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21.
Jackhammer manufacturers have recently developed lightweight (45-60 lbs) jackhammers intended to reduce the required lifting and pushing forces during operation. However, the vibration characteristics of the lightweight jackhammers and their effect on muscle activity are currently unknown. The objective of this study was to compare the measured vibration and muscle activity between: (i) conventional (90 lb) and light weight (60 lb) jackhammers, (ii) different pavement type/thickness combinations, and (iii) pneumatic and hydraulic jackhammers. Five jackhammers were tested on 4 and 6 inch thick asphalt and concrete pavements by four experienced operators. Analysis of the results revealed that both weight classes averaged 9.7 m/s(2) at the 20 Hz weighted 1/3 octave band frequency, and the TLV of daily exposure for either weight class of jackhammer was less than 1.5 hours/per day. There was an approximately 33% difference in vibration measured on the hand of the operators due to pavement thickness, 30% due pavement type, and no difference due to power source. Conventional jackhammers overall produced higher muscle activity than lightweight jackhammers. Although selection of the correct jackhammer for the job involves many factors including pavement type and thickness, the results of this research can be used to assist in selecting the appropriate jackhammer. 相似文献
22.
The present study deals with the method of estimation of the parameters of k-components load-sharing parallel system model
in which each component’s failure time distribution is assumed to be geometric. The maximum likelihood estimates of the load-share
parameters with their standard errors are obtained. (1 − γ) 100% joint, Bonferroni simultaneous and two bootstrap confidence intervals for the parameters have been constructed. Further,
recognizing the fact that life testing experiments are time consuming, it seems realistic to consider the load-share parameters
to be random variable. Therefore, Bayes estimates along with their standard errors of the parameters are obtained by assuming
Jeffrey’s invariant and gamma priors for the unknown parameters. Since, Bayes estimators can not be found in closed form expressions,
Tierney and Kadane’s approximation method have been used to compute Bayes estimates and standard errors of the parameters.
Markov Chain Monte Carlo technique such as Gibbs sampler is also used to obtain Bayes estimates and highest posterior density
credible intervals of the load-share parameters. Metropolis–Hastings algorithm is used to generate samples from the posterior
distributions of the unknown parameters. 相似文献
23.
Shweta Shenoy Jasmine Kaur Chawla Swati Gupta Jaspal Singh Sandhu 《Journal of women & aging》2017,29(4):334-347
The purpose of this study was to find the prevalence of low bone health conditions and assess associated nutritional and other risk factors in Indian women aged 41–60 years. A total of 1,911 women participated in this cross-sectional study. Bone health was assessed using an Omnisense multisite quantitative ultrasound bone densitometer on two sites (radius and tibia). Crude prevalence of osteopenia and osteoporosis was found to be 30.09% and 19.89%, respectively. The Indian women were deficient in a majority of nutrients. Postmenopause, hysterectomy, hyperthyroid, hypothyroid, hypertension, low physical activity, low sun exposure, high stress levels, and low calcium levels were found to be independent risk factors of low bone health. 相似文献
24.
This article considers the problem of estimating the parameters of Weibull distribution under progressive Type-I interval censoring scheme with beta-binomial removals. Classical as well as the Bayesian procedures for the estimation of unknown model parameters have been developed. The Bayes estimators are obtained under SELF and GELF using MCMC technique. The performance of the estimators, has been discussed in terms of their MSEs. Further, expression for the expected number of total failures has been obtained. A real dataset of the survival times for patients with plasma cell myeloma is used to illustrate the suitability of the proposed methodology. 相似文献
25.
This paper applies stratified random sampling using Neyman allocation to Mangat et al. (1992) unrelated question randomized response (RR) strategy for both completely truthful reporting and less than completely truthful reporting. It is shown that, for the prior information given, our new model is more efficient in terms of variance (in the case of completely truthful reporting) and mean square error (in terms of less than completely truthful reporting) than Kim and Elam's (2007) model. Numerical illustrations and graphs are also given in support of the present study. 相似文献
26.
The crux of this article is to estimate the mean of the number of persons possessing a rare sensitive attribute based on the Mangat (1991) randomization device by utilizing the Poisson distribution in simple random sampling and stratified sampling. Properties of the proposed randomized response (RR) model have been studied along with recommendations. It is also shown that the proposed model is more efficient than that of Land et al. (2011) in simple random sampling and that of Lee et al. (2013) in stratified random sampling when the proportion of persons possessing a rare unrelated attribute is known. Numerical illustrations are also given in support of the present study. 相似文献
27.
Housila P. Singh 《统计学通讯:理论与方法》2017,46(8):3957-3984
This paper addresses the problem of estimating a general parameter using information on an auxiliary variable X. We have suggested a class of exponential-type ratio estimators for the parameter and its properties are studied. It is identified that the estimators due to Upadhyaya et al. [Journal of Statistical Theory and Practice (2011), 5(2), 285–302] and Yadav and Kadilar [Revista Columbiana de Estadistica, (2013), 36(1), 145–152] are members of the proposed estimator. We have also shown that the suggested estimator is more efficient than the estimators of Upadhyaya et al. (2011) and Yadav and Kadilar (2013). Numerical illustration is provided in support of the present study. 相似文献
28.
Manju Panwar Deepali Mathur Gian Chand Manju Dkhaka R. R. Singh 《Social Work Education》2014,33(8):984-997
This paper captures the experiences of the faculty members of a relatively new graduate social work program situated in the largely rural state of Haryana India in reframing the foundation year practicum through community-based and engaged action learning in small villages. Located within Bhagat Phool Singh Vishwavidyalaya (BPSMV), north India's first all women public university, the mission of which is to enhance women's engagement in the greater society through post-secondary, professional and character education, the department is educating social workers for community engagement in social development and in the development of women as an empowered group in society, particularly at the village level. Over a three-year period, the faculty has successfully launched and sustained action learning as an alternative to the traditional practicum in social work education, enhanced civic engagement among students and faculty in three rural villages, and further developed community social work as a principal focus of social work education in India. The paper offers a rationale for action learning in the graduate social work curriculum, describes and documents the department's strategy of action learning, and lays out lessons learned from action learning as a central focus of pedagogy, research, and service within BPSMV Department of Social Work and the rural villages it serves. 相似文献
29.
Zawar Hussain Mashail M. Al-Sobhi Bander Al-Zahrani Housila P. Singh Tanveer A. Tarray 《Mathematical Population Studies》2016,23(4):205-221
Randomized response models deal with stigmatizing variables appearing in health surveys. Additive and subtractive scrambling in split sample and double response yield unbiased mean and sensitivity estimators of high precision. The split sample method is protective of privacy. The double response method is as protective only conditionally. To achieve the maximum efficiency, the scrambling variables must be similar to each other and the probability of obtaining a true response must be as large as possible. The randomized response procedures yield more efficient estimates of the average total number of classes missed by university students. 相似文献
30.
In this paper we consider the problem of determining the optimum number of repairable and replaceable components to maximize a system's reliability when both, the cost of repairing the components and the cost of replacement of components by new ones, are random. We formulate it as a problem of non-linear stochastic programming. The solution is obtained through Chance Constrained programming. We also consider the problem of finding the optimal maintenance cost for a given reliability requirement of the system. The solution is then obtained by using Modified E-model. A numerical example is solved for both the formulations. 相似文献