Cooling capacity assessment of semi-closed greenhouses

Leading Dutch researchers have reported significant benefits of closed greenhouse systems. Ooteghem (2007) predicted reduced heating fuel consumption and increased crop yield. Opdam et al. (2005) found 19% primary energy use saving, 22% tomatoes production increase, 80% chemical reduction, and 50% irrigation water saving can be achieved in a closed greenhouse. This research proposes to develop a design analysis tool to determine cooling/dehumidification needs, and proper cooling capacity needed to minimize greenhouse ventilation economically for northern climate. A preliminary analysis shows it is expensive to keep greenhouses in Ohio closed year round. Further analysis suggests better return maybe achieved with semi-closed greenhouse designs instead of fully closed operation. For example, a 50% peak load design can meet cooling needs 90% of the time yearly. The proposed tool can be used to specify internal cooling capacity requirements for desired greenhouse closure level.Cooperative State Research, Education, and Extension Service of United States Department of AgricultureOhio Agricultural Research and Development Cente

Cooling capacity assessment of semi-closed greenhouses

Leading Dutch researchers have reported significant benefits of closed greenhouse systems. Ooteghem (2007) predicted reduced heating fuel consumption and increased crop yield. Opdam et al. (2005) found 19% primary energy use saving, 22% tomatoes production increase, 80% chemical reduction, and 50% irrigation water saving can be achieved in a closed greenhouse. This research proposes to develop a design analysis tool to determine cooling/dehumidification needs, and proper cooling capacity needed to minimize greenhouse ventilation economically for northern climate. A preliminary analysis shows it is expensive to keep greenhouses in Ohio closed year round. Further analysis suggests better return maybe achieved with semi-closed greenhouse designs instead of fully closed operation. For example, a 50% peak load design can meet cooling needs 90% of the time yearly. The proposed tool can be used to specify internal cooling capacity requirements for desired greenhouse closure level.Cooperative State Research, Education, and Extension Service of United States Department of AgricultureOhio Agricultural Research and Development Cente

A Tool to Assess Heating Efficiency of Direct-fired Heater with the Impact of Humidity Control

Heating is one of the top two expenses of greenhouse operations in northern climates. Direct-fired heater (DFH) that has been promoted having high heating efficiency, 99.9%, compared to 80-94% of conventional indirect-fired heaters (IFH), could be an energy efficient choice. However, the high efficiency claim does not consider energy lost through air intake during combustion process. Fresh air intake is important for clean combustion and extra dehumidification for the water vapor generated from the combustion process to maintain a healthy environment for plant growth. The actual heating efficiency of a DFH is affected by amount of fresh air intake where higher air intake rate causes lower heating efficiency. A decision support tool (the tool, thereafter) was developed to determine the minimum air intake needs for the combustion and water removal, thus, the highest net heating efficiency of a DFH can achieve. In a case study, the tool predicted that a DFH had a net heating efficiency of 86%. The prediction was verified with field experiments to compare heating performance of the DFH to a popular IFH. The results showed varied DFH heating efficiency that was affected by the heater operation strategy to regulate fresh air intake rate. A higher heating efficiency was achieved with a fresh air intake rate determined by the tool. The DFH consumed 8.8% less fuel than that of the IFH. The field tested DFH heating efficiency was 87% which was in close agreement with the prediction of the tool.Ohio Agricultural Research and Development Cente

Identification, Growth Kinetics And Cell Disintegration Of Mru5, A Bacterium Isolated From An Oil Well In Sarawak, Malaysia

A hyperthermophilic bacterium, coded MRU5 was isolated from an oil-producing well in Sarawak, Malaysia. This microorganism was found to be a strictly anaerobic sulphate-reducing bacteria. Since this bacteria can survive and carry out its functions at extremely harsh conditions (high pressure, high temperature, high salinity), it is postulated that the enzymes isolated would be highly suitable for use in industrial processes, which need enzymes to be robust and stable. In this study, the cell disruption methods of the bacterium were optimized and the activity of possible industrial thermostable extracellular enzymes such as xylanases, lipases and amylolytic enzymes were determined. The bacterium, has an irregular coccoid shape, is Gram negative, and is able to grow at 90oC, pH 7.0 and high salinity (10% NaCl). It is resistant to antibiotic such as ampicillin, chloramphenicol, kanamycin, rifampin, streptomycin, tetracycline and geneticin. Based on this profile, MRU5 is suggested to be a new species under the halothermophile Archaea family. 16S rRNA sequencing failed to identify the taxanomy because of limitation of universal PCR primers. Amylase, xylanase and lipase had been isolated extracellularly with the activity of 11.8 U/L, 82.1 U/L and 7.61 U/L, respectively. Amylase was chosen for cell breakage studies as an indicator. Different methods of cell breakage were applied to obtain a high intracellular enzyme activity. The methods used were bead miller, lysozyme and combinations of bead mill with ultrasonicator and high pressure homogenizer. The breakages of cells were observed under scanning electron microscope. Amylase activity was detected intracellularly as well as on the membrane. Cell disruption treatment with only bead mill with 6g of glass beads recorded the highest specific enzyme activity (1.81 U/mg) at hour 3 where it is almost double compared to combination of bead mill and ultrasonication (0.983 U/mg) at similar time

Spin susceptibility and the pi-excitation in underdoped cuprates

The dynamical spin susceptibility chi'' at wave vector (pi, pi) and the spectrum pi'' of the spin-triplet particle--particle excitation with center of mass momentum (pi, pi) (pi-excitation) are considered in the slave-boson formulation of the t--J-model. Propagators are calculated in a diagrammatic t-matrix approximation in the d-wave superconducting state for a wide doping range. The resulting spectra chi'' and pi'' both show a resonance at a doping dependent energy, in qualitative agreement with recent numerical cluster calculations. In underdoped systems, the peak position is comparable to that found in neutron scattering experiments. The peak in chi'' as well as pi'' is at low doping entirely caused by spin fluctuations, whereas the triplet particle--particle channel does not contribute as a collective mode.Comment: 3 pages, 4 eps-figures included, uses revtex, eps

Writing Transition in Postsecondary Education: A Case Study

AbstractThis study looks at writing transition from the culture of writing in pre-university to the culture of writing in university in the Malaysian context. A multiple case study was conducted among six students. Data was collected through personal interviews, personal narratives, class observations and written texts over a period of one and a half years. The study is based on Vygotsky's sociocultural theory. The findings indicate that students faced tensions in the writing transition. These tensions and their appropriation of the writing cultures were impacted by their sociocultural historical makeup and point to a need to review current writing practices in postsecondary education

Relationship Between Emotional Intelligence and Resilience Among Newly Licensed Registered Nurses Transitioning to the Professional Role

Background: With the current nursing shortage there are fewer experienced nurses and more newly licensed registered nurses (NLRNs) in the workplace. This shortage may be due in part to inconsistencies between role expectations learned in school and the practice environment. These inconsistencies may make it challenging to transition from nursing school into professional healthcare organizations. Nurses with certain person-level traits, including resilience and emotional intelligence, may be more likely to make a successful transition into practice. Findings may improve our understanding of what person-level traits are important for making the successful transition to the workforce. Purpose: The current study explored whether emotional intelligence (EI) and resilience influenced transition into professional roles. Theoretical Framework: Understanding how cultural shock and adaptation are challenging for many NLRNs is important. Duchscher transition theory provided an overview of how NLRNs engaged in the professional practice role as they are confronted with the realities of the work environment. Methods: A non-experimental research design with descriptive cross-sectional study is used to determine if EI and resilience have any effect on NLRNs transitioning into their professional roles. Results: With a sample size of 63, there is a direct positive linear relationship between resilience and global trait EI and its subscales for NLRNs. The correlation is significant with the exception of the EI subscale emotionality. Also there was no significance with NLRNs who transitioned in a critical care setting and those in other specialty care areas. Conclusions: There is a need for further exploration of this relationship with a larger sample size and the need to investigate person-level characteristics in NLRNs who successfully transition to their professional role