The Influence of Natural Ventilation to the Thermal and Moisture Environment in a Passive Greenhouse

2011 ◽  
Vol 374-377 ◽  
pp. 57-61
Author(s):  
Lin Hua Zhang ◽  
Li Na Chang
Keyword(s):  
Natural Ventilation ◽  
High Reliability ◽  
Flow Temperature ◽  
Temperature And Humidity ◽  
And Control ◽  
Temporal Field ◽  
Homogeneous Temperature ◽  
Humidity Profiles ◽  
Humidity Field ◽  
Typical Soil

The temperature and humidity profiles in spatial and temporal field inside the greenhouse are coupled to outside climates. Took a typical soil-walled passive greenhouse located in Jinan, Shandong, China as an example, an unsteady tri-dimensional numerical simulation was applied to solve the temperature and humidity profiles under natural ventilation conditions inside the greenhouse, based on the CFD program. The measurement was carried out to validate the CFD model, the results showed that the special temperature and humidity gradient were obvious inside the greenhouse, a homogeneous temperature and humidity field was obtained at crop level. The simulation results agree well with test values about the temperature and humidity inside the greenhouse with fitting degree of 99.8% and 99.7%, respectively. With high reliability, the model can be used as the basis to predict and control the environment inside the greenhouse. Greenhouse with natural ventilation under different wind conditions was simulated on a typical sunny day to predict the distribution of air flow, temperature and humidity field. By analyzing, some useful conclusions which can provide certain basis about the influence of natural ventilation on the thermal and moisture environment are deduced.

Application of PID in Controllable Pitch Propeller of a Multipurpose Ocean Tug

2013 ◽  
Vol 464 ◽  
pp. 253-257
Author(s):  
Hui Fang Chen
Keyword(s):  
Control System ◽  
Automatic Control ◽  
Automatic Control System ◽  
High Reliability ◽  
Control Process ◽  
Good Control ◽  
Control Performance ◽  
Hardware Configuration ◽  
Design Idea ◽  
And Control

This paper takes the automatic control system of controllable pitch propeller in a multipurpose ocean tug as an example to describe the application of the S7-200 series PLC in the control system of 4500 horse power controllable pitch propeller in detail. The principle of control system is addressed, as well as the hardware configuration, the design idea of the main software and control process. The system shows high reliability, accuracy and good control performance in practical in practical running.

Research of Multi-Channel Hygrothermoscope Acquiring System

2012 ◽  
Vol 214 ◽  
pp. 177-182
Author(s):  
Xiao Bing Wu
Keyword(s):  
Air Conditioning ◽  
High Reliability ◽  
Temperature Data ◽  
Simple Circuit ◽  
Control Room ◽  
Host Machine ◽  
Humidity Transducer ◽  
And Control ◽  
Humidity Monitoring ◽  
Conditioning Control

The paper introduces a multipoint remote Hygrothermoscope monitoring system based on the MAX485 bus. The system of remote multipoint temperature control is composed of the host machine and slave machine; the host system for display and control, the slave system is responsible for collecting temperature data. Between master machine and slave machine communicate through the RS-485 bus, can realize the distant control room of the scene monitoring. The STC89C54 MCU is used as the controller and DHT11 is used as the temperate and humidity transducer. The hardware and software of the system are outlined. The system has realized multiple measuring points, easy expansion, and high reliability, anti-interference. The whole system has the advantages of simple circuit, reliable, and can be used for measuring temperature, humidity, temperature of building air conditioning control temperature and humidity monitoring and other fields.

The Application of S7-200 PLC Reactive Compensation Device in Small Substation

2012 ◽  
Vol 479-481 ◽  
pp. 1476-1480
Author(s):  
Qing He Chu ◽  
Wen Si Cao ◽  
Zhen Nie
Keyword(s):  
Reactive Power ◽  
Control Method ◽  
High Reliability ◽  
Reactive Power Compensation ◽  
Control Device ◽  
Reactive Compensation ◽  
Reconstruction Project ◽  
Compensation Device ◽  
And Control

In the present rural power grid reconstruction project ,according to the problems of capacitor reactive power compensation in rural small substation. Take a small substation for instance, according to its operation and control method, set the criterion of the capacitor bank switching. A new high reliability, flexible reactive power compensation control device based on s7-200 PLC is designed. It plays an important role in improving the power supply , guaranteeing the quality of voltage, reducing the loss of rural power gid.

Capturing the Familiness of Family Businesses: Development of the Family Influence Familiness Scale (FIFS)

2017 ◽  
Vol 41 (5) ◽  
pp. 709-742 ◽  
Author(s):  
Hermann Frank ◽  
Alexander Kessler ◽  
Thomas Rusch ◽  
Julia Suess–Reyes ◽  
Daniela Weismeier–Sammer
Keyword(s):  
High Reliability ◽  
Family Members ◽  
Reliability And Validity ◽  
Family Influence ◽  
Factor Analyses ◽  
Confirmatory Factor Analyses ◽  
Proficiency Level ◽  
Confirmatory Factor ◽  
The Family ◽  
And Control

This article develops a familiness scale measuring the family influence on the business via decision premises that express familiness. In three studies, we examine familiness with qualitative and quantitative approaches based on new systems theory. Narrative interviews are employed to generate items. Exploratory and confirmatory factor analyses led to a multidimensional scale (Family Influence Familiness Scale [FIFS]) comprising six dimensions: (1) ownership, management, and control; (2) proficiency level of active family members; (3) sharing of information between active family members; (4) transgenerational orientation; (5) family–employee bond; and (6) family business identity. Results indicate high reliability and validity levels.

Sign in / Sign up

Export Citation Format

Share Document