The inaccessibility of a utility grid is the challenge for rural and remote areas. This work presents the application of solar photovoltaic (PV) integrated battery energy storage (BES) for rural area ...electrification. The addition of a BES at DC link, is realised by means of a DC–DC bidirectional converter. The BES is discharged/charged in accordance with the solar PV generation and load variations. This converter control also maintains the voltage for the maximum power point tracking (MPPT) with perturb and observe (P & O) control at the DC link. The voltage source converter (VSC) works by means of voltage control algorithm in a solar PV‐BES system. The system manages the power for the load network with frequency and voltage regulation by the non‐ideal discrete proportional and resonant controller (PR). The fundamental component from the load current, is acquired using an adaptive digital filter, which improves the power quality. The utilization of buck‐boost converter with an optimum BES rating as related to the system, when it is linked directly at the VSC DC link. The system's operations at steady state and dynamic circumstances i.e. solar insolation change and load variation, load disconnection, are authenticated with test results on a developed prototype.
This study presents the commercial solar PV plant (SPVP) operation, integrated into the low voltage (LV) AC network. The SPVP has the multi‐functional operational capability. It feeds the PV array ...generated power to loads and the AC network, while ensuring the power quality improvement at the point of common coupling (PCC) as per the IEEE std. 519, irrespective of the load characteristic (linear/nonlinear and balanced/unbalanced). The SPVP minimises the line losses in the AC network by recouping the load reactive power requirement locally. Moreover, the SPVP operates in either maximum power extraction (MPE) mode or constant power generation (CPG) mode, depending upon the rise in PCC voltage amplitude during the peak PV array power generation and low load demand condition. The SPVP switches between the MPE and the CPG modes during the high rise in PCC voltage amplitude and regulates the PV array generated power to protect itself and the load connected at PCC. In this study, an adaptive filter technique based on maximum correntropy criterion is used for the PQI, and the perturb and observe based algorithm is used for MPE. A simulation model and reduced rating hardware prototype are developed to validate the system's performance.
Active power filters (APFs) have been used to compensate harmonics, reactive current, and negative sequence fundamental frequency current drawn by nonlinear loads. The control of APF is the core ...issue for their proper operation. The flexibility of selective compensation embedded in the control scheme makes APF versatile for compensation of reactive power, harmonic currents, and unbalance in source currents and their combinations, depending upon the limited rating of voltage source inverter employed as APF. The proposed scheme utilizes neural network-based decomposition of the load current into positive and negative sequence fundamental frequency component, reactive component and harmonic components. The adaline-based current decomposer estimates the reference currents through tracking of unit vectors together with tuning of the weights. The implementation of the control scheme facilitates selective compensation which respects the limited rating of the APF. The simulated results using developed MATLAB model are presented and are validated by experimental results to depict the effectiveness of the proposed control method of APF
Cancer is a major cause of death worldwide, with an increasing number of cases being reported annually. The elevated rate of mortality necessitates a global challenge to explore newer sources of ...anticancer drugs. Recent advancements in cancer treatment involve the discovery and development of new and improved chemotherapeutics derived from natural or synthetic sources. Natural sources offer the potential of finding new structural classes with unique bioactivities for cancer therapy. Endophytic fungi represent a rich source of bioactive metabolites that can be manipulated to produce desirable novel analogs for chemotherapy. This review offers a current and integrative account of clinically used anticancer drugs such as taxol, podophyllotoxin, camptothecin, and vinca alkaloids in terms of their mechanism of action, isolation from endophytic fungi and their characterization, yield obtained, and fungal strain improvement strategies. It also covers recent literature on endophytic fungal metabolites from terrestrial, mangrove, and marine sources as potential anticancer agents and emphasizes the findings for cytotoxic bioactive compounds tested against specific cancer cell lines.
Microorganisms associated with medicinal plants are of interest as the producers of important bioactive compounds. To date, the diversity of culturable endophytic actinomycetes associated with ...medicinal plants is in its initial phase of exploration. In this study, 42 endophytic actinomycetes were isolated from different organs of seven selected medicinal plants. The highest number of isolates (n = 22, 52.3%) of actinomycetes was isolated from roots, followed by stems (n = 9, 21.4%), leaves (n = 6, 14.2%), flowers (n = 3, 7.1%), and petioles (n = 2, 4.7%). The genus Streptomyces was the most dominant among the isolates (66.6%) in both the locations (Dampa TRF and Phawngpuii NP, Mizoram, India). From a total of 42 isolates, 22 isolates were selected for further studies based on their ability to inhibit one of the tested human bacterial or fungal pathogen. Selected isolates were identified based on 16S rRNA gene analysis and subsequently the isolates were grouped to four different genera; Streptomyces, Brevibacterium, Microbacterium, and Leifsonia. Antibiotic sensitivity assay was performed to understand the responsible antimicrobials present in the isolates showing the antimicrobial activities and revealed that the isolates were mostly resistant to penicillin G and ampicillin. Further, antimicrobial properties and antibiotic sensitivity assay in combination with the results of amplification of biosynthetic genes polyketide synthase (PKS-I) and non-ribosomal peptide synthetase (NRPS) showed that the endophytic actinomycetes associated with the selected medicinal plants have broad-spectrum antimicrobial activity. This is the first report of the isolation of Brevibacterium sp., Microbacterium sp., and Leifsonia xyli from endophytic environments of medicinal plants, Mirabilis jalapa and Clerodendrum colebrookianum. Our results emphasize that endophytic actinomycetes associated with medicinal plants are an unexplored resource for the discovery of biologically active compounds.
This article proposes a reliable and cost-effective solution of water pumping system for the off-grid community, where the grid supply is not available. The designed system uses an 8/6 pole, ...four-phase switched reluctance motor (SRM) with a midpoint converter as a drive to pump the water. A three-level boost converter (TLBC) is used as an intermediate power conversion stage between the solar photovoltaic (PV) array and motor-pump. The TLBC has many benefits such as low voltage stress across devices, small inductor size, and ability to operate with a wide voltage range, which make the proposed system highly efficient and cost-effective. An efficient control technique is developed for the designed system, which simultaneously maximizes the PV array power and equalizes the voltages across split capacitors of a midpoint converter under all working conditions. An online flux optimization with a single-pulse mode of the SRM drive is developed and implemented. The developed control scheme eliminates the need of any phase current sensor, and the motor speed is fully governed by the available PV array power. This article proposes a new technique to emulate the characteristics of centrifugal water pump using a dc generator. This technique provides a simple solution to test the centrifugal solar pumps in the laboratory. The system under study is simulated in MATLAB/Simulink, and its different responses are examined under all possible working conditions. The simulated results are authenticated by the test results obtained through a developed prototype in the laboratory.
Biotic stresses in plants have a significant impact on agricultural productivity. In the present study, in vivo experiments were conducted to determine the physiological responses of tomato (Solanum ...lycopersicum L.) seedlings by inoculation with an endophytic actinobacterium, Streptomyces thermocarboxydus isolate BPSAC147 under greenhouse conditions. Further, photochemical quantum yield of photosystem II (PSII) (Fv/Fm), photochemical quenching (qP) and non-photochemical (NPQ) were calculated in seedlings inoculated with S. thermocarboxydus (T1) and were compared with control (T0) plants. Furthermore, the electron transport rate (ETR) of PSII exhibited a significant increase in T1 plants, relative to T0 plants. These results indicate that inoculation of tomato seedlings with S. thermocarboxydus had a positive effect on the process of photosynthesis, resulting in enhanced chlorophyll fluorescence parameters due to increased ETR in the thylakoid membrane. GC-MS analysis showed significant differences in the volatile compounds in the different treatments performed under greenhouse conditions. The present study suggests that S. thermocarboxydus can be used as new biocontrol agent to control Fusarium wilt in tomato crops and enhance productivity by enhancing photosynthesis.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
This work deals with the development of an efficient and reliable solar photovoltaic‐fed water pump with a battery energy storage (BES). This system ensures a continuous and rated supply of water in ...all working conditions. A new control logic for BES is developed, which significantly improves the overall response of the system. The support of the battery as a backup source is obtained through a bidirectional DC‐DC converter. Both the charging/discharging control and maximum power tracking of the solar panel are achieved through this bidirectional converter, whereas the voltage asymmetry compensation across split capacitors at DC link and motor drive controls are supervised by switched reluctance motor converter. The performance of the present scheme is examined through both simulated and experimental responses and is found adequate under all operational scenarios.
Endophytic fungi associated with medicinal plants are reported as potent producers of diverse classes of secondary metabolites. In the present study, an endophytic fungi, Aspergillus clavatonanicus ...strain MJ31, exhibiting significant antimicrobial activity was isolated from roots of Mirabilis jalapa L., was identified by sequencing three nuclear genes i.e. internal transcribed spacers ribosomal RNA (ITS rRNA), 28S ribosomal RNA (28S rRNA) and translation elongation factor 1- alpha (EF 1α). Ethyl acetate extract of strain MJ31displayed significant antimicrobial potential against Bacillus subtilis, followed by Micrococccus luteus and Staphylococcus aureus with minimum inhibitory concentrations (MIC) of 0.078, 0.156 and 0.312 mg/ml respectively. In addition, the strain was evaluated for its ability to synthesize bioactive compounds by the amplification of polyketide synthase (PKS) and non ribosomal peptide synthetase (NRPS) genes. Further, seven antibiotics (miconazole, ketoconazole, fluconazole, ampicillin, streptomycin, chloramphenicol, and rifampicin) were detected and quantified using UPLC-ESI-MS/MS. Additionally, thermal desorption-gas chromatography mass spectrometry (TD-GC-MS) analysis of strain MJ31 showed the presence of 28 volatile compounds. This is the first report on A. clavatonanicus as an endophyte obtained from M. jalapa. We conclude that A. clavatonanicus strain MJ31 has prolific antimicrobial potential against both plant and human pathogens and can be exploited for the discovery of new antimicrobial compounds and could be an alternate source for the production of secondary metabolites.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The disturbances including harmonics, distortions, transients, fluctuations, and dc offsets in the grid voltages and uncertain load currents, are the most challenging issues in the scenario of ...renewable sources based energy generating systems integrated to the conventional grid. A three-phase, double stage, grid tied solar photovoltaic based distributed generating (SPVDG) system fulfilling multiple objectives, is presented using an adaptive digital disturbance estimator (DDE) and a peak power tracking scheme. The adaptive DDE has the detection proficiency of all the harmonics and lumped disturbances resulting fundamental component estimation of the periodic signals such as grid voltages and load currents. This system deals with objectives such as reactive power compensation, load balancing, peak solar power extraction, operation at grid voltage sags and swells, estimation of harmonics, dc offsets, disturbances, etc. and their elimination. Moreover, this system ensures the active power flow from the SPVDG system to the local loads as well as the grid through a three-phase voltage source converter (VSC). An adaptive technique is used to adjust the dc-link voltage with respect to the grid voltage variation(s) that is advantageous in terms of losses in the VSC. A Lyapunov function candidate is considered to estimate the gains of the disturbance estimator confirming its parameter convergence. Considering the aforementioned objectives, SPVDG system with the proposed DDE-based control scheme, is simulated using Matlab /Simulink environment and then practically implemented using a prototype developed in the laboratory to confirm its performance under steady and dynamic conditions.
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