Design of Diversified Intelligent Control System for Energy-saving Optimization of Solar Greenhouse in North China

Intelligent greenhouse can promote the development of modern agriculture, realize the high quality and high yield of crops, and also bring greater economic benefits. In accordance with the climate conditions in northwest China, a set of intelligent control system for diversified environment of solar greenhouse was designed. The system divides the annual greenhouse control into six stages according to the optimal energy saving. It uses modern detection technology to collect the greenhouse environmental temperature, environmental humidity, soil humidity, CO_(2) concentration and illumination parameters under different working modes. It uses programmable logic control technology to realize the data processing of various parameters and the action control of rolling film, wet curtain fan and other actuators. It uses KingView monitoring software to realize the monitoring and manual control of greenhouse environment parameters. The operation results indicate that the control system runs stably and basically meets the control requirements.

Determination and Analysis on Heat of Trapezoidal Soil Wall in Solar Greenhouse

Solar greenhouse with trapezoidal soil wall is widely used due to its good heat retaining property and cost efficiency.In this study, solar irradiance, heat flux and the temperature 0.05 and 0.3 m from the inner surface of the wall at the upper,middle and lower measured positions were determined to study the thermal condition of the trapezoidal soil wall in solar greenhouse. The results showed: first, both the solar irradiance and the temperature increased from the upper to the lower measured position. Second, the heat absorption also increased from the upper to the lower measured position. In clear day, the heat absorption at the three measured positions accounted for 31.4%, 32.6% and 36.0% of the total amount of heat absorption of the whole wall. In cloudy day, the heat absorption at the three measured positions were 0.249, 0.370 and 0.440 MJ/m^2, which accounted for 23.5%, 35.0% and 41.4% of the total amount of heat absorption of the whole wall. When P<0.05, the heat fluxes were strikingly different between the upper and lower measured positions. But when P<0.01, the heat flux had no big difference among the three measured positions. Third, in clear day, the heat emission was the biggest at the middle measured position and smallest at the upper measured position. The heat emission at the three measured positions accounted for 27.5%, 36.7%and 35.8% of the total amount of heat emission of the whole wall. And the heat emission between the middle and lower measured position was not strikingly different. In cloudy day, the heat emission was the biggest at the lower measured position and smallest at the upper measured position. The average heat emission at the three measured positions accounted for 26.1%,36.4% and 37.4% of the total amount of heat emission of the whole wall. Fourthly, correlativity, the solar irradiance directly influenced the heat absorption and had close relation with heat emission. And heat emission again had close relation with the temperature in the greenhouse. Solar irradiance directly influences the thermal condition of a solar green house. It is hoped that this study can be referred to optimize trapezoidal structure and to improve the thermal conditions of the solar greenhouse.

Control Technology of Solanaceous Vegetable Diseases in Solar Greenhouse in Shandong Province

The occurrence of major diseases of protected solanaceous vegetables in Shandong Province,including tomato Pythium root rot,tomato Phytophthora root rot,tomato Pythium basal stem rot,tomato stem blight,sweet pepper root rot,pepper blight and eggplant stem rot,are studied,and corresponding comprehensive control measures are put forward.

Analysis of Variation Characters and Prediction Model of Soil Temperature in Solar Greenhouse

[Objective] The aim was to study the soil temperature changes and its forecast model in greenhouse by solar heat. [Method] Annual and daily variation characters of soil temperature were analyzed in this paper by using the observation data of air temperature out of solar greenhouse and different layers soil temperature in it. The soil temperature (daily maximum, daily minimum and daily mean) forecasting models were also studied. Simulation and test were conducted to the forecast model of soil temperature in the greenhouse. [Result] The annual changes and daily changes of soil temperature of each layer in the greenhouse were in single peak curve. The lower layer temperature changes were smaller than the upper layer. The soil temperature of each layer within the greenhouse was closely related to the relevance of same type temperature outside the greenhouse of the day. Taking the average daily temperature, daily maximum temperature and daily lowest temperature of the day and the day before as forecast factors, soil temperature forecast model of different layer of same type within greenhouse was constructed. The simulation outcome of average daily temperature of each layer within the greenhouse was better than the simulation outcome of highest temperature of corresponding layer, worse than the simulation of lowest temperature of corresponding layer. The highest temperature of lower soil and daily temperature of soil were better than the upper layer. The simulated soil temperature was much more close to the observation when the observation was during 15-30 ℃. In other interval, it was lower than the observation. [Conclusion] The study offered theoretical reference for the growth environment of sunlight greenhouse plantation.

Two-stage seedling cultivation method for sweet peppers combining closed plant factory and solar greenhouse

This study introduced a two-stage cultivation method for sweet pepper seedlings, integrating the strengths of a closed plant factory and solar greenhouse, to mitigate the environmental constraints in Northeast China during the early spring season. In the first stage, seedlings were cultivated in a closed plant factory, followed by a second stage in a solar greenhouse. Four treatments- T1 (9 and 36 d), T2 (12 and 33 d), T3 (15 and 30 d), and T4 (18 and 27 d) - were designed for the first and second stages, respectively, with solar greenhouse-only approach serving as the control (CK). The findings reveal that the two-stage methodology significantly outperformed the control across multiple metrics, including seedling health index, chlorophyll content, photosynthetic capacity, yield, etc. Specifically, T3 emerged as optimal, boosting the health index by 38.59%, elevating chlorophyll content by 39.61%, increasing net photosynthesis by 34.61%, and augmenting yield per plant by 40.67%. Additionally, T3 expedited the time to harvest by 25 d compared to the control. Although the seedling cost for T3 was 0.12 RMB yuan higher, the benefits offset the additional investment. In conclusion, the two-stage cultivation method effectively leverages the advantages of both closed-plant factories and solar greenhouses, resulting in superior seedling quality compared to using only solar greenhouses. It offers a practical and economically viable solution for enhancing the quality and yield of sweet pepper seedlings, thus contributing to the progress in the field of facility seedling cultivation research.

Simple model for predicting hourly air temperatures inside Chinese solar greenhouses

For an efficient energy greenhouse,temperature is the most important climate parameter,which not only affects crop growth and health but also determines the management of energy consumption.So reliable monitoring of temperature is of great significance,and often hourly values are required.However,due to the low level of automation for Chinese solar greenhouse,the loss or poor quality of climate data often occurs.In order to accurately supplement the missing data,as well as for the generation of future temperature,a 24-hour indoor temperature prediction model was established.It uses a piecewise Bezier curve equation that takes the characteristic temperature as the control point which was determined by the outside weather recording.The 130 d of observed hourly temperature data were used to build and validate the model,and the results showed that the temperature model proposed was accurate and sufficient for the simulation of the trend curve of hourly temperature change inside a solar greenhouse.(EF=0.98,R2=0.89).After validation,this temperature model proposed can be useful for the quantitative analysis of crop growth and optimal management.

Temperature variations inside Chinese solar greenhouses with external climatic conditions and enclosure materials

Chinese solar greenhouses enable the extension of the crop growing season in the cold climate in Northern China with little or no additional heating.The temporal variations of the air temperatures inside solar greenhouses located at three cities in North,Northeast and Northwest China were predicted by CFD simulations of the greenhouse systems using typical meteorological data.The predicted temperatures based on the meteorological data in Shenyang are quite similar to the measured temperatures.The results also show that the external air temperatures and solar radiation fluxes play more important roles for the inside temperatures as indicated by the highest inner temperature in the morning on Feb.18 and from 10:00 to 14:00 on Feb.19 in Beijing and by the predicted temperatures inside the greenhouse being higher in Lanzhou than those in Shenyang and Beijing during most of the day.The average daily temperature inside the greenhouse in Lanzhou was nearly 3.5℃higher than that in Shenyang.Predicted air temperatures for various wall designs show that for single walls,the daily average interior temperatures in the aerated concrete wall greenhouse were higher than those in the brick wall and reinforced concrete wall greenhouses.However,the air temperature fluctuations were lower in the reinforced concrete wall greenhouse due to greater thermal storage capacity.The results also show that the temperatures in the layered wall greenhouses are quite similar,which coincides with the experimental results。

Improved root zone temperature buffer capacity enhancing sweet pepper yield via soil-ridged substrate-embedded cultivation in solar greenhouse

A novel soilless cultivation method,called as soil-ridged substrate-embedded cultivation(SSC)was invented,and an experiment was designed to investigate root zone temperature and production efficiency of sweet pepper cultivated by two SSC patterns,i.e.,SSC-P(polyethylene groove inserted)and SSC-W(wire-mesh groove inserted),and also other two cultivation methods,i.e.,soil ridge(SR)and naked polyethylene groove(PG).Results showed that PG,SSC-P and SSC-W increased the average minimal root zone temperature by 1.01℃,0.75℃,and 1.16℃ compared to SR(16.33℃)during March 16-20,2015.During June 1-5,SSC-P and SSC-W decreased the average maximal root zone temperature by 1.28℃ and 1.29℃ compared to SR(34.99℃),while PG increased it by 1.44℃.PG,SSC-P,and SSC-W decreased the differences of average daytime and night time temperatures by 1.34℃,2.13℃,and 2.88℃ compared to SR(4.56℃)during early stage.However,SSC-P and SSC-W decreased temperature differences of average daytime and night time by 0.9℃ and 1.07℃ compared to SR(0.95℃)during later stage,but PG improved by 2.85℃.Temperature difference of daytime and night time of SSC-W was minimal,and the temperature difference between the diurnal highest and the lowest temperature of SSC-W was also minimal.The buffer capacity of SSC-W was slightly better than that of SSC-P.SSC-W significantly improved the growth of sweet pepper compared to SR.Similarly,fruit yield per square meter of sweet pepper cultivated on SSC-P and SSC-W improved by 21.24%and 50.33%,respectively compared to SR(3.06 kg/m^(2)),while PG lowered the yield by 13.72%.SSC-W was a better SSC pattern compared with SSC-P in terms of production efficiency.

Analysis of microclimate characteristics in solar greenhouses under natural ventilation

The solar greenhouse is a typical greenhouse type in northern China.It provides a favorable environment for the growth of various plants and extends cultivation periods for almost a whole year to achieve a high yield.However,indoor environmental control is primarily based on growers'experience,and the objective test data required for the complex climate control and management of greenhouses are lacking.The present study used three greenhouses in northwest China as research objects:one greenhouse with mature plants(GH-M),one greenhouse with young plants(GH-Y)and one greenhouse without plants(GH-E).Field tests were performed to investigate microclimate characteristics,such as indoor air temperature,relative humidity,and solar radiation under natural ventilation.The results showed that the maximum temperature difference reached approximately 8.2℃in the vertical direction,and semiempirical equations for the normalized temperature distribution were obtained.The soil temperature remained constant at a certain depth(0.4 m).The distribution of the relative humidity and solar radiation was analyzed.The current study is helpful for growers to develop better greenhouse climate control strategies for management practices.

Comprehensive evaluation of combining CFD simulation and entropy weight to predict natural ventilation strategy in a sliding cover solar greenhouse

This study proposed a comprehensive evaluation system to incorporate the contribution of both numerical simulation and statistical decision theory in ventilation performance assessment.A high-resolution model based on the finite volume approach was established to analyze the influence of rotation angles(i.e.,side vent flip angle and roof vent flip angle)of the rack-and-pinion ventilated structure on the greenhouse microclimate.The water circulating system and tomato seeding canopies were considered.Heat removal efficiency and mean age of air were employed as quantitative attributes to reflect the internal thermal environment and the airflow organization in the sliding cover solar greenhouse.The simulation model was verified with the temperature profile measured and the average relative error was 1.74%.The results demonstrate that the rotating angles of ventilation schemes have a substantial impact on the microclimate and inhomogeneity of the tomato seeding canopies.The results suggest the average velocity and its inhomogeneity are the crucial predictors,and their entropy weight values are 0.231 and 0.218,respectively.The relative degree of membership of the side vent flip angle of 45°is 36%and 97%higher than that of the side vent flip angle of 35°and the side vent flip angle of 25°,respectively.This study can provide a reference to evaluate the ventilated strategies of the sliding cover solar greenhouse for the regional and central government.

Effects of different root zone heating systems on the microclimate and crop development in solar greenhouses

Heating greenhouse is indispensable for plant development particularly in winter when the air temperature is lower.In that sense,root zone heating is more energy-saving than traditional air heating.The current work was devoted to the study of the effect of two root zone heating systems based on carbon crystal electrothermal film and low temperature hot water pipe on the microclimate and tomato yield in solar greenhouse.And their performance was tested in the coldest period of winter in Yongqing County of Hebei Province.The results showed that the use of root zone heating system can improve the average substrate temperature by 6.8℃.This microclimate improvement had a positive impact on tomato production.The output per square meter has increased by 19%compared to the unheated.It was also noted that the presence of root zone heating leads to a decrease in the development of disease in heated areas.Based on these results,the root zone heating system can be an effective method of improving the environmental temperature of crop plant,which is of great significance for increasing crop yield.

Sustainable energy management of solar greenhouses using open weather data on MACQU platform

Precision energy management is very important for sustainability development of solar greenhouses,since huge energy demand for agricultural production both in quantity and quality.A proactive energy management,according to the optimal energy utilization in a look-ahead period with weather prediction,is presented and tested in this research.A multi-input-multi-output linear model of the energy balance of solar greenhouses based on on-line identification system can simulate greenhouse behavior and allow for predictive control.The good time allocation of available solar energy can be achieved by intelligent use of controls,such as store/retrieve fans and ventilation windows,i.e.solar energy to warm up the air or to be stored in the storage elements(wall,soil,etc.)or to be exhausted to outside.The proactive energy management can select an optimal trajectory of air temperature for the forecasted weather period to minimize plants’thermal‘cost’defined by an‘expert’in terms of set-points for the specific crop.The selection of temperature trajectory is formulated as a generalized traveling salesman problem(GTSP)with precedence constraints and is solved by a genetic algorithm(GA)in this research.The simulation study showed good potential for energy saving and timely allocation to prevent excessive crop stress.The active control elements in addition to predefining and applying,within energy constraints,optimal climate in the greenhouse,it also reduces the energy deficit,i.e.the working hours of the‘heater’in the sustained freezing weather,as well as the ventilation hours,that is,more energy harvest in the warm days.This intelligent solar greenhouse management system is being migrated to the web for serving a‘customer base’in the Internet Plus era.The capacity,of the concrete ground CAUA system(CAUA is an abbreviations from both China Agricultural University and Agricultural University of Athens),to implement web‘updates’of criteria,open weather data and models,on which control actions are based,is what makes use of Cloud Data for closing the loop of an effective Internet of Things(IoT)system,based on MACQU(MAnagement and Control for QUality)technological platform.

Analysis of the thermal performance of the novel assembled Chinese solar greenhouse with a modular soil wall in winter of Yinchuan,China

In order to improve the thermal insulation and storage performance of Chinese solar greenhouses in winter,a novel assembled Chinese solar greenhouse(ACSG)without energy supplement in cold climatic areas was designed to evaluate and compare its thermal performance with that of conventional Chinese solar greenhouse(CSG).The thermal properties of both greenhouses were tested in field on cold winter days in Ningxia,China.The results indicated that the land utilization rate of ACSG was 19.3%higher than that of CSG.On a typical sunny day(the lowest outdoor temperature was−22.0℃)and typical cloudy day(the lowest outdoor temperature was−19.7℃)during the experiment,the minimum indoor temperature of ACSG was respectively 1.7℃and 2.0℃higher than that of CSG.The results for 24 consecutive days(the average outdoor daily minimum air temperature was−19.0℃)showed that the average minimum indoor temperature of ACSG was 1.4℃higher than that of CSG(p<0.05).The modular soil wall attached with colored steel polystyrene boards would be exploited as the north wall of CSG in Yinchuan area.

Effects of window opening style on inside environment of solar greenhouse based on CFD simulation

Solar greenhouse is extensively used in horticultural production in China.Natural ventilation is one of the key technological means to adjust the inside environment of greenhouse,while the effects of window opening styles on the inside environment are still not well understood.In the present study,the temperature and air flow field of five operation styles,namely back roof central opening style(G1),back roof evenly spaced opening style(G2),top roof full opening style(G3),style of G1+G3,and style of G2+G3 were simulated using the CFD method.The results indicated that:(1)the simulated and measured results exhibited favorable agreement,with relative errors within 5%;(2)In the case of the windows opening area was the same and only single ventilation style was applied,back roof full opening style exhibited the best cooling effect.The inside average temperature of the greenhouse with G1 style decreased by 0.5°C and 1.6°C respectively compared with those of greenhouses with G2 and G3.(3)The cooling effect of the style of G2+G3 was more favorable than that of the style of G1+G3.The style of G2+G3 exhibited better cooling effect than the single ventilation styles,with the lowest temperature(27.5°C)and temperature uniformity coefficient(0.36).

Influence of thermodynamic disfigurement on the convective heat transfer of solar greenhouse

Solar greenhouse is a typical greenhouse without any additional heating system,which has developed rapidly in Northern China.However,due to the construction quality,management methods,especially the long-term use and other factors,there are usually different degrees of thermodynamic disfigurements in the envelop enclosure of solar greenhouse.The purpose of this study was to investigate the influences of thermodynamic disfigurement on the temperature distribution and convective heat transfer of solar greenhouse.In this study,the east and west compartments of a typical solar greenhouse which is located in Yangling,China(108°4′E,34°16′N)were tested.The air temperature of each compartment was collected using temperature recorders,and the thermal infrared images of different compartment envelopes were obtained by a thermal infrared imager on a typical cloudy day.Convective heat transfer coefficients and heat flux densities of different compartment envelopes in the solar greenhouse were calculated.The results showed that the temperature difference can be displayed in the thermal infrared images of compartment envelopes,the surface temperature of the front roof was the lowest,followed by the back roof,the wall surface temperature was the highest.The minimum average surface temperature of the front roof in the eastern compartment was only 3.8℃,which was 6.8℃ and 9.2℃ lower than the average surface temperature of the back roof and back wall,respectively.The surface average temperature of thermodynamic disfigurements located at the bottom of the south side in the front roof of the eastern compartment,whose area accounted for 16.5%of the total front roof in the eastern compartment,was only 5.4℃.Compared with non-thermodynamic disfigurement,the average convective heat transfer coefficient and heat flux density of thermodynamic disfigurements in the front roof of the eastern compartment were increased by 20.3%and 110.3%,respectively.The average air temperature in the eastern compartment was 3.5℃ lower than the average air temperature in the western compartment of the solar greenhouse.Construction of brick wall at the bottom of the south side of the front roof in the solar greenhouse helped to increase the inner surface temperature of the front roof,with an average temperature rise of 6.2℃,and reduce the area of thermodynamic disfigurement,which only accounted for 2.6%of the total front roof in the western compartment.The average surface temperature of thermodynamic disfigurements mainly caused by the entry and exit door in the wall of the eastern compartment was only 9.8℃,which was lower 3.2℃ than the average temperature of non-thermodynamic disfigurement of the wall.Thermodynamic disfigurement helped to increase heat loss.The weighted average proportion of thermodynamic disfigurement in the western compartment was 2.1%,while that of thermodynamic disfigurement in the eastern compartment was 10.7%.The thermal insulation performance of the western compartment envelope in the solar greenhouse was better than that of the eastern compartment envelope.

Sensitivity of solar greenhouse envelopes to the thermal disfigurements and optimal selection of the thermal insulation quilt

The objectives of the present work are focused on exploration of the reasons for temperature difference in different envelopes,the sensitivity of envelopes of solar greenhouse to thermal disfigurements and optimal selection of the thermal insulation quilt.Theoretical analysis and derivation are conducted according to the experimental results of surface temperature,convective heat transfer,and heat flux density in different envelopes which with thermal disfigurements of solar greenhouse using heat transfer theory.The results revealed that the difference of intrinsic thermal conductivity and thickness of the envelopes leads to difference in the thermal flux and thus in the surface temperature of different envelopes.Compared with the front roof and back roof,the wall is more sensitive to thermal disfigurements.According to the influence of thermal disfigurements on solar greenhouse temperature,the allowable thermal disfigurements area fraction of front roof and back roof are given.Based on the analysis of heat transfer theory and test results,the work given the expression of the thickness and thermal conductivity of thermal insulation quilt under different outdoor minimum temperatures for optimal selection of thermal insulation quilt based on comprehensive considering factors of the solar greenhouse structure,crop demand,outdoor minimum temperature,and insulation quilt properties.The results of this work give technical criterion for whether the envelopes with thermal disfigurements needs to be repaired or replaced,and it also provides theoretical and technical support for design the solar greenhouse as well as methodological guidance for the optimal selection of the thermal insulation quilt.

Analysis of solar radiation changes in Chinese solar greenhouses with different roof structures based on a solar radiation model

Chinese solar greenhouses(CSGs)are important agricultural production facilities.Under non-artificial heating conditions,solar radiation is the only CSGs energy source.It is highly important to optimally obtain solar energy in greenhouse construction and production.In this study,a solar radiation model for solar greenhouses was adopted to explore the quantities of solar radiation in greenhouses considering different front roof forms and angles.Herein,the solar radiation amounts corresponding to five roof forms,namely,double-section arc,parabolic,oval,arc,and linear roofs,are compared and analyzed during the four solar periods(beginning of spring,vernal equinox,beginning of winter,and winter solstice).It was found that the solar radiation of oval roof greenhouses on the ground was the largest and was 4.44%-23.68%higher than that of parabolic roofs.In addition,the cumulative sum of light on the linear roof greenhouse wall is also the largest and was 6.02%to 12.08%higher than the parabolic roof greenhouse in the four solar terms.Moreover,the solar radiation in CSGs was compared with front roof angles of 25°,30°,and 35°.It was observed that the solar radiation amount gradually increases with increasing angles.Notably,the variation at an angle of 35°influences the solar radiation of the paraboloidal CSGs ground and elliptical CSGs north wall to the greatest extent,which increased by 8.23%and 12.74%,respectively.This study confirms the role of front roof form and inclination angle in enhancing the greenhouse solar radiation level.

Development and test verification of air temperature model for Chinese solar and Spainish Almeria-type greenhouses

Growth can be defined as an increment in biomass or an increment in weight or height of the organs of the plant influenced by physiological processes.Many of these processes have their limits genetically determined,but climate and irrigation play an important role.Because of its importance,microclimate has been extensively studied in the modeling as a surrounding condition which is imposed by the exterior climate.The main objective of this work was to develop a temperature model based on the energy balance dynamics at two different greenhouse locations-South-eastern Spain and Northern China,and the traditional structures of Chinese solar greenhouse and Almería-type multi-span greenhouse were taken into account.The final model was developed by combining the external conditions,the actuator influence and the crop growth,where the temperature is influenced by soil,crop,cover,actuators,back wall and greenhouse geometry.The model took into account the energy lost by convective and conductive fluxes,as well as the energy supplied by solar radiation and heating systems.The soil and the back wall are the main media for energy storage.The temperature dynamic was determined by a physical model,which considered the energy balance from a holistic point of view-as a sub-model for a customizable interface among the external climate,the plant and the greenhouse system.The influences of different subsystems included in the temperature model were analyzed and evaluated.The results showed a high R^(2)value of 0.94 for Beijing and 0.95 for Almeria,and the average error was low,of which the MAE and RMSE were 0.71 and 1.365 for Almeria and 0.62 and 1.102 for Beijing,respectively.Thus,the model can be considered as a powerful tool for control design purposes in microclimate systems.

Application performances of two greenhouses with new types of backwall in Yangling,China

In order to investigate the application performances of the solar greenhouses with new types of backwall(greenhouse W_(2),and greenhouse W_(3))and the ordinary clay brick backwall greenhouse(greenhouse W_(1)),and provide a theoretical basis for the construction of solar greenhouse in Yangling Demonstration Zone,Shaanxi,China,two greenhouses with different new types of backwall were designed.The backwall of one of them was built with lightweight aggregate concrete block(greenhouse W_(2))and that of the other one was assembled with a row of sand-filled cement pipes(greenhouse W_(3)).The tested greenhouses were constructed in Yangling Demonstration Zone.Based on the data collected on typical sunny and cloudy days,the indoor temperature,inside wall temperature,and the heat flow of the greenhouses with new types of backwall were compared with those detected in the ordinary clay brick backwall solar greenhouse,and the tested results were numerically simulated.According to the comparison of the physiological indicators of tomatoes planted in the greenhouses and the construction costs,the greenhouse type with the best practicability was found.The results indicated that:The average air temperature in greenhouses W_(1),W_(2),and W_(3)and outside was 15.1℃,15.9℃,17.3℃,and−0.4℃ on the night of a sunny day,and the air temperature in W_(3)was the highest.The average air temperature in greenhouses W_(1),W_(2),and W_(3)and outside were 9.5℃,13.3℃,11.0℃,and−5.5℃ on the night of a cloudy day,the air temperature in W_(2)was the highest.In the depth of 0-330 mm from the interface of the backwalls,the walls were obviously affected by the solar radiation,and the temperature changed greatly.The wall temperature on the sunny days exhibited an ascending order of W_(1),W_(2),W_(3),while on the cloudy days was in the ascending order of W_(1),W_(3),W_(2).The wall of W_(3)absorbed the most heat during the daytime and released the most heat at night on the sunny day,while W_(2)exhibited the second most heat absorption during the daytime,however,it exhibited the highest heat release at night on the cloudy day,which were almost equaled to its heat absorption.Tomatoes in W_(3)grew well and exhibited the highest yield,and this greenhouse had the lowest construction costs.Comprehensively considering the physiological indicators of tomatoes and the corresponding construction costs of greenhouses,W_(3)has the best application performance in Yangling Demonstration Zone.

Mechanical model for double side self-propelled rolling machine based on rigid and flexible contact dynamics

The objective of the present research was to establish a mechanical model to study the performance of double side self-propelled rolling machine.There are two key models in the modeling process.The first model is the soft cover dynamics model,which is an important innovation in this study.And the insulation quilt was established based on the Macro-modeling technology.The second model is the double side self-propelled rolling machine virtual prototype model.By specifying multiple contact constraints and loadings between the soft cover dynamics model and the rigid component,the virtual prototype model was built successfully and the double side self-propelled rolling process was completely simulated.Moreover,the interaction mechanisms of the rigid and flexible coupling mechanics were investigated.The virtual rolling processes of different insulation quilt lengths were analyzed under different thickness treatments.The simulated results showed a good agreement with the experimental measurements,which suggested that the established model is an effective approach to evaluating and optimizing the rolling machine.The successful establishment of the mechanical model can facilitate the study of the performance of the product and further optimization,and also is of great significance to shorten the development cycle and reduce costs.