Mechanical Engineering

Permanent URI for this community

https://repository.elizadeuniversity.edu.ng/handle/20.500.12398/10

Browse

Now showing 1 - 20 of 105

Artificial neural network prediction of exhaust emissions and flame temperature in LPG (liquefied petroleum gas) fueled low swirl burner
(Energy by Elsevier, 2013-09) Adewole, Bamiji Z.; Abidakun, Olatunde A.; Asere, Abraham A.
This study deals with ANN (artificial neural network) modeling of a swirl burner. The model was used to predict the flame temperature and pollutant emissions (CO (carbon monoxide) and NOx (nitrogen oxide)) from combustion of LPG (liquefied petroleum gas) in the swirl burner. The data for the training and testing of the proposed ANN was obtained by combusting LPG at various equivalent ratios (LPG/air ratios) and swirler’s vane angles in a low swirl burner. Vane angles of 35e60 in steps of 5 and equivalent ratios of 0.94, 0.90, 0.85, 0.80, 0.75, 0.71, 0.66 and 0.61 were considered. An ANN model based on standard back-propagation algorithms for the swirl burner was developed using some of the experimental data for training and validation. The performance of the ANN was tested by comparing the predicted outputs with the experimental values that were not used in training the network. R values of 0.94 were obtained for CO and NOx and 0.99 for flame temperature. These results show that very strong correlation exists between the ANN predicted values and the experimental results. Therefore, this study demonstrates that the performance and emissions of swirl burner can be accurately predicted using ANN approach.
Atomistic Simulations of Interfacial deformation and bonding mechanism of Pd-Cu Composite Metal Membrane using Cold Gas Dynamic Spray Process.
(Vacuum, 2020-12-01) Oyinbo, S.T.; Jen, T.C.; Zhu, Y.; Ajiboye, J.S.; Ismail, S.O.
Abstract The creation of atomic structures and the study of the deformation processes through molecular dynamics simulations have shown many advantages. However, gaps associated with the development and evolution of microstructure in the coating zone and dynamic processes that take place during cold gas dynamic sprayed materials still exist. The focus of this study was to investigate the interfacial deformation behaviours and the mechanism of bonding between atoms of palladium (Pd) and copper (Cu) composite metal membrane (CMM) using molecular dynamic simulations. The results confirmed that asymmetric deformation occurred during cold gas dynamic spray at the Pd-Cu interfacial region. As the impact time increases, the layer thickness at the interface also increases. The concentrations of Pd-Cu CMM at the interfacial zone showed the presence of phase transitions at relatively long impact time. Furthermore, CGDS deformation was found to be an unsteady and dynamic process. Explicit bond analysis in this study also has shown that breaking of atomic bonds is not the key mechanism for the initial Pd-Cu plastic deformation occurrence. The higher interfacial bonding energy and interfacial shearing strength at the Pd-Cu CMM interface expressed the bonding strength and compatibility of Pd and Cu.
Bio- Agro Waste Valorization and its Sustainability in the Industry: A Review
(International Conference on Engineering for Sustainable World (ICESW 2020), 2021-03) Afolalu, S. A.; Salawu, E.Y.; Ogedengbe, T.S.; Joseph, O. O.; Okwilagwe, Osise; Emetere, M. E.; Yusuf, O. O.; Noiki, A.A; Akinlabi, S.A
The application of bio-agro waste in industrial production has become extensive. Many industries have embarked in large scale production due to the broadness in the application of the bio-agro waste. This study vividly and succinctly surveyed the different bio-agro waste, its areas of application and its sustainability in industrial production. Several examples of bio-agro waste have been reported. Their relevance in bio-ethanol production has equally been discussed. More so, current research and development in harnessing the bio-agro waste were equally reported, to achieve better economic sustainability. Thus, the study has provided a new circular economic method for addressing the problems associated with bio-agro waste.
Biodiesel production by transmethylation of Nigerian palm kernel oil
(Ife Journal of Technology, 2009-11) Shote, AS; Betiku, Eriola; Asere, AA
The need for this study arose from the recent energy crisis coupled with the huge potential that Nigeria has for the production of Palm Kernel Oil (PKO). Locally produced PKO was chemically modified (methanolysis) to produce PKO-based biodiesel. The reaction temperature and the catalyst loading were maintained at 60 o C and 1.0% weight of oil, respectively. The methanol to oil molar ratio was kept at 6: 1. The production of PKO-based biodiesel (at 60 o C for 1.5 hours) by transmethylation process in the presence of NaOH as catalyst yielded crude products, Glycerol and biodiesel. Subsequently, PKO (parent oil), automotive gas oil (AGO) and PKO methyl esters transesterified were characterized to determine their properties and suitability as fuels in Compression Ignition Engine (CIE). Results of the transmethylated PKO showed that properties such as viscosity (3.359 cSt), specific gravity (0.8728), water content (nil) and flash point (100 o C) conformed to standards (ASTM, BIS). Properties of the PKO biodiesel were comparable with properties of AGO. Emissions assessment showed that CO concentration was reduced by 30% when PKO biodiesel was used in CIE compared with AGO. Hence, PKO-based biodiesel has a promising prospect for partial or total replacement for petro-diesel in CIE.
Characterisation of pulverised palm kernel shell for sustainable waste diversification
(International Journal of Scientific and Engineering Research, 2013-04) Fono-Tamo, R. S.; Koya, Olufemi A.
The paper presents a report on the physico-thermal properties and elemental composition of pulverized palm kernel shell to enhance its use in engineering applications. Clean palm kernel shell were dried, milled and screened to obtain particles 0.23 mm mean diameter. Experiments were conducted to evaluate the physical and thermal properties of the pulverized palm kernel shell and its differential thermal analysis. Its elemental composition was determined by X-Ray Fluorescent analysis. Test results showed that pulverized palm kernel shell consist mainly of non-ferrous metals. Its bulk density was 560 kg/m3; specific gravity, 1.26. Its thermal properties were characterized by thermal conductivity of 0.68 W/m K; specific heat capacity, 1.98 kj/kg K, and phase change at 101.40C. The report established significant potentials in the diversification of palm kernel shell from waste to fuel in improved combustion systems and as a future element in biomaterial composites.
Characteristics of CO and NOx emissions from combustion of transmethylated palm kernel oil-based biodiesel blends in a compression ignition engine
(Journal of King Saud University – Engineering Sciences, 2018-02) Shote, Adeola S.; Betiku, Eriola; Asere, Abraham A.
This study assessed hazardous emissions from transesterified Palm Kernel Oil-based (PKO-based) biodiesel blends in a Compression Ignition Engine (CIE). Automotive Gas Oil (AGO) was blended with the PKO-methyl esters in the ratios 1:9; 2:8; 3:7; . . .; 9:1. The various blends were thereafter fired in a CIE. Besides, 100% AGO and 100% PKO-methyl esters were also burnt in the CIE. Results showed that as the concentration of the PKO biodiesel increased in the blends, carbon monoxide (CO) emissions reduced. There was about 35% significant reduction in the lethal CO emissions as the concentration of methyl esters increased in the blends at 99.9% confidence (p 0.001). At 90% confidence, there were no significant changes in NOx emissions as a result of change in blend ratios (p > 0.01). There exists a degree of association between NOx and gas temperature in agreement with Zeldovich mechanism.
Characterization of Frictional Behavior in Cold Forging
(Tribology Letter, 2010-10-15) Jung, K.H.; Lee, H.C.; Ajiboye, J.S.; Im, Y.T.
In the present investigation, tip test was utilized to characterize the effects of surface roughness of the specimen and forming tools, rate of deformation, and type of lubricants on friction in solid and solid contact under high contact pressure at room temperature. For the test, a cylindrical specimen made of aluminum alloy of 6061-O was used and grease, corn oil, VG100, and VG32 were applied as lubricants. Single punch and two counter punch sets with different surface roughness of Ra = 0.08 and 0.63 lm were manufactured in order to investigate a frictional behavior during the test. In addition, two different deformation speeds of 0.1 and 5.0 mm/s were used for the test to check their effect on friction as well. Load levels and tip distances obtained from the test were compared to find out any correlation between the two. The change of surface topology of the specimen was monitored by optical measurement technique to better understand a frictional behavior at the punch and counter punch interfaces. Present investigation clearly shows that tip test is easy to apply to experimentally characterize the frictional behavior in cold forging under various processing conditions considered.
Chip Morphological Behaviour During Machining Of Ti-6Al-4V Using Refrigerated Soluble Oil
(IOP Conference Series: Materials Science and Engineering, 2021-08) Ogedengbe, T.S.; Abdulkareem, S.; Afolalu, S.A.; Ibitoye, S.O.
Chips formed during machining are a vital instrument for the assessment both of machinability of material and the effectiveness of the machining method adopted. Various approaches have been proposed by researchers to make machining Ti-6Al-4V easier, ranging from reduction of cutting speed and feed rate to the use of coolant during machining. In this study, investigatation of the effect of refrigerated soluble oil on machinability of Ti-6Al-4V via monitoring of the chips formed during the various machining processes was carried out. The chips formed for various machining conditions were collected using a designed chip receptor medium and was analyzed using a metallographic microscope with an attached stylus. The experiment was planned using central composite designs (CCD) of the Response Surface Methodology (RSM) resulting in a 20 experimental run plan for dry and wet machining. Machining factors considered were cutting speed, feed rate, depth of cut and coolant temperature with corresponding values 40-120 m/min, 0.05-0.20 mm/rev, 0.2-1.0 mm and 5-11°C respectively. Responses monitored chip thickness, tooth profile and peak height. The effect of various factors on responses were discussed. Basically, results show that chip diameter increased with an increase in cutting speed. However, the sawtooth profile on chip reduced with an increase in cutting speed. It was therefore concluded that coolant temperature has an effect on chip morphology during machining of Ti-6Al-4V using refrigerated coolant.
CO-pyrolysis of bituminous coal and coconut shell blends via thermogravimetric analysis
(Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2020-08) Adewole, Bamiji Zacheous; Adeboye, Busayo Sunday; Malomo, Babafemi Olamide; Obayopo, Sirajudeen Olanrewaju; Mamuru, Solomon Almanto
The thermal behavior of bituminous coal, coconut shell, and their blends during pyrolysis process was investigated in this study. The experiments were conducted at different weight percent of coconut shell (10, 20, 30, 40, and 50 wt%) and temperatures ranging from 30°C to 900°C. The DTG data for fuel blends showed additive profiles that reflected behavior of the individual fuel. When coconut shell was mixed with coal under weight percent of 20–50%, the nature of peaks in DTG profiles changed from higher to lower in the third stage reaction, shifting devolatilization temperature from 400°C to 450°C. This led to a decrease in the maximum rate of mass loss from 10.6% to 7.4%/min. However, the 10 wt% blend caused a slight increase in the maximum rate of mass loss from 10.6% to 11%/min. In addition, co-pyrolysis kinetics of fuel blends indicated that the blending of coconut shell with coal at BBR higher than 30% can increase the value of activation energy and induce slow pyrolysis of blends.
Co-pyrolysis of cassava peel with synthetic polymers: thermal and kinetic behaviors
(Waste Disposal & Sustainable Energy, 2021-06-24) Adeboye, B.S.; Adewole, B. Z.; Adedoja, A. M.; Obayopo, S. O.; Mamuru, S. A.; Idris, M. O.; Okediran, I. K.; Asere, A. A.
This research effort focuses on the co-pyrolysis of cassava peels waste and some synthetic polymers towards energy conversion and reducing the volume of these waste fractions dumped on dumpsites. The co-pyrolysis behavior and pyrolysis kinetics of various synthetic polymer wastes/cassava peel blends were investigated by blending cassava peel waste with low-density polyethylene (LDPE), polyethylene terephthalate (PET), and polystyrene (PS) at different weight ratios. The physical characteristics of each sample were investigated and the co-pyrolysis experiments were conducted at a heating rate of 10 °C/min from room temperature to 800 °C in N2 atmosphere in a thermogravimetric analyzer. Subsequent to thermal decomposition, kinetic analysis was done using the thermogravimetric data. Results from physicochemical characterization showed that cassava peel has a relatively lower calorific value of 15.92 MJ/kg compared with polystyrene (41.1 MJ/kg), low-density polyethylene (42.6 MJ/kg), and polyethylene terephthalate (21.1 MJ/kg). The thermal decomposition behavior of cassava peel was seen to be significantly different from those of the synthetic polymers. The decomposition of the biomass material such as cassava peel generally occurs in two stages while the decomposition of LDPE, PS, and PET occurred in a single stage. The activation energy required for thermal degradation in cassava peel was also found to be lower to that of the plastic material. The co-pyrolysis of cassava peel and different synthetic polymers affected the thermal and kinetic behaviors of the blends, reduce the activation energy and residue after pyrolysis.
Comparative Analysis of AISI 1050 Steel Using N5-Soluble Oil and Arachis Oil in Metal Cutting Operation
(Proceedings of the 30 th AGM and International Conference of the Nigerian Institution for Mechanical Engineers. Hosted by The Nigerian Institution of Mechanical Engineers, Kaduna, Nigeria, 24 th - 27 th , October, 2017., 2017-10-27) Abdulkareem, S.; Ogedengbe, T.S.; Aweda, J.O.; Khan, A.A
The use of coolant during cutting processes does not only help in the improvement of surface integrity and increase in tool life, but it also facilitates the conservation of energy due to reduction in power consumed during the process. However, some of these coolants affect human health negatively, hence there is need to consider alternatives. The influence of N5- soluble oil and Arachis oil on machinability of carbon steels is reported in this paper. The performance of the use of soluble oil and Arachis oil using flooded cooling approach was investigated in with interest on their effects on temperature at cutting zone, surface roughness, chip formation and material removal rate. The experimental runs were designed using Taguchi L18 orthogonal array using Minitab version 16 and temperature at the cutting zone was monitored using a digital thermometer and a k-type thermocouple wire. Analysis of experimental results was done with focus on percentage contributions of various factors affecting surface roughness and material removal rate and chip profile. It was observed that, the use of Arachis oil as cutting fluid produced a surface finish of 35% improvement compared to soluble oil. Additionally, the chips formed using Arachis oil as coolant is more ductile and continuous than those obtained using N5soluble oil.
Comparative Analysis of AISI 1050 Steel Using N5-Soluble Oil and Arachis Oil in Metal Cutting Operation
(Proceedings of the 30th AGM and International Conference of the Nigerian Institution for Mechanical Engineers. Kaduna, 2017-10) Abdulkareem, Sulaiman; Ogedengbe, Temitayo S.; Aweda, Jacob O.; Khan, Ali A.
The use of coolant during cutting processes does not only help in the improvement of surface integrity and increase in tool life, but it also facilitates the conservation of energy due to reduction in power consumed during the process. However, some of these coolants affect human health negatively, hence there is need to consider alternatives. The influence of N5- soluble oil and Arachis oil on machinability of carbon steels is reported in this paper. The performance of the use of soluble oil and Arachis oil using flooded cooling approach was investigated in with interest on their effects on temperature at cutting zone, surface roughness, chip formation and material removal rate. The experimental runs were designed using Taguchi L18 orthogonal array using Minitab version 16 and temperature at the cutting zone was monitored using a digital thermometer and a k-type thermocouple wire. Analysis of experimental results was done with focus on percentage contributions of various factors affecting surface roughness and material removal rate and chip profile. It was observed that, the use of Arachis oil as cutting fluid produced a surface finish of 35% improvement compared to soluble oil. Additionally, the chips formed using Arachis oil as coolant is more ductile and continuous than those obtained using N5soluble oil
Comparative analysis of exhaust gases obtained in S.I and C.I of an internal combustion engine
(Scholars Research Library, 2015) Alabi, I. O.; Olaiya, K. A.; Kareem, M. O.; Olalekan, A. I.
ICE which could be spark ignition (S.I) or compression ignition (C.I) engine is one of the building blocks of modern civilization. In light of this, an effective engine should be able to contribute immensely to a safe environment. Numerous factors like fuel economy, power and torque, reliability, pollution, safety and cost are necessary in determining and comparing the effectiveness of the engines. This paper identifies, examines and compares the rate of incombustible particles present in the engines (S.I and C.I) at varying loading and speed conditions via exhaust gas detector. Post-hoc analysis was carried out using SPSS. It was discovered that CO and HC are the most dangerous incombustible particles present in engines and also the incombustible rate is more pronounced in C.I than S.I engine, which confirmed that S.I. engine is far better in terms of pollution reduction. Probable recommendations were later made.
Comparative Analysis of Machining Stainless Steel using Soluble and Vegetable oils as Cutting Fluids
(International Journal of Engineering Materials and Manufacture, 2019-03-01) OGEDENGBE, T.S.; AWE, Peter; Joseph, Ojotu Ijiwo
In this study, the performance of groundnut oil as an alternate cutting fluid was compared with that of soluble oil during machining of stainless steel. The temperature at the cutting zone, surface roughness and the chip formation were monitored under the two cutting conditions (soluble oil and vegetable oil). The machining parameters used were cutting speed (75 – 135 rev/min), feed rate (0.01 – 0.05 mm3/mm) and depth of cut (0.01 – 0.08 mm). The experiment was designed using Taguchi orthogonal array of Minitab 18 which generated a 9 run machining parameter mix for the experimentation. The Physiochemical properties of the various fluids were also analyzed to determine the properties and constituent elements of the cutting fluids. The actual machining of the stainless steel bar was done using a Colchester mastiff lathe machine. Results show that feed rate and cutting speed had the most significant effect on surface roughness during machining of stainless steel both with groundnut oil and soluble oil. Soluble oil was a better coolant but poorer in lubrication as vegetable oil reduced surface roughness more when used. Surface roughness value improved from 9.21μm during machining with soluble oil to 3.84μm during machining with groundnut oil which represented a 58.3% improvement. Hence, vegetable oil is therefore recommended as good alternative cutting fluid to soluble oil during machining of stainless steel.
A Comparative Performance and Emission Analysis of Blended Groundnut Oil and Mineral Oil Based Lubricants Using a Spark Ignition Engine
(The CIGR E journal Manuscript, 2008-09) Ejilah, I. R; Asere, A. A.
This paper presents the performance and emission behaviour of a spark ignition engine run on groundnut oil blended lubricants. However, for the purpose of comparism, benchmark tests were carried out on multigrade and monograde motor oils. A 5.0 h.p engine test-bed incorporated with an A.C dynamometer and flue gas analyzer was used to conduct the tests. At maximum engine speed, the groundnut oil blended lubricants generated an exhaust temperature of 6.02% higher than multigrade oil, and 6.26% higher than monograde oil. The brake power was 12.70% and 10.94% higher than the monograde and multigrade oils. In terms of fuel economy, the monograde and groundnut oil blended lubricants are 7.50% and 2.18% higher than multigrade oil respectively. It is shown that as the proportion of viscosity modifier in the oil sample increases, exhaust temperature, brake power, brake mean effective pressure (b.m.ep) also increases, while the specific fuel consumption diminishes. At various speeds, CO2 level emitted by the use of groundnut oil blended lubricants was observed to be higher than it was the case for multigrade and monograde oils. In the light of the fast depleting fossil fuel reserve in Nigeria, this work has demonstrated the feasibility of using groundnut oil blends as lubricant substitutes in spark ignition engines.
A Comparative Performance and Emission Analysis of Blended Groundnut Oil and Mineral Oil Based Lubricants Using a Spark Ignition Engine.
(Agricultural Engineering International: The CIGR E journal Manuscript EE 07017., 2008-09) Ejilah, I. R; Asere, A. A.
This paper presents the performance and emission behaviour of a spark ignition engine run on groundnut oil blended lubricants. However, for the purpose of comparism, benchmark tests were carried out on multigrade and monograde motor oils. A 5.0 h.p engine test-bed incorporated with an A.C dynamometer and flue gas analyzer was used to conduct the tests. At maximum engine speed, the groundnut oil blended lubricants generated an exhaust temperature of 6.02% higher than multigrade oil, and 6.26% higher than monograde oil. The brake power was 12.70% and 10.94% higher than the monograde and multigrade oils. In terms of fuel economy, the monograde and groundnut oil blended lubricants are 7.50% and 2.18% higher than multigrade oil respectively. It is shown that as the proportion of viscosity modifier in the oil sample increases, exhaust temperature, brake power, brake mean effective pressure (b.m.e.p) also increases, while the specific fuel consumption diminishes. At various speeds, CO2 level emitted by the use of groundnut oil blended lubricants was observed to be higher than it was the case for multigrade and monograde oils. In the light of the fast depleting fossil fuel reserve in Nigeria, this work has demonstrated the feasibility of using groundnut oil blends as lubricant substitutes in spark ignition engines.
Comparison of the Elemental Structure and Emission Characteristics of Selected PVC and Non PVC Ceiling Materials Available in Nigerian Markets
(International Journal of Applied Engineering Research, 2017) Dirisu, J.O; Asere, A.A.; et, al
The recurring fire outbreak in buildings in Nigeria is quite alarming, just as the shift to the use of PVC as a choice for ceiling material due to its aesthetic appearance is on the increase. Hence this study determined the emission characteristics PVC and non-PVC samples. This was done with a view to establishing their suitability as ceiling materials in building designs for tropical countries and providing thermal and combustion data for building stakeholders that could help to checkmate man made fire disasters. This experiment involves the burning of a consistent mass, 50g of 6 samples of 3 PVC and 3 non-PVC in an open furnace where the combustion is carefully controlled. It investigates the flue gasses concentration emitted in the cause of fire outbreak and its effect on occupants. It responds to the question in mind that not only visible flame kills but also toxicity from flue gas can be detrimental to health of victims. The results showed that PVC samples are unwelcome in terms of their emission characteristics which were due to their elemental makeup of their composites such as PVC recorded highest Carbon composition of 77.9% and lowest oxygen composition of 18.0 %. VOCs are cancerous, cause dizziness, rapid heartbeat, vomiting and eventual death. Benzene, a known VOC, is used in making PVC which is a human carcinogen compound. Ceiling materials that will achieve low noxious emission and as well fire retardant should be investigated and employed for use. These materials can be improved upon to achieve environmental friendly building materials.
Computationally Efficient Stratified Flow Wet Angle Correlation for High Resolution Simulations
(International Journal of Scientific & Engineering Research, 2019-01) Oloruntoba, Olusola; Kara, Fuat
In high resolution two-phase pipe flow simulations, such as slug capturing simulation for liquid-gas pipe flow, explicit calculation of stratified flow wet angle has been proposed to improve computational speed of simulations. Most phenomenological and approximate models for obtaining reliable predictions for stratified flow wet angle employ iterative methods or contain long explicit equations which reduce computational efficiency of these models in high-resolution simulations. Therefore, the aim of this study is to adapt a simple mathematical model for predicting stratified flow wet angle to achieve computationally efficient high-resolution liquid-gas pipe flow simulations. The proposed model for predicting stratified flow wet angle is obtained by fitting the generic regression model, Hoerl power law, to analytical stratified flow wet angle data. The proposed model is compared with existing prediction model. Results obtained show that the prediction model proposed gives up to 25.9% savings in computational time over the existing prediction model.
Computer Aided Plant Layout Development for an Aluminum Product Factory.
(The Pacific Journal of Science and Technology., 2012) Ogedengbe, T.S.; Adejuyigbe, S.B.; Ismaila, S.O.; Adewumi, B.A.; Ali, D.M.
This study presents research into the use of computers as a tool to aid the planning of layouts in factories to reduce daily cost incurred, using developed software. The approach involves identifying and solving plant layout problems (especially closeness relationship problems) thereby generating an ideal layout through the use of computer software which was developed using the programming language known as Visual Basic. A building products fabrication plant in Lagos, Nigeria was used as a case study in the research. It was discovered that the computer software developed (AUTO LAY 2010) could be used to generate alternative layouts which are more effective as it reduced material movement between departments and hence lowered Transportation cost, these ultimately reduces the relative cost of setting up facilities in a company. The results derived from the application of AUTO LAY 2010 to the case study company generated a layout with a cost reduction of ₦500.00, ₦33,000.00, and ₦1,000.00 daily in the office, production, and whole plant sections of the case study factory respectively, resulting in a cost reduction of ₦34,500.00 daily and about N9 million annually. These results show that the use of computer software in modern facility design will not only save costs but also enhance production and thereby increase the profit margins in the manufacturing industry.
Computer Aided Plumbing Design
(Academic Journals Inc., USA, 2007) Ajayi, Oluseyi; Ajayi, Oluseyi; Koya, Olufemi A.; Koya, Olufemi A.
This study has been used to eliminate the rigorous activities and time consuming mathematical analysis involved in Plumbing design. The various mathematical steps employed in the design of plumbing systems has been converted into easily interpreted hand user computer program that can be used to generate automatically all the various parameters needed for full design work, when the input data such as head available, various number of fittings, actual length of pipe run and assumed pipe diameter are provided. This has been used to provide a pathway to easy plumbing design

Browse

Browsing Mechanical Engineering by Title

Results Per Page

Sort Options