Greenhouse Model Research Articles

A new optimisation methodology used to study the effect of cover properties on night-time greenhouse climate

This study presents an optimisation method for improving greenhouse design. The approach was based on the surrogate-based method and combines the use of energy balance simulation (ES) and computational fluid dynamics (CFD). The optimisation was applied to study the effects of cover properties on the night-time greenhouse climate. The ES model was verified by comparing its predictions with experimental data. The root mean square error (RMSE) values for internal temperature and humidity showed there was good agreement between the ES and experimental values. The optimisation process highlighted the importance of using a low emissivity and low transmissivity cover material. Under a clear sky the predicted temperature gain by using a high reflectance material compared to a regular one on an unheated greenhouse was approximately 4 °C. The relative humidity in the same scenario was reduced by almost 10%. Two ES parametric studies were carried out, the first showed the effects of different combinations of thermal radiation properties in term of temperature and humidity; the second showed the effects of the high reflectance material under different external conditions (equivalent sky temperature and soil heat flux (SHF)). This paper suggests that ES and CFD can be used together to provide a complete approach to greenhouse modelling.

An Intelligent Greenhouse Control System

Because the greenhouse control systems designed in the past are not adaptable in practice, a new greenhouse control system based on RS485 bus is realized in this paper. A new smart sensor block is developed in the system to acquire field environment factor, which can reduce complex routing and increase reliability of the whole system. The model of solar greenhouse is introduced and fuzzy control is adopted in control unit. Besides, a friendly human-computer interface is developed by LabVIEW. The proposed system has been verified by the experiments in the control of medium single-span greenhouses. DOI: http://dx.doi.org/10.11591/telkomnika.v11i8.308 8

Towards Sustainability of Protected Agriculture: Automatic Control and Structural Technologies Integration of an Intelligent Greenhouse

Nowadays, protected agriculture has continually lagged because of the scarce and slow technological advances and unskilled labor. The implementation of intelligent greenhouses to improve the quality and quantity of crops allows a precise regulation of the environmental conditions inside the greenhouse considering the lifecycle of the crop within the control rules. The main objective of the present is to describe the stages of analysis, design and implementation of an intelligent greenhouse developed in the Tecnológico de Monterrey Campus Ciudad de México. The focus of this is based on the sustainable development approach considering a robust design that integrates reliable, simple, efficient, ecologic and low cost materials and systems with the aim of achieving the automation and control of the microenvironment. The reason of using artificial intelligence techniques over conventional methods, resides in the fact that the greenhouse model is highly nonlinear at many operating points.

CFD Based Study of Heterogeneous Microclimate in a Typical Chinese Greenhouse in Central China

Indoor microclimate is important for crop production and quality in greenhouse cultivation. This paper focuses on microclimate study based on a computational fluid dynamics (CFD) model of a typical plastic greenhouse (with a sector shape vertical cross-section) popularly used in central China. A radiation model is added into the CFD model so as to simulate coupling of convective transfers and radiative exchanges at the cover and the roof, instead of using the usual coupling approach based on energy balance. In addition, a fractal permeability model is innovatively adopted in the modeling of the crop canopy. Compared the numerical results with measured experimental data, the model simulation is proved with success. This model then is used to explore the microclimate variable distributions in the greenhouse. It shows that the airflow pattern, temperature and humidity profiles are different from those in a sawtooth Mediterranean-type greenhouse. The study suggests that this deliberately developed CFD model can be served as a useful tool in macroclimate research and greenhouse design investigating.

Shading screens for the improvement of the night time climate of unheated greenhouses

The objective of this work was to study the effect of shading screens, normally used during the day for cooling purposes, on the night-time climate of unheated greenhouses. For this purpose, first a number of experimental measurements were taken during cold nights to characterise the greenhouse climate both with and without an aluminised external screen. Secondly a Computational Fluid Dynamic (CFD) model of greenhouse was developed. After validation of the model by comparison with experimental data, the model was used to simulate the greenhouse climate for different sky conditions ranging from cloudless to overcast nights. Simulations were performed for a greenhouse with internal and external shading screens and for the same greenhouse without screens. Experimental results showed the positive effect of an external shading screen, whose use increased night-time temperature and reduced the risk of thermal inversion. Its effect was much stronger under clear sky conditions. The CFD model supported this conclusion and provided a detailed explanation of the temperature behaviour of all the greenhouse types considered. CFD simulations proved that an aluminised screen placed inside the greenhouse at gutter height gave the greatest thermal increase. Therefore, external or internal screens can help to increase the sustainability of greenhouse production in areas with mild winter climates by enhancing the use of solar energy stored in the greenhouse soil during the previous day and released at night-time.

Effects of person-centered care on residents and staff in aged-care facilities: a systematic review

BackgroundSeveral residential aged-care facilities have replaced the institutional model of care to one that accepts person-centered care as the guiding standard of practice. This culture change is impacting the provision of aged-care services around the world. This systematic review evaluates the evidence for an impact of person-centered interventions on aged-care residents and nursing staff.MethodsWe searched Medline, Cinahl, Academic Search Premier, Scopus, Proquest, and Expanded Academic ASAP databases for studies published between January 1995 and October 2012, using subject headings and free-text search terms (in UK and US English spelling) including person-centered care, patient-centered care, resident-oriented care, Eden Alternative, Green House model, Wellspring model, long-term care, and nursing homes.ResultsThe search identified 323 potentially relevant articles. Once duplicates were removed, 146 were screened for inclusion in this review; 21 were assessed for methodological quality, resulting in nine articles (seven studies) that met our inclusion criteria. There was only one randomized, controlled trial. The majority of studies were quasi-experimental pre-post test designs, with a control group (n = 4). The studies in this review incorporated a range of different outcome measures (ie, dependent variables) to evaluate the impact of person-centered interventions on aged-care residents and staff. One person-centered intervention, ie, the Eden Alternative, was associated with significant improvements in residents’ levels of boredom and helplessness. In contrast, facility-specific person-centered interventions were found to impact nurses’ sense of job satisfaction and their capacity to meet the individual needs of residents in a positive way. Two studies found that person-centered care was actually associated with an increased risk of falls. The findings from this review need to be interpreted cautiously due to limitations in study designs and the potential for confounding bias.ConclusionTypically, person-centered interventions are multifactorial, comprising: elements of environmental enhancement; opportunities for social stimulation and interaction; leadership and management changes; staffing models focused on staff empowerment; and assigning residents to the same care staff and an individualized philosophy of care. The complexity of the interventions and range of outcomes examined makes it difficult to form accurate conclusions about the impact of person-centered care interventions adopted and implemented in aged-care facilities. The few negative consequences of the introduction of person-centered care models suggest that the introduction of person-centered care is not always incorporated within a wider “hierarchy of needs” structure, where safety and physiological need are met before moving onto higher level needs. Further research is necessary to establish the effectiveness of these elements of person-centered care, either singly or in combination.

Greenhouse Modeling Using Continuous Timed Petri Nets

This paper presents a continuous timed Petri nets (ContPNs) based greenhouse modeling methodology. The presented methodology is based on the definition of elementary ContPN modules which are designed to capture the components of a general energy and mass balance differential equation, like parts that are reducing or increasing variables, such as heat, CO2concentration, and humidity. The semantics of ContPN is also extended in order to deal with variables depending on external greenhouse variables, such as solar radiation. Each external variable is represented by a place whose marking depends on ana prioriknown function, for instance, the solar radiation function of the greenhouse site, which can be obtained statistically. The modeling methodology is illustrated with a greenhouse modeling example.

CHANGES IN ENERGY DEMAND FOR A PARTIALLY GLAZED GREENHOUSE / ENERGIJOS POREIKIŲ KITIMAS IŠ DALIES ĮSTIKLINTAME ŠILTNAMYJE

The article analyzes changes in energy demand for a greenhouse. The worked out solution to the construction of the building is a partially glazed greenhouse having a glazed roof and open vertical barriers. Design Builder software has been applied for analytical calculations and greenhouse modelling as well as for introducing changes in annual energy demand and establishing temperature variations and regime. The paper reviews the obtained results and diagrams, performs analysis and draws conclusions. Santrauka Straipsnyje nagrinėjamas energijos poreikių kitimas šiltnamyje. Pasirinktas šiltnamio konstrukcinis sprendimas – iš dalies įstiklintas šiltnamis. Tai toks šiltnamio variantas, kai įstiklintas statinio stogas, o vertikalios atitvaros neįstiklintos. Atlikti analitiniai skaičiavimai ir šiltnamis sumodeliuotas programa DesignBuilder. Nagrinėtas energijos poreikių kitimas per metus, temperatūrų kitimas, patalpų temperatūros režimas, naudojant minėtą kompiuterinę programą. Apžvelgti gauti rezultatai, diagramos, atlikta analizė, padarytos išvados.

Computational Fluid Dynamics Modeling to Improve Natural Flow Rate and Sweet Pepper Productivity in Greenhouse

Natural flow rate and sweet peppers productivity in tropical greenhouse are improved by CFD simulation is the main objective of this research work. Most of the greenhouse types today are in the arch shape. To develop an improved greenhouse structure for the region, the arch type was built and used as the control model. Mae Sar Mai agriculture research station under the royal project foundation was selected as the field test site. Temperature sensors with data logger were installed to monitor variation of temperature inside the greenhouse. The measured temperature data were used as the boundary conditions for the CFD analysis. A new greenhouse model with two-step roof shape was designed and the air flow behavior was simulated by using CFD. Regarding CFD results the air flow rate of the new model is about 39% higher than that of old model. The maximum temperature of the new model is lower than that of the old one. The sweet paper growths in both greenhouse models were measured and compared. Results show that the new model obtains 4°C lower maximum temperature in day time, 97% in number and 90% in weight higher the first grade pepper productivity than the old one.

GA Optimization of the Coupled Climate Model of an Order Two of a Greenhouse

Greenhouses are used for the main purpose of improving the environmental conditions in which plants are grown.The efficiency of plant production in greenhouses depends significantly on the adjustment of several components particularly, the greenhouse interior temperature, vapour pressure and Co2 concentration. Here are developed a nonlinear coupled multiple-input, multiple-output (MIMO) model of an environmental greenhouse under matlab/simulink. This paper presents the optimization of temperature and vapour pressure employing a complex greenhouse climate model .The investigation of the newly developed approach for determining the optimal values for the greenhouse model parameters using the genetic algorithm technique (GA) was used.The mathematical model and the data used to test the proposed method were acquired in a commercial greenhouse using a sampling time interval of 1 hour. The greenhouse is automated with several actuators and sensors that are connected to an acquisition and control system based on a personal computer. The simulation results demonstrate the effectiveness of the proposed method.

Uptake of human pharmaceuticals and personal care products by cabbage (Brassica campestris) from fortified and biosolids-amended soils

Human pharmaceuticals and personal care products (PPCPs) are routinely found in biosolids from wastewater treatment plants (WWTPs). Once land applied, the PPCPs in biosolids are potentially available for plant uptake and bioaccumulation. This study used a greenhouse model to investigate uptake of PPCPs commonly detected in biosolids by the agricultural plant Chinese cabbage (Brassica campestris). Two series of greenhouse experiments were conducted as part of this project. In the first set of experiments, four pharmaceuticals were added to an organic matter-rich soil in environmentally relevant concentrations based on typical biosolids application rates, resulting in final soil concentrations of 2.6 ng g(-1) carbamazepine, 3.1 ng g(-1) sulfamethoxazole, 5.4 ng g(-1) salbutamol, and 0.5 ng g(-1) trimethoprim. In the second set of experiments, the cabbage was grown in soil amended with an agronomic rate of biosolids from a local WWTP. The ambient concentration of PPCPs in the biosolids resulted in final soil concentrations of 93.1 ng g(-1) carbamazepine, 67.4 ng g(-1) sulfamethoxazole, 30.3 ng g(-1) salbutamol, 433.7 ng g(-1) triclosan, and 24.7 ng g(-1) trimethoprim. After growing to maturity, the aerials of the plants were separated from roots and the two tissue types were analyzed separately. All four human pharmaceuticals were detected in both tissues in the cabbage grown in the soil fortified with the four pharmaceuticals with median concentrations of 255.4 ng g(-1) aerials and 272.9 ng g(-1) roots carbamazepine; 222.8 ng g(-1) aerials and 260.3 ng g(-1) roots sulfamethoxazole; 108.3 ng g(-1) aerials and 140.6 ng g(-1) roots salbutamol; and 20.6 ng g(-1) aerials and 53.7 ng g(-1) roots trimethoprim. Although all study compounds were present in the biosolids-amended planting soil, only carbamazepine (317.6 ng g(-1) aerials and 416.2 ng g(-1) roots), salbutamol (21.2 ng g(-1) aerials and 187.6 ng g(-1) roots), and triclosan (22.9 ng g(-1) aerials and 1220.1 ng g(-1) roots) were detected in the aerials of the cabbage. In addition to the study compounds detected in the aerials, sulfamethoxazole was detected in the roots of one of the plants in the biosolid-amended soil. In comparison to many previous studies that have utilized PPCP concentration that exceed environmentally relevant concentrations, plants in this study were exposed to environmentally relevant concentrations of the PPCPs, yet resulted in uptake concentrations similar to or greater than those reported in comparable studies. We suggest that rhizosphere conditions, particularly the presence of dissolved organic matter in the planting matrix, might be one of the critical factors determining mobilization and bioavailability of xenobiotic compounds such as PPCPs.

PERFORMANCE OF A POLY-GREENHOUSE WITH DIFFERENT VENTILATION GAPS UNDER FAYOUM CLIMATIC CONDITIONS

Four different poly-greenhouse models were compared with the open field condition at El-Azab village, Fayoum, Egypt from 18th January to 30th July, 2010. Production of chili pepper in greenhouses was an effective way of increasing the yield per unit area and enhancing its quality. Therefore, different sized poly-greenhouse ventilation gaps with 25% shade net and UV stabilized plastic film sheet materials were used. The thermal performance of the greenhouse models and their effects on the growth rate and yield of chili pepper were investigated. The obtained results indicated that the air temperature in the open field condition was lower than in the poly-greenhouse treatments throughout the growth period of chili peppers bushes. Production of chilli pepper in greenhouse was an effective way of increasing the yield per unit area and enhancing the quality. Poly-greenhouse model with ventilation gaps in the triangular roof and four sidewalls (T3) was found more suitable for better plant growth and yield of chili pepper than those with the other ventilation gaps in poly-greenhouse models and open field condition.

English

Research activities have been taking on place in many ports of the world to develop or produce new greenhouse construction materials in order to grow more economic agricultural products. One of the new technological materials is the glass fiber reinforced plastic (GFRP) materials. GFRP materials are basically constituted of resin and continuous or chopped fiber and they are manufactured by using various manufacturing methods. The pultrusion process is a proven manufacturing method for obtaining lengths of high quality GFRP and became a competitive alternative to traditional structural materials. Factors in choosing GFRP materials for greenhouse applications are: lightweight, non‑corrosive, chemically resistant, possess good fatigue strength, provide electrical and flame resistance. In this study, the structural behavior of the greenhouse structure, which is constructed using pultruded GFRP structural element, has been investigated. The mechanical properties of the pultruded GFRP sections have been computed using national and international standards. The proposed structures have been modeled using well known finite element program (SAP, 2000) to investigate the structural behavior under the static and dynamic loads. The pultruded GFRP box section and three different connection details have also been developed. The advantages and importance of GFRP profiles used in the greenhouse structure have been demonstrated.   Key words: Glass fiber reinforced plastic, greenhouse model, static analysis, dynamic analysis.

From Nursing Home to Green House

This article tracks the changing roles of certified nursing assistants (CNAs) as they transition from a traditional nursing home setting to a “deinstitutionalized” care setting called the Green House. The Green House concept, developed by William Thomas, MD and based on the Eden Alternative paradigm, emphasizes autonomy, dignity, privacy, and reciprocal relationships between residents and staff. This qualitative work focuses on how CNAs (called “shabazim” in the Green House) negotiated the transition from traditional nursing home to the Green House model. Interview, focus group, and participant observation data before and after the transition to the Green Houses reveal that in the traditional nursing home environment, informants report that resident-CNA interactions tend to be rushed, detached, and adversarial, whereas in the Green House care environment, interdependency and stronger ties are promoted. Shabazim report diminished guilt and enhanced sense of empowerment in their new role.

A Compatible Control Algorithm for Greenhouse Environment Control Based on MOCC Strategy

Conventional methods used for solving greenhouse environment multi-objective conflict control problems lay excessive emphasis on control performance and have inadequate consideration for both energy consumption and special requirements for plant growth. The resulting solution will cause higher energy cost. However, during the long period of work and practice, we find that it may be more reasonable to adopt interval or region control objectives instead of point control objectives. In this paper, we propose a modified compatible control algorithm, and employ Multi-Objective Compatible Control (MOCC) strategy and an extant greenhouse model to achieve greenhouse climate control based on feedback control architecture. A series of simulation experiments through various comparative studies are presented to validate the feasibility of the proposed algorithm. The results are encouraging and suggest the energy-saving application to real-world engineering problems in greenhouse production. It may be valuable and helpful to formulate environmental control strategies, and to achieve high control precision and low energy cost for real-world engineering application in greenhouse production. Moreover, the proposed approach has also potential to be useful for other practical control optimization problems with the features like the greenhouse environment control system.

Evidence Behind the Green House and Similar Models of Nursing Home Care

The Green House and similar models of nursing home care offer a solution to the institutional nature of nursing homes. In The Green House model, small houses are home to 6–12 residents in which care is given as much attention as treatment and is provided by a consistent, self-directed team of staff who are responsible for all care, including preparing meals in a centrally located open kitchen. Residents have private rooms and bathrooms that open onto a central living area. Although a nurse is available 24 h a day and the clinical care team is nearby and visits the home to provide care, the sense is that one is receiving care in a family-type setting. While these homes are expanding rapidly and seem to embody a better culture of nursing home care, their future growth may depend on the evidence that supports or refutes the quality of care that they provide.

EFFECT OF POLY-GREENHOUSE SHADING RATIOS ON GERMINATION AND YIELD OF TOMATO UNDER FAYOUM DEPRESSION CLIMATIC

Four similar experimental poly-greenhouse models with different shading rations and ventilation gaps were used and compared with the open field condition. One of the four poly-greenhouse models was covered by a single layer of polyethylene (without shading), and the others three models were covered with an external black screen shade net sheets of 25%, 63% and 75% shading ratios, during the winter months. While, three poly-greenhouse models were covered only with black screen shade net sheets of 25%, 63% and 75% shading ratios during the summer months. The thermal performance of the greenhouse models and their effects on seedlings germination and yield of tomato (GSI Seed, Hybrid Tomato, Nora-765) were investigated under Fayoum depression climatic conditions during the winter and summer months of 2009. The obtained results indicated that the air temperature inside the un-shaded model was almost higher than in shaded models and ambient temperature during the winter months (January to May). The air temperature inside the greenhouse models covered only by black screen shade net sheets of 63% and 75% shading ratios were down the ambient temperature during the summer months (June to October) with ventilation rate during the night time. All shading ratios caused to increase the relative humidity inside the greenhouse models, especially with 63% and 75% shading ratios. As shading ratio increased the light intensity decreased, and thus, the light intensity was adequate when it decreased by 63% and 75%, which is satisfactory for seedlings germination, plant growth and yield of tomato at the summer months. Poly-greenhouse with single layer of polyethylene was found more suitable for seedlings germination, plant growth and yield of tomato than those with the other shading ratios and open field condition during the winter months. Poly-greenhouse covered only by black screen sheets (especially with 63% or 75% shading ratios) was found more suitable for better seedlings germination, plant growth and yield of tomato than this with 25% shading ratio and open field condition in the summer months.

A METHODE TO IMPROVE EVAPORATIVE COOLING SYSTEM IN GREENHOUSES UNDER HOT AND HUMID CLIMATIC CONDITIONS

A combining cooling system is proposed and analyzed to achieve higher cooling efficiency in hot and humid climatic conditions such as in Saudi Arabia. The system was investigating and tested under the weather conditions of Al-Ahssa, Saudi Arabia. In this paper, the results of a study on combining cooling coil unit (CCU) and direct evaporative cooling (DEC) have been discussed.The cooling effectiveness of the cooling coil unit and direct evaporative cooling systems are experimentally investigating on small greenhouse model.Total solar radiation entering the greenhouse, temperature and relative humidity of outdoor air, dry and wet-bulb temperatures of air just leaving the cooling coil unit CCU), and dry and wet-bulb temperatures of air just leaving the direct evaporative cooling system (DEC) were measured and recorded on a data-logger to analyses their correlation with the effectiveness of each cooling system. The obtained data showed that, the hourly average solar radiation flux incident outside and transmitted into the greenhouse was 555.7 and 298.7 W/m2, respectively, consequently, the effective transmittance of the covering material was on the average 53.75%. The temperature and relative humidity of outdoor air, respectively, were 37.3oC and 21.8%, dry and wet-bulb temperatures just leaving the cooling coil were 29.4oC and 18.8oC, respectively, and dry-bulb temperatures of air just leaving the direct evaporative cooling were 22.8oC. The obtained results also revealed that, the overall effectiveness of the combining cooling system was more than 100%. Thus, this system environmentally clean and energy efficient system, which considered as an alternative to the mechanical, vapour compression systems. This combining cooling system provided and maintained optimal microclimatic conditions that achieved vapour pressure deficit (VPD) *Assistant Professor, Department of Agricultural Systems Engineering, King Faisal University, Hofuf, Saudi Arabia. of 0.76 and 0.40 kPa inside the greenhouse model during daylight and at night, respectively. It can also conclude that, this combining cooling system can use in various climatic conditions as an environmentally clean and energy efficient system.

Pseudo bond graph model of coupled heat and mass transfers in a plastic tunnel greenhouse

In greenhouses, models built are classified into two kinds; heterogeneous approaches based on computational fluid dynamics (CFD) codes and homogeneous one based on heat and mass balance equations. Bond graph modelling was not seriously introduced in greenhouse modelling in spite of the concordance of the energetic based approach of bond graphs with the nature of the greenhouse plant. In this research work, a pseudo bond graph model of a greenhouse was elaborated to simulate temperature and relative humidity inside. The model proposed is an energetic lumped approach which describes coupled heat and mass transfers in a plastic tunnel greenhouse. This model includes convection, evaporation/condensation phenomena, air change flow and soil heat and mass transfer. Multiport (3 ports) bond graph elements are introduced to describe the state of the two elements (dry air and water vapor) fluid. New bond graph schemes are used to characterize the coupling effect between heat and mass transfer, and for modelling free evaporation/condensation mechanism. Big leaf assumption was used to model the canopy. New boundary layer elements are added in the model, these elements allow a separation of the different phenomena inside greenhouse and thus a simplification of the modelling task. The practical results obtained from an experimental tunnel greenhouse are used here as validation elements for the greenhouse bond graph model. A good correlation is observed between measured and predicted samples.

Modeling and evaluation of greenhouse for floriculture in subtropics

Greenhouse technology provides favorable microclimate for year round cultivation of crops. Floricultural production in the greenhouse is an attractive venture for subtropical India due to its economic and aesthetic value. However, production and quality of flowers suffer due to high summer temperatures. Hence, development of a reliable model to predict the microclimate of greenhouse is necessary to manage the crop production and to optimize the design. Experiments were conducted in two different shape and size of greenhouses to evaluate the microclimate and crop performance. A simple dynamic model was developed to predict air temperature, vapor pressure and canopy temperatures. Submodels of natural ventilation and crop transpiration constituted the sensible and latent heat transfers in the greenhouse. The model was validated for Gerbera crop cultivation during winter and summer seasons. Good agreement was found between the predicted and observed values of temperature with RMSE values of 0.73 °C and 0.87 °C during winter and summer seasons, respectively. Sensitivity analysis of the model showed that width of side opening and angle of roof vent influenced the model performance considerably. It was concluded that the model can be used as a design tool for prediction of microclimate in the greenhouse for floricultural production.