青少年学生纯音听力级调查

为了了解青少年的听力零级,并为优秀耳的筛选提供基础数据,使用医用听力计对三组青少年群体的纯音听力级进行调查观测。被调查群体包括一组农村中小学校学生,一组大学生,一组专科学校学员。参考其它研究者的文献数据,对青少年群体的纯音听力级进行了分析。发现调查结果与其它文献所给出的数据有明显差异,根据调查结果提出了优秀耳的纯音听力级筛选建议。     

Finite element crash simulations of the human body: Passive and active muscle modelling

Conventional dummy based testing procedures suffer from known limitations. This report addresses issues in finite element human body models in evaluating pedestrian and occupant crash safety measures. A review of material properties of soft tissues and characterization methods show a scarcity of material properties for characterizing soft tissues in dynamic loading. Experiments imparting impacts to tissues and subsequent inverse finite element mapping to extract material properties are described. The effect of muscle activation due to voluntary and non-voluntary reflexes on injuries has been investigated through finite element modelling.     

Mathematical modelling of the cardiovascular system

This paper is an introduction to the special issue of the Journal of Engineering Mathematic (Volume 47/3–4, 2003) on the mathematical modelling of the cardiovascular system. This issue includes the 2003 James Lighthill Memorial Paper written by Pedley [1] on the mathematical modelling of arterial fluid dynamics. This introduction is written to bring cardiovascular biomechanics to readers with a background in mathematical modelling and computational mechanics. The importance of mathematical modelling for physiological understanding, diagnostics, prosthesis development, patient selection and medical planning is indicated and discussed shortly. A subdivision into models for cardiac mechanics, pressure- and flow-wave propagation, mass transfer and fully three-dimensional fluid-structure interaction is made and references are given to the different contributions of the issue.     

大学生群体听力损失的调查研究

运用网络问卷调查和主观听音测试两种方法,对大学生群体的听力损失问题进行了研究。网络调查结果表明,相比听音习惯良好的人群,具有不良听音习惯人群的听力损失比例更高,而高年级人群也比低年级人群的的听力损失比例要高。由听音实验测出的等响曲线进一步印证了上述结果。结果表明,应重视对大学生群体的听力保护,养成良好的听音习惯和定期上医院做听力检查将有助于消除或降低大学生群体听力损失的风险。     

Mathematical modelling of a robust inspection process plan: Taguchi and Monte Carlo methods

This study develops a new optimisation framework for process inspection planning of a manufacturing system with multiple quality characteristics, in which the proposed framework is based on a mixed-integer mathematical programming (MILP) model. Due to the stochastic nature of production processes and since their production processes are sensitive to manufacturing variations; a proportion of products do not conform the design specifications. A common source of these variations is maladjustment of each operation that leads to a higher number of scraps. Therefore, uncertainty in maladjustment is taken into account in this study. A twofold decision is made on the subject that which quality characteristic needs what kind of inspection, and the time this inspection should be performed. To cope with the introduced uncertainty, two robust optimisation methods are developed based on Taguchi and Monte Carlo methods. Furthermore, a genetic algorithm is applied to the problem to obtain near-optimal solutions. To validate the proposed model and solution approach, several numerical experiments are done on a real industrial case. Finally, the conclusion is provided.     

响度感知特征研究进展

响度是反映人耳对声音强弱感知的最基本参量,它是分析计算很多其它心理声学参量的基础。响度特征的研究不仅在噪声评价、心理学及声品质方面有重要的应用,还广泛应用于语音信号处理等方面。在此从等响曲线、双耳异响条件下的响度感知特征以及纯音和复音时变信号响度感知特征等三个方面介绍了近年来的研究结果。     

Mathematical modelling of moisture-induced panel deformation

A new mathematical model is introduced to describe the moisture-induced deformation in an elastic panel. The problem for the stresses is found to be singularly perturbed in the aspect ratio squared, the domain being split into four asymptotic regions. Determination of the matching constants is made possible by the introduction of a stress function in the boundary layer. Explicit expressions are derived for the stress and deformation in the three-dimensional problem. The predictions for deformation are compared with experimental results; the agreement is reasonable. The moment of the moisture concentration is found to be the crucial factor in determining panel warp. A model, which consists of two coupled parabolic equations, is also proposed for moisture transport in exterior applications. The disparate time-scales allow the system to be reduced to a single partial differential equation. In one parameter régime, a multiple-scale analysis further reduces this partial differential equation to an averaged equation which only requires solution over the long moisture-diffusion time-scale.     

广州市老年人听力状况调查与分析

采用老年人听力障碍(Hearing Handicap Inventory for the Elderly,HHIE)量表在广州市内随机调查了582名60岁以上老年人,获取广州市内老年人的听力状况,探讨老年人的听力状况与各因素之间的关系。统计结果显示:广州市老年人听力障碍患病率是42.1%;高龄老人更易因听力问题而影响日常生活和身心健康,且70岁左右的年龄是老年人听力损失的敏感年龄;有听力障碍的老年人使用助听器的比重较低且多集中在大于75岁的高龄段,使用助听器的老年人多为重度听力障碍者,双耳使用助听器的老年人的HHIE得分显著高于单耳使用助听器的老年人。     

Mathematical modelling of toxicity-related trade-offs in metronomic chemotherapy

For better quality of life (QoL) for the cancer patients, metronomic chemotherapy (MCT) would be the rational option instead of conventional chemotherapy. However, in view of the recent arguments regarding the accumulation of toxicity in MCT, it is worthwhile to examine the role of pathophysiological constraints in retarding the curative potential of MCT. Drug application is stopped upon attaining a certain high level of toxicity and subsequent resumption is possible once the toxicity drops below a certain low level. Large delays in subsequent drug administration can thus effectively handle toxicity and it may retard the therapeutic potential due to excessive tumour growth in the absence of drug. Small delays, on the other hand, may result in inoperable pathophysiological states resulting in poor QoL. It is argued that only the intervention of domain knowledge of an expert oncologist with respect to drug administration decision can in fact clinch the trade-off issues arising out of the situation in favour of a sustainable QoL. A mathematical model that may act as a general guideline to tackle the trade-off issues in cancer treatment is provided. Rigorous simulation exercises are required to establish the concept of MCT in the backdrop of conventional cancer treatment practices.     

Mathematical modelling and computer simulation of nitriding

Abstract

Mathematical modelling of matter transmission during gas nitriding has been deduced by a numerical calculation in the present study. The diffusion coefficient of nitrogen in 38CrMoAl steel and the matter transmission coefficent in the interfacial reaction have been measured. Owing to the large difference between the nitrogen activity at the surface of the workpiece and that of the gas phase during the nitriding process, it is very difficult to control the nitrogen potential and balance the nitrogen activity. In order to solve this problem, is it proposed that the nitrogen potential is dynamically controlled by computer. Under conditions of high nitriding speed, the computer controlled technique used in practical manufacture shows good reproducibility and can control the nitrogen potential accurately, thereby reducing the brittleness of the nitrided layer.     

Mathematical modelling of test limits and guardbands

To gain market share on product performance, suppliers will routinely specify product datasheet (DS) performance to tighter than six sigma specifications. To maintain quality levels in this instance, the product must be 100% tested in production to screen out parts that are outside specification. Because of test measurement error and temperature drift, the test limits (TLs) used must be guardbanded tighter than the DS limit to ensure that the shipped product meets the parts per million requirement. These guardbands are protection zones that protect the customer from receiving parts that are outside specification. A review of current guardbanding techniques finds that they are conservative in nature. New guardbanding models are presented, which calculate the limit sets required for production test, quality assurance test and DS limit specifications. These models account for both test measurement error and temperature drift. Model results show that the guardband required varies with Cpk of the TL, test measurement error and temperature correlation coefficient. Copyright © 2009 John Wiley & Sons, Ltd.     

Mathematical modelling of creep/environment interactions

Physically-based creep Continuum Damage Mechanics (CDM) is briefly reviewed to introduce the formalism necessary for mathematical modelling of creep and fracture in the presence of a chemically-interacting fluid environment. A recently developed theory of creep in precipitation-hardened alloys is presented in the form of a constitutive equation and two important creep/environment interactions are discussed in detail. Spallation of oxide scales during creep of a low-alloy ferritic steel is one and is modelled using the new creep constitutive equation which incorporates particle-ageing as the principal intrinsic damage mechanism. Lack of experimental data has meant that only qualitative support for the model predictions could be given. Carbon dioxide gas bubble formation along grain boundaries in nickel alloys is the other form of environmental attack considered; a new kinetic model based upon oxyen diffusion-control is described and shown to be in quantitative agreement with a large experimental dataset.     

Mathematical modelling of dimensional accuracy in vacuum assisted casting

Vacuum assisted casting (VAC) is one of the prototype making processes used to generate replicas of plastic components (PC) for batch production activities (like: investment casting applications). In the present study, the outcome of the Taguchi model has been used for developing a mathematical model for dimensional accuracy (DA) using Buckingham's π-theorem for VAC of PC. Four input parameters, namely material type, mixing ratio (hardener: softener), de-mould time and de-mould temperature, were selected to give output in the form of DA. This study will provide the main effects of these variables on DA and will shed light on the mechanism of DA in VAC for replicas of PC. The comparison with experimental results will also serve as further validation of the model.     

模拟听觉的机器故障诊断设备的框架

文章先分析谱相关和人耳听觉的某些相似特性,如两者都不管信号的初相位,即使相位相差90°的正弦和余弦信号,只要频率相同人耳听到的是同样的声音,而谱相关系数也接近于1。然后,利用谱相关系数模拟人耳听觉的某些特性,提出一个机器故障诊断设备的框架。     

基于主成分分析的护听器优选方法研究

为了探究不同护听器对抽水蓄能电站内不同工作场所的降噪效果及适用情况,以便于工作人员根据不同需要选择合适的护听器,根据112种护听器的插入损失测试结果,应用主成分分析(Principal Component Analysis, PCA)对数据进行分析。结合某抽水蓄能电站10个工作场所的现场测试结果,得出文中所测试的112种护听器大部分适用于该蓄水电站中1#发电机隔声罩内、1#水车室外、1#水车室内、2#尾水锥管室外、2#尾水锥管检修门、3#尾水锥管室外和3#尾水锥管检修门7个工作场所,其他场所需要有针对性地选择适合的护听器。该文同时可以为其他不同工作场所情况下护听器的选择提供借鉴。     

Mathematical modelling of microsegregation in eutectic and peritectic binary alloys

Abstract

A mathematical model of microsegregation for eutectic and peritectic binary alloys was implemented using a finite volume method to solve the differential equations for mass transport. In this model simple ideas are used to handle phase boundaries and coarsening without the need to employ node jumping schemes or any transformation of variables to fix the domain size. Some model results were compared with available analytical solutions, revealing excellent agreement, which proved the approach useful to solve dissolution and diffusion coupled problems as well as microsegregation ones. Furthermore, good agreement was observed between the model results and measurements of eutectic volume fractions published previously for an Al–Cu alloy. The model was also capable of showing some important features of a typical peritectic transformation. Some instability was observed during model calculations, but it was easily handled by a time step refining technique.     

Quantitative analysis of harmonic convergence in mosquito auditory interactions

This article analyses the hearing and behaviour of mosquitoes in the context of inter-individual acoustic interactions. The acoustic interactions of tethered live pairs of Aedes aegypti mosquitoes, from same and opposite sex mosquitoes of the species, are recorded on independent and unique audio channels, together with the response of tethered individual mosquitoes to playbacks of pre-recorded flight tones of lone or paired individuals. A time-dependent representation of each mosquito''s non-stationary wing beat frequency signature is constructed, based on Hilbert spectral analysis. A range of algorithmic tools is developed to automatically analyse these data, and used to perform a robust quantitative identification of the ‘harmonic convergence’ phenomenon. The results suggest that harmonic convergence is an active phenomenon, which does not occur by chance. It occurs for live pairs, as well as for lone individuals responding to playback recordings, whether from the same or opposite sex. Male–female behaviour is dominated by frequency convergence at a wider range of harmonic combinations than previously reported, and requires participation from both partners in the duet. New evidence is found to show that male–male interactions are more varied than strict frequency avoidance. Rather, they can be divided into two groups: convergent pairs, typified by tightly bound wing beat frequencies, and divergent pairs, that remain widely spaced in the frequency domain. Overall, the results reveal that mosquito acoustic interaction is a delicate and intricate time-dependent active process that involves both individuals, takes place at many different frequencies, and which merits further enquiry.     

Mathematical modeling of the process of sublimation drying

A complex physicomathematical analysis of vacuum sublimation drying has been given. Approaches to calculation and designing of sublimation dryers have been proposed. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 1, pp. 48–55, January–February, 2006.     

Mathematical modeling of the process compaction of wood

Within the framework of the mechanics of heterophase systems a mathematical model for the process of pressing wood has been offered; this model takes account of the influence of its complex rheological properties and surface phenomena in thin interlayers of water on the change in a porous structure. With numerical methods, a study has been made of the influence of the sample’s humidity and temperature fields on the strength and quality of the material obtained. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 78, No. 5, pp. 62–69, September–October, 2005.