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Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, cellulose ano-fibril (CNF)/ano-silicon dioxide composites were prepared by mimicking the fast paper-making method. Mechanical property, thermal degradation and moisture adsorption of the composites were studied. The results revealed that tensile strength and modulus decreased as the loading of ano-silicon dioxide increased. The measured density value of CNF was 1 305.04 kg/cm3 while the density of CNF with 20% ano-silicon was only 1 132.9 kg/cm3. Tensile strength of CNF was 120.98 MPa and Modulus was 6.41 GPa. As the loading of ano-silicon dioxide increased, the tensile strength and modulus decreased sharply. When the content of ano-silicon dioxide reached 20%, the tensile of ano-composite was 49.41 MPa and the modulus was 2.96 GPa. The thermal stability of ano-composite was improved after adding ano-silicon dioxide. The onset cellulose decomposition temperature was around 270 °C and weight loss in this period was around 4%. Although the onset decomposition temperature of nanocomposites did not increase, the lower weight loss indicated less initial decompositions in this stage. In addition, as the content of silica became higher, the char residue increased. The amount of dry plain CNF was 23%, noticeably smaller than that of corresponding CNF/ ano-silicon dioxide samples which ranged from 30% and 65%. Degradation models including the Kissinger, modified Coats-Redfern and Flynn-Wall-Ozawa (F-W-O) methods were utilized to calculate the activation energy. The Kissinger method led to an apparent activation energy ranging from 150 to 225 for all films. NFC with inorganic silica normally showed a higher activation energy than the control, high clay content also resulted in high activation energy. Results from the modified Coats-Redfern and F-W-O methods were similar (activation energy ranged from 180 to 220) to the observations. Nano-silicon dioxide provides barrier to the oxygen which leads to an improvement in flame retardant property. Limiting oxygen index of the tested CNF was 21.8 which is similar to normal paper but lower than CNF with ano-silicon dioxide. Limiting oxygen index of the CNF with 20% ano-silicon dioxide was 24.20%. The CNF/ano-silica dioxide composites were placed in a container with relative humidity 95% for 24 hours and moisture content of composites increased as the time continued. Among all composites, CNF/ano-silicon dioxide showed more moisture sensitivity than plaint CNF. The higher the ano-silica dioxide content was, the more moisture was absorbed. The final moisture content (FMC) of CNF was around 20% while the FMC of CNF with 20% ano-silica dioxide was around 26%. Contact angle was used to determine surface wettability of these nanocomposites. The contact angle of plain CNF was 55.9°. As the ano-silicon dioxide content increased, the contact angle of nanocomposites decreased. When the loading of ano-silicon dioxide was lower than 10%, the contact angle of nanocomposite was similar with CNF. However, as the loading of ano-silicon dioxide increased to 15%, the contact angle of the nanocomposite was only 45.4°. When the content of ano-silicon dioxide was 20%, the contact angle decrease to 40.4°. In conclusion, mechanic and water adsorption properties of cellulose ano-fibril were affected by added ano-silicon dioxide amount, but the thermos property of the cellulose ano-fibril/ ano-silicon dioxide was stable. [ABSTRACT FROM AUTHOR]

In order to explore the mechanism of soil reinforcement and slope protection by plant roots, in this paper, the mechanical characteristics of roots on soil stabilization were discussed from the meso angle, and using a CT triaxial apparatus developed at the Yangtze River Scientific Research, a series of unconsolidated-undrained CT real-time triaxial shear test of the non-rooted clay sample and two kinds of Broussonetia papyrifera-rooted clay samples with different root diameters were carried out. Through a quantitative analysis of CT scan data of three sections at the different strain for three kinds of samples, it was found that both the downward section of (mean CT number) ME-ε1 curve and the upward section of (the variance of CT number) SD-ε1 curve of the non-rooted soils had a greater changing amplitude than those of the rooted soils in three different scan layer sections. It indicated that the internal defects of the rooted soil grew more slowly and weakly, the initiation and propagation of internal cracks slower, and the roots resist cracks. This paper focused on the qualitative and quantitative analysis of CT scanning images of the height of a 7/16 cross section at the different strain for three kinds of soil samples. Using the program self-prepared in Matlab software, the CT scan images were binarized, and the statistical crack data of the scan layer section were obtained including the crack rate of cross section, the total crack size in the area near the root and beyond the root respectively, and the length and width of the maximum crack area. Through the comparative analysis of CT scan images evolution under pressure and the statistical crack data of them for the non-rooted soils and the rooted soils, the fundamental differences in destruction process of the soil and crack propagation between the non-rooted soil and the rooted soil were described, thus exposing the crack resistance and the bridging effect of roots. It was concluded that the mesomechanics mechanism of roots reinforcement is mainly the crack resistance and the bridging effect of root on the soil. [ABSTRACT FROM AUTHOR]

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Finite element models, which employ the Drucker-Prager yield criterion, have been developed to simulate the static contact statuses between conical silos and granular materials in 3 forms: the near contact, the sliding contact and the sticking contact. Contact conditions are established when 2 separated surfaces touch at normal direction while maintaining tangential relative movement. In general physical meaning, the surfaces in contact status have the following characteristics: 1) No penetration between each other; 2) The normal pressure and the tangent friction force may be transferred during contact; 3) Generally the normal pulling force cannot be transferred when surface separation occurs. Due to the symmetric property of conical structures, simplified two-dimensional contacting simulations are carried out in this paper, nonlinear finite element software ANSYS is used and the contacting surfaces between granular materials and conical silos are defined with rigid-to-flexible surface-to-surface contact pair. The target surfaces of conical silos are modeled with TARGE169 element and the contact surfaces of granular materials are modeled with CONTA171 element. During finite element analysis, conical silos and granular materials are meshed with two-dimensional solid element, PLANE42. The static contact statuses are investigated with conical silos containing different granular materials. The silo geometries vary at a dip angle of 20°, 33.7° and 45°. Sunflower seeds, corn, coal, rounded gravel and wheat are selected as the granular materials. Results show that the mechanical properties of granular materials (including bulk density, elastic modulus, Poisson's ratio, dilation angle, internal friction angle, cohesion) and silo designs (especially dip angle) have significant effects on the contact statuses at the interface between conical silos and granular materials: 1) For various granular material, 3 contact statuses, i.e. the form of near contact, sliding contact and sticking contact, can be found between granular materials and conical silo walls; 2) The contact statuses between conical silos and granular materials do not depend on (or not mainly depend on) any mechanical property of granular materials. The contact statuses are a combined effect of all mechanical properties of granular materials. Those granular materials with very small dilation angle may have the near contact statuses. Those granular materials with higher cohesive force usually present a smaller sticking contact area, and those granular materials with higher elastic modulus and bulk density usually present a larger sticking contact area than those with opposite material properties; 3) With the decreasing of conical silo depth, the near contact area disappears, the sliding contact area decreases and the sticking contact area increases. 4) Under the sliding contact status, the friction energy dissipation is mainly due to the relative motion between contact surfaces. Under the sticking contact status, the friction energy dissipation is mainly due to the elastic deformation because of the contact. The greater the sticking contact area, the more difficultly the silo discharges. The greater the sliding contact area, the more seriously the silo internal surfaces could be damaged. Since larger sticking/sliding contact area inevitably causes unloading difficulties or friction damage, contact statuses between granular materials and conical silos should be optimized in the silos design in order to boost storage efficiency. [ABSTRACT FROM AUTHOR]

Wood-plastics composite (WPC) is a new kind of composite material, booming at home and abroad in recent years. It includes 2 types: one is the composite produced directly using extrusion and injection methods based on biomass materials such as wood powder, bamboo powder and hemp fiber; the other is based on carbonized biomass materials, which is fabricated by carbonizing biomass materials at high temperature and then compounding with polymer. The former has been studied in detail, but the latter is scarce. So in this paper, we prepared the charcoal/epoxy composites using compressing method. The effects of charcoal content on the mechanical properties and the heat resistance of charcoal/epoxy composites were investigated using scanning electron microscope (SEM), material testing machines, dynamical thermal mechanical analyzer (DMA) and Vicat softening temperature (VST) measuring instrument. The epoxy, diluents and curing agent at weight ratio of 3:2:5 were used to yield charcoal/epoxy composites. The weight fraction of charcoal in composite was set to 5%, 10%, 20%, 30% and 40%, and the curing temperature and curing time were 100°C and 3 h, respectively. The results showed that the charcoal in composites, acting as physical cross-link, could improve the mechanical properties of epoxy resins. The flexural strength of composites increased from 10.1 to 38.2 MPa as charcoal loading increased from 0 to 10%, but it started to reduce when charcoal loading exceeded 10%. Like flexural strength, the impact strength of composites also increased from 8.7 to 20.5 kJ/m2 within 10% charcoal loading. However, the flexural modulus of composites increased with charcoal loading increasing till 30%. At high charcoal content, due to the poor wetting properties of charcoal, the mechanical properties of composites began to decrease. The DMA results confirmed that the glass transition temperature of epoxy resins was elevated from 37.5°C to 60.5°C as charcoal loading increased from 0 to 10%, indicating strong interaction between epoxy and charcoal. When charcoal loading exceeded 10%, the glass transition temperature started to decline, but it was still higher than that of net epoxy resins. The addition of charcoal improved the heat resistance of epoxy composites, and the VST of charcoal/epoxy composites increased linearly with the increasing of charcoal loading. The 10% charcoal made the VST of epoxy resins increase from 81.2°C to 126.6°C. Further elevating the charcoal loading caused the VST of composites to exceed 200°C. The results indicate that the charcoal/epoxy composites have better mechanical properties and heat resistance with the charcoal loading of 10%. [ABSTRACT FROM AUTHOR]

In fact, the ultimate properties of wood-plastics composites (WPCs) not only rely on the structure, composition and morphology, but also depend on the processing conditions, such as processing temperature, pressure (blending rate ) and time. Due to the degradation of bamboo powder under high processing temperature or long processing time, this paper studied mainly the effects of blending rate on the mechanical and rheological properties of low density polyethylene (LDPE)/bamboo powder composites, which were fabricated by the melt compounding method with the compounding temperature of 170 °C and 10 min, by using the rotational rheometer, material testing machine and scanning electron microscope (SEM). The maleic anhydride grafted polyethylene (MAPE) was selected as the compatibilizer for LDPE and bamboo powder. The mass proportion of LDPE, MAPE and bamboo powder was set to 65:5:30. The mechanical properties, water absorption and morphology of LDPE/bamboo composites were investigated in detail by changing the blending rate (40, 75 and 100 r/min). Before experiments, all the materials were dried in vacuum oven at 70 °C for 24 h. The addition of bamboo powder improved the tensile strength and flexural strength of LDPE, which were increased by 28% and 115% respectively compared to neat LDPE, but reduced the impact strength of LDPE. The tensile strength and flexural strength of the LDPE/bamboo composites decreased as the rotation rate increased from 40 to 100 r/min. The flexural modulus of LDPE/bamboo composites decreased from 48.45 to 40.75 MPa as blending rate increased from 40 to 100 r/min, and the highest flexural modulus increased by 238% compared to neat LDPE (14.35 MPa); however, the notched impact strength of LDPE/bamboo composites increased from 12.8 (40 r/min) to 18.27 kJ/m² (100 r/min), lower than that of neat LDPE (29.19 kJ/m²). For rheological experiments, the LDPE/bamboo composites exhibited shearing thinning behaviors, and at the same frequency, the complex viscosity of LDPE/bamboo composites decreased as blending rate increased, indicative of the improvement in processing performance; the storage modulus of LDPE/bamboo composites also reduced as blending rate increased, indicating the rigidness reduction, and this result was consistent with the results from mechanical properties. Also, the water absorption of LDPE/bamboo composites decreased from 0.89% (40 r/min) to 0.59 % (100 r/min). The reason was that the high blending rate caused the LDPE and bamboo powder to compound more evenly and the interfacial performance between LDPE and bamboo power was improved. The SEM results showed that at low blending rate (40 r/min), the bamboo powder surface was only coated with a thin layer of resin, and the interface between LDPE and bamboo powder was very clear, indicative of poor interfacial properties, and no plastic deformation was observed; at high rotation rate (100 r/min), bamboo powder was coated with a thick layer of polymer resin, exhibiting good interface performance with LDPE, and what's more, the big plastic deformation was observed in matrix, suggesting LDPE/bamboo composite (100 r/min) exhibited a good toughness. The above results confirmed that elevating blending rate could improve the toughness and reduce the water absorption of LDPE/bamboo composites, and in our experiments, the LDPE/bamboo composites, produced by blending rate (100 r/min), exhibited the better impact strength and water absorption. [ABSTRACT FROM AUTHOR]

Sweet potato is a crop which is drought-resistant, tolerant of poor soil, and owns increasingly enormous potential. It is an important foodstuff, a raw material for starch industry, a kind of health food to prevent cancer and a new raw material for energy as well. The sweet potato planting area in China per year on average is usually 3 667 000 hectares, accounting for 45% of the world's planting area. As sweet potato vines are very long and broomy, the vines must be cleaned up before sweet potatoes are harvested, otherwise are unable to be harvested. Vine crushing and returning machine is usually the dominant form adopted to clean sweet potato vines internationally, but the problems existed in this type of machine were obvious such as low smashing proportion and more stubble residue on the top ridge. New problems have been brought by long stubble such as blocking, larger load and worse smooth working property. Aiming at these problems, the machinery and agronomy should be combined, in order to prove mechanical properties of sweet potato vine and stalk during harvest and working quality of sweet potato vine crushing and returning testing machine. In this paper, the types of fresh purple sweet potato Ningzi 1 and Ningzi 2 in Nanjing, Jiangsu Province were regarded as the tested subject, the electronic universal testing machine, electric drying oven with forced convection, and sweet potato vine crushing and returning testing machine etc. were applied, and the change of moisture percentage and shear strength of sweet potato stalk during harvest were studied. The results showed that at the beginning of experience harvest period, when the percentage of moisture were 81.5% and 78.1%, the shear force were 90.1 and 94.8 N, respectively, during 18 testing days the moisture percentage of sweet potato stalk reduced by 14.8% and 13.97%, respectively, but the shear force of stalk increased by 36.3 and 37.5 N respectively, which showed that the moisture percentage of sweet potato stalk was lower and the shear force was larger as the growth time of plants went on. The internal relations between mechanical crushing quality and percentage of moisture, shear strength were revealed: during the testing period of 18 days, the qualified rates of vine's crushing length for sweet potato type Ningzi 1 and Ningzi 2 dropped by 6.3% and 6.7% respectively, stubble length on top ridge increased by 3.6 and 4.4 cm respectively, which showed that with the increasing of the growth period and the rising of stalk's shear force, the working quality of sweet potato vine crushing and returning machine declined. The quadratic function regression equations on the change between shearing force and moisture percentage of the two types of fresh purple sweet potatoes' stalk were obtained with Matlab when the percentage of moisture was 86.92%-70.08%, and the fitting coefficient of determination R² both reached above 0.99. From the point of increasing the quality of mechanical smashing and mechanical work, it was put forward that the most suitable time of mechanical crushing for the two kinds of purple sweet potatoes during harvest was about 6-8 days, which was a relatively short time. The results offer the direct basis for parameter design of new sweet potato vine crushing and returning testing machine such as machine speed, cutter linear velocity, and also provide the important reference for the selection of suitable harvest period and cultivation agronomic research that fits for machinery operations. [ABSTRACT FROM AUTHOR]

Zein is the major storage protein of corn and comprises 45%-50% of total protein in corn, and possesses good property of forming film in virtue of abundant sulphur amino acids. High content of hydrophobic amino acid grants hydrophobicity to zein film, but film made of natural casting retains its crispness. In order to improve the flexibility of zein film, plasticizers are added into the film solution. Though plasticizers can significantly enhance mechanical properties of zein film, they affect their security and edibility. Equipments such as pulsed electric field used in processing of casting can improve the properties of zein film by taking appropriate measures, without affecting the security and edibility of zein film. But the popularization of these equipments is hindered for their high price. In this paper, the combination of DC power (DYY-8C, Beijing) and conducting glass coated with indium tin oxide was used to set up paralleled uniform electric field, and then the electric field was introduced into the processing of zein film. This method was of simple equipment, easy operation and good selectivity. Coupled with the paralleled uniform electric field (1-5 A/m²), the soft zein films with complete shape were obtained by casting. The properties of zein film such as tensile strength, elongation at break, water vapor permeability and water absorption were measured and analyzed to evaluate the influence of the paralleled uniform electric field on zein film. Meanwhile, thermostability difference between films before and after treatment was studied by differential scanning calorimetry. By analyzing the data, tensile strength and elongation at break increased with the increase of electric current density while water vapor permeability and water absorption decreased. When electric current density was at 4 A/m², properties of zein film were optimal. Tensile strength and elongation at break reached the maximum value (73.09 MPa and 9.68%, respectively); water absorption and water vapor permeability reached the minimum value (14.87% and 2.54*10-8 g-m/(m².h.Pa), respectively). Contact angle declined slightly (within 5°), and tended towards stability when electric current density was above 2 A/m². Experiments indicated that the presence of electric field force facilitated interaction between zein molecules, and these molecules were organized in a network pattern contributing to the improvement of mechanical properties. Meanwhile, polar amino acid residues tended to move forward to the topside of the network, resulting in the slight decline of contact angle. There existed significant difference among the data obtained from the experiments by Duncan analysis (P<0.01). During the processing of zein film, no hazardous substance was added into the film solution. By adjusting the electric current density, film or edible packing material with flexibility, fixed shape, mechanical strength, certain mechanical properties or contact angle can be obtained, which are biodegradable, edible and non-toxic toward humans and environment. [ABSTRACT FROM AUTHOR]

In order to reduce the breakage rate of the broccoli seedling during mechanized planting and to avoid the transplanting failure caused by the discordance between planting nozzle and seedling while the planting nozzle has arrived at the planting location but the seedling has not slipped to the bottom of planting nozzle, the orthogonal experiments based on agronomic requirements has been carried out in this paper. The volume of soil block (represent plate size), seedling age, and moisture content of soil blocks are selected as the experimental factors. Every factor has three levels. One experiment has been carried out to test the compressive strength of soil blocks under different schemes. Through using the universal material testing machine, the relationships between compressive force and compressive amount have been obtained and expressed as curves. In order to analyze these curves, the compression elasticity of the soil block has been proposed, which was defined as the straight slope between point D (starting point of linear elastic) and point E (yield point). Then, several sets of compression elasticity and yield limit under different schemes have been obtained. Analysis results show that the compression elasticity increases at first, then decreases with the reduction of the volume of soil blocks, while the yield limit decreases with the reduction of the volume of soil blocks. Both of them have no significant relationship with seedling age, but decrease with the increase in moisture content. Another experiment was carried out to test the motion resistance coefficient between seedling and planting nozzle. The broccoli seedling was put on an incline, then the process of broccoli seedling sliding along the incline was recorded by the high-speed camera. The sliding acceleration along the incline of broccoli seedling was obtained by video processing technology. Afterwards, the motion resistance coefficient was derived by using Newtonian mechanics theory. Analysis results show that the motion resistance coefficient decreases with the reduction of soil block volume, and increases with the increase of both the seedling age and moisture content. The mechanics model of the colliding process between seedling and planting nozzle has been built, and the highest relative speed allowed was obtained from the model. In order to avoid the breakage of seedling, meanwhile the motion resistance coefficient shouldn't be too high, a comprehensive scoring method was applied to evaluate the combinations of soil block volume, seedling age, and moisture content. Four combinations were chosen by comparing the scores. In order to achieve the best combination, the field planting simulation experiment was conducted. This experiment was done indoors by using a rotating circular soil tank driven by the friction of tires. Breakage rate and rewind rate were obtained from this experiment. The best combination that is suitable for mechanized planting of broccoli seedling was obtained: medium soil block (128 holes plate), 2-3 leaves, and water content at 63%. This study provides reference for the design of planting mechanism. [ABSTRACT FROM AUTHOR]

Due to advantages in being lightweight, inexpensive, biodegradable, and an easy process, composite materials with plant fiber filler have been widely applied in industry, agriculture, national defense, and other fields. In this study, flowerpots in a friendly environment were moulding-prepared through the procedure of mixing and hot-pressing in an oil hydraulic machine. The flowerpots were made of rice husk, rice husk power, and modified urea-formaldehyde resin. The rice husk or husk power components were added as reinforcing agents, while the resin component was added as a matrix material. The purpose of this paper is to discuss the influence of the dosage of urea-formaldehyde resin (UF), modified urea-formaldehyde resin (SUF), ratio of rice husk and rice husk power, and the wet cycle treatment on the mechanical property of the flowerpots. Thermal stability and microstructure of the flowerpots treated with the rewetting method were analyzed by Thermo-gravimetric Analysis (TGA) and a Scanning electronic microscope (SEM). The results showed that the mechanical properties of the flowerpots could be improved by applying modified urea-formaldehyde resin or adding rice husk power. With the dosage of modified UF, modulus of rupture, modulus of elasticity, and tensile strength of the straw flowerpot all improved. The modulus of rupture, modulus of elasticity, and tensile strength were 75.48 MPa, 16.06 GPa, and 17.44 MPa, respectively, when the ratio of reinforcing agent and matrix material was 1:0.5 (w/w) and the ratio of unbroken rice husk and rice husk power was 3:7 (w/w). Wet cycle treatment led mechanical parameter values of all formula specimens to decline in different degrees, with tensile strength and maximum bending deformation of SUF-pot specimens dropping most significantly. Using rice husk as the reinforcing agent (RH) in the wet cycle treatment resulted in the modulus of rupture, modulus of elasticity, and tensile strength of UF/RH to drop to 21.97%、 24.91%、 and 15.09%, while SUF/RH dropped 9.92%、 15.37%, and 30.10%, respectively. TGA analysis showed that the pyrolysis rate and mode of the straw flowerpot materials by wet cycle treatment had been slightly changed; namely materials mass loss rate was reduced and maximum thermal decomposition temperature increased. The SEM graphs of the composites fractured surface showed that the surface of the flowerpots treated by wet cycling had become rough. Some pieces of rice husk divorced from modified urea formaldehyde resin were clearly visible. Obviously, the interface between rice hull and SUF had become weak. This test showed that the straw flowerpots prepared with SUF resin were less stable than those prepared with UF resin, which implied that the former was liable to degrade. In regard to the production costs, the straw flowerpots are more than 10% lower than the plastic flowerpots. Substitution of plastic flowerpots with straw flowerpots would not only be beneficial in reducing white pollution from the use of plastic products, but also in promoting comprehensive utilization of the crop straw. Therefore, there will be an excellent market prospect of straw flowerpots. [ABSTRACT FROM AUTHOR]