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What is this?You have just seen a slippery oily magnetic fluid called Ferrofluid. Though the working principles and material compositions are complicated, the basics are very simple. Tiny nanoscale ferromagnetic particles are suspended in oil or water. Each particle is coated with a surfactant to inhibit clumping. A surfactant is a substance that lowers the surface tension between liquids or between liquid and a solid. Ferrofluids usually do not retain magnetization in the absence a magnet or a magnetic field.Steve Papell of NASA developed the fluid in the 1960’s in response to the need for moving fuel in space where ... Read More
A career in Linux technology has always been extremely rewarding for many and seems to be evergreen and recession proof. In case you are having an idea of pursuing a course in Linux, then you can be sure that the demand for Linux certified professionals will zoom up in the near future which is sufficient and stable.The Linux job market is very hot right now, particularly for those with system administration skills. Everybody is looking for Linux talent. Recruiters are knocking down the doors of anybody with Linux experience as the demand for Linux professionals is increasing day by day. ... Read More
The revolution of computing started in the early 2000’s. There are multiple reasons for such revolution of computing. As the population got increased, the demand for computing also got increased. As the demand increased, computers reached people much closer than before. The revolution started with large room-sized machines to hand size devices. A lot of technologies played a crucial role in this revolution. One such important technology was the Internet. Many things divided the entire globe. However, internet united the entire globe under a single roof. The role of Internet in computing is very important since computing is getting shifted ... Read More
In this article, we will learn how to change the MySQL Data Directory or relocate the MySQL Database data to the new location, this situation may be used when the database is growing very fast, or for some security reasons we want to move the data directory to the new location.PrerequisitesAn Ubuntu machine with a non-root user with Sudo permission.MySQL installed and working.A new volume or location where we want to move the database data location, the new location will be /mnt/data_vol/MySQL as the data_vol is the new volume attached to the machine or server.Changing the MySQL Data Folder LocationBefore ... Read More
Hibernate or JPA support 4 different types of primary key generator. These generators are used to generate primary key while inserting rows in the database. Below are the primary key generator −GenerationType.AUTOGenerationType. IDENTITYGenerationType.SEQUENCE GenerationType.TABLEGenerationType. IDENTITY − In identity , database is responsible to auto generate the primary key. Insert a row without specifying a value for the ID and after inserting the row, ask the database for the last generated ID. Oracle 11g does not support identity key generator. This feature is supported in Oracle 12c. GenerationType. SEQUENCE − In sequence, we first ask database for the next set of the sequence ... Read More
Collection.stream().forEach() and Collection.forEach() both are used to iterate over collection. Collection.forEach() uses the collection’s iterator. Most of the collections doesn’t allow the structurally modification while iterating over them. If any element add or remove while iteration they will immediately throw concurrent modification exception. If Collection.forEach() is iterating over the synchronized collection then they will lock the segment of the collection and hold it across all the calls. Collection.stream().forEach() is also used for iterating the collection but it first convert the collection to the stream and then iterate over the stream of the collection therefore the processing order is undefined. It also throws ... Read More
Many people love summers but most hate the heat. Therefore, air conditioners have been one of the most favourite electrical appliances in the dog days of summer. Nonetheless, air conditioners consume enough electricity and manufacturers have been fiercely fighting to diminish the electricity consumption of air conditioners.If you notice carefully, you’d find many air conditioner advertisements that focus on low electricity consumption. It is important because saving energy is not only important for environmental sustainability, but electrical appliances also need to be light on the pocket.Now, if we say air conditioners can run without electricity too, will you be impressed? ... Read More
In this article, we will learn how to change or relocate the PostgreSQL Database data directory to the new location on Ubuntu 16.04. This database grows more frequently and depends upon the size of the company, as we needed more space and for security reasons we will change the data directory to the other volume or other location.PrerequisitesAn Ubuntu machine with a non-root user with Sudo permission.A PostgreSQL server installed and working.A new volume or location where we want to move the database data location, the new location will be /mnt/data_vol/PostgreSQL as the data_vol is the new volume attached to ... Read More
In a world where big-screen devices are all the craze, how about getting a camera that comfortably fits one’s palms, and yet manages to click pictures large enough to give even the widest screens in the world a run for their money? Yes, you guessed it right! We are talking of 360-degree cameras that- as per their names- can take a 360-degree view snapshot.Ricoh Theta- $399The feature about Ricoh Theta that immediately arrests your attention has, interestingly, got to do with not the specifications but the price. Keeping in mind what this camera can do, it comes at a jaw-dropping ... Read More
In this article, we will learn how to change the Apache default web root folder to a new location. By default, the Apache web root or Document root folder location is at /var/www/html.These type of changes will be useful for security reason or having the space issue due to data size, we want to change the document root folder to another location or mount point. This will be helpful if we have multiple instances and we want to keep the data for each website into their own volumes or folders.PrerequisitesAn Ubuntu 16.04 server with a user with Sudo permissions on ... Read More