Using Artificial Neural Networks to predict the unconfined compressive Strength of Clayey Soils Stabilized by Various Stabilization Agents

Khalid R. Mahmood Aljanabi,Nihad Bahaaldeen Salih 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.9

Soil stabilization is commonly accepted for amending undesired soil geotechnical characteristics to be suitable for various structures foundations. Various additives namely iron ore (UIR), used automobile oil (UAO), shale rock powder (ShP), a mixture of hydrated lime, gypsum, and cement (LGC), waste plastic pieces (WPP), rice husk (RH), and sandstone powder (SSP) were used with different percentages. The experimental results reveal that additives namely SSP, UIR, and ShP showed an improvement in the unconfined compressive strength (UCS) of the soil, while the rest of the additives showed that the higher the percentage of the additive, the lower the unconfined compressive strength. Neural networks can capture the complex relationship that links several parameters together and provides the possibility to study the effect of each input variable on the desired output. Thus, this study was implemented to examine the applicability of Artificial Neural Networks (ANNs) to perform an effective prediction model for some geotechnical characteristics correlation of stabilized clayey soils utilizing various stabilization agents. Four input variables including liquid limit (LL), plastic limit (PL), linear shrinkage limit (SL), and additives type while the output is unconfined compressive strength (UCS) of the stabilized clayey samples were utilized. The selected geotechnical parameters can be determined in a laboratory on soil samples; however, these tests are time-consuming and expensive. Therefore, one model was developed to estimate the UCS from the consistency parameters. The ANNs models were developed and verified using a database of 74 cases of actual measured parameters of stabilized clayey soils. As the result of the study, the proposed ANNs model has good accuracy for the prediction of the UCS of clayey soils

Shear response of lean duplex stainless steel plate girders

Salam R. Armoosh,A.R. Khalim,Akram Sh. Mahmood 국제구조공학회 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.54 No.6

Carbon steel plate girders have been used on a large scale in the building industry. Nowadays, Lean Duplex Stainless Steel (LDSS) plate girders are gaining popularity as they possess greater strength and are more impervious to corrosion than those that are constructed from carbon steel. Regardless of their popularity, there is very limited information with regards to their shear behavior. In this paper, the non-linear finite element analysis was employed to investigate the shear behavior of LDSS plate girders. Parameters considered were the web thickness, the flange width, and the girders aspect ratio. The analysis revealed that although the shear behavior of the LDSS girders was no different from that of carbon steel plate girders, it had obviously been affected by the non-linearity of the material. Furthermore, the selected parameters were found to pronounce effect on the shear capacity of the LDSS girders. That is, the shear capacity increased considerably with web thickness, and increased slightly with flange width. However, it was reduced as the aspect ratio increased. Comparisons between the finite element analysis failure loads and those predicted by the current European Code of Practice revealed that the latter underestimated the shear strength of the LDSS plate girders.

Pathogenesis and Bone Resorption in Acquired Cholesteatoma: Current Knowledge and Future Prospectives

Mahmood A. Hamed,Seiichi Nakata,Ramadan H. Sayed,Hiromi Ueda,Badawy S. Badawy,Yoichi Nishimura,Takuro Kojima,Noboru Iwata,Ahmed R. Ahmed,Khalid Dahy,Naoki Kondo,Kenji Suzuki 대한이비인후과학회 2016 Clinical and Experimental Otorhinolaryngology Vol.9 No.4

Cholesteatoma is a cystic non tumorous lesion of the temporal bone that has the ability to destroy nearby structures by its power to cause bone resorption and as a result, fatal complications prevail. We aimed to conduct a comprehensive review for pathogenesis of acquired cholesteatoma, bone resorption mechanisms, and offer a future vision of this serious disease. We have reviewed different theories for pathogenesis of acquired cholesteatoma including the most relevant and updated ones with special emphasis on the mechanisms of bone resorption through Medline/PubMed research using the keywords ‘aetiopathogenesis, bone resorption, acquired cholesteatoma, temporal bone, and cytokines.’ In order to strengthen our study, we searched the reference lists of identified reviews. Cholesteatoma is a subject of debate among otolaryngologists since it was prescribed firstly. Over many decades, several theories were postulated for aetiopathogenesis of cholesteatoma with a tendency to follow more than one theory to explain the proper nature of that disease. Until now, the mechanism of bone resorption has yet to be more clarified. In the last century, a leap has occurred in the field of biomolecular cholesteatoma research which improved our knowledge about its pathophysiology and bone destructive mechanism. However, surgery is still the only available treatment. We conclude that discovery of new therapeutic choices for cholesteatoma other than surgery by the use of anti-growth, anti-proliferative, apoptotic agents as well as medications that antagonize osteoclastogenesis should be the main concern in the future clinical and experimental research work. Also, searching for predictors of the aggressiveness of cholesteatoma can affect the timing of intervention and prevent occurrence of complications.

On the origin of viscoelastic Taylor–Couette instability resulted from normal stress differences

Mahmood Norouzi,M.H. Sedaghat,M.M. Shahmardan,M.R.H. Nobari 한국유변학회 2015 Korea-Australia rheology journal Vol.27 No.1

In this paper, the effect of normal stress differences on the viscoelastic Taylor–Couette instability is studied numerically. The governing equations are discretized using FTCS finite difference method on a staggered mesh based on the artificial compressibility algorithm. Using the CEF model as the constitutive equation and the Carreau–Yasuda model as the viscometric functions, the flow between rotating cylinders has been studied for a range of radius ratios, Taylor numbers and rheological properties. It is shown that increasing the first normal stress difference destabilizes the flow field while increasing the negative second normal stress difference stabilizes the flow field. The main contribution of the current study is an answer to thisquestion: How do the first and second normal stress differences affect the stability of viscoelastic flowbetween rotating cylinders? For this reason, we used the order of magnitude technique to obtain a force balancerelation in the core region of flow. Based on this relation and numerical simulation, the origin of viscoelasticTaylor–Couette instability resulted from normal stress differences are studied in detail. Furthermore, a two dimensional analytical solution for the main flow velocity component between finiterotating cylinders is carried out considering the end effect of stationary walls

First principle study of vanadium doped ZnS: Structural, electronic, elastic, magnetic and optical properties using mBJ approximation

Q. Mahmood,G. Murtaza,R. Ahmad,T. Hussain,I.G. Will 한국물리학회 2016 Current Applied Physics Vol.16 No.3

The structural, electronic, magnetic, mechanical and optical properties of ternary Zn1xVxS (x ¼ 0.0, 0.25, 0.50, 0.75 and 1.0) ferromagnetic semiconductor alloys have been studied in the zinc blende (ZB) phase, by first principle approach. Density functional theory has been employed to calculate the fundamental properties of the alloys using full-potential linearized augmented plane-wave plus the local orbitals (FPLAPW þ Lo) method. In addition, the electronic and magnetic properties are investigated by the local spin density approximation coupled with the modified BeckeeJohnson exchange potential (mBJLDA). Structural analysis revealed that the structure of the three alloys Zn0.75V0.25S, Zn0.50V0.50S, and Zn0.25V0.75S are stable in the ferromagnetic phase. It is noted that the calculated lattice constant decreases, while the bulk modulus increases with the increase of V content. The density of states and spin polarized band structure investigation demonstrated the half-metallic ferromagnetic characteristics of the investigated alloys and are also used to determines ped exchange constants N0a and N0b, due to S (p) eV(3d) hybridization. These results reveal that magnetic moment of V dopant element reduced from its free space value of 3 mB, because the Zn and S sites acquire minor atomic magnetic moments. The energy band gap analysis show an increasing trend with V doping that makes our compound a suitable candidate for the fabrication of devices operating in the ultraviolet region. Moreover, the static dielectric constant, ε1 (u), and static refractive index, n (u), increases with V contents. The incorporation of V generates some new peaks in the energy regions of 0e2.83 eV and 4e10 eV. The substitution by V increases the intensity of the peaks, and a slight red shift has been observed in the absorption peak. The extinction coefficient k (u) and optical conductivity also follow a similar trend to that of the dielectric constants. These results give deep insight into the design of devices for optical and spintronics applications using V doped ZnS.

Does school connectedness differ by student ethnicity? A latent class analysis among Canadian youth

Patte Karen A.,Gohari Mahmood R.,Leatherdale Scott T. 한국다문화교육학회 2021 Multicultural Education Review Vol.13 No.1

Latent class analysis was performed to identify clusters of items on the Longitudinal Study of Adolescent Health – School Connectedness Scale among students. Cluster membership was explored by student-reported ethnicity. The sample included students attending Canadian secondary schools in two waves of the COMPASS study: Years 4 (Y4:2015/16) (N=40,436) and 7 (Y7:2018/19) (N=60,610). Results were comparable across waves. Four clusters resulted: strongly connected (Y4 66.6%; Y7 67.9%), socially disconnected (14.1%; 15.2%; perceptions of equitable treatment but lacking feelings of belonging), social belonging (11.9%; 10.3%; feelings of being part of their school and close to others, but less likely to perceive equitable treatment), and weakly connected (7.4%; 6.6%). White and Asian students were more likely to be ‘strongly connected’, while Black and ‘other’ or mixed ethnicity students were overrepresented in the ‘weakly connected’ and ‘social belonging’ clusters. Cluster variations merit attention to improve how racialized and ethnic minority youth experience school environments.

Stress waves transmission from railway track over geogrid reinforced ballast underlain by clay

Fattah, Mohammed Y.,Mahmood, Mahmood R.,Aswad, Mohammed F. Techno-Press 2022 Structural monitoring and maintenance Vol.9 No.1

Extensive laboratory tests were conducted to investigate the effect of load amplitude, geogrid position, and number of geogrid layers, thickness of ballast layer and clay stiffness on behavior of reinforced ballast layer and induced strains in geogrid. A half full-scale railway was constructed for carrying out the tests, the model consists of two rails 800 mm in length with three wooden sleepers (900 mm × 10 mm × 10 mm). The ballast was overlying 500 mm thickness clay in two states, soft and stiff state. Laboratory tests were conducted to investigate the response of the ballast and the clay layers where the ballast was reinforced by a geogrid. Settlement in ballast and clay, soil pressure and pore water pressure induced in the clay were measured in reinforced and unreinforced ballast cases. It was concluded that the effect of frequency on the settlement ratio is almost constant after 500 cycles. This is due to that the total settlement after 500 cycles, almost reached its peak value, which means that the ballast particles become very close to each other, so the frequency is less effective for high contact particles forces. The average maximum vertical stress and pore water pressure increased with frequency.

Residual stresses measurement in the butt joint welded metals using FSW and TIG methods

Fathollah Taheri-Behrooz,Mohammad R.M. Aliha,Mahmood Maroofi,Vahid Hadizadeh 국제구조공학회 2018 Steel and Composite Structures, An International J Vol.28 No.6

Friction Stir Welding (FSW) is a solid-state process, where the objects are joined together without reaching their melting point. It has been shown that this method is a suitable way to join dissimilar aluminium alloys. The current article employed hole drilling technique to measure the residual stress distribution experimentally in different zones of dissimilar aluminium alloys AA6061-T6 and AA7075-T6 Butt welded using FSW. Results are compared with those of similar AA6061-T6 plates joined using a conventional fusion welding method called tungsten inert gas (TIG). Also, the evolution of the residual stresses in the thickness direction was investigated, and it was found that the maximum residual stresses are below the yield strength of the material in the shoulder region. It was also revealed that the longitudinal residual stresses in the joint were much larger than the transverse residual stresses. Meanwhile, Vickers micro hardness measurements were performed in the cross-section of the samples. The largest hardness values were observed in the stir zone (SZ) adjacent to the advancing side whereas low hardness values were measured at the HAZ of both alloys and the SZ adjacent to the retreating side.

Instability analysis of microfilaments with and without surface effects using Euler theory

Taj, Muhammad,Khadimallah, Mohamed A.,Hussain, Muzamal,Mahmood, Shaid,Safeer, Muhammad,Rashid, Yahya,Ahmad, Manzoor,Naeem, M. Nawaz,Asghar, Sehar,Ponnore, Joffin,Al Qahtani, Abdelaziz,Mahmoud, S.R.,Al Techno-Press 2021 Advances in nano research Vol.10 No.6

The study of cell components has been an active area of research since the last few decades. Cytoskeleton of the cell which gives shape and provides structure to the cell has three main components, microtubules, microfilaments and intermediate filaments. Each of the cytoskeletal components is surrounded by various filamentous or the other cytoskeletal components act as a surface layer on these filaments. The stability of these components affected when cell perform various functions in the body and as a result these filaments buckle, vibrate and bend. In the present study the buckling behavior of microfilament is discussed with the effects of surface by using Euler Bernoulli beam theory and the obtained results for free and surrounded microfilament are shown in the tables and figures.

First principles investigations of electronics, magnetic, and thermoelectric properties of rare earth based PrYO3(Y¼Cr, V) perovskites

B. Sabir,G. Murtaza,Q. Mahmood,R. Ahmad,K.C. Bhamu 한국물리학회 2017 Current Applied Physics Vol.17 No.11

The structural, electronic, magnetic, optical and thermoelectric properties of PrYO3(Y¼Cr, V) have been studied by using density functional based FP-LAPWþ lo method as implemented into WIEN2k code. The analysis of band structures and density of states confirm the half metallic ferromagnetism in studied compounds. The nature and origin of ferromagnetism has been depicted in terms of crystal field energies, exchange energies involved and exchange constants. Moreover, the reduction of magnetic moment from V/Cr, Pr sites and generation of small magnetic moments on oxygen and interstitials sites leads to negative value of indirect exchange energy Dx(pd) and strong hybridization. Finally, the thermoelectric behavior has been explained by discussing the electrical conductivity, thermal conductivity, Seebeck coefficient, power factor and thermal efficiency. Moreover, evaluation of PrYO3 on the basis of its magnetic and thermoelectric properties conform that the compounds are much suitable for spintronic and thermoelectric applications.