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A Multi-Indexes Based Technique for Resolving Collision in a Hash Table
Yusuf, Ahmed Dalhatu,Abdullahi, Saleh,Boukar, Moussa Mahamat,Yusuf, Salisu Ibrahim International Journal of Computer ScienceNetwork S 2021 International journal of computer science and netw Vol.21 No.9
The rapid development of various applications in networking system, business, medical, education, and other domains that use basic data access operations such as insert, edit, delete and search makes data structure venerable and crucial in providing an efficient method for day to day operations of those numerous applications. One of the major problems of those applications is achieving constant time to search a key from a collection. A number of different methods which attempt to achieve that have been discovered by researchers over the years with different performance behaviors. This work evaluated these methods, and found out that almost all the existing methods have non-constant time for adding and searching a key. In this work, we designed a multi-indexes hashing algorithm that handles a collision in a hash table T efficiently and achieved constant time O(1) for searching and adding a key. Our method employed two-level of hashing which uses pattern extraction h<sub>1</sub>(key) and h<sub>2</sub>(key). The second hash function h<sub>2</sub>(key) is use for handling collision in T. Here, we eliminated the wasted slots in the search space T which is another problem associated with the existing methods.
Yusuf Zuntu Abdullahi,Tiem Leong Yoon,Mohd Mahadi Halim,Md. Roslan Hashim,Mohd. Zubir Mat Jafri,Lim Thong Leng 한국물리학회 2016 Current Applied Physics Vol.16 No.8
In this paper, geometric, electric and magnetic properties of graphitic heptazine with embedded Mn atom under bi-axial tensile strain are investigated using density-functional theory with the spin polarized generalized gradient approximation and Hubbard U correction. The binding energy computed for the systems are found to uniformly decrease with the increase in small bi-axial tensile strain (0e5%). The decrease of the binding energy can be related to the increase in the NeCeN bond angle within the cavity which tries to recover its sp2 hybridized bond. The projected density of states (PDOS) of strained/unstrained systems is also computed. It is found that the covalent bonding of the 6 nitrogen atoms located at the edge of the cavity and the embedded manganese atom in CN1 is mainly contributed by s, dzx and dz2 of the Mn atom, as well as the sp-like orbitals of these nitrogen atoms in the majority spin state respectively. Our calculations also predict enhanced band gap (0.67 eV at zero strain, 1.12 eV at 4% strain) induced by small amount of bi-axial tensile strain. The increase in band gap can be attributed to the structural distortions of the sheet caused by the symmetric deformations which lead to the backward shift in the s-like orbitals states of the CN1 atoms. Such properties may be desirable for diluted magnetic semiconductors, future spintronics, molecular magnet and nanoelectronics devices.
Hybrid Encryption of ElGamal-AES with Huffman Coding for Efficient Data Communication
Abdullahi Yahaya Yusuf,Farouk Lawan Gambo,Hyeju Shin,Abubakar Muhamad Miyim 한국디지털콘텐츠학회 2023 The Journal of Contents Computing Vol.5 No.2
Information security or data transmission efficiency and reliability are unanimously considered as some of the most important things that are required whenever communication between parties is to be established. Inefficient data security and improper management of voluminous data during data communication increases data transmission cost, delay in data transmission, and risk of confidentiality and privacy to the transmitted data. Thus, this paper proposes an improved cryptosystem to ensure reliability and efficiency to data in communication channel. The work adopted two cryptographic methods (ElGamal cryptosystem) for the asymmetric key distribution; Advanced Encryption Standard (AES) was suggested for message encryption. In the other hand, Huffman coding (compression algorithm) was introduced along the way to reduce the size of the data to be transmitted. The results of our proposed scheme show that the entropy ensures reliability and encryption time ensures efficiency to data in communication channel. This hybrid scheme is promising with a potential of improving data security.
Abdullahi Yakubu,Zaharaddeen Sani Gano,Omar Umar Ahmed,Suleiman Mohammed Shuwa,Abdulazeez Yusuf Atta,Baba Yakubu Jibril 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.5
Hydrophobic deep eutectic solvent (DES) was synthesized from TBAB and decanoic acid and used tostudy the extraction of aromatic hydrocarbon from contaminated water samples. DES was screened by selecting differentratios between the TBAB and decanoic acid. A ratio of 1 : 2 was observed to be the best among others and wasused for the desired application. Within the temperature range of 25-70 oC, physicochemical properties such as density(944-915 kg/m3), viscosity (1,636-179 mPa·s), conductivity (141-1,007 S/cm), and pH (3.14-2.73) of the synthesizedDES were determined. For the extraction study, benzene, toluene, and xylene (BTX)-doped water were used as a simulatedcontaminated water. Response surface methodology was employed in modeling and optimizing the effects oftemperature, time, and solvent mass fraction on the extraction efficiency of the DES. Extraction efficiency of 68.1%,70.84% and 77.73% for BTX, respectively, was recorded at optimum values of 25 oC, 60 min and 0.6 (solvent mass fraction). Extraction efficiency as high as 86.61%, 88.94%, and 92.71% for BTX, respectively, can be obtained within thedesign space. Effective regeneration and reuse of the DES after each extraction was carried out for five consecutivecycles; their results showed no significant decrease in their respective extraction efficiencies and recovery of the DES. This, therefore, improves the overall performance of hydrophobic DES for the extraction process.
Ibrahim Yusuf,U. A. Ali,Ramatu Idris Gatawa,Maimuna Abdullahi Bichi,Surajo Mahmud Umar 한국신뢰성학회 2020 International Journal of Reliability and Applicati Vol.21 No.1
The present paper deal with the reliability modelling and performance analysis of serial communication network system consisting of a transmitter, two relay stations and a receiver arranged as series parallel system. The failure and repair time of both transmitter, relay and receiver are assumed to be exponentially distributed. System of first order linear differential equations are developed and solved to obtain the explicit expressions for the steady-state availability, busy period probability of repairman due to repair of transmitter, relay or receiver, profit function and mean time to failure are derived and examined. Furthermore, the results of the proposed model are beneficial for system engineers and designers, reliability and maintenance managers.