Analysis of a two-echelon inventory system with returns

Product take-back and recovery activities have grown in recent times as a consequence of stringent government regulations and increased customer awareness of environmental pollution. Inventory management in the context of product returns has drawn the attention of many researchers. However, the inherent complexity of the system with uncertain returns makes the analysis of the system extremely difficult. So far, the literature on this type of system is mostly limited to single echelons. The few papers available in literature on multi-echelon systems with returns base their analyses on simplified assumptions such as non-existence or non-relevance of set-up and holding costs at different levels. In this paper, we relax these assumptions and consider a two-echelon system with returns under more generalized conditions. We develop a deterministic model as well as a stochastic model under continuous review for the system, and provide numerical examples for illustration.     

SB-robust estimator for the concentration parameter of circular normal distribution

In this paper we discuss robust estimation of the concentration parameter (κ) of the circular normal (CN) distribution. It is known that the MLE of the concentration parameter is not B-robust at the family of all circular normal distributions with fixed mean direction (μ) and varying κ > 0. In this paper we propose a new estimator for κ and show that it is B-robust and SB-robust at the family {CN(μ, κ) : m ≤ κ ≤ M} where m and M are two arbitrary constants.     

Pearsonian Type I curve and its fertility projection potentials

New procedures are developed in this article for estimating parameters of the Pearsonian Type I curve which are particularly adaptive to factors influencing the pattern of age-specific fertility rates. It is shown that with this model the number of parameters required for the graduation and simulation of these rates can be reduced to only three—total fertility rate, mean and modal ages of fertility. The reduction in the number of fertility parameters offers considerable operational and analytical advantages, and makes the Pearsonian Type I curve particularly appropriate for the construction of a parametric model for fertility projections. In light of the results of empirical tests based on fertility data for Canada, the model’s potential for birth projections appears quite promising.     

Date fighting experiences among college students: are they associated with other health-risk behaviors?

OBJECTIVE: The authors examined the clustering of health-risk behaviors among college students who reported date fight involvement. PARTICIPANTS AND METHODS: The authors administered a Web-based survey to a stratified random sample of 3,920 college students from 10 universities in North Carolina. RESULTS: Among men, 5.6% reported date fight victimization, and 1% reported date fight perpetration. Victimization among men was associated with (1) first drink at age 15 years or younger, (2) a recent threat of violence by someone who had been drinking, (3) smoking, (4) amphetamine use, and (5) older age. Among women, 6.7% reported date fight victimization, which was associated with (1) older age, (2) assault from a student who had been drinking, (3) sex with 2 or more persons, (4) consumption of alcohol in high school, (5) illegal drug use, (6) nonsexual assault requiring medical treatment, and (7) living off campus. Of the women, 4.2% reported date fight perpetration, which was associated with (1) minority race/ethnicity, (2) older age, (3) frequency of sexual intercourse, and (4) alcohol and marijuana use. CONCLUSIONS: Date fight experiences were associated with multiple health-risk behaviors among this sample of college students.     

Sequential estimation of the sum of sinusoidal model parameters

Estimating the parameters of the sum of a sinusoidal model in presence of additive noise is a classical problem. It is well known to be a difficult problem when the two adjacent frequencies are not well separated or when the number of components is very large. In this paper we propose a simple sequential procedure to estimate the unknown frequencies and amplitudes of the sinusoidal signals. It is observed that if there are p components in the signal then at the k  th (k?p)$(k?p)$ stage our procedure produces strongly consistent estimators of the k   dominant sinusoids. For k>p$k>p$, the amplitude estimators converge to zero almost surely. Asymptotic distribution of the proposed estimators is also established and it is observed that it coincides with the asymptotic distribution of the least squares estimators. Numerical simulations are performed to observe the performance of the proposed estimators for different sample sizes and for different models. One ECG data and one synthesized data are analyzed for illustrative purpose.     

Youth Participation in U.S. Contexts: Student Voice Without a National Mandate

Unlike the United Kingdom and other nations that mandate youth participation to some degree, U.S. policies instead tend to inhibit child participation rather than encourage it. Given these policy contexts, it can be challenging to locate spaces where robust opportunities for democratic participation and student voice exist. We use this article as an opportunity to examine the disciplinary, philosophical and methodological approaches that have framed youth participation in youth contexts. We conclude by identifying critical issues of citizenship and belonging that must be considered in participatory research.     

Merchandizing the Sacred: Commodifying Hindu Religion,Gods/Goddesses,and Festivals in the United States

The Immigration and Nationality Act of 1965 opened the gates for immigrants from India, who have come to the United States for various reasons other than religion. Their religious consciousness has grown along with the age of their children who are born in the United States. They have felt the need to retain and hand down their tradition and culture. In the process, sustaining their tradition and culture has become equivalent with religion, so they express it through rituals and festivals. With these festive observances has developed an intimate connection between commerce and religion, fashion and festival, celebration and consumption. In this scholarly essay, I analyze how Hindu religion has succumbed to the world of advertisements, mass production, and marketing in the United States. This aspect is significant because it gives an opportunity to conceptualize a larger transnational space that deals with Hindu religious practices and sees the participation of retailers and businesses located in various Hindu diasporic spaces using various marketing media strategically.     

Technology Import and Industrial Employment: Evidence from Developing Countries

Abstract. This paper based on panel data across countries examines the possible effect of the imported technology on labour absorption in the industrial sector, after controlling for real wage rate and GDP per capita. Findings tend to suggest a negative relationship between the two. Technical efficiency index derived on the basis of the stochastic frontier function framework is also negatively affected by the import of technology. Without enhancing the knowledge relating to the mechanisms of exploiting the new technology acquired from abroad, a mere increase in import of technology would mean rising unutilized capacity. And this could be due to the poor skill base of the available human capital. Investment in human capital in terms of skill formation, up‐gradation, and training on the one hand and technological advancement to suit the internal labour market conditions are the two important policy conclusions for reviving the role of industry as the engine of pro‐poor growth.     

On approximate least squares estimators of parameters of one-dimensional chirp signal

Chirp signals are quite common in many natural and man-made systems such as audio signals, sonar, and radar. Estimation of the unknown parameters of a signal is a fundamental problem in statistical signal processing. Recently, Kundu and Nandi [Parameter estimation of chirp signals in presence of stationary noise. Stat Sin. 2008;75:187–201] studied the asymptotic properties of least squares estimators (LSEs) of the unknown parameters of a simple chirp signal model under the assumption of stationary noise. In this paper, we propose periodogram-type estimators called the approximate least squares estimators (ALSEs) to estimate the unknown parameters and study the asymptotic properties of these estimators under the same error assumptions. It is observed that the ALSEs are strongly consistent and asymptotically equivalent to the LSEs. Similar to the periodogram estimators, these estimators can also be used as initial guesses to find the LSEs of the unknown parameters. We perform some numerical simulations to see the performance of the proposed estimators and compare them with the LSEs and the estimators proposed by Lahiri et al. [Efficient algorithm for estimating the parameters of two dimensional chirp signal. Sankhya B. 2013;75(1):65–89]. We have analysed two real data sets for illustrative purposes.     

M-estimator-based robust estimation of the number of components of a superimposed sinusoidal signal model

In this paper, we consider the problem of estimating the number of components of a superimposed nonlinear sinusoids model of a signal in the presence of additive noise. We propose and provide a detailed empirical comparison of robust methods for estimation of the number of components. The proposed methods, which are robust modifications of the commonly used information theoretic criteria, are based on various M-estimator approaches and are robust with respect to outliers present in the data and heavy-tailed noise. The proposed methods are compared with the usual non-robust methods through extensive simulations under varied model scenarios. We also present real signal analysis of two speech signals to show the usefulness of the proposed methodology.