The object of this study was to understand precisely the acoustic vibration characteristics of the paulownia for musical instrument. Two paulownia chosen were Paulownia australis and Paulownia elongata, and compared w...
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The object of this study was to understand precisely the acoustic vibration characteristics of the paulownia for musical instrument. Two paulownia chosen were Paulownia australis and Paulownia elongata, and compared with the picea (Far East Picea koraiensis and Picea jezoensis). The acoustic vibration parameters of four trees were respectively measured and comparative analyzed based on the vibration method of FFT by tapping, and then the acoustic vibration characteristics of paulownia were comprehensive evaluated. The results demonstrated that the density had nearly no effect on the loss angle tangents of the paulownia and the picea, and the loss angle tangents of four trees were similar. At the same time, the values of the specific Young's modulus and acoustic impedance of the paulownia were smaller than that of the picea, but the paulownia's acoustic radiation constants and the loudness were larger and higher than the picea's. It indicated that, according to all acoustic vibration parameters evaluated, the paulownia had the same good acoustic vibration characteristics with the picea, and the paulownia was suitable for wood for musical instrument.
People pay great attention on the indoor air pollution of public building now. Indoor environment of six university buildings (library, laboratory, classroom, dormitory, computer room and office) were measured with ga...
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People pay great attention on the indoor air pollution of public building now. Indoor environment of six university buildings (library, laboratory, classroom, dormitory, computer room and office) were measured with gas detector from March to May. The concentrations of total volatile organic compounds (VOCs) of these sites meet the "Indoor air quality standards "requirements of China. The average VOCs concentration of student dorm in eight hours is the highest. The VOCs level is higher in morning, and decreased rapidly in the afternoon. It is expected the existence of computer and printer is also contributed to indoor VOCs when the I/O values of teacher office and computer lab are higher. The ventilation, season variation and outdoor air quality have a direct impact on indoor VOCs level.
Information technologies of “Wood science” international resource sharing platform, question-answering system and micro-blog were discussed combining teaching characteristics of “Wood science” with social developm...
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Information technologies of “Wood science” international resource sharing platform, question-answering system and micro-blog were discussed combining teaching characteristics of “Wood science” with social development needs. Teaching methods of “Wood science” are expanded in terms of promoting international academic exchanges, long-rang guidance for practices, tracking latest news real-time and so on. Meanwhile, these are new approaches to enhance teaching quality and culture high-quality personnel.
Data acquisition card and microphone were used to build wood non-destructive testing system based on virtual machines in this paper. Signals of nondestructive vibration experiments was collected and processed by th...
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Data acquisition card and microphone were used to build wood non-destructive testing system based on virtual machines in this paper. Signals of nondestructive vibration experiments was collected and processed by the graphic program of labview6.1. The dynamic elastic modulus was acquired by the calculation frequency of vibration signals. The static elastic modulus was calculated by the mechanical testing machine. The results showed that the correlation coefficient of dynamic elastic modulus which was acquired by virtual machine method and FFT is 0.958. The correlation coefficient of elastic modulus which was acquired by virtual machine method and the mechanical testing machine is *** methods showed a highly degree of linear correlation and the virtual instrument can be applied to calculate the dynamic elastic modulus of wood. The non-destructive testing of wood based on virtual instrument technology has advantages of accurate, simple operation and low cost.
novel biomass composite inspired from wood porous structure was manufactured by impregnating vinyl monomer into wood cellular structure under vacuum conditions, and initiating the monomer for in situ polymerization th...
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novel biomass composite inspired from wood porous structure was manufactured by impregnating vinyl monomer into wood cellular structure under vacuum conditions, and initiating the monomer for in situ polymerization through a thermal treatment. The vacuum condition was studied, and the mechanical properties of the composite were also tested. SEM observation shows that polymer generated in the wood porous structure, and strongly interacted with wood matrix;and the polymer content increased with vacuum value increasing. FTIR indicates that polymer grafted onto wood matrix, resulting chemical complex between them. The rate of monomer loading increased with increasing vacuum value and time, accordance with rate of polymer loading. The compression strength and modulus of elasticity linearly increased with the increasing rate of polymer loading. Results indicate that the novel biomass composite possesses good mechanical properties capable of applying in the fields of construction, traffic and so forth.
Glucose production from pretreated larch by cellulose enzymatic hydrolysis with cellulase was investigated and compared with no pretreatment, as a reference. The larch was pretreated with microwave, sulfuric acid hydr...
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Glucose production from pretreated larch by cellulose enzymatic hydrolysis with cellulase was investigated and compared with no pretreatment, as a reference. The larch was pretreated with microwave, sulfuric acid hydrolysis and dilute sodium hydroxide solution hydrolysis respectively. The cellulose material was also submitted to a pretreatment with dilute sodium hydroxide solution hydrolysis followed by microwave and with dilute sulfuric acid solution hydrolysis followed by microwave separately. The enzymatic hydrolysis experiments were carried out at 50°C, 50 g/l dry matter (DM) solid substrate concentration and 15 filter paper unit (IU)/g DM of a commercial cellulase. Fermentable sugar were able to be produced from all the pretreated larches with an overall yield of 10-30% of the maximum theoretical yield, based on the glucan available in the solid and liquid substrate. The larch pretreated with acid and microwave had the best yield as 30% followed by the larch pretreated with dilute sodium hydroxide solution with an overall yield of 18% with 15 IU/g DM of cellulase. Glucose was the main product with enzymatic hydrolysis yield ratio 11.74%in the sulfuric acid pretreated larch, while with enzymatic hydrolysis yield ratio 23.44%in the dilute sodium hydroxide solution pretreated larch under enzymatic hydrolysis conditions. These advantages, along with its negative price, make this solid a valuable raw material for L-lactic acid production.
Zn:Mn:Fe:LiNbO3 crystals with various Li/Nb ratios were grown by the Czochralski method. The optical scattering resistance ability of crystals were measured, the optical scattering resistance of Zn:Mn:Fe:LiNbO3 crysta...
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Zn:Mn:Fe:LiNbO3 crystals with various Li/Nb ratios were grown by the Czochralski method. The optical scattering resistance ability of crystals were measured, the optical scattering resistance of Zn:Mn:Fe:LiNbO3 crystal of Li/Nb=1.38 are over one order of magnitude higher than that of Zn:Mn:Fe:LiNbO3 crystal. The holographic storage properties measured by using two wave coupling optical path dual wavelength (blue-red light) technique. The dual wavelength storage properties superior to dual color storage properties. The optical stimulation carriers of dual wavelength [blue light (476 nm)-red light] are hole. Mn ion is shallow energy, Fe ion is deep energy level. Using Zn:Mn:Fe:LiNbO3 crystal of Li/Nb=0.94 and 1.05 go on dual wavelength nonvolatile holographic storage experiment, its nonvolatile diffraction efficiency and response speed are higher than that of dual color nonvolatile holographic storage.
This design put forward a kind of computer color matching system design scheme based on fuzzy neural network and realizes its software design by C language programming. This system took the color differences between k...
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This design put forward a kind of computer color matching system design scheme based on fuzzy neural network and realizes its software design by C language programming. This system took the color differences between known colors and objective colors as its input and formula concentration as its output.
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