Faculty of Engineering

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A cloud-based Bi-directional LSTM approach to grid-connected solar PV energy forecasting for multi-energy systems
(Science Direct, 2023-12) Liu, Q., Darteh, O. F., Bilal, M., Huang, X., Attique, M., Liu, X., & Acakpovi, A.
The drive for smarter, greener, and more livable cities has led to research towards more effective solar energy forecasting techniques and their integration into traditional power systems. However, the availability of real-time data, data storage, and monitoring has become challenging. This research investigates a method based on Bi-directional LSTM (BDLSTM) neural network. BDLSTM takes into account the data’s past and future context. The future hidden layer takes input in ascending order while the past hidden layer evaluates the input in decreasing order, making BDLSTM relevant in analyzing the input data’s past context and evaluating future predictions. The eleven-year (2010–2020) weather dataset used for this paper was acquired from NASA. Two pre-processing approaches, Automatic Time Series Decomposition (ATSD) and Pearson correlation, were used to remove the noisy values from the residual components and for feature selection, respectively. To ensure storage and reuse of data, the architecture includes a cloud-based server for data management and reuse for future predictions. Popular in multi-energy systems, the cloud-based server also serves as a platform for monitoring predicted solar energy data. The metrics values and results obtained have demonstrated that the BDLSTM performs efficiently on the available data. Data from two separate climatic horizons proved the study’s quality and reliability.
Advances in nondestructive methods for meat quality and safety monitoring.
(Materials Science and Engineering:, 2019) Kutsanedzie, F. Y.; Guo, Z.; Chen, Q.
Meat is highly perishable and poses health threats when its quality and safety is unmonitored. Chemical methods of quality and safety determination are expensive, time-consuming and lack real-time monitoring applicability. Nondestructive techniques have been reported as antidotes to these constraints. This paper assessed the potential of nondestructive techniques such as near-infrared spectroscopy, hyperspectral imaging, multispectral imaging, e-nose, and their data fusion, all combined with algorithms for quality monitoring of pork, beef, and chicken, the most consumed meat sources in the world. These techniques combined with data processing applications may offer a panacea for realtime industrial meat quality and safety monitoring.
Analysis of electrochemical machining-textured surfaces under point contacts in rolling tribo-test.
(Springer, Cham., 2021) Gyimah, G. K.; Oman, E. K.; Nyanor, P.; Acakpovi, A.; Jiang, S.; Guo, Z.; Barber, G. C.
Purpose: The need for the right textured surface and selecting the right material in tribology is critical to friction reduction and energy savings in machine elements under full film lubrication rolling point contacts. This study provides a guide to proper material selection and the right surface texturing technique to enable machine elements to carry heavy loads at different speeds under the fully-flooded EHL regime. Design/Methodology/Approach: A lapped GCr15 ball bearing, cast iron (HT 500) plates, GCr15 tempered plates and GCr15 plates without tempering were used. The electrochemical machining (ECM) technique was used to manufacture Micro-texture surfaces on the plates. The ECM micro-textured surfaces and lapped plain surfaces of the same material were subjected to friction and wear behaviour between a ball and a plate test in a fully-flooded EHL point contact rolling condition. The tribological test was conducted under different rolling speeds and pressure. The topographical characteristics of the lapped plain surfaces and the Electrochemical Machining (ECM) textures surfaces were analysed by both optical and scanning electron microscopy. Findings: The outcome of the study showed that the geometry characteristics (micro-textured and lapped untextured) and the densities of the micro-texture impact was critical to the film formation in the tribological behaviour test against the lapped GCr 15 steel bearing balls. Significantly, low friction and wear were observed for the micro-textured surfaces as compared to the lapped untextured surfaces. Research Limitation/Implications: The research was on rolling point contact in fully-flooded EHL tribo-test using lapped untextured and micro-textured surfaces in contact with ball bearing. The study did not consider line contact and sliding force. The rolling point contact is the predominant phenomenon in gears, cams, tractions and balls in energy transmission. Practical Implication: The outcome of this research increase the knowledge base of this area, it informs technologies and tribologies to select and design machine elements with energy-saving criteria in mind. In addition, this work has opened other opportunities for research to harness the full potentials of the micro-texturing. Social Implication: This paper also guides to industrial and manufacturing sectors using machine elements as moving systems to generate and transmit energy in adopting energy-saving systems and policies that is based on the outcome of such studies. Originality/Value: The innovation of this research is centered on the tribological performance of GCr15 undergoing Micro-texturing by Electrochemical Machining which demonstrates better film thickness formation within EHL regime over HT 500 counterpart material. This outcome is a good starting point for further research and development.
An analytical model of diesel injector’s needle valve eccentric motion.
(International Journal of Engine Research, 2022) Wang, C.; Adams, M.; Jin, T.; Sun, Y.; Röll, A.; Luo, F.; Gavaises, M.
Past experimental studies have shown that the needle valve of high-pressure diesel injectors undergoes lateral movement and deformation, while the continuous increase in injection pressure enlarges the gap of the needle valve assembly. Two different analytical models, considering or omitting this change are presented here, linking the geometries of the needle valve assembly with the magnitude of needle valve tip lateral movement. It is found that the physical dimensions of the needle valve assembly and the injection pressure have a significant impact on the radial displacement of the needle. For example, for nominal clearances between the needle guidance and the needle valve of about 1–3 μm, the magnitude of the radial movement of the needle tip could reach tens of microns. The model that takes into account the variation of the gap between the needle guide and needle valve is found to give predictions closer to the experimental results.
Application of powder metallurgy methods for production of a novel Cu-based composite frictional train brake material.
(Powder metallurgy-fundamentals and case studies, 2017) Gyimah, G. K.; Guo, Z.; Huang, P.; Chen, D.
A novel Cu-based composite frictional train brake material composed of several elements such as Al, SiO2, Fe, graphite, Sn, Mn and SiO2 re-enforced with other elements was treated under Powder Metallurgy (P/M) route. The materials were sintered at three different temperatures (850°C, 900°C and 950°C) at a constant pressure.
Assessing the Performance of Liquid Waste Disposal Systems in West Africa: A Case Study in Ghana and Nigeria
(MDPI, 2022-09-28) Omani, J., & Acakpovi, A
This research is an assessment of existing liquid waste disposal systems in West Africa and their performances over the years, using systems in Ghana and Nigeria as a case study. The main purpose of the study was to improve upon the sustainability of the systems, which according to earlier research activities, have been failing and resulting in health hazards. Ghana and Nigeria were selected because, from occurrences, especially in the West African sub-region, the two countries dictate the pace in contributions to the body of knowledge. Many portable liquid waste disposal systems were identified as part of the research process, as earlier researchers called for a paradigm shift from the practice of Europeanized systems that had not been successful in the entire sub-region. Many reasons have been attributed to the failures, and more worryingly, the systems continue to be operational despite their states of malfunctioning. Frequent power cuts and ineffective revenue generation contribute to numerous problems. West Africans have been enduring these occurrences for a long time with no solution in place. In a few instances, raw sewage is piped into a central biogas system for the future generation of electrical power; this system was found to be right on point because it was determined from the initial stages of development that by-products could be used to mitigate the high costs of maintenance. Another system that combines a biofil digester with its treated wastewater being channeled into a saturation pond was found to be a success because the outflow from the biofil was not meant to be channeled into main drains, as it did not wholly meet EPA approvals. The centralized sewage treatment systems have been functioning well in advanced countries; however, they are found to be ineffective in developing countries. The reasons included lack of availability for spare parts and coagulants, etc., which were normally imported. Additionally, when a larger community is targeted, revenue generation becomes a problem, thereby affecting return on investments (ROI) and operating and maintenance (O&M). None of the available central sewerage systems harvest by-products, making revenue generation a difficult task. The portable systems have been discussed in this research study, with examples and a record of performance over the years that could contribute to the body of knowledge in the field of sustainability for sewage treatment processes suitable for West Africa and for the whole of sub-Saharan Africa.
Assessing the Performance of Liquid Waste Disposal Systems in West Africa: A Case Study in Ghana and Nigeria.
(Engineering Proceedings, 2022) Omani, J.; Acakpovi, A.
This research is an assessment of existing liquid waste disposal systems in West Africa and their performances over the years, using systems in Ghana and Nigeria as a case study. The main purpose of the study was to improve upon the sustainability of the systems, which according to earlier research activities, have been failing and resulting in health hazards. Ghana and Nigeria were selected because, from occurrences, especially in the West African sub-region, the two countries dictate the pace in contributions to the body of knowledge. Many portable liquid waste disposal systems were identified as part of the research process, as earlier researchers called for a paradigm shift from the practice of Europeanized systems that had not been successful in the entire sub-region. Many reasons have been attributed to the failures, and more worryingly, the systems continue to be operational despite their states of malfunctioning. Frequent power cuts and ineffective revenue generation contribute to numerous problems. West Africans have been enduring these occurrences for a long time with no solution in place. In a few instances, raw sewage is piped into a central biogas system for the future generation of electrical power; this system was found to be right on point because it was determined from the initial stages of development that by-products could be used to mitigate the high costs of maintenance. Another system that combines a biofil digester with its treated wastewater being channeled into a saturation pond was found to be a success because the outflow from the biofil was not meant to be channeled into main drains, as it did not wholly meet EPA approvals. The centralized sewage treatment systems have been functioning well in advanced countries; however, they are found to be ineffective in developing countries. The reasons included lack of availability for spare parts and coagulants, etc., which were normally imported. Additionally, when a larger community is targeted, revenue generation becomes a problem, thereby affecting return on investments (ROI) and operating and maintenance (O&M). None of the available central sewerage systems harvest by-products, making revenue generation a difficult task. The portable systems have been discussed in this research study, with examples and a record of performance over the years that could contribute to the body of knowledge in the field of sustainability for sewage treatment processes suitable for West Africa and for the whole of sub-Saharan Africa.
Assessment of Hydro-climatic Trends and Variability over the Black Volta Basin in Ghana
(Springer Science and Business Media Deutschland GmbH, 2020) Abungba, J. A.; Khare, D.; Pingale, S. M.; Adjei, K. A.; Gyamfi, C.; Odai, S. N.
The present study examines the trends of hydro-climatic parameters over the Black Volta Basin in Ghana. Trend analysis was carried at different time scales (i.e., monthly, seasonal, and annual) from 1961 to 2016. Modified Mann–Kendall (MMK) test, Sen’s slope estimates, and Pettit–Mann–Whitney test were applied to compute the existence of a trend, the degree of change, and probable change point, respectively. The results revealed that there are warming trends over the entire Black Volta Basin. Both temperature extremes, i.e., highest and lowest (annual, seasonal, and monthly scale), for upstream and downstream region revealed an increasing trend. The annual rainfall in the upstream region depicted a downward trend, while downstream showed an increasing trend in the Basin. The seasonal trend analysis for rainfall depicted a falling trend (@ Sen’s slopes − 0.47 and − 0.69) with a percentage change over the 56 years − 19.66% and − 19.30%, respectively, for upstream and downstream regions during the dry periods. While, the rainy season showed a decreasing rainfall trend (@ Sen’s slope − 0.71 and percentage change − 4.41%) for the upstream region and increasing (@ + 0.71 & 4.39%) for the downstream. However, annual rainfall for the sites in the Basin depicted a decreasing trend (@ − 0.88 and − 4.76%) for upstream and an increasing trend (@ + 0.16 with 0.81% change) for downstream region. Annual streamflow revealed an increasing trend (@ + 0.02 with a 1.53% change) over the 43 years for upstream and a decreasing trend (@—0.41 and − 15.04% change) for downstream region at Chache-Bole. Therefore, this study output will be helpful for different stakeholders and policymakers within the Black Volta Basin of the West African sub-region toward improving decisions on water resources management.
Assessment of the quality of the Densu river using multicriterial analysis and water quality index.
(Applied Water Science, 2021) Ofosu, S. A.; Adjei, K. A.; Odai, S. N.
The natural resources, especially water in the Densu river basin, play signifcant roles in the socio-economic development of Ghana. The purpose of this study was to analyse the water quality of the Densu river using water quality index (WQI) and multivariate techniques. In this study, physico-chemical and bacteriological parameters were measured from surface water samples taken from eight (8) sampling stations in the study area. water quality index and multivariate techniques such as hierarchical cluster analysis and principal component analysis were utilized in the analysis of surface water quality data. The results indicated that the average WQI of the Densu river for the two sampling periods was sixty-one (61) which is classifed as Medium, based on the Solway WQI index. The pH levels of all the samples were within allowable limits of World Health Organization (WHO) guidelines. All the sampling stations for the two seasonal periods had bacteriological parameters higher than WHO guidelines, making the samples unsuitable for most domestic uses. The study revealed that six (6) principal components accounted for about 97% of the total variance of dataset and three (3) spatial clusters were classifed. This research has provided the basis for applying both WQI and multivariate techniques in analysing and classifying water quality in a river basin.
Barriers and prospects of smart grid adoption in Ghana
(Elsevier B.V., 2019) Acakpovi, A.; Abubakar, R.; Asabere, N. Y.; Majeed, I. B.
Distributed generation presents the potential solution to the power deficit problem faced in developing counties by encouraging local generation with renewable energy resources that are abundantly available in some part of the world, especially in Ghana. Distributed generations on the other hand are closely linked to Smart Grid (SG) that uses information technology to manage electricity networks. A plethora of problems relating to safety, reliability and affordability of Smart grid solutions remains challenging today. In Africa, especially in Ghana, the adoption of smart grid has been very slow, poorly managed, and almost inexistent in some countries despite the crucial need for electricity provision. This slow adoption can be attributed to many limiting factors that demand a thorough investigation. This paper aims at investigating the barriers to the adoption of smart grids in Africa and also develops and evaluates countermeasures to hasten the adoption process. A stratified sampling approach was used to collect comprehensive data in Ghana that were handled with SmartPLS software. The evaluation of factors was done through inferential statistics. The impact of the proposed measures was tested using a partial least structural equation model analysis. Findings revealed some factors that strongly influence the adoption of SG including cost, education, government policies; other factors like culture, Grid stability, had slight influence on the adoption process, nevertheless, societal perception had a low impact on the adoption process and therefore attracts less attention in fostering the SG acceptance in Ghana. Regarding SG prospects, the study identified several factors that can foster the prospect of smart grid adoption in Ghana namely education on smart grid technology, government policies and consumers behaviour. It is believed that, if careful attention is given to the factors listed above, the adoption of SG in Ghana will move at a faster speed.
Big data challenges in transportation: A case study of traffic volume count from massive radio frequency identification (RFID) data.
(2017) Wemegah, T. D.; Zhu, S.
We are in an advancing stage of data acquisition and an even greater dynamic stage of dealing with big data. Data sizes have evolved over the years from a few kilobytes to Exabyte. The transportation engineer has also been caught up in the big data era and to efficiently analyze this massive data for maximum benefits, various challenges relating to data acquisition, data storage, data cleaning, data analysis and visualization has to be overcome. In this paper, we discuss these challenges and approaches to managing them with respect to massive Radio Frequency Identification data for traffic volume count in Nanjing, China. We recommended software, use analytical and visualization techniques like aggregation, graduated circular symbols and traffic count map to overcome big data challenges to produce peak hour, offpeak hour traffic volume counts and traffic count maps showing locations of low and high volume traffic. The paper, therefore, contributes to the management of big data by transportation engineers for traffic volume and congestion analysis.
Biotite influence on the binding properties of bituminous materials.
(International Journal of Engineering Research & Technology (IJERT), 2017) Aforla, B.; Woode, A.; Amoah, D. K.; AY, B. S.
The effect of biotite on rheological properties of bitumen was investigated using biotite extracted from gneiss rocks. The research methodology involves two phases. The first phase involves the separation of biotite from gneiss rock. The second phase involved tests carried out on bitumen- biotite blend to determine the effect of biotite on the rheological properties of bitumen. The biotite was ground to 75Âµm size and blended with bitumen AC-10 prepared in various proportions and the rheological properties determined in the laboratory. The results of this study shows that biotite improves the binding properties of bitumen. At low temperatures, the presence of biotite in bituminous mixtures in the proportion of 2 to 3.5% by weight of bitumen improves the binding properties. Conversely, at higher temperatures of about 135oC, the biotite bitumen mix showed best result at 2%. An increase of up to 3.5% by weight of biotite resulted in a drop in the kinematic viscosity values even though there was an improvement in the binding properties over the pure AC-10 bitumen results.
Causes of delays in highway construction projects in Ghana
(Civil and Environmental Research, 2016) Aforla, B.; Woode, A.; Amoah, D. K.
Delays in construction projects are a global phenomenon, causing a multitude of negative effects on the key project participants – clients, consultants, and contractors. The main purpose of this study is to identify the causes of delay of highway construction projects in Ghana to determine the most important to the key project participants. Literature review and semi-structured interviews of 12 key players in the implementation process were conducted. Thirty five possible causes of delay were identified and further grouped into ten categories. A questionnaire survey was conducted on the resulting list of delay causes for the identification of the most important causes of delay. The relative importance of the individual causes were determined and ranked by their Relative Importance Index. The findings revealed that the five most important causes of delay in road construction projects in Ghana are 1) Delay in honouring payment certificates 2) Equipment failure 3) Shortage of materials 4) Poor site management 5) Late delivery of materials on site. It is hoped that the findings of this paper will help project participants to act on critical causes to minimize delay of their projects.
Challenges and facilitators of public engagement with water, sanitation, hygiene and other environmental health issues in Ghana and Uganda: Perspectives of scientists
(Journal of Water, Sanitation and Hygiene for Development, 2020) Appiah, B.; Poudyal, A.; Anum, D. A.; Appiah, G.; Wesuta, A. C.; Akodwaa-Boadi, K.; Odai, S. N.
Despite many water, sanitation, hygiene (WASH) and other environmental health challenges in sub-Saharan Africa, little is known about interactions involving scientists, journalists and the public to aid public understanding of the relationship between WASH and health. Using purposive sampling, we conducted key informant interviews and focus group discussions with scientists, journalists and members of the public in Ghana and Uganda to identify issues associated with the promotion of public engagement with WASH and other environmental health issues. An inductive thematic analysis was used to explore the evidence, challenges and opportunities of public engagement. The effectiveness of public engagement was constrained by poor interactions between scientists and journalists and limited understanding among the public on WASH and other environmental health issues. Challenges identified included inadequate scientists–journalists collaborations, scientists' lack of time, pressure from media organizations and concerns about journalists' inadequate capacity to communicate environmental issues due to lack of training. Possible solutions included increased interactions, science communication training and using public information officers as knowledge brokers between scientists and journalists to boost public engagement with WASH and other environmental health issues. Our study contributes to the literature on the need to actively engage the public with WASH and other environmental health concerns.
Change and Analysis of Extreme Rainfall Indices During 1960–2010 and 2011–2100 in Abidjan District (Côte d’Ivoire).
(Climate Change Research at Universities, 2017) Danumah, J. H.; Odai, S. N.; Saley, M. B.; Akpa, L. Y.; Szarzynski, J.; Kouame, F. K.
Flood risk occurrence is very often related to heavy precipitation. The availability of analysis of weather data is a potential source for long term flood risk prediction and management. The aim of this paper was to determine and analyse trends of observed and future rainfall indices from 1961 to 2010 and 2011 to 2100 using rclimdex model in Abidjan District. This work was based on the integration of daily weather data within rclimdex model throughout quality control test, homogeneity test and indices calculation of ten (10) rainfall indices. The results showed an overall decrease trend of the rainfall indices namely through a negative trend in the annual total rainfall, maximum number of consecutive wet days, and number of extremely wet days during the period from 1961 to 2010. Exception was made from 1995 to 2010 where the same indices showed a positive trend. However, the results have showed also an increase trend of consecutive wet days (CWD), Simple daily intensity index (SDII) and Number of heavy precipitation days (R10) indices from 2011 to 2100. Thus these findings explain the nowadays flood occurrence and indicate that rainfall extreme under flood risk events will continue in the future. Therefore it call decision makers for preparedness and mitigation strategies in Abidjan District.
Characterisation of fractured carbonate aquifers using ambient borehole dilution tests.
(Journal of Hydrology, 2020) Agbotui, P. Y.; West, L. J.; Bottrell, S. H.
Fractured carbonate aquifers derive their transmissivity essentially from a well-developed network of solutionally-enhanced fractures and conduits that can lead to high groundwater velocities and high vulnerability to contamination of water quality. Characterisation of the variation of hydraulic properties with depth is important for delineating source protection areas, characterising contaminant fate and transport, determination of the effectiveness of aquifer remediation, and parameter estimation for models. In this work, ambient open borehole uniform and point injection dilution tests were conducted on observation boreholes in the unconfined Cretaceous Chalk aquifer of East Yorkshire, UK, and interpreted in conjunction with other data via the implementation of a new work flow. This resulted in the characterisation of flow in these boreholes and the inference of properties such as groundwater flow patterns and velocities in the surrounding aquifer formation. Our workflow allowed sections of open boreholes showing horizontal versus vertical flow to be distinguished, and the magnitude of such flows and exchanges with the aquifer to be determined. Flow within boreholes were then used to characterise: i) presence and direction of vertical hydraulic gradients; ii) nature and depth distribution of flowing features; iii) depth interval porosity and permeability estimation of the flowing features from overall borehole transmissivity and geophysical image or caliper logs; iv) groundwater velocity estimation in the surrounding aquifer. Discrete flowing features were distributed across the range of depths sampled by the observation boreholes (typically up to 45–60 mbgl), but the majority were located in the zone of water table fluctuation marked by solutionally enlarged flow features. Quantitative interpretation of both uniform injection (tracer distributed throughout the open borehole section) and point injection (slug of tracer introduced at targeted depth) yielded vertical velocities within the borehole water column in broad agreement with those measured by flow logging. Depth specific fracture kinematic porosities inferred from the ambient dilution data combined with long-interval pump test and geophysical log data ranged between 3.7 × 10−4–4.1 × 10−3 with an average of 2.1 × 10−3; these values were in excellent agreement with those from other methods applied to the same aquifer such as larger scale pumping tests. A new approach to estimation of groundwater velocities from the dilution test data using externally measured hydraulic gradients gave inferred horizontal groundwater velocities ranging between 60 and 850 m/day, in full agreement with those from previously conducted borehole-to-borehole tracer tests. These results confirm that the studied aquifer is karstic, with rapid preferential pathways which have implication for flow and transport modelling, and pollution vulnerability. Our study results indicate that ambient single-borehole dilution approaches can provide an inexpensive and reliable approach for the characterisation of fractured and karstic aquifers.
The characteristics of pure heterogeneous reaction for H2/Air mixture in the micro-combustors with different thermophysical properties.
(Applied Thermal Engineering, 2018) Zhang, Y.; Pan, J.; Lu, Z.; Tang, A.; Zhu, Y.; Bani, S.
This paper investigated the characteristics of pure heterogeneous reaction for H2/Air mixture under different wall thermophysical conditions namely; thermal conductivity, convective heat transfer and thermal capacity. The phenomena of pure heterogeneous reaction were observed by OH Planar Laser induced Fluorescence (OH-PLIF) to determine the working conditions. (3D)-models were built to numerically study the effects of different wall thermophysical conditions. The results show that lower thermal conductivity and convective heat transfer coefficient is beneficial to enhancing heterogeneous reaction and improve conversion rate of H2 as less heat is dissipated. The greater thermal capacity has beneficial impact on the reaction stability when the boundary condition changes, but no effect under the steady state. The performance of thermal conduction and convection were comprehensively considered to study the influence and proportion of each on the heterogeneous reaction. Higher thermal resistance can improve the reaction efficiency, reaction stability and reduce application cost. The influence of thermal conduction is greater than that of convective heat transfer.
Characterization of a fractured aquifer using open-well dilution tests.
(80th European Association of Geoscientists & Engineers (EAGE) Conference and Exhibition, 2018) Agbotui, P.Y.; West, J.; Bottrell, S.
An approach to characterization of multilayer aquifer systems using open well borehole dilution is described. The approach involves measuring observation well flow velocities while a nearby extraction well is pumped by introducing a saline tracer into observation wells and collecting dilution vs. depth profiles. Inspection of tracer profile evolution allows discrete permeable layers within the aquifer to be identified. Dilution profiles for well sections between permeable layers are then converted into vertical borehole flow velocities and their evolution, using an analytic solution to the advection-dispersion equation applied to borehole flow. The dilution approach is potentially able to measure much smaller flow velocities that would be detectable using flowmeters. Vertical flow velocity data from the observation wells are then matched to those generated using a hydraulic model of the aquifer system, "shorted" by the observation wells, to yield the hydraulic properties of the constituent layers. Observation well flow monitoring of pumping tests represents a cost-effective alternative or preliminary approach to pump testing each layer of a multilayer aquifer system separately using straddle packers or screened wells and requires no prior knowledge of permeable layer depths and thicknesses. The modification described here, of using tracer dilution rather than flowmeter logging to obtain well flow velocities, allows the approach to be extended to greater well separations, thus characterizing a larger volume of the aquifer. An example of the application of this approach to a multilayer Chalk Aquifer in Yorkshire, Northeast England, is presented.
Characterization of Al-5Ni-0.5 Mg/x (Al2O3-GNs) nanocomposites manufactured via hot pressing technique.
(Materials Characterization, 2022) Yehia, H. M.; Nyanor, P.; Daoush, W. M.
Exfoliating graphite to graphene nanosheets by mechanical ball milling with alumina, coating alumina particles with graphene layers to enhance their electrical and thermal properties, minimizing aluminum composite's production time, and improving the adhesion between the matrix and reinforcement were the aims of this study. Ball milling (BM) followed by electroless silver coating was used to prepare the (Al2O3-GNs) hybrid nanoparticles. A matrix sample from Al, 5 wt% Ni, and 0.5 wt% Mg was reinforced with different ratios of (Al2O3-GNs)/Ag nanoparticles up to 7.5 wt%. The cold and hot compaction technique was used to prepare the study samples. 550 °C and 50 min were the suitable parameters for fabricating the aluminum matrix composite. Microstructure investigation has been followed by chemical analysis, hardness, compressive strength, and electrical conductivity measurements. New intermetallic phases Al50Mg48Ni2, AlNi, and AlMg, have been formed during the powder consolidation by the hot-pressing process. The density of the Al-5Ni-0.5Mg (3.005 g/cm3) matrix was not significantly affected by the Al2O3/GN (3.907 g/cm3) reinforcement density. The 7.5 wt% Al2O3-GN reinforced composite exhibits the highest hardness. The electrical conductivity and the composites' compressive strength are also increased by 133% and 78%, respectively, for the 7.5 wt% sample.
Combined effect of injection timing and injection angle on mixture formation and combustion process in a direct injection (DI) natural gas rotary engine
(Energy, 2017) Fan, B.; Pan, J.; Yang, W.; Pan, Z.; Bani, S.; Chen, W.; He, R.
The application of direct injection (DI) technology is considered as a key solution to the problems of combustion efficiency and emissions on the rotary engine. This work aimed to numerically study the combined effect of injection timing (IT) and injection angle (IA) on mixture formation and combustion process in the 3D flow field of a DI natural gas rotary engine. On the basis of the 3D dynamic simulation model which was established in our previous work [29, 30], some critical information was obtained which was difficult to acquire through experiment. Simulation results showed that to satisfy the ideal fuel distribution for high combustion rate, a small IA should be used when the IT was at the early stages of intake stroke, and a big IA should be used when the IT was at the early stages of compression stroke. However, when the IT was at the middle and later stages of intake stroke, the IA which could satisfy the ideal fuel distribution, was difficult to determine with the changed IT in the middle and later stage of intake stroke. For the above reason, the middle and late stage of intake stroke was not recommended as injection timing in engineering application.

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