scholarly journals Optimal Airflow Control of Laboratory Air Handling Unit (LAHU) Systems

2004 ◽  
Vol 126 (2) ◽  
pp. 750-758 ◽  
Author(s):  
Yujie Cui ◽  
Mingsheng Liu ◽  
Kirk Conger
Keyword(s):  
Linear Optimization ◽  
Weather Conditions ◽  
Optimization Method ◽  
Energy Characteristics ◽  
Laboratory Section ◽  
Air Handling Unit ◽  
Air Temperatures ◽  
Laboratory Supply ◽  
Air Intake ◽  
Air Control

The Laboratory Air Handling Unit (LAHU) system conditions both the office section and the laboratory section. It improves indoor air quality by maximizing outside air intake to the office section and minimizes thermal energy consumption by re-circulating the office section air to the laboratory section. This paper presents a theoretical linear optimization method and results of optimal outside air control in LAHUs. The optimal outside airflows are expressed as functions of the weather conditions (outside air temperature and enthalpy), office and laboratory airflow rates, office and laboratory supply air temperatures, and four dimensionless parameters that describe the building system and energy characteristics. The optimization method used in this paper can be used to identify the optimal control schedules in other HVAC systems.

Optimal Outside Airflow Control of an Integrated Air-Handling Unit System for Large Office Buildings

2004 ◽  
Vol 126 (1) ◽  
pp. 614-619 ◽  
Author(s):  
L. Song ◽  
M. Liu
Keyword(s):  
Air Temperature ◽  
Linear Optimization ◽  
Optimization Method ◽  
Geometric Optimization ◽  
Variable Air Volume ◽  
Unit System ◽  
Analytical Functions ◽  
Air Handling Unit ◽  
Conventional Systems ◽  
Air Control

This paper presents optimal outside air control schedules for an integrated air-handling unit system for large commercial buildings (OAHU). The schedules are developed using the geometric linear optimization method and expressed as analytical functions of the outside air temperature and enthalpy, the interior zone airflow ratio, and the exterior zone supply air temperature. The optimal outside air control schedules can be applied to both constant and variable air volume systems. When the schedules are implemented, the OAHU system can significantly improve indoor air quality (IAQ) and use significantly less thermal energy than conventional systems. The geometric optimization method can also be used in other linear HVAC optimizations with non-liner constraint conditions.

Optimal Outside Airflow Control of Integrated Air Handling Unit System for Large Office Buildings

Solar Energy ◽  
2003 ◽  
Author(s):  
L. Song ◽  
M. Liu
Keyword(s):  
Air Temperature ◽  
Linear Optimization ◽  
Optimization Method ◽  
Geometric Optimization ◽  
Variable Air Volume ◽  
Unit System ◽  
Analytical Functions ◽  
Air Handling Unit ◽  
Conventional Systems ◽  
Air Control

This paper presents the optimal outside air control in the integrated air handling unit system for large commercial buildings (OAHU). The optimal outside air control schedules are developed using the geometric linear optimization method, and expressed as analytical functions of the outside air temperature and enthalpy, the interior zone airflow ratio, and the exterior zone supply air temperature. The optimal outside air control schedules can be applied to both constant and variable air volume systems. When the optimal outside air control schedules are implemented, the OAHU system can significantly improve indoor air quality (IAQ) and use significantly less thermal energy than conventional systems. The geometric optimization method can also be used in other linear HVAC optimizations with non-liner constraint conditions.

Vulnerability of sweet cherry cultivars to continuous periods of spring frosts in Plovdiv, Bulgaria

2020 ◽  
Vol 12 (4) ◽  
pp. 348-352
Author(s):  
S. Malchev ◽  
S. Savchovska
Keyword(s):  
Sweet Cherry ◽  
Weather Conditions ◽  
Frost Damage ◽  
Cold Weather ◽  
Bud Burst ◽  
Intermediate Group ◽  
Air Temperatures ◽  
Wide Range ◽  
Group Form ◽  
Sweet Cherry Cultivars

Abstract. The periods with continuous freezing air temperatures reported during the spring of 2020 (13 incidents) affected a wide range of local and introduced sweet cherry cultivars in the region of Plovdiv. They vary from -0.6°C on March 02 to -4.9°C on March 16-17. The duration of influence of the lowest temperatures is 6 and 12 hours between March 16 and 17. The inspection of fruit buds and flowers was conducted twice (on March 26 and April 08) at different phenological stages after continuous waves of cold weather conditions alternated with high temperatures. During the phenological phase ‘bud burst’ (tight cluster or BBCH 55) some of the flowers in the buds did not develop further making the damage hardly detectable. The most damaged are hybrid El.28-21 (95.00%), ‘Van’ (91.89%) and ‘Bing’ (89.41%) and from the next group ‘Lapins’ (85.98%) and ‘Rosita’ (83.33%). A larger intermediate group form ‘Kossara’ (81.67%), ‘Rozalina’ (76.00%), ‘Sunburst’ (75.00%), ‘Bigarreau Burlat’ (69.11%) and ‘Kuklenska belitza’ (66.67%). Candidate-cultivar El.17-90 ‘Asparuh’ has the lowest frost damage values of 55.00% and El.17-37 ‘Tzvetina’ with damage of 50.60%.

scholarly journals Performance Evaluation of a CO2 Refrigeration System Enhanced with a Dew Point Cooler

Energies ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 1079 ◽  
Author(s):  
Martin Belusko ◽  
Raymond Liddle ◽  
Alemu Alemu ◽  
Edward Halawa ◽  
Frank Bruno
Keyword(s):  
Weather Conditions ◽  
Dew Point ◽  
Coefficient Of Performance ◽  
Experimental Program ◽  
Refrigeration System ◽  
Conventional System ◽  
Ambient Temperatures ◽  
Air Temperatures ◽  
Condenser Temperature

Dew point cooling (DPC) is a novel indirect evaporative cooling concept capable of delivering air temperatures approaching the dew point. Coupling this technology with CO2 refrigeration is well suited to minimising transcritical operation when the coefficient of performance (COP) is dramatically reduced in hot climates. A substantial experimental program was conducted to characterise this combination by testing a 20 kW CO2 refrigeration system subject to ambient temperatures above 40 °C. It was demonstrated that DPC operation not only avoided transcritical operation during such weather conditions, but also increased the COP by up to 140% compared to the conventional system. The combination of these technologies was successfully mathematically modelled, from which the optimum condenser inlet air temperature was identified for each condenser temperature. Using this optimum condition, it was possible to maximise the COP for a range of conditions applicable to the psychometric chart. An annual case study for Adelaide, Australia was conducted which demonstrated that optimally coupling DPC with CO2 refrigeration can reduce the annual energy consumption and peak demand by 16% and 47%, respectively, compared to a conventional CO2 booster system. Furthermore, the number of hours of transcritical operation was reduced from 3278 to 27.

scholarly journals Sugar accumulation in winter wheat crops depending on the sowing dates

2019 ◽  
Vol 49 (2) ◽  
pp. 27-33
Author(s):  
S. I. Anosov ◽  
A. S. Surnachev ◽  
K. K. Musinov
Keyword(s):  
Winter Wheat ◽  
Coefficient Of Variation ◽  
Sugar Content ◽  
Weather Conditions ◽  
Sugar Accumulation ◽  
Planting Dates ◽  
Air Temperatures ◽  
Sowing Dates ◽  
Soft Winter Wheat ◽  
Growing Conditions

The object of the research was to study the influence of sowing dates on sugar accumulation in different varieties of soft winter wheat. Less winterhardy variety of soft winter wheat Novosibirskaya 2 was compared with more winter-hardy ones Novosibirskaya 3, Novosibirskaya 40 and Krasnoobskaya ozimaya. The research was carried out in 2016-2018 inthe established experimental plot in the foreststeppe of Priobye, theObregion. The predecessor was bare fallow. The planting dates were August 20, September 1, September 10. Weather conditions of the autumn growing season, during which the accumulation of sugars occurs, differed significantly depending on the year of study and the sowing dates. The warmest conditions were in 2018, whereas the coolest – in 2017. The amount of accumulated sugars varied depending on the growing conditions and genotypic characteristics of varieties. The highest amount of sugars was accumulated by all varieties during the third term of planting, the lowest amount – during the second term. Lower air temperatures contributed to the increase in the amount of sugars, even when the duration of their accumulation period was shortened, which can be explained by a change in carbohydrate balance in crops when the accumulation of sugars is greater than their consumption for crop respiration. The genotype plays an important role in the carbohydrate metabolism of plants. In more winter-hardy varieties (Novosibirskaya 40, Novosibirskaya 3), the change in the amount of accumulated sugars in contrasting conditions ranged insignificantly (the coefficient of variation was 9.1 and 8.7%, respectively). At the same time, plants of the less winter-hardy variety of Novosibirskaya 2 showed a significantly greater variation in the sugar content under similar conditions (the coefficient of variation 24.7%). Cooler conditions of a later term of sowing contributed to the greatest amount of accumulated sugars. Varietal differences also determined changes in carbohydrate balance.

scholarly journals Fast Quadratic Shape From Shading With Unknown Light Direction

2021 ◽  
Author(s):  
Kuros Yalpani
Keyword(s):  
Linear Optimization ◽  
Quadratic Function ◽  
Optimization Method ◽  
Shape From Shading ◽  
Surface Patch ◽  
Algebraic Complexity ◽  
Surface Patches ◽  
Quadratic Surface ◽  
Least Squares Optimization ◽  
Light Source Direction

An algorithm is proposed that extracts 3D shape from shading information in a digital image. The algorithm assumes that there is only a single source of light producing the image, that the surface of the shape giving rise to the image is Lambertian (matte) and that its shape can be locally approximated by a quadratic function. Previous work shows that under these assumptions, robust shape from shading is possible, though slow for large images because a non-linear optimization method is applied in order to estimate local quadratic surface patches from image intensities. The work presented here shows that local quadratic surface patch estimates can be computed, without prior knowledge of the light source direction, via a linear least squares optimization, thus greatly improving the algebraic complexity and run-time of this existing algorithms.

scholarly journals Sea surface temperature variations in the south-eastern BalticSea in 1960–2015

Baltica ◽  
2018 ◽  
Vol 30 (2) ◽  
pp. 75-85 ◽  
Author(s):  
Viktorija Rukšėnienė ◽  
Inga Dailidienė ◽  
Loreta Kelpšaitė-Rimkienė ◽  
Tarmo Soomere
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Air Temperature ◽  
Weather Conditions ◽  
Sea Surface ◽  
South Eastern ◽  
Air Temperatures ◽  
Joint Application ◽  
Open Sea ◽  
And Cluster Analysis

This study focuses on time scales and spatial variations of interrelations between average weather conditions and sea surface temperature (SST), and long-term changes in the SST in south-eastern Baltic Sea. The analysis relies on SST samples measured in situ four times a year in up to 17 open sea monitoring stations in Lithuanian waters in 1960–2015. A joint application of non-metric multi-dimensional scaling and cluster analysis reveals four distinct SST regimes and associated sub-regions in the study area. The increase in SST has occurred during both winter and summer seasons in 1960–2015 whereas the switch from relatively warm summer to colder autumn temperatures has been shifted by 4–6 weeks over this time in all sub-regions. The annual average air temperature and SST have increased by 0.03°C yr–1 and 0.02°C yr–1, respectively, from 1960 till 2015. These data are compared with air temperatures measured in coastal meteorological stations and averaged over time intervals from 1 to 9 weeks. Statistically significant positive correlation exists between the SST and the average air temperature. This correlation is strongest for the averaging interval of 35 days.

Energy efficiency path planning for a quadrotor aerial vehicle

2021 ◽  
pp. 014233122110585
Author(s):  
Fouad Yacef ◽  
Nassim Rizoug ◽  
Laid Degaa ◽  
Omar Bouhali ◽  
Mustapha Hamerlain
Keyword(s):  
Optimal Control ◽  
Optimal Control Problem ◽  
Control Problem ◽  
Weather Conditions ◽  
Optimization Method ◽  
Control Approach ◽  
Mission Success ◽  
Aerial Vehicle ◽  
Vehicle Trajectory ◽  
Point To Point

Unmanned aerial vehicles are used today in many real-world applications. In all these applications, the vehicle endurance (flight time) is an important constraint that affects mission success. This study investigates the limitations of embedded energy for a quadrotor aerial vehicle. We consider a quadrotor simple tasked to travel from an initial hover configuration to a final hover configuration. In order to have a precise approximation of the consumed energy, we propose a power consumption model with battery dynamic, motor dynamic, and rotor efficiency function. We then introduce an optimization algorithm to minimize the energy consumption during quadrotor aerial vehicle mission. The proposed algorithm is based on an optimal control problem formulated for the quadrotor model and solved using nonlinear programming. In the optimal control problem, we seek to find control inputs (rotor velocity) and vehicle trajectory between initial and final configurations that minimize the consumed energy during a point-to-point mission. We extensively test in simulation experiments the proposed algorithm under normal and windy weather conditions. We compare the proposed optimization method with a nonlinear adaptive control approach to highlight the saved amount of energy.

Medical Emergencies During a Half Marathon Race – The Influence of Weather

2019 ◽  
Vol 40 (05) ◽  
pp. 312-316 ◽  
Author(s):  
Eric Carlström ◽  
Mats Borjesson ◽  
Gunnar Palm ◽  
Amir Khorram-Manesh ◽  
Fredrik Lindberg ◽  
...  
Keyword(s):  
Meteorological Data ◽  
Weather Conditions ◽  
Daily Maximum ◽  
Equivalent Temperature ◽  
Physiological Equivalent Temperature ◽  
Marathon Race ◽  
Air Temperatures ◽  
Medical Emergencies ◽  
Pet Index ◽  
Maximum Air Temperature

AbstractThe aim was to analyze the influence of weather conditions on medical emergencies in a half-marathon, specifically by evaluating its relation to the number of non-finishers, ambulance-required assistances, and collapses in need of ambulance as well as looking at the location of such emergencies on the race course. Seven years of data from the world’s largest half marathon were used. Meteorological data were obtained from a nearby weather station, and the Physiological Equivalent Temperature (PET) index was used as a measure of general weather conditions. Of the 315,919 race starters, 104 runners out of the 140 ambulance-required assistances needed ambulance services due to collapses. Maximum air temperature and PET significantly co-variated with ambulance-required assistances, collapses, and non-finishers (R2=0.65–0.92; p=0.001–0.03). When air temperatures vary between 15–29°C, an increase of 1°C results in an increase of 2.5 (0.008/1000) ambulance-required assistances, 2.5 (0.008/1000) collapses (needing ambulance services), and 107 (0.34/1000) non-finishers. The results also indicate that when the daily maximum PET varies between 18–35°C, an increase of 1°C PET results in an increase of 1.8 collapses (0.006/1000) needing ambulance services and 66 non-finishers (0.21/1000).

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