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An experimentally validated finite element method is used to model the sound level in rooms at low frequencies. It is demonstrated that the dimensions of rectangular rooms strongly influence the sound pressure level difference. Additional factors were investigated which are not normally considered in the frequency range where diffuse sound field conditions can be assumed. Three effects were investigated: room damping due to wall vibrations, furniture, the effect of small deviations from simple rectangular shapes. It is confirmed by field measurements that the vibrations of masonry walls and floors introduce less damping than surfaces of lightweight construction. Assigning to the FE model a damping equivalent to a surface absorption of 0.02 reproduces the effect of walls of heavyweight construction. Damping equivalent to a surface absorption of 0.15 reproduces the effects of plastered timber-frame walls, floors and ceilings. The work was briefly extended to a room pair built with heavyweight and lightweight material of construction. The modification of the shape of the room frequency response highlights well the effect of material of construction. In-situ and laboratory measurements show that furniture has little effect on steady-state room response below 100 Hz. Modelling a wall recess smaller than 0.5 m improved the agreement between prediction and measurements but the assumption of a simple rectangular room remains appropriate. 相似文献
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用灰色非线性建模理论,建立了家具销售方面的两个预测模型,为家具企业的生产、销售,提供了一个科学而又容易操作的决策方法。 相似文献
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Emissions from surfaces (from furniture, wall paintings or floor coverings for instance) significantly influence indoor air
quality and therefore the wellbeing or even the health of the occupants. Together with metabolites from mold they are responsible
for the well-known “sick building syndrome”. Therefore, it is in the interest of the manufacturer as well as of the occupants
to have a fast and accurate method for the detection of substances relevant to this syndrome in order to be able to monitor
and control product quality and indoor air quality. The use of small and easy-to-transport ion mobility spectrometers that
use UV light as the ionization source enables rapid in situ detection of such substances with high selectivity and sensitivity
(detection limits in the lower ppb range). If a multicapillary column is used for preseparation as well, the selectivity is
increased and the unwanted influence of humidity on the spectra can be eliminated, thus enabling the use of the instruments
under normal ambient conditions. Furthermore, the use of air as carrier gas avoids the need for other sources of high-purity
gas. An emission cell with a homogeneous and constant air flow over the surface to be investigated was developed in order
to ensure reproducible results. Investigations of emissions from wooden surfaces with and without additional contamination
as well as from complex mixtures are presented. The results demonstrate that relevant emissions can be identified and quantified
with high sensitivity and selectivity in under five minutes. Therefore, the method is useful for indoor air quality monitoring,
especially when miniaturized instruments are applied.
Figure 相似文献
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中国家具工业发展的现状与展望 总被引:19,自引:1,他引:18
吴智慧 《南京林业大学学报(自然科学版)》2002,26(5):87-92
改革开放20多年以来,中国的家具工业得到迅速发展,形成了一定的产业规律。但随着中国进入WTO,中国家具市场的竞争将会更加激烈,家具行业将面临新的挑战。目前,中国家具的设计水平和出口规模还不够理想。笔对中国家具工业的生产现状、存在问题、市场前景和发展趋势进行了概括分析,提出了一些建议,以期引起国内家具业同仁的重视。 相似文献
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本文介绍了AutoCAD在家具实体建模和工艺图纸设计上的一些应用技巧。通过运用外部参照和块提取的方式实现家具设计精确制图以及图纸的自动更新,从而最大程度地提高家具设计的制图效率。 相似文献
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家具制造业信息化的构想及关键技术 总被引:2,自引:0,他引:2
阐述了中国家具制造业信息化建设研究的现状、内涵和发展趋势,提出了实现中国家具制造业信息化的构想,并就其关键技术进行了初步的探讨。在“以信息化带动工业化,以工业化促进信息化”、“用高新技术和先进适用技术改造提升传统产业”的基础上,提出了加强中国家具制造业信息化建设研究的建议。 相似文献
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对GB18584-2001中有关家具标准的探讨 总被引:1,自引:0,他引:1
对国家标准GB18584—2001中关于家具甲醛释放量的取样方法和测定方法进行了探讨。分析了《标准》中干燥器法测定家具甲醛释放量存在的一些缺陷,建议进一步完善取样和测定方法。讨论了“大型舱法”测定家具甲醛释放量的优越性,提出由“大型舱法”逐步取代“干燥器法”,加速与国际接轨,以提高我国木质品的国际竞争力。 相似文献