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395 results on '"Ullah, Nasim"'

2. Expert knowledge-based peak current mode control of electrosurgical generators for improved output power regulation

Author

Rafiq Muhammad Mohsin, Ibeas Asier, and Ullah Nasim

Subjects
electro-surgery, tissue burning, tissue impedance, peak current mode control, expert knowledge control, Medicine (General), R5-920
Abstract

Electrosurgical generators (ESG) are widely used in medical procedures to cut and coagulate tissue. Accurate control of the output power is crucial for surgical success, but can be challenging to achieve. In this paper, a novel expert knowledge-based peak current mode controller (EK-PCMC) is proposed to regulate the output power of an ESG. The EK-PCMC leverages expert knowledge to adapt to changes in tissue impedance during surgical procedures. We compared the performance of the EK-PCMC with the classical peak current mode controller (PCMC) and fuzzy PID controller. The results demonstrate that the EK-PCMC significantly outperformed the PCMC, reducing the integral square error (ISE) and integral absolute error (IAE) by a factor of 3.88 and 4.86, respectively. In addition, the EK-PCMC outperformed the fuzzy PID controller in terms of transient response and steady-state performance. Our study highlights the effectiveness of the proposed EK-PCMC in improving the regulation of the output power of an ESG and improving surgical outcomes.

Published
2023
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6. An Advanced Two-Stage Grid Connected PV System: A Fractional-Order Controller

Author

Fahad, Shah, Ullah, Nasim, Mahdi, Ali Jafer, Ibeas, Asier, and Goudarzi, Arman

Subjects
Electrical Engineering and Systems Science - Systems and Control
Abstract

A fractional-order (FO) based controller for a grid-connected PV system is presented in this paper. A single phase two-stage grid-connected photovoltaic generator (PVG) is used to test the performance of the FO controller. The main objectives of the proposed controller are: (1) To regulate the output voltage of PVG at a point where the maximum power is drawn. (2) Constant DC-link voltage control. (3) Power factor control (PFC) at the inverter output with low total harmonic distortion (THD). To solve the first problem, a non-linear control method known as fractional-order back-stepping control (FOBSC) is used to regulate the output voltage of PVG. A maximum power point tracking (MPPT) technique known as perturb and observe (P & O) is used to generate a reference voltage which is suitable for tracking the maximum power generation of PVG. The generated reference is used to regulate the output voltage of PVG using FOBSC. The DC-link voltage fluctuation issue is tackled using FO based PI controller. The last objective is achieved using FOBSC to obtain maximum power factor of the grid. Lyapunov candidate function is used to verify the stability of the system. To test the performance of the proposed controller, it is compared to conventionally known Integer-order (IO) controller. Results have shown a significant improvement in THD and efficiency of the system. The proposed controller offers 0.94%, 1.43% and 1.86% lower THD in comparison with IO controller at 100%, 80% and 70% of the power generation capacity of PVG, respectively. The overall efficiency of the system for 100%, 80%, and 70% of the dynamic powers of the system is noticed to be better in case of FO controller.

Published
2020

18. The important contribution of renewable energy technologies in overcoming Pakistan's energy crisis: Present challenges and potential opportunities.

Author

Asghar, Rafiq, Sulaiman, Mohd H, Mustaffa, Zuriani, Ullah, Nasim, and Hassan, Waqas

Subjects
RENEWABLE energy sources, ENERGY shortages, ENERGY development, ENERGY consumption, ENERGY infrastructure, RENEWABLE energy standards
Abstract

In recent years, the environmental and economic consequences of coal, gasoline and other conventional energy sources have been widely discussed. Currently, Pakistan's energy output is highly dependent on these resources; as a consequence, the country is facing a severe energy crisis. The government spends more than $3.7 billion annually on fossil fuel imports, which has a significant impact on an already vulnerable economy. Moreover, the country is ranked as the seventh-most impacted region by climate change, making it critical for the government to take proactive measures. Renewable energy that is both economical and sustainable will become a realistic and viable choice for satisfying Pakistan's current and future energy demands. This article provides a detailed overview of Pakistan's long-standing energy scarcity concerns and discusses the country's current renewable energy challenges and opportunities. Additionally, Pakistan's efforts in the realm of renewable energy are compared to those of other Asian nations in order to understand how these countries are advancing renewable energy sources. Numerous statistics show that despite government initiatives, the amount of power generated from renewable sources falls short of the Indicative Generation Capacity Expansion Plan's (IGCEP's) 2025 and 2030 targets. Achieving these aspirational targets will require competent policies, incentives, technological expertise and substantial political and financial commitments. Hence, this article also advised policymakers and city municipalities on how to enhance energy infrastructure, knowledge and the capacity for overcoming future challenges. In contrast, the development of renewable energy in Pakistan has been an extremely successful endeavour, but an effective and efficient approach is necessary to leverage the benefits of rapid progress. [ABSTRACT FROM AUTHOR]

Published
2023
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28. Toward Optimal Softcore Carry-aware Approximate Multipliers on Xilinx FPGAs.

Author

AWAIS, MUHAMMAD, ZAHIR, ALI, ALI SHAH, SYED AYAZ, REVIRIEGO, PEDRO, ULLAH, ANEES, ULLAH, NASIM, KHAN, ADAM, and ALI, HAZRAT

Subjects
GATE array circuits, BIT error rate, SIGNAL processing, IMAGE processing, MACHINE learning, FIELD programmable gate arrays
Abstract

Domain-specific accelerators for signal processing, image processing, and machine learning are increasingly being implemented on SRAM-based field-programmable gate arrays (FPGAs). Owing to the inherent error tolerance of such applications, approximate arithmetic operations, in particular, the design of approximate multipliers, have become an important research problem. Truncation of lower bits is a widely used approximation approach; however, analyzing and limiting the effects of carry-propagation due to this approximation has not been explored in detail yet. In this article, an optimized carry-aware approximate radix-4 Booth multiplier design is presented that leverages the built-in slice look-up tables (LUTs) and carry-chain resources in a novel configuration. The proposed multiplier simplifies the computation of the upper and lower bits and provides significant benefits in terms of FPGA resource usage (LUTs saving 38.5%–42.9%), Power Delay Product (PDP saving 49.4%–53%), performance metric (LUTs × critical path delay (CPD) × PDP saving 68.9%– 73.1%) and errors (70% improvement in mean relative error distance) compared to the latest state-of-the-art designs. Therefore, the proposed designs are an attractive choice to implement multiplication on FPGA-based accelerators. [ABSTRACT FROM AUTHOR]

Published
2023
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38. Numerical Investigation of Photo-Generated Carrier Recombination Dynamics on the Device Characteristics for the Perovskite/Carbon Nitride Absorber-Layer Solar Cell

Author

Saeed, Faisal, primary, Haseeb Khan, Muhammad, additional, Tauqeer, Haider Ali, additional, Haroon, Asfand, additional, Idrees, Asad, additional, Shehrazi, Syed Mzhar, additional, Prokop, Lukas, additional, Blazek, Vojtech, additional, Misak, Stanislav, additional, and Ullah, Nasim, additional

Published
2022
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