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Influence of accelerated curing on the compressive strength of polymer-modified concrete

Frontiers of Structural and Civil Engineering 2022年第5期16卷 589-599页

作者： Izhar ahmad Kashif Ali KHAN tahir ahmad Muhammad ALAM Muhammad Tariq BASHIR College of Civil and Transportation Engineering Hohai UniversityNanjing 210098China Department of Civil Engineering Muslim Youth UniversityIslamabad 44000Pakistan Department of Civil Engineering CECOS University of IT&Emerging SciencesPeshawar 25000Pakistan Department of Civil Engineering University of Engineering&TechnologyMardan 23200Pakistan

In recent building practice,rapid construction is one of the principal ***,in designing concrete structures,compressive strength is the most significant of all *** 3-d and 7-d compressive strength reflects the strengths at early phases,the ultimate strength is *** effort has been made in this study to develop mathematical models for predicting compressive strength of concrete incorporating ethylene vinyl acetate(EVA)at the later ***-Smirnov(KS)goodness-of-fit test was used to examine distribution of the *** compressive strength of EVA-modified concrete was studied by incorporating various concentrations of EVA as an admixture and by testing at ages of 28,56,90,120,210,and 365 *** accelerated compressive strength at 3.5 hours was considered as a reference strength on the basis of which all the specified strengths were predicted by means of linear regression *** on the results of KS goodness-of-fit test,it was concluded that KS test statistics value(D)in each case was lower than the critical value 0.521 for a significance level of 0.05,which demonstrated that the data was normally *** on the results of compressive strength test,it was concluded that the strength of EVA-modified specimens increased at all ages and the optimum dosage of EVA was achieved at 16%***,it was concluded that predicted compressive strength values lies within a 6%difference from the actual strength values for all the mixes,which indicates the practicability of the regression *** research work may help in understanding the role of EVA as a viable material in polymer-based cement composites.

关键词： compressive strength prediction polymer-modified concrete linear regression fit early age strength ethylene vinyl acetate

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Hypsometric properties of mountain landscape of Hunza River Basin of the Karakoram Himalaya

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Journal of Mountain Science 2018年第9期15卷 1881-1891页

作者： BAIG Siddique Ullah tahir Adnan ahmad DIN ahmad KHAN Humaira High Mountain Research Center Development Studies COMSATS University Islamabad (Abbottabad Campus) Environmental Sciences COMSATS University Islamabad (Abbottabad Campus) Computer Sciences COMSATS University Islamabad (Abbottabad Campus)

Within Karakoram Himalaya, Hunza River Basin(study area) is unique for a number of reasons: 1) potential impacts of highly concentrated highpitched mountains and glacial ice; 2) the glaciated portions have higher mean altitude as compared to other glaciated landscapes in the Karakoram; 3) this basin occupies varieties of both clean and debriscovered glaciers and/or ice. Therefore, it is imperative to understand the stability of topographic surface and potential implications of fluctuating glacial-ice causing variations in the movement of material from higher to lower elevations. This paper advocates landscape-level hypsometric investigations of glaciated landscape lies between 2280–7850 m elevation above sea level and non-glaciated landscape between 1461–7570 m. An attempt is made to understand intermediate elevations, which disguise the characteristics of glaciated hypsometries that are highly correlated with the Equilibrium Line Altitude(ELA). However, due to data scarcity for high altitude regions especially above 5000 m elevation, literature values for climatic conditions are used to create a relationship between hypsometry and variations in climate and ELA. The largest glaciated area(29.22%) between 5047 to 5555 m lies in the vertical regime of direct snow-accumulation zone and in the horizontal regime of net-accumulation zone(low velocity, net freezing, and no-sliding). In both landscapes, the hypsometric curves are ‘slow beginning' followed by ‘steep progress' and finally reaching a ‘plateau', reflecting the rapid altitudinal changes and the dominance of fluvial transport resulting in the denudation of land-dwelling and the transport of rock/debris from higher to lower altitudes. Reported slight differences in the average normalized bin altitudes against the cumulative normalized area between glaciated and non-glaciated landscapes are an indicator of slightly different land-forms and landform changes.

关键词： Karakoram Hypsometry Glaciation Equilibrium Line Altitude

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Spatio-temporal changes in the six major glaciers of the Chitral River basin(Hindukush Region of Pakistan)between 2001 and 2018

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Journal of Mountain Science 2020年第3期17卷 572-587页

作者： Jawaria GUL Sher MUHAMMAD LIU Shi-yin Siddique ULLAH Shakeel ahmad Huma HAYAT Adnan ahmad tahir Department of Environmental Sciences COMSATS University Islamabad(CUI)Abbottabad Campus22060AbbottabadPakistan International Center for Integrated Mountain Development(ICIMOD) KathmanduNepal Institute of International Rivers and Eco-Security Yunnan UniversityKunmingChina Division of Environmental System Analysis School of EnvironmentTsinghua UniversityBeijing 100084 China

Glaciers in the northern Pakistan are a distinctive source of freshwater for the irrigation,drinking and industrial water supplies of the people living in those regions and downstream. These glaciers are under a direct global warming impact as indicated in many previous studies. In this study, we estimated the glacier dynamics in terms of Equilibrium Line Altitude(ELA), mass balance and the snout position variation using remote sensing data between 2001 and 2018. Six glaciers, having area≥ 20 km2 each, situated in the Chitral region(Hindukush Mountains) were investigated in this study. Digital Elevation Model(DEM) and available cloud-free continuous series of Landsat and Sentinel satellite images from minimum snow cover season were used to monitor the variability in the studied glaciers by keeping the status of glaciers in year 2001 as a reference. The annual climatic trends of mean temperature and total precipitation from Chitral weather station were detected using the nonparametric Mann-Kendall’s test. Results revealed a general increase in the ELA, decrease in the glacier mass balance and the retreat of snout *** upward shift in the ELA for the entire study area and data period was ~345 ± 93 m at a rate of^13 m.a-1 from the reference year’s position i.e.~4803 m asl. Estimated mean mass balance for the entire study area indicated a decline of-0.106 ± 0.295 m w.e. a-1. Periods of snout retreat and advance in different glaciers were found but the mean value over the entire study area was a retreat of-231 ± 140 *** obvious relationship was found between the glacier variation trends and the available gauged climatic data possibly due to the presence of debris cover in ablation zones of all the studied glaciers which provides insulation and reduces the immediate climatic effects.

关键词： Glacier dynamics Hindukush region Sentinel Landsat Mass balance Equilibrium Line Altitude Snout position

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Simulation of snowmelt-runoff under climate change scenarios in a data-scarce mountain environment

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International Journal of Digital Earth 2019年第8期12卷 910-930页

作者： Adnan ahmad tahir Samreen Abdul Hakeem Tiesong Hu Huma Hayat Muhammad Yasir Department of Environmental Sciences COMSATS Institute of Information TechnologyAbbottabadPakistan State Key Laboratory of Water Resources and Hydropower Engineering Sciences Wuhan UniversityWuhanPeople’s Republic of China

Pakistan is an agriculture-based economy and major proportion of irrigation water for its cultivated lands is abstracted from the Upper Indus Basin(UIB).UIB water supplies are mostly contributed from the high-altitude snow and glacier fields situated in the Hindukush–Karakoram–Himalayan *** change in the flows of these river catchments due to climate variability may result in the form of catastrophic events like floods and droughts and hence will adversely affect the economy of *** study aims to simulate snowmelt runoff in a mountainous sub-catchment(Shyok River basin)of the UIB under climate change *** Runoff Model(SRM)coupled with remotely sensed snow cover product(MOD10A2)is used to simulate the snowmelt runoff under current and future climate scenarios in the study *** results indicate that(a)SRM has efficiently simulated the flow in Shyok River with average Nash–Sutcliff coefficient value(R2)of 0.8(0.63–0.93)for all six years(2000–2006)of basin-wide and zone-wise simulations,(b)an increase of 10%(by 2050)and 20%(by 2075)in SCA will result in a flow rise of∼11%and∼20%,respectively,and(c)an increase of 1℃(by 2025),2℃(by 2050),3℃(by 2075)and 4℃(by 2100)in mean temperature will result in a flow rise of∼26%,∼54%,∼81%and∼118%,*** study suggests that SRM equipped with remotely sensed snow cover data is an effective tool to estimate snowmelt runoff in high mountain data-scarce environments.

关键词： Upper Indus Basin(UIB) Shyok River basin MOD10A2 Snowmelt Runoff Model(SRM) climate change

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Breast cancer therapy by laser-induced Coulomb explosion of gold nanoparticles

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Chinese Journal of Cancer Research 2013年第6期25卷 756-761页

作者： Muhammad Gul Bahar Ashiq Mohammad Alam Saeed Bashir ahmad tahir Noorddin Ibrahim Muhammad Nadeem Physics Department Universiti Teknologi Malaysia Department of Electrical and Computer Engineering McMaster University National Defense University of Malaysia

Objective： Laser-induced Coulomb explosion of gold nanoparticles for breast cancer has been studied by nanophotolysis technique. This study aimed to investigate whether laser-induced bubble formation due to Coulomb explosion can provide an effective approach for selective damage of breast cancer with gold nanoparticles. Method： Numerical method involves laser-induced Coulomb explosion of gold nanoparticles. Different parameters related to nanophotolysis such as laser fluence, tumor depth, cluster radius, laser pulse duration, and bubble formation is studied numerically. Numerical simulation was performed using Mat lab. Results： The gold nanopartieles of 10, 20, 30, 40, and 50 nm in radius could penetrate into tumor 1.14, 1.155, 1.189, 1.20 and 1.22 cm in depth respectively. The maximum penetration depth in tumor could be obtained with nanoparticles of 50 nm radius. Short laser pulse of 40 ns with nanoparticles of 10 nm radius could penetrate into tumor 1.14 cm in depth. Bubbles with a radius of 9 pm could effectively kill breast cancer cells without damaging healthy ones. The bubble radius increased from 4 to 9 lam with an increase in pulse duration in the range of 10 to 30 ns. Conclusions： Gold nanoparticles with increasing radius and bubble formation for selective damage of breast cancer cells are successfully probed. The present calculated results are compared with other experimental findings, and good correlation is found between the present work and previous experimental values. It was demonstrated that bubble formation in tumor may further increase the efficacy of breast cancer treatment.

关键词： Gold nanoparticles tumor depth nanophotolysis bubble formation breast cancer

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A 37 GHz Millimeter-Wave Antenna Array for 5G Communication Terminals

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Computers, Materials & Continua 2023年第4期75卷 1317-1330页

作者： Jalal Khan Sadiq Ullah Usman Ali Ladislau Matekovits Farooq ahmad tahir Muhammad Inam Abbasi Telecommunication Engineering Department University of Engineering and TechnologyMardan23200Pakistan Department of Electronics and Telecommunications Politecnico di TorinoTurin10129Italy Istituto di Elettronica e di Ingegneria Dell’Informazione e Delle Telecomunicazioni National Research Council of ItalyTurin10129Italy Department of Measurements and Optical Electronics Politehnica University TimisoaraTimisoara300006Romania Research Institute for Microwave and Millimeter-Wave Studies(RIMMS) National University of Sciences and Technology(NUST)Islamabad44000Pakistan Department of Electronics and Computer Engineering Technology(JTKEK) Faculty of Electrical and Electronic Engineering Technology(FTKEE)Universiti Teknikal Malaysia Melaka(UTeM)Hang Tuah JayaDurian TunggalMelaka76100Malaysia

This work presents,design and specific absorption rate(SAR)analysis of a 37GHz antenna,for 5th Generation(5G)*** proposed antenna comprises of 4-elements of rectangular patch and an even *** radiating element is composed of copper material supported by Rogers RT5880 substrate of thickness,0.254 mm,dielectric constant(εr),2.2,and loss tangent,*** 4-elements array antenna is compact in size with a dimension of 8mm×20mm in length and *** radiating patch is excited with a 50 ohms connector i.e.,*** antenna resonates in the frequency band of 37 GHz,that covers the 5G *** antenna behavior is studied both in free space and in the proximity of the human *** models of the human body,i.e.,belly,hand,and head(contain skin,fat,muscles,and bone)are considered for on-body *** resonant frequency,the antenna gives a boresight gain of 11.6 *** antenna radiates efficiently with a radiated efficiency of more than 90%.Also,it is observed that the antenna detunes to the lowest in the proximity of the human body,but still a good impedance matching is achieved considering the−10 dB ***,SAR is also being *** safe limit of 2 W/kg for any 10 g of biological tissue,specified by the European International Electro Technical Commission(IEC)has been *** calculated values of SAR for human body models,i.e.,belly,hand and head are 1.82,1.81 and 1.09 W/kg,*** SAR values are less than the international recommendations for the three ***,the simulated and measured results of the antenna are in close agreement,which makes it,a potential candidate for the fifth-generation smart phones and other handheld devices.

关键词： 5G antenna array SAR millimeter-wave smart phones

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The Development and Characterization of Zirconia-Silica Sand Nanoparticles Composites

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World Journal of Nano Science and Engineering 2011年第1期1卷 7-14页

作者： tahir ahmad Othman Mamat 不详

The present study aims to develop zirconia-Silica sand nanoparticles composites through powder processing route and to study the physical properties, mechanical properties and microstructure of the composites. Zirconia based silica sand nanoparticles composite with 5, 10, 15 and 20 wt.% were developed through powder processing technique and sintered at 1500 ℃ for two hours. A decreasing trend of green density however an improvement in sintered density was observed. Also the addition of silica sand nanoparticles with 20 wt.% increased the hardness up to 12.45 GPa and microstructures indicated the diffusion mechanism of silica sand nanoparticles into pore sites of the composites.

关键词： Zirconia-Silica Sand Nanoparticles Composites Physical Properties Mechanical Properties Microstructures

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Remote Sensing Data Application to Monitor Snow Cover Variation and Hydrological Regime in a Poorly Gauged River Catchment—Northern Pakistan

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International Journal of Geosciences 2014年第1期5卷 27-37页

作者： Samreen Abdul Hakeem Muhammad Bilal Arshid Pervez Adnan ahmad tahir Department of Environmental Sciences COMSATS Institute of Information Technology Abbottabad Pakistan

Snow- and glacier-nourished river basins located in the Himalaya-Karakoram-Hindukush (HKH) ranges supply a significant amount of discharge in River Indus upstream Tarbela Dam. It is, hence, important to comprehend the cryosphere variation and its relationship to the stream flow in these high-altitude river catchments. The MODIS remotely sensed database of snow products was chosen to examine the average annual snow and glacier cover (cryosphere) variations in the Shigar River basin (poorly gauged mountainous sub-catchment of the Indus River). Hydrological regime in the area was investigated through monthly database of observed stream fluxes and climate variables (precipitation and mean temperature) for the Shigar River catchment. Analysis indicated the usefulness of remote sensing techniques for estimation of the snow cover variation in the poorly or un-gauged high-elevation catchments of the HKH zone. Results also showed that Shigar River discharge was influenced mainly by the seasonal and annual snow cover area (SCA) variation and the temperature seasonality. Moreover, it is important to uncover such inter-relationship of stream flow, climate variables and snow cover in the poorly gauged high-altitude catchments of Karakoram region for better water resource management and accurate flood hazards predictions at Tarbela.

关键词： Shigar River Basin Satellite Remote Sensing MODIS Snow Products Water Resources Management ASTER-GDEM

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Erratum to:Spatio-temporal changes in the six major glaciers of the Chitral River basin(Hindukush Region of Pakistan)between 2001 and 2018

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Journal of Mountain Science 2020年第8期17卷 2048-2048页

作者： Jawaria GUL Sher MUHAMMAD LIU Shi-yin Siddique ULLAH Shakeel ahmad Huma HAYAT Adnan ahmad tahir Department of Environmental Sciences COMSATS University Islamabad(CUI)Abbottabad Campus22060AbottabadPakistan International Center for Integrated Mountain Development(ICIMOD) KathmanduNepal Institute of International Rivers and Eco-Security Yunnan UniversityKunmingChina Division of Environmental System Analysis School of EnvironmentTsinghua UniversityBeijing 100084 China

The article Spatio-temporal changes in the six major glaciers of the Chitral River basin(Hindukush Region of Pakistan)between 2001 and 2018,written by Jawaria GUL,Sher MUHAMMAD,LIU Shi-yin,Siddique ULLAH,Shakeel ahmad,Huma HAYAT and Adnan ahmad tahir,was originally published Online First without Open *** publication in volume 17,issue 3,page 572-587,the author decided to opt for Open Choice and to make the article an Open Access ***,the copyright of the article has been changed to C The Author(s)2020 and the article is forthwith distributed under the terms of the Creative Commons Attribution 4.0 International License(http://***/licenses/by/4.0/),which permits use,duplication,adaptation,distribution and reproduction in any medium or format,as long as you give appropriate credit to the original author(s)and the source,provide a link to the Creative Commons license,and indicate if changes were *** original version of this article has been revised due to a retrospective Open Access order.

关键词： Open Region license

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Extracting Eye Models from MRI Scans Using U-Net-Based Deep Learning Framework

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Journal of Computer and Communications 2024年第11期12卷 95-107页

作者： Waqar ahmad tahir Opeyemi Sheu Alamu Dip Sarker Md Tafhimul Haque Sadi Abdullah Al Hasib Tonmoy Kumar Sarker Md Rakibul Islam Dipankar Roy Dip Ashish Sharma Syed Wajeeh Abbas Rizvi Department of Internal Medicine/Casualty Khalifa Gull Nawaz Teaching Hospital Bannu Pakistan Department of Statistics Federal College of Animal Health and Production Technology Ibadan Nigeria Department of Computer Science American International University-Bangladesh Dhaka Bangladesh Department of Internal Medicine Arogya Hospital Pvt. Ltd. Baglung Nepal Department of Data Science National University of Computer & Emerging Sciences (FAST City Campus) Karachi Pakistan

.Abstracting eye models from MRI images is critical in advancing medical imaging, particularly for clinical diagnostics. Current methods often struggle with accuracy and efficiency, highlighting a gap this research aims to fill. This study investigates the application of machine learning methods, focusing on the U-net-based deep learning framework, to improve the accuracy of eye model extraction. The objectives include fitting measured eye data to models such as the Ellipsoid model, evaluating automated segmentation tools, and assessing the usability of machine learning-based extractions in clinical scenarios. We employed point cloud data of 202,872 points to fit eye models using ellipsoid, non-linear, and spherical fitting techniques. The fitting processes were optimized to ensure precision and reliability. We compared the performance of these models using mean squared error (MSE) as the primary metric. The non-linear model emerged as the most accurate, with a significantly lower MSE (1.186562) compared to the ellipsoid (781.0542) and spherical models. This finding indicates that the non-linear model provides a more detailed and precise representation of the eye’s geometry. These results suggest that machine learning methods, particularly non-linear models, can significantly enhance the accuracy and usability of eye model extraction in clinical diagnostics, offering a robust framework for future advancements in medical imaging.

关键词： Eye Model Extraction U-Net Deep Learning MRI Segmentation Ellipsoid and Non-Linear Models Mean Squared Error(MSE)

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