查询词典 base 2

The opened magnetic circuit is composed as tow NdFeB permanent magnets and a top plate without U-yoke. After take analyzed deeply for the opened magnet circuit with FEMM (Finite Element Method Magnetics) we find out the field distributing that is separated into three sections . One is the main area what we called as positive field section. Beside the main field there are tow areas that are called the inverted field sections. Loudspeaker arise a very serious distortion when the voice coil moving into inverted field areas. The direction of induced current in the coil part of entered inverted field area is same with the current driving into loudspeaker so that total currents increas largely and heat increase rapidly. With more coils moving into inverted area the voice coil will take on negative inductance properties. It is the main reason that voice coil is burned by heating with increasing current due to arise negative inductance. So opened magnetic circuit is not suitable for the woofers in which the voice coil have wider displacement range. When using this kind magnetic circuit design, the voice coil moving range should be less than the range of positive field to avoid loudspeaker arise serious distortion and heating. Even though voice coil moving range is in the positive area, loudspeaker will still arise more distortion because the field distribution is very cliffy at tow sides of the positive area and full range of magnetic field distribution is not parallel that will arise distortion. Base on above reasons, opened magnetic circuit is not an ideal magnetic circuit for low-frequency loudspeakers. But it can be used in mid-range or high-frequency productions.

开式磁路是由2片钕铁硼磁铁和主导磁板和导磁垫片组成，我们在实践过程中发现这种磁路结构不适合于低频扬声器的使用，我们通过使用FEMM（Finite Element Method Magnetics）软件包对该磁路进行了分析，该磁路的磁场范围被分成3个区域，其中在主导磁板附近形成一个正向磁场，在正向磁场的两边存在反向的磁场，音圈在工作时有很大一部分进入了反向磁场中，在反向磁场内线圈的感应电流方向与驱动电流方向相同，使得音圈呈现出负感抗特性，由于音圈的负感抗特性引起电流的增加导致音圈发热甚至烧毁，因此在扬声器中使用开式磁路时，音圈的运动范围应控制在正向磁场范围之内，否则音圈运动到反向磁场区域时将会产生很大的失真和发热，即使在设计时已经将音圈的运动范围控制在正向磁场范围之内，由于正向磁场的2个边缘磁场强度衰减太快，同时开式磁路中磁场的分布不是平行的，而是自由发散的分布，这样肯定会导致扬声器的非线性失真，因此我们得到的结论是：开式磁路并不是一个理想的磁路，它不适合于低频扬声器的使用，但它还可以应用于中高频扬声器。

Female inflorescence terminal or axillary on dwarf shoots, racemose; flowers paired; bracts leaflike, complanate, overlapping, 2- or 3-lobed at base.

在矮小上的雌花序顶生或腋生嫩枝，总状；成对的花苞片叶状，扁平，重叠，2或3裂在基部。

Leaves simple, alternate, sometimes fascicled on short branchlets, conduplicate when young; petiole usually with 2 nectaries or sometimes nectaries at base of leaf blade margin; leaf blade margin often serrate.

有托叶。单叶，交替，有时由短开出的簇生小枝，幼时；叶柄通常具2蜜腺或有时蜜腺在基部的叶片边缘；叶片边缘通常有锯齿。

Leaves simple, alternate or fascicled on short branchlets, conduplicate when young; petiole usually with 2 apical nectaries or nectaries sometimes at base of leaf blade margin; leaf blade margin singly or doubly serrate, rarely serrulate.

单叶，交替或在上，对折幼时；有时的叶柄通常具2顶端的蜜腺或蜜腺叶片边缘的在基部；单个的叶片边缘或重锯齿，很少有细锯齿。

Leaves conferted on the upper part of stem and branches; petiole 5-7 mm long; leaf blade obovate- or elliptic-lanceolate, 3.5-8 cm long and 1.5-2.5 cm wide, apex acute, base obtuse or subrounded, adaxial surface covered with brown minute stiff hairs, abaxial surface pink or dark purple, glabrous.

叶聚生於茎和枝的上部；叶片纸质，倒卵状或椭圆状披针形，长3.5-8厘米，宽1.5-2.5厘米，先端急尖，基部钝或近圆形，上面被褐色小刚毛，下面淡红色或暗紫色，无毛；叶柄长5-7毫米。

Stamens 5 or rarely 4; filaments short; anthers mostly sagittate, free or connivent into a cone adherent to pistil head, dehiscing longitudinally, base rounded, cordate, sagittate, or prolonged into an empty spur; pollen granular; disc ringlike or cup-shaped, 2-5-lobed, or absent.

雄蕊5或很少4；花丝短花药多数箭头形，离生或靠合花柱成圆锥形，纵裂，基部圆形、心形、箭头形，或延长为空的距；花粉颗粒状；杯状的花盘环形或，浅裂的2-5，或无。

Filaments free, very short; anthers free or mostly connivent into a sheath around ovary, 2 anterior ones with spurlike or wartlike and nectariferous appendages at base, these extending into anterior spur, connectives produced apically into conspicuous, membranous appendages.

花丝离生，非常短；花药离生或多数在子房周围靠合成为鞘，前面2枚基部具距状或瘤状和分泌蜜汁的附属物，这些延伸进入前面的距中，药隔顶部生明显、膜质附属物。

Petals absent or, if present, 2–3 mm, shorter than stamens; leaf base cordate or broadly cuneate.

花瓣无的或，如果有，2-3毫米，短于雄蕊；叶基部心形或宽楔形。

Leaves odd-pinnate, 15-21 cm; leaflets 3-5; leaflet blades oblong to oblong-obovate,(6-)10-12(-13)× 2.5-4(-5) cm, leathery, glabrous, lateral veins 7 or 8(-10) pairs, conspicuous, base acute, margin crenately serrate, apex acuminate.

奇数羽状复叶，15-21厘米；小叶3-5；小叶叶片长圆形到长圆状倒卵形，(6-)10-12(-13)* 2.5-4(-5)厘米，革质，无毛，侧脉7或8(-10)对，明显，锐尖的基部，边缘有锯齿，先端渐尖。

Cymes 1-4-flowered; leaf blade base cordate to broadly cuneate, margin crenulate; staminodes 2

聚伞花序1-4开花；叶片基部心形到宽楔形，边缘具细圆齿；退化雄蕊2 11 Petrocosmea barbata 髯毛石蝴蝶

Do you know, i need you to come back

你知道吗，我需要你回来

Yang yinshu、Wang xiangsheng、Li decang,The first discovery of haemaphysalis conicinna.

1〕 杨银书，王祥生，李德昌。安徽省首次发现嗜群血蜱。