Search

The cross-linked polyethylene cable will undergo thermal aging during service, which will seriously affect the service life of the cable. The current integration method can analyze the charge injection and conduction parameters from the dynamic change rate of the charge over time, and then analyze the insulation state of the polymer. Aiming at the field 10KV fault breakdown cable, this paper uses the current integration method to compare the dynamic change characteristics of the charge of the faulty cable and the new cable, and uses the ratio of Q(t) at t=600s and t=4s to study Charge injection and accumulation situation. Through analysis, it is found that the fault breakdown of the cable, the maximum charge accumulation under high voltage is 9000 Q/nC, the charge change rate is about 2, and the dielectric constant is 3.1, which is much greater than that of the new cable, indicating that the breakdown of the three-phase cable is mainly caused by the cable. It is caused by aging and eventually leads to insulation deterioration and breakdown.

We study the quantum coherence and its distribution of N-partite GHZ and W states of bosonic fields in the noninertial frames with arbitrary number of acceleration observers. We find that the coherence of both GHZ and W state reduces with accelerations and freezes in the limit of infinite accelerations. The freezing value of coherence depends on the number of accelerated observers. The coherence of N-partite GHZ state is genuinely global and no coherence exists in any subsystems. For the N-partite W state, however, the coherence is essentially bipartite types, and the total coherence is equal to the sum of coherence of all the bipartite subsystems.

In view of the chaotic relationship between user-transformer in the current low-voltage stations, manual identification consumes a long time period, low identification accuracy, and high input system costs. This paper proposes a method for identifying household change relations in low-voltage stations based on dual-scale similarity and spectral clustering algorithm. First, according to the different similarities of user voltage curves in different stations, consider Euclidean distance and cosine distance to establish a two-scale spectral clustering similarity matrix from the distance and shape of the voltage curve. Then based on the two-scale similarity matrix, perform spectral clustering on the voltage curves of the same station area to complete the clustering of users in the same station area. Examples show that the method proposed in the article has high recognition accuracy, low input cost, and has good application effects.

To study the dynamic charge characteristics of XLPE cables. In this paper, a Qt test system is built in the laboratory to test the Qt dynamic charge characteristics of different thermal aging samples, and the current characteristics of different aging degrees are obtained according to the charge test differentiation. The experimental results show that the charge value of unaged sample is about 1100 nC, and the charge value of aged sample is about 2000 nC. At the moment of pressurization, the XLPE cable sheet sample flows through a large instantaneous charging current, and the initial current is more than 10−9 orders of magnitude. For the unaged sample, the charge accumulation value and conduction current value of H1 and H2 are better than those of F sample. The analysis shows that due to the insufficient aging degree of the sample, the initial aging stage is in the recrystallizaon stage.

As a common lung disease, pneumonia affects millions of people worldwide each year and is often detected during physical examination using chest X-ray images (CXRs), which are usually diagnosed by radiologists. This time-consuming task often leads to fatigue-based diagnostic error and cannot be performed in countries or areas lack of radiologists. In this work, we proposed a multi-task learning model: Mt-pnet. We learn from the experience of imaging doctors in the diagnosis of pneumonia, let the network pay attention to the patient’s gender and age information in the diagnosis of pneumonia. The combined information is helpful for the network to learn robust image features for pneumonia diagnosis. At the same time, we also found that using multi-task model is helpful to improve the recall of patients with pneumonia, which has important clinical significance.

Undercooled melt of Ge73.7Ni26.3 alloy sample floated on B2O3 melt was subjected to sputtering-deposition of Ni clusters on cooling to induce solidification. The initial temperature of solidification was 975 K. Its undercooling Delta T was 134 K with respect to the melting temperature of the primary phase Ge. On the cooling curve existed dual recalescences representing the transformation of the primary phase (Ge) and the eutectics (Ge+GeNi) respectively But for the sample unsputtered, only a single exothermic peak presented on the cooling curve with the initial solidification temperature of 904 K and undercooling of 205 K. Careful observation of the microstructure proved that the Ge phase primarily formed in the sputtering experiment was now formed together with the formation of the eutectics in the experiment without sputtering.

Highly crystalline and transparent CdS films are grown by utilizing the vacuum thermal evaporation (VTE) method. The structural, surface morphological, and optical properties of the films are studied and compared with those prepared by chemical bath deposition (CBD). It is found that the films deposited at a high substrate temperature (200 °C) have a preferential orientation along (002) which is consistent with CBD-grown films. Absorption spectra reveal that the films are highly transparent and the optical band gap values are found to be in a range of 2.44 eV–2.56 eV. CuIn1−xGaxSe2 (CIGS) solar cells with in-situ VTE-grown CdS films exhibit higher values of Voc together with smaller values of Jsc than those from CBD. Eventually the conversion efficiency and fill factor become slightly better than those from the CBD method. Our work suggests that the in-situ thermal evaporation method can be a competitive alternative to the CBD method, particularly in the physical- and vacuum-based CIGS technology.

The advancement in nanotechnology has produced technological and conceptual breakthroughs but the effects nanomaterials have on organisms at the cellular level are poorly understood. Here we report that carboxyl-terminated multi-walled carbon nanotubes (MWCNTs) act as antagonists of three types of potassium channels as assessed by whole-cell patch clamp electrophysiology on undifferentiated pheochromocytoma (PC12) cells. Our results showed that carboxyl-terminated MWCNTs suppress the current densities of I(to), I(K) and I(K1) in a time-dependent and irreversible manner. The suppressions were most distinct 24 h after incubation with MWCNTs. However, MWCNTs did not significantly change the expression levels of reactive oxygen species (ROS) or intracellular free calcium and also did not alter the mitochondrial membrane potential (DeltaPsi(m)) in PC12 cells. These results suggest that oxidative stress was not involved in the MWCNTs suppression of I(to), I(K) and I(K1) current densities. Nonetheless, the suppression of potassium currents by MWCNTs will impact on electrical signaling of excitable cells such as neurons and muscles.

One-dimensional boron nitride (BN) nanotube nanojunctions are of great interest for both fundamental and applied research because of their stable and excellent mechanical and physical properties. Large quantities of highly pure BN nanotube multiple Y- and/or T-junctions were synthesized by annealing pure boron nanowire precursors in N-2 atmosphere at 1500 degrees C. Transmission electron microscopy and electron energy-loss spectroscopy studies reveal that the products possess a concentric tubular structure and stoichiometric BN composition. The boron nanostructured precursors react with nitrogen at high temperature to form the corresponding BN components, retaining their original morphologies. A non-equilibrium interdiffusion of nitrogen and boron might be involved in the transformation process of the solid boron nanowires to hollow BN nanostructures. Our results illustrate the technological potential of BN nanoscale multiple junctions being incorporated into future nanoscale mechanical and electronic devices.