穿孔板

The result of experiment illustrated that three layer micro-perforated panel after optimization can indeed obtain satisfactory absorption curve. The result is accordant with calculation, which can be used on project.

同时选用了结构参数相近的微穿孔板进行实验，实验结果表明，优化设计的三层微穿孔板结构确实能够获得饱满的吸声系数曲线，与理论计算结果吻合，为工程应用提供了依据。

Based on the acoustic absorption theory of microperforated panel and by the means of the theoretical analysis and emulation, the paper focuses on the acoustic characteristic including acoustic impedance, frequency and acoustic absorption coefficient of microperrforated panel working in the combustion chamber which has high temperature and great temperature gradient.

摘要根据微穿孔板吸声理论，采用理论分析和仿真的方法，着重讨论微穿孔板在温度梯度下的声阻抗、共振频率和吸声系数等声学特性，分析其受温度影响变化的机理。

In this paper, based on Maa's theory, the theory of micro perforated panel absorber is summarized, a comparison between the calculated result and the testing result for intermediate and lower frequency standing wave tubes is made.

在微穿孔板消声理论的基础上，根据气动马达消声器的实际需要设计了一种微穿孔板消声器，并通过实验对这种消声器的消声特性和流阻进行了研究。

The wood structures of Lauraceae were characterized by most diffuse porous; most pores solitary, less multiple and cluster pores; simple and scalariform perforation with few bars; most solitary pore; alternate intervessel pitting; most of rays multiseriate, less uniseriate; all of rays heterogeneous, mostly heterogeneous Ⅲ and Ⅱ type rays; most of axial parenchyma paratracheal type, less banded or marginal type; oil cell and mucilage cell in axial parenchyma cell or ray cell; mostly fiber tracheid and libriform fiber, less septate fiber.

结果表明：除檫木外，其它木材的管孔分布均为散孔材，具较高的单孔率；导管分子穿孔板兼有单穿孔和梯状穿孔2种或者仅具有单穿孔；导管间纹孔式为互列；导管－射线间纹孔式类型丰富，主要为刻痕状和大圆状。木射线有单列和多列射线2种类型，单列射线稀少、短，多列射线数量多；射线组织主要为异形Ⅲ和异形Ⅱ；轴向薄壁组织以傍管状为主，少数有带状或轮界状。油细胞和粘液细胞普遍存在于射线薄壁细胞或轴向薄壁细胞中。木纤维由韧性纤维和纤维管胞组成，部分树种具分隔纤维。

The tracheary elements in secondary xylems of Actaea asiatica root and rhizomes were observered with a scanning electron microscope and found to contain abundant types, which mainly included tracheids, tracheid-like vessels, fibriform vessels, and typical vessels. Of these types, the tracheids, tracheid-like vessels, fibriform vessels were first found. Scalariform perforation plates, reticulate perforation plates, mixed perforation plates and simple perforation plates were observed in the typical vessels and the reticulate perforation plates ,mixed perforation plates were first founded the lateral-wall perforation plates, multiple end walls and pit membrane vestige were also observed in the tracheary elements.

利用扫描电子显微镜对毛茛科类叶升麻根和根状茎次生木质部中的管状分子进行观察，发现其管状分子类型丰富，主要有：管胞、管胞状导管、纤维导管和典型的导管分子，其中管胞、管胞状导管和纤维导管为在该类群中首次报道；在导管分子中，存在着梯状穿孔板、网状穿孔板、混合型穿孔板和单穿孔板，其中网状穿孔板和混合型穿孔板为在该类群中的首次报道；对其导管分子上的侧壁穿孔板、多穿孔板和纹孔膜残余也进行了描述。

Emblica have many different forms and most of them have tails and their perforation plates divide into two types:(1)there is one simple perforation plate at each end of the vessel elements and (2) there is one simple perforation plate at one end of the vessel elements and two simple perforation plate at the other end;(3)a few vessel elements have special inclusions;(4)the intervascular pits are alternate pits;(5)the pits between the vessels and rays are mixed pits ,pits with transverse gashes and scalariform pits.

结果发现，余甘子次生木质部导管分子中存在着许多不同的样式，导管分子大多数具尾；其穿孔板存在着两种类型：(1)两端均为1个单穿孔板；(2)一端为1个单穿孔板；另一端为2个单穿孔板；(3)极少数的导管分子具有特殊的内含物；(4)管间纹孔式为互列纹孔式；(5)导管射线间纹孔式为混合型纹孔与横列刻痕状纹孔以及梯状穿孔。

MPPs are typically made of a thin metal or plastic panel. However, thin limp panels are generall not suitable as an interiornish of room walls because they do not have sucient strength, which prevent spractica lapplication of MPPs as an interiornish of roomwalls.

典型的微穿孔板为孔径与板厚均小于1mm的金属或塑料板，这些极薄的板材因其强度低，通常不适用于民用，也因此使微穿孔板这一良好的吸声共振结构的应用范围受到局限。

Results There were 3 types of vessel elements,scalariform vessel,reticulated vessel and pitted vessel,the perforation plates were simple perforation plate.

结果茵陈蒿具有梯纹、网纹和孔纹3种类型的导管，穿孔板类型为单穿孔。

The Lithostegia Ching was considered as a member of Peranemaceae for a long time, according to the research,we found that it has the typical scalariform perforation plates,no associated or crossed phenomena,and some region have intact plate,no dimorphic phenomena,no weblike or threadlike remnants,these suggest that The Lithostegia Ching is in a primal evolutional position.

与传统观点不同，我们认为穿孔板仅存在于端壁的管状分子为导管分子，而端壁和侧壁形态、结构相似，有或无穿孔板的管状分子为管胞，蕨类植物中的管状分子主要为管胞。

The experiment shows that the catalyst portion has very obvious effect on the exhaust purity box ,purity ratio and oil consumption ; In the course of the opening ratio has an less obvious impact on experiment ,the three items ;the least impact on the three items is the carrers diameter.

试验结果表明，催化剂用量对净化消声器的消声量、净化率及油耗三项指标均有显著的影响；穿孔板的穿孔率在试验范围内，对净化消声器的三项指标影响较为显著；载体直径对净化消声器的三项指标的影响次之。

Singer Leona Lewis and former Led Zeppelin guitarist Jimmy Page emerged as the bus transformed into a grass-covered carnival float, and the pair combined for a rendition of "Whole Lotta Love".

歌手leona刘易斯和前率领的飞艇的吉他手吉米页出现巴士转化为基层所涵盖的嘉年华花车，和一双合并为一移交&整个lotta爱&。

This is Kate, and that's Erin.

这是凯特，那个是爱朗。