Study on failure mechanism of multi-storeyed reinforced concrete framed structures

Ahmed, Irfan,Sheikh, Tariq Ahmad,Gajalakshmi, P.,Revathy, J. Techno-Press 2021 Advances in computational design Vol.6 No.1

Failure of a Multi-storeyed reinforced concrete framed structure occurs when a primary vertical structural component is isolated or made fragile, due to artificial or natural hazards. Load carried by vertical component (column) is transferred to neighbouring columns in the structure, if the neighbouring column is incompetent of holding the extra load, this leads to the progressive failure of neighbouring members and finally to the failure of partial or whole structure. The collapsing system frequently seeks alternative load path in order to stay alive. One of the imperative features of collapse is that the final damage is not relative to the initial damage. In this paper, the effect on the column and beam adjacent to statically removed vertical element in terms of axial force, shear force and bending moment is investigated. Using Alternate load path method, numerical modelling of two dimensional one bay, two bay with variation in storey heights are analysed with FE model in order to obtain better understanding of failure mechanism of multi-storeyed reinforced concrete framed structure. The results indicate that the corner column is more susceptible to progressive collapse when compared to middle column, using this simplified methodology one can easily predict how the structure can be made to stay alive in case of sudden failure of any horizontal or vertical structural element before designing.

Emerging Trends of Financial Markets Integration: Evidence from Pakistan

Ahmed, Irfan Korea Distribution Science Association 2014 The Journal of Asian Finance, Economics and Busine Vol.1 No.1

This study investigates extensively the integration of various segments of financial markets (i.e. money market, lending and deposit market, exchange rate market, and capital market) both domestically and internationally. Cointegration approach is employed in the study to find out long term relationship among the variables. Data are on a monthly interval for the period spreads over 2001 to 2010. The results show no evidence of cointegration between money market and exchange rate market and between capital market and exchange rate market of Pakistan. On the other hand, international financial markets integration is also investigated and the findings revealed that domestic money market rates of Pakistan and USA are not cointegrated. Whereas, an evidence of cointegration between capital markets of Pakistan and USA is found in this study.

Indigenous Radiosynthesis of [131I]Iodobenzylguanidine ([131I]mIBG) for Neuroblastoma Imaging

Nadeem Ahmed Lodhi,Muhammad Irfan,Muhammad Nasir Saddique,Kahkshan Bashir Mir,Naseer Ahmed,Shazia Fatima,Mumtaz Khan,Muhammad Wasim,Samina Roohi 대한방사성의약품학회 2022 Journal of radiopharmaceuticals and molecular prob Vol.8 No.2

Indigenous diagnostic dose of 131I-labeled meta-iodobenzylguanidine ([131I]mIBG) was prepared via Cu+ catalyzed isotope exchange reaction generated in situ by sodium metabisulfite for imaging of neuroblastoma tumor. [131I]mIBG was produced in overall 85-90% radiochemical yield. The average amount of radioactivity of [131I]mIBG was 2164 MBq (1998-2331MBq) with an average specific activity > 1000 MBq/mg at the end of synthesis. The radiochemical purity was ≥ 99.9% after purification through Dowex-1 × 8 ion exchange resin (100-150 mesh) at the date of preparation. The stability of [131I]mIBG at concentration 480-555 MBq/mL was > 97% at 4 °C after 4 days. The room temperature (25 °C) stability of [131I]mIBG was > 98% after 24 h. Biodistribution of [131I]mIBG in patient showed uptake in salivary glands, liver, spleen and excreted though urinary bladder. Neuroendocrine medicated uptake into tumor lesion and metastatic sites were noted which strongly correlate with the morphological abnormalities of patient.

Influence of Financial Literacy and Educational Skills on Entrepreneurial Intent: Empirical Evidence from Young Entrepreneurs of Pakistan

Muhammad Ahmed BILAL,Hadi Hassan KHAN,Muhammad IRFAN,S.M. Nabeel Ul HAQ,Manzoor ALI,Ali KAKAR,Wahab AHMED,Abdul RAUF 한국유통과학회 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.1

This paper attempts to study the impact of Financial Literacy on Youth Entrepreneurial Intent in Pakistan. A closed-ended self-administered structured questionnaire covering financial literacy, computer knowledge, financial attitude, and financial knowledge with Entrepreneurial Intent was collected from young entrepreneurs. The research tried to investigate the education level with computer skill to inspect the effect of financial literateness on young generation Entrepreneurial Intent in the context of Pakistan. The research model was tested using PLS-SEM and authenticating a measurement model through the advanced methodology and their association with Entrepreneurial Intent. Results revealed that financial literacy and its two parts (financial attitude and financial knowledge) have a positive impact on Entrepreneurial Intent. The size of the joint impact of financial literacy and its components on Entrepreneurial Intent was assessed to be adequate. Entrepreneurial Intent is essential for creating new firms to maintain economic development. Furthermore, it is determined in this research that if youth has better financial knowledge and financial attitude, the probability of Entrepreneurial Intent increases. This suggests that if the youth in Pakistan desire to attain a higher limit of Entrepreneurial Intent, they must implement financial literacy models for enhancing and promoting their current Entrepreneurial Intent.

Analysis and design of flux cancellation power-decoupling method for electrolytic-capacitorless three-phase cascaded multilevel inverters

Irfan, Mohammad Sameer,Tawfk, Mohamed Atef,Ahmed, Ashraf,Park, Joung-Hu The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.2

Cascaded multilevel inverter cells produce double-grid frequency ripples that require a large electrolytic capacitor bank for every cell, resulting in reduced system reliability and lifespan. This paper proposes a new generalized power-decoupling methodology that is applicable to any three-phase cascaded multilevel inverter topology. The proposed flux cancellation method is based on forcing a three-phase double-frequency ripple into the core of a three-phase transformer. The flux components from each phase, which are phase-shifted by 120°, cancel each other inside the core. Therefore, no power-decoupling capacitor is required in this method. A three-port bidirectional isolated converter is proposed to cancel the three-phase 120 Hz pulsating power in a single high-frequency (HF) core. High-leakage inductances and imbalances among the ports of a HF transformer are a topographical challenge. The imbalance in leakage inductances can be reduced by improving the winding schemes. However, increased leakage and imbalance among the three ports are unavoidable under high voltages because of the need for higher isolation. A universal solution involves the application of a phase shift-based controller to obtain balanced and reduced voltage ripples among the three DC links. This paper presents the dynamic analysis and controller design procedure. Results of the prototype hardware confirm the suitability of the proposed power-decoupling methods.

Evaluation of Risk Factors Causing Cost Overrun in Road Projects in Terrorism Affected Areas Pakistan – a Case Study

Irfan Zafar,Tashfeen Yousaf,Sarfraz Ahmed 대한토목학회 2016 KSCE Journal of Civil Engineering Vol.20 No.5

The risks and uncertainties inherent to the construction industry are more than any other industry and this industry exhibits poor management of these risks. Hence, many projects fail to meet time schedules and budget targets. Transport sector is an important part of the construction industry and is vital to its growth. However this sector has been severely affected by delayed completion of the projects with exceeded cost. These issues are more pronounced in terrorism affected areas around the world, predominantly in Pakistan, Afghanistan and Iraq. Evaluation of Risk Factors Causing Cost Overrun in Road Projects in Terrorism Affected Areas: Pakistan - a Case Study. Pakistan being top ranked terrorism affected country among 85 terrorist affected countries around the world in 2012, has been taken as case study. In Pakistan, Federally Administrated Tribal Area (FATA) being the recipient of max casualties in 2012 is the focus of the study. After 9/11, FATA received maximum share of development projects especially road infrastructure however, these projects could not fulfill their desired purpose due to lack of evaluation of risks associated with the dynamics and culture of that area resulting in severe cost overrun of these projects. This study presents the mechanism to identify the key risk factors contributing to the failure of achieving budget targets of road projects in FATA and suggests measures to overcome them. The study is undertaken via a questionnaire based survey comprising of 18 cost overrun risk factors which were ranked using their mean weightage. Analysis of the results show that non-availability of suitable contractors, project location within FATA, idling cost of plant and equipment due to security threats, differing site conditions in a project and inaccurate survey and site investigation due to security threat were major factors responsible for cost overrun. Moreover, responsibility among the stakeholders for these risks was also established. The results of the study warrant adoption of proactive measures for effective management of these risks by owner, consultants and contractors to avoid budget escalation in road construction projects in terrorism affected area around the world.

Current-Sensorless Power-Decoupling Phase-Shift Dual-Half-Bridge Converter for DC–AC Power Conversion Systems Without Electrolytic Capacitor

Irfan, Mohammad Sameer,Ahmed, Ashraf,Park, Joung-Hu,Seo, Chulhun Institute of Electrical and Electronics Engineers 2017 IEEE transactions on power electronics Vol. No.

<P>In this paper, a novel DHB power-decoupling control scheme without current sensor is proposed for single-phase inverters. As electrolyte capacitors are conventionally used; however, these capacitors limit ripple current capability and circuit reliability. Film capacitors improve the ripple current capability, size reduction, and circuit reliability. Conventionally, non-isolated topologies are used for power decoupling. The volume of the decoupling capacitor per unit energy in isolated bidirectional power decoupling topologies is reduced as compared to nonisolated due to unrestricted voltage across the decoupling capacitor. Voltage-fed Phase-Shift Dual Half-Bridge (DHB) is preferred with film capacitors as it has the least number of components in isolated bidirectional topologies. However, in DHB, power decoupling controller is a challenge as current control is conventionally required. The challenge has been overcome with novel current-sensorless dc link ripple rejection control. The controller has the advantage of current-sensorless configuration especially when it needs information from inverter phase-lock-loop (PLL). The proposed power decoupling control scheme is independent of the inverter control and universal. A new dynamic analysis has been carried out by taking into account the input-voltage dynamics. The advantage of the DHB is that it has single pole behavior and, hence, sufficient bandwidth can be obtained. Simulations and experiments have been performed to verify the analysis of the power decoupling control scheme and the capability of film-capacitor DHB for power decoupling.</P>

Enhancement in Isolation among Collinearly Placed Microstrip Patch Antenna Arrays

Irfan Ali, Tunio,Hernan, Dellamaggiora,Umair, Saeed,Ayaz Ahmed, Hoshu,Ghulam, Hussain International Journal of Computer ScienceNetwork S 2023 International journal of computer science and netw Vol.23 No.1

Strong surface waves among collinearly arranged patch antenna arrays pose unwanted inter element coupling particularly when high permittivity dielectric materials are used. In order to avert those waves, a novel Defected Ground Structure (DGS) is carved out systematically between two E-plane patch antenna elements. The introduced low profile μ shaped structure consequently improves impedance bandwidth and reflection coefficient by suppressing surface waves considerably. Parametric simulation results are analyzed and discussed.

A Cascaded-Boost Topology for Electrolyte-less Power Conditioning System Suitable for PV Residential Applications

Ashraf Ahmed,Mohammad Irfan,Joung-hu Park 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

Single-phase inverters need large bulk DC link electrolyte capacitors which reduce the life time of the converter circuit. Furthermore, there is a safety need for low input voltage in photovoltaic (PV) residential applications. A new cascaded power-decoupling topology is proposed in this paper with film capacitors and high step-up ratio. The topology is based on cascaded double boost; the output of the source side boost (the auxiliary DC link) is free to oscillate in double frequency of the AC output around a controlled average voltage. Besides, the second boost controls the main DC-link voltage within a demanded ripple range. A detailed design procedure of the topology is proposed, followed by transient analysis and controller design. Finally, the proposed circuit will be verified by simulation and experimental results.

Qualitative Comparisons of Several Image Dehazing Techniques

Jameel Ahmed Khan,Irfan Riaz,Jingchun Piao,Yawar Rehman,Hyunchul Shin 대한전자공학회 2017 대한전자공학회 학술대회 Vol.2017 No.1