Assessing the quality of multilevel graph clustering

“Lifting up” a non-hierarchical approach to handle hierarchical clustering by iteratively applying the approach to hierarchically cluster a graph is a popular strategy. However, these lifted iterative strategies cannot reasonably guide the overall nesting process precisely because they fail to evaluate the very hierarchical character of the clustering they produce. In this study, we develop a criterion that can evaluate the quality of the subgraph hierarchy. The multilevel criterion we present and discuss in this paper generalizes a measure designed for a one-level (flat) graph clustering to take nesting of the clusters into account. We borrow ideas from standard techniques in algebraic combinatorics and exploit a variable $q$ to keep track of the depth of clusters at which edges occur. Our multilevel measure relies on a recursive definition involving variable $q$ outputting a one-variable polynomial. This paper examines archetypal examples as proofs-of-concept; these simple cases are useful in understanding how the multilevel measure actually works. We also apply this multilevel modularity to real world networks to demonstrate how it can be used to compare hierarchical clusterings of graphs.     

Synthesis and properties of chiral helical chromophore-functionalised polybinaphthalenes for second-order nonlinear optical applications

Chiral, helical, nonlinear optical polybinaphthalenes were prepared by covalent bonding of chromophores to the backbone of polybinaphthalenes via a Mitsunobu reaction. This was achieved in a two-step reaction, with the formation of a precursor polymer by a Suzuki coupling reaction, which was afterwards functionalised with chromophores. It was tried to achieve a chiral ordering of the chromophores by attaching them to a chiral, helical polymer backbone. Poled films of the polymers were measured for their second-harmonic generation effect and showed nonresonant nonlinear susceptibilities (χ_zzz⁽²⁾(0)) up to 10.6 pm/V.     

Comparison of visual and automated colorimeters—An international collaborative study

Color as a fundamental quality of edible oils has been determined primarily by visual comparison methods for many decades. The automatic colorimeters introduced recently made it possible to replace the manually operated visual color instrument, which requires experience to master and is often subject to operator variabilities. A previous study with an automatic colorimeter, Colourscan, to measure the colors of refined and refined bleached cottonseed oils showed good agreement (r ²=0.99) with visual color measurements by means of the Lovibond-AOCS Color Scale. The current work is to establish a broad-scale correlation between the automated colorimeter and visual color measurements. In this international effort, factory-processed refined and refined, bleached, deodorized (RBD) canola, corn, cottonseed, peanut, sunflower and soybean oils, as well as refined palm olein, RBD palm oil, and washed, dried, filtered and deodorized tallow were used. A total of 14 laboratories from the United States and Canada, and 16 laboratories from 12 countries outside of North America, participated in this collaborative study. The results of this study, with statistical analyses, are reported.     

Morphological,thermal, and mechanical properties of poly(ε‐caprolactone)/poly(ε‐caprolactone)‐grafted‐cellulose nanocrystals mats produced by electrospinning

Electrospun nanocomposites of poly(ε‐caprolactone) (PCL) incorporated with PCL‐grafted cellulose nanocrystals (PCL‐g‐CNC) were produced. PCL chains were grafted from cellulose nanocrystals (CNC) surface by ring‐opening polymerization. Grafting was confirmed by infrared spectroscopy (FTIR) and thermogravimetric analyses (TGA). The resulting PCL‐g‐CNC were then incorporated into a PCL matrix at various loadings. Homogeneous nanofibers with average diameter decreasing with the addition of PCL‐g‐CNC were observed by scanning electron microscopy (SEM). PCL‐g‐CNC domains incorporated into the PCL matrix were visualized by transmission electron microscopy (TEM). Thermal and mechanical properties of the mats were analyzed by differential scanning calorimetry (DSC), TGA and dynamic mechanical analysis (DMA). The addition of PCL‐g‐CNC into the PCL matrix caused changes in the thermal behavior and crystallinity of the electrospun fibers. Significant improvements in Young's modulus and in strain at break with increasing PCL‐g‐CNC loadings were found. These results highlighted the great potential of cellulose nanocrystals as a reinforcement phase in electrospun PCL mats, which can be used as biomedical materials. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43445.     

Well-conditioned model predictive control

Model-based predictive control is an advanced control strategy that uses a move suppression factor or constrained optimization methods for achieving satisfactory closed-loop dynamic responses of complex systems. While these approaches are suitable for many processes, they are formulated on the selection of certain parameters that are ambiguous and also computationally demanding which makes them less suited for tight control of fast processes. In this paper, a new dynamic matrix control (DMC) algorithm is proposed that reduces inherent ill-conditioning by allowing the process prediction time step to exceed the control time step. The main feature, that stands in contrast with current DMC approaches, is that the original open-loop data are used to evaluate a "shifting factor" m in the controller matrix where m replaces the move suppression coefficient. The new control algorithm is practically demonstrated on a fast reacting process with better control being realized in comparison with DMC using move suppression. The algorithm also gives improved closed-loop responses for control simulations on a multivariable nonlinear process having variable dead-time, and on other models found in the literature. The shifting factor m is generic and can be effectively applied for any control horizon.     

Using monte carlo simulation for accurate critical dimension metrology of super small isolated poly‐lines

With the reduction of critical dimensions (CD) of physical gate lines, standard methods for evaluating bottom CD from the scanning electron microscope (SEM) signal become inaccurate. The two peaks, originating from the line edges, merge into a single peak, and the correct position of the topographical top and bottom points is not clear. A general Monte Carlo simulation program, developed to model SEM signals, was used to analyze the signals emerging from ultra small silicon lines. By correlating the simulated signals with the features, we deduced the location of the top and bottom points. This analysis was done for lines with various CDs, sidewall angles, and corner rounding, as well as for different spot sizes. This work shows the feasibility of using SEM for measuring ultranarrow features and supply data for algorithm development.     

BiTE: a dynamic bi-level traffic engineering model for load balancing and energy efficiency in data center networks

Applied Intelligence - With the recent significant growth of virtualization and cloud services, the data center network (DCN) as the underlying infrastructure is more important. The increasing and...     

Analysis of diffusion in metals based on non-equilibrium thermodynamics

A general form of the first Fick law for diffusion in single-phase metallic alloys is obtained by the methods of non-equilibrium thermodynamics. Because the vacancies are treated as an independent component, the reactions for the creation of vacancies are considered. The electrons are also treated as a component, and therefore an internally generated electric field appears in the generalized equation, in addition to the usual externally applied electric field. Similarly, two types of temperature gradient are considered; consequently, even in nominally isothermal diffusion a gradient in temperature may exist. The power of an analysis based on non-equilibrium thermodynamics is shown by the fact that the resulting equations have produced solutions to three previously unresolved problems.     

The singularities and dynamics of a Stewart platform manipulator

The Stewart platform manipulator is a fully parallel kinematic linkage system that has major mechanical differences over typical serial link robots. Its closed kinematic chain and parallel linkage structure give it great rigidity and a high force-to-weight ratio. In this paper, based on the forward and inverse kinematic analysis, the Jacobian matrix and the dynamic equations of the six-degree-of-freedom Stewart platform are derived. The singularities of the Stewart platform are also studied. Four singular positions are proved and some other conditions under which the possible singular positions may occur are given. These results provide us with the necessary information to avoid passing through singular points. The dynamic equations in Cartesian space appear in a very simple form. Especially in some applications if there is no rotation about the fixed X-axis, then the inertia matrix reduces to a constant, diagonal matrix and the Coriolis and centrifugal matrix goes to zero, which makes the Stewart platform become a decoupled, linear system in Cartesian space.