The impact of preventive voice care programs for training teachers: A longitudinal study

The teaching profession puts vocal health at a higher risk than other professions, causing what is referred to as "occupational dysphonia." There is a need for primary prevention of "occupational dysphonia" among the teaching profession, where good vocal health is promoted before a problem occurs. To investigate the primary prevention of occupational dysphonia among teachers, this study uses a sample population of 55 training teachers, in the postgraduate certificate of education (PGCE) course at the University of Ulster, Northern Ireland, who were randomly assigned to three training groups: control, indirect, and direct. The vocal performance of the three groups was measured at two points over the year of the PGCE course: first before any teaching or training began, and again after the first teaching practice. The training for the indirect and direct groups was provided before the teaching practices. Acoustic and self-perceptual measurements were used to assess the multidimensional outcomes. The results demonstrate interesting trends, that although not found to be significant, are approaching significance. Their voices will be reevaluated at a third point of measurement. The acoustic measurement reflects deterioration from time 1 to time 2 for the control group, improvement for the direct group, and no change for the indirect group, indicating that the training has proved beneficial. The self-rating scores vary in agreement with the acoustic results, presenting interesting findings. The findings of this study will be of benefit to teachers, their educators, voice therapists, health promoters, and human resource personnel.     

Effects of singing training on the speaking voice of voice majors

This longitudinal study gathered data with regard to the question: Does singing training have an effect on the speaking voice? Fourteen voice majors (12 females and two males; age range 17 to 20 years) were recorded once a semester for four consecutive semesters, while sustaining vowels and reading the "Rainbow Passage." Acoustic measures included speaking fundamental frequency (SFF) and sound pressure level (SLP). Perturbation measures included jitter, shimmer, and harmonic-to-noise ratio. Temporal measures included sentence, consonant, and diphthong durations. Results revealed that, as the number of semesters increased, the SFF increased while jitter and shimmer slightly decreased. Repeated measure analysis, however, indicated that none of the acoustic, temporal, or perturbation differences were statistically significant. These results confirm earlier cross-sectional studies that compared singers with nonsingers, in that singing training mostly affects the singing voice and rarely the speaking voice.     

Optimizing the Ex-post Trading Profits in a Financial Market

1.Introduction"Buylow,sellhigh"isaninveStmentdicttnnwhichiseasiersaidthandone.Thefacultyinvolvedisthatthefutureisunknownand'highs,and'lOws,arenotwelldefinedunlessthefuturepricesareknobs.However,evenwhenthefUturepricesarecompletelyknown,itmaynotbeeasytodet…     

Associative memory approach to the identification of structural and mechanical systems

This paper presents a new method for identification of parameters in nonlinear structural and mechanical systems in which the initial guesses of the unknown parameter vectors may be far from their true values. The method uses notions from the field of artificial neural nets and, using an initial set of training parameter vectors, generates in an adaptive fashion other relevant training vectors to yield identification of the parameter vector in a recursive fashion. The simplicity and power of the technique are illustrated by considering three highly nonlinear systems. It is shown that the technique presented here yields excellent estimates with only a limited amount of response data, even when each element of the set comprising the initial training parameter vectors is far from its true value—in fact, sufficiently far that the usual recursive identification schemes fail to converge.     

Optimal skill mix: An application of the maximum principle for systems with retarded controls

In this paper, we analyze the optimal skill mix in a model with two kinds of imperfectly substitutable labor, skilled and unskilled. The population is characterized by a distribution of innate abilities, and individuals are trained according to optimal rules or market rules (with imperfect expectations); the length of each individual's training period depends upon his innate ability. The market and optimal rules are characterized and compared, and corrective policies are investigated. This model represents a major advance over earlier models, which are based on the following assumptions: (a) either unskilled and skilled labor are perfectly substitutable or training is a necessary condition for employment; (b) individuals are innately identical; (c) in most cases, training occurs either instantaneously or with fixed lag.Earlier versions of this paper were delivered at the IFAC/IFORS International Conference on Dynamic Modelling of National Economies held in Coventry, England. A Guest Lecture was delivered by the first author to the 14th Biennial Seminar of the Canadian Mathematical Congress on Optimal Control Theory and its Applications held in London, Ontario, 1973. The authors acknowledge with appreciation support from a National Science Foundation Grant in Economics to Carnegie-Mellon University; in addition, the second author was supported by a Ford Foundation Faculty Research Fellowship during the academic year 1970–71. The authors are indebted to D. Cass, R. E. Lucas, and G. L. Thompson for valuable comments on an earlier draft, although all remaining errors of commission and omission are ours.     

完善数学建模课程体系，提高学生自主创新能力

随着大学生数学建模竞赛的快速发展,全国大部分高校越来越认识到数学建模教学在大学生创新意识和实践能力培养中的重要作用,如何提高数学建模活动的成效成为普遍关注的问题。从数学建模课程的本质出发,尝试构建了较为完善的数学建模教学体系,达到数学建模教学贯穿大学生培养的全过程的教学理念。同时讨论了拓宽数学建模活动形式的途径和尚存在亟待解决的几个问题。     

基于复数神经网络的粘弹性材料动态模量拟合方法

固体火箭发动机药柱粘弹性材料除具有弹塑性特性,还具有粘滞性,这一特性使得材料变形具有明显的时间效应,本构关系复杂,进行动态力学分析时,动态模量难以有效拟合．本文提出了一种基于(Levenberg-Marquardt, L-M)算法的复数神经网络拟合粘弹性材料动态模量的方法．通过广义Maxwell模型推导得到材料的动态模量表达式,以此构造未定网络参数为复数的神经网络,从而提供了一种输入、输出样本均为复数的神经网络解决方法．将实数L-M训练算法进行改进,衍生到复数领域,提出复数L-M训练算法．通过粘弹性材料实验,将实验数据时温等效转换,获得复数神经网络的训练及测试样本．通过对神经网络进行训练,实现粘弹性材料动态模量的高精度拟合．数值算例表明,与传统神经网络拟合方法相比,所提方法在训练速度和泛化能力方面都有其优越性．     

Effects of vocal training on the acoustic parameters of the singing voice

Vocal training (VT) has, in part, been associated with the distinctions in the physiological, acoustic, and perceptual parameters found in singers' voices versus the voices of nonsingers. This study provides information on the changes in the singing voice as a function of VT over time. Fourteen college voice majors (12 females and 2 males; age range, 17–20 years) were recorded while singing, once a semester, for four consecutive semesters. Acoustic measures included fundamental frequency (F₀) and sound pressure level (SPL) of the 10% and 90% levels of the maximum phonational frequency range (MPFR), vibrato pulses per second, vibrato amplitude variation, and the presence of the singer's formant. Results indicated that VT had a significant effect on the MPFR. F₀ and SPL of the 90% level of the MPFR and the 90–10% range increased significantly as VT progressed. However, no vibrato or singers' formant differences were detected as a function of training. This longitudinal study not only validates previous cross-sectional research, ie, that VT has a significant effect on the singing voice, but also it demonstrates that these effects can be acoustically detected by the fourth semester of college vocal training.     

通过数学建模竞赛 培养研究生创新思维的探索与实践

全国研究生数学建模竞赛是教育部研究生教育创新计划项目,旨在通过举办竞赛不断增强研究生数学建模创新能力,为提高研究生培养质量奠定重要的知识和能力基础．本文介绍了我院在组织研究生参加大赛并取得较好成绩的成功经验和做法．     

开展3+1培养模式 科学地发展地实践信息与计算科学专业的建设

结合农垦院校办学特色和信息与计算科学专业的办学定位和办学指导思想,科学地发展地调整课程体系的设置,集思广益,认真制定、修订和运行教学计划;优化实践教学设置和深化实践教学内容,并积极建立长期的稳定的校外实习基地;与北京科瑞尔思研究院—大庆实训实习基地合作开展3+1培养模式,收到良好效果.