Study on Harmonic Resonance and Grid-Connected Control Technology of Doubly-Fed Wind Turbines

The development of clean energy has been paid more and more attention. The installed capacity of wind turbine is increasing, but wind turbine is prone to be affected by grid deformation as the stator of wind turbine is connected directly with power grid, and the power grid of wind farm is at the end of the whole grid, and its connection is weak. In order to reduce the influence of grid distortion on wind turbine, harmonic current suppression test was carried out on the doubly-fed wind power integration platform built based on the mathematical model of the wind power system using stator current harmonic control, and it was compared with the traditional current control method. No matter the rotational speed of the motor was subsynchronous or supersynchronous, the proposed method always had better performance in controlling harmonic current. Six times of pulse frequency of the electromagnetic torque could be effectively suppressed when the control strategy was switched from the traditional control method to the method which was put forward by this study under supersynchronous rotational speed. In conclusion, the method proposed in this paper can effectively suppress the influence of the harmonic voltage generated by the grid distortion on current in grid and improve the operation stability of doubly-fed wind motor

Nicotinic acid changes rumen fermentation and apparent nutrient digestibility by regulating rumen microbiota in Xiangzhong black cattle

Objective The aim of this study was to investigate the impact of dietary nicotinic acid (NA) on apparent nutrient digestibility, rumen fermentation, and rumen microbiota in uncastrated Xiangzhong black cattle. Methods Twenty-one uncastrated Xiangzhong black cattle (385.08±15.20 kg) aged 1.5 years were randomly assigned to the control group (CL, 0 mg/kg NA in concentrate diet), NA1 group (800 mg/kg NA in concentrate diet) and NA2 group (1,200 mg/kg NA in concentrate diet). All animals were fed a 60% concentrate diet and 40% dried rice straw for a 120-day feeding experiment. Results Supplemental NA not only enhanced the apparent nutrient digestibility of acid detergent fiber (p<0.01), but also elevated the rumen acetate and total volatile fatty acid concentrations (p<0.05). 16S rRNA gene sequencing analysis of rumen microbiota revealed that dietary NA changed the diversity of rumen microbiota (p<0.05) and the abundance of bacterial taxa in the rumen. The relative abundances of eight Erysipelotrichales taxa, five Ruminococcaceae taxa, and five Sphaerochaetales taxa were decreased by dietary NA (p< 0.05). However, the relative abundances of two taxa belonging to Roseburia faecis were increased by supplemental 800 mg/kg NA, and the abundances of seven Prevotella taxa, three Paraprevotellaceae taxa, three Bifidobacteriaceae taxa, and two operational taxonomic units annotated to Fibrobacter succinogenes were increased by 1,200 mg/kg NA in diets. Furthermore, the correlation analysis found significant correlations between the concentrations of volatile fatty acids in the rumen and the abundances of bacterial taxa, especially Prevotella. Conclusion The results from this study suggest that dietary NA plays an important role in regulating apparent digestibility of acid detergent fiber, acetate, total volatile fatty acid concentrations, and the composition of rumen microbiota

Relevance of JAK2V617F positivity to hematological diseases - survey of samples from a clinical genetics laboratory

<p>Abstract</p> <p>Background</p> <p>JAK2V617F is found in the majority of patients with Ph- myeloproliferative neoplasms (MPNs) and has become a valuable marker for diagnosis of MPNs. However, it has also been found in many other hematological diseases, and some studies even detected the presence of JAK2V617F in normal blood samples. This casts doubt on the primary role of JAK2V617F in the pathogenesis of MPNs and its diagnostic value.</p> <p>Methods</p> <p>In the present study, we analyzed JAK2V617F positivity with 232 normal blood samples and 2663 patient blood, bone marrow, and amniotic fluid specimens obtained from a clinical genetics laboratory by using a simple DNA extraction method and a sensitive nested allele-specific PCR strategy.</p> <p>Results</p> <p>We found JAK2V617F present in the majority (78%) of MPN patients and in a small fraction (1.8-8.7%) of patients with other specific hematological diseases but not at all in normal healthy donors or patients with non-hematological diseases. We also revealed associations of JAK2V617F with novel as well as known chromosomal abnormalities.</p> <p>Conclusions</p> <p>Our study suggests that JAK2V617F positivity is associated with specific hematological malignancies and is an excellent diagnostic marker for MPNs. The data also indicate that the nested allele-specific PCR method provides clinically relevant information and should be conducted for all cases suspected of having MPNs as well as for other related diseases.</p

A novel strategy for power sources management in connected plug-in hybrid electric vehicles based on mobile edge computation framework

This paper proposes a novel control framework and the corresponding strategy for power sources management in connected plug-in hybrid electric vehicles (cPHEVs). A mobile edge computation (MEC) based control framework is developed first, evolving the conventional on-board vehicle control unit (VCU) into the hierarchically asynchronous controller that is partly located in cloud. Elaborately contrastive analysis on the performance of processing capacity, communication frequency and communication delay manifests dramatic potential of the proposed framework in sustaining development of the cooperative control strategy for cPHEVs. On the basis of MEC based control framework, a specific cooperative strategy is constructed. The novel strategy accomplishes energy flow management between different power sources with incorporation of the active energy consumption plan and adaptive energy consumption management. The method to generate the reference battery state-of-charge (SOC) trajectories in energy consumption plan stage is emphatically investigated, fast outputting reference trajectories that are tightly close to results by global optimization methods. The estimation of distribution algorithm (EDA) is employed to output reference control policies under the specific terminal conditions assigned via the machine learning based method. Finally, simulation results highlight that the novel strategy attains superior performance in real-time application that is close to the offline global optimization solutions

α-SMA gene and protein expression was detected in intramuscular CD45^-/CD31^-/α7-integrin^-/GFP (Col1)⁺ fibrogenic cells.

<p><b>The α-SMA expression level was low but the collagen expression level was high in the <i>ColI-GFP/mdx</i></b>^{<b><i>5cv</i></b>}<b>diaphragm fibrogenic cells as compared with the <i>ColI-GFP/mdx</i></b>^{<b><i>5cv</i></b>}<b>quadriceps fibrogenic cells. The α-SMA protein expression was low in the fibrogenic cells from <i>ColI-GFP/mdx</i></b>^{<b><i>5cv</i></b>}<b>diaphragm as compared with those from fibrotic lungs</b>. (A) qRT-PCR of α-SMA gene using fibrogenic cells freshly sorted from diaphragm (Dia) and quadriceps (Qua) muscles of the <i>ColI-GFP/mdx</i>^<i>5cv</i> mice at 3 months. (B) Western blot of α-SMA protein using fibrogenic cells (FB) freshly sorted from diaphragm (Dia) and quadriceps (Qua) muscles of the <i>ColI-GFP/mdx</i>^<i>5cv</i> (<i>mdx</i>^<i>5cv</i>) mice at 3 months (a, b), from injured muscles at of the <i>ColI-GFP/Ccr2</i>^<i>-/-</i> mice (<i>Ccr2</i>^<i>-/-</i>) day 7 post-injury (a), and from fibrotic lungs (Lung FB) with fibrosis induced by bleomycin in the <i>ColI-GFP</i> mice (b). NIH3T3 fibroblasts were used as a positive control, and intramuscular CD45⁺/F4/80⁺/Siglec F^- macrophages (MP) were used as a negative control. Data presented represents 3 independent experiments. (C) q-RT-PCR of ECM genes using fibrogenic cells freshly sorted from diaphragm (Dia) and quadriceps (Qua) muscles of the <i>ColI-GFP/mdx</i>^<i>5cv</i> mice at 3 months. Fold change refers to the comparison to the quadriceps fibrogenic cells of the <i>ColI-GFP/mdx</i>^<i>5cv</i> mice (A, C). Each experiment was independently performed twice. Each time, 10 mice were used for fibrogenic cell isolation and RNA or protein preparation. *<i>p</i><0.05; **<i>p</i><0.01.</p

Calibration for discrete element modelling of railway ballast: A review

The discrete element method (DEM) has been confirmed as an effective numerical method for modelling railway ballast, and successfully used to analyse a wide range of ballast-related applications (e.g. geomaterials). However, there still exists some aspects under development. Among them, the model calibration can be the most significant one (morphology, degradation and contact model). Because reliable and accurate results can be obtained only when the parameters are carefully selected. Therefore, diverse DEM applications and developments in railway ballast are critically reviewed. Furthermore, the model calibration methods are discussed. This is able to help future researchers improve the existing calibration methods, further, build more accurate, standardised and validated DEM models for ballast-related studies. Additionally, this paper can assist researchers to choose an appropriate model for specific applications.Accepted author manuscriptRailway Engineerin

α-SMA⁺/ColI (GFP)⁺ cells were not detected in diaphragm or quadriceps muscles of <i>ColI-GFP/mdx</i>^<i>5cv</i> mice.

<p>(A) α-SMA/GFP (ColI) double immunostaining of quadriceps (Qua) and diaphragm (Dia) muscles in the <i>ColI-GFP/mdx</i>^<i>5cv</i> mice at 3 months. (B) α-SMA/GFP (ColI) double immunostaining of quadriceps (Qua) and diaphragm (Dia) muscles in the <i>ColI-GFP/mdx</i>^<i>5cv</i> mice at 6 months. (C) α-SMA/GFP (ColI) double immunostaining of fibrotic lungs from the <i>ColI-GFP</i> mice with the lung fibrosis induced by bleomycin (Lung). n = 5 mice/group. Bar = 50μm.</p

Fibrosis was more severe in diaphragm than in quadriceps muscles of <i>mdx</i>^<i>5cv</i> mice.

<p>(A) H&E staining of quadriceps (Qua) and diaphragm (Dia) muscles in the <i>mdx</i>^<i>5cv</i> mice at 3 months and 6 months of age (arrows: representative areas of myonecrosis and inflammation; asterisks: representative areas of endomysial fibrosis and inflammation). (B) Collagen III immunostaining of quadriceps (Qua) and diaphragm (Dia) muscles of <i>mdx</i>^<i>5cv</i> mice at 3 months and 6 months. (C) Hydroxyproline assay of quadriceps (Qua) and diaphragm (Dia) muscles from the <i>ColI-GFP/mdx</i>^<i>5cv</i> mice at 3 months and 6 months. Fold change refers to the comparison to the <i>mdx</i>^<i>5cv</i> quadriceps at 3 months. We used 5 mice/group/time point for tissue collections for HE staining, collagen III immunostaining, and protein preparation for hydroxyproline assay. *<i>p</i><0.05, ***<i>p</i><0.001. Bar = 50μm.</p