Sunday, May 27, 2018
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Monday, May 21, 2018
HOW TO INSTALL MQTT BROKER IN WINDOWS
1 ECLIPSE MOSQUITTO
According to its website at https://mosquitto.org/ , “Eclipse Mosquitto™ is an open source (EPL/EDL licensed) message broker that implements the MQTT protocol versions 3.1 and 3.1.1. MQTT provides a lightweight method of carrying out messaging using a publish/subscribe model.” On the following, we will discuss about how to install and test Mosquitto on Windows, Raspberry Pi and Linux System.1.1 ECLIPSE MOSQUITTO ON WINDOWS
The following steps describe how to install and run Mosquitto on Windows:
1. Download Mosquitto broker for Windows from http://www.eclipse.org/downloads/download.php?file=/mosquitto/binary/win32/mosquitto-1.4.10-install-win32.exe
2. Install Mosquitto on Windows by following the steps specified in https://sivatechworld.wordpress.com/2015/06/11/step-by-step-installing-and-configuring-mosquitto-with-windows-7/
3. To start the Mosquitto service, open up Windows command line by clicking “Start” on the Taskbar, typing in “cmd” and pressing Enter. Navigate to where you installed Mosquitto. By default it will be located in “C:\Program Files (x86)\mosquitto” as shown on the picture below.
TUTORIAL ON MOSQUITTO AND PAHO
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4. You can test your broker with the following commands on two new terminals:
Use `mosquitto_sub` to subscribe to a topic on terminal 1:
mosquitto_sub -t 'test/topic' -v
And to publish a message on terminal 2:
mosquitto_pub -t 'test/topic' -m “hello world”
REFERENCED FROM :http://www.steves-internet-guide.com/install-mosquitto-broker/
https://mosquitto.org/
Working of Refrigerator & Refrigeration Principle
Working of Refrigerator & Refrigeration Principle
The basic principle
The basic principle of refrigeration is simple. You simply pass a colder liquid continuously around the object that is to be cooled. This will take heat from the object. In the example shown, a cold liquid is passed over an apple, which is to be cooled. Due to the temperature difference, the apple loses heat to the refrigerant liquid. The refrigerant in turn is heated due to heat absorption from the apple.
It is clear that, if we can produce cold liquid refrigerant continuously, we can achieve continuous refrigeration. This simple fact forms the core of the refrigeration technology. We will next see how this is achieved.
Components of Refrigerator
1.Throttling Device
obstruct the flow of liquid. cold liquid is provided by this . throttling device is a capillary tube. It has approximate length of 2 m for effective throttling at the inlet. The refrigerant should be a high pressure. the boiling point of refrigerant is lowered and it starts to evaporate. It is wrong to say that the throttling is a process. We know only the endpoints of throttling2.Evaporator - Heat Absorption Process
This phase is simple. This cold liquid is passed over the body that has to be cooled. As a result, the refrigerant absorbs the heat.the refrigerant further evaporates and transforms in to pure vapour. A proper heat exchange is required.
3.Compressor
The compressor will raise the pressure back to its initial level. But since it is compressing gas along with pressure, temperature will also be increased. This is unavoidable.
4.Condenser
This part is fitted outside the refrigerator and the refrigerant temperature is higher than atmospheric temperature. so heat will dissipate to the surroundings. The vapor will be condensed to liquid
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