Background and Objectives: Blockchain technology as a Distributed and tamper-proof data ledger is attracting more and more attention from various fields around the world. Due to the continuously growing of the blockchain in both transaction data and the number of nodes joining the network, Scalability emerges as a challenging issue. Methods: In this survey, the existing Scalability solutions in the blockchain are discussed under five categories including on-chain Scalability, off-chain Scalability, scalable consensus mechanisms, DAG-based Scalability, and horizontal Scalability through sharding. Meanwhile, the novelties they have created on the fundamental layers of the blockchain architecture are investigated.Results: As a result, the advantages and disadvantages of the discussed mechanisms are pointed out, and a comparison between them in terms of different Scalability metrics such as throughput, latency, bandwidth, and storage usage is presented. Therefore, this study provides a comprehensive understanding of the various aspects of blockchain Scalability and the available Scalability solutions. Finally, the research directions and open issues in each category are argued to motivate further improvement efforts for blockchain Scalability in the future.Conclusion: Scalability allows blockchain system to sustain its performance as it grows up. Lack of Scalability has a negative effect on the mass adoption of the blockchain in practical environments. This paper presents a profound analysis of the existing Scalability solutions, the issues and challenges they address, and the ones that are not resolved yet. Consequently, it inspires novel ideas for more scalable and efficient blockchains in the future.

A single Server finite population queueing model with compulsory Server vacation and with fixed batch service has been considered. For this model the system steady state probabilities are obtained. Some performance measures are calculated and numerical examples are also given.

In this paper, the designing of a parallel channel queuing system is considered in which it is desirable to serve the customers immediately upon their arrival. To design such a service facility, the first and the second moments of the number of customers are obtained in an infinite channel Server under the assumption that the arrival process has a general probability structure and the service times of customers are independent and identically Distributed random variables. With the knowledge about the above two moments, one can obtain the approximate number of channels such that the queue length becomes zero.    

Since their invention, microwaves have found significant use in different fields, including medicines and food processing, as well as sterilization of microorganisms for use in biomedical treatment and research. Various scientific studies have demonstrated microwave application’, s capability as clean technology and a veritable solution for producing a pure and desirable drug candidate in bionutraceuticals processing....