In the post-genomic era, one of the challenges and a source of competition is the development of high-throughput, large-scale and low-cost eukaryotic cDNA cloning and expression systems. The baculovirus expression system is the most popular one and plays an important role in the high-level expression of eukaryotic proteins. In the present study, a convenient, rapid and highly efficient method for the construction of recombinant BmNPV (Bombyx mori nuclear polyhedrosis virus)-Bacmid vector (BmBacmid) for low-cost protein expression in silkworm (B. mori) larvae was established by using the MAGIC (mating-assisted genetically integrated cloning) strategy. By simply mixing the donor bacteria strain containing the constructed donor vector pCTdual harbouring foreign genes and the recipient strain containing modified BmBacmid, 99.8% positive recombinant BmNPV-Bacmids were obtained. Reporter genes egfp (enhanced green fluorescent protein gene) and DsRed (Discosoma sp. red fluorescent protein gene) and target gene man (beta-mannanase gene) encoding beta-mannanase were expressed in the silkworm larvae of B. mori at high level by injection of recombinant BmBacmid DNA directly with the standard calcium phosphate transfection procedure. The possibility of constructing a high-quality baculovirus cDNA library by transferring an ordinal plasmid cDNA library into the recipient BmBacmid in Escherichia coli was explored.
To test different car’s noise in a semi-anechoic room with different engine’s speed, measure and analysis engine noise’s characteristics and the dash panel’s sound insulation quantity. The conclusion is that:the engine noise gets bigger 10 dB(A) when engine speeds up every 1000 r/min; engine noise’s frequency mainly distributed in 1600 ~ 4000 Hz; peak part concentrates in the range 100 ~ 400 Hz; engine noise has no direct relation to engine’s displacement; cab noise frequency mainly concentrated in the range 250 ~ 630 Hz and the peaks exist in the intermediate and low frequency part, the high frequency part attenuates obviously which show the car’s dash panel has a good noise insulation and absorption effect in the high frequency part but not too ideal at the intermediate and low frequency especially in the range 250 ~ 630 Hz. These results have high practical value for the design of the automotive to decline noise and vibration.
Automobile door closure’s sound quality is good or bad directly affecting customers evaluate to vehicle performance. Foreign automobile manufacturers spend lots of manpower, material and financial resources to improve and research door closure quality [1-3]. Door closure is important embodiment of product quality and performance, which is related to design method, manufacture process, sealing material, etc. This paper selects three different models and series cars, measuring their exterior door closure and anglicizing objective parameters of sound quality. It conclusion that front door frequency concentrated in 200-2000 Hz; back door’s concentrated in 315-2500Hz;The significant frequency band of characteristic loudness contains linear and A sound pressure level significant frequency band, etc.The result can provide ideas for automobile vibration and noise reduction.
With the development of the car industry, the pace of the urban construction is accelerating as well. Cars have gradually entered the ordinary family. As the car noise has a big effect on the health of the passengers, as well as on the surroundings, one of the car industry key duties is the car noise reduction. By researching the materials applied to car, this article describe that PU material could reduce the impact of the engine noise on the cab efficiently; Polypropylene needle-spun felt could reduce the noise passed by chassis; PET material's sound absorption is poor in mid bass, however in high frequency it's sound absorption is good; sound absorbing sponge can reduce the low and high frequency noise; The combine sponge can reduce the noise from the tire and transmission system ; Cotton material could absorb the high frequency noise.
This paper researched on four different types cars, analyzing interior noise at the same speed under different points, the same point different speeds and the same car different speed different points, it is concluded that family car interior noise distribution law; Through analysis noise spectrum curve which can get the main frequency band, that may provide theoretical basis for automotive noise reduction. In addition, this paper gets that medium low-frequency noise(0-2Brk) are the biggest to composition car’s characteristics loudness from research on characteristic loudness curve, and with speed continuously improve characteristic loudness growth is very significant.
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