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Blockchain has emerged as a new light in the digital world. Though this technology is one of the newest inventions, it has widened the doors of security and transparency in the technology-based world. Stakeholder’s feedback brings out more opportunities in an organization. But it is not easy to find honest feedback since people may feel hesitation to give an honest review for many reasons like safety, bias, nepotism, etc. Today mostly a database system is used to store the data of feedback, but lack of trust in the database system leads to false feedback or partially compromised feedback. In this paper, a digital feedback system will be used where feedback will be ensured with the anonymity of the users. This system will make sure the trust of users is being stalled when feedback is given. Furthermore, it will give an idea of how the people of an organization think about certain topics. This system can be a game-changer in the corporate world as well.

Harnessing wind energy across all over the globe increasing due to raw energy availability and uses of a higher grade of optimized technology. Mostly European countries are adopted this energy expansion over other regions because of the huge availability of wind in these areas. The potential of wind energy in Bangladesh is not tremendously good but has some good prospect if modern technology and greater optimization can take place. Presently the coastal regions, as well as Cox's Bazar, Chittagong, Teknaf, Patenga, Mongla, and Kutubdia, are a most suitable point to harnessing or working on wind energy. Although the velocity of wind in these regions is not perfect for harnessing energy from a big size wind turbine rather it is quite capable to generate electricity from small size turbine in an efficient way. Vertical axis wind turbine (VAWT) is perfectly appropriate for extracting the maximum power from wind in such these low wind speed area. NACA foil is mainly prioritized to build this type small sized VAWT system because of the low maintained mechanism. The small-sized VAWT system needs more analyzed wind data to work in an optimized condition. The positions and efficiency of the turbine system are highly depend on the blade lift and drag coefficient because of random wind flow directions. Counting all these points the main objective is to examine the wind data available in these areas and design a vertical axis wind turbine (VAWT) suitable for small sized electricity generation system in an efficient way by optimizing turbine blades and its foil mechanism.

Filtration is a very basic and primitive technique of water treatment. For many remote, under-privileged and poor communities, this is the only pre-treatment of drinking water prior to boiling. With the emergence of arsenic contaminations in many groundwater aquifers, the filtration became imperative for many communities around the world. However, after repetitive/continuous uses, clogging of the filter media is obvious, which eventually causes poor performance of the filtration process. Backwashing is a common technique being used for the recovery of the filtration capacity of clogged filter media. This study presents development of a simple clogging and backwashing efficiency model for a special filter media. “3rd generation IHE family filter” was developed by UNESCO-IHE Institute for Water Education and widely used for treating arsenic-contaminated water in many countries including Bangladesh. Several field tests were conducted in three different sites in Bangladesh having different qualities o...

Acoustic emission (AE) monitoring technique is a well-known approach in the field of NDE/SHM. AE monitoring from the defect formation and failure in the materials were well studied by the researchers. However, conventional AE monitoring techniques are predominantly based on statistical analysis. In this study we focus on understanding the AE waveforms from the fatigue crack growth using physics based approach. The growth of the fatigue crack causes the acoustic emission in the material that propagates in the structure. One of the main challenges of this approach is to develop the physics based understanding of the AE source itself. The acoustic emission happens not only from the crack growth but also from the interaction of the crack lips during fatigue loading of the materials. As the waveforms are generated from the AE event, they propagate and create local vibration modes along the crack faces. Fatigue experiments were performed to generate the fatigue cracks. Several test specimens were used in the fatigue experiments and corresponding AE waveforms were captured. The AE waveforms were analyzed and distinguished into different groups based on the similar nature on both time domain and frequency domain. The experimental results are explained based on the physical observation of the specimen.

In this paper, the design and analysis of a modified outer rotor PMA has been presented, which increases the efficiency and machine capacity by minimizing the cogging torque. The modified outer rotor type PMA will be suitable for extremely low-speed wind turbine based power generation system. The performances of the machine are analyzed by simulation using ANSOFT MAXWEL software, and the results are compared with the typical PMA model. All the performances are examined using finite element analysis (FEA) method to get higher accuracy in simulation stage.

The outer rotor permanent magnet alternator is unrivaled for low-speed wind turbine frameworks because of it's robust structure, low maintenance and construction cost while the inner rotor permanent magnet alternators are most economically accessible for its customary auxiliary setup. In this research, a comparative study of design and performance analysis between an inner rotor PMA and an outer rotor PMA used for low-speed and small capacity wind turbine system has been overviewed using simulation. The basic setup like materials, magnets and some electrical and mechanical parameters are concentrated on, and the performance parameters of PMAs are observed by changing these rudimentary electromechanical parameters. By considering all of these contemplations, higher productivity from the outer rotor PMA with higher efficiency has been accomplished compared to that of inner rotor PAMs for low-speed wind turbine system.

The in-runner permanent magnet alternator (PMA) is adequately utilized as a part of wind power generation system specially for its robust and conventional structural configuration. In this research, the execution investigation of an in-runner outspread flux PMA intended for direct driven, extremely low-speed and small capacity wind power system has been examined with numerous modification shave taken into account e.g. changing some mechanical parameters such as use of effective and robust material, fractional slotting per pole, improving the slot fill factor and mounting of the magnets for reduction of cogging torque. The proposed configuration has been analyzed by finite element analysis (FEA) technique keeping in mind the end goal to observe the real time performance with several loss counting and cogging torque calculation. A good slot fill factor improves the thermal condition in the slot of the stator by reducing the copper losses. Considering all the point, an in-runner radial flux permanent magnet alternator (RFPMA) has been achieved with minimum losses and higher efficiency.

Implementation of wind turbines has been expanded fundamentally on account of its accessibility and simple and easy generation techniques all around the globe. In the interim in Bangladesh wind energy conversion techniques are exceptionally late idea contrasted with other renewable energy conversion techniques but then in numerous spots research are going on to study and investigate the wind speed. Bangladesh has reasonably wind energy potential. In the present study, wind attributes and wind energy capability in the coastal regions including Chittagong, Cox's Bazar, Hatiya, Teknaf, Kutubdia, Mongla and Patenga are been investigated. The main focus of this research is to study the wind prospects of coastal regions in Bangladesh by building up a measurable examination of wind speed and available power calculation at diverse seaside areas at 15m height, analyzation of air foils and design of turbine's blades for a 250W low-speed horizontal axis wind turbine (HAWT).

Currently, the demand of memories has been increasing due to its higher speed, lower cost and lower power consumption. The complexity of instructions to control the memory devices increases with the increase in technology. DDR4 is the latest generation family of DDR SDRAM. This memory device provides higher reliability, availability and serviceability than other DDR memories. In this paper, the overall architecture of the DDR4 SDRAM controller is proposed. The detailed design and operation of its individual sub blocks is described. Also the advantages of DDR4 over DDR3 SDRAM are discussed.