2020 IEEE 29th International Symposium on Industrial Electronics (ISIE)
This paper proposes an online fault localization method for low voltage DC microgrids. This metho... more This paper proposes an online fault localization method for low voltage DC microgrids. This method is based on Artificial Neural Network (ANN) and only requires real-time measurements of a local power converter to locate a fault. During a DC fault, the current component fed by the AC grid can contribute to time-variant non-linearity, which is undesirable to the development of the data-driven method. A novel real-time scheme is thus proposed to exclude such components from DC fault current. The principle of the scheme is introduced and illustrated with time-domain analysis. The effectiveness is verified by case studies of locating a DC fault in a radial DC network fed by a 3-phase voltage source converter.
Antibiotic resistance is not the story of the future but a reality today. Bacterial resistance to... more Antibiotic resistance is not the story of the future but a reality today. Bacterial resistance to antibiotics can be conferred by several mechanisms, including the overexpression of dedicated efflux pumps, some of them belonging to the ABC (“ATP-binding cassette”) transporters superfamily. ABC transporters are ubiquitous proteins that use ATP hydrolysis to pump a wide range of substrates. They are also responsible for the development of MDR (“MultiDrug Resistance”) phenotypes in cancer cells and pathogenic microorganisms.The bacterial ABC exporter BmrA (“Bacillus multidrug resistance ATP”), is structurally and functionally close to ABCB1, a human transporter involved in MDR phenotypes in cancer cells. Together with extensive knowledge in its overexpression and purification, BmrA is a useful archetypical transporter to gain information on the functioning of multidrug ABC transporters. Our goal is to decipher the conformational changes associated with drug transport.We showed that Bmr...
Study of the conformational states of a bacterial multidrug ABC transporter BmrA
La résistance aux antibiotiques est une réalité à laquelle nous devons faire face. La résistance ... more La résistance aux antibiotiques est une réalité à laquelle nous devons faire face. La résistance bactérienne aux antibiotiques peut être conférée par plusieurs mécanismes, dont la surexpression de pompes à efflux, certaines appartenant à la superfamille des transporteurs ABC (“ATP-binding cassette”). Les transporteurs ABC sont des protéines omniprésentes qui utilisent l'hydrolyse de l'ATP pour pomper une large gamme de substrats. Ils sont également responsables du développement des phénotypes de résistance à de multiple drogues dans les cellules cancéreuses et les microorganismes pathogènes.L'exportateur bactérien ABC BmrA (“Bacillus multidrug resistance ATP”), est homologue à ABCB1, un transporteur humain impliqué dans les phénotypes de résistance dans les cellules cancéreuses. Avec une connaissance approfondie de sa surexpression et de sa purification, BmrA est un archétype utile pour obtenir des informations sur le fonctionnement des transporteurs ABC de multiples drogues. Notre objectif est de déchiffrer les changements conformationnels associés au transport des médicaments.Nous avons montré que BmrA existe dans au moins deux conformations différentes, dans des micelles de détergent ou reconstitué dans des nanodisques. En l'absence de ligand (forme apo), différentes partie de BmrA fixe rapidement du deutérium comme le montre l'échange hydrogène deutérium couplé à la spectrométrie de masse (HDX-MS). La forme piégée par l'ADP induite par le vanadate montre une grande protection globale contre l'incorporation de deutérium. De plus, il a été observé que BmrA dans les nanodisques présente un profil de deutération différent en présence de médicament, indicatif d'une nouvelle conformation intermédiaire. De plus, en utilisant deux mutants affectés dans différentes étapes du cycle catalytique, il a été montré comment BmrA change de conformations au cours du cycle d'export des médicaments. Les résultats obtenus à partir de la diffusion de neutrons aux petits angles (SANS), brossent un tableau similaire et renforcent les résultats obtenus sur le cycle catalytique de BmrA.Ces résultats conduisent à une meilleure compréhension des changements de conformation de BmrA qui s’opèrent pour permettre le phénotype de résistance aux médicaments.Antibiotic resistance is not the story of the future but a reality today. Bacterial resistance to antibiotics can be conferred by several mechanisms, including the overexpression of dedicated efflux pumps, some of them belonging to the ABC (“ATP-binding cassette”) transporters superfamily. ABC transporters are ubiquitous proteins that use ATP hydrolysis to pump a wide range of substrates. They are also responsible for the development of MDR (“MultiDrug Resistance”) phenotypes in cancer cells and pathogenic microorganisms.The bacterial ABC exporter BmrA (“Bacillus multidrug resistance ATP”), is structurally and functionally close to ABCB1, a human transporter involved in MDR phenotypes in cancer cells. Together with extensive knowledge in its overexpression and purification, BmrA is a useful archetypical transporter to gain information on the functioning of multidrug ABC transporters. Our goal is to decipher the conformational changes associated with drug transport.We showed that BmrA exists in at least two different conformations, in detergent micelles or when reconstituted in nanodiscs. In the absence of ligand (apo form), BmrA gets quickly exchanged with deuterium as shown by Hydrogen Deuterium Exchange Coupled to Mass Spectrometry (HDX-MS). The vanadate-induced ADP trapped form shows a large overall protection against deuterium incorporation. Moreover, it was observed that BmrA in nanodiscs shows a different deuteration profile in the presence of drug, indicative of a new intermediate conformation. In addition, using two different catalytic mutants of BmrA, that are trapped in two opposite conformations of the catalytic cycle, it was shown how BmrA changes conformations during the drug export cycle. The results obtained from Small Angle Neutron Scattering (SANS), on WT BmrA and the mutants, paint a similar picture and strengthen the results obtained on the catalytic cycle of BmrA.These results could potentially lead to a better understanding of the structural basis of MDR
Multidrug ABC transporters translocate drugs across membranes by a mechanism for which the molecu... more Multidrug ABC transporters translocate drugs across membranes by a mechanism for which the molecular features of drug release are so far unknown. Here, we resolved three ATP-Mg 2+ –bound outward-facing conformations of the Bacillus subtilis (homodimeric) BmrA by x-ray crystallography and single-particle cryo–electron microscopy (EM) in detergent solution, one of them with rhodamine 6G (R6G), a substrate exported by BmrA when overexpressed in B. subtilis . Two R6G molecules bind to the drug-binding cavity at the level of the outer leaflet, between transmembrane (TM) helices 1–2 of one monomer and TM5′–6′ of the other. They induce a rearrangement of TM1–2, highlighting a local flexibility that we confirmed by hydrogen/deuterium exchange and molecular dynamics simulations. In the absence of R6G, simulations show a fast postrelease occlusion of the cavity driven by hydrophobicity, while when present, R6G can move within the cavity, maintaining it open.
Low Voltage DC Microgrid Protection System - A Review
2018 53rd International Universities Power Engineering Conference (UPEC), 2018
Direct Current (DC) Microgrids protection and operational issues have become a matter of greater ... more Direct Current (DC) Microgrids protection and operational issues have become a matter of greater concern with the growth in DC distribution market. Different protection schemes for detecting, locating and isolating faults have been studied on several systems under various conditions. This paper presents the state-of-the-art of protection schemes developed for the DC microgrid with a comprehensive evaluation on LVDC systems and their protection. Further, the work compares different fault locating techniques with an emphasis on their complexity level considering the time constraint for operating the protective devices for fault isolation. The existing standards for low voltage DC systems are also presented in this paper.
Figure 1. Different temporal distortion strategies for animated transitions. Solid shapes show or... more Figure 1. Different temporal distortion strategies for animated transitions. Solid shapes show original positions, faded shapes show ending positions. In this paper, we address this lack of empirical data by comparing object tracking performance in visually cluttered animations under different temporal distortion strategies, and show how effective these strategies are for important lowinria-00556177,
Multidrug ABC transporters translocate drugs across membranes by a mechanism for which the molecu... more Multidrug ABC transporters translocate drugs across membranes by a mechanism for which the molecular features of drug release are so far unknown. Here, we resolved two ATP-Mg2+-bound outward-facing (OF) conformations of the Bacillus subtilis (homodimeric) BmrA, one by X-ray crystallography without drug, and another by single-particle cryo-EM with rhodamine 6G (R6G). Two R6G molecules bind to the drug-binding cavity at the level of the outer leaflet, between transmembrane (TM) helices 1-2 of one monomer and TM5’-6’ of the other. R6G induces a rearrangement of TM1-2, highlighting a flexibility that was confirmed by H/D exchange and molecular dynamics simulations. The latter also shows a fast post-release occlusion of the cavity driven by hydrophobicity. Altogether, these data support a new swing mechanism for drug transport.
In this paper, three distinct distributed energy resources (DERs) modules have been built based o... more In this paper, three distinct distributed energy resources (DERs) modules have been built based on demand side management (DSM), and their use in power management of dwelling in future smart cities has been investigated. The investigated modules for DERs system are: incorporation of load shedding, reduction of grid penetration with renewable energy systems (RES), and implementation of home energy management systems (HEMS). The suggested approaches offer new potential for improving demand side efficiency and helping to minimize energy demand during peak hours. The main aim of this work was to investigate and explore how a specific DSM strategy for DER may assist in reducing energy usage while increasing efficiency by utilizing new developing technology. The Electrical Power System Analysis (ETAP) software was used to model and assess the integration of distributed generation, such as RES, in order to use local power storage. An energy management system has been used to evaluate a PV ...
Proceedings of the 10th International Conference on Smart Cities and Green ICT Systems, 2021
Smart Grid (SG), components with historical set of security challenges, becomes more vulnerable b... more Smart Grid (SG), components with historical set of security challenges, becomes more vulnerable because Information and Communications Technology (ICT) has its own share of problems while Cloud infrastructure adds yet another unpredicted layer of threats. Scalability and availability, which are strong aspects of the cloud platform making it attractive to users, also attracts security threats for the same reasons. The malware installed on single host offers very limited scope compared to attack magnitude that compromised Cloud platform can offer. Therefore, the strongest aspect of Cloud itself becomes a nightmare in Cloud-Based SG. A breach in such a delicate system can cause severe consequences including interruption of electricity, equipment damage, data breach, complete blackouts, or even life-threatening consequences. We mimic Denial-of-Service (DoS) attacks to demonstrate interruption of electricity in SG with open-source solution to co-simulate power and communication systems.
Distributed Energy Management Analysis for Microgrids
2021 56th International Universities Power Engineering Conference (UPEC), 2021
A key method of reducing energy usage and bills is collaborative demand management of buildings, ... more A key method of reducing energy usage and bills is collaborative demand management of buildings, and smart distribution networks using local renewable energy integrated sources. Emerging technologies such as the IOT (internet of things) can be integrated with grids, allowing bidirectional communication between customers and suppliers, while supporting remote management and monitoring of live energy usage. These systems create opportunities to deal with the distributed aggregation and control of distributed energy resources (DERs). Investigating how DERs are used at residential level in buildings such as smart houses reveal new possibilities relating to how the demand side can be made more efficient. In the long term, reducing energy demand during onpeak hours is a step towards creating a clean energy future. The primary goal of this paper is to observe and investigate how specific DSM strategies minimize energy consumption while maximizing efficiency with the use of new emerging technologies. A software called ETAP is used to analyse the integration of distributed generation such as renewable energy sources (RES) to utilize local power storage. In short, this is useful in providing flexibility to consumers. A PV system was also tested with an individual domestic load using an energy management system. This test examined how appliance energy usage can be reduced and shows why a management system is required to optimally utilize a PV system.
Power Management through Smart Grids and Advance Metering Infrastructure
2020 6th IEEE International Energy Conference (ENERGYCon), 2020
This paper describes the novel methodology for load management control system with continuous pow... more This paper describes the novel methodology for load management control system with continuous power supply feature in Pakistan. Smart meter and smart grids are the crucial components of this proposed power management system for diminishing the possibility of load shedding. Also, this methodology makes it possible to utilize the available energy resources more efficiently using internet of things to overcome the higher energy demands. The advanced metering infrastructure uses the power demand and supply information available from the communication network in managing the demand and supply, real time pricing problems and control over energy theft. Moreover, mathematical analysis supports the efficacy of proposed methodology.
overexpression of correctly folded membrane proteins is a fundamental prerequisite for functional... more overexpression of correctly folded membrane proteins is a fundamental prerequisite for functional and structural studies. one of the most commonly used expression systems for the production of membrane proteins is Escherichia coli. While misfolded proteins typically aggregate and form inclusions bodies, membrane proteins that are addressed to the membrane and extractable by detergents are generally assumed to be properly folded. Accordingly, GFP fusion strategy is often used as a fluorescent proxy to monitor their expression and folding quality. Here we investigated the functionality of two different multidrug ABC transporters, the homodimer BmrA from Bacillus subtilis and the heterodimer patA/ patB from Streptococcus pneumoniae, when produced in several E. coli strains with T7 expression system. strikingly, while strong expression in the membrane of several strains could be achieved, we observed drastic differences in the functionality of these proteins. Moreover, we observed a general trend in which mild detergents mainly extract the population of active transporters, whereas a harsher detergent like Fos-choline 12 could solubilize transporters irrespective of their functionality. Our results suggest that the amount of T7 RNA polymerase transcripts may indirectly but notably impact the structure and activity of overexpressed membrane proteins, and advise caution when using GFp fusion strategy.
Low voltage direct current (LVDC) distribution has gained the significant interest of research du... more Low voltage direct current (LVDC) distribution has gained the significant interest of research due to the advancements in power conversion technologies. However, the use of converters has given rise to several technical issues regarding their protections and controls of such devices under faulty conditions. Post-fault behaviour of converter-fed LVDC system involves both active converter control and passive circuit transient of similar time scale, which makes the protection for LVDC distribution significantly different and more challenging than low voltage AC. These protection and operational issues have handicapped the practical applications of DC distribution. This paper presents state-of-the-art protection schemes developed for DC Microgrids. With a close look at practical limitations such as the dependency on modelling accuracy, requirement on communications and so forth, a comprehensive evaluation is carried out on those system approaches in terms of system configurations， fault...
Biochimica et Biophysica Acta (BBA) - Biomembranes, 2019
Laurylmaltose neopentylglycol (LMNG) bears two linked hydrophobic chains of equal length and two ... more Laurylmaltose neopentylglycol (LMNG) bears two linked hydrophobic chains of equal length and two hydrophilic maltoside groups. It arouses a strong interest in the field of membrane protein biochemistry, since it was shown to efficiently solubilize and stabilize membrane proteins often better than the commonly used dodecylmaltopyranoside (DDM), and to allow structure determination of some challenging membrane proteins. However, LMNG was described to form large micelles, which could be unfavorable for structural purposes. We thus investigated its auto-assemblies and the association state of different membrane proteins solubilized in LMNG by analytical ultracentrifugation, size exclusion chromatography coupled to light scattering, centrifugation on sucrose gradient and/or small angle scattering. At high concentrations (in the mM range) LMNG forms long rods, and it stabilized the membrane proteins investigated herein, i.e. a bacterial multidrug transporter, BmrA; a prokaryotic analogous of the eukaryotic NADPH oxidases, SpNOX; an E. coli outer membrane transporter, FhuA; and the halobacterial bacteriorhodopsin, bR. BmrA, in the Apo and the vanadate-inhibited forms showed reduced kinetics of limited proteolysis in LMNG compared to DDM. Both SpNOX and BmrA display an increased specific activity in LMNG compared to DDM. The four proteins form LMNG complexes with their usual quaternary structure and with usual amount of bound detergent. No heterogeneous complexes related to the large micelle size of LMNG alone were observed. In conditions where LMNG form assemblies of large size, FhuA crystals diffracting to 4.0 Å were obtained by vapor diffusion. LMNG large micelle size thus does not preclude membrane protein homogeneity and crystallization.
The present study was aimed to assess the drinking water quality in District Dir Lower. During th... more The present study was aimed to assess the drinking water quality in District Dir Lower. During the study 33 water samples were collected from tube wells, dug wells and hand pumps and were analyzed for various physicochemical parameters. The results of evaluated parameters were compared against the standard guideline values recommended by the World Health Organization for drinking water. The parameters studied were variable in different ranges: pH 6.5-8.5, conductivity 680-3250 µs/cm, total solids 880-1250 mg/L, total hardness 260-615 mg/L, calcium hardness 150-340 mg/L, magnesium hardness 75-220 mg/L, alkalinity 190-420 mg/L, total dissolved solids 720-2010 mg/L, total suspended solids 1-35 mg/L, sodium 100-250 mg/L, chlorides 60-220 mg/L, nitrites 0.5-2 mg/L, sulphate 60-312 mg/L and potassium 1.9-21.3 mg/L. The results showed that the water parameters of the areas distant from river Panjkora falls within the WHO suggested permissible limits. The water quality of the riverine areas was somewhat disturbed for some parameters. It is suggested to monitor the water regularly to avoid further deterioration. The agricultural run offs and domestic wastes should be treated properly before disposing off. The waste products should be dumped to proper disposal sites instead of river banks.
Spatializing visual exploration: Transforming interactive visual analysis into spatial representations to aid sensemaking
Interactive visual analysis is the process of collecting insights about a dataset, while using on... more Interactive visual analysis is the process of collecting insights about a dataset, while using one or more interactive data visualization techniques. The process is based on the progressive refinement of an analyst\\u27s knowledge about the dataset, while using different interaction and analytical operations. In the presence of large and complex datasets, interactive visual analysis often places a high cognitive load on the analyst in terms of memory, perception, and reasoning. For example, when studying a complex dataset such as U.S. Census demographics, scientific co-authorship networks, or sales data, an analyst may have to simultaneously keep track of current insights, potential avenues for further investigation, and also the steps taken to reach a particular result. In this work, we propose a new methodology for automatically spatializing the individual steps, involved in an interactive visual analysis, onto a visual canvas allowing users to easily recall, reflect, and assess their exploration. In essence, instead of using a single viewport with a set of visual representations that change as the user selects, filters, and navigates in the data, we cause different interactions with visualization to spawn a new visualization where the desired change—such as a filter, annotation, or change of visualization technique—has been enacted. The benefit of this radical approach to spatializing individual steps is to externalize not just the data being visualized, but the exploration process itself used to analyze the data, and hence to aid sensemaking. To validate this new methodology, and to measure its efficiency for different types of datasets and visualization techniques, we develop various novel information visualization systems. In particular, we present the StackZoom application for performing multifocus exploration in skewed-aspect visual spaces, PolyZoom for achieving multiscale multifocus exploration in 2D visual spaces such as Google Maps, and the ExPlates technique for analyzing large multidimensional datasets in web browsers. We also discuss different experimental studies, performed to investigate the performance of these applications for various practical tasks such as navigation, search, and comparison. Results from the experiments confirm the effectiveness of the new applications and in general highlight the usefulness of spatializing interactive visual exploration
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Papers by Waqas Javed