A Data Warehouse is a computer system designed for storing and analyzing an organization's historical data from day-to-day operations in Online Transaction Processing System (OLTP). Usually, an organization summarizes and copies information from its operational systems to the data warehouse on a regular schedule and management performs complex queries and analysis on the information without slowing down the operational systems. Data need to be pre-processed to improve quality of data, before storing into data warehouse. This survey paper presents data cleaning problems and the approaches in use currently for pre-processing. To determine which technique of pre-processing is best in what scenario to improve the performance of Data Warehouse is main goal of this paper. Many techniques have been analyzed for data cleansing, using certain evaluation attributes and tested on different kind of data sets. Data quality tools such as YALE, ALTERYX, and WEKA have been used for conclusive results to ready the data in data warehouse and ensure that only cleaned data populates the warehouse, thus enhancing usability of the warehouse. Results of paper can be useful in many future activities like cleansing, standardizing, correction, matching and transformation. This research can help in data auditing and pattern detection in the data.

Brain-Computer Interfacing (BCI) enables a communication pathway that is used to directly control certain object or device with the human brain. It is possible to acquire data from the brain with the help of sensors which essentially monitor the physical processes that occur in the brain and with the help of software we can direct a device accordingly. BCI introduces its users a new system that communicates in a special way without the use of muscles. BCI also provides a useful platform for the people with physical disabilities to conveniently perform certain tasks in our society. It uses brain imaging technologies which help in increasing the quality of the communication between humans and machines. There has been significant research effort in the past decade to explore different aspects of this promising field of technology. Previously, BCIs had limited functionality but due to recent advancement in technology it has attained the maturity of its own right by adding new trends and extra features to it.
In this paper, research work of development and integration of both hardware and software in BCI and the advancements of BCI are surveyed considering all the possibilities of direct communication of computers with a brain using emerging technologies. Different approaches used up till now with an overview of the methodology are presented to make the reader understand its meaning and functionality in a compact way. This research paper will guide a beginner to end up with a thorough knowledge of what’s, how’s and why’s of BCI. In addition, BCI applications, challenges, possible solutions and future directions have also been discussed.