电缆与连接器（四）

（上接2008年第3期100页）2．6．8为何接地环路对EMC设计没有影响接地环路有时也称作噪声回路,因为在EMC设计有缺陷的音响系统中接地环路会引起嗡嗡的噪声。通常的做法是采用单点接地和电缆屏蔽层的单端搭接,从而避免形成接地环路,但是接地环路问题其实是由不恰当的产品设计所引起的。     

外部干扰的抑制（二）

6．1．4控制屏蔽机箱的放电 屏蔽是一种抑制ESD的有效方式,可以对ESD进行适当的控制,使得ESD不会影响产品内部电路的正常工作。第4部分内容对屏蔽技术进行了讨论,我们所要做的就是让机箱在非常高的频率具有理想的屏蔽效能。     

Nitrous oxide emissions from two sites in Southern England during winter 1981/1982

Nitrous oxide fluxes from soil surfaces were measured during winter 1981/82 on two fallow sites, a loamy sand and a clay loam, that had been watered to field capacity and fertilised at the rate of 200 kg N ha^?1 on the 5 October 1981. Highest fluxes were obtained in the sampling period immediately after fertiliser application. They were in the range 3.5–20 g N₂O? N ha^?1 day^?1 on the loamy sand, and declined rapidly from a peak of almost 165 g N₂O? N ha^?1 day^?1 on the day following fertiliser application on the clay loam. The temperature during this period was in the range 6.5 to 14°C. As soil temperature declined during the sampling periods in December (?2 to 3°C) and February (4.5 to 6.5°C) and nitrate was leached in the subsoil, N₂O evolution became very low (<1 g N₂O? N ha^?1 day^?1). Rainfall over the whole sampling period from early October to mid-February was 282 mm. On both sites there was a very high degree of variability within the sites at any sampling time.     

便携设备的电源管理技术展望

2005年对以电池驱动的便携设备的电源管理解决方案来说，将是充满机遇的一年。这些设备的制造商不断在寻求各种可能的方式，以把更多的功能合并到一个已经很紧凑的外壳中，这说明他们将不断需要具有高度集成、最小占位面积、最高运行效率的集成电路解决方案，以延长电池的使用时间。     

Crystallization-Directed Anisotropic Electroactuation in Selectively Solvated Olefinic Thermoplastic Elastomers: A Thermal and (Electro)Mechanical Property Study

Dielectric elastomers (DEs), a class of soft electroactive polymers that change size upon exposure to an external electric field, constitute an increasingly important class of stimuli-responsive polymers due primarily to their large actuation strains, facile and low-cost fabrication, scalability, and mechanical robustness. Unless purposefully constrained, most DEs exhibit isotropic actuation wherein size changes are the same in all actuation directions. Previous studies of DEs containing oriented, stiff fibers have demonstrated, however, that anisotropic actuation along a designated direction is more electromechanically efficient since this design eliminates energy expended in nonessential directions. To identify an alternative, supramolecular-level route to anisotropic electroactuation, we investigate the thermal and mechanical properties of novel thermoplastic elastomer gels composed of a selectively solvated olefinic block copolymer that not only microphase-separates but also crystallizes upon cooling from the solution state. While these materials possess remarkable mechanical attributes (e.g., giant strains in excess of 4000%), their ability to be strain-conditioned enables huge anisotropic actuation levels, measured to be greater than 30 from the ratio of orthogonal actuation strains. This work establishes that crystallization-induced anisotropic actuation can be achieved with these DEs.     

Data hiding approach for efficient image indexing

A data hiding approach to embed the indexing keys inside the JPEG compressed images for their retrieval, inspired from the spirit of digital watermarking, is proposed. At the stage of database population, the existing approach is to compress all images by standard JPEG in order to save their storage space, but this ignores the compression of their indexing keys under the notion that the size of each indexing key is negligible. When a large image database is established, however, this part of storage space becomes non-trivial. By hiding the indexing keys inside the JPEG compressed codes, significant advantages are gained in that the indexing keys can be compressed naturally by JPEG without any additional cost. Experiments on hiding an indexing key of 256 bytes illustrate that: no noticeable distortion is introduced in comparison with non-watermarked images; and their storage space is reduced into the region of 7-27% of their original size.     

Organic Photovoltaic Cells Based On Solvent‐Annealed,Textured Titanyl Phthalocyanine/C60 Heterojunctions

Organic photovoltaic cells (OPV) with good near‐IR photoactivity are created from highly textured titanyl phthalocyanine (TiOPc)/C₆₀ heterojunctions. Vacuum deposited TiOPc thin films are converted to the near‐IR absorbing “Phase II” polymorph using post‐deposition solvent annealing. The Phase I → Phase II transition broadens the absorbance spectrum of the Pc film producing absorptivities (α ≈ 10⁵ cm^?1) from 600–900 nm, along with substantial texturing of the Pc layer. Atomic force microscopy and field‐emission scanning electron microscopy of the solvent annealed films show that the surface roughness of the Pc layers is increased by a factor of greater than 2× as a result of the phase transformation. Current–voltage (J–V) responses for white light illumination of ITO (100 nm)/TiOPc (20 nm)/C₆₀ (40 nm)/BCP (10 nm)/Al (100 nm) OPVs show a near doubling of the short‐circuit photocurrent (J_SC), with only a small decrease in open‐circuit photopotential (V_OC), and a concomitant increase in power conversion efficiency. Incident photon current efficiency (IPCE) plots confirmed the enhanced near‐IR OPV activity, with maximum IPCE values of ca. 30% for devices using Phase II‐only TiOPc films. UV‐photoelectron spectroscopy (UPS) of TiOPc/C₆₀ heterojunctions, for both Phase I and Phase II TiOPc films, suggest that the Phase II polymorph has nearly the same HOMO energy as seen in the Phase I polymorph, and similar frontier orbital energy offsets, E_HOMO^Pc–E_LUMO^C60, leading to comparable open‐circuit photovoltages. These studies suggest new strategies for the formation of higher efficiency OPVs using processing conditions which lead to enhance near‐IR absorptivities, and extensive texturing of crystalline donor or acceptor films.     

电缆与连接器(十)

（上接2009年第3期79页） 3．5．11浪涌抑制器件的组合应用 有时候靠一个浪涌抑制器件（SPD）很难满足所有的需求,为了优化SPD的浪涌抑制性能,同时减小生产成本,可以将多个SPD组合使用。图3AT是一个能够承受高功率的气体放电管（GDT）和一个箝位动作迅速的金属氧化物压敏电阻（MOV）的组合应用情况。GDT被触发后可以吸收大部分浪涌能量,当产生过压时,串联电感可以使GDT触发,而MOV可以保护负载不受GDT触发电压的影响。     

汽车电子系统要求低静态电流

如今的汽车电子系统越来越复杂。同时，汽车环境对任何电子产品来说都是很大的挑战，因为汽车电子系统要求运行电压很宽，并且有很大的瞬态电压和温度变化。另外，性能要求也越来越高，需要多个供应电压以满足系统的不同要求。典型的     

Machine learning in control of functional electrical stimulationsystems for locomotion

Two machine learning techniques were evaluated for automatic design of a rule-based control of functional electrical stimulation (FES) for locomotion of spinal cord injured humans. The task was to learn the invariant characteristics of the relationship between sensory information and the FES-control signal by using off-line supervised training. Sensory signals were recorded using pressure sensors installed in the insoles of a subject's shoes and goniometers attached across the joints of the affected leg. The FES-control consisted of pulses corresponding to time intervals when the subject pressed on the manual push-button to deliver the stimulation during FES-assisted ambulation. The machine learning techniques used were the adaptive logic network (ALN) and the inductive learning algorithm (IL). Results to date suggest that, given the same training data, the IL learned faster than the ALN while both performed the test rapidly. The generalization was estimated by measuring the test errors and it was better with an ALN, especially if past points were used to reflect the time dimension. Both techniques were able to predict future stimulation events. An advantage of the ALN over the IL was that ALN's can be retrained with new data without losing previously collected knowledge. The advantages of the IL over the ALN were that the IL produces small, explicit, comprehensible trees and that the relative importance of each sensory contribution can be quantified