| 1. |
- khan, Imran, et al.
(författare)
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Remotely Controlled Laboratory Setup for Active Noise Control and Acoustic Experiments
- 2012
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Ingår i: 2012 9th International Conference on Remote Engineering and Virtual. - Bilbao : IEEE. - 9781467325424 - 9781467325400
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Konferensbidrag (refereegranskat)abstract
- This paper presents a remotely controlled educational experiments setup for Active Noise Control (ANC) and acoustic experiments. The experiments setup is based on the Virtual Instruments Systems in Reality (VISIR) open source platform, National Instruments LabVIEW software and a Digital Signal Processor TMS320C6713 from Texas Instruments. The software development and equipment are controlled remotely form a client PC using a standard web browser. The proposed laboratory setup focuses on ANC experiments applied to noise in a ventilation duct. The laboratory setup will enable students to test and investigate properties and behaviour of adaptive algorithms in reality as compared to more confined simulations usually carried out in Matlab etc. The general steps in ANC, such as the feasibility of active control, designing, testing and debugging ANC algorithms, configuration and implementation of an active control system, are all covered. In addition students will be able to study the effect of analog to digital converters (ADC), anti-aliasing filters, digital to analog converters (DAC) and reconstruction filters using digital signal processing in reality, etc. The laboratory setup is suitable for a wide range of courses such as sound related experiments in upper secondary school physics, digital signal processing, adaptive signal processing, and acoustics at university level.
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| 2. |
- Subhan, Sidra, et al.
(författare)
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Fabrication of MnO2 NPs incorporated UiO-66 for the green and efficient oxidative desulfurization and denitrogenation of fuel oils
- 2021
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Ingår i: Journal of Environmental Chemical Engineering. - : Elsevier. - 2213-3437. ; 9:3
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Tidskriftsartikel (refereegranskat)abstract
- In this study, Manganese oxide nanoparticles (MnO2 NPs) are deposited over Zr-based UiO-66 molecular organic framework (MOF) resulting in MnO2/UiO-66 composite which is oxidized with NaClO for the catalytic oxidative desulfurization and denitrogenation of fuel oil. The as-synthesized composites were characterized via FE-SEM, EDX, BET, XPS and FT-IR techniques which confirmed the uniform deposition of MnO2 NPs and resulted in increased surface area and average mesoporous volume of pristine UiO-66. Catalytic results showed that MnO2/UiO-66 oxidized 2000 ppm of DBT (347 ppm Sulfur) and pyridine (502.8 ppm Nitrogen) in 3 min at O/S and O/N of 4, 0.06 g/15 mL catalyst dose and 25 °C. The mechanism behind the super-fast and highly efficacious performance of MnO2/UiO-66 is the ideal synergy among Mn4+, Zr4+ and NaClO species, which produced strong oxidizing •OH and •O2− radicals. Under the optimized reaction parameters, much higher removal of DBT and pyridine (100%) was achieved as compared to those of BT, 4,6-DMDBT, indole, and carbazole up to 6th cycles. This study provided important oxidant-catalyst system i.e. MnO2/UiO-66-NaClO for the highly efficacious, super-fast, and time and cost-effective alternative to the large scale oxidative desulfurization and denitrogenation of fuel oils.
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| 3. |
- Abdulaziz, Mohammed, et al.
(författare)
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A Cellular Receiver Front-End with Blocker Sensing
- 2016
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Ingår i: IEEE Radio Frequency Integrated Circuits Symposium (RFIC), 2016. - 9781467386517
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Konferensbidrag (refereegranskat)abstract
- A receiver front-end supporting contiguous and non-contiguous intra-band carrier aggregation scenarios with a fully integrated spectrum sensor that can detect both in-gap and out-of-band blockers has been implemented in 65nm CMOS technology. An NF of 2.5dB is achieved using a noise canceling LNTA, and linearized OTAs are used to achieve an IIP3 improvement of up to 6.5dB in-band and 11dB at the filter band edge. The spectrum sensor can detect blocker levels in 22 steps of 9MHz between -100MHz and 100MHz IF. The system consumes between 36.6mA and 57.6mA from a 1.2V supply.
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| 4. |
- Abdulaziz, Mohammed, et al.
(författare)
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A Linearization Technique for Differential OTAs
- 2017
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Ingår i: IEEE Transactions on Circuits and Systems II: Express Briefs. - 1549-7747. ; 64:9, s. 1002-1006
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Tidskriftsartikel (refereegranskat)abstract
- This brief presents an operational transconductance amplifier (OTA) linearization technique that is applied to a low-noise amplifier (LNA) and an OTA-C filter. Simulations show the effectiveness of the proposed technique on the LNA, whose noise and gain performance remain unaffected while the linearity is significantly improved. Measurements of the 80-MHz fourth order Butterworth OTA-C filter are also presented. It is implemented using six OTAs instead of eight, thus reducing the power consumption and area. The filter is implemented in 65-nm low-power CMOS, with a core area of 0.05 mm 2 and consumes 12.6 mA from 1.2 V supply. The measured in-band noise voltage is below 42 nV/ Hz‾‾‾√ , and the measured third order intercept point improvement using OTA linearization is up to 17 dB in-band and about 3 dB out-of-band. Supply and temperature variation measurements on three samples show that the linearization is effective without a need for bias adjustment.
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| 5. |
- Ahmad, Naveed, et al.
(författare)
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Relationship between corporate social responsibility at the micro-level and environmental performance : The mediating role of employee pro-environmental behavior and the moderating role of gender
- 2021
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Ingår i: Sustainable Production and Consumption. - : Elsevier BV. - 2352-5509. ; 27, s. 1138-1148
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Tidskriftsartikel (refereegranskat)abstract
- Since Pakistan is vulnerable to changing climatic conditions, the country needs emergency measures at every level to mitigate their effect. Many studies have addressed Corporate Social Responsibility (CSR) at the macro or institutional level, but its effect at the micro-level is largely ignored in the contemporary literature. The present study aims at filling this gap by highlighting the role of micro-level CSR on Environmental Performance (ENP) and how it is influenced by employees’ pro-environmental (PEB) behavior and gender. This study has been carried out in the context of deteriorating environmental conditions, scarce CSR activities and a male dominant society. Data were collected through a self-administered questionnaire targeting the manufacturing and the service sectors of Pakistan and analyzed through the structural equation modeling technique, using AMOS and SPSS software. The results of this study confirm that micro-level CSR initiatives directly (β = 0.39⁎⁎) and indirectly (β = 0.031⁎⁎) influence the environmental performance of an organization by means of employees’ PEB. A conditional indirect gender effect on this interaction was also observed, with women (β =0.17⁎⁎) exerting a stronger effect than men (β = 0.031⁎⁎). These findings may be helpful for policymakers involved in environmental management: It is possible to reduce the environmental footprint of Pakistan's organizations by encouraging employee's PEB and particularly by actively involving women which are systematically set apart from decision making in Pakistan.
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| 6. |
- Ahmad, Waqas, et al.
(författare)
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A Fully Integrated 26dBm Linearized RF Power Amplifier in 65nm CMOS Technology
- 2015
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Konferensbidrag (refereegranskat)abstract
- In this paper, design and measurements of a fully integrated power amplifier (PA) are presented. The PA consists of two amplifying chains each having a driver and a power stage. A low loss on chip power combiner combines the outputs from two amplifying chains, and also performs impedance transformation and differential to single-ended conversion. To linearize the PA, the driver stage is biased in class-C, acting as a pre-distorter for the power stage which is biased in class-AB. The linearization scheme is validated by measurements, improving the third order intermodulation distortion (IMD3) by 7dB, output referred 1-dB compression point by 4dB, and adjacent channel leakage ratio (ACLR) by 4.5 dB. With a supply voltage of 2.2V, the PA delivers a saturated output power of 26.1 dBm with a power added efficiency (PAE) of 26.8% at operating frequency of 2.24 GHz. The measured power gain of the PA is 21.8 dB, and the output referred 1-dB compression point is 25.4 dBm. The ACLR1 (5 MHz offset) is better than -33 dBc while transmitting a 23dBm WCDMA signal. The circuit is manufactured in a standard 65nm CMOS process and occupies 1mm 2 of chip area.
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| 7. |
- Ahmad, Waqas, et al.
(författare)
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A Fully Integrated Radio-Fiber Interface in 65 nm CMOS Technology
- 2014
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Ingår i: IEEE Photonics Technology Letters. - 1041-1135. ; 26:5, s. 444-446
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Tidskriftsartikel (refereegranskat)abstract
- In this work we present a fully integrated Radio-Fiber interface implemented in 65nm CMOS, intended for remote antenna units (RAUs) in distributed antenna systems. To relax the requirements on the optical components, an intermediate frequency (IF) signal (100MHz) is transmitted over the multi-mode fiber, which is then up-converted to 2.2GHz inside the RAU. Local Oscillator (LO) signals to the mixers are generated by an on-chip frequency synthesizer. The measured optical to electrical conversion gain\,(V/W) is 59\,dB, whereas the input referred current noise is 3.5pA/$\sqrt{\mathrm{Hz}}$ and SFDR is 96.5dBHz^2/3. An LO leakage of -40dBc and an image rejection ratio of 43\,dB is measured. The circuit achieves an adjacent channel leakage ratio (ACLR) of -39dB and -41dB, for a 10MHz 32QAM signal at output power of 1dBm, and a 3.84MHz QPSK signal at 4dBm, respectively.
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| 8. |
- Ahmad, Waqas, et al.
(författare)
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Analysis of long term meteorological trends in the middle and lower Indus Basin of Pakistan-A non-parametric statistical approach
- 2014
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Ingår i: Global and Planetary Change. - : Elsevier BV. - 0921-8181 .- 1872-6364. ; 122, s. 282-291
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Tidskriftsartikel (refereegranskat)abstract
- The Indus basin of Pakistan is vulnerable to climate change which would directly affect the livelihoods of poor people engaged in irrigated agriculture. The situation could be worse in middle and lower part of this basin which occupies 90% of the irrigated area. The objective of this research is to analyze the long term meteorological trends in the middle and lower parts of Indus basin of Pakistan. We used monthly data from 1971 to 2010 and applied non-parametric seasonal Kendal test for trend detection in combination with seasonal Kendall slope estimator to quantify the magnitude of trends. The meteorological parameters considered were mean maximum and mean minimum air temperature, and rainfall from 12 meteorological stations located in the study region. We examined the reliability and spatial integrity of data by mass-curve analysis and spatial correlation matrices, respectively. Analysis was performed for four seasons (spring-March to May, summer-June to August-fall-September to November and winter-December to February). The results show that max. temperature has an average increasing trend of magnitude +0.16, +0.03, 0.0 and +0.04 degrees C/decade during all the four seasons, respectively. The average trend of min. temperature during the four seasons also increases with magnitude of +0.29, +0.12, +0.36 and +0.36 degrees C/decade, respectively. Persistence of the increasing trend is more pronounced in the min. temperature as compared to the max. temperature on annual basis. Analysis of rainfall data has not shown any noteworthy trend during winter, fall and on annual basis. However during spring and summer season, the rainfall trends vary from -1.15 to +0.93 and -3.86 to +2.46 mm/decade, respectively. It is further revealed that rainfall trends during all seasons are statistically non-significant. Overall the study area is under a significant warming trend with no changes in rainfall.
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| 9. |
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| 10. |
- Ahmad, Waqas, et al.
(författare)
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CMOS Adaptive TIA with Embedded Single-Ended to Differential Conversion for Analog Optical Links
- 2015
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Ingår i: 2015 IEEE International Symposium on Circuits and Systems (ISCAS). - 9781479983919
-
Konferensbidrag (refereegranskat)abstract
- A variable gain transimpedance amplifier (TIA) is presented featuring single-ended to differential conversion by means of negative feedback. The proposed topology also ensures stability when amplifier gain is varied. Furthermore, effective input capacitance of the TIA is reduced by using a positive capacitive feedback. The circuit is intended for intermediate frequency (IF) over fiber systems, but can be readily adapted for other applications. When simulated with a photodiode capacitance of 1.4 pF, the TIA exhibits a tunable gain range of 51 to 73dBΩ with a bandwidth of 550 MHz. The circuit designed in a standard 65nm CMOS process consuming 4mA from a 1.2V supply, achieves a spurious free dynamic range (SFDR) of 109dB·Hz 2/3 at 100 MHz.
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| 11. |
- Ahmad, Waqas, et al.
(författare)
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CMOS Integrated Remote Antenna Unit for Fiber-Fed Distributed MIMO Systems
- 2017
-
Ingår i: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480. ; 65:1, s. 173-186
-
Tidskriftsartikel (refereegranskat)abstract
- A fully integrated remote antenna unit (RAU) intended for fiber-fed distributed multiple-input multiple-output systems is presented. The circuit is designed for narrowband (60 MHz) time-division duplex systems, where an IF over fiber approach is chosen to facilitate the use of low-cost optical components and integrated photodetectors. A novel antenna switch control scheme is introduced, which enables the use of an integrated antenna switch instead of a bulky off chip circulator. The reference frequency signal is distributed in the fiber together with user data and used by a phase-locked-loop-based frequency synthesizer to generate the local oscillator signal inside the RAU, hence synchronizing all RAUs of the distributed antenna system. At an operating frequency of 2.1 GHz, the measured optical-to-electrical conversion gain of the downlink is 71.7 dB, the error vector magnitude is 3.2%, and the adjacent channel leakage ratio is 39.2 dBc at an output power of +3 dBm for a 16-quadrature amplitude modulation (16-QAM) long-term evolution downlink signal. The uplink has a gain of 32.5 dB, a noise figure of 3.5 dB, and an in-band third-order intercept point of -12 dBm. Implemented in a standard 65-nm CMOS process, the complete RAU occupies just 2 mm2 of die area and consumes 146 mW during downlink signal transmission and 122 mW during uplink signal reception.
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| 12. |
- Ahmad, Waqas, et al.
(författare)
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Compression scheme for sparsely sampled light field data based on pseudo multi-view sequences
- 2018
-
Ingår i: OPTICS, PHOTONICS, AND DIGITAL TECHNOLOGIES FOR IMAGING APPLICATIONS V Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE - International Society for Optical Engineering.
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Konferensbidrag (refereegranskat)abstract
- With the advent of light field acquisition technologies, the captured information of the scene is enriched by having both angular and spatial information. The captured information provides additional capabilities in the post processing stage, e.g. refocusing, 3D scene reconstruction, synthetic aperture etc. Light field capturing devices are classified in two categories. In the first category, a single plenoptic camera is used to capture a densely sampled light field, and in second category, multiple traditional cameras are used to capture a sparsely sampled light field. In both cases, the size of captured data increases with the additional angular information. The recent call for proposal related to compression of light field data by JPEG, also called “JPEG Pleno”, reflects the need of a new and efficient light field compression solution. In this paper, we propose a compression solution for sparsely sampled light field data. In a multi-camera system, each view depicts the scene from a single perspective. We propose to interpret each single view as a frame of pseudo video sequence. In this way, complete MxN views of multi-camera system are treated as M pseudo video sequences, where each pseudo video sequence contains N frames. The central pseudo video sequence is taken as base View and first frame in all the pseudo video sequences is taken as base Picture Order Count (POC). The frame contained in base view and base POC is labeled as base frame. The remaining frames are divided into three predictor levels. Frames placed in each successive level can take prediction from previously encoded frames. However, the frames assigned with last prediction level are not used for prediction of other frames. Moreover, the rate-allocation for each frame is performed by taking into account its predictor level, its frame distance and view wise decoding distance relative to the base frame. The multi-view extension of high efficiency video coding (MV-HEVC) is used to compress the pseudo multi-view sequences. The MV-HEVC compression standard enables the frames to take prediction in both direction (horizontal and vertical d), and MV-HEVC parameters are used to implement the proposed 2D prediction and rate allocation scheme. A subset of four light field images from Stanford dataset are compressed, using the proposed compression scheme on four bitrates in order to cover the low to high bit-rates scenarios. The comparison is made with state-of-art reference encoder HEVC and its real-time implementation X265. The 17x17 grid is converted into a single pseudo sequence of 289 frames by following the order explained in JPEG Pleno call for proposal and given as input to the both reference schemes. The rate distortion analysis shows that the proposed compression scheme outperforms both reference schemes in all tested bitrate scenarios for all test images. The average BD-PSNR gain is 1.36 dB over HEVC and 2.15 dB over X265.
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| 13. |
- Ahmad, Waqas, et al.
(författare)
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Computationally Efficient Light Field Image Compression Using a Multiview HEVC Framework
- 2019
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Ingår i: IEEE Access. - 2169-3536. ; 7, s. 143002-143014
-
Tidskriftsartikel (refereegranskat)abstract
- The acquisition of the spatial and angular information of a scene using light eld (LF) technologies supplement a wide range of post-processing applications, such as scene reconstruction, refocusing, virtual view synthesis, and so forth. The additional angular information possessed by LF data increases the size of the overall data captured while offering the same spatial resolution. The main contributor to the size of captured data (i.e., angular information) contains a high correlation that is exploited by state-of-the-art video encoders by treating the LF as a pseudo video sequence (PVS). The interpretation of LF as a single PVS restricts the encoding scheme to only utilize a single-dimensional angular correlation present in the LF data. In this paper, we present an LF compression framework that efciently exploits the spatial and angular correlation using a multiview extension of high-efciency video coding (MV-HEVC). The input LF views are converted into multiple PVSs and are organized hierarchically. The rate-allocation scheme takes into account the assigned organization of frames and distributes quality/bits among them accordingly. Subsequently, the reference picture selection scheme prioritizes the reference frames based on the assigned quality. The proposed compression scheme is evaluated by following the common test conditions set by JPEG Pleno. The proposed scheme performs 0.75 dB better compared to state-of-the-art compression schemes and 2.5 dB better compared to the x265-based JPEG Pleno anchor scheme. Moreover, an optimized motionsearch scheme is proposed in the framework that reduces the computational complexity (in terms of the sum of absolute difference [SAD] computations) of motion estimation by up to 87% with a negligible loss in visual quality (approximately 0.05 dB).
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| 14. |
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| 15. |
- Ahmad, Waqas, et al.
(författare)
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Fully Integrated Radio over Fiber Downlink for Distributed Multi-antenna Systems in 65nm CMOS
- 2014
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Ingår i: 2014 IEEE 12th International New Circuits and Systems Conference (NEWCAS). - 9781479978694 ; , s. 353-356
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Konferensbidrag (refereegranskat)abstract
- This paper presents a fully integrated downlink for low-cost remote antenna units in fiber-fed distributed multi-antenna systems. To reduce the cost of optical parts, an intermediate frequency(IF) signal is distributed over the fiber, and the circuit consists of an optical receiver, a single side-band frequency up-converting radio transmitter, and LO generation circuitry. The optical to electrical conversion gain(V/W) of the system is 59dB, and an output referred 1dB compression point of +6dBm and an OIP3 of +17dBm are measured. The SFDR of the circuit is 96.5 dBHz^2/3. The phase noise of the PLL measured at 4.2GHz is -145dBc/Hz at 20MHz offset, where as the reference spur level is -58dBc. The circuit is fabricated in a standard 65nm CMOS process and occupies just 0.8mm^2 of chip area including bond pads.
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| 16. |
- Ahmad, Waqas
(författare)
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High Efficiency Light Field Image Compression : Hierarchical Bit Allocation and Shearlet-based View Interpolation
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Over the years, the pursuit of capturing the precise visual information of a scenehas resulted in various enhancements in digital camera technology, such as highdynamic range, extended depth of field, and high resolution. However, traditionaldigital cameras only capture the spatial information of the scene and cannot pro-vide an immersive presentation of it. Light field (LF) capturing is a new-generationimaging technology that records the spatial and angular information of the scene. Inrecent years, LF imaging has become increasingly popular among the industry andresearch community mainly for two reasons: (1) the advancements made in optical and computational technology have facilitated the process of capturing and processing LF information and (2) LF data have the potential to offer various post-processing applications, such as refocusing at different depth planes, synthetic aperture, 3Dscene reconstruction, and novel view generation. Generally, LF-capturing devicesacquire large amounts of data, which poses a challenge for storage and transmissionresources. Off-the-shelf image and video compression schemes, built on assump-tions drawn from natural images and video, tend to exploit spatial and temporalcorrelations. However, 4D LF data inherit different properties, and hence there is aneed to advance the current compression methods to efficiently address the correla-tion present in LF data.In this thesis, compression of LF data captured using a plenoptic camera andmulti-camera system (MCS) is considered. Perspective views of a scene capturedfrom different positions are interpreted as a frame of multiple pseudo-video se-quences and given as an input to a multi-view extension of high-efficiency videocoding (MV-HEVC). A 2D prediction and hierarchical coding scheme is proposedin MV-HEVC to improve the compression efficiency of LF data. To further increasethe compression efficiency of views captured using an MCS, an LF reconstructionscheme based on shearlet transform is introduced in LF compression. A sparse set of views is coded using MV-HEVC and later used to predict the remaining views by applying shearlet transform. The prediction error is also coded to further increase the compression efficiency. Publicly available LF datasets are used to benchmark the proposed compression schemes. The anchor scheme specified in the JPEG Plenocommon test conditions is used to evaluate the performance of the proposed scheme. Objective evaluations show that the proposed scheme outperforms state-of-the-art schemes in the compression of LF data captured using a plenoptic camera and an MCS. Moreover, the introduction of shearlet transform in LF compression further improves the compression efficiency at low bitrates, at which the human vision sys-tem is sensitive to the perceived quality.The work presented in this thesis has been published in four peer-reviewed con-ference proceedings and two scientific journals. The proposed compression solu-tions outlined in this thesis significantly improve the rate-distortion efficiency forLF content, which reduces the transmission and storage resources. The MV-HEVC-based LF coding scheme is made publicly available, which can help researchers totest novel compression tools and it can serve as an anchor scheme for future researchstudies. The shearlet-transform-based LF compression scheme presents a compre-hensive framework for testing LF reconstruction methods in the context of LF com-pression.
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| 17. |
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| 18. |
- Ahmad, Waqas, et al.
(författare)
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Interpreting Plenoptic Images as Multi-View Sequences for Improved Compression
- 2017
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Ingår i: ICIP 2017. - : IEEE. - 9781509021758 ; , s. 4557-4561
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Konferensbidrag (refereegranskat)abstract
- Over the last decade, advancements in optical devices have made it possible for new novel image acquisition technologies to appear. Angular information for each spatial point is acquired in addition to the spatial information of the scene that enables 3D scene reconstruction and various post-processing effects. Current generation of plenoptic cameras spatially multiplex the angular information, which implies an increase in image resolution to retain the level of spatial information gathered by conventional cameras. In this work, the resulting plenoptic image is interpreted as a multi-view sequence that is efficiently compressed using the multi-view extension of high efficiency video coding (MV-HEVC). A novel two dimensional weighted prediction and rate allocation scheme is proposed to adopt the HEVC compression structure to the plenoptic image properties. The proposed coding approach is a response to ICIP 2017 Grand Challenge: Light field Image Coding. The proposed scheme outperforms all ICME contestants, and improves on the JPEG-anchor of ICME with an average PSNR gain of 7.5 dB and the HEVC-anchor of ICIP 2017 Grand Challenge with an average PSNR gain of 2.4 dB.
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| 19. |
- Ahmad, Waqas
(författare)
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Low Cost Remote Antenna Units in CMOS for Fiber-fed Distributed MIMO Systems
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Massive multiple input multiple output (MIMO) is a revolutionary communication technique, where large numbers of antennas are employed at the base stations to increase the spectral efficiency, reliability and data rate of the system. Moreover, in multi-user MIMO (MU-MIMO) multiple users can be served by the base stations on the same time-frequency resource. Distributed antenna system (DAS) is a form of massive MIMO, where the antennas are distributed over a geographic area instead of being co-located. Optical fibers can be used to connect these remote antenna units (RAUs) to the base station in a low loss and coherent fashion. Since large numbers of RAUs are required it is very important to reduce their cost. This work is focused on designing a low cost RAU intended for a multi-mode fiber (MMF) fed distributed MIMO system. It is also assumed that MMF and vertical cavity surface emitting lasers (VCSELs) would be used to keep the system cost low. A standard 65 nm CMOS technology was used to design the circuits. In paper I, a low cost RAU architecture was presented where a basic downlink signal chain with an integrated photodiode was designed. An intermediate frequency (IF) over fiber approach is chosen, so that an integrated photodiode and low cost optical components could be used. Measurement results indicated that the proposed architecture is promising for implementing low cost RAUs. Paper II presents the design and measurements of a complete RAU, featuring both uplink and downlink signal chains, and frequency generation circuits. The designed RAU also includes a novel scheme which allows the use of an antenna switch instead of a bulky circulator, saving both cost and area. Furthermore, RAU phase synchronization is achieved using reference signal distribution, which is critical for the performance of distributed MIMO systems. In paper III design and measurements of a RF power amplifier driver is presented. The driver was linearized by a triode multiplier, which significantly increased the linearity performance without any power and with minimal area overhead. The design and measurements of a fully integrated RF power amplifier (PA) is presented in paper IV. The PA was linearized by analog pre-distortion, achieved by employing a driver stage biased in class-C. In paper V, design and measurements of different CMOS photodiodes are presented. The obtained results are then used to choose the optimum photodiode structure for the optical receiver. Paper VI presents the design of a transimpedance amplifier, which converts the single-ended current signal from the integrated photodiode into a differential voltage signal. The single-ended to differential conversion was achieved by applying an ac common mode feedback. Furthermore, capacitive cross-coupling was applied to increase the gain of TIA, without affecting its bandwidth or using extra power.
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| 20. |
- Ahmad, Waqas, et al.
(författare)
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Matching Light Field Datasets From Plenoptic Cameras 1.0 And 2.0
- 2018
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Ingår i: Proceedings of the 2018 3DTV Conference. - 9781538661253
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Konferensbidrag (refereegranskat)abstract
- The capturing of angular and spatial information of the scene using single camera is made possible by new emerging technology referred to as plenoptic camera. Both angular and spatial information, enable various post-processing applications, e.g. refocusing, synthetic aperture, super-resolution, and 3D scene reconstruction. In the past, multiple traditional cameras were used to capture the angular and spatial information of the scene. However, recently with the advancement in optical technology, plenoptic cameras have been introduced to capture the scene information. In a plenoptic camera, a lenslet array is placed between the main lens and the image sensor that allows multiplexing of the spatial and angular information onto a single image, also referred to as plenoptic image. The placement of the lenslet array relative to the main lens and the image sensor, results in two different optical design sof a plenoptic camera, also referred to as plenoptic 1.0 and plenoptic 2.0. In this work, we present a novel dataset captured with plenoptic 1.0 (Lytro Illum) and plenoptic 2.0(Raytrix R29) cameras for the same scenes under the same conditions. The dataset provides the benchmark contents for various research and development activities for plenoptic images.
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| 21. |
- Ahmad, Waqas, et al.
(författare)
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Performance evaluation of N-well/P-sub photodiodes in 65nm CMOS process
- 2013
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Ingår i: [Host publication title missing]. - 9781479904648 ; , s. 135-136
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Konferensbidrag (refereegranskat)abstract
- This work explores the n-well/p-substrate photodiode in a deep submicron CMOS process. A CMOS chip is designed featuring different structures of the photodiode. When characterized at a wavelength of 850nm DC responsivities between 0.12 and 0.16 A/W and 3-dB bandwidths of about 6 MHz with a roll-off of about 5.5dB/decade are measured. These investigations are very useful in designing the transimpedance amplifier and equalizer for a fully integrated optical receiver. According to the authors’ knowledge it is the first reported study on n-well/p-sub photodiodes in a 65nm CMOS technology.
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| 22. |
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| 23. |
- Ahmad, Waqas, et al.
(författare)
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Shearlet Transform-Based Light Field Compression under Low Bitrates
- 2020
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Ingår i: IEEE Transactions on Image Processing. - : IEEE. - 1057-7149 .- 1941-0042. ; 29, s. 4269-4280
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Tidskriftsartikel (refereegranskat)abstract
- Light field (LF) acquisition devices capture spatial and angular information of a scene. In contrast with traditional cameras, the additional angular information enables novel post-processing applications, such as 3D scene reconstruction, the ability to refocus at different depth planes, and synthetic aperture. In this paper, we present a novel compression scheme for LF data captured using multiple traditional cameras. The input LF views were divided into two groups: key views and decimated views. The key views were compressed using the multi-view extension of high-efficiency video coding (MV-HEVC) scheme, and decimated views were predicted using the shearlet-transform-based prediction (STBP) scheme. Additionally, the residual information of predicted views was also encoded and sent along with the coded stream of key views. The proposed scheme was evaluated over a benchmark multi-camera based LF datasets, demonstrating that incorporating the residual information into the compression scheme increased the overall peak signal to noise ratio (PSNR) by 2 dB. The proposed compression scheme performed significantly better at low bit rates compared to anchor schemes, which have a better level of compression efficiency in high bit-rate scenarios. The sensitivity of the human vision system towards compression artifacts, specifically at low bit rates, favors the proposed compression scheme over anchor schemes. The proposed compression scheme performed significantly better at low bit rates compared to anchor schemes, which have a better level of compression efficiency in high bit-rate scenarios. The sensitivity of the human vision system towards compression artifacts, specifically at low bit rates, favors the proposed compression scheme over anchor schemes. The proposed compression scheme performed significantly better at low bit rates compared to anchor schemes, which have a better level of compression efficiency in high bit-rate scenarios. The sensitivity of the human vision system towards compression artifacts, specifically at low bit rates, favors the proposed compression scheme over anchor schemes.
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| 24. |
- Ahmad, Waqas, et al.
(författare)
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Shearlet Transform Based Prediction Scheme for Light Field Compression
- 2018
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Konferensbidrag (refereegranskat)abstract
- Light field acquisition technologies capture angular and spatial information ofthe scene. The spatial and angular information enables various post processingapplications, e.g. 3D scene reconstruction, refocusing, synthetic aperture etc at theexpense of an increased data size. In this paper, we present a novel prediction tool forcompression of light field data acquired with multiple camera system. The captured lightfield (LF) can be described using two plane parametrization as, L(u, v, s, t), where (u, v)represents each view image plane coordinates and (s, t) represents the coordinates of thecapturing plane. In the proposed scheme, the captured LF is uniformly decimated by afactor d in both directions (in s and t coordinates), resulting in a sparse set of views alsoreferred to as key views. The key views are converted into a pseudo video sequence andcompressed using high efficiency video coding (HEVC). The shearlet transform basedreconstruction approach, presented in [1], is used at the decoder side to predict thedecimated views with the help of the key views.Four LF images (Truck, Bunny from Stanford dataset, Set2 and Set9 from High DensityCamera Array dataset) are used in the experiments. Input LF views are converted into apseudo video sequence and compressed with HEVC to serve as anchor. Rate distortionanalysis shows the average PSNR gain of 0.98 dB over the anchor scheme. Moreover, inlow bit-rates, the compression efficiency of the proposed scheme is higher compared tothe anchor and on the other hand the performance of the anchor is better in high bit-rates.Different compression response of the proposed and anchor scheme is a consequence oftheir utilization of input information. In the high bit-rate scenario, high quality residualinformation enables the anchor to achieve efficient compression. On the contrary, theshearlet transform relies on key views to predict the decimated views withoutincorporating residual information. Hence, it has inherit reconstruction error. In the lowbit-rate scenario, the bit budget of the proposed compression scheme allows the encoderto achieve high quality for the key views. The HEVC anchor scheme distributes the samebit budget among all the input LF views that results in degradation of the overall visualquality. The sensitivity of human vision system toward compression artifacts in low-bitratecases favours the proposed compression scheme over the anchor scheme.
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| 25. |
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| 26. |
- Ahmad, Waqas, et al.
(författare)
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The Plenoptic Dataset
- 2018
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Annan publikationabstract
- The dataset is captured using two different plenoptic cameras, namely Illum from Lytro (based on plenoptic 1.0 model) and R29 from Raytrix (based on plenoptic 2.0 model). The scenes selected for the dataset were captured under controlled conditions. The cameras were mounted onto a multi-camera rig that was mechanically controlled to move the cameras with millimeter precision. In this way, both cameras captured the scene from the same viewpoint.
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| 27. |
- Ahmad, Waqas, et al.
(författare)
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Towards a generic compression solution for densely and sparsely sampled light field data
- 2018
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Ingår i: Proceedings of 25TH IEEE International Conference On Image Processing. - 9781479970612 ; , s. 654-658
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Konferensbidrag (refereegranskat)abstract
- Light field (LF) acquisition technologies capture the spatial and angular information present in scenes. The angular information paves the way for various post-processing applications such as scene reconstruction, refocusing, and synthetic aperture. The light field is usually captured by a single plenoptic camera or by multiple traditional cameras. The former captures a dense LF, while the latter captures a sparse LF. This paper presents a generic compression scheme that efficiently compresses both densely and sparsely sampled LFs. A plenoptic image is converted into sub-aperture images, and each sub-aperture image is interpreted as a frame of a multiview sequence. In comparison, each view of the multi-camera system is treated as a frame of a multi-view sequence. The multi-view extension of high efficiency video coding (MVHEVC) is used to encode the pseudo multi-view sequence.This paper proposes an adaptive prediction and rate allocation scheme that efficiently compresses LF data irrespective of the acquisition technology used.
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| 28. |
- Ahmed Waqas, Hafiz, et al.
(författare)
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Performance Prediction of Hybrid Bamboo-Reinforced Concrete Beams Using Gene Expression Programming for Sustainable Construction
- 2023
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Ingår i: Materials. - : MDPI. - 1996-1944. ; 16:20
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Tidskriftsartikel (refereegranskat)abstract
- The building and construction industry’s demand for steel reinforcement bars has increased with the rapid growth and development in the world. However, steel production contributes to harmful waste and emissions that cause environmental pollution and climate change-related problems. In light of sustainable construction practices, bamboo, a readily accessible and ecofriendly building material, is suggested as a viable replacement for steel rebars. Its cost-effectiveness, environmental sustainability, and considerable tensile strength make it a promising option. In this research, hybrid beams underwent analysis through the use of thoroughly validated finite element models (FEMs), wherein the replacement of steel rebars with bamboo was explored as an alternative reinforcement material. The standard-size beams were subjected to three-point loading using FEMs to study parameters such as the load–deflection response, energy absorption, maximum capacity, and failure patterns. Then, gene expression programming was integrated to aid in developing a more straightforward equation for predicting the flexural strength of bamboo-reinforced concrete beams. The results of this study support the conclusion that the replacement of a portion of flexural steel with bamboo in reinforced concrete beams does not have a detrimental impact on the overall load-bearing capacity and energy absorption of the structure. Furthermore, it may offer a cost-effective and feasible alternative.
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| 29. |
- Axholt, Andreas, et al.
(författare)
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A 90nm CMOS UWB LNA
- 2008
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Ingår i: [Host publication title missing]. - 9781424424924 ; , s. 25-28
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Konferensbidrag (refereegranskat)abstract
- A single-ended two-stage 3.1-10.6GHz Low Noise Amplifier aimed for Ultra Wide Band (UWB) communication is presented. The LNA is fabricated in a 90nm CMOS process and measures just 0.31x0.41 mm2 including pads. The first stage topology is common-gate, to achieve a wideband input match. The second stage is a common source stage with resistive shunt feedback, to achieve high and flat gain over a wide frequency range. The chip was measured using RF-probes and has a gain of 17.25±1.25dB, a noise figure of 4.1-9.4 dB, and an input reflection S11 better than -12dB between 3.1GHz and 10.6GHz, while consuming 8.6mA from a 1V supply.
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| 30. |
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| 31. |
- Danish, Muhammad, et al.
(författare)
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An efficient catalytic degradation of trichloroethene in a percarbonate system catalyzed by ultra-fine heterogeneous zeolite supported zero valent iron-nickel bimetallic composite
- 2017
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Ingår i: Applied Catalysis A. - : Elsevier. - 0926-860X .- 1873-3875. ; 531, s. 177-186
-
Tidskriftsartikel (refereegranskat)abstract
- Zeolite supported nano iron-nickel bimetallic composite (Z-nZVI-Ni) was prepared using a liquid-phase reduction process. The corresponding surface morphologies and physico-chemical properties of the Z-nZVI-Ni composite were determined using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Energy dispersive X-ray spectra (EDS), Brunauer Emmett Teller (BET) adsorption, wide angle X-ray diffractometry (WA-XRD), and Fourier transform infrared spectroscopy (FTIR). The results indicated high dispersion of iron and nickel nano particles on the zeolite sheet with an enhanced surface area. Complete destruction of trichloroethene (TCE) and efficient removal of total organic carbon (TOC) were observed by using Z-nZVI-Ni as a heterogeneous catalyst for a Fenton-like oxidation process employing sodium percarbonate (SPC) as an oxidant. The electron spin resonance (ESR) of Z-nZVI-Ni verified the generation and intensity of hydroxyl radicals (OH center dot). The quantification of OH center dot elucidated by using p-chlorobenzoic acid, a probe indicator, confirmed the higher intensity of OH center dot. The transformation products were identified using GC-MS. The slow iron and nickel leaching offered higher stability and better catalytic activity of Z-nZVI-Ni, demonstrating its prospective long term applications in groundwater for TCE degradation. (C) 2016 Elsevier B.V. All rights reserved.
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| 32. |
- Ghafoor, Mubeen, et al.
(författare)
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Perceptually Lossless Surgical Telementoring System Based on Non-Parametric Segmentation
- 2019
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Ingår i: Journal of Medical Imaging and Health Informatics. - : American Scientific Publishers. - 2156-7018 .- 2156-7026. ; 9:3, s. 464-473
-
Tidskriftsartikel (refereegranskat)abstract
- Bandwidth constraint is one of the significant concerns of surgical telementoring, especially in rural areas. High-Efficiency Video Coding (H.265/HEVC) based video compression techniques have shown promising results for telementoring applications. However, there is a tradeoff between the quality of video received by the remote surgeon and the bandwidth resources required for video transmission. In order to efficiently compress and transmit real-time surgical videos, a hybrid lossless-lossy approach is proposed where surgical incision region (location of surgery) is coded in high quality while the background (non-incision) region is coded in medium to low quality depending on the nature of the region. The surgical incision region is detected based on an efficient color and location-based non-parametric segmentation approach. This approach takes explicitly into account the physiological nature of the human visual system and efficiently encodes the video by providing good overall visual impact in the location of surgery. The results of the proposed approach are shown in terms of video quality metrics such as Bjontegaard delta bitrate (BD-BR), Bjontegaard delta peak signal-to-noise ratio (BD-PSNR), and structural similarity index measurement (SSIM). Experimental results showed that in comparison with default full-frame HEVC encoding, the proposed surgical incision region based encoding achieved an average BD-BR reduction of 77.5% at high-quality settings (QP in range of 0 to 20 in surgical incision region and an increasing QP in skin and background region). The average gain in BD-PSNR of the proposed algorithm was 6.99 dB in surgical incision region at high-quality setting, and the average SSIM index came out to be 0.9926 which is only 0.006% less than the default full-frame HEVC coding. Based on these results, the proposed encoding algorithm can be considered as an efficient and effective solution for surgical telementoring systems for limited bandwidth networks.
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| 33. |
- Ghumman, Iss, et al.
(författare)
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Computational Fluid Mechanics Model for Numerical Investigation of Frictional Tribo-pair during Mixed Lubrication
- 2022
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Ingår i: Proceedings of 2022 19th International Bhurban Conference on Applied Sciences and Technology, IBCAST 2022. - : Institute of Electrical and Electronics Engineers Inc.. - 9781665460514 ; , s. 815-820
-
Konferensbidrag (refereegranskat)abstract
- All the machines are constructed through mechanical links and pairs. One of the crucial pairs is the sliding pair; due to their nature and general use, they are often subjected to a higher degree of dynamics and external forces leading to high frictional force. To reduce wear from friction formerly thick film of commercial oil is used. However, viscosity-based higher thickness yields higher energy losses, and nano-lubricants are popular in reducing friction while keeping film thickness and improving wear resistance. This paper develops a numerical model for sliding pairs that predicts the load carried by components under different lubrication regimes. The aim is to simulate hydrodynamic and mixed lubrication regimes for different loading conditions. A detailed multiphysics model of tribo-pair was modeled, including lubricant rheology, surface topology, oil film squeeze, and film temperature through the moving mesh. The fluid domain has been meshed with Arbitrary Lagrangian and Eulerian techniques. Energy loss due to viscous friction and boundary friction were determined by solving Naiver- Stokes equations in the moving mesh deformable geometry domain. The numerical model was compared with the available literature, and the results are presented. This numerical simulation remained valid and provides the fundamental understanding of oil film thickness and load-carrying capacity of sliding tribo-pair in the presence of nano-lubricants. The developed model is a useful methodology for studying lubricant oil enriched with nanoparticles.
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| 34. |
- Hassan, A., et al.
(författare)
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High Efficiency Video Coding (HEVC)–Based Surgical Telementoring System Using Shallow Convolutional Neural Network
- 2019
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Ingår i: Journal of digital imaging. - : Springer Science and Business Media LLC. - 0897-1889 .- 1618-727X. ; 32:6, s. 1027-1043
-
Tidskriftsartikel (refereegranskat)abstract
- Surgical telementoring systems have gained lots of interest, especially in remote locations. However, bandwidth constraint has been the primary bottleneck for efficient telementoring systems. This study aims to establish an efficient surgical telementoring system, where the qualified surgeon (mentor) provides real-time guidance and technical assistance for surgical procedures to the on-spot physician (surgeon). High Efficiency Video Coding (HEVC/H.265)–based video compression has shown promising results for telementoring applications. However, there is a trade-off between the bandwidth resources required for video transmission and quality of video received by the remote surgeon. In order to efficiently compress and transmit real-time surgical videos, a hybrid lossless-lossy approach is proposed where surgical incision region is coded in high quality whereas the background region is coded in low quality based on distance from the surgical incision region. For surgical incision region extraction, state-of-the-art deep learning (DL) architectures for semantic segmentation can be used. However, the computational complexity of these architectures is high resulting in large training and inference times. For telementoring systems, encoding time is crucial; therefore, very deep architectures are not suitable for surgical incision extraction. In this study, we propose a shallow convolutional neural network (S-CNN)–based segmentation approach that consists of encoder network only for surgical region extraction. The segmentation performance of S-CNN is compared with one of the state-of-the-art image segmentation networks (SegNet), and results demonstrate the effectiveness of the proposed network. The proposed telementoring system is efficient and explicitly considers the physiological nature of the human visual system to encode the video by providing good overall visual impact in the location of surgery. The results of the proposed S-CNN-based segmentation demonstrated a pixel accuracy of 97% and a mean intersection over union accuracy of 79%. Similarly, HEVC experimental results showed that the proposed surgical region–based encoding scheme achieved an average bitrate reduction of 88.8% at high-quality settings in comparison with default full-frame HEVC encoding. The average gain in encoding performance (signal-to-noise) of the proposed algorithm is 11.5 dB in the surgical region. The bitrate saving and visual quality of the proposed optimal bit allocation scheme are compared with the mean shift segmentation–based coding scheme for fair comparison. The results show that the proposed scheme maintains high visual quality in surgical incision region along with achieving good bitrate saving. Based on comparison and results, the proposed encoding algorithm can be considered as an efficient and effective solution for surgical telementoring systems for low-bandwidth networks.
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| 35. |
- Khan, Imran, et al.
(författare)
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Performing active noise control and acoustic experiments remotely
- 2012
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Ingår i: International Journal of Online Engineering. - : Kassel University Press GmbH. - 1868-1646 .- 1861-2121. ; 8:special issue 2, s. 65-74
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a novel and advanced remotely controlled laboratory for conducting Active Noise Control (ANC), acoustic and Digital Signal Processing (DSP) experiments. The laboratory facility, recently developed by Blekinge Institute of Technology (BTH) Sweden, supports remote learning through internet covering beginners level such as simple experimental measurements to advanced users and even researchers such as algorithm development and their performance evaluation on DSP. The required software development for ANC algorithms and equipment control are carried out anywhere in the world remotely from an internet-connected client PC using a standard web browser. The paper describes in detail how ANC, acoustic and DSP experiments can be performed remotely The necessary steps involved in an ANC experiment such as validity of ANC, forward path estimation and active control applied to a broad band random noise [0-200Hz] in a ventilation duct will be described in detail. The limitations and challenges such as the forward path and nonlinearities pertinent to the remote laboratory setup will be described for the guidance of the user. Based on the acoustic properties of the ventilation duct some of the possible acoustic experiments such as mode shapes analysis and standing waves analysis etc. will also be discussed in the paper.
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| 36. |
- khan, Imran, et al.
(författare)
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Remotely Controlled Active Noise Contol Laboratiories
- 2012
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Ingår i: The Nineteenth International Congress on Sound and Vivration. - Vilnius : Curran Associates, Inc.. - 9781622764655
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Remotely controlled laboratories in educational institutions are gaining popularity at an exponential rate due to the multidimensional benefits they provide. The Virtual Instrument Systems in Reality (VISIR) project by Blekinge Institute of Technology (BTH) Sweden has successfully implemented remotely controlled laboratories, with remotely controlled real instruments and experimental setups. Currently these laboratories provide students the opportunity to conduct experiments in the field of electronics, antenna theory and mechanical vibration measurements. In this paper a prototype system of a remotely controlled laboratory for active noise control (ANC) is introduced. The proposed lab will focus on addressing the problem of a ventilation duct noise. The laboratory is informative and to a great extent introduces a student to the general steps in ANC when it is suggested as a plausible solution for a noise problem. The student can perform an investigation concerning feasibility of active control, design, configuration and implementation of an active control system. The laboratory is based on a modern and relevant DSP platform with the corresponding software development environment controlled remotely. In addition, it may be utilized remotely both for lab assignments in acoustics courses and digital signal processing courses.
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| 37. |
- Muzaffar, Nimra, et al.
(författare)
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Designing of VCuS@MXene nanocomposite electrode for energy storage device and electrochemical glucose sensor
- 2024
-
Ingår i: Journal of materials science. Materials in electronics. - : Springer Nature. - 0957-4522 .- 1573-482X. ; 35:9
-
Tidskriftsartikel (refereegranskat)abstract
- MXene, a two-dimensional (2D) material composed of transition metal carbides (TMCs) and nitrides, have fascinated substantial scientific interest. This increased interest results from their exceptional properties, which include extraordinary conductivity, transparency, outstanding absorbing capacity, and significant charge storage capacities. In this work, the MXene-doped vanadium copper sulfide (VCuS) was synthesized through the hydrothermal method. In three electrode measurement system, the VCuS/MXene composite electrode showed exhibited a specific capacity (Qs) of 1620 Cg−1. As application point of view, the hybrid device is designed and measured the electrochemical properties. The hybrid device showed the remarkable Qs of 1528 C.g−1, power density (Pd) of 2347 Wkg−1 and an energy density (Ed) of 34.99 Whkg−1. Further, the VCuS/MXene//AC device is measured up to 6000 cycles to check the stability and durability. The device showed the capacity retention (CR) of 88.5% and a high Coulombic efficiency of 82.6%. Additionally, the VCuS/MXene electrode material is utilized as an electrochemical glucose sensor for the precise detection of H2O2 down to a minimal concentration of H2O2/mm, exhibiting exceptional precision. The use of multifunctional VCuS/MXene nanocomposite electrode material presents novel possibilities for the construction of hybrid energy harvesting systems.
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| 38. |
- Qayyum, Waqas, et al.
(författare)
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Assessment of Convolutional Neural Network Pre-Trained Models for Detection and Orientation of Cracks
- 2023
-
Ingår i: Materials. - : MDPI. - 1996-1944. ; 16:2
-
Tidskriftsartikel (refereegranskat)abstract
- Failure due to cracks is a major structural safety issue for engineering constructions. Human examination is the most common method for detecting crack failure, although it is subjective and time-consuming. Inspection of civil engineering structures must include crack detection and categorization as a key component of the process. Images can automatically be classified using convolutional neural networks (CNNs), a subtype of deep learning (DL). For image categorization, a variety of pre-trained CNN architectures are available. This study assesses seven pre-trained neural networks, including GoogLeNet, MobileNet-V2, Inception-V3, ResNet18, ResNet50, ResNet101, and ShuffleNet, for crack detection and categorization. Images are classified as diagonal crack (DC), horizontal crack (HC), uncracked (UC), and vertical crack (VC). Each architecture is trained with 32,000 images equally divided among each class. A total of 100 images from each category are used to test the trained models, and the results are compared. Inception-V3 outperforms all the other models with accuracies of 96%, 94%, 92%, and 96% for DC, HC, UC, and VC classifications, respectively. ResNet101 has the longest training time at 171 min, while ResNet18 has the lowest at 32 min. This research allows the best CNN architecture for automatic detection and orientation of cracks to be selected, based on the accuracy and time taken for the training of the model.
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| 39. |
- Qayyum, Waqas, et al.
(författare)
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Predicting characteristics of cracks in concrete structure using convolutional neural network and image processing
- 2023
-
Ingår i: Frontiers in Materials. - : Frontiers. - 2296-8016. ; 10
-
Tidskriftsartikel (refereegranskat)abstract
- The degradation of infrastructures such as bridges, highways, buildings, and dams has been accelerated due to environmental and loading consequences. The most popular method for inspecting existing concrete structures has been visual inspection. Inspectors assess defects visually based on their engineering expertise, competence, and experience. This method, however, is subjective, tiresome, inefficient, and constrained by the requirement for access to multiple components of complex structures. The angle, width, and length of the crack allow us to figure out the cause of the propagation and extent of the damage, and rehabilitation can be suggested based on them. This research proposes an algorithm based on a pre-trained convolutional neural network (CNN) and image processing (IP) to obtain the crack angle, width, endpoint length, and actual path length in a concrete structure. The results show low relative errors of 2.19%, 14.88%, and 1.11%, respectively for the crack angle, width, and endpoint length from the CNN and IP methods developed in this research. The actual path length is found to be 14.69% greater than the crack endpoint length. When calculating the crack length, it is crucial to consider its irregular shape and the likelihood that its actual path length will be greater than the direct distance between the endpoints. This study suggests measurement methods that precisely consider the crack shape to estimate its actual path length.
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| 40. |
- Safdar, Aqsa, et al.
(författare)
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Comparison of EKFC, Pakistani CKD-EPI and 2021 Race-Free CKD-EPI creatinine equations in South Asian CKD population : A study from Pakistani CKD community cohort
- 2024
-
Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 19:3
-
Tidskriftsartikel (refereegranskat)abstract
- IntroductionSouth Asian individuals possess a high risk of chronic kidney disease. There is a need to study, evaluate, and compare the newly suggested glomerular filtration rate (eGFR) equations for accurate CKD diagnosis, staging, and drug dosing. This study aimed to (1) evaluate the European Kidney Function Consortium (EKFC), Pakistani CKD-EPI, and 2021 Race-Free CKD-EPI creatinine equation in the South Asian population with CKD and (2) to examine the expected implications on both CKD classification as well as End Stage Renal Disease (ESRD) prevalence across these equations in South Asian population.MethodsWe carried out a cross-sectional investigation on 385 participants, a CKD cohort ≥ 18 years, at Allama Iqbal Medical College, Jinnah Hospital, Lahore. Serum creatinine was measured by Jaffe’s method and rGFR was measured by inulin clearance.ResultsPakistani CKD-EPI has a lower median difference at -1.33 ml/min/1.73m2 elevated precision (IQR) at 2.33 (-2.36, -0.03) and higher P30 value at 89.35% than 2021 CKD-EPI and EKFC equations. The mean difference (ml/min/1.73m2), 95% agreement limits (ml/min/1.73m2) of CKD-EPI PK: -1.18, -6.14, 2021 CKD-EPI: -5.98, -13.24 and EKFC: -5.62, -13.01 (P <0.001). These equations highly correlated to rGFR (P <0.001). An upward re-classification in GFR categories was shown by 2021 CKD-EPI and EKFC compared to the Pakistani CKD-EPI equation. However, there was an exception regarding the G5 category, where an elevated count of 217 (56.36%) was shown for CKD-EPI PK. The prevalence of ESRD was seen in entire age groups and prevailed among females more than in males overall equations.ConclusionsPakistani CKD-EPI exhibited outstanding performance, while 2021 CKD-EPI and EKFC demonstrated poor performances and could not show an adequate advantage for both CKD classification and prevalence of ESRD compared to Pakistani CKD-EPI. Therefore, Pakistani CKD-EPI appears optimal for this region and warrants future validation in other South Asian countries. In contrast, suitable measures must be implemented in Pakistani laboratories.
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| 41. |
- Sahil, Mehran, et al.
(författare)
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Seismic performance evaluation of exterior reinforced concrete beam-column connections retrofitted with economical perforated steel haunches
- 2024
-
Ingår i: Results in Engineering (RINENG). - : Elsevier. - 2590-1230. ; 22
-
Tidskriftsartikel (refereegranskat)abstract
- The exterior beam-column joint (BCJ) within reinforced concrete (RC) frame structures is acknowledged as a vulnerable component prone to seismic failure. This article proposes a practical and economical strengthening method for exterior BCJs using a perforated steel haunch system. This method is designed to mitigate damage in BCJs and improve the seismic performance of the structure. Employing finite element modeling (FEM) techniques, the study evaluates the impact of perforated steel haunches on the BCJs’ behavior and performance. The investigation involves creating nine distinct models, each representing a BCJ with a steel haunch system. These models include a control model without any perforations and eight variations with different levels of perforation (ranging from 10% to 50%) within the steel haunch system. Furthermore, the study analyzes the influence of perforation shapes on the connections’ performance, considering square, circular, hexagonal, and triangular shapes. The results reveal that utilizing a steel haunch without perforations significantly increases the load-carrying capacity of a BCJ by about 89%. Additionally, circular or square-shaped perforations, up to 30–35% within the steel haunch, effectively prevent the joints’ failure and promote the ductile behavior. These findings hold the potential to advance the design methodology for RC joints subjected to seismic loads, thereby enhancing the structural resilience in earthquake-prone regions.
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| 42. |
- Saif-Ul-Allah, Muhammad Waqas, et al.
(författare)
-
Computationally Inexpensive 1D-CNN for the Prediction of Noisy Data of NOx Emissions From 500 MW Coal-Fired Power Plant
- 2022
-
Ingår i: Frontiers in Energy Research. - : FRONTIERS MEDIA SA. - 2296-598X. ; 10
-
Tidskriftsartikel (refereegranskat)abstract
- Coal-fired power plants have been used to meet the energy requirements in countries where coal reserves are abundant and are the key source of NOx emissions. Owing to the serious environmental and health concerns associated with NOx emissions, much work has been carried out to reduce NOx emissions. Sophisticated artificial intelligence (AI) techniques have been employed during the past few decades, such as least-squares support vector machine (LSSVM), artificial neural networks (ANN), long short-term memory (LSTM), and gated recurrent unit (GRU), to develop the NOx prediction model. Several studies have investigated deep neural networks (DNN) models for accurate NOx emission prediction. However, there is a need to investigate a DNN-based NOx prediction model that is accurate and computationally inexpensive. Recently, a new AI technique, convolutional neural network (CNN), has been introduced and proven superior for image class prediction accuracy. According to the best of the author's knowledge, not much work has been done on the utilization of CNN on NOx emissions from coal-fired power plants. Therefore, this study investigated the prediction performance and computational time of one-dimensional CNN (1D-CNN) on NOx emissions data from a 500 MW coal-fired power plant. The variations of hyperparameters of LSTM, GRU, and 1D-CNN were investigated, and the performance metrics such as RMSE and computational time were recorded to obtain optimal hyperparameters. The obtained optimal values of hyperparameters of LSTM, GRU, and 1D-CNN were then employed for models' development, and consequently, the models were tested on test data. The 1D-CNN NOx emission model improved the training efficiency in terms of RMSE by 70.6% and 60.1% compared to LSTM and GRU, respectively. Furthermore, the testing efficiency for 1D-CNN improved by 10.2% and 15.7% compared to LSTM and GRU, respectively. Moreover, 1D-CNN (26 s) reduced the training time by 83.8% and 50% compared to LSTM (160 s) and GRU (52 s), respectively. Results reveal that 1D-CNN is more accurate, more stable, and computationally inexpensive compared to LSTM and GRU on NOx emission data from the 500 MW power plant.
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| 43. |
- TIRED, TOBIAS, et al.
(författare)
-
A 1.5 V 28 GHz beam steering SiGe PLL for an 81-86 GHz E-band transmitter
- 2016
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Ingår i: IEEE Microwave and Wireless Components Letters. - 1531-1309. ; 26:10, s. 843-845
-
Tidskriftsartikel (refereegranskat)abstract
- This letter presents measurement results for a low supply voltage 28 GHz beam steering PLL, designed in a SiGe bipolar process with fT=200 GHz. The PLL, designed around a QVCO, is intended for a beam steering 81-86 GHz E-band transmitter. Linear phase control is implemented by variable current injection into a Gilbert type phase detector, with a measured nominal phase control sensitivity of 2.5 °/ μA . The demonstrated LO generation method offers great advantages in the implementation of beam steering mm-wave transmitters, since only the low frequency PLL reference signal of 1.75 GHz needs to be routed across the chip to the different transmitters. Except for an active loop filter, used to extend the locking range of the PLL, the design uses a low supply voltage of 1.5 V. The PLL obtains a measured in band phase noise of −107 dBc/Hz at 1 MHz offset. The power consumption equals 54 mW from the 1.5 V supply plus 1.8 mW for the variable supply of the active low pass filter.
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| 44. |
- Wernehag, Johan, et al.
(författare)
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A 30dBm PA for MTC Communication in 65nm CMOS Technology
- 2016
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Ingår i: 2016 IEEE 7th Latin American Symposium on Circuits & Systems (LASCAS). - 9781467378352 ; , s. 147-150
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Konferensbidrag (refereegranskat)abstract
- In this paper the feasibility of using a fully integrated 65nm CMOS PA in future machine-type communication standards has been investigated. The integrated PA investigated shows a linear output power in VSWR 2:1 of minimum 24dBm. A VSWR of 2:1 with an associated 3.1dB front-end insertion loss corresponds to a VSWR of 5:1 at the antenna, which is a conservative number. The PAE at 1dB compression point is close to 40% for VSWR 1:1. Taking margin for modulation peak-to-average ratio of 5dB, the PAE at compression point -5dB is 31% at 2100MHz and 24% at 2600MHz. To show the possibility of multi-band operation the PA is centered at 2100MHz and then retuned to 2600MHz, indicating feasibility of a single high band PA. The gain of the two-stage PA is 27dB at 2100MHz and 24dB at 2600MHz. All simulated with a 3.3V output stage supply.
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