Are the Chinese Saving for Old Age?

Worldwide, older people’s support used to be the adult children’s responsibility. In China, two generations after introducing the one-child policy in the late 70-ies, this becomes an increasingly demanding obligation. The Chinese government took the responsibility to mitigating old- age poverty risks and realized unprecedented progress in pension coverage. At the same time, the household savings increased to about 30 % of disposable income. Built on previous research on the politics of ageing, this study analyses households responses to the established governmental and firm pension programs as well as to the New Rural Pension Scheme (NRPS), introduced in 2009. The central question is: will participation in the established and new pension programs lead to higher current Chinese household expenditures and therefore to lower savings? The China Health and Retirement Longitudinal Study (CHARLS) dataset of 2011 offered the opportunity to study the influence of the recently introduced NRPS. We find that Chinese households with members between 45 and 60 years who expect future benefits of NRPS do not have higher expenditures than those not covered by NRPS. For the participants in the established, mostly urban pension programs a correlation was found with higher current expenditures (28 % more spending on basic needs, 80 % more on luxury) However, further analysis shows that this correlation cannot be interpreted as a causal relationship. This implies that coverage by pensions, be it in urban or rural programs, does not determine higher current expenditures and lower savings.     

Are some parts larger than others? Qualifying Hammerton's quantifiers

An investigation is reported in which people were asked to give verbal equivalents of percentages, and percentage equivalents of verbal statements. The results suggested that such statements and percentages could be ranked reasonably consistently, but that the ranking differed from that proposed by Hammerton in an earlier article in this journal.     

A heuristic algorithm for a supply chain׳s production-distribution planning

In this paper we consider the problem of planning the production and distribution in a supply chain. The situation consists in a set of distribution centers seeking to serve to a set of retailers; these distribution centers are supplied by a set of plants trying to minimize the operation and transportation costs. The problem is formulated as a bilevel mathematical problem where the upper level consists of deciding the amount of product sent from the distribution centers to the retailers trying to minimize the transportation costs and also by considering the costs of acquiring the products that come from the plants. Meanwhile the lower level consists in minimizing the plants׳ operations cost meeting the demand grouped in the distribution centers. We propose a heuristic algorithm based on Scatter Search that considers the Stackelberg׳s equilibrium; numerical tests show that our proposed algorithm improves the existing best known results in the literature.     

Are genetic algorithms useful for the parameter estimation of FM signals?

The estimation of polynomial-phase signals (PPSs) is a multiparameter problem, and the maximum likelihood (ML) optimization functions have numerous local optima, making the application of gradient techniques impossible. The common solution to this problem is based on the phase differentiation (PD) techniques that reduce the number of dimensions but, at the same time, reduce the accuracy and generate additional difficulties such as spurious components and error propagation. Here we show that genetic algorithms (GAs) can serve as a powerful alternative to the PD techniques. We investigate the limits of accuracy of the ML technique, and of some alternatives such as the high-order cubic phase function (HO-CPF) and high-order Wigner distribution (HO-WD). The ML approach combined with the proposed GA setup is limited up to the fifth-order PPS, which is not sufficient in many applications. However, the HO-CPF and HO-WD techniques coupled with the GA are able to accurately estimate phase parameters up to the tenth-order PPS. They significantly improve the accuracy with respect to the high-order ambiguity function (HAF) and product HAF (PHAF) and, for higher-order PPSs, they are much simpler and more efficient than the integrated generalized ambiguity function (IGAF).     

A methodology for the generation of planar models for multibody chain drives

To overcome the difficulty on building manually complex models of chain drives, this work proposes a comprehensive methodology to build multibody models of any general chain drive automatically from a minimal set of data. The proposed procedure also evaluates the initial positions and velocities of all components of the drive that are consistent with the kinematic joints or with the contact pairs used in the model. In this methodology, all links and sprockets are represented by rigid bodies connected to each other either by ideal or by clearance revolute joints. The clearance revolute joint contact is further extended to handle the contact between the chain rollers and the sprocket teeth exact profiles. A suitable cylindrical continuous contact law is applied to describe the interaction on all contact pairs. One of the complexities of the computational study of roller chain drives is the large number of bodies in the system and the dynamics of the successive engagement and disengagement of the rollers with the sprockets. Each time a roller engages or disengages with a sprocket tooth, the number of rigid bodies in contact changes. The search for the contact pairs is recognized as one of the most time consuming task in contact analysis. This work proposes a procedure to specify the contact pairs and their update during the dynamic analysis optimizing the computational efficiency of the contact search. The methodologies adopted result in a general computer program that is applied and demonstrated in a generic chain drive that can be used in industrial machines, vehicle engines or any other type of mechanical system.     

Delay-dependent criteria for the robust stability of systems with time-varying delay

The problem of delay-dependent robust stability for systems with time-varying delay has been considered. By using the S-procedure and the Park's inequality in the recent issue, a delay-dependent robust stability criterion which is less conservative than the previous results has been derived for time-delay systems with time-varying structured uncertainties. The same idea has also been easily extended to the systems with nonlinear perturbations. Numerical examples illustrated the effectiveness and the improvement of the proposed approach.     

Root-locus method for the Tsypkin and Jury and Lee criteria†

A method is developed for application of the Tsypkin criterion and the Jury and Lee stability criteria for certain classes of non-linear sampled data systems

The method, which uses root-locus techniques, is based on the root-locus interpretation of the Popov criterion for continuous data non-linear systems. This method was developed by Ramapriyan et al. (1966).     

Tuning for software analytics: Is it really necessary?

Context: Data miners have been widely used in software engineering to, say, generate defect predictors from static code measures. Such static code defect predictors perform well compared to manual methods, and they are easy to use and useful to use. But one of the “black arts” of data mining is setting the tunings that control the miner.Objective: We seek simple, automatic, and very effective method for finding those tunings.Method: For each experiment with different data sets (from open source JAVA systems), we ran differential evolution as an optimizer to explore the tuning space (as a first step) then tested the tunings using hold-out data.Results: Contrary to our prior expectations, we found these tunings were remarkably simple: it only required tens, not thousands, of attempts to obtain very good results. For example, when learning software defect predictors, this method can quickly find tunings that alter detection precision from 0% to 60%.Conclusion: Since (1) the improvements are so large, and (2) the tuning is so simple, we need to change standard methods in software analytics. At least for defect prediction, it is no longer enough to just run a data miner and present the result without conducting a tuning optimization study. The implication for other kinds of analytics is now an open and pressing issue.     

Are loss functions all the same?

In this letter, we investigate the impact of choosing different loss functions from the viewpoint of statistical learning theory. We introduce a convexity assumption, which is met by all loss functions commonly used in the literature, and study how the bound on the estimation error changes with the loss. We also derive a general result on the minimizer of the expected risk for a convex loss function in the case of classification. The main outcome of our analysis is that for classification, the hinge loss appears to be the loss of choice. Other things being equal, the hinge loss leads to a convergence rate practically indistinguishable from the logistic loss rate and much better than the square loss rate. Furthermore, if the hypothesis space is sufficiently rich, the bounds obtained for the hinge loss are not loosened by the thresholding stage.     

Are visual cortex maps optimized for coverage?

The elegant regularity of maps of variables such as ocular dominance, orientation, and spatial frequency in primary visual cortex has prompted many people to suggest that their structure could be explained by an optimization principle. Up to now, the standard way to test this hypothesis has been to generate artificial maps by optimizing a hypothesized objective function and then to compare these artificial maps with real maps using a variety of quantitative criteria. If the artificial maps are similar to the real maps, this provides some evidence that the real cortex may be optimizing a similar function to the one hypothesized. Recently, a more direct method has been proposed for testing whether real maps represent local optima of an objective function (Swindale, Shoham, Grinvald, Bonhoeffer, & Hübener, 2000). In this approach, the value of the hypothesized function is calculated for a real map, and then the real map is perturbed in certain ways and the function recalculated. If each of these perturbations leads to a worsening of the function, it is tempting to conclude that the real map is quite likely to represent a local optimum of that function. In this article, we argue that such perturbation results provide only weak evidence in favor of the optimization hypothesis.     

Are the available boiling heat transfer coefficients suitable for silicon microchannel heat sinks?

The typical MEMS fabrication of micro evaporators ensures the perfect smooth wall surface that is lack of nucleation sites, significantly decreasing the heat transfer coefficients compared with miniature evaporators fabricated using copper or stainless steel. In the present paper, we performed the boiling heat transfer experiment in silicon triangular microchannel heat sink over a wide parameter range for 102 runs. Acetone was used as the working fluid. The measured boiling heat transfer coefficients versus the local vapor mass qualities are compared with the classical Chen’s correlation and other correlations for macro and miniature capillary tubes. It is found that most of these correlations significantly over-predict the measured heat transfer coefficients. New correlations are given. There are many reasons for such deviations. The major reason is coming from the perfect smooth silicon surface that lowers the heat transfer performances. New theory is recommended for the silicon microchannel heat sink that should be different from metallic capillary tubes.     

Are we ready for cyberterrorist attacks?—Examining the role of individual resilience

This study measures individual resilience to cyberterrorist attacks on financial systems and explores the antecedents of resilience. The research model integrates the resilience literature with the fear appraisal literature to address individuals’ fears of cyberterrorist attacks on financial systems. The model is tested using data collected through an online survey. The results show that (1) community support and family financial management significantly increase resilience toward cyberterrorist attacks, and (2) resilience to and fear of cyberterrorist attacks significantly influence individuals’ behaviors in handling their finances. This research helps IT practitioners to develop strategies to build cyber resilience capacities among individuals and communities.     

Are isophotes and reflection lines the same?

Isophotes and reflection lines are standard tools for surface interrogation. We study the correlations between them. We show that isophotes and reflection lines are different (but not disjunct) classes of surface curves. Furthermore we introduce the concept of reflection circles as a generalization of isophotes and reflection lines. Reflection circles can be considered as the mirror images of a family of concentric circles on the surface. We show that reflection circles contain both isophotes and reflection lines as special cases.