There is growing interest in developing high-voltage MOSFET devices that can be integrated with low-voltage CMOS digital and analog circuits. In this paper,high-voltage nand p-type MOSFETs are fabricated in a commerci...There is growing interest in developing high-voltage MOSFET devices that can be integrated with low-voltage CMOS digital and analog circuits. In this paper,high-voltage nand p-type MOSFETs are fabricated in a commercial 3.3/ 5V 0.5μm n-well CMOS process without adding any process steps using n-well and p-channel stops. High current and highvoltage transistors with breakdown voltages between 23 and 35V for the nMOS transistors with different laydut parameters and 19V for the pMOS transistors are achieved. This paper also presents the insulation technology and characterization results for these high-voltage devices.展开更多
The technique to improve the performance of W/TiN stacked gate MOS capacitor with 3nm gate oxide is reported by optimizing the sputtering process of a refractory metal gate electrode and adopting a proper anneal tempe...The technique to improve the performance of W/TiN stacked gate MOS capacitor with 3nm gate oxide is reported by optimizing the sputtering process of a refractory metal gate electrode and adopting a proper anneal temperature to eliminate the damages.Specific methods involved in the optimization of sputtering process include:selecting a proper TiN thickness to reduce stresses;using a smaller sputtering rate to suppress the damages to gate dielectric and adopting a higher N 2/Ar ratio during the TiN sputtering process to further nitride the gate dielectric.With these measures,excellent C V curves are obtained and surface state density ( N ss ) is successfully reduced to below 8×10 10 cm -2 ,which is comparable to the polysilicon gate MOS capacitor.展开更多
The reducing efficiencies of the commonly used heat treatment methods and fermentation processes on aflatoxin M1 (AFM1) in Nigeria were investigated. Seventy samples of fresh cow milk from both conventional and tradit...The reducing efficiencies of the commonly used heat treatment methods and fermentation processes on aflatoxin M1 (AFM1) in Nigeria were investigated. Seventy samples of fresh cow milk from both conventional and traditional dairy cattle herds were collected and analyzed for the determination of AFM1 using Cobra-cell incorporated high performance liquid chromatography. Of these analyzed samples, 56 (80.0%) tested positive for AFM1 out of which 3 milk samples with high AFM1 concentrations were selectively pooled and subjected to varied conditions of heat treatments and fermentation processes using both indigenized and exotic strains of lactic acid bacteria (Lactobacillus bulgaricus + Streptococcus thermophilus and L. rhamnosus and L. plantarum) as starter cultures respectively. Both processes used either singly or combined, demonstrated high degrees of reducing effects on AFM1 levels. Sterilization of the milk at 121?C and 80?C under the same condition of time (15 - 20) min showed significant reduction of up to 58.8% (p 0.05) in the level of AFM1 when compared with the initial mean AFM1 concentration of the untreated fresh milk. The situation was however different around the boiling temperature of 100?C at which point the level of AFM1 reduction was found to be inconsistent. The indigenized combined strains showed some slight margins of AFM1 reduction in the proportions of (20.5, 30.8 and 43.9)% over and above that of the exotic strains (17.4, 30.0 and 41.1)% in 12 h, 48 h and 72 h of fermentation respectively. Generally, fermentation alone showed lower reduction of AFM1 in milk from 24.5% to 43.9% compared with the reducing activities of (35.4 to 58.8)% when heat-treated milk samples were subsequently subjected to varied fermentation conditions.展开更多
In this paper, by considering the stochastic proces s of the busy period and the idle period, and introducing the unfinished work as a supplementary variable, a new vector Markov process was presented to study th e M...In this paper, by considering the stochastic proces s of the busy period and the idle period, and introducing the unfinished work as a supplementary variable, a new vector Markov process was presented to study th e M/G/1 queue again. Through establishing and solving the density evolution equa tions, the busy-period distribution, and the stationary distributions of waitin g time and queue length were obtained. In addition, the stability condition of th is queue system was given by means of an imbedded renewal process.展开更多
When deciding on the best historic building retrofit,energy savings and thermal comfort can be quantitatively evaluated using an energy model,whereas conservation compatibility is intrinsically qualitative and reflect...When deciding on the best historic building retrofit,energy savings and thermal comfort can be quantitatively evaluated using an energy model,whereas conservation compatibility is intrinsically qualitative and reflects the perspective of the local heritage authority. We present a methodology that permits finding and comparing optimal retrofits for historic buildings in a multi-perspective and quantitative way. We use an analytic hierarchyprocess to quantify conservation compatibility by distilling a conservation score from the opinions of 10 experts in the field. This score,along with energy needs for heating and cooling and thermal comfort,are the three targets of a multi-objective optimization aimed at identifying optimal retrofits for a medieval building in the north of Italy,destined to become a museum. Retrofit measures considered were different kinds of external and internal envelope insulation,improvement of airtightness,replacement of windows,and ventilative cooling. The result is a portfolio of optimal retrofits that cover the whole range of conservation compatibility. We showthat in the analyzed case heritage preservation is compatible with a four-fold reduction in energy needs at a high thermal comfort level. Even higher energy savings are only achievable at the cost of heritage degradation.展开更多
During the tokamak operation, variation of the stored energy can cause internal perturbations of the plasma. These perturbations may develop into large-scale vertical movement of the whole column for the vertically el...During the tokamak operation, variation of the stored energy can cause internal perturbations of the plasma. These perturbations may develop into large-scale vertical movement of the whole column for the vertically elon- gated tokamak, eventually generating the hot vertical displacement event （VIDE,）. It will cause considerable damage to the machine. In this work, the hot VDE process due to stored energy perturbations is investigated by a mature non-linear time-evolution code DINA. The influence on the vertical instability, the displacement direction and the electromagnetic loads on in-vessel components during the hot VDE are analyzed. It is shown that a larger perturbation leads to faster development of the vertical instability. Meanwhile the variation of the Shafranov shift, due to the energy change, is related to the VDE direction. The vertical electromagnetic force on the vacuum vessel and the halo current flowing in the divertor baffle become larger in the case of VDE moving towards the X point.展开更多
A high-performance, distributed, complex-event processing en- gine with improved scalability is proposed. In this new engine, the stateless proeessing node is combined with distributed stor- age so that scale and perf...A high-performance, distributed, complex-event processing en- gine with improved scalability is proposed. In this new engine, the stateless proeessing node is combined with distributed stor- age so that scale and performance can be linearly expanded. This design prevents single node failure and makes the system highly reliable.展开更多
The 2D CCD camera has been used to take photos during hydrogen multi-pellet injection in HL-1M tokamak. The hydrogen multi-pellet (2 × 1.0 mm, 3× 1.2 mm, 3×1.2 ~ 1.3 mm) is horizontally injected into ...The 2D CCD camera has been used to take photos during hydrogen multi-pellet injection in HL-1M tokamak. The hydrogen multi-pellet (2 × 1.0 mm, 3× 1.2 mm, 3×1.2 ~ 1.3 mm) is horizontally injected into plasma. The observation is performed above the injection path at a sight angle 13.4°，As the shape of cloud ablation varies so quickly, the key points of the experiment have to be the high temporal resolution of CCD and the determination of pellet radial location in plasma. A series of improvements have been made with the experiment setup, including camera parameter, control (NA, ROI) and trigger mode, so as to satisfy the experiment requirements. Thus very nice photos along with the satisfying experimental results are obtained such as: (1) single exposure time reduced to 100 us (2) multi-frame in one discharge (FPS≥ 40) (3)multi-exposure for one pellet so that further observation of the temporal process of pellet ablation may be possible. Through the data analysis on the spatial distibution of pellet ablation clouds in photos taken, the pellet dimensions, trajectory of the cloud and pellet velocity are obtained, and the physical mechanism of pellet-plasma interactions also analyzed. In particular, it is possible to provide an effective means for measuring q-profile of HL-1M plasma.展开更多
Analyzing the traditional PBL teaching time, volume and number three dimensional space restrictions. Try to use resource allocation and IDEF3 process modeling method to solve.
In terms of second language acquisition or learning, research on anxiety has primarily focused on foreign language classroom anxiety or test anxiety, with little attention paid to anxiety in the process of writing aca...In terms of second language acquisition or learning, research on anxiety has primarily focused on foreign language classroom anxiety or test anxiety, with little attention paid to anxiety in the process of writing academic theses. This study aims to explore to what extent anxiety affects the whole process of three English majors writing their M.A. theses, as well as testing the relationships between anxiety and self-regulation in the whole process. The findings indicate that anxiety appears with high degree atthe preparation stage, slumps at the writing stage and reaches another high level at the revision stage. Anxiety also exists when negotiating with supervisors. What’s more, self-regulation has been proved to alleviate anxiety in the process of writing. This studycontributes new knowledge to the field by relating anxiety to self-regulation in the process of writing M.A. theses, yielding a deepened understanding of self-regulation that reduces anxiety in terms of the progress gradually achieved in the writing process. It alsohas implications for supervisors to pay attention to the way of negotiating with students that may cause anxiety during the academictheses writing process.展开更多
Streamers represent an important stage in the initiation of gap discharge. In this work, we used an eight-frame intensified charge-coupled device camera to capture the streamer development process when a lightning imp...Streamers represent an important stage in the initiation of gap discharge. In this work, we used an eight-frame intensified charge-coupled device camera to capture the streamer development process when a lightning impulse voltage of 95%–100% U50% was applied in a 3 m rod–plate gap and the streamer velocity was analyzed. Analysis of the observations shows that streamer velocity can be defined by three stages: rapid velocity decline(stage 1), rapid velocity rise(stage 2)and slow velocity decline(stage 3). The effects of electrode shape, applied voltage and gap breakdown or withstanding on streamer velocity were analyzed. The electrode with a larger radius of curvature will result in a higher initial velocity, and a higher voltage amplitude will cause the streamer to propagate faster at stage 3. Gap withstanding or breakdown has no obvious effect on streamer velocity. In addition, the experimental results are compared with previous results and the statistical characteristics of the primary streamer discharge are discussed.展开更多
文摘There is growing interest in developing high-voltage MOSFET devices that can be integrated with low-voltage CMOS digital and analog circuits. In this paper,high-voltage nand p-type MOSFETs are fabricated in a commercial 3.3/ 5V 0.5μm n-well CMOS process without adding any process steps using n-well and p-channel stops. High current and highvoltage transistors with breakdown voltages between 23 and 35V for the nMOS transistors with different laydut parameters and 19V for the pMOS transistors are achieved. This paper also presents the insulation technology and characterization results for these high-voltage devices.
文摘The technique to improve the performance of W/TiN stacked gate MOS capacitor with 3nm gate oxide is reported by optimizing the sputtering process of a refractory metal gate electrode and adopting a proper anneal temperature to eliminate the damages.Specific methods involved in the optimization of sputtering process include:selecting a proper TiN thickness to reduce stresses;using a smaller sputtering rate to suppress the damages to gate dielectric and adopting a higher N 2/Ar ratio during the TiN sputtering process to further nitride the gate dielectric.With these measures,excellent C V curves are obtained and surface state density ( N ss ) is successfully reduced to below 8×10 10 cm -2 ,which is comparable to the polysilicon gate MOS capacitor.
文摘The reducing efficiencies of the commonly used heat treatment methods and fermentation processes on aflatoxin M1 (AFM1) in Nigeria were investigated. Seventy samples of fresh cow milk from both conventional and traditional dairy cattle herds were collected and analyzed for the determination of AFM1 using Cobra-cell incorporated high performance liquid chromatography. Of these analyzed samples, 56 (80.0%) tested positive for AFM1 out of which 3 milk samples with high AFM1 concentrations were selectively pooled and subjected to varied conditions of heat treatments and fermentation processes using both indigenized and exotic strains of lactic acid bacteria (Lactobacillus bulgaricus + Streptococcus thermophilus and L. rhamnosus and L. plantarum) as starter cultures respectively. Both processes used either singly or combined, demonstrated high degrees of reducing effects on AFM1 levels. Sterilization of the milk at 121?C and 80?C under the same condition of time (15 - 20) min showed significant reduction of up to 58.8% (p 0.05) in the level of AFM1 when compared with the initial mean AFM1 concentration of the untreated fresh milk. The situation was however different around the boiling temperature of 100?C at which point the level of AFM1 reduction was found to be inconsistent. The indigenized combined strains showed some slight margins of AFM1 reduction in the proportions of (20.5, 30.8 and 43.9)% over and above that of the exotic strains (17.4, 30.0 and 41.1)% in 12 h, 48 h and 72 h of fermentation respectively. Generally, fermentation alone showed lower reduction of AFM1 in milk from 24.5% to 43.9% compared with the reducing activities of (35.4 to 58.8)% when heat-treated milk samples were subsequently subjected to varied fermentation conditions.
基金Project supported by the National Natural Science Foundation of China(Grant No.70171059)
文摘In this paper, by considering the stochastic proces s of the busy period and the idle period, and introducing the unfinished work as a supplementary variable, a new vector Markov process was presented to study th e M/G/1 queue again. Through establishing and solving the density evolution equa tions, the busy-period distribution, and the stationary distributions of waitin g time and queue length were obtained. In addition, the stability condition of th is queue system was given by means of an imbedded renewal process.
文摘When deciding on the best historic building retrofit,energy savings and thermal comfort can be quantitatively evaluated using an energy model,whereas conservation compatibility is intrinsically qualitative and reflects the perspective of the local heritage authority. We present a methodology that permits finding and comparing optimal retrofits for historic buildings in a multi-perspective and quantitative way. We use an analytic hierarchyprocess to quantify conservation compatibility by distilling a conservation score from the opinions of 10 experts in the field. This score,along with energy needs for heating and cooling and thermal comfort,are the three targets of a multi-objective optimization aimed at identifying optimal retrofits for a medieval building in the north of Italy,destined to become a museum. Retrofit measures considered were different kinds of external and internal envelope insulation,improvement of airtightness,replacement of windows,and ventilative cooling. The result is a portfolio of optimal retrofits that cover the whole range of conservation compatibility. We showthat in the analyzed case heritage preservation is compatible with a four-fold reduction in energy needs at a high thermal comfort level. Even higher energy savings are only achievable at the cost of heritage degradation.
基金Supported by the Chinese ITER Plan Project Foundation under Grant Nos 2013GB113001 and 2015GB105001the National Natural Science Foundation of China under Grant No 11575056
文摘During the tokamak operation, variation of the stored energy can cause internal perturbations of the plasma. These perturbations may develop into large-scale vertical movement of the whole column for the vertically elon- gated tokamak, eventually generating the hot vertical displacement event （VIDE,）. It will cause considerable damage to the machine. In this work, the hot VDE process due to stored energy perturbations is investigated by a mature non-linear time-evolution code DINA. The influence on the vertical instability, the displacement direction and the electromagnetic loads on in-vessel components during the hot VDE are analyzed. It is shown that a larger perturbation leads to faster development of the vertical instability. Meanwhile the variation of the Shafranov shift, due to the energy change, is related to the VDE direction. The vertical electromagnetic force on the vacuum vessel and the halo current flowing in the divertor baffle become larger in the case of VDE moving towards the X point.
文摘A high-performance, distributed, complex-event processing en- gine with improved scalability is proposed. In this new engine, the stateless proeessing node is combined with distributed stor- age so that scale and performance can be linearly expanded. This design prevents single node failure and makes the system highly reliable.
文摘The 2D CCD camera has been used to take photos during hydrogen multi-pellet injection in HL-1M tokamak. The hydrogen multi-pellet (2 × 1.0 mm, 3× 1.2 mm, 3×1.2 ~ 1.3 mm) is horizontally injected into plasma. The observation is performed above the injection path at a sight angle 13.4°，As the shape of cloud ablation varies so quickly, the key points of the experiment have to be the high temporal resolution of CCD and the determination of pellet radial location in plasma. A series of improvements have been made with the experiment setup, including camera parameter, control (NA, ROI) and trigger mode, so as to satisfy the experiment requirements. Thus very nice photos along with the satisfying experimental results are obtained such as: (1) single exposure time reduced to 100 us (2) multi-frame in one discharge (FPS≥ 40) (3)multi-exposure for one pellet so that further observation of the temporal process of pellet ablation may be possible. Through the data analysis on the spatial distibution of pellet ablation clouds in photos taken, the pellet dimensions, trajectory of the cloud and pellet velocity are obtained, and the physical mechanism of pellet-plasma interactions also analyzed. In particular, it is possible to provide an effective means for measuring q-profile of HL-1M plasma.
文摘Analyzing the traditional PBL teaching time, volume and number three dimensional space restrictions. Try to use resource allocation and IDEF3 process modeling method to solve.
文摘In terms of second language acquisition or learning, research on anxiety has primarily focused on foreign language classroom anxiety or test anxiety, with little attention paid to anxiety in the process of writing academic theses. This study aims to explore to what extent anxiety affects the whole process of three English majors writing their M.A. theses, as well as testing the relationships between anxiety and self-regulation in the whole process. The findings indicate that anxiety appears with high degree atthe preparation stage, slumps at the writing stage and reaches another high level at the revision stage. Anxiety also exists when negotiating with supervisors. What’s more, self-regulation has been proved to alleviate anxiety in the process of writing. This studycontributes new knowledge to the field by relating anxiety to self-regulation in the process of writing M.A. theses, yielding a deepened understanding of self-regulation that reduces anxiety in terms of the progress gradually achieved in the writing process. It alsohas implications for supervisors to pay attention to the way of negotiating with students that may cause anxiety during the academictheses writing process.
基金supported by the Beijing Science Fund for Distinguished Young Scholars(No.JQ22009)National Natural Science Foundation of China(No.51977198)。
文摘Streamers represent an important stage in the initiation of gap discharge. In this work, we used an eight-frame intensified charge-coupled device camera to capture the streamer development process when a lightning impulse voltage of 95%–100% U50% was applied in a 3 m rod–plate gap and the streamer velocity was analyzed. Analysis of the observations shows that streamer velocity can be defined by three stages: rapid velocity decline(stage 1), rapid velocity rise(stage 2)and slow velocity decline(stage 3). The effects of electrode shape, applied voltage and gap breakdown or withstanding on streamer velocity were analyzed. The electrode with a larger radius of curvature will result in a higher initial velocity, and a higher voltage amplitude will cause the streamer to propagate faster at stage 3. Gap withstanding or breakdown has no obvious effect on streamer velocity. In addition, the experimental results are compared with previous results and the statistical characteristics of the primary streamer discharge are discussed.
