SiC trench MOSFET with dual shield gate and optimized JFET layer for improved dynamic performance and safe operating area capability

A novel silicon carbide(SiC) trench metal–oxide–semiconductor field-effect transistor(MOSFET) with a dual shield gate(DSG) and optimized junction field-effect transistor(JFET) layer(ODSG-TMOS) is proposed. The combination of the DSG and optimized JFET layer not only significantly improves the device’s dynamic performance but also greatly enhances the safe operating area(SOA). Numerical analysis is carried out with Silvaco TCAD to study the performance of the proposed structure. Simulation results show that comparing with the conventional asymmetric trench MOSFET(Con-ATMOS), the specific on-resistance(Ron,sp) is significantly reduced at almost the same avalanche breakdown voltage(BVav). Moreover, the DSG structure brings about much smaller reverse transfer capacitance(Crss) and input capacitance(Ciss), which helps to reduce the gate–drain charge(Qgd) and gate charge(Qg). Therefore, the high frequency figure of merit(HFFOM) of Ron,sp·Qgdand Ron,sp· Qgfor the proposed ODSG-TMOS are improved by 83.5% and 76.4%, respectively.The switching power loss of the proposed ODSG-TMOS is 77.0% lower than that of the Con-ATMOS. In addition, the SOA of the proposed device is also enhanced. The saturation drain current(Id,sat) at a gate voltage(Vgs) of 15 V for the ODSGTMOS is reduced by 17.2% owing to the JFET effect provided by the lower shield gate(SG) at a large drain voltage. With the reduced Id,sat, the short-circuit withstand time is improved by 87.5% compared with the Con-ATMOS. The large-current turn-off capability is also improved, which is important for the widely used inductive load applications.

Object-Based Burned Area Mapping with Extreme Gradient Boosting Using Sentinel-2 Imagery

The Sentinel-2 satellites are providing an unparalleled wealth of high-resolution remotely sensed information with a short revisit cycle, which is ideal for mapping burned areas both accurately and timely. This paper proposes an automated methodology for mapping burn scars using pairs of Sentinel-2 imagery, exploiting the state-of-the-art eXtreme Gradient Boosting (XGB) machine learning framework. A large database of 64 reference wildfire perimeters in Greece from 2016 to 2019 is used to train the classifier. An empirical methodology for appropriately sampling the training patterns from this database is formulated, which guarantees the effectiveness of the approach and its computational efficiency. A difference (pre-fire minus post-fire) spectral index is used for this purpose, upon which we appropriately identify the clear and fuzzy value ranges. To reduce the data volume, a super-pixel segmentation of the images is also employed, implemented via the QuickShift algorithm. The cross-validation results showcase the effectiveness of the proposed algorithm, with the average commission and omission errors being 9% and 2%, respectively, and the average Matthews correlation coefficient (MCC) equal to 0.93.

Esophageal nasopharyngeal catheter in the wake-up anesthesia of the brain function area operations

Objective To evaluate the feasibility and safety of the self developed sound outside the ventilation device-esophageal nasopharynx catheter in brain functional areas surgery applications. Methods 13 patients involved functional areas of brain surgery were chosed. After induction of general anesthesia,the catheters were placed in the esophagus,then connected to anesthesia machines to an external

Machine Learning-Based Threatened Species Translocation Under Climate Vulnerability

Climate change is the most serious causes and has a direct impact on biodiversity.According to the world’s biodiversity conservation organization,rep-tile species are most affected since their biological and ecological qualities are directly linked to climate.Due to a lack of time frame in existing works,conser-vation adoption affects the performance of existing works.The proposed research presents a knowledge-driven Decision Support System(DSS)including the assisted translocation to adapt to future climate change to conserving from its extinction.The Dynamic approach is used to develop a knowledge-driven DSS using machine learning by applying an ecological and biological variable that characterizes the model and mitigation processes for species.However,the frame-work demonstrates the huge difference in the estimated significance of climate change,the model strategy helps to recognize the probable risk of threatened spe-cies translocation to future climate change.The proposed system is evaluated using various performance metrics and this framework can comfortably adapt to the decisions support to reintroduce the species for conservation in the future.

Area Operators on Bergman Spaces

We completely characterize the boundedness of area operators from the Bergman spaces A_(α)^(p)(Bn)to the Lebesgue spaces L^(q)(S_(n))for all 0<p,q<∞.For the case n=1,some partial results were previously obtained by Wu in[Wu,Z.:Volterra operator,area integral and Carleson measures,Sci.China Math.,54,2487–2500(2011)].Especially,in the case q<p and q<s,we obtain some characterizations for the area operators to be bounded.We solve the cases left open there and extend the results to n-complex dimension.

Angiopoietin-2/angiopoietin-1 as non-invasive biomarker of cirrhosis in chronic hepatitis C

AIM To evaluate the efficacy of peripheral blood concentrations of angiopoietins(Ang) as cirrhosis biomarkers of chronic hepatitis C(CHC).METHODS Ang1 and Ang2 serum levels were measured by enzyme-linked immunosorbent assays(ELISA) in samples from 179 cirrhotic and non-cirrhotic CHC patients, classified according to the METAVIR system.Groups were compared by non-parametric MannWhitney U test. Subsequently, the association of peripheral concentrations of angiopoietins with the stage of fibrosis was analyzed using Spearman correlation test. Finally, the accuracy, sensitivity and specificity of circulating angiopoietins for cirrhosis diagnosis were determined by the study of the respective area under the curve of receiver operator characteristics(AUC-ROC).RESULTS Peripheral blood concentrations of Ang1 and Ang2 in CHC patients were significantly related to fibrosis. While Ang1 was decreased in cirrhotic subjects compared to non-cirrhotic(P < 0.0001), Ang2 was significantly increased as CHC progressed to the end stage of liver disease(P < 0.0001). Consequently, Ang2/Ang1 ratio was notably amplified and significantly correlated with fibrosis(P < 0.0001). Interestingly, the individual performance of each angiopoietin for the diagnosis of cirrhosis reached notable AUC-ROC values(above 0.7, both), but the Ang2/Ang1 ratio was much better(AUC-ROC = 0.810) and displayed outstanding values of sensitivity(71%), specificity(84%) and accuracy(82.1%) at the optimal cut-off(10.33). Furthermore, Ang2/Ang1 ratio improved the performance of many other previously described biomarkers or scores of liver cirrhosis in CHC.CONCLUSION Ang2/Ang1 ratio might constitute a useful tool for monitoring the progression of chronic liver disease towards cirrhosis and play an important role as therapeutic target.

Operation-area-constrained Adaptive Primary Frequency Support Strategy for Electric Vehicle Clusters

Due to their fast response and strong short-term power throughput capacity, electric vehicles(EVs) are promising for providing primary frequency support to power grids. However, due to the complicated charging demands of drivers, it is challenging to efficiently utilize the regulation capacity of EV clusters for providing stable primary frequency support to the power grid. Accordingly, this paper proposes an adaptive primary frequency support strategy for EV clusters constrained by the charging-behavior-defined operation area. First, the forced charging boundary of the EV is determined according to the driver's charging behavior, and based on this, the operation area is defined. This ensures full utilization of the available frequency support capacity of the EV. An adaptive primary frequency support strategy of EV clusters is then proposed. The output power of EV is adaptively regulated according to the real-time distance from the EV operating point to the forced charging boundary. With the proposed strategy, when the EV approaches the forced charging boundary, its output power is gradually reduced to zero. Then, the rapid state-of-charge declines of EVs and sudden output power reductions in EV clusters caused by forced charging to meet the driver's charging demands can be effectively avoided. EV clusters can then provide sustainable frequency support to the power grid without violating the driver's charging demands. Simulation results validate the proposed operation-area-constrained adaptive primary frequency support strategy, which outperforms the average strategy in terms of stable output maintenance and the optimal utilization of regulation capacities of EV clusters.

Automated Burned Scar Mapping Using Sentinel-2 Imagery

The Sentinel-2 satellites are providing an unparalleled wealth of high-resolution remotely sensed information with a short revisit cycle, which is ideal for mapping burned areas both accurately and timely. However, the high detail and volume of information provided actually encumbers the automation of the mapping process, at least for the level of automation required to map systematically wildfires on a national level. This paper proposes a fully automated methodology for mapping burn scars using Sentinel-2 data. Information extracted from a pair of Sentinel-2 images, one pre-fire and one post-fire, is jointly used to automatically label a set of training patterns via two empirical rules. An initial pixel-based classification is derived using this training set by means of a Support Vector Machine (SVM) classifier. The latter is subsequently smoothed following a multiple spectral-spatial classification (MSSC) approach, which increases the mapping accuracy and thematic consistency of the final burned area delineation. The proposed methodology was tested on six recent wildfire events in Greece, selected to cover representative cases of the Greek ecosystems and to present challenges in burned area mapping. The lowest classification accuracy achieved was 92%, whereas Matthews correlation coefficient (MCC) was greater or equal to 0.85.

BMC LIMITED AREA MODEL GENERAL DESCRIPTION AND OPERATIONAL RESULTS

The limited area 5-level primitive equation model,as the first operational precipitation forecast model in China,has been run at Beijing (National) Meteorological Center (BMC) for more than four years.The opera- tional results show that this model gives continuous services,and the forecast skill is satisfied for the forecast of some weather situations,such as extratropical cyclone,front and the precipitation associated with them. The forecast guides are widely used at the local weather services now.

Mapping of Freshwater Snails’ Habitat—A Source of Transmitting Bilharzia in Mwea Sub-County, Kenya

Bilharzia is vector-borne disease carried by a parasite that is hosted by fresh water snails. The distribution of the disease is concurrent with the existence of the freshwater snails and is dependent on certain suitable environmental conditions. It is difficult to identify the specific habitats of the snails as they are often inaccessible on the ground, the snails also migrate by means of flowing water, making it difficult to keep a track of the freshwater snails’ habitat. This paper aimed at using GIS, Remote Sensing and Species Distribution Modelling techniques to model the suitable habitats for the freshwater snails and to prove that the snails migrate when there are sudden changes in water levels whilst showing the population at risk of bilharzia. The SDM used is the Maximum Entropy (MAXENT) for its ability to make right predictions even with small presence sites. The AUC value of the model was 0.951. The research results showed that the environmental variables;brightness Index, elevation, temperatures were negatively correlated with the snails’ presence while the wetness index, MSAVI, greenness index and soil pH were positively correlated. The snails are observed to favor clay soils of the montmorillonite type and the crop-lands land cover. Areas consistently submerged by water especially after flooding are shown to be the most suitable areas where snails migrate by means of river or canal water. The research proves that Mwea is not the source habitat of the freshwater snails. The neighboring sub-counties within Kirinyaga County should be investigated using such models as a likely source-habitat of the freshwater snails. Destroying the source habitats will lead to complete eradication of the freshwater snails within Mwea.

Generalized area operators on L^p（R^n）

We introduce the generalized area operators by using nonnegative measures defined on upper half-spaces R＋^n＋1. The characterization of the boundedness and compactness of the generalized area operator from LP（]Rn） to Lq（IRn） is investigated in terms of s-Carleson measures with 1 〈 p, q 〈 ＋∞. In the case of p = q = 1, the weak type estimate is also obtained.

Synchronous Construction and Operation of Coal Mine and Power Plant in Mining Area

In accordance with the experience withSynchronous construction of coal mine andpower plant in Yongxia mining area, thispaper discusses the existing issues regardingmine mouth power plant including capital,power grid connection, electricity price for gridconnection, installed capacity generation setselection as well as self- protection of coalindustry. It is regarded that under marketeconomy as long as the benefits of the threesectors of coal, electricity and the local arecomprehensively considered, a suitable waycan be arrived for conl industry to operate electricity business.

Clinical Application of "Combined Acupuncture-Drug Anesthesia"to the Operations on Cerebral Function Areas

Objective: To find out whether high resection rate and low incidence of disability can be obtained from operations for tumors on cerebral functional areas by applying “combined acupuncture-drug anesthesia”Methods: According to the route of entry of operations, two different groups of acupoints for body acupuncture combined with ear acupuncture therapy were applied.Results: Among the 80 patients operated on, 20 were suffering from tumors in the speech center, 60 in the sensorimotor center. Good result was obtained from all the operations. Grade 1 effective rate of acupuncture anesthesia reached 100%. None of the patients experienced aggravation of dysphasia or dysfunction. Five patients showed aggravation of myasthenia and dysesthesia, but all of them recovered within 2-4 weeks.Conclusions: High resection rate and low incidence of disability may result from operations performed with “combined acupuncture-drug anesthesia;” so this kind of anesthesia can be used as a routine anesthetic method for operations.

Baseline Hepatitis B Virus DNA Level is a Promising Factor for Predicting the 3^rd Month Virological Response to Entecavir Therapy： A Study of Strict Defined Hepatitis B virus Induced Cirrhosis

Background： Cirrhosis is a common complication of chronic hepatitis B. It remains unclear if viral and biochemical parameters at baseline affect virological response to entecavir and therefore warrant investigation. In the present study, we aimed to eval uate the efficacy of entecavir therapy by monitoring virological response at the end of the 3^rd month of treatment and try to figure out whether baseline factors could help predict it in a cohort of hepatitis B virus （HBV） compensated cirrhosis patients and to determine the cut-off value of a predicting parameter.Methods： A total of 91 nucleos（t）ide-naive patients with HBV induced cirrhosis （compensatory stage） were enrolled in a prospective cohort. HBV DNA and alanine aminotransferase （ALT） were tested at baseline and monitored every 3-6 months after starting therapy. Results： Of all 91 patients, the median follow-up time was 12 （9-24） months. Overall, 64 patients （70.3%） achieved virological response in the 3^rd month. Univariate analysis showed that the 3^rd month virological response can be predicted by baseline HBV DNA levels （P 〈 0.001, odds ratio [OR]： 2.13, 95% confidence interval [CI]： 1.44-3.15）, ALT value （P = 0.023, OR： 1.01, 95% CI： 1.00 1.01 ） and hepatitis B e antigen （HBeAg） negativity （P = 0.016, OR： 0.30, 95% CI： 0.11-0.80）. Multiple regression analysis showed baseline H BV DNA level was the only parameter related to full virological response. Higher baseline HBV DNA strata indicated a higher probability that HBV DNA remains detectable at the 3^rd month （P = 0.001）. Area under receiver operating characteristic curve for determining the 3^rd month virological response by baseline HBV DNA was 77.6% （95% CI： 66.7-85.2%）, with a best cut-offvalue of 5.8 log10. Conclusions： Baseline HBV DNA, HBeAg negativity, and ALT were independent factors contributing to virological response at the 3^rt month. Further, multiple regression showed that HBV DNA level was the only parameter predicting full virological response as early as the 3^rd month, in this cirrhosis cohort.

PSA density improves the rate of prostate cancer detection in Chinese men with a PSA between 2.5-10.0 ng ml-1 and 10.1-20.0 ng ml-1： a multicenter study

Chinese men should have a higher prostate-specific antigen （PSA） ＂gray zone＂ than the traditional value of 2.5-10.0 ng ml-1 since the incidence of prostate cancer （PCa） in Chinese men is relative low. We hypothesized that PSA density （PSAD） could improve the rate of PCa detection in Chinese men with a PSA higher than the traditional PSA ＂gray zone.＂ A total of 461 men with a PSA between 2.5 and 20.0 ng ml-1, who had undergone prostatic biopsy at two Chinese centers were included in the analysis. The men were then further divided into groups with a PSA between 2.5-10.0 ng ml-1 and 10.1-20.0 ng ml-1. Receiver operating characteristic （ROC） curve was used to evaluate the efficacy of PSA and PSAD for the diagnosis of PCa. In men with a PSA of 2.5-10.0 ng ml-1 or 10.1-20.0 ng ml-z, the areas under the ROC curve were higher for PSAD than for PSA. This was consistent across both centers and the cohort overall. When the entire cohort was considered, the optimal PSAD cut-off for predicting PCa in men with a PSA of 2.5-10.0 ng m1-1 was 0.15 ng ml-2 ml-2, with a sensitivity of 64.4% and specificity of 64.6%. The optimal cut-off for PSAD in men with a PSA of 10.1-20.0 ng m1-1 was 0.33 ng ml-1 ml-1, with a sensitivity of 60.3% and specificity of 82.7%. PSAD can improve the effectiveness for PCa detection in Chinese men with a PSA of 2.5-10.0 ng ml-1 （traditional Western PSA ＂gray zone＂） and 10.1-20.0 ng ml-2 （Chinese PSA ＂gray zone＂）.

Kirk effect and suppression for 20 V planar active-gap LDMOS

For 20 V planar active-gap lateral double-diffused MOSFET （LDMOS）, the sectional channel is utilized to decrease the electric field in the n-drift region below the poly gate edge in the off-state, compared with the conventional single channel. Then the n-drift concentration can be increased to decrease the Kirk effect, while keeping off-state breakdown voltage Vbd unchanged. Meanwhile the influence of the n-drift concentration and the n-drift length Ldrift （the drain n＋ diffusion to gate spacing） which are related to the Kirk effect is discussed. The trade-offs between Rdson.Area, breakdown voltage Vbd and the electrical safe operating area （e-SOA） performance of LDMOS are considered also. Finally the proposed planar active-gap LDMOS devices with varied values of Ldria are experimentally demonstrated. The experimental results show that the Kirk effect can be greatly suppressed with slight increase in the Rdson.Area parameter.

Energy capability enhancement for isolated extended drain NMOS transistors

Isolated extended drain NMOS（EDNMOS） transistors are widely used in power signal processing.The hole current induced by a high electric field can result in a serious reliability problem due to a parasitic NPN effect. By optimizing p-type epitaxial（p-epi） thickness,n-type buried layer（BLN） and nwell doping distribution,the peak electric field is decreased by 30%and the peak hole current is decreased by 60%,which obviously suppress the parasitic NPN effect.Measured I-V characteristics and transmission line pulsing（TLP） results show that the onstate breakdown voltage is increased from 28 to 37 V when 6 V V;is applied and the energy capability is improved by about 30%,while the on-state resistance remains unchanged.

An LDMOS with large SOA and low specific on-resistance

An LDMOS with nearly rectangular-shape safe operation area （SOA） and low specific on-resistance is proposed. By utilizing a split gate, an electron accumulation layer is formed near the surface of the n-drift region to improve current conduction capability during on-state operation. As a result, the specific on-resistance can be low- ered down to 74.7 m^2.cm2 for a 600 V device from simulation. Furthermore, under high-voltage and high-current conditions, electrons and holes flow as majority carriers in the n-drift region and p-type split gate, respectively. Due to charge compensation occurring between holes and electrons, the local electric field is reduced and impact ion- ization is weakened in the proposed device. Therefore, a higher on-state breakdown voltage at large V6s is obtained and snap-back is suppressed as well.