Advanced Materials Research Vols. 726-731

Abstract: Ethanol pulping is a kind of solvent pulping technology. The utilization of lignin in waste liquor can reduce pollution and increase high value of product. The lignin in the waste liquor could be isolated by adding water in the system after standing for several hours and purified by enzymatic and acidic hydrolysis two-step procedure. Results showed that the optimized purification conditions are as follows, enzyme dosage is 0.004g/g (to oven dry lignin), enzymatic buffer pH is 5, enzymatic hydrolysis temperature is 30°C, and hydrochloric acid concentration of acid hydrolysis is 0.055mol/L. The lignin purity is 91.61%, and the yield is 81.89%.

Abstract: The paper discusses the spatial distribution of the road traffic noise using the monitoring data of the road traffic noise in Xuchang city. The spatial distribution of the road traffic noise in urban district of Xuchang city has notable characteristic. The results indicate that the current situation of traffic noise pollution is a severe threat for people's life in Xuchang city. And the traffic noise in business district is higher than the value of residential district and industrial district. The traffic noise in Weidu district is higher than the value in other district.

Abstract: Taking the 3-in-1 after treatment device of a diesel engine produced by FAW Jiefang Automotive CO., Ltd as an example, the acoustic finite element method of software Virtual.Lab is used to analysis the transmission loss and insertion loss, then analysis the acoustic performance of its substructure. The results show that the heat exchange tube has little effect on acoustic performance of the entire device; The silencer module of multi-cavity structure can significantly improve the performance in low-frequency. Perforated plate and perforated pipe have effect on improving medium-high frequency, and changes of structural parameter affect its acoustic characteristics; The comparison between direct simulation results of insertion loss and the experimental results has a good effect.

Abstract: The paper is utilizes the double difference method of to relocate the north and south earthquake belt's Ludian earthquake sequence to obtained the Ludian earthquake sequence's detailed earthquake parameters. And at the same time we have established an whole set of perfect method in data processing and result analysising. Have the ability of useing'the north and south earthquake belt earthquake to strengthen the monitor's real time data to accuratly relocate the medium intensity earthquake sequenc of the north and south belt. Thus,we could produce the more accurate earthquake parameter, and short provides a more conclusive evidence into the warning area division and earthquake forecast.

Abstract: Particle damping is a method for improving damping of a dynamic system by means of energy dissipation due to repeated collisions of a free mass on the base structure. In this paper, the theoretical investigations carried out to study and characterize damping with respect to the level of base excitation. The mathematical model consists of a particle damping system. The response obtained from the mathematical model for the drum brake and paticle damper. Here the effect of particle damping is studied for low frequency and high amplitude excitation. Optimum parameters are determined for design of impact damper based on the mathematical model. A good match is obtained by theoretical results.

Abstract: In this paper, we describe a method for classifying the workplaces as regards the noise risk. This method provides an univocal classification of work area and allows to correctly implement the control measures in accordance with a suitable priority scale. Finally, this method can be easily adjusted to respect various national standards.

Abstract: To discover the vibrating compaction mechanism and optimize the working parameters, the test on vibration compaction is designed and the compressive stress and the compaction energy on the loess during the vibrating compaction are studied. The distribution of the compressive stress is analyzed from the stress signals in time domain. And the distribution, absorption and transfer law of the compaction energy in the loess are analyzed from frequency spectrum of the compressive stress signals. The results show that the value of the compressive stress on every layer in the loess increases with the increasing of the rolling times and it decreases with the increasing of the depth. The compressive stress at the top layer increases most quickly, and arrives at its maximum value for the ninth rolling time. The middle and bottom layers both arrive at their maximum values for the eleventh rolling time. The natural frequency of the test loess is 30Hz. At this vibratory frequency, the compaction energy working at the loess is more adequate than that of the other frequencies. And the compaction effect is the best. The vibratory energy absorbed by every layer decreases with the increasing of the soil density. The top layer can get more energy than the middle and the bottom layers. It arrives at the density state firstly. The analysis is in accordance with the experimental results of the compactness.

Abstract: The purpose of this paper is to analyze the electromechanical properties of piezoelectric harvesting unit from road vibration. A new kind of piezoelectric harvesting unit, which consists of 8 pieces of PZT vibrators and sizes of 280*280*20mm, is purposed. The vibrators are connected and covered by epoxy resin. With the software of ANSYS, open circuit voltage and stress distribution of the unit under the function of vehicle tire pressure are analyzed. The results show that the maximums of open circuit voltage and stress distribution are proportional with the tire pressure. When the tire pressure is 1.0MPa, open circuit voltage and the maximum stress generated by the piezoelectric unit are 950.8V and 9.8MPa, respectively. It means that application of the piezoelectric harvesting unit can couple with the asphalt pavement very well and harvest higher electricity from road vibration on larger area.

Abstract: A novel imminent earthquake analysis method is proposed. Firstly, BHZ data are acquired from seismic networks, then, structure parameters of part of the earth are identified based on SSI (stochastic subspace identification); finally, imminent earthquake is analyzed based on the results of system identification. It is prevented from entering earth interior or using artificial seismic explosion. Location of epicenter and process of earthquake on imminent earthquake can be analyzed based on characteristics of main vibration frequency, change trend of model shape and damping by using SSI to analyze field data on earthquake event.

Abstract: Advances in Computational Aeroacoustics (CAA) depend critically on the availability of accurate, nondispersive, least dissipative computation algorithm as well as high quality numerical boundary treatments. This paper focuses on the Perfectly Matched Layer (PML) for external boundaries in CAA. To achieve low dissipation and dispersion errors, Dispersion-Relation-Preserving (DRP) Schemes are used for spatial discretization of the acoustic equations. The classical fourth-order Runge-Kutta time scheme is applied to the acoustic equations for time discretization. Four cases are given to illustrate the 2D PML equations for the linearized/nonlinear Euler equations in Cartesian coordinates and Cylindrical coordinates. The results show that the PML is effective as absorbing boundary condition. Those are basis for PML in actual computations of acoustic problems.