Advanced Materials Research Vols. 518-523

Abstract: In order to the search for more effective noise control measures and a more rational urban planning from the angle of economy, environment, so that we can create a healthier living environment, this paper does some preliminary investigation in the aspect of soundscape. This paper introduces soundscape science research status and research results domesticity and abroad, and on this basis, makes a subjective evaluation of voice of the landscape in Jiangxi Normal University, by combinating Psychoacoustic Evaluation Method. This paper record various of sounds existing in the campus, analyses properties of each sound, and does a large-scale survey about the popularity of these sounds. The paper chooses ten most popular voices using mark-giving method, and analyses the ten 10 kinds of sound by SD methods. The following are the results: (1) the ten most popular voices in the campus: voice of birds, sounds of musical instruments, voice of singing、reading、and teachers’ lectures, and the sound of radio(music)、 broadcasting (in English and other programs)、computer sound (music, film sound) and wind，50% of which are natural sounds, 30% human voice, and 20% noise of machines. From above, we can see that the sounds from nature are more acceptable. (2) By using semantic differential method (SD Act), the paper does a subjective evaluation on the ten popular kinds of voices. Marks are different form different analysing angle, that is, different people like different voices on different degrees. (3) When people work and learn, it is good to create some comfortable sounds in the surroundings and control or eliminate noisy sounds. Creating a comfortable sound surrounding environment is a good way to improve people’s working and learning effeciency.

Abstract: Present, railway stations are rather common in every cities, towns and villages. In this study, the field study method of soundscape in railway stations has been developed, aiming at finding out the relationships between users’ evaluation of sound environment and other factors in such spaces, as well as their similarities and differences with other urban public spaces. Based on sociological theory, questionnaires and simpling methods have been designed. Using these methods, soundscape surveys and measurement have been carried out in 4 railway stations in capital cities, China, considering both staffs and passengers. By analysing the data, some initial results are given in this paper for further research.

Abstract: At present MEMS inertial devices is unable to satisfy the precision request of the inertial posture measurement system. This paper has designed a gyro dynamic data generator for simulation according to the gyro signal characteristics.The signal produced by the generator is specified as the gyro data and the optimal estimator for data fusion is designed by using the Kaman filter algorithm.The multi-segment data is analyzed and identified while the optimal data is estimated .The results show no matter how the correlation of the data is, the fusion data has attenuation of 10dB in noise, with its signal-to-noise ratio being enhanced more than 2 times at least.

Abstract: It has been demonstrated in previous studies that the evaluation of soundscape was influenced by some social characteristics of persons. In this study, more than 600 questionnaire surveys were undertaken at waiting halls of 4 railway stations in capital cities of China, to determine how the users’ social characteristics influence their evaluation of soundscape. These results show that the relationships between evaluation of acoustic and gender or age are not significant (p>0.1), but female passengers were more careful on evaluation of sounscape. The acoustic comfort was influenced by income and education, with correlation coefficient is -0.35 and -0.32 (p<0.01), respectively, while subjective loudness was influenced by education and occupation, with correlation coefficient is 0.35 and -0.51 (p<0.01), respectively. This study can enhance the understanding of aural environment in railway stations and also can help architects using social characteristics design the better spaces for evaluation of acoustics in the waiting halls of railway stations.

Abstract: Nowadays, the users’ evaluation of sound environment in the railway stations is focused by all kinds of experts. Comparing with other spaces, the waiting hall is usually recognized as the most important space in the railway station. In this study, more than 600 questionnaire survey has been undertaken at 4 waiting halls of railway stations in capital cities of China, to determine how the sound sources and sound pressure level influence acoustic evaluation. More details of acoustic evaluation in the waiting hall of Harbin railway station are given in this paper. Based on the analysis of the investigation results, it has been found that in the waiting halls of railway stations, PA system is generally noticeable and ‘masking’ other less preferred sound sources, while sound from mobiles is preferred by passengers. The relationship between the measured LAeq and the subjective loudness, acoustic comfort evaluation as well as subjective loudness and acoustic comfort are all of a linear shape, and the acoustic comfort is general better when LAeq is lower than 75dBA.

Abstract: This paper proposes an intelligent method for diagnosing structural faults of rotating machinery using ant colony optimization (ACO) and non-dimensional symptom parameters (NSPs) in order to detect faults and distinguish fault types at an early stage. NSPs are defined for reflecting the features of vibration signals measured in each state. Detection index (DI) using statistical theory has also been defined to evaluate the applicability of the NSPs. The DI can be used to indicate the fitness of an NSP for ACO. Lastly, the state identification for the condition diagnosis of rotating machinery is converted to a clustering problem of the values of NSPs calculated from vibration signals in different states of the machine. Ant colony optimization (ACO) is also introduced for this purpose. Practical examples of fault diagnosis for rotating machinery are provided to verify the effectiveness of the proposed method. The verification results show that the structural faults often occurring in a rotation machinery, such as a unbalance, a misalignment and a looseness states are effectively identified by the proposed method.

Abstract: Retracted paper: This paper introduces a low-order system frequency response model (SFR). SFR model is simplified from other models, which can be used to estimate the frequency response of a large power system, or sudden load disturbance of the island.SFR model is based on the neglecting nonlinear power system of u the units equation, which is controlled by the steam turbine generator . This means that the generator inertia and reheat time constant make system average frequency response. In addition, because of the two time constant , the resulting frequency response can be calculated in the closed loop form, which provides a simple and accurate method to estimate the essential characteristics of the system frequency response.

Abstract: This article will introduce the mechanical loosening form caused by rotating machinery, analysize the fault characteristics and typical spectrum of all types of loosening form and vibration mechanism caused by mechanical loosening

Abstract: It has been demonstrated in previous studies that the evaluation of soundscape was influenced by not only social characteristics but also some behavioral characteristics of persons. In this study, more than 600 questionnaire survey has been undertaken at waiting halls of 4 railway stations in capital cities of China, to determine how the users’ behavioral characteristics influence their evaluation of soundscape. The results show that the relationships between evaluation of acoustics and passengers’ waiting time, rest or partners is not significant (p>0.1), but visiting times (p<0.01). The evaluation of subjective loudness is the highest, when waiting time at 1.5 to 2 hours, while evaluation of subjective loudness is general lower at other time. The evaluation of acoustic comfort is more different between sitting and standing, when waiting time at 0.5 to 1 hour. The passengers with no partner will give general higher acoustic comfort at first (<0.5 hours), but give lower acoustic comfort at following time.

Abstract: A general formulation to obtain the analytical expression for the sensitivity of the acoustic power radiation by a vibrating closed structure to one its design variables is described. The formulation is based on finite elements and the theory of acoustic radiation modes. The sensitivity coefficients indicate the effect of changing various designs or modeling parameters on the acoustic power and can be used to optimize the structure for minimum sound radiation. Putting a rectangle case as an example and verifying the feasibility of this method.