Crimean-Congo haemorrhagic fever virus (CCHFV) is a tick-borne virus causing Crimean-Congo haemorrhagic fever (CCHF), a disease reported to have a high fatality rate in numerous countries. The virus ...is geographically widespread due to its vector, and numerous wild and domestic animals can develop asymptomatic infection. Serological and limited molecular evidence of CCHFV has previously been reported in
(the dromedary, or one-humped camel) in the United Arab Emirates (UAE). In this study, 238 camel samples were screened for CCHFV RNA where 16 camel samples were positive for CCHFV by RT-PCR. Analysis of full-length CCHFV genome sequences revealed a novel lineage in camels from the UAE, and potential reassortment of the M segment of the genome.
Camelpox is the most infectious and economically important disease of camelids that causes significant morbidity and mortality rates. Several live attenuated vaccines against
(CMLV) are produced ...worldwide by passaging field isolates in cell culture. Sequence of a high passage Saudi isolate of CMLV was previously found closely resembled Vaccinia virus (VACV).
To determine whether other high cell culture passage CMLV isolates are genetically resemble VACV and further to explore the possible mechanism of the resemblance.
We performed polymerase chain reaction and DNA sequence analysis of A-type inclusion body protein (ATIP), L1R, and open reading frame (ORF) 185 genes on different cell culture passage levels of a field isolate, two high passage vaccines, wild-type, and reference strains of CMLV.
We demonstrate that additional two high passage attenuated vaccine candidate from Sudan and UAE likewise contain sequences resembling VACV more than CMLV. Furthermore, sequence analysis of the ATIP gene of selected virus passages in cell culture revealed that the shift to VACV-like occurred between passage 11 and 20 and up to the 10th passage the genome still resembles wild-type virus. This observation was further confirmed by recombination analysis which indicated recombination events at ATIP and ORF185 genes occurred at higher passages.
We confirmed that the cell culture passage CMLV turns to resemble VACV after cell culture passage and concluded that the resemblance may not be a result of contamination or misidentification as previously thought but could be due to recombination events that occurred during the passage process.
Despite a steady increase in camel husbandry worldwide, pathology of camel diseases is still relatively under-investigated. Clinical hematuria is generally indicative of either acute or chronic ...urogenital inflammations, traumatic calculous injuries, cancers, corrosive poisonings. Infectious agents are not typically implicated in urinary tract infection of camels.
This study aims to explore possible causes in camels clinically suffered from acute febrile disease with severe hematuria.
To achieve aims of the study culturing of urine samples, microscopic examination for detection of blood parasites, phenotypic and genotypic characterization for the identification of isolated bacteria were followed.
Conventional bacteriology enabled identification of Salmonella enterica subsp. enterica serovar typhimurium which further genotyped by 16S rRNA gene sequencing. Microscopic examination of Giemsa stained blood smears from both infected dromedary camels revealed the presence of pleomorphic Theileria piroplasms. The results suggest that the clinical symptoms were as coinfection induced by salmonellosis and theileriosis.
Given these remarkable findings, further research should aim to better characterize the opportunistic pathogens associated with camel theileriosis, as well as to determine other possible infectious agents of the camel urinary tract.
This study was conducted to evaluate the use of Brucellergene skin test (BST) for the diagnosis of Brucellosis in camels (
) in comparison with Rose Bengal test (RBT) and competitive enzyme-linked ...immunosorbent assay (c-ELISA). A total of 68 apparently healthy adult dromedary camels of either gender from three different geographical locations of Abu Dhabi Emirate, United Arab Emirates (UAE), were included in the study. The skin test was applied on two shaved areas at the middle of the neck: one for the test and the other area was injected with normal saline as a control. Reading was done 72 h postinjection. Results were subjected to Bayesian analysis to assess the test performances in camels. The model estimated the following sensitivity and specificity median values: BST: Se = 70.72%, Sp = 98.82%; RBT: Se = 93.27%, Sp = 97.79%; and c-ELISA: Se = 94.78%, Sp = 98.48%. As the BST investigated in this study proved to be a highly specific test, we propose using it as a confirmatory test in camels particularly when the serological tests give doubtful results on individual animals.
Serological tests may represent an essential tool for the diagnosis of camel brucellosis; however, concerns arise in the scientific community regarding the direct transposition from cattle and small ...ruminants without adequate validation. The present study was made to compare four serological tests for the diagnosis of brucellosis in dromedary camels (Camelus dromedarius). In terms of sensitivity, our results show that the Immunochromatographic Test (ICT) shows the higher value of sensitivity, 98.67% (95% Confidence Level (C.L): 94.36%-99.99%), followed by the Fluorescence Polarization Assay (FPA) with 95.05% (95% C.L: 88.23%-99.51%), then the Competitive Enzyme-Linked Immunosorbent Assay (c-ELISA) with 94.94% (95% C.L: 88.25%-99.45%) and, finally, the Rose Bengal Test (RBT) with 68.95% (95% C.L: 56.55%-80.69%), which is the only test showing a significantly lower sensitivity compared to the others. On the other hand, our study revealed no significant difference in terms of specificity between all the tests under study, with a range from 99.06% (95% C.L: 98.34%-99.64%) for the ICT to 99.92% (95% C.L: 99.64%-100%) for the RBT. The ICT was found to be comparable in terms of sensitivity and specificity with the most commonly used tests for camel brucellosis. The results of the present study are of paramount importance for designing surveillance and control measures for brucellosis in camel populations.
Fault-current handling capability of the modular multilevel converters (MMCs) under dc-cable short-circuit conditions is a major concern for the MMC applications on the high-voltage direct-current ...(HVDC) transmission systems, where the MMCs based on half-bridge submodules (SMs) cannot block the fault currents to protect the converter devices. In this paper, a comprehensive review for the fault-ride-through capability of the HVDC transmission systems based on the MMCs adopting different SM schemes is presented, where the MMCs can block the fault currents and compensate the reactive currents to the electric grid during the dc faults. An analysis of the dc short-circuit faults in the MMC is introduced and then the operation principle of different SM circuits building the MMC for blocking the fault currents is highlighted. The fault-tolerant operation of these MMC schemes as static synchronous compensator to enhance the ac grid stability during the dc faults is also investigated. A comparison in terms of investment cost, loss, volume, and controllability for various MMC topologies is performed. Comprehensive simulation results for the most promising topologies of the MMC with a capability of fault-ride through under dc-fault conditions are finally presented.
The study of power flow analysis for microgrids has gained importance where several methods have been proposed to solve these problems. However, these schemes are complicated and not easy to ...implement due to the absence of a slack bus as well as the dependence of the power on frequency as a result of the droop characteristics. This paper proposes simple and effective modifications to the conventional method (Newton Raphson) to compute the power flow for microgrids. The presented method provides a simple, easy to implement, and accurate approach to solve the power flow equations for microgrids. The proposed method is applied to two test systems: a 6-bus system and a 38-bus system. The results are compared against simulation results from PSCAD/EMTDC which validate the effectiveness of the developed method. The proposed technique can be easily integrated in current commercially available power system software and can be applied for power system studies.
A Type-3 PLL for Single-Phase Applications Bamigbade, Abdullahi; Khadkikar, Vinod; Hosani, Mohamed Al
IEEE transactions on industry applications,
2020-Sept.-Oct., 2020-9-00, 20200901, Letnik:
56, Številka:
5
Journal Article
Recenzirano
This article proposes an effective solution by means of gain and phase-lead compensations to overcome the challenges of instability and slow dynamic performance exhibited by single-phase type-3 ...phase-locked loops (PLLs). By considering a single-phase second-order generalized integrator based type-3 PLL, a detailed design guideline is provided in choosing the PLL's parameters. Stability analysis of the designed PLL reveals that its finite gain margin causes PLL instability under severe voltage dip, while its limited phase margin results in poor dynamics. Therefore, gain compensation is carried out within a limited region such that the PLL's stability limit is not exceeded, while phase-lead compensation is employed to enhance the PLL's damping. When both modifications are incorporated within the PLL loop, the PLL's speed of estimation is improved significantly when compared with those of existing solutions applied to type-3 PLLs and the response obtained is comparable to that of a type-2 PLL. The performance evaluation of the proposed solution is carried out by experimental comparison with a standard single-phase type-3 PLL, a type-3 PLL with the amplitude normalization system, a phase feed-forward type-3 PLL, a dual-loop type-3 PLL, and a type-2 PLL.
This paper proposes an energy management strategy (EMS) of a reconfigurable grid-tied hybrid ac/dc microgrid (HMG) architecture for commercial building (CB) applications. This HMG architecture ...consists of a multi-mode configuration (MMC) with renewable-based distributed generators (DGs), energy storages (ESs), and genset. The main advantage of this architecture is its capability to reconfigure its structure based on the predicted building load power (BLP) and renewable-based DGs power. However, minimizing the building electricity cost (BEC) and maximizing the reliability index (RI) of a reconfigurable grid-tied HMG architecture is a challenging task due to the stochastic behaviors of BLP and renewable-based DGs power. In this context, the BLP and renewable-based DGs behaviors are modeled using an artificial neural network approach to predict future time slot values. Then, system level models are developed for HMG energy sources and grid-tied converters/switches. Furthermore, BEC and RI models are developed based on the dynamic pricing of grid/HMG electricity cost and supplied energy. Then, an EMS is proposed for the developed reconfigurable grid-tied HMG architecture, which consists of a two-stage control strategy, i.e., stage I and stage II. Stage I control strategy minimizes BEC and maximizes RI using multi-objective particle swarm optimization (MOPSO) and MMC. Stage II control strategy generates control signals for HMG energy sources, converters, and grid-tied converters/switches based on stage I reference signals. Historical data is used to demonstrate the effectiveness of the proposed EMS for a reconfigurable grid-tied HMG architecture. Through numerical simulation studies, it is shown that the proposed EMS is capable of reducing BEC and increasing RI by concurrently enabling MMC of a reconfigurable grid-tied HMG architecture.
Phase-locked loops (PLLs) are widely used for the synchronization of power electronic based equipment due to their ease of digital implementation and satisfactory response. This article focuses on a ...single-phase PLL to enhance its performance under distorted supply voltage condition. In most single-phase PLLs, the loop filter used within the control loop cannot completely reject low-order harmonics. Thus, the distortion in supply voltage significantly affects the frequency and phase estimations, both in steady-state and dynamic conditions. To overcome these problems, this article proposes a type-1 frequency-fixed frequency-locked loop (FLL). Generally, when the frequency is fixed in a PLL or FLL, the estimated variables (frequency and phase) suffer from double-frequency oscillation and phase offset whenever the system experiences any frequency variation. In the proposed work, a modified low-pass filter with notch characteristics is used to reject the double-frequency oscillation while the phase offset error is compensated by adding the linearized phase error to the estimated phase angle. Furthermore, a selective harmonic filtering technique is incorporated to improve the disturbance rejection capability under distorted conditions. These advantages make the proposed FLL robust for grid synchronization of single-phase converters. Experimental results are provided to verify the performance of the proposed FLL.
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