We theoretically analyze the organizing filament of small amplitude scroll waves in general excitable media by perturbation method and explicitly give the expressions of coefficients in Keener theory. In particular fo...We theoretically analyze the organizing filament of small amplitude scroll waves in general excitable media by perturbation method and explicitly give the expressions of coefficients in Keener theory. In particular for the excitable media with equal diffusion, we obtain a close system for the motion of the filament. With an example of the Oregonator model, our results are in good agreement with those simulated by Winfree.展开更多
The paper introduces the characteristics of a new type washing machine (mini washing machine) and analyzes the global problems solved by mini washing machines from the perspective of meeting different consumers'ne...The paper introduces the characteristics of a new type washing machine (mini washing machine) and analyzes the global problems solved by mini washing machines from the perspective of meeting different consumers'needs. On the basis of current performance specifications of IEC 60456, it explains how to improve the performance test method of mini washing machine in details, and points out the direction of standards research and test improvement. Meanwhile, the author briefs about other new type washing machines and the developmental trend of washing machines.展开更多
In the framework of the heavy quark effective theory, the leading order Isgur-Wise functions relevant to semileptonie decays of the orbitally P-wave excited Bs meson states Bs＊, including the newly found narrow Bs1 ...In the framework of the heavy quark effective theory, the leading order Isgur-Wise functions relevant to semileptonie decays of the orbitally P-wave excited Bs meson states Bs＊, including the newly found narrow Bs1 （5830） andBs2（5840） states, into the （Ds1（2536）, Ds2（2573）） doublet are calculated from QCD sum rules. With these universal form factors, the decay rates and branching ratios are also estimated.展开更多
The B-meson decay constant fB is an important component for studying the B-meson decays, which can be studied through QCD sum rules. We make a detailed discussion on f B from two sum rules up to next-to- leading order...The B-meson decay constant fB is an important component for studying the B-meson decays, which can be studied through QCD sum rules. We make a detailed discussion on f B from two sum rules up to next-to- leading order, i.e. sum rules I and II, which are derived from the conventional correlator and the correlator with chiral currents respectively. It is found that these two sum rules are consistent with each other. The sum rules H involves less non-perturbative condensates as that of sum rules I, and in principle, it can be more accurate if we know the dimensionfour gluon condensate well. It is found that fB decreases with the increment of mb, and to compare with the Belle experimental data on fB, both sum rules I and H prefer smaller pole b-quark mass, mb= 4.68 ± 0.07 GeV. By varying all the input parameters within their reasonable regions and by adding all the uncertainties in quadrature, we obtain fB=172-25^＋23 MeV for sum rules I and fB =214-34^26 MeV for sum rules П.展开更多
Following a cross-sectional design, the present study investigated the acquisition of English requests by Chinese learners at three proficiency levels with open production questionnaires. It was found that L2 linguist...Following a cross-sectional design, the present study investigated the acquisition of English requests by Chinese learners at three proficiency levels with open production questionnaires. It was found that L2 linguistic proficiency, L1 pragmatic transfer and classroom instruction have interactive effect on learners' L2 pragmatic development. A range of acquisitional features were found-learners' employment of direct request strategies decreased, the employment of conventionally indirect strategies increased and the number and variety of internal modifiers increased with the increase of proficiency. It was also found that L1 pragmatic transfer worked on various aspects of learners' requestive behavior and that inadequate or inappropriate input from the teaching materials and the EFL classroom arrangements might constrain their pragmatic development.展开更多
The paper presents a new fast integral equation solver for Maxwell＇s equations in 3-D layered media. First, the spectral domain dyadic Green＇s function is derived, and the 0-th and the 1-st order Hankel transforms o...The paper presents a new fast integral equation solver for Maxwell＇s equations in 3-D layered media. First, the spectral domain dyadic Green＇s function is derived, and the 0-th and the 1-st order Hankel transforms or Sommerfeld-type integrals are used to recover all components of the dyadic Green＇s function in real space. The Hankel transforms are performed with the adaptive generalized Gaussian quadrature points and window functions to minimize the computational cost. Subsequently, a fast integral equation solver with O（N2zNxNy log（NzNy）） in layered media is developed by rewriting the layered media integral operator in terms of Hankel transforms and using the new fast multipole method for the n-th order Bessel function in 2-D. Computational cost and parallel efficiency of the new algorithm are presented.展开更多
Various flexible mechanisms related to quality of service （QoS） provisioning have been specified for uplink traffic at the medium access control （MAC） layer in the IEEE 802.16 standards. Among the mechanisms, cont...Various flexible mechanisms related to quality of service （QoS） provisioning have been specified for uplink traffic at the medium access control （MAC） layer in the IEEE 802.16 standards. Among the mechanisms, contention based bandwidth request scheme can be used to indicate bandwidth demands to the base station for the non-real-time polling and best-effort services. These two services are used for most applications with unknown traffic characteristics. Due to the diverse QoS requirements of those applications, service differentiation （SD） is anticipated over the contention based bandwidth request scheme. In this paper we investigate the SD with the bandwidth request scheme by means of assigning different channel access parameters and bandwidth allocation priorities at different packets arrival probability. The effectiveness of the differentiation schemes is evaluated by simulations. It is observed that the initial backoff window can be efficient in SD, and if combined with the bandwidth allocation priority, the SD performances will be better.展开更多
文摘We theoretically analyze the organizing filament of small amplitude scroll waves in general excitable media by perturbation method and explicitly give the expressions of coefficients in Keener theory. In particular for the excitable media with equal diffusion, we obtain a close system for the motion of the filament. With an example of the Oregonator model, our results are in good agreement with those simulated by Winfree.
文摘The paper introduces the characteristics of a new type washing machine (mini washing machine) and analyzes the global problems solved by mini washing machines from the perspective of meeting different consumers'needs. On the basis of current performance specifications of IEC 60456, it explains how to improve the performance test method of mini washing machine in details, and points out the direction of standards research and test improvement. Meanwhile, the author briefs about other new type washing machines and the developmental trend of washing machines.
基金Supported by the National Natural Science Foundation of China under Grant No. 10975184
文摘In the framework of the heavy quark effective theory, the leading order Isgur-Wise functions relevant to semileptonie decays of the orbitally P-wave excited Bs meson states Bs＊, including the newly found narrow Bs1 （5830） andBs2（5840） states, into the （Ds1（2536）, Ds2（2573）） doublet are calculated from QCD sum rules. With these universal form factors, the decay rates and branching ratios are also estimated.
基金Supported by Natural Science Foundation Project of CQ CSTC under Grant No.2008BB0298by Natural Science Foundation of China under Grant Nos.10805082 and 11075225by the Fundamental Research Funds for the Central Universities under Grant No.CDJZR101000616
文摘The B-meson decay constant fB is an important component for studying the B-meson decays, which can be studied through QCD sum rules. We make a detailed discussion on f B from two sum rules up to next-to- leading order, i.e. sum rules I and II, which are derived from the conventional correlator and the correlator with chiral currents respectively. It is found that these two sum rules are consistent with each other. The sum rules H involves less non-perturbative condensates as that of sum rules I, and in principle, it can be more accurate if we know the dimensionfour gluon condensate well. It is found that fB decreases with the increment of mb, and to compare with the Belle experimental data on fB, both sum rules I and H prefer smaller pole b-quark mass, mb= 4.68 ± 0.07 GeV. By varying all the input parameters within their reasonable regions and by adding all the uncertainties in quadrature, we obtain fB=172-25^＋23 MeV for sum rules I and fB =214-34^26 MeV for sum rules П.
文摘Following a cross-sectional design, the present study investigated the acquisition of English requests by Chinese learners at three proficiency levels with open production questionnaires. It was found that L2 linguistic proficiency, L1 pragmatic transfer and classroom instruction have interactive effect on learners' L2 pragmatic development. A range of acquisitional features were found-learners' employment of direct request strategies decreased, the employment of conventionally indirect strategies increased and the number and variety of internal modifiers increased with the increase of proficiency. It was also found that L1 pragmatic transfer worked on various aspects of learners' requestive behavior and that inadequate or inappropriate input from the teaching materials and the EFL classroom arrangements might constrain their pragmatic development.
基金supported by the US Army Ofce of Research(Grant No.W911NF11-1-0364)the National Science Foundation of USA(Grant No.DMS-1005441)National Natural Science Foundation of China(Grant No.91230105)
文摘The paper presents a new fast integral equation solver for Maxwell＇s equations in 3-D layered media. First, the spectral domain dyadic Green＇s function is derived, and the 0-th and the 1-st order Hankel transforms or Sommerfeld-type integrals are used to recover all components of the dyadic Green＇s function in real space. The Hankel transforms are performed with the adaptive generalized Gaussian quadrature points and window functions to minimize the computational cost. Subsequently, a fast integral equation solver with O（N2zNxNy log（NzNy）） in layered media is developed by rewriting the layered media integral operator in terms of Hankel transforms and using the new fast multipole method for the n-th order Bessel function in 2-D. Computational cost and parallel efficiency of the new algorithm are presented.
基金the National Basic Research Program(973) of China (No. 2005C13321804)
文摘Various flexible mechanisms related to quality of service （QoS） provisioning have been specified for uplink traffic at the medium access control （MAC） layer in the IEEE 802.16 standards. Among the mechanisms, contention based bandwidth request scheme can be used to indicate bandwidth demands to the base station for the non-real-time polling and best-effort services. These two services are used for most applications with unknown traffic characteristics. Due to the diverse QoS requirements of those applications, service differentiation （SD） is anticipated over the contention based bandwidth request scheme. In this paper we investigate the SD with the bandwidth request scheme by means of assigning different channel access parameters and bandwidth allocation priorities at different packets arrival probability. The effectiveness of the differentiation schemes is evaluated by simulations. It is observed that the initial backoff window can be efficient in SD, and if combined with the bandwidth allocation priority, the SD performances will be better.
