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The construction sector has undergone significant reforms towards increased sustainability in recent decades. Therefore, there has been a great interest in developing alternative binders for stabilising expansive clay subgrades and improving their mechanical properties while mitigating their swelling and shrinking behaviour. One such alternative binder is vinyl acetate-ethylene (VAE) polymers. However, there are only a few studies on utilising polymers, especially VAE polymers, for clay stabilisation. Specifically, there is a lack of research on using VAE polymer-stabilised clays for road subgrade purposes. This study aims to address this knowledge gap by evaluating the potential of using a VAE solid powder polymer to stabilise expansive clay subgrade through a comprehensive series of mechanical tests as well as physicochemical and microstructural analyses. The results of the experiments provide evidence that the introduction of the polymer considerably improved the mechanical strength and swell and shrinkage behaviour of the expansive clay. [ABSTRACT FROM AUTHOR]

Due to the depletion of supplies for high-quality aggregates, it has become necessary to incorporate marginally soft materials like moorum in pavement structural layers. This study aimed to investigate the mechanical characteristics of cementitiously stabilised moorum materials (CSMM), which would be relevant during the mechanistic design of pavements. The tests includes the unconfined compressive strength, california bearing ratio in a soaked state, flexural strength, indirect tensile strength, durability and shrinkage behaviour through a comprehensive laboratory investigation procedure. In this investigation, the collected moorum sample was from Bihar, the eastern state of India. Relationships between various mechanical characteristics have been developed for pavement analyses. The properties are achieved as per standards to study the behaviour of the pavement structures. Based on the research findings, the effectiveness of the strength and shrinkage characteristics in determining the acceptability of CSMM as a road base and subbase applications have been discussed. [ABSTRACT FROM AUTHOR]

Motivated by empirical evidence, this article focuses on the behaviour of a store inventory exposed to inventory record inaccuracy. The inventory, controlled by an infinite horizon, single-stage, single-product periodic-review policy, is subject to shrinkage errors that cause a difference between the physical and information system inventory levels. We model a set of scenarios depending on the technology available to track shrinkage in the store. In scenarios where a technology such as Radio Frequency IDentification (RFID) is not used, inventory is controlled by estimating the expected shrinkage rate. We assume that an inspection process is performed at a regular frequency of N selling periods. We analyse two situations that permit management of the joint ordering and inspection policy based on the information the inventory manager has on shrinkage errors. A comparison between these two situations permits us to analyse the impact of shrinkage errors and the value of taking into account the inventory inaccuracy issue when optimising the inventory and inspection policies. The deployment of the RFID technology produces two benefits: total visibility of the shrinkage rate and the elimination of shrinkage errors. A comparison of the scenarios enables us to evaluate the economic impact of inventory record inaccuracies, which can be significant, particularly in systems with a poor estimation of the error parameter as well as with a high inspection cost. [ABSTRACT FROM PUBLISHER]

Although the Kelly portfolio is theoretically optimal in maximizing the long-term log-growth rate, in practice this is not always so. In this paper, we first show that the sample plug-in estimator of the Kelly portfolio weights is actually biased, and we then propose an unbiased estimator as an alternative. We further derive a shrinkage estimator under the objective of minimizing the expected growth loss of the actual growth relative to the true growth. An explicit formula for the shrinkage coeffi- cient is established. Statistical properties for the shrinkage coefficient are studied through extensive Monte Carlo simulations, and conditions for obtaining accurate estimates for the shrinkage coeffi- cient are also discussed. The effectiveness of the proposed unbiased and shrinkage Kelly portfolios in reducing the expected growth loss are validated by various simulation studies. It is found that our proposed shrinkage Kelly portfolio has superior performances in growth loss reduction, followed by the unbiased Kelly portfolio, and the sample plug-in Kelly portfolio. The advantages of our proposed unbiased and shrinkage Kelly portfolios for long-term investments are additionally confirmed by stock investment in the U.S. market. [ABSTRACT FROM AUTHOR]

The determination of reject allowances for job shop set-ups usually considers defects to occur randomly through the production run. It is suggested that most defects arise during and just after the setting-up stage.
An analysis is conducted considering the setting-up stage as a learning process and incorporating the effects of additional set-ups. The analysis is extended to cover the effects of a single production station and a multi-station model, where rejects may occur at any station. The model was tested against a sample of actual jobs in a large manufacturing company. It was demonstrated that the station model using a skill and learning probability distribution was the more multi-adequate model, but experienced judgement achieved slightly better results than this model. [ABSTRACT FROM AUTHOR]

RFID application can improve operation performance in a supply chain by reducing or eliminating inventory misplacement and shrinkage. In this paper, we present a periodic review inventory model to investigate and characterize the multiperiod inventory control policies in both non-RFID and RFID cases when the firm encounters misplacement and shrinkage. The optimal inventory control policy is proved to be a two-control limit policy. The control limits in both the non-RFID case and the RFID case are analyzed and examined, while considering the impact of shrinkage and misplacement on inventory policies. A critical inventory level is determined to identify the relationship of higher inventory level control limits between the RFID case and the non-RFID case. An intensive numerical study with sensitivity analysis of selling price, misplacement rate, shrinkage rate, inventory recovery rate, and tag price is conducted. We find that when RFID technology is adopted, the inventory control policy in the RFID case is much more stable than that of the non-RFID case, as the misplaced inventory can be recovered perfectly and instantly for sale and the inventory shrinkage can be reduced by RFID technology. In addition, one of our intriguing findings is that when the shrinkage rate is below a threshold value which is independent of parameters, RFID application has no effect on inventory control policy if the misplaced inventory can be recovered in a timely manner by physical audit, which has not been revealed in previous studies. [ABSTRACT FROM AUTHOR]

The Poisson regression is very popular in applied researches when analyzing the count data. However, multicollinearity problem arises for the Poisson regression model when the independent variables are highly intercorrelated. Shrinkage estimator is a commonly applied solution to the general problem caused by multicollinearity. Recently, the ridge regression (RR) estimators and some methods for estimating the ridge parameterkin the Poisson regression have been proposed. It has been found that some estimators are better than the commonly used maximum-likelihood (ML) estimator and some other RR estimators. In this study, the modified Jackknifed Poisson ridge regression (MJPR) estimator is proposed to remedy the multicollinearity. A simulation study and a real data example are provided to evaluate the performance of estimators. Both mean-squared error and the percentage relative error are considered as the performance criteria. The simulation study and the real data example results show that the proposed MJPR method outperforms the Poisson ridge regression, Jackknifed Poisson ridge regression and the ML in all of the different situations evaluated in this paper. [ABSTRACT FROM AUTHOR]

In this paper, we consider the estimation problem of the parameter vector in the linear regression model with heteroscedastic errors. First, under heteroscedastic errors, we study the performance of shrinkage-type estimators and their performance as compared to theunrestricted and restricted least squares estimators. In order to accommodate the heteroscedastic structure, we generalize an identity which is useful in deriving the risk function. Thanks to the established identity, we prove that shrinkage estimators dominate the unrestricted estimator. Finally, we explore the performance of high-dimensional heteroscedastic regression estimator as compared to classical LASSO and shrinkage estimators. [ABSTRACT FROM AUTHOR]

A number of alternative mean-variance portfolio strategies have been recently proposed to improve the empirical performance of the classic Markowitz mean-variance framework. Designed as remedies for parameter uncertainty and estimation errors in portfolio selection problems, these alternative portfolio strategies deliver substantially better out-of-sample performance. In this article, we first show how to solve a general portfolio selection problem in a linear regression framework. Then we propose to reduce the estimation risk of expected returns and the variance-covariance matrix of asset returns by imposing additional constraints on the portfolio weights. With results from linear regression models, we show that portfolio weights derived from new approaches enjoy two favorable properties: sparsity and stability. Moreover, we present insights into these new approaches as well as their connections to alternative strategies in literature. Four empirical studies show that the proposed strategies have better out-of-sample performance and lower turnover than many other strategies, especially when the estimation risk is large. [ABSTRACT FROM PUBLISHER]

In order to reduce the maintenance costs of ballasted railway track and improve passenger comfort, the railway ballast particle breakage and its effect on track settlement need to be better understood. The failure process of individual railway ballast loaded between flat platens is simulated using the discrete element method, considering its irregular shape with the incorporation of parallel bonds. The tensile strength, the stress of a survival probability of 37% of samples, is obtained and compared with laboratory results from published literature for the verification of DEM simulations. The evolution to failure of the particle is understood from the stress-strain curve and progressive failure modes. The internal breakage mechanisms are analysed by tracking the accumulation of bond breakage number and the contact force distributions. [ABSTRACT FROM PUBLISHER]

The degradation of coal and the production of coal fines during handling and transport is a serious problem in processes that depend on closely sized large particles. To minimize the production of fines, a fundamental understanding of coal breakage is required, so, to clarify the complex nature of coal breakage, a series of experiments was conducted to determine the influence of the internal physical coal structures on compression breakage characteristics. The structures investigated are the cleat and layered structure of coal and the mineral inclusions. Samples of uniform size and shape were prepared from a large block of South African Waterberg coal. The samples were analyzed nondestructively using microfocus x-ray computed tomography then wrapped in cling film and mechanically compressed while the pressure applied was measured. The virtual three-dimensional volume tomograms of the initial sample and the progeny were compared and the changes qualitatively analyzed. Conclusions were drawn as to where the fatal cracks initialized and how the cracks propagated. Particle-size distributions were done to quantify the extent of breakage versus the breakage strength of the sample. It was found that, of all the internal structures, the inherent crack distribution has the biggest influence on breakage and breakage patterns of coal. [ABSTRACT FROM AUTHOR]

Cutting tool breakage detection is an important task, due to its economic impact on mass production lines in the automobile industry. This task presents a central limitation: real data-sets are extremely imbalanced because breakage occurs in very few cases compared with normal operation of the cutting process. In this paper, we present an analysis of different data-mining techniques applied to the detection of insert breakage in multitooth tools. The analysis applies only one experimental variable: the electrical power consumption of the tool drive. This restriction profiles real industrial conditions more accurately than other physical variables, such as acoustic or vibration signals, which are not so easily measured. Many efforts have been made to design a method that is able to identify breakages with a high degree of reliability within a short period of time. The solution is based on classifier ensembles for imbalanced data-sets. Classifier ensembles are combinations of classifiers, which in many situations are more accurate than individual classifiers. Six different base classifiers are tested: Decision Trees, Rules, Naïve Bayes, Nearest Neighbour, Multilayer Perceptrons and Logistic Regression. Three different balancing strategies are tested with each of the classifier ensembles and compared to their performance with the original data-set: Synthetic Minority Over-Sampling Technique (SMOTE), undersampling and a combination of SMOTE and undersampling. To identify the most suitable data-mining solution, Receiver Operating Characteristics (ROC) graph and Recall-precision graph are generated and discussed. The performance of logistic regression ensembles on the balanced data-set using the combination of SMOTE and undersampling turned out to be the most suitable technique. Finally a comparison using industrial performance measures is presented, which concludes that this technique is also more suited to this industrial problem than the other techniques presented in the bibliography. [ABSTRACT FROM PUBLISHER]

We study a discrete-time periodic-review inventory system where the unmet demand is lost, and the excess inventory is subject to shrinkage. We first derive the state evolution and then introduce unnormalized conditional probabilities to transform the nonlinear state evolution into a linear one. We then prove the existence and uniqueness of the solution for the Bellman equation in the case of unbounded costs and show that the solution yields the value function. [ABSTRACT FROM PUBLISHER]

We propose a flexible class of models based on scale mixture of uniform distributions to construct shrinkage priors for covariance matrix estimation. This new class of priors enjoys a number of advantages over the traditional scale mixture of normal priors, including its simplicity and flexibility in characterizing the prior density. We also exhibit a simple, easy to implement Gibbs sampler for posterior simulation, which leads to efficient estimation in high-dimensional problems. We first discuss the theory and computational details of this new approach and then extend the basic model to a new class of multivariate conditional autoregressive models for analyzing multivariate areal data. The proposed spatial model flexibly characterizes both the spatial and the outcome correlation structures at an appealing computational cost. Examples consisting of both synthetic and real-world data show the utility of this new framework in terms of robust estimation as well as improved predictive performance. Supplementary materials are available online. [ABSTRACT FROM AUTHOR]

Since around 2000, there has been extensive research on questions regarding shrinkage and urban renewal in Germany after a task force report revealed approximately 1.4 million vacant flats in East Germany. Since then, most towns and cities have been labelled “shrinking cities” there. While from a planning perspective urban decline and also shrinking cities are widely studied phenomena throughout the industrialized world and a substantial literature exists on the phenomenon in Germany, the impact of political debates and normative considerations is under-researched. This paper highlights the role of political–normative ideas of metropolization and societal relations within this complex core–periphery process, elaborating on the concept of peripheralization and calling for further research. [ABSTRACT FROM AUTHOR]

Micronization and nanoparticle production of poorly water-soluble drugs was investigated using single wet milling equipment operating in the attritor and stirred media modes. The drug particles in the median size range of 0.2--2 µµm were prepared by changing the milling mode and operating conditions of a Micros mill with a purpose of elucidating the dynamics of the wet milling process. It was determined that particle breakage due to mechanical stresses and aggregation due to insufficient stabilization are two competing mechanisms which together control the wet milling dynamics of the poorly water-soluble drugs. The study in the attritor mode using four different classes of stabilizers with six drugs indicated that steric stabilization worked better than electrostatic stabilization for the drugs studied. In addition, the existence of different minimum polymer concentrations for the stabilization of microsuspensions and nanosuspensions was indicated. The major role of a non-ionic polymer during the production of fine particles is its stabilization action through steric effects, and no experimental evidence was found to support the so-called Rehbinder effect. Periodic addition of the polymer as opposed to the addition of the polymer at the start of milling process was introduced as a novel processing method. This novel method of polymer addition provided effective stabilization and breakage of drug particles leading to a narrower and finer particle size distribution. Alternatively, it may allow shorter processing time and lower overall power consumption of the milling process for a desired particle size. [ABSTRACT FROM AUTHOR]

In this paper, a series of laboratory tests on shrinkage of plaster materials are presented. The plaster materials consist of cohesive soil, sand and different natural fibres. Three types of fibres, wheat straw, barley straw and wood shavings, were used as reinforcement in the tests. The shrinkage behaviour of earth plasters was studied by laboratory tests for different compositions and under different curing conditions. The specimens of plaster material were dried under a constant temperature of 30, 50 and 70°C, respectively. The effect of the following factors on shrinkage was investigated: temperature, soil composition, fibre type and fibre content. It was established that shrinkage crack formation decreases with increasing fibre content and increases with increasing soil content. In general, it was also found that lower curing temperature and higher fibre content are to be preferred to improve the performance of earth plasters. [ABSTRACT FROM AUTHOR]

This paper analyses and compares two probabilistic models described in the literature concerning pipe breakage in a water distribution system. The first model was proposed by Mailhot et al. (Mailhot, A., et al., 2000. Modeling the evolution of the structural state of water pipe networks with brief recorded pipe break histories: methodology and application. Water Resources Research, 36 (10), 3053-3062), whereas the second was proposed by Le Gat and Eisenbeis (Le Gat, Y. and Eisenbeis, P., 2000. Using maintenance record to forecast future failures in water networks. Urban Water, 2, 173-181). Both models are presented by the respective authors as being parameterisable even using data relating to a time window that is not very broad; they were thus applied to a case study on the water distribution system serving the western part of the province of Ferrara, for which the available breakage data cover a time span of nearly 7 years and comprise a total of around 3500 breakages. This data sample is one of the richest and most complete in Italy. A preliminary statistical analysis of these data and of the main characteristics of the transmission and distribution system resulted in the selection of two different parameterisation approaches for the two models, in which the data are stratified, respectively, according to materials and the periods in which the pipes were laid. With each of the two models, tests were then carried out to assess (a) their ability to reproduce, in a probabilistic sense, the number of breakages and the number of broken pipes recorded over the observation time window; (b) how they behave in forecasting the number of breakages in the years following the observation period; and (c) how they behave in quantifying the benefits to be derived, in terms of reducing breakages, from the planning of pipe rehabilitation initiatives. An analysis of the results of these tests showed that the two models perform similarly in modelling the number of breakages and the number of broken pipes recorded during the observation period. However, as regards their behaviour in forecasting the number of future breakages and in quantifying the benefits to be derived from rehabilitation, the model proposed by Le Gat and Eisenbeis (2000) appears to be more reliable and less sensitive to the type of data stratification than the model proposed by Mailhot et al. (2000). This is due to the structure of the model of Le Gat and Eisenbeis (2000), which enables optimal exploitation of the abundant information available for a large-sized water distribution system, including diameters, lengths, etc., whereas the model proposed by Mailhot et al. (2000) does not use this type of information and takes into account solely the pipe installation period. [ABSTRACT FROM AUTHOR]

In a large retail chain, we used statistical regression to relate shrinkage to explanatory variables such as staffing, security, store layout and catchment-area demographics. There were large measurement errors in the retailer's estimates of shrinkage, together with high correlations among the potential causal variables. These effects caused our models to give poor predictions of shrinkage for individual stores, but the models were highly statistically significant, which means that they can accurately forecast the average (and hence the aggregate) effects of policy changes affecting hundreds of stores. Factors associated with lower shrinkage included high turnover of stock, and high densities on the sales floor of staff, pay-points and customers. Our results suggest that crowding among staff and customers may be a more effective inhibitor of shrinkage than many traditional formal security precautions, such as CCTV and store detectives. [ABSTRACT FROM AUTHOR]

In this research the effect of breakage—the rounding down of payoffs to winning bets—on the measured efficiency of racetrack betting markets is examined empirically. Over twenty thousand horse races are analysed and it is demonstrated that evidence of betting market inefficiency is systematically related to the expected breakage. These empirical results suggest that failure to control for breakage may bias statistical tests towards rejection of the efficiency hypothesis. [ABSTRACT FROM AUTHOR]

Fibre withdrawal at high speeds is very common in fibre-opening processes such as carding. Understanding the effect of the withdrawal speed on the fibre-withdrawal force is of importance in improving the process productivity while controlling the level of associated fibre breakages. In this work, high-speed fibre-withdrawal forces were measured during a simulated carding process by using high-speed computer-data-acquisition techniques. There was no significant effect of withdrawal speed (up to 8 m/s) on the withdrawal-force level, and no fibre breakage occurred when the withdrawn fibre was not entangled. However, the configuration of the fibre assembly, particularly its degree of entanglement, plays an important role in determining the pattern and level of withdrawal forces. The peak withdrawal forces were found to increase with an increase in the fibre-pin contact angles and fibre-assembly density. [ABSTRACT FROM AUTHOR]

An investigation is reported in which the shrink-resistance of wool treated by exhaustion with Synthappret BAP and magnesium chloride was improved by the introduction of a strongly alkaline treatment immediately before or after the polymer-application step. The greatest improvements were observed with pre-treatments at around pH 11 or with after-treatments at around pH 10. After-treatments gave a greater improvement. The improved shrink-resistance was attributed to the promotion by alkali (in the bath, or carried over on the fibres) of reactions of the carbamoyl sulphonate groups in Synthappret BAP with themselves (cross-linking) or with the fibre. Alkaline pre-treatments were considered to be more practical than after-treatments. They could be simply incorporated into the normal Synthappret BAP-magnesium chloride exhaustion-processing sequence by a change from a neutral or mildly alkaline scour with non-ionic detergents to a preliminary scour with sodium carbonate or metasilicate solution at pH 11. Alkaline pre- and after-treatments were examined with a range of other exhaustion shrink-resist finishes for wool based on polymers the only other case to show improved shrink-resistance was the batch Hercosett 125 treatment of chlorinated wool, and that only at low chlorination levels. In a comparison of a selection of exhaustion shrink-resist treatments on untreated wool, the most effective (for the amount of polymer applied) on the fabrics studied was Synthappret BAP-magnesium chloride coupled with an alkaline after-treatment. [ABSTRACT FROM AUTHOR]