Challenges and Opportunities for Wound Field Synchronous Generators in Future More Electric Aircraft

Electrical machines and drives keep moving away from traditional technologies such as brushed machines and wound field machines towards lighter, ‘easier to maintain’ machines. A very interesting aspect is that certain transport applications, especially the aerospace industry, still favour the classical wound field machine for its main generating system such as the Boeing 787. This paper focuses on investigating this particular trend by presenting a detailed overview of historical power generation systems on aircraft. This paper compares the current state of the art of wound field machines with other generator families. The results of this analysis are then projected into the needs of the electrical power generation and distribution system on aircraft. While power density is a major objective for any aerospace application, however the extra benefits associated with wound field systems are still essential in modern aircraft. The paper then focuses on the main challenges for improving power density of wound field machines. Recommendations, opportunities and improvements related to wound field machines are discussed. In conclusion, if robust designs for higher speed wound field generators were consolidated, it would be very probable that these classical machines might still be implemented on future MEA platforms

Pre-Absorbed Immunoproteomics: A Novel Method for the Detection of Streptococcus suis Surface Proteins

Streptococcus suis serotype 2 (SS2) is a zoonotic pathogen that can cause infections in pigs and humans. Bacterial surface proteins are often investigated as potential vaccine candidates and biomarkers of virulence. In this study, a novel method for identifying bacterial surface proteins is presented, which combines immunoproteomic and immunoserologic techniques. Critical to the success of this new method is an improved procedure for generating two-dimensional electrophoresis gel profiles of S. suis proteins. The S. suis surface proteins identified in this study include muramidase-released protein precursor (MRP) and an ABC transporter protein, while MRP is thought to be one of the main virulence factors in SS2 located on the bacterial surface. Herein, we demonstrate that the ABC transporter protein can bind to HEp-2 cells, which strongly suggests that this protein is located on the bacterial cell surface and may be involved in pathogenesis. An immunofluorescence assay confirmed that the ABC transporter is localized to the bacterial outer surface. This new method may prove to be a useful tool for identifying surface proteins, and aid in the development of new vaccine subunits and disease diagnostics

A lytic phage to control multidrug-resistant avian pathogenic Escherichia coli (APEC) infection

The inappropriate use of antibiotics has led to the emergence of multidrug-resistant strains. Bacteriophages (phages) have gained renewed attention as promising alternatives or supplements to antibiotics. In this study, a lytic avian pathogenic Escherichia coli (APEC) phage designated as PEC9 was isolated and purified from chicken farm feces samples. The morphology, genomic information, optimal multiplicity of infection (MOI), one-step growth curve, thermal stability, pH stability, in vitro antibacterial ability and biofilm formation inhibition ability of the phage were determined. Subsequently, the therapeutic effects of the phages were investigated in the mice model. The results showed that PEC9 was a member of the siphovirus-like by electron microscopy observation. Biological characterization revealed that it could lyse two serotypes of E. coli, including O1 (9/20) and O2 (6/20). The optimal multiplicity of infection (MOI) of phage PEC9 was 0.1. Phage PEC9 had a latent period of 20 min and a burst period of 40 min, with an average burst size of 68 plaque-forming units (PFUs)/cell. It maintained good lytic activity at pH 3-11 and 4-50°C and could efficiently inhibit the bacterial planktonic cell growth and biofilm formation, and reduce bacterial counts within the biofilm, when the MOI was 0.01, 0.1, and 1, respectively. Whole-genome sequencing showed that PEC9 was a dsDNA virus with a genome of 44379 bp and GC content of 54.39%. The genome contains 56 putative ORFs and no toxin, virulence, or resistance-related genes were detected. Phylogenetic tree analysis showed that PEC9 is closely related to E. coli phages vB_EcoS_Zar3M, vB_EcoS_PTXU06, SECphi18, ZCEC10, and ZCEC11, but most of these phages exhibit different gene arrangement. The phage PEC9 could successfully protect mice against APEC infection, including improved survival rate, reduced bacterial loads, and organ lesions. To conclude, our results suggest that phage PEC9 may be a promising candidate that can be used as an alternative to antibiotics in the control of APEC infection

Plant growth and their root development after inoculation of arbuscular mycorrhizal fungi in coal mine subsided areas

Abstract Coal mining often cause serious land degradation, soil erosion, and desertification affecting growth of the local vegetation, especially the roots. Arbuscular mycorrhizal fungi (AMF) inoculation is considered a potential biotechnological tool for mined soil remediation because mycorrhizal fungi could improve plant growth environment, especially under adverse conditions due to their good symbiosis. A field experiment was conducted to study the ecological effects of AMF (Funneliformis mosseae, Rhizophagus intraradices) on the growth of Amygdalus pedunculata Pall. and their root development in the regenerated mining subsidence sandy land. The reclamation experiment included four treatments: inoculation of Funneliformis mosseae (F.m), inoculation of Rhizophagus intraradices (R.i), combined inoculation of F.m and R.i and non-inoculated treatment. Root mycorrhizal colonization, plant height, crown width, soil moisture, root morphology and certain soil properties were assessed. The results showed that AMF improved the shoot and root growth of Amygdalus pedunculata Pall., and significantly increased root colonization after 1 year of inoculation. Available phosphorus content, activities of phosphatase as well as electrical conductivity in soil rhizosphere of all the three inoculation treatments were higher than that of the non-inoculated treatment. AMF increased the quantity of bacteria and fungi in soil rhizosphere compared with the non-inoculated treatment. Our study indicates that revegetation with AMF inoculum could influence plant growth and root development as well as soil properties, suggesting that AMF inoculation can be effective method for further ecological restoration in coal mine subsided areas

Molecular dynamics simulation study on impact of interface chemistry on pearlite mechanical response

The molecular dynamics (MD) simulation method was adopted to explore impact of interface chemistry on pearlite mechanical response of Bagaryatskii orientation relationship between ferrite and cementite. By changing terminal surface types of cementite at ferrite-cementite interface, this study analyzed influence of interface chemistry on pearlite peak stress and plastic deformation behavior, as well as strain transmission between two phases (ferrite and cementite) during stretching process. Two horizontal directions parallel to pearlite interface were considered as loading directions respectively. The results show pearlite will experience inelastic deformation due to atomic slip in ferrite phase. When terminal surface of cementite at interface is FeC-Fe, the atomic slip in ferrite is the most difficult to occur, and inelastic deformation shall be suppressed. At this time, pearlite produces the largest peak stress. Types of terminal surface and loading direction will affect slip systems activated in ferrite. Stretching along ${\left[100\right]}_{\theta }$ direction: for pearlite with Fe-FeC and Fe-Fe cementite terminal surfaces at interface, S1 ({112} 〈111〉) slip system in ferrite is activated. While terminal surface is FeC-Fe pearlite, what is activated is S2 slip system ({110} 〈111〉) in ferrite. Stretching along ${\left[010\right]}_{\theta }$ direction: regardless of types of terminal surface, slip systems activated are Type S2. Compared with S1 slip system, activation of S2 slip system makes is easier for plastic deformation in ferrite to pass through ferrite-cementite interface to the cementite

Study on parameters optimization of unmanned aerial vehicle and ecological remediation of buckwheat stained with DSE

The complex and changeable terrain, subsidence topography and land fissures of mining area in northern Shaanxi make it difficult for mechanical restoration of ecological environment. Based on M8A20A eight-rotor UAV platform, this study investigated the effects of the optimal parameters on aerial seeding, and the ecological restoration of buckwheat by DSE infection and aerial seeding. Results showed that the flight parameters had significant effects on the available width and uniformity of buckwheat seeds. The optimal parameters of aerial seeding includehigh speed, flight height of 2.5 m, flight speed of 4.0 m/s and operating distance of 6.0 m. Compared with the control group, plant height, ground diameter and above-ground biomass of the buckwheat infected with Dark Septate Endophytes(DSE)increased by 11%、25%、49%, respectively. In addition, the DSE infection could increase the SPADR and photosynthetic rate of buckwheat, promoting the root to grow and improving the yield and quality of buckwheat. This UAV aerial seeding combined with growth promotion of DSE infection could offer reference for ecological restoration of complex terrain in the western mining areas

Nonlinear Dynamic Responses of a Honeycomb Sandwich Plate Subject to Transverse Excitations

Nonlinear dynamic behaviors of a simply supported honeycomb sandwich plate subjected to the transverse excitations are investigated in this paper. Based on the classical thin plate theory and Von Karman large deformation theory, the governing equation of motion for the honeycomb sandwich plate is established by using the Hamilton principle. The nonlinear governing partial differential equation is discretized to the ordinary differential equations by differential quadrature method and then solved by Runge-Kutta-Fehlberg method. Based on the numerical simulations, combined with nonlinear dynamic theory, the influences of the frequency and amplitude of the transverse excitation are investigated respectively by using the bifurcation diagrams, Poincare maps and phase portraits. The results exhibit the existence of the period-1, period-2 and chaotic responses with the variation of the excitations, which demonstrate that those motions appear alternately