Sunday, March 20, 2011

The Principle of Thermostat

A thermostat is an appliance that regulates the temperature of a system so that the temperature of that system is kept at a particular desired temperature. This desired temperature is described as the 'set point' temperature. The thermostat operates by turning heating devices on or off, to maintain the temperature of a fluid at the set point temperature. The 'main' thermostat refers to the thermostat in a heating system that possesses only one thermostat.

Technological Sensor Methods

  • One of the key principles of a main thermostat, and indeed any thermostat, is the technological method by which the thermostat senses the ambient temperature. There are two main techniques by which thermostats can sense their surrounding temperature. These are bimetallic sensors and electronic thermistors. Bimetallic sensors use a strip of two metals joined together that have slightly different expansion rates in response to heat, this results in a bending of the bimetallic strip that can be used to break an electrical circuit at high enough temperatures. Electronic thermistors are an electronic component that increases its electrical resistance with increasing temperature, and as such can be used to break a circuit when a particular temperature is reached.

Feedback

  • Thermostats are based on the principle of feedback. The thermistor controls the output of a heating system. The heating system heats a fluid. When the fluid reaches a certain temperature it triggers the thermostat to reduce the heat output, usually by simply switching off the heating system. When the heating system is switched off the temperature of the fluid falls until the thermistor reactivates the heating system. This type of control system is called 'negative feedback' and is a key principle in the design of the main thermostat in many central heating systems.

Digital or Analogue

  • Another key principle of main thermostats is whether they are digital or analogue. This key principle of main thermostats is based around the idea that some thermostats work simply by turning a heating system on or off when a particular temperature is reached or constantly adjusting the heat output of the heating system across a range of possible outputs. The former are digital thermostats and the latter are analogue thermostats.

Location

  • A key principle of the main thermostat, when that thermostat is controlling a central heating system in your house, is its location in your house. If a main thermostat is poorly located it can lead to high levels of energy inefficiency and poor heating patterns. In a small house a sensible place for the location of a main thermostat is on the staircase or upstairs landing.

World's deadliest disasters ( You will get shocked if you will see )

Tsunami
a_small_boat_gets_stuck_in_a_tsunami_whirlpool
A small boat gets stuck in a tsunami whirlpool.tsunami_ploughed_into_tragic_miyako_city_japan
Tsunami ploughed into tragic Miyako city, Japan waves_of_tsunami_topple_trees
Waves of tsunami topple trees
houses_swallowed_by_tsunami
Houses swallowed by the tsunami burn in Sendai, Miyagi

houses_swept_by_a_tsunami
Houses swept by a tsunami

tsunami_hits_airport_in_sendai_japan
Tsunami hits airport in Sendai, Japan

Earthquake
fractured_road_in_japan
Fractured road, Japan

twisted_railroad_japan
Twisted railroad, Japan

collapsed_bridge_guatemala
Collapsed bridge, Guatemala

a_rupture_forms_in_road_after_an_earthquake
A rupture forms in road after an earthquake

a_massive_earthquake_struck_southwest_china
A massive earthquake struck southwest China

san_andreas_fault_california
San Andreas Fault, California

Wildfire
san_diego_wildfires
San Diego wildfires

boise_forest_fire
Boise forest fire

wildfires_force_evacuations_in_la
Wildfires force evacuations in L.A.

idaho_fire
Idaho fire

Volcano
three_volcanoes_mount_semeru_mount_bromo_and_mount_batok_in_indonesia
Three volcanoes – Mount Semeru, Mount Bromo and Mount Batok in Indonesia

mount_etna_in_italy
Mount Etna, Italy

volcanic_lightning
Volcanic lightning

two_eruptions
Two eruptions

ash_cloud
Ash cloud

Tornado
a_mother_ship_cloud_formation_hovers_over_childress_texas
A mother ship cloud formation hovers over Childress, Texas

violent_tornado_in_northeastern_iowa
Violent tornado in northeastern Iowa

water_spout
Waterspout

curved_tornado
Curved tornado

south_dakota_tornado
South Dakota tornado

big_tornado
Big tornado

Lightning
city_strike
City strike

bolts_on_the_water
Bolts on the water

cn_tower_canada
CN tower, Canada

lightning_over_miami
Lightning over Miami

lightning_at_night_walton_nebraska
Lightning at night, Walton, Nebraska

Other Natural Disasters
hurricane_ivan
Hurricane Ivan

hurricane_winds
Hurricane winds

avalanche_in_mt_rainier_national_park_in_washington
Avalanche in Mt. Rainier National Park in Washington

rock_mountain_avalanche
Rock mountain avalanche

a_sandstorm_engulfs_the_saudi_capital
A sandstorm engulfs the Saudi capital



sandstorm_strikes_israel
Sandstorm strikes Israel

How to create a stored procedure(SQL Server Management Studio)

This topic describes how to create a Transact-SQL stored procedure by using Object Explorer in SQL Server Management Studio and provides an example that creates a simple stored procedure in the AdventureWorks2008R2 database.

To create a stored procedure

  1. In Object Explorer, connect to an instance of Database Engine and then expand that instance.
  2. Expand Databases, expand the database in which the stored procedure belongs, and then expand Programmability.
  3. Right-click Stored Procedures, and then click New Stored Procedure.
  4. On the Query menu, click Specify Values for Template Parameters.
  5. In the Specify Values for Template Parameters dialog box, the Value column contains suggested values for the parameters. Accept the values or replace them with new values, and then click OK.
  6. In the query editor, replace the SELECT statement with the statements for your procedure.
  7. To test the syntax, on the Query menu, click Parse.
  8. To create the stored procedure, on the Query menu, click Execute.
  9. To save the script, on the File menu, click Save. Accept the file name or replace it with a new name, and then click Save.

    To create a stored procedure example

  10. In Object Explorer, connect to an instance of Database Engine and then expand that instance.
  11. Expand Databases, expand the AdventureWorks2008R2 database, and then expand Programmability.
  12. Right-click Stored Procedures, and then click New Stored Procedure.
  13. On the Query menu, click Specify Values for Template Parameters.
  14. In the Specify Values for Template Parameters dialog box, enter the following values for the parameters shown.
    ParameterValue
    AuthorYour name
    Create DateToday's date
    DescriptionReturns employee data.
    Procedure_nameHumanResources.uspGetEmployees
    @Param1@LastName
    @Datatype_For_Param1nvarchar(50)
    Default_Value_For_Param1NULL
    @Param2@FirstName
    @Datatype_For_Param2nvarchar(50)
    Default_Value_For_Param2NULL
  15. Click OK.
  16. In the query editor, replace the SELECT statement with the following statement:
    SELECT FirstName, LastName, JobTitle, Department
        FROM HumanResources.vEmployeeDepartment
        WHERE FirstName = @FirstName AND LastName = @LastName;
    1. To test the syntax, on the Query menu, click Parse. If an error message is returned, compare the statements with the information above and correct as needed.
    2. To create the stored procedure, on the Query menu, click Execute.
    3. To save the script, on the File menu, click Save. Enter a new file name, and then click Save.
    4. To run the stored procedure, on the toolbar, click New Query.
    5. In the query window, enter the following statements:
      USE AdventureWorks2008R2;
      GO
      EXECUTE HumanResources.uspGetEmployees @FirstName = N'Diane', @LastName = N'Margheim';
      On the Query menu, click Execute.
      GO