What is Engineering???

Engineering is the discipline, art and profession of acquiring and applying technical, scientific and mathematical knowledge to design and implement materials, structures, machines, devices, systems, and processes that safely realize a desired objective or inventions.

The American Engineers' Council for Professional Development (ECPD, the predecessor of ABET) has defined engineering as follows:

“The creative application of scientific principles to design or develop structures, machines, apparatus, or manufacturing processes, or works utilizing them singly or in combination; or to construct or operate the same with full cognizance of their design; or to forecast their behavior under specific operating conditions; all as respects an intended function, economics of operation and safety to life and property.”

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Configuring Failover and Load Balancing with HAproxy using Keepalived

Network Scenario: LB1: 192.168.10.10 LB2: 192.168.10.11 Virtual IP: 192.168.10.12 APP_Server1: 192.168.10.20 APP_Server2: 192.168.10.21 Load Balancing: STEP 1 - Install HAProxy: HAProxy package is available under default yum repository for CentOS, Redhat systems. Use the following yum package manager command to install HAProxy on your system. # yum install haproxy STEP 2 - Configure HAProxy : Update your HAProxy configuration file /etc/haproxy/haproxy.cfg as per your requirement, You may also use below given configuration file as an example of setup and modify it. Keep the config file same of both servers i.e. LB1 and LB2. ----------------------------------------------------------------------------------------------------------- global log /dev/log local0 log /dev/log local1 notice ...

HAProxy automatic failover

HAProxy automatic failover HAProxy is a TCP load balancing tool with some useful features, including ACLs and SSL termination support. I’ve been using it for a while now on a number of load-balanced sites where scalability is key. What I haven’t yet looked at, however, is automated failover capabilities. My aims were simple: If a server fails, stop using it. If said server starts working again (i.e. because the problem is fixed) start using it again. If all servers in the load balancer pool fail, serve a temporary static page from another location. But first: Some basic HAProxy concepts HAProxy as a load balancer is fairly simple, and works on the basis of defined frontends and backends. A frontend is simply an IP and port declaration that you want the load balancer to listen on. A backend is the set of servers that requests to a frontend are sent to. Your HAProxy configuration lists the frontends and their respective backends, as well as the load balancing algorithm ...

Line Following Robot!

What is a line follower? Line follower is a machine that can follow a path. The path can be visible like a black line on a white surface (or vice-versa) or it can be invisible like a magnetic field. Why build a line follower? Sensing a line and maneuvering the robot to stay on course, while constantly correcting wrong moves using feedback mechanism forms a simple yet effective closed loop system. As a programmer you get an opportunity to ‘teach’ the robot how to follow the line thus giving it a human-like property of responding to stimuli. Practical applications of a line follower : Automated cars running on roads with embedded magnets; guidance system for industrial robots moving on shop floor etc. I started with building a parallel port based robot which could be controlled manually by a keyboard. On the robot side was an arrangement of relays connected to parallel port pins via opto-couplers. The next version was a true computer controlled line foll...

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