scholarly journals Improving Greenhouse Microclimate Control with the Help of Plant Temperature Measurements

1995 ◽  
Author(s):  
Marcel Fuchs ◽  
Ishaiah Segal ◽  
Ehude Dayan ◽  
K. Jordan
Keyword(s):  
Transfer Functions ◽  
Warm Season ◽  
Sweet Pepper ◽  
Ventilation Rate ◽  
Critical Parameters ◽  
Vegetable Crops ◽  
Climate Control ◽  
High Productivity ◽  
Leaf Resistance ◽  
Layer Resistance

A model of the energy balance of a transpiring crop in a greenhouse was developed in a format suitable for use in climate control algorithms aimed at dissipating excess heat during the warm periods. The model's parameters use external climatic variables as input. It incorporates radiation and convective transfer functions related to the operation of control devices like shading screens, vents, fans and enhanced evaporative cooling devices. The model identified the leaf boundary-layer resistance and the leaf stomatal and cuticular resistance as critical parameters regulating the temperature of the foliage. Special experiments evaluated these variables and established their relation to environmental factors. The research established that for heat load conditions in Mediterranean and arid climates transpiring crops maintained their foliage temperature within the range allowing high productivity. Results specify that a water supply ensuring minimum leaf resistance to remain below 100 s m-1, and a ventilation rate of 30 air exchanges per hour, are the conditions needed to achieve self cooling. Two vegetable crops, tomato and sweet pepper fulfilled maintained their leaf resistance within the prescribed range at maturity, i.e., during the critical warm season. The research evaluates the effects of additional cooling obtained from wet pad systems and spray wetting of foliage.

scholarly journals Multispectral Assessment of Sweet Pepper (Capsicum annuum L.) Fruit Quality Affected by Calcite Nanoparticles

Biomolecules ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 832
Author(s):  
Monika Vidak ◽  
Boris Lazarević ◽  
Marko Petek ◽  
Jerko Gunjača ◽  
Zlatko Šatović ◽  
...  
Keyword(s):  
Convex Hull ◽  
Capsicum Annuum ◽  
Fruit Quality ◽  
Sweet Pepper ◽  
Quality Analysis ◽  
Morphological Properties ◽  
Agricultural Practice ◽  
Vegetable Crops ◽  
Physiological Maturity ◽  
Capsicum Annuum L

Sweet pepper (Capsicum annuum L.) is one of the most important vegetable crops in the world because of the nutritional value of its fruits and its economic importance. Calcium (Ca) improves the quality of sweet pepper fruits, and the application of calcite nanoparticles in agricultural practice has a positive effect on the morphological, physiological, and physicochemical properties of the whole plant. The objectives of this study were to investigate the effect of commercial calcite nanoparticles on yield, chemical, physical, morphological, and multispectral properties of sweet pepper fruits using a combination of conventional and novel image-based nondestructive methods of fruit quality analysis. In the field trial, two sweet pepper cultivars, i.e., Šorokšari and Kurtovska kapija, were treated with commercial calcite nanoparticles (at a concentration of 3% and 5%, calcite-based foliar fertilizer (positive control), and water (negative control) three times during vegetation). Sweet pepper fruits were harvested at the time of technological and physiological maturity. Significant differences were observed between pepper cultivars as well as between harvests times. In general, application of calcite nanoparticles reduced yield and increased fruit firmness. However, different effects of calcite nanoparticles were observed on almost all properties depending on the cultivar. In Šorokšari, calcite nanoparticles and calcite-based foliar fertilizers significantly increased N, P, K, Mg, Fe, Zn, Mn, and Cu at technological maturity, as well as P, Ca, Mg, Fe, Zn, Mn, Cu, and N at physiological maturity. However, in Kurtovska kapija, the treatments increased only Ca at technological maturity and only P at physiological maturity. The effect of treatments on fruit morphological properties was observed only at the second harvest. In Šorokšari, calcite nanoparticles (3% and 5%) increased the fruit length, minimal circle area, and minimal circle radius, and it decreased the fruit width and convex hull compared to the positive and negative controls, respectively. In Kurtovska kapija, calcite nanoparticles increased the fruit width and convex hull compared to the controls. At physiological maturity, lower anthocyanin and chlorophyll indices were found in Kurtovska kapija in both treatments with calcite nanoparticles, while in Šorokšari, the opposite effects were observed.

The Control of Multi-Bending: A Flexible Method to Fabricate Complex Structural Parts

1994 ◽  
Author(s):  
Jack X. Luo ◽  
Kim A. Stelson
Keyword(s):  
Process Model ◽  
Transfer Functions ◽  
Control Method ◽  
Dimensional Accuracy ◽  
High Productivity ◽  
Bending Process ◽  
Shape Errors ◽  
Complex Structural ◽  
Structural Parts ◽  
Machine Operator

Abstract The CNC multi-axis bending process can achieve high productivity and flexibility over conventional forming processes for fabricating long slender structural components of arbitrary shape. However, generating a CNC program to produce an accurate part shape is currently a laborious procedure involving trial-and-error by the machine operator. A systematic method has been developed to replace the manual control method and increase the dimensional accuracy. The concept of an intrinsic representation from differential geometry is applied as a basis to represent the part shape and develop the process model. The feedback control is derived from two transfer functions that represent the bending and twisting processes. By applying shape errors to the inverse transfer functions, incremental control commands can be determined and used to improve the control performance. Experimental results have demonstrated that shape errors decrease on subsequent iterations.

scholarly journals Powdery mildew of Allium species caused by Oidiopsis taurica in Brazil

2004 ◽  
Vol 22 (4) ◽  
pp. 758-760 ◽  
Author(s):  
Ailton Reis ◽  
Leonardo S. Boiteux ◽  
Milton L. Paz-Lima ◽  
Patrícia P. Silva ◽  
Carlos A. Lopes
Keyword(s):  
Powdery Mildew ◽  
Allium Sativum ◽  
Leaf Surface ◽  
Federal District ◽  
Sweet Pepper ◽  
Host Specialization ◽  
Vegetable Crops ◽  
Allium Species ◽  
Powdery Mildew Disease ◽  
Fungal Colony

Oidiopsis taurica Salmon (Syn. Oidiopsis sicula Scalia) was identified as the causal agent of a powdery mildew disease occurring on distinct Allium species in Brazil. This disease was initially observed in plastic house and field-grown garlic (Allium sativum) and leek (A. porrum) accessions in Brasília (Federal District) and in field-grown and greenhouse onion (A. cepa) cultivars in Belém do São Francisco (Pernambuco State) and Brasília, respectively. Typical symptoms consisted of chlorotic areas on the leaf surface corresponding to a fungal colony. These lesions turned to a brownish color with the progress of the disease. Fungi morphology was similar to that described for O. taurica. Endophytic mycelium emerging through estomata, light pale conidia were dimorphic (lanceolate primary conidia and somewhat cylindrical secondary conidia), fibrosin bodies were absent, conidia formed predominantly single (not in chains), and appressoria were non-lobed. Its sexual stage, Leveillula taurica (Lev.) Arnaud, was not observed. Inoculations were performed with the O. taurica isolates from distinct Allium hosts. These isolates were also pathogenic to sweet pepper and tomato, indicating an apparent absence of host specialization. One bunching onion (A. fistulosum) accessions was not infected by O. taurica suggesting that this species might carry useful resistance alleles to this pathogen. This is the first formal report of a powdery mildew disease on species of the genus Allium in Brazil. This disease might become important on these vegetable crops especially in hot and dry areas such as those in the Central and Northeast regions of Brazil.

scholarly journals Fruit characteristics of new pepper variety "NS Prva"

2021 ◽  
Vol 27 (1) ◽  
pp. 1-6
Author(s):  
Dario Danojević ◽  
Slađana Medić-Pap ◽  
Svetlana Glogovac
Keyword(s):  
Open Field ◽  
Sweet Pepper ◽  
Fruit Weight ◽  
Vegetable Crops ◽  
Yellow Colour ◽  
Fruit Type ◽  
Light Yellow ◽  
The Republic ◽  
The Many ◽  
Cold Chamber

Pepper (Capsicum annuum) is one of the major vegetable species in the world, and Serbia as well. The pepper assortment of the Institute of Field and Vegetable Crops includes varieties of different fruit type such as the bell, conical, kapia, elongated, pepperoni and tomato-shaped peppers. However, in the assortment of the Institute, there is no variety of sweet pepper with conical and hanging fruits. Because of that, we wanted to develop a new pepper variety with this fruit type and offer it to the market. Selected lines from one of the crossbreeding combinations were grown in the open field and the greenhouse area by the pedigree method in the period 2012-2017. Based on the phenotype, the most vital plants that had the desired characteristics of the fruit were selected. During the many years of breeding, a new pepper variety NS Prva was obtained. NS Prva has been registered in the Republic of Serbia in 2019 and from that period it has been on the National variety list. The fruits of this variety are about 150 g, have one peak, grow hanging on the plant, with light yellow colour in technological maturity, and red in full maturity. A new pepper variety NS Prva is recommended for growing in a greenhouse where it gives uniform fruits suitable for the market in all maturity stages. It can also be recommended for growing in the open field where it gives slightly longer fruits. NS Prva showed good storage ability three weeks after harvest since it had the smallest reduction in fruit weight during storage in a cold chamber

scholarly journals A New Local Sustainable Inorganic Material for Soilless Culture in Spain: Granulated Volcanic Rock

HortScience ◽  
2014 ◽  
Vol 49 (12) ◽  
pp. 1537-1541 ◽  
Author(s):  
Judith Pozo ◽  
Juan E. Álvaro ◽  
Isidro Morales ◽  
Josefa Requena ◽  
Tommaso La Malfa ◽  
...  
Keyword(s):  
Volcanic Rock ◽  
Sweet Pepper ◽  
Fruit Production ◽  
Pollutant Emissions ◽  
Limiting Factor ◽  
Vegetable Crops ◽  
Physical Chemical ◽  
Geological Origin ◽  
The University

Volcanic rock has been used for decades as a horticultural substrate worldwide. In Spain, the use of this material as a substrate is ancient; it was initially used in the Canary Islands because of its volcanic geological origin. At the University of Almería (Almería, Spain), three independent vegetable crops were grown under greenhouse conditions: sweet pepper, tomato, and melon. The volcanic rock came from a location in the geographic center of Spain, which facilitated logistics. Bags of volcanic rock (25 L) were used and were compared with a commercial coconut fiber substrate of an equal volume. All physical, physical–chemical, and chemical parameters of the volcanic rock were determined using European standard analytical procedures. Fertigation was applied, independently adapted to the physical, physical–chemical, and chemical characteristics of each substrate. The cultures were performed under a randomized complete block experimental design. Fertigation parameters, pollutant emissions, fruit production, and the quality of each culture were measured. The results showed that the assessed parameters of the volcanic rock substrate are not a limiting factor for its use as a horticultural substrate. The resultant production and quality were very similar among the three crops compared with a widely used commercial control. Therefore, volcanic rock emerges as a local, sustainable alternative to be used for soilless crop cultivation.

scholarly journals Without substrate technology of the intensive grow light of green crops

2018 ◽  
Vol 1 ◽  
pp. 46-52
Author(s):  
Kononchuk P.IU. ◽  
KHomiakov IU.V. ◽  
Gurova T.A. ◽  
Vertebnyi V.E. ◽  
Sudakov V.L. ◽  
...  
Keyword(s):  
Environmental Pollution ◽  
Crop Production ◽  
Production Waste ◽  
Vegetable Crops ◽  
High Quality ◽  
High Productivity ◽  
Environmental Situation

Designed for off-season (or year-round) cultivation of high-quality products, including in areas requiring special attention to the environmental situation, without substrate technologies of grow light of green crops and spicy-flavoring vegetable crops are aimed at reducing environmental pollution by production waste. The use of the possibilities of intensive grow light for crop production ensures their high productivity.

scholarly journals New varieties of vegetable cowpea (Vigna unguiculata subsp. sesquipedalis (L.) Verdc.) and prospects of their cultivation in southern Russia

2019 ◽  
pp. 33-37
Author(s):  
Marina O. Burlyaeva ◽  
Mariya V. Gurkina ◽  
Pavel A. Chebukin ◽  
Irina N. Perchuk ◽  
Elena V. Miroshnichenko
Keyword(s):  
Vigna Unguiculata ◽  
Far East ◽  
Growing Season ◽  
Climatic Conditions ◽  
Vegetable Crops ◽  
High Productivity ◽  
Pod Yield ◽  
Experiment Station ◽  
State Register

Relevance. Currently, there is an interest in this country in vegetable varieties of Vigna unguiculata subsp. sesquipedalis (L.) Verdc. However, a small number of varieties adapted to different cultivation conditions prevents a wider distribution of this crop. The present work was aimed at creating new vegetable cowpea varieties adapted to the climatic conditions of southern regions of Russia.Materials and methods. The study was carried out in 1998-2018 in the Astrakhan Province (Astrakhan Experiment Station) and in 2012-2018 in Primorsky Territory (Far East Experiment Station). Vegetable cowpea accessions from the global VIR collection were studied.Results. Many years of breeding have resulted in creation of such varieties as ‘Astrakhanskaya krasavitsa’, ‘Kaspiyskaya zarya’, ‘Zhemchyuzhina Kaspiya’ and ‘Lyanchihe’, which were included in the State Register of Breeding Achievements in 2019. All varieties are characterized by earliness, high productivity, excellent quality of vegetable pods, high protein content in pods in the technical ripeness phase (29.5-33.5%), and by low demand to the soil fertility. ‘Zhemchyuzhina Kaspiya’, ‘Astrakhanskaya krasavitsa’ and ‘Kaspiyskaya zarya’ are tolerant to high temperatures, air drought and soil salinity. The growing season for these varieties lasts 62-68 days in the Astrakhan Province under irrigation, while technical ripeness of pods occurs in 46-50 days. The green pod yield is 16.1–28.2 t/ha and the seed yield is 1.91-2.71 t/ha. The ‘Lyanchihe’ variety tolerates humidity well; its growing season in southern Primorsky Territory is 97-110 days, and pods reach technical ripeness in 61-70 days. The green pod yield is 21.0-24.0 t/ha, and that of seeds is 2.38-2.64 t/ha. The released varieties will broaden the range of vegetable crops cultivated in this country and improve the quality of nutrition of the population.

Land-Ocean interactions at the southwest Greenland margin during the Holocene

2020 ◽  
Author(s):  
Estelle Allan ◽  
Anne de Vernal ◽  
Marit-Solveig Seidenkrantz ◽  
Claude Hillaire-Marcel ◽  
Christof Pearce ◽  
...  
Keyword(s):  
Transfer Functions ◽  
Greenland Ice Sheet ◽  
Sea Surface ◽  
Human Occupation ◽  
Ice Dynamics ◽  
Surface Conditions ◽  
The Holocene ◽  
High Productivity ◽  
Holocene Thermal Maximum ◽  
Greenland Margin

<p>Palynomorph analysis of marine cores raised off Nuuk (southwestern Greenland) provided records of sea-surface conditions and climate-ocean-ice dynamics at centennial resolution over the last 12,000 years. Transfer functions using dinocyst assemblages provided information about the sea-ice cover, seasonal sea-surface temperature (SST) and salinity (SSS), as well as primary productivity. At about 10,000 cal. years ago, an increase in species diversity and the rapid increase of phototrophic taxa (light-dependent), marks the onset of interglacial conditions, with summer temperature increasing up to ~10°C during the Holocene Thermal Maximum (HTM). Low SSS and high productivity conditions are recorded during the interval, which we associate to increased meltwater and nutrient input from the Greenland Ice Sheet. After ~5000 cal. years BP, the decrease of phototrophic taxa marks a two-steps cooling associated with the Neoglacial trend. Since ~2000 cal. years BP, an increase in the high-frequency variability of sea surface conditions is noticeable. The second step change towards colder and more unstable conditions starting about 3000 cal. years BP coincides with the disappearance of the Saqqaq culture. The gap of human occupation in western Greenland, between the Dorset and the Norse settlements, i.e., from ca. 2000 to 1000 cal. years BP, may thus be linked to the highly unstable conditions in surface waters.</p>

Multiple-Model Adaptive Control of a Hybrid Solid Oxide Fuel Cell Gas Turbine Power Plant Simulator

2017 ◽  
Author(s):  
Alex Tsai ◽  
Paolo Pezzini ◽  
David Tucker ◽  
Kenneth M. Bryden
Keyword(s):  
Adaptive Control ◽  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Gas Turbine ◽  
Transfer Functions ◽  
Solid Oxide ◽  
Critical Parameters ◽  
Oxide Fuel ◽  
Multiple Model ◽  
Multiple Model Adaptive Control

A Multiple Model Adaptive Control (MMAC) methodology is used to control the critical parameters of a Solid Oxide Fuel Cell Gas Turbine (SOFC-GT) cyberphysical simulator, capable of characterizing 300kW hybrid plants. The SOFC system is comprised of a hardware Balance of Plant (BoP) component, and a high fidelity FC model implemented in software. This study utilizes empirically derived Transfer Functions (TF) of the BoP facility to derive the multi model adaptive controller (MMAC) gains for the BoP system, based on an estimation algorithm which identifies current operating points. The MMAC technique is useful for systems having a wide operating envelope with nonlinear dynamics. The practical implementation of the adaptive methodology is presented through simulation in the MATLAB/SIMULINK environment.

scholarly journals Chemical characteristics of size-resolved atmospheric aerosols in Iasi, north-eastern Romania: nitrogen-containing inorganic compounds control aerosol chemistry in the area

2018 ◽  
Vol 18 (8) ◽  
pp. 5879-5904 ◽  
Author(s):  
Alina Giorgiana Galon-Negru ◽  
Romeo Iulian Olariu ◽  
Cecilia Arsene
Keyword(s):  
Atmospheric Aerosols ◽  
Inorganic Compounds ◽  
Mixing Layer ◽  
Warm Season ◽  
Cold Season ◽  
Critical Parameters ◽  
Aerosol Chemistry ◽  
Aerosol Mass Concentration ◽  
Fine Particulate ◽  
North Eastern

Abstract. This study assesses the effects of particle size and season on the content of the major inorganic and organic aerosol ionic components in the Iasi urban area, north-eastern Romania. Continuous measurements were carried out over 2016 using a cascade Dekati low-pressure impactor (DLPI) performing aerosol size classification in 13 specific fractions over the 0.0276–9.94 µm size range. Fine-particulate Cl−, NO3-, NH4+, and K+ exhibited clear minima during the warm season and clear maxima over the cold season, mainly due to trends in emission sources, changes in the mixing layer depth and specific meteorological conditions. Fine-particulate SO42- did not show much variation with respect to seasons. Particulate NH4+ and NO3- ions were identified as critical parameters controlling aerosol chemistry in the area, and their measured concentrations in fine-mode (PM2.5) aerosols were found to be in reasonable good agreement with modelled values for winter but not for summer. The likely reason is that NH4NO3 aerosols are lost due to volatility over the warm season. We found that NH4+ in PM2.5 is primarily associated with SO42- and NO3- but not with Cl−. Actually, indirect ISORROPIA-II estimations showed that the atmosphere in the Iasi area might be ammonia rich during both the cold and warm seasons, enabling enough NH3 to be present to neutralize H2SO4, HNO3, and HCl acidic components and to generate fine-particulate ammonium salts, in the form of (NH4)2SO4, NH4NO3, and NH4Cl. ISORROPIA-II runs allowed us to estimate that over the warm season ∼ 35 % of the total analysed samples had very strongly acidic pH (0–3), a fraction that rose to ∼ 43 % over the cold season. Moreover, while in the cold season the acidity is mainly accounted for by inorganic acids, in the warm ones there is an important contribution by other compounds, possibly organic. Indeed, changes in aerosol acidity would most likely impact the gas–particle partitioning of semi-volatile organic acids. Overall, we estimate that within the aerosol mass concentration the ionic mass brings a contribution as high as 40.6 %, with the rest still being unaccounted for.

Sign in / Sign up

Export Citation Format

Share Document