Risk Analysis of a Gas-Processing Complex in India

ONGC's Hazira Gas-Processing Complex (HGPC) consists of facilities for receiving natural gas along with associated condensate from an off-shore field at a rate of 20 MMN M3 per day. After separating the condensate, which is processed in condensate fractionation units, the gas is processed through various steps to recover LPG and to reduce its dew point to less than 5 degrees C in order to make it suitable for transportation over long distances. The acid gas recovered during the gas-sweetening step is processed to obtain sulphur. The major products manufactured at HGPC therefore are lean sweet gas, LPG, NGL, and sulphur. The Oil and Natural Gas Commission awarded the assignment on Hazard Study and Risk Analysis of their Hazira Gas-Processing Complex (HGPC) to the Council of Scientific and Industrial Research (CSIR) in association with the Netherlands Organisation for Applied Scientific Research (TNO). The scope of this assignment covered a number of closely related and fully defined activities normally encountered in this type of work. Identification of hazards through the most appropriate methods, assigning frequency of occurrence of major unwanted incidents, quantification and assessment of probable damage to plant equipment, environment, human and animal life due to an unexpected event, and evaluation of various methods for reducing risk, together constituted the methodology for this assignment. Detailed recommendations aimed at reducing risk and enhancing reliability of plant and machinery were made. This article gives an overview of the assignment.     

Recurrence relations between product moments of order statistics

A general result for obtaining recurrence relations between product moments of order statistics is established and this result is used to determine the recurrence relations between product moments of some doubly truncated distributions. The examples considered are Weibull, exponential, Pareto, power function and Cauchy distributions.     

A note on the asymptotic efficiency of the sobel–wald test

Let X₁,X₂, … be iid random variables with the pdf f(x,θ)=exp(θx?b(θ)) relative to a σ-finite measure μ, and consider the problem of deciding among three simple hypotheses H_i:θ=θ_i (1?i?3) subject to P(acceptH_i|θ_i)=1?α (1?i?3). A procedure similar to Sobel–Wald procedure is discussed and its asymptotic efficiency as compared with the best nonsequential test is obtained by finding the limit lim_a→0(E_iN(a)/n(a)), where N (a) is the stopping time of the proposed procedure and n(a) is the sample size of the best non-sequential test. It is shown that the same asymptotic limit holds for the original Sobel–Wald procedure. Specializing to N(θ,1) distribution it is found that lim_a→0$\text{(E}{}_{\mathrm{i}}\text{N(α)/n(α))=}\text{1}\text{4}$ (i=1,2) and lim_a→0 (E₃N(α)n(α))=δ²₁/4δ, where δ_i=(θ_i+1?θ_i) with 0<δ₁?δ₂. Also, the asymptotic efficiency evaluated when the X's have an exponential distribution.     

A note on the admissibility of hammersley's estimator of an integer mean

Let X₁, X₂, …, X_n be identically, independently distributed N(i,1) random variables, where i = 0, ±1, ±2, … Hammersley (1950) showed that d = [X?_n], the nearest integer to the sample mean, is the maximum likelihood estimator of i. Khan (1973) showed that d is minimax and admissible with respect to zero-one loss. This note now proves a conjecture of Stein to the effect that in the class of integer-valued estimators d is minimax and admissible under squared-error loss.     

Caste and Muslim Peasantries of North India and East and West Pakistan

On croit généralement que l'lslamisme est une confession religieuse égalitaire et qu'il en découle que les sociétés où l'on est de cette religion n'ont pas un systéme rigide de stratification. A la suite d'une recherche effectuée auprès de paysans musulmans dans le nord de l'lnde et dans les régions orientale et occidentale du Pakistan, l'auteur indique au contraire que des classes rigides existent dans des sociétés de religion islamique. II tente de démontrer que la rigidité de cette stratification tient en partie à la tradition islamique même et pas seule-ment à rinfluence des castes hindoues.     

Asymmetric impact of inflation and unemployment on poverty in Pakistan: new evidence from asymmetric ARDL cointegration

The current study is intended to examine the asymmetric impact of inflation and unemployment on the poverty of Pakistan over the period of 1970 to 2016 by applying asymmetric Autoregressive Distributed Lag (ARDL) cointegration approach. The results revealed the presence of long-run asymmetries among inflation, unemployment and poverty. These findings also confirmed the atypical reaction of poverty to negative and positive shocks in unemployment and inflation. Furthermore, findings also confirmed negative and significant association among health expenditures (HE), population growth and poverty. The findings of the study have relevant implications for policymakers interested in the asymmetric relationship among inflation, unemployment and poverty in Pakistan.     

Regional disparities in Indonesia: A social indicators approach

The paper examines the nature of regional imbalance in Indonesia by using a number of social indicators. Several disaggregated social indices are constructed with the help of a taxonomic technique. For the purpose of comparison, an overall economic index is also constructed. It is observed that the ranking of provinces differ substantially across the indices, implying that there is no causal relationship between the selected social and economic indicators. Regional disparities declined in the past decade in terms of all social indices except the demographic index. Economic inequality nowever increased between 1970 and 1980.     

The effect of child mortality experience on subsequent fertility: in Pakistan and Bangladesh

Summary This paper presents an empirical analysis of the effects, behavioural and biological, of child mortality experience on subsequent fertility in two South Asian Islamic nations. Data for the investigation came from retrospective pregnancy histories of 2,910 currently married women interviewed in the Pakistan National Impact Survey (1968-69) and from longitudinal vital registration data (1966-2070) of 5,236 women residing in a rural area of Bangladesh collected by the Cholera Research Laboratory. The aim of this study was to assess the importance of the child-replacement motivational response to child death experience after biological effects have been controlled adequately. A common approach employed previously has been to examine cumulative fertility according to child death experience. In Pakistan and Bangladesh, a consistently positive relationship was demonstrated between the number of children ever born and the number of child deaths. This method, however, did not exclude the inverse relationship, the influence of fertility on mortality, nor did it dissect out behavioural from biological effects. Utilizing a measure of subsequent fertility, live-birth-to-live-birth intervals, the study further illustrated another common pitfall. Since the risk of infant death, which leads to shorter birth intervals, is associated with the mother's reproductive history, women with child mortality experience are more likely to experience shorter intervals because of the biological effect of subsequent infant death. Behavioural influences may, therefore, be observed by considering only those birth intervals in which the first-born child survives to the end of the interval. With these limitations controlled, very few, if any, behavioural influences were noted in the Pakistan and Bangladesh data. Median birth intervals in Pakistan varied between 35-43 and 41-42 months, increasing with parity. Within each parity group, no consistent difference was observed between women with and without previous child loss. In Bangladesh, the median birth interval for all women with a surviving infant was 37-2 months. This was shortened to 24-31 months by an infant death. When intervals with infant deaths were excluded, little or no behavioural influence was detected among women of the same parity, but with varying levels of previous child loss. Even without behavioural effects, elimination of infant mortality in Bangladesh would reduce fertility by prolonging the average period of post-partum sterility. In the Bangladesh setting, however, the size of the effect was only about four per cent. This modest effect, more-over, was counterbalanced by an overall increase of net reproduction by seven per cent due to better survivorship of infants.     

Combining Bayesian method and Kalman smoother for detection additive outlier patches in autoregressive time series

ABSTRACT

This article proposes a development of detecting patches of additive outliers in autoregressive time series models. The procedure improves the existing detection methods via Gibbs sampling. We combine the Bayesian method and the Kalman smoother to present some candidate models of outlier patches and the best model with the minimum Bayesian information criterion (BIC) is selected among them. We propose that this combined Bayesian and Kalman method (CBK) can reduce the masking and swamping effects about detecting patches of additive outliers. The correctness of the method is illustrated by simulated data and then by analyzing a real set of observations.