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.

The Actuality and Prospect of Meteorological Service Technology for Solar Greenhouse

The solar greenhouse's construction and its demand on meteorological service in the process of production management in China were analyzed,and the current situation of meteorological service on it was summarized.Combined with the trend of related technology,the future development of solar greenhouse meteorological service was prospected.

Construction of Cucumber Powdery Mildew Early Warning System in Solar Greenhouse Based on Internet of Things

ln order to explore the design and construction of cucumber powdery mildew warning system in solar greenhouse, internet of things technology was used to conduct the real-time dynamic monitoring of the incidence of cucumber powdery mildew and cucumber growth environment in solar greenhouse. The growth environ-ment included temperature and humidity of air and soil. Logistic regression model was used to construct cucumber powdery mildew warning model. The results showed that humidity characteristic variable （maximum air humidity） and temperature characteristic variable （maximum air temperature） had significant effects on the inci-dence probability of cucumber powdery mildew in solar greenhouse. And it was fea-sible to construct cucumber powdery mildew warning system in solar greenhouse with internet of things.

Impact of Illumination and Temperature Performance of Blanket-Inside Solar Greenhouse and CO_2 Enrichment on Cucumber Growth and Development

To evaluate the effects of solar greenhouse with different structure and CO2 enrichment on illumination and temperature performance of greenhouse and cucumber growth and development in the central region of Inner Mongolia, the research used traditional solar greenhouse （A） and blanket-inside solar greenhouse（B）, and set 4 treatments： AE （traditional solar greenhouse A with CO2 enrichment）, AN （traditional solar greenhouse A without CO2 enrichment）, BE （blanket-inside solar greenhouse B with CO2 enrichment） and BN （blanket-inside solar greenhouse B without CO2 enrichment）, to explore the influence of cucumber growth, photosynthetic property, quality and yield in different structure solar greenhouses with CO2 enrichment. The results showed that the illumination and temperature in blanket-inside solar greenhouse was superior to traditional solar greenhouse, and the average light intensity in blanket-inside solar greenhouse increased by 21.05%, compared with traditional solar greenhouse. Under the condition of same greenhouse structure, stem height ,average stem diameter, contents of soluble sugar, vitamin C, net photosynthetic rate and yield showed any significant difference between the treatments with CO2 enrichment or not. Under the condition of same CO2 concentration, BE cucumber average stem height, average stem diameter, contents of soluble sugar, net photosynthetic rate and yield in BE was higher than which in AE. Therefore, the optimization in structure of blanket-inside solar greenhouse remarkably improved illumination and temperature property, combining with CO2 enrichment as application technology, there was crucial significance to promote the greenhouse performance and improve the efficiency of greenhouse vegetable production.

Characters of Temperature Variation and Minimal Temperature Forecast inside of Solar Greenhouse in Winter in Shouguang City of Shandong Province

[Objective] The aim was to improve meteorological service of protected agriculture and to reduce effects of meteorological disasters. [Method] Characters of temperature variation in solar greenhouse and minimal temperature forecast models in winter were analyzed based on meteorological data inside and outside of solar greenhouse in winter during 2008-2011, as per correlation and stepwise regression method. [Result] Temperature was of significant changes in solar greenhouse in sunny and cloudy days and the change was higher in sunny days. In overcast days, temperature in solar greenhouse was lower and plants were affected seriously. In addition, the minimal temperature was of good correlation with outside temperature and humidity, temperature and soil temperature in greenhouse. [Conclusion] The minimal temperature forecast model of solar greenhouse is established and the average absolute error of the forecasted minimums in different types of weather was less than 1 ℃ and the average relative error was lower than 10%.

Estimation of Cucumber Evapotranspiration in Solar Greenhouse in Northeast China

The solar greenhouse without heating system has been widely used for vegetable production in Northeast China since the 1980s. The experiment was conducted in the solar greenhouse to study the relationship between evapotranspiration （ET） of cucumber and climatic factors. Reference evapotranspiration （ET0） and pan evaporation （Ep） were applied to determine cucumber evapotranspiration by regression methods. Results showed that the ET of cucumber increased with the increasing of solar radiation, air temperature and vapor pressure. The solar radiation was the most important factor that influences ET among environmental parameters. The determination coefficient （R2） was 0.865 between ET and Ep, higher than that between ET and ET0 （application of a constant vegetation coefficient, R2 = 0.46）. The pan coefficient （kp, determined from the ratio of ET to Ep） and the crop coefficients （kc, determined from the ratio of ET to ET0） showed considerable variability and no obvious systematic pattern could be described throughout the study period. Ep was linearly related to ET and 20 cm pan can be well used to determine the water requirement of cucumber under subsurface drip irrigation in this type of solar greenhouse.

The Relationship between Working Conditions and Adverse Health Symptoms of Employee in Solar Greenhouse

To determine the correlation between the working environment and the health status of employees in solar greenhouse, 1171 employees were surveyed. The results show the ＇Greenhouse diseases＇ are affected by many factors. Among general uncomforts, the morbidity of the bone and joint damage is the highest and closely related to labor time and age. Planting summer squash and wax gourd more easilv cause skin pruritus.

Effects of Light and Temperature on Uptake andDistribution of Nitrogen, Phosphorus and Potassiumof Cucumber in Solar Greenhouse

The influence of light and temperature conditions inside solar greenhouse of winter-spring and autumn-winter crop in northern China on uptake and distribution of nitrogen. phosphorus and potassium of cucumber was studied. The results showed that plant root development and uptake and distribution of N, P and K benefited more from inside light and temperature changes in winter-spring crop. Root volume and root activity increased more rapidly in winter-spring than in autumn-winter. Uptake of total N, P2O5 and K2O increased with plant development in winter-spring, and declined in autumn-winter crop. Distribution of total N, P2O5 and K2O at different part of cucumber at fruit bearing stage was significantly influenced by inside light and temperature of solar greenhouse. Total N, P2O5 and K2O were mainly distributed to leaves and stems at early stage, and increasingly to fruits after fruit bearing.

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.

Study on the discharge coefficient of wind-driven naturally ventilated Chinese solar greenhouses

The Chinese solar greenhouse(CSG)is a prevalent feature in agricultural practices within China.Nevertheless,the regulation of natural ventilation within this architectural structure remains suboptimal.Consequently,the development of a natural ventilation model becomes imperative for the effective management of the greenhouse environment.Of particular significance within these models is the consideration of the discharge coefficient as a pivotal parameter.Conducting a multi-case investigation into the variable-dependent discharge coefficient is crucial for both practical application and model advancement.This research delved into the impact of various factors,including the upper-lower vents area ratio(A_(up)/A_(low)),vent-greenhouse area ratio(A_(low)/A_(greenhouse)),lower vent position height(h/H),the incident angle of the external wind,and altitude,on the discharge coefficient(C_(d))of CSG.A CFD model was developed for a scaled CSG with validation conducted through field experiments and wind tunnel tests.Results indicated a 61.6%reduction in C_(d)on average corresponding to an 80%decrease in A_(up)/A_(low).C_(d)levels remained consistent following the attainment of an A_(up)/A_(low)ratio of 1.0.Besides,there was an average increase of 52.5%in C_(d)levels for every 0.09 decline in h/H,attributed to the blocking effect of the cover.Moreover,the ventilation rate and the pressure coefficient difference were utilized to construct a model of C_(d)pertaining to greenhouse design and ventilation operation,exhibiting a notable accuracy level of R^(2)=0.95.Furthermore,the blocking effect of higher h/H was relieved as the incident angleθdecreased under the windward conditions.The increase in A_(up)/A_(low)and the decrease in A_(low)/A_(greenhouse)were identified as crucial factors contributing to the growth of C_(d)under leeward conditions.Ultimately,the high-altitude environment led to a rise in C_(d)levels in contrast to the low-altitude region.The increasing rate of C_(d)correlated positively with A_(low)/A_(greenhouse)and h/H initially,but exhibited a decline once A_(low)/A_(greenhouse)reached 0.036,remaining stable thereafter once h/H reached 0.18.In summary,a comprehensive examination of the discharge coefficient of CSG was undertaken,addressing a significant knowledge deficiency and laying the groundwork for advancements in the natural ventilation model and the intelligent control system for CSG.

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。

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.

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.

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).

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.

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.