This paper proposes a simulated annealing (SA)-based global maximum power point tracking (GMPPT) technique designed for photovoltaic (PV) systems which experience partial shading conditions (PSC). ...The proposed technique is compared with the common perturb and observe MPPT technique and the particle swarm optimization method for GMPPT. The performance is assessed by considering the time taken to converge and the number of sample cases where the technique converges to the GMPP. Simulation results indicate the improved performance of the SA-based GMPPT algorithm, with arbitrarily selected parameters, in tracking to the global maxima in a multiple module PV system which experiences PSC. Experimental validation of the technique is presented based on PV modules that experience nonuniform environmental conditions. Additionally, studies regarding the influence of the key parameters of the SA-based algorithm are described. Simulation and experimental results verify the effectiveness of the proposed GMPPT method.
Microgrids gain popularity due to their economical and environmental benefits along with low power losses and smaller infrastructure. However, it has several operational challenges such as power ...quality, power system instability, reliability, and protection issues. Microgrid protection strategy is a prime issue for the reliable operation of the microgrid. The microgrid protection scheme must meet the essential conditions for grid-connected and islanded operational modes. This paper presents a comprehensive review and comparative analysis of protection schemes and their implementation challenges for different microgrid architectures with various operational requirements. The challenges associated with the implementation of microgrid protection schemes are identified and discussed in detail. Furthermore, various simulation studies have been conducted to demonstrate the microgrid protection challenges associated with different modes of operation. This paper presents key information to researchers and protection engineers to identify microgrid protection challenges and their mitigation approaches.
Electric Vehicles (EVs) are projected to be one of the major contributors to energy transition in global transportation due to their rapid expansion. High-level EVs integration into the electricity ...grid will introduce many challenges for the power grid planning, operation, stability, standards, and safety. Therefore, the wide-scale adoption of EVs imposes research and development of charging systems and EV supply equipment (EVSE) to achieve expected charging solutions for EV batteries as well as to improve ancillary services. Analysis of the status of EV charging technologies is important to accelerate EV adoption with advanced control strategies to discover a remedial solution for negative impacts and to enhance desired charging efficiency and grid support. This paper presents a comprehensive review of EV charging technologies, international standards, the architecture of EV charging stations, and the power converter configurations of EV charging systems. The charging systems require a dedicated converter topology, a control strategy, compatibility with standards, and grid codes for charging and discharging to ensure optimum operation and enhance grid support. An overview of different charging systems in terms of onboard and off-board chargers, AC-DC and DC-DC converter configuration, and AC and DC-based charging station architectures are evaluated. In addition, recent charging systems which are integrated with renewable energy sources are presented to identify the power train of modern charging stations. Finally, future trends and challenges in EV charging and grid integration issues are summarized as the future direction of the research.
Detecting cancer at an early stage is crucial for timely treatment and better chances of survival. This research focuses on a scanning method for detecting cancer by examining the nonlinear optical ...characteristics of blood plasma samples. The study used both cancerous and noncancerous plasma samples and presented the results statistically by utilizing an incident laser power-dependent nonlinear optical phase shift variable called ζ in the Z-scan technique. The results showed a clear difference between the cancerous and non-cancerous samples with an accuracy of 92%. Furthermore, the study suggests the potential for measuring the cancer staging from the cancerous plasma. The study also confirmed a significant difference in ζ for plasma samples undergoing chemotherapy. A red laser with high power (above 18mW) was used to avoid the involvement of fluorophores or other chemical reagents in the plasma samples during the measurement.
This paper presents a novel control strategy for the operation of a direct-drive permanent-magnet synchronous-generator-based stand-alone variable-speed wind turbine. The control strategy for the ...generator-side converter with maximum power extraction is presented. The stand-alone control is featured with output voltage and frequency controller that is capable of handling variable load. The potential excess of power is dissipated in the dump-load resistor with the chopper control, and the dc-link voltage is maintained. Dynamic representation of dc bus and small-signal analysis are presented. Simulation results show that the controllers can extract maximum power and regulate the voltage and frequency under varying wind and load conditions. The controller shows very good dynamic and steady-state performance.
Understanding the spatial variation of agricultural livelihood vulnerability to climate change is crucial for developing adaptation strategies in the future, something that has only been seldom done ...so far in developing economies like Bangladesh. To this end, we developed an integrated vulnerability index (IVI) based on the IPCC framework for analyzing and mapping the vulnerability of agricultural livelihoods in coastal Bangladesh. The IVI was calculated as a function of three components: exposure, sensitivity, and adaptive capacity. We used 45 indicators from nationally comparable and reliable datasets to conduct the research. Besides, a socio-economic livelihood vulnerability index (SELVI) was developed on the basis of sensitivity and adaptive capacity indicators and displayed in a scatter diagram in order to identify the socio-economically more vulnerable districts of coastal Bangladesh. A circumplex chart was used to disaggregate the normalized indices of sensitivity and adaptive capacity components, allowing the researcher to discover the factors that cause and mitigate the vulnerability. Using the IVI information, a vulnerability map was created that revealed that Patuakhali, Noakhali, Bhola, and Barguna districts in the exposed central coastal region were the topmost vulnerable districts, reflecting the fact that the agricultural livelihoods of 7.3 million people were highly vulnerable to the effects of climate change. The geographical diversity in salt intrusion, river-bank erosion, dependence ratio, crop yield, literacy, the density of physicians in the hospital, disaster-resistant houses, shelter facilities, and irrigated farming areas contributed to the diverse coastal agricultural livelihood vulnerability.
•Vulnerability of agricultural livelihood was assessed by using 45 biophysical, agro-ecological, and socio-economic variables.•The drivers of livelihood vulnerability were identified by the SELVI framework to suggest location-specific interventions.•Agricultural livelihoods of exposed coastal districts are more vulnerable than the interior coastal districts.•The exposure component had a greater influence on determining vulnerability status than sensitivity and adaptive capacity.
Smart grid is one of the major prospective candidates in the Industrial Internet of Things family that ensures smooth and efficient power distribution, restoration in times of emergency, and usage ...control for the consumers. Electric power generators contribute at the core of smart grid along with the transmission lines and transformers. Extensive research works are conducted to optimize different parameters such as efficient energy usage, automated demand response, and emergency grid failure recovery. However, the component status analysis of the electric generators within a smart grid is still in the nascent stage. In this paper, we propose a novel routing protocol for supervised device-data transfer from smart grid generators to the command and control center using wireless ad hoc and sensor networks. Our protocol assumes various sensor devices (temperature sensors, oil level sensor, turbine status sensors, etc.) to be employed on each generator due to their mechanical sophistication. Additionally, we introduce the ambient energy harvesting for the sensors energy replenishment to accommodate tolerable node outage. Our simulation results demonstrate promising outcome with respect to different key parameters such as message flow, energy consumption, outage frequency, remaining energy, and harvested energy.
Cassia occidentalis
L. is widely used in indigenous and traditional medicine, but its impact on multi-drug resistant (MDR) bacterial infections mostly remains unknown. Therefore, this study aimed to ...evaluate the
in vitro
antibacterial efficiency of methanol and ethyl acetate extracts of
C. occidentalis
L. leaves (MECOL and EAECOL) against multi-drug resistant
Pseudomonas aeruginosa
and to identify potential antibacterial agents through computational studies targeting the LasR protein. Initially, 82 compounds were identified using GC-MS analysis, and the functional groups were determined through FT-IR analysis. Both extracts of the plant exhibited dose-dependent antibacterial activity, with MICs of 104.16 ± 36.08 μg mL
−1
for MECOL and 83.33 ± 36.08 μg mL
−1
for EAECOL, and an MBC of 125 μg mL
−1
. Among the 82 compounds, 12 potential compounds were identified based on binding scores using molecular docking with the LasR protein and MM-GBSA analysis. Furthermore, screening for ADME properties, including physicochemical features, water solubility, lipophilicity, RO5 compliance, and toxicity, identified the top three compounds: methyl dihydrojasmonate, methyl benzoate, and 4a-methyl-4,4a,5,6,7,8-hexahydro-2(3
H
)-naphthalenone, which also demonstrated binding affinity with the active site residues of the LpxC protein of the bacteria. Additionally, molecular dynamics (MD) simulations confirmed the binding reliability of these three phytochemicals to LasR's active pocket, comparable to the protein native inhibitory ligands (C12-HSL). The study offers scientific support for the traditional use of
C. occidentalis
in treating bacterial infections, highlighting the potential of the three compounds as leads for developing LasR inhibitors to combat multi-drug resistant
P. aeruginosa
.
Avian infectious bronchitis (AIB) is a highly transmissible infection that affects the poultry industry globally. This study aims to isolate and characterize emerging strains of infectious bronchitis ...virus (IBV) from field samples of layer chickens in Bangladesh. A total of 108 samples (trachea, lung, and kidney) were taken from dead and sick layer chickens from 18 farms in 4 areas detecting outbreaks in Bangladesh. The samples were processed and inoculated in embryonated chicken eggs (ECEs) and finally screened by the trypsin-induced hemagglutination (THA) test. Using various techniques such as hemagglutination inhibition (HI), agar gel immuno-diffusion (AGID), virus neutralization test (VNT), reverse transcription-polymerase chain reaction (RT-PCR), and nucleotide sequencing, we were able to identify and confirm the isolated IBV viruses. The study also determined the hemagglutination (HA) pattern of isolated virus using avian and mammalian red blood cells. The pathogenicity of the isolated IBV was determined using embryonated chicken eggs and day-old chicks. The study found that 8 samples were positive for IBV using ECEs, and 4 were positive by the THA test. These isolates were confirmed using HI, AGID, and VN tests. S1 gene-based RT-PCR confirmed all four isolates as IBV, with the recent isolates belonging to the genotype-QX and being similar to IBV isolates from Thailand, Saudi Arabia, and India. The HA pattern of the recent isolates showed that the isolated IBV was virulent. The pathogenicity test also revealed that the four isolates were highly pathogenic. The study indicated that the prevalent genotype (QX) of the IBV strain is present in the layer chicken population of Bangladesh.
This paper presents a decentralized fault detection technique for power distribution systems with resonant grounding. The aim of this paper is to detect single phase to ground faults and identify the ...faulty feeder within three cycles of the fault occurrence. In the proposed technique, faults are first detected based on the neutral voltage displacement. The pre-fault and post-fault voltages (phase to ground) are then used to identify the faulty phase. Finally, the faulty feeder (as well as the faulty area of a long feeder) is identified from the relationship between the initial transient of the zero-sequence current and the faulty phase voltage just after the occurrence of faults. A signal processing tool called mathematical morphology is utilized to identify the faulty feeder. To identify the faulty feeder, it is also required to know the fault occurrence time that is estimated using the slope of the neutral voltage. The main feature of the proposed scheme is that this technique only uses voltage and current signals from the corresponding voltage transformers and current transformers. Therefore, it does not require communication among protection devices in the same or different feeders to identify the faulty feeder. The proposed technique also has the ability to distinguish the nature of faults, i.e., whether the faults are permanent or temporary. The effectiveness of the proposed scheme is tested, on an IEEE test system as well as on a practical test system, using MATLAB/SimPowerSystems. Simulation results show that the proposed technique can quickly detect the single phase to ground faults in a resonant grounding power distribution system and identify the faulty feeder. It is also capable of distinguishing faults from other disturbances. Moreover, it works under different compensation levels as well as for different fault inception angles.
PDF
