Polaron transport in a long phonon waves approximation

One seeks to understand directly the smooth electron distribution functions long ago observed in semiconductors by Haynes and Westphal, and found to satisfy the Einstein relation for diffusion.A zero-order approximation to the distribution function analogous to Chandrashekhar's solution of the Brownian motion problem is established. This is done on the basis of the expression of Feynman et al., for the density matrix of the electron with phonon coordinates eliminated. Justification of the underlying approximation of expansion in long phonon waves, as well as a discussion of the relation of the scheme to the Boltzmann or rate equation approach, is given.     

An improved approximation to the microstrip line capacitance

A new empirical formula is presented for the normalised capacitance of microstrip lines. The formula uses a single equation to represent the microstrip line capacitance over the useful range of the aspect ratio. The maximum error of the new formula is contained within 0.8 percent and the relative root-mean-square error is contained within 0.55 percent. The new formula can be easily implemented in computeraided design and analysis as well as in hand calculations using pocket calculators.     

Generalized bethe approximation in lattice models of long polymers

The phase transition behavior of a self-avoiding linear polymer model on a three-dimensional lattice is studied. An approximate procedure is proposed which gives the exact divergence of the specific heat aboveT _c for the two-dimensional case. In three dimensions our method predicts a finite value forC atT _c and demonstrates clearly what neglected contributions to the partition function lead to such a behavior of the model.     

Feed optimization for the slotted line antenna for high-densityplasma production

Investigations on the optimization of feed structures for exciting the slotted line antenna for high-density plasma production are presented. Each feed structure used (except the direct feed) excites a preferred component of the wave electric/magnetic field. It is seen that the efficacy of plasma production using the different feeds depends directly on the relative importance of the field components (which the feeds excite) for the flow wave mode of the antenna. The optimal feed is shown to be a dipole antenna, oriented so as to excite the radial component of the electric field within the slotted line structure. The plasma characterization results as a function of the input microwave power and the magnetic field in the antenna region are also presented and discussed. The ability of the antenna to maintain high-density plasmas well away from electron-cyclotron resonance is demonstrated     

Is the markovian approximation to the GME correct in the long time domain?

Three elementary analytically solvable examples are devised in order to illustrate a generally ignored warning that the Markovian approximation to the finite-coupling Generalized Master Equations in the convolution form may appreciably distort the solution even in the long-time domain. This means that even for the short-time memory, the memory effects may be in general hardly ignored on the long-time scale.     

Differences Between Flexible and Rigid Endoscopy in Assessing the Posterior Glottic Chink

Objective

To determine whether different modalities of laryngeal examination produce differences in the assessment of the posterior glottic chink (PGC), and whether the prevalence of PGC differs by gender.

Introduction

The PGC has been described as a triangular laryngeal space between the posterior laryngeal wall and the vocal processes during glottic closure found commonly in human females, but less often in males. The purpose of this study was not only to identify whether there are gender differences in prevalence of posterior glottic but also to determine whether there is a difference in detection of this configuration dependent on the modality of laryngeal imaging, specifically flexible nasopharyngolaryngoscopy (FNPL) versus rigid laryngoscopy (RL).

Methods

A review of 104 consecutive initial laryngeal examinations was performed. All patients underwent both flexible laryngoscopy (FL) and RL performed under stroboscopic light. Patients with immobile vocal folds, masses causing glottic gaps, atrophy, or severe muscle tension dysphonia causing an inability to fully visualize the entire length of the vocal fold were excluded. In the remaining patients, the posterior glottic configuration showing a posterior chink in relation to the vocal process was graded on a 0–4 scale (called the Posterior Glottic Closure Score [PGCS]); 0 was used to indicate a closed glottis and 4 the most open configuration without creating a complete glottic gap. PGCSs for males were compared with those of females, and the PGCSs obtained by flexible nasopharyngolaryngoscopy was compared with RL.

Results

Fifty-two patients were included in the study. Twenty-four of the patients were male, and 28 were female. The average age of the patients was 48.4 years (SD ± 17.35), and the range was 15–81 years. On RL, eight males had a PGCS 1–4, that is, evidence of PGC, and 23 females had a PGCS 1–4. On flexible nasopharyngolaryngoscopy, only four males had a PGCS 1–4 and 24 females had PGCS 1–4. Twenty-two females had a PGC detected by both modalities, and the PGCS was significantly higher using RL (2.73 ± 0.70 vs 2.14 ± 0.834) than FL. For the four males in which PGC was detected by both modalities, there was no statistical significance when comparing the PGCS between RL and FL (1.75 ± 0.96 vs 1.75 ± 0.5, P < 0.05). When comparing only males and females who had a PGC (PGCS 1–4), females had a higher PGCS (2.65 ± 0.78) than males (1.75 ± 0.71, P < 0.05) on RL, indicating a more open posterior glottis in females. On flexible examination, there was no difference detected in the average PGCS, 2.08 ± 0.83 for females and males 1.75 ± 0.50. PGCs were more common in younger (age 43 years) than older (age 54–56 years) subjects for both laryngoscopic modalities.

Conclusion

From this pilot study, we determined that there is a difference in male and female PGC prevalence and size. PGC is more common in females than males. Prevalence (or the detection rate) is about the same with RL and FL in females, but higher with RL than FL in males. The average score of the glottic opening, when present, was statistically significantly different between RL and FL in females but not in males. Furthermore, females had a larger PGCS on both modalities when compared with males, although this difference was only found to be statistically significant on RL; and complete glottic closure was more common in older than in younger subjects.     

EAST离子回旋加热天线传输线结构设计

阐述了EAST离子回旋加热天线传输线的结构设计。用有限元的方法对EAST离子回旋加热天线传输线内导体结构进行了分析,获得了内导体的受力情况。根据内导体的受力情况适当加大波纹管厚度和设计内导体支撑,通过ANSYS分析优化确定了波纹管的厚度和内导体布置的位置。此外,还计算了传输线的热损耗、热变形、电压驻波系数和最大功率容量,计算结果进一步验证了传输线结构的可行性。     

An improved separability approximation for line radiative transport in nonhomogeneous media

A simple modification to the constant half-width approximation of Wilson and Greif, which is an extension of the well-known Curtis-Godson method to the treatment of temperature variations along the integration path, is introduced which permits a more accurate evaluation of line radiative transport in non- homogeneous gases. To demonstrate the method's accuracy, comparisons are made with Wilson and Greif and numerical frequency integrated results for the line equivalent width and radiative flux in a planar slab with prescribed Planck function and line half-width spatial variations are chosen to represent typical shock layer conditions. It is found that the modified procedure reduces the inaccuracies inherent in Wilson and Greif's approximation by factors ranging from 5 to 10, while retaining the latter method's ease of application.     

L波段磁绝缘线振荡器一体化辐射天线

根据小型化的要求,提出了可以用于小型化L波段磁绝缘线振荡器的一体化辐射天线的模型,即介质+插板移相型模式变换器,该模型可以有效缩短模式变换器的物理长度,并基于该模型研究了一体化辐射天线的方向图、增益、物理长度等特性,初步优化设计了一体化辐射天线,为结构紧凑的小型化磁绝缘线振荡器的研究提供了方便。     

切比雪夫渐变线TEM喇叭天线数值模拟

设计了一种采用切比雪夫渐变线的TEM喇叭天线,分析了其工作原理,采用数值模拟的方法研究了其阻抗特性、传输特性与辐射特性,并在不同的馈入脉冲下与常用的线性渐变TEM喇叭天线进行了性能对比。结果表明: 切比雪夫渐变线TEM喇叭天线具有低反射、高带宽和高辐射场强的优点,其性能要明显优于线性渐变TEM喇叭天线,且馈入脉冲越宽,性能越明显。分析了最大反射系数对切比雪夫渐变线TEM喇叭天线辐射性能的影响,馈入脉冲越窄时,宜选择反射系数越大的辐射天线。     

Design of a small-sized expanded coaxial line antenna at L-band

为了减小常规L波段高功率微波测量接收天线的结构尺寸及增益,设计了一种基于轴向缝隙馈电的小型化同轴扩张型天线.通过理论分析和数值模拟,选择了较优的结构尺寸,得到天线的增益及方向图特性:在1.3～1.6 GHz范围内,增益从-2.0 dBi变化至0.8 dBi；天线最大辐射方向在物理结构轴向.基于矢量网络分析仪E8362B的天线特性测量结果与数值计算结果基本一致:工作频率从1 3～1 6GHz变化时,增益从-2.3 dBi变化至1.2 dBi；E面方向图主瓣宽度大于 60°,轴向轴比大于35dB,结果表明设计的天线能够满足L波段高功率微波渊量天线低增益小型化要求.     

L波段磁绝缘线振荡器一体化辐射天线

 根据小型化的要求,提出了可以用于小型化L波段磁绝缘线振荡器的一体化辐射天线的模型,即介质+插板移相型模式变换器,该模型可以有效缩短模式变换器的物理长度,并基于该模型研究了一体化辐射天线的方向图、增益、物理长度等特性,初步优化设计了一体化辐射天线,为结构紧凑的小型化磁绝缘线振荡器的研究提供了方便。     

切比雪夫渐变线TEM喇叭天线数值模拟

设计了一种采用切比雪夫渐变线的TEM喇叭天线,分析了其工作原理,采用数值模拟的方法研究了其阻抗特性、传输特性与辐射特性,并在不同的馈入脉冲下与常用的线性渐变TEM喇叭天线进行了性能对比。结果表明:切比雪夫渐变线TEM喇叭天线具有低反射、高带宽和高辐射场强的优点,其性能要明显优于线性渐变TEM喇叭天线,且馈入脉冲越宽,性能越明显。分析了最大反射系数对切比雪夫渐变线TEM喇叭天线辐射性能的影响,馈入脉冲越窄时,宜选择反射系数越大的辐射天线。     

L波段小型化同轴扩张型天线设计

为了减小常规L波段高功率微波测量接收天线的结构尺寸及增益,设计了一种基于轴向缝隙馈电的小型化同轴扩张型天线。通过理论分析和数值模拟,选择了较优的结构尺寸,得到天线的增益及方向图特性：在1.3~1.6 GHz范围内,增益从-2.0 dBi变化至0.8 dBi;天线最大辐射方向在物理结构轴向。基于矢量网络分析仪E8362B的天线特性测量结果与数值计算结果基本一致：工作频率从1.3~1.6 GHz变化时,增益从-2.3 dBi变化至1.2 dBi;E面方向图主瓣宽度大于60,轴向轴比大于35 dB,结果表明设计的天线能够满足L波段高功率微波测量天线低增益小型化要求。     

长磁绝缘传输线动态特性

基于粒子模拟研究了长磁绝缘传输线的电压电流关系、自限制流状态和损失前沿传播速度的变化规律,验证了稳态流假设下建立的不同磁绝缘传输线模型在描述长磁绝缘传输线工作状态时的精确程度。结果表明:Mendel模型在描述长磁绝缘传输线电压电流关系时较精确;Rescaled模型计算长磁绝缘传输线自限制流状态下的阳极电流较精确;损失前沿在长磁绝缘传输线中的传播速度沿着能量传输方向是动态变化的,其速度的大小与输入电压上升速率相关。     

长磁绝缘传输线动态特性

基于粒子模拟研究了长磁绝缘传输线的电压电流关系、自限制流状态和损失前沿传播速度的变化规律, 验证了稳态流假设下建立的不同磁绝缘传输线模型在描述长磁绝缘传输线工作状态时的精确程度。结果表明：Mendel模型在描述长磁绝缘传输线电压电流关系时较精确; Rescaled模型计算长磁绝缘传输线自限制流状态下的阳极电流较精确; 损失前沿在长磁绝缘传输线中的传播速度沿着能量传输方向是动态变化的, 其速度的大小与输入电压上升速率相关。     

Acoustic characteristics of a multichannel long line of the flexural type

The properties of an acoustic object represented by a multichannel long line of the flexural type are considered. Analytical formulas are obtained for the basic acoustic characteristics of a multichannel long line with an arbitrary number of flexurally oscillating single lines constituting it: the input impedance, the resonance frequencies, and the reflection and transmission coefficients are determined for an insulating multichannel long line, including the case of a cascade connection. Numerical calculations are performed and the plots are presented for the frequency dependences of the reflection and transmission coefficients for various parameters of the constituting lines. It is demonstrated that the acoustic characteristics of insulating multichannel long lines have certain advantages in comparison with the characteristics of similar objects based on single lines.