V型双振子螺杆式直线压电作动器研究

提出一种V型双振子螺杆式直线压电作动器,该作动器由定子圆筒、精密螺母、螺杆及2个弹性体振子构成。利用2个弹性体振子弯曲振动产生的对称模态和反对称模态,激励圆筒端面质点作椭圆轨迹运动,通过螺母和螺杆间的摩擦耦合驱动螺杆作轴向直线运动。利用有限元分析,设计制作了试验样机,并对其主要输出性能进行了实验测试。在电压峰-峰值为300V条件下,样机稳定工作频率为9.7kHz,无负载最大转速为57.7r/min,最大输出力为2.3N。     

压电式合成射流致动器的设计与实验研究

采用两种不同的压电陶瓷片制作了压电振子,基于压电振子设计了不同喷口形式和压电振子布局形式的合成射流致动器.实验中利用热线风速仪对致动器喷口中心的速度进行了测量.结果表明,所设计的合成射流致动器喷口峰值速度达22.55 m/s,致动器典型布局时方形缝倾斜角对喷口峰值速度影响较大,90°法向射流比45°倾斜射流能获得更大的喷口动能,射流法向喷出时致动器典型布局比侧面布局能获得更多的喷口动能.     

滚磨工艺对压电陶瓷振子性能的影响

介绍行星式滚磨工艺在压电陶瓷频率元件制造过程的应用,对压电陶瓷振子的频率具有调整作用。在给出不同滚磨试验条件下得到不同的滚磨结果。结果分析得出滚磨工艺影响压电陶瓷振子性能的关键因素,确定了滚磨条件。压电陶瓷频率元件产品的主要指标——振子频率控制精度要求越来越高,通过行星式滚磨机的滚磨加工,实现频率精细调整的目的。     

一种弯曲模态直线超声电机的研究

提出了一种改进的弯曲模态直线超声电机。该电机利用兰杰文振子两相正交的3阶弯曲振动,在其驱动足处形成椭圆运动,推动动子运动。采用超声变幅放大了定子驱动足处的振幅。利用有限元方法用来设计定子的结构尺寸。实验表明,在电压峰-峰值200V下,该电机最大空载速度为113mm/s,最大输出力为10N。     

A Controllable Synthesis of Rich Nitrogen‐Doped Ordered Mesoporous Carbon for CO2 Capture and Supercapacitors

A controllable one‐pot method to synthesize N‐doped ordered mesoporous carbons (NMC) with a high N content by using dicyandiamide as a nitrogen source via an evaporation‐induced self‐assembly process is reported. In this synthesis, resol molecules can bridge the Pluronic F127 template and dicyandiamide via hydrogen bonding and electrostatic interactions. During thermosetting at 100 °C for formation of rigid phenolic resin and subsequent pyrolysis at 600 °C for carbonization, dicyandiamide provides closed N species while resol can form a stable framework, thus ensuring the successful synthesis of ordered N‐doped mesoporous carbon. The obtained N‐doped ordered mesoporous carbons possess tunable mesostructures (p6m and Im m symmetry) and pore size (3.1–17.6 nm), high surface area (494–586 m² g^?1), and high N content (up to 13.1 wt%). Ascribed to the unique feature of large surface area and high N contents, NMC materials show high CO₂ capture of 2.8–3.2 mmol g^?1 at 298 K and 1.0 bar, and exhibit good performance as the supercapacitor electrode with specific capacitances of 262 F g^?1 (in 1 M H₂SO₄) and 227 F g^?1 (in 6 M KOH) at a current density of 0.2 A g^?1.     

A Synergetic Effect of Molecular Weight and Fluorine in All‐Polymer Solar Cells with Enhanced Performance

A synergetic effect of molecular weight (M_n) and fluorine (F) on the performance of all‐polymer solar cells (all‐PSCs) is comprehensively investigated by tuning the M_n of the acceptor polymer poly((N,N′‐bis(2‐octyldodecyl)‐naphthalene‐1,4,5,8‐bis(dicarboximide)‐2,6‐diyl)‐alt‐5,5′‐(2,2′‐bithiophene)) (P(NDI2OD‐T2)) and the F content of donor polymer poly(2,3‐bis‐(3‐octyloxyphenyl)quinoxaline‐5,8‐dyl‐alt‐thiophene‐2,5‐diyl). Both M_n and F variations strongly influence the charge transport properties and morphology of the blend films, which have a significant impact on the photovoltaic performance of all‐PSCs. In particular, the effectiveness of high M_n in increasing power conversion efficiency (PCE) can be greatly improved by the devices based on optimum F content, reaching a PCE of 7.31% from the best all‐PSC combination. These findings enable us to further understand the working principles of all‐PSCs with a view on achieving even higher power conversion efficiency in the future.     

Specific features in the energy spectrum of the narrow-gap semiconductor bicrystals Bi1 ? x Sb x (0.06 ≤ x ≤ 0.20)

The results of studying the effect of an interface of crystallites on the energy spectrum of electrons in narrow-gap Bi_{1 − x} Sb _x semiconductor bicrystals are reported (0.06 ≤ x ≤ 0.20). The structure of the reflection spectra for bicrystals with the inclined crystallite boundary and corresponding single crystals is analyzed. A number of features are revealed from comparison of the optical spectra of single crystals and bicrystals with the same parameters in wavelength ranges as high as 6 eV; these features are caused by the effect of the crystallites’ interface on the energy spectrum of charge carriers. Original Russian Text ? A.E. Georgitsé, V.I. Ivanov-Omskiĭ, F.M. Muntyanu, M.I. Karaman, I.T. Postolaki, 2007, published in Fizika i Tekhnika Poluprovodnikov, 2007, Vol. 41, No. 10, pp. 1195–1197.     

压电振子弹性支撑的数值与实验研究

针对压电振动输送装置中压电振子的固定方式,提出一种实用的新支撑方式即橡胶弹性支撑。利用有限元软件分析了橡胶弹性支撑对两种压电振子振动模态及其固有频率的影响,并进行了实验测试。数值分析与实验结果基本吻合。研究结果表明,橡胶片厚度大于一定值时,压电振子的弯曲固有频率与无支撑的同阶固有频率的偏差很小。压电振子橡胶弹性支撑位置对振子的固有频率影响很小,支撑位置可不作压电振动输送装置的动态设计变量。     

铜 压电陶瓷复合型悬臂压电振子发电性能分析

利用压电振子采集环境振动能量为低功耗电子产品供能是近年来研究的热点,而压电振子的振动发电能力与其几何形状有关。该文针对悬臂梁压电振子,利用ANSYS软件仿真分析了其自由端尺寸的改变对压电振子的输出电压及固有频率的影响。结果表明,在相同条件下,存在一定的自由端尺寸使压电振子采集环境中低频振动的能量最大。     

基于压电换能器的液滴驱动模型研究

基于智能车辆视觉传感器表面除水的需求,该文提出了一种利用压电换能器激励兰姆波以驱动液滴运动的装置,并建立了压电振子和弹性体平板的二维有限元模型。首先运用COMSOL Multiphysics仿真软件对自由边界条件下的压电振子进行频率分析,得到前4阶特征模态,第2阶模态具有最大的结构相对位移,其特征频率为谐振频率;然后对压电振子所激励的兰姆波在平板中的传播特性进行了分析。结果表明,兰姆波在板中出现明显的频散特性,并通过改变压电振子间隔激励A₀模态占主导的兰姆波,以提高液滴驱动效果。通过实验验证了兰姆波驱动液滴模型的可行性。     

Influence of random phase errors on polarization characteristics of antenna array

Polarization properties of the field of linear antenna arrays with random phase errors in the excitation currents of orthogonal vibrators and a system of biorthogonal radiators are studied. The influence of errors’ correlation on the degree of polarization and ellipticity of antenna with broadside radiation of waves with circular polarization is analyzed.     

Enhanced photo-degradation methyl orange by N–F co-doped BiVO4 synthesized by sol–gel method

Using ammonium fluoride (NH₄F) as the source of nitrogen (N) and fluorine (F), N–F co-doped bismuth vanadate (BiVO₄) visible-light-driven photocatalysts have been synthesized via a sol–gel method. The resulting materials were characterized by a series of techniques: X-ray photoelectron spectroscopy, X-ray diffractometry, scanning electron microscopy, Brunauer–Emmett–Teller (BET) surface analysis, and UV–vis diffuse reflectance spectroscopy. Compared with BiVO₄, the N–F co-doped BiVO₄ photocatalysts exhibited much higher photocatalytic activity for methyl orange (MO) degradation under visible light irradiation. It was revealed that N and F atoms were doped into the lattice of BiVO₄. The doped N atoms existed as O–N or V–O–N bonding, and the F atoms replaced some O atoms to form the O–V–F structure, which can be attributed to the appearance of more active species V⁴⁺ and oxygen vacancies. The doped N and F atoms resulted in a red shift in the absorption edge. However, the N and F doping only slightly changed the morphologies and BET special surface areas of the samples. The photocatalytic activity of BiVO₄ significantly depended on the N–F doping content and the calcination temperature. The maximum activity was observed for the catalyst obtained with calcination at 500 °C, a molar ratio of NH₄F to Bi(NO₃)₃ was 6%.     

Nonfullerene Polymer Solar Cells based on a Perylene Monoimide Acceptor with a High Open‐Circuit Voltage of 1.3 V

Nonfullerene polymer solar cells (PSCs) are fabricated with a perylene monoimide‐based n‐type wide‐bandgap organic semiconductor PMI‐F‐PMI as an acceptor and a bithienyl‐benzodithiophene‐based wide‐bandgap copolymer PTZ1 as a donor. The PSCs based on PTZ1:PMI‐F‐PMI (2:1, w/w) with the treatment of a mixed solvent additive of 0.5% N ‐methyl pyrrolidone and 0.5% diphenyl ether demonstrate a very high open‐circuit voltage (V _oc) of 1.3 V with a higher power conversion efficiency (PCE) of 6%. The high V _oc of the PSCs is a result of the high‐lying lowest unoccupied molecular orbital (LUMO) of ?3.42 eV of the PMI‐F‐PMI acceptor and the low‐lying highest occupied molecular orbital (HOMO) of ?5.31 eV of the polymer donor. Very interestingly, the exciton dissociation efficiency in the active layer is quite high, even though the LUMO and HOMO energy differences between the donor and acceptor materials are as small as ≈0.08 and 0.19 eV, respectively. The PCE of 6% is the highest for the PSCs with a V _oc as high as 1.3 V. The results indicate that the active layer based on PTZ1/PMI‐F‐PMI can be used as the front layer in tandem PSCs for achieving high V _oc over 2 V.     

粘结层对不同形状叠层压电振子发电性能影响

针对悬臂梁叠层压电振子,利用ANSYS软件仿真分析了其自由端尺寸的改变对于压电振子的输出电压及其固有频率的影响,并得到了叠层压电振子在结合面上的切应力的变化关系。研究表明,在相同条件下,随着自由端尺寸的减小,压电振子的开路电压、基频均有不同程度的增加,但其结合面上的切应力却有较大程度的增幅(最大为74%),这种变化易使叠层结构发生抗剪强度不足的破坏。     

How conflict resolution emerged within the commercial sector

A CPR News special: Two recent speeches discussing Alternatives' publisher's impact on ADR, and what the future may look like. First, the remarks of 2006 CPR Corporate Leadership Award dinner keynoter Joseph A. Greenaway Jr., a Newark, N.J., U.S. District Court Judge, focus on where ADR works and where its promise lies. CPR Senior Vice President F. Peter Phillips, in addressing the First African ADR Congress in Nigeria in November, provides a history of commercial conflict resolution.     

Synthesis of antenna arrays radiation patterns on random geometry cylinders

Synthesis algorithm for gain-phase radiation patterns formed by linear electrical vibrators antenna arrays located on random geometry cylinders is discussed. The results of numerical calculations are presented.     

Proceeding to yes: A federal judge looks at ADR's future

A CPR News special: Two recent speeches discussing Alternatives' publisher's impact on ADR, and what the future may look like. First, the remarks of 2006 CPR Corporate Leadership Award dinner keynoter Joseph A. Greenaway Jr., a Newark, N.J., U.S. District Court Judge, focus on where ADR works and where its promise lies. CPR Senior Vice President F. Peter Phillips, in addressing the First African ADR Congress in Nigeria in November, provides a history of commercial conflict resolution.     

In Situ Formation of Copper‐Based Hosts Embedded within 3D N‐Doped Hierarchically Porous Carbon Networks for Ultralong Cycle Lithium–Sulfur Batteries

Lithium–sulfur (Li–S) batteries are promising energy storage systems due to their large theoretical energy density of 2600 Wh kg^?1 and cost effectiveness. However, the severe shuttle effect of soluble lithium polysulfide intermediates (LiPSs) and sluggish redox kinetics during the cycling process cause low sulfur utilization, rapid capacity fading, and a low coulombic efficiency. Here, a 3D copper, nitrogen co‐doped hierarchically porous graphitic carbon network developed through a freeze‐drying method (denoted as 3D Cu@NC‐F) is prepared, and it possesses strong chemical absorption and electrocatalytic conversion activity for LiPSs as highly efficient sulfur host materials in Li–S batteries. The porous carbon network consisting of 2D cross‐linked ultrathin carbon nanosheets provides void space to accommodate volumetric expansion upon lithiation, while the Cu, N‐doping effect plays a critical role for the confinement of polysulfides through chemical bonding. In addition, after sulfuration of Cu@NC‐F network, the in situ grown copper sulfide (Cu_xS) embedded within Cu_xS@NC/S‐F composite catalyzes LiPSs conversion during reversible cycling, resulting in low polarization and fast redox reaction kinetics. At a current density of 0.1 C, the Cu_xS@NC/S‐F composites' electrode exhibits an initial capacity of 1432 mAh g^?1 and maintains 1169 mAh g^?1 after 120 cycles, with a coulombic efficiency of nearly 100%.     

Manifestation of clustering of Ge atoms in the spectra of electron spin resonance of Si1 ? xGex alloys (0 < x < 0.057)

The electron spin resonance (ESR) at phosphorus dopants in the P-doped Si_1−x Ge _x alloys (0 < x < 0.057) with the concentration of phosphorus in the range 10¹⁵–10¹⁶ cm⁻³ is studied at temperatures from 3 to 30 K. The ESR spectra of the alloys (x > 0) are compared to the ESR spectra of similar silicon samples (x = 0). It is found that, from the smallest Ge content x = 0.008, the ESR spectra contain two additional lines. It is assumed that these lines are due to phosphorus dopants located in clusters with higher Ge content. It is found that an increase in the Ge content in the alloys up to x = 0.024 yields only an increase in the concentration of such clusters. At x ≥ 0.024, the Ge content increases with x both inside and outside the clusters. Original Russian Text ? A.I. Veinger, A.G. Zabrodskiĭ, T.V. Tisnek, S.I. Goloshchapov, N.V. Abrosimov, 2007, published in Fizika i Tekhnika Poluprovodnikov, 2007, Vol. 41, No. 6, pp. 687–693.     

双弯曲振子型压电式管内移动机构的试验研究

提出了一种利用双弯曲振动驱动的压电式管内移动机构，该机构由两个带有凸起的矩形板振子和弹性支撑元件组成，通过振子的凸起端部的椭圆运动形成驱动能力。本文作者利用分割设计法对振子进行了初步设计，然后通过有限元法进行结构分析，最后试制了试验样机。初步的试验结果表明，此种结构可以实现管内行走，其移动速度最高为9.98mm/s。