为了实现对氮化镓高电子迁移率晶体管GaN HEMT(gallium nitride high electron mobility transistor)高速开关带来的开通过压、误导通、开关振荡和EMI噪声等问题展开定量的仿真分析,提出了一种基于建模数据和最优化算法的门极增强型GaN ...为了实现对氮化镓高电子迁移率晶体管GaN HEMT(gallium nitride high electron mobility transistor)高速开关带来的开通过压、误导通、开关振荡和EMI噪声等问题展开定量的仿真分析,提出了一种基于建模数据和最优化算法的门极增强型GaN HEMT电热行为模型建模方法。相比较于常规GaN HEMT行为模型,所提出的建模方法采用2个简单的建模公式实现了对GaN HEMT在第一和第三象限宽工作温度范围内的电热特性进行准确的建模。同时采用一个紧凑的建模公式实现对GaN HEMT非线性寄生电容的精确建模。此外,提出了一种遗传算法和Levenberg-Marquardt算法组合的优化算法,基于该优化算法和建模数据实现了对建模参数的快速提取,在较大程度上减小了建模时间和工作量。仿真表明,所提出的建模方法能够实现对不同公司多个型号的GaN HEMT器件展开精确的建模。最后通过吻合的动态仿真和实验数据验证了所提建模方法的正确性和有效性。展开更多
Web services are commonly perceived as an environment of both offering opportunities and threats. In this environment, one way to minimize threats is to use reputation evaluation, which can be computed, for example, t...Web services are commonly perceived as an environment of both offering opportunities and threats. In this environment, one way to minimize threats is to use reputation evaluation, which can be computed, for example, through transaction feedback. However, the current feedback-based approach is inaccurate and ineffective because of its inner limitations （e.g., feedback quality problem）. As the main source of feedback, the qualities of existing on-line reviews are often varied greatly from low to high, the main reasons include： （1） they have no standard expression formats, （2） dishonest comments may exist among these reviews due to malicious attacking. Up to present, the quality problem of review has not been well solved, which greatly degrades their importance on service reputation evaluation. Therefore, we firstly present a novel evaluation approach for review quality in terms of multiple metrics. Then, we make a further improvement in service reputation evaluation based on those filtered reviews. Experimental results show the effectiveness and efficiency of our proposed approach compared with the naive feedback-based approaches.展开更多
Burst buffer has become a major component to meet the I/O performance requirement of HPC bursty traffic.This paper proposes Gfarm/BB that is a file system for a burst buffer efficiently exploiting node-local storage s...Burst buffer has become a major component to meet the I/O performance requirement of HPC bursty traffic.This paper proposes Gfarm/BB that is a file system for a burst buffer efficiently exploiting node-local storage systems.Although node-local storages improve storage performance,they are only available during the job allocation.Gfarm/BB should have better access and metadata performance while it should be constructed on-demand before the job execution.To improve the read and write performance,it exploits the file descriptor passing and remote direct memory access(RDMA).It improves the metadata performance by omitting the persistency and the redundancy since it is a temporal file system.Using RDMA,writes and reads bandwidth are improved by 1.7x and 2.2x compared with IP over InfiniBand(IPoIB),respectively.It achieves 14700 operations per second in the directory creation performance,which is 13.4x faster than the fully persistent and redundant case.The construction of Gfarm/BB takes 0.31 seconds using 2 nodes.IOR benchmark and ARGOT-IO application I/O benchmark show the scalable performance improvement by exploiting the locality of node-local storages.Compared with BeeOND,Gfarm/BB shows 2.6x and 2.4x better performance in IOR write and read benchmarks,respectively,and it shows 2.5x better performance in ARGOT-IO.展开更多
Large displays have become ubiquitous in our everyday lives, but these displays are designed for sighted people.This paper addresses the need for visually impaired people to access targets on large wall-mounted displa...Large displays have become ubiquitous in our everyday lives, but these displays are designed for sighted people.This paper addresses the need for visually impaired people to access targets on large wall-mounted displays. We developed an assistive interface which exploits mid-air gesture input and haptic feedback, and examined its potential for pointing and steering tasks in human computer interaction（HCI）. In two experiments, blind and blindfolded users performed target acquisition tasks using mid-air gestures and two different kinds of feedback（i.e., haptic feedback and audio feedback）. Our results show that participants perform faster in Fitts＇ law pointing tasks using the haptic feedback interface rather than the audio feedback interface. Furthermore, a regression analysis between movement time（MT） and the index of difficulty（ID）demonstrates that the Fitts＇ law model and the steering law model are both effective for the evaluation of assistive interfaces for the blind. Our work and findings will serve as an initial step to assist visually impaired people to easily access required information on large public displays using haptic interfaces.展开更多
基金supported by the National Natural Science Foundation of China under Grant Nos.60603020,60496325 and 60573092
文摘Web services are commonly perceived as an environment of both offering opportunities and threats. In this environment, one way to minimize threats is to use reputation evaluation, which can be computed, for example, through transaction feedback. However, the current feedback-based approach is inaccurate and ineffective because of its inner limitations （e.g., feedback quality problem）. As the main source of feedback, the qualities of existing on-line reviews are often varied greatly from low to high, the main reasons include： （1） they have no standard expression formats, （2） dishonest comments may exist among these reviews due to malicious attacking. Up to present, the quality problem of review has not been well solved, which greatly degrades their importance on service reputation evaluation. Therefore, we firstly present a novel evaluation approach for review quality in terms of multiple metrics. Then, we make a further improvement in service reputation evaluation based on those filtered reviews. Experimental results show the effectiveness and efficiency of our proposed approach compared with the naive feedback-based approaches.
基金This work is partially supported by the JSPS KAKENHI Grant No.17H01748,JST CREST Grant No.JPMJCR1414New Energy and Industrial Technology Development Organization(NEDO),and Fujitsu Laboratories.
文摘Burst buffer has become a major component to meet the I/O performance requirement of HPC bursty traffic.This paper proposes Gfarm/BB that is a file system for a burst buffer efficiently exploiting node-local storage systems.Although node-local storages improve storage performance,they are only available during the job allocation.Gfarm/BB should have better access and metadata performance while it should be constructed on-demand before the job execution.To improve the read and write performance,it exploits the file descriptor passing and remote direct memory access(RDMA).It improves the metadata performance by omitting the persistency and the redundancy since it is a temporal file system.Using RDMA,writes and reads bandwidth are improved by 1.7x and 2.2x compared with IP over InfiniBand(IPoIB),respectively.It achieves 14700 operations per second in the directory creation performance,which is 13.4x faster than the fully persistent and redundant case.The construction of Gfarm/BB takes 0.31 seconds using 2 nodes.IOR benchmark and ARGOT-IO application I/O benchmark show the scalable performance improvement by exploiting the locality of node-local storages.Compared with BeeOND,Gfarm/BB shows 2.6x and 2.4x better performance in IOR write and read benchmarks,respectively,and it shows 2.5x better performance in ARGOT-IO.
基金partially supported by the National Natural Science Foundation of China under Grant No.61228206the Grant-in-Aid for Scientific Research of Japan under Grant Nos.23300048 and 25330241
文摘Large displays have become ubiquitous in our everyday lives, but these displays are designed for sighted people.This paper addresses the need for visually impaired people to access targets on large wall-mounted displays. We developed an assistive interface which exploits mid-air gesture input and haptic feedback, and examined its potential for pointing and steering tasks in human computer interaction（HCI）. In two experiments, blind and blindfolded users performed target acquisition tasks using mid-air gestures and two different kinds of feedback（i.e., haptic feedback and audio feedback）. Our results show that participants perform faster in Fitts＇ law pointing tasks using the haptic feedback interface rather than the audio feedback interface. Furthermore, a regression analysis between movement time（MT） and the index of difficulty（ID）demonstrates that the Fitts＇ law model and the steering law model are both effective for the evaluation of assistive interfaces for the blind. Our work and findings will serve as an initial step to assist visually impaired people to easily access required information on large public displays using haptic interfaces.
