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Aims and Scope
Editorial Board

1. Influence of intermittent minimal mixing intensity on high-solids anaerobic digestion energy efficiency of dairy manure in a pilot-scale stirred tank digester

Ibrahim Denka Kariyama¹, Weixiang Li², Shaoqi Yu², Long Chen², Rui Qi², Hao Zhang², Xiaxia Li², Xin Deng³, Jian Lin⁴, and Binxin Wu²

¹Faculty of Engineering, Department of Agricultural Engineering, Dr. Hilla Limann Technical University, Wa, Ghana.

²College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310058, China.

³Department of Intelligent Science and Technology，Jiangxi Tellhow Animation Vocational College，Nanchang 330200, China.

⁴College of Mechanical and Electrical Engineering, Fujian Agriculture and Forestry University, Fuzhou 350100, China.

Abstract: The influence of intermittent minimal mixing intensity on high-solids anaerobic digestion energy efficiency of dairy manure was investigated in a pilot-scale anaerobic stirred tank digester operated under mesophilic temperature conditions. A non-mixed experiment was also investigated. Three mixing intensities were investigated; 50, 100 and 150 rpm mixed only once during feeding for a constant mixing time of 5 minutes. The volatile solids concentration ranged from 105.74 to 135 kg m^-3, with an organic loading rate varying from 3.5 to 4.5 kg VS m^-3 d^-1 for a 30-day hydraulic retention time. The results of the methane yield and specific methane production rate show that the 100 rpm performed better than the 50 rpm which also performed better than the 150 rpm mixing intensity. This research confirms that there exists a mixing intensity threshold for every anaerobic digestion setup and above which increasing the mixing intensity is a waste of energy and does not increase methane production but rather may reduce it. The results of the net energy production in kilowatt hours confirms that the 100 rpm is the economical speed, followed by 50 and 150 rpm. A high mixing intensity is not beneficial to increase methane production but rather waste energy used for mixing and should be avoided. Mixing intensity within the ranges of 50 to 100 rpm is therefore ideal for optimum methane production. Using the net energy production is the best criteria in determining the mixing mode, mixing intensity, mixing time and mixing interval for every anaerobic digestion operating plan.

Volume 13, issue 2, 2022, pp.53-64.

2. Analytical investigation for crack effect on unstable pipe conveying fluid

Mohammed Maan Kirmasha, Muhannad Al-Waily

Department of Mechanical Engineering, Faculty of Engineering, University of Kufa, Iraq.

Abstract: Pipe applications are important and widely used applications in all industrial fields because pipes are used in many fields such as water, oil, gas, etc. It was therefore necessary to highlight the study of the pipes and the problems faced by them. In this study, the problem of controlling the vibration produced by the flow of fluids within the pipes was discussed. The research included studying the amount of stability of the pipes, in addition to, the effect of crack was investigated on the level of stability Confidentiality and vibration of the pipes in various regions and dimension the crack and depth of the crack. The results of this study were obtained by deriving the differential equations of the pipes with crack and without crack and for the different types of fixation (simply supported, cantilever, and fixed from one edge and spring and damper from other edge). Through the derivation of the differential equations of the movement and dealing with them for the purpose of reaching the general equation so as to facilitate conversion within the state space and analysis of equations. The final equations are programmed and the results are found for the pipes. Vibration control is performed by increasing the pressures through the differential pressure connect to the system. To conclude of the results show that the addition of damping vibration increase in the stability of the pipes during the flow. In addition, the adoption of the frequency (imaginary), which indicates the stability of the pipes where the occurrence of the lead leads to a decrease in frequency and this, leads to increased instability of the pipes with crack. It appears that the increasing stability by adding damping vibrations to the pipe network.

3. The effect of different surface roughness on the Ti6Al4V alloy surface implant by ceramic composite materials coated

Dunya Abdulsahib Hamdi

Prosthetics and Orthotics Engineering Department, Al-Nahrain University, Baghdad, Iraq.

Abstract: In this research was study the effect of roughness types on the surface of substrate implants. The Ti6Al4V alloy was prepare by Dip coating method with solution include (HAp (a hydroxyapatite has 2 um particle size with purity is 5N (99.999%)), TiO2 (a Titania pure rutile phase has 2um particle size with purity is 4N (99.99%)) and polymer PVB)) after mechanical and chemical treatments with heat treatment at 500ᵒC. In order to increasing biocompatibility surface alloy. Atomic Force microscopy measure the value roughness of surface alloy Ti6Al4V (43.8 nm for mechanical and (23.4nm) chemical treatments. The microstructure of samples   were identify by using   Scanning Electron Microscopic SEM and Optical microscope OP analysis. The efficiency biocompatibility of the coated surface were seen  with biomimetic tests  In vitro studies were carried out in simulated body fluid with  HP 7.4. OP and SEM shows presence the elements of coated layer Hap (which appearance of many forms such as dendritic, lumbar and sheets shapes) and TiO2. The intensity result of EDS shows the concentration of Ca, P and Ti or mechanical treatments is more than in chemical treatments. Also initial TiO2 and especially HAp surface on the sample was found to have suitable an inter grain to growth the apatite in a solution SBF.  The increasing in the concentrations of Ca and P after immersion in SBF  was show EDS Also the components of SBF  appearing in other peaks (C,O,Na,K,Cl and Mg) that is mean the surfaces is biocompatibility and this confirm by Optical microscopy, according to the result the coating will be compatible with human tissue. The value of V Hardness samples was (120, 90, 83) Kg/mm for Ti6Al4V alloy (uncoated, Coating (chemical treatment) and Coating   (mechanical treatment)) respectively, shows are decreasing and more approached to the human bone value compared with uncoated of Ti alloy.

4. Design and analysis of new compound journal bearing

Nadhim N. Nadhim, Mahmud. R. Ismail

Al-Nahrain University, College of Engineering, Prosthetics and Orthotics Engineering Department, Iraq.

Abstract: Journal bearing is one of the most important mechanical parts which can vastly be found in any application of mechanical camcorders such as engine, roterdynamic, aerodynamic and many more. One of the main performance related problems that this mechanical part may encounter during its service life is due to friction and wear over a short period of time, especially at high speeds, a one of the main challenges was to keep the shaft running efficiently for another hours. Many designs and modifications are attempted by researchers to improve certain specifications of the journal. In this construction a new design of the magazine bearing system was developed. It consists of three floors; the second is the bearing (internal and external) and the third is the thrust bearing. All three bearing units are combined into a single case as a magazine assembly. In this configuration, two hydrodynamic pressure profiles can be generated around the inner and outer fluid films in the circumferential direction and one in the axial direction. To predict the journal parameters, a mathematical model for the new magazine bearing design was developed using Reynolds' hydrodynamic equations. Lubrication in two dimensions. The governing partial differential equation was solved using Finite Difference method via MATLAB software. The main bearing parameters such as pressure, load capacity, friction force and so on are evaluated and their effect on journal geometry and operating conditions are investigated. A sample journal model was fabricated using CNC machine and tested experimentally with specially made testing rig, Vibration characteristics and stability of the journal are analyzed and studied also. The stress analysis of the journal housing are performed by using Finite Element method and excited by ANSYS 14. The effect of using Nano additive to the lubricant oil is studied both theoretically and experimentally. The preliminary results of this work indicated that the new suggested journal can significantly increase the ability of withstanding higher pressure and carrying load by about 23.60% and 12.90% respectively more than the traditional journal. Furthermore it exhibits less friction and higher critical operating speed. Using oil with Nano-particles can reduce friction by 16% with higher temperature operation. The optimum design conditions are occurred at 0.92 eccentricity ratio and 0.5 compound size ratio.