It’s never too early in the year to start planning a break from the stress of city life,and southwest China’s charming Guizhou Province is a destination that should be right at the top of your list.
The burst error of wireless channels and the two-state Markov wireless model are analyzed. Based on this model and the coding modes of the video encoder,the channel distortion of inter-coding and intra-coding due to b...The burst error of wireless channels and the two-state Markov wireless model are analyzed. Based on this model and the coding modes of the video encoder,the channel distortion of inter-coding and intra-coding due to burst error is deduced. Then we propose a novel intra refresh scheme in rate-distortion (R-D) framework. This scheme optimizes the error resilience and coding efficiency of wireless video transmission system. It can also stop error propagation and reduce channel distortion effectively. Simulations under different channel conditions verify the improvements of the proposed scheme with respect to error resilience for wireless video communication.展开更多
A dual-resolution（DR） version of a regional ensemble Kalman filter（EnKF）-3D ensemble variational（3DEnVar） coupled hybrid data assimilation system is implemented as a prototype for the operational Rapid Refresh f...A dual-resolution（DR） version of a regional ensemble Kalman filter（EnKF）-3D ensemble variational（3DEnVar） coupled hybrid data assimilation system is implemented as a prototype for the operational Rapid Refresh forecasting system. The DR 3DEnVar system combines a high-resolution（HR） deterministic background forecast with lower-resolution（LR） EnKF ensemble perturbations used for flow-dependent background error covariance to produce a HR analysis. The computational cost is substantially reduced by running the ensemble forecasts and EnKF analyses at LR. The DR 3DEnVar system is tested with 3-h cycles over a 9-day period using a 40/13-km grid spacing combination. The HR forecasts from the DR hybrid analyses are compared with forecasts launched from HR Gridpoint Statistical Interpolation（GSI） 3D variational（3DVar）analyses, and single LR hybrid analyses interpolated to the HR grid. With the DR 3DEnVar system, a 90% weight for the ensemble covariance yields the lowest forecast errors and the DR hybrid system clearly outperforms the HR GSI 3DVar.Humidity and wind forecasts are also better than those launched from interpolated LR hybrid analyses, but the temperature forecasts are slightly worse. The humidity forecasts are improved most. For precipitation forecasts, the DR 3DEnVar always outperforms HR GSI 3DVar. It also outperforms the LR 3DEnVar, except for the initial forecast period and lower thresholds.展开更多
The paper presents the research results of using an innovative method to reclaim the waste moulding sands containing water glass. Two of the examined processes are connected with "dry" or "wet" act...The paper presents the research results of using an innovative method to reclaim the waste moulding sands containing water glass. Two of the examined processes are connected with "dry" or "wet" activation of inorganic binder in waste moulding sand mixtures physically hardened by microwave radiation. The sand mixtures consisting of high-silica sand and water-glass with average molar module 2.5, were subjected to the following cyclical process: mixing the components, compacting, microwave heating, cooling-down, thermally loading the mould to 800 °C, cooling-down to ambient temperature, and knocking-out. After being knocked-out, the waste moulding sands were subjected to either dry or wet activation of the binder. To activate thermally treated inorganic binder, each of the examined processes employed the surface phenomenon usually associated to mechanical reclamation. The study also covered possible use of some elements of wet reclamation to rehydrate waste binder. To evaluate the effectiveness of the two proposed methods of waste binder activation, selected strength and technological parameters were measured. After each subsequent processing cycle, the permeability, tensile strength and bending strength were determined. In addition, the surface of activated sand grains was examined with a scanning electron microscope. Analysis of the results indicates that it is possible to re-activate the used binder such as sodium silicate, and to stabilize the strength parameters in both activation processes. Permeability of the refreshed moulding sands strongly depends on the surface condition of high-silica grains. The wet activation process by wetting and buffering knocked-out moulding sands in closed humid environment makes it possible to reduce the content of refreshing additive in water-glass. The moulding sands cyclically prepared in both processes do not require the addition of fresh high-silica sand. The relatively high quality achieved in the refreshed moulding sands allows them to be reused for manufacture of next moulds. Thus, the two proposed methods for cyclically processing used moulding sands containing sodium silicate, subject to microwave hardening, are suitable for economic and ecological circulation moulding mixtures.展开更多
The partial cycle(PC)strategy has been used in many rapid refresh cycle systems(RRC)for regional short-range weather forecasting.Since the strategy periodically reinitializes the regional model(RM)from the global mode...The partial cycle(PC)strategy has been used in many rapid refresh cycle systems(RRC)for regional short-range weather forecasting.Since the strategy periodically reinitializes the regional model(RM)from the global model(GM)forecasts to correct the large-scale drift,it has replaced the traditional full cycle(FC)strategy in many RRC systems.However,the extra spin-up in the PC strategy increases the computer burden on RRC and generates discontinuous smallscale systems among cycles.This study returns to the FC strategy but with initial fields generated by dynamic blending(DB)and data assimilation(DA).The DB ingests the time-varied large-scale information from the GM to the RM to generate less-biased background fields.Then the DA is performed.We applied the new FC strategy in a series of 7-day batch forecasts with the 3-hour cycle in July 2018,and February,April,and October 2019 over China using a Weather Research and Forecast(WRF)model-based RRC.A comparison shows that the new FC strategy results in less model bias than the PC strategy in most state variables and improves the forecast skills for moderate and light precipitation.The new FC strategy also allows the model to reach a balanced state earlier and gives favorable forecast continuity between adjacent cycles.Hence,this new FC strategy has potential to be applied in RRC forecast systems to replace the currently used PC strategy.展开更多
The recently reported quasi-nonvolatile memory based on semi-floating gate architecture has attracted extensive attention thanks to its potential to bridge the large gap between volatile and nonvolatile memory.However...The recently reported quasi-nonvolatile memory based on semi-floating gate architecture has attracted extensive attention thanks to its potential to bridge the large gap between volatile and nonvolatile memory.However,the further extension of the refresh time in quasi-nonvolatile memory is limited by the charge leakage through the p-n junction.Here,based on the density of states engineered van der Waals heterostructures,the leakage of electrons from the floating gate to the channel is greatly suppressed.As a result,the refresh time is effectively extended to more than 100 s,which is the longest among all previously reported quasi-nonvolatile memories.This work provides a new idea to enhance the refresh time of quasi-nonvolatile memory by the density of states engineering and demonstrates great application potential for high-speed and low-power memory technology.展开更多
We propose a novel prioritized intra refresh method for the wireless video communication.The proposed method considers the characteristics of the human visual system,the error-sensitivity of the bitstream,and the stat...We propose a novel prioritized intra refresh method for the wireless video communication.The proposed method considers the characteristics of the human visual system,the error-sensitivity of the bitstream,and the state of the time-varying wireless channel jointly.An expected perceptual distortion model was used to adjust the intra refresh rate adaptively.This model consists of the perceptual weight map based on an attention model,the bit error probability map based on bitstream size,and the dynamic channel state information(CSI).Experimental results indicate that,compared with other intra refresh methods that consider only the content of the video or the CSI,the proposed method improves the average peak signal-to-noise ratio(PSNR) of the whole frame by about 0.5 dB,and improves the average PSNR of the attention-area by about 0.8 dB.展开更多
For video streaming over lossy channels, intra refresh can mitigate the error-propagation effect caused by packet losses Besides some intra-mode macroblocks （MBs） generated by the ＂Lagrangian rate-distortion＂ or ...For video streaming over lossy channels, intra refresh can mitigate the error-propagation effect caused by packet losses Besides some intra-mode macroblocks （MBs） generated by the ＂Lagrangian rate-distortion＂ or ＂Sum of absolute difference＂ mode decision, the encoder or transcoder possibly needs to increase some ＂forced＂ intra-mode MBs for robust video streaming. Based on the error-propagation analysis in a group of pictures （GOP）, we propose an unequal Forced-Intra-Refresh （FIR） scheme to improve packet loss resilience of video streaming. According to a GOP-level error-propagation model, the proposed unequal FIR scheme can optimally increase the unequal number of forced intra-mode MBs for different frames in a GOP. Simulation results showed that the proposed scheme can effectively enhance the robustness of video streaming under different channel conditions, and achieve about 0. 1-0.9 dB gains over the average FIR scheme in H.264/AVC tools.展开更多
<正> Like most July days,it was hot. I stepped into a tiny ice-cream shop to cool off with a chocolate sundae. It was an old-time store, just recently restored—~* with white oak wood-work,little round tables an...<正> Like most July days,it was hot. I stepped into a tiny ice-cream shop to cool off with a chocolate sundae. It was an old-time store, just recently restored—~* with white oak wood-work,little round tables and curlicue chairs.As I entered, 1 caught a glimpse of a very old woman bentover a table near the door.~* Her back was so badly twisted展开更多
在第四代迅驰平台Sonta Rosa发布八个月之后,名为Sonta Rosa Refresh的平台正式于2008年1月8日发布。正如人们之前预料的那样,它在保持芯片组和无线模块等组件不变的基础上,将基于第五代迅驰平台(Montevina),代号为Penryn的45纳米处理...在第四代迅驰平台Sonta Rosa发布八个月之后,名为Sonta Rosa Refresh的平台正式于2008年1月8日发布。正如人们之前预料的那样,它在保持芯片组和无线模块等组件不变的基础上,将基于第五代迅驰平台(Montevina),代号为Penryn的45纳米处理器提前应用到现有平台当中。那么,新规格的Penryn处理器有哪些优化设计? Penryn处理器的加入能给迅驰平台带来多大的性能提升?Santa Rosa Refresh平台体现在游戏上又有怎么样的表现呢?展开更多
Intra refresh is an efficient and simple technique for suppressing temporal error propagation in video transmission over error-prone networks. However, most existing intra refresh algorithms do not make good use of th...Intra refresh is an efficient and simple technique for suppressing temporal error propagation in video transmission over error-prone networks. However, most existing intra refresh algorithms do not make good use of the visual perceptual mechanism of the Human Visual System （HVS）. This paper presents an intra refresh algorithm based on an attention model and a loss impact model. Intra refresh rates are allowed to vary for different image regions according to the HVS characteristic and the channel conditions to protect the most important macro-blocks against packet loss. A joint source-channel rate-distortion model was de- veloped taking into account the HVS characteristic to achieve an optimal end-to-end distortion for a better subjective quality. Tests demonstrate that, for the same bit rate and packet loss rate, this method provides a much better subjective feeling than existing intra refresh methods.展开更多
This paper focuses on the mechanism underlying the overall delay of a real-time video communication system from the time of capture at the encoder to the time of display at the decoder. A detailed analysis is presente...This paper focuses on the mechanism underlying the overall delay of a real-time video communication system from the time of capture at the encoder to the time of display at the decoder. A detailed analysis is presented to illustrate the delay problem. We then describe a statistically uniform intra-block refresh scheme for very low delay video communication. By scattering intra-blocks uniformly into continuous frames, the overall delay is significantly decreased, and object changes in the scene could be presented to the end user instantly. For comparison, the overall delay and the peak signal-to-noise ratio (PSNR) performance are tested. The experiment results show that an average of approximately 0.1 dB PSNR gain on average is obtained relative to random intra-macroblock refresh algorithm in H.264 JM, and the end-to-end delay performance is significantly improved.展开更多
Dynamic random access memory(DRAM) is facing the challenge of technology scaling. The decreasing feature size makes it harder to make DRAM cells which can keep the current data-holding time. When DRAM cells cannot hol...Dynamic random access memory(DRAM) is facing the challenge of technology scaling. The decreasing feature size makes it harder to make DRAM cells which can keep the current data-holding time. When DRAM cells cannot hold data for a long time, DRAM chips need a more frequent refreshing operation. Therefore, in the near future, time and energy cost on DRAM refreshing will be no longer trivial. In this paper, we propose DRAM Error Correction Pointer(ECP), an error-correction-manner framework, to reduce DRAM refreshes without data loss. We exploit the non-uniform feature of DRAM cells with respect to the data retention time. Compared with the conventional refreshing mechanisms, which refresh DRAM chips by the retention time of the leakiest cells, we refresh the chips much fewer times, and treat the not-in-time refreshed cells as fault elements. We use the structure of ECP as a fault tolerant element. By recording the data which are supposed to be written into the leaky cells in our DRAM-ECP structures, DRAM-ECP can significantly decrease refreshing frequency. When these data are to be read out, DRAM-ECP retrieves the data stored in ECPs and covers them to the corresponding position in the data row. Our experiments show that DRAM-ECP can reduce over 70%refreshing operations than the current refreshing mechanism and also get significant energy saving.展开更多
Focused ion beam (FIB) machining can be used to fabricate gallium arsenide-based devices, which have a surface fnish of several nanometers, and the FIB machining speed and surface fnish can be greatly improved using x...Focused ion beam (FIB) machining can be used to fabricate gallium arsenide-based devices, which have a surface fnish of several nanometers, and the FIB machining speed and surface fnish can be greatly improved using xenon difuoride (XeF2) gas-assisted etching. Although the refresh time is one of the most important parameters in the gas-assisted etching process, its efect on the machining quality of the surface fnish has rarely been studied. Therefore, in this work, we investigated the efect of the refresh time on the etching process, including the dissociation process of XeF2, the refresh time dependency of the sputter in yield under diferent incident angles, and the surface fnish under diferent refresh times. The results revealed that a selective etching mechanism occurred at diferent refresh times. At an incidence angle of 0°, the sputtering yield increased with the refresh time and reached its maximum value at 500 ms;at an incidence angle of 30°, the sputtering yield reached its minimum value at a refresh time of 500 ms. For surface roughness, the incident angle played a more important role than the refresh time. The surface fnish was slightly better at an incidence angle of 30° than at 0°. In addition, both F and Xe elements were detected in the processed area: Xe elements were evenly distributed throughout the processing area, while F elements tended to accumulate in the whole processing area. The results suggest that the optimum surface can be obtained when a larger refresh time is employed.展开更多
In late May,the city of Dunhuang,a key historical hub of Eastern and Western cultures in Northwest China's Gansu Province,basked in clear and refreshing weather under a brilliant blue sky.The rugged Mingsha Mounta...In late May,the city of Dunhuang,a key historical hub of Eastern and Western cultures in Northwest China's Gansu Province,basked in clear and refreshing weather under a brilliant blue sky.The rugged Mingsha Mountain,renowned for the musical sounds produced by wind-blown sands when the wind blows,stood in silent majesty.To the close north of the mountain's massive golden dunes stood the city's international convention centre,where some 400 vips from 60 countries host cultural exchanges and mutual learning.展开更多
文摘It’s never too early in the year to start planning a break from the stress of city life,and southwest China’s charming Guizhou Province is a destination that should be right at the top of your list.
文摘The burst error of wireless channels and the two-state Markov wireless model are analyzed. Based on this model and the coding modes of the video encoder,the channel distortion of inter-coding and intra-coding due to burst error is deduced. Then we propose a novel intra refresh scheme in rate-distortion (R-D) framework. This scheme optimizes the error resilience and coding efficiency of wireless video transmission system. It can also stop error propagation and reduce channel distortion effectively. Simulations under different channel conditions verify the improvements of the proposed scheme with respect to error resilience for wireless video communication.
基金supported by the National Natural Science Foundation of China (Grant Nos.41730965,41775099 and 2017YFC1502104)PAPD (the Priority Academic Program Development of Jiangsu Higher Education Institutions)
文摘A dual-resolution（DR） version of a regional ensemble Kalman filter（EnKF）-3D ensemble variational（3DEnVar） coupled hybrid data assimilation system is implemented as a prototype for the operational Rapid Refresh forecasting system. The DR 3DEnVar system combines a high-resolution（HR） deterministic background forecast with lower-resolution（LR） EnKF ensemble perturbations used for flow-dependent background error covariance to produce a HR analysis. The computational cost is substantially reduced by running the ensemble forecasts and EnKF analyses at LR. The DR 3DEnVar system is tested with 3-h cycles over a 9-day period using a 40/13-km grid spacing combination. The HR forecasts from the DR hybrid analyses are compared with forecasts launched from HR Gridpoint Statistical Interpolation（GSI） 3D variational（3DVar）analyses, and single LR hybrid analyses interpolated to the HR grid. With the DR 3DEnVar system, a 90% weight for the ensemble covariance yields the lowest forecast errors and the DR hybrid system clearly outperforms the HR GSI 3DVar.Humidity and wind forecasts are also better than those launched from interpolated LR hybrid analyses, but the temperature forecasts are slightly worse. The humidity forecasts are improved most. For precipitation forecasts, the DR 3DEnVar always outperforms HR GSI 3DVar. It also outperforms the LR 3DEnVar, except for the initial forecast period and lower thresholds.
基金co-financed by the European Union within the European Social Fund in the project"Mloda Kadra 2015+"
文摘The paper presents the research results of using an innovative method to reclaim the waste moulding sands containing water glass. Two of the examined processes are connected with "dry" or "wet" activation of inorganic binder in waste moulding sand mixtures physically hardened by microwave radiation. The sand mixtures consisting of high-silica sand and water-glass with average molar module 2.5, were subjected to the following cyclical process: mixing the components, compacting, microwave heating, cooling-down, thermally loading the mould to 800 °C, cooling-down to ambient temperature, and knocking-out. After being knocked-out, the waste moulding sands were subjected to either dry or wet activation of the binder. To activate thermally treated inorganic binder, each of the examined processes employed the surface phenomenon usually associated to mechanical reclamation. The study also covered possible use of some elements of wet reclamation to rehydrate waste binder. To evaluate the effectiveness of the two proposed methods of waste binder activation, selected strength and technological parameters were measured. After each subsequent processing cycle, the permeability, tensile strength and bending strength were determined. In addition, the surface of activated sand grains was examined with a scanning electron microscope. Analysis of the results indicates that it is possible to re-activate the used binder such as sodium silicate, and to stabilize the strength parameters in both activation processes. Permeability of the refreshed moulding sands strongly depends on the surface condition of high-silica grains. The wet activation process by wetting and buffering knocked-out moulding sands in closed humid environment makes it possible to reduce the content of refreshing additive in water-glass. The moulding sands cyclically prepared in both processes do not require the addition of fresh high-silica sand. The relatively high quality achieved in the refreshed moulding sands allows them to be reused for manufacture of next moulds. Thus, the two proposed methods for cyclically processing used moulding sands containing sodium silicate, subject to microwave hardening, are suitable for economic and ecological circulation moulding mixtures.
基金the two anonymous reviewers.This work is supported by the National Key R&D Program of China(2018YFC1506803,2019YFB2102901)National Natural Science Foundation of China(Grant 41705135,41790474).
文摘The partial cycle(PC)strategy has been used in many rapid refresh cycle systems(RRC)for regional short-range weather forecasting.Since the strategy periodically reinitializes the regional model(RM)from the global model(GM)forecasts to correct the large-scale drift,it has replaced the traditional full cycle(FC)strategy in many RRC systems.However,the extra spin-up in the PC strategy increases the computer burden on RRC and generates discontinuous smallscale systems among cycles.This study returns to the FC strategy but with initial fields generated by dynamic blending(DB)and data assimilation(DA).The DB ingests the time-varied large-scale information from the GM to the RM to generate less-biased background fields.Then the DA is performed.We applied the new FC strategy in a series of 7-day batch forecasts with the 3-hour cycle in July 2018,and February,April,and October 2019 over China using a Weather Research and Forecast(WRF)model-based RRC.A comparison shows that the new FC strategy results in less model bias than the PC strategy in most state variables and improves the forecast skills for moderate and light precipitation.The new FC strategy also allows the model to reach a balanced state earlier and gives favorable forecast continuity between adjacent cycles.Hence,this new FC strategy has potential to be applied in RRC forecast systems to replace the currently used PC strategy.
基金This work was supported by the National Natural Science Foundation of China(61925402,61851402 and 61734003)Science and Technology Commission of Shanghai Municipality(19JC1416600)+2 种基金National Key Research and Development Program(2017YFB0405600)Shanghai Education Development Foundation and Shanghai Municipal Education Commission Shuguang Program(18SG01)China Postdoctoral Science Foundation(2019M661358,2019TQ0065).
文摘The recently reported quasi-nonvolatile memory based on semi-floating gate architecture has attracted extensive attention thanks to its potential to bridge the large gap between volatile and nonvolatile memory.However,the further extension of the refresh time in quasi-nonvolatile memory is limited by the charge leakage through the p-n junction.Here,based on the density of states engineered van der Waals heterostructures,the leakage of electrons from the floating gate to the channel is greatly suppressed.As a result,the refresh time is effectively extended to more than 100 s,which is the longest among all previously reported quasi-nonvolatile memories.This work provides a new idea to enhance the refresh time of quasi-nonvolatile memory by the density of states engineering and demonstrates great application potential for high-speed and low-power memory technology.
文摘We propose a novel prioritized intra refresh method for the wireless video communication.The proposed method considers the characteristics of the human visual system,the error-sensitivity of the bitstream,and the state of the time-varying wireless channel jointly.An expected perceptual distortion model was used to adjust the intra refresh rate adaptively.This model consists of the perceptual weight map based on an attention model,the bit error probability map based on bitstream size,and the dynamic channel state information(CSI).Experimental results indicate that,compared with other intra refresh methods that consider only the content of the video or the CSI,the proposed method improves the average peak signal-to-noise ratio(PSNR) of the whole frame by about 0.5 dB,and improves the average PSNR of the attention-area by about 0.8 dB.
基金Project (No. 60332030) supported by the National Natural ScienceFoundation of China
文摘For video streaming over lossy channels, intra refresh can mitigate the error-propagation effect caused by packet losses Besides some intra-mode macroblocks （MBs） generated by the ＂Lagrangian rate-distortion＂ or ＂Sum of absolute difference＂ mode decision, the encoder or transcoder possibly needs to increase some ＂forced＂ intra-mode MBs for robust video streaming. Based on the error-propagation analysis in a group of pictures （GOP）, we propose an unequal Forced-Intra-Refresh （FIR） scheme to improve packet loss resilience of video streaming. According to a GOP-level error-propagation model, the proposed unequal FIR scheme can optimally increase the unequal number of forced intra-mode MBs for different frames in a GOP. Simulation results showed that the proposed scheme can effectively enhance the robustness of video streaming under different channel conditions, and achieve about 0. 1-0.9 dB gains over the average FIR scheme in H.264/AVC tools.
文摘<正> Like most July days,it was hot. I stepped into a tiny ice-cream shop to cool off with a chocolate sundae. It was an old-time store, just recently restored—~* with white oak wood-work,little round tables and curlicue chairs.As I entered, 1 caught a glimpse of a very old woman bentover a table near the door.~* Her back was so badly twisted
文摘在第四代迅驰平台Sonta Rosa发布八个月之后,名为Sonta Rosa Refresh的平台正式于2008年1月8日发布。正如人们之前预料的那样,它在保持芯片组和无线模块等组件不变的基础上,将基于第五代迅驰平台(Montevina),代号为Penryn的45纳米处理器提前应用到现有平台当中。那么,新规格的Penryn处理器有哪些优化设计? Penryn处理器的加入能给迅驰平台带来多大的性能提升?Santa Rosa Refresh平台体现在游戏上又有怎么样的表现呢?
基金Supported by the National Natural Science Foundation of China(No. 60572081)
文摘Intra refresh is an efficient and simple technique for suppressing temporal error propagation in video transmission over error-prone networks. However, most existing intra refresh algorithms do not make good use of the visual perceptual mechanism of the Human Visual System （HVS）. This paper presents an intra refresh algorithm based on an attention model and a loss impact model. Intra refresh rates are allowed to vary for different image regions according to the HVS characteristic and the channel conditions to protect the most important macro-blocks against packet loss. A joint source-channel rate-distortion model was de- veloped taking into account the HVS characteristic to achieve an optimal end-to-end distortion for a better subjective quality. Tests demonstrate that, for the same bit rate and packet loss rate, this method provides a much better subjective feeling than existing intra refresh methods.
基金Project partially supported by the Fundamental Research Funds for the Central Universitiesthe 111 Project Program for Changjiang Scholars and Innovative Research Team in University (No. B08038),China
文摘This paper focuses on the mechanism underlying the overall delay of a real-time video communication system from the time of capture at the encoder to the time of display at the decoder. A detailed analysis is presented to illustrate the delay problem. We then describe a statistically uniform intra-block refresh scheme for very low delay video communication. By scattering intra-blocks uniformly into continuous frames, the overall delay is significantly decreased, and object changes in the scene could be presented to the end user instantly. For comparison, the overall delay and the peak signal-to-noise ratio (PSNR) performance are tested. The experiment results show that an average of approximately 0.1 dB PSNR gain on average is obtained relative to random intra-macroblock refresh algorithm in H.264 JM, and the end-to-end delay performance is significantly improved.
基金supported by National High-tech R&D Program of China(863 Program)(Grant No.2012AA01A3-02)National Natural Science Foundation of China(Grant Nos.61133004+2 种基金61361126011)State Key Laboratory of Software Development Environment(Grant No.SKLSDE-2013ZX-22)Open Project Program of the State Key Laboratory of Mathematical Engineering and Advanced Computing
文摘Dynamic random access memory(DRAM) is facing the challenge of technology scaling. The decreasing feature size makes it harder to make DRAM cells which can keep the current data-holding time. When DRAM cells cannot hold data for a long time, DRAM chips need a more frequent refreshing operation. Therefore, in the near future, time and energy cost on DRAM refreshing will be no longer trivial. In this paper, we propose DRAM Error Correction Pointer(ECP), an error-correction-manner framework, to reduce DRAM refreshes without data loss. We exploit the non-uniform feature of DRAM cells with respect to the data retention time. Compared with the conventional refreshing mechanisms, which refresh DRAM chips by the retention time of the leakiest cells, we refresh the chips much fewer times, and treat the not-in-time refreshed cells as fault elements. We use the structure of ECP as a fault tolerant element. By recording the data which are supposed to be written into the leaky cells in our DRAM-ECP structures, DRAM-ECP can significantly decrease refreshing frequency. When these data are to be read out, DRAM-ECP retrieves the data stored in ECPs and covers them to the corresponding position in the data row. Our experiments show that DRAM-ECP can reduce over 70%refreshing operations than the current refreshing mechanism and also get significant energy saving.
基金The authors gratefully acknowledge the startup funding support by the Dalian University of Technology(DUT)(Award No.82232022,82232043,and DUT22LAB404)。
文摘Focused ion beam (FIB) machining can be used to fabricate gallium arsenide-based devices, which have a surface fnish of several nanometers, and the FIB machining speed and surface fnish can be greatly improved using xenon difuoride (XeF2) gas-assisted etching. Although the refresh time is one of the most important parameters in the gas-assisted etching process, its efect on the machining quality of the surface fnish has rarely been studied. Therefore, in this work, we investigated the efect of the refresh time on the etching process, including the dissociation process of XeF2, the refresh time dependency of the sputter in yield under diferent incident angles, and the surface fnish under diferent refresh times. The results revealed that a selective etching mechanism occurred at diferent refresh times. At an incidence angle of 0°, the sputtering yield increased with the refresh time and reached its maximum value at 500 ms;at an incidence angle of 30°, the sputtering yield reached its minimum value at a refresh time of 500 ms. For surface roughness, the incident angle played a more important role than the refresh time. The surface fnish was slightly better at an incidence angle of 30° than at 0°. In addition, both F and Xe elements were detected in the processed area: Xe elements were evenly distributed throughout the processing area, while F elements tended to accumulate in the whole processing area. The results suggest that the optimum surface can be obtained when a larger refresh time is employed.
文摘Lexus’After-sales Services upgrade:From July 1 to August 31,Lexus introduces the Summer Refreshing vehicle maintenance program to owners across China.
文摘In late May,the city of Dunhuang,a key historical hub of Eastern and Western cultures in Northwest China's Gansu Province,basked in clear and refreshing weather under a brilliant blue sky.The rugged Mingsha Mountain,renowned for the musical sounds produced by wind-blown sands when the wind blows,stood in silent majesty.To the close north of the mountain's massive golden dunes stood the city's international convention centre,where some 400 vips from 60 countries host cultural exchanges and mutual learning.
