was less dominant.

Austenite Grain Growth Behavior of 30BF Steel Before Rough Rolling

To investigate the effect of heat treatment on the grain size of austenite in 30BF steel, the comparisons of the morphologies and sizes of austenite grains between heating samples were made with a high-temperature electric resistance furnace, and the austenite growth models were built with method of mathematics. The results show that most grains in original specimen with the sizes below 70 μm uniformly distributed. At a heating rate (v) of 10 °C/s, the grain size (d) value under a certain time (t) increased by 60–100 μm with raising temperature (T) from 850 to 1100 °C, whereas the d value under a certain T merely increased by 70–120 μm with raising time to 60 min. Under v = 0.1 °C/s, T = 850 °C, and t = 0 s, the occupied ratio of grains with sizes of 40–50 μm was 0.165, whereas at 900 °C, the occupied ratio was 0.125. The evolutions of $$\ln \left({d^{5.8} - d_{0}^{5.8}} \right)$$ with 1/T were in negative linear correlations, whereas the $$\ln \left({d^{5.8} - d_{0}^{5.8}} \right)$$ with lnt were in positive linear correlations. To sum up, the grain growth behavior of steel was elucidated.

Relationship between Fusarium Head Blight, Kernel Damage, Concentration of Fusarium Biomass, and Fusarium Toxins in Grain of Winter Wheat Inoculated with Fusarium culmorum.

Winter wheat lines were evaluated for their reaction to Fusarium head blight (FHB) after inoculation with Fusarium culmorum in two field experiments. A mixture of two F. culmorum chemotypes was applied (3ADON—deoxynivalenol producing, NIV—nivalenol producing). Different types of resistance were evaluated, including head infection, kernel damage, Fusarium biomass content and trichothecenes B (deoxynivalenol (DON), and nivalenol (NIV)) accumulation in grain. The aim of the study was to find relationships between different types of resistance. Head infection (FHB index) and Fusarium damaged kernels (FDK) were visually scored. Fusarium biomass was analysed using real-time PCR. Trichothecenes B accumulation was analysed using gas chromatography. Wheat lines differ in their reaction to inoculation for all parameters describing FHB resistance. We found a wide variability of FHB indexes, FDK, and Fusarium biomass content. Both toxins were present. DON content was about 60% higher than NIV and variability of this proportion between lines was observed. Significant correlation was found between head infection symptoms and FDK. Head infection was correlated with F. culmorum biomass and NIV concentration in grain. No correlation was found between the FHB index and DON concentration. Similarly, FDK was not correlated with DON content, but it was with NIV content; however, the coefficients were higher than for the FHB index. Fusarium biomass amount was positively correlated with both toxins as well as with the FHB index and FDK. Environmental conditions significantly influenced the DON/NIV ratio in grain. In locations where less F. culmorum biomass was detected, the DON amount was higher than NIV, while in locations where more F. culmorum biomass was observed, NIV prevailed over DON.

ВПЛИВ СТРУКТУРИ ПОСІВНИХ ПЛОЩ НА ПРОДУКТИВНИЙ ПОТЕНЦІАЛ ОРНИХ ЗЕМЕЛЬ ПІВДЕННО-ЗАХІДНОГО ЛІСОСТЕПУ УКРАЇНИ

It is indicated on the role of crop rotation in increasing the productive potential of arable land. The output of products by feed and grain units from 1 ha of arable land in crop rotation with different ratios of grains and technical crops on the basis of the achieved level of yield of field crops in the conditions of a particular agrarian enterprise was established. For the conditions of Kitsman-Kelmentsy land evaluation area of Chernivtsi region, the effect of maize (corn, 1 or 2 fields) and sugar beet (1 or 2 fields) on the productivity of 7 fields rotation of cereals and row crops was studied. Humus balance is calculated and the main ways of improving humus conditions in rotation of cereals and row crops are given. The schemes of crop rotation have been established, providing the highest degree of realization of productive potential of arable land.

Effect of thermal anisotropy on binary alloy dendrite growth

A numerical model to study the effect of thermal anisotropy on binary alloy dendrite growth is presented. The model is based on the volume averaged enthalpy method with explicit surface tension anisotropy for crystal orientation. Thermal anisotropy is incorporated using anisotropic thermal conductivity in the energy equation. This is done by splitting the anisotropic conductivity into two parts, equivalent isotropic conductivity and anisotropic departure source term, enabling the use of a conventional isotropic solver to model anisotropic heat transfer. The proposed model is applied to study the effect of thermal anisotropy ratio on tip velocity, aspect ratio and equivalent radius of an equiaxed grain growing in an undercooled binary alloy melt. It is found that the thermal energy stored in the grain during solidification plays an important role in interface evolution, and thus anisotropic conductivity in the solid affects the grain morphology. There is a consistent increase in the aspect ratio of grains with increase in thermal anisotropy ratio, although the grain volume remains almost invariant. Due to unequal growth rates of the perpendicular arms, severe distortion of the solid crystal is seen at higher thermal anisotropy ratios. The model is further extended to study the growth of multiple dendrites in order to simulate microstructure evolution with thermal anisotropy. It is observed that thermal anisotropy significantly affects the grain morphology at low grain density but has a smaller influence at high grain density as compared to other governing factors such as solute transport.

The effect of sulphur and nitrogen supply on the growth and nutrient content of spring wheat (Triticum aestivum L.)

Sulphur is an essential element for plants. Decreasing sulphur deposition from the air, and the use of more concentrated phosphate fertilizers, which contain no sulphur, has led to reports of sulphur deficiencies for wheat. Sulphur deficiency significantly affects yield and also the quality of wheat. The pot experiment was set up on calcareous chernozem soil at Látókép, Hungary, test plant was spring wheat (Triticum aestivum L). Seven treatments were used where nitrogen and sulphur were supplied as soil fertilizers in increasing rates (NS1, NS2, NS3) and in foliar fertilizer as well (NS1+fol., NS2+fol., NS3+fol.). Plant aboveground biomass production was determined in samples taken in the stages of development BBCH 29-30, 51-59, 61-69, 89. The nitrogen and sulphur content of straw and grain were measured. N/S ratios of grain and straw were calculated. The weights of grain were ranging between 8.6–16.1 g/pot. NS2 and NS2+fol. treatments produced the highest values. Foliar fertilizer had no further effect on grain. Analysing the values of the straw, it was observed that tendencies were similar to values of grain. The NS2 treatment produced the highest weight of straw and the NS3 rate already decreased that amount. The obtained results show the unfavourable effect of excessively high rate applied in NS3 treatment. The supplementary foliar fertilizer had no significant influence on the weight of straw. Both N and S-uptake of plant was very intensive at the stem elongation stage, then the N and S-content of plant continuously decreased in time in all treatments. The N-content of grain ranged between 2.215–2.838%.
 The N-content of grain slightly increased with increasing of nitrogen doses. In the higher doses (NS2, NS3) foliar fertilization slightly increased the nitrogen content of grain, although this effect was not statistically proved. The N-content of straw varied from 0.361 to 0.605%. The growing dose of soil fertilizer also considerably increased the nitrogen content of straw. Foliar fertilization further increased the nitrogen content of straw. The S-content of grain ranged between 0.174–0.266%. The lowest fertilizer dose (NS1) significantly increased the sulphur content of grain. The further increasing fertilizer doses (NS2, NS3) did not cause additional enhance in sulphur content of grain.
 The foliar fertilizer also did not change the sulphur value of plant. The increasing amount of soil fertilizer and the supplementary foliar fertilizer had no effect on the sulphur content of straw. The treatments influenced the N/S ratios of grain and straw. On the basis of experimental results it can be concluded that the examined nitrogen and sulphur containing soil fertilizer had positive effect on the growth and yield of spring wheat grown on the calcareous chernozem soil. The soil fertilizer application enhanced the grain nitrogen and sulphur content. The highest rate of fertilizer (600 kg ha-1) proved to have decreasing effect on the yield. The sulphur and nitrogen containing foliar fertilizer did not have significant effect on the yield parameters but slightly increased the nitrogen content of plant.

Influence of drying temperature on the structural and cooking quality properties of black rice

Background and objectivesPaddy rice was dried in a fixed‐bed dryer at 20, 40, 60, 80, and 100°C, with air speed set at 0.5 m/s. The drying kinetics, moisture diffusivity, and morphologic characteristics of black rice grains from IAC 600 genotype were determined.FindingsBlack rice grains dried at 60, 80, and 100°C exhibited a reduction in the head rice percentage after dehusking (HRD) as the temperature increased. This behavior was confirmed by the occurrence of cracks in the endosperm of black rice when observed using an SEM. There was a reduction in cooking time, hardness, adhesiveness, and in the extractability of water‐soluble proteins as well as in the extractability of proteins in 2% sodium dodecyl sulfate media in black rice subjected to 100°C of drying temperature, as compared to 20°C. Conversely, increases in the rehydration ratio of grains dried at 100°C were observed. Increases in the peak and breakdown viscosities and reductions in pasting temperature, final viscosity, and setback viscosity in Rapid Visco Analyzer profile of 100°C‐dried black rice were also observed.ConclusionsThe increase in drying temperature promoted the increase in drying rate (k) and Deff. When black rice grains were dried at 60, 80, and 100°C, there was a decrease in HRD because of the evident increase in the intensity of endosperm fissures. The fissure formation is attributed to drying at temperatures of 60, 80, and 100°C occurring above the glass transition temperature (rubbery region) coupled with a non‐efficient tempering. At 100°C, modifications were observed in the flour pasting properties, indicating the higher extent of protein–starch interactions, confirmed by the reduction of protein extractability.Significance and noveltyFew reports exist on black rice structure and cooking quality as a function of post‐harvest conditions. The present work provides scientific support on how drying temperature impacts black rice quality.

Organic manures: an efficient move towards maize grain biofortification

PurposeIn a novel approach, certain organic wastes byproducts of agro industries were assessed for their ability to support maize growth and Zn bioavailability in maize grain.MethodsIn a field experiment, maize (Zea mays) was supplemented with farm yard manure (FYM), press mud (PM), fisheries manure (FM), and slaughter house waste (SHW) in combination with Zn soil application (ZnS) and Zn foliar spray (ZnF) with recommended doses of N:P:K (140:100:60 kg ha−1), respectively. Besides assessing the maize growth, grain, and straw yield, Zn bioavailability in maize grain was also studied.ResultsOrganic materials combined with ZnS and ZnF significantly increased the maize yield and Zn bioavailability. PM + ZnS increased the grain yield by 69.71%, while FM + ZnF and FYM + ZnF increased the grain Zn concentration by 86.37 and 86.16%, respectively. Moreover, grain Zn content was greatly influenced by PM + ZnS and PM + ZnF resulted an average increase by 160%. Phytate concentration and phytae:Zn molar ratio in grain were decreased by 30.34 and 66.92%, respectively by FYM + ZnF. Estimated Zn bioavailability ranged from 0.92 to 2.04 mg Zn/300 g in maize grain, and was maximum by PM and FYM combined with ZnF.ConclusionOrganic manures influence the nutrient uptake from soil, increase the product quality, and act as a good organic fertilizer. The current study revealed that organic manures can enhance crop growth and Zn uptake in grain in sustainable manner. It would be an eco-friendly approach by utilizing organic wastes annually generated by agro industries.

Allanite-(Ce): a Typical Mineral of Metakimberlite from the Lake Kimozero Area, Karelia

Paleoproterozoic kimberlite from the Kimozero area in Karelia is the oldest rock of this type in Russia. It is strongly tectonized, metamorphosed, and it finally transformed into metakimberlite of the prehnite-pumpellyite facies with widespread lanthanide minerals: allanite-(Ce), bastnaesite-(Ce), bastnaesite-(La), parisite-(Ce), and monazite-(Ce). The contacts between their crystals and other metamorphic minerals, e.g., titanite, antigorite, and tremolite, are characterized by induction surfaces of concerted growth. Among lanthanide minerals, allanite-(Ce) is the most abundant. It occurs close to clinochlore pseudomorphs after phlogopite or as intergrowths with titanite in aggregates of tremolite–actinolite, calcite, and dolomite. Allanite crystals from the Kimozero area are not zonal, but vary in lanthanide contents and the Fe3+/Fe2+ ratio in grains no more than tens of microns from one another. Kimozero allanite mostly belongs to the allanite–ferriallanite series (up to 30% of ferriallanite endmember); the lesser amount corresponds to the allanite–Cr-bearing allanite series. At the late stage of metamorphism, allanite was partly replaced with parisite, bastnaesite, or monazite.

Anisotropic properties of Na-\u03b2\u2033-alumina + YSZ composite synthesized by vapor phase method

Two α-alumina + YSZ samples were prepared by sintering for 3 h one at 1500 °C and the other at 1700 °C. The samples were then converted to Na-β″-alumina + YSZ by vapor phase conversion. Characterization techniques such as X-ray diffraction, scanning electron microscopy, and electrochemical impedance spectroscopy in addition to dimensional geometrical changes reveal the evolution of slight anisotropy in these samples during conversion. This results in an electrical conductivity anisotropy factor of about 5.5 and 1.8 for samples sintered at 1500 °C and 1700 °C, respectively. In all samples, the higher ionic conductivity was measured across the sample thickness as opposed to parallel to the disc faces. The ionic conductivity measurements show the conductivity of about 0.15 S/cm and 0.07 S/cm at 300 °C for samples sintered at 1500 °C and 1700 °C, respectively. The larger anisotropy in samples sintered at 1500 °C is explained by the higher aspect ratio of grains in this sample and by different Na concentrations.

Analytic Study on On-Line Model of Moisture in Hot Air Drying Process of Grain

This study aims to review variation pattern of moisture content ratio of grains in deep-bed drying process, guide the drying technology design, realize real-time tracking and regulation in drying process, improve the quality of drying process and reduce energy consumption. Based on the moisture diffusion model in thin layer drying process, the principle of mass conservation of deep drying process, state function and irreversible thermodynamics analytic method, we have established and solved basic equations of deep-bed drying of grains, obtained the moisture content ratio of grains and analysis formula of drying velocity distribution in processes of concurrent flow drying, counter flow drying, cross-flow drying and standing drying and resolved the sustained decreasing drying process of grains in the concurrent flow drying and extreme point of drying rate in the counter-flow drying. Under the same conditions of temperature, humidity and air output, the drying velocity in counter-flow drying significantly higher than that in the concurrent flow drying. It means the energy utilization effects in counter-flow drying is better than that in the concurrent flow drying. Drying characteristics of grains in cross-flow drying and standing flow drying are the same, while drying rates in inlet-air side and outlet-air side vary widely. It means that when the layer thickness is 0.5m and the moisture content is over 20%, the drying rate in outlet-air side is nearly zero and the drying uniformity is bad. Tests on 5HP-3.5 recirculation drier shows that maximum deviation between analytic value and measured value in deep drying process is 0.69% and the range scope is -0.27%-0.69%. From the drying characteristics of grains, deviations mainly come from instrument detection deviations. The analytic method has important significance for realizing real-time tracking and regulation in drying process, guiding drying technology design, reducing energy consumption, increasing drying rate and drying machine capacity.

Microstructure evolution during solution treatment of extruded Al-Zn-Mg profile containing a longitudinal weld seam

In this study, the microstructure evolution during solution treatment of extruded Al-Zn-Mg profile containing a longitudinal weld seam was firstly reported. The porthole die extrusion experiment was conducted to obtain the extruded profile. The solution treatment was performed at 470 °C for 15 min, 60 min and 120 min, respectively, and the aging was performed at 120 °C for 24 h. The secondary phase distribution, grain morphology, grain size and texture evolution of welding zone during solution were investigated. Moreover, the hardness and tensile properties after aging were analyzed. The results show that the solution for 15 min is sufficient for the dissolution of MgZn2 phase, while Al2CuMg and Al23CuFe4 phases cannot be dissolved even the solution time is prolonged to 120 min. The main texture components of {110}<111> and {110}<115> are formed after extrusion process, and these textures are remained after solution treatment. With increasing solution time, the intensity and volume fraction of texture firstly increases and then decreases. Furthermore, both the average size and aspect ratio of grains in welding zone increase with increasing solution time. The best hardness, tensile strength and elongation was obtained in the Al- Zn-Mg profile after solution treated for 15 min.

Processing and characterization of sintered reaction bonded Si3N4 ceramics

The present contribution reports the influence of nitridation and sintering conditions on the densification, microstructure, mechanical and thermal conductivity properties of sintered reaction bonded Si3N4 (SRBSN) mixed with 3.5% Y2O3-1.5% MgO. The nitridation of samples was carried out at 1450 and 1500°C for different time schedules (2.5, 8 and 16h) in order to increase β Si3N4 phase and subsequently sintering was performed at various temperatures (1850, 1900 and 1950°C) for 10h to enhance densification and properties of SRBSN ceramics. It was observed that the density of the samples slightly decreased and β Si3N4 phase significantly increased to 87% with increasing nitridation temperature and time. The density of gas pressure sintered (GPS) samples increased with increasing sintering temperature, almost full density was measured for all the samples at the respective sintering temperature (except those samples which were given nitridation at 1500°C for 16h). The microstructure of SRBSN samples were characterized by bimodal microstructure with equiaxed and rod like elongated grains and average grain size of SRBSN samples varied between 1.62 and 2.43μm and aspect ratio of grains varied from 3.78 to 6.88 with varying the sintering temperature. Depending on the sintering density and microstructure, the SRBSN samples exhibited hardness (16.69 to 19.47GPa), fracture toughness (7.02 to 9.20MPa·m1/2) and thermal conductivity (77.32 to 98.52W/m·K). The coarsening of grain size and aspect ratio negatively affected hardness and fracture toughness, on the contrary the thermal conductivity increased. Among all samples, the SRBSN (which was subjected to nitridation at 1500°C for 16h; GPS at 1950°C for 10h) measured with good combination of hardness: 17.32GPa, fracture toughness: 8.36MPa·m1/2and thermal conductivity: 98.52W/m·K.

The effect of municipal sewage sludge on the content, use and mass ratios of some elements in spring barley biomass

Abstract Municipal sewage sludge contains considerable amounts of macro and microelements essential for plant nutrition. With decreasing use of natural and organic fertilizers, there is a need to search for alternative sources of organic matter (which is a substrate for humus reproduction). In a field experiment carried out on heavy soil with neutral reaction, the effect of single application of municipal sewage sludge in a dose of 5.34 Mg·ha−1 DM was compared to an equivalent dose of mineral fertilizers. The test plant was spring barley. After application of municipal sewage sludge, slight positive changes in the chemical properties of the soil were observed. The sewage sludge increased the yield of spring barley grain and straw by, respectively, 14 and 13% in relation to treatment with mineral fertilization. Spring barley fertilized with sewage sludge contained more elements than barley grown only on mineral fertilizers. It was shown that application of municipal sewage sludge to the soil had a significant effect on increase in nutrient uptake by spring barley. Fe was taken up in the highest amount, followed by Al and Mn, and Co was taken up in the smallest amounts. Utilization of Fe, Mn, Co and Al from sewage sludge by spring barley was at 6.0, 4.7, 0.7 and 0.7%, respectively of the amount applied to the soil with this waste. The mass ratios (Fe:Mn, Fe:Al, Mn:Co) analyzed in spring barley biomass were much wider in straw than in grain. In terms of grain feed value, Fe:Mn ratio in grain and straw was greater than optimum.

Pore scale evaluation of thermal conduction anisotropy in granular porous media using Lattice Boltzmann method

PurposeThermal conduction anisotropy, which is defined by the dependency of thermal conductivity on direction, is an important parameter in many engineering and research studies such as the design of nuclear waste depositional sites. In this context, the authors aim to investigate the effect of grain shape in thermal conduction anisotropy using pore scale modeling that utilizes real shapes of grains, pores and throats to characterize petrophysical properties of a porous medium.Design/methodology/approachThe authors generalize the swelling circle approach to generate porous media composed of randomly arranged but regularly oriented elliptical grains at various grain ratios and porosities. Unlike previous studies that use fitting parameters to capture the effect of grain–grain thermal contact resistance, the authors apply roughness to grains’ surface. The authors utilize Lattice Boltzmann method to solve steady state heat conduction through medium.FindingsBased on the results, when the temperature field is not parallel to either major or minor axes of grains, the overall heat flux vector makes a “deviation angle” with the temperature field. Deviation angle increases by augmenting the ratio of thermal conductivities of solid to fluid and the aspect ratios of grains. In addition, the authors show that porosity and surface roughness can considerably change the anisotropic properties of a porous medium whose grains are elliptical in shape.Originality/valueThe authors developed an algorithm for generation of non-circular-based porous medium with a novel approach to include grain surface roughness. In previous studies, the effect of grain contacts has been simulated using fitting parameters, whereas in this work, the authors impose the roughness based on the its fractal geometry.

Responses of wheat yield, quality and bread-making properties on the sulphur fertilization

ABSTRACTThis study presents a versatile influence of sulphur (S) application on winter wheat – beginning with the influence on the grain yield and primary quality indices, followed by the one on the bread-making properties of flour and dough, and ending with the one on the quality indices of baked products. Field experiments were conducted at two locations on haplic Luvisol and calcaric Cambisol during five years. S was given as NS-fertilizers on the background of N100 during wheat tillering. Flour and dough properties for bread-making were determined by using a farinograph Brabender. The baking tests were carried out in laboratory conditions. The influence of S on the grain yield and quality, and bread-making properties of wheat depended on the year and location. As the average of field experiments conducted at two locations, the application of S significantly increased the grain yield (r = 0.960). The increasing yields were accompanied by decreasing contents of wet gluten (r = 0.825). However, the significant positive (r = 0.938) effect of the S application on the Gluten index was revealed, which is a good predictor of the baking quality of wheat flour. The S addition by nitrogen fertilization resulted also in a positive shift of the N:S ratio in grains, which is better for the bread-making quality. The significant positive effects of the S application on the dough stability time (r = 0.898) and on the farinograph quality number (r = 0.917) were demonstrated. The loaf volume was significantly (r = 0.842) increasing under the influence of S. Thus, the application of S in parallel with increasing yields improved several bread-making parameters of wheat.

Evaluation of Pomegranate Fruit Powder Coated on Urea as Urea-N Immobilizer and Soil-P Mobilizer

ABSTRACTIt has been shown that pomegranate fruit powder (PFP) has the potential to decrease urea-nitrogen (N) mineralization and improve grain yield of maize, but the mechanisms of this effect are not fully understood. Therefore, the objective of this study was to investigate these mechanisms. For this purpose, an incubation and a pot experiment were conducted, in which four levels of PFP coating equivalent to 0%, 30%, 70%, and 100% (w/w) of urea were studied. PFP had very little effect on nitrification (1.4–2.9%). Mineral N and nitrite (NO2−)–N decreased (23% and 38%, respectively) with increasing PFP application, probably due to N-immobilization or urea hydrolysis inhibition. Biomass and grain yield of maize increased with increasing phosphorus (P)/N ratio of leaf and stem, and decreasing P/N ratio of grain, indicating soil-P-mobilization and soil-N-immobilization during vegetative growth and the inverse, during grain filling by PFP. According to these results, PFP can be introduced as an urea-N immobilizer and soil-P mobilizer.

Microstructures and Mechanical Properties of Extruded Al 7050 Billet and Ring Forged One with Large Scale

The manufacturing process of large scaled Al 7050 alloy is difficult for the occurrence of solidification crack during casting. The aims of this study are the evaluations of microstructure and mechanical properties of extruded Al 7050 billet and ring forged one with large scale. Large scaled Al 7050 billet was casted by direct-chill casting process. The extruded and ring forged specimens were prepared from the casted ingot after residual stress relief and homogenization heat treatment, respectively. Microstructures, hardness and tensile test of the surface, middle and center part of each specimen were performed at room temperature. Sheared and elongated type grains were observed at the edge parts of surface and center area and its aspect ratios of grains were low and similar as 0.21 while that of middle area was closed to 0.92 value in ring forged Al 7050 alloy. The mechanical properties of extruded Al 7050 alloy were superior than those of ring forged one. The hardness values of surface and center part were slightly higher than that of middle part in ring forged Al 7050 alloy.

Detailed modeling of cutting forces in grinding process considering variable stages of grain-workpiece micro interactions

Grinding forces are a key parameter in the grinding process, most previous studies on grinding forces, however, (i) were regardless of grain-workpiece micro interaction statuses and (ii) could only predict average/maximal grinding forces based on average/maximal cutting depths or chip thicknesses. In this study, a novel detailed modeling methodology of grinding forces has been analytically established, experimentally validated and utilised to study a specific issue that previous methods can not address. Based on the proposed method, grinding forces with detailed information (e.g. three components including rubbing, plowing and cutting forces) could be accurately predicted. Except for grinding forces, the proposed methodology also enable the availability of other grinding process details at the grain scale (e.g. the ratios of grains that are experiencing rubbing, plowing and cutting stages to the total engaging grain number). Validation experiment results have proved that, the proposed method could, to a large extent, describe the realistic grinding forces. Based on the proposed method, the effects of grinding conditions (including depths of cut, wheel speeds, workpiece feed speeds and grinding wheel abrasive sizes) on each component of grinding forces (rubbing, plowing, and cutting forces) have been analyzed. Some new findings, which could enhance the existing understandings of grinding forces and guide industrial manufacture, have been gained. The proposed method therefore is anticipated to be not only meaningful to provide a new way to model grinding forces in detail, but also promising to study other grinding issues (e.g. grinding heat, machined surface topography, grinding chatter), especially under the trend of miniaturization and microfabrication where grinding details at the grain scale are highly needed to optimise the micro grinding tool efficiency and micro-grinding accuracy.

Grain Output and Cultivated Land Preservation: Assessment of the Rewarded Land Conversion Quotas Trading Policy in China’s Zhejiang Province

Although it is difficult, many countries are attempting to balance economic development and cultivated land preservation for various reasons. China’s experience is a good illustration of such challenges during rapid economic development and urbanization. The central government of China emphasized the high self-sufficiency ratio of grain and therefore set a bottom-line for the area of cultivated land in order to ensure food security. The State Council of China requires that the area of cultivated land should not be less than 120,000,000 hectares until 2020 through strict land management measures. In view of such stringent regulations, various alternative practices, such as rewarded land conversion quota (RLCQ) trading in Zhejiang Province, have been proposed to satisfy the construction demand while preserving cultivated land. This study empirically investigates the impact of RLCQ trading on cultivated land preservation in terms of grain output. Results showed that RLCQ trading leads to decreased grain production, measured in both total grain output and grain output per hectare, for both buyers and sellers. Furthermore, buyers of land quotas experience a more severe grain reduction than sellers. The findings suggest that RLCQ trading is unfavorable to cultivated land preservation in terms of grain output. Recognizing this dilemma, local governments should improve the land market mechanism to motivate intensive use of existing construction land and consolidation for improving quality of cultivated land.