Effect of Greenhouse Cladding Materials and Thermal Screen Configuration on Heating Energy and Strawberry (Fragaria ananassa var. “Seolhyang”) Yield in Winter

Strawberry cultivation depends on environmental factors, making its cultivation in the greenhouse a challenge in the winter. This study investigated the most appropriate greenhouse cladding material and thermal screen configuration for strawberry production in the winter by considering greenhouse air temperature, relative humidity (RH, vapor pressure deficit (VPD, and solar radiation (SR). Two gothic greenhouses with different cladding materials and thermal screen configurations, namely, the single-layer greenhouse and double-layer greenhouse, were used for strawberry cultivation. The greenhouse microclimate was controlled by natural ventilation aided with circulating fans and boilers. Strawberries were planted on 5 greenhouse benches, 660 stands per greenhouse. Daily environmental parameters were recorded and processed into daytime and nighttime. The impacts of cladding material-thermal screen configurations on temperature, RH, VPD, and SR, and the subsequent effect on strawberry yield in both greenhouse systems, were evaluated. Comparing the environmental parameters recorded in the single-layer and double-layer greenhouse showed that VPD and SR were significantly different in the daytime, whereas RH and VPD were significantly different in the nighttime. The post hoc test further showed that RH, VPD, and SR in both greenhouses were significantly different. The significant difference in RH and VPD can be attributed to the inner layer of polyethene in the double-layer greenhouse, which sealed up the pores of the thermal screen, resulting in humidity buildup, causing a lower VPD than in the single-layer greenhouse. The single-layer greenhouse yield was 14% greater than the double-layer greenhouse yield and can be attributed to the higher daytime VPD and lower RH achieved in the single-layer greenhouse at night. The study established that though the single-layer greenhouse system was cost-effective regarding construction, the operating cost of the single-layer greenhouse was higher than that of the double-layer greenhouse.

Solar Radiation Transmittance Characteristics of Textile Woven Fabrics suitable for Greenhouse covering Materials

Nowadays, greenhouse covering materials have a vital role in terms of a protective cultivation process. Many farmers use polyfilms, rigid or semi-rigid plastic panels, and glazing materials as greenhouse covering materials in the present scenario. However, these plastic covering materials are known for their high cost, short service life, and cause of harmful environment. Solar transmittance property is one of the main criteria for choosing any greenhouse covering materials. This study prepares various woven fabrics made of polyester, cotton, and polyester–cotton blend yarns. Their solar transmittance characteristic is analyzed to develop fabric and compare it with a polyethylene film already used as a greenhouse cladding material to substitute for plastic materials. The solar transmission of polyester fabric is achieved as high as 70% in the photosynthesis active radiation, suitable for a commercial greenhouse material. In addition, the polyester fabric has tensile strength and extension much higher than that of commercial plastic greenhouse material.

Arc Welding-Laser Shock Forging Process for Improving the Mechanical Properties of the Fe-Cr-C Cladded Layer

While parts can be repaired via arc welding (AW), it is usually necessary to add some types of excitation method to improve the mechanical properties of the cladded layer. Here, the arc welding-laser shock forging (AW-LSF) was used to repair Q235 steel pipes (Fe-Cr-C alloy was used as the cladding material). The effects of the welding current (WC), welding speed (WS), and laser shock frequency (LSF) on the geometry and microhardness of the weld bead were studied. The AW-LSF and AW repair processes were compared. The results demonstrate that the bead width (W) and penetration depth (D) increase with the WC, while the weld height (H) decreases with the WC. The H, W, and D all decrease with the WS; W and D increase with the LSF; and H decreases with the LSF. As the WC increases, the hardness of the fusion zone (FZ) and partial fusion zone (PFZ) decreases significantly, while the hardness of the heat-affected zone (HAZ) remains nearly unchanged. As the WS increases, the hardness of the PFZ decreases, while the hardness of the FZ and HAZ remains nearly unchanged. With the increase of the LSF, the hardness of the PFZ, FZ, and HAZ increases. Compared with AW, the AW-LSF can reduce the cladded layer crystal grain size, increase the hardness, and improve the sliding wear resistance.

Impact of Radiation-Induced Microstructures on the Integrity of Spent Nuclear Fuel (SNF) Elements in Long-Term Storage

The current safety concept provides for a period in the range of 40 years for interim storage of spent fuel elements. Since the requirement for proof of safety for to up to 100 years arises, the integrity of the spent fuel elements in prolonged interim storage and long-term repositories is becoming a critical issue. In response to this safety matter, this study aims to assess the impact of radiation-induced microstructures on the mechanical properties of spent fuel elements, in order to provide reliable structural performance limits and safety margins. The physical processes involved in radiation damage and the effect of radiation damage on mechanical properties are inherently multiscalar and hierarchical. Damage evolution under irradiation begins at the atomic scale, with primary knock-on atoms (PKAs) resulting in displacement cascades (primary damage), followed by the defect clusters leading to microstructural deformations. In this context, we have developed and applied a multiscale simulation methodology consistent with the multistage damage mechanisms and the corresponding effects on the mechanical properties of spent fuel cladding and its integrity. Within the improved hierarchical modelling sequence, the effect of the radiation field on the fuel element cladding material (Zircalloy-4) is assessed using Monte Carlo methods. A molecular dynamics method is employed to model damage formation by PKAs and primary damage defect configurations. The formation of clusters and evolution of microstructures are simulated by extending the simulation sequence to a longer time scale with the kinetic Monte Carlo (KMC) method. Transferring the calculated radiation-induced microstructures into macroscopic quantities is ultimately decisive for the structural/mechanical behaviour and stability of the cladding material, and thus for long-term integrity of the spent fuel elements. Results of the multiscale modelling and simulations as well as a comparison with experimental results will be presented at the conference session.

Sensitivity analysis of hygrothermal performance of wood framed wall assembly under different climatic conditions: the impact of cladding properties

One of the parameters that influences the moisture performance of the wood framed wall assembly is the material properties of exterior cladding. The uncertainties of its properties, would result in a range of wall performance. The objective of this study was to investigate the impact of uncertainties in cladding material properties on moisture performance of wood framed wall assembly under different climatic conditions. A wood framed (2×6 wood stud) wall with exterior brick cladding was simulated assuming 1% rain leakage deposited on the exterior side of sheathing membrane. A parametric study was carried out to analyze the impact of the cladding properties on the moisture response of OSB. The simulations were conducted in five different cities located in different climate zones across Canada. The aim was to identify the most influential cladding property on the moisture response of OSB, i.e., mould growth index and moisture content, to the varying cladding properties under different climatic conditions i.e., different cities under historical and future conditions. In general, it was found that liquid diffusivity is the parameter that has the most influence on moisture response of OSB in all the five cities. Also, the significance of this influence varies depending on the climatic conditions.

Effect of aging of Cladding Material on Crop Yield under Greenhouse Cultivation

Agriculture is the basis of our economic activity. For improving agricultural production greenhouse technology was developed to prevent adverse climatic conditions. Even though higher yield and profit were obtained from greenhouse production compared to open field cultivation farmers were not satisfied with this technique due to the drastic reduction of crop yield with the aging of cladding material. To test this, an experiment was conducted in the instructional farm of Kelappaji College of Agricultural Engineering and Technology (KCAET), Tavanur, Kerala during the period from April to June 2021. Amaranthus variety CO1 was planted inside two greenhouses where one is having cleaned cladding material and the other is an old one. Microclimatic parameters and the biometric observations of crop in both conditions were compared. Mean monthly values of temperature and light intensity were higher inside the cleaned greenhouse than the old one while relative humidity was higher inside the old greenhouse. Crop growth parameters were higher inside the cleaned greenhouse than the old one except the internodal length. From this study, it was clear that the aging of cladding material has a significantly higher influence on crop performance under greenhouse.