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This study examines Einstein's field equations in the context of general relativity, comparing five distinct methodologies: (a) vanishing complexity, (b) embedding class one or the Karmarkar condition, (c) conformally flat spacetime, (d) conformal killing symmetry, and (e) the Karmarkar scalar condition. The first four methods reveal a significant connection between two metric potentials, while the fifth method provides a coordinate-independent condition expressed in terms of structural scalars. The paper provides a comprehensive comparative analysis of a new exact solution derived by assuming a common metric function and solving the remaining metric functions through corresponding bridge equations to evaluate their effectiveness and validity. Critical parameters such as thermodynamic factors, causality conditions, stability, and mass function analysis are investigated. [ABSTRACT FROM AUTHOR]

In this paper, a multiproduct multiperiod capacitated production system that has been organized as a flow shop is considered. The main novelty of the paper is proposing a more efficient mathematical model for the problem of integrating lot sizing and scheduling with sequence-dependent setups. In comparison to the former model, because of fewer continuous and binary decision variables and constraints in the proposed model, this model is very easier to solve. Comparison between two models proves the superiority of the proposed model. Two mixed integer programming-based approaches with rolling horizon framework have been used to solve this model. To evaluate the performance of the proposed model and solution method, problems of different scales have been studied. The used algorithms search the solution space for both lot-sizing and scheduling problems and find a combination of production planning and scheduling that is feasible and close to optimum. [ABSTRACT FROM AUTHOR]

This paper develops a new mathematical model and proposes two meta-heuristics for solving a two-machine flowshop scheduling problem that minimizes bi-objectives, namely the total idle time and the mean deviation from a common due data. In this paper, we assume the arrival time of jobs is dynamic, in which each job has a time window and can arrive in its time window randomly. We also assume the learning effect on the processing times considering as a position-dependent effect. Since the problem is an NP-hard one, we present a multiobjective genetic algorithm (MOGA) and a multiobjective simulated annealing (MOSA) algorithm to solve the given problems. The computational results confirm that the proposed MOGA has a better solution in comparison with the proposed MOSA, especially in large-sized problems. [ABSTRACT FROM AUTHOR]

No-wait job shop scheduling problems refer to the set of problems in which a number of jobs are available for processing on a number of machines in a job shop context with the added constraint that there should be no waiting time between consecutive operations of the jobs. In this paper, a two-machine, no-wait job shop problem with separable setup times and a single-server constraint is considered. The considered performance measure is the makespan. This problem is strongly NP-hard. A mathematical model of the problem is developed and a number of propositions are proven for the special cases. Moreover, a genetic algorithm is proposed in this paper to find the optimal (or near-optimal) solutions. In order to evaluate the developed algorithm, a number of small instances are solved to optimality using the developed mathematical model. The proposed algorithm is able to find the optimal solution of all of these cases. For larger instances, the developed algorithm has been compared with the 2-opt algorithm as well as a proposed lower bound. Computational results show the efficiency of the proposed algorithm in generating good quality solutions compared to the developed lower bounds and 2-opt algorithm. [ABSTRACT FROM AUTHOR]

Data envelopment analysis (DEA) is an important managerial tool for evaluating and improving the performance of decision making units. The existing DEA models are mostly limited to static environment using crisp data and are time-consuming and also have weak discriminating power. The aim of this work is to introduce a new fuzzy dynamic DEA model with missing values, which benefits from strengths of multi-objective modeling to overcome weakness and drawbacks of the classic DEA models. To check for quality and accuracy of the proposed model, this paper offers a comparative study to compare the discriminating power and computational efforts of the model with two problems in the literature taken as benchmarks. Also, this paper presents a real application of the fuzzy dynamic DEA model for assessing and ranking the level of performance for 56 railways around the globe using real data gathered from credible sources. The numerical case illustrates the model and the result may be used by railways to improve their performance efficiency compared to the best in the sample. Results for the comparative study and the real case reveal significant improvement in computational time and discriminating power. [ABSTRACT FROM AUTHOR]

In this paper, we used a 3-D discrete-element model, Grains3D, which allows the simulation of unsteady granular flows of monodisperse soft spherical particles in a common situation (i.e., down a rectangular channel). A series of numerical dam-break experiments was performed to predict the behavior of granular columns that propagate down a rough horizontal surface from different initial conditions (varying the initial aspect ratio). Numerical results were compared to those obtained experimentally by Lajeunesse et al. (Phys Fluids 17:103302, ) from a similar configuration. Runout distance, temporal flow evolution, deposit morphology and internal flow structures of similar laboratory experiments were quantitatively reproduced as well as prediction of empirical and theoretical scaling laws. This paper highlights that such fully 3-D simulations of soft-spheres can remarkably capture dam-break collapses performed in a rectangular channel. Moreover, Grains3D can provide a complete physical description of such complex unsteady systems which will be the topic of future on-going studies. [ABSTRACT FROM AUTHOR]

This paper addresses two seeming paradoxes in the realm of employer-provided health insurance: First, businesses consistently claim that they bear the burden of the insurance they provide for employees, despite theory and empirical evidence indicating that workers bear the full incidence. Second, benefit generosity and the percentage of premiums paid by employers have decreased in recent decades, despite the preferential tax treatment of employer-paid benefits relative to wages-trends unexplained by the standard incidence model. This paper offers a revised incidence model based on nominal wage rigidity, in an attempt to explain these paradoxes. The model predicts that when the nominal wage constraint binds, some of the burden of increasing insurance premiums will fall on firms, particularly small companies with low-wage employees. In response, firms will reduce employment, decrease benefit generosity, and require larger employee premium contributions. Using Current Population Survey data from 2000-2001, I find evidence for this kind of wage rigidity and its associated impact on the employment and premium contributions of low-wage insured workers during a period of rapid premium growth. [ABSTRACT FROM AUTHOR]

By restricting the number of age groups to two and by introducing continued fractions, the dynamics of populations with deterministically changing vital rates are completely specified at all times. Explicit expressions for the sequence of the product of population projection matrices are given. From these, relative age distribution and reproductive values to any desired accuracy are obtained as functions of the vital rates. Thus, the results given in this paper are stronger than any existing weak ergodic theorems. [ABSTRACT FROM AUTHOR]

Introduction: The efficiency of The International Classification of Headache Disorders (ICHD-3) in reflecting patients' disability has recently been questioned. This prompts consideration that clinical features beyond pain may more accurately indicate the extent of underlying brain impairment than the mere frequency of headache days. Important cognitive dysfunctions and psychological impairment have been reported in burdensome cases of migraine, and the presence of these alterations has been associated with biological changes in the nervous system. This study aimed to compare migraine-related disability within a specific patient group, classified using ICHD-3 criteria or classified based on findings from a neuropsychological evaluation using machine learning. Additionally, a complementary voxel-based morphometry (VBM) comparison was conducted to explore potential neuroanatomical differences between the resulting groups. Patients and methods: The study included episodic and chronic migraine patients seeking consultation at a specialized headache department. A neuropsychological evaluation protocol, encompassing validated standardized tests for cognition, anxiety, depression, perceived stress, and headache-related impact (HIT-6) and disability (MIDAS), was administered. Results from this evaluation were input into an automated K-means clustering algorithm, with a predefined K=2 for comparative purposes. A supplementary Voxel-based Morphometry (VBM) evaluation was conducted to investigate neuroanatomical contrasts between the two distinct grouping configurations. Results: The study involved 111 participants, with 49 having chronic migraine and 62 having episodic migraine. Seventy-four patients were assigned to cluster one, and 37 patients were assigned to cluster two. Cluster two exhibited significantly higher levels of depression, anxiety, and perceived stress, and performed worse in alternating and focalized attention tests. Differences in HIT-6 and MIDAS scores between episodic and chronic migraine patients did not reach statistical significance (HIT-6: 64.39 (±7,31) vs 62.92 (±11,61); p= 0. 42 / MIDAS: 73.63 (±68,61) vs 84.33 (±63,62); p=0.40). In contrast, patients in cluster two exhibited significantly higher HIT-6 (62.32 (±10,11) vs 66.57 (±7,21); p=0.03) and MIDAS (68.69 (±62,58) vs 97.68 (±70,31); p=0.03) scores than patients in cluster one. Furthermore, significant differences in grey matter volume between the two clusters were noted, particularly involving the precuneus, while differences between chronic and episodic migraine patients did not withstand correction for multiple comparisons. Conclusions: The classification of migraine patients based on neuropsychological characteristics demonstrates a more effective separation of groups in terms of disability compared to categorizing them based on the chronic or episodic diagnosis of ICHD-3. These findings could reveal biological changes that might explain differences in treatment responses among apparently similar patients. [ABSTRACT FROM AUTHOR]

Parkinson's disease (PD) and essential tremor (ET) are prevalent movement disorders that mainly affect elderly people, presenting diagnostic challenges due to shared clinical features. While both disorders exhibit distinct speech patterns—hypokinetic dysarthria in PD and hyperkinetic dysarthria in ET—the efficacy of speech assessment for differentiation remains unexplored. Developing technology for automatic discrimination could enable early diagnosis and continuous monitoring. However, the lack of data for investigating speech behavior in these patients has inhibited the development of a framework for diagnostic support. In addition, phonetic variability across languages poses practical challenges in establishing a universal speech assessment system. Therefore, it is necessary to develop models robust to the phonetic variability present in different languages worldwide. We propose a method based on Gaussian mixture models to assess domain adaptation from models trained in German and Spanish to classify PD and ET patients in Czech. We modeled three different speech dimensions: articulation, phonation, and prosody and evaluated the models' performance in both bi-class and tri-class classification scenarios (with the addition of healthy controls). Our results show that a fusion of the three speech dimensions achieved optimal results in binary classification, with accuracies up to 81.4 and 86.2% for monologue and /pa-ta-ka/ tasks, respectively. In tri-class scenarios, incorporating healthy speech signals resulted in accuracies of 63.3 and 71.6% for monologue and /pa-ta-ka/ tasks, respectively. Our findings suggest that automated speech analysis, combined with machine learning is robust, accurate, and can be adapted to different languages to distinguish between PD and ET patients. [ABSTRACT FROM AUTHOR]

In unsupervised classification, kernel k-means clustering method has been shown to perform better than conventional k-means clustering method in identifying non-isotropic clusters in a data set. The space and time requirements of this method are O( n), where n is the data set size. Because of this quadratic time complexity, the kernel k-means method is not applicable to work with large data sets. The paper proposes a simple and faster version of the kernel k-means clustering method, called single pass kernel k -means clustering method. The proposed method works as follows. First, a random sample $\mathcal{S}$ is selected from the data set $\mathcal{D}$. A partition $\Pi_{\mathcal{S}}$ is obtained by applying the conventional kernel k-means method on the random sample $\mathcal{S}$. The novelty of the paper is, for each cluster in $\Pi_{\mathcal{S}}$, the exact cluster center in the input space is obtained using the gradient descent approach. Finally, each unsampled pattern is assigned to its closest exact cluster center to get a partition of the entire data set. The proposed method needs to scan the data set only once and it is much faster than the conventional kernel k-means method. The time complexity of this method is O( s + t + nk) where s is the size of the random sample $\mathcal{S}$, k is the number of clusters required, and t is the time taken by the gradient descent method (to find exact cluster centers). The space complexity of the method is O( s). The proposed method can be easily implemented and is suitable for large data sets, like those in data mining applications. Experimental results show that, with a small loss of quality, the proposed method can significantly reduce the time taken than the conventional kernel k-means clustering method. The proposed method is also compared with other recent similar methods. [ABSTRACT FROM AUTHOR]

In this article, different approaches of the use of black box modelling techniques for piezoelectric actuators are particularly addressed, regardless of the employed technique/algorithm. A modelling approach in this paper refers to two matters: the first, the role of black box techniques in modelling (i.e. if physics-based techniques are also involved in modelling; if so, how and to what extent). From this aspect, the spectrum of approaches ranges from those merged with/inspired by classical phenomenological models to an approach based on purely system identification-based techniques. The second aspect of modelling approaches, in this article, is the input variables to the model. Current and previous values of input voltage, previous values of the output (displacement), derivatives and extremum values of the system's input/output have been used as the inputs to the model so far. Both aforementioned aspects of modelling approaches are addressed appropriately in this article, and various modelling approaches in the literature are categorized and presented in a uniform and comparable manner, so that readers can easily identify research trends in this area and the gaps in the literature. One of the identified unanswered questions in the literature is whether the extremum values of the system's input/output should/should not be used as an input to black box models of piezoelectric actuators. There are works in the literature which have/have not used the aforementioned input variables, but there is no published investigation to evidently answer the proposed question. This article, in the last section, answers this question by reporting and discussing an experimental study. [ABSTRACT FROM AUTHOR]

This paper deals with hybrid flow shop scheduling problems considering time lags and sequence-dependent setup times which have wide application in real-world problems. Most of the researches on operations scheduling problems have ignored time lags. A mathematical model is presented which is capable of solving the small size of the considered problem in a reasonable time. Since these problems are strongly NP-hard, a meta-heuristic algorithm based on the immune algorithm is developed. The optimization criterion considered in this paper is the minimization of the makespan. Numerical experiments are used to evaluate the performance and effectiveness of the proposed algorithm. The results of the proposed algorithm are compared with the presented mathematical programming model and a benchmark algorithm. Computational results indicate that the proposed algorithm can produce near-optimal solutions in a short computational time. Moreover, it can be applied easily in real factory conditions and for large-sized problems. [ABSTRACT FROM AUTHOR]

It is widely believed that structural variables such as inequitable land distribution, lack of rural employment opportunities, and rural-urban wage and amenity gaps influence population movements in developing countries. Yet quantitative evidence is scant. In this paper a multilevel model is used to investigate the effects of individual-, household-, and areal-level factors on rural-urban out-migration in the Ecuadorian Sierra. Data from a detailed survey carried out in 1977-1978 and from government macro-areal statistics are used to investigate factors affecting the out-migration of youths aged 12-25. Preliminary conclusions are presented on the usefulness of multilevel models in studying migration and policy implications for Ecuador. [ABSTRACT FROM AUTHOR]

In this paper we develop and test a theory of childhood mortality after the first month of life. Parents are assumed to have well-defined family size and sex composition objectives and to face severe budget constraints. In this set of circumstances, it is understandable that they will make allocative decisions that will affect the survival probabilities of children. These decisions and the environmental influences on mortality are the basic forces which determine whether a child will survive through the post-neonatal period. The model is tested with survey data from rural Uttar Pradesh, India. The results are consistent with the hypothetical framework discussed above. The burden of this pattern of choice is felt particularly strongly by female births. [ABSTRACT FROM AUTHOR]

This paper analyzes cross-cohort trends in the age pattern of women at first birth in the United States. The analysis involves fitting the Coale-McNeil marriage model to the age distribution of first birth frequencies for a number of recent white and nonwhite cohorts. Methodologically, the results (a) provide support for the application of the Coale-McNeil marriage model to first birth data, and (b) demonstrate the ability of the model to accurately project first birth fertility for cohorts which have yet to complete their childbearing years. Substantively the results indicate (a) that the proportion of women who will never have a first birth is increasing across cohorts and can be expected to be as high as .25 and .20 for recent white and nonwhite cohorts respectively; (b) that recent nonwhite cohorts have an appreciable number of first births at earlier ages than their white counterparts, as well as a lower mean age at first birth and increasingly less dispersion (across cohorts) in their age at first birth; and (c) that the mean age at first birth and the proportion of first births occurring between ages 25 and 34 is increasing across cohorts of white women but is stable across cohorts of nonwhite women. [ABSTRACT FROM AUTHOR]

This paper is part of a long-term investigation known as the Mormon Historical Demography Project. It examines the capability of a simulation model, originally proposed by John Bongaarts (1976), to fit the natural fertility pattern which characterized the mid-nineteenth century Mormon population. Application of this model permits estimates to be made of the historical timing and age-incidence of fertility limitation. A sensitivity analysis of the model's parameters demonstrates that simple changes in the model's proximate determinants of fertility, excluding contraceptive practices, would be insufficient to account for later transition effects. Thus the results successfully capture the dynamics underlying the Mormon natural fertility pattern as well as offer a framework for future modeling of the transition away from natural fertility. [ABSTRACT FROM AUTHOR]

This paper introduces an analytic framework that can be used to assess the relationships between individual movement differentials and place characteristics, on the one hand, and aggregate mobility levels and city-suburb population change (in size or composition), on the other. Application of this framework using census data for individual metropolitan areas allows the analyst to decompose population changes due to net migration into contributing mobility streams and their component rates which are subject to unique community and individual influences. The paper provides both theoretical and empirical rationale for the framework, illustrates its use with 1970 census data, and discusses its implications for empirical research on city-suburb population redistribution. [ABSTRACT FROM AUTHOR]

In this paper, the actuarial method of multiple decrement life table analysis of censored, longitudinal data is examined. The discussion is organized in terms of the first segment of usage of an intrauterine device. Weaknesses of the actuarial approach are pointed out, and an alternative approach, based on the classical model of competing risks, is proposed. Finally, the actuarial and the alternative method of analyzing censored data are compared, using data from the Taichung Medical Study on Intrauterine Devices. [ABSTRACT FROM AUTHOR]

A population consisting of women who have conceived before a time t ignores all women whose conception time exceeds t. Such a population is considered as a truncated population, and the samples are called truncated samples. Under the assumption that fecundability among women varies according to a Beta distribution (with parameters a and b), the distribution of conception times in a truncated population can be considered as truncated Type I geometric. This paper presents an algorithm to obtain the moment and maximum likelihood estimates of a and b from the truncated samples. Large sample properties of the estimators are also studied. Examples using the Hutterite and the Princeton Fertility Survey data are given. [ABSTRACT FROM AUTHOR]

Background: Patient complexity is often operationalized by counting multiple chronic conditions (MCC) without considering contextual factors that can affect patient risk for adverse outcomes.Objective: Our objective was to develop a conceptual model of complexity addressing gaps identified in a review of published conceptual models.Data Sources: We searched for English-language MEDLINE papers published between 1 January 2004 and 16 January 2014. Two reviewers independently evaluated abstracts and all authors contributed to the development of the conceptual model in an iterative process.Results: From 1606 identified abstracts, six conceptual models were selected. One additional model was identified through reference review. Each model had strengths, but several constructs were not fully considered: 1) contextual factors; 2) dynamics of complexity; 3) patients' preferences; 4) acute health shocks; and 5) resilience. Our Cycle of Complexity model illustrates relationships between acute shocks and medical events, healthcare access and utilization, workload and capacity, and patient preferences in the context of interpersonal, organizational, and community factors.Conclusions/implications: This model may inform studies on the etiology of and changes in complexity, the relationship between complexity and patient outcomes, and intervention development to improve modifiable elements of complex patients. [ABSTRACT FROM AUTHOR]

Background/objectives: Insects have been the subject of recent attention as a potentially environmentally sustainable and nutritious alternative to traditional protein sources. The purpose of this paper is to test the hypothesis that insects are nutritionally preferable to meat, using two evaluative tools that are designed to combat over- and under-nutrition. Subjects/methods: We selected 183 datalines of publicly available data on the nutrient composition of raw cuts and offal of three commonly consumed meats (beef, pork and chicken), and six commercially available insect species, for energy and 12 relevant nutrients. We applied two nutrient profiling tools to this data: The Ofcom model, which is used in the United Kingdom, and the Nutrient Value Score (NVS), which has been used in East Africa. We compared the median nutrient profile scores of different insect species and meat types using non-parametric tests and applied Bonferroni adjustments to assess for statistical significance in differences. Results: Insect nutritional composition showed high diversity between species. According to the Ofcom model, no insects were significantly 'healthier' than meat products. The NVS assigned crickets, palm weevil larvae and mealworm a significantly healthier score than beef (P<0.001) and chicken (P<0.001). No insects were statistically less healthy than meat. Conclusions: Insect nutritional composition is highly diverse in comparison with commonly consumed meats. The food category 'insects' contains some foods that could potentially exacerbate diet-related public health problems related to over-nutrition, but may be effective in combating under-nutrition. [ABSTRACT FROM AUTHOR]

In this paper, we present some distributional properties of the survival and frailty distribution involved in the proportional odds (PO) frailty model. Stochastic orderings are studied for this proportional odds frailty model. It is showed that negative dependence arises in the PO frailty model as opposed to the proportional hazard frailty model. [ABSTRACT FROM AUTHOR]

This paper presents a new hybrid method for continuous Arabic speech recognition based on triphones modelling. To do this, we apply Support Vectors Machine (SVM) as an estimator of posterior probabilities within the Hidden Markov Models (HMM) standards. In this work, we describe a new approach of categorising Arabic vowels to long and short vowels to be applied on the labeling phase of speech signals. Using this new labeling method, we deduce that SVM/HMM hybrid model is more efficient then HMMs standards and the hybrid system Multi-Layer Perceptron (MLP) with HMM. The obtained results for the Arabic speech recognition system based on triphones are 64.68 % with HMMs, 72.39 % with MLP/HMM and 74.01 % for SVM/HMM hybrid model. The WER obtained for the recognition of continuous speech by the three systems proves the performance of SVM/HMM by obtaining the lowest average for 4 tested speakers 11.42 %. [ABSTRACT FROM AUTHOR]

Fluid viscous dampers are extensively adopted as efficient and cheap energy dissipation devices in structural seismic protection. If we consider the usefulness of these passive control devices, the exact recognition of their mechanical behavior is of outstanding importance to provide a reliable support to design a very efficient protection strategy. In scientific and technical applications, many different constitutive models have been proposed and adopted till now to represent fluid viscous dampers, with different levels of complexity and accuracy. This paper focuses on parameter identification of fluid viscous dampers, comparing different existing literature models, with the aim to recognize the ability of these models to match experimental loops under different test specimens. The identification scheme is developed evaluating the experimental and the analytical values of the forces experienced by the device under investigation. The experimental force is recorded during the dynamic test, while the analytical one is obtained by applying a displacement time history to the candidate mechanical law. The identification procedure furnishes the device mechanical parameters by minimizing a suitable objective function, which represents a measure of the difference between the analytical and experimental forces. To solve the optimization problem, the particle swarm optimization is adopted, and the results obtained under various test conditions are shown. Some considerations about the agreement of different models with experimental data are furnished, and the sensitivity of identified parameters of analyzed models against the frequency excitation is evaluated and discussed. [ABSTRACT FROM AUTHOR]

An attempt is made in this paper to find out the analytical solution of the thermal field induced in a semi-infinite body by a moving heat source with Gaussian distribution by selecting appropriate inside volume for submerged arc welding process. Three different types of heat source shapes in the form of oval, double ellipsoidal, and conical forms were considered and compared with the experimental result. The study shows that for heat input of submerged arc welding process, the best suitable heat source shape is in the form of an oval. The study also shows two alternate ways of predicting the size of the heat-affected zone. [ABSTRACT FROM AUTHOR]

Ball burnishing is a surface enhancement process where a residual compressive stress is created in the surface layers of the workpiece. Several studies have been conducted on this process, but they are more concerned with the experimental aspect. So, there is still a real need for reliable numerical models that enable us to understand the mechanical behaviour of the workpiece during the process. These models also serve to optimise the studied process. Two-dimensional and three-dimensional finite element (FE) ball burnishing modelling is presented in this paper, where an elastic-plastic material model is assumed in the framework of the FE analysis. The pertinence of these models to predict residual stresses created by the process is discussed by drawing comparisons between simulation results and experimental data. The obtained results show that the three-dimensional FE model predicts the residual stresses and provides useful information on the effect of the process parameters. [ABSTRACT FROM AUTHOR]

Multiple-route job shop scheduling problem (MRJSP) is a generalization of job shop scheduling problem in which each job may have more than one route for its production and the numbers of operations associated to the alternative routes of the job are not necessarily equal. MRJSP is recognized to be extremely difficult because of its combinatorial nature of integer optimization and the large size of the real problem, necessitating the use of heuristic approaches or dispatching rules for its solution. In this paper, mathematical formulation of MRJSP is first presented. Then, a two-phase algorithm is proposed to deal with the two major sub-problems in MRJSP, namely, the route selection and the sequencing sub-problems. In order to evaluate the effectiveness of the proposed algorithm, several problems (in small, medium, and large sizes) are designed and solved using the proposed algorithm. The problems are also solved using some other dispatching rules, and comparisons are provided. The computational results show that the proposed algorithm generates high-quality schedules in a timely fashion. [ABSTRACT FROM AUTHOR]

This paper analyses different objective functions for the parameter identification of parallel mechanisms and studies the influence in the position and orientation errors to improve their accuracy. A new objective function considering deviation terms is presented. This function is compared with other widely used functions and the advantages and disadvantages of each function are presented. The geometric parameter identification is performed by external calibration by means of the direct kinematic model. First, the objective functions are defined considering error position, error orientation and deviations in measurement. These functions compare the measured and calculated moving platform coordinates in order to obtain the identified model parameters that minimize this difference. The measured coordinates are obtained by measuring three sphere centres, fixed to the moving platform of a parallel mechanism, and the computed coordinates are given by the kinematic model. Second, the model is solved by the Levenberg-Marquardt algorithm for a number of identification positions. Finally, the calibration is verified in test positions. The results obtained show that the consideration of the deviations in measurement in the objective function with respect to classical approaches allows us to better identify those kinematic parameters corresponding with passive joints that cannot be measured. These findings confirm that a suitable objective function can improve the mechanism accuracy by more than one order of magnitude in both position and orientation errors. [ABSTRACT FROM AUTHOR]

This paper presents a novel fuzzy possibilistic bi-objective model for a hub covering location-allocation problem with specific features. Considering two major objectives is the main novelty of this problem, comparing to the previous studies. The first objective is to minimize the total costs consisting of (1) covering costs, (2) transportation costs, (3) opening costs of facilities in hubs, (4) reopening costs of facilities in hubs, (5) activating costs of facilities in hubs, and (6) transporters purchasing costs. The second objective is to minimize the sum of the times of shipping commodities by transporters from the origin node to the destination node via hubs. Furthermore, to come closer to reality, the main parameters of the proposed mathematical model are regarded as fuzzy ones. To solve the proposed multi-objective model, four recent approaches are used and the results are compared with each other. [ABSTRACT FROM AUTHOR]

In this paper, we develop an integrated inventory model for vendor-buyer coordination under an imperfect production process. The proportion of defective items in each production lot is assumed to be stochastic and follows a known probability density function. The vendor inspects the items while they are being produced and delivers good-quality items to the buyer in small lots over multiple shipments. We assume that shortages are permitted and are completely backordered. The expected annual integrated total cost is derived and a solution procedure is provided to find the optimal solution. Numerical examples show that the integrated model gives an impressive cost reduction in comparison to an independent decision by the buyer. The results also show that if back orders are permitted, the expected integrated annual cost is less than that when back orders are not permitted. Therefore, if customers are willing to wait for the next shipment when a shortage occurs, it is profitable for the company to allow back orders although the delay incurs a penalty cost. [ABSTRACT FROM AUTHOR]

This paper addresses the multiple-route job shop scheduling problem to minimize makespan. The problem is recognized to be extremely difficult because of its combinatorial nature of integer optimization and the large size of the real problem. The goal is, thus, to obtain near-optimal schedules in a computationally efficient manner. Mathematical formulation of the problem is first presented. Then, an approach based on artificial immune algorithm is proposed. In order to evaluate the effectiveness of the proposed approach, 30 problems in small, medium, and large size are designed and solved using the proposed approach. Problems are also solved using Lingo software and the results are compared. The computational results show that the proposed approach generates high-quality schedules in a timely fashion. [ABSTRACT FROM AUTHOR]

This scientific paper proposes an analytic framework specifically for Rabindrasangeet singing that models the time-varying physical and expressive characteristics unique to an individual voice through a phonetogram analysis. The present study incorporates the most popular Rabindrasangeet into account for analysis to get an idea about the specific numerical data regarding the fundamental frequency, semitones, SPL range, and area as well as to give a precise guideline to those clients. While comparing the trained and untrained singers both males and females the FO parameter is found to be louder in trained group. The mean semitone is always higher in females than in males and the trained male subjects have significantly higher SPL range than trained female subjects and trained females have higher SPL range than untrained female subjects. The enclosed area is larger in trained singers and more in females than males. Results of this study indicate differences between untrained and trained phonetograms. These differences can be attributed to greater natural capacities in trained subjects or a superior learned control over the voice mechanism. [ABSTRACT FROM AUTHOR]

One fundamental problem in cellular manufacturing is the formation of product families and machine cells. Many solution methods have been developed for the cell formation problem. Since efficient grouping is the prerequisite of a successful Cellular Manufacturing installation the research in this area will likely be continued. In this paper, we consider the problem of cell formation in cellular manufacturing systems with the objective of maximizing the grouping efficacy. We propose a Genetic Algorithm (GA) to obtain machine-cells and part-families. Developed GA has three different selection and crossover operators. The proper operators and parameters of the GA were determined by design of experiments. A set of 15 test problems with various sizes drawn from the literature is used to test the performance of the proposed algorithm. The corresponding results are compared to several well-known algorithms published. The comparative study shows that the proposed GA improves the grouping efficacy for 40% of the test problems. [ABSTRACT FROM AUTHOR]

Regression analysis is one of the most applicable methods in statistical methodology used to find the best regression model according to the relationship among several variables in a system. The estimation of regression model, which is solved as a formulate optimization problem and making use of heuristic algorithms, is much simpler and faster than classic methods. Genetic algorithm (GA) as one of the heuristic algorithms had been used to solve this problem. In this paper, we extend the noising method as a recent combinatorial optimization problem to estimate the best regression model and evaluate its performances compared to GA. Also, in order to enhance the performance of our GA, we apply the Taguchi experimental design method to tune the parameters of the algorithm. [ABSTRACT FROM AUTHOR]

The aim of this paper is to simulate the nonlinear wave propagation in granular chains of beads using a recently introduced multiple impact model and to compare numerical results to experimental ones. Different kinds of granular chains are investigated: monodisperse chains, tapered chains and stepped chains. Particular attention is paid to the dispersion effect, and the wave propagation in tapered chains, the interaction of two solitary waves in monodisperse chains, and the formation of solitary wave trains in stepped chains. We show that the main features of the wave propagation observed experimentally in these granular chains are very well reproduced. This proves that the considered multiple impact model and numerical scheme are able to encapsulate the main physical effects that occur in such multibody systems. [ABSTRACT FROM AUTHOR]

Consideration was given to the extragradient methods for solution of the variational inequalities and related problems. The present paper set itself as an object the theoretical substantiation of convergence of the two-step extragradient method intended for solution of the variational inequalities and carrying out computer experiments over some special problems with the aim of comparing the constructed method with the extragradient and gradient methods. [ABSTRACT FROM AUTHOR]

Delineation of drainage basins from a digital elevation model (DEM) has become a standard operation in a number of terrain analysis software packages, but limitations of the conventionally used techniques have become apparent. Firstly, the delineation methods make assumption of error-free data, which is an unreachable utopia even with modern sensor technology. Secondly, even though the computing capacity has increased dramatically during the last decades, sizes of geospatial data sets have increased simultaneously. Thus far, the typical problems arising when using uncertainty-aware geospatial analysis are 1) the computational complexity of the analysis and 2) memory allocation problems when large datasets are used. In this paper, we raise the question about the general need for developing scalable and uncertainty-aware algorithms for terrain analysis and propose improvements to the existing drainage basin calculation methods. The distributed uncertainty-aware catchment delineation methods with and without spatial partitioning of the DEM are introduced and the performance of the methods in different cases are compared. [ABSTRACT FROM AUTHOR]

Background: In a highly publicized joint report, the National Academy of Engineering and the Institute of Medicine recently recommended the systematic application of systems engineering approaches for reforming our health care delivery system. For this to happen, medical professionals and managers need to understand and appreciate the power that systems engineering concepts and tools can bring to redesigning and improving health care environments and practices.Objective: To present and discuss fundamental concepts and tools of systems engineering and important parallels between systems engineering, health services, and implementation research as it pertains to the care of complex patients.Design: An exploratory, qualitative review of systems engineering concepts and overview of ongoing applications of these concepts in the areas of hemodialysis, radiation therapy, and patient flow modeling.Results: In this paper, we describe systems engineering as the process of identifying the system of interest, choosing appropriate performance measures, selecting the best modeling tool, studying model properties and behavior under a variety of scenarios, and making design and operational decisions for implementation.Conclusions: We discuss challenges and opportunities for bringing people with systems engineering skills into health care. [ABSTRACT FROM AUTHOR]

This paper presents a general approach to solution of the complex simulation problem of spindle units (SUs) running on rolling bearings (ball bearings and roller bearings) and proves the necessity of making a complex analysis of their nonlinear tribo-mechanical properties at the development stage. For doing this, we apply SU beam analytical diagrams and develop a complex mathematical model of SUs, which incorporates theparticular models, e.g. elastic-deformation, dynamic and heat models, and the model of the bearing fatigue life. To facilitate practical analysis in design, we develop software and demonstrate its application by examples of the comparative analysis the typical structures of SUs. [ABSTRACT FROM AUTHOR]

This paper examines the probabilities of first marriage dissolution in Canada, using the marital history data collected from a national sample of women in their reproductive years. It is found that age at marriage, year of marriage, cohabitation before marriage, a premarital birth or conception, urban-rural place of residence, and religiosity are all significantly correlated with marriage dissolution. Religion and education, on the other hand, do not seem to affect the marriage dissolution probabilities when other factors are controlled. Canadian patterns are not too different from patterns in the United States. [ABSTRACT FROM AUTHOR]

This paper examines relationships among six social factors and infant mortality in California in 1978 and seeks to explain social differentials in terms of two intervening variables. Linked birth and infant death records are analyzed to test for interactions among the social factors and mortality and for causal linkages involving the intervening variables. Social factors are related to the risk of infant mortality in a conditional manner; significant interactions involve maternal age and both birth order and marital status, and race/ethnicity and both education and marital status. Birth weight and prenatal care are important intervening variables but do not fully explain the social differentials. [ABSTRACT FROM AUTHOR]

This paper develops and estimates an interactive contextual model of migration in Ilocos Norte, the Philippines. It focuses on how contextual features alter the effects of family class status and community development level on the family's migration decisions. The model estimates show a curvilinear relation between class status and migration, but the pattern differs in accordance with the prevalence of migration from the community in the past. In addition, the effects of socioeconomic development and agricultural commercialization patterns vary with context. These results demonstrate the importance of using interactive models for analyzing the contextual influences on migration. [ABSTRACT FROM AUTHOR]

This paper, analyzes movements among household types. Persons in one household may join another type. Correspondingly, a household's structure may change when someone joins it. Data are from the Panel Survey of Income Dynamics, spanning `1968-1980. The individuals followed in the survey generated spells analyzed with a multivariate competing risk hazard model. We develop a map of the flow among household types and of the economic and demographic profiles of individuals making the transitions. We find wide variability in the stability of household types and marked racial differences in the relative stability and pattern of destination choices. [ABSTRACT FROM AUTHOR]

This paper compares several methods of generating confidence intervals for forecasts of population size. Two rest on a demographic model for age-structured populations with stochastic fluctuations in vital rates. Two rest on empirical analyses of past forecasts of population sizes of Sweden at five-year intervals from 1780 to 1980 inclusive. Confidence intervals produced by the different methods vary substantially. The relative sizes differ in the various historical periods. The narrowest intervals offer a lower bound on uncertainty about the future. Procedures for estimating a range of confidence intervals are tentatively recommended. A major lesson is that finitely many observations of the past and incomplete theoretical understanding of the present and future can justify at best a range of confidence intervals for population projections. Uncertainty attaches not only to the point forecasts of future population, but also to the estimates of those forecasts' uncertainty. [ABSTRACT FROM AUTHOR]

In this paper, we model unmarried teenagers' decisions about their pregnancy outcome by considering that the teenager contrasts her expected utility (1) as a married mother, (2) as an unmarried mother, or (3) after abortion. We use cross-sectional data on 297 California teenagers aged 13-19 who were pregnant for the first time between 1972 and 1974. Both Anglo and Mexican-American girls are included. We find that pregnant girls who are eligible for or are receiving public assistance are more likely to give birth and remain unmarried. Teenagers with greater time values are more likely to choose abortion, and Mexican-American girls are more likely to carry their pregnancies to term. [ABSTRACT FROM AUTHOR]

This paper examines biases that may occur when models of couple behavior are estimated using one partner's report of own and of spouse's desired family size rather than independent reports obtained from both partners. When estimates of random measurement error are incorporated in a model of couple fertility expectations, proxy reports are valid indicators of spouse desires. In particular, there is little evidence that proxy reports are affected by systematic errors arising from projection of own beliefs onto the spouse. For desired family size, random measurement error in both proxy and self reports is of far greater concern than is systematic error. [ABSTRACT FROM AUTHOR]

This paper presents estimates of delayed childbearing and permanent childlessness in the United States and the determinants of those phenomena. The estimates are derived by fitting the Coale-McNeil marriage model to survey data on age at first birth and by letting the parameters of the model depend on covariates. Substantively, the results provide evidence that the low first birth fertility rates experienced in the 1970s were due to both delayed childbearing and to increasing levels of permanent childlessness. The results also indicate that (a) delayed childbearing is less prevalent among black women than among nonblack women; (b) education is an important determinant of delayed childbearing whose influence on this phenomenon seems to be increasing across cohorts; (c) education is positively associated with heterogeneity among women in their age at first birth; (d) the dispersion of age at first birth is increasing across cohorts; (e) race has an insignificant effect on childlessness; and (f) education is positively associated with childlessness, with the effect of education increasing and reaching strikingly high levels for the most recent cohorts. [ABSTRACT FROM AUTHOR]

Most research on married women's labor force participation relates characteristics of individual women to their probability of labor force participation. Some studies relate characteristics of geographic areas to average labor force participation rates in those areas, although these aggregate level analyses are usually gross tests of ideas about individual-level processes. Here we take a quintessentially sociological perspective and seek to understand how characteristics of geographic areas structure the relationship between properties of individual women and their probabilities of labor force participation. Our analysis has two steps. In step one, we fit individual-level probit models of married women's probability of labor force participation. A separate model is fitted in each of 409 areas using 1970 Census data, and the relationship between individual characteristics and labor force participation is found to vary substantially across areas. In step two, we attempt to explain areal variation in the effects of women's children on their labor force participation. We hypothesize that the effect of children on their mothers' labor force participation is a function of the cost and availability of childcare , and of the "convenience" of jobs for working mothers in the places where the mothers live. Measures of childcare cost, childcare availability and job convenience are developed. Weighted least squares analyses of probit coefficients from the first stage are, in general, very consistent with our findings, and suggest that the approach taken in this paper is likely to be a fruitful one for future studies. [ABSTRACT FROM AUTHOR]

Analyzing data from a fifteen-year follow-up survey of high school students originally surveyed in 1957-58 and resurveyed in 1973-74, this paper examines the effects of the timing of marriage and first birth on subsequent childspacing, holding constant the effects of other variables that may be sources of spuriousness. The results suggest that age at first marriage has a causal effect on the occurrence of a short first birth interval and that age at first marriage and premarital pregnancy interact in their effect on the occurrence of a short second birth interval. Age at first marriage has no causal effect on the spacing of the second birth for those whose first child was maritally conceived. The spacing of the first birth, however, appears to have a causal effect on the spacing of the second. [ABSTRACT FROM AUTHOR]