Leveraging the smog crisis that Punjab has been facing for a couple of years, attention has been drawn towards matters that were not considered worrisome. Joudat Bint Khalil presented her master’s research that advocated the potential impacts of ground-level ozone on crop yields by assessing the spatio-temporal spread it has over agricultural fields of Punjab. Joudat used model simulated and real time observational concentrations of ozone for interpretation of seasonal and diurnal variations prevalent over rural and urban areas. An Atmospheric Dynamics and Chemistry Transport Modeling (ADCTM) system was set up to simulate the land atmosphere dynamics and obtain simulated concentrations. Whereas, the observational data was recorded from an Air Quality monitor deployed by the Punjab Government’s Environment Protection Department (EPD). The simulated ozone fields were evaluated by comparison against observed concentration to assess the ability of the Chemical Transport Model to capture the seasonal and diurnal variation of ozone at an urban site in Lahore. In addition, adjusted predicted concentrations were also calculated by bias correcting the predicted concentrations for rural sites due to lack of recorded data. Given the significance of having an adequate monitoring network to accurately characterize air pollution at high spatial and temporal resolutions, an air quality sensor suite suitable for deployment at a remote site was developed and tested as a part of Joudat’s research. The sensor suite; having a vertical configuration, could capture the atmospheric conditions and the exchange that occurs between the land surface, land subsurface, and atmosphere. Joudat’s research was aimed towards calculating ozone induced losses in crop yields for three staple crops: maize, soybean, and wheat for which she has concurrently incorporated AOT40 and M7/M12 ozone exposure metrics and crop-specific concentration response equations. In conclusion, the research stated that elevated levels of ozone have greater impact on crop yields as it was accumulated over specific periods and at specific times of the day when plants are most likely to consume ozone. This research was supervised by Dr. Abubakr Muhammad and co-supervised by Dr. Maudood N. Khan. A 12-month long post thesis research was also carried out by Joudat at the Centre for Water Informatics and Technology (WIT). During this time, she intensively worked on conducting prolonged field campaigns, installation and maintenance of the instrument suites, and data analysis to investigate the matter with real time recorded observations at the farm level.

پچھلے چند سالوں سے پنجاب کو اسموگ کے بحران کا سامنا ہے جس کی بدولت تحقیقی برادری کی ایسے امور کی طرف توجہ مبذول کرائی گئی ہے جنہیں اس سے قبل تشویشناک نہیں سمجھا جاتا تھا۔ سائیفائینٹس لیب میں بطور ایم ایس طالب علم جودت بنت خلیل نے اپنے تحقیقی مقالے میں زرعی علاقوں میں زمینی سطح کی اوزون گیس کی زمانی و مکانی تقسیم کے زرعی پیداوار پر ممکنہ اثرات کی تحقیق پیش کی- جودت نے دیہی اور شہری علاقوں میں رونما ہونے والی اوزون کی حرکت میں موسمی اور روزانہ ہر گھنٹے کے حساب سے پیش آنے والے طرزعمل کو سمجھنے کے لئے ماڈل کی سیمولیشن اور ریکارڈ شدہ مشاہدات کو استعمال کیا ۔زمین اور فضا کے درمیان ہوا کے تبادلے کے عمل کو سمجھنے اور سیمولیشن کو بنانے کے لئے ایٹموسفیئرک ڈائنامکش اینڈ کیمسٹری ٹرانسپورٹ ماڈلنگ (اے ڈی سی ٹی ایم) سسٹم قائم کیا گیا تھا ۔ موجودہ مشاہدات کو ایئر کوالٹی مانیٹر کے ذریعے بروقت ریکارڈاور نشر کیا گیا جو کےحکومت پنجاب کے ماحولیاتی تحفظ کے محکمہ (ای پی ڈی) کے ذریعہ تنصیب تھا ۔کیمسٹری ٹرانسپورٹ ماڈل کی موسمی اور روزانہ ہر گھنٹے کی تغیرات کی تسلی بحش نقل کرنے کی صلاحیت کا اندازہ کرنے کے لئے ماڈلنگ سسٹم سے حاصل کردہ اوزون کا موازنہ ‍حقیقی مشاہدات سے کیا گیا ۔ اس کے علاوہ، ریکارڈ شدہ مشاہدات کی کمی کے باعث دیہی علاقوں میں اوزون کا اندازہ ماڈل سیمولیشن کو اعداد شمار کے مطابق اصلاح کر کے لگایا گیا ۔ فضائی آلودگی کی خصوصیات کو بہتر سمجھنے کے لیے اعلی مانیٹر نگ نیٹ ورک کی اہمیت کو مد نظر رکھتے ہوئے جودت کی تحقیق میں دور دراز علاقوں میں تنصیب کے لئے موزوں ایئر کوالٹی سنسرکے مجمعے کو تیار اور ٹیسٹ کیا گیا تھا ۔سنسر مجمع عمودی ترتیب رکھنے کی وجہ سے ، ماحولیاتی حالات اور اس تبادلے کا بخوبی اندازہ لگا سکتا ہے جو زمین کی سطح ، سطح کے زیر زمین اور گردونواح کے مابین ہوتا ہے۔ جودت کی تحقیق کا مقصد فصلوں کی پیداوار میں اوزون سے ہونے والے نقصانات کا حساب لگانا تھا جن میں مکئی ، سویا بین ، اور گندم شامل ہیں جس کے لئے انہوں نے اصلاح شدہ اوزان کو اوزان میٹرکس اور فصل کے مخصوص کاسنٹریشن رسپانس مساوات کو شامل کیا ۔ تحقیق میں بتایا گیا ہے کہ اوزان کی بلند سطح کا فصلوں کی پیداوار پر منفی اثر پڑتا ہے کیونکہ یہ مخصوص ادوار میں اور دن کے مخصوص اوقات میں جمع ہوتی ہے جب فصل میں اوزون جذب کرنے کا امکان ہوتا ہے -اس تحقیقی مقالے کو ڈاکٹر ابوبکر محمد اور ڈاکٹر مودود خان کی نگرانی میں مکمل کیا گیا ۔ سینٹر فار واٹر انفارمیٹکس اینڈ ٹکنالوجی (ڈبلیو آئی ٹی) میں جودت نے مقالے کی تکمیل کے بعد 12 ماہ کے عرصے تک تحقیق کی- اس دورانیہ میں انہوں نے علاقائی سطح پر ریکارڈ شدہ مشاہدات کے ساتھ معاملے کی تحقیقات کے لئے طویل عرصے کی فیلڈ مہمات، سنسر مجمعے کی تنصیب ، دیکھ بھال ، اور ڈیٹا انیلسیز پر دل جمعی سے کام کیا۔

Abstract

The work in this dissertation is related to the development of novel techniques for the processing of signals defined on the sphere. Known as spherical signals, these are encountered in areas of science and engineering where the underlying geometry of the problem has a spherical configuration, e.g., in astronomy, cosmology, acoustics, medical imaging, geophysics and wireless communication. In most of these areas, acquired signals are almost always marred with unwanted, yet unavoidable noise due to different sources of interference, which places signal filtering and estimation at the heart of signal processing methods. In this context, the first part of the dissertation addresses the problem of signal estimation on the sphere in the presence of random anisotropic noise.  

Signal analysis on the sphere can be classified as global and local. In global analysis, signals are considered over the whole sphere and are most commonly represented in terms of spherical harmonic functions. However, the data may not be available, or may not be reliable, over some regions on the sphere, which invokes the need for localized signal representations. One such localized basis for accurate representation of signals over spherical regions, called the Slepian basis, is obtained through the solution of Slepian spatial-spectral concentration problem on the sphere. The second part of this dissertation is focused on the use of Slepian basis functions to support localized signal analysis on the sphere. Analytical formulation for the (i) surface integration of signals, and (ii) computation of Slepian basis functions, over simple spherical polygons is presented. Furthermore, a subset of Slepian basis is employed to formulate a new joint spatial-Slepian domain representation of spherical signals through the novel spatial-Slepian transform. A framework for generalized linear transformations in the joint spatial-Slepian domain is also presented, which is exemplified through optimal filtering on the sphere. 

The third part of this dissertation considers the use of Slepian basis functions for multiscale (multiresolution) analysis of spherical signals through hierarchical partitioning of the sphere into pixels of varying spatial extent. In this context, different sampling/partitioning methods on the sphere are reviewed and a Hierarchical Equal Area iso-Latitude iso-Longitude Pixelization (HEALLPix) scheme is proposed. Employing the formulation available in the literature, an overcomplete multiscale dictionary of Slepian functions is constructed. Additionally, a framework for analytical computation of Slepian functions for pixels generated using Hierarchical Equal Area iso-Latitude Pixelization (HEALPix) scheme is formulated, which facilitates the construction of another multiscale overcomplete dictionary of Slepian functions on the sphere. Both dictionaries are analyzed for the span and mutual coherence of their elements.  

Abstract: 

The electricity consumption in residential buildings is on the rise due to the increasing incorporation of heating and cooling loads along with the increasing penetration of electric vehicles. According to the Internal Energy Agency (IEA) word energy outlook 2020, the residential sectors account for 26.9% of the world’s final total electricity consumption. With changing house loads dynamics to DC, a significant amount of energy is lost due to AC to DC conversion. While the utility grid is AC in nature, it is high time to evaluate more efficient building level distribution to cater to the changing load dynamics, as highly efficient DC loads are replacing the conventional AC loads in modern buildings. Furthermore, these newer building architectures must efficiently incorporate green technologies such as solar photovoltaics (PV) and battery storage, generating and storing DC energy, respectively. So, this work evaluates DC-based residential architectures at multiple voltage levels. The work is also complemented by a techno-economic analysis of these systems with a stable energy management system for a typical DC home.  

For DC-only home systems, the most significant problem that hinders DC homes' immediate deployment is that unlike standardized AC distribution (110V, 60Hz or 220V, 50Hz), the existing DC distribution standards are disjoint, ranging from 48V to 380V. With the system’s efficiency due to distribution voltage selection at stake, it is essential to carefully select a suitable DC voltage level for the residential power network based on the typical load requirements and the variety of available generation. Hence, in this work, a framework for analyzing the impact of various DC voltage levels based upon the loss analysis is also developed. Various other aspects are also elaborated in the publications (cited below) emerging out of the thesis.  

Publication: 

J1)    Siraj K, Awais M, Khan HA, Zafar A, Hussain A, Zaffar NA, Jaffery SH. “Optimal power dispatch in solar‐assisted uninterruptible power supply systems”. International Transactions on Electrical Energy Systems. 2020 Jan;30(1):e12157. https://onlinelibrary.wiley.com/doi/abs/10.1002/2050-7038.12157 

J2)    Siraj K, Khan HA. “Dc distribution for residential power networks—a framework to analyze the impact of voltage levels on energy efficiency.” Energy Reports. 2020 Nov 1; 6:944-51. https://www.sciencedirect.com/science/article/pii/S2352484719313757 

C1)  Siraj K, Ahsan SM, Khan HA “Techno-economic Evaluation of Residential DC Power Systems on Multiple Distribution Voltages.” Accepted for 48th IEEE Photovoltaic Specialists Conference (PVSC 48), USA, June 2021. 

Abstract:

Smart urban buildings are being built as a synergetic deployment of renewable energy sources and electric vehicles. These buildings employ rooftop solar (depending on space constraints) to reduce grid dependence and as per our assessment have high profit margins by either contributing to the grid stability and/or having local aggregation for optimum routing of power. A large influx of rooftop solar photovoltaics (PV) deployments has been seen in buildings over the past decade due to lucrative netmetering schemes introduced by the various governments, including Pakistan. However, the selection of optimum technology for large-scale rooftop PV installations and the introduction of a comprehensive profitable architecture in smart buildings has remained an open question for the PV and smart grid research community, respectively, primarily due to the evolving space of the technology as well as changing regulations around feed-in tariffs (FiTs). Precisely, in the context of profit maximization and operational viability (technical) for smart buildings, it is needed to assess the a) optimum solar PV technology for rooftop deployments under constraints (low irradiance and partial shading conditions), b) lucrative business propositions for smart buildings (with solar PV, storage and/or charging infrastructure) and c)total harmonic distortion (THD) in current and voltage as a power quality parameter to gauge the stability of low voltage distribution network. Therefore, in this thesis all these research areas are explored leading to a novel and comprehensive framework for the profitable electricity sharing mechanism among multiple buildings.

Firstly, it is examined that under low irradiance and partial shade, the performance of thin film (TF) PV outshines the power output from crystalline silicon (c-Si) PV. However, due to the relatively low efficiency of TF PV modules, larger rooftop area is required to extract similar amount of power compared to c-Si. Secondly, to cope with the challenge of lowering the overall electricity tariff for the consumers, a novel business model is proposed for multiple buildings having bilateral contracts and connected with the grid, simultaneously. The proposed business architecture caters for the profit margins of each participating building, whether it has rooftop solar PV or not. The detailed results from the model signify that smart building (with solar and storage) earn up to 43 % of annual profits after incorporating installation costs of photovoltaic-battery system. Further, secondary buildings (without solar or storage) achieve 3 - 16 % of savings in the electricity costs based on different contracted loads and agreement tariffs.

Thirdly, the integration of electric vehicles in smart buildings enables added options of electricity trade for the prosumer (smart building) along with the optimized charging of electric vehicles. It allows the smart building to earn up to 87 % profit and secondary buildings electricity cost saving goes up to 41 %. To further facilitate the charging station integration in smart buildings, vehicle-to-everything (V2X) concept is introduced. The optimized charging and discharging of electric vehicles in the parking station of smart building enables the fleet of electric vehicles to earn savings up to 66 %. In addition, primary building (smart building) earns profit up to 62 % whereas the electricity cost savings of secondary buildings ranges from 2- 20%. Lastly, the technical evaluation of rooftop grid-connected PV systems with high diffusion of non-linear loads facilitates the integration of rooftop solar PV as a distributed energy resource in the low voltage networks. The results reveal that the installation of solar PV at alternate buses allows to operate within the limits for total harmonic distortion in voltage and current. Overall, this thesis presents a detailed techno-economic model for smart building(s) having bilateral contracts with secondary buildings and charging infrastructure for electric vehicles, along with a detailed assessment of the power quality parameters for grid-connected rooftop solar PV in low voltage networks.

Publications:

1. Ahsan, S., Niazi, K. A. K., Khan, H. A., & Yang, Y. (2018). Hotspots and performance evaluation of crystalline-silicon and thin-film photovoltaic modules. Microelectronics Reliability, 88, 1014-1018.

2. Ahsan, S. M., & Khan, H. A. (2019). Performance comparison of CdTe thin film modules with c-Si modules under low irradiance. IET Renewable Power Generation, 13(11), 1920-1926.

3. Ahsan, S. M., Khan, H. A., Hassan, N. U., Arif, S. M., & Lie, T. T. (2020). Optimized power dispatch for solar photovoltaic-storage system with multiple buildings in bilateral contracts. Applied Energy, 273, 115253.

4. Baig, M. Q., Khan, H. A., & Ahsan, S. M. (2020). Evaluation of solar module equivalent models under real operating conditions—A review. Journal of Renewable and Sustainable Energy, 12(1), 012701.

5. Arif, S. M., Lie, T. T., Seet, B. C., Ahsan, S. M., & Khan, H. A. (2020). Plug-In Electric Bus Depot Charging with PV and ESS and Their Impact on LV Feeder. Energies, 13(9), 2139.

6. Arif, S. M., Hussain, A., Lie, T. T., Ahsan, S. M., & Khan, H. A. (2020). Analytical Hybrid Particle Swarm Optimization Algorithm for Optimal Siting and Sizing of Distributed Generation in Smart Grid. Journal of Modern Power Systems and Clean Energy, 8(6), 1221-1230.

7. Ahsan, S. M., Khan, H. A., Ayyadi, S., Arif, S. M., & Lie, T. T. (2021, October). Optimized Power Dispatch for Solar-Storage System and Electric Vehicles with Multiple Buildings in Bilateral Contracts. In 2021 IEEE PES Innovative Smart Grid Technologies Europe (ISGT Europe) (pp. 1-5). IEEE.

8. Ahsan, S. M., Khan, H. A., Hussain, A., Tariq, S., & Zaffar, N. A. (2021). Harmonic Analysis of GridConnected Solar PV Systems with Nonlinear Household Loads in Low-Voltage Distribution Networks. Sustainability, 13(7), 3709.

9. Siraj, K., Ahsan, S. M., & Khan, H. A. (2021, June). Techno-economic Evaluation of Residential DC Power System for Multiple Distribution Voltages. In 2021 IEEE 48th Photovoltaic Specialists Conference (PVSC) (pp. 0858-0862). IEEE.

10. S. M. Ahsan, and H. A. Khan, " LV Harmonic Analysis of Single-Phase Rooftop Solar PV Systems with Non-Linear Loads," (Accepted in IEEE Green Tech, USA, 2022)

11. S. M. Ahsan, H. A. Khan, N.-u. Hassan, and S. Ayyadi," Optimized Power Dispatch for Smart Building(s) and Electric Vehicles with V2X Operation," (Submitted in Energy Reports).