Experimental and Numerical Analyses of the Effects of Overload on the Fatigue Life of Aluminum Alloy Panels Repaired with Bonded Composite Patch

N. H. M. Bouchkara,Abdulmohsen Albedah,Faycal Benyahia,Sohail M. A. Khan Mohammed,Bel Abbes Bachir Bouiadjra 한국항공우주학회 2021 International Journal of Aeronautical and Space Sc Vol.22 No.5

In this study, we analyzed the effect of a single overload fatigue cycle on the efficiency of bonded composite patch repair on a cracked Al 2024 T3 aluminum plate. Experimental and numerical analyses were performed to achieve the objective of the study. In the experimental part of the study, fatigue tests were conducted on a V-notched aluminum plate subjected to a constant amplitude fatigue loading with an overload applied at a relative crack length of 0.06 (a/W = 0.06). The plate was repaired with a carbon/epoxy composite patch. A fatigue life curve (a = f(N)) was plotted for the patched and unpatched specimens using the results of the experimental tests, and scanning electron microscopy images of the fracture surfaces of the failed specimens were observed. In the numerical part, the elastic–plastic finite element method was used to evaluate the plasticity induced by the overload on the patched plate and to analyze the adhesive damage after this overload was applied. The obtained results demonstrate that the patch deposition of the overload can lead to an extended fatigue life, and the adhesive damage after the overload is quite significant, but the risk of total failure of the adhesive layer is not high.

Conversion of Y into SSZ-13 zeolites and ethylene-to-propylene reactions over the obtained SSZ-13 zeolites

Jun, J.W.,Khan, N.A.,Seo, P.W.,Kim, C.U.,Kim, H.J.,Jhung, S.H. Elsevier 2016 CHEMICAL ENGINEERING JOURNAL -LAUSANNE- Vol.303 No.-

Y zeolites having wide ranges of SiO<SUB>2</SUB>/Al<SUB>2</SUB>O<SUB>3</SUB> ratios (silica/alumina ratios or SARs) were converted into SSZ-13 zeolites in the presence of N,N,N-trimethyl-1-adamantanamine iodide (TMAda-I) as a template. SSZ-13s with increased SARs could be obtained from Y zeolites having SARs of 5.1-80 and sodium silicate by both conventional electric (CE) and microwave (MW) heating. The syntheses conducted using MW and CE heating at 140<SUP>o</SUP>C were completed in 2h and 144h, respectively, because of accelerations by MW in both the nucleation and crystal growth stages. The obtained yields of SSZ-13 decreased as SARs of the starting Y zeolites increased, demonstrating the relatively easy conversion of aluminous Y into SSZ-13. The obtained SSZ-13s with wide SAR ranges (19-287) were applied as catalysts in the direct conversion of ethylene-to-propylene (ETP) to understand the effect of the SARs on the ETP performances, including the conversion of ethylene and propylene selectivity. The stability of ETP was highly dependent on the SAR of the SSZ-13 zeolites. SSZ-13s with excessively high or low SARs caused low ethylene conversion (from the beginning of the reaction) or rapid deactivation in the conversion, respectively. The propylene selectivity or yield (at a fixed ethylene conversion of 80%) generally increased with decreasing SARs (up to 19) of SSZ-13s under the studied conditions because of a steady increase in the selectivities for butenes and higher products with increasing SARs of SSZ-13s.

Structure-based magnetic, electrical and transport properties of Ni–Zn–Co ferrite by V5+ substitution

Hossain M.D.,Khan M.N.I.,Hossain Md Sarowar,Ahned S.J.,Alam M.K.,Liba S.I.,Hakim M.A.,Jamil A.T.M.K. 한국물리학회 2022 Current Applied Physics Vol.43 No.-

This article presents the modification of structure-based magnetic, electronic and transport properties along with the conduction mechanism and its relaxation process in a Ni–Zn–Co ferrite tailored by V5+ substitution at B-site replacing Fe3+ ions. The composition Ni0.7Zn0.2Co0.1Fe2-xVxO4 (0≤ x≤ 0.12) was synthesized by standard solid-state reaction method and all samples were crystallized with a single-phase cubic spinel structure belonging to the Fd3m space group. The lattice constants decreased gradually from 8.3673≽A to 8.3602≽A and the average grain sizes (DSEM) are also decreased from 6.92 μm to 1.99 μm due to V5+ ions substitution at Fe3+ of B-site. However, more than 25% of Fe3+ ions migrate to A-site from B-site due to V5+ substitution at Fe3+ of B-site. In all samples θD does not strictly follow the Anderson’s prediction, rather it monotonically decreases to a low value until x = 0.12. Magnetic phase transition temperature shifted to the lower temperature and the net magnetization (ηeB) decreases due to V5+ substitution in Ni–Zn–Co ferrite. Apart this, during conduction charge carriers should require more energy to jump from one cationic site to other for V5+ substitution in the Ni–Zn–Co ferrite and the activation energy (Ea) is much more higher in V5+ substituted sample. Moreover, long-range interaction with localized relaxation mechanism is observed in V5+ doped samples. The resistance at the grain (Rg) is maximum (243.09 Ω) for the sample x = 0.10 while grain boundary resistance (Rgb) is maximum (5.98×105 Ω) for the sample x = 0.07. However, the higher value of ρdC for x = 0.12 sample ensures to be suitable for electromagnets, transformers, electronic inductors, and at high-frequency applications. Moreover, x = 0.07 sample displays high value of TCR ( -8.6%/K at 418 K) which may be utilized as an infrared detector for night vision bolometer material.

New constituents triterpene ester and sugar derivatives from Panax ginseng Meyer and their evaluation of antioxidant activities

Chung, I.M.,Siddiqui, N.A.,Kim, S.H.,Nagella, P.,Khan, A.A.,Ali, M.,Ahmad, A. Saudi Pharmaceutical Society 2017 Saudi pharmaceutical journal Vol.25 No.5

Panax ginseng C. A. Meyer (Araliaceae), is a well-known herb and used in the old established system of Oriental remedy, especially in Japan, China and Korea. Four new compounds characterized as (cis)- 7β,11α,19,21-tetra-O-decanoyl-18, 22β-dihydroxy-dammar-1-en-3-one (1), 3β,4α,12β-trihydroxystigmast-5-en-21-yl octadecan-9',12'-dienoate (2), dammar-12, 24-dien-3α, 6β, 15α-triol-3α-D-arabinopyranosyl-6β-L-arabinopyranoside (3) and dammar-24-en-3α, 6β, 16α, 20β-tetraol-3α-D-arabinopyranosyl-6β-D-arabinopyranoside (4) were isolated and established from the ethyl acetate and butanol extracts of the roots of P. ginseng. Their structures were established on the basis of spectral data and chemical reactions. Natural compounds indicative a great reservoir of materials and compounds with evolved biological activity, including antioxidant. Compounds 1-4 were investigated in vitro for antioxidant potential using ferric reducing antioxidant power (FRAP), the Nitric oxide (NO) scavenging activity, reducing power, phosphomolybdenum and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging actions, and the decision showed the compounds 3and 4 have probablyessential antioxidant properties than the compounds 1and 2 presented weak activity.

Critical Analysis of Density-based Spatial Clustering of Applications with Noise (DBSCAN) Techniques

Said Akbar,M.N.A. Khan 보안공학연구지원센터 2014 International Journal of Database Theory and Appli Vol.7 No.5

Clustering is the most used technique in data mining. Clustering maximize the intra-cluster similarity and minimize the inter clusters similarity. DBSCAN is the basic density based clustering algorithm. Cluster is defined as regions of high density are separated from regions that are less dense. DBSCAN algorithm can discover clusters of arbitrary shapes and size in large spatial databases. Beside its popularity, DBSCAN has drawbacks that its worst time complexity reaches to O (n2). Similarly, it cannot deal with varied densities. It is hard to know the initial value of input parameters. In this study, we have studied and discussed some significant enhancement of DBSCAN algorithm to tackle with these problems. We analysed all the enhancements to computational time and output to the original DBSCAN. Majority of variations adopted hybrid techniques and use partitioning to overcome the limitations of DBSCAN algorithm. Some of which performs better and some have their own usefulness and characteristics.

MULTI-RESPONSE OPTIMIZATION OF DIESEL ENGINE PERFORMANCE PARAMETERS USING THUMBA BIODIESEL-DIESEL BLENDS BY APPLYING THE TAGUCHI METHOD AND GREY RELATIONAL ANALYSIS

A. KARNWAL,M. M. HASAN,N. KUMAR,A. N. SIDDIQUEE,Z. A. KHAN 한국자동차공학회 2011 International journal of automotive technology Vol.12 No.4

This paper presents an experimental study that involves an application of the Taguchi method and grey relational analysis to determine the optimum factor level to obtain optimum multiple-performance characteristics of a diesel engine run with different low-percentage thumba biodiesel-diesel blends. Four factors, namely, low-percentage thumba biodiesel-diesel blend, compression ratio, nozzle opening pressure and injection timing were each considered at three levels. An L9 orthogonal array was used to collect data for various engine performance- and emission-related responses under different engine loads. The signal-to-noise (S/N) ratio and grey relational analysis were used for data analysis. The results of the study revealed that the combination of a blend consisting of 30% thumba biodiesel (B30), a compression ratio of 14, anozzle opening pressure of 250 bar and an injection timing of 20o produces maximum multiple performance of a diesel engine with minimum multiple emissions from the engine.

An investigation of boat-tail helmet to reduce drag

Pathan, Khizar A.,Khan, Sher A.,Shaikh, Aadil N.,Pathan, Arsalan A.,Khan, Shahnawaz A. Techno-Press 2021 Advances in aircraft and spacecraft science Vol.8 No.3

A helmet is a kind of shielding equipment used to shield the head from fatal injuries. The helmet experiences drag while moving at a certain velocity. The total drag on the helmet increases with an increase in velocity. The drag force at high velocity has a significant effect on the rider's neck and may result in cervical spondylosis. Now a day's neck pain, neck sprain, spondylosis have become significant issues related to the human body. The reduction of drag on the helmet will be a boon for society, which will reduce the force on the neck. The decrease in drag is an essential field of study. The drag force can be reduced by various methods like coating on the surface, modifying the helmet's shape, etc. The study's purpose is to decrease drag on the helmet by improving the helmet's shape. The CFD analysis is carried out to find the best profile of the helmet and fineness ratio of the boat-tailed helmet to minimize drag. The CFD results are validated with the wind tunnel laboratory outcomes. Based on the findings, a considerable reduction in the drag is accomplished at the velocity of 32.5 m/s.

An investigation of boat-tail helmet to reduce drag

Pathan, Khizar A.,Khan, Sher A.,Shaikh, Aadil N.,Pathan, Arsalan A.,Khan, Shahnawaz A. Techno-Press 2021 Advances in aircraft and spacecraft science Vol.8 No.3

A helmet is a kind of shielding equipment used to shield the head from fatal injuries. The helmet experiences drag while moving at a certain velocity. The total drag on the helmet increases with an increase in velocity. The drag force at high velocity has a significant effect on the rider's neck and may result in cervical spondylosis. Now a day's neck pain, neck sprain, spondylosis have become significant issues related to the human body. The reduction of drag on the helmet will be a boon for society, which will reduce the force on the neck. The decrease in drag is an essential field of study. The drag force can be reduced by various methods like coating on the surface, modifying the helmet's shape, etc. The study's purpose is to decrease drag on the helmet by improving the helmet's shape. The CFD analysis is carried out to find the best profile of the helmet and fineness ratio of the boat-tailed helmet to minimize drag. The CFD results are validated with the wind tunnel laboratory outcomes. Based on the findings, a considerable reduction in the drag is accomplished at the velocity of 32.5 m/s.

Comparative study of electron temperature and excitation temperature in a magnetic pole enhanced-inductively coupled argon plasma

A.W. Khan,F. Jan,A. Saeed,M. Zaka-ul-Islam,M. Abrar,N.A.D. Khattak,M. Zakaullah 한국물리학회 2013 Current Applied Physics Vol.13 No.7

Magnetic Pole Enhanced-Inductively Coupled Plasmas (MaPE-ICPs) in analogy to the conventional ICPs exhibit two modes of operation, depending on the power coupling mechanism, i.e., a low power mode with dominant capacitive coupling (E-mode) and a high power mode with dominant inductive coupling (H-mode). A comparative study of the electron temperature measured by a Langmuir probe ðTLP e Þ and the electron excitation temperature ðTOES exc Þ determined by Optical Emission Spectroscopy (OES) is reported in the two distinct modes of a MaPE-ICP operated in argon. The dependence of TLP e , TOES exc and their ratio ðTLP e =TOES exc Þ on applied power (5-50 W) and gas pressure (15-60 mTorr) is explored, and the validity of TOES exc as an alternative diagnostic to TLP e is tested in the two modes of MaPE-ICP. The OES based noninvasive measurement of the plasma parameters such as electron temperature is very useful for plasma processing applications in which probe measurements are limited.

Hydraulic Oil Leakage through a Pressure Reducing Valve Spool

H. A. Khan(하룬 아흐마드 칸),E. A. Jeong(정은아),J. W. Park(박정우),J. H. Hun(정황훈),S. N. Yun(윤소남) 유공압건설기계학회 2021 유공압건설기계학회 학술대회논문집 Vol.2021 No.11

Power losses in a hydraulic system are intrinsically linked to leakage, which is unwanted in any application. Depending on the use, pressure regulating valves feature two or three ports. Prior research on leakage in oil-hydraulic pressure reducing valves has not been extensively done which makes this study more significant. A data processing system and pressure sensors were installed as part of the experimental equipment used to test the valve. The test results were recorded and evaluated. The steady-state leakage of the valve was measured using a stop watch and a beaker with volume markings. Because of the unreliability of flow sensors at extremely low flow rates, a more fundamental method of volume per time was used. The valve was controlled by a solenoid with a variable output pressure. The leakage properties for various output pressures were investigated.