VSC-HVDC transmission line fault location based on transient characteristics

Accurate and reliable fault location is necessary for ensuring the safe and reliable operation of the VSC-HVDC transmission system. This paper proposed a single-terminal fault location method based on the fault transient characteristics of the two-terminal VSCH-VDC transmission system. The pole-to-pole transient fault process was divided into three stages, the time-domain expression of the DC current during the diode freewheel stage was used to locate the fault point, and a criterion for judging whether the fault evolves to the diode freewheel stage was proposed. Taking into account the enhancing effect of the opposite system to the fault current, the DC side pole-to-ground fault networkwas equated to a fourth-order circuit model, the relationship of fault distance with the characteristic roots of fault current differential equationwas derived, and the Prony algorithmwas utilized for datafitting to extract characteristic roots to realize fault location. A two-terminal VSC-HVDC transmission system was modelled in PSCAD/EMTDC. The simulation result verifies that the proposed principle can accurately locate the fault point on the VSC-HVDC transmission lines

The Effects of Guide Pads on Bore Diameter Enlargement Magnitude in Deep Hole Drilling

Deep hole machining accuracy plays a crucial role in product’s quality. The results of an investigation into the machining accuracy of deep drilling holes which highlights problems of bore diameter enlargement magnitude assessment are presented in this paper. Through the study of BTA deep drilling tool properties and mechanism, as well as the formation rule of deep hole surface, clarified the burnishing mechanism of guide pad in deep hole drilling, and obtained the directly relationship between surface formation rule and the guide pad. After drilling experimentrevealed the effect of guide pad on bore diameter enlargement magnitude

Epidermal Growth Factor Promotes Proliferation and Migration of Follicular Outer Root Sheath Cells via Wnt/β-Catenin Signaling

Background/Aims: To investigate the effect and molecular mechanism of EGF on the growth and migration of hair follicle outer root sheath (ORS) cells. Methods: Intact anagen hair follicles were isolated from mink skin and cultured with EGF in vitro to measure ORS daily growth. Meanwhile, purified primary ORS cells were treated or transfected with EGF, and their proliferation and migration were assessed by MTT assay and transwell assay, respectively. The signaling pathway downstream of EGF was characterized by using the Wnt/β-catenin signaling inhibitor, XAV-939. Results: EGF of 2-20 ng/ml, not higher or lower, promoted the growth of follicular ORS in vitro. EGF treatment or overexpression promoted the proliferation and migration of ORS cells. Moreover, EGF stimulation induced nuclear translocation of β-catenin, and upregulated the expression of Wnt10b, β-catenin, EGF receptor and SOX9. Inhibition of Wnt/β-catenin signaling by XAV-939 significantly reduced the basal and EGF-enhanced proliferation and migration of ORS cells. In addition, a number of follicle-regulatory genes, such as Survivin, Msx2 and SGK3, were upregulated by EGF in the ORS cells, which was also inhibited by XAV-939. Conclusion: EGF promotes the proliferation and migration of ORS cells and modulates the expression of several follicle-regulatory genes via Wnt/β-catenin signaling

The Effects of Guide Pads on Bore Diameter Enlargement Magnitude in Deep Hole Drilling

Deep hole machining accuracy plays a crucial role in product’s quality. The results of an investigation into the machining accuracy of deep drilling holes which highlights problems of bore diameter enlargement magnitude assessment are presented in this paper. Through the study of BTA deep drilling tool properties and mechanism, as well as the formation rule of deep hole surface, clarified the burnishing mechanism of guide pad in deep hole drilling, and obtained the directly relationship between surface formation rule and the guide pad. After drilling experimentrevealed the effect of guide pad on bore diameter enlargement magnitude

Impact of Thermal Control Measures on the Imaging Quality of an Aerial Optoelectronic Sensor

The image resolution is the most important performance parameter for an aerial optoelectronic sensor. Existing thermal control methods cannot eliminate the sensor’s temperature gradient, making the image resolution difficult to further improve. This article analyzes the different impacts of temperature changes on the imaging resolution and proposes modifications. Firstly, the sensor was subjected to thermo-optical simulation by means of finite element analysis, and the different impacts of temperature changes on the imaging quality were analyzed. According to the simulation results, an active thermal control method is suggested to enhance the temperature uniformity of the sensor. Considering the impacts of active and passive thermal control measures, thermal optical analysis was carried out to predict the performance of the sensor. The results of the analysis show that the imaging quality of the sensor has been significantly improved. The experimental results show that the image resolution of the optoelectronic sensor improved from 47 to 59 lp/mm, which demonstrates that the sensor can produce a high image quality in a low-temperature environment

Application of formulated diets and their effects on nutrient digestibility and reproductive performance of female mink (Neovison vison) during gestation

This study was designed to investigate the possibility of total replacement of conventional diet by formulated experimental feed in farmed mink during gestation. Ninety female mink (Neovison vison) were randomly assigned to three groups: control group was fed conventional diet with normal (36%, C) protein level composed of fresh or frozen animal by-products and extruded corn. Formulated experimental diets contained animal meals, vegetable ingredients and fat, with normal (36%, E1) or high (44%, E2) protein level, and were mixed with water prior to administration. Nutrient digestibility, nitrogen (N)-balance and reproductive performance were determined to compare the effect of diets fed to female mink during gestation. Mink fed both experimental diets had lower nutrient digestibility than the control. Higher barren females, decreased birth survival rate and birth weight were noted for the two experimental groups, especially diet E1 with normal dietary protein, indicating impaired reproduction performance, but signs of improvement were seen in the experimental group with high protein level (44%, E2)

Administration of Curcumin Protects Kidney Tubules Against Renal Ischemia-Reperfusion Injury (RIRI) by Modulating Nitric Oxide (NO) Signaling Pathway

Background/Aims: To explore the protective effect of curcumin on renal ischemia-reperfusion injury (RIRI) in rats, and its influence on nephridial tissue’s NO and cGMP levels as well as downstream signaling pathway, to elucidate the possible mechanism of curcumin on RIRI. Methods: 36 Sprague Dawley rats (SD rats) were randomly divided into Sham group, Model group, curcumin (CUR +) Model group, 12 rats per group. They were all given RIRI model preparation by unilateral artery occlusion method. All groups’ β2-MG in urine in 24h, serum Cr and BUN were compared, and UAER were calculated. Nitric oxide synthase (NOS), cGMP-dependent protein kinase (PKG), Caspase-3 expression were all determined by western blot. Nitric oxide (NO), NOS and cGMP levels were also examined by using ELISA. All groups’ nephridial histomorphology and kidney tubules score were evaluated and compared. Results: β2-MG and UAER in urine, serum Cr and BUN, in renal tissue were all elevated in Model of RIRI, indicating the success of animal model of RIRI establishment, and above index in CUR + Model group were all lower than those in Model group. Furthermore, iNOS, NO, cGMP, PKG and Caspase-3 in renal tissue were all increased in Model of RIRI, indicating the NO signaling pathway was activated, which is one of the pathogenesis of RIRI, and above index in CUR + Model group were all lower than those in Model group, suggesting that inactivation of iNOS/NO/cGMP/PKG signaling pathway is one of the reasons that explain the protective effect of curcumin in RIRI. Conclusion: The activation of iNOS/NO/cGMP/PKG signaling pathway and the consequent promoted apoptosis of renal tubules are significantly involved in the pathogenesis of development of RIRI, and curcumin treatment could protect renal tubules against RIRI, at least partially, by suppressing the activated iNOS/NO/cGMP/PKG signaling pathway

Effects of dry dietary protein on digestibility, nitrogen-balance and growth performance of young male mink

The experiment was to study the nutrient digestibility and metabolism performance of male minks, which were fed different protein level diets during growth period. Effects of protein quantity on growth and development of minks and feed conversion ratio (FCR) were also investigated. Sixty healthy male minks of 45 d were randomly allocated into six groups with ten replicates, which was one sable for each replicate. The minks in six groups were fed diets in which protein levels were 28, 30, 32, 34, 36 and 38%, respectively. The six groups were denoted as P28, P30, P32, P34, P36 and P38. After 2 wk, all minks were weighed, average daily gains (ADG) were calculated, and the digestibility values of nutrients were determined. The results indicated that digestibility of calcium, nitrogen of fence, nitrogen deposition, net protein utilization (NPU), and biological value of protein (BV) were similar (P > 0.05), however, nitrogen intake greatly varied among groups (P < 0.01). Compared with group P28, groups of P34, P36 and P38 showed significant difference (P < 0.01) in ADG and FCR. In conclusion, it was recommended that adding 34% protein to mink diet would optimize production parameters including ADG, digestibility of nutrition, and FCR, and negative result was observed when diet protein was lower than 28%