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Heavy ion-induced electrical degradations and mechanisms of high-electron-mobility transistors (HEMTs) were investigated in this article. AlGaN/GaN HEMTs were irradiated by 800-MeV Bi ions with total fluence of $5.23\times 10^{{10}}$ ions/cm2. The results show that the saturation current decreased by 13.1%, the threshold voltage negatively shifted by 0.21 V, the peak transconductance decreased by 26.6%, the reverse gate-leakage current increased much more than 16 times, and forward gate-leakage current increased more than three times. Furthermore, all electrical performances experienced partial recovery after room temperature annealing (RTA) and 175 °C thermal annealing except gate-leakage current. To further explore the mechanism of gate-leakage degradation, AlGaN/GaN heterojunction wafers were exposed to 1400-MeV Ta ions with fluence of $6.86\times107$ ions/cm2, and characterized by conductive atomic force microscope (CAFM) before and after the irradiation. The results show that the leakage current significantly increased in AlGaN material areas after the irradiation. Comparing the increase in gate leakage of the AlGaN/GaN heterojunction and AlGaN/GaN HEMT induced by heavy ions irradiation, it can be seen that the gate-leakage current of AlGaN/GaN HEMT after heavy irradiation almost entirely was caused by latent tracks. The mechanism for the irreversible increase in gate leakage after heavy ions irradiation could be attributed to the latent tracks along the ion trajectories through the heterojunction.

Background Recently, the pivotal role of component of inhibitor of nuclear factor kappa B kinase complex (CHUK) in lipid levels and blood pressure has been reported, and hypertension and hyperlipidemia are common risk factors of ischemic stroke (IS). However, the association between CHUK and IS has not yet been explored. This study aims at evaluating the relationship of CHUK polymorphisms (rs3808916, rs2230804 and rs3808917) and IS risk as well as IS-related risk factors. Methods: CHUK mRNA expression was detected between 53 IS patients and 53 healthy controls using quantitative real-time polymerase chain reaction (qRT-PCR). A total of 816 IS patients and 816 age- and sex-matched healthy controls were genotyped using the Sequenom MassARRAY iPLEX platform. Results: CHUK mRNA was highly expressed in IS patients compared with healthy subjects (P＜0.001). No significant associations were observed between rs3808916, rs2230804, rs3808917 and IS susceptibility (P＞0.05). Moreover, haplotype analysis showed that no haplotype of CHUK polymorphisms was associated with IS (P > 0.05). However, rs2230804 was related to diastolic blood pressure (DBP) of IS patients (P = 0.035), while rs3808917 was associated with triglyceride (TG) levels (P = 0.046). Conclusions: The CHUK expression is involved in the development of IS. CHUK variants rs2230804, and rs3808917 may affect blood pressure and lipid levels of IS patients. However, CHUK rs3808916, rs2230804 and rs3808917 polymorphisms are not associated with IS risk.

The single event burnout (SEB) effects of SiC power MOSFET are investigated by irradiations. An SEB is observed when drain biased above 400 V for 181Ta ion irradiation. The failure analysis shows a melting “hole” near the gate region due to the thermal runaway. Based on TCAD simulations, the impact ionization and parasitic bipolar are the key factors to trigger SEB in SiC MOSFET. Unlike the impact ionization, the turning on of the parasitic bipolar is not necessary for an SEB. But it will significantly reduce the threshold of SEB. Except for SEB, another permanent damage mode is also observed, which is manifested as the increase of leakage current and the abnormal of the output characteristics. This damage may be related to the latent track produced by heavy ion according to the failure analysis. The SEBs are observed for proton irradiations. The maximum LET value of the proton‐induced secondary ions can reach 13.9 MeV cm2/mg for 100 MeV proton. The simulations imply that most of the secondary ions can contribute to SEB. The biggest discrepancy from heavy ion irradiation is that no leakage current increases and output characteristics degradations are observed for the device without SEB after proton irradiation.

Horizontal axis wind turbine (HAWT) often works under yaw due to the stochastic variation of wind direction. Yaw also can be used as one of control methods for load reduction and wake redirection of HAWT. Thus, the aerodynamic performance under yaw is very important to the design of HAWT. For further insight into the highly unsteady characteristics aerodynamics of HAWT under yaw, this paper investigates the unsteady variations of the aerodynamic performance of a small wind turbine under static yawed and yawing process with sliding grid method, as well as the there-dimensional effect on the unsteady characteristics, using unsteady Reynolds-averaged Navier–Stokes (URANS) simulations. The simulation results are validated with experimental data and blade element momentum (BEM) results. The comparisons show that the CFD results have better agreement with the experimental data than both BEM results. The wind turbine power decreases according to a cosine law with the increase of yaw angle. The torque under yaw shows lower frequency fluctuations than the non-yawed condition due to velocity component of rotation and the influence of spinner. Dynamic yawing causes larger fluctuate than static yaw, and the reason is analyzed. The aerodynamic fluctuation becomes more prominent in the retreating side than that in the advancing side for dynamic yawing case. Variations of effective angle of attack and aerodynamic forces along the blade span are analyzed. The biggest loading position moves from middle span to outer span with the increase of yaw angle. Three-dimensional stall effect presents load fluctuations at the inner board of blade, and becomes stronger with the increase of yaw angle.

To investigate the correlation between enhancement degrees of brain metastases on contrast-enhanced T2-fluid-attenuated inversion recovery (CE-T2 FLAIR) and vascular permeability parameters of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). Thirty-nine patients with brain metastases were prospectively collected. They underwent non-enhanced T2 FLAIR, DCE-MRI, CE-T2 FLAIR, and contrast-enhanced three-dimensional brain volume imaging (CE-BRAVO). Quantitative parameters of DCE-MRI were evaluated for all lesions, which included volume transfer constant (Ktrans), rate constant (Kep), and fractional volume of the extracellular extravascular space (Ve). Contrast ratio (CR) and percentage increase (PI) values of all lesions on CE-T2 FLAIR were also measured. The tumor enhancement degree on CE-T2 FLAIR in relation to CE-BRAVO was visually classified as higher (group A), equal (group B), and lower (group C). A total of 82 brain metastases were evaluated, including 31 in group A, 19 in group B, and 32 in group C. The Ktrans and Kep were negatively correlated with the CR (ρ = − 0.551, p

The floating offshore wind turbines (FOWTs) have many more advantages than the onshore wind turbines, but they also have more complicated aerodynamic characteristics due to complex platform motions. The research objective of this paper is to investigate unsteady aerodynamic characteristics of a FOWT under the pitch, yaw, and coupled pitch–yaw platform motions using the computational fluid dynamics (CFD) method in the Unsteady Reynolds Averaged Navier-Stokes (URANS) simulations. The pitch, yaw, and coupled pitch–yaw motions are studied separately to analyze the platform motions’ effects on the rotor blade. The accuracy of the numerical simulation method is verified, and the overall performances, including power and thrust, are discussed. In addition, the comparison of total aerodynamic performance, force coefficients at different spans and structural dynamic response is provided. The numerical simulation results show that the platform pitching is the main influencing factor of power fluctuation, and the average thrust values of the pitch, yaw, and coupled motions are consistent regardless of the frequency value. The angle of attack (AOA) of airfoils is much more sensitive to the yaw motion, while the blade normal and tangential forces are mainly affected by pitch motion. As for the structural response, the results suggest that the aerodynamic loads of the wind turbine are more sensitive to the pitch motion, which is confirmed by the thrust force and torque of each blade during the platform motions.

Offshore wind energy developed rapidly in recent years. Due to the platform motions causing by ocean waves, the aerodynamics of floating offshore wind turbines (FOWT) show strong unsteady characters than onshore wind turbines. The widely used methods to investigate the unsteady aerodynamic performance of wind turbine are Blade Element Momentum (BEM) and Free-Vortex Wake (FVW) methods. The accuracy of these two methods strongly depend on empirical formula or correction models. However, for dynamics motions of wind turbine, there is still a lack of accurate models. CFD simulations using overset or dynamic mesh methods also have been used for FOWT aerodynamic investigations. However, the mesh deforming or reconstruction methods are usually suitable for small movement of wind turbine blade. In this paper, a dual-sliding mesh method is employed to simulate the unsteady aerodynamic characters of an offshore floating wind turbine with supporting platform motions using Unsteady Reynolds Averaged Navier-Stokes (URANS) simulations. Both rotor rotation and platform motions are treated as rigid angular motions. The relative motion and data exchange were simulated using sliding mesh method. The NREL 5MW reference wind turbine with platform pitching and rolling motions are considered. The pitching and rolling motions of floating platform are simplified in the form of a prescribed sinusoidal function. Different conditions with two amplitudes and two frequencies of pitching and rolling motions were investigated. URANS were performed with full structured mesh for wind turbine rotor using commercial software FLUENT. The platform motions were set using User Defined Function (UDF). Transitional Shear Stress Turbulence (T-SST) model was employed. The simulation results were compared with BEM method and FVW method results. Both steady status and dynamic pitching processes are investigated. The variations of wind turbine aerodynamic load, as well as the aerodynamic character of airfoils at different spanwise positions, were obtained and analyzed in detail. The simulations results show that the platform pitching introduce remarkable influence on the wind turbine aerodynamic performance. The platform pitching has much larger influence on the wind turbine power and thrust than the platform rolling. The dual-sliding mesh method shows potentials to investigation the dynamic process with multiple rigid motions.

We introduce deep convolutional and recurrent neural networks for end-to-end, open-vocabulary text reading on historical maps. A text detection network predicts word bounding boxes at arbitrary orientations and scales. The detected word images are then normalized for a robust recognition network. Because accurate recognition requires large volumes of training data but manually labeled data is relatively scarce, we introduce a dynamic map text synthesizer providing a practically infinite stream of training data. Results are evaluated on a labeled data set of 30 maps featuring over 30,000 text labels.

The rapid entire body assessment (REBA) is a rapid and semi-quantitative ergonomic assessment method for those who engaged in manual handling and/or standing work for a long time. In order to provide a self-assessment tool for operators, an App software based on Mask RCNN is proposed in this paper. The software is developed by adopting the architecture of a mobile terminal App combined with an imaging processing server. The main functions of the App are video capturing of work process, the operation of the process of REBA, human-machine interaction, etc., while the server is work for processing the video imaging transmitted from the App, key-points extraction of worker’s body from the images for work posture identification. One thousand working scene photos marked by VIA are used for training and testing based on the Microsoft COCO dataset to obtain a reliable target detection model. Experiment of container handling scene shows that the App evaluation software has achieved higher evaluation efficiency and accuracy. The validation of this method has been proved compared with manual evaluation based on REBA. And other work posture evaluation methods will be developed in the future to form an ergonomic evaluation software system.

Background Catheter-related bladder discomfort (CRBD), secondary to catheterization of urinary bladder is distressing. The aim of this study was to assess the efficacy of preoperative education on CRBD with image illustration for alleviating CRBD. Methods Sixty adult male patients, undergoing elective colonal and rectal surgery, were randomized to receive tetracaine mucilage instilled into the urethra and applied to the catheter (tetracain group), or receive tetracaine mucilage in combination with image illustration on CRBD (image group) before urethral catheterization. The incidence and severity of CRBD were assessed at 0.5, 1, 2, and 6 h after patients’ extubation. The severity of postoperative pain, incidence of postoperative agitation and other adverse events were also recorded. Results Patients in image group reported remarkably less CRBD than those in tetracaine group at 0.5,1, 2 and 6 h after extubation (20, 20, 6.7 and 6.7% v.s. 60, 73.3, 53.3 and 53.3%, respectively, P

Paper mill sludge-derived heterogeneous catalyst was synthesized through a facile method. X-ray diffraction (XRD) analysis confirmed the existence of α-Fe2O3, and Fourier transformed infrared (FT-IR) spectroscopy proved the formation of chemical bonds (Fe–O–Si). The as-prepared catalyst exhibited effective methylene blue (MB) degradation and exhibited an excellent stability of catalytic activity. This study provides an alternative environmentally friendly reuse method for paper mill sludge and a low cost and effective heterogeneous catalyst.

For the paper industry, the disposal and management of the yielded sludge are a considerable challenge. In our work, the paper mill sludge-derived magnetically separable heterogeneous catalyst (PMS-Fe-380) was prepared easily through a facile synthesis method. The morphology and structure of PMS-Fe-380 were fully characterized by means of X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and Brunauer-Emmet-Teller analysis. The catalytic activity of PMS-Fe-380 was evaluated by degradation of Methylene Blue (MB). The reusability and stability of PMS-Fe-380 were evaluated in five repeated runs, which suggested that PMS-Fe-380 manifested excellent stability of catalytic activity. Moreover, leaching tests indicated that the leached iron is negligible (

Enterprise has gradually developed into national economic wealth creating force and plays an important role in the development of regional economic. Traditional enterprises purchasing models cannot tolerate a growing purchase scale, and it difficult to improve purchasing efficiency and reduce procurement costs. To organize and implement e-procurement is imminent. The purpose of this paper is to analyze application of e-procurement in enterprises. According to the role of e-commerce in enterprises, the paper dissects the superiority of the e-procurement over traditional modes and explores the approaches of e-procurement.

Traditional monitoring techniques are not suitable for embedded systems because they could incur significant overhead. This paper proposes a lightweight dynamic performance monitoring framework for embedded systems focusing on reducing the dynamic monitoring overhead. With the introduction of a target-host separation and cooperation model, the target (embedded) system only needs to perform minimal low-overhead tasks while most of the high-overhead tasks were migrated to the host machine. The overhead in the target embedded system is further reduced through a low-cost dynamic instrumentation mechanism with direct jump instructions.

In traditional compressed sensing MRI methods, single sparsifying transform limits the reconstruction quality because it cannot sparsely represent all types of image features. Based on the principle of basis pursuit, a method that combines sparsifying transforms to improve the sparsity of images is proposed. Simulation results demonstrate that the proposed method can well recover different types of image features and can be easily associated with total variation.